MicroRNA-206 regulates the secretion of inflammatory cytokines and MMP9 expression by targeting TIMP3 in...

Tuberculosis (TB) is a serious disease that is characterized by Mycobacterium tuberculosis (M.tb)-triggered immune system impairment and lung tissue damage shows limited treatment options. MicroRNAs (miRNAs) are regulators of gene expression that play critical roles in many human diseases, and can be up- or downregulated by M.tb infection in macrophage. Recently, tissue inhibitor of matrix metalloproteinase (TIMP) 3 has been found to play roles in regulating macrophage inflammation. Here, we found that TIMP3 expression was regulated by miR-206 in M.tb-infected THP-1 human macrophages. In THP-1 cells infected with M.tb, the miR-206 level was significantly upregulated and the expression of TIMP3 was markedly decreased when the secretion of inflammatory cytokines was increased. Inhibition of miR-206 markedly suppressed inflammatory cytokine secretion and upregulated the expression of TIMP3. In contrast, the upregulation of miR-206 promoted the matrix metalloproteinase (MMP) 9 levels and inhibited TIMP3 levels. Using a dual-luciferase reporter assay, a direct interaction between miR-206 and the 3'-untranslated region (UTR) of TIMP3 was confirmed. SiTIMP3, the small interfering RNA (siRNA) specific for TIMP3, significantly attenuated the suppressive effects of miR-206-inhibitor on inflammatory cytokine secretion and MMP9 expression. Our data suggest that miR-206 may function as an inflammatory regulator and drive the expression of MMP9 in M.tb-infected THP-1 cells by targeting TIMP3, indicating that miR-206 is a potential therapeutic target for patients with TB.