5-Lipoxygenase and cyclooxygenase-2 in the lungs of pigs naturally affected by enzootic pneumonia and porcine pleuropneumonia.

Enzootic pneumonia by Mycoplasma hyopneumoniae and pleuropneumonia by Actinobacillus pleuropneumoniae are among the most common and economically relevant pulmonary diseases in swine herds. We herein investigated the activity and expression of 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) in healthy and diseased porcine lungs, by means of immunohistochemical, immunochemical and biochemical assays. Diseased lungs showed a significantly higher activity and expression of 5-LOX and COX-2 in a wide range of cell types, thus suggesting the likely involvement of both enzymes in the pathogenesis of bacterial porcine pneumonia. Consistently, increased enzyme activities were paralleled by increased leukotriene B(4) (LTB(4)), a 5-LOX product and prostaglandin E(2) (PGE(2)), a COX-2 product, content in diseased versus healthy lungs.

Expression of nitric oxide synthase 2 and cyclooxygenase-2 in swine experimentally infected with Actinobacillus pleuropneumoniae.

The expression of inflammatory mediators was examined in pigs experimentally infected with Actinobacillus pleuropneumoniae. The activity of nitric oxide synthase 2 (NOS2) and cyclooxygenase-2 (COX-2) was determined by measuring nitric oxide (NO) and prostaglandin E2 (PGE2) in bronchoalveolar lavage fluid in response to A. pleuropneumoniae in vivo. By in situ hybridization and immunohistochemistry, both NOS2 and COX-2 enzymes were detected in neutrophils and macrophages that had infiltrated into alveolar spaces. The sharp increase in PGE2 concentration preceded the increase in the concentrations of NO. NO levels were highly correlated with PGE2 level (rs=0.7218, P <0.05). The NO levels were positively correlated with lung lesion scores (rs=0.9087, P <0.05) until 24 hours postinoculation (hpi) as were the lung lesion scores and PGE2 levels (rs=0.925, P <0.01). High levels of PGE2 produced by COX-2 are generated in early infection (6 hpi). However, in later stages of infection (12-36 hpi), there is participation of NO and PGE2 accompanied by coinduction of both NOS2 and COX-2.

Evidence of nitric oxide synthase 2 activity in swine naturally infected with Actinobacillus pleuropneumoniae.

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.

Diagnostic value of lactate dehydrogenase isoenzyme pattern in pleural effusions.

Lactate dehydrogenase isoenzymes have been used to classify the nature of pleural effusion. Nevertheless, studies have reported conflicting results. The objective of this study was to evaluate the diagnostic value of lactate dehydrogenase isoenzymes in the analysis of pleural effusions. Pleural fluid samples obtained from three respective diagnostic groups: group I transudate (n = 23), group II parapneumonic effusion (n = 29) and group III malignant effusion or pleuritis carcinomatosa (n = 41) were evaluated. Total lactate dehydrogenase activity and lactate dehydrogenase (LDH) isoenzyme pattern were significantly different between transudative (group I) and exudative (group II and III) effusions. Group II and III showed a low percentage of LDH1 (p < 0.001), whereas the percentages of LDH4 (p < 0.001) and LDH5 (p < 0.001) were higher compared to group I. Moreover, in exudative effusions the percentage of LDH1 (p < 0.005), LDH4 (p < 0.005), as well as LDH5 (p < 0.005) were significantly different between parapneumonic and malignant effusions. In contrast to relative lactate dehydrogenase isoenzyme values, the absolute values of lactate dehydrogenase isoenzymes did not differ between group II and group III. Logistic regression analysis yielded a strong discrimination between group I and II+III, simultaneously using lactate dehydrogenase, glucose and protein as explanatory variables. Logistic regression analysis yielded only a weak discrimination between group II and III, simultaneously using lactate dehydrogenase, glucose and the absolute values of LDH2 and LDH4 as explanatory variables. In conclusion, the lactate dehydrogenase isoenzyme pattern differed between pleural effusions of transudative and exudative origin. However, including lactate dehydrogenase isoenzyme activities in the biochemical work-up of pleural effusions did not reveal an additional discriminatory value in the assessment of the classification of these effusions.

Decreased glucose in RA-cell-positive pleural effusion: correlation of pleural glucose, lactic dehydrogenase and protein concentration to the presence of RA-cells.

A significant correlation between RA-cells in the pleural fluid and lowered concentration of glucose, increased LDH activity and protein content was demonstrated in pleural effusions of diverse etiology. The finding might suggest a common metabolic reaction of the pleura, the mechanism of which remains unexplained at present.