Infection with the strain H37Rv and incubation with IFN-γ, synergistically inhibited expression of MR gene in murine BMDM [7, 23], constitutively expressing high levels of MR , resembling in this manner, alveolar macrophages BYL719 . In line with these observations, infection of the cells pretreated with IFN-γ by the moderately virulent strains, H37Rv and B2, in our experiments resulted in down-regulation of MR expression. In contrast to these strains, infection of MΦ by the strain MP287/03 restored expression of MR reduced by the IFN-γ treatment. High and persistent levels of MR expression in the MΦ infected with strain MP287/03 in the presence or absence of IFN-γ suggested that these cells
could be more susceptible to the deleterious effects of Mannosyl-capped lipoarabinomannan
(ManLAM) expressed by the pathogenic mycobacteria. Interaction of Man-LAM with MR has been demonstrated to inhibit fusion of phagosomes with lysosomes in the infected MΦ, interfere with IFN-γ-mediated signaling in MΦ activation, as well as suppress TLR-dependent induction of expression of IL-12 and other proinflammatory cytokines [25, 26]. In line with this suggestion, the infected cells expressing higher levels of MR in our experiments were permissive to enhanced intracellular growth even in the presence of IFN-γ. The ability of the strain MP287/03 to induce in MΦ some properties of the M2 cells, suggested that infection of the MΦ, pretreated with IL-10, Luminespib cell line by these bacteria may synergize in IL-10- dependent M2 polarization of these cells. The obtained results demonstrated that the treatment with IL-10 led to reduction of the proinflammatory MΦ activation by the studied mycobacterial strains. These cells displayed increased expression of the M2 markers, MR, IL-10 and Arg-1. The highest TCL levels of Arg-1 were observed in the cells infected by
MP287/03 mycobacteria, demonstrating that the treatment with IL-10 favored the M2-type activation of these cells. Although the cells infected with MP287/03 strain displayed increased levels of the M2 markers in the presence or absence of regulating cytokines, these cells secreted high levels of the proinflammatory MIP-2 chemokine. In contrast to the MCP-1 chemokine, regulating monocyte recruitment which is essential for selleck formation of functional granuloma, the continues production of MIP-2, and other chemokines attracting granulocytes, was demonstrated to cause excessive recruitment of neutrophils to the infected lungs, contributing to tissue damage in pulmonary tuberculosis, reviewed by . The high level of MIP-2 secretion and inappropriate proinflammatory MΦ activation, observed in the BMDM cultures infected with MP287/03 strain in this study, may have aggravating implications for in vivo infection with these, fast-replicating intracellular bacteria.