Small RNA Sequencing and Bioinformatics Analysis of RAW264.7-Derived Exosomes after Mycobacterium Bovis Bacillus Calmette-Guérin Infection

Abstract

Background: The mechanisms through which Mycobacterium tuberculosis evades immune surveillance during tuberculosis (TB) infection remain complex. Previous studies have found that Mycobacteria can manipulate the miRNAs of host cells to promote their survival during host-pathogen interactions, and most of these effects occur at the cellular miRNA level. We at-tempted to investigate the possible related mechanisms at the exosomal miRNA level. Results: High-throughput sequencing revealed that Bacillus Calmette-Guérin (BCG) infection could alter the composition of the macrophage exosome content, and the expression levels of miRNAs in exosomes derived from the cell culture media of macrophages showed significant differences be-tween the BCG-infected and noninfected groups. Compared with the non-infection group, 20 exosomal miRNAs were up-regulated and 7 exosomal miRNAs were down-regulated in the infection group (p<0.05), of which mmu-miR-27b-3p, mmu-miR-93-5p, mmu-miR-25-3p, mmu-miR-1198-5p, mmu-let-7c-5p and let-7a-5p were significantly up-regulated. A bioinformatic analysis indicated that these differentially expressed exosomal miRNAs were involved in multiple biological processes and pathways. The target genes of top six miRNAs in up-regulated groups were positively correlated with the regulation of apoptosis.Conclusions: Our study provides relatively strong evidence for unravelling the complex pathophysiological processes of TB and the mechanisms of mycobacterial immune escape based on differential exosomal miRNA expression in host macrophages. Additionally, these exosomal miRNAs may serve as potential immunotherapy targets for the effective control of TB infection, but this probability requires further study.