Patent Application
20230340524
Mouse models have been used extensively to study human diseases in vivo to circumvent the complexity dealing with human patients. Nevertheless, murine models often inadequately recapitulate the human disease partly due to important differences between mouse and human immune systems (Hagai et al., 2018; Kanazawa, 2007; Mestas & Hughes, 2004; Williams, Flavell, & Eisenbarth, 2010). Thus, humanized mice, defined as mice with human immune system, could be an attractive alternative (Shultz, Brehm, Garcia-Martinez, & Greiner, 2012; Theocharides, Rongvaux, Fritsch, Flavell, & Manz, 2016; Victor Garcia, 2016; Zhang & Su, 2012). To this end immunodeficient mice lacking common gamma chain (γc) like NOD-SCID-Il 2γc−/− (NSG), or BALB/c-Rag2−/−-γc−/− (BRG) (Matsumura et al., 2003; Traggiai et al., 2004) can be humanized by transplantation of human CD34+ hematopoietic progenitor cells (HPCs). Based on the sources of T cells, the model can be further categorized into two types: (1) a model in which mature T cells are isolated from the donor of HPCs and adoptively transferred (Aspord et al., 2007; Pedroza-Gonzalez et al., 2011; Wu et al., 2014; Wu et al., 2018; Yu et al., 2008); in this case the T cells have been selected in human thymus; and (2) a model in which endogenous T cells are de novo generated from human CD34+ HPCs (Matsumura et al., 2003; Traggiai et al., 2004); in which case human T cells are selected in mouse thymus.
The present disclosure provides multiple improved immunodeficient mice generated primarily using CRISPR technology for one-step generation of animals carrying mutations (Table 1) (Wang et al., 2013). These models were generated to address limitations of the models discussed above. The biggest limitation of the first model in which mature T cells are isolated from the donor of HPCs and adoptively transferred is graft-versus-host disease; the biggest limitation of the second model in which endogenous T cells are de novo generated from human CD34+ HPCs is a limited number of T cells able to recognize human major histocompatibility complex (MHC). Furthermore, substantial limitations remain that hamper the use of humanized mice for advanced in vivo studies including: 1) incomplete development of a full range of hematopoietic lineages like neutrophils, erythrocytes, Langerhans cells (Shultz et al., 2012); 2) limited long-term engraftment, especially of myeloid cells, which leads to an imbalance between myeloid and lymphoid lineages over time (Audige et al., 2017); 3) insufficient support of the engraftment of adult CD34+ HPCs derived from blood or bone marrow, which hampers the feasibility of constructing fully autologous models where the tumor and the immune system are from the same patient (Saito et al., 2016); 4) insufficient colonization of non-lymphoid tissues (for example mucosal barriers) with both myeloid and lymphoid cells (Herndler-Brandstetter et al., 2017; Rongvaux et al., 2014); and last but not least maturation of human adaptive immunity in the context of mouse major histocompatibility complex (MHC).
The strategy used herein to improve humanized mice is based, at least in part, on the concept that improved development of human myeloid cells and specifically of human dendritic cells (DCs) will improve adaptive immunity. We approached this in a stepwise manner. Because DCs are critical for proper immune homeostasis and for the generation of adaptive immunity (Banchereau & Steinman, 1998), we started by creating the mouse Fms Related Receptor Tyrosine Kinase 3 (Flt3) knockout (KO) models to produce a more permissible environment for human DC development by the inhibition of mouse DCs. We then made human Interleukin 6 (IL6) knockin (KI), human lymphotoxin beta receptor (LTBR) KI and human thymic stromal lymphopoietin (TSLP) KI in the mouse Flt3 KO model and crossed existing NSG mice with transgenic (Tg) expression of human Stem Cell Factor (SCF), Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) and Interleukin 3 (IL3) (NSG-SGM3, SGM3) (Nicolini, Cashman, Hogge, Humphries, & Eaves, 2004; Wunderlich et al., 2010) in the mouse Flt3 KO model.
The mouse Flt3 KO models provided herein create space for human DCs and, by making the receptor ligand Flt3L available to human cells, improve the development of human myeloid cells upon transplant with human CD34+ HPCs. Moreover, the Flt3 KO models with additional human KI or Tg gene expression engrafted with human HPCs can generate human vaccine-specific antibodies including neutralizing antibodies against influenza virus. Overall, the strains of the present invention address existing limitation of humanized mouse model for translational immunology/immune-oncology studies.
Thus, some aspects of the present disclosure provide a non-obese diabetic (NOD) mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, and an inactivated mouse Flt3 allele. Further aspects of the present disclosure provide an NSG™ mouse comprising an inactivated mouse Flt3 allele. Further aspects of the present disclosure provide an NSG™ mouse comprising an inactivated mouse Flt3 allele.
Also provided herein are methods of producing an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, and an inactivated mouse Flt3 allele, methods of using the mouse as a model system, and methods of propagating the mouse.
Some aspects of the present disclosure provide an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, an inactivated mouse Flt3 allele, and a nucleic acid encoding human TSLP. Further aspects of the present disclosure provide an NSG™ mouse comprising an inactivated mouse Flt3 allele, and a nucleic acid encoding human TSLP.
Also provided herein are methods of producing an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, an inactivated mouse Flt3 allele, and a nucleic acid encoding human TSLP, methods of using the mouse as a model system, and methods of propagating the mouse.
Some aspects of the present disclosure provide an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, an inactivated mouse Flt3 allele, and a nucleic acid encoding human IL6. Further aspects of the present disclosure provide an NSG™ mouse comprising an inactivated mouse Flt3 allele, and a nucleic acid encoding human IL6.
Also provided herein are methods of producing an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, an inactivated mouse Flt3 allele, and a nucleic acid encoding human IL6, methods of using the mouse as a model system, and methods of propagating the mouse.
Some aspects of the present disclosure provide an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, an inactivated mouse Flt3 allele, and a nucleic acid encoding human LTBR. Further aspects of the present disclosure provide an NSG™ mouse comprising an inactivated mouse Flt3 allele, and a nucleic acid encoding human LTBR.
Also provided herein are methods of producing an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, an inactivated mouse Flt3 allele, and a nucleic acid encoding human LTBR, methods of using the mouse as a model system, and methods of propagating the mouse.
Some aspects of the present disclosure provide an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, an inactivated mouse Flt3 allele, a nucleic acid encoding human IL3; a nucleic acid encoding human GM-CSF; and a nucleic acid encoding human SCF. Further aspects of the present disclosure provide an NSG™ mouse comprising an inactivated mouse Flt3 allele, and a nucleic acid encoding human IL3, a nucleic acid encoding human GM-CSF, and a nucleic acid encoding human SF.
Also provided herein are methods of producing an NOD mouse comprising an inactivated mouse Prkdc allele, an inactivated mouse IL2rg allele, an inactivated mouse Flt3 allele, a nucleic acid encoding human IL3; a nucleic acid encoding human GM-CSF; and a nucleic acid encoding human SCF, methods of using the mouse as a model system, and methods of propagating the mouse.
Further aspects of the present disclosure provide cells obtained from any one of the mouse models described herein.
The present disclosure provides immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG™) mouse models that comprise an inactivated mouse Flt3 allele and, in some models, additional genetic modifications. The mouse models provided herein are useful, for example, for superior engraftment of diverse hematopoietic lineages and for immune-oncology, immunology and infectious disease studies.
Flt3 is a receptor important for development of the dendritic cells and monocytic lineages. Flt3L-Flt3 signaling is important for the development of various DC and monocytic lineages (Ding et al., 2014; Ginhoux et al., 2009; McKenna et al., 2000; Waskow et al., 2008) and it's role is further supported by the increase of circulating conventional (c)DCs and plasmacytoid (p)DCs after the administration of Flt3L in vivo in mice and humans (Karsunky, Merad, Cozzio, Weissman, & Manz, 2003; Maraskovsky et al., 1996; Pulendran et al., 2000). Knocking-out mouse Flt3 can lead to: (1) decrease in murine DCs and other myeloid cells; and (2) increase in the availability of mouse Flt3L (which can act via human receptor) to human cells, thereby improving the long-term development of human myeloid cells upon transplant with human CD34+ HPCs. The present disclosure, in some embodiments, uses a CRISPR/Cas system to generate Flt3 KO mice in an NSG™ background.
Thus, in some aspects, the present disclosure provides mouse models having a NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG™) background and further comprising an inactivated mouse Fit allele (referred to herein as NSGF mice). In some embodiments, the genotype of an NSGF mouse model is NSG™ Flt3em1Akp (see Example 1 for an exemplary method of generating the NSG™ Flt3em1Akp mouse).
Other aspects of the present disclosure provide mouse models having an NSG™ background and further comprising an inactivated mouse Flt3 allele and a nucleic acid encoding human IL6 in lieu of mouse Il6 (referred to herein as NSGF6 mice). In some embodiments, the genotype of an NSGF6 mouse model is NSG™ Flt3em1Akp Il6e1m(IL6)Akp (see Example 2 for an exemplary method of generating the NSG™ Flt3em1Akp Il6em1(IL6)Akp mouse).
Yet other aspects of the present disclosure provide mouse models having an NSG™ background and further comprising an inactivated mouse Flt3 allele and a nucleic acid encoding human TSLP in lieu of mouse Tslp (referred to herein as NSGFT mice). In some embodiments, the genotype of an NSGFT mouse model is NSG™ Flt3em1Akp Tslpem3(TSLP)Akp (see Example 3 for an exemplary method of generating the NSG™ Flt3em1Akp Tslpem3(TSLP)Akp mouse).
Still other aspects of the present disclosure provide mouse models having an NSG™ background and further comprising an inactivated mouse Flt3 allele and a nucleic acid encoding human LTBR in lieu of mouse Ltbr (referred to herein as NSGFL mice). In some embodiments, the genotype of an NSGFL mouse model is NSG™ Flt3em1Akp Ltbrem1(LTBR)Akp (see Example 4 for an exemplary method of generating the NSG™ Flt3em1Akp Ltbrem1(LTBR)Akp mouse).
Further aspects of the present disclosure provide mouse models having an NSG™ background and further comprising an inactivated mouse Flt3 allele and a nucleic acid encoding human IL3, GM-CSF, and SCF (referred to herein as SGM3F mice). In some embodiments, the genotype of an SGM3F mouse model is NSG™ Flt3em1Akp-Tg(Hu-CMV-IL3, CSF2, KITLG)1Eav/MloySzJ (see Example 5 for an exemplary method of generating the NSG™ Flt3em1Akp-Tg(Hu-CMV-IL3, CSF2, KITLG)1Eav/MloySzJ mouse).
The NSG™ mouse is an immunodeficient mouse that lacks mature T cells, B cells, and natural killer (NK) cells, is deficient in multiple cytokine signaling pathways, and has many defects in innate immunity (see, e.g., (Shultz, Ishikawa, & Greiner, 2007; Shultz et al., 2005; Shultz et al., 1995), each of which is incorporated herein by reference). The NSG™ mouse, derived from the non-obese diabetic (NOD) mouse strain NOD/ShiLtJ (see, e.g., (Makino et al., 1980), which is incorporated herein by reference), include the Prkdcscid mutation (also referred to as the “severe combined immunodeficiency” mutation or the “scid” mutation) and the Il2rgtm1Wjl targeted mutation. The Prkdcscid mutation is a loss-of-function mutation in the mouse homolog of the human PRKDC gene—this mutation essentially eliminates adaptive immunity (see, e.g., (Blunt et al., 1995; Greiner, Hesselton, & Shultz, 1998), each of which is incorporated herein by reference). The Il2rgtm1Wjl mutation is a null mutation in the gene encoding the interleukin 2 receptor gamma chain (IL2Rγ, homologous to IL2RG in humans), which blocks NK cell differentiation, thereby removing an obstacle that prevents the efficient engraftment of primary human cells (Cao et al., 1995; Greiner et al., 1998; Shultz et al., 2005), each of which is incorporated herein by reference). A loss-of-function mutation, as is known in the art, results in a gene product with little or no function. By comparison, a null mutation results in a gene product with no function. An inactivated allele may be a loss-of-function allele or a null allele.
An inactivated allele is an allele that does not produce a detectable level of a functional gene product (e.g., a functional protein). In some embodiments, an inactivated allele is not transcribed. In some embodiments, an inactivated allele does not encode a functional protein. Thus, a mouse comprising an inactivated mouse Flt3 allele does not produce a detectable level of functional FLT3. In some embodiments, a mouse comprising an inactivated mouse Flt3 allele does not produce any functional FLT3.
The mouse models provide herein (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mice, or any combination thereof) comprise a genomic modification that inactivates the mouse Flt3 allele. A modification, with respect to a nucleic acid, is any manipulation of the nucleic acid, relative to the corresponding wild-type nucleic acid (e.g., the naturally-occurring nucleic acid). A genomic modification is thus any manipulation of a nucleic acid in a genome, relative to the corresponding wild-type nucleic acid (e.g., the naturally-occurring nucleic acid) in the genome. Non-limiting examples of nucleic acid (e.g., genomic) modifications include deletions, insertions, “indels” (deletion and insertion), and substitutions (e.g., point mutations). In some embodiments, a deletion, insertion, indel, or other modification in a gene results in a frameshift mutation such that the gene no longer encodes a functional product (e.g., protein). Modifications also include chemical modifications, for example, chemical modifications of at least one nucleobase. Methods of nucleic acid modification, for example, those that result in gene inactivation, are known and include, without limitation, RNA interference, chemical modification, and gene editing (e.g., using recombinases or other programmable nuclease systems, e.g., CRISPR/Cas, TALENs, and/or ZFNs). In some embodiments, CRISPR/Cas gene editing is used to inactivate the mouse Flt3 allele, as described elsewhere herein. In some embodiments, a genomic modification (e.g., a deletion or an indel) is in a (at least one) region of the mouse Flt3 allele selected from coding regions, non-coding regions, and regulatory regions. In some embodiments, the genomic modification (e.g., a deletion or an indel) is a coding region of the mouse Flt3 allele. For example, the genomic modification (e.g., a deletion or an indel) may be in exon 3, or it may span exon 3 of the mouse Flt3 allele. In some embodiments, the genomic modification is a genomic deletion. For example, the mouse Flt3 allele may comprise a genomic deletion of nucleotide sequences in exon 3. In some embodiments, the nucleotide sequence of SEQ ID NO: 1 has been deleted from an inactivated mouse Flt3 allele. In some embodiments, an inactivated mouse Flt3 allele comprises the nucleotide sequence of SEQ ID NO: 1.
In some embodiments, the mouse models provided herein (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mice, or any combination thereof) do not express a detectable level of mouse FLT3. A detectable level of mouse FLT3 is any level of FLT3 protein detected using a standard protein detection assay, such as flow cytometry and/or an ELISA. In some embodiments, a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mice, or any combination thereof) expresses an undetectable level or a low level of mouse FLT3. For example, a mouse model may express less than 1,000 pg/ml mouse FLT3. In some embodiments, mouse model expresses less than 500 pg/ml mouse FLT3 or less than 100 pg/ml mouse FLT3. The mouse FLT3 receptor is also referred to as cluster of differentiation antigen CD135. Thus, in some embodiments, a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mice, or any combination thereof) does not comprise (there is an absence of) CD135+ multipotent progenitor cells.
Flt3 knockout mice, in some embodiments, are generated by CRISPR using Cas9 mRNA and a guide RNA (gRNA). In some embodiments, the gRNA (e.g., 5′-AAGTGCAGCTCGCCACCCCA-3′, SEQ ID NO: 5) targets exon 3 of mouse Flt3 of NSG™ mice (NOD.Cg-Prkdcscid Il2rgtm1Wjl; RRID:IMSR JAX:005557). The blastocysts derived from the injected embryos, in some embodiments, are transplanted into foster mothers and newborn pups are obtained. In some embodiments, mice carrying a null deletion are backcrossed to NSG™. F0 and F1 littermates may be tested for successful gene-knockout by PCR and Sanger sequencing, for example. For example, primers (5′-GGTACCAGCAGAGTTGGATAGC-3′, SEQ ID NO: 12) and (5′-ATCCCTTACACAGAAGCTGGAG-3′, SEQ ID NO: 13) may be used in a PCR reaction to detect the mouse Flt3 wildtype allele from mutant allele (Table 2). The WT allele yields a DNA fragment 799 bp in length, whereas the mutated allele generates a DNA fragment of 363 bp in length.
Knockin mouse models (KI mice) can be generated to modify a gene sequence, for example, by substituting the gene sequence with a transgene, or by adding a gene sequence that is not found within the locus. The NSGF6, NSGFT, NSGFL, and SGM3F mouse models provided herein include a knockin allele. They include an exogenous nucleic acid that has been introduced into the mouse genome.
A nucleic acid used as provided herein may be a DNA, an RNA, or a chimera of DNA and RNA. In some embodiments, a nucleic acid (e.g., DNA) comprises a gene encoding a particular protein of interest (e.g., IL6, TSLP, LTBR, IL3, GM-CSF, SCF, or any combination thereof). A gene is a distinct sequence of nucleotides, the order of which determines the order of monomers in a polynucleotide or polypeptide. A gene typically encodes a protein. A gene may be endogenous (occurring naturally in a host organism) or exogenous (transferred, naturally or through genetic engineering, to a host organism). An allele is one of two or more alternative forms of a gene that arise by mutation and are found at the same locus on a chromosome. A gene, in some embodiments, includes a promoter sequence, coding regions (e.g., exons), non-coding regions (e.g., introns), and regulatory regions (also referred to as regulatory sequences). As is known in the art, a promoter sequence is a DNA sequence at which transcription of a gene begins. Promoter sequences are typically located directly upstream of (at the 5′ end of) a transcription initiation site. An exon is a region of a gene that codes for amino acids. An intron (and other non-coding DNA) is a region of a gene that does not code for amino acids.
A mouse comprising a human gene is considered to comprise a human transgene. A transgene is a gene exogenous to a host organism. That is, a transgene is a gene that has been transferred, naturally or through genetic engineering, to a host organism. A transgene does not occur naturally in the host organism (the organism, e.g., mouse, comprising the transgene).
Methods of producing a knockin mouse model are described elsewhere herein.
The present disclosure provides mouse models having an NSG™ background and further comprising an inactivated mouse Flt3 allele and a nucleic acid encoding human IL6 in lieu of mouse Il6 (referred to herein as NSGF6 mice). In some embodiments, the genotype of an NSGF6 mouse model is NSG™ Flt3em1Akp Il6em1(IL6)Akp (see Example 2 for an exemplary method of generating the NSG™ Flt3em1Akp Il6em1(IL6)A kp mouse).
IL6 (e.g., NC_000007.1; chromosome:GRCh38:7:22725889-22732002) is a cytokine and growth factor that stimulates inflammation and the maturation of immune cells (e.g., B cells) by binding and activating the interleukin 6 receptor, alpha. IL6 is essential in HPC maintenance (Encabo, Mateu, Carbonell-Uberos, & Minana, 2003) and in the differentiation of activated B cells into antibody producing plasma cells (Jego et al., 2003; Nurieva et al., 2009). To improve the NSG-based humanized mice, human IL6 knockin mice were generated to replace the mouse ortholog in NSGF mice.
In some embodiments, the NSGF6 mice described herein comprise an inactivated mouse Flt3 allele and a nucleic acid encoding IL6. In some embodiments, the nucleic acid encodes human IL6. In some embodiments, the nucleic acid comprises a human IL6 transgene. In some embodiments, a transgene, such as a human IL6 transgene, is integrated into a mouse genome. In some embodiments, a human IL6 transgene comprises the nucleic acid sequence of SEQ ID NO: 2.
Human IL6 knockin mice, in some embodiments, are generated using a CRISPR/cas system. Cas9 mRNA, gRNAs targeting mouse Il6 and recombinant human IL6 DNA, for example, may be coinjected into fertilized NSGF oocytes (e.g., NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp). Human IL6, in some embodiments, is inserted into exon 1 and exon 5 via homologous recombination. In some embodiments, the resulting founders, carrying human IL6 are bred, for example, to NSGF mice for multiple (e.g., two generations), and are then interbred until all offspring are homozygous for the Il6 targeted mutation. Examples of primers that may be used for genotype by PCR reaction are listed in Table 2.
The present disclosure also provides mouse models having an NSG™ background and further comprising an inactivated mouse Flt3 allele and a nucleic acid encoding human TSLP in lieu of mouse Tslp (referred to herein as NSGFT mice). In some embodiments, the genotype of an NSGFT mouse model is NSG™ Flt3em1AkpTslpem3(TSLP)Akp (see Example 3 for an exemplary method of generating the NSG™ Flt3em1AkpTslpem3(TSLP)Akp mouse).
Thymic stromal lymphopoietin (TSLP) (e.g., NC_000005.10;
chromosome:GRCh38:5:111070080-111078026) is a species-specific cytokine and exhibits species-specific function (Hanabuchi, Watanabe, & Liu, 2012). Human TSLP induces proliferation of naïve T cells, drive Th2 differentiation, Tregs development (Hanabuchi et al., 2010; Ito et al., 2005; Lu et al., 2009). TSLP stimulates the production of immune cells (e.g., B cells and T cells) by binding and activating the heterodimeric receptor complex composed of the thymic stromal lymphopoietin receptor chain and the IL-7R alpha chain (see, e.g., (He & Geha, 2010)). TSLP is also important for the polarization of dendritic cells. In contrast to IL-7 which directly acts on CD4+ T cells, TSLP mediates T cell homeostasis indirectly through human DCs (Lu et al., 2009). To improve the T cell development and differentiation, human TSLP knockin mice were generated to replace mouse Tslp in NSGF mice.
In some embodiments, the NSGFT mice described herein comprise an inactivated mouse Flt3 allele and a nucleic acid encoding TSLP. In some embodiments, the nucleic acid encodes human TSLP. In some embodiments, the nucleic acid comprises a human TSLP transgene. In some embodiments, a transgene, such as a human TSLP transgene, is integrated into a mouse genome. In some embodiments, a human TSLP transgene comprises the nucleic acid sequence of SEQ ID NO: 3.
Human TSLP knockin mice, in some embodiments, are generated using a CRISPR/cas system. Cas9 mRNA, gRNAs targeting mouse Tslp and recombinant human TSLP DNA, for example, may be coinjected into fertilized NSGF oocytes (e.g., NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp). Human TSLP, in some embodiments, is inserted into exon 1 and exon 5 via homologous recombination. In some embodiments, the resulting founders, carrying human TSLP are bred, for example, to NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp mice, and are then interbred until all offspring are homozygous for the TSLP targeted mutation. Examples of primers that may be used for genotype by PCR reaction are listed in Table 2.
The present disclosure further provides mouse models having an NSG™ background and further comprising an inactivated mouse Flt3 allele and a nucleic acid encoding human LTBR in lieu of mouse Ltbr (referred to herein as NSGFL mice). In some embodiments, the genotype of an NSGFL mouse model is NSG™ Flt3em1Akp Ltbrem1(LTBR)Akp (see Example 4 for an exemplary method of generating the NSG™ Flt3em1Akp Ltbrem1(LTBR)Akp mouse).
Follicular dendritic cells (FDCs) are essential for the development of lymphoid follicles and B cell responses (Futterer, Mink, Luz, Kosco-Vilbois, & Pfeffer, 1998). PDGFRb+ Mfge8+ FDC precursors in the perivascular area of Rag2−/−-γc−/− mice could differentiated into mature FDCs upon the activation of lymphotoxin beta receptor (LTBR) (e.g., NC_000012.12; chromosome:GRCh38:12:6375160-6391571) through lymphocyte reconstitution (Krautler et al., 2012). Thus, human LTBR knockin mice were generated to replace mouse Ltbr in NSGF mice.
In some embodiments, the NSGFL mice described herein comprise an inactivated mouse Flt3 allele and a nucleic acid encoding LTBR. In some embodiments, the nucleic acid encodes human LTBR. In some embodiments, the nucleic acid comprises a human LTBR transgene. In some embodiments, a transgene, such as a human LTBR transgene, is integrated into a mouse genome. In some embodiments, a human LTBR transgene comprises the nucleic acid sequence of SEQ ID NO: 4.
Human LTBR knockin mice, in some embodiments, are generated using a CRISPR/cas system. Cas9 mRNA, sgRNAs targeting mouse Ltbr and synthetic human LTBR minigene (encodes NM_002342 with all Exon and intron 1 sequences followed by a bGHpA STOP cassette) flanked by 5′ and 3′ mouse Ltbr homology sequence, for example, may be coinjected into fertilized NSGF oocytes (e.g., NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp). Human LTBR, in some embodiments, is inserted into exon 1 and exon 2 via homologous recombination. In some embodiments, the resulting founders, carrying human LTBR are bred, for example, to NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp mice, and are then interbred until all offspring were homozygous for the LTBR targeted mutation. Examples of primers that may be used for genotype by PCR reaction were listed in Table 2.
Further still, the present disclosure provides mouse models having an NSG™ background and further comprising an inactivated mouse Flt3 allele and nucleic acids encoding human IL3, GM-CSF, and SCF (referred to herein as SGM3F mice). In some embodiments, the genotype of an SGM3F mouse model is NSG™ Flt3em1Akp-Tg(Hu-CMV-IL3, CSF2, KITLG)1Eav/MloySzJ (see Example 5 for an exemplary method of generating the NSG™ Flt3em1Akp-Tg(Hu-CMV-IL3, CSF2, KITLG)1Eav/MloySzJ Mouse).
A limited biologic cross-reactivity between murine and human cytokines and cytokine receptors constrains the development of the human innate immune system, especially monocyte, macrophages and neutrophils. Efforts have been made to express human cytokines either through transgenic or knock-in human genes (Rathinam et al., 2011; Rongvaux et al., 2014; Willinger et al., 2011). One such variant of immunodeficient mice is based on NSG mice with transgenic expression of human Stem Cell Factor (SCF), Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) and Interleukin (IL)-3 (NSG-SGM3, SGM3) (Nicolini et al., 2004; Wunderlich et al., 2010). IL3 (e.g., NC_000005.10; chromosome:GRCh38:5:132060655-132063204), GM-CSF (e.g., NC_000005.10; chromosome:GRCh38:5:132073789-132076170) and SCF (e.g., NC_000012.12; chromosome: GRCh38:12:88492793-88580851) are cytokines and growth factors that promote the proliferation of a broad range of hematopoietic cell types. Initial studies demonstrated that, when transplanted with hCD34+ HPCs, SGM3 mice efficiently support the development of human immune cells, especially the CD33+ myeloid cells as well as CD4+Foxp3+ regulatory T cells, as compared to non-transgenic counterparts (Billerbeck et al., 2011). To further boost myeloid development, Flt3 mutant mice (NSGF) and SGM3 mice were crossed to yield SGM3F mice.
