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fMLP‐induced in vitro nitric oxide production and its regulation in murine peritoneal macrophages
Author(s) -
Sodhi Ajit,
Biswas Subhra K.
Publication year - 2002
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.71.2.262
Subject(s) - nitric oxide , biology , wortmannin , chemokine , sodium orthovanadate , macrophage , microbiology and biotechnology , kinase , phosphatase , in vitro , phosphorylation , inflammation , biochemistry , signal transduction , pi3k/akt/mtor pathway , immunology , endocrinology
Bacterial N ‐formyl peptides such as N ‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP) are important mediators of monocyte/macrophage recruitment and activation at the sites of inflammation. In the current study, the role of nitric oxide (NO) in the activation of murine peritoneal macrophages to tumoricidal state in response to in vitro fMLP treatment has been investigated. Murine peritoneal macrophages on treatment with fMLP showed a dose‐ and time‐dependent production of NO together with increased tumoricidal activity against P815 mastocytoma cells. L‐NMMA, a specific inhibitor of L‐arginine pathway, inhibited the fMLP‐induced NO secretion and macrophage‐mediated tumoricidal activity against P815 cells. These results indicate the L‐arginine‐dependent production of NO to be one of the effector mechanisms contributing to the tumoricidal activity of fMLP‐treated macrophages. The expression of iNOS protein and iNOS mRNA is also observed. The pharmacological inhibitors genistein, wortmannin, H7, PD98059, TPCK, and pertussis toxin (PTX) blocked the fMLP‐induced NO production, suggesting the involvement of tyrosine kinases, PI3K, PKC, p42/44 MAPkinase, NF‐κB, and G‐proteins. The expression of phospho‐p42/44 MAPK and phospho‐IκB was also observed. The role of protein phosphatases in the above pathway has been suggested using the specific inhibitors of these phosphatases, i.e., okadaic acid and sodium orthovanadate.