Interferon-gamma- and lipopolysaccharide-induced tumor necrosis factor-alpha is required for nitric oxide production: tumor necrosis factor-alpha and nitric oxide are independently involved in the killing of Mycobacterium microti in interferon-gamma- and lipopolysaccharide-treated J774A.1 cells.
A comparative study was done using J774A.1 and J774A.1-derived transfected cells (J774A.1 C.1) containing antisense tumor necrosis factor alpha (TNF-alpha) plasmid to determine the role of endogenous TNF-alpha on nitric oxide production as well as on the growth of Mycobacterium microti in interferon gamma (IFN-gamma)- and lipopolysaccharide (LPS)-treated cells. On stimulation with IFN-gamma and LPS a higher level of NO was observed in J774A.1 cells compared to J774A.1 C.1 which indicated that endogenous TNF-alpha is required for the production of NO. Comparing the effect of IFN-gamma and LPS on the intracellular growth of M. microti, the growth-reducing activity was higher in J774A.1 cells than in J774A.1 C.1 cells and was not completely abrogated in the presence of the nitric oxide inhibitor NG-methyl-L-arginine (L-NMA). J774A.1 C.1 cells infected with M. microti produced a significant amount of NO when exogenous TNF-alpha was added along with IFN-gamma and LPS and the concentration of intracellular bacteria decreased almost to that in IFN-gamma and LPS treated parental J774A.1 cells. Addition of exogenous TNF-alpha even in the presence of L-NMA in J774A.1 C.1 cells could also partially restore intracellular growth inhibition of M. microti caused by IFN-gamma and LPS. TNF-alpha is probably required for the production of NO in J774A.1 cells by IFN-gamma and LPS but TNF-alpha and NO are independently involved in the killing of intracellular M. microti with IFN-gamma and LPS.
Majumdar
S
S
Institute of Microbial Technology, Chandigarh 160 036, India. majumdar@hotmail.com
Gupta
R
R
Dogra
N
N
D000818:Animals; D002460:Cell Line; D015169:Colony Count, Microbial; D007371:Interferon-gamma / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology / Q000382:microbiology; D051379:Mice; D009161:Mycobacterium / Q000254:growth & development* / Q000472:pathogenicity; D009164:Mycobacterium Infections / Q000382:microbiology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D010957:Plasmids; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse