Effects of RhoA, Rac1 and Cdc42 on liver fibrosis in patients with biliary atresia

Abstract

Objective To explore the expressions of RhoA, Rac1 and Cdc42 in liver tissues of children with biliary atresia (BA). Methods Samples were collected from patients with congenital biliary dilatation (CBD group, n=15), BA (BA group, n=15) and BA children undergoing liver transplantation (LT) due to liver failure (LT group, n=10). Hematoxylin & eosin (HE) staining was used for observing the degrees of liver fibrosis; the expressions of RhoA, Rac1 and Cdc42 in liver tissues were detected by immunohistochemical staining; Quantitative real-time polymerase chain reaction (qRT-PCR) was used for testing the mRNA expression levels of RhoA, Rac1 and Cdc42. Results (1) HE staining: less fiber cell hyperplasia in CBD group; Widened portal tracts, portal fibrosis and bridging fibrosis and pseudo-lobules were seen in BA group; The widened portal area was obvious, portal fibrosis was heavier and bridging fibrosis generally formed, pseudo-lobular was remarkable in LT group. (2) Immunohistochemistry: the expressions of RhoA, Rac1 and Cdc42 were weakly positive in CBD group. The positive expression of RhoA, Rac1 and Cdc42 protein in cytoplasm of hepatocytes and bile duct epithelial cells in BA and LT groups. Semi-quantitative analysis: the results of RhoA, Rac1 and Cdc42 protein among three groups were: RhoA (0.1419±0.0683, 0.2295±0.0623, 0.2203±0.0476), Rac1 (0.1587±0.0072, 0.1970±0.0242, 0.1993±0.0270) and Cdc42 (0.887±0.0270, 0.1397±0.0360, 0.1519±0.0168) indicating significant differences (P 0.05); (3) qRT-PCR: the mRNA expression levels of RhoA, Rac1 and Cdc42 in three groups were RhoA [0.3350(0.2525-0.6350), 1.5200(1.4375-2.1700)& 1.9350(1.7950-2.3925)], Rac1[0.2800(0.1450-0.3025), 0.8200(0.7275-0.9300)& 0.8000(0.7725-0.9825)], Cdc42 [0.5950(0.4375-0.7125), 1.8950(1.8675-2.1925)& 1.9900(1.8675-2.2050)]. Significant differences existed among three groups(P<0.017). Furthermore, the mRNA expression levels of RhoA, Rac1 and Cdc42 were higher in BA and LT groups than those of CBD group (P<0.017). Conclusions The expressions of RhoA, Rac1 and Cdc42 are up-regulated in BA patients. It suggests that RhoA, Rac1 and Cdc42 may be involved in the process of liver fibrosis. Key words: Biliary atresia; RhoA GTP-binding protein; Rac1 GTP-binding protein; Cdc42 GTP-binding protein; TGF-β1; Liver fibrosis