De-novo nonalcoholic fatty liver disease at 5 years after liver transplantation: prevalence and predictive factors

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.

The impact of obesity on postoperative complications and short-term survival after liver transplantation

BACKGROUND AND AIMS

Obesity is considered a risk factor for perioperative complications, but its effect on patients undergoing liver transplantation (LT) remains unclear. This study was conducted to analyze the impact of obesity on early morbidity and mortality risk following LT.

METHODS

A multicenter study of outcomes in patients submitted to LT between 2009 and 2019 was conducted. Recipients were stratified into obese (BMI ≥ 30 kg/m2) and nonobese patients (BMI < 30 kg/m2). Early postoperative complications were compared and 30-day and 1-year patient and graft survival were assessed by Kaplan-Meier method. Primary graft nonfunction (PGNF) was defined as the presence of total bilirubin > 10 mg/dl, INR > 1.6 or ALT > 2000 U/l within the first week after LT.

RESULTS

A total of 1608 patients were included after applying exclusion criteria, nonobese (1149, 71.46%) and obese patients (459, 28.54%). There were no significant differences in age, sex, Model for End-stage Liver Disease, Charlson comorbidity score, ethnicity, waiting list time and ischemia time. There were significantly higher rates of vascular (17.58% vs 23.53%, P = 0.021) and biliary complications (27.68% vs 35.73%, P = 0.006) and PGNF (11.40% vs 12.20%, P = 0.021) in obese patients. There was a significantly increased risk for long-term graft failure; however, there was no significant difference in patient survival after LT.

CONCLUSION

Obese patients have significantly increased morbidity in terms of vascular and biliary complications and PGNF after LT. They have a higher risk for worse 1-year graft survival in comparison to controls.

Hepatic steatosis after liver transplantation: a systematic review and meta-analysis

NAFLD can occur after liver transplantation (LT), as recurrence or de novo hepatic steatosis (HS). We aimed to evaluate the literature on prevalence, risk factors, and prognosis of post-LT HS. Systematic review with meta-analysis through a search on: PUBMED, Scopus, and Web-of-Science, from inception until the September 30, 2021. Forty studies were included, representing 6979 patients. The post-LT HS prevalence was 39.76% (95% CI, 34.06-45.46), with a rising kinetics (11.06% increase per decade, p =0.04), and a geographical distribution (15.10% more prevalent in American continent compared with Europe and Asia). Recurrent HS was up to 5-fold more likely than de novo HS [OR: 5.38 (2.69-10.76)]. Metabolic disturbances were stronger risk factors in the post-LT recipient [obesity: OR: 4.62 (3.07-6.96); metabolic syndrome: OR: 3.26 (2.03-5.25)] as compared with pre-LT recipients, with the exception of diabetes mellitus, which doubled the risk at any set [pre-LT diabetes mellitus: OR: 2.06 (1.58-2.68); post-LT diabetes mellitus: OR: 2.12 (1.73-2.59)]. Donor factors were not the relevant risk factors for post-LT HS and the only immunosuppressive drug associated with increased risk was sirolimus [OR: 1.68 (1.07-2.64)]. The prevalence of post-LT steatohepatitis was 28.82% (19.62-38.03) and the strongest risk factor was pre-LT NAFLD. Limited outcomes data suggest that post-LT HS did not increase the risk for liver cirrhosis or mortality in these studies. Two out of 5 patients submitted to LT will develop post-LT HS, being recurrent HS more common than de novo HS. Diabetes mellitus and post-LT metabolic syndrome are the strongest risk factors for HS and baseline NAFLD for steatohepatitis. All transplanted patients should be enrolled in lifestyle interventions to prevent post-LT metabolic syndrome, and sirolimus should be avoided in high-risk patients.

Growing challenge of post-liver transplantation non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver disease, cirrhosis, and hepatocellular carcinoma worldwide, with an estimated prevalence of 25%. Post-liver transplantation (LT) recurrent or de novo hepatic steatosis is a common complication in recipients, irrespective of transplantation indication. Risk factors for graft steatosis mainly include obesity, immunosuppression, donor steatosis, and genetic factors. Liver transplant recipients are at high risk of developing insulin resistance, new-onset diabetes, and post-transplantation metabolic syndrome that is highly associated with immunosuppressive treatment. Post-LT NAFLD is often underdiagnosed due to the poor sensitivity of most routine imaging methods. The gold standard for the diagnosis of hepatic steatosis is liver biopsy, which is, however, limited to more complex cases due to its invasive nature. There is no approved pharmacotherapy in NAFLD. Lifestyle modification remains the cornerstone in NAFLD treatment. Other treatment strategies in post-LT NAFLD include lifestyle modifications, pharmacotherapy, bariatric surgery, and tailored immunosuppression. However, these approaches originate from recommendations in the general population, as there is scarce data regarding the safety and efficacy of current management strategies for NAFLD in liver transplant patients. Future prospective studies are required to achieve tailored treatment for these patients.

Extrahepatic organs in the development of non-alcoholic fatty liver disease in liver transplant patients

BACKGROUND AND OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is highly prevalent in patients who undergo liver transplantation (LT). Whereas there is huge data on NAFLD, little is known about NAFLD in LT. In this review, we aim to explore extrahepatic organs and their potential mechanisms in the development of NAFLD in LT patients and discuss current limitations in preclinical and clinical scenarios with suggestions for future study.

METHODS

The following keywords, such as NAFLD, NASH, liver transplant, therapy, pathogenesis and biomarkers, were set for literature retrieval. The articles which were published articles in English till 25th June 2020 in PubMed database were included, and there is no limit for the study design type.

KEY CONTENT AND FINDINGS

Following LT, there are significant shifts in the microbiota and farnesoid X receptor may be a potential therapeutic target for NAFLD in LT settings. The roles of probiotics and diet on NALFD remain inconclusive in LT background. Nevertheless, the adipokines and cytokines disorder and local insulin resistance of adipose tissue may contribute to NAFLD process. Bariatric surgeries are promising in controlling de novo and recurrent NAFLD with significant reduction in abdominal adipose tissue, despite the optimal timing is inconclusive in LT cases. Furthermore, circumstantial evidence indicates that miRNA-33a may function as a mediator bridging sarcopenia and NAFLD of post-LT. β-Hydroxy-β-Methyl-Butyrate treatment could improve muscle status in graft recipients and shows protective potential for NAFLD in LT settings.

CONCLUSIONS

Gut, adipose tissue and muscle are intricately intertwined in promoting NAFLD in LT cases. Further animal studies are needed to deepen our understanding of mechanisms in multi-organ crosstalk. High quality clinical trials are warrant for making guidelines and developing management strategies on NAFLD after LT.

De novo and recurrence of metabolic dysfunction-associated fatty liver disease after liver transplantation

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a new acronym adopted from the consensus of international experts. Given the increasing prevalence of MAFLD in pre-transplant settings, de novo and recurrent graft steatosis/MAFLD are common in post-transplant settings. The impact of graft steatosis on long-term outcomes is unclear. The current knowledge of incidence rate, risk factors, diagnosis, long-term outcomes, and management of graft steatosis (both de novo and recurrent) is discussed in this review.