Triterpenoid compound betulin attenuates allergic airway inflammation by modulating antioxidants, inflammatory cytokines and tissue transglutaminase in ovalbumin-induced asthma mice model

Objectives This study hypothesized that to analyse the anti-inflammatory effect of triterpenoid compound betulin in ovalbumin (OVA)-induced asthmatic mice. Methods In this study, betulin was intraperitoneally administered in OVA-challenged and sensitized mice. The effect of betulin on inflammatory cells, lung function, reactive oxygen species (ROS) production, antioxidants status, oxidative stress markers, serum IgE level and inflammatory cytokines status in BALF was examined by enzyme-linked immunosorbent assay. The expression of tTG, TGF-beta 1, MMP-9 and TIMP-1 in lung tissue was scrutinized by RT-qPCR analysis, and the expression of TREM-1, p-I kappa B-alpha and NF-kappa Bp65 proteins in lung tissue was examined by western blot analysis. Key findings We found that the betulin treatment has effectively attenuated the proliferation of inflammatory cells, reduced the ROS generation, elevated the antioxidant enzymes and attenuated the level of oxidative markers in asthma induced mice. Moreover, reduced the level of serum IgE and pro-inflammatory cytokines, and increased the anti-inflammatory cytokine IFN-gamma. Betulin treatment down-regulated the expression of MMP-9, tTG and TGF-beta 1 genes; moreover, betulin treatment effectively down-regulated the TREM-1, p-I kappa B-alpha and NF-kappa Bp65 proteins level in lung. Conclusion Betulin exhibited effective anti-asthmatic activity by attenuating the accumulation of inflammatory cells, expression of tTG, TGF-beta 1 and MMP-9 genes in lung tissue.