title: Immunomodulatory role of interleukin-10 in visceral leishmaniasis: defective activation of protein kinase C-mediated signal transduction events.
abstract: Leishmania donovani, an intracellular protozoan parasite, challenges host defense mechanisms by impairing the signal transduction of macrophages. In this study we investigated whether interleukin-10 (IL-10)-mediated alteration of signaling events in a murine model of visceral leishmaniasis is associated with macrophage deactivation. Primary in vitro cultures of macrophages infected with leishmanial parasites markedly elevated the endogenous release of IL-10. Treatment with either L. donovani or recombinant IL-10 (rIL-10) inhibited both the activity and expression of the Ca2+-dependent protein kinase C (PKC) isoform. However, preincubation with neutralizing anti-IL-10 monoclonal antibody (MAb) restored the PKC activity in the parasitized macrophage. Furthermore, we observed that coincubation of macrophages with rIL-10 and L. donovani increased the intracellular parasite burden, which was abrogated by anti-IL-10 MAb. Consistent with these observations, generation of superoxide (O2-) and nitric oxide and the release of murine tumor necrosis factor-alpha were attenuated in response to L. donovani or rIL-10 treatment. On the other hand, preincubation of the infected macrophages with neutralizing anti-IL-10 MAb significantly blocked the inhibition of nitric oxide and murine tumor necrosis factor-alpha release by the infected macrophages. These findings imply that infection with L. donovani induces endogenous secretion of murine IL-10, which in turn facilitates the intracellular survival of the protozoan and orchestrates several immunomodulatory roles via selective impairment of PKC-mediated signal transduction.
authors.affiliation: Department of Microbiology, Bose Institute, Calcutta 700 054, India.
authors.forename: S
authors.initials: S
authors.lastname: Bhattacharyya
authors.forename: S
authors.initials: S
authors.lastname: Ghosh
authors.forename: P L
authors.initials: PL
authors.lastname: Jhonson
authors.forename: S K
authors.initials: SK
authors.lastname: Bhattacharya
authors.forename: S
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002455:Cell Division; D004789:Enzyme Activation; D016753:Interleukin-10 / Q000276:immunology*; D007527:Isoenzymes / Q000378:metabolism; D007898:Leishmaniasis, Visceral / Q000276:immunology*; D017737:Macrophages, Peritoneal / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000276:Adjuvants, Immunologic; D007527:Isoenzymes; D009573:Nitrites; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D016753:Interleukin-10; D009569:Nitric Oxide; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases