Patent Application
20090318413
Throughout this application, various references or publications are cited. Disclosures of these references or publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.
This invention relates to the field of treatment for asthma.
Asthma and chronic obstructive pulmonary disease (COPD) are inflammatory airway diseases that are characterized by different patterns of airway remodeling (1). Nevertheless, the decrease in lung function that characterizes both diseases is associated with an increased mass of bronchial smooth muscle (BSM) (2, 3), which is likely to be the most important abnormality responsible for the airway narrowing observed in response to bronchoconstricting stimuli (4). The mechanisms underlying such remodeling of smooth muscle remain largely unknown.
On the one hand, in smooth muscle from asthmatic patients, excessive in vitro proliferation of BSM cells has been demonstrated (5-7). In addition, decreased apoptosis of BSM cells has also been demonstrated, although this was in a rat model of experimental asthma (7). On the other hand, in COPD, smooth muscle remodeling appears limited to airways distal to the fourth generation (3, 8). Although an increase in TGF-α1 production by BSM cells has been proposed, such localization and the complete mechanism remain unexplained (9). Whatever its cause, BSM remodeling is poorly sensitive to current therapeutics in both asthma and COPD.
Mitochondria play a major role in both cell proliferation and apoptosis (10, 11). In cancer, for instance, targeting of mitochondrial function and mitochondrial anti-apoptotic protein bcl-2 has been used to either suppress the proliferation of tumor cells (10) or induce cell apoptosis in solid tumors (12). Mitochondria are also involved in other diseases, such as neuron-degenerative diseases (11). However, their role in asthma or COPD remains to be investigated.
It was discovered that asthmatic BSM was characterized by an increased mitochondrial biogenesis that, in turn, enhanced cell proliferation. Mitochondria were identified as new target for the treatment of asthmatic smooth muscle remodeling. The Applicant has developed drugs interacting with mitochondrial biogenesis, including drugs acting at the site of calcium homeostasis, for preventing and/or reversing BSM remodeling in asthma.
The present invention thus provides a method of inhibiting bronchial smooth muscle remodeling in asthma, comprising the step of administering to a subject having asthma an agent that inhibits calcium-dependent mitochondrial biogenesis. In one embodiment, the agent inhibits calcium influx in bronchial smooth muscle cells. In another embodiment, the agent inhibits proliferation of bronchial smooth muscle cells. In yet another embodiment, the agent is a calcium channel blocker. Examples of calcium channel blocker include, but are not limited to, gallopamil verapamil, devapamil, emopamil, nifedipine, nicardipine, diltiazem and salt thereof.
The present invention also provides a method of inhibiting bronchial smooth muscle remodeling in asthma, comprising the step of administering to a subject having asthma an agent that inhibits cellular signaling of calcium-dependent mitochondrial biogenesis. In one embodiment, the agent inhibits expression or function of signaling molecule involved in calcium-dependent mitochondrial biogenesis. Examples of signaling molecule include, but are not limited to, mitochondrial transcription factor A, nuclear respiratory factor-1, peroxisome proliferatorαactivated receptor α coactivator—1α, and calcium/calmodulin-dependent protein kinase IV. In one embodiment, the expression or function of the signaling molecule can be inhibited at the protein, DNA or RNA level.
The present invention also provides a pharmaceutical composition for inhibiting bronchial smooth muscle remodeling in asthma, comprising a therapeutically active amount of an agent that inhibits calcium-dependent mitochondrial biogenesis in asthmatic bronchial smooth muscle cells and a pharmaceutically acceptable vehicle. According to this embodiment, the agent is present and administered in an amount sufficient to inhibit calcium influx in asthmatic bronchial smooth muscle cells. Alternatively, the amount of agent is present and administered in an amount sufficient to inhibit cellular signaling of calcium-dependent mitochondrial biogenesis. In one embodiment, the agent inhibits expression or function of signaling molecule involved in calcium-dependent mitochondrial biogenesis. Examples of signaling molecule include, but are not limited to, mitochondrial transcription factor A, nuclear respiratory factor-1, peroxisome proliferator-activated receptor coactivator-1α, and calcium/calmodulin-dependent protein kinase IV. In one embodiment, the expression or function of the signaling molecule can be inhibited at the protein, DNA or RNA level.
The present invention provides a method of inhibiting bronchial smooth muscle remodeling in asthma, comprising the step of administering to a subject having asthma a therapeutically active amount of an agent that inhibits calcium-dependent mitochondrial biogenesis. The present invention also provides a pharmaceutical composition for inhibiting bronchial smooth muscle remodeling in asthma comprising a therapeutically effective amount of an agent that inhibits calcium-dependent mitochondrial biogenesis and a pharmaceutically acceptable vehicle.
In one embodiment, the agent inhibits calcium influx in bronchial smooth muscle cells or inhibits proliferation of bronchial smooth muscle cells. In another embodiment, the agent is a calcium channel blocker. Examples of calcium channel blocker include, but are not limited to, gallopamil verapamil, devapamil, emopamil, anipamil, nifedipine, nicardipine, diltiazem, or salts thereof. Currently, 3 classes of calcium channel blockers in multiple immediate or sustained-release preparations are available in the United States. These classes are as follows: phenylalkylamines (e.g., gallopamil, verapamil), benzothiazines (e.g. diltiazem), and dihydropyridines (e.g. nifedipine, amlodipine). Calcium channel blockers function by binding to the L-subtype, voltage-sensitive, slow calcium channels in cell membranes, thereby decreasing the flow of calcium into the cell. Each calcium channel blocker has a certain degree of tissue specificity, but they do have common properties. They are all absorbed early in the GI system, are substantially bound by plasma proteins, and are predominantly metabolized by the liver.
The pharmaceutical compositions according to the present invention include the formulations that are suitable for any desired administration, including but not limited to, oral, parenteral, including subcutaneous, intradermal, intramuscular, intravenous and intraarticular, rectal and topical, including dermal, buccal, sublingual and intraocular administration, or by inhalation via a dose inhaler or nebulization.
The present invention also provides a method of inhibiting bronchial smooth muscle remodeling in asthma, comprising the step of administering to a subject having asthma an agent that inhibits cellular signaling of calcium-dependent mitochondrial biogenesis. The present invention also provides a pharmaceutical composition for inhibiting bronchial smooth muscle remodeling in asthma comprising a therapeutically effective amount of an agent that inhibits cellular signaling of calcium-dependent mitochondrial biogenesis and a pharmaceutically acceptable vehicle.
In one embodiment, the agent inhibits expression or function of signaling molecule involved in calcium-dependent mitochondrial biogenesis. Examples of signaling molecule include, but are not limited to, mitochondrial transcription factor A, nuclear respiratory factor-1, peroxisome proliferator-activated receptor coactivator-1α, and calcium/calmodulin-dependent protein kinase IV. In one embodiment, the expression or function of the signaling molecule can be inhibited at the protein, DNA or RNA level.
The present invention also provides a method of treating asthma comprising the step of administering to a subject having asthma a therapeutically effective dose of an agent that inhibits calcium-dependent mitochondrial biogenesis in asthmatic bronchial smooth muscle cells. The treated subject can be a patient, preferably a human patient, with severe asthma or non severe asthma (where remodeling of smooth muscle has just started). In one embodiment, the agent that inhibits calcium-dependent mitochondrial biogenesis is a calcium channel blocker such as gallopamil verapamil, devapamil, emopamil, anipamil, nifedipine, nicardipine, diltiazem, or salts thereof.
A therapeutically effective dose or amount of an agent is intended to mean an amount or a proportion thereof sufficient to inhibit calcium influx in bronchial smooth muscle cells and/or to inhibit proliferation of bronchial smooth muscle cells, and/or inhibit cellular signaling of calcium-dependent mitochondrial biogenesis, and/or inhibit expression or function of signaling molecule involved in calcium-dependent mitochondrial biogenesis.
The agent as described above may be administered to the subject via various following routes of administration, such as oral, parenteral, including subcutaneous, intradermal, intramuscular, or intravenous, rectal and topical, including dermal, buccal, sublingual or by inhalation.
While it may be possible for the agents of the invention to be administered as the raw chemical, it is preferable to provide them as a pharmaceutical composition, for any of the disorders described herein. According to a further aspect, the present invention provides a pharmaceutical composition comprising a therapeutically effective amount of the agent of the invention or a pharmaceutically acceptable salt, together with one or more pharmaceutically acceptable vehicle thereof and optionally one or more other therapeutic ingredients for indications such as asthma.
One of ordinary skill in the art would readily determine a suitable treatment schedule. In one embodiment, a subject or patient can be treated with 70 mg to 150 mg or 100 mg tablets of a calcium channel blocker such as gallopamil twice a day for 12 months, or 6 months, 8 months, 10 months, 14 months, or up to 24 months. According to the IUPAC designation, gallopamil corresponds to 5-[2-(3,4-dimémethoxyphenyl)ethyl-methylamino]-2-propan-2-yl-2-(3,4,5-triméthoxyphenyl)pentanenitrile hydrochloride, and is known under ATC code C08DA02. Also, gallopamil is marketed under PROCORUM® by Abbott, e.g., 50 mg or 100 mg tablets, wherein the active substance according to the DCI designation is gallopamil hydrochloride or methoxyverapamil or D600. Such tablets comprise microcrystalline cellulose, sodium alginate, povidone, magnesium stearate, and purified water, as excipients.
In a preferred embodiment, the calcium channel blocker such as gallopamil is administered in a sufficient therapeutic amount to obtain (i) 5-50%, 5-40%, 5-30%, 5-20%, or 5-15% decrease of asthmatic smooth muscle remodeling; or (ii) 5-50%, 5-40%, 5-30%, 5-20%, or 5-15% decrease of bronchial thickness assessed by 3D analysis of computed tomography; or (iii) a control of asthma according to the questionnaire (ACQ) validated by Juniper; or (iv) a reduction of BSM mitochondrial number and activity assessed by electronic microscopy, oxygraphy, or Western blot.
In another preferred embodiment, treatment with an agent that inhibits calcium-dependent mitochondrial biogenesis as described above can be combined with standard care therapy for asthma. For example, one standard therapy for asthma comprises 2 treatments: (1) inhaled corticosteroids such as beclomethasone (2000 pg/day equivalent), or budesonide (64 μg/dose) marketed under Rhinocort®, or fluticasone, and (2) LABA (Long acting beta 2 agonists) (200 μg/day equivalent), such as formoterol or salmeterol, and optionally a third one which is an oral corticoid such as prednisolone.
The present invention is based on the discovery that both asthma and COPD are by BSM remodeling, a specific mitochondria-dependent pathway is required for BSM proliferation only in asthma. This pathway is initiated by an altered calcium homeostasis, upon the activation of asthmatic BSM cells. Proliferation of BSM in both health and COPD was found to be, at the very least, less mitochondria dependent. The Applicant has thus characterized mitochondria as being a specific new therapeutic target in airway remodeling in asthma.
Special attention was paid when comparing data from severe asthmatics to that of COPD patients because both diseases have been shown to present smooth muscle remodeling (2, 3, 17). Using a variety of different experimental approaches, it was discovered that asthmatic BSM expressed a higher number of active mitochondria and a clear aspect of intense mitochondrial biogenesis. The Applicant has then assessed mitochondrial mass using various parameters, including the number of mitochondria by electron microscopy both ex vivo and in vitro, the mitochondrial network by confocal microscopy, and the porin content by Western blot. All of these methods have provided consistent results. Significant correlations were also found between in vitro BSM porin content, which was a relevant quantitative estimate of mitochondrial mass, and both the duration of the disease and the FEV1/FVC ratio within the asthmatic population. On the one hand, the longer the duration of the disease that was known to favor airway remodeling (18), the higher the mitochondrial mass, and on the other hand, the lower the FEV1/FVC ratio, which also reflected airway remodeling, the higher the mitochondrial mass. Moreover, to obtain a comprehensive assessment of mitochondrial content, the expression level of mtTFA was measured by both quantitative RT-PCR and Western blot to assess mitochondrial respiratory chain content, as mitochondrial overall content and respiratory chain content were not always linked (19).
The increased number of mitochondria was limited to asthmatic BSM cells compared with endothelial and epithelial cells from asthmatic, COPD, or control subjects. However, two characteristics of such asthmatic populations deserve further comment. First, the Applicant has found that it was unlikely that asthma treatments interfered with the observed changes because, on the one hand, 9/17 COPD patients took treatments similar to that of asthmatics, and, on the other hand, no difference has been found between controls and COPD. Second, the younger mean age of the asthmatic population was unlikely to contribute to this increase in mitochondrial content because (a) this increase persisted when comparing asthmatics to a subgroup of nonsmoking controls whose mean age was similar, and (b) in skeletal muscle, if not any other muscle, age does not influence mitochondrial content (20). Such mitochondrial characteristics in any type of smooth muscle cells with potential pathophysiological implications was never previously characterized and described. It has been previously reported that in a variety of differentiated tissues, a mitochondrial dysfunction increases mitochondrial biogenesis, suggesting a cellular compensatory mechanism (21). However, no mitochondrial dysfunction was reported in the case of asthmatic patient because the respiration of asthmatic BSM mitochondria was efficiently coupled. Similarly, artificial activation of mitochondrial biogenesis of mouse neonatal cardiac myocytes largely induced a coupled respiration (22).
Many factors may control mitochondrial biogenesis. PGC-1α is a well-known master activator of mitochondrial biogenesis through the production of both NRF-1 and mtTFA in various cell types, including myoblast (23), fibroblast, or adipocytes (24). To this regard, the Applicant has demonstrated that such a cascade was activated in asthmatic BSM cells, as shown by the concomitant up-regulation of PGC-1α, NRF-1, and mtTFA. Moreover, cyclic GMP has been shown to activate PGC-1α and mitochondrial biogenesis in various cell lines, including U937, L6, and PC12 (16, 25). It was observed that cyclic GMP induces mitochondrial biogenesis in both control and COPD BSM cells, but not in asthmatic BSM cells. These findings suggested that mitochondrial biogenesis in asthmatic BSM cells may already be up-regulated. In this connection, cyclic GMP also improved cell proliferation of control and COPD BSM cells, but not those of asthmatics. It could be argued that cyclic GMP regulates many different genes in smooth muscle, such as vascular smooth muscle (26). However, cyclic GMP has been shown to inhibit, rather than enhance, the proliferation of vascular smooth muscle cells, as well as that of mesangial cells and various fibroblasts (26). In addition, direct improvement of mitochondrial biogenesis by transgenic overexpression of PGC-1α activated skeletal muscle atrophy (27) and cardiac muscle dysfunction (22). Conversely, cyclic GMP increased the proliferation of endothelial cells, but the role of mitochondria in this phenomenon has never been so far (28).
PGC-1α activation can be calcium-dependent (29). The Applicant has discovered that CaMK-IV was more phosphorylated in asthmatic BSM cells than in both controls and COPD. Rises in calcium concentration have been previously shown to activate CaMK-IV in other cell types, including skeletal muscle cells (29) or osteoclasts (30). Interestingly, the Applicant has demonstrated that calcium homeostasis in asthmatic BSM cells was altered, thus providing a mechanistic explanation for the increased activation of calcium-dependent signaling enzymes such as CaMK-IV (31). A gallopamil (D600) sensitive calcium influx was suspected to account for such asthma-induced alteration in calcium homeostasis. The Applicant evidenced that this calcium influx was the initial priming event because, when blocked, mitochondrial biogenesis and subsequent asthmatic BSM cell-increased proliferation was inhibited. Thus blockage of such influx was predicted to be beneficial. Previous studies using methoxyverapamil (gallopamil) were focused on short-term effects for up to 4 wk and did not show airway remodeling (32, 33).
