Genetic and Life Style Risk Factors for Recurrent Non-alcoholic Fatty Liver Disease Following Liver Transplantation

Metabolic-Dysfunction-Associated Steatotic Liver Disease (MASLD) after Liver Transplantation: A Narrative Review of an Emerging Issue

The development of steatotic liver disease after liver transplant (LT) is widely described, and epidemiological data have revealed an increased incidence in recent times. Its evolution runs from simple steatosis to steatohepatitis and, in a small proportion of patients, to significant fibrosis and cirrhosis. Apparently, post-LT steatotic disease has no impact on the recipient's overall survival; however, a higher cardiovascular and malignancy burden has been reported. Many donors' and recipients' risk factors have been associated with this occurrence, although the recipient-related ones seem of greater impact. Particularly, pre- and post-LT metabolic alterations are strictly associated with steatotic graft disease, sharing common pathophysiologic mechanisms that converge on insulin resistance. Other relevant risk factors include genetic variants, sex, age, baseline liver diseases, and immunosuppressive drugs. Diagnostic evaluation relies on liver biopsy, although non-invasive methods are being increasingly used to detect and monitor both steatosis and fibrosis stages. Management requires a multifaceted approach focusing on lifestyle modifications, the optimization of immunosuppressive therapy, and the management of metabolic complications. This review aims to synthesize the current knowledge of post-LT steatotic liver disease, focusing on the recent definition of metabolic-dysfunction-associated steatotic liver disease (MASLD) and its metabolic and multisystemic concerns.

Current status of liver transplantation for non-B non-C liver cirrhosis and hepatocellular carcinoma

Recently, non-B non-C chronic liver diseases, including alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH), have markedly increased worldwide. Liver transplantation (LT) is an effective curative therapy for hepatocellular carcinoma (HCC) as well as decompensated liver cirrhosis. In Japan, where the source of liver grafts is strongly dependent on living donors, efforts have been made to unify the indications for eligibility of HCC patients for LT, leading to the development of 5-5-500 criteria. Along with the expansion of eligibility for LT, the current changing trends in underlying liver diseases of LT recipients, which are related to the rising tide of non-B non-C cirrhosis and HCC, are highlighting the importance of peri-transplant management of patients with various comorbidities. The post-LT prognosis of patients with ALD is significantly affected by de novo malignancies and metabolic syndrome-related complications as well as posttransplant alcohol relapse. NAFLD/NASH patients often suffer from obesity, type 2 diabetes mellitus, and other metabolic syndrome-related disorders, and nonneoplastic factors such as cardiovascular events and recurrence of NAFLD/NASH have a significant impact on post-LT outcomes. Patient management in the peri-transplant period as well as risk assessment for LT are key to improving post-LT outcomes in the era of a growing number of cases of LT for non-B non-C liver diseases.

Case report: NAFLD and maple syrup urine disease: Is there an interplay between branched-chain amino acids and fructose consumption?

BACKGROUND

The worldwide increase in pediatric overweight and obesity, in parallel with the global increase in the consumption of sucrose and fructose, is associated with non-alcoholic fatty liver disease (NAFLD). Elevated branched-chain amino acids (BCAAs) are a metabolic feature related to obesity and an early risk factor for insulin resistance and NAFLD. However, few studies have assessed metabolic risk factors and nutritional status in maple syrup urine disease (MSUD) patients under restricted BCAA and high carbohydrate diets.

METHODS AND RESULTS

Herein, we present a pilot report of a 17-year-old boy with classic MSUD with poor diet compliance and high fructose consumption, mainly during early adolescence. At that time, he was overweight and developed features of metabolic syndrome, including persistently elevated liver enzymes and hepatic steatosis. He underwent liver transplantation at the age of 13 years to prevent the risk of progressive cognitive impairment. Two months later, NAFLD relapsed in the graft, despite a better BCAA balance and weight loss. Nevertheless, 6 months after dietary restriction of fructose consumption, NAFLD had sustainably improved.

CONCLUSION

Childhood overweight and fructose overconsumption are wellestablished driving forces in the development of pediatric NAFLD. However, their role in the early onset and progression of NAFLD in the allograft remains to be established. Furthermore, it is not known whether the dysmetabolic state associated with elevated BCAAs may be contributory. Further studies are required with a cohort of MSUD subjects to validate our findings and to ascertain the possible interaction between a BCAA imbalance and dietary intake in the development of NAFLD.