Mechanism of recombinant Mycobacterium smegmatis in alleviating airway inflammation in mice with non-eosinophilic asthma

Objective To observe the effects of intranasal inoculation with recombinant Mycobacterium smegmatis (rMS) on the airway inflammation of non-eosinophilic asthmatic mouse and further investigate the relative mechanism. Methods DO11.10 T-cell receptor transgenic mice were divided randomly into three groups.Non-eosinophilic asthmatic model was established via OVA challenge, rMS were administrated into mice before challenge.Anti-IL-17A autoantibody in sera, IL-6 and IL-17A in BALF were measured by ELISA, the proportion of neutrophil in BALF was measured by FCM, MPO activity in lung tissue was detected by colorimetry, and the mRNA expression of CXCL2 and CXCL5 was measured by real-time PCR. Results Compared to control group, the number of neutrophils, IL-6 and IL-17A levels in BALF from asthmatic mice was significantly increased, meanwhile MPO activity and the expression of CXCL2, CXCL5 in lung tissue were both significantly upregulated.The results showed that high titer of autoantibody of IL-17A in sera of mice vaccined with recombinant Mycobacterium smegmatis was detected.Compared to asthma group, neutrophils and IL-6, IL-17A in BALF were significantly decreased, meanwhile MPO activity and CXCL2, CXL5 mRNA expression were significantly down-regulated. Conclusion Recombinant Mycobacterium smegmatis exhibits anti-inflammatory activity in murine neutrophilic asthma model and it may have protective effects on asthma. Key words: Bronchial asthma; IL-17A; Autoantibody; Airway inflammation