title: Control of nitric oxide production by endogenous TGF-beta1 and systemic nitric oxide in retinal pigment epithelial cells and peritoneal macrophages.
abstract: Both in vivo and in vitro experiments demonstrate that transforming growth factor-beta1 (TGF-beta1) suppresses expression of the inducible form of nitric oxide synthase (iNOS). In this study, we examined the effects of exogenous and endogenous TGF-beta1 on retinal pigment epithelial (RPE) cells and resident peritoneal macrophages ex vivo using cells from TGF-beta1 null (TGF-beta1-/-) mice or age-matched wild-type (TGF-beta1+/+) or heterozygous (TGF-beta1+/-) littermates. RPE cells from both TGF-beta1-/- mice and TGF-beta1+/+ littermates produced NO and were immunocytochemically positive for iNOS protein only following treatment with interferon-gamma (IFN-gamma) and bacterial lipopolysaccharide (LPS); however, RPE cells from TGF-beta1-/- mice produced 40% more NO than cells from TGF-beta1+/+ mice. In contrast, resident peritoneal macrophages from both TGF-beta1+/+ and TGF-beta1-/- mice expressed iNOS protein without stimulation and in the absence of detectable production of NO. The expression of iNOS was increased by treatment with IFN-gamma, resulting in detectable levels of NO. Macrophages from TGF-beta1+/+ mice appeared to produce NO in a manner inversely proportional to the serum content of NO2- and NO3- of the mice from which the cells were obtained; no such correlation existed in TGF-beta1+/- or TGF-beta1-/- mice. Treatment of RPE cells or macrophages from both TGF-beta1+/+ and TGF-beta1-/- mice with exogenous TGF-beta1 decreased both iNOS protein and NO production. These findings demonstrate a novel role of endogenous TGF-beta1 in coupling systemic NO production to the production of NO by macrophages, and demonstrate that endogenous and exogenous TGF-beta1 can act differently to suppress NO production.
authors.affiliation: Laboratory of Chemoprevention, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Vodovotz
authors.forename: J J
authors.initials: JJ
authors.lastname: Letterio
authors.forename: A G
authors.initials: AG
authors.lastname: Geiser
authors.forename: L
authors.initials: L
authors.lastname: Chesler
authors.forename: A B
authors.initials: AB
authors.lastname: Roberts
authors.forename: J
authors.initials: J
authors.lastname: Sparrow
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D007166:Immunosuppressive Agents / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000378:metabolism*; D011090:Polyenes / Q000494:pharmacology; D020123:Sirolimus; D016212:Transforming Growth Factor beta / Q000494:pharmacology / Q000502:physiology*
chemical_list: D007166:Immunosuppressive Agents; D011090:Polyenes; D016212:Transforming Growth Factor beta; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D020123:Sirolimus