Has-miR-30c-1-3p inhibits macrophage autophagy and promotes Mycobacterium tuberculosis survival by targeting ATG4B and ATG9B.

Autophagy is a widespread physiological process in the body, which also protects the host by degrading invading pathogens and harmful substances during pathological conditions. Nevertheless, Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis, has evolved strategies to subvert autophagy by modulating microRNA (miRNA) expression, enabling its escape from host defenses. In this study, we established an in vitro model using the human macrophage cell line infected with the highly virulent MTB strain H37Rv. Through RNA sequencing and bioinformatic analysis post H37Rv infection, we screened 14 differentially expressed miRNAs. We predicted and demonstrated that miR-30c-1-3p inhibits autophagy and promotes MTB survival by targeting ATG4B and ATG9B during the infection process. The results showed that miR-30c-1-3p expression was gradually increased before 12 h of H37Rv infection, followed by a decrease. Overexpression of miR-30c-1-3p suppressed autophagic activity. We also identified the targeting of miR-30c-1-3p to ATG4B and ATG9B for the first time, and overexpression of both ATG4B and ATG9B, alone or together, on the basis with upregulation of miR-30c-1-3p reversed the inhibition of autophagy. Autophagy levels were analyzed at different levels by western blot, immunofluorescence, and transmission electron microscopy, all of which showed that upregulation of miR-30c-1-3p inhibited autophagy during H37Rv infection. Additionally, the intervention of miR-30c-1-3p mimics resulted in an increased bacterial load in macrophages, suggesting that MTB achieves immune evasion by upregulating miR-30c-1-3p during infection. In conclusion, our study provides a valuable target for the development of host-directed anti-tuberculosis therapy as well as a new diagnostic marker.