title: The curative effect of fucoidan on visceral leishmaniasis is mediated by activation of MAP kinases through specific protein kinase C isoforms.
abstract: Fucoidan can cure both antimony-sensitive and antimony-resistant visceral leishmaniasis through immune activation. However, the signaling events underlying this cellular response remain uncharacterized. The present study reveals that fucoidan induces activation of p38 and ERK1/2 and NF-κB DNA binding in both normal and Leishmania donovani-infected macrophages, as revealed by western blotting and electrophoretic mobility shift assay (EMSA), respectively. Pharmacological inhibition of p38, ERK1/2 or the NF-κB pathway markedly attenuated fucoidan-induced pro-inflammatory cytokine synthesis and inducible nitric oxide synthase (iNOS) gene transcription, resulting in a reduction of parasite clearance. To decipher the underlying mechanism of fucoidan-mediated parasite suppression, the expression and functionality of various protein kinase C (PKC) isoforms were evaluated by immunoblotting and enzyme activity assay. Fucoidan elicited an increase in expression and activity of PKC-α, -βI and -βII isoforms in infected macrophages. Functional knockdown of PKC-α and -β resulted in downregulation of p38 and ERK1/2, along with a marked reduction of IL-12 and TNF-α production in fucoidan-treated infected macrophages. Collectively, these results suggest that the curative effect of fucoidan is mediated by PKC-dependent activation of the mitogen-activated protein kinase (MAPK)/NF-κB pathway, which ultimately results in the production of nitric oxide (NO) and disease-resolving pro-inflammatory cytokines.
authors.affiliation: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Gunjan
authors.initials: G
authors.lastname: Sharma
authors.affiliation: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Susanta
authors.initials: S
authors.lastname: Kar
authors.affiliation: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Writoban
authors.initials: W
authors.lastname: Basu Ball
authors.affiliation: Department of Biochemistry, Calcutta University, Kolkata, India.
authors.forename: Kuntal
authors.initials: K
authors.lastname: Ghosh
authors.affiliation: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
authors.forename: Pijush K
authors.initials: PK
authors.lastname: Das
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology / Q000627:therapeutic use; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D007109:Immunity / Q000187:drug effects; D018836:Inflammation Mediators / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007893:Leishmania donovani / Q000187:drug effects; D007898:Leishmaniasis, Visceral / Q000188:drug therapy* / Q000201:enzymology* / Q000276:immunology / Q000469:parasitology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D011134:Polysaccharides / Q000494:pharmacology / Q000627:therapeutic use*; D011493:Protein Kinase C / Q000378:metabolism*; D013843:Thiazines / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism
chemical_list: C093124:2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine; D000911:Antibodies, Monoclonal; D018836:Inflammation Mediators; D007527:Isoenzymes; D016328:NF-kappa B; D011134:Polysaccharides; D013843:Thiazines; D018808:Transcription Factor AP-1; C007789:fucoidan; D052247:Nitric Oxide Synthase Type II; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases