Nitric oxide synthase inflammatory response

To set up and validate the in vitro systems we initiated a study with rat Uver slices. Stimulation by Upopolysaccharide (LPS) in liver slices was used to evoke a pro-inflammatory response in the Uver. Lipopolysaccharide (LPS), a component of Gram-negative bacterial ceU walls (also called endotoxin), has been associated with tissue injury and sepsis. In the Uver LPS activates the resident macrophages, the Kupffer ceUs, which results in cytokine release [96]. Furthermore, LPS is cleared by the Uver, mainly by Kupffer ceUs [97]. One of the major features of endotoxic shock is the induction of nitric oxide S5mthase in the Uver [98]. Inducible nitric oxide synthase (iNOS), the expression of which is induced by LPS and cytokines, produces nitric oxide (NO) in large quantities [99]. 

The mechanistic basis of the neuroprotective activity of FAEE appears to rely not only on its general free-radical trapping or antioxidant activity per se, but also on its activity in mediating the induction of stress response proteins (HO-1 and F1SP72), cytoprotective (phase 2) proteins, and the parallel suppression of genes induced by pro-inflammatory cytokines, such as nitric oxide synthase (iNOS). 

In addition to direct effects on genes regulating inflammation, glucocorticoids also inhibit the transcription factors that initiate synthesis of pro-inflammatory cytokines (e.g., interleukin-1, tumor necrosis factor), enzymes (e.g., COX-2, nitric oxide synthase), and receptor proteins (e.g., natural killer receptors).17,87,89 Glucocorticoids may also exert some of their effects via a membrane-bound receptor that regulates activity of macrophages, eosinophils, T lymphocytes, and several other types of cells involved in the inflammatory response.89 Consequently, glucocorticoids affect many aspects of inflammation, and their powerful anti-inflammatory effects in rheumatoid arthritis result from their ability to blunt various cellular and chemical components of the inflammatory response. 

It decreases the production of inducible nitric oxide synthase, which is responsible for the release of pro-inflammatory nitric oxide. 

As the CNS representatives of the monocytic cell lineage, microglia undergo an inflammatory type of activation in response to brain injury and stress. Among the products of microglia activated by inflammatory signals is nitric oxide, which is produced by the exquisitely NF-KB-sensitive, inducible nitric oxide synthase. This enzyme can be elevated in an NF-xB-dependent manner in astrocytes (Akama et al.,... 

Kim OS, Park EJ, Joe E-H, Jou I (2002) JAK-STAT signaling mediates gtmgliosides-induced inflammatory responses in brain microglial cells. J Biol Chem 277 40594-40601 Kong G-Y, Peng Z-C, Costanzo C, Kristensson K, Bentivoglio M (2000) Inducible nitric oxide synthase expression elicited in the mouse brain by inflammatory mediators circulating in the... 

The innate pro-inflammatory response of these cells is activated upon exposure to LPS, prostaglandin or other TLR ligands, leading to production of classical proinflammatory cytokines including tumor necrosis factor (TNF)-a. On the other hand, classical activation by interferon (fFN)- /andLPS leads to production of TNF-a and also increased secretion of reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS). 

The molecular mechanism linking the inflammatory response to redox equilibria and modification of nitric oxide production will be explored in an animal model system of septic shock, a generalized inflammation induced by bacterial lipopolisaccharide (LPS). It is known that endotoxemia induces a complex interplay between the activation of nuclear transcription factors such as nuclear factor kappa B (NFkB) and a cascade-activation of various enzymatic activities, mostly mediators of the inflammatory response with particular attention to the variation of the inducible form of nitric oxide synthase (iNOS). 

Nitric oxide ( NO) also contributes to the alveolar epithelium s oxidant burden, primarily as a result of the formation of reactive oxygen or nitrogen species. NO, one of the smallest and most distinctive biological mediators, is generated by nitric oxide synthase (NOS) which has three isoforms neuronal (nNOS, isoform I), inducible (iNOS, isoform II) and endothelial (eNOS, isoform III). nNOS and eNOS are constitutively expressed in cells and generate NO in small quantities for brief periods of time in response to increased intracellular CA2+ concentrations. It is currently unclear whether the level of expression or the enzymatic activity or either eNOS or nNOS is modulated by pathogens or inflammatory stimuli. 

Y. Hayashi, Y. Sawa, N. Fukuyama, H. Nakazawa, H. Matsuda, Preoperative glutamine administration induces heat-shock protein 70 expression and attenuates cardiopulmonary bypass-induced inflammatory response by regulating nitric oxide synthase activity, Circulation 106, 2601-07 (2002). 

Exhaled nitric oxide was used as the marker of airway inflammation after patients who had asthma were found to have increased levels of exhaled nitric oxide and nitric oxide synthase expression [17]. Exhaled nitric oxide correlated with a response to steroid, defined as change in pulmonary function testing, asthma symptoms, and BHR [18]. Patients who have symptoms of asthma who respond to steroids have higher exhaled nitric oxide than those who do not, implying inadequate anti-inflammatory treatment. The cutoff of exhaled nitric oxide for steroid response was determined to be approximately 48 parts per billion in one study [18], but no standards are widely used. 

Increased cytokine production may also play a role in silica-induced autoimmune vascular disease. Adhesion molecule expression is elevated on vascular endothelial cells in response to TNF-a and IL-1. Adhesion molecules such as endothelial leukocyte adhesion molecule-1 (ELAM-1) and intercellular adhesion molecule-1 (ICAM-1) recruit inflammatory cells to specific sites on the vascular endothelium, and it has been hypothesized that vascular pathology following silica exposure may be the result of this interaction (Nowack et al., 1998). IFN-y is expressed at elevated levels by lymphocytes in silicotic thoracic lymph nodes and may be responsible for the long-lasting inducible nitric oxide synthase (iNOS) expression in these tissues (Friedetzky et al., 2002). The increase in IFN-y may also cause a shift towards a dominant Thl response, contributing to the maintenance of a chronic inflammatory state in silica-containing lymph nodes (Gam et al., 2000). 

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