Thus, the SGM3F mice described herein comprise an inactivated mouse Flt3 allele and a nucleic acid encoding IL3, a nucleic acid encoding GM-CSF, and a nucleic acid encoding SCF. In some embodiments, the SGM3F mice comprise a nucleic acid encoding human IL3, a nucleic acid encoding human GM-CSF, and a nucleic acid encoding human SCF. In some embodiments, the SGM3F mice comprise a human IL3 transgene, a human CSF2 transgene, and a human KITLG transgene. In some embodiments, a transgene, such as a human IL3, CSF2, and/or KITLG transgene, is integrated into a mouse genome. Human IL3, CSF2, and KITLG transgenes are described (Nicolini et al., 2004), incorporated by reference herein.
SGM3F mice, in some embodiments, are generated by crossing NSG-SGM3 mice (NOD.Cg-PrkdcscidIl2rgtm1Wjl Tg(CMV-IL3,CSF2,KITLG)1Eav/MloySzJ; RRID:IMSR JAX:013062) to NSGF mice and interbreeding until all offspring are homozygous. NSG-SGM3 mice carry three separate transgenes which were designed each carrying one of the human interleukin-3 (IL-3) gene, the human granulocyte/macrophage-stimulating factor (GM-CSF) gene, or human Steel factor (SF) gene. Expression of each gene is driven by a human cytomegalovirus promoter/enhancer sequence and is followed by a human growth hormone cassette and a polyadenylation (polyA) sequence (Nicolini et al., 2004). The transgenes were microinjected into fertilized C57BL/6×C3H/HeN oocytes. The resulting founders, carrying all three transgenes (3GS), in some embodiments, are backcrossed to BALB/c-scid/scid mice for several generations and subsequently backcrossed to NOD.CB17-Prkdcscid mice for multiple (e.g., at least 11) generations. These mice may then be bred to NSG mice (NOD.Cg-Prkdcscid Il2rgtm1Wjl; RRID:IMSR JAX: 005557), for example, and then interbred until all offspring are homozygous for 3GS and the IL2rg targeted mutation. The transgenic mice may be bred to NSG mice for at least one generation to establish NSG-SGM3 mice. NSGF mice may be generated, for example, using the CRISPR/cas system. Cas9 mRNA and sgRNAs targeting mouse Flt3, in some embodiments, are coinjected into fertilized NSG oocytes. The resulting founders, carrying Flt3 deletion may be bred to NSG mice, and then interbred until all offspring are homozygous for Flt3 targeted mutation.
The mouse models of the present disclosure (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof), in some embodiments, are used to support human CD34+ HSCs and development of a human innate immune system. The human immune system includes the innate immune system and the adaptive immune system. The innate immune system is responsible for recruiting immune cells to sites of infection, activation of the complement cascade, the identification and removal of foreign substances from the body by leukocytes, activation of the adaptive immune system, and acting as a physical and chemical barrier to infectious agents.
In some embodiments, a mouse model provided herein (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) is sublethally irradiated (e.g., 100-300 cGy) to kill resident mouse HSCs, and then the irradiated mouse is engrafted with human CD34+ HSCs (e.g., 50,000 to 200,000 HSCs) to initiate the development of a human innate immune system. Thus, in some embodiments, a mouse further comprises human CD34+ HSCs. Human CD34+ HSCs may be from any source including, but not limited to, human fetal liver, human umbilical cord blood, mobilized peripheral blood, and bone marrow. In some embodiments, human CD34+ HSCs are from human umbilical cord blood.
The differentiation of human CD34+ HSCs into divergent immune cells (e.g., T cells, B cells, dendritic cells) is a complex process in which successive developmental steps are regulated by multiple cytokines. This process can be monitored through cell surface antigens, such as cluster of differentiation (CD) antigens. CD45, for example, is expressed on the surface of HSCs, macrophages, monocytes, T cells, B cells, natural killer cells, and dendritic cells, thus can be used as a marker indicative of engraftment. On T cells, CD45 regulates T cell receptor signaling, cell growth, and cell differentiation. In some embodiments, a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) comprises human CD45+ cells. In some embodiments, a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) also exhibits engraftment of human CD45+ cells to tissues, but not limited to, in the lung, thymus, spleen, lymph nodes, and/or small intestine.
As CD45+ cells mature, they begin to express additional biomarkers, indicative of the various developmental stages and differentiating cell types. Developing T cells, for example, also express CD3, CD4, and CD8. As another example, developing myeloid cells express CD33+. A mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) herein, in some embodiments, comprises not only human CD45+ cells but also double positive human CD45+/CD3+ T cells as well as double positive human CD45+/CD33+ myeloid cells.
Thus, in some embodiments, a population of human CD45+ cells in a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) comprises human CD45+/CD3+ T cells. In some embodiments, the population of human CD45+ cells comprises an increased percentage of human CD45+/CD3+ T cells, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD3+ T cells in a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) is increased by at least 25%, relative to an NSG™ control mouse. For example, the percentage of human CD45+/CD3+ T cells in a mouse model may be increased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD3+ T cells in a mouse model is increased by at least 50%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD3+ T cells in a mouse model is increased by at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD3+ T cells in a mouse model is increased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse.
In some embodiments, a population of human CD45+ cells in a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) comprises human CD45+/CD33+ myeloid cells. In some embodiments, the population of human CD45+ cells comprise an increased percentage of human CD45+/CD33+ myeloid cells, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD33+ myeloid cells in a mouse model is increased by at least 25%, relative to an NSG™ control mouse. For example, the percentage of human CD45+/CD33+ myeloid cells in a mouse model may be increased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD33+ myeloid cells in a mouse model is increased by at least 50%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD33+ myeloid cells in a mouse model is increased by at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD33+ myeloid cells in a mouse model is increased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse.
In some embodiments, a population of human CD45+ cells in a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) comprises human CD45+/CD19+ B cells. In some embodiments, the population of human CD45+ cells comprises an decreased percentage of human CD45+/CD19+ B cells, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD19+ B cells in a mouse model is decreased by at least 25%, relative to an NSG™ control mouse. For example, the percentage of human CD45+/CD19+ B cells in a mouse model may be decreased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD19+ B cells in a mouse model is decreased by at least 50%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD19+ B cells in a mouse model is decreased by at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD45+/CD19+ B cells in a mouse model is decreased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse.
The mouse models provided herein (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof), surprisingly, are also capable of supporting engraftment of dendritic cells (e.g., plasmacytoid dendritic cells and myeloid dendritic cells), natural killer cells, and monocyte-derived macrophages (monocyte macrophages). Plasmacytoid dendritic cells (pDCs) secrete high levels of interferon alpha; myeloid dendritic cells (mDCs) secrete interleukin 12, interleukin 6, tumor necrosis factor, and chemokines; natural killer cells destroy damaged host cells, such as tumor cells and virus-infected cells; and macrophages consume substantial numbers of bacteria or other cells or microbes.
In some embodiments, a mouse model provided herein (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) comprises an increased percentage of human CD14+ monocytes or macrophages, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD14+ monocytes or macrophages in a mouse model is increased by at least 25%, relative to an NSG™ control mouse. For example, the percentage of human CD14+ monocytes or macrophages in a mouse model may be increased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD14+ monocytes or macrophages in a mouse model is increased by at least 50%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD14+ monocytes or macrophages in a mouse model is increased by at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD14+ monocytes or macrophages in a mouse model is increased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse.
In some embodiments, an SGM3F mouse comprises an increased percentage of human CD66b+ cells, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human CD66b+ cells in the SGM3F mouse is increased by at least 25%, relative to an NSG™ control mouse and/or an NSGF control mouse. For example, the percentage of human CD66b+ cells in the NSG™ SGM3F mouse may be increased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human CD66b+ cells in the SGM3F mouse is increased by at least 50%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human CD11C+ HLA-DR+ myeloid dendritic cells in the SGM3F mouse is increased by at least 100%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human CD66b+ cells in the SGM3F mouse is increased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, an SGM3F mouse comprises an increased percentage of human CD11c+ myeloid dendritic cells, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human CD11c+ HLA-DR+ myeloid dendritic cells in the SGM3F mouse is increased by at least 25%, relative to an NSG™ control mouse and/or an NSGF control mouse. For example, the percentage of human CD11c+ HLA-DR+ myeloid dendritic cells in the NSG™ SGM3F mouse may be increased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human CD11c HLA-DR+ myeloid dendritic cells in the SGM3F mouse is increased by at least 50%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human CD11c+ HLA-DR+ myeloid dendritic cells in the SGM3F mouse is increased by at least 100%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human CD11c+ HLA-DR+ myeloid dendritic cells in the SGM3F mouse is increased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse and/or an NSGF control mouse.
