Circulating levels of FGF-21 in obese youth: associations with liver fat content and markers of liver damage

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.

The Impact of Human Liver Transplantation on the Concentration of Fibroblast Growth Factors: FGF19 and FGF21

The multitude of processes in which the liver participates makes it vulnerable to many serious diseases, which can lead to chronic organ failure. Modern medicine bases the treatment of end-stage liver failure on liver transplantation. To ensure the proper functioning of the transplanted liver, a balance of cellular and immunological processes and appropriate concentrations of many different factors are necessary, including, among others, fibroblast growth factors (FGFs). Over the last several years, studies have focused on some FGF growth factors, i.e., FGF19 and FGF21. These two growth factors belong to the FGF19 subfamily, and we concentrate on these two factors in our work. These factors diffuse away from the site of secretion into the blood, acting as hormones. FGF19 is a growth factor with a high therapeutic potential, involved in the homeostasis of bile acids necessary to maintain the proper function of the transplanted liver. FGF21, in turn, plays an important role in regulating lipid and glucose homeostasis. This study aimed to evaluate changes in the concentration of growth factors FGF19 and FGF21 in the plasma of 84 patients before, 24 h, and 2 weeks after liver transplantation (ELISA test was used). Additionally, the correlations of the basic laboratory parameters-alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGTP), alkaline phosphatase (ALP), total bilirubin, C-reactive protein (CRP), albumin and hemoglobin (Hb)-with FGF19 and FGF21 were determined. Our studies noted statistically significant changes in FGF19 and FGF21 concentrations before, 24 h, and 2 weeks after liver transplantation. The highest values for FGF19 before liver transplantation and the lowest values 24 h after this surgery were observed for FGF21; the highest concentrations were observed the day after liver transplantation, and the lowest were observed immediately before surgery. Observations of increases and decreases in the concentration of the examined factors at individual time points (before and after transplantation) allow us to suspect that FGF19 has an adaptive and protective function toward the transplanted liver. At the same time, FGF21 may affect the regenerative mechanisms of the damaged organ.

Hepatic lipogenesis marked by GCKR-modulated triglycerides increases serum FGF21 in children/teens with obesity

AIMS

Fibroblast growth factor 21 (FGF21) decreases hepatic lipogenesis in animal models, and FGF21 analogues decrease serum triglycerides (TG) in adults in phase-2 trials. On the other hand, serum FGF21 is associated with higher TG in observational studies of people with obesity, raising a sort of paradox. We tested the hypothesis that FGF21 is induced by TG in youth with obesity, as a compensatory mechanism.

MATERIALS AND METHODS

We recruited 159 children/adolescents with obesity (80 males, 12.7 ± 2.1 years). Besides serum FGF21 and lipid dosages, we genotyped the Pro446Leu variant at glucokinase regulator (GCKR) as a known marker of genetically increased hepatic de novo lipogenesis, and we used it as an instrumental variable to establish a cause-and-effect relationship between FGF21 and TG, according to a Mendelian randomization analysis.

RESULTS

The Pro446Leu variant increased circulating TG (β = +0.35, p < 0.001), which was positively associated with circulating FGF21 (β = +0.42, p < 0.001). The Pro446Leu variant increased FGF-21 (β = +0.14, p = 0.031) with the expected slope (β-coefficient) in case of association entirely mediated by TG: 0.35 (slope between Pro446Ala and TG) × 0.42 (slope between TG and FGF21) = 0.14.

CONCLUSIONS

Hepatic lipogenesis, marked by GCKR-modulated triglycerides, is significantly associated with increased serum FGF-21 in children/adolescents with obesity.

Identification of State Markers in Anorexia Nervosa: Replication and Extension of Inflammation-Associated Biomarkers Using Multiplex Profiling

Background

Proteomics offers potential for detecting and monitoring anorexia nervosa (AN) and its variant, atypical AN (atyp-AN). However, research has been limited by small protein panels, a focus on adult AN, and lack of replication.

Methods

In this study, we performed Olink multiplex profiling of 92 inflammation-related proteins in females with AN/atyp-AN (n = 64), all of whom were ≤90% of expected body weight, and age-matched healthy control individuals (n = 44).

Results

Five proteins differed significantly between the primary AN/atyp-AN group and the healthy control group (lower levels: HGF, IL-18R1, TRANCE; higher levels: CCL23, LIF-R). The expression levels of 3 proteins (lower IL-18R1, TRANCE; higher LIF-R) were uniquely disrupted in participants with AN in our primary model. No unique expression levels emerged for atyp-AN. In the total sample, 12 proteins (ADA, CD5, CD6, CXCL1, FGF-21, HGF, IL-12B, IL18, IL-18R1, SIRT2, TNFSF14, TRANCE) were positively correlated with body mass index and 5 proteins (CCL11, FGF-19, IL8, LIF-R, OPG) were negatively correlated with body mass index in our primary models.

Conclusions

Our results replicate the results of a previous study that demonstrated a dysregulated inflammatory status in AN and extend those results to atyp-AN. Of the 17 proteins correlated with body mass index, 11 were replicated from a previous study that used similar methods, highlighting the promise of inflammatory protein expression levels as biomarkers of AN disease monitoring. Our findings underscore the complexity of AN and atyp-AN by highlighting the inability of the identified proteins to differentiate between these 2 subtypes, thereby emphasizing the heterogeneous nature of these disorders.

Fibroblast growth factor 21: An emerging pleiotropic regulator of lipid metabolism and the metabolic network

Fibroblast growth factor 21 (FGF21) was originally identified as an important metabolic regulator which plays a crucial physiological role in regulating a variety of metabolic parameters through the metabolic network. As a novel multifunctional endocrine growth factor, the role of FGF21 in the metabolic network warrants extensive exploration. This insight was obtained from the observation that the FGF21-dependent mechanism that regulates lipid metabolism, glycogen transformation, and biological effectiveness occurs through the coordinated participation of the liver, adipose tissue, central nervous system, and sympathetic nerves. This review focuses on the role of FGF21-uncoupling protein 1 (UCP1) signaling in lipid metabolism and how FGF21 alleviates non-alcoholic fatty liver disease (NAFLD). Additionally, this review reveals the mechanism by which FGF21 governs glucolipid metabolism. Recent research on the role of FGF21 in the metabolic network has mostly focused on the crucial pathway of glucolipid metabolism. FGF21 has been shown to have multiple regulatory roles in the metabolic network. Since an adequate understanding of the concrete regulatory pathways of FGF21 in the metabolic network has not been attained, this review sheds new light on the metabolic mechanisms of FGF21, explores how FGF21 engages different tissues and organs, and lays a theoretical foundation for future in-depth research on FGF21-targeted treatment of metabolic diseases.

Immune cell balance as potential biomarker of progressing non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a widespread chronic, slowly progressive metabolic multifactorial disease. It is represented by several clinical and morphological forms: steatosis, nonalcoholic steatohepatitis (NASH) (with or without fibrosis), and liver cirrhosis. The search for minimally invasive and cost-effective biomarkers of NAFLD is a key task in the diagnosis, staging of progression, and long-term monitoring of NAFLD. This article discusses the possibility of using immune cell balance as potential minimally invasive peripheral markers of NAFLD progression. In the progression of NASH from steatosis to fibrosis and cirrhosis, inflammation plays an important role because of the activation of Kupffer cells and increased migration of monocytes, dendritic cells, neutrophils, and activated T lymphocytes into the tissues. Macrophages originating from monocytes, with NASH progression, gradually begin to prevail over the pool of resident macrophages. The risk of NASH and fibrosis development in patients with NAFLD increases with the ratio of neutrophils/lymphocytes in the liver. An increase in the Th17 cell count and a decrease in T-regulatory cell count can contribute to increased hepatic steatosis and inflammation development in NAFLD and accelerate the transition from simple steatosis to steatohepatitis and fibrosis. Information on the participation of noncoding RNAs in the regulation of the balance of immune cells in NAFLD is presented, which also allows us to consider them as additional, along with cellular, markers of disease progression.

