2-2--(hydroxynitrosohydrazono)bis-ethanamine and Inflammation

Inflammation is known to cause significant neuronal damage and axonal injury in many neurological disorders. Among the range of inflammatory mediators, nitric oxide is a potent neurotoxic agent. Recent evidence has suggested that cellular peroxisomes may be important in protecting neurons from inflammatory damage. To assess the influence of peroxisomal activation on nitric oxide-mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator-activated receptor (PPAR)-α agonist fenofibrate on cortical neurons exposed to a nitric oxide donor or co-cultured with activated microglia. Fenofibrate protected neurons and axons against both nitric oxide donor-induced and microglia-derived nitric oxide-induced toxicity. Moreover, cortical neurons treated with this compound showed a significant increase in gene expression of ABCD3 (the gene encoding for peroxisomal membrane protein-70), with a concomitant increase in protein levels of PPAR-α and catalase, which was associated with a functional increase in the activity of this enzyme. Collectively, these observations provide evidence that modulation of PPAR-α activity and peroxisomal function by fenofibrate attenuates nitric oxide-mediated neuronal and axonal damage, suggesting a new therapeutic approach to protect against neurodegenerative changes associated with neuroinflammation.

Topics: Animals; Catalase; Cell Survival; Cells, Cultured; Cerebral Cortex; Coculture Techniques; Fenofibrate; Hypolipidemic Agents; Inflammation; Inflammation Mediators; Interferon-gamma; Lipopolysaccharides; Microglia; Neurons; Neuroprotective Agents; Nitric Oxide; Nitric Oxide Donors; Nitroso Compounds; Peroxisomes; PPAR alpha; Rats; Rats, Wistar

The hypothesis that the NO/cGMP pathway modulates PMN adhesion to human brain microvessel endothelial cells (HBMEC) was examined. Human PMN were incubated with resting or TNF-alpha-treated endothelial monolayers, and adhesion was quantified by light microscopy. TNF-alpha upregulated PMN adhesion in a time-dependent manner. Treatment of HBMEC with the NO donors SNP and DETA NONOate for 4 or 24 h decreased PMN adhesion. This was completely reversed by the guanylyl cyclase inhibitor ODQ, while addition of a cGMP agonist (8-Br-cGMP) decreased PMN adhesion. NO donors did not affect the levels of E-selectin or ICAM-1 in HBMEC. However, pre-treatment of PMN with NO donors or 8-Br-cGMP decreased their adhesion to recombinant E-selectin and ICAM-1, suggesting an effect of NO on PMN. These findings indicate that NO modulates PMN-HBMEC interactions through cGMP and decreases the binding of PMN to the adhesion molecules E-selectin and ICAM-1.

Topics: Blotting, Western; Brain; Cell Adhesion; Cells, Cultured; Cyclic GMP-Dependent Protein Kinases; E-Selectin; Endothelial Cells; Endothelium, Vascular; Humans; Inflammation; Intercellular Adhesion Molecule-1; Microcirculation; Models, Biological; Neutrophils; Nitric Oxide; Nitroso Compounds; Signal Transduction; Time Factors; Tumor Necrosis Factor-alpha; Up-Regulation

During inflammatory responses in the brain, the expression of cytochrome P450 isoforms in the CNS are modulated and the capacity of the brain to metabolize drugs and to synthesize or degrade certain endogenous chemicals and drugs is diminished. While this response can be attributed in part, to the production and action of cytokines within the brain, it is also likely that other inflammatory mediators play an integral role. This paper investigates a potential role for nitric oxide (NO) in the loss of cytochrome P450 (CYP1A) in the brain during inflammation. Escherichia coli lipopolysaccharide (LPS), a commonly used proinflammatory endotoxin, was incubated with cultured rat astrocytes to provide a model of inflammation in the CNS. CYP1A activity was significantly decreased in cultured astrocytes incubated with LPS for 24 h. This loss in enzyme activity was accompanied by a substantial production of nitric oxide (NO) by these cells. Immunohistochemical examination demonstrated an upregulation of inducible nitric oxide synthase (iNOS) expression following the exposure of astrocytes to LPS. The addition of a selective iNOS blocker (1400W) caused a partial but significant reversal of the LPS-mediated loss in CYP1A. The incubation of astrocytes with the NO-generating compound (DETA NONOate) resulted in a loss of CYP1A. Taken together, these observations suggest that NO plays a pivotal role in the inflammation mediated loss in CYP1A activity in the brain.

Topics: Amidines; Animals; Astrocytes; Benzylamines; Cells, Cultured; Cytochrome P-450 CYP1A1; Enzyme Inhibitors; Immunohistochemistry; Inflammation; Lipopolysaccharides; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitroso Compounds; Rats

Nitric oxide (NO) appears to act as an inflammatory mediator on monocytic cells. Exogenous NO augmented release of chemokines from human promonocytic U937 cells and peripheral blood mononuclear cells. Pharmacological strategies aiming at modulation of NO-induced release of interleukin-8 (IL-8) were investigated in U937 cells in detail. Release of IL-8 was down-regulated by transforming growth factor beta2 (TGF-beta2), by the protein tyrosine-kinase inhibitor genistein, and via rises in intracellular cyclic AMP, generated by prostaglandin E(2), rolipram, pentoxifylline, forskolin, or dibutyryl-cyclic AMP. In addition, incubation with the synthetic glucocorticoid dexamethasone or suppression of activity of p38 mitogen-activated protein (MAP) kinases by SB-203580 modulated release of IL-8. Activation of p38 MAP kinases was confirmed by the demonstration of an augmented appearance of phosphorylated p38 in the presence of NO. The present data suggest that exposure to exogenous NO resembles activation of U937 cells by proinflammatory stimuli. The anti-inflammatory cytokine TGF-beta2, as well as anti-inflammatory or immunosuppressive agents such as genistein, pentoxifylline, rolipram, dexamethasone, and SB-203580 modulate inflammatory, chemokine-inducing actions of NO.

Topics: Chemokine CCL4; Chemokines; Cyclic AMP; Dexamethasone; Enzyme Inhibitors; Genistein; Humans; Imidazoles; Inflammation; Interleukin-8; Macrophage Inflammatory Proteins; Mitogen-Activated Protein Kinases; Monocytes; Nitric Oxide; Nitric Oxide Donors; p38 Mitogen-Activated Protein Kinases; Protein-Tyrosine Kinases; Pyridines; Signal Transduction; Tetradecanoylphorbol Acetate; Transforming Growth Factor beta; Triazenes; U937 Cells

Topics: Action Potentials; Animals; Axons; Electric Stimulation; Female; Ganglia, Spinal; Inflammation; Male; Nervous System Diseases; Nitric Oxide; Nitric Oxide Donors; Nitrogen Oxides; Nitroso Compounds; Rats; Rats, Inbred Lew; Rats, Sprague-Dawley; Rats, Wistar; Spermine; Spinal Cord; Spinal Nerve Roots