In some embodiments, an NSGF mouse comprises an increased percentage of human CD303+ plasmacytoid dendritic cells, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD303+ plasmacytoid dendritic cells in the NSGF mouse is increased by at least 25%, relative to an NSG™ control mouse. For example, the percentage of human CD303+ plasmacytoid dendritic cells in the NSGF mouse may be increased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD303+ plasmacytoid dendritic cells in the NSGF mouse is increased by at least 50%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD303+ plasmacytoid dendritic cells in the NSGF mouse is increased by at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human CD303+ plasmacytoid dendritic cells in the NSGF mouse is increased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse.
In some embodiments, an SGM3F mouse comprises an increased percentage of human proportion of CCR7− effector T cells, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human proportion of CCR7− effector T cells in the SGM3F mouse is increased by at least 25%, relative to an NSG™ control mouse and/or an NSGF control mouse. For example, the percentage of human proportion of CCR7− effector T cells in the NSG™ SGM3F mouse may be increased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human proportion of CCR7− effector T cells in the SGM3F mouse is increased by at least 50%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of human proportion of CCR7− effector T cells in the SGM3F mouse is increased by at least 100%, relative to an NSG™ control mouse. In some embodiments, the percentage of human proportion of CCR7− effector T cells in the SGM3F mouse is increased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse and/or an NSGF control mouse.
In some embodiments, an SGM3F mouse comprises an increased percentage of total human IgG, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of total human IgG in the SGM3F mouse is increased by at least 25%, relative to an NSG™ control mouse and/or an NSGF control mouse. For example, the percentage of total human IgG in the NSG™ SGM3F mouse may be increased by at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 100%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of total human IgG in the SGM3F mouse is increased by at least 50%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of total human IgG in the SGM3F mouse is increased by at least 100%, relative to an NSG™ control mouse and/or an NSGF control mouse. In some embodiments, the percentage of total human IgG in the SGM3F mouse is increased by 25%-100%, 25%-75%, 25%-50%, 50%-100%, 50%-75%, or 75%-100%, relative to an NSG™ control mouse and/or an NSGF control mouse.
In some embodiments, an SGM3F mouse comprises a significant functional improvement of the human immune system relative to a SGM3 control mouse. For example, an SGM3F mouse may comprise increased specific TgG to KLH following vaccination with alum-adjuvanted Tdap/KLH vaccine IP/SC relative to a SGM3 control mouse. In some embodiments, an SGM3F mouse comprises increased specific IgG to Fluzone following vaccination with Fluzone IV/IP relative to a SGM3 control mouse. In some embodiments, an SGM3F mouse comprises neutralizing antibody to H1N1 FluA/Cal9 virus, but not to influenza B virus as measured by hemagglutination inhibition assay relative to a SGM3 control mouse.
In some embodiments, an NSGF mouse of the present disclosure is used to support human hematopoietic cell engraftment and human myelopoiesis.
In some embodiments, an NSGF6 mouse of the present disclosure is used to support human hematopoietic cell engraftment, human myelopoiesis, and human lymphopoiesis.
In some embodiments, an NSGFT mouse of the present disclosure is used to support human hematopoietic cell engraftment, human myelopoiesis, and human lymphopoiesis.
In some embodiments, an NSGFL mouse of the present disclosure, in some embodiments, is used to support the development of human lymphoid tissue, particularly the adaptive immune response and germinal center formation.
The SGM3F mouse of the present disclosure, in some embodiments, is used to support engraftment of myeloid lineages and regulatory T cell populations.
Provided herein, in some aspects, are methods of producing a transgenic animal that expresses human IL6, human TSLP, human LTBR, human IL3, human GM-CSF, human SCF, or any combination thereof. A transgenic animal, herein, refers to an animal that has a foreign (exogenous) nucleic acid (e.g., transgene) inserted into (integrated into) its genome. In some embodiments, the transgenic animal is a transgenic rodent, such as a mouse or a rat. In some embodiments, the transgenic animal is a mouse. Three conventional methods used for the production of transgenic animals include DNA microinjection (Gordon & Ruddle, 1981), incorporated herein by reference), embryonic stem cell-mediated gene transfer (Gossler, Doetschman, Korn, Serfling, & Kemler, 1986), incorporated herein by reference) and retrovirus-mediated gene transfer (Jaenisch, 1976), incorporated herein by reference), any of which may be used as provided herein. Electroporation may also be used to produce transgenic mice (see, e.g., WO 2016/054032 and WO 2017/124086, each of which is incorporated herein by reference).
A nucleic acid encoding human IL6, human TSLP, human LTBR, human IL3, human GM-CSF, human SCF, or any combination thereof, in some embodiments, comprises a transgene, for example, a transgene that comprises a promoter (e.g., a constitutively active promoter) operably linked to a nucleotide sequence encoding human IL6, human TSLP, human LTBR, human IL3, human GM-CSF, human SCF, or any combination thereof. In some embodiments, a nucleic acid encoding human IL6, human TSLP, human LTBR, human IL3, human GM-CSF, human SCF, or any combination thereof used to produce a transgenic animal (e.g., mouse) is present on an vector, such as a plasmid, a bacterial artificial chromosome (BAC), or a yeast artificial chromosome (YAC), which is delivered, for example, to the pronucleus/nucleus of a fertilized embryo where the nucleic acid randomly integrates into the animal genome. In some embodiments, the fertilized embryo is a single-cell embryo (e.g., a zygote). In some embodiments, the fertilized embryo is a multi-cell embryo (e.g., a developmental stage following a zygote, such as a blastocyst). In some embodiments, the nucleic acid (e.g., carried on a BAC) is delivered to a fertilized embryo of an NSG™ mouse to produce a mouse model of the present disclosure (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof). Following injection of the fertilized embryo, the fertilized embryo may be transferred to a pseudopregnant female, which subsequently gives birth to offspring comprising the nucleic acid encoding human IL6, human TSLP, human LTBR, human IL3, human GM-CSF, human SCF, or any combination thereof. The presence or absence of the nucleic acid encoding human IL6, human TSLP, human LTBR, human IL3, human GM-CSF, human SCF, or any combination thereof may be confirmed, for example, using any number of genotyping methods (e.g., sequencing and/or genomic PCR).
In some embodiments, a CRISPR system is used to generate deletion in specific target sites encoding endogenous mouse 116, mouse Tslp, or mouse Ltbr of a mouse model provided herein (e.g., the NSGF, NSGF6, NSGFT, NSGFL, mouse model, or any combination thereof). By coinjecting donor DNA encoding human IL6, human TSLP, or human LTBR, gene editing is achieved precisely by homology-directed repair (See, e.g. (Yang et al., 2013), which is incorporated by reference herein). For example, Cas9 mRNA or protein, one or multiple guide RNAs (gRNAs) and donor plasmid template encompassing the human IL6 gene flanked by 5′ and 3′ mouse 116 homology sequence can be injected directly into mouse embryos to generate precise genomic edits into a 116 gene. Mice that develop from these embryos can be genotyped or sequenced to determine if they carry the desired transgene, and those that do may be bred to confirm germline transmission.
Also provided herein are methods of inactivating an endogenous Flt3 allele. In some embodiments, an endogenous Flt3 allele is inactivated in a transgenic animal. In some embodiments, a gene/genome editing method is used for gene (allele) inactivation. Engineered nuclease-based gene editing systems that may be used as provided herein include, for example, clustered regularly interspaced short palindromic repeat (CRISPR) systems, zinc-finger nucleases (ZFNs), and transcription activator-like effector nucleases (TALENs). See, e.g., (Carroll, 2011; Gaj, Gersbach, & Barbas, 2013; Joung & Sander, 2013), each of which is incorporated by reference herein.
In some embodiments, a CRISPR system is used to inactivate an endogenous Flt3 allele of a mouse model provided herein (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof). See, e.g., (Harms et al., 2014; Inui et al., 2014), each of which are incorporated by reference herein). For example, Cas9 mRNA or protein and one or multiple guide RNAs (gRNAs) can be injected directly into mouse embryos to generate precise genomic edits into a Flt3 gene. Mice that develop from these embryos can be genotyped or sequenced to determine if they carry the desired mutation(s), and those that do may be bred to confirm germline transmission.
The CRISPR/Cas system is a naturally occurring defense mechanism in prokaryotes that has been repurposed as a RNA-guided-DNA-targeting platform for gene editing. Engineered CRISPR systems contain two main components: a guide RNA (gRNA) and a CRISPR-associated endonuclease (e.g., Cas protein). The gRNA is a short synthetic RNA composed of a scaffold sequence for nuclease-binding and a user-defined nucleotide spacer (e.g., ˜15-25 nucleotides, or ˜20 nucleotides) that defines the genomic target to be modified. Thus, one can change the genomic target of the Cas protein by simply changing the target sequence present in the gRNA. In some embodiments, the CRISPR-associated endonuclease is selected from Cas9, Cpf1, C2c1, and C2c3. In some embodiments, the Cas nuclease is Cas9.
A guide RNA comprises at least a spacer sequence that hybridizes to (binds to) a target nucleic acid sequence and a CRISPR repeat sequence that binds the endonuclease and guides the endonuclease to the target nucleic acid sequence. As is understood by the person of ordinary skill in the art, each gRNA is designed to include a spacer sequence complementary to its genomic target sequence (e.g., a region of the Flt3 allele). See, e.g., (Deltcheva et al., 2011; 25 Jinek et al., 2012), each of which is incorporated by reference herein. In some embodiments, a gRNA used in the methods provided herein binds to a region (e.g., exon 3) of a mouse Flt3 allele. In some embodiments, the gRNA that binds to a region of a mouse Flt3 allele comprises the nucleotide sequence of 5′-AAGTGCAGCTCGCCACCCCA-3′ (SEQ ID NO: 5). In some embodiments, gRNAs used in the methods provided herein binds to regions (e.g., exon 1 and exon 5) of a mouse Il6 allele. In some embodiments, the gRNAs that binds to regions of a mouse 116 allele comprises the nucleotide sequences of 5′-AGGAACTTCATAGCGGTTTC-3′ (SEQ ID NO: 6) and 5′-ATGCTTAGGCATAACGCACT-3′ (SEQ ID NO: 7). In some embodiments, gRNAs used in the methods provided herein binds to regions (e.g., exon 1 and exon 5) of a mouse Tslp allele. In some embodiments, the gRNAs that binds to regions of a mouse Tslp allele comprises the nucleotide sequences of 5′-CCACGTTCAGGCGACAGCAT-3′ (SEQ ID NO: 8) and 5′-TTATTCTGGAGATTGCATGA-3′ (SEQ ID NO: 9). In some embodiments, gRNAs used in the methods provided herein binds to regions (e.g., exon 1 and exon 2) of a mouse Ltbr allele. In some embodiments, the gRNAs that binds to regions of a mouse Ltbr allele comprises the nucleotide sequences of 5′-GCTCGGCTGACCAGACCGGG-3′(SEQ ID NO: 10) and 5′-GAGCCACTGTTCTCACCTGG-3′ (SEQ ID NO: 11).
The mouse models provided herein (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) may be used for any number of applications. For example, a mouse model may be used to test how a particular agent (e.g., therapeutic agent) or medical procedure (e.g., tissue transplantation) impacts the human innate immune system (e.g., human innate immune cell responses) and human adaptive immune system (e.g., antibody response).
In some embodiments, a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) is used to evaluate an effect of an agent on human innate immune system development. Thus, provided herein are methods that comprise administering an agent to a mouse model, and evaluating an effect of the agent on human innate immune system development in the mouse. Effects of an agent may be evaluated, for example, by measuring a human innate immune cell (e.g., T cell and/or dendritic cell) response (e.g., cell death, cell signaling, cell proliferation, etc.) and human adaptive immune response (e.g., antibody production). Non-limiting examples of agents include therapeutic agents, such as anti-cancer agents and anti-inflammatory agents, and prophylactic agents, such as immunogenic compositions (e.g., vaccines).
In other embodiments, a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) is used to evaluate an immunotherapeutic response to a human tumor. Thus, provided herein are methods that comprise administering an agent to a mouse model that has a human tumor, and evaluating an effect of the agent on the human innate immune system and/or on the tumor in the mouse. Effects of an agent may be evaluated by measuring a human innate immune cell (e.g., T cell and/or dendritic cell) response, human adaptive immune response (e.g., antibody production) and/or tumor cell response (e.g., cell death, cell signaling, cell proliferation, etc.). In some embodiments, the agent is an anti-cancer agent.
In yet other embodiments, a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) is used to evaluate a human immune response to an infectious microorganism. Thus, provided herein are methods that comprise exposing a mouse model to an infectious microorganism (e.g., bacteria and/or virus), and evaluating an effect of the infectious microorganism on the human immune response. Effects of an infectious microorganism may be evaluated by measuring a human innate immune cell (e.g., T cell and/or dendritic cell) response (e.g., cell death, cell signaling, cell proliferation, etc.) and human adaptive immune response (e.g., antibody production). These methods may further comprise administering a drug or an anti-microbial agent (e.g., an anti-bacterial agent or an anti-viral agent) to the mouse and evaluating an effect of the drug or anti-microbial agent on the infectious microorganism.
In still further embodiments, a mouse model (e.g., the NSGF, NSGF6, NSGFT, NSGFL, or SGM3F mouse model, or any combination thereof) is used to evaluate a human immune response to tissue transplantation. Thus, provided herein are methods that comprise transplanting tissue (e.g., allogeneic tissue) to a mouse model and evaluating an effect of the transplanted tissue on the human innate immune response. Effects of a transplanted tissue may be evaluated by measuring a human innate immune cell (e.g., T cell and/or dendritic cell) response (e.g., cell death, cell signaling, cell proliferation, etc.) and human adaptive immune response (e.g., antibody production) to the transplanted tissue.
Mouse Flt3 KO creates space for human DCs and, by making the receptor ligand Flt3L available to human cells, improves the development of human myeloid cells upon transplant with human CD34+ HPCs. Side-by-side comparison of the SGM3 mice and the NSGF mice generated herein revealed some similarities but also substantial differences between the two strains, for example: (1) NSGF mice support human hematopoiesis upon transplant of cord blood as well as adult bone marrow HPCs; (2) NSGF mice support differentiation of human DC subsets; and (3) hSGM3 mice can generate human antibody titers. These results motivated us to cross the two strains to generate a novel strain, SGM3F. hSGM3F mice therefore represent a step towards an improved model because our studies show that these mice support the generation of antibody responses upon vaccination—an outcome that can be attributed to human myeloid cells. In line with this, we generated multiple improved immunodeficient mice using CRISPR technology. By crossing each strain of mice, we aim to combine various the features of the human transgenes to obtain mouse models with the capacity to develop various subsets of human immune cells and to mount specific immune response upon reconstitution with human HPCs.
Flt3 is a receptor important for development of the dendritic cells and monocytic lineages. Flt3L-Flt3 signaling is important for the development of various DC and monocytic lineages (Ding et al., 2014; Ginhoux et al., 2009; McKenna et al., 2000; Waskow et al., 2008) and it's role is further supported by the increase of circulating conventional (c)DCs and plasmacytoid (p)DCs after the administration of Flt3L in vivo in mice and humans (Karsunky et al., 2003; Maraskovsky et al., 1996; Pulendran et al., 2000). Knocking-out mouse Flt3 can lead to: 1. decrease in murine DCs and other myeloid cells; and 2. increase in the availability of mouse Flt3L (which can act via human receptor) to human cells, thereby improving the long-term development of human myeloid cells upon transplant with human CD34+ HPCs. Thus, we used CRISPR/Cas system to generate a Flt3 KO mouse in NSG background. Founder mice carrying a chromosomal deletion at the exon 3 were backcross to NSG and inbred to obtain homozygous Flt3−/− allele (
One question was whether deletion of mouse DCs will improve human engraftment and generate “space” for human DCs. To this end, sublethally irradiated NSGF mice were transplanted with 1×105 fetal liver CD34+ HPCs, and the engraftment of human cells was measured in the blood at different time points after transplantation (
Generation of Mouse Model: Mouse Flt3 knockout mice (NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp) were generated by CRISPR using Cas9 mRNA and sgRNAs (5′-AAGTGCAGCTCGCCACCCCA-3′, SEQ ID NO: 5) targeting exon 3 of mouse Flt3 in fertilized eggs of NSG mice (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ; RRID:JMSR JAX:005557). The blastocysts derived from the injected embryos were transplanted into foster mothers and newborn pups were obtained. Mice carrying a null deletion were backcrossed to NSG. F0 and F1 littermates were tail tipping and tested for successful gene-knockout by PCR and Sanger sequencing. Forward primer (5′-GGTACCAGCAGAGTTGGATAGC-3′, SEQ ID NO: 12) and reverse primers (5′-ATCCCTTACACAGAAGCTGGAG-3′, SEQ ID NO: 13) were used in a PCR reaction to detect the mouse Flt3 wildtype (WT) allele from mutant allele (Table 2). The WT allele yields a DNA fragment 799 bp in length, whereas the mutated allele generates a DNA fragment of 363 bp in length.
IL6 is essential in HPC maintenance (Encabo, Mateu, Carbonell-Uberos, & Minana, 2003) and in the differentiation of activated B cells into antibody producing plasma cells (Jego et al., 2003; Nurieva et al., 2009). To improve the current NSG-based humanized mice, we generated human IL6 knockin that replaces mouse ortholog in NSGF mice. To this end, we used CRISPR-Cas9 gene targeting in zygotes using Cas9 mRNA, sgRNAs flanking the start codon and stop codon in the mouse Il6 gene and donor plasmid template encompassing 4,308 bp of the human IL6 gene (from the start to stop codons, retaining all exon/intron sequences) flanked by 5′ and 3′ mouse 116 homology sequence. Potential founder mice were selected first with a PCR assay designed specifically against intron 3 and 5 region of human IL6. To determine whether human IL6 was correctly targeted into the murine Il6 locus, we developed long-range PCR assays targeting 5′ and 3′ junctions (with one primer anchored in the mouse genome but outside the donor plasmid homology arms and the other primer anchored within the human IL6 gene) and full-length sequence between two homology arms (expected 8.4 kb in KI, 10.5 kb in wildtype mice) (
Generation of Mouse Model: Human IL6 knockin mice (NOD.Cg-PrkdcscidIl2rgtmWjl-Flt3em1AkpIl6em1(IL6)Akp) were generated using CRISPR/cas system. Cas9 mRNA, sgRNAs targeting mouse 116 (5′-AGGAACTTCATAGCGGTTTC-3′, SEQ ID NO: 6 and 5′-ATGCTTAGGCATAACGCACT-3′, SEQ ID NO: 7) and recombinant human IL6 DNA were coinjected into fertilized NSGF oocytes (NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp). Human IL6 was inserted into exon 1 and exon 5 via homologous recombination. The resulting founders, carrying human IL6 were bred to NSGF mice for two generations, and were then interbred until all offspring were homozygous for Il6 targeted mutation. Primer used for genotype by PCR reaction were listed in Table 2.
Thymic stromal lymphopoietin (TSLP) is a species-specific cytokine and exhibits species-specific function (Hanabuchi, Watanabe, & Liu, 2012). Human TSLP induces proliferation of naïve T cells, drive Th2 differentiation, Tregs development (Hanabuchi et al., 2010; Ito et al., 2005; Lu et al., 2009). In contrast to IL-7 which directly acts on CD4+ T cells, TSLP mediates T cell homeostasis indirectly through human DCs (Lu et al., 2009). To improve the T cell development and differentiation, we generated human TSLP knockin to replace mouse Tslp in NSGF mice. Using CRISPR/cas system, fertilized NSGF oocytes were injected with Cas9 mRNA, sgRNAs flanking the start codon and stop codon in the mouse Tslp gene and donor plasmid template encompassing human TSLP gene (from the start to stop codons, retaining all exon/intron sequences) flanked by 5′ and 3′ mouse Tslp homology sequence. Human TSLP was inserted into exon 1 and exon 5 via homologous recombination. To determine whether human TSLP was correctly targeted into the murine Tslp locus, we developed long-range PCR assays targeting 5′ and 3′ junctions (with one primer anchored in the mouse genome but outside the donor plasmid homology arms and the other primer anchored within the human TSLP gene. Sequencing of these PCR products confirmed proper targeting of human TSLP. Two founder mice with human TSLP KI (SEQ ID NO: 3) were identified (
Generation of Mouse Model: Human TSLP knockin mice (NOD.Cg-PrkdcscidIl2rgtm1Wjl-Flt3em1AkpTslpem3(TSLP)Akp) were generated using CRISPR/cas system. Cas9 mRNA, sgRNAs targeting mouse Tslp (5′-CCACGTTCAGGCGACAGCAT-3′, SEQ ID NO: 8 and 5′-TTATTCTGGAGATTGCATGA-3′, SEQ ID NO: 9) and recombinant human TSLP DNA were coinjected into fertilized NSGF oocytes (NOD.Cg-Prkdcscid Il2rgtm1WjlFlt3em1Akp). Human TSLP was inserted into exon 1 and exon 5 via homologous recombination. The resulting founders, carrying human TSLP were bred to NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp mice, and were then interbred until all offspring were homozygous for TSLP targeted mutation. Primer used for genotype by PCR reaction were listed in Table 2.
Follicular dendritic cells (FDCs) are essential for the development of lymphoid follicles and B cell responses (Futterer et al., 1998). PDGFRb+ Mfge8+FDC precursors in the perivascular area of Rag2−/−-γc−/− mice could differentiated into mature FDCs upon the activation of lymphotoxin beta receptor (LTBR) through lymphocyte reconstitution (Krautler et al., 2012). Thus, we generated human LTBR knockin to replace mouse Ltbr in NSGF mice. To this end, we used CRISPR-Cas9 gene targeting in zygotes using Cas9 mRNA, sgRNAs flanking Exon 1 and 2 of mouse Ltbr gene and donor plasmid template encompassing synthetic human LTBR minigene (encodes NM_002342 with all Exon and intron 1 sequences followed by a bGHpA STOP cassette) flanked by 5′ and 3′ mouse Ltbr homology sequence (
Generation of Mouse Model: Human LTBR knockin mice (NOD.Cg-Prkdcscid Il2rgtm1Wjl-Flt3em1Akp-Ltbrem1(LTBR)Akp) were generated using CRISPR/cas system. Cas9 mRNA, sgRNAs targeting mouse Ltbr (5′-GCTCGGCTGACCAGACCGGG-3′, SEQ ID NO: 10 and 5′-GAGCCACTGTTCTCACCTGG-3′, SEQ ID NO: 11) and synthetic human LTBR minigene (encodes NM_002342 with all Exon and intron 1 sequences followed by a bGHpA STOP cassette) flanked by 5′ and 3′ mouse Ltbr homology sequence were coinjected into fertilized NSGF oocytes (NOD.Cg-Prkdcscid Il2rgtm1Wjl Flt3em1Akp). Human LTBR was inserted into exon 1 and exon 2 via homologous recombination. The resulting founders, carrying human LTBR were bred to NOD.Cg-PrkdcscidIl2rgtm1Wjl Flt3em1Akp mice, and were then interbred until all offspring were homozygous for LTBR targeted mutation. Primer used for genotype by PCR reaction were listed in Table 2.
A limited biologic cross-reactivity between murine and human cytokines and cytokine receptors constrains the development of the human innate immune system, especially monocyte, macrophages and neutrophils. Efforts have been made to express human cytokines either through transgenic or knock-in human genes (Rathinam et al., 2011; Rongvaux et al., 2014; Willinger et al., 2011). One such variant of immunodeficient mice is based on NSG mice with transgenic expression of human Stem Cell Factor (SCF), Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) and Interleukin (IL)-3 (NSG-SGM3, SGM3) (Nicolini et al., 2004; Wunderlich et al., 2010). Initial studies demonstrated that, when transplanted with hCD34+ HPCs, these mice efficiently support the development of human immune cells, especially the CD33+ myeloid cells as well as CD4+Foxp3+ regulatory T cells, as compared to non-transgenic counterparts (Billerbeck et al., 2011). To further boost myeloid development, we crossed Flt mutant mice (NSGF) and SGM3 mice to yield NOD.Cg-PrkdcscidIl2rgtm1Wjl Flt3em1Akp Tg(CMV-IL3,CSF2,KITLG)1Eav/MloySzJ (NSG-SGM3-Flt3KO, SGM3F) mice. To test their capacity to support the engraftment of the human immune system, we compared four strains of immunodeficient mice: NSG, NSGF, SGM3, SGM3F mice that were irradiated sub-lethally and transplanted with 1×105 CD34+ HPCs from cord blood or from adult bone marrow. While all four strains of mice support cord blood HPCs, hSGM3F mice demonstrate superior hCD45+ engraftment at 12-weeks post-transplant with the expansion of both CD33+ myeloid cells and CD3+ T cells in the blood (
Next, we compared the development of myeloid compartment including CD66b+ granulocytic, CD14+ monocytic myeloid cells and DCs in different strains of humanized mice. While all four strains of mice support the differentiation of different myeloid cells in the bone marrow, hSGM3F mice demonstrate higher expansion of CD14+ and DCs (
In thymus, the majority of human CD3+ thymocytes were double-positive for CD4 and CD8 in hNSG and hNSGF mice, while higher percentage of single-positive CD4 or CD8 thymocytes were found in both hSGM3 and hSGM3F mice (
Finally, we sought to probe the capacity of humanized mouse strains to mount antibody responses to vaccination. We first measured the level of different immunoglobulin (Ig) isotype in the plasma of humanized mice. hNSG and hNSGF had little human IgG and IgA in the plasma while hSGM3 and hSGM3F had higher level of different Ig isotypes (
Generation of Mouse Model: NSG-SGM3-Flt3ko or SGM3F mice (NOD.Cg-PrkdcscidIl2rgtm1Wjl-Flt3em1Akp Tg(CMV-IL3, CSF2,KITLG)1Eav/MloySzJ), were generated by crossing NSG-SGM3 mice (NOD.Cg-PrkdcscidIl2rgtm1Wjl Tg(CMV-IL3,CSF2,KITLG)1Eav/MloySzJ; RRID:IMSR Jackson Lab Stock #013062) to NSGF mice and interbred until all offspring were homozygous. NSG-SGM3 mice carried three separate transgenes which were designed each carrying either the human interleukin-3 (IL-3) gene, the human granulocyte/macrophage-stimulating factor (GM-CSF) gene, or human Steel factor (SF) gene. Expression of each gene is driven by a human cytomegalovirus promoter/enhancer sequence, and is followed by a human growth hormone cassette and a polyadenylation (polyA) sequence. The transgenes were microinjected into fertilized C57BL/6×C3H/HeN oocytes. The resulting founders, carrying all three transgenes (3GS) were backcrossed to BALB/c-scid/scid mice for several generations and subsequently backcrossed to NOD.CB17-Prkdcscid mice for at least 11 generations. These mice were bred to NSG mice (NOD.Cg-Prkdcscid Il2rgtm1Wjl; RRID:IMSR JAX: 005557), and were then interbred until all offspring were homozygous for 3GS and the IL2rg targeted mutation. Upon arrival at The Jackson Laboratory, transgenic mice were bred to NSG mice for one generation to establish NSG-SGM3 mice. NSGF mice were generated using CRISPR/cas system. Cas9 mRNA and sgRNAs targeting mouse Flt3 were coinjected into fertilized NSG oocytes. The resulting founders, carrying Flt3 deletion were bred to NSG mice, and were then interbred until all offspring were homozygous for Flt3 targeted mutation.
