Effect of Immunosuppressive Agents on Hepatocyte Apoptosis Post-Liver Transplantation

• Published in: PloS one Vol. 10; no. 9; p. e0138522
• Main Authors: Lim, Eu Jin, Chin, Ruth, Nachbur, Ueli, Silke, John, Jia, Zhiyuan, Angus, Peter W, Torresi, Joseph
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21-09-2015; Public Library of Science (PLoS)
• Subjects: Adult; Aged; Aged, 80 and over; Allografts; Animals; Antineoplastic Combined Chemotherapy Protocols - pharmacology; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Apoptosis; Apoptosis - drug effects; Caspase; Caspase 3 - metabolism; Caspase-3; Cell death; Cell Survival - drug effects; Cyclosporine - pharmacology; Cyclosporine - urine; Cyclosporins; Dosage and administration; Drug dosages; Drug Therapy, Combination - methods; Experiments; Female; Fibrosis; Fluorouracil - pharmacology; Fluorouracil - therapeutic use; Graft rejection; Growth factors; Hepatocytes; Hepatocytes - drug effects; Hepatocytes - metabolism; Hospitals; Humans; Immunohistochemistry; Immunosuppressive agents; Immunosuppressive Agents - pharmacology; Immunosuppressive Agents - therapeutic use; Infections; Inflammation; Inflammatory response; Laboratories; Life assessment; Liver - drug effects; Liver - metabolism; Liver Cirrhosis - drug therapy; Liver Cirrhosis - metabolism; Liver diseases; Liver transplantation; Liver Transplantation - adverse effects; Liver Transplantation - methods; Liver transplants; Male; Medicine; Mice; Mice, Inbred C57BL; Middle Aged; Mitomycin - pharmacology; Mitomycin - therapeutic use; Mortality; Patients; Rapamycin; Rodents; Semustine - pharmacology; Semustine - therapeutic use; Sirolimus - pharmacology; Sirolimus - therapeutic use; Tacrolimus; Tacrolimus - pharmacology; Tacrolimus - therapeutic use; Transplants & implants; United States; Australia
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0138522

Immunosuppressants are used ubiquitously post-liver transplantation to prevent allograft rejection. However their effects on hepatocytes are unknown. Experimental data from non-liver cells indicate that immunosuppressants may promote cell death thereby driving an inflammatory response that promotes fibrosis and raises concerns that a similar effect may occur within the liver. We evaluated apoptosis within the liver tissue of post-liver transplant patients and correlated these findings with in vitro experiments investigating the effects of immunosuppressants on apoptosis in primary hepatocytes.
Hepatocyte apoptosis was assessed using immunohistochemistry for M30 CytoDEATH and cleaved PARP in human liver tissue. Primary mouse hepatocytes were treated with various combinations of cyclosporine, tacrolimus, sirolimus, or MMF. Cell viability and apoptosis were evaluated using crystal violet assays and Western immunoblots probed for cleaved PARP and cleaved caspase 3.
Post-liver transplant patients had a 4.9-fold and 1.7-fold increase in M30 CytoDEATH and cleaved PARP compared to normal subjects. Cyclosporine and tacrolimus at therapeutic concentrations did not affect hepatocyte apoptosis, however when they were combined with MMF, cell death was significantly enhanced. Cell viability was reduced by 46% and 41%, cleaved PARP was increased 2.6-fold and 2.2-fold, and cleaved caspase 3 increased 2.2-fold and 1.8-fold following treatment with Cyclosporine/MMF and Tacrolimus/MMF respectively. By contrast, the sirolimus/MMF combination did not significantly reduce hepatocyte viability or promote apoptosis.
Commonly used immunosuppressive drug regimens employed after liver transplantation enhance hepatocyte cell death and may thus contribute to the increased liver fibrosis that occurs in a proportion of liver transplant recipients.