Advances in Noninvasive Biomarkers for Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) currently represents one of the most common liver diseases worldwide. Early diagnosis and disease staging is crucial, since it is mainly asymptomatic, but can progress to nonalcoholic steatohepatitis (NASH) or cirrhosis or even lead to the development of hepatocellular carcinoma. Over time, efforts have been put into developing noninvasive diagnostic and staging methods in order to replace the use of a liver biopsy. The noninvasive methods used include imaging techniques that measure liver stiffness and biological markers, with a focus on serum biomarkers. Due to the impressive complexity of the NAFLD's pathophysiology, biomarkers are able to assay different processes involved, such as apoptosis, fibrogenesis, and inflammation, or even address the genetic background and "omics" technologies. This article reviews not only the currently validated noninvasive methods to investigate NAFLD but also the promising results regarding recently discovered biomarkers, including biomarker panels and the combination of the currently validated evaluation methods and serum markers.

Identification of State Markers in Anorexia Nervosa: Replication and Extension of Inflammation Associated Biomarkers Using Multiplex Profiling in Anorexia Nervosa and Atypical Anorexia Nervosa

Proteomics provides an opportunity for detection and monitoring of anorexia nervosa (AN) and its related variant, atypical-AN (atyp-AN). However, research to date has been limited by the small number of proteins explored, exclusive focus on adults with AN, and lack of replication across studies. This study performed Olink Proseek Multiplex profiling of 92 proteins involved in inflammation among females with AN and atyp-AN (N = 64), all < 90% of expected body weight, and age-matched healthy controls (HC; N=44). After correction for multiple testing, nine proteins differed significantly in the AN/atyp-AN group relative to HC group ( lower levels: CXCL1, HGF, IL-18R1, TNFSF14, TRANCE; higher levels: CCL23, Flt3L, LIF-R, MMP-1). The expression levels of three proteins ( lower IL-18R1, TRANCE; higher LIF-R) were uniquely disrupted in females with AN. No unique expression levels emerged for atyp-AN. Across the whole sample, twenty-one proteins correlated positively with BMI (ADA, AXIN1, CD5, CD244, CD40, CD6, CXCL1, FGF-21, HGF, IL-10RB, IL-12B, IL18, IL-18R1, IL6, LAP TGF-beta-1, SIRT2, STAMBP, TNFRSF9, TNFSF14, TRAIL, TRANCE) and six (CCL11, CCL23, FGF-19, IL8, LIF-R, OPG) were negatively correlated with BMI. Overall, our results replicate the prior study demonstrating a dysregulated inflammatory status in AN, and extend these results to atyp-AN (AN/atyp-AN all < 90% of expected body weight). Of the 27 proteins correlated with BMI, 18 were replicated from a prior study using similar methods, highlighting the promise of inflammatory protein expression levels as biomarkers of disease monitoring. Additional studies of individuals across the entire weight spectrum are needed to understand the role of inflammation in atyp-AN.

Noninvasive biomarkers in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide among children and adolescents. It encompasses a spectrum of disease, from its mildest form of isolated steatosis, to nonalcoholic steatohepatitis (NASH) to liver fibrosis and cirrhosis, or end-stage liver disease. The early diagnosis of pediatric NAFLD is crucial in preventing disease progression and in improving outcomes. Currently, liver biopsy is the gold standard for diagnosing NAFLD. However, given its invasive nature, there has been significant interest in developing noninvasive methods that can be used as accurate alternatives. Here, we review noninvasive biomarkers in pediatric NAFLD, focusing primarily on the diagnostic accuracy of various biomarkers as measured by their area under the receiver operating characteristic, sensitivity, and specificity. We examine two major approaches to noninvasive biomarkers in children with NAFLD. First, the biological approach that quantifies serological biomarkers. This includes the study of individual circulating molecules as biomarkers as well as the use of composite algorithms derived from combinations of biomarkers. The second is a more physical approach that examines data measured through imaging techniques as noninvasive biomarkers for pediatric NAFLD. Each of these approaches was applied to children with NAFLD, NASH, and NAFLD with fibrosis. Finally, we suggest possible areas for future research based on current gaps in knowledge.

