Therapeutic Effects of Mycobacterial Secretory Proteins Against Established Asthma in BALB/c Mice

Abstract

Purpose Live/killed mycobacteria and culture supernatants can suppress asthmatic reactions. This study investigated whether mycobacterial secretory proteins have therapeutic effects on asthma. Methods Mycobacterium bovis bacille Calmette-Guérin (BCG; 2×10 5 CFUs) and mycobacterial secretory proteins (Ag85 complex, 38-kDa protein or MPB70; 4 or 20 µg) were administered intraperitoneally to female BALB/c mice with established airway hyperresponsiveness. One week after treatment, the mice underwent a methacholine challenge test, and then inflammatory cell numbers in bronchoalveolar lavage fluid (BAL) and around bronchi (<500 µm), and cytokine levels in splenocyte supernatants, were assessed. Results BCG and all of the tested secretory proteins significantly improved airway sensitivity compared to baseline values ( P <0.05). The secretory protein Ag85 complex significantly suppressed airway reactivity also ( P <0.05), while 38-kDa protein significantly suppressed reactivity and maximal narrowing ( P <0.05). The number of eosinophils in BAL and around bronchi, and the goblet cell proportion, were also significantly reduced in mice in both the BCG and secretory protein groups compared to the asthma control group. IFN-γ/IL-5 ratios were significantly higher in mice treated with BCG, 4 µg MPB70 or 4 µg 38-kDa protein than in asthma control mice ( P <0.05), and were negatively associated with airway hyperresponsiveness, peribronchial eosinophil numbers and goblet cell proportion (all P <0.05). IL-17A was positively correlated with IL-5 (r=0.379, P <0.001), maximal airway narrowing, peribronchial eosinophil numbers and goblet cell proportion (all P <0.05). Conclusions Secretory proteins from BCG and M. tuberculosis and live BCG were effective against established asthma, their effects being accompanied by increased IFN-γ/IL-5 ratios. Thus, allergic asthma could be effectively treated with mycobacterial secretory proteins.

Novel T‐cell epitopes on Schistosoma japonicum SjP40 protein and their preventive effect on allergic asthma in mice

“…Immunotherapy based on immune deviation is an effective strategy to treat or prevent allergic asthma. Live and dead bacteria, parasite, or bacterial components such as purified protein derivative from Mycobacterium tuberculosis have shown potential to protect mice from developing allergic Th2 responses by inducing Th1 responses . Different intracellular bacterial infections, such as BCG vaccine, can induce strong Th1 immune response, thus suppressing asthmatic reactions by balancing Th1/Th2 responses .…”

An evaluation of the use of immunoglobulin A antibody response against mycobacterial antigens for the diagnosis of Mycobacterium bovis infection in cattle

“…Native MPB70 protein was purified from M. bovis strain BCG (Bacillus Calmette-Guérin; Tokyo strain) culture filtrate proteins (CFPs) using a 2-step biochemical method as previously described. 9,17 Briefly, M. bovis BCG was grown at 37°C as a surface pellicle on Sauton medium for 6 weeks, after which the CFPs were filter sterilized with a 0.2-μm membrane. The 50-80% ammonium sulfate precipitate (ASP) of the CFPs was dialyzed against 1 mM potassium phosphate buffer (PPB, pH 7.0), loaded onto a hydroxyapatite column equilibrated with 1 mM PPB, and eluted with 1 mM PPB because MPB70 was not retained on the column.…”

Vaccine Potential of Mycobacterial Antigens against Asthma

“…To determine if individual secreted proteins of M. tuberculosis can modulate asthma, studies have been conducted with single proteins purified from the culture supernatants of M. tuberculosis , i.e., Ag85 complex, 38 kDa protein, and MPB70 [72], and the recombinant Ag85B produced in Escherichia coli [73]. These secreted proteins have been shown to be the inducers of Th1 cytokine IFN-γ from human peripheral blood cells [74].…”

“…These secreted proteins have been shown to be the inducers of Th1 cytokine IFN-γ from human peripheral blood cells [74]. The findings in the experimental asthma model showed that immunization of mice with the purified and recombinant proteins provided protection against asthma in the ovalbumin-challenge model [72, 73]. With respect to cells and cytokines, mice immunized with individual mycobacterial proteins preferentially activated Th1 cells and showed increased IFN-γ/IL-5 ratios [72, 73].…”

“…The findings in the experimental asthma model showed that immunization of mice with the purified and recombinant proteins provided protection against asthma in the ovalbumin-challenge model [72, 73]. With respect to cells and cytokines, mice immunized with individual mycobacterial proteins preferentially activated Th1 cells and showed increased IFN-γ/IL-5 ratios [72, 73]. In another study on a mouse model of asthma, immunization with Ag85A and IL-17A fusion protein (Ag85A-IL17A) resulted in a significant decrease in the concentration of cytokines secreted by Th2 cells (i.e., IL-4 and IL-13) and Th17 cells (IL-17A) and the number of total cells, eosinophils, and neutrophils in the BALF as well as the infiltration of inflammatory cells in the peribronchial region of the lung tissue [75].…”