Pancreatic β-Cell Dysfunction Is Associated with Nonalcoholic Fatty Liver Disease

Metabolic-associated fatty liver disease is characterized by a post-oral glucose load hyperinsulinemia in individuals with mild metabolic alterations

Metabolic-associated fatty liver disease (MAFLD) has been identified as risk factor of incident type 2 diabetes (T2D), but the underlying postprandial mechanisms remain unclear. We compared the glucose metabolism, insulin resistance, insulin secretion, and insulin clearance post-oral glucose tolerance test (OGTT) between individuals with and without MAFLD. We included 50 individuals with a body mass index (BMI) between 25 and 40 kg/m2 and ≥1 metabolic alteration: increased fasting triglycerides or insulin, plasma glucose 5.5-6.9 mmol/L, or glycated hemoglobin 5.7-5.9%. Participants were grouped according to MAFLD status, defined as hepatic fat fraction (HFF) ≥5% on MRI. We used oral minimal model on a frequently sampled 3 h 75 g-OGTT to estimate insulin sensitivity, insulin secretion, and pancreatic β-cell function. Fifty percent of participants had MAFLD. Median age (IQR) [57 (45-65) vs. 57 (44-63) yr] and sex (60% vs. 56% female) were comparable between groups. Post-OGTT glucose concentrations did not differ between groups, whereas post-OGTT insulin concentrations were higher in the MAFLD group (P < 0.03). Individuals with MAFLD exhibited lower insulin clearance, insulin sensitivity, and first-phase pancreatic β-cell function. In all individuals, increased insulin incremental area under the curve and decreased insulin clearance were associated with HFF after adjusting for age, sex, and BMI (P < 0.02). Among individuals with metabolic alterations, the presence of MAFLD was characterized mainly by post-OGTT hyperinsulinemia and reduced insulin clearance while exhibiting lower first phase β-cell function and insulin sensitivity. This suggests that MAFLD is linked with impaired insulin metabolism that may precede T2D.NEW & NOTEWORTHY Using an oral glucose tolerance test, we found hyperinsulinemia, lower insulin sensitivity, lower insulin clearance, and lower first-phase pancreatic β-cell function in individuals with MAFLD. This may explain part of the increased risk of incident type 2 diabetes in this population. These data also highlight implications of hyperinsulinemia and impaired insulin clearance in the progression of MAFLD to type 2 diabetes.

Pump-Less, Recirculating Organ-on-Chip (rOoC) Platform to Model the Metabolic Crosstalk between Islets and Liver

Type 2 diabetes mellitus (T2DM), obesity, and metabolic dysfunction-associated steatotic liver disease (MASLD) are epidemiologically correlated disorders with a worldwide growing prevalence. While the mechanisms leading to the onset and development of these conditions are not fully understood, predictive tissue representations for studying the coordinated interactions between central organs that regulate energy metabolism, particularly the liver and pancreatic islets, are needed. Here, a dual pump-less recirculating organ-on-chip platform that combines human pluripotent stem cell (sc)-derived sc-liver and sc-islet organoids is presented. The platform reproduces key aspects of the metabolic cross-talk between both organs, including glucose levels and selected hormones, and supports the viability and functionality of both sc-islet and sc-liver organoids while preserving a reduced release of pro-inflammatory cytokines. In a model of metabolic disruption in response to treatment with high lipids and fructose, sc-liver organoids exhibit hallmarks of steatosis and insulin resistance, while sc-islets produce pro-inflammatory cytokines on-chip. Finally, the platform reproduces known effects of anti-diabetic drugs on-chip. Taken together, the platform provides a basis for functional studies of obesity, T2DM, and MASLD on-chip, as well as for testing potential therapeutic interventions.

Insulin Resistance/Sensitivity Measures as Screening Indicators of Metabolic-Associated Fatty Liver Disease and Liver Fibrosis

BACKGROUND

Measures of insulin resistance (IR)/sensitivity (IS) are emerging tools to identify metabolic-associated fatty liver disease (MAFLD). However, the comprehensive assessment of the performance of various indicators is limited. Moreover, the utility of measures of IR/IS in detecting liver fibrosis remains unclear.

AIMS

To evaluate the predictive ability of seventeen IR/IS and two beta cell function indices to identify MAFLD and liver fibrosis.

METHODS

A cross-sectional study was conducted on individuals aged 25-75 years. Transient elastography was used to estimate liver stiffness and controlled attenuation parameter. The following measures were computed: homeostatic model assessment (HOMA/HOMA2) for IR, IS, and beta cell function; QUICKI; Bennett index; glucose/insulin; FIRI; McAuley index; Reynaud index; SPISE index; TyG; TyG-BMI; TyG-WC; TyG-WHtR; TG/HDL; and METS-IR. Subgroup analyses were performed according to age, gender, diabetes status, and body weight.

RESULTS

A total of 644 individuals were included in our analysis. MAFLD and significant liver fibrosis were detected in 320 (49.7%) and 80 (12.4%) of the participants, respectively. All measures of IR/IS identified MAFLD and liver fibrosis. However, TyG-WC, TyG-BMI, and TyG-WHtR were the top three indicators that identified MAFLD. Measures that include insulin level in their mathematical calculation, namely, Raynaud index, HOMA-IR, HOMA 2-IR, FIRI, and QUICKI had the best performance in identifying liver fibrosis in the entire population, as well as among the study subgroups.

CONCLUSIONS

TyG-WC, TyG-BMI, and TyG-WHtR were the best predictors of MAFLD. Insulin-based measures had better performances in the detection of advanced fibrosis. This was independent of age, gender, obesity, or diabetes status.

Mechanism of Action and Related Natural Regulators of Nrf2 in Nonalcoholic Fatty Liver Disease

With the acceleration of people's pace of life, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the world, which greatly threatens people's health and safety. Therefore, there is still an urgent need for higher-quality research and treatment in this area. Nuclear factor Red-2-related factor 2 (Nrf2), as a key transcription factor in the regulation of oxidative stress, plays an important role in inducing the body's antioxidant response. Although there are no approved drugs targeting Nrf2 to treat NAFLD so far, it is still of great significance to target Nrf2 to alleviate NAFLD. In recent years, studies have reported that many natural products treat NAFLD by acting on Nrf2 or Nrf2 pathways. This article reviews the role of Nrf2 in the pathogenesis of NAFLD and summarizes the currently reported natural products targeting Nrf2 or Nrf2 pathway for the treatment of NAFLD, which provides new ideas for the development of new NAFLD-related drugs.

The role of bariatric surgery on beta-cell function and insulin resistance in patients with nonalcoholic fatty liver disease and steatohepatitis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) are strongly associated with obesity, metabolic syndrome, and insulin resistance (IR).

OBJECTIVE

The aim of this study was to investigate the effects of metabolic surgery on pancreatic beta cell function and IR in patients with obesity and NAFLD.

SETTING

University Hospital, Germany.

METHODS

Liver biopsies were taken intraoperatively from 112 patients undergoing sleeve gastrectomy (n = 68) or Roux-en-Y gastric bypass (n = 44) and analyzed histologically for the presence of simple steatosis (NAFL) or NASH. Clinical and biochemical parameters were collected over up to 2 years. Beta cell function and IR were assessed using the homeostasis model assessment of beta-cell function (HOMA2-%B) and insulin resistance (HOMA2-IR) index.

RESULTS

NASH was present in 53.6% (n = 60) of the patients and NAFL in 25.9% (n = 29). Liver enzymes, adiponectin/leptin ratio, triglycerides, and HbA1C were improved at 6 months, 1, and 2 years after surgery. HOMA2-IR was significantly lower in patients without NAFLD while HOMA2-IR did not differ between patients with NAFL and/or NASH. HOMA2-%B was highest in the NAFLD group and lowest in patients with NASH. While there was no change in HOMA2-%B and HOMA2-IR in the No-NAFLD group, HOMA2-%B decreased and IR improved in the NAFL and NASH groups.

