Down-regulation of inducible nitric-oxide synthase (NOS-2) during parasite-induced gut inflammation: a path to identify a selective NOS-2 inhibitor.
Nitric oxide (NO) possesses potent anti-inflammatory properties; however, an over-production of NO will promote inflammation and induce cell and tissue dysfunction. Thus, the ability to precisely regulate NO production could prove beneficial in controlling damage. In this study, advantage was taken of the well characterized inflammatory response caused by an intestinal parasite, Trichinella spiralis, to study the relationship between intestinal inflammation and the regulation of nitric oxide synthase-type 2 (NOS-2) expression. Our study revealed that a specific gut inflammatory reaction results in inhibition of NOS-2 expression. Characteristics of this inhibition are: 1) local jejunal inflammation induced by T. spiralis systemically inhibits NOS-2 gene transcription, protein expression, and enzyme activity; 2) the inhibition blunts endotoxin-stimulated NOS-2 expression; 3) the inhibition does not extend to the expression of other isoforms of NOS, to paxillin, a housekeeper protein, or to cyclooxygenase-2, another protein induced by proinflammatory cytokines; 4) the inhibition is unlikely related to the formation of specific anti-parasite antibodies; and 5) the inhibition may involve substances other than stress-induced corticosteroids. Elucidation of such potent endogenous NOS-2 down-regulatory mechanisms could lead to the development of new strategies for the therapy of inflammatory conditions characterized by the overproduction of NO.
Department of Integrative Biology and Pharmacology, The University of Texas-Houston Medical School, Houston, Texas 77030-0708, USA.
K
K
Bian
Y
Y
Harari
M
M
Zhong
M
M
Lai
G
G
Castro
N
N
Weisbrodt
F
F
Murad
D000818:Animals; D015536:Down-Regulation / Q000235:genetics; D007082:Ileum / Q000201:enzymology / Q000469:parasitology; D007249:Inflammation / Q000201:enzymology* / Q000276:immunology; D007413:Intestinal Mucosa / Q000201:enzymology / Q000469:parasitology; D007421:Intestine, Small / Q000201:enzymology* / Q000276:immunology / Q000469:parasitology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000378:metabolism; D017160:Trichinella spiralis / Q000276:immunology; D014235:Trichinellosis / Q000201:enzymology* / Q000276:immunology
D008070:Lipopolysaccharides; D012333:RNA, Messenger; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse