Sitagliptin in patients with non-alcoholic steatohepatitis: A randomized, placebo-controlled trial

Optimized strategy among diet, exercise, and pharmacological interventions for nonalcoholic fatty liver disease: A network meta-analysis of randomized controlled trials

BACKGROUND

Emerging treatment methods, including exercise, diet, and drugs, for nonalcoholic fatty liver disease have been proposed. However, the differences in their efficacy have not been determined. We aimed to compare the effects of these treatments excluding surgery via a systematic review and network meta-analysis of randomized controlled trials.

DATA SOURCE

The data sources included PubMed, Embase, Web of Science and Cochrane up to February 1st, 2023. The endpoints consisted of body mass index (BMI), serum markers of metabolism and liver injury markers, liver fat content, and stiffness.

RESULTS

A total of 174 studies with 10,183 patients were included in this meta-analysis. In terms of improving BMI, Pan-agonist of peroxisome proliferator-activated receptors (PPAR) is the best treatment with the highest SUCRA (surface under the cumulative ranking) of 84.8% (mean = -3.40, 95% CI -5.55, -1.24) by the comparative effectiveness ranking. GLP-1 (glucagon-like peptide-1) has the best effect in improving the liver fat content based on the MRI-PDFF, steatosis score (SUCRA 99.7%, mean = -2.19, 95% CI -2.90, -1.48) and ballooning score (SUCRA 61.2%, mean = -0.82, 95% CI -4.46, 2.83).

CONCLUSIONS

Pan-agonist of PPAR was the most efficacious regimen in lowering BMIs, whereas GLP-1R agonists achieved the highest efficacy of steatosis improvement in this network meta-analysis.

Hepatic glucose metabolism in the steatotic liver

The liver is central in regulating glucose homeostasis, being the major contributor to endogenous glucose production and the greatest reserve of glucose as glycogen. It is both a target and regulator of the action of glucoregulatory hormones. Hepatic metabolic functions are altered in and contribute to the highly prevalent steatotic liver disease (SLD), including metabolic dysfunction-associated SLD (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH). In this Review, we describe the dysregulation of hepatic glucose metabolism in MASLD and MASH and associated metabolic comorbidities, and how advances in techniques and models for the assessment of hepatic glucose fluxes in vivo have led to the identification of the mechanisms related to the alterations in glucose metabolism in MASLD and comorbidities. These fluxes can ultimately increase hepatic glucose production concomitantly with fat accumulation and alterations in the secretion and action of glucoregulatory hormones. No pharmacological treatment has yet been approved for MASLD or MASH, but some antihyperglycaemic drugs approved for treating type 2 diabetes have shown positive effects on hepatic glucose metabolism and hepatosteatosis. A deep understanding of how MASLD affects glucose metabolic fluxes and glucoregulatory hormones might assist in the early identification of at-risk individuals and the use or development of targeted therapies.

Comparative Efficacy of Drug Interventions on NAFLD Over 24 Weeks: A Traditional and Network Meta-Analysis of Randomized Controlled Trials

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD), currently referred to as metabolic dysfunction-associated steatotic liver disease (MASLD), affects approximately 38% of the world's population, yet no pharmacological therapies have been approved for treatment. We conducted a traditional and network meta-analysis to comprehensively assess the effectiveness of drug regimens on NAFLD, and continued to use the old terminology for consistency.

METHODS

Randomized, placebo-controlled trials (RCTs) investigating drug therapy in an adult population diagnosed with NAFLD with or without diabetes mellitus were included. We assessed the quality of RCTs via the Risk of Bias 2 (ROB 2) tool. When I2 < 50%, we chose a random-effects model, otherwise a fixed-effects model was selected. A random effects model was applied in the network meta-analysis. The odds ratio (OR), weighted mean difference (WMD) or standard mean difference (SMD) with 95% confidence interval (CI) were used for outcome evaluation. The primary endpoint was the resolution of nonalcoholic steatohepatitis (NASH) without the worsening of liver fibrosis. Other endpoints included histological findings and metabolic changes. The PROSPERO Registration ID was CRD42023404309.

RESULTS

Thiazolidinediones (TZDs), vitamin E plus pioglitazone, glucagon-like peptide-1 (GLP-1) receptor agonists and fibroblast growth factor-21 (FGF-21) analogue had a higher surface under the cumulative ranking curve (SUCRA = 76.6, 73.0, 72.0 and 71.6) regarding NASH resolution. Improvement of liver fibrosis stage (≥ 1) was observed with obeticholic acid 25 mg/day (OR 2.01, 95% CI 1.35-2.98), lanifibranor 1200 mg/day (OR 2.39, 95% CI 1.19-4.82) and silymarin (OR 4.54, 95% CI 1.18-17.43) in traditional meta-analysis.

CONCLUSIONS

The results of the comprehensive analysis suggested hypoglycemic drug therapy as an effective intervention for NAFLD, with or without diabetes mellitus. A prioritized selection of TZDs, vitamin E plus pioglitazone, GLP-1 receptor agonists and FGF-21 analogue may be considered for NASH resolution. Obeticholic acid, lanifibranor and silymarin could be considered for the improvement of liver fibrosis. Each medication was relatively safe compared with placebo.

The role of anti-diabetic drugs in NAFLD. Have we found the Holy Grail? A narrative review

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) has become a leading cause of liver disease, affecting 30% of the global population. NAFLD prevalence is particularly high in obese individuals and patients with type 2 diabetes mellitus (T2DM). NAFLD ranges from simple fat deposition in the liver to necroinflammation and fibrosis (non-alcoholic steatohepatitis (NASH)), NASH-cirrhosis, and/or hepatocellular carcinoma. Insulin resistance plays a key role in NAFLD pathogenesis, alongside dysregulation of adipocytes, mitochondrial dysfunction, genetic factors, and changes in gut microbiota. Since insulin resistance is also a major predisposing factor of T2DM, the administration of anti-diabetic drugs for the management of NAFLD seems reasonable.

METHODS

In this review we provide the NAFLD-associated mechanisms of action of some of the most widely used anti-diabetic drugs, namely metformin, pioglitazone, sodium-glucose transport protein-2 inhibitors (SGLT2i), glucagon-like peptide 1 receptor analogs (GLP1 RAs), and dipeptyl-peptidase-4 inhibitors (DPP4i) and present available data regarding their use in patients with NAFLD, with and without T2DM.

RESULTS

Both metformin and DPP4i have shown rather contradictory results, while pioglitazone seems to benefit patients with NASH and is thus the only drug approved for NASH with concomitant significant liver fibrosis by all major liver societies. On the other hand, SGLT2i and GLP1 RAs seem to be beneficiary in patients with NAFLD, showing both remarkable results, with SGLT2i proving to be more efficient in the only head-to-head study so far.

CONCLUSION

In patients with NAFLD and diabetes, pioglitazone, GLP1 RAs, and SGLT2i seem to be logical treatment options. Larger studies are needed before these drugs can be recommended for non-diabetic individuals.

Gemigliptin, a DPP4 inhibitor, ameliorates nonalcoholic steatohepatitis through AMP-activated protein kinase-independent and ULK1-mediated autophagy

OBJECTIVE

Abnormal autophagic function and activated inflammasomes are typical features in the liver of patients with non-alcoholic steatohepatitis (NASH). Here, we explored whether gemigliptin, a dipeptidyl peptidase 4 (DPP4) inhibitor for treatment of type 2 diabetes, can induce autophagy and regulate inflammasome activation as a potential NASH treatment independent of its anti-diabetic effect.

METHODS

Expression analysis was performed using human liver samples obtained from 18 subjects who underwent hepatectomy. We explored the function and mechanism of gemigliptin using a methionine- and choline-deficient diet (MCD)-induced NASH mouse model and HepG2 cells cultured in MCD-mimicking medium.

RESULTS

Autophagy was suppressed by marked decreases in the expression of ULK1 and LC3II/LC3I ratio in human NAFLD/NASH patients, a NASH mouse model, and HepG2 cells cultured with MCD-mimicking media. Surprisingly, we found that the expression of p-AMPK decreased in liver tissues from patients with steatosis but was restored in NASH patients. The expression of p-AMPK in the NASH mouse model was similar to that of the control group. Hence, these results indicate that autophagy was reduced in NASH via an AMPK-independent pathway. However, gemigliptin treatment attenuated lipid accumulation, inflammation, and fibrosis in the liver of MCD diet-fed mice with restoration of ULK1 expression and autophagy induction. In vitro, gemigliptin alleviated inflammasome activation through induction of ULK1-dependent autophagy. Furthermore, gemigliptin treatment upregulated ULK1 expression and activated AMPK even after siRNA-mediated knockdown of AMPKα1/2 and ULK1, respectively.

CONCLUSIONS

Collectively, these results suggest that gemigliptin ameliorated NASH via AMPK-independent, ULK1-mediated effects on autophagy.

Comparative efficacy of glucose-lowering drugs on liver steatosis as assessed by means of magnetic resonance imaging in patients with type 2 diabetes mellitus: systematic review and network meta-analysis

PURPOSE

To assess the comparative efficacy of glucose-lowering drugs on liver steatosis as assessed by means of magnetic resonance imaging (MRI) in patients with T2D.

METHODS

We searched several databases and grey literature sources. Eligible trials had at least 12 weeks of intervention, included patients with T2D, and assessed the efficacy of glucose-lowering drugs as monotherapies. The primary outcome of interest was absolute reduction in liver fat content (LFC), assessed by means of MRI. Secondary efficacy outcomes were reduction in visceral and subcutaneous adipose tissue. We performed random effects frequentist network meta-analyses to estimate mean differences (MDs) with 95% confidence intervals (CIs). We ranked treatments based on P-scores.

RESULTS

We included 29 trials with 1906 patients. Sodium-glucose cotransporter-2 (SGLT-2) inhibitors (P-score 0.84) and glucagon-like peptide-1 receptor agonists (GLP-1 RAs) (0.71) were the most efficacious in terms of liver fat content reduction. Among individual agents, empagliflozin was the most efficacious (0.86) and superior to pioglitazone (MD -5.7, 95% CI -11.2 to -0.3) (very low confidence). GLP-1 RAs had also the most favorable effects on visceral and subcutaneous adipose tissue.

CONCLUSIONS

GLP-1 RAs and SGLT-2 inhibitors seem to be the most efficacious glucose-lowering drugs for liver steatosis in patients with T2D. Assessment of their efficacy on NAFLD in patients irrespective of presence of T2D is encouraged.

Why do some glucose-lowering agents improve non-alcoholic fatty liver disease whereas others do not? A narrative review in search of a unifying hypothesis

Non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2D) are metabolic disorders connected by common pathophysiological mechanisms. Since insulin resistance (IR) and metabolic alterations are common to both conditions, almost all glucose-lowering agents which improve IR have also been studied in patients with NAFLD. Some have shown great efficacy, others none. Thus, the mechanisms behind the efficacy of these drugs in improving hepatic steatosis, steatohepatitis, and eventually fibrosis remain controversial. Glycaemic control improves T2D, but probably has limited effects on NAFLD, as all glucose-lowering agents ameliorate glucose control but only a few improve NAFLD features. In contrast, drugs that either improve adipose tissue function, reduce lipid ingestion, or increase lipid oxidation are particularly effective in NAFLD. We therefore hypothesise that improved free fatty acid metabolism may be the unifying mechanism behind the efficacy of some glucose-lowering agents on NAFLD and may represent the key to NAFLD treatment.

Pharmacotherapies of NAFLD: updated opportunities based on metabolic intervention

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease that is becoming increasingly prevalent, and it ranges from simple steatosis to cirrhosis. However, there is still a lack of pharmacotherapeutic strategies approved by the Food and Drug Administration, which results in a higher risk of death related to carcinoma and cardiovascular complications. Of note, it is well established that the pathogenesis of NAFLD is tightly associated with whole metabolic dysfunction. Thus, targeting interconnected metabolic conditions could present promising benefits to NAFLD, according to a number of clinical studies. Here, we summarize the metabolic characteristics of the development of NAFLD, including glucose metabolism, lipid metabolism and intestinal metabolism, and provide insight into pharmacological targets. In addition, we present updates on the progresses in the development of pharmacotherapeutic strategies based on metabolic intervention globally, which could lead to new opportunities for NAFLD drug development.

Statins on nonalcoholic fatty liver disease: A systematic review and meta-analysis of 14 RCTs

BACKGROUND

The prevalence of nonalcoholic fatty liver disease (NAFLD) is rising rapidly in the world. Our aim is to investigate the efficacy and safety of statins in the treatment of NAFLD.

METHODS

This study was conducted by searching The National Library of Medicine, Cochrane Library, China National Knowledge Infrastructure, Web of Science, and Wanfang Data Knowledge Service Platform databases. Literature data are expressed as mean difference (MD) and 95% confidence intervals (CIs) or relative risk and 95% CI. For I2 > 50% trials, random effect model is used for statistical analysis, otherwise fixed effect model is used.

RESULTS

Fourteen studies are selected for this meta-analysis, which includes totally 534 patients in the treatment group and 527 patients in the control group. As a result, 5 studies show that the total effective rate of the treatment group is 17% higher than that of the control group (Z = 2.11, relative risk = 1.17, 95% CI: [1.01-1.35]). Twelve studies show that alanine aminotransferase levels of the experimental group are lower than that of the control group (Z = 2.63, P = .009, MD = -5.53, 95% CI: [-9.64 to -1.41]). Eleven studies show that aspartate transaminase levels of the experimental group are lower than that of the control group (Z = 2.01, P = .04, MD = -3.43, 95% CI: [-6.77 to -0.08]). Six studies show that alkaline phosphatase levels of the experimental group are lower than that of the control group (Z = 0.79, P = .43, MD = -3.46, 95% CI: [-12.08 to 5.16]). Eight studies show that gamma-glutamyl transpeptidase levels of the experimental group are lower than that of the control group (Z = 2.04, P = .04, MD = -4.05, 95% CI: [-7.96 to -0.15]). Thirteen studies show that triglyceride levels of the experimental group are lower than that of the control group (Z = 4.15, P < .0001, MD = -0.94, 95% CI: [-1.39 to -0.50]). Eleven studies show that the total cholesterol levels of the experimental group are lower than that of the control group (Z = 5.42, P < .00001, MD = -1.51, 95% CI: [-2.05 to -0.96]). Seven studies show that low-density lipoprotein-cholesterol levels of the experimental group are lower than that of the control group (Z = 5.00, P < .00001, MD = -0.85, 95% CI: [-1.18 to -0.52]).

CONCLUSION

Statins can significantly reduce liver biochemical indicators in patients with NAFLD.

New anti-diabetic agents for the treatment of non-alcoholic fatty liver disease: a systematic review and network meta-analysis of randomized controlled trials

Objectives

This network meta-analysis aims to compare the efficacy and safety of new anti-diabetic medications for the treatment of non-alcoholic fatty liver disease (NAFLD).

Materials and methods

PubMed and Scopus were searched from inception to 27th March 2022 to identify all randomized controlled trials (RCTs) in NAFLD patients. Outcomes included reductions in intrahepatic steatosis (IHS) and liver enzyme levels. The efficacy and safety of DPP-4 inhibitors, GLP-1 agonists, SGLT-2 inhibitors, and other therapies were indirectly compared using a NMA approach. Unstandardized mean difference (USMD) with 95% confidence intervals (CI) were calculated.

Results

2,252 patients from 31 RCTs were included. "Add-on" GLP-1 agonists with standard of care (SoC) treatment showed significantly reduced IHS compared to SoC alone [USMD (95%CI) -3.93% (-6.54%, -1.33%)]. Surface under the cumulative ranking curve (SUCRA) identified GLP-1 receptor agonists with the highest probability to reduce IHS (SUCRA 88.5%), followed by DPP-4 inhibitors (SUCRA 69.6%) and pioglitazone (SUCRA 62.2%). "Add-on" GLP-1 receptor agonists were also the most effective treatment for reducing liver enzyme levels; AST [USMD of -5.04 (-8.46, -1.62)], ALT [USMD of -9.84 (-16.84, -2.85)] and GGT [USMD of -15.53 (-22.09, -8.97)] compared to SoC alone. However, GLP-1 agonists were most likely to be associated with an adverse event compared to other interventions.

Conclusion

GLP-1 agonists may represent the most promising anti-diabetic treatment to reduce hepatic steatosis and liver enzyme activity in T2DM and NAFLD patients. Nevertheless, longer-term studies are required to determine whether this delays progression of liver cirrhosis in patients with NAFLD and T2DM.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021259336.1.

Effectiveness of One-Year Pemafibrate Therapy on Non-Alcoholic Fatty Liver Disease Refractory to Long-Term Sodium Glucose Cotransporter-2 Inhibitor Therapy: A Pilot Study

Background: Both pemafibrate and sodium glucose cotransporter-2 (SGLT2) inhibitor can decrease serum transaminase levels in patients with non-alcoholic fatty liver disease (NAFLD) complicated with dyslipidemia and type 2 diabetes mellitus (T2DM), respectively. However, the effectiveness of combined therapy has been rarely reported. Methods: This is a two-center retrospective observational study. NAFLD patients complicated with T2DM treated with pemafibrate for >1 year were included, in whom prior treatment with SGLT2 inhibitor > 1 year failed to normalize serum alanine aminotransferase (ALT) levels. Hepatic inflammation, function, and fibrosis were assessed by ALT, albumin-bilirubin (ALBI) score, and Mac-2 binding protein glycosylation isomer (M2BPGi) levels, respectively. Results: Seven patients were included. The median duration of prior treatment with SGLT2 inhibitors was 2.3 years. During the one year before starting pemafibrate therapy, the therapy did not significantly change hepatic enzymes. All patients received pemafibrate 0.1 mg twice daily without dose escalations. During one year of pemafibrate therapy, triglyceride, aspartate aminotransferase, ALT, γ-glutamyl transpeptidase, ALBI score, and M2BPGi levels significantly improved (p < 0.05), although weight or hemoglobin A1c did not significantly change. Conclusions: One year of pemafibrate therapy improves markers of hepatic inflammation, function, and fibrosis in NAFLD patients in whom long-term SGLT2 inhibitor therapy failed to normalize serum ALT.

How far are we from an approved drug for non-alcoholic steatohepatitis?

INTRODUCTION

Metabolic associated fatty liver disease (MAFLD) previously known but still debatable, as non-alcoholic fatty liver disease (NAFLD) is one of the main causes of chronic liver disease and subsequent cirrhosis worldwide, accounting for around 30% of liver diseases. The change in its nomenclature has been brought about by the novel discoveries regarding its pathogenesis, in which metabolic dysfunction plays the most important role. It is widely known that for every disease, the treatment should always be targeted toward the underlying etiology and pathogenesis.

AREAS COVERED

MAFLD/NAFLD pathogenesis is heterogeneous, and includes multiple gene polymorphisms, presence of insulin resistance, as well as concomitant diseases that contribute to the disease onset and progression. As a result of this, even though lifestyle modification (owing to metabolic abnormalities) is the first line of treatment, multiple drugs have been tested to target each of the known pathways leading to MAFLD/NAFLD and progression of steatohepatitis. We aim to review the most relevant information regarding previous and ongoing research and recommendations regarding treatment of MAFLD/NAFLD.

EXPERT OPINION

Combination therapies associated to weight loss and exercise will be the optimal approach for these patients. It is important to evaluate each patient to select the specific combination according to patient characteristics.

Therapeutic Potentials of Reducing Liver Fat in Non-Alcoholic Fatty Liver Disease: Close Association with Type 2 Diabetes

Nonalcoholic fatty liver disease (NAFLD), the most widespread chronic liver disease worldwide, confers a significant burden on health systems and leads to increased mortality and morbidity through several extrahepatic complications. NAFLD comprises a broad spectrum of liver-related disorders, including steatosis, cirrhosis, and hepatocellular carcinoma. It affects almost 30% of adults in the general population and up to 70% of people with type 2 diabetes (T2DM), sharing common pathogenetic pathways with the latter. In addition, NAFLD is closely related to obesity, which acts in synergy with other predisposing conditions, including alcohol consumption, provoking progressive and insidious liver damage. Among the most potent risk factors for accelerating the progression of NAFLD to fibrosis or cirrhosis, diabetes stands out. Despite the rapid rise in NAFLD rates, identifying the optimal treatment remains a challenge. Interestingly, NAFLD amelioration or remission appears to be associated with a lower risk of T2DM, indicating that liver-centric therapies could reduce the risk of developing T2DM and vice versa. Consequently, assessing NAFLD requires a multidisciplinary approach to identify and manage this multisystemic clinical entity early. With the continuously emerging new evidence, innovative therapeutic strategies are being developed for the treatment of NAFLD, prioritizing a combination of lifestyle changes and glucose-lowering medications. Based on recent evidence, this review scrutinizes all practical and sustainable interventions to achieve a resolution of NAFLD through a multimodal approach.

Immunotherapy for NAFLD and NAFLD-related hepatocellular carcinoma

The progression of non-alcoholic fatty liver disease (NAFLD), the most common liver disease, leads to non-alcoholic steatohepatitis and hepatocellular carcinoma. Despite the increasing incidence and prevalence of NAFLD, its therapeutic and preventive strategies to lower the disease burden is limited. In recent years, immunotherapy, including anti-programmed cell death 1/programmed cell death 1 ligand 1 treatment, has emerged as a potential approach to reach satisfactory modulation for the progression of NAFLD and treatment of NAFLD-related hepatocellular carcinoma. However, the effectiveness of immunotherapy against NAFLD and NAFLD-related hepatocellular carcinoma is in the early phase and it is yet not advanced. In addition, conflicting results are being reported regarding the prognosis of patients with NAFLD-related hepatocellular carcinoma and high expression of programmed cell death 1/programmed cell death 1 ligand 1. Herein, this review will discuss and elucidate the attempts and underlying mechanisms of immunotherapy against NAFLD and NAFLD-related hepatocellular carcinoma.

Comparative efficacy of diabetes medications on liver enzymes and fat fraction in patients with nonalcoholic fatty liver disease: A network meta-analysis,

OBJECTIVES

This network meta-analysis (NMA) aimed to evaluate the relative rank-order of existing diabetes medications in patients with nonalcoholic fatty liver disease (NAFLD) with or without type 2 diabetes mellitus (T2DM).

METHODS

A systematic literature search was conducted using the Medline, Embase and Cochrane databases. Clinical trials comparing the efficacy of diabetes medications with other interventions, including lifestyle modification and placebo, in patients with NAFLD were included. The results from the NMA are presented as the weighted mean difference (WMD) of the continuous results and the corresponding 95% confidence intervals (95% CIs).

RESULTS

The articles presented the results of 49 trials involving 3,836 subjects published between 2013 and 2021. According to our results, thiazolidinedione (TZD) was ranked as the best diabetes medication in the reduction of alanine aminotransferase (ALT) (WMD = -10.10, 95% CI: -15.18, -5.01), followed by dipeptidyl peptidase-4 inhibitor (DPP4i) (WMD = -8.90, 95% CI: -14.41, -3.40). DPP4i also resulted in the greatest reduction in aspartate aminotransferase (AST) (WMD = -6.89, 95% CI: -11.72, -2.07). γ-Glutamyl transferase (γ-GT) reduction was highest in patients treated with glucagon-like peptide 1 receptor agonists (GLP1RAs) (WMD = -15.48, 95% CI: -30.93, -0.02). Ultimately, SGLT2is and GLP1RAs were superior to other diabetes medications or placebo in reducing liver fat fraction (LFF) (WMD = -6.09, 95% CI: -10.50, -1.68; WMD = -5.55, 95% CI: -10.40, -0.69, respectively).

CONCLUSION

Diabetes medications, including TZD, DPP4i and GLP1RAs, were found to be suitable alternatives for liver enzyme reduction in the treatment of NAFLD patients. SGLT2is are considered the most effective therapies for lipid modulation in these patients.

Old and new classes of glucose-lowering agents as treatments for non-alcoholic fatty liver disease: A narrative review

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease with a global prevalence of about 55% in people with type 2 diabetes mellitus (T2DM). T2DM, obesity and NAFLD are three closely inter-related pathological conditions. In addition, T2DM is one of the strongest clinical risk factors for the faster progression of NAFLD to non-alcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma. Increasing evidence suggests that newer classes of glucose-lowering drugs, such as peroxisome proliferator-activated receptor agonists, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors or sodium-glucose cotransporter-2 inhibitors, could reduce the rates of NAFLD progression. This narrative review aims to briefly summarize the recent results from randomized controlled trials testing the efficacy and safety of old and new glucose-lowering drugs for the treatment of NAFLD or NASH in adults both with and without coexisting T2DM.

Molecular mechanisms of metabolic associated fatty liver disease (MAFLD): functional analysis of lipid metabolism pathways

The metabolic-associated fatty liver disease (MAFLD) is a condition of fat accumulation in the liver in combination with metabolic dysfunction in the form of overweight or obesity and insulin resistance. It is also associated with an increased cardiovascular disease risk, including hypertension and atherosclerosis. Hepatic lipid metabolism is regulated by a combination of the uptake and export of fatty acids, de novo lipogenesis, and fat utilization by β-oxidation. When the balance between these pathways is altered, hepatic lipid accumulation commences, and long-term activation of inflammatory and fibrotic pathways can progress to worsen the liver disease. This review discusses the details of the molecular mechanisms regulating hepatic lipids and the emerging therapies targeting these pathways as potential future treatments for MAFLD.

A randomized triple-blind controlled clinical trial evaluation of sitagliptin in the treatment of patients with non-alcoholic fatty liver diseases without diabetes

The current study aimed to evaluate the efficacy of sitagliptin vs. placebo in treating non-alcoholic fatty liver disease (NAFLD). In a triple-blind randomized clinical trial, we assigned 120 eligible subjects with NAFLD to receive daily dosing of 50 mg sitagliptin (n = 60) or the placebo (n = 60) for 56 weeks and lifestyle modification in both groups. Laboratory and anthropometric outcomes were measured, and liver stiffness was assessed using a fibroscan. The primary outcome measures were changes from baseline in fibrosis scores and liver transferases. Out of 120 patients randomized into sitagliptin and placebo groups, 76 patients completed the trial, of whom 44 were in the sitagliptin and 32 in the placebo groups. Patients receiving sitagliptin showed a significant decrease in the fibrosis scores (P = 0.001). The reductions in the alanine aminotransferase (AST) (P = 0.036) and aspartate AST (P &lt; 0.001) levels were also statistically significant. The effect of sitagliptin in reducing fibrosis scores was significantly greater in normal-weight and overweight individuals than in obese individuals (p = 0.036, and p = 0.018, respectively), whereas the effects of sitagliptin on AST levels were greater among overweight/obese patients (p = 0.028, and p = 0.016, respectively). Sitagliptin reduced fibrosis scores and liver enzymes in NAFLD patients after 56 weeks of therapy. The changes in fibrosis scores were more prominent in patients with normal weight and overweight than obese patients, whereas the effects on AST levels were greater among overweight/obese patients. Other randomized trials with larger sample sizes and longer treatment durations may be required before precise results can be reached.

Clinical Trial Registration

[https://www.irct.ir/trial/46140], identifier [IRCT20140430017505N2].

Non-alcoholic fatty liver disease, metabolic syndrome, and type 2 diabetes mellitus: where do we stand today?

Non-alcoholic fatty liver disease (NAFLD), metabolic syndrome (MetS), and type 2 diabetes (T2DM) are metabolic disorders that belong to a highly prevalent disease cluster with a significant impact on public health worldwide. MetS is a complex condition characterized by metabolism perturbations that include glucose intolerance, insulin resistance, dyslipidaemia, associated pro-inflammatory state, and arterial hypertension. Because the components of MetS commonly co-occur, the management of these disorders cannot be considered separate issues. Thus NAFLD, recognized as a hepatic manifestation of MetS, is frequently associated with T2DM. This review analyses the underlying connections between these diseases and the risks associated with their co-occurrence. The effective management of NAFLD associated with MetS and T2DM involves an early diagnosis and optimal treatment of each condition leading to improvement in glycaemic and lipid regulation, liver steatosis, and arterial hypertension. The net effect of such treatment is the prevention of atherosclerotic cardiovascular diseases and liver fibrosis.

Prolonged effects of DPP-4 inhibitors on steato-hepatitic changes in Sprague-Dawley rats fed a high-cholesterol diet

OBJECTIVE

Sitagliptin and other dipeptidyl peptidase (DPP)-4 inhibitors/gliptins are antidiabetic drugs known to improve lipid profile, and confer anti-inflammatory and anti-fibrotic effects, which are independent of their hypoglycemic effects. However, in our previous short-term (35 days) studies, we showed that sitagliptin accentuates the hepato-inflammatory effects of high dietary cholesterol (Cho) in male Sprague-Dawley rats. Since most type 2 diabetics also present with lipid abnormalities and use DPP-4 inhibitors for glucose management, the present study was conducted to assess the impact of sitagliptin during long-term (98 days) feeding of a high Cho diet. An additional component of the present investigation was the inclusion of other gliptins to determine if hepatic steatosis, necro-inflammation, and fibrosis were specific to sitagliptin or are class effects.

METHODS

Adult male Sprague-Dawley rats were fed control or high Cho (2.0%) diets, and gavaged daily (from day 30 through 98) with vehicle or DPP-4 inhibitors (sitagliptin or alogliptin or saxagliptin). On day 99 after a 4 h fast, rats were euthanized. Blood and liver samples were collected to measure lipids and cytokines, and for histopathological evaluation, determination of hepatic lesions (steatosis, necrosis, inflammation, and fibrosis) using specific staining and immunohistochemical methods.

RESULTS

Compared to controls, the high Cho diet produced a robust increase in NASH like phenotype that included increased expression of hepatic (Tnfa, Il1b, and Mcp1) and circulatory (TNFα and IL-1β) markers of inflammation, steatosis, necrosis, fibrosis, and mononuclear cell infiltration. These mononuclear cells were identified as macrophages and T cells, and their recruitment in the liver was facilitated by marked increases in endothelium-expressed cell adhesion molecules. Importantly, treatment with DPP-4 inhibitors (3 tested) neither alleviated the pathologic responses induced by high Cho diet nor improved lipid profile.

CONCLUSIONS

The potential lipid lowering effects of DPP-4 inhibitors were diminished by high Cho (a significant risk factor for inducing liver damage). The robust inflammatory responses induced by high Cho feeding in long-term experiment were not exacerbated by DPP-4 inhibitors and a consistent hepatic inflammatory environment persisted, implying a prospective physiological adaptation.

Placebo effect on progression and regression in NASH: Evidence from a meta-analysis

BACKGROUND AND AIMS

The evaluation of the natural history of NASH has been limited. Currently, liver biopsy remains the gold standard in the assessment of NASH. Placebo-controlled trials represent a controlled environment with paired biopsies for the evaluation of NASH. This meta-analysis thus seeks to quantify the change severity of NASH over time, with patients on placebo arms from randomized controlled trials (RCTs) to examine the natural history of NASH.

METHODS

A search was conducted to include NASH RCTs with placebo treatment arms. Primary outcomes were (1) the resolution of NASH without worsening of fibrosis, (2) two-point reduction in NAFLD activity score without worsening of fibrosis, and (3) at least one-point reduction in fibrosis. Generalized linear mix model was used to estimate pooled proportion and mean differences.

RESULTS

This meta-analysis of 43 RCTs included 2649 placebo-treated patients. The pooled estimate of NASH resolution and two-point NAFLD activity score reduction without worsening of fibrosis was 11.65% (95% CI: 7.98-16.71) and 21.11% (95% CI: 17.24-25.57). The rate of ≥1 stage reduction and progression of fibrosis was 18.82% (95% CI: 15.65-22.47) and 22.74% (CI: 19.63-26.17), respectively. Older age and African American ethnicity was associated with lower NASH resolution rate in placebo-treated patients.

CONCLUSIONS

Despite the absence of any pharmacological interventions, a significant proportion of patients in the placebo arm demonstrated improvements in liver histology, highlighting the possibility that NASH is a disease that can not only progress but regress spontaneously over time. Additionally, histologic response in placebo-treated patients is helpful in future design of phase 2B and phase 3 trials.

Ascorbic Acid Ameliorates Cardiac and Hepatic Toxicity Induced by Azithromycin-Etoricoxib Drug Interaction

The complexity of prescribing safe and effective drug therapy is still challenging. Due to the increased number of medications taken by patients, the potential for drug-drug interactions has clinically important consequences. This study focuses on the potential drug-drug interaction between azithromycin and etoricoxib and the possibility of counteracting this adverse reaction by giving ascorbic acid intraperitoneally to male albino rats. Sixty adult male albino rats weighing 150–180 g were used. The rats were allocated into six equal groups. One group was a control, and the others were given azithromycin, etoricoxib, either alone or combination, with one group treated with ascorbic acid and the last group treated with the drug combination and ascorbic acid. Blood samples were collected for measuring AST, ALT, LDH, CK-MB, and troponin alongside antioxidant enzymes and histopathological examination for both liver and heart tissue. The results showed both hepatic and cardiac damage in azithromycin and etoricoxib groups represented by increasing levels of heaptoc enzymes (ALT, AST, LDH, CK-MB, and troponin) with declining antioxidant enzymes and elevation of malondialdehyde and the appearance of hepatic and cardiac toxicities. Upon administration, ascorbic acid ameliorated all the mentioned biochemical parameters. In conclusion, ascorbic acid has great antioxidant capacities and hepatic and cardiac ameliorative effects and can alleviate drug interaction toxicity.

Nonalcoholic Steatohepatitis (NASH) and Atherosclerosis: Explaining Their Pathophysiology, Association and the Role of Incretin-Based Drugs

Nonalcoholic steatohepatitis (NASH) is the most severe manifestation of nonalcoholic fatty liver disease (NAFLD), a common complication of type 2 diabetes, and may lead to cirrhosis and hepatocellular carcinoma. Oxidative stress and liver cell damage are the major triggers of the severe hepatic inflammation that characterizes NASH, which is highly correlated with atherosclerosis and coronary artery disease. Regarding drug therapy, research on the role of GLP-1 analogues and DPP4 inhibitors, novel classes of antidiabetic drugs, is growing. In this review, we outline the association between NASH and atherosclerosis, the underlying molecular mechanisms, and the effects of incretin-based drugs, especially GLP-1 RAs, for the therapeutic management of these conditions.

American Association of Clinical Endocrinology Clinical Practice Guideline for the Diagnosis and Management of Nonalcoholic Fatty Liver Disease in Primary Care and Endocrinology Clinical Settings: Co-Sponsored by the American Association for the Study of Liver Diseases (AASLD)

OBJECTIVE

To provide evidence-based recommendations regarding the diagnosis and management of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) to endocrinologists, primary care clinicians, health care professionals, and other stakeholders.

METHODS

The American Association of Clinical Endocrinology conducted literature searches for relevant articles published from January 1, 2010, to November 15, 2021. A task force of medical experts developed evidence-based guideline recommendations based on a review of clinical evidence, expertise, and informal consensus, according to established American Association of Clinical Endocrinology protocol for guideline development.

RECOMMENDATION SUMMARY

This guideline includes 34 evidence-based clinical practice recommendations for the diagnosis and management of persons with NAFLD and/or NASH and contains 385 citations that inform the evidence base.

CONCLUSION

NAFLD is a major public health problem that will only worsen in the future, as it is closely linked to the epidemics of obesity and type 2 diabetes mellitus. Given this link, endocrinologists and primary care physicians are in an ideal position to identify persons at risk on to prevent the development of cirrhosis and comorbidities. While no U.S. Food and Drug Administration-approved medications to treat NAFLD are currently available, management can include lifestyle changes that promote an energy deficit leading to weight loss; consideration of weight loss medications, particularly glucagon-like peptide-1 receptor agonists; and bariatric surgery, for persons who have obesity, as well as some diabetes medications, such as pioglitazone and glucagon-like peptide-1 receptor agonists, for those with type 2 diabetes mellitus and NASH. Management should also promote cardiometabolic health and reduce the increased cardiovascular risk associated with this complex disease.

Meta-analysis: analysis of mechanistic pathways in the treatment of non-alcoholic steatohepatitis. Evidence from a Bayesian network meta-analysis

BACKGROUND AND AIMS

Non-alcoholic steatohepatitis (NASH) is the most common cause of liver disease. However, there is lack of comparison of efficacy between different NASH drug classes. We conducted a network meta-analysis evaluating drug classes through comparing histological outcomes and targets of drugs.

APPROACH AND RESULTS

Medline, EMBASE and CENTRAL were searched for randomised controlled trials evaluating NASH drugs in biopsy-proven NASH patients. Primary outcomes included NASH resolution without worsening of fibrosis, at least 2-point reduction in Non-alcoholic fatty liver disease Activity Score (NAS) without worsening of fibrosis and at least 1-point reduction in fibrosis. Treatments were classified into inflammation, energy, bile acid and fibrosis modulators. The analysis was conducted with Bayesian network model and surface under the cumulative ranking curve (SUCRA) analysis. Among 49 included trials, treatments modulating energy (Risk ratio (RR): 1.92, Credible intervals (Crl): 1.59-2.34) were most likely to achieve NASH resolution followed by treatments modulating fibrosis (RR 1.66, Crl: 0.65-4.50), bile acids (RR: 1.37, Crl: 0.99-1.92) and inflammation (RR: 1.00, Crl: 0.75-1.33). Energy and bile acids modulation were effective in at least 2-point NAS reduction without worsening of fibrosis (RR: 1.52, Crl 1.30-1.77; RR: 1.69, Crl 1.41-2.03) and at least 1-point reduction in fibrosis (RR: 1.26, Crl:1.05-1.49; RR: 1.54, Crl: 1.20-1.97).

CONCLUSIONS

This network analysis demonstrates the relative superiority of drugs modulating energy pathways and bile acids in NASH treatment. This guides the development and selection of drugs for combination therapies.

Antidiabetic Drug Sitagliptin with Divalent Transition Metals Manganese and Cobalt: Synthesis, Structure, Characterization Antibacterial and Antioxidative Effects in Liver Tissues

Metals and their complexes have an increasing number of medical applications. Sitagliptin (STG) acts as an antidiabetic drug. Mn(II) and Co(II) complexes were studied and characterized based on physical characterization, FT-IR, DG/TG, XRD, ESM, and TEM. Data revealed that STG acts as a bidentate ligand through the oxygen atom of a carbonyl group and the nitrogen atom of an amino group. Magnetic measurement data revealed that the Mn/STG metal complex has a square planner geometry. The experiment was performed on 40 male albino rats who were divided into four groups: the control group, STG group, group treated with STG/Mn, and group treated with Co/STG. Biomarkers for hepatic enzymes and antioxidants were found in the blood, and hepatic tissue histology was evaluated. STG in combination with Mn and Co administration showed potent protective effects against hepatic biochemical alterations induced by STG alone, as well as suppressing oxidative stress and structural alterations. These complexes prevented any stress and improved hepatic enzymatic levels more than STG alone. The STG/Mn complex was highly effective against Bacillus subtilis and Streptococcus pneumonia, while STG/Co was highly effective against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureas. Therefore, STG combined with Mn and Co produced a synergistic effect against oxidative stress and improved the histological structure of the liver tissues. STG metal complexes with Mn and Co showed the most potential ameliorative antioxidant and hepatoprotective effects.

The metabolic triad of non-alcoholic fatty liver disease, visceral adiposity and type 2 diabetes: Implications for treatment

Non-alcoholic fatty liver disease (NAFLD) is associated with visceral obesity, insulin resistance, type 2 diabetes (T2D) and has been often considered as the hepatic expression of the metabolic syndrome (MetS). Epidemiological studies highlight a bidirectional relationship of NAFLD with T2D in which NAFLD increases the risk of incident T2D and T2D increases the risk of severe non-alcoholic steatohepatitis (NASH) and liver fibrosis. Regarding the molecular determinants of NAFLD, we specifically focused in this review on adipocyte dysfunction as a key molecular link between visceral adipose tissue, MetS and NAFLD. Notably, the subcutaneous white adipose tissue expandability appears a critical adaptive buffering mechanism to prevent lipotoxicity and its related metabolic complications, such as NAFLD and T2D. There is a clinical challenge to consider therapeutic strategies targeting the metabolic dysfunction common to NASH and T2D pathogenesis. Strategies that promote significant and sustained weight loss (~10% of total body weight) such as metabolic and bariatric surgery or incretin-based therapies (GLP-1 receptor agonists or dual GLP-1/GIP or GLP-1/glucagon receptor co-agonists) are among the most efficient ones. In addition, insulin sensitizers such as PPARγ (pioglitazone) and pan-PPARs agonists (lanifibranor) have shown some beneficial effects on both NASH and liver fibrosis. Since NASH is a complex and multifactorial disease, it is conceivable that targeting different pathways, not only insulin resistance but also inflammation and fibrotic processes, is required to achieve NASH resolution.

Novel Antidiabetic Strategies and Diabetologists' Views in Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide with high prevalence, especially in individuals with obesity and type 2 diabetes. Among individuals with type 2 diabetes, the severe insulin resistant subgroup has the greatest risk of NAFLD, likely due to dysfunctional adipose tissue mass but also genetic factors, and may progress earlier to inflammatory and profibrotic nonalcoholic steatohepatitis (NASH). NASH has been associated with increased liver-related as well as cardiovascular morbidity and mortality. International diabetes associations recommend certain screening and treatment strategies for NASH in type 2 diabetes, which, however, bear several limitations such as lack of accurate noninvasive diagnostic tools and targeted treatments. Currently, antihyperglycemic drug concepts based on glucagon-like peptide-1 receptor agonists and sodium glucose cotransporter 2 inhibitors offer metabolic as well as cardiorenal benefits and provide treatment options for both hyperglycemia and NASH in type 2 diabetes.

