Leishmania donovani promastigotes evade the activation of mitogen-activated protein kinases p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinase-1/2 during infection of naive macrophages.
The protozoan parasite Leishmania fails to activate naive macrophages for proinflammatory cytokines production, and selectively impairs signal transduction pathways in infected macrophages. Because mitogen-activated protein kinases (MAPK)- and NF-kappaB-dependent signaling pathways regulate proinflammatory cytokines release, we investigated their activation in mouse bone marrow-derived macrophages (BMM) exposed to Leishmania donovani promastigotes. In naive BMM, the parasite failed to induce the phosphorylation of p38 MAPK, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK)1/2, as well as the degradation of IkappaB-alpha. The use of L. donovani mutants defective in the biosynthesis of lipophosphoglycan revealed that evasion of ERK1/2 activation requires surface expression of the repeating unit moiety of this virulence determinant. In IFN-gamma-primed BMM, L. donovani promastigotes strongly induced the phosphorylation of p38 MAPK and ERK1/2, and the use of selective inhibitors for ERK (PD98059) and p38 MAPK (SB203580) revealed that both kinases are required for L. donovani-induced TNF-alpha but not NO(2)(-) release. Collectively, these data suggest that both p38 MAPK and ERK1/2 pathways participate in some Leishmania-induced responses in IFN-gamma-primed BMM. The ability of L. donovani promastigotes to avoid MAPK and NF-kappaB activation in naive macrophages may be part of the strategy evolved by this parasite to evade innate immune responses.
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INRS-Institut Armand-Frappier, Université du Québec, Laval, Canada.
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D000818:Animals; D004789:Enzyme Activation; D005260:Female; D007371:Interferon-gamma / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D007893:Leishmania donovani / Q000276:immunology*; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology* / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D048051:p38 Mitogen-Activated Protein Kinases
D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D007371:Interferon-gamma; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases