Plasma Fibroblast Growth Factor 21 Is Associated With Severity of Nonalcoholic Steatohepatitis in Patients With Obesity and Type 2 Diabetes

FGF21 reverses MASH through coordinated actions on the CNS and liver

Metabolic dysfunction-associated steatotic liver disease (MASLD) and its progressive form, metabolic dysfunction-associated steatohepatitis (MASH), represent a growing public health burden with limited therapeutic options. Recent studies have revealed that fibroblast growth factor 21 (FGF21)-based analogs can significantly improve MASH, but the mechanisms for this effect are not well understood. Here, we demonstrate that the beneficial metabolic effects of FGF21 to reverse MASH are mediated through distinct mechanisms to independently lower hepatic triglyceride and cholesterol levels. Specifically, FGF21 signaling directly to glutamatergic neurons in the central nervous system (CNS) stimulates hepatic triglyceride reduction and reversal of fibrosis, whereas FGF21 signaling directly to hepatocytes is necessary and sufficient to reduce hepatic cholesterol levels in mice. Mechanistically, we show that FGF21 acts in the CNS to increase sympathetic nerve activity to the liver, which suppresses hepatic de novo lipogenesis. These results provide critical insights into a promising pharmacological target to treat MASH.

Effects of Intermittent Fasting on Liver Steatosis and Fibrosis, Serum FGF-21 and Autophagy Markers in Metabolic Dysfunction-Associated Fatty Liver Disease: A Randomized Controlled Trial

BACKGROUND

This randomized controlled study sought to determine the effect of intermittent fasting on anthropometric measurements, fibroblast growth factor (FGF)-21, and autophagy markers, as well as on hepatic steatosis and fibrosis levels in overweight or obese patients with metabolic dysfunction-associated fatty liver disease (MAFLD).

METHODS

Patients were randomly assigned into two groups: received a dietary treatment involving 22-25 kcal/kg/day of energy for 8 weeks and followed the same dietary intervention and a 16:8 pattern. The extent of hepatic steatosis and fibrosis was determined using transient elastography on a FibroScan® device. The controlled attenuation parameter (CAP) and liver stiffness measurement (LSM), determined by transient elastography, reflect hepatic steatosis and fibrosis, respectively. In duplicate, serum levels of FGF-21, Beclin-1, and ATG-5 were determined using enzyme-linked immunosorbent assay.

RESULTS

The study included 48 patients with a mean age of 48.2 ± 1.4 years (27 female and 21 male). Improvements in anthropometric measurement and CAP and LSM levels and a decrease in serum FGF-21 levels were found in both groups (p < 0.05). Changes in the CAP and FGF-21 levels were higher in the energy + time-restricted diet group (p < 0.05). Autophagy-related protein (ATG)-5 levels increased only in the energy + time-restricted diet group [(0.74 (0.46-1.29) ng/mL vs. 0.95 (0.73-1.32) ng/mL, p = 0.03].

CONCLUSIONS

Intermittent fasting was potentially practical in the management of MAFLD. In particular, changes in FGF-21 and ATG-5 levels indicate the potential of intermittent fasting to regulate metabolic processes and autophagy. However, methodological limitations should be taken into consideration when interpreting the study results.

Therapeutic Potential of Sotagliflozin in Animal Models of Non-alcoholic Fatty Liver Disease with and without Diabetes

Sotagliflozin, a dual SGLT1/2 inhibitor, enhances glucagon like peptide-1 (GLP-1) levels and GLP-1 receptor agonists are used to manage non-alcoholic fatty liver disease (NAFLD). Study investigates the effects of sotagliflozin on NAFLD, alone and combined with linagliptin, comparing outcomes in normoglycemic and hyperglycemic animal models.Obese fatty liver disease (FLD) model was induced by high-fat diet (HFD) feeding, while a diabetic non-alcoholic steatohepatitis (NASH) model was developed by administering a single dose of streptozotocin to neonatal mice, followed by HFD feeding post-weaning. At termination of the study, parameters including biochemical markers, inflammatory cytokines, hepatic lipid content, and histopathology were assessed.In NASH mice, sotagliflozin and linagliptin reduced hepatic triglycerides by 60% and 44%, respectively, and cholesterol by 46% and 49%. Their combination further decreased triglycerides by 68.5% and cholesterol by 83.9%. In FLD mice, sotagliflozin and linagliptin reduced triglycerides by 33% and 17%, respectively, and cholesterol by 46% and 21%. Combination treatment offered no benefit, reducing triglycerides by 38% and cholesterol by 27%. Both the treatments improved plasma fibroblast growth factor 21, hepatic interlukin-6, glucose tolerance, steatosis and mitigated fat pad weight, but their combination did not show additional benefit. However, combination treatment demonstrated added benefit in modulating NAFLD activity score, liver enzymes, glycogenated hepatic nuclei, plasma glucose and active GLP-1 levels.Study underscores sotagliflozin's potential to mitigate NAFLD and highlights the benefit of combining it with linagliptin in hyperglycemic NASH model, which showed limited efficacy in normoglycemic FLD mice.

Weight-adjusted waist circumference index with hepatic steatosis and fibrosis in adult females: a cross-sectional, nationally representative study (NHANES 2017-2020)

BACKGROUND

Obesity is detrimental to liver health. Weight-adjusted waist circumference (WWI) is a new indicator of obesity that is superior to body mass index (BMI) and waist circumference (WC) in predicting obesity. There are limited studies on the relationship between Metabolic Associated Fatty Liver Disease (MASLD) and WWI. Therefore, this study aimed to investigate the association between WWI, Controlled Attenuation Parameters (CAP), and Liver Stiffness Measurement (LSM), with special attention to gender differences.

METHODS

This cross-sectional study included participants from the 2017 to 2020 National Health and Nutrition Examination Survey (NHANES). The study used multiple linear regression models, smoothed curves, and threshold effects analyses to describe the relationships between variables. Multiple regression analyses were used to examine the associations between the four obesity indicators and CAP and LSM. Subject work characteristics (ROC) curves were used to assess the predictive value of WWI and other traditional obesity indicators for hepatic steatosis and liver fibrosis, and predictive power was assessed by area under the curve (AUC).

RESULTS

The study involved 6713 participants, including 3072 men (46%) and 3641 women (54%). The results showed that among female participants, higher WWI was associated with hepatic steatosis (OR = 1.71, 95% CI: 1.43, 2.04; P < 0.0001) and hepatic fibrosis (OR = 2.11, 95% CI: 1.58, 2.84; P < 0.0001). Smoothed curve fitting of WWI versus CAP showed a statistically significant positive correlation between WWI in male and female participants There was a statistically significant positive correlation with CAP for both male and female participants. The same significant non-linear relationship was found between WWI and LSM, with no significant difference between males and females. WWI was also a good predictor of hepatic steatosis compared to other obesity indicators and was more pronounced in male participants (AUC = 0.8224). Whereas in the comparison of WWI with LSM, wBMI was a better predictor in female participants (AUC = 0.7751).

CONCLUSIONS

Based on this study, WWI was significantly associated with the risk of hepatic steatosis and hepatic fibrosis in women, suggesting the potential of WWI as a screening tool. Due to the cross-sectional design, causality cannot be inferred. Longitudinal studies are needed to validate our findings.

FGF21 Signaling Exerts Antifibrotic Properties during Pulmonary Fibrosis

Rationale: Idiopathic pulmonary fibrosis (IPF) is a lethal disease with limited therapeutic options. FGF21 (fibroblast growth factor 21), an endocrine fibroblast growth factor that acts through the FGFR1 (fibroblast growth factor receptor 1)/KLB (β-Klotho) pathway, mitigates liver fibrosis. Objectives: We hypothesized that FGF21 could exert antifibrotic properties in the lung. Methods: The concentrations of FGF21 and KLB in the plasma of patients with IPF and control subjects were assessed. Pulmonary fibrosis development was assessed in Fgf21-deficient mice compared with wild-type littermates, at Day 14 (D14) after the intratracheal injection of bleomycin. We determined the effect of repeated subcutaneous injections of a PEGylated FGF21 analog at D7, D10, D14, and D17 after bleomycin on the development of pulmonary fibrosis. Mice were killed at D21. The effects of FGF21, alone or with KLB, on apoptosis in murine lung epithelial 15 cells and on the phenotype of human lung fibroblasts were assessed in vitro. Measurements and Main Results: In the plasma of patients with IPF, FGF21 concentrations were increased, while KLB concentrations were decreased. Fgf21-deficient mice showed increased sensitivity to bleomycin in comparison with their wild-type littermates. Treatment with PEGylated FGF21 mitigated lung fibrogenesis, as evidenced by a lower injury score and decreased fibrosis markers and profibrotic mediator expression compared with the control group receiving the diluent. In murine lung epithelial 15 cells, stimulation with FGF21 and KLB inhibited apoptosis, through the decrease of BAX and BIM. Fibroblastic phenotype remained unaltered. Conclusions: Our data indicate a possible antifibrotic effect of FGF21 in the lung achieved through the inhibition of alveolar type 2 cell apoptosis.

Improvement of β-Cell Function After Switching From DPP-4 Inhibitors to Oral Semaglutide: SWITCH-SEMA2 Post Hoc Analysis

CONTEXT

Whether continuation of dipeptidyl peptidase-4 inhibitors (DPP-4is) or switching to oral semaglutide is more beneficial for β-cell function is unclear.

OBJECTIVE

To assess the efficacy of switching from DPP-4is to oral semaglutide for β-cell function compared with DPP-4i continuation.

METHODS

Post hoc analysis of SWITCH-SEMA 2, a multicenter prospective randomized controlled trial on the switch to oral semaglutide vs DPP-4i continuation without dose adjustment for 24 weeks in subjects with type 2 diabetes treated with DPP-4is, was conducted. Changes in markers for glucose metabolism, including homeostatic model assessment (HOMA2) scores and disposition index (DI), were compared between the groups.

RESULTS

A total of 146 subjects (semaglutide group, 69; DPP-4i group, 77) were analyzed. In the semaglutide group, glycemic control, liver enzyme deviations, and lipid profiles improved after 24 weeks. Regarding indices for β-cell function, changes in HOMA2-β as well as DI, reflecting the ability of β-cells to compensate for insulin resistance, were significantly higher in the semaglutide group compared with the DPP-4i group (mean change, +10.4 vs +0.6 in HOMA2-β [P = .001] and +0.09 vs 0.0 in DI [P < .001]). Improvement in DI in the semaglutide group was correlated significantly to changes in body mass index (BMI), HbA1c, and fatty liver index reflecting liver steatosis. Multiple linear regression analysis revealed that dose of semaglutide (≥ 7 mg/day), reduction in fatty liver index, and metformin nonuse were independently associated with improvement of DI.

CONCLUSION

Switching to oral semaglutide ameliorated β-cell function compared with DPP-4is, presumably via tissue-to-tissue crosstalk between liver and β-cells.

Effects of exercise intensity and diet on cardiac tissue structure and FGF21/β-Klotho signaling in type 2 diabetic mice: a comparative study of HFD and HFD + STZ induced type 2 diabetes models in mice

BACKGROUND

Structural heart disease is one of the leading causes of death in people with type 2 diabetes (T2D), which is not known to have an effect on exercise training. The aim of this study was to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on heart tissue structure, the serum level of FGF21 and the heart tissue level of β-Klotho, an FGF21 coreceptor, in HFD and HFD + STZ-induced diabetic mice.

METHODS

Thirty-six male C57BL/6J mice were divided into high-fat diet (HFD) and normal chow diet (ND) groups. After 20 weeks of diet, the HFD mice were divided into HFD and HFD + STZ groups, and the latter group was injected with STZ. Then, the mice in the ND, HFD and HFD + STZ groups were divided into three subgroups of control (C), HIIT and MICT, and mice were placed in one of nine groups ND-C, ND-HIIT, ND-MICT, HFD-C, HFD-HIIT, HFD-MICT, HFD + STZ-C, HFD + STZ-HIIT, and HFD + STZ-MICT. The mice in the exercise training (ET) groups were run on a treadmill for eight weeks. Finally, the tissue and serum samples were collected and analyzed by two-way ANOVA.

RESULTS

Statistical analyses showed that the main effect of diabetes inducing model (DIM) was significant for all variables (p < 0.05), except vascular density (p = 0.055); the main effect of ET type on fasting blood glucose and FGF21 was significant (p < 0.001); and the interaction was significant for fasting blood glucose, heart weight and FGF21 (p < 0.001). Post hoc and subgroup analysis showed a superior effect of MICT over HIIT in decreasing fasting blood glucose and serum level of FGF21 (p < 0.001). Additionally, the results of the myocardial tissue qualitative analyses differed between the diabetic mouse models and the ET groups.

CONCLUSIONS

In a mouse model, type 2 diabetes can negatively affect heart tissue structure and FGF21 signaling in cardiac tissue, and both HIIT and MICT can prevent this effect. However, MICT likely more effective that HIIT in reducing circulating FGF21.

Celastrus orbiculatus Thunb. extracts and celastrol alleviate NAFLD by preserving mitochondrial function through activating the FGF21/AMPK/PGC-1α pathway

Objective

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver disease globally, characterized by the accumulation of lipids, oxidative stress, and mitochondrial dysfunction in the liver. Celastrus orbiculatus Thunb. (COT) and its active compound celastrol (CEL) have demonstrated antioxidant and anti-inflammatory properties. Our prior research has shown the beneficial effects of COT in mitigating NAFLD induced by a high-fat diet (HFD) in guinea pigs by reducing hepatic lipid levels and inhibiting oxidative stress. This study further assessed the effects of COT on NAFLD and explored its underlying mitochondria-related mechanisms.

Methods

COT extract or CEL was administered as an intervention in C57BL/6J mice fed a HFD or in HepG2 cells treated with sodium oleate. Oral glucose tolerance test, biochemical parameters including liver enzymes, blood lipid, and pro-inflammatory factors, and steatosis were evaluated. Meanwhile, mitochondrial ultrastructure and indicators related to oxidative stress were tested. Furthermore, regulators of mitochondrial function were measured using RT-qPCR and Western blot.

Results

The findings demonstrated significant reductions in hepatic steatosis, oxidative stress, and inflammation associated with NAFLD in both experimental models following treatment with COT extract or CEL. Additionally, improvements were observed in mitochondrial structure, ATP content, and ATPase activity. This improvement can be attributed to the significant upregulation of mRNA and protein expression levels of key regulators including FGF21, AMPK, PGC-1α, PPARγ, and SIRT3.

Conclusion

These findings suggest that COT may enhance mitochondrial function by activating the FGF21/AMPK/PGC-1α signaling pathway to mitigate NAFLD, which indicated that COT has the potential to target mitochondria and serve as a novel therapeutic option for NAFLD.

Connecting the Dots: FGF21 as a Potential Link between Obesity and Cardiovascular Health in Acute Coronary Syndrome Patients

Fibroblast growth factor 21 (FGF21) is a hormone involved in regulating the metabolism, energy balance, and glucose homeostasis, with new studies demonstrating its beneficial effects on the heart. This study investigated the relationship between FGF21 levels and clinical, biochemical, and echocardiographic parameters in patients with acute coronary syndromes (ACSs). This study included 80 patients diagnosed with ACS between May and July 2023, categorized into four groups based on body mass index (BMI): Group 1 (BMI 18.5-24.9 kg/m2), Group 2 (BMI 25-29.9 kg/m2), Group 3 (BMI 30-34.9 kg/m2), and Group 4 (BMI ≥ 35 kg/m2). Serum FGF21 levels were measured by ELISA (Abclonal Catalog NO.: RK00084). Serum FGF21 levels were quantifiable in 55 samples (mean ± SD: 342.42 ± 430.17 pg/mL). Group-specific mean FGF21 levels were 238.98 pg/mL ± SD in Group 1 (n = 14), 296.78 pg/mL ± SD in Group 2 (n = 13), 373.77 pg/mL ± SD in Group 3 (n = 12), and 449.94 pg/mL ± SD in Group 4 (n = 16), with no statistically significant differences between groups (p = 0.47). Based on ACS diagnoses, mean FGF21 levels were 245.72 pg/mL for STEMI (n = 21), 257.89 pg/mL for NSTEMI (n = 9), and 456.28 pg/mL for unstable angina (n = 25), with no significant differences observed between these diagnostic categories. Significant correlations were identified between FGF21 levels and BMI, diastolic blood pressure, and serum chloride. Regression analyses revealed correlations with uric acid, chloride, and creatinine kinase MB. This study highlights the complex interplay between FGF21, BMI, and acute coronary syndromes. While no significant differences were found in FGF21 levels between the different BMI and ACS diagnostic groups, correlations with clinical and biochemical parameters suggest a multifaceted role of FGF21 in cardiovascular health. Further research with a larger sample size is warranted to elucidate these relationships.

A long-acting FGF21 attenuates metabolic dysfunction-associated steatohepatitis-related fibrosis by modulating NR4A1-mediated Ly6C phenotypic switch in macrophages

BACKGROUND AND PURPOSE

Because of the absence of effective therapies for metabolic dysfunction-associated steatohepatitis (MASH), there is a rising interest in fibroblast growth factor 21 (FGF21) analogues due to their potential anti-fibrotic activities in MASH treatment. PsTag-FGF21, a long-acting FGF21 analogue, has demonstrated promising therapeutic effects in several MASH mouse models. However, its efficacy and mechanism against MASH-related fibrosis remain less well defined, compared with the specific mechanisms through which FGF21 improves glucose and lipid metabolism.

EXPERIMENTAL APPROACH

The effectiveness of PsTag-FGF21 was evaluated in two MASH-fibrosis models. Co-culture systems involving macrophages and hepatic stellate cells (HSCs) were employed for further assessment. Hepatic macrophages were selectively depleted by administering liposome-encapsulated clodronate via tail vein injections. RNA sequencing and cytokine profiling were conducted to identify key factors involved in macrophage-HSC crosstalk.

KEY RESULTS

We first demonstrated the significant attenuation of hepatic fibrosis by PsTag-FGF21 in two MASH-fibrosis models. Furthermore, we highlighted the crucial role of macrophage phenotypic switch in PsTag-FGF21-induced HSC deactivation. FGF21 was demonstrated to regulate macrophages in a PsTag-FGF21-like manner. NR4A1, a nuclear factor which is notably down-regulated in human livers with MASH, was identified as a mediator responsible for PsTag-FGF21-induced phenotypic switch. Transcriptional control over insulin-like growth factor 1, a crucial factor in macrophage-HSC crosstalk, was exerted by the intrinsically disordered region domain of NR4A1.

CONCLUSION AND IMPLICATIONS

Our results have elucidated the previously unclear mechanisms through which PsTag-FGF21 treats MASH-related fibrosis and identified NR4A1 as a potential therapeutic target for fibrosis.

The endocrine FGFs axis: A systemic anti-fibrotic response that could prevent pulmonary fibrogenesis?

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease for which therapeutic options are limited, with an unmet need to identify new therapeutic targets. IPF is thought to be the consequence of repeated microlesions of the alveolar epithelium, leading to aberrant epithelial-mesenchymal communication and the accumulation of extracellular matrix proteins. The reactivation of developmental pathways, such as Fibroblast Growth Factors (FGFs), is a well-described mechanism during lung fibrogenesis. Secreted FGFs with local paracrine effects can either exert an anti-fibrotic or a pro-fibrotic action during this pathological process through their FGF receptors (FGFRs) and heparan sulfate residues as co-receptors. Among FGFs, endocrine FGFs (FGF29, FGF21, and FGF23) play a central role in the control of metabolism and tissue homeostasis. They are characterized by a low affinity for heparan sulfate, present in the cell vicinity, allowing them to have endocrine activity. Nevertheless, their interaction with FGFRs requires the presence of mandatory co-receptors, alpha and beta Klotho proteins (KLA and KLB). Endocrine FGFs are of growing interest for their anti-fibrotic action during liver, kidney, or myocardial fibrosis. Innovative therapies based on FGF19 or FGF21 analogs are currently being studied in humans during liver fibrosis. Recent data report a similar anti-fibrotic action of endocrine FGFs in the lung, suggesting a systemic regulation of the pulmonary fibrotic process. In this review, we summarize the current knowledge on the protective effect of endocrine FGFs during the fibrotic processes, with a focus on pulmonary fibrosis.

Glucagon augments the secretion of FGF21 and GDF15 in MASLD by indirect mechanisms

INTRODUCTION

Glucagon receptor agonism is currently explored for the treatment of obesity and metabolic dysfunction-associated steatotic liver disease (MASLD). The metabolic effects of glucagon receptor agonism may in part be mediated by increases in circulating levels of Fibroblast Growth Factor 21 (FGF21) and Growth Differentiation Factor 15 (GDF15). The effect of glucagon agonism on FGF21 and GDF15 levels remains uncertain, especially in the context of elevated insulin levels commonly observed in metabolic diseases.

METHODS

We investigated the effect of a single bolus of glucagon and a continuous infusion of glucagon on plasma concentrations of FGF21 and GDF15 in conditions of endogenous low or high insulin levels. The studies included individuals with overweight with and without MASLD, healthy controls (CON) and individuals with type 1 diabetes (T1D). The direct effect of glucagon on FGF21 and GDF15 was evaluated using our in-house developed isolated perfused mouse liver model.

RESULTS

FGF21 and GDF15 correlated with plasma levels of insulin, but not glucagon, and their secretion was highly increased in MASLD compared with CON and T1D. Furthermore, FGF21 levels in individuals with overweight with or without MASLD did not increase after glucagon stimulation when insulin levels were kept constant. FGF21 and GDF15 levels were unaffected by direct stimulation with glucagon in the isolated perfused mouse liver.

CONCLUSION

The glucagon-induced secretion of FGF21 and GDF15 is augmented in MASLD and may depend on insulin. Thus, glucagon receptor agonism may augment its metabolic benefits in patients with MASLD through enhanced secretion of FGF21 and GDF15.

IFNγ-IL12 axis regulates intercellular crosstalk in metabolic dysfunction-associated steatotic liver disease

Obesity is a major cause of metabolic dysfunction-associated steatohepatitis (MASH) and is characterized by inflammation and insulin resistance. Interferon-γ (IFNγ) is a pro-inflammatory cytokine elevated in obesity and modulating macrophage functions. Here, we show that male mice with loss of IFNγ signaling in myeloid cells (Lyz-IFNγR2-/-) are protected from diet-induced insulin resistance despite fatty liver. Obesity-mediated liver inflammation is also attenuated with reduced interleukin (IL)-12, a cytokine primarily released by macrophages, and IL-12 treatment in vivo causes insulin resistance by impairing hepatic insulin signaling. Following MASH diets, Lyz-IFNγR2-/- mice are rescued from developing liver fibrosis, which is associated with reduced fibroblast growth factor (FGF) 21 levels. These results indicate critical roles for IFNγ signaling in macrophages and their release of IL-12 in modulating obesity-mediated insulin resistance and fatty liver progression to MASH. In this work, we identify the IFNγ-IL12 axis in regulating intercellular crosstalk in the liver and as potential therapeutic targets to treat MASH.

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.

FGF21-mediated autophagy: Remodeling the homeostasis in response to stress in liver diseases

Liver diseases are worldwide problems closely associated with various stresses, such as endoplasmic reticulum stress. The exact interplay between stress and liver diseases remains unclear. Autophagy plays an essential role in maintaining homeostasis, and recent studies indicate tight crosstalk between stress and autophagy in liver diseases. Once the balance between damage and autophagy is broken, autophagy can no longer resist injury or maintain homeostasis. In recent years, FGF21 (fibroblast growth factor 21)-induced autophagy has attracted much attention. FGF21 is regarded as a stress hormone and can be up-regulated by an abundance of signaling pathways in response to stress. Also, increased FGF21 activates autophagy by a complicated signaling network in which mTOR plays a pivotal role. This review summarizes the mechanism of FGF21-mediated autophagy and its derived application in the defense of stress in liver diseases and offers a glimpse into its promising prospect in future clinical practice.

The role of FGF21 in the interplay between obesity and non-alcoholic fatty liver disease: a narrative review

Obesity poses a significant and escalating challenge in contemporary society, increasing the risk of developing various metabolic disorders such as dyslipidemia, cardiovascular diseases, non-alcoholic fatty liver disease (NAFLD), type 2 diabetes, and certain types of cancer. The current array of therapeutic interventions for obesity remains insufficient, prompting a pressing demand for novel and more effective treatments. In response, scientific attention has turned to the fibroblast growth factor 21 (FGF21) due to its remarkable and diverse impacts on lipid, carbohydrate, and energy metabolism. This comprehensive review aims to delve into the multifaceted aspects of FGF21, encompassing its discovery, synthesis, functional roles, and potential as a biomarker and therapeutic agent, with a specific focus on its implications for NAFLD.

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.

Letter: Severe underweight and sarcopenia in decompensated cirrhosis are associated with high FGF21 levels-authors' reply

This article is linked to Alkhouri et al papers. To view these articles, visit https://doi.org/10.1111/apt.17709 and https://doi.org/10.1111/apt.17881

Hepatokine-based identification of fibrotic NASH and improved risk stratification in a multicentre cohort of NAFLD patients

BACKGROUND AND AIMS

The presence of significant liver fibrosis associated with non-alcoholic steatohepatitis (NASH) is regarded as the major prognostic factor in non-alcoholic fatty liver disease (NAFLD). Identification of patients at risk for NASH with significant fibrosis is therefore important. Although the established fibrosis score FIB-4 is suitable to exclude advanced fibrosis, it does not allow the prediction of significant fibrosis in NAFLD patients. We therefore evaluated whether the hepatokine fibroblast growth factor 21 (FGF21), a regulator of glucose and lipid metabolism, might identify 'at-risk NASH' in NAFLD.