CONCLUSION

Insufficient compensatory beta-cell function may contribute to the progression from NAFL alongside with IR to NASH. Our findings suggest that bariatric surgery decreases IR while at the same time reducing compensatory insulin oversecretion. These results are associated with beneficial changes in adipose tissue function after bariatric surgery.

Non-alcoholic fatty liver disease and complications in type 1 and type 2 diabetes: A Mendelian randomization study

AIM

To investigate the potential causal relationship between non-alcoholic fatty liver disease (NAFLD) and complications in type 1 diabetes (T1D) and type 2 diabetes (T2D).

MATERIALS AND METHODS

Two-sample Mendelian randomization (MR) analysis was conducted to appraise after controlling for the confounding factors. Genetic instrument variables for NAFLD surrogated by chronically elevated serum alanine transferase were derived from a recent genome-wide association study. Diabetes-related complications, including diabetic ketoacidosis, nephropathy and retinopathy, were included as outcomes. Four complementary MR methods were used to test reliability.

RESULTS

Genetically instrumented NAFLD showed a suggestive causal association with ketoacidosis in T1D (odds ratio [OR]: 1.574; 95% confidence interval [CI]: 1.076, 2.302; P = .019; false discovery rate [FDR] = 0.096) and a significant causal association with early-stage kidney disease in T1D (OR: 1.249; 95% CI: 1.089, 1.432; P = 1.457 × 10^-3 , FDR = 0.015). Sensitivity analysis indicated low heterogeneity, low pleiotropy and high reliability of the causal estimates. However, the MR analyses failed to show a causal association between NAFLD and T1D retinopathy, T2D ketoacidosis, nephropathy and retinopathy.

CONCLUSIONS

This study supports a causal effect of genetically driven chronic serum alanine aminotransferase-associated NAFLD on early-stage kidney disease in T1D and a suggestive causal effect on ketoacidosis in T1D. However, MR studies did not provide enough evidence to suggest that NAFLD independently increases the risk of retinopathy in T1D and of ketoacidosis, nephropathy and retinopathy in T2D.

Low-Grade Hepatic Steatosis Is Associated with Long-term Remission of Type 2 Diabetes Independent of Type of Bariatric-Metabolic Surgery

BACKGROUND

Bariatric-metabolic surgery (BS) decreases the grade of steatosis, hepatic inflammation, and fibrosis in patients with severe obesity and non-alcoholic fatty liver disease (NAFLD). Mechanisms include substantial weight loss, but also simultaneous effects on glucose homeostasis. Therefore, we aimed to investigate the association between NAFLD and remission of type 2 diabetes (T2D) up to 8 years following different types of BS.

METHODS

In a retrospective cohort study including 107 patients with obesity and T2D at baseline, the association between biopsy-proven NAFLD defined as steatosis in > 5% of hepatocytes at the time of surgery and T2D remission up to 8 years following different surgical procedures was investigated. Univariate regression analysis was used to examine the association between NAFLD and remission of T2D.

RESULTS

Long-term remission of T2D was present in 56% of patients (n = 60). The presence of low-grade liver steatosis (grade 1) was associated with remission of T2D. Patients with a liver steatosis score ≥ 2 showed higher HbA1c levels at baseline. There were no significant differences in preoperative presence of lobular inflammation, hepatocyte ballooning, or fibrosis between patients who achieved T2D remission compared with those with no remission. Type of surgery did not affect remission of T2D.

CONCLUSION

Our results suggest that the presence of low-grade liver steatosis is associated with remission of T2D following sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). Therefore, BS should be considered at an early NAFLD stage in patients with T2D.