Non-alcoholic fatty liver disease: A patient guideline

This patient guideline is intended for all patients at risk of or living with non-alcoholic fatty liver disease (NAFLD). NAFLD is the most frequent chronic liver disease worldwide and comes with a high disease burden. Yet, there is a lot of unawareness. Furthermore, many aspects of the disease are still to be unravelled, which has an important impact on the information that is given (or not) to patients. Its management requires a close interaction between patients and their many healthcare providers. It is important for patients to develop a full understanding of NAFLD in order to enable them to take an active role in their disease management. This guide summarises the current knowledge relevant to NAFLD and its management. It has been developed by patients, patient representatives, clinicians and scientists and is based on current scientific recommendations, intended to support patients in making informed decisions.

The complex link between NAFLD and type 2 diabetes mellitus - mechanisms and treatments

Nonalcoholic fatty liver disease (NAFLD) has reached epidemic proportions worldwide. NAFLD and type 2 diabetes mellitus (T2DM) are known to frequently coexist and act synergistically to increase the risk of adverse (hepatic and extra-hepatic) clinical outcomes. T2DM is also one of the strongest risk factors for the faster progression of NAFLD to nonalcoholic steatohepatitis, advanced fibrosis or cirrhosis. However, the link between NAFLD and T2DM is more complex than previously believed. Strong evidence indicates that NAFLD is associated with an approximate twofold higher risk of developing T2DM, irrespective of obesity and other common metabolic risk factors. This risk parallels the severity of NAFLD, such that patients with more advanced stages of liver fibrosis are at increased risk of incident T2DM. In addition, the improvement or resolution of NAFLD (on ultrasonography) is associated with a reduction of T2DM risk, adding weight to causality and suggesting that liver-focused treatments might reduce the risk of developing T2DM. This Review describes the evidence of an association and causal link between NAFLD and T2DM, discusses the putative pathophysiological mechanisms linking NAFLD to T2DM and summarizes the current pharmacological treatments for NAFLD or T2DM that might benefit or adversely affect the risk of T2DM or NAFLD progression.

Emerging and Established Therapeutic Approaches for Nonalcoholic Fatty Liver Disease

PURPOSE

Nonalcoholic fatty liver disease (NAFLD), more recently referred to as metabolic-associated fatty liver disease, refers to a disease spectrum ranging from hepatic steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis, associated with hepatic complications (including liver fibrosis, cirrhosis, and hepatocellular carcinoma) and extrahepatic complications (particularly cardiometabolic complications, including type 2 diabetes and cardiovascular disease). Treatment options include lifestyle interventions (dietary modification and physical activity programs) and pharmacologic interventions. Treatment aims should be broad, with a hepatic focus (to improve/reverse hepatic inflammation, fibrosis, and steatohepatitis), ideally with additional extrahepatic effects affecting metabolic co-morbidities (eg, insulin resistance, glucose dysregulation, dyslipidemia), causing weight loss and affording cardiovascular protection. NASH and fibrosis represent the main histopathological features that warrant treatment to prevent disease progression. Despite a paucity of established treatments, the array of potential molecular targets, pathways, and potential treatments is continually evolving. The goal of this article was to provide a narrative review summarizing the emerging and more established therapeutic options considering the complex pathophysiology of NAFLD and the important long-term sequelae of this condition.

METHODS

The literature was reviewed by using PubMed, conference abstracts, and press releases from early-phase clinical studies to provide an overview of the evidence.

FINDINGS

As understanding of the pathophysiology of NASH/NAFLD evolves, drugs with different mechanisms of action, targeting different molecular targets and aberrant pathways that mediate hepatic steatosis, inflammation, and fibrosis, have been developed and are being tested in clinical trials. Pharmacologic therapies fall into 4 main categories according to the molecular targets/pathways they disrupt: (1) meta-bolic targets, targeting insulin resistance, hepatic de novo lipogenesis, or substrate utilization; (2) inflam-matory pathways, inhibiting inflammatory cell recruitment/signaling, reduce oxidative/endoplasmic reticulum stress or are antiapoptotic; (3) the liver-gut axis, which modulates bile acid enterohepatic circulation/signaling or alters gut microbiota; and (4) antifibrotic targets, targeting hepatic stellate cells, decrease collagen deposition or increase fibrinolysis.

IMPLICATIONS

Lifestyle modification must remain the cornerstone of treatment. Pharmacologic treatment is reserved for NASH or fibrosis, the presence of which requires histopathological confirmation. The disease complexity provides a strong rationale for combination therapies targeting multiple pathways simultaneously.

Nonalcoholic fatty liver disease (NAFLD) from pathogenesis to treatment concepts in humans

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) comprises hepatic alterations with increased lipid accumulation (steatosis) without or with inflammation (nonalcoholic steatohepatitis, NASH) and/or fibrosis in the absence of other causes of liver disease. NAFLD is developing as a burgeoning health challenge, mainly due to the worldwide obesity and diabetes epidemics.

SCOPE OF REVIEW

This review summarizes the knowledge on the pathogenesis underlying NAFLD by focusing on studies in humans and on hypercaloric nutrition, including effects of saturated fat and fructose, as well as adipose tissue dysfunction, leading to hepatic lipotoxicity, abnormal mitochondrial function, and oxidative stress, and highlights intestinal dysbiosis. These mechanisms are discussed in the context of current treatments targeting metabolic pathways and the results of related clinical trials.

MAJOR CONCLUSIONS

Recent studies have provided evidence that certain conditions, for example, the severe insulin-resistant diabetes (SIRD) subgroup (cluster) and the presence of an increasing number of gene variants, seem to predispose for excessive risk of NAFLD and its accelerated progression. Recent clinical trials have been frequently unsuccessful in halting or preventing NAFLD progression, perhaps partly due to including unselected cohorts in later stages of NAFLD. On the basis of this literature review, this study proposed screening in individuals with the highest genetic or acquired risk of disease progression, for example, the SIRD subgroup, and developing treatment concepts targeting the earliest pathophysiolgical alterations, namely, adipocyte dysfunction and insulin resistance.

Emerging therapeutic approaches for the treatment of NAFLD and type 2 diabetes mellitus

Non-alcoholic fatty liver disease (NAFLD) has emerged as the most prevalent liver disease in the world, yet there are still no approved pharmacological therapies to prevent or treat this condition. NAFLD encompasses a spectrum of severity, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Although NASH is linked to an increased risk of hepatocellular carcinoma and cirrhosis and has now become the leading cause of liver failure-related transplantation, the majority of patients with NASH will ultimately die as a result of complications of type 2 diabetes mellitus (T2DM) and cardiometabolic diseases. Importantly, NAFLD is closely linked to obesity and tightly interrelated with insulin resistance and T2DM. Thus, targeting these interconnected conditions and taking a holistic attitude to the treatment of metabolic disease could prove to be a very beneficial approach. This Review will explore the latest relevant literature and discuss the ongoing therapeutic options for NAFLD focused on targeting intermediary metabolism, insulin resistance and T2DM to remedy the global health burden of these diseases.

Anti-diabetic drugs and NASH: from current options to promising perspectives

Introduction: Accumulating evidence supports a bidirectional association between nonalcoholic steatohepatitis (NASH) and type 2 diabetes (T2D). There is a clinical challenge to consider pharmaceutical strategies targeting the metabolic dysfunction common to NASH and T2D pathogenesis.Areas covered: By using PubMed, we performed a literature search to review the potential beneficial effect of anti-diabetic and metabolic investigational drugs on NASH.Expert opinion: Since insulin resistance is central in the pathophysiology of both T2D and NASH, there is an urgent need for new insulin sensitizers. Peroxisome proliferator-activated receptor (PPAR) agonists, especially PPARγ and pan-PPARs agonists, have shown some beneficial effects on both NASH and liver fibrosis, but their routine use should be limited by their safety profile. Incretin-based therapies, including glucagon-like peptide 1 receptor agonists (GLP-1 RAs) and the polyagonists (GLP-1, GIP, glucagon) under development are the most promising anti-diabetic drugs for NASH treatment, mainly due to their action on body weight loss. Preliminary, preclinical and early phase studies suggest that SGLT2 inhibitors and fibroblast growth factor (FGF)19 and FGF21-based therapies are promising targets for NASH and T2D treatment. The common weakness for all of these drugs is their limited effect on liver fibrosis, potentially due to short-term trial design.

Liver-targeting drugs and their effect on blood glucose and hepatic lipids

The global epidemic of non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) and the high prevalence among individuals with type 2 diabetes has attracted the attention of clinicians specialising in liver disorders. Many drugs are in the pipeline for the treatment of NAFLD/NASH, and several glucose-lowering drugs are now being tested specifically for the treatment of liver disease. Among these are nuclear hormone receptor agonists (e.g. peroxisome proliferator-activated receptor agonists, farnesoid X receptor agonists and liver X receptor agonists), fibroblast growth factor-19 and -21, single, dual or triple incretins, sodium-glucose cotransporter inhibitors, drugs that modulate lipid or other metabolic pathways (e.g. inhibitors of fatty acid synthase, diacylglycerol acyltransferase-1, acetyl-CoA carboxylase and 11β-hydroxysteroid dehydrogenase type-1) or drugs that target the mitochondrial pyruvate carrier. We have reviewed the metabolic effects of these drugs in relation to improvement of diabetic hyperglycaemia and fatty liver disease, as well as peripheral metabolism and insulin resistance.

Nonalcoholic Fatty Liver Disease (NAFLD). Mitochondria as Players and Targets of Therapies?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and represents the hepatic expression of several metabolic abnormalities of high epidemiologic relevance. Fat accumulation in the hepatocytes results in cellular fragility and risk of progression toward necroinflammation, i.e., nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and eventually hepatocellular carcinoma. Several pathways contribute to fat accumulation and damage in the liver and can also involve the mitochondria, whose functional integrity is essential to maintain liver bioenergetics. In NAFLD/NASH, both structural and functional mitochondrial abnormalities occur and can involve mitochondrial electron transport chain, decreased mitochondrial β-oxidation of free fatty acids, excessive generation of reactive oxygen species, and lipid peroxidation. NASH is a major target of therapy, but there is no established single or combined treatment so far. Notably, translational and clinical studies point to mitochondria as future therapeutic targets in NAFLD since the prevention of mitochondrial damage could improve liver bioenergetics.

Efficacy of Various Hypoglycemic Agents in the Treatment of Patients With Nonalcoholic Liver Disease With or Without Diabetes： A Network Meta-Analysis

Objective

To comprehensively evaluate and compare the therapeutic effects of various hypoglycemic agents in NAFLD patients with or without diabetes.

Methods

All literature from the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, and Clinical Trials was searched, and the language was limited to English. Two reviewers independently assessed study eligibility, continuous data extraction, and independent assessment of bias risk. Our primary outcomes were alanine aminotransferase (ALT), aspartate aminotransferase (AST) and triglyceride levels, while our secondary outcomes were high-density lipoprotein (HDL) and low-density lipoprotein (LDL) levels, body weight, BMI, and fasting glucose and glycosylated hemoglobin (HbA1c) levels.

Results

The review identified 20 eligible trials that met the inclusion criteria. We found that, compared to other drugs, thiazolidinediones, especially pioglitazone, had a greater effect on the levels of ALT (-8.01 (95% CI -14.3 to 2.02)) and AST (-5.0 (95% CI -9.21 to -1,22)) and other biological indicators, but they were also associated with an increased risk of weight gain (3.62 (95% CI 2.25 to 4.99) and increased BMI (0.59 (95% Cl -0.13 to 1.29). GLP1 RAs and metformin also had better therapeutic effects than other drugs as measured by the levels of ALT (liraglutide: -9.36 (95% Cl -18 to -0.34), metformin: -2.84 (95% CI -11.09 to 5.28)) and AST (liraglutide: -5.14 (95% CI -10.69 to 0.37), metformin: -2.39 (95% CI -7.55, 2.49)) and other biological indicators.

Conclusion

Despite the significant risk of weight gain, thiazolidinediones, especially pioglitazone, are beneficial in normalizing liver and glucose metabolism in NAFLD patients. In clinical practice, we believe that GLP1 RAs such as liraglutide and exenatide or metformin can be used in combination to offset the risk of weight gain associated with thiazolidinediones. However, long-term studies are still needed to verify the efficacy and safety of individual hypoglycemic agents.

Systematic Review Registration

[PROSPERO], identifier [CRD42020212025].

New Drugs on the Block-Emerging Treatments for Nonalcoholic Steatohepatitis

Patients with nonalcoholic steatohepatitis (NASH) are at higher risk of progression to advanced stages of fibrosis, cirrhosis, hepatocellular carcinoma and other end-stage liver disease complications. When addressing treatment of NASH, we have limited approved options, and the mainstay of therapy is lifestyle intervention. Extensive research and revelation in the field of pathogenesis of NASH has offered new possibilities of treatment and emerging new drugs that are being tested currently in numerous preclinical and clinical trials. These drugs target almost all steps in the pathogenesis of NASH to improve insulin sensitivity, glucose and lipid metabolism, to inhibit de novo lipogenesis and delivery of lipids to the liver, and to influence apoptosis, inflammation and fibrogenesis. Although NASH is a multifactorial disease, in the future we could identify the predominating pathological mechanism and, by choosing the most appropriate specific medication, tailor the treatment for every patient individually.

Novel glucose-lowering drugs for non-alcoholic fatty liver disease

BACKGROUND

The efficacy of novel glucose-lowering drugs in treating non-alcoholic fatty liver disease (NAFLD) is unknown.

AIM

To evaluate the efficacy of glucose-lowering drugs dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1 RAs), and sodium-glucose cotransporter 2 (SGLT2) inhibitors in treating NAFLD and to perform a comparison between these treatments.

METHODS

Electronic databases were systematically searched. The inclusion criteria were: Randomized controlled trials comparing DPP-4 inhibitors, GLP-1 RAs, or SGLT2 inhibitors against placebo or other active glucose-lowering drugs in NAFLD patients, with outcomes of changes in liver enzyme [alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST)] from baseline.

RESULTS

Nineteen studies were finally included in this meta-analysis. Compared with placebo or other active glucose-lowering drug treatment, treatment with DPP-4 inhibitors, GLP-1 RAs, and SGLT2 inhibitors all led to a significant decrease in ALT change and AST change from baseline. The difference between the DPP-4 inhibitor and SGLT2 inhibitor groups in ALT change was significant in favor of DPP-4 inhibitor treatment (P < 0.05). The trends of reduction in magnetic resonance imaging proton density fat fraction and visceral fat area changes were also observed in all the novel glucose-lowering agent treatment groups.

CONCLUSION

Treatment with DPP-4 inhibitors, GLP-1 RAs, and SGLT2 inhibitors resulted in improvements in serum ALT and AST levels and body fat composition, indicating a beneficial effect in improving liver injury and reducing liver fat in NAFLD patients.

Protocols for Mitochondria as the Target of Pharmacological Therapy in the Context of Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent metabolic chronic liver diseases in developed countries and puts the populations at risk of progression to liver necro-inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma. Mitochondrial dysfunction is involved in the onset of NAFLD and contributes to the progression from NAFLD to nonalcoholic steatohepatitis (NASH). Thus, liver mitochondria could become the target for treatments for improving liver function in NAFLD patients. This chapter describes the most important steps used for potential therapeutic interventions in NAFLD patients, discusses current options gathered from both experimental and clinical evidence, and presents some novel options for potentially improving mitochondrial function in NAFLD.

Therapeutic approaches for non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) have been reported as a novel worldwide epidemic, very often associated with obesity, metabolic syndrome, and type 2 diabetes. Both conditions have also been shown to be associated with a number of endocrine pathologies. Despite the epidemic, the complex pathophysiology and major complications, ranging from metabolic disturbances (diabetes and more) to cardiovascular disease, people with NASH are left with very few management options. The best and most approved therapeutic option is lifestyle intervention. Although pharmacotherapies based on pathophysiological background are in development, response rates appear modest, mainly for fibrosis treatment, which is the reason for lack of approved drug therapy. Previous drugs analyzed, such as pioglitazone and vitamin E, show weak efficacy. From different phase II trials, antidiabetic (injectable) drugs seem to be promising, both in mono- or bitherapy. Also, derivatives of peroxisome proliferator-activated receptors may have an interesting future, as well. For that reason, more focus should be given on prevention of this novel disease entity. In view of this booming epidemic, with a background of obesity and type 2 diabetes, and the important medical consequences, early recognition, prevention and intervention of NAFLD/NASH seems appropriate. In this review, we will focus on the different current and future therapeutic intervention options, taking into consideration the complex pathophysiology of this disease.

A Review of the Epidemiology, Pathophysiology, and Efficacy of Anti-diabetic Drugs Used in the Treatment of Nonalcoholic Fatty Liver Disease

In recent years, epidemiological studies have consistently demonstrated that the coexistence of nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) is strongly associated with increased mortality and morbidity related to hepatic- and extrahepatic causes. Indeed, compared with the general population, patients with T2DM are more likely to be diagnosed with more severe forms of NAFLD (i.e., nonalcoholic steatohepatitis (NASH) with liver fibrosis). There is an ongoing debate whether NALFD is a consequence of diabetes or whether NAFLD is simply a component and manifestation of the metabolic syndrome, since liver fat (steatosis) and even more advanced stages of liver fibrosis can occur in the absence of diabetes. Nevertheless, insulin resistance is a key component of the mechanism of NAFLD development; furthermore, therapies that lower blood glucose concentrations also appear to be effective in the treatment of NAFLD. Here, we will discuss the pathophysiological and epidemiological associations between NAFLD and T2DM. We will also review currently available anti-diabetic agents with their regard to their efficacy of NAFLD/NASH treatment.

Type 2 diabetes subgroups and potential medication strategies in relation to effects on insulin resistance and beta-cell function: A step toward personalised diabetes treatment?

Background

Type 2 diabetes is a syndrome defined by hyperglycaemia that is the result of various degrees of pancreatic β-cell failure and reduced insulin sensitivity. Although diabetes can be caused by multiple metabolic dysfunctions, most patients are defined as having either type 1 or type 2 diabetes. Recently, Ahlqvist and colleagues proposed a new method of classifying patients with adult-onset diabetes, considering the heterogenous metabolic phenotype of the disease. This new classification system could be useful for more personalised treatment based on the underlying metabolic disruption of the disease, although to date no prospective intervention studies have generated data to support such a claim.

Scope of Review

In this review, we first provide a short overview of the phenotype and pathogenesis of type 2 diabetes and discuss the current and new classification systems. We then review the effects of different anti-diabetic medication classes on insulin sensitivity and β-cell function and discuss future treatment strategies based on the subgroups proposed by Ahlqvist et al.

Major Conclusions

The proposed novel type 2 diabetes subgroups provide an interesting concept that could lead to a better understanding of the pathophysiology of the broad group of type 2 diabetes, paving the way for personalised treatment choices based on understanding the root cause of the disease. We conclude that the novel subgroups of adult-onset diabetes would benefit from anti-diabetic medications that take into account the main pathophysiology of the disease and thereby prevent end-organ damage. However, we are only beginning to address the personalised treatment of type 2 diabetes, and studies investigating the effects of current and novel drugs in subgroups with different metabolic phenotypes are needed to develop personalised treatment of the syndrome

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Novel subgroups of type 2 diabetes provide a concept that could lead to a better understanding of its pathophysiology.

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Treatment strategies would benefit from anti-diabetic medications that influence the main pathophysiology of diabetes.

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Here, we review different anti-diabetic medications classes affecting insulin sensitivity and β-cell function.

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We suggest that future treatment strategies could benefit by taking into account subgroups provided by Ahlqvist et al.

Comparison of dapagliflozin and teneligliptin in nonalcoholic fatty liver disease patients without type 2 diabetes mellitus: a prospective randomized study

There are no reports regarding the efficacy of sodium-glucose cotransporter 2 inhibitor (SGLT2i) and dipeptidyl peptidase 4 inhibitor (DPP4i) administrations in nonalcoholic fatty liver disease (NAFLD) patients without type 2 diabetes mellitus. The purpose of this study was to evaluate the efficacy of those drugs in such patients. NAFLD patients without type 2 diabetes mellitus were enrolled in this single center double-blind randomized prospective study, and allocated to receive either dapagliflozin (SGLT2i) or teneligliptin (DPP4i) for 12 weeks. Laboratory variables and body compositions were assessed at the baseline and end of treatment. The primary endpoint was alanine aminotransferase (ALT) reduction level at the end of treatment. Twenty-two eligible patients (dapagliflozin group, n = 12; teneligliptin group, n = 10) were analyzed. In both groups, the serum concentration of ALT was significantly decreased after treatment (p<0.05). Multiple regression analysis results showed that decreased body weight of patients with dapagliflozin administration was significantly related to changes in total body water and body fat mass. Administration of dapagliflozin or teneligliptin decreased the serum concentration of ALT in NAFLD patients without type 2 diabetes mellitus. With dapagliflozin, body weight decreased, which was related to changes in total body water and body fat mass (UMIN000027304).

Beneficial and deleterious effects of sitagliptin on a methionine/choline-deficient diet-induced steatohepatitis in rats

Non-alcoholic fat liver disease (NAFLD) is the most common chronic liver disease in the world. NAFLD is a spectrum of diseases ranging from simple steatosis to hepatic carcinoma. The complexity of pathomechanisms makes treatment difficult. The oral antidiabetic agents, dipeptidyl peptidase four inhibitors (DPP-4i) have been proposed as possible therapeutic agents. This study was performed using a well-established NAFLD model in rats to elucidate whether sitagliptin could prevent steatohepatitis. Rats were fed a methionine/choline-deficient (MCD) diet with or without sitagliptin treatment for six weeks. Liver tissue was examined to estimate sitagliptin's effect on the development of NASH. The MCD diet decreased the SAM/SAH ratio, and increased plasma levels of homocysteine, free fatty acids, and long-chain acylcarnitines in the MCD rats. MMP2 and Col1A2 expression also increased under the MCD diet. Sitagliptin treatment did not reverse these effects and increased steatosis and long-chain acylcarnitines. In conclusion, sitagliptin was ineffective to prevent from NAFLD in the MCD rat model. This result challenges previous data reporting beneficial effects and is consistent with the clinical trials' negative results.

Evaluation and management of extrahepatic manifestations of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a multisystemic disease and a rapidly growing cause of chronic liver disease in children and adults worldwide. Diagnosis and management of extrahepatic manifestations of NAFLD, including cardiovascular disease (CVD), type 2 diabetes mellitus, metabolic syndrome, chronic kidney disease, obstructive sleep apnea, polycystic ovarian syndrome, hypothyroidism, psoriasis, and extrahepatic malignancy are crucial for the treatment of patients with NAFLD. The leading cause of death in NAFLD is primarily from CVD, followed by liver-related mortality, extrahepatic cancer, liver cancer, and diabetes-related mortality. Therefore, clinicians need to identify high-risk patients earlier in the disease course and be aware of the extrahepatic manifestations of NAFLD to improve liver disease outcomes. In this review, we focus on the monitoring and management of the extrahepatic manifestations of NAFLD.

A look to the future in non-alcoholic fatty liver disease: Are glucagon-like peptide-1 analogues or sodium-glucose co-transporter-2 inhibitors the answer?

The increasing prevalence of diabetes and non-alcoholic fatty liver disease (NAFLD) is a growing public health concern associated with significant morbidity, mortality and economic cost, particularly in those who progress to cirrhosis. Medical treatment is frequently limited, with no specific licensed treatments currently available for people with NAFLD. Its association with diabetes raises the possibility of shared mechanisms of disease progression and treatment. With the ever-growing interest in the non-glycaemic effects of diabetes medications, studies and clinical trials have investigated hepatic outcomes associated with the use of drug classes used for people with type 2 diabetes (T2D), such as glucagon-like peptide-1 (GLP-1) analogues or sodium-glucose co-transporter-2 (SGLT2) inhibitors. Studies exploring the use of GLP-1 analogues or SGLT2 inhibitors in people with NAFLD have observed improved measures of hepatic inflammation, liver enzymes and radiological features over short periods. However, these studies tend to have variable study populations and inconsistent reported outcomes, limiting comparison between drugs and drug classes. As these drugs appear to improve biomarkers of NAFLD, clinicians should consider their use in patients with NAFLD and T2D. However, further evidence with greater participant numbers and longer trial durations is required to support specific licensing for people with NAFLD. Larger trials would allow reporting of major adverse hepatic events, akin to cardiovascular and renal outcome trials, to be determined. This would provide a more meaningful evaluation of the impact of these drugs in NAFLD. Nevertheless, these drugs represent a future potential therapeutic avenue in this difficult-to-treat population and may beget significant health and economic impacts.