Differential cytokine response by macrophages to ManLAM of Mycobacterium tuberculosis under various culture conditions (INC7P.419)

Abstract

Abstract Lipoarabinomannan, a lipoglycan is a major virulence factor for Mycobacterium. Mannosylated form of Lipoarabinomannan (ManLAM) is commanly found in pathogenic Mycobacterium tuberculosis. It has been shown that ManLams inhibit production of TNFα and IL-12 by macrophages under in vitro culture conditions. In this study, we tested cytokine responses of macrophages stimulated with ManLAM under various culture conditions. ManLAM was isolated from M. tuberculosis strain H37Rv (ATCC 25618). Macrophages (J744.1; murine macrophage cell line) were stimulated with ManLAM in three different conditions, either alone or in co-cultures with fibroblasts (3T3; ATCC, CRL1658) in contact-culture and non-contact culture systems. Cytokines were measured using commercially available ELISA kits. In comparison to unstimulated controls, TNFα, IL-6 and IFNγ levels increased significantly in co-culture systems after stimulation with ManLAM while a slight increase occurred for IL-12 in the same cultures. However, we observed no change in TNFα, IL-6 and IL-12 for stimulated macrophages when they were cultured alone in the absence of fibroblasts. These results suggested that macrophage activity to ManLAM changed in the presence of the fibroblast in co-culture systems that might be an in vitro model for granuloma formation in tuberculosis infections.