Finally, mitochondria-deficient BSM cells were generated by depletion of mitochondrial DNA with ethidium bromide, which is a potent inhibitor of mitochondrial DNA replication and transcription (10, 15). Mitochondria-deficient BSM cells from asthmatics were unable to proliferate, thereby confirming the importance of mitochondria in asthmatic BSM cell proliferation. Thus, the increased mitochondrial biogenesis observed in asthmatic BSM cells appeared to be a cause rather than a consequence of the asthmatic BSM cell increased proliferation. However, it was well known that training can increase mitochondrial biogenesis in skeletal muscle (34). It was unlikely that a similar phenomenon appears to the BSM from asthmatics. In this study, none of the asthmatics presented recent exacerbations, and all of these patients were treated by relaxant 2 agonists.
As described herein above, the pharmaceutical compositions according to the present invention include the formulations that are suitable for any desired administration, including but not limited to, oral, parenteral, including subcutaneous, intradermal, intramuscular, intravenous and intraarticular, rectal and topical, including dermal, buccal, sublingual and intraocular administration, or by inhalation via a dose inhaler or nebulization.
The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art of pharmacy. All methods include the step of bringing into association an agent of the invention or a pharmaceutically acceptable salt with the carrier or vehicle which constitutes one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both and then, if necessary, shaping the product into the desired formulation.
Formulations of the present invention suitable for oral administration may be presented as discrete units such as capsules or tablets each containing a predetermined amount of the agent as described above; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous liquid; or as an oil-in-water liquid emulsion or a water-in-oil liquid emulsion. The active agent may also be presented as a bolus, electuary or paste.
A tablet may be made by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, lubricating, surface active or dispersing agent. Molded tablets may be made by molding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active agent therein.
Formulations for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain anti-oxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. The formulations may be presented in unit-dose or multi-dose containers, for example sealed ampuls and vials, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example, saline, water-for-injection, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.
Formulations for rectal administration may be presented as a suppository with the usual carriers such as cocoa butter or polyethylene glycol.
Formulations for topical administration in the mouth, for example buccally or sublingually, include lozenges comprising the active ingredient in a flavored basis such as sucrose and acacia or tragacanth, and pastilles comprising the active ingredient in a basis such as gelatin and glycerin or sucrose and acacia.
The invention being generally described, will be more readily understood by reference to the following examples which are included merely for purposes of illustration of certain aspects and embodiments of the present invention, and are not intended to limit the invention.
The clinical characteristics of all subjects are shown in Table 1. All of the 14 severe persistent asthmatics were lifelong nonsmokers and received stable treatments, including oral or inhaled corticosteroids and β32 agonists. Ten of them were atopic. The 17 moderate to severe chronic obstructive pulmonary disease (COPD) patients were either current or former smokers, and 9 of them received stable treatments, including oral or inhaled corticosteroids and/or β2 agonists. None of the asthmatic or COPD patients experienced a recent (<3 mo) exacerbation of the disease. The mean duration of the disease in asthmatic and COPD patients was 26±4.6 and 18±2.8 yr, respectively. Of the 19 control subjects who received no treatment, 8 of them were lifelong nonsmokers, whereas 11 were former smokers.
Asthmatic patients were enrolled using the following inclusion criteria. Patients >18 yr had to exhibit characteristic symptoms (i.e. wheezing and breathlessness), as well as bronchial hyper-responsiveness confirmed either by a significant improvement by >15% in the forced expiratory volume in 1 s (FEV1) 10 min after the inhalation of 200 μg of salbutamol, or a provocative concentration of methacholine required to lower the FEV1 by 20% (PC20) of <4 mg/ml according to the American Thoracic Society criteria. Patients must all be graded as severe persistent asthmatics according to the Global Initiative for Asthma guidelines based on both clinical features and daily medication regimen. All patients must also be lifelong nonsmokers with no recent exacerbation (<3 mo). Exclusion criteria were recent bacterial or viral infections (<3 mo).
COPD patients were enrolled using the following inclusion criteria. Patients >18 yr had to present chronic symptoms (i.e. cough and breathlessness) and poorly reversible airflow obstruction defined by both an improvement of <10% in the FEV1 10 min after the inhalation of 200 μg of salbutamol or ipratropium bromide, and a postbronchodilator FEV1/forced vital capacity ratio <70% according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. Patients must be graded as moderate to severe COPD according to the GOLD guidelines. Exclusion criteria were recent bacterial or viral infections (<3 mo).
Control subjects were enrolled using the following inclusion criteria. Subjects >18 yrs had to have normal lung function test and have underwent a fiberoptic fibroscopy or a thoracotomy because of hemoptysis or abnormal image on x ray. They must be asymptomatic without any treatment, and only those in whom fiberoptic investigation and bronchial mucosa were normal were selected as controls. Exclusion criteria were any co-morbidity, such as asthma or COPD, and recent bacterial or viral infections (<3 mo).
The study followed recommendations outlined in the Helsinki Declaration and received approval from the local ethics committee.