METHODS

FGF21 levels were assessed by enzyme-linked immunosorbent assay in sera from an exploration (n = 137) and a validation (n = 88) cohort of biopsy-proven NAFLD patients with different disease activity and fibrosis stages. In addition, we evaluated whether the use of FGF21 could improve risk stratification in NAFLD patients with low (<1.3) or intermediate (1.3-2.67) FIB-4.

RESULTS

FGF21 levels could significantly discriminate between NASH and non-alcoholic fatty liver (NAFL) patients, even in the absence of diabetes. Moreover, patients with NASH and fibrosis ≥F2 showed significantly higher FGF21 levels compared to NAFLD patients without significant fibrosis. Significantly elevated FGF21 levels could even be detected in NAFLD patients with NASH and significant fibrosis despite low or intermediate FIB-4.

CONCLUSION

Serological FGF21 detection might allow the identification of NAFLD patients at risk and improves patient stratification in combination with FIB-4.

Global prevalence of non-alcoholic fatty liver disease in type 2 diabetes mellitus: an updated systematic review and meta-analysis

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease, with type 2 diabetes mellitus (T2DM) as a major predictor. Insulin resistance and chronic inflammation are key pathways in the pathogenesis of T2DM leading to NAFLD and vice versa, with the synergistic effect of NAFLD and T2DM increasing morbidity and mortality risks. This meta-analysis aims to quantify the prevalence of NAFLD and the prevalence of clinically significant and advanced fibrosis in people with T2DM.

METHODS

MEDLINE and Embase databases were searched from inception until 13 February 2023. The primary outcomes were the prevalence of NAFLD, non-alcoholic steatohepatitis (NASH) and fibrosis in people with T2DM. A generalised linear mixed model with Clopper-Pearson intervals was used for the analysis of proportions with sensitivity analysis conducted to explore heterogeneity between studies.

RESULTS

156 studies met the inclusion criteria, and a pooled analysis of 1 832 125 patients determined that the prevalence rates of NAFLD and NASH in T2DM were 65.04% (95% CI 61.79% to 68.15%, I2=99.90%) and 31.55% (95% CI 17.12% to 50.70%, I2=97.70%), respectively. 35.54% (95% CI 19.56% to 55.56%, I2=100.00%) of individuals with T2DM with NAFLD had clinically significant fibrosis (F2-F4), while 14.95% (95% CI 11.03% to 19.95%, I2=99.00%) had advanced fibrosis (F3-F4).

CONCLUSION

This study determined a high prevalence of NAFLD, NASH and fibrosis in people with T2DM. Increased efforts are required to prevent T2DM to combat the rising burden of NAFLD.

PROSPERO REGISTRATION NUMBER

CRD42022360251.

Pegozafermin Is a Potential Master Therapeutic Regulator in Metabolic Disorders: A Review

Pegozafermin (PGZ), a novel glycopegylated version of human fibroblast growth factor 21 (FGF21), has demonstrated potential for addressing metabolic comorbidities, including severe hypertriglyceridemia, insulin resistance, nonalcoholic fatty liver disease, and obesity. FGF21 is a naturally occurring peptide hormone primarily produced by the liver, with a half-life of 0.5 to 2 hours. It can influence metabolic processes through endocrine cellular effects. FGF21 receptors are found in the liver, adipose, skeletal muscles, and pancreatic tissues. Those receptors rely on the beta klotho (KLB) coreceptors, a transmembrane protein, to activate the FGF21 signaling pathway and FGF21's associated transcription factors. PGZ, through its extended half-life of 55 to 100 hours, has evidenced significant improvements in metabolic functions. Its mechanism of action includes promoting adiponectin levels, enhancing insulin sensitivity, increasing triglyceride uptake, and reducing de novo lipogenesis. This emerging pharmaceutical compound has shown promise in treating liver fibrosis and inflammation linked to nonalcoholic steatohepatitis. The ENTRIGUE trial, a phase 2 clinical trial of PGZ, has demonstrated a 57% reduction in triglyceride level compared to placebo; a 45% reduction in liver hepatic steatosis; improved insulin sensitivity; reductions in nonhigh-density lipoprotein-cholesterol; and reductions in apolipoprotein B-100.

Efruxifermin, an investigational treatment for fibrotic or cirrhotic non-alcoholic steatohepatitis (NASH)

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease and strongly associated with metabolic disorders: obesity, type 2 diabetes (T2D), cardiovascular disease. Persistent metabolic injury results in inflammatory processes leading to nonalcoholic steatohepatitis (NASH), liver fibrosis and ultimately cirrhosis. To date, no pharmacologic agent is approved for the treatment of NASH. Fibroblast growth factor 21 (FGF21) agonism has been linked to beneficial metabolic effects ameliorating obesity, steatosis and insulin resistance, supporting its potential as a therapeutic target in NAFLD.

AREAS COVERED

Efruxifermin (EFX, also AKR-001 or AMG876) is an engineered Fc-FGF21 fusion protein with an optimized pharmacokinetic and pharmacodynamic profile, which is currently tested in several phase 2 clinical trials for the treatment of NASH, fibrosis and compensated liver cirrhosis. EFX improved metabolic disturbances including glycemic control, showed favorable safety and tolerability, and demonstrated antifibrotic efficacy according to FDA requirements for phase 3 trials.

EXPERT OPINION

While some other FGF-21 agonists (e.g. pegbelfermin) are currently not further investigated, available evidence supports the development of EFX as a promising anti-NASH drug in fibrotic and cirrhotic populations. However, antifibrotic efficacy, long-term safety and benefits (i.e. cardiovascular risk, decompensation events, disease progression, liver transplantation, mortality) remain to be determined.

The potential effect of metformin on fibroblast growth factor 21 in type 2 diabetes mellitus (T2DM)

Fibroblast growth factor 21 (FGF21) is a peptide hormone mainly synthesized and released from the liver. FGF21 acts on FGF21 receptors (FGFRs) and β-Klotho, which is a transmembrane co-receptor. In type 2 diabetes mellitus (T2DM), inflammatory disorders stimulate the release of FGF21 to overcome insulin resistance (IR). FGF21 improves insulin sensitivity and glucose homeostasis. Metformin which is used in the management of T2DM may increase FGF21 expression. Accordingly, the objective of this review was to clarify the metformin effect on FGF21 in T2DM. FGF21 level and expression of FGF2Rs are dysregulated in T2DM due to the development of FGF21 resistance. Metformin stimulates the hepatic expression of FGF21/FGF2Rs by different signaling pathways. Besides, metformin improves the expression of β-Klotho which improves FGF21 sensitivity. In conclusion, metformin advances FGF21 signaling and decreases FGF21 resistance in T2DM, and this might be an innovative mechanism for metformin in the enhancement of glucose homeostasis and metabolic disorders in T2DM patients.

Short-Term Decreasing and Increasing Dietary BCAA Have Similar, but Not Identical Effects on Lipid and Glucose Metabolism in Lean Mice

Branched-chain amino acids (BCAA) showed multiple functions in glycolipid metabolism and protein synthesis. However, the impacts on the metabolic health of low or high dietary BCAA remain controversial due to the various experimental conditions. Gradient levels of BCAA were supplemented in lean mice for four weeks: 0BCAA (without BCAA), 1/2BCAA (half BCAA), 1BCAA (regular BCAA), and 2BCAA (double BCAA). The results showed that the diet without BCAA caused energy metabolic disorders, immune defects, weight loss, hyperinsulinemia, and hyperleptinemia. 1/2BCAA and 2BCAA diets reduced body fat percentage, but 1/2 BCAA also decreased muscle mass. 1/2BCAA and 2BCAA groups improved lipid and glucose metabolism by affecting metabolic genes. Meanwhile, significant differences between low and high dietary BCAA were observed. The results of this study provide evidence and reference for the controversy about dietary BCAA levels, which indicates that the main difference between low and high BCAA dietary levels may present in the longer term.

Albumin-fused long-acting FGF21 analogue for the treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) currently affects about 25% of the world's population, and the numbers continue to rise as the number of obese patients increases. However, there are currently no approved treatments for NAFLD. This study reports on the evaluation of the therapeutic effect of a recombinant human serum albumin-fibroblast growth factor 21 analogue fusion protein (HSA-FGF21) on the pathology of NAFLD that was induced by using two high-fat diets (HFD), HFD-60 and STHD-01. The HFD-60-induced NAFLD model mice with obesity, insulin resistance, dyslipidemia and hepatic lipid accumulation were treated with HSA-FGF21 three times per week for 4 weeks starting at 12 weeks after the HFD-60 feeding. The administration of HSA-FGF21 suppressed the increased body weight, improved hyperglycemia, hyperinsulinemia, and showed a decreased accumulation of plasma lipid and hepatic lipid levels. The elevation of C16:0, C18:0 and C18:1 fatty acids in the liver that were observed in the HFD-60 group was recovered by the HSA-FGF21 administration. The increased expression levels of the hepatic fatty acid uptake receptor (CD36) and fatty acid synthase (SREBP-1c, FAS, SCD-1, Elovl6) were also suppressed. In adipose tissue, HSA-FGF21 caused an improved adipocyte hypertrophy, a decrease in the levels of inflammatory cytokines and induced the expression of adiponectin and thermogenic factors. The administration of HSA-FGF21 to the STHD-01-induced NAFLD model mice resulted in suppressed plasma ALT and AST levels, oxidative stress, inflammatory cell infiltration and fibrosis. Together, HSA-FGF21 has some potential for use as a therapeutic agent for the treatment of NAFLD.

Fibroblast Growth Factor-21 as a Potential Therapeutic Target of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a highly prevalent disease without any approved treatment to-date despite intensive research efforts by researchers and pharmaceutical industry. Fibroblast growth factor (FGF)-21 has been gaining increasing attention as a possible contributing factor and thus therapeutic target for obesity-related metabolic disorders, including NAFLD, mainly due to its effects on lipid and carbohydrate metabolism. Most animal and human observational studies have shown higher FGF-21 concentrations in NAFLD than non-NAFLD, implying that FGF-21 may be increased to counteract hepatic steatosis and inflammation. However, although Mendelian Randomization studies have revealed that variations of FGF-21 levels within the physiological range may have effects in hyperlipidemia and possibly nonalcoholic steatohepatitis, they also indicate that FGF-21, in physiological concentrations, may fail to reverse NAFLD and may not be able to control obesity and other diseases, indicating a state of FGF-21 resistance or insensitivity that could not respond to administration of FGF-21 in supraphysiological concentrations. Interventional studies with FGF-21 analogs (eg, pegbelfermin, efruxifermin, BOS-580) in humans have provided some favorable results in Phase 1 and Phase 2 studies. However, the definite effect of FGF-21 on NAFLD may be clarified after the completion of the ongoing clinical trials with paired liver biopsies and histological endpoints. The aim of this review is to critically summarize experimental and clinical data of FGF-21 in NAFLD, in an attempt to highlight existing knowledge and areas of uncertainty, and subsequently, to focus on the potential therapeutic effects of FGF-21 and its analogs in NAFLD.

FGF21 protects against hepatic lipotoxicity and macrophage activation to attenuate fibrogenesis in nonalcoholic steatohepatitis

Analogues of the hepatokine fibroblast growth factor 21 (FGF21) are in clinical development for type 2 diabetes and nonalcoholic steatohepatitis (NASH) treatment. Although their glucose-lowering and insulin-sensitizing effects have been largely unraveled, the mechanisms by which they alleviate liver injury have only been scarcely addressed. Here, we aimed to unveil the mechanisms underlying the protective effects of FGF21 on NASH using APOE*3-Leiden.CETP mice, a well-established model for human-like metabolic diseases. Liver-specific FGF21 overexpression was achieved in mice, followed by administration of a high-fat high-cholesterol diet for 23 weeks. FGF21 prevented hepatic lipotoxicity, accompanied by activation of thermogenic tissues and attenuation of adipose tissue inflammation, improvement of hyperglycemia and hypertriglyceridemia, and upregulation of hepatic programs involved in fatty acid oxidation and cholesterol removal. Furthermore, FGF21 inhibited hepatic inflammation, as evidenced by reduced Kupffer cell (KC) activation, diminished monocyte infiltration, and lowered accumulation of monocyte-derived macrophages. Moreover, FGF21 decreased lipid- and scar-associated macrophages, which correlated with less hepatic fibrosis as demonstrated by reduced collagen accumulation. Collectively, hepatic FGF21 overexpression limits hepatic lipotoxicity, inflammation, and fibrogenesis. Mechanistically, FGF21 blocks hepatic lipid influx and accumulation through combined endocrine and autocrine signaling, respectively, which prevents KC activation and lowers the presence of lipid- and scar-associated macrophages to inhibit fibrogenesis.

Targeting FGF21 in cardiovascular and metabolic diseases: from mechanism to medicine

Cardiovascular and metabolic disease (CVMD) is becoming increasingly prevalent in developed and developing countries with high morbidity and mortality. In recent years, fibroblast growth factor 21 (FGF21) has attracted intensive research interest due to its purported role as a potential biomarker and critical player in CVMDs, including atherosclerosis, coronary artery disease, myocardial infarction, hypoxia/reoxygenation injury, heart failure, type 2 diabetes, obesity, and nonalcoholic steatohepatitis. This review summarizes the recent developments in investigating the role of FGF21 in CVMDs and explores the mechanism whereby FGF21 regulates the development of CVMDs. Novel molecular targets and related pathways of FGF21 (adenosine 5'-monophosphate-activated protein kinase, silent information regulator 1, autophagy-related molecules, and gut microbiota-related molecules) are highlighted in this review. Considering the poor pharmacokinetics and biophysical properties of native FGF21, the development of new generations of FGF21-based drugs has tremendous therapeutic potential. Related preclinical and clinical studies are also summarized in this review to foster clinical translation. Thus, our review provides a timely and insightful overview of the physiology, biomarker potential, molecular targets, and therapeutic potential of FGF21 in CVMDs.

The interplay between nonalcoholic fatty liver disease and atherosclerotic cardiovascular disease

Therapeutic approaches that lower circulating low-density lipoprotein (LDL)-cholesterol significantly reduced the burden of cardiovascular disease over the last decades. However, the persistent rise in the obesity epidemic is beginning to reverse this decline. Alongside obesity, the incidence of nonalcoholic fatty liver disease (NAFLD) has substantially increased in the last three decades. Currently, approximately one third of world population is affected by NAFLD. Notably, the presence of NAFLD and particularly its more severe form, nonalcoholic steatohepatitis (NASH), serves as an independent risk factor for atherosclerotic cardiovascular disease (ASCVD), thus, raising interest in the relationship between these two diseases. Importantly, ASCVD is the major cause of death in patients with NASH independent of traditional risk factors. Nevertheless, the pathophysiology linking NAFLD/NASH with ASCVD remains poorly understood. While dyslipidemia is a common risk factor underlying both diseases, therapies that lower circulating LDL-cholesterol are largely ineffective against NASH. While there are no approved pharmacological therapies for NASH, some of the most advanced drug candidates exacerbate atherogenic dyslipidemia, raising concerns regarding their adverse cardiovascular consequences. In this review, we address current gaps in our understanding of the mechanisms linking NAFLD/NASH and ASCVD, explore strategies to simultaneously model these diseases, evaluate emerging biomarkers that may be useful to diagnose the presence of both diseases, and discuss investigational approaches and ongoing clinical trials that potentially target both diseases.

Dietary total antioxidant capacity is inversely associated with the odds of non-alcoholic fatty liver disease in people with type-2 diabetes

BACKGROUND

This study was conducted to evaluate possible associations between Dietary Total Antioxidant Capacity (DTAC) and odds of non-alcoholic fatty liver disease (NAFLD) in people with type-2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

We recruited two hundred people with T2DM, and evaluated their liver steatosis using Fibroscan. Dietary intakes of participants were assessed using a validated food frequency questionnaire. DTAC was computed via ferric reducing antioxidant power (FRAP).

RESULTS

In the crude model, no statistically significant association was found between DTAC and the odds of NAFLD in people with diabetes. However, after adjustment for potential confounders including age, gender, diabetes duration, smoking status, physical activity, BMI, waist circumference, and energy, the most reduced adjusted OR was indicated for the third tertile vs. the first one (OR: 0.28, 95% CI: 0.09-0.81, P = 0.02), meaning that diabetic patients in the third tertile of DTAC had 72% decreased risk of NAFLD in comparison to those in the first one. The relationship was remained significant after additional adjustment for HOMA-IR, HbA1c, serum Triglyceride (TG), and low-density lipoprotein-cholesterol (LDL) levels (OR: 0.29, 95% CI: 0.09-0.93, P = 0.03). Importantly, a dose-response pattern was demonstrated for DTAC and risk of NAFLD (P = 0.04).

CONCLUSION

Higher DTAC was related with a decreased risk of NAFLD in individuals with diabetes.

Sitagliptin reduces FAP-activity and increases intact FGF21 levels in patients with newly detected glucose abnormalities

INTRODUCTION

Fibroblast growth factor 21 (FGF21), a hormone with pleiotropic metabolic effects, is inactivated by fibroblast activation protein (FAP), a member of the dipeptidyl peptidase-IV (DPP-IV) family. We investigate if sitagliptin (DPP-IV inhibitor) inhibits FAP-activity and increases intact FGF21.

METHODS

Patients with impaired glucose metabolism were randomized to 100 mg sitagliptin (n = 34) or placebo (n = 37) treatment for 12 weeks. Plasma samples obtained at study entry and at 12-weeks were analysed for FAP-activity, FAP, total FGF21 and intact FGF21.

RESULTS

Sitagliptin significantly inhibited FAP-activity (497 ± 553 vs. 48 ± 712 RFU/min, p < 0.01) and correspondingly increased intact FGF21 (253 ± 182 vs 141 ± 80 ng/L, p < 0.01) compared to placebo in plasma. Sitagliptin dose-dependently inhibited the FAP-activity in vitro. Intact FGF21 was higher in patients obtaining a normal glucose tolerance regardless of treatment (p = 0.03).

CONCLUSION

A sitagliptin-induced increase of intact FGF21 may contribute to an improved metabolic effect in patients with impaired glucose metabolism.

Regulatory network and interplay of hepatokines, stellakines, myokines and adipokines in nonalcoholic fatty liver diseases and nonalcoholic steatohepatitis

Fatty liver disease is a spectrum of liver pathologies ranging from simple hepatic steatosis to non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), and culminating with the development of cirrhosis or hepatocellular carcinoma (HCC). The pathogenesis of NAFLD is complex and diverse, and there is a lack of effective treatment measures. In this review, we address hepatokines identified in the pathogenesis of NAFLD and NASH, including the signaling of FXR/RXR, PPARα/RXRα, adipogenesis, hepatic stellate cell activation/liver fibrosis, AMPK/NF-κB, and type 2 diabetes. We also highlight the interaction between hepatokines, and cytokines or peptides secreted from muscle (myokines), adipose tissue (adipokines), and hepatic stellate cells (stellakines) in response to certain nutritional and physical activity. Cytokines exert autocrine, paracrine, or endocrine effects on the pathogenesis of NAFLD and NASH. Characterizing signaling pathways and crosstalk amongst muscle, adipose tissue, hepatic stellate cells and other liver cells will enhance our understanding of interorgan communication and potentially serve to accelerate the development of treatments for NAFLD and NASH.

The Burden of Nonalcoholic Steatohepatitis: A Systematic Review of Epidemiology Studies

Background and Aims

Nonalcoholic steatohepatitis (NASH) is associated with increased mortality and risk of complications but is often asymptomatic and under-recognized. A systematic review of NASH epidemiology was conducted to provide information on the burden of NASH and highlight important evidence gaps for future research.

Methods

Medline, EMBASE, and Cochrane Library databases were searched for English-language publications published from 2010 to January 2022 that reported on natural history, risk factors, comorbidities, and complications of a NASH population or subpopulation.

Results

Overall, 173 publications were included. NASH was shown to have a variable disease course and high prevalence of comorbid disease. Although many patients progressed to cirrhosis and end-stage liver disease, disease regression or resolution was reported in up to half of patients in some studies. Reported risk factors for disease progression or resolution included levels of (or changes in) serum fibrosis markers, liver enzymes, and platelets. The presence of NASH increased the risk of liver cirrhosis and other serious diseases such as hepatocellular carcinoma, colorectal cancer, chronic kidney disease, and cardiovascular disease. In 2017, NASH was responsible for ∼118,000 cirrhosis deaths globally, and an increasing proportion of patients are receiving liver transplantation for NASH in Europe and the United States. Consolidation of data was hampered by heterogeneity across the studies in terms of patient populations, follow-up time, and outcomes measured.

Conclusion

NASH is associated with significant morbidity and mortality, an increased risk of comorbidities, and imposes an increasing burden among liver transplantation recipients. Longer studies with harmonized study criteria are required to better understand the impact of NASH on patient outcomes.

Molecular signatures of long-term hepatocellular carcinoma risk in nonalcoholic fatty liver disease

Prediction of hepatocellular carcinoma (HCC) risk is an urgent unmet need in patients with nonalcoholic fatty liver disease (NAFLD). In cohorts of 409 patients with NAFLD from multiple global regions, we defined and validated hepatic transcriptome and serum secretome signatures predictive of long-term HCC risk in patients with NAFLD. A 133-gene signature, prognostic liver signature (PLS)-NAFLD, predicted incident HCC over up to 15 years of longitudinal observation. High-risk PLS-NAFLD was associated with IDO1+ dendritic cells and dysfunctional CD8+ T cells in fibrotic portal tracts along with impaired metabolic regulators. PLS-NAFLD was validated in independent cohorts of patients with NAFLD who were HCC naïve (HCC incidence rates at 15 years were 22.7 and 0% in high- and low-risk patients, respectively) or HCC experienced (de novo HCC recurrence rates at 5 years were 71.8 and 42.9% in high- and low-risk patients, respectively). PLS-NAFLD was bioinformatically translated into a four-protein secretome signature, PLSec-NAFLD, which was validated in an independent cohort of HCC-naïve patients with NAFLD and cirrhosis (HCC incidence rates at 15 years were 37.6 and 0% in high- and low-risk patients, respectively). Combination of PLSec-NAFLD with our previously defined etiology-agnostic PLSec-AFP yielded improved HCC risk stratification. PLS-NAFLD was modified by bariatric surgery, lipophilic statin, and IDO1 inhibitor, suggesting that the signature can be used for drug discovery and as a surrogate end point in HCC chemoprevention clinical trials. Collectively, PLS/PLSec-NAFLD may enable NAFLD-specific HCC risk prediction and facilitate clinical translation of NAFLD-directed HCC chemoprevention.

Non-Alcoholic Fatty Liver Disease in Long-Term Type 2 Diabetes: Role of rs738409 PNPLA3 and rs499765 FGF21 Polymorphisms and Serum Biomarkers

Fibroblast growth factor 21 (FGF21) signaling and genetic factors are involved in non-alcoholic fatty liver disease (NAFLD) pathogenesis. However, these factors have rarely been studied in type 2 diabetes mellitus (T2D) patients from admixed populations such as in those of Brazil. Therefore, we aimed to evaluate rs738409 patanin-like phospholipase domain-containing protein (PNPLA3) and rs499765 FGF21 polymorphisms in T2D, and their association with NAFLD, liver fibrosis, and serum biomarkers (FGF21 and cytokeratin 18 levels). A total of 158 patients were included, and the frequency of NAFLD was 88.6%, which was independently associated with elevated body mass index. Significant liver fibrosis (≥F2) was detected by transient elastography (TE) in 26.8% of NAFLD patients, and was independently associated with obesity, low density lipoprotein, and gamma-glutamyl transferase (GGT). PNPLA3 GG genotype and GGT were independently associated with cirrhosis. PNPLA3 GG genotype patients had higher GGT and AST levels; PNPLA3 GG carriers had higher TE values than CG patients, and FGF21 CG genotype patients showed lower gamma-GT values than CC patients. No differences were found in serum values of FGF21 and CK18 in relation to the presence of NAFLD or liver fibrosis. The proportion of NAFLD patients with liver fibrosis was relevant in the present admixed T2D population, and was associated with PNPLA3 polymorphisms.

The Effect of Hyperlipidemia on the Course of Diabetic Retinopathy—Literature Review

Diabetes mellitus is a very important social issue, and its retinal complications continue to be one of the major causes of blindness worldwide. The effect of glucose level on the development of retinal retinopathy has been the subject of numerous studies and is well understood. Hypertension and hyperlipidemia have been known to be important risk factors in the development of diabetes complications. However, the mechanisms of this effect have not been fully explained and raise a good deal of controversy. The latest research results suggest that some lipoproteins are closely correlated with the incidence of diabetic retinopathy and that by exerting an impact on their level the disease course can be modulated. Moreover, pharmacotherapy which reduces the level of lipids, particularly by means of statins and fibrate, has been shown to alleviate diabetic retinopathy. Therefore, we have decided to review the latest literature on diabetic retinopathy with respect to the impact of hyperlipidemia and possible preventive measures

Part 1: Disease of the Heart and Liver: A Relationship That Cuts Both Ways

The heart and the liver display multifaceted, complex interactions that can be divided into cardiac effects of liver disease, hepatic effects of heart disease, and disease processes affecting both organs. In part 1 of this 2 part series, we discuss how acute and chronic heart failure can have devastating effects on the liver, such as acute cardiogenic liver injury and congestive hepatopathy. On the other hand, primary liver disease, such as cirrhosis, can lead to a plethora of cardiac insults representative in cirrhotic cardiomyopathy as systolic dysfunction, diastolic dysfunction, and electrophysiological disturbances. Nonalcoholic fatty liver disease has long been associated with cardiovascular events that increase mortality. The management of both disease processes changes when the other organ system becomes involved. This consideration is important with regard to a variety of interventions, most notably transplantation of either organ, as risk of complications dramatically rises in the setting of both heart and liver disease (discussed in part 2). As our understanding of the intricate communication between the heart and liver continues to expand so does our management.