Additional Materials and Methods
Humanized Mice
Humanized mice were generated on different strains of mice in NSG background obtained from The Jackson Laboratory (Bar Harbor, ME). All protocols were reviewed and approved by the Institutional Animal Care and Use Committee at The Jackson Laboratory (14005) and University of Connecticut Health Center (101163-0220 & 101831-0321; Farmington, CT). Mice were sub-lethally irradiated (10 cGy per gram of body weight) using gamma irradiation at the age of four weeks. 100,000 CD34+ HPCs from fetal liver or full-term cord blood (Advanced Bioscience Resources or Lonza) were given by tail-vein intravenous (IV) injection in 200 μL of PBS. Alternatively, mice received adult CD34+ HPCs from bone marrow (Lonza) as indicated. Mice were bled at 4-12 weeks post HPC transplant to evaluate engraftment and euthanized according to the individual experimental design.
Mice were euthanized and blood was collected with heparin. The bones (femur and tibia), spleen and lungs were collected to make single cell suspension. Spleen were digested with 50 μg/ml of Liberase (Roche Diagnostics, Indianapolis, IN) and 24 U/mL of DNase I (Sigma) for 10 min at 37° C. Lungs were digested with 50 μg/ml of Liberase and 24 U/mL of DNase I (Sigma) for 30 min at 37° C., followed by mechanical dissociation with GentleMACS (Miltenyi Biotec). Cells were first treated with murine Fc blocker (BD) and then stained on ice with antibody cocktails for 30 mins. After washing twice with PBS, the samples were acquired on a LSRII or FACSARIA II (BD), and analyzed with FlowJo software (Tree Star, Ashland, OR). For the expression of mouse Flt3, cells were stained with antibodies to mouse CD45-BV650 (30− F11, BD) and FLT3-BV421 (A2F10.1, BD). For the expression of human LTBR, cells were stained with antibodies to mouse CD45-BV650 (30-F11, BD) and human LTBR-PE (31G4D8, BD). For the analysis of mouse DCs, cells were stained antibodies to mouse CD45-BV650 (30− F11, BD), CD3-PE-CF579 (145-2C11, BD), CD19-PE-CF579 (ID3, BD), CD103-PerCP-Cy5.5 (M290, BD), F4/80-PE-Cy7 (F4/80, BD), Gr1-PO (RB6-8C5, BD), IAg7-FITC (10-2-16, BD), CD11c-V450 (HL3, BD), CD172a-PE (P84, BD), CD8-PE (53-6.72, BD), and PDCA-1-APC (927, Biolegend). For human engraftment in the blood, cells were stained with antibodies to mouse CD45-BV650 (30-F11, BD) and human CD45-BV510 (HI30, BD), CD33-PE (P67.6, Biolegend), CD14-PE-Cy7 (MqP9, BD), CD19-APC (HIB19, Biolegend) and CD3-APC-H7 (SK7, BD). For human immune cell phenotype, additional antibodies were used to stain bone marrow, spleen and thymus including antibodies to human CD1c-PerCPCy5.5 (L161, Biolegend), CLEC9A-PE (8F9, Biolegend), CD303-FITC (AC144, Miltenyi Biotec), HLA-DR-APC-eFour 780 (LN3, Thermofisher), CD11c-V450 (B-ly6, BD), CD66b-FITC (G10F5, BD), CD8-ECD (SF121Thy2D3, Beckman Coulter), CD4-BUV395 (SK3, BD), CD45RA-PerCPCy5.5 (HI100, BD) and CCR7-PE-Cy7 (3D12, BD).
Tissues were embedded in OCT (Sakura Finetek U.S.A.) and snap frozen in liquid nitrogen. Frozen sections were cut at 6 μm, air dried on Superfrost plus slides and fixed with cold acetone for five minutes. Tissue sections were first treated with 0.03% hyaluronidase (Sigma) for 15 minutes, followed by treatment with Background Buster and Fc Receptor Block (Innovex Bioscience). The sections were then stained with monoclonal antibodies to mouse I-Ag7 (10.2.16, BD), human CD3 (UCHT1, Biolegend), CD4 (RPA-T4, Biolegend), CD8 (RPA-T8, BD), CD11c (S-HCL-3, BD), or HLA-DR (L243, Biolegend) for one hour at room temperature, followed by isotype-specific secondary antibodies for 30 minutes at room temperature. Respective isotype antibodies were used as the control. Finally, sections were counterstained with 1 μg/ml of 4′,6-diamidino-2-phenylindole (DAPI), mounted with Fluoromount (Thermo Fisher Scientific), and visualized using a Leica SP 8 confocal microscope with Leica LAS AF 2.0 software or a Zeiss Axio fluorescence microscope with ZEN software.
Cytokine production were measured with ELISA kit following manufacture protocol. For mouse Flt3L, plasma from both WT and Flt3-KO mice were tested with mouse Flt3L ELISA Duo Set from R&D systems. For human IL6, plasma from both WT and IL6-KI mice treated with 20 μg of LPS (Invivogen) IP for 2 hours were tested with human IL6 ELISA MAX Deluxe Set from Biolegend. For human TSLP, mouse lungs from both WT and TSLP-KI mice were stimulated ex-vivo with 50 ng/mL of PMA (Sigma) and 1 μg/mL of ionomycin (Sigma) for 18 hours and human TSLP were measured in the culture supernatant with human TSLP ELISA Max Deluxe Set from Biolegend. For total human IgM, IgG and IgA, plasma samples were tested with Human IgM, IgG, and IgA ELISA kit (Bethyl Laboratories). For KLH-specific human IgG, ELISA plates were coated with 10 μg/mL of purified KLH (Thermo Fisher Scientific) and detected with Human IgG ELISA kit. For Fluzone-specific human IgG, ELISA plates were coated with Fluzone (2015-2016 season, Sanofi) and detected with Human IgG ELISA kit.
The hemagglutination inhibition (HAI) assay was performed to detect and quantitate antiviral antibodies in the serum. Aliquots of 50 μl of serum (including all the test sera and reference human serum as positive control) were first treated with receptor destroying enzyme (Sigma) for 16-18 hours at 37° C. Sera were then heated to 56° C. for thirty minutes to remove the enzyme activity and incubated with 200 μl of 1% chicken red blood cells (CRBCs) at room temperature for thirty minutes to remove non-specific hemagglutination activity in the serum. Diluted samples (⅕ dilution) were recovered by centrifuging at 1200 rpm for ten minutes. Mixture of 50 μl of influenza virus containing 4 HA unit and 50 μl of 2-fold serial diluted serum are incubate at room temperature for thirty minutes in duplicate on 96-well U bottom plates. Then, 50 μl of 1% CRBCs were added into each well and incubated at room temperature for forty-five minutes. The HAI titer was defined as the reciprocal of the final dilution that does not give hemagglutination.
Statistical analyses were performed in Prism (GraphPad). Comparisons between any 2 groups were analyzed using the Mann-Whitney test or two-tailed t-test. Comparisons between any 3 or more groups were analyzed by analysis of variance (ANOVA).
All references, patents and patent applications disclosed herein are incorporated by reference with respect to the subject matter for which each is cited, which in some cases may encompass the entirety of the document.
The indefinite articles “a” and “an,” as used herein the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”
It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.
In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.
The terms “about” and “substantially” preceding a numerical value mean±10% of the recited numerical value.
Where a range of values is provided, each value between and including the upper and lower ends of the range are specifically contemplated and described herein.
This application claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional application No. 63/049,175, filed Jul. 8, 2020, which is incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US21/40678 | 7/7/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63049175 | Jul 2020 | US |
