Effects of Mycobacterium tuberculosis heparin-binding hemagglutinin(HBHA) on macrophage polar-ization / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the effects of Mycobacterium tuberculosis heparin-binding he-magglutinin (HBHA) on the polarization of mouse bone marrow-derived macrophages (BMDM) and a mu-rine macrophage cell line(Raw264.7 cells). Methods After HBHA was confirmed to be able to enter into macrophages by immunofluorescence, mouse BMDM and Raw264. 7 cells were treated with LPS (100 ng/ml)+IFN-γ (2.5 ng/ml),IL-4 (20 ng/ml),HBHA (1 μg/ml,3 μg/ml,6 μg/ml,10 μg/ml) and ESAT-6 (5 μg/ml),respectively. IL-6,IL-12 and TNF-α in the supernatants of cell culture were measured by ELISA. RT-PCR was performed to detect the expression of molecular markers of macrophage polarization [inducible nitric oxide synthase (iNOS), TNF-α, Arg-1 and CD206] at mRNA level. Western blot assay was used to detect the expression of iNOS and Arg-1 at protein level. Results Increased secretion of IL-6, IL-12 and TNF-α in the supernatants of cell culture and enhanced expression of iNOS and TNF-α at mRNA level were observed after treating BMDM with Mycobacterium tuberculosis HBHA. Similarly,in HBHA-trea-ted Raw264.7 cells,the secretion of IL-6 and the expression of TNF-α were also up-regulated. Mycobacteri-um tuberculosis HBHA and ESAT-6 had similar effects on murine macrophages. Neither of them could in-crease the expression of Arg-1,a molecular marker of M2 macrophages,in BMDM at protein level,but both enhanced the expression of iNOS,a molecular marker of M1 macrophages,in BMDM and Raw264.7 cells. Conclusion Mycobacterium tuberculosis HBHA can induce the polarization of murine macrophages to M1 phenotype.