MicroRNA-27b Modulates Inflammatory Response and Apoptosis during Mycobacterium tuberculosis Infection.

Mycobacterium tuberculosis poses a significant global health threat. MicroRNAs play an important role in regulating host anti-mycobacterial defense; however, their role in apoptosis-mediated mycobacterial elimination and inflammatory response remains unclear. In this study, we explored the role of microRNA-27b (miR-27b) in murine macrophage responses to M. tuberculosis infection. We uncovered that the TLR-2/MyD88/NF-κB signaling pathway induced the expression of miR-27b and miR-27b suppressed the production of proinflammatory factors and the activity of NF-κB, thereby avoiding an excessive inflammation during M. tuberculosis infection. Luciferase reporter assay and Western blotting showed that miR-27b directly targeted Bcl-2-associated athanogene 2 (Bag2) in macrophages. Overexpression of Bag2 reversed miR-27b-mediated inhibition of the production of proinflammatory factors. In addition, miR-27b increased p53-dependent cell apoptosis and the production of reactive oxygen species and decreased the bacterial burden. We also showed that Bag2 interacts with p53 and negatively regulates its activity, thereby controlling cell apoptosis and facilitating bacterial survival. In summary, we revealed a novel role of the miR-27b/Bag2 axis in the regulation of inflammatory response and apoptosis and provide a potential molecular host defense mechanism against mycobacteria.