Microbial delivery system

BACKGROUND OF THE INVENTION

[0003] Allergic reactions pose serious public health problems worldwide. Pollen allergy alone (allergic rhinitis or hay fever) affects about 10-15% of the population, and generates huge economic costs. For example, reports estimate that pollen allergy generated $1.8 billion of direct and indirect expenses in the United States in 1990 (Fact Sheet, National Institute of Allergy and Infectious Diseases; McMenamin, Annals of Allergy 73:35, 1994). Asthma, which can be triggered by exposure to antigens, is also a serious public health problem, and like anaphylactic allergic reactions, can lead to death in extreme cases. Asthma currently accounts for millions of visits yearly to hospitals and is increasing in frequency. The only treatment currently available is for alleviation of symptoms, for example, to relieve constriction of airways. More serious than the economic costs associated with pollen and other inhaled allergens (e.g., molds, dust mites, animal danders) is the risk of an anaphylactic allergic reaction observed with allergens such as food allergens, insect venoms, drugs, and latex.

[0004] Allergic reactions result when an individual's immune system overreacts, or reacts inappropriately, to an encountered antigen. Typically, there is no allergic reaction the first time an individual is exposed to a particular antigen. However, it is the initial response to an antigen that primes the system for subsequent allergic reactions. In particular, the antigen is taken up by antigen presenting cells (APC; e.g., macrophages and dendritic cells) that degrade the antigen and then display antigen fragments to T cells. T cells, in particular CD4+ “helper” T-cells, respond by secreting a collection of cytokines that have effects on other immune system cells. The profile of cytokines secreted by responding CD4+ T cells determines whether subsequent exposures to the antigen will induce allergic reactions. Two classes of CD4+ T cells (Th1 and Th2) influence the type of immune response that is mounted against an antigen.

[0005] Th2 cells can secrete a variety of cytokines and interleukins including IL-4, IL-5, IL-6, IL-10 and IL-13. One effect of IL-4 is to stimulate the maturation of B cells that produce IgE antibodies specific for the antigen. Allergic responses to allergens are characterized by the production of antigen-specific IgE antibodies which are dependent on help from IL-4 secreting CD4+ T cells. These antigen-specific IgE antibodies attach to receptors on the surface of mast cells, basophils and eosinophils, where they act as a trigger to initiate a rapid allergic reaction upon the next exposure to antigen. When the individual encounters the antigen a second time, the antigen is quickly bound by these surface-associated IgE molecules. Each antigen typically has more than one IgE binding site, so that the surface-bound IgE molecules quickly become crosslinked to one another through their simultaneous (direct or indirect) associations with antigen. Such cross-linking induces mast cell degranulation, resulting in the release of histamines and other substances that trigger allergic reactions. Individuals with high levels of IgE antibodies are known to be particularly prone to allergies.

[0006] Current treatments for allergies involve attempts to “vaccinate” a sensitive individual against a particular allergen by periodically injecting or treating the individual with a crude suspension of the raw allergen. The goal, through controlled administration of known amounts of antigen, is to modulate the IgE response mounted in the individual. If the therapy is successful, the individual's IgE response is diminished, or can even disappear. However, the therapy requires several rounds of vaccination, over an extended time period (3-5 years), and very often does not produce the desired results. Moreover, certain individuals suffer anaphylactic reactions to the vaccines, despite their intentional, controlled administration.

[0007] Clearly, there is a need for treatments and preventive methods for patients with allergies to allergens that elicit serious allergic responses including anaphylaxis.

SUMMARY OF THE INVENTION

[0008] The present invention provides methods and compositions for modulating the immune response in a subject. It is an aspect of the present invention to provide a method of treating or preventing undesirable allergic reactions and anaphylactic allergic reactions to allergens in a subject. Methods of the present invention involve administering to subjects, microorganisms that express or produce allergens of interest. Without being limited to the proposed mechanism of action, after administration the microorganisms are taken up by antigen-presenting cells in the subject where the expressed antigens are released. After being processed inside the antigen-presenting cells and displayed on the cell surface, the processed antigens activate T-cell mediated immune responses. Use of genetically modified microorganisms to express and deliver allergens to a subject therefore reduces the exposure of the allergens to the subject's IgE antibodies, which lead to allergic reactions and possibly anaphylaxis. The present invention therefore reduces the risk of anaphylaxis during immunotherapy. Furthermore, the microorganisms may act as a natural adjuvant to enhance desirable Th1-type immune responses.

[0009] In a preferred embodiment, microorganisms are genetically modified to express selected polypeptides or proteins, and are used as delivery vehicles in accordance with the present invention. Such microorganisms include but are not limited to bacteria, viruses, fingi (including yeast), algae, and protozoa. Generally, preferred microorganisms for use in accordance with the present invention are single cell, single spore or single virion organisms. Additionally, included within the scope of the present invention are cells from multi-cellular organisms which have been modified to produce a polypeptide of interest.

[0010] In a particularly preferred embodiment, bacteria or yeast are used as microorganisms to express and deliver allergenic proteins to individuals to treat or prevent allergic responses, including anaphylactic allergic responses, to the allergens. Gram-positive and gram-negative bacteria may be used in the present invention has delivery vehicles. Antigens expressed by the bacteria may be secreted or non-secreted. Secretion of proteins may involve secretion into the cellular medium. For gram-negative bacteria and yeast, secretion may involve secretion into the periplasm. Secretion of polypeptides may be facilitated by secretion signal peptides. In certain preferred embodiments microorganisms expressing allergenic compounds may be administered to subjects in compositions as attenuated microorganisms, non-pathogenic microorganisms, non-infectious microorganisms, or as killed microorganisms. Preferably, the killed microorganisms are killed without degrading the antigenic properties of the polypeptides.

[0011] In another preferred embodiment, the allergens utilized are allergens found in foods, venom, drugs and a rubber-based products. Particularly preferred protein allergens are found in foods and venoms that elicit anaphylactic allergic responses in subjects who are allergic to the allergens. Included in the present invention are peptides and polypeptides whose amino acid sequences are found in the proteins allergens in nature. Also included in the present invention are allergens that have modifications that reduce the ability of the peptides, polypeptides and proteins to bind and crosslink IgE antibodies. Also included in the present invention are non-peptide allergens that are produced by microorganisms and include for example antibiotics such as penicillin.

[0012] In another aspect of the invention, compositions for use in treating or prevent allergic and anaphylactic allergic responses in a subject comprise microorganisms that have been engineered by the hand of man, and preferably by the introduction of one or more introduced nucleic acids, to produce allergens in accordance with the present invention. In certain preferred embodiments, the produced allergens are peptides, polypeptides, or proteins encoded by the introduced nucleic acids(s).

BRIEF DESCRIPTION OF FIGURES

[0013]
FIG. 1. Experiments designed to determine the optimal temperature for heat-killing bacteria (E. coli) are depicted in graphic form. The number of surviving colonies in aliquots of samples are shown as a function of temperature (Celsius).

[0014]
FIG. 2. Determination of protein produce per cell. The optical density (O.D.) of the HIS-tagged Ara h 2 allergen was determined from an immunoblot where different concentrations of E. coli extract has been electrophoresed on SDS-PAGE gels. The allergen O.D. was used to estimate the amount of protein produced by that extract.

[0015]
FIG. 3. Results of ELISA analysis of Ara h 2-specific IgG antibodies produced in mice following injection of E. coli producing Ara h 2. IgG1 is on the left and IgG2a is on the right.

[0016]
FIG. 4. Results of ELISA analysis of Ara h 3-specific IgG antibodies produced in mice following injection of E. coli producing Ara h 3. IgG1 is on the left and IgG2a is on the right.

DEFINITIONS

[0017] “Allergen”: An “allergen” is an antigen that (i) elicits an IgE response in an individual; and/or (ii) elicits an asthmatic reaction (e.g., chronic airway inflammation characterized by eosinophilia, airway hyperresponsiveness, and excess mucus production), whether or not such a reaction includes a detectable IgE response). Preferred allergens for the purpose of the present invention are peptide, polypeptide and protein allergens. An exemplary list of protein allergens is presented as an Appendix. This list was adapted from ftp://biobase.dk/pub/who-iuis/allergen.list (updated on Mar. 1, 2000), which provides lists of known allergens. Other preferred allergens are chemical compounds such as small molecules that are produced by proteins.

[0018] “Allergic reaction”: An allergic reaction is a clinical response by an individual to an antigen. Symptoms of allergic reactions can affect cutaneous (e.g., urticaria, angioedema, pruritus), respiratory (e.g., wheezing, coughing, laryngeal edema, rhinorrhea, watery/itching eyes) gastrointestinal (e.g., vomiting, abdominal pain, diarrhea), and/or cardiovascular (if a systemic reaction occurs) systems. For the purposes of the present invention, an asthmatic reaction is considered to be a form of allergic reaction.

[0019] “Anaphylactic antigen”: An “anaphylactic antigen” according to the present invention is an antigen (or allergen) that is recognized to present a risk of anaphylactic reaction in allergic individuals when encountered in its natural state, under natural conditions. For example, for the purposes of the present invention, pollens and animal danders or excretions (e.g., saliva, urine) are not considered to be anaphylactic antigens. On the other hand, food antigens, insect antigens, drugs, and rubber (e.g., latex) antigens latex are generally considered to be anaphylactic antigens. Food antigens are particularly preferred anaphylactic antigens for use in the practice of the present invention. Particularly interesting anaphylactic antigens are those (e.g., nuts, seeds, and fish) to which reactions are commonly so severe as to create a risk of death.

[0020] “Anaphylaxis” or “anaphylactic reaction”, as used herein, refers to an immune response characterized by mast cell degranulation secondary to antigen-induced cross-linking of the high-affinity IgE receptor on mast cells and basophils with subsequent mediator release and the production of pathological responses in target organs, e.g., airway, skin digestive tract and cardiovascular system. As is known in the art, the severity of an anaphylactic reaction may be monitored, for example, by assaying cutaneous reactions, puffiness around the eyes and mouth, and/or diarrhea, followed by respiratory reactions such as wheezing and labored respiration. The most severe anaphylactic reactions can result in loss of consciousness and/or death.

[0021] “Antigen”: An “antigen” is (i) any compound or composition that elicits an immune response; and/or (ii) any compound that binds to a T cell receptor (e.g., when presented by an MHC molecule) or to an antibody produced by a B-cell. Those of ordinary skill in the art will appreciate that an antigen may be collection of different chemical compounds (e.g., a crude extract or preparation) or a single compound (e.g., a protein). Preferred antigens are peptide, polypeptide or protein antigens.

[0022] “Antigen presenting cells”: “Antigen presenting cells” or APCs” include known APCs such as Langerhans cells, veiled cells of afferent lymphatics, dendritic cells and interdigitating cells of lymphoid organs. The term also includes mononuclear cells such as lymphocytes and macrophages which take up polypeptides and proteins according to the invention.

[0023] “Attenuation”: “Attenuation” of microorganisms as used herein refers to the manipulation of the microorganisms so that the microorganisms do not induce significant toxic reactions in individuals or laboratory test animals. The manipulations include genetic methods and are well known in the art.

[0024] “IgE binding site”: An IgE binding site is a region of an antigen that is recognized by an anti-antigen IgE molecule. Such a region is necessary and/or sufficient to result in (i) binding of the antigen to IgE; (ii) cross-linking of anti-antigen IgE; (iii) degranulation of mast cells containing surface-bound anti-antigen IgE; and/or (iv) development of allergic symptoms (e.g., histamine release). In general, IgE binding sites are defined for a particular antigen or antigen fragment by exposing that antigen or fragment to serum from allergic individuals (preferably of the species to whom inventive compositions are to be administered). It will be recognized that different individuals may generate IgE that recognize different epitopes on the same antigen. Thus, it is typically desirable to expose antigen or fragment to a representative pool of serum samples. For example, where it is desired that sites recognized by human IgE be identified in a given antigen or fragment, serum is preferably pooled from at least 5-10, preferably at least 15, individuals with demonstrated allergy to the antigen. Those of ordinary skill in the art will be well aware of useful pooling strategy in other contexts.

[0025] “Immunologic inducing agents”: The term “immunological inducing agents” is used herein as agents that prompt the expression of Th1 stimulating cytokines by T-cells and include factors such as, CD40, CD40 ligand, oligonucleotides containing CpG motifs, TNF, and microbial extracts such as preparations of Staphylococcus aureus, heat killed Listeria, and modified cholera toxin.

[0026] “Inducible promoter”: The term “inducible promoter”, as used herein, means a promoter site which is activated directly by the presence or absence of a chemical agent or indirectly by an environmental stimulus such as temperature changes. A promoter is the region of DNA at which the enzyme RNA polymerase binds and initiates the process of gene transcription.

[0027] “Mast cell”: As will be apparent from context, the term “mast cell” is often used herein to refer to one or more of mast cells, basophils, and other cells having IgE receptors, which when activated by crosslinking bound IgE molecules, releases histamines, vasodilators, and/or other mediators of allergic responses.

[0028] “Microorganisms”: “Microorganisms” as used herein are cells, bacteria, fungi, viruses, algae, and protozoa. Preferred microorganisms can be genetically manipulated to produce a desired polypeptide(s).

[0029] “Peptide”: According to the present invention, a “peptide” comprises a string of at least three amino acids linked together by peptide bonds. Inventive peptides preferably contain only natural amino acids, although non-natural amino acids (i.e., compounds that do not occur in nature but that can be incorporated into a polypeptide chain; see, for example, http://www.cco.caltech.edu/˜dadgrp/Unnatstruct.gif, which displays structures of non-natural amino acids that have been successfully incorporated into functional ion channels) and/or amino acid analogs as are known in the art may alternatively be employed. Also, one or more of the amino acids in an inventive peptide may be modified, for example, by the addition of a chemical entity such as a carbohydrate group, a phosphate group, a farnesyl group, an isofarnesyl group, a fatty acid group, a linker for conjugation, functionalization, or other modification, etc.

[0030] A peptide or polypeptide is derived from a protein if the amino acid sequence of the peptide or polypeptide is found within the amino acid sequence of the protein. The sequences are preferably identical but may have a sequence homology between approximately 80-100%. It is also recognized that amino acid residues may be replaced with other amino acids residues with similar physical properties such as hydrophobicity, hydrophilicity, charge, aromatic structures and polarity.

[0031] “Reduced IgE binding”: An inventive composition or antigen is considered to have “reduced IgE binding” if it demonstrates a lower level of interaction with IgE when compared with unmodified antigen in any available assay. For example, a modified antigen is considered to have reduced IgE binding if (i) its affinity for anti-antigen IgE (assayed, for example, using direct binding studies or indirect competition studies) is reduced at least about 2-5 fold, preferably at least about 10, 20, 50, or 100 fold as compared with intact antigen; (ii) ability of the modified antigen to support cross-linking of anti-antigen IgE is reduced at least about 2-fold, preferably at least about 5, 10, 20, 50, or 100 fold as compared with intact antigen; (iii) mast cells containing surface-bound anti-antigen IgE degranulate less (at least about 2 fold, preferably at least about 3, 5, 10, 20, 50, or 100 fold less) when contacted with modified as compared with unmodified antigen; and/or (iv) individuals contacted with modified antigen develop fewer (at least about 2 fold, preferably at least about 3, 5, 10, 20, 50, or 100 fold fewer) allergic symptoms, or developed symptoms are reduced in intensity when exposed to modified antigens as compared with unmodified antigens.

[0032] “Secretion signals”: A secretion signal is any amino acid sequence which when conjugated to a peptide, polypeptide or protein facilitates the transport of the conjugate fusion proteins across cell membranes. For uses of secretion signals in microorganisms, transport of fusion proteins involves crossing an inner membrane into the periplasm. It is preferred that secretion signals also facilitate transport of fusion proteins across an outer membrane into an extracellular medium. Secretion of proteins into the extracellular medium is considered “excretion”.

[0033] “Sensitized mast cell”: A “sensitized” mast cell is a mast cell that has surface-bound antigen specific IgE molecules. The term is necessarily antigen specific. That is, at any given time, a particular mast cell will be “sensitized” to certain antigens (those that are recognized by the IgE on its surface) but will not be sensitized to other antigens.

[0034] “Small molecules”: As used herein, the term “small molecule” refers to a compound either synthesized in the laboratory or found in nature. Typically, a small molecule is organic and is characterized in that it contains several carbon-carbon bonds, and has a molecular weight of less than 1500 daltons, although this characterization is not intended to be limiting for the purposes of the present invention. Examples of “small molecules” that are allergens include without limitation penicillin, alcohols, and aspirin. Non-organic small molecule allergens include sulfites present in wine, for example.

