-20pt?>Mycobacterium tuberculosis (Mtb) is a pathogenic bacterium that causes contagious tuberculosis (TB). Recently, Mtb-secreted proteins have been considered virulence factors and candidates for drugs and vaccines. Among these proteins, 6-kDa early secreted antigenic target (ESAT-6) is known to be able to induce component of matrix metalloproteinase-9 (MMP-9) in epithelial cells, leading to recruitment of macrophages. However, detailed function of ESAT-6 during macrophage recruitment to inflammatory sites remains unknown. Thus, the objective of the present study was to elucidate such function of EAST-6 and mechanism(s) involved. In the present study, we have found that recombinant ESAT-6 purified in the form of ESAT-6 double-connected structure (2E6D) could inhibit lipopolysaccharide (LPS)-induced potential of cell migration and inflammation in murine macrophage cells. Interestingly, 2E6D suppressed LPS-induced MMP-9 expression at both protein and mRNA levels as well as its enzyme activity. Levels of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) enzymes as known upregulators of MMP-9 were significantly decreased when 2E6D has been treated. In addition, nitric oxide (NO) as a second messenger was also significantly decreased by treatment with the purified 2E6D. Furthermore, 2E6D inhibited LPS-induced phosphorylation of IκB and translocation of NF-κB. Moreover, 2E6D suppressed phosphorylation of MAPK signaling proteins. Taken together, these results suggest that ESAT-6 can suppress LPS-induced MMP-9 and inflammation by downregulating COX-2, iNOS, and NO through NF-κB and MAPK signaling.
CITATION STYLE
Ha, S. H., Choi, H., Park, J. Y., Abekura, F., Lee, Y. C., Kim, J. R., & Kim, C. H. (2020). Mycobacterium tuberculosis–Secreted Protein, ESAT-6, Inhibits Lipopolysaccharide-Induced MMP-9 Expression and Inflammation Through NF-κB and MAPK Signaling in RAW 264.7 Macrophage Cells. Inflammation, 43(1), 54–65. https://doi.org/10.1007/s10753-019-01087-x
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