Bronchial specimens were obtained by either fiberoptic bronchoscopy or lobectomy, as previously described (Berger et al., FASEB J. 17:2139-2141 (2003); El-Shazly et al., J. Immunol. 176:1860-1868 (2006)). Fiberoptic bronchoscopy was performed after the anesthesia of the upper airways was achieved with lidocaine 10% spray. The fiberoptic bronchoscope (FB-5V; Pentax) was introduced, and biopsies were taken from various bronchial carinae from the middle lobe.
Because the smooth muscle remodeling in both asthma and COPD occurred at two different bronchial localizations, asthmatic bronchial specimens were thus collected from the third to the fourth generation, those from COPD patients from the fourth to the sixth generation and those from control subjects were collected from the third to the sixth generation. Specimens were immediately transferred to the laboratory in a sterile container containing DME.
Bronchial specimens were fixed in 10% buffered formalin and processed in standard fashion for paraffin embedding. Three μm-thick sections were cut and stained with hematoxylin-eosin-safran or processed for immunohistochemistry. After deparaffinization and rehydratation through graded alcohols, endogenous peroxidase was inhibited using a solution of 0.1% sodium azide and 0.3% hydrogen peroxide for 30 min, followed by two rinses in PBS (Invitrogen). Nonspecific staining was blocked using 10% BSA (Dako) for 30 min. Sections were incubated for 2 h at room temperature with mouse anti-human smooth muscle actin (clone 1A4) or an unrelated mouse antibody (both from Sigma-Aldrich). After rinsing in PBS, biotinylated rabbit anti-mouse F(ab′)2 (Dako) was applied to the sections for 2 hours, followed by the streptavidin-biotinylated horseradish peroxidase complex (Dako) for an additional 2 hours. After rinsing in PBS, 1 mg/ml 3,3′-diaminobenzidine tetrahydrochloride (Dako), plus 0.02% hydrogen peroxide for 6 min, were used as substrate to develop a peroxide-dependent brown color reaction at room temperature. Finally, the sections were rinsed and counterstained with Mayer's hematoxylin. There was assessable BSM in the bronchial specimens from all 14 asthmatics, 17 COPD patients, and 19 controls. The total area of smooth muscle layer was assessed manually in a blinded fashion using ScanView software (Soft Imaging System) at a magnification of 200×. This smooth muscle area was normalized by the whole area of the corresponding tissues and presented as percentages of whole area.
Specimens were fixed in 2.5% glutaraldehyde in cacodylate buffer, postfixed in 1% osmium tetroxide, dehydrated, and embedded in epon. For each specimen, semithin sections (1 μm thick) were cut and stained with alkaline toluidine blue. The first semithin section large enough to span from the epithelium to the muscular layer was selected. Ten ultrathin serial sections (60 nm thick) were then cut on diamond knives. Three of these latter sections were subsequently randomly selected and placed on grids. Staining was performed with uracile acetate and lead citrate. Grids were then scanned by transmission electron microscopy (Tecnai 12; Philips) and examined by a pathologist from left to right and from top to bottom to locate every whole nucleated BSM, epithelial, and endothelial cell. Each ultrathin section was examined in its entirety. To evaluate the number of mitochondria, computerized photographs and measurements were performed in a blinded fashion by using ScanView software at a standard magnification of 6,000×. Mitochondrial densities were performed using Image J 1.34s free software (National Institutes of Health).
Primary cultures of BSM cells were established from bronchial specimens. After a fine dissection under a microscope, smooth muscle explants were cultured in six-well plates in a humidified atmosphere at 37° C. with 5% CO2. Cells were maintained in sterile DME containing 10% (vol/vol) FCS and 4.5 g/liter glucose, supplemented with 2 mM 1-glutamine, 100 U/ml penicillin, 100 mg/ml streptomycin, and 0.25 mg/ml amphotericine B (antimycotic/antibiotic solution; all from Invitrogen), 1 mM sodium pyruvate, and 1% (vol/vol) nonessential amino acid mixture (both from Sigma-Aldrich). The medium was changed every 48-72 h. After 6-8 wk, confluent cells were rinsed twice with HBSS and passaged with trypsin-EDTA (both from Invitrogen).
To assess purity of the cells, an immunocytochemical method was used, using an indirect immunofluorescence technique. Cells of varying passage number were growth arrested by incubating the cells with serum-free DME supplemented with 10 μg/ml insulin, 5.5 μg/ml transferrin, 5 ng/ml selenium, 0.5 μg/ml BSA, and 4.7 μg/ml linoleic and oleic acid (ITS solution; Sigma-Aldrich). After 48 h, cells were rinsed twice in PBS and fixed with cold methanol for 20 min. Nonspecific staining was blocked using PBS containing 3% BSA for 30 min. Monoclonal antibodies (mAb) diluted in PBS with 1% BSA, including anti-α-smooth muscle actin (Sigma-Aldrich), anti-smooth muscle myosin (Sigma-Aldrich), anti-cytokeratin 18 (Sigma-Aldrich), and anti-factor VIII (Dako) were incubated for 1 h. Control slides were treated similarly, using an unrelated antibody (mouse IgG; Sigma-Aldrich). After rinsing with PBS containing 0.05% Tween20 (Sigma-Aldrich), the cells were incubated for 1 h with FITC-conjugated anti-mouse immunoglobulins (Dako). Slides were mounted with a drop of fluorescent mounting medium (Dako) and observed under a fluorescence microscope (Nikon). Depending on the experiments, cells with a confirmed smooth muscle phenotype were seeded on coverslips, chamber slides, 75-cm2 culture flasks, and 6-, 12-, or 96-well plates. Only cells at passage 2 to 4 were used for this study.