Cellular interplay between cardiomyocytes and non-myocytes in diabetic cardiomyopathy

Patients with Type 2 diabetes mellitus (T2DM) frequently exhibit a distinctive cardiac phenotype known as diabetic cardiomyopathy. Cardiac complications associated with T2DM include cardiac inflammation, hypertrophy, fibrosis and diastolic dysfunction in the early stages of the disease, which can progress to systolic dysfunction and heart failure. Effective therapeutic options for diabetic cardiomyopathy are limited and often have conflicting results. The lack of effective treatments for diabetic cardiomyopathy is due in part, to our poor understanding of the disease development and progression, as well as a lack of robust and valid preclinical human models that can accurately recapitulate the pathophysiology of the human heart. In addition to cardiomyocytes, the heart contains a heterogeneous population of non-myocytes including fibroblasts, vascular cells, autonomic neurons and immune cells. These cardiac non-myocytes play important roles in cardiac homeostasis and disease, yet the effect of hyperglycaemia and hyperlipidaemia on these cell types are often overlooked in preclinical models of diabetic cardiomyopathy. The advent of human induced pluripotent stem cells provides a new paradigm in which to model diabetic cardiomyopathy as they can be differentiated into all cell types in the human heart. This review will discuss the roles of cardiac non-myocytes and their dynamic intercellular interactions in the pathogenesis of diabetic cardiomyopathy. We will also discuss the use of sodium-glucose cotransporter 2 inhibitors as a therapy for diabetic cardiomyopathy and their known impacts on non-myocytes. These developments will no doubt facilitate the discovery of novel treatment targets for preventing the onset and progression of diabetic cardiomyopathy.

Hepatocyte-specific fibroblast growth factor 21 overexpression ameliorates high-fat diet-induced obesity and liver steatosis in mice

Fibroblast growth factor (FGF) 21 is an endocrine growth factor mainly secreted by the liver in response to a ketogenic diet and alcohol consumption. FGF21 signaling requires co-receptor β-klotho (KLB) co-acting with FGF receptors, which has pleiotropic metabolic effects, including induced hepatic fatty acid oxidation and ketogenesis, in human and animal models of obesity. We examined the hepatocyte-specific enhancer/promoter of FGF21 expression plasmids in high-fat diet-fed mice for 12 weeks. Hydrodynamic injection for FGF21 delivery every 6 weeks sustained high circulating levels of FGF21, resulting in marked reductions in body weight, epididymal fat mass, insulin resistance, and liver steatosis. FGF21-induced lipolysis in the adipose tissue enabled the liver to be flooded with fat-derived FFAs. The hepatic expression of Glut2 and Bdh1 was upregulated, whereas that of gluconeogenesis-related genes, G6p and Pepck, and lipogenesis-related genes, Srebp-1 and Srebp-2, was significantly suppressed. FGF21 induced the phosphorylation of AMPK at Thr172 and Raptor at ser792 and suppressed that of mTOR at ser2448, which downregulated mTORC1 signaling and reduced IRS-1 phosphorylation at ser1101. Finally, in the skeletal muscle, FGF21 increased Glut4 and Mct2, a membrane protein that acts as a carrier for ketone bodies. Enzymes for ketone body catabolism (Scot) and citrate cycle (Cs, Idh3a), and a marker of regenerating muscle (myogenin) were also upregulated via increased KLB expression. Thus, FGF21-induced lipolysis was continuously induced by a high-fat diet and fat-derived FFAs might cause liver damage. Hepatic fatty acid oxidation and ketone body synthesis may act as hepatic FFAs' disposal mechanisms and contribute to improved liver steatosis. Liver-derived ketone bodies might be used for energy in the skeletal muscle. The potential FGF21-related crosstalk between the liver and extraliver organs is a promising strategy to prevent and treat metabolic syndrome-related nonalcoholic steatohepatitis.

FGF21 (Fibroblast Growth Factor 21) Defines a Potential Cardiohepatic Signaling Circuit in End-Stage Heart Failure

BACKGROUND

Extrinsic control of cardiomyocyte metabolism is poorly understood in heart failure (HF). FGF21 (Fibroblast growth factor 21), a hormonal regulator of metabolism produced mainly in the liver and adipose tissue, is a prime candidate for such signaling.

METHODS

To investigate this further, we examined blood and tissue obtained from human subjects with end-stage HF with reduced ejection fraction at the time of left ventricular assist device implantation and correlated serum FGF21 levels with cardiac gene expression, immunohistochemistry, and clinical parameters.

RESULTS

Circulating FGF21 levels were substantially elevated in HF with reduced ejection fraction, compared with healthy subjects (HF with reduced ejection fraction: 834.4 [95% CI, 628.4-1040.3] pg/mL, n=40; controls: 146.0 [86.3-205.7] pg/mL, n=20, P=1.9×10-5). There was clear FGF21 staining in diseased cardiomyocytes, and circulating FGF21 levels negatively correlated with the expression of cardiac genes involved in ketone metabolism, consistent with cardiac FGF21 signaling. FGF21 gene expression was very low in failing and nonfailing hearts, suggesting extracardiac production of the circulating hormone. Circulating FGF21 levels were correlated with BNP (B-type natriuretic peptide) and total bilirubin, markers of chronic cardiac and hepatic congestion.

CONCLUSIONS

Circulating FGF21 levels are elevated in HF with reduced ejection fraction and appear to bind to the heart. The liver is likely the main extracardiac source. This supports a model of hepatic FGF21 communication to diseased cardiomyocytes, defining a potential cardiohepatic signaling circuit in human HF.

Endocrine Fibroblast Growth Factors in Relation to Stress Signaling

Fibroblast growth factors (FGFs) play important roles in various growth signaling processes, including proliferation, development, and differentiation. Endocrine FGFs, i.e., atypical FGFs, including FGF15/19, FGF21, and FGF23, function as endocrine hormones that regulate energy metabolism. Nutritional status is known to regulate the expression of endocrine FGFs through nuclear hormone receptors. The increased expression of endocrine FGFs regulates energy metabolism processes, such as fatty acid metabolism and glucose metabolism. Recently, a relationship was found between the FGF19 subfamily and stress signaling during stresses such as endoplasmic reticulum stress and oxidative stress. This review focuses on endocrine FGFs and the recent progress in FGF studies in relation to stress signaling. In addition, the relevance of the stress-FGF pathway to disease and human health is discussed.

The Regulatory Role of the Central and Peripheral Serotonin Network on Feeding Signals in Metabolic Diseases

Central and peripheral serotonin (5-hydroxytryptamine, 5-HT) regulate feeding signals for energy metabolism. Disruption of central 5-HT signaling via 5-HT2C receptors (5-HT2CRs) induces leptin-independent hyperphagia in mice, leading to late-onset obesity, insulin resistance, and impaired glucose tolerance. 5-HT2CR mutant mice are more responsive than wild-type mice to a high-fat diet, exhibiting earlier-onset obesity and type 2 diabetes. High-fat and high-carbohydrate diets increase plasma 5-HT and fibroblast growth factor-21 (FGF21) levels. Plasma 5-HT and FGF21 levels are increased in rodents and humans with obesity, type 2 diabetes, and non-alcohol fatty liver diseases (NAFLD). The increases in plasma FGF21 and hepatic FGF21 expression precede hyperinsulinemia, insulin resistance, hyperglycemia, and weight gain in mice fed a high-fat diet. Nutritional, pharmacologic, or genetic inhibition of peripheral 5-HT synthesis via tryptophan hydroxylase 1 (Tph1) decreases hepatic FGF21 expression and plasma FGF21 levels in mice. Thus, perturbing central 5-HT signaling via 5-HT2CRs alters feeding behavior. Increased energy intake via a high-fat diet and/or high-carbohydrate diet can upregulate gut-derived 5-HT synthesis via Tph1. Peripheral 5-HT upregulates hepatic FGF21 expression and plasma FGF21 levels, leading to metabolic diseases such as obesity, insulin resistance, type 2 diabetes, and NAFLD. The 5-HT network in the brain–gut–liver axis regulates feeding signals and may be involved in the development and/or prevention of metabolic diseases.