[0035] “Susceptible individual”: According to the present invention, a person is susceptible to an allergic reaction if (i) that person has ever displayed symptoms of allergy after exposure to a given antigen; (ii) members of that person's genetic family have displayed symptoms of allergy against the allergen, particularly if the allergy is known to have a genetic component; and/or (iii) antigen-specific IgE are found in the individual, whether in serum or on mast cells.

[0036] “Th1 response” and “Th2 response”: Certain preferred peptides, polypeptides, proteins and compositions of the present invention are characterized by their ability to suppress a Th2 response and/or to stimulate a Th1 response preferentially as compared with their ability to stimulate a Th2 response. Th1 and Th2 responses are well-established alternative immune system responses that are characterized by the production of different collections of cytokines and/or cofactors. For example, Th1 responses are generally associated with production of cytokines such as IL-1β, IL-2, IL-12, IL-18, IFNα, IFNγ, TNFβ, etc; Th2 responses are generally associated with the production of cytokines such as IL-4, IL-5, IL-10, etc. The extent of T cell subset suppression or stimulation may be determined by any available means including, for example, intra-cytoplasmic cytokine determination. In preferred embodiments of the invention, Th2 suppression is assayed, for example, by quantitation of IL-4, IL-5, and/or IL-13 in stimulated T cell culture supernatant or assessment of T cell intra-cytoplasmic (e.g., by protein staining or analysis of mRNA) IL-4, IL-5, and/or IL-13; Th1 stimulation is assayed, for example, by quantitation of IFNα, IFNγ, IL-2, IL-12, and/or IL-18 in activated T cell culture supernatant or assessment of intra-cytoplasmic levels of these cytokines.

Description of Certain Preferred Embodiments

[0037] The present invention provides compositions and methods for modulating the immune response in a subject. It is an aspect of the present invention that undesirable allergic immune responses to antigens in a subject are treated or prevented by administering modified cells, virions, or spores (“microorganisms”) that express allergens of interest. By using genetically modified microorganisms to express and deliver allergens, exposure of the allergens to the subject's IgE-mediated allergic immune response is reduced or eliminated. Without limitation to the mechanisms proposed, it is expected that the modified microorganisms of the present invention are engulfed by antigen-presenting cells (APCs) such as macrophages and dendritic cells without exposing allergens to IgE antibodies. Once inside the APCs, the expressed allergens are released by lysis of the microorganisms or secretion of the antigen by the microorganisms. The allergens are then processed, for example through partial digestion by the APCs, and displayed on the cell surface.

[0038] Once the processed antigens are displayed on the cell surface, activation of the cytotoxic T cell response and helper T cell response promotes cellular immune response and Th1-mediated B cell response to protein allergens. In addition, the processed antigens have a reduced ability (or no ability) to bind and crosslink IgE antibodies located on the surface of mast cells and basophils leading to the release of histamines and other vasodilators responsible for allergic and sometimes fatal anaphylactic responses.

[0039] Host Microorganisms

[0040] Any microorganism capable of expressing (e.g., by expression of polypeptide or protein allergens, or by expression of polypeptide or protein enzymes involved in synthesis of small molecule allergens) allergens may be used as delivery vehicles in accordance with the present invention. Such microorganisms include but are not limited to bacteria, viruses, fungi (including yeast), algae, and protozoa. Generally, microorganisms are single cell, single spore or single virion organisms. Additionally, included within the scope of the present invention are cells from multi-cellular organisms which have been modified to produce a polypeptide of interest. Microorganisms that can be genetically manipulated to produce a desired polypeptide are preferred. (Ausubel et al. Current Protocols in Molecular Biology. Wiley and Sons, Inc. 1999, incorporated herein by reference) Genetic manipulation includes mutation of the host genome, insertion of genetic material into the host genome, deletion of genetic material of the host genome, transformation of the host with extrachromosomal genetic material, transformation with linear plasmids, transformation with circular plasmids, insertion of genetic material into the host (e.g., injection of mRNA), insertion of transposons, and chemical modification of genetic material. Methods for constructing nucleic acids (including an expressible gene), and introducing such nucleic acids into an expression system to express the encoded protein are well established in the art (see, for example, Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd Ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989, incorporated herein by reference).

[0041] Use of microorganisms such as bacteria and yeast for allergen delivery in accordance with the present invention offers many advantages over delivery of allergens that are not encapsulated inside microorganisms for immunotherapy. Generally, microorganisms, such as bacteria, are known to act as an adjuvant (for a review, see for example, Freytag et al. Curr Top Microbiol Immunol 236:215-36, 1999). Therefore, use of microorganisms to delivery allergens to subjects, and APCs of subjects, provides protection of the allergen from IgE-mediated allergic responses and also provides an adjuvant effect which elicits a Th1-type immune response from an individual susceptible to allergic responses. In addition, use of non-pathogenic, non-infectious, attenuated and/or killed microorganisms reduces or eliminates toxicity which may be associated with allergen delivery vehicles.

[0042] In a preferred embodiment, bacteria are used as protein delivery microorganisms. Generally, bacteria are classified as gram-negative or gram-positive depending on the structure of the cell walls. Those skilled in the art are capable of identifying gram-negative and gram-positive bacteria which may be used to express proteins in accordance with the present invention. Non-limiting examples of genera and species of gram-negative bacteria include Escherichia coli, Vibro cholera, Salmonella, Listeria, Legionella, Shigella, Yersenia, Citrobacter, Enterobacter, Klebsiella, Morganella, Proteus, Providencia, Serratia, Plesiomonas, Aeromonas. Non-limiting examples of genera and species of gram-positive bacteria which may be used in the present invention include Bacillus subtilis, Sporolactobacillus, Clostridium, Arthrobacter, Micrococcus, Mycobacterium, Peptococcus, Peptostreptococcus, and Lactococcus.

[0043] Gram-negative bacterial systems for use as delivery vehicles are known and may be used in the present invention. For example, E. coli is a well-studied bacteria, and methods of protein expression in E. coli are well-established. Most strains of E. coli have the advantage of being non-pathogenic since E. coli is found naturally in the gut. Therefore, E. coli is preferred as a delivery vehicle in the present invention. In addition, Calderwood et al. (U.S. Pat. No. 5,747,028) utilize Vibrio cholerae as a delivery vehicle for production of antigens for use as a live vaccine against infectious organisms. Miller and Mekalanos (U.S. Pat. No. 5,731,196) utilize Salmonella as delivery vehicle for production of antigens for use as a live vaccine against infectious organisms. Hess et al. (Proc. Natl. Acad. Sci. USA 93:1458-1463, 1996) utilize recombinant attenuated Salmonella which secretes antigenic determinants of Listeria as a live vaccine to protect against listeriosis. Donner et al. (WO 98/50067) utilize attenuated Salmonella typhimurium as a gram-negative host for secretion of polypeptides for controlling fertility and also teach that other attenuated gram-negative strains including Yersinia may be used to express and secrete such polypeptides.

[0044] Gram-positive bacteria have also been studied as delivery vehicles for proteins to modulate an immune response in a subject. WO 97/14806 describes the use of Lactococcus to deliver polypeptides into a body to enhance the immune response to the polypeptides. However, WO 97/14806 does not teach the use of Lactococcus to treat patients with food allergies and venom allergies which may result in anaphylaxis

[0045] In another preferred embodiment, yeast are used as protein delivery microorganisms. It is well known that yeast are amenable to genetic manipulation to express a protein or proteins of choice (Ausubel et al. supra). Furthermore, in general most yeast are non-pathogenic. Without limitation to these species, two well-characterized species of yeast are the budding yeast Saccharomyces cerevisiae, and the fission yeast, Schizosaccharomyces pombe. Moreover, the administration of yeast that express protein antigens to alter an immune response has been studied. Duke et al. (U.S. Pat. No. 5,830,463; “Duke”) describe the use of yeast to express proteins after administration of the yeast to a mammal. However, Duke does not teach the use of yeast to treat patients with food allergies and venom allergies which may result in anaphylaxis.

