Comprehensive analysis of macrophages infected with avirulent and virulent Mycobacterium tuberculosis uncovers distinct immune mechanisms and anti-TB effect of treated exosomes

Abstract

Tuberculosis (TB) is now the worlds second deadliest infectious killer after COVID-19. Human-macrophages and their secreted exosomes play important roles in combating invading Mtb. However, the panoramic analysis of the underlying immune mechanism for the infected macrophages, package or secretion mechanism, and anti-TB effect of Mtb treated exosomes remain poorly understood. Here we conducted comprehensive analyses of the macrophages infected with avirulent and virulent Mtb (H37Ra & H37Rv) and their secreted exosomes, collected cells and corresponding exosomes for omics and phenotypic analysis. The results showed that avirulent Mtb stimulated robust immune-responses and apoptosis in macrophages to eliminate the invading Mtb; virulent Mtb induced severe necrosis and immune-escape for survival. The HMGB1 signaling pathway and TNFRSF1B plays important roles in the immune escape of virulent Mtb. Interestingly, our results suggest that macrophages kill Mtb in an IFN-{gamma} independent but simulative way, highlighting the central role of IFN signaling pathway in anti-TB immune response. Moreover, we observed selective transport of host and Mtb RNAs from macrophages to exosomes. Notably, "H37Ra-treated exosomes" displayed a higher anti-TB effect than "H37Rv-treated exosomes" due to some enriched pro-inflammation and immune-escape related Mtb proteins in these two exosomes, respectively. Conclusively, our findings shed new light on the immune mechanism of macrophages in response to Mtb infection, offering a new TB-treatment strategy and some promising vaccine candidates.