1140-170 Hydrogen peroxide-induced superoxide production in endothelial cells: Role of nitric oxide synthase

Sepsis-associated encephalopathy is an early manifestation of sepsis, resulting in a diffuse dysfunction of the brain. Recently, nitric oxide (NO) has been proposed to be one of the key molecules involved in the modulation of inflammatory responses in the brain. The aim of this study was to assess the role of NO in cerebrovascular endothelial cell activation/dysfunction during the early onsets of sepsis. To this end, we employed an in vitro model of sepsis in which cultured mouse cerebrovascular endothelial cells (MCVEC) were challenged with blood plasma (20% vol/vol) obtained from sham or septic (feces-induced peritonitis, FIP; 6 h) mice. Exposing MCVEC to FIP plasma for 1 h resulted in increased production of reactive oxygen species and NO as assessed by intracellular oxidation of oxidant-sensitive fluorochrome, dihydrorhodamine 123 (DHR 123), and nitrosation of NO-specific probe, DAF-FM, respectively. The latter events were accompanied by dissociation of tight junction protein, occludin, from MCVEC cytoskeletal framework and a subsequent increase in FITC-dextran (3-kDa mol mass) flux across MCVEC grown on the permeable cell culture supports, whereas Evans blue-BSA (65-kDa mol mass) or FITC-dextran (10-kDa mol mass) flux were not affected. FIP plasma-induced oxidant stress, occludin rearrangement, and MCVEC permeability were effectively attenuated by antioxidant, 1-pyrrolidinecarbodithioic acid (PDTC; 0.5 mM), or interfering with nitric oxide synthase (NOS) activity [0.1 mM nitro-l-arginine methyl ester (l-NAME) or endothelial NOS (eNOS)-deficient MCVEC]. However, treatment of MCVEC with PDTC failed to interfere with NO production, suggesting that septic plasma-induced oxidant stress in MCVEC is primarily a NO-dependent event. Taken together, these data indicate that during early sepsis, eNOS-derived NO exhibits proinflammatory characteristics and contributes to the activation and dysfunction of cerebrovascular endothelial cells.

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Retinoic acid decreases nitric oxide production in endothelial cells: a role of phosphorylation of endothelial nitric oxide synthase at Ser1179

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2004.11.099 ◽

2005 ◽

Vol 326 (4) ◽

pp. 703-710 ◽

Cited By ~ 13

Author(s):

Du-Hyong Cho ◽

Yoon Jung Choi ◽

Sangmee Ahn Jo ◽

Jae-Hwan Nam ◽

Sung-Chul Jung ◽

...

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Retinoic Acid ◽

Nitric Oxide Synthase ◽

Endothelial Nitric Oxide Synthase ◽

Nitric Oxide Production ◽

Oxide Production ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

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Role of inducible nitric oxide synthase in the regulation of leucocyte recruitment

Clinical Science ◽

10.1042/cs1000001 ◽

2000 ◽

Vol 100 (1) ◽

pp. 1-12 ◽

Cited By ~ 34

Author(s):

Michael J. HICKEY

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Nitric Oxide Synthase ◽

Cell Types ◽

Adhesive Interactions ◽

Oxide Synthase ◽

Leucocyte Recruitment

Constitutively produced nitric oxide released by endothelial cells has been shown to act as an endogenous agent which inhibits the rolling and adhesion of leucocytes in the microcirculation. However, during various types of inflammation, expression of the inducible form of nitric oxide synthase (iNOS) can dramatically increase the amount of nitric oxide present in tissues. Furthermore, as iNOS can be expressed by a wide variety of cell types, the distribution of nitric oxide is likely to be altered relative to that in unstimulated tissue. Under these conditions, it is less well understood whether iNOS-derived nitric oxide retains the anti-adhesive capabilities of constitutively produced nitric oxide. This review summarizes work done to examine this issue. Three main approaches have been used. In vitro studies have examined the role of iNOS in adhesive interactions between stimulated endothelial cells and leucocytes, providing evidence of an anti-adhesive effect of iNOS. In addition, the role of iNOS has been examined in vivo in animal models of inflammation using pharmacological iNOS inhibitors. These experiments were extended by the advent of the iNOS-deficient (iNOS-/-) mouse. Intravital microscopy studies of these mice have indicated that, under conditions of low-dose endotoxaemia, iNOS-derived nitric oxide can inhibit leucocyte rolling and adhesion. The potential mechanisms for these effects are discussed. In contrast, several other studies have observed either no effect or an enhancing effect of iNOS on inflammatory leucocyte recruitment. Taken together, these studies suggest that the importance of iNOS in modulating leucocyte recruitment can vary according to the type of inflammatory response.

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