The Nuanced Metabolic Functions of Endogenous FGF21 Depend on the Nature of the Stimulus, Tissue Source, and Experimental Model

Fibroblast growth factor 21 (FGF21) is a hormone that is involved in the regulation of lipid, glucose, and energy metabolism. Pharmacological FGF21 administration promotes weight loss and improves insulin sensitivity in rodents, non-human primates, and humans. However, pharmacologic effects of FGF21 likely differ from its physiological effects. Endogenous FGF21 is produced by many cell types, including hepatocytes, white and brown adipocytes, skeletal and cardiac myocytes, and pancreatic beta cells, and acts on a diverse array of effector tissues such as the brain, white and brown adipose tissue, heart, and skeletal muscle. Different receptor expression patterns dictate FGF21 function in these target tissues, with the primary effect to coordinate responses to nutritional stress. Moreover, different nutritional stimuli tend to promote FGF21 expression from different tissues; i.e., fasting induces hepatic-derived FGF21, while feeding promotes white adipocyte-derived FGF21. Target tissue effects of FGF21 also depend on its capacity to enter the systemic circulation, which varies widely from known FGF21 tissue sources in response to various stimuli. Due to its association with obesity and non-alcoholic fatty liver disease, the metabolic effects of endogenously produced FGF21 during the pathogenesis of these conditions are not well known. In this review, we will highlight what is known about endogenous tissue-specific FGF21 expression and organ cross-talk that dictate its diverse physiological functions, with particular attention given to FGF21 responses to nutritional stress. The importance of the particular experimental design, cellular and animal models, and nutritional status in deciphering the diverse metabolic functions of endogenous FGF21 cannot be overstated.

Contribution of Liver and Pancreatic Islet Crosstalk to β-Cell Function/Dysfunction in the Presence of Fatty Liver

Tissue-to-tissue crosstalk regulates organ function, according to growing data. This phenomenon is relevant for pancreatic β-cells and the liver, as both tissues are involved in glucose homeostasis and lipid metabolism. The ability to fine-tune regulation and adaptive responses is enabled through communication between pancreatic β-cells and the liver. However, the crosstalk between both tissues changes when metabolic dysregulation is present. Factors and cargo from extracellular vesicles (EVs) released by liver and pancreatic β-cells that reach the circulation form the words of this interaction. The molecules released by the liver are called hepatokines and are usually secreted in response to the metabolic state. When hepatokines reach the pancreatic islets several mechanisms are initiated for their protection or damage. In the case of the crosstalk between pancreatic β-cells and the liver, only one factor has been found to date. This protein, pancreatic derived factor (PANDER) has been proposed as a novel linker between insulin resistance (IR) and type 2 diabetes mellitus (T2D) and could be considered a biomarker for non-alcoholic fatty liver disease (NAFLD) and T2D. Furthermore, the cargo released by EVs, mainly miRNAs, plays a significant role in this crosstalk. A better knowledge of the crosstalk between liver and pancreatic β-cells is essential to understand both diseases and it could lead to better prevention and new therapeutic options.

Non-Alcoholic Steatohepatitis Severity Associates with FGF21 Level and Kidney Glucose Uptake

Background: Nonalcoholic steatohepatitis (NASH) is a severe form of fatty liver disease that has been shown to be associated with chronic kidney disease (CKD). Mechanism for the association of NASH with CKD remains unclear. In this study, we examined the association between NASH severity and kidney glucose uptake and the liver-secreted signaling molecule fibroblast growth factor 21 (FGF21). Methods: Kinetic parameters for kidney glucose transport rate (K₁) and standardized uptake value (SUV) were determined using dynamic positron emission tomography after injection of ¹⁸F-fluorodeoxyglucose. Liver biopsies were scored for NASH activity (inflammation and ballooning), fibrosis, and steatosis FGF21 was measured from fasting serum samples. Patients were categorized by liver biopsy and multivariate analyses were performed to evaluate the associations. Results: Of 41 NASH patients 73% were females, 71% white, 51% with steatosis ≥2, 39% with NASH activity ≥4 and fibrosis ≥3. With severe NASH activity, kidney SUV significantly increased even when adjusted for underlying insulin-resistant (IR) state. Kidney K₁ decreased significantly in higher liver activity in unadjusted models but not when adjusted for IR. FGF21 decreased with severe liver activity in adjusted models (P < 0.05) and associated with kidney K1 but not SUV. Conclusion: Our pilot data indicate that kidney glucose metabolism associates with NASH activity and FGF21 levels, suggesting a potential mechanism to NASH-induced CKD. Clinical Trials.gov ID: NCT02754037.

Mitochondrial Lipid Homeostasis at the Crossroads of Liver and Heart Diseases

The prevalence of NAFLD (non-alcoholic fatty liver disease) is a rapidly increasing problem, affecting a huge population around the globe. However, CVDs (cardiovascular diseases) are the most common cause of mortality in NAFLD patients. Atherogenic dyslipidemia, characterized by plasma hypertriglyceridemia, increased small dense LDL (low-density lipoprotein) particles, and decreased HDL-C (high-density lipoprotein cholesterol) levels, is often observed in NAFLD patients. In this review, we summarize recent genetic evidence, proving the diverse nature of metabolic pathways involved in NAFLD pathogenesis. Analysis of available genetic data suggests that the altered operation of fatty-acid β-oxidation in liver mitochondria is the key process, connecting NAFLD-mediated dyslipidemia and elevated CVD risk. In addition, we discuss several NAFLD-associated genes with documented anti-atherosclerotic or cardioprotective effects, and current pharmaceutical strategies focused on both NAFLD treatment and reduction of CVD risk.

Effects of interleukin-1 antagonism and corticosteroids on fibroblast growth factor-21 in patients with metabolic syndrome

Fibroblast growth factor-21 (FGF21) is elevated in patients with the metabolic syndrome. Although the exact underlying mechanisms remain ill-defined, chronic low-grade inflammation with increased Interleukin-(IL)-1β expression may be responsible. The aim of this study was to investigate effects of two different anti-inflammatory treatments (IL-1 antagonism or high-dose corticosteroids) on FGF21 in patients with the metabolic syndrome. This is a secondary analysis of two interventional studies in patients with obesity and features of the metabolic syndrome. Trial A was an interventional trial (n = 73) investigating short-term effects of the IL-1 antagonist anakinra and of dexamethasone. Trial B was a randomized, placebo-controlled, double-blinded trial (n = 67) investigating longer-term effects of IL-1 antagonism. In total, 140 patients were included in both trials. Median age was 55 years (IQR 44-66), 26% were female and median BMI was 37 kg/m² (IQR 34-39). Almost half of the patients were diabetic (45%) and had increased c-reactive protein levels of 3.4 mg/L. FGF21 levels correlated with fasting glucose levels, HOMA-index, C-peptide levels, HbA1c and BMI. Short-term treatment with anakinra led to a reduction of FGF21 levels by - 200 pg/mL (95%CI - 334 to - 66; p = 0.004). No effect was detectable after longer-term treatment (between-group difference: - 8.8 pg/mL (95%CI - 130.9 to 113.3; p = 0.89). Acute treatment with dexamethasone was associated with reductions of FGF21 by -175 pg/mL (95%CI - 236 to - 113; p < 0.001). Anti-inflammatory treatment with both, IL-1 antagonism and corticosteroids reduced FGF21 levels at short-term in individuals with the metabolic syndrome.Trial registration: ClinicalTrials.gov Identifiers NCT02672592 and NCT00757276.

Pubertal FGF21 deficit is central in the metabolic pathophysiology of an ovine model of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS), affecting over 10% of women, is associated with insulin resistance, obesity, dyslipidaemia, fatty liver and adipose tissue dysfunction. Its pathogenesis is poorly understood and consequently treatment remains suboptimal. Prenatally androgenized (PA) sheep, a clinically realistic model of PCOS, recapitulate the metabolic problems associated with PCOS. Fibroblast Growth Factor 21 (FGF21) is a metabolic hormone regulating lipid homeostasis, insulin sensitivity, energy balance and adipose tissue function. We therefore investigated the role of FGF21 in the metabolic phenotype of PA sheep. In adolescence PA sheep had decreased hepatic expression and circulating concentrations of FGF21. Adolescent PA sheep show decreased FGF21 signalling in subcutaneous adipose tissue, increased hepatic triglyceride content, trend towards reduced fatty acid oxidation capacity and increased hepatic expression of inflammatory markers. These data parallel studies on FGF21 deficiency, suggesting that FGF21 therapy during adolescence may represent a treatment strategy to mitigate metabolic problems associated with PCOS.