The roles of hepatokine and osteokine in liver-bone crosstalk: Advance in basic and clinical aspects

Both the liver and bone are important secretory organs in the endocrine system. By secreting organ factors (hepatokines), the liver regulates the activity of other organs. Similarly, bone-derived factors, osteokines, are created during bone metabolism and act in an endocrine manner. Generally, the dysregulation of hepatokines is frequently accompanied by changes in bone mass, and osteokines can also disrupt liver metabolism. The crosstalk between the liver and bone, particularly the function and mechanism of hepatokines and osteokines, has increasingly gained notoriety as a topic of interest in recent years. Here, based on preclinical and clinical evidence, we summarize the potential roles of hepatokines and osteokines in liver-bone interaction, discuss the current shortcomings and contradictions, and make recommendations for future research.

Relationship Between the Serum FGF21 Level and Growth in Children of Short Stature

BACKGROUND

This study investigated the relationship between fibroblast growth factor 21 (FGF21) levels and growth in children with growth hormone deficiency (GHD) and idiopathic short stature (ISS), and the effects of the FGF21 level on response to growth hormone (GH) treatment.

METHODS

We included 171 pre-pubertal children with a GHD (n = 54), ISS (n = 46), and normal height (n = 71). Fasting FGF21 levels were measured at baseline and every 6 months during GH treatment. Factors associated with growth velocity (GV) after GH therapy were investigated.

RESULTS

The FGF21 level was higher in short children than in the controls without significant difference between the GHD and ISS groups. In the GHD group, the FGF21 level was inversely associated with the free fatty acid (FFA) level at baseline (r = -0.28, P = 0.039), however, was positively correlated with the FFA level at 12 months (r = 0.62, P = 0.016). The GV over 12 months of GH therapy was positively associated with the delta insulin-like growth factor 1 level (β = 0.003, P = 0.020). The baseline log-transformed FGF21 level was inversely associated with GV with marginal significance (β = -0.64, P = 0.070).

CONCLUSION

The FGF21 level was higher in children of short stature, both those with GHD and the ISS, than in children with normal growth. The pretreatment FGF21 level negatively affected the GV of children with GH-treated GHD. These results suggest the existence of a GH/FFA/FGF21 axis in children.

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.

Fibroblast Growth Factor 21 Levels and Bone Mineral Density in Metabolically Healthy and Metabolically Unhealthy Obese Children

OBJECTIVE

The harmful or beneficial effect of obesity on bone mineral density (BMD) remains controversial in children and adolescents. Fibroblast growth factor 21 (FGF21) is a metabolic factor that plays a specific role in the regulation of carbohydrate and lipid metabolism. However, the role of FGF21 in bone metabolism appears paradoxical and is complex. To determine whether serum FGF21 level was associated with BMD in obese children and adolescents.

METHODS

The study was conducted with the participation of children and adolescents aged 8-18 years. Ninety-eight obese children were included in the study group and 44 children were included in the control group. BMD, in addition to the routine obesity workup, which includes fasting blood glucose, fasting insulin levels, lipid profile, and liver enzymes; serum FGF21 levels have been analyzed.

RESULTS

The mean age of the obese group (n=98) was 13.34±2.24 years and the mean age of controls (n=44) was 13.48±2.87 years. Based on International Diabetes Federation criteria, 15 of 98 (15.3%) patients were metabolically unhealthy. FGF21 levels were 193.54±139.62 mg/dL in the obese group and 158.69±151.81 mg/dL in the control group (p=0.06). There was no difference between the FGF21 and BMD z-score values of girls and boys in the obese and control groups (p>0.05).

CONCLUSION

BMD-z-score was increased in obese children compared to healthy control. Moreover, BMD-z-score tended to be higher when more metabolic risk factors were present. However, there was no significant relationship between FGF21 levels and BMD z-score values in obese children.

