Replicative Senescence of Biliary Epithelial Cells Precedes Bile Duct Loss in Chronic Liver Allograft Rejection

Abstract

Early chronic liver allograft rejection (CR) is characterized by distinctive cytological changes in biliary epithelial cells (BECs) that resemble cellular senescence, in vitro, and precede bile duct loss. If patients suffering from early CR are treated aggressively, the clinical and histopathological manifestations of CR can be completely reversed and bile duct loss can be prevented. We first tested whether the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR, and whether treatment reversed the expression. The percentage of p21+ BECs and the number of p21+ BECs per portal tract is significantly increased in early CR (26 +/- 17% and 3.6 +/- 3.1) compared to BECs in normal liver allograft biopsies or those with nonspecific changes (1 +/- 1% and 0.1 +/- 0.3; P: < 0.0001 and P: < 0.02), chronic hepatitis C (2 +/- 3% and 0.7 +/- 1; P: < 0.0001 and P: < 0.04) or obstructive cholangiopathy (7 +/- 7% and 0.7 +/- 0.6; P: < 0.006 and P: = 0.04). Successful treatment of early CR is associated with a decrease in the percentage of p21+ BECs and the number of p21+ BECs per portal tract. In vitro, nuclear p21(WAF1/Cip1) expression is increased in large and multinucleated BECs, and is induced by transforming growth factor (TGF)-beta. TGF-beta1 also increases expression of TGF-beta receptor II, causes phosphorylation of SMAD-2 and nuclear translocation of p21(WAF1/Cip1), which inhibits BEC growth. Because conversion from cyclosporine to tacrolimus is an effective treatment for early CR, we next tested whether these two immunosuppressive drugs directly influenced BEC growth in vitro. The results show that cyclosporine, but not tacrolimus, stimulates BEC TGF-beta1 production, which in turn, causes BEC mito-inhibition and up-regulation of nuclear p21(WAF1/Cip1). In conclusion, expression of the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR and decreases with successful recovery. Replicative senescence accounts for the characteristic BEC cytological alterations used for the diagnosis of early CR and lack of a proliferative response to injury. The ability of cyclosporine to inhibit the growth of damaged BECs likely accounts for the relative duct sparing properties of tacrolimus.

Role of Replicative Senescence in the Progression of Fibrosis in Hepatitis C Virus (Hcv) Recurrence After Liver Transplantation

“…It is noteworthy that several experimental and human studies have demonstrated the involvement of RS in specific pathologic conditions, including those associated with transplantation (15,19). For our purpose, we used a histochemical procedure, detecting senescent cells according to the activity of A-␤-Gal.…”

“…Likewise, Lunz et al (15) showed that RS of biliary epithelial cells, through the increased expression of p21WAF/Cip1, could contribute to the bile-duct loss in chronic rejection of liver grafts. RS, in which the cell is still metabolically active but cannot further proliferate, is associated with a major shortening of telomeres, the extreme ends of each chromosome (16,17).…”

NIH Consensus Development Project on Criteria for Clinical Trials in Chronic Graft-versus-Host Disease: II. The 2014 Pathology Working Group Report

“…These include both diastase-sensitive polyglucosan-like ground-glass cytoplasmic inclusions [35, 36] and PAS-positive diastase-resistant pseudo-Lafora bodies thought to represent an unusual form of degenerative organelles and glycogen [37, 38]. Data are insufficient to determine whether IHC staining for replicative senescence by p21 [39], determination of the Th17/T regulatory cell ratio [40], or staining for C4d provides additional information above and beyond the usual histological evaluation [41]. …”

Molecular mechanisms of cholangiopathy in primary biliary cirrhosis

“…40,48,49 Enhanced biliary apoptosis in PBC TUNEL-positive apoptotic cells are frequently found on biliary epithelial cells, particularly more cholangitic bile ducts in PBC, but very a few in control livers (Fig.4). These biliary epithelial cells showing cholangitis aberrantly express Fas antigen in their luminal surface and/or basolateral membrane accompanying the infiltration of Fas ligand-expressing inflammatory cells.…”