A Comprehensive Review of Liver Allograft Fibrosis and Steatosis: From Cause to Diagnosis

Abstract

Despite advances in posttransplant care, long-term outcomes for liver transplant recipients remain unchanged. Approximately 25% of recipients will advance to graft cirrhosis and require retransplantation. Graft fibrosis progresses in the context of de novo or recurrent disease. Recurrent hepatitis C virus infection was previously the most important cause of graft failure but is now curable in the majority of patients. However, with an increasing prevalence of obesity and diabetes and nonalcoholic fatty liver disease as the most rapidly increasing indication for liver transplantation, metabolic dysfunction-associated liver injury is anticipated to become an important cause of graft fibrosis alongside alloimmune hepatitis and alcoholic liver disease. To better understand the landscape of the graft fibrosis literature, we summarize the associated epidemiology, cause, potential mechanisms, diagnosis, and complications. We additionally highlight the need for better noninvasive methods to ameliorate the management of graft fibrosis. Some examples include leveraging the microbiome, genetic, and machine learning methods to address these limitations. Overall, graft fibrosis is routinely seen by transplant clinicians, but it requires a better understanding of its underlying biology and contributors that can help inform diagnostic and therapeutic practices.

FIGURE 1.

| Potential mechanisms and risk factors of liver allograft fibrosis. HCV, hepatitis C virus; HSC, hepatic stellate cell; NAFLD, nonalcoholic fatty liver disease; NASH, nonalcoholic steatohepatitis.

FIGURE 2.

| Current methods for diagnosing liver allograft fibrosis. ALT, alanine transaminase; AST, aspartate aminotransferase.