Liraglutide in patients with non-alcoholic fatty liver disease: a systematic review and meta-analysis of randomized controlled trials

Glucagon-Like Peptide-1: New Regulator in Lipid Metabolism

Glucagon-like peptide-1 (GLP-1) is a 30-amino acid peptide hormone that is mainly expressed in the intestine and hypothalamus. In recent years, basic and clinical studies have shown that GLP-1 is closely related to lipid metabolism, and it can participate in lipid metabolism by inhibiting fat synthesis, promoting fat differentiation, enhancing cholesterol metabolism, and promoting adipose browning. GLP-1 plays a key role in the occurrence and development of metabolic diseases such as obesity, nonalcoholic fatty liver disease, and atherosclerosis by regulating lipid metabolism. It is expected to become a new target for the treatment of metabolic disorders. The effects of GLP-1 and dual agonists on lipid metabolism also provide a more complete treatment plan for metabolic diseases. This article reviews the recent research progress of GLP-1 in lipid metabolism.

Efficacy and safety of semaglutide in non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease. The prevalence and disease burden of NAFLD are projected to exponentially increase resulting in significant healthcare expenditures and lower health-related quality of life. To date, there are no approved pharmacotherapies for NAFLD or non-alcoholic steatohepatitis (NASH). Semaglutide has glycemic and weight loss benefits that may be advantageous for patients with NAFLD.

AIM

To investigate the efficacy and safety of semaglutide in patients with NAFLD.

METHODS

MEDLINE, CENTRAL, and EMBASE were searched from inception to May 1, 2023, to identify eligible randomized controlled trials (RCTs). Meta-analysis was performed using random effects model expressing continuous outcomes as mean differences (MD) or standardized MDs (SMD), and dichotomous outcomes as odds ratios (OR) with 95% confidence intervals (CI). Statistical heterogeneity was assessed using the Cochran's Q test and I2 statistic.

RESULTS

Three RCTs involving 458 patients were included. Semaglutide increased the likelihood of NASH resolution (OR: 3.18, 95%CI: 1.70, 5.95; P < 0.001), improvement in steatosis (OR: 2.83, 95%CI: 1.19, 6.71; P = 0.03), lobular inflammation (OR: 1.81, 95%CI: 1.11, 2.96; P = 0.02), and hepatocellular ballooning (OR: 2.92, 95%CI: 1.83, 4.65; P < 0.001), but not fibrosis stage (OR: 0.71, 95%CI: 0.15, 3.41; P = 0.67). Radiologically, semaglutide reduced liver stiffness (SMD: -0.48, 95%CI: -0.86, -0.11; P = 0.01) and steatosis (MD: -4.96%, 95%CI: -9.92, 0.01; P = 0.05). It also reduced alanine aminotransferase (MD: -14.06 U/L, 95%CI: -22.06, -6.07; P < 0.001) and aspartate aminotransferase (MD: -11.44 U/L, 95%CI: -17.23, -5.65; P < 0.001). Semaglutide led to improved cardiometabolic outcomes, including decreased HgA1c (MD: -0.77%, 95%CI: -1.18, -0.37; P < 0.001) and weight loss (MD: -6.53 kg, 95%CI: -11.21, -1.85; P = 0.006), but increased the occurrence of GI-related side effects (OR: 3.72, 95%CI: 1.68, 8.23; P = 0.001). Overall risk of serious adverse events was similar compared to placebo (OR: 1.40, 95%CI: 0.75, 2.62; P < 0.29).

CONCLUSION

Semaglutide is effective in the treatment of NAFLD while maintaining a well-tolerated safety profile. Future studies are required to evaluate its effects on fibrosis regression and different phases of NAFLD.

Non-Alcoholic Fatty Liver Disease: Translating Disease Mechanisms into Therapeutics Using Animal Models

Nonalcoholic fatty liver disease (NAFLD) is a range of pathologies arising from fat accumulation in the liver in the absence of excess alcohol use or other causes of liver disease. Its complications include cirrhosis and liver failure, hepatocellular carcinoma, and eventual death. NAFLD is the most common cause of liver disease globally and is estimated to affect nearly one-third of individuals in the United States. Despite knowledge that the incidence and prevalence of NAFLD are increasing, the pathophysiology of the disease and its progression to cirrhosis remain insufficiently understood. The molecular pathogenesis of NAFLD involves insulin resistance, inflammation, oxidative stress, and endoplasmic reticulum stress. Better insight into these molecular pathways would allow for therapies that target specific stages of NAFLD. Preclinical animal models have aided in defining these mechanisms and have served as platforms for screening and testing of potential therapeutic approaches. In this review, we will discuss the cellular and molecular mechanisms thought to contribute to NAFLD, with a focus on the role of animal models in elucidating these mechanisms and in developing therapies.