Advance of Serum Biomarkers and Combined Diagnostic Panels in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) affects approximately 25-30% population worldwide, which progresses from simple steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma, and has complications such as cardiovascular events. Liver biopsy is still the gold standard for the diagnosis of NAFLD, with some limitations, such as invasive, sampling deviation, and empirical judgment. Therefore, it is urgent to develop noninvasive diagnostic biomarkers. Currently, a large number of NAFLD-related serum biomarkers have been identified, including apoptosis, inflammation, fibrosis, adipokines, hepatokines, and omics biomarkers, which could effectively diagnose NASH and exclude patients with progressive fibrosis. We summarized serum biomarkers and combined diagnostic panels of NAFLD, to provide some guidance for the noninvasive diagnosis and further clinical studies.

Bicistronic reporter mice for monitoring of Fgf21 expression

Fibroblast growth factor 21 (FGF21) is a metabolic hormone that is synthesized and secreted by cellular and metabolic stresses. Serum FGF21 levels are associated with clinical parameters in patients with various diseases, including metabolic disorders. Animal models that allow FGF21 levels to be monitored in vivo are important for research and clinical applications of FGF21. Here, a novel Fgf21-reporter mouse strain (Fgf21^+/Luc2-tdT) expressing luciferase and tandem dimer tomato (tdT) fluorescence proteins under the control of the endogenous Fgf21 promoter was generated, which provided an in vitro and in vivo monitoring tool for the Fgf21 expression. Luciferase activity, in vivo bioluminescence, and tdT fluorescence were analyzed in adult mice fed or fasted for 24 h. Luciferase activities were significantly increased in the liver but slightly decreased in the pancreas of fasted mice compared with those of fed mice. In vivo bioluminescence signal was increased in the liver of fasted mice. Obvious tdT fluorescence was detected in the pancreas. These results suggest that Fgf21-reporter mice have great potential for research and clinical applications of FGF21.

An Open-Label Exploratory Clinical Trial Evaluating the Effects of GLS (Coptidis Rhizoma-Evodiae Fructus 2 : 1) on Fibroblast Growth Factor 21 in Patients with Nonalcoholic Fatty Liver Disease

Methods

In a 12-week, open-label, exploratory clinical trial, 126 NAFLD patients were randomly divided into the GLS group (lifestyle intervention plus GLS) or the polyene phosphatidylcholine (PPC) group (lifestyle intervention plus PPC). Random numbers generated by DPS software were used in combination with opaque, sealed envelopes for allocation concealment. At baseline as well as at the end of the study, anthropometric parameters, glucose, lipids, hepatic enzymes, and FGF 21 were measured, with hepatic fat accumulation assessed by ultrasound (US) and US-based controlled attenuation parameter (CAP).

Results

119 patients completed the study. Baseline parameters did not significantly differ between the two groups (P > 0.05). Compared with PPC, GLS decreased more significantly in hepatic fat accumulation, body weight index, waist circumference, waist-to-hip ratio, serum glucose, total cholesterol, triglyceride, low-density lipoprotein cholesterol, alanine transaminase, aspartate transaminase, gamma-glutamyl transferase, and FGF 21 (P < 0.05). The effects of GLS on waist circumference, waist-to-hip ratio, CAP, and gamma-glutamyl transferase (GGT) were positively correlated with serum FGF 21 (r = 0.343, 0.342, 0.315, and 0.374, respectively, P < 0.05). The GGT and FGF-21 changes were also confirmed by multiple linear regression analysis (B, 0.777; 95% CI: 0.307–1.247, P < 0.05).

Conclusion

GLS has a significant hepatoprotective effect on NAFLD patients, causing a decrease in FGF-21 secretion in response to the damage itself.

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 stimulatory effects of glucagon on cortisol and GH secretion occur independently from FGF-21

PURPOSE

Glucagon stimulation test (GST) is used to assess the hypothalamo-pituitary-adrenal (HPA) and growth hormone (GH) axes with an incompletely defined mechanism. We aimed to assess if glucagon acted through fibroblast growth factor-21 (FGF-21) to stimulate cortisol and GH secretion. The secondary outcome was to determine the relationship of FGF-21 with variable GH responses to GST in obesity.

METHODS

A total of 26 healthy participants; 11 obese (body mass index (BMI) > 30 kg/m²) and 15 leans (BMI < 25 kg/m²) were included. Basal pituitary and target hormone levels were measured and GST was performed. During GST, glucose, insulin, cortisol, GH, and FGF-21 responses were measured.

