Impact of glucose tolerance on the severity of non-alcoholic steatohepatitis

Global epidemiology of type 2 diabetes in patients with NAFLD or MAFLD: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD) shares common pathophysiological mechanisms with type 2 diabetes, making them significant risk factors for type 2 diabetes. The present study aimed to assess the epidemiological feature of type 2 diabetes in patients with NAFLD or MAFLD at global levels.

METHODS

Published studies were searched for terms that included type 2 diabetes, and NAFLD or MAFLD using PubMed, EMBASE, MEDLINE, and Web of Science databases from their inception to December 2022. The pooled global and regional prevalence and incidence density of type 2 diabetes in patients with NAFLD or MAFLD were evaluated using random-effects meta-analysis. Potential sources of heterogeneity were investigated using stratified meta-analysis and meta-regression.

RESULTS

A total of 395 studies (6,878,568 participants with NAFLD; 1,172,637 participants with MAFLD) from 40 countries or areas were included in the meta-analysis. The pooled prevalence of type 2 diabetes among NAFLD or MAFLD patients was 28.3% (95% confidence interval 25.2-31.6%) and 26.2% (23.9-28.6%) globally. The incidence density of type 2 diabetes in NAFLD or MAFLD patients was 24.6 per 1000-person year (20.7 to 29.2) and 26.9 per 1000-person year (7.3 to 44.4), respectively.

CONCLUSIONS

The present study describes the global prevalence and incidence of type 2 diabetes in patients with NAFLD or MAFLD. The study findings serve as a valuable resource to assess the global clinical and economic impact of type 2 diabetes in patients with NAFLD or MAFLD.

Excessive gluconeogenesis causes the hepatic insulin resistance paradox and its sequelae

Background

Hepatic insulin signaling suppresses gluconeogenesis but promotes de novo lipid synthesis. Paradoxically, hepatic insulin resistance (HIR) enhances both gluconeogenesis and de novo lipid synthesis. Elucidation of the etiology of this paradox, which participates in the pathogenesis of non-alcoholic fatty liver disease (NAFLD), cardiovascular disease, the metabolic syndrome and hepatocellular carcinoma, has not been fully achieved.

Scope of review

This article briefly outlines the previously proposed hypotheses on the etiology of the HIR paradox. It then discusses literature consistent with an alternative hypothesis that excessive gluconeogenesis, the direct effect of HIR, is responsible for the aberrant lipogenesis. The mechanisms involved therein are explained, involving de novo synthesis of fructose and uric acid, promotion of glutamine anaplerosis, and induction of glucagon resistance. Thus, gluconeogenesis via lipogenesis promotes hepatic steatosis, a component of NAFLD, and dyslipidemia. Gluconeogenesis-centred mechanisms for the progression of NAFLD from simple steatosis to non-alcoholic steatohepatitis (NASH) and fibrosis are suggested. That NAFLD often precedes and predicts type 2 diabetes is explained by the ability of lipogenesis to cushion against blood glucose dysregulation in the earlier stages of NAFLD.

Major conclusions

HIR-induced excessive gluconeogenesis is a major cause of the HIR paradox and its sequelae. Such involvement of gluconeogenesis in lipid synthesis rationalizes the fact that several types of antidiabetic drugs ameliorate NAFLD. Thus, dietary, lifestyle and pharmacological targeting of HIR and hepatic gluconeogenesis may be a most viable approach for the prevention and management of the HIR-associated network of diseases.

Effect of sodium-glucose cotransporter 2 inhibitor in patients with non-alcoholic fatty liver disease and type 2 diabetes mellitus: a propensity score-matched analysis of real-world data

BACKGROUND

Although sodium-glucose cotransporter 2 inhibitors (SGLT2-Is) improve not only glycemic control but also liver inflammation and fatty changes in patients with non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM), its sustainability and effect on liver fibrosis have remained unclear. The current study aimed to clarify the effects of 48-week SGLT2-I therapy on liver inflammation, fatty changes, and fibrosis in NAFLD patients with T2DM.

METHODS

This study evaluated the effects of SGLT2-I on NAFLD, including liver fibrosis assessed via transient elastography, in 56 patients with NAFLD who received SGLT2-I for 48 weeks. Moreover, changes in each clinical parameter between patients receiving SGLT2-I (the SGLT2-I group) and those receiving other oral hypoglycemic agents (OHAs) (the non-SGLT2-I group) were compared, using 1:1 propensity score matching to adjust for baseline factors.

RESULTS

The SGLT2-I group exhibited a significant decrease in controlled attenuation parameter (312 dB/m at baseline to 280 dB/m at week 48) and liver stiffness measurement (9.1-6.7 kPa) (p < 0.001 for both). After propensity score matching (44 patients each in the SGLT2-I and non-SGLT2-I groups), no significant difference in HbA1c decrease was observed between the two groups. However, compared with the non-SGLT2-I group, the SGLT2-I group showed a significant decrease in body weight (p < 0.001), alanine aminotransferase (p = 0.02), uric acid (p < 0.001), and Fibrosis-4 (FIB-4) index (p = 0.01) at week 48. The improvement in FIB-4 index, defined as a ⩾10% decline from baseline at week 48, was 56.8% (25/44) in the SGLT2-I group and 20.5% (9/44) in the non-SGLT2-I group (p < 0.001).

CONCLUSION

SGLT2-Is improved not only glycemic control but also liver fatty infiltration and fibrosis in patients with NAFLD and T2DM, suggesting their possible superiority to other OHAs concerning these effects.

Predicting Nonalcoholic Fatty Liver Disease through a Panel of Plasma Biomarkers and MicroRNAs in Female West Virginia Population

(1) Background: Nonalcoholic fatty liver disease (NAFLD) is primarily characterized by the presence of fatty liver, hepatic inflammation and fibrogenesis eventually leading to nonalcoholic steatohepatitis (NASH) or cirrhosis. Obesity and diabetes are common risk factors associated with the development and progression of NAFLD, with one of the highest prevalence of these diseased conditions in the West Virginia population. Currently, the diagnosis of NAFLD is limited to radiologic studies and biopsies, which are not cost-effective and highly invasive. Hence, this study aimed to develop a panel and assess the progressive levels of circulatory biomarkers and miRNA expression in patients at risk for progression to NASH to allow early intervention strategies. (2) Methods: In total, 62 female patients were enrolled and blood samples were collected after 8–10 h of fasting. Computed tomography was performed on abdomen/pelvis following IV contrast administration. The patients were divided into the following groups: Healthy subjects with normal BMI and normal fasting blood glucose (Control, n = 20), Obese with high BMI and normal fasting blood glucose (Obese, n = 20) and Obese with high fasting blood glucose (Obese + DM, n = 22). Based on findings from CT, another subset was created from Obese + DM group with patients who showed signs of fatty liver infiltration (Obese + DM(FI), n = 10). ELISA was performed for measurement of plasma biomarkers and RT-PCR was performed for circulating miRNA expression. (3) Results: Our results show significantly increased levels of plasma IL-6, Leptin and FABP-1, while significantly decreased level of adiponectin in Obese, Obese + DM and Obese + DM(FI) group, as compared to healthy controls. The level of CK-18 was significantly increased in Obese + DM(FI) group as compared to control. Subsequently, the expression of miR-122, miR-34a, miR-375, miR-16 and miR-21 was significantly increased in Obese + DM and Obese + DM(FI) group as compared to healthy control. Our results also show distinct correlation of IL-6, FABP-1 and adiponectin levels with the expression of miRNAs in relation to the extent of NAFLD progression. (4) Conclusion: Our results support the clinical application of these biomarkers and miRNAs in monitoring the progression of NAFLD, suggesting a more advanced diagnostic potential of this panel than conventional methods. This panel may provide an appropriate method for early prognosis and management of NAFLD and subsequent adverse hepatic pathophysiology, potentially reducing the disease burden on the West Virginia population.

Hyperglycemia drives intestinal barrier dysfunction and risk for enteric infection

Obesity, diabetes, and related manifestations are associated with an enhanced, but poorly understood, risk for mucosal infection and systemic inflammation. Here, we show in mouse models of obesity and diabetes that hyperglycemia drives intestinal barrier permeability, through GLUT2-dependent transcriptional reprogramming of intestinal epithelial cells and alteration of tight and adherence junction integrity. Consequently, hyperglycemia-mediated barrier disruption leads to systemic influx of microbial products and enhanced dissemination of enteric infection. Treatment of hyperglycemia, intestinal epithelial-specific GLUT2 deletion, or inhibition of glucose metabolism restores barrier function and bacterial containment. In humans, systemic influx of intestinal microbiome products correlates with individualized glycemic control, indicated by glycated hemoglobin levels. Together, our results mechanistically link hyperglycemia and intestinal barrier function with systemic infectious and inflammatory consequences of obesity and diabetes.

Altered expression of MALAT1 lncRNA in nonalcoholic steatohepatitis fibrosis regulates CXCL5 in hepatic stellate cells

In the present study, we sought to identify long noncoding RNA (lncRNA) expression profiles in nonalcoholic steatohepatitis (NASH) patients with histologic evidence of lobular inflammation and advanced fibrosis. We profiled lncRNA expression using RNA-sequencing of wedge liver biopsies from 24 nonalcoholic fatty liver disease (NAFLD) patients with normal liver histology, 53 NAFLD patients with lobular inflammation, and 65 NAFLD patients with advanced fibrosis. Transcript profiling identified 4432 and 4057 differentially expressed lncRNAs in comparisons of normal tissue with lobular inflammation and fibrosis samples, respectively. Functional enrichment analysis revealed lncRNA participation in transforming growth factor beta 1 and tumor necrosis factor signaling, insulin resistance, and extracellular matrix maintenance. Several lncRNAs were highly expressed in fibrosis relative to normal tissue, including nuclear paraspeckle assembly transcript 1, hepatocellular carcinoma upregulated lncRNA, and metastasis-associated lung adenocarcinoma transcript 1 (MALAT1). Two potential target mRNAs, syndecan 4 (SDC4), and C-X-C motif chemokine ligand 5 (CXCL5) were identified for hepatocellular carcinoma upregulated lncRNA and MALAT1, respectively, but only CXCL5 showed differential expression among the different histologic classes. Knockdown of MALAT1 expression reduced CXCL5 transcript and protein levels by 50% and 30%, respectively, in HepG2 cells. The expression of MALAT1 and CXCL5 was upregulated in activated hepatic stellate (LX-2) cells compared to cells in the quiescent state, and MALAT1 expression was regulated by hyperglycemia and insulin in HepG2 cells, but only by insulin in LX-2 cells. Dysregulated lncRNA expression is associated with inflammation and fibrosis in NASH. Functionally relevant differences in MALAT1 expression may contribute to the development of fibrosis in NASH through mechanisms involving inflammatory chemokines.

Analysis of factors influencing glucose tolerance in Japanese patients with non-alcoholic fatty liver disease

BACKGROUND

While the association of the prevalence of non-alcoholic fatty liver disease (NAFLD) with impaired glucose metabolism has been reported, the factors influencing glucose tolerance in NAFLD remain to be clarified.

METHODS

Glucose tolerance of 131 Japanese patients diagnosed as NAFLD by histological findings of liver biopsy specimen was examined using 75 g-OGTT. According to Matteoni's classification, patients were divided to 4 groups [M1 ~ 4, M1, 2: non-alcoholic fatty liver (NAFL); and M3, 4: non-alcoholic steatohepatitis (NASH)]. Based on the OGTT data, insulinogenic index (IGI) and QUICKI were calculated as indices of insulin secretion and insulin sensitivity, respectively. Plasma glucose 120 min after glucose loading (G₁₂₀) was used as the index for glucose intolerance.

RESULTS

Stepwise multiple regression analysis using G₁₂₀ as a dependent variable and log_e-IGI, QUICKI, sex, BMI, age, NAFL/NASH as independent variables revealed that log_e-IGI (β = -0.595) and QUICKI (β = -0.323) are significant factors predicting glucose intolerance (R² = 0.403), indicating an important role of insulin secretion in glucose tolerance. These findings accord with glucose intolerance as high as 89.7% in patients with impaired insulin secretion defined by ≤43.2 pmol/mmol (40 μU/mg) IGI. Stepwise multiple regression analysis using QUICKI as a dependent variable and NAFL/NAFLD, sex, BMI, and age as independent variables revealed that BMI (β = -0.469) and NAFL/NAFLD (β = -0.204) are significant factors predicting insulin sensitivity (R² = 0.248).

CONCLUSION

Impairment of insulin secretion is the most important factor to predict glucose intolerance in NAFLD; severity of histological findings is associated with insulin sensitivity independent of adiposity in NAFLD.

Lessons from mouse models of high-fat diet-induced NAFLD

Nonalcoholic fatty liver disease (NAFLD) encompasses a clinicopathologic spectrum of diseases ranging from isolated hepatic steatosis to nonalcoholic steatohepatitis (NASH), the more aggressive form of fatty liver disease that may progress to cirrhosis and cirrhosis-related complications, including hepatocellular carcinoma. The prevalence of NAFLD, including NASH, is also increasing in parallel with the growing epidemics of obesity and diabetes. However, the causal relationships between obesity and/or diabetes and NASH or liver tumorigenesis have not yet been clearly elucidated. Animal models of NAFLD/NASH provide crucial information, not only for elucidating the pathogenesis of NAFLD/NASH, but also for examining therapeutic effects of various agents. A high-fat diet is widely used to produce hepatic steatosis and NASH in experimental animals. Several studies, including our own, have shown that long-term high-fat diet loading, which can induce obesity and insulin resistance, can also induce NASH and liver tumorigenesis in C57BL/6J mice. In this article, we discuss the pathophysiology of and treatment strategies for NAFLD and subsequent NAFLD-related complications such as NASH and liver tumorigenesis, mainly based on lessons learned from mouse models of high-fat diet-induced NAFLD/NASH.

Modification of a simple clinical scoring system as a diagnostic screening tool for non-alcoholic steatohepatitis in Japanese patients with non-alcoholic fatty liver disease

Aims/Introduction

We reinvestigated the clinical usefulness of the modified NAFIC scoring system, modified by changing the weightage assigned to the fasting serum insulin level based on the importance of hyperinsulinemia in the pathogenesis of non‐alcoholic steatohepatitis (NASH), in Japanese patients with non‐alcoholic fatty liver disease (NAFLD) who had undergone liver biopsy.

Materials and Methods

The NAFIC score is conventionally calculated as follows: serum ferritin ≥200 ng/mL (female) or ≥300 ng/mL (male), 1 point; serum fasting insulin ≥10 μU/mL, 1 point; and serum type IV collagen 7 s ≥5.0 ng/mL, 2 points. A total of 147 patients with NAFLD who had undergone liver biopsies were included in the estimation group. To validate the modified scoring system, 355 patients from nine hepatology centers in Japan were also enrolled.

Results

In the estimation group, 74 (50.3%) patients were histologically diagnosed as having NASH, whereas the remaining 73 (49.7%) were diagnosed as not having NASH. As the percentage of NASH patients increased not only among participants with serum insulin levels greater than 10 μU/mL, but also in those with serum levels greater than 15 μU/mL, we advocated use of the modified NAFIC score, as follows: serum fasting insulin 10–15 μU/mL, 1 point and ≥15 μU/mL, 2 points. The modified NAFIC score showed improved sensitivity and negative predictive value for the diagnosis of NASH. This finding was also confirmed in the validation group.

Conclusions

The modified NAFIC scoring system could be a clinically useful diagnostic screening tool for NASH.