Spinal Tuberculosis (STB) is a common cause of spinal malformation caused by extrapulmonary tuberculosis in developing countries, which seriously affects the quality of life of patients. It was found that the expression of miRNAs in macrophages was stable, specific and readily available after Mycobacterium tuberculosis (MTB) infection. Our research group determined the differential expression of miR-29a-3p in the vertebra of spinal tuberculosis and intervertebral disc lesions through RNAs chip screening and bioinformatics analysis. However, the specific molecular mechanism of miR-29a-3p in the inflammatory response of spinal tuberculosis remains unclear.

In this study, we mainly discussed the expression of miR-29a-3p in the focal tissue of spinal tuberculosis and the role and molecular mechanism of miR-29a-3p mediated by METTL3 in the inflammatory response of spinal tuberculosis.

The tissues of 15 cases of lumbar degenerative diseases and vertebral lesions of spinal tuberculosis were collected, and the THP-1 macrophage model infected by Mycobacterium tuberculosis was constructed, and verified by qRT-PCR, Western blot, fluorescence in situ hybridization, immunohistochemistry, Cell fluorescence and ELISA.

We found that the expression of miR-29a-3p was significantly down-regulated in the vertebral body and disc lesion tissues of patients with spinal tuberculosis. Overexpression of miR-29a-3p inhibited the levels of inflammatory factors including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), and inhibition of miR-29a-3p expression promoted the release of the levels of TNF-α, IL-1β and IL-6 inflammatory factors. Our study also shows that knockout of methyltransferase 3 (METTL3) can significantly reduce the expression of miR-29a-3p and promote the release of pro-inflammatory cytokines in macrophages.