[0046] Microorganisms of the present invention may be administered to a subject as live or dead microorganisms. Preferably if the microorganisms are administered as live microorganisms, they are non-pathogenic or attenuated pathogenic microorganisms. For applications of the invention where live microorganisms are administered to individuals, preferably the microorganisms are attenuated and/or are administered in suitable encapsulation materials and/or as pharmaceutical compositions as vaccines to decrease an individuals immune response to the microorganism and/or allergenic compounds. Generally, attenuation involves genetically modifying the infectious pathogenic microorganism to reduce or eliminate the infectious ability of the microorganism. Preferably, the microorganism is attenuated such that an individual inoculated with the microorganism does not suffer any cytotoxic effects from the presence of the microorganism. Particularly preferred attenuated microorganisms are infectious intracellular pathogens which are phagocytosed by antigen-presenting cells in individuals who are exposed to the microorganism. Examples of microorganisms which are intracellular pathogens include Salmonella, Mycobacterium, Leishmania, Legionella, Listeria, and Shigella.

[0047] Microorganisms of the present invention may be administered to subjects after killing the microorganisms. Any method of killing the microorganisms may be utilized that does not greatly alter the antigenicity of the expressed polypeptides. Methods of killing microorganism include but are not limited to using heat, antibiotics, chemicals such as iodine, bleach, ozone, and alcohols, radioactivity (i.e. irradiation), UV light, electricity, and pressure. Preferred methods of killing microorganisms are reproducible and kill at least 99% of the microorganisms. Particularly preferred is the use of heat above 50 degrees Celsius for a period of time that kills greater than 99% of the cells and preferably 100% of the cells.

[0048] Inducible Systems

[0049] In another preferred embodiment, the inventive expression of allergens by microorganisms is regulated so that synthesis occurs at a controlled time after the live microorganism is administered to an individual. Preferably the induction of protein synthesis is regulated so that activation occurs after the microorganism(s) is taken up by antigen-presenting cells (APCs) and phagocytosed into the endosome. A desirable result of this regulation is that production of the allergen of interest occurs inside the APCs and therefore reduces or eliminates the exposure of the allergen to IgE molecules bound to the surface of histamine-releasing mast cells and basophils. This reduces or eliminates the risk of anaphylaxis during administration of microorganisms that produce anaphylactic antigens.

[0050] Any method of controlling protein synthesis in the microorganism may be used in accordance with the present invention. Preferably, the method of controlling protein synthesis utilizes an inducible promoter operatively-linked to the gene of interest (e.g., a gene which encodes a signal peptide and protein antigen). Many systems for controlling transcription of a gene using an inducible promoter are known (Ausubel et al. Current Protocols in Molecular Biology. Wiley and Sons. New York. 1999). Generally, inducible systems either utilize activation of the gene or derepression of the gene. It is preferred that the present invention utilizes activation of a gene to induces transcription. However, inducible systems using derepression of a gene may also be used in the present invention. Systems using activation are preferred because these systems are able to tightly control inactivation (and hence basal level synthesis) since derepression may result in low levels of transcription if the derepression is not tight.

[0051] Methods of inducing transcription include but are not limited to induction by the presence or absence of a chemical agent, induction using a nutrient starvation inducible promoter, induction using a phosphate starvation inducible promoter and induction using a temperature sensitive inducible promoter. A particularly preferred system for regulating gene expression utilizes tetracycline controllable expression system. Systems which utilize the tetracycline controllable expression system are commercially available (see for example, Clontech, Palo Alto, Calif.).

[0052] Another particularly preferred system for regulating gene expression utilizes an ecdysone-inducible expression system which is also commercially available (Invitrogen, Carlsbad Calif.). The ecdysone-inducible expression system is based on the ability of ecdysone which is an insect hormone, to activate gene expression by binding to the ecdysone receptor. The expression system utilizes a modified heterologous protein containing the ecdysone receptor, a viral transactivation domain (from VP16) and the retinoid X receptor derived from mammalian cells to bind to a modified ecdysone response element in the presence of a ligand such as ecdysone or an analog (e.g. muristerone A, ponasterone A).

[0053] It is preferred that inducible systems for use in the present invention utilize inducing agents that are non-toxic to mammalians cells including humans. Furthermore, it is preferred that transcriptional inducing agents permeate cells membranes. More specifically for activation of protein synthesis in microorganisms after phagocytosis by APCs, transcriptional inducing agents must be able to pass through cells membranes of the APC and cell membranes of the microorganism to activate the expression of genes encoding protein allergens in accordance with the present invention. Since both tetracycline and ecdysone are able to pass through cell membranes and are non-toxic, tetracycline-inducible systems and ecdysone-inducible systems are ideally suited for use in the present invention. However, the use of inducible systems in the present invention is not limited to those systems.

[0054] It is also preferred that bacteria that have not been phagocytosed are killed before induction of genes expressing polypeptide allergens of interest. A preferred method of killing bacteria is to use antibiotics which are not permeable to mammalian cell membranes such that only bacteria that are not phagocytosed are killed. The use of antibiotics in accordance with the present embodiment reduces or eliminates the production of polypeptides by bacteria outside antigen presenting cells. It is important to reduce or eliminate exposure of allergen-producing bacteria to the immune system, especially bacteria that secrete polypeptides, which could elicit a potentially lethal anaphylactic reaction in an individual. Those having ordinary skill in the art are readily aware of antibiotics which may be used. Such antibiotics include but are not limited to penicillin, ampicillin, cephalosporin, griseofulvin, bacitracin, polymyxin b, amphotericin b, erythromycin, neomycin, streptomycin, tetracycline, vancomycin, gentamicin, and rifamycin

[0055] Secretion Signals

[0056] In another embodiment of the present invention, expressed allergens (and/or immunomodulatory molecules, such as cytokines; see below) are secreted by the microorganisms. Preferably, secretion of the allergens occurs inside a mammalian cell to reduce or eliminate exposure of allergens to a subject's allergic immune response. Secretion of polypeptides includes secretion into the extracellular medium and secretion of polypeptides into the periplasm of microorganisms such as gram-negative bacteria and yeast. Advantages of secreting allergens into the periplasm include reducing leakage of the allergens prior to phagocytosis of the microorganism. This advantage is most applicable in non-inducible systems. Advantages of secreting allergens into the extracellular medium in inducible systems include maximizing the amount of allergens available for processing by antigen-presenting cells after phagocytosis of the microorganisms of the present invention.

[0057] To express secreted polypeptides in bacteria, a variety of bacterial secretion signals known in the art may be used. For example, the Sec-dependent process in E. coli is one which is well known (for a review see Driessen et al. Curr. Opin. Microbiology 1:216-22). In addition, the OmpA signal peptide in E. coli has been described by Wong and Sutherland (U.S. Pat. No. 5,223,407). Fusion proteins containing either of these secretion signal peptides are not fully secreted by the bacteria, but rather transported across the inner membrane of the gram-negative bacteria into the periplasm. These secretion signals may be used in the present invention to transport allergenic or immunomodulatory polypeptides into the periplasm of bacteria. After administration of the genetically engineered bacteria to an individual and subsequent phagocytosis by APCs, the allergenic or immunomodulatory polypeptides in the periplasm are released after degradation of the outer membrane by enzymes in the endosome of the APCs. Preferably, the bacteria synthesize and secrete the polypeptides into the periplasm and are killed, preferably heat-killed, before administration. However, it is recognized that attenuated bacteria may be used to secrete inventive allergens into the periplasm and administered to individuals.

[0058] In another preferred embodiment of secreted proteins or polypeptides, fusion proteins containing secretion signal sequences and allergenic or immunomodulatory sequences are fully secreted into the extracellular medium by a microorganism after synthesis of the protein. Such secretion signals include those found in hemolysin and listeriolysin. In a particularly preferred embodiment, the hemolysin complex of E. coli is used to transport allergenic or immunomodulatory polypeptides across the inner and outer membrane of a microorganism (e.g. E. coli, Salmonella, Shigella, Vibrio, Yersinia, Citrobacter, Serratia, Pseudomonas) into the extracellular medium (Spreng et al. Mol. Microbiol. 31:1589-1601, 1999, and references therein all of which are incorporated herein by reference). Fusion of HlyAs to proteins and polypeptides has been shown to result in secretion of these fusion proteins utilizing the hemolysin secretion system (Blight and Holland, Trends Biotechnol. 1994 November; 12(11):450-5.; Gentschev et al., Behring Inst Mitt. 1994 December;(95):57-66)

[0059] The hemolysin protein (HlyA) contains a C-terminal transport signal (HlyAs) which is approximately 50-60 amino acids in length (Hess et al., Mol Gen Genet. 1990 November;224(2):201-8; Jarchau et al., Mol Gen Genet. 1994 Oct. 17;245(1):53-60). The HlyA protein is secreted across the inner and outer cellular membranes by the hemolysin secretion system. This complex contains three membrane proteins. Two of these proteins, HlyB and HlyD, are located in the inner membrane, and the third TolC, is located at the outer membrane. Genes encoding these proteins are part of the hemolysin operon which consists of four genes hlyC, hlyA, hlyB, and hlyD (Wagner et al., J. Bacteriol. 1983 April;154(1):200-10; Gentschev. Gene. 1996 Nov. 7;179(1):133-40).

