Effects of combined BCG and DHEA treatment in preventing the development of asthma

Androgens are effective bronchodilators with anti-inflammatory properties: A potential alternative for asthma therapy

Changes in plasma androgen levels in asthmatic men may be linked to asthma severity, seemingly acting through nongenomic and genomic effects. Nongenomic effects include rapid relaxation of carbachol or antigenic challenge pre-contracted guinea pig airway smooth muscle (ASM) in vitro: testosterone (TES) blocks l-type voltage dependent Ca²⁺ channels, stored operated Ca²⁺ channels, inositol 1,4,5-trisphosphate receptors and promotes prostaglandin E₂ biosynthesis. In ASM at rest, TES lowers basal intracellular Ca²⁺ concentration and tension, maintaining a proper airway patency keeping steady smooth muscle tension and basal intracellular Ca²⁺ concentration at rest. Moreover, the bronchospasm in sensitized guinea-pigs was ablated by dehydroepiandrosterone (DHEA), a precursor of steroids, TES and its metabolites 5α- and 5β-dihydrotestosterone (DHT). On the other hand, genomic effects related to androgens' anti-inflammatory properties in asthma have been recently studied. Briefly, TES negatively regulates type 2 immune response sustained by CD4+ Th2 and group 2 innate lymphoid cells, diminishing allergic airway inflammation in males. Also, novel findings establish that TES decreases interleukin (IL)-17A protein expression produced by CD4+ Th17 cells and therefore neutrophilic airway inflammation. Clearly, DHEA, TES or its 5β-reduced metabolite that possesses minimal androgenic effect, might have potential therapeutic capacities in the treatment of severe asthma via mechanisms distinct from corticosteroid treatment.

Bacillus Calmette-Guerin alleviates airway inflammation and remodeling by preventing TGF-β1 induced epithelial-mesenchymal transition

Bacillus Calmette-Guerin (BCG) is a potent agent for the prevention of tuberculosis. Current studies have regarded BCG as an immunomodulator. However, there is little information on whether it can be used to inhibit airway inflammation and airway remodeling caused by asthma. Therefore, in this study, we investigate the role of epithelial-mesenchymal transition (EMT) in airway inflammation and airway remodeling as well as the possible therapeutic mechanism of BCG for the treatment of asthma. Wistar rats were sensitized and challenged by ovalbumin for 2 weeks or 8 weeks. BCG was subcutaneously administered daily before every ovalbumin challenge to determine its therapeutic effects. The 2 weeks model group showed extensive eosinophilia, chronic inflammatory responses, bronchial wall thickening, airway epithelium damage, increased levels of transforming growth factor β 1 (TGF-β₁) in both bronchoalveolar lavage fluid and sera, decreased expression of epithelial marker E-cadherin, and increased expressions of mesenchymal markers α-smooth muscle actin (α-SMA) and Fibronectin (Fn). Except for inflammatory responses, all responses were more significant in the 8 weeks model group which displayed characteristics of airway remodeling including subepithelial fibrosis, smooth muscle hypertrophy, and goblet cell hyperplasia. When compared with the model groups, BCG administration inhibited airway inflammation and airway remodeling, decreased TGF-β₁ levels, upregulated expression of E-cadherin, and downregulated expression of α-SMA and Fn. The present study suggests for the first time that increased secretion of TGF- β₁ induced by asthmatic chronic inflammation may result in EMT, which is one of the most important mechanisms of airway inflammation and airway remodeling seen with asthma. BCG alleviates airway inflammation and airway remodeling by preventing TGF-β₁ induced EMT, therefore BCG may be a new therapy for treating asthma.

Endocrine regulation of airway contractility is overlooked

Asthma is a prevalent respiratory disorder triggered by a variety of inhaled environmental factors, such as allergens, viruses, and pollutants. Asthma is characterized by an elevated activation of the smooth muscle surrounding the airways, as well as a propensity of the airways to narrow excessively in response to a spasmogen (i.e. contractile agonist), a feature called airway hyperresponsiveness. The level of airway smooth muscle (ASM) activation is putatively controlled by mediators released in its vicinity. In asthma, many mediators that affect ASM contractility originate from inflammatory cells that are mobilized into the airways, such as eosinophils. However, mounting evidence indicates that mediators released by remote organs can also influence the level of activation of ASM, as well as its level of responsiveness to spasmogens and relaxant agonists. These remote mediators are transported through circulating blood to act either directly on ASM or indirectly via the nervous system by tuning the level of cholinergic activation of ASM. Indeed, mediators generated from diverse organs, including the adrenals, pancreas, adipose tissue, gonads, heart, intestines, and stomach, affect the contractility of ASM. Together, these results suggest that, apart from a paracrine mode of regulation, ASM is subjected to an endocrine mode of regulation. The results also imply that defects in organs other than the lungs can contribute to asthma symptoms and severity. In this review, I suggest that the endocrine mode of regulation of ASM contractility is overlooked.

Nongenomic bronchodilating action elicited by dehydroepiandrosterone (DHEA) in a guinea pig asthma model

Primates secrete large amounts of the precursor steroid dehydroepiandrosterone (DHEA); in humans, its levels are low during childhood and start declining after the fourth decade. It has been postulated that the progressive decline in DHEA levels may be related with the severity of asthma associated with age. To determine whether DHEA may regulate the airway smooth muscle (ASM) activity, isolated tracheal rings with and without epithelium from male guinea pigs were isometrically recorded to characterize the response of ASM to DHEA at different concentrations on KCl- and carbachol (CCh)-induced contraction as well as on ovalbumin (OVA)-induced contraction in sensitized guinea pigs. Additionally, we used barometric plethysmography in sensitized guinea pigs in order to compare changes of the lung resistance increased by the antigen challenge to OVA in the absence and presence of different doses of DHEA. DHEA concentration-dependently abolished the contraction to KCl, CCh and OVA, and no differences were found in preparations with and without epithelium. DHEA-induced relaxation was not modified by the suppression of protein synthesis or transcription, pharmacological inhibition of nitric oxide (NO) synthase, nor by antagonist of β2-adrenergic receptors or an inhibitor of the 3β-HSD enzyme. Likewise, Ca(2+)-induced contraction in Ca(2+)-free depolarized tissues was antagonized by DHEA, and the contraction to the L-type voltage-dependent calcium channel activator (Bay K 8644) was inhibited by DHEA. Furthermore, DHEA prevented OVA-induced increases in lung resistance. These results indicate that DHEA-induced relaxation in ASM is a nongenomic (membrane) action and is not produced after its bioconversion. The data suggest that DHEA-induced relaxation is an epithelium- and NO-independent mechanism that involves a blockade of voltage-dependent calcium channels and possible non-selective cation channels.

Dehydroepiandrosterone suppresses eosinophil infiltration and airway hyperresponsiveness via modulation of chemokines and Th2 cytokines in ovalbumin-sensitized mice

In this study, we evaluated the anti-inflammatory response and the mechanism by which dehydroepiandrosterone modulates immunity in ovalbumin-sensitized asthmatic mice. Female BALB/c mice were sensitized and challenged with ovalbumin and then treated with oral administration of dehydroepiandrosterone on days 21 to 27. The results showed dehydroepiandrosterone could suppress airway hyperresponsiveness and decrease eosinophil infiltration of the lungs in ovalbumin-sensitized mice. Moreover, dehydroepiandrosterone inhibited chemokines, including CCL11/eotaxin-1 and CCL24/eotaxin-2, and Th2-associated cytokine levels in bronchoalveolar lavage fluid. After the inflammatory human bronchial epithelial cell line BEAS-2B was treated with dehydroepiandrosterone, levels of proinflammatory cytokines and chemokines were inhibited, including IL-6, IL-8, CCL11, and CCL24. We suggested that dehydroepiandrosterone inhibited inflammation in bronchial epithelial cells as indicated by the suppression of Th2-associated cytokines and chemokines. Dehydroepiandrosterone also suppressed eosinophil migration and infiltration into the lung to improve the symptoms of asthma in ovalbumin-sensitized mice.

Personal Factors Affecting Therapeutic Responses to BCG Vaccination in Asthmatics

Purpose

Bacille Calmette-Guérin (BCG) vaccination has been reported to be an effective treatment for asthma in several animal models. This study investigated whether the response to BCG treatment in asthma depends on subject clinical characteristics.

Methods

Stable asthma patients were vaccinated with BCG. One month later, alterations in pulmonary function after vaccination and their relationships with subject clinical characteristics were determined.

Results

Of 149 patients with asthma, 54 (36.2%) showed a good or fair response to BCG. The ΔFEV1 after vaccination was significantly related to age (r=-0.348, P<0.001), peripheral blood eosinophil counts (r=0.315, P<0.001) and baseline FEV1, expressed as % personal best value (r=-0.474, P<0.001), but not to FEV1 % predicted value (r=-0.066, P>0.05). A good/fair response was highly prevalent in atopic females compared with atopic males, especially among those aged ≤50 years (90.9% vs. 40.0%, P=0.024). Age (P<0.001, odds ratios (OR)=0.92, confidence interval (CI)=0.88-0.96) and atopy (P<0.01, OR=4.95, CI=1.70-14.44) were significant predictors for a good/fair response in females. However, blood eosinophil counts (P<0.05, OR=1.18, CI=1.01-1.39) and FEV1 % best (P<0.001, OR=0.86, CI=0.79-0.94), but not age or atopy, were significant predictors in males. Approximately three-quarters of the males were smokers.

Conclusions

The therapeutic effect of BCG in asthma may differ according to patient clinical characteristics. The greatest benefit occurred in young atopic females. Asthma activity indices, such as eosinophilia and FEV1 % best, were more predictive of a good/fair response in males; this may have been related to cigarette smoking.

Gender-specific asthma treatment

Because genetic characteristics vary among subjects, the therapeutic effects of a certain drug differ among patients with the same disease. For this reason, special interest has focused on tailored treatments. Although it is well known that sex is genetically determined, little attention has been paid to sex differences in the clinical features and treatment of asthma. Females are more likely to suffer allergic asthma, to have difficulty controlling asthma symptoms, and to show adverse effects to drugs. As asthma symptoms show cyclic changes depending on female hormone levels in many women of child-bearing age, the use of contraceptives may specifically help to treat female patients with asthma such as those with perimenstrual asthma and severe asthma. Generally, testosterone seems to suppress asthma, and dehydroepiandrosterone (DHEA), a less virilizing androgen, may be effective for treating asthma. Evidence exists for a therapeutic and steroid-sparing effect of DHEA. However, further studies on the optimal dose and route of DHEA for each sex are needed. Monitoring of the serum DHEA-S level is necessary for patients with asthma on inhaled steroid treatment, and at minimum, replacement therapy for patients with a low level of DHEA may be helpful for treating their asthma.

Comparison of BCG, MPL and cationic liposome adjuvant systems in leishmanial antigen vaccine formulations against murine visceral leishmaniasis

Background

The development of an effective vaccine against visceral leishmaniasis (VL) caused by Leishmania donovani is an essential aim for controlling the disease. Use of the right adjuvant is of fundamental importance in vaccine formulations for generation of effective cell-mediated immune response. Earlier we reported the protective efficacy of cationic liposome-associated L. donovani promastigote antigens (LAg) against experimental VL. The aim of the present study was to compare the effectiveness of two very promising adjuvants, Bacille Calmette-Guerin (BCG) and Monophosphoryl lipid A (MPL) plus trehalose dicorynomycolate (TDM) with cationic liposomes, in combination with LAg, to confer protection against murine VL.

Results

All the three formulations afforded significant protection against L. donovani in both the visceral organs, liver and spleen. Although comparable level of protection was observed in BCG+LAg and MPL-TDM+LAg immunized mice, highest level of protection was exhibited by the liposomal LAg immunized group. Significant increase in anti-LAg IgG levels were detected in both MPL-TDM+LAg and liposomal LAg immunized animals with higher levels of IgG2a than IgG1. But BCG+LAg failed to induce any antibody response. As an index of cell-mediated immunity DTH responses were measured and significant response was observed in mice vaccinated with all the three different formulations. However, highest responses were observed with liposomal vaccine immunization. Comparative evaluation of IFN-γ and IL-4 responses in immunized mice revealed that MPL-TDM+LAg group produced the highest level of IFN-γ but lowest IL-4 level, while BCG+LAg demonstrated generation of suboptimum levels of both IFN-γ and IL-4 response. Elicitation of moderate levels of prechallenge IFN-γ along with optimum IL-4 corresponds with successful vaccination with liposomal LAg.

Conclusion

This comparative study reveals greater effectiveness of the liposomal vaccine for protection against progressive VL in BALB/c. Again, evaluation of the immune responses by vaccination emphasizes the need of stimulation of potent cellular immunity based on both Th1 and Th2 cell responses to confer protection against VL.

Hormonal influences on lung function and response to environmental agents: lessons from animal models of respiratory disease

Numerous studies in humans and experimental animals have identified considerable sex differences in respiratory physiology and in the response of the lung to environmental agents. These differences appear to be mediated, at least in part, by sex hormones and their nuclear receptors. Moreover, animal models are increasingly used to study pathogenic mechanisms and test potential therapies for a variety of human lung diseases, many of which appear to be influenced by sex and sex hormones. In this article, data are summarized from studies of lung function and disease in which sex differences have been observed. Specific attention is paid to animal models of acute lung injury, nonallergic and allergic lung inflammation, and lung fibrosis. It is anticipated that continued investigation of the role of sex and sex hormones in animal models will provide valuable insight into the pathogenesis and potential treatments for a variety of acute and chronic human lung diseases.

Effects of combined bacille Calmette-Guérin and dehydroepiandrosterone treatment on established asthma in mice

Both bacille Calmette-Guerin (BCG) and dehydroepiandrosterone induce Th1 immune responses and suppress Th2 allergic reactions. To investigate whether a combined administration of BCG and dehydroepiandrosterone treat asthma more effectively, BALB/c mice (n = 8 per group) with established airway hyper-responsiveness were treated with BCG and/or dehydroepiandrosterone. Combined treatment with 2 x 10(5) colony-forming units (CFUs) of BCG and 0.01% dehydroepiandrosterone was the most effective one at suppressing eosinophilia in bronchoalveolar lavage fluids. In addition, this combination also was better at suppressing hypersensitivity as compared to BCG alone (13.7 +/- 4.0- versus 3.6 +/- 0.5-fold increase in the sensitivity index; P < .05) in male mice. Similarly, the effect of the combined treatment was superior to that of individual treatments at decreasing the serum ovalbumin-specific immunoglobulin E (IgE) level. However, the addition of 0.1% dehydroepiandrosterone to BCG significantly decreased the efficacy of BCG on hypersensitivity in female mice. In male mice, the suppressive effect of the treatments on hypersensitivity tended to be lower, and the baseline interferon-gamma /interleukin-5 (IFN-gamma /IL-5) ratio in the splenocyte supernatant was significantly higher as compared to female mice. In conclusion, treatment with an appropriate combination of BCG and dehydroepiandrosterone had additive therapeutic effects on mice with established asthma. Androgens in males and dehydroepiandrosterone overdose might reduce the efficacy of BCG.

Neonatal bacillus Calmette-Guérin vaccination inhibits de novo allergic inflammatory response in mice via alteration of CD4+CD25+ T-regulatory cells

AIM

The hygiene hypothesis suggests a lack of bacterial infections would favor the development of allergic diseases. Mycobacterium bovis bacille Calmette-Guérin (BCG) infection can inhibit allergen-induced asthma reactions, but the underlying mechanism of this infection on the immunological responses is unclear. T-regulatory (Treg) cells are thought to play a role as a crucial immunoregulatory cells that are capable of regulating adaptive immune responses. We conducted this study to investigate whether the protective effect of the BCG vaccination on allergic pulmonary inflammation is associated with the alteration of CD4+CD25+ Treg cells in a murine asthma model and the mechanisms of Treg cells.

METHODS

Newborn C57BL/6 mice were vaccinated 3 times with BCG on d 0, 7, and 14 and subsequently sensitized and challenged with ovalbumin. Eosinophil infiltration was investigated. The frequencies of spleen CD4+CD25+ Treg cells and the expression of specific transcriptional factor Foxp3 were assayed. The cytotoxic lymphocyte associated antigen (CTLA)-4 expression and cytokine interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) levels were measured.

RESULTS

We showed that treatment of mice with BCG inhibited de novo allergic inflammatory response in a mouse model of asthma. BCG treatments are associated with the increase of CD4+CD25+ Treg cells and Foxp3 expression, accompanied by an increased CTLA-4 expression and cytokine IL-10 and TGF-beta levels (P<0.05).

CONCLUSION

Neonatal BCG vaccinations ameliorate de novo local eosinophilic inflammation induced by allergen and increase the numbers of CD4+CD25+ Treg cells and Foxp3 expression. The cell-cell contact inhibition and regulatory cytokine production may be involved in the regulatory mechanism.

Effects of dehydroepiandrosterone on Th2 cytokine production in peripheral blood mononuclear cells from asthmatics

BACKGROUND/AIMS

The androgen dehydroepiandrosterone (DHEA) attenuates allergic inflammatory airway reactions by down-regulating the Th2 response in mice. The purpose of this study was to investigate whether DHEA suppresses Th2 cytokine production in cultured peripheral blood mononuclear cells (PBMCs) from asthmatic patients.

METHODS

Sixty-one consecutive suspected asthmatic or non-asthmatic men underwent tests for asthma. PBMCs from each subject were cultured with and without DHEA (0.01~10 microM) for 48 h. The concentrations of interferon (IFN)-gamma, interleukin (IL)-5, and IL-10 in the culture supernatant were measured via an enzyme-linked immunosorbent assay.

RESULTS

In PBMCs from subjects exhibiting methacholine airway hyperresponsiveness (AHR), DHEA significantly suppressed IL-10, IL-5, and IFN-gamma production in a dose-dependent manner (all p<0.001) and tended to increase the IFN-gamma/IL-5 ratio (p=0.087). DHEA (10 microM) suppressed cytokine production to a greater degree in subjects with AHR compared with those without AHR (IL-5: 24.0+/-7.8% vs. 40.9+/-3.6%, p<0.01; IFN-gamma: 29.7+/-7.0% vs. 54.5+/-5.1%, p<0.01). Cytokine suppression was significantly related to AHR, serum total IgE levels, and skin reactivity to house dust mites.

CONCLUSIONS

DHEA suppressed both Th1 and Th2 responses, with a Th1 bias, and the degree of suppression was associated with the severity of AHR or atopy. Therefore, DHEA may be a useful therapy for asthma.