The Role of GLP1-RAs in Direct Modulation of Lipid Metabolism in Hepatic Tissue as Determined Using In Vitro Models of NAFLD

Glucagon-like peptide 1 receptor agonists (GLP-1RAs) have been shown to improve glucose and lipid homeostasis, promote weight loss, and reduce cardiovascular risk factors. They are a promising therapeutic option for non-alcoholic fatty liver disease (NAFLD), the most common liver disease, associated with T2DM, obesity, and metabolic syndrome. GLP-1RAs have been approved for the treatment of T2DM and obesity, but not for NAFLD. Most recent clinical trials have suggested the importance of early pharmacologic intervention with GLP-1RAs in alleviating and limiting NAFLD, as well as highlighting the relative scarcity of in vitro studies on semaglutide, indicating the need for further research. However, extra-hepatic factors contribute to the GLP-1RA results of in vivo studies. Cell culture models of NAFLD can be helpful in eliminating extrahepatic effects on the alleviation of hepatic steatosis, modulation of lipid metabolism pathways, reduction of inflammation, and prevention of the progression of NAFLD to severe hepatic conditions. In this review article, we discuss the role of GLP-1 and GLP-1RA in the treatment of NAFLD using human hepatocyte models.

Utility of Human Relevant Preclinical Animal Models in Navigating NAFLD to MAFLD Paradigm

Fatty liver disease is an emerging contributor to disease burden worldwide. The past decades of work established the heterogeneous nature of non-alcoholic fatty liver disease (NAFLD) etiology and systemic contributions to the pathogenesis of the disease. This called for the proposal of a redefinition in 2020 to that of metabolic dysfunction-associated fatty liver disease (MAFLD) to better reflect the current understanding of the disease. To date, several clinical cohort studies comparing NAFLD and MAFLD hint at the relevancy of the new nomenclature in enriching for patients with more severe hepatic injury and extrahepatic comorbidities. However, the underlying systemic pathogenesis is still not fully understood. Preclinical animal models have been imperative in elucidating key biological mechanisms in various contexts, including intrahepatic disease progression, interorgan crosstalk and systemic dysregulation. Furthermore, they are integral in developing novel therapeutics against MAFLD. However, substantial contextual variabilities exist across different models due to the lack of standardization in several aspects. As such, it is crucial to understand the strengths and weaknesses of existing models to better align them to the human condition. In this review, we consolidate the implications arising from the change in nomenclature and summarize MAFLD pathogenesis. Subsequently, we provide an updated evaluation of existing MAFLD preclinical models in alignment with the new definitions and perspectives to improve their translational relevance.

Glucagon-Like Peptide-1 Receptor Agonists for Treatment of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis: An Updated Meta-Analysis of Randomized Controlled Trials

To assess the efficacy of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for treatment of nonalcoholic fatty liver disease (NAFLD) or steatohepatitis (NASH), we performed a systematic review and meta-analysis of randomized controlled trials (RCTs). Three large electronic databases were systematically searched (up to 15 December 2020) to identify placebo-controlled or active-controlled RCTs using different GLP-1 RAs. We included eleven placebo-controlled or active-controlled phase-2 RCTs (involving a total of 936 middle-aged individuals) that used liraglutide (n = 6 RCTs), exenatide (n = 3 RCTs), dulaglutide (n = 1 RCT) or semaglutide (n = 1 RCT) to specifically treat NAFLD or NASH, detected by liver biopsy (n = 2 RCTs) or imaging techniques (n = 9 RCTs). Compared to placebo or reference therapy, treatment with GLP-1 RAs for a median of 26 weeks was associated with significant reductions in the absolute percentage of liver fat content on magnetic resonance-based techniques (pooled weighted mean difference: −3.92%, 95% confidence intervals (CI) −6.27% to −1.56%) and serum liver enzyme levels, as well as with greater histological resolution of NASH without worsening of liver fibrosis (pooled random-effects odds ratio 4.06, 95% CI 2.52–6.55; for liraglutide and semaglutide only). In conclusion, treatment with GLP-1 RAs (mostly liraglutide and semaglutide) is a promising treatment option for NAFLD or NASH that warrants further investigation.

Glucagon-Like Peptide-1 Receptor Agonists for Treatment of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis: An Updated Meta-Analysis of Randomized Controlled Trials

To assess the efficacy of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for treatment of nonalcoholic fatty liver disease (NAFLD) or steatohepatitis (NASH), we performed a systematic review and meta-analysis of randomized controlled trials (RCTs). Three large electronic databases were systematically searched (up to 15 December 2020) to identify placebo-controlled or active-controlled RCTs using different GLP-1 RAs. We included eleven placebo-controlled or active-controlled phase-2 RCTs (involving a total of 936 middle-aged individuals) that used liraglutide (n = 6 RCTs), exenatide (n = 3 RCTs), dulaglutide (n = 1 RCT) or semaglutide (n = 1 RCT) to specifically treat NAFLD or NASH, detected by liver biopsy (n = 2 RCTs) or imaging techniques (n = 9 RCTs). Compared to placebo or reference therapy, treatment with GLP-1 RAs for a median of 26 weeks was associated with significant reductions in the absolute percentage of liver fat content on magnetic resonance-based techniques (pooled weighted mean difference: −3.92%, 95% confidence intervals (CI) −6.27% to −1.56%) and serum liver enzyme levels, as well as with greater histological resolution of NASH without worsening of liver fibrosis (pooled random-effects odds ratio 4.06, 95% CI 2.52–6.55; for liraglutide and semaglutide only). In conclusion, treatment with GLP-1 RAs (mostly liraglutide and semaglutide) is a promising treatment option for NAFLD or NASH that warrants further investigation.