3-nitrotyrosine and Pleuropneumonia

1. The aim of this study was to investigate the effect of GW274150, a novel, potent and selective inhibitor of inducible nitric oxide synthase (iNOS) activity in a model of lung injury induced by carrageenan administration in the rats. 2. Injection of carrageenan into the pleural cavity of rats elicited an acute inflammatory response characterized by: fluid accumulation in the pleural cavity which contained a large number of polymorphonuclear cells (PMNs) as well as an infiltration of PMNs in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate (NO(x)), tumour necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta). 3. All parameters of inflammation were attenuated in a dose-dependent manner by GW274150 (2.5, 5 and 10 mg x kg(-1) injected i.p. 5 min before carrageenan). 4. Carrageenan induced an upregulation of the intracellular adhesion molecules-1 (ICAM-1), as well as nitrotyrosine and poly (ADP-ribose) (PAR) as determined by immunohistochemical analysis of lung tissues. 5. The degree of staining for the ICAM-1, nitrotyrosine and PAR was reduced by GW274150. These results clearly confirm that NO from iNOS plays a role in the development of the inflammatory response by altering key components of the inflammatory cascade. 6. GW274150 may offer a novel therapeutic approach for the management of various inflammatory diseases where NO and related radicals have been postulated to play a role.

Topics: Animals; Carrageenan; Disease Models, Animal; Enzyme Inhibitors; Intercellular Adhesion Molecule-1; Interleukin-1; Interleukin-1beta; Lung; Male; Malondialdehyde; Nitrates; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; Peptide Fragments; Peroxidase; Pleuropneumonia; Pneumonia; Poly(ADP-ribose) Polymerases; Rats; Rats, Sprague-Dawley; Sulfides; Tumor Necrosis Factor-alpha; Tyrosine

Evidence of nitric oxide synthase (NOS) 2 activity was determined by formation of nitrotyrosine (a reaction product of peroxynitrite) and by activation of poly(ADP-ribose) synthetase (PARS) in NOS2-expressed pleuropneumonic lungs from 20 pigs naturally infected with Actinobacillus pleuropneumoniae using immunohistochemistry. Intense immunostaining for nitrotyrosine residue was seen within the lung lesions from A. pleuropneumoniae-infected pigs, but it was minimal in the unaffected parts of the lung from A. pleuropneumoniae-infected pigs and in the normal lung from control pigs. Staining was especially strong in neutrophils and macrophages in the periphery of the lesions and within the alveolar spaces. There was close cell-to-cell correlation when serial sections were examined by immunohistochemistry for NOS2 and nitrotyrosine in each of the 20 lung samples. Expression of PARS was always present within inflammatory lesions but was minimal in the unaffected lung of A. pleuropneumoniae-infected pigs. Macrophages in alveolar spaces frequently exhibited strong staining for PARS. Colocalization of nitrotyrosine and PARS antigen was especially prominent in macrophages in the periphery of lesions. NOS2 expression in pleuropneumonic areas associated with protein nitrosation and PARS suggests that NOS2 is functionally active during infections caused by A. pleuropneumoniae.

Topics: Actinobacillus Infections; Actinobacillus pleuropneumoniae; Animals; Antigens, Viral; Enzyme Induction; Immunohistochemistry; Lung; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Pleuropneumonia; Poly(ADP-ribose) Polymerases; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Swine; Swine Diseases; Tyrosine