To analyze the mitochondrial ultrastructure, BSM cells were growth arrested, as described in the previous section, for 6 d. Three million cells were then collected and centrifuged at 400 g for 5 min. Cell pellets were fixed in 2.5% glutaraldehyde for 2 h at 4° C. and processed for electron microscopy, as described in the previous section. Growth curves were built to assess the role of mitochondria in cell proliferation. For this purpose, 25,000 BSM cells were plated on 75-cm2 flasks and cultured with 10% FCS-DME containing either 4.5 g/liter galactose or 4.5 g/liter glucose. In another set of experiments, we investigated the effects of 50 μg/liter ethidium bromide (Qbiogene) for up to 33 d, 1.3 g/liter cyclic cGMP (3 mM; Sigma-Aldrich) for up to 6 d, or 0.5 g/liter D600, i.e., methoxyverapamil or gallopamil (1 μM; Sigma-Aldrich) for up to 2 d in 10% FCS-DME containing 4.5 g/liter glucose. For these latter experiments, medium was changed every 24 h, and, at the indicated time, BSM cells were harvested by trypsinization and counted in triplicate using a cytometer.
Whole lysates from BSM cells were collected using 1% Triton X-100 lysis buffer in the presence of 2 mM Na orthovanadate, 1 mM EDTA, 50 μg/ml aprotinin, 100 μM leupeptin, 1 mM 1.4 Dithio-DL-Treitol, and 1 mM amino-ethyl-benzenesulfonyl fluoride hydrochloride (all from Sigma-Aldrich). Cellular extracts were reduced with mercaptoethanol, subjected to electrophoresis on a 10% acrylamide reducing gel, and transferred to PVDF membranes (Immobilon TM-P; Millipore). The immunoblots were then developed using mouse anti-human porin (MitoSciences), mouse anti-human α-actin (Sigma-Aldrich), rabbit anti-human phospho-CaMK-IV, rabbit anti-human PGC-1α, rabbit anti-human NRF-1, or rabbit anti-human mitochondrial transcription factor A (mtTFA; all purchased from Santa Cruz Biotechnology, Inc.) for 14 h at 4° C. For amplification, biotinylated goat secondary antibody anti-mouse IgG (Bio-Rad Laboratories) or anti-rabbit IgG (Santa Cruz Biotechnology, Inc.) for 2 h at room temperature and a streptavidin-biotinylated horseradish peroxidase complex (Dako) were used. Immunoblots were revealed by enhanced chemiluminescence (Uptima). Blot images were acquired using BioCaptMW (Thermo Fisher Scientific), and band densities were quantified using ImageJ software.
Endogenous cellular oxygen consumption was monitored on intact cells at 37° C. in a 1-ml thermostatically controlled chamber (106 cells/ml/run) equipped with a Clark oxygen electrode (Oxygraph System; Hansatech). The respiratory buffer was the glucose or the galactose culture medium described in Cell culture. The endogenous respiratory rates were expressed in ngatom 0/min/106 cells. To assess the mitochondrial coupling, respiratory rates were monitored using inhibitors of the phosphorylation system, i.e., 1 mM atractyloside, 1 mM carboxyatractyloside, and 1 nM oligomycin in combination. Such inhibitors are considered as decouplers and can be used to evaluate the degree of mitochondrial ATP synthesis. Control experiments were performed using 1 mM cyanide as a blocker of the respiratory chain.
To visualize the mitochondrial network, GFP was targeted to the mitochondrial matrix space of the BSM cells. For this purpose, the mitochondrion-targeted GFP plasmid (mito-GFP), which was derived from the plasmid pEGFP-N1 (Clontech Laboratories, Inc.) containing the leader sequence of the E1α subunit of pyruvate dehydrogenase was used. One day before transfection, BSM cells were plated at 50% confluency in 10% FCS-DME without antibiotics. Transfections were conducted for 6 h at 37° C. in 5% CO2 with 1.5 μg of plasmid and 1.7% of the cationic lipid Lipofectamine 2000 (Invitrogen) in the absence of FCS. After 72 h, BSM cells were rinsed in PBS and fixed with 4% paraformaldehyde (PFA) for 20 min on ice. After drying, the slides were mounted with fluorescent mounting medium (Dako). Confocal differential interference contrast images were obtained using the FluoView laser scanning microscope (Nikon) and 60× oil-immersion objective. Z series sections were recorded in successive z axis serial sections at 0.5-μm intervals, and they were composed of optical sections in the x-y optical plane. Sections were reconstituted in three-dimensional images using Imaris Software (Bitplane).
BSM cells were washed twice with HBSS and lysed by the addition of 300 liters/well Trizol (Invitrogen) and 30 μl of chloroform (Sigma-Aldrich). The RNA was extracted from the aqueous phase after being centrifuged at 12,000 g for 15 min. RNA was precipitated in the presence of isopropanol (Sigma-Aldrich) at 220° C. overnight. The pure RNA was recovered by centrifugation and washed with 80% ethanol (Sigma-Aldrich). The purity was assessed by electrophoresis (30 mA for 75 min) on 1.5% agarose gel (Bio-Rad Laboratories), followed by 20 min incubation in 10 μg/ml ethidium bromide (Sigma-Aldrich), showing 2 bands corresponding to the 28S and 18S fractions of ribosomal RNA. The concentration of RNA was measured spectrophotometrically by GeneQuant RNA/DNA calculator (GE Healthcare). The total RNA (1 μg) was reverse transcribed into cDNA using AMV RT (Promega), RNase inhibitor, and oligo d(T) as a primer at 42° C. for 60 min, followed by heating at 94° C. for 3 min.
Real-time quantitative PCR was performed on a Rotor-Gene 2000 (Corbett Research). In brief, triplicate PCR reactions were assembled in 0.1-ml strip tubes containing cDNA from 10 ng of total RNA, 0.2 μl 50× Titanium Taq DNA Polymerase, 1× Titanium Taq PCR Buffer (Clontech Laboratories, Inc.), 1 mM dNTP, 100 mM each of the appropriate primer, and 0.5× Sybr Green I (Invitrogen). The PCR was performed under the following conditions: denaturation at 95° C. for 15 s, annealing temperature (64-72° C.) depending on specific primers for 15 s, and extension at 70° C. for 30 s for 30-40 cycles. Data collection was performed after each extension step, at a temperature at least 3.5° C. lower than the melting temperature of the amplicon (generally between 80-85° C.) to eliminate nonspecific fluorescence signal. PCR-negative controls were systematically made using water instead of cDNA or RNA sample without the RT step. All specific primers were designed using the primer analysis software (Oligo 6.6; Molecular Biology Insights) and were ordered from Sigma-Aldrich. Primers, sense and antisense, were as follows: for mtTFA (NM—003201), forward 5′-GAAGTCGACTGCGCTCCC-3′ (SEQ ID NO:1) and reverse 5′-ACTCCGCCCTATAAGCATC-3′(SEQ ID NO:2); for PGC-1α( (NM—013261), forward 5′-GTCACCACCCAAATCCTTATT-3′(SEQ ID NO: 3) and reverse 5′-GGCGATCTTGAACGTGAT-3′ (SEQ ID NO: 4); for NRF-1 (NM—005011), forward 5′-AAGATCAGCAAACGCAAACAC-3′ (SEQ ID NO: 5) and reverse 5′-CCCGTACCAACCTGGATAAGT-3′ (SEQ ID NO: 6); for tyrosin 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide (YWHAZ) (NM—003406), forward 5′-GGGGATGTGGAATTTTTATACAAG-3′ (SEQ ID NO: 7) and reverse 5′-CGCCAGGACAAACCAGTATGTAG-3′ (SEQ ID NO: 8); for hypoxanthine phosphoribosyltransferase 1 (HPRT-1) (NM—000194), forward 5′-GTGAAAAGGACCCCACGAA-3′ (SEQ ID NO: 9) and reverse 5′-AGTCAAGGGCATATCCTACAACAA-3′ (SEQ ID NO: 10) ; and for human acidic ribosomal phosphoproteins (PO) (NM—001002), forward 5′-CAACGGGTACAAACGAGTC-3′ (SEQ ID NO: 11) and reverse 5′-CTTCCTTGGCTTCAACCTTAG-3′ (SEQ ID NO: 12). The efficiency of the PCR reactions was always >90%. The specificity of the amplified PCR products was examined with the melting curve analysis, and also in 2% agarose gel containing ethidium bromide. The RT-PCR expression of the target genes (i.e., mtTFA, PGC-1α, and NRF-1) was thus presented as an arbitrary unit and normalized to endogenous references (geometric averaging of three internal control genes; i.e., YWHAZ, HPRT-1, and PO) according to geNorm software.
Change in growth-arrested BSM cell intracellular calcium concentration ([Ca2+]i), was assessed using the Ca2+-sensitive probe indo-1, as previously described (Berger et al., J. Appl. Physiol. 91:995-1003 (2001); Trian et al., Am. J. Respir. Cell Mol. Biol. 34:49-55 (2006)). In brief, cells were loaded with indo-1 (Calbiochem) and mounted in a perfusion chamber continuously perfused with phosphate salt solution containing either 2 mM Ca2+ in the absence or presence of 1 μM D600, or 400 μM EGTA (Sigma-Aldrich) in the absence of extracellular calcium. BSM cells were stimulated with 10−5 M acetylcholine or histamine (both from Sigma-Aldrich). Individual cell calcium levels were monitored continuously. Results were expressed as the mean±the SEM of resting or peak of [Ca2+]i rises (in millimoles) and area under the curves (nanomoles/second). Experiments were carried out at room temperature (22-25° C.).
Growth-arrested BSM cells were cultured in 96-well plates for 24 h and stimulated with 10% FCS-DME containing glucose, galactose, ethidium bromide, or cyclic GMP for 24 h or containing D600 for 48 h, as described above. Control BSM cells remained in serum-deprived DME. DNA synthesis was measured using the BrdU kit according to the manufacturer's instructions (Roche). In brief, BSM cells were incubated with 10 μM BrdU for 2 h at 37° C. and fixed for 20 min at room temperature. Cells were denaturized for 30 min and incubated with the anti-BrdU antibody for 2 h at room temperature. Absorbance was measured at 370 nm in a microplate reader in triplicate. Results are expressed as a normalized ratio of BrdU incorporation, i.e. absorbance for test condition divided by absorbance for control serum-deprived condition.
The statistical analysis was performed with NCSS 2001 software. Comparisons between the three groups were performed by means of ANOVA, with the use of Bonferroni's test for multiple comparisons or paired Student's t tests. Values are presented as the mean±the SEM. A Pearson correlation matrix was built between in vitro and in vivo measurements. A P value <0.05 was considered statistically significant.
A morphological analysis of BSM was performed in the three groups of subjects (
There was a significant increase in the mitochondrial density in asthmatic BSM cells both ex vivo (
It is also found within the asthmatic population that both duration of the disease and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) ratio were correlated with the porin content (r=0.77, P=0.03 and r=−0.84, P=0.01, respectively), whereas no correlation was found within the COPD or the control population. Similarly, the oxygen consumption of asthmatic BSM cells was specifically enhanced compared with COPD or control BSM cells (
Next, the mitochondrial network was analyzed by confocal microscopy (
Next, whether calcium homeostasis was deregulated in asthmatic BSM cells was investigated using micro-spectrofluorimetry. The resting calcium concentration was consistent in asthmatic (125±8 nM), COPD (127±7 nM), or control BSM cells (133±4 nM; P=0.60) However, the calcium response to acetylcholine was significantly altered in asthmatic BSM cells (
To further assess the specific role of mitochondria in asthmatic BSM proliferation contributing to airway remodeling, BSM cell growth in the presence or absence of anaerobic glycolysis was compared. For this purpose, BSM cell proliferation curves were plotted in the three groups of subjects using either glucose or galactose in the culture medium (
Because an increase in cell growth can be related to a decreased apoptosis and/or an increased proliferation, Annexin V binding and BrdU incorporation were analyzed, respectively. Taking into account the percentage of Annexin V-positive cells, spontaneous apoptosis was not altered in asthmatic BSM cells as compared with that of COPD and controls (data not shown). However, BrdU incorporation increased in BSM cells from asthmatics as compared with that in both COPD and controls in the presence of glucose (
To determine whether the increased mitochondrial biogenesis found in asthmatic BSM cells is a cause or a consequence of the asthmatic BSM cell increased proliferation, three alternative approaches were used. First, mitochondria-deficient BSM cells were generated using culture with ethidium bromide, as previously described (10, 15). After 16 d of culture, all of the asthmatic BSM cells died, whereas those from both COPD patients and controls were still alive up to 30 d in the ethidium bromide medium (unpublished data). 6 d of incubation with ethidium bromide significantly decreased the amount of porin in the three groups of subjects (
In a second alternative approach, mitochondrial biogenesis was stimulated using cyclic GMP for 6 d as previously described (16). The amount of mitochondria increased in such stimulated BSM cells from both COPD and controls (
Finally, in a last approach, the effect of altering calcium homeostasis on the proliferation of BSM cells was analyzed. D600, which blocks calcium influx (
The effects of calcium channel inhibitors such as gallopamil on asthmatic smooth muscle remodeling can be examined with severe asthmatic or non severe asthmatic patients. A phase 2 randomized double blind study against placebo is conducted. Since inflammation also activates mitochondrial biogenesis in BSM cells, optimization of asthma treatment is first effected during 3 months by both controlling co morbidities and decreasing bronchial inflammation using exhaled NO and eosinophil count within the induced sputum. Patients are subject to fiberoptic fibroscopies before and after 12-month treatment with gallopamil/placebo. Same proceedings are conducted with calcium channel inhibitors, such as verapamil, devapamil, emopamil, anipamil, nifedipine, nicardipine, or diltiazem. Also, treatments are performed in combination with standard care therapy for asthma, such as (1) inhaled corticosteroids such as beclomethasone (up to 2000 μg/day equivalent), or budesonide, or fluticasone, and (2) LABA (Long acting beta 2 agonists), such as formoterol or salmeterol, and (3) optionally a third one which is an oral corticoid such as prednisolone.
Inclusion criteria include male or female aged more than 18 yrs; written informed consent; and a diagnosis of severe asthma according to ATS criteria. Main exclusion criteria include smoker or former smoker; chronic viral infections (hepatitis, HIV); pregnancy or breastfeeding; contraindications to gallopamil or bronchoscopy.
The primary outcomes are bronchial smooth muscle remodeling assessed by the smooth muscle size within the bronchial mucosa, the smooth muscle cell size, the number of smooth muscle cells/area of smooth muscle, and the proliferation rate of the smooth muscle cells. Secondary outcomes include: bronchial thickness assessed by 3D analysis of computed tomography; asthma control using the asthma control questionnaire (ACQ) validated by Juniper; and BSM mitochondrial number and activity assessed by electronic microscopy, oxygraphy, or Western blot.
The clinical study comprises 3 phases. The initial phase (3 months) includes initial clinical and functional assessment of asthma control including ACQ, plethysmography, exhaled NO, and induced sputum; Co-morbidity treatment; and optimization of asthma treatment. After the first fiberoptic fibroscopy, the treatment phase lasts 12 months, and the final phase (3 months) includes fiberoptic fibroscopy and 3 month follow-up after stopping the treatment.
This application claims benefit of U.S. Provisional Application No. 61/073,677 filed Jun. 18, 2008, the entire disclosure of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61073677 | Jun 2008 | US |
