Fibrotic Evolution Research Articles

MASSIVE ALVEOLAR THROMBIN ACTIVATION IN PSEUDOMONAS AERUGINOSA-INDUCED ACUTE LUNG INJURY

In acute lung injury (ALI), a coagulation/fibrinolysis imbalance leads to fibrin deposition, persistence of which contributes to fibrotic evolution. Our study evaluated the effects of early inhibition of coagulation in Pseudomonas aeruginosa (Pa)-induced ALI through the use of recombinant human antithrombin (rhAT). The study was conducted in vivo on a murine model of Pa-induced ALI. Intravenous rhAT was administered simultaneously with intratracheal Pa. Four experimental groups were compared: CTR, intratracheal saline (0.5 mL/kg)/intravenous saline (1 mL); PNP, intratracheal Pa (0.5 mL/kg of 2 x 10(9) cfu)/intravenous saline; AT, intratracheal saline/intravenous rhAT (500 IU/kg); ATPNP, intratracheal Pa/intravenous rhAT. Epithelial and endothelial permeabilities were evaluated with radiolabeled albumin flux across the alveolar barrier (125I- and 131I-labeled albumin). Thrombin-antithrombin (TAT) complexes levels were used as markers of coagulation activation in blood samples and in BAL fluid. Epithelial and endothelial protein permeability were increased in Pa-induced ALI versus control. Intravenous rhAT administration led to further permeability disorders. Administration of rhAT in Pa ALI led to a rise in TAT complexes in ATPNP blood serum and BAL fluids compared with the other groups. In Pa-induced ALI the administration intravenous rhAT leads to major histologic damage, alveolar capillary barrier injury, and permeability increase. Such effects of the inhibition of thrombin activation by rhAT lead to the hypothesis of a probable beneficial role of early coagulation activation in ALI as a factor limiting both the extent of injury and permeability disorders. Our study suggests that inhibition of this initial procoagulative imbalance is potentially dangerous.

The first intron of the human osteopontin gene contains a C/EBP-beta-responsive enhancer.

The osteopontin (OPN) protein is found expressed at high level in several processes including fibrotic evolution of organ injuries, tumorigenesis, and immune response. The molecular mechanisms that underly overexpression, especially at the transcriptional level, have been only partially clarified. Therefore, this study was undertaken in search for additional DNA elements in the regulatory regions of the OPN gene and cognate transcription factors. Our results on the region upstream of the transcription start site confirmed that essential elements are located within the first 100 bp. Analysis of the sequence that includes the first untranslated exon and first intron revealed that it could enhance the promoter activity. Experiments of transfection of constructs containing different fragments of this sequence showed that most of the enhancer activity was confined in the terminal 30-bp tract of the first intron, although it was not functioning in a myofibroblast cell line. DNA/protein binding assays and cotransfection experiments showed that the C/EBP-beta transcription factor was able to bind a recognition sequence in this 30-bp segment. We found a bi-allelic sequence polymorphism at +245 in the first intron, which did not show a significant functional effect, but is a useful tool for future association studies.

Expression of collagens type I and IV, osteonectin and transforming growth factor beta-1 (TGFβ1) in biliary atresia and paucity of intrahepatic bile ducts during infancy

Background/Aims: Biliary atresia and paucity of intrahepatic bile ducts are the main causes of neonatal cholestasis leading to hepatic fibrosis. Fibrotic evolution is slow in paucity of bile ducts as compared to the rapid progression to biliary cirrhosis in biliary atresia when cholestasis persists despite hepatoportoenterostomy. Our aim was to compare the expression of collagens type I and IV,α-smooth muscle actin, osteonectin and transforming growth factor β1 in biliary atresia and paucity of bile ducts. Methods: Liver biopsies were obtained in 12 children with biliary atresia and in five with paucity of bile ducts. Collagens type I and IV, α-smooth muscle actin were detected with immunostaining. Collagens type I and IV, osteonectin and transforming growth factor β1 mRNAs were detected by in situ hybridization. Results: Expression of mRNA and proteins was roughly parallel. In ductular proliferation areas of biliary atresia: (1) the expression of collagens type I and IV and osteonectin was increased, and was localized to periductular myofibroblasts; (2) transforming growth factor β1 was expressed around biliary ductules, probably in inflammatory cells, and also in biliary cells. Osteonectin expression was also increased in the lobules. In paucity of bile ducts, there was no overexpression of collagens type I and IV and transforming growth factor β1, except in the only child with marked fibrosis. However, osteonectin expression was enhanced at the periphery of the lobules, even when fibrosis was mild or absent. Conclusions: These findings suggest that in biliary atresia ductular proliferation areas are the site of a marked production of extracellular matrix proteins in periductular myofibroblasts, probably secondary to transforming growth factor β1 production by inflammatory cells and by biliary cells. The weak expression of transforming growth factor β1 could explain the slow progression of fibrosis in paucity of bile ducts.

EXPRESSION OF COLLAGEN TYPE I AND IV, OSTEONECTIN AND TRANSFORMING GROWTH FACTOR BETA-1 (TGFβ1) IN BILIARY ATRESIA AND PAUCITY OF INTRAHEPATIC BILE DUCTS

169 Biliary atresia (BA) and Paucity of Interlobular Bile Ducts (PIBD) are the two main causes of neonatal cholestasis leading to hepatic fibrosis. Fibrotic evolution is slow in PIBD as compared to the rapid progression to biliary cirrhosis in BA when cholestasis persists despite hepatoportoenterostomy. Aim of the study: examine the expression of collagens type I and IV, two components of the extracellular matrix; osteonectin, a protein involved in matrix remodeling; smooth muscle α-actin, a marker of myofibroblasts; and TGFβ1, one of the main profibrogenic factors, in BA and PIBD. Methods: liver samples were obtained during the Kasai procedure in 12 BA (age: 27 to 84 days) and during percutaneous liver biopsy, required for histological diagnosis, in 5 PIBD (age: 64 to 106 days). Collagens type I(Co1) and type IV (Co4), and smooth muscle α-actin were detected with immunostaining. Co1 and Co4, osteonectin (ON) and TGFβ1 mRNAs were detected by in situ hybridization. Results: Expression of mRNA and proteins was parallel. In ductular proliferation areas of BA, the expression of Co1, Co4 and ON was increased, and was localized to periductular myofibroblasts. TGFβ1 was expressed in biliary cells. In the lobules of BA, ON expression was increased. No expression of Co1, Co4 and TGFβ1 was found in PIBD, except in the single child with a marked fibrosis. ON expression was enhanced at the periphery of the lobules, even when fibrosis was mild or absent in PIBD. Conclusion: In BA, ductular proliferation areas are the site of a marked production of extracellular matrix proteins in periductular myofibroblasts, probably secondary to TGFβ1 production in epithelial biliary cells. The weak expression of TGFβ1 could explain the slow evolutivity of fibrosis in PIBD.

Pneumopathie interstitielle aux inhibiteurs de l'enzyme de conversion de l'angiotensine. À propos d'un cas

Cough and bronchial hyperreactivity are the known respiratory side effects of angiotensin converting enzyme inhibitors (ACI). Eosinophilic lung infiltration and lymphocytic alveolitis have recently been described. We report a case of interstitial eosinophilic pneumopathy with fibrotic evolution that occured during ACI treatment.