B and T lymphocyte attenuator regulates autophagy in mycobacterial infection via the AKT/mTOR signal pathway

• Published in: International immunopharmacology 2021-02, Vol.91, p.107215-107215, Article 107215
• Main Authors: Liu, Jiao, Ming, Siqi, Song, Weifeng, Meng, Xiaojun, Xiao, Qiang, Wu, Minhao, Wu, Yongjian, Xie, Hanbin, Zhou, Jie, Zhong, Haibo, Huang, Xi
• Format: Article
• Language: English
• Subjects: 1-Phosphatidylinositol 3-kinase; AKT protein; Apoptosis; Autophagy; Bacterial clearance; BTLA; BTLA protein; CD14 antigen; Granuloma; Infections; Intracellular; Intracellular signalling; Lungs; Lymphocytes; Lymphocytes B; Lymphocytes T; Macrophage; Macrophages; Monocytes; mRNA; Phagocytosis; Phosphorylation; Reactive oxygen species; Signaling; Spleen; Substrate inhibition; Survivability; Survival; Therapeutic applications; TOR protein; Tuberculosis
• ISSN: 1567-5769; 1878-1705
• DOI: 10.1016/j.intimp.2020.107215

•BTLA expression is elevated in macrophages during M.tb infection.•BTLA enhances macrophage-mediated clearance of M.tb by promoting autophagy.•AKT/mTOR signaling is required for BTLA mediated autophagy and M.tb clearance.•BTLA agonist treatment protects mice from mycobacterial infection. The survivability of Mycobacterium tuberculosis (M.tb) in macrophages in granuloma is a predominant cause for tuberculosis (TB) infection and recurrence. However, the mechanism of mycobacterial clearance in macrophages still needs further study. Here, we explored a novel role of B and T lymphocyte Attenuator (BTLA) in macrophage-mediated host defense against mycobacterial infection. We found that the surface expression of BTLA was increased in CD14+ monocytes from active TB patients. The mRNA levels of BTLA were induced in human and mice monocytes/macrophages during Mycobacterium bovis BCG or M.tb H37Rv infection, as well as spleen and lung of H37Rv-infected mice. Furthermore, silencing of BTLA promoted the intracellular survival of BCG and H37Rv by suppressing the autophagy in macrophages but not effecting phagocytosis, reactive oxygen species (ROS) and apoptosis. Silence of BTLA reduced bacterial-autophagosome and bacterial-lysosome colocalization. Moreover, BTLA inhibited AKT and mTOR signaling substrates S6K and 4EBP1 phosphorylation in BCG and H37Rv infected macrophages, and BTLA-mediated AKT-mTOR signaling and intracellular BCG survival were reversed by PI3K inhibitors in macrophages. Finally, treatment with BTLA agonist ameliorated lung pathology and promoted autophagy and mycobacterial clearance during mycobacterial infection in vivo. These results demonstrate that BTLA promotes host defense against mycobacteria by enhancing autophagy, which may provide potential therapeutic interventions against tuberculosis.