[0060] In a preferred embodiment for use of the Hly secretion system, DNA plasmids (vectors) are used to express fusion proteins containing the HlyAs signal peptide and allergenic or immunomodulatory polypeptides. The genes encoding the transport complex (hlyB, and hlyD) are encoded by the same vector. It is recognized that multiple vectors can be used to encode and express these genes, or that sequences encoding these genes can be inserted into the host genome for expression. Preferably, a single vector contains the complete hemolysin operon including the hly specific promoter and an enhancer-type regulator hlyR; the HlyA gene where only the minimal polypeptide sequence necessary to transport a fusion protein is present; and the antigen of interest. TolC protein is generally produced by the host E. coli system. However, in systems where tolC DNA is not encoded by a host organism, tolC can be encoded by a vector.

[0061] In a particularly preferred embodiment, the secretion plasmid pMOhly1 described in WO 98/50067 (“Donner”) is used to express fusion proteins containing secretion signal sequences and polypeptides related to inducing anaphylaxis in individuals. The secretion vector pMOhly1 contains the complete hemolysin operon including the hly specific promoter and an enhancer-type regulator hlyR. A majority of the hlyA gene has been deleted so that HlyA encodes only the 34 amino terminal and 61 carboxyl terminal amino acids (HlyAs). A unique Nsi restriction enzyme site between the amino terminal and carboxyl terminal residues of HlyA facilitates the insertion of heterologous genes or gene fragments into the reading frame of HlyAs. The genetic information for antigens the size of 10-1000 amino acids can be inserted into this secretion vector pMOhlyl, which facilitates the secretion of these antigens in attenuated Salmonella and other gram-negative attenuated inoculation strains (e.g. E. coli, Vibrio cholera, Yersina enterocolitica). In contrast to other secretion systems, the secretion of fusion proteins using a single plasmid is described by Donner. An advantage of the hemolysin secretion system in comparison to conventional transport systems is the larger size of the fusion proteins synthesized and secreted according to the methods taught in Donner. Conventional secretion systems for the presentation of antigens are only capable of secreting relatively short peptides to the outer part of the bacterial cell (Cardenas and Clements, Clin Microbiol Rev. 1992 July;5(3):328-42).

[0062] Antigens and Allergens

[0063] In general, any allergen may be produced by microorganisms in accordance with the present invention. Preferred allergens are found in certain foods, venom, drugs or rubber and are capable of eliciting allergic responses, and in particular anaphylactic allergic responses in an individual. Particularly preferred allergens are protein or polypeptide allergens.

[0064] In a preferred embodiment, microorganisms of the present invention produce allergenic proteins that elicit allergies, possibly anaphylaxis, and are found in foods, venoms, drugs, and rubber-based products. Particularly preferred allergenic proteins that induce anaphylaxis, such as several protein allergens found in food (peanut, milk, egg, wheat), insect venom (i.e. bees, reptiles), drugs, and latex. Non-limiting examples of protein allergens found in food include proteins found in nuts (e.g., peanut walnut, almond, pecan, cashew, hazelnut, pistachio, pine nut, brazil nut), seafood (e.g. shrimp, crab, lobster, clams), fruit (e.g. plums, peaches, nectarines; Ann Allergy Asthma Immunol 7(6):504-8 (1996); cherries, Allergy 51(10):756-7 (1996)), seeds (sesame, poppy, mustard), and soy and dairy products (e.g., egg, milk).

[0065] Some protein allergens found in nuts are related to legume allergies and may be used instead of the legume proteins (e.g. peanuts, soybeans, lentils; Ann Allergy Asthma Immunol 77(6): 480-2 (1996). Also, protein antigens found in pollen-related food allergies may be used (e.g. birch pollen related to apple allergies). Other protein allergens found in foods include those found in young garlic (Allergy 54(6):626-9 (1999), and for children allergic to house dust mites, allergens found in snails (Arch Pediatr 4(8):767-9 (1997)). Protein allergens in wheat are known to cause exercise-induced allergies (J Allergy Clin Immunol 1999 May;103(5 Pt 1):912-7).

[0066] Stings from organisms that inject venoms, such as insect stings are known to cause anaphylaxis in individuals with allergies to the venom. In general, insect venom includes venom from Hymenoptera such as bees, hornets, wasps, yellow jackets, velvet ants, and fire ants. In particular for example, venom from honey bees of the genus Apis can cause anaphylaxis in stung victims who are allergic (Weber et al. Allergy 42:464-470). The venom from honey bees contains numerous compounds which have been extensively studied and characterized (see for a reference, Banks and Shipolini. Chemistry and Pharmacology of Honey-bee Venom. Chapter 7 of Venoms of the Hymenoptera. Ed. T. Piek. Academic Press. London. 1986). The two main components of bee venom are phospholipase A2 and melittin and are preferred protein allergens for use in the present invention for treating and preventing allergies to bee venom.

[0067] In certain uses of the present invention, it will be desirable to work in systems in which a single compound (e.g., a single protein) is responsible for most observed allergy. In other cases, the invention can be applied to more complex allergens. Therefore, collections of more than one antigen can be used so that immune responses to multiple antigens may be modulated simultaneously.

[0068] Appendix A presents a representative list of certain known protein antigens. As indicated, the amino acid sequence is known for many or all of these proteins, either through knowledge of the sequence of their cognate genes or through direct knowledge of protein sequence, or both. Of particular interest are anaphylactic antigens.

[0069] In another embodiment of allergenic antigens, microorganisms are genetically engineered to synthesize and secrete modified allergenic polypeptides that elicit anaphylaxis when exposed to individuals who are susceptible to anaphylactic shock. Preferably, the allergens are modified such that the ability to elicit anaphylaxis is reduced or eliminated. As previously discussed allergens elicit allergic responses which are sometimes severe enough to induce anaphylactic shock by crosslinking IgE antibodies bound to the surface of mast cells and basophils. The IgE crosslinking releases compounds such as histamines which causes symptoms related to allergies and anaphylactic shock. In accordance with the present invention, microorganisms are used to synthesize and secrete antigens which are modified to reduce or eliminate IgE binding sites while still maintaining antigenicity or immunomodulatory activity (U.S. Ser. No. 09/141,220 incorporated herein by reference). This reduces the risk of allergic or anaphylactic responses in individuals treated with vaccines containing these engineered microorganisms.

[0070] The amount of antigen to be employed in any particular composition or application will depend on the nature of the particular antigen and of the application for which it is being used, as will readily be appreciated by those of ordinary skill in the art. The experiments described in Examples 1-4 suggest that larger amounts of polypeptides are useful for inducing Th1 responses. The amount of antigen can be controlled by a variety of factors including but not limited to expression systems, inducible expression systems, levels of secretion and excretion, methods of killing bacteria before delivery. Those of ordinary skill in the art are capable of determining the desired levels of antigens to be produced by bacteria and delivered to individuals.

[0071] It is recognized that multiple antigenic molecules may be delivered by bacteria simultaneously in accordance with the methods of the present invention. Without limitation, different antigenic determinants for one antigenic protein may be delivered. Different antigenic determinants from different antigenic proteins may also be delivered. Further, multiple antigenic polypeptides and proteins may be delivered in accordance with the present invention. It is also recognized that single or multiple antigenic polypeptides and single or multiple cytokines may be delivered to individuals by bacteria in accordance with the present invention. For example but without limitation, allergenic antigens of the present invention and immunomodulatory molecules such as interleukins may be delivered by bacteria using secreted or non-secreted methods in accordance with the present invention.

[0072] Adjuvants and Immunostimulatory Agents

[0073] Compositions and methods of the present invention include the use of adjuvants and immunomodulatory polypeptides or immunostimulatory factors to modulate an individual's immune response. Immunologic adjuvants are agents that enhance specific immune responses to vaccines. Formulation of vaccines with potent adjuvants is desirable for improving the performance of vaccines composed of antigens. Adjuvants may have diverse mechanisms of action and should be selected for use based on the route of administration and the type of immune response (antibody, cell-mediated, or mucosal immunity) that is desired for a particular vaccine

[0074] In general, immunomodulatory polypeptides include cytokines which are small proteins or biological factors (in the range of 5-20 kD) that are released by cells and have specific effects on cell-cell interaction, communication and behavior of other cells. As previously described, cytokines in accordance with the present invention are proteins that are secreted to T-cells to induce a Th1 or Th2 response. Preferably, the cytokine(s) to be administered is/are selected to reduce production of a Th2 response to antigens associated with anaphylaxis. One preferred method of reducing a Th2 response is through induction of the alternative response. Cytokines that, when expressed during antigen delivery into cells, induce a Th1 response in T cells (i.e., “Th1 stimulating cytokines”) include IL-12, IL-2, I-18, IL-1 or fragments thereof, IFN, and/or IFNγ.

[0075] Other compounds that are immunomodulatory include immunological inducing agents. These inducing agents prompt the expression of Th1 stimulating cytokines by T-cells and include factors such as, CD40, CD40 ligand, oligonucleotides containing CpG motifs, TNF, and microbial extracts such as preparations of Staphylococcus aureus, heat killed Listeria, and modified cholera toxin, etc.

[0076] Those of ordinary skill in the art readily appreciate the preferred types of adjuvants for use with particular antigen compositions. In general, immunologic adjuvant include gel-type adjuvants (e.g. aluminum hydroxide/aluminum phosphate, calcium phosphate), microbial adjuvants (e.g. DNA such as CpG motifs; endotoxin such as monophosphoryl lipid A; exotoxins such as cholera toxin, E. coli heat labile toxin, and pertussis toxin; and muramyl dipeptide), oil-emulsion and emulsifier-based adjuvants (e.g. Freund's Incomplete Adjuvant, MF59, and SAF), particulate adjuvants (e.g. liposomes, biodegradable microspheres, and saponins), and synthetic adjuvants (e.g. nonionic block copolymers, muramyl peptide analogues, polyphosphazene, and synthetic polynucleotides).

[0077] Adjuvants that are known to stimulate Th2 responses are preferably avoided. Particularly preferred adjuvants include, for example, preparations (including heat-killed samples, extracts, partially purified isolates, or any other preparation of a microorganism or macroorganism component sufficient to display adjuvant activity) of microorganisms such as Listeria monocytogenes or others (e.g., Bacille Calmette-Guerin [BCG], Corynebacterium species, Mycobacterium species, Rhodococcus species, Eubacteria species, Bortadella species, and Nocardia species), and preparations of nucleic acids that include unmethylated CpG.motifs (see, for example, U.S. Pat. No. 5,830,877; and published PCT applications WO 96/02555, WO 98/18810, WO 98/16247, and WO 98/40100, each of which is incorporated herein by reference). Other preferred adjuvants reported to induce Th1-type responses and not Th2-type responses include, for example, Aviridine (N,N-dioctadecyl-N′N′-bis(2-hydroxyethyl)propanediamine) and CRL 1005. Particularly preferred are ones that induce IL-12 production, including microbial extracts such as fixed Staphylococcus aureus, Streptococcal preparations, Mycobacterium tuberculosis, lipopolysaccharide (LPS), monophosphoryl lipid A (MPLA) from gram negative bacterial lipopolysaccharides (Richards et al. Infect Immun 1998 June;66(6):2859-65), listeria monocytogenes, toxoplasma gondii, leishmania major. Some polymers are also adjuvants. For example, polyphosphazenes are described in U.S. Pat. No. 5,500,161 to Andriavnov, et al. These can be used not only to encapsulate the microorganisms but also to enhance the immune response to the antigen.

[0078] If adjuvants are not synthesized by microorganisms in accordance with the present invention, adjuvants which are cytokines may be provided as impure preparations (e.g., isolates of cells expressing a cytokine gene, either endogenous or exogenous to the cell), but are preferably provided in purified form. Purified preparations are preferably at least about 90% pure, more preferably at least about 95% pure, and most preferably at least about 99% pure. Alternatively, genes encoding the cytokines or immunological inducing agents may be provided, so that gene expression results in cytokine or immunological inducing agent production either in the individual being treated or in another expression system (e.g., an in vitro transcription/translation system or a host cell) from which expressed cytokine or immunological inducing agent can be obtained for administration to the individual. It is recognized that microorganisms utilized to synthesize and deliver allergenic and/or immunomodulatory proteins according to the present invention can act as an adjuvant, and that preferred microorganisms are immunostimulatory adjuvants.

[0079] It will be appreciated by those of ordinary skill in the art that the inventive administration of microorganisms expressing cytokines and/or allergens may optionally be combined with the administration of any other desired immune system modulatory factor such as, for example, an adjuvant or other immunomodulatory compound.

[0080] Methods of Administration

[0081] Formulations can be delivered to a patient by any available route including for example enteral, parenteral, topical (including nasal, pulmonary or other mucosal route), oral or local administration. The compositions are preferably administered in an amount effective to elicit cellular immunity and production of Th1-related IgG while minimizing IgE mediated responses. Also preferred are compositions administered in an effective amount to active T-cell response, preferably Th1-type responses. For compositions of the present invention containing bacteria, administration is preferably delivered parenterally.

[0082] Pharmaceutical Compositions

[0083] Pharmaceutical compositions for use in accordance with the present invention may include a pharmaceutically acceptable excipient or carrier. As used herein, the term “pharmaceutically acceptable carrier” means a non-toxic, inert solid, semi-solid or liquid filler, diluent, encapsulating material or formulation auxiliary of any type. Some examples of materials which can serve as pharmaceutically acceptable carriers are sugars such as lactose, glucose, and sucrose; starches such as corn starch and potato starch; cellulose and its derivatives such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; powdered tragacanth; malt; gelatin; talc; excipients such as cocoa butter and suppository waxes; oils such as peanut oil, cottonseed oil; safflower oil; sesame oil; olive oil; corn oil and soybean oil; glycols; such as propylene glycol; esters such as ethyl oleate and ethyl laurate; agar; buffering agents such as magnesium hydroxide and aluminum hydroxide; alginic acid; pyrogen-free water; isotonic saline; Ringer's solution; ethyl alcohol, and phosphate buffer solutions, as well as other non-toxic compatible lubricants such as sodium lauryl sulfate and magnesium stearate, as well as coloring agents, releasing agents, coating agents, sweetening, flavoring and perfuming agents, preservatives and antioxidants can also be present in the composition, according to the judgment of the formulator. The pharmaceutical compositions of this invention can be administered to humans and/or to other animals, orally, rectally, parenterally, intracisternally, intravaginally, intraperitoneally, topically (as by powders, ointments, or drops), bucally, or as an oral or nasal spray.

[0084] Liquid dosage forms for oral administration include pharmaceutically acceptable emulsions, microemulsions, solutions, suspensions, syrups and elixirs. In addition to the active compounds, the liquid dosage forms may contain inert diluents commonly used in the art such as, for example, water or other solvents, solubilizing agents and emulsifiers such as ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, dimethylformamide, oils (in particular, cottonseed, groundnut, corn, germ, olive, castor, and sesame oils), glycerol, tetrahydrofurfuryl alcohol, polyethylene glycols and fatty acid esters of sorbitan, and mixtures thereof. Besides inert diluents, the oral compositions can also include agents such as wetting agents, emulsifying and suspending agents, sweetening, flavoring, and perfuming agents.

[0085] Injectable preparations, for example, sterile injectable aqueous or oleaginous suspensions may be formulated according to the known art using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable solution, suspension or emulsion in a nontoxic parenterally acceptable diluent or solvent, for example, as a solution in 1,3-butanediol. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution, U.S.P. and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil can be employed including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid are used in the preparation of injectables.

[0086] In order to prolong the effect of an agent, it is often desirable to slow the absorption of the drug from subcutaneous or intramuscular injection. This may be accomplished by the use of a liquid suspension of crystalline or amorphous material with poor water solubility. The rate of absorption of the agent then depends upon its rate of dissolution which, in turn, may depend upon crystal size and crystalline form. Alternatively, delayed absorption of a parenterally administered drug form is accomplished by dissolving or suspending the drug in an oil vehicle. Injectable depot forms are made by forming microencapsule matrices of the drug in biodegradable polymers such as polylactide-polyglycolide. Depending upon the ratio of agent to polymer and the nature of the particular polymer employed, the rate of release of the agent can be controlled. Examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides) Depot injectable formulations are also prepared by entrapping the drug in liposomes or microemulsions which are compatible with body tissues.

[0087] Compositions for rectal or vaginal administration are preferably suppositories which can be prepared by mixing the compounds of this invention with suitable non-irritating excipients or carriers such as cocoa butter, polyethylene glycol or a suppository wax which are solid at ambient temperature but liquid at body temperature and therefore melt in the rectum or vaginal cavity and release the active compound.

[0088] Solid dosage forms for oral administration include capsules, tablets, pills, powders, and granules. In such solid dosage forms, the active compound is mixed with at least one inert, pharmaceutically acceptable excipient or carrier such as sodium citrate or dicalcium phosphate and/or a) fillers or extenders such as starches, lactose, sucrose, glucose, mannitol, and silicic acid, b) binders such as, for example, carboxymethylcellulose, alginates, gelatin, polyvinylpyrrolidinone, sucrose, and acacia, c) humectants such as glycerol, d) disintegrating agents such as agar-agar, calcium carbonate, potato or tapioca starch, alginic acid, certain silicates, and sodium carbonate, e) solution retarding agents such as paraffin, f) absorption accelerators such as quaternary ammonium compounds, g) wetting agents such as, for example, cetyl alcohol and glycerol monostearate, h) absorbents such as kaolin and bentonite clay, and i) lubricants such as talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, and mixtures thereof. In the case of capsules, tablets and pills, the dosage form may also comprise buffering agents.

[0089] Solid compositions of a similar type may also be employed as fillers in soft and hard-filled gelatin capsules using such excipients as lactose or milk sugar as well as high molecular weight polyethylene glycols and the like.

[0090] The solid dosage forms of tablets, dragees, capsules, pills, and granules can be prepared with coatings and shells such as enteric coatings and other coatings well known in the pharmaceutical formulating art. They may optionally contain opacifying agents and can also be of a composition that they release the active ingredient(s) only, or preferentially, in a certain part of the intestinal tract, optionally, in a delayed manner. Examples of embedding compositions which can be used include polymeric substances and waxes.

[0091] Solid compositions of a similar type may also be employed as fillers in soft and hard-filled gelatin capsules using such excipients as lactose or milk sugar as well as high molecular weight polethylene glycols and the like.

[0092] The compounds can also be in micro-encapsulated form with one or more excipients as noted above. The solid dosage forms of tablets, dragees, capsules, pills and granules can be prepared with coatings and shells such as enteric coatings, release controlling coatings and other coatings well known in the pharmaceutical formulating art. In such solid dosage forms the active compound may be admixed with at least one inert diluent such as sucrose, lactose or starch. Such dosage forms may also comprise, as is normal practice, additional substances other than inert diluents, e.g., tableting lubricants and other tableting aids such a magnesium stearate and microcrystalline cellulose. In the case of capsules, tablets and pills, the dosage forms may also comprise buffering agents. They may optionally contain opacifying agents and can also be of a composition that they release the active ingredient(s) only, or preferentially, in a certain part of the intestinal tract, optionally, in a delayed manner. Examples of embedding compositions which can be used include polymeric substances and waxes.

[0093] Dosage forms for topical or transdermal administration of an inventive pharmaceutical composition include ointments, pastes, creams, lotions, gels, powders, solutions, sprays, inhalants or patches. The active component is admixed under sterile conditions with a pharmaceutically acceptable carrier and any needed preservatives or buffers as may be required. Ophthalmic formulation, ear drops, eye drops are also contemplated as being within the scope of this invention.

[0094] The ointments, pastes, creams and gels may contain, in addition to an active compound of this invention, excipients such as animal and vegetable fats, oils, waxes, paraffins, starch, tragacanth, cellulose derivatives, polyethylene glycols, silicones, bentonites, silicic acid, talc and zinc oxide, or mixtures thereof.

[0095] Powders and sprays can contain, in addition to the compounds of this invention, excipients such as lactose, talc, silicic acid, aluminum hydroxide, calcium silicates and polyamide powder, or mixtures of these substances. Sprays can additionally contain customary propellants such as chlorofluorohydrocarbons.

[0096] Transdermal patches have the added advantage of providing controlled delivery of a compound to the body. Such dosage forms can be made by dissolving or dispensing the compound in the proper medium. Absorption enhancers can also be used to increase the flux of the compound across the skin. The rate can be controlled by either providing a rate controlling membrane or by dispersing the compound in a polymer matrix or gel.

[0097] Encapsulation

[0098] In a preferred embodiment, inventive compositions comprising live microorganisms are provided in association with an encapsulation device (see, for example, U.S. S. No. 60/169,330 entitled “Controlled Delivery of Antigens” filed Dec. 6, 1999, incorporated by reference herewith). Preferred encapsulation devices are biocompatible, are stable inside the body so that microorganisms are not released until after the encapsulation device reaches its intended destination (e.g. mucosal lining of the gut, endocytosis by antigen-presenting cells (APC)). For example, preferred systems of encapsulation are stable at physiological pH and degrade at acidic pH levels comparable to those found in the digestive tract or endosomes of APCs. Particularly preferred encapsulation compositions include but are not limited to ones containing liposomes, polylactide-co-glycolide (PLGA), chitosan, synthetic biodegradable polymers, environmentally responsive hydrogels, and gelatin PLGA nanoparticles. Inventive compositions may be encapsulated in combination with one or more adjuvants, targeting entities, or other agents including, for example, pharmaceutical carriers, diluents, excipients, oils, etc. Alternatively or additionally the encapsulation device itself may be associated with a targeting entity and/or an adjuvant.

[0099] Methods of encapsulating live cells are known and may also be used in accordance with the present invention for delivering antigen-secreting microorganisms to individuals. The following references are provided as examples of encapsulation of live cells. However, any method of encapsulating live cells may be used in the present invention. U.S. Pat. No. 5,084,350; U.S. Pat. No. 4,680,174; and U.S. Pat. No. 4,352,883 (all of which are incorporated herein by reference) describe the encapsulation of a prokaryotic or eukaryotic cell or cell culture in microcapsules. Briefly, U.S. Pat. Nos. 5,084,350; 4,680,174; and 4,352,883 disclose that a tissue sample, cell, or cell culture to be encapsulated is first prepared in finely divided form in accordance with well-known techniques and suspended in an aqueous medium suitable for maintenance and for supporting the ongoing metabolic processes of the particular cells involved. Media suitable for this purpose generally are available commercially. Thereafter, a water-soluble substance which is physiologically compatible with the cells and which can be rendered water-insoluble to form a shape-retaining coherent spheroidal mass or other shape is added to the medium. The solution is then formed into droplets containing cells together with their maintenance or growth medium and is immediately rendered water-insoluble and gelled to form shape-retaining, typically spheroidal coherent masses.

[0100] The material used to induce gelation of the culture medium may be any non-toxic water-soluble material which, by a change in the surrounding temperature, pH, ionic environment, or concentration, can be converted to shape-retaining masses. Preferably, the material also is one which comprises plural, easily ionized groups, e.g., carboxyl or amino groups, which can react by salt formation with polymers containing plural groups which ionize to form species of the opposite charge. Use of this type of material enables the deposition of a membrane of a selected porosity range without damage to the labile cells. The presently preferred materials for forming the gelled masses are water-soluble natural or synthetic polysaccharides. Many such commercially available materials are typically extracted from vegetable matter and are often used as additives in various foods. Sodium alginate is the presently preferred water-soluble polysaccharide. Other usable materials include acidic fractions of guar gum, gum arabic, carrageenan, pectin, tragacanth gum or xanthan gums. These materials may be gelled when multivalent ions are exchanged for the acidic hydrogen or alkali metal ion normally associated with the carboxyl groups.

[0101] Uses

[0102] The compositions of the present invention may be employed to treat or prevent allergic reactions in a subject. Subjects are animal and human patients in need of treatment for allergies. Preferably, the animal is a domesticated mammal (e.g., a dog, a cat, a horse, a sheep, a pig, a goat, a cow, etc). Animals also include laboratory animals such as mice, rats, hamsters, monkeys, and rabbits. Any individual who suffers from allergy, or who is susceptible to allergy, may be treated. It will be appreciated that an individual can be considered susceptible to allergy without having suffered an allergic reaction to the particular antigen in question. For example, if the individual has suffered an allergic reaction to a related antigen (e.g., one from the same source or one for which shared allergies are common), that individual will be considered susceptible to allergy to the relevant antigen. Similarly, if members of an individual's family are allergic to a particular antigen, the individual may be considered to be susceptible to allergy to that antigen. More preferably, any individual who is susceptible to anaphylactic shock upon exposure to food allergens, venom allergens or rubber allergens may be treated according to the present invention.

[0103] The compositions of the present invention may be formulated for delivery by any route. Preferably, the compositions are formulated for injection, ingestion, or inhalation.

[0104] Modifications and variations of the methods and compositions described herein are intended to be within the scope of the following claims.

[0105] Other Embodiments

[0106] Those of ordinary skill in the art will readily appreciate that the foregoing represents merely certain preferred embodiments of the invention. Various changes and modifications to the procedures and compositions described above can be made without departing from the spirit or scope of the present invention, as set forth in the following claims.

EXAMPLES

[0107] Material and Methods

[0108] For general methods used to express proteins in microorganisms see Ausubel et al. (supra) and Sambrook et al. (supra) both of which are incorporated herein by reference. In addition, expression vectors for use in the present invention are widely available from commercial sources (see for example, Clontech, Palo Alto, Calif.; Invitrogen, Carlsbad, Calif.; Promega Corporation, Madison, Wis.; New England Biolabs, Beverly, Mass.).

[0109] The following experiments describe the encapsulation of allergens in bacteria for use as a delivery vehicle and/or adjuvant in immunotherapy in accordance with the teachings of the present invention. Recombinant peanut allergen proteins (Ara h 1, Ara h 2, and Ara h 3; Burks et al. J Allergy Clin Immunol. 88(2):172-9, 1991; Burks et al. J Allergy Clin Immunol. 90(6 Pt 1):962-9, 1992; Rabjohn et al. J Clin Invest. 103(4):535-42, 1999; incorporated herein by reference) were produced in E. coli BL21 cells by transforming the bacterial cells with cDNA clones encoding the proteins (see Appendix B; sequences cloned into pET24, Novagen, Madison, Wis.). The transformed cells were then injected into C3H/HEJ mice to determine if the allergen-expressing E. coli elicited an immune response.

Example 1

Methods of Killing Allergen-Producing E. coli

[0110] Several methods of killing allergen-producing E. coli were tested. Preferably, the method of killing bacteria does not denature or proteolyze the recombinant allergen(s) produced by the bacteria. As non-limiting examples, E. coli were killed by heat (at temperatures ranging from 37° C. to 95° C.), by using ethanol (0.1% to 10%), and by using solutions containing iodine (0.1% to 10%). Survival was determined by plating 100 μl of cells onto the appropriate agar plates, and subsequently counting the resulting colonies. The most reproducible method was heat killing. Therefore, the preferred method of killing allergen-producing E. coli is to incubate the cells at 60° C. for 20 minutes which results in 100% death (i.e. no colonies formed; see Figure #).

Example 2

Growth of Bacteria

[0111] The following protocol was developed for the preparation of allergen-producing E. coli cells for inoculation of mice.

[0112] Day 1

[0113] Five milliliters (ml) of liquid cultures of LB (Luria-Bertani broth) containing kanamycin (30 micrograms/ml per each cell line used) were prepared in 50 ml sterile tubes or flasks. Cultures were inoculated with approximately 10 microliters from a frozen stock of the desired bacterial cell line containing the desired expression vectors. The inoculated cultures were incubated with shaking overnight at 37° C.

[0114] Day 2

[0115] The following morning, 100 ml of liquid LB (500 ml Erlenmeyer flask) containing kanamycin (30 micrograms/ml) were inoculated using a 1 ml aliquot from the 5 ml culture grown from the previous day. (The remaining 4 mls of culture were frozen. Optionally, the remaining 4 milliliters of culture can be stored at 4° C. for several weeks for inoculating subsequent cultures) The inoculated cultures were incubate with shaking at 37° C. until the optical density of the solution measured at 600 nM (OD 600) reached approximately 0.6 to 0.9.

[0116] Day 3

[0117] To induce production of recombinant proteins, the cultures from the previous day were induced by adding isopropyl-beta-D-thiogalactopyranoside (IPTG; Sigrna-Aldrich, St. Louis, Mo.) from a 1 M stock to a final concentration of 1 mM (100 microliters of 1 M IPTG per 100 mls of culture) when the OD 600 of the culture reached approximately 0.6-0.9. The induced cultures were incubated overnight.

[0118] Day 4

[0119] 1.4 ml of culture from the previous day were aliquoted into each of five 1.5 ml microfuge tubes for each culture and heat killed at 60° C. in a water bath for 20 minutes. The tubes were centrifuged at 16,000×g for 5 minutes at room temperature and the supernatant discarded. The pellets were washed with 1× phosphate buffer saline (PBS) and centrifuged at 16,000×g for 5 minutes at room temperature. Again, the supernatant was discarded and the pellets were resuspended in 250 microliters of 1×PBS. The resuspended pellets from the same original samples were combined. The OD 600 were determined for each sample and diluted to the desired OD 600 using 1×PBS.

Example 3

Production and Release of Allergen.

[0120] Release of Allergen by Heat-Killed Bacteria

[0121] In order to determine if the cells remained intact after heat-killing we measured the amount of allergen released into the media. A dot-blot assay was developed that utilized as controls, purified recombinant allergens applied to a filter at known concentrations and serum IgE from peanut sensitive patients. The assay detected and quantified the amount of allergen present in 100 microliters of supernatant after pelleting heat-killed bacteria. The level of allergen released varied and was dependent on the expression vector and protein tested. In general, more Ara h 2 was released than Ara h 1 and Ara h 3 (Ara h 2>>Ara h 1>Ara h 3).

[0122] Production of Allergen.

[0123] In order to measure amounts of allergen in E. coli, we developed an immunoblot assay that utilizes a six histidine tag (HIS tag) that is present on all of our purified recombinant allergens and a HIS tag antibody to build a standard curve that could then be used to estimate amounts of allergen produced. The amount of allergen produced on a per cell basis varied depending on which clone was tested. In general, more Ara h 3 was produced than Ara h 2 and Ara h 1 (Ara h 3>Ara h 2>>Ara h1).

[0124] Our best estimates for amounts of allergen delivered in 100 μl of a 2.0 O.D. inoculum of E. coli varies from about 1 μg of Ara h 1 to about 20 μg of Ara h 3.

[0125]
FIG. 2 is an example of a standard curve generated for Ara h 2. The optical density (O.D.) of the HIS-tagged Ara h 2 allergen is then determined from an immunoblot where different concentrations of E. coli extract has been electrophoresed on SDS-PAGE gels. The allergen O.D. is then used to estimate the amount of protein produced by that extract.

Example 4

Immune Response of Mice

[0126] The following protocol was utilized to determine the immune response of mice injected with allergen-producing bacteria. Blood was collected from the tail vein of each mouse used before the first injection. Enough blood was collected for antibody ELISA for each allergen and E. coli proteins. On Day Zero each mouse was injected with 100 microliters of the killed E. coli samples subcutaneously in the left hind flank. The mice were injected for the second time on Day 14 using the same procedure as Day Zero. On Day 21, a second blood sample was collected from each mouse. Blood samples at Day 0 and Day 21 were assayed for IgG1 and IgG2a antibodies to either Ara h 1, Ara h 2, or Ara h 3 by an ELISA assay.

[0127] Mice injected with E. coli producing Ara h 1 did not give detectable levels of any immunoglobulin to the Ara h 1 allergen and therefore, that data are not shown. Without limitation to theory, we speculate that this may be due to the relatively small amounts of Ara h 1 produced by these cells (see previous discussion). Mice injected with E. coli producing Ara h 2 contained relatively high levels of IgG1 and IgG2a. Again, without limitation to the cause, we speculated that this may be due to the amount of Ara h 2 released from these cells (see discussion above). Mice injected with E. coli producing Ara h 3 contained relatively high levels of IgG2a (indicative of a Th1-type response) and elicited relatively low levels of IgG1 (indicative of a Th2-type response.

[0128] Interpretation of Results

[0129] The present data should be cautiously interpreted. The data in the Figures only represent O.D. levels and do not represent absolute amounts of immunoglobulin. Therefore comparisons between groups should take into consideration the data presented as O.D. However, the general trend suggests that for example, more mice exhibited an IgG2a response to Ara h 3 than mice that exhibit an IgG1 response to Ara h 3.

	Number	Date	Country
Parent	09731375	Dec 2000	US
Child	10728323	Dec 2003	US

Microbial delivery system

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