Alterations in lung and skin compositions of rat in bleomycin-induced fibrosis

Epigallocatechin-3-gallate exhibits anti-fibrotic effect by attenuating bleomycin-induced glycoconjugates, lysosomal hydrolases and ultrastructural changes in rat model pulmonary fibrosis

Pulmonary fibrosis is characterized by excessive deposition of extracellular matrix components in the alveolar space, which hampers normal respiration process. Pathophysiological enzymes, glycoprotein moieties and matrix degrading lysosomal hydrolases are key markers and play a crucial role in the progression of fibrosis. Bleomycin is an anti-neoplastic drug, used for the treatment of various types of cancers and induces pulmonary fibrosis due its deleterious side effect. Tea catechin epigallocatechin-3-gallate (EGCG) is known for its wide array of beneficial effects. The present study was intended to evaluate the beneficial efficacy of EGCG against bleomycin-induced glycoconjugates, lysosomal hydrolases and ultrastructural changes in the lungs of Wistar rats. Intratracheal instillation of bleomycin (6.5 U/kg body weight) to rats increased the activities of pathophysiological enzymes such as aspartate transaminase, alanine transaminase, lactate dehydrogenase and alkaline phosphatase, which were attenuated upon EGCG treatment. The increased level of hydroxyproline and histopathological parameters in bleomycin-induced rats were decreased upon EGCG treatment. Bleomycin-induced increase in the level of glycoconjugates was restored closer to normal levels on EGCG treatment. Furthermore, the increased activities of matrix degrading lysosomal enzymes in bleomycin-induced rats were reduced upon EGCG supplementation. Treatment with EGCG also attenuated bleomycin-induced ultrastructural changes as observed from transmission electron microscopy studies. The results of the present study put-forward EGCG as a potential anti-fibrotic agent due to its attenuating effect on potential fibrotic markers.

A new model of hepatic fibrosis induced by intra-arterial injection of iodized oil and pingyangmycin emulsions

AIM: To investigate the feasibility of setting up a hepatic fibrosis model by intra-arterial injection of emulsions of iodized oil and pingyangmycin.

METHODS: Twenty-four Japanese big-ear rabbits were divided into sham-operation, experiment A and B group according to the doses of emulsions of iodized oil and pingyangmycin (1.2 and 2.0 mg for A and B, respectively) injected into the hepatic artery. The live specimens were obtained 1, 2, 4, 6, 10, and 14 wk after injection. The histological changes were determined by HE staining, and the contents of platelet derived growth factor-B (PDGF-B) were detected by immunohistochemical staining.

RESULTS: Six weeks after injection, typical features of fibrosis appeared in all the liver tissues of group A and B, and the pseudolobules formed in some tissues. In group B, sclerosis with a diameter of 1.0 cm was found in one of the four rabbits at 10th week under light microscope. The contents of PDGF-B were significantly increased in A and B group as compared with those in sham-operation group 1, 2, 4, and 6 wk after injection (integral optical density: 118714±14941, 154344±25102 vs 42745±871, P <0.01; 130399±11690, 164855±15486 vs 44052±1043, P <0.01; 116594±21230, 147099±20317 vs 41081±769, P <0.01; 101732±8794, 124177±20429 vs 46366±975, P <0.01).

CONCLUSION: The model of hepatic fibrosis can be established successfully by injection of iodized oil and pingyangmycin emulsions into the hepatic artery. PDGF-B plays an important role in the progress of fibrosis as a promoter.

Biochemical and connective tissue changes in cyclophosphamide-induced lung fibrosis in rats

The present investigation was designed to characterize the biochemical and connective tissue components and to correlate the significance of morphological and biochemical perturbations in cyclophosphamide (CP)-induced lung fibrosis in rats. Lung fibrosis was induced in male Wistar rats by intraperitoneal injection of 20 mg/100 g body weight of CP, and their pneumotoxic derangements were characterized during an early destructive phase followed by a proliferative and synthetic phase. Serum angiotensin-converting enzyme (ACE) activity was higher in CP-treated rats at days 2, 3, 5, 7, and 11, but there was a significant decrease in lung ACE activity during the same time period. Elevated levels of beta-glucuronidase activity were observed in the lung lavage fluid of CP-administered rats days 2, 3, 5, and 7. Lung myeloperoxidase activity was higher in CP rats. Of significance was the presence of collagenase and collagenolytic cathepsin in the lavage fluid of CP rats, when compared with the barely detectable levels in controls. A similar increase in these enzyme activities was also noticed in the lung tissue of CP rats during the same experimental period. Lavage fluid hydroxyproline content was higher in CP rats when compared with controls. Similarly, lung protein and DNA levels were elevated significantly after treatment with CP. The pulmonary histamine and serotonin contents were significantly higher in CP rats. The incorporation of [3H]thymidine into lung total DNA, [3H]proline into lung hydroxyproline, and [35S]sulphate into lung glycosaminoglycan, measured as indicators of lung DNA, collagen, and glycosaminoglycan synthesis, respectively, was also higher in CP groups. Increased levels of hydroxyproline, elastin, hexosamine, total hexose, fucose, sialic acid, and uronic acid in the lungs of rats 14, 28, and 42 days after CP insult were characterized as biomarkers of CP-induced interstitial changes. These findings indicate that CP-induced lung fibrosis results in alterations not only in collagen synthesis and accumulation, but also in glycosaminoglycan and glycoprotein content.

Glycoprotein composition in cyclophosphamide-induced lung fibrosis

The present study investigated the glycosylation state of proteins in lung tissue of a cyclophosphamide-induced model of pulmonary fibrosis in rats. In fibrotic lung, the carbohydrate constituents (total hexose, fucose, sialic acid and hexosamine) of salt-soluble, collagenase, elastase and papain digested glycoproteins were significantly higher compared to normal lungs. Interestingly, fibrotic lung tissues had higher activities of mannosyl, glucosyl, galactosyl, sialyl and fucosyl transferases than normal lung tissues. Similarly, mannosyl, glucosyl, galactosyl, sialyl and fucosyl transferases were higher in serum from rats with fibrosis than in that from normals. These data indicate that glycoprotein metabolism is significantly altered from normal in animals with interstitial lung fibrosis.