RESULTS

The mean age of the participants was 26.3±3.6 years. Glucagon resulted in significant increases in FGF-21, glucose, insulin, cortisol, and GH levels. The levels of basal cortisol, GH, FGF-21, and IGF-1 were similar in the two groups. The peak GH and area under the curve (AUC)_(GH) responses to GST in the obese group were lower than those of the normal-weight group with a different pattern of response. There were no differences between the groups in terms of peak cortisol, AUC_(cortisol), peak insulin, AUC_(insulin), peak FGF-21, and AUC_(FGF21). Obesity was associated with significantly increased glucose and insulin responses and slightly decreased FGF-21 response to glucagon.

CONCLUSION

Obesity was associated with blunted and delayed GH, but preserved cortisol responses to GST. This is the first study showing that glucagon stimulates the HPA and GH axis independently from FGF-21. The delayed GH response to GST in obesity does not seem to be related to FGF-21.

Hepatocellular Carcinoma and Obesity, Type 2 Diabetes Mellitus, Cardiovascular Disease: Causing Factors, Molecular Links, and Treatment Options

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, which will affect more than a million people by the year 2025. However, current treatment options have limited benefits. Nonalcoholic fatty liver disease (NAFLD) is the fastest growing factor that causes HCC in western countries, including the United States. In addition, NAFLD co-morbidities including obesity, type 2 diabetes mellitus (T2DM), and cardiovascular diseases (CVDs) promote HCC development. Alteration of metabolites and inflammation in the tumor microenvironment plays a pivotal role in HCC progression. However, the underlying molecular mechanisms are still not totally clear. Herein, in this review, we explored the latest molecules that are involved in obesity, T2DM, and CVDs-mediated progression of HCC, as they share some common pathologic features. Meanwhile, several therapeutic options by targeting these key factors and molecules were discussed for HCC treatment. Overall, obesity, T2DM, and CVDs as chronic metabolic disease factors are tightly implicated in the development of HCC and its progression. Molecules and factors involved in these NAFLD comorbidities are potential therapeutic targets for HCC treatment.

Serum Fibroblast Growth Factor 21 Levels in Children and Adolescents with Hashimoto’s Thyroiditis before and after l-Thyroxin Medication: A Prospective Study

Backgrounds and Objectives: Fibroblast growth factor 21 (FGF-21) is a complex hormone, sharing common sites of action with thyroid hormones. We investigated the association among FGF-21 levels, resting metabolic rate (RMR), and l-thyroxin (LT4) treatment in children and adolescents with Hashimoto’s thyroiditis. Materials and Methods: A total of 60 youngsters with chronic autoimmune thyroiditis (AIT) (30 with subclinical hypothyroidism, 30 with euthyroidism) and 30 age and sex-matched healthy participants (5–18 years old) were enrolled in the study. Anthropometric, biochemical parameters, and RMR levels were assessed in all participants; serum FGF-21 levels were measured in the control group and the group with subclinical hypothyroidism before and six months after medication with LT4. Results: FGF-21 levels were lower in the treatment group compared with the healthy ones, but this difference was not statistically significant (p > 0.05); despite the increase in FGF-21 levels after six months of LT4 treatment, this difference was not statistically significant (p > 0.05). Free thyroxin (FT4) levels correlated well with FGF-21 levels (r = 0.399, p < 0.01), but further analysis revealed no interaction between these two variables. Both patient groups presented elevated triglyceride (TG) levels compared to controls (p < 0.05). LT4 treatment had no impact on RMR and lipid or liver or glycaemic parameters. An increase in fat mass and fat-free mass were reported, independently of FGF-21 levels. Conclusions: In youngsters with subclinical hypothyroidism due to Hashimoto’s thyroiditis, the serum FGF-21 levels are not significantly lower than in healthy individuals and increase after treatment with LT4 without a statistical significance. Further studies with a large number of young patients and severe hypothyroidism are recommended to confirm our results.

Altered adipokines in obese adolescents: a cross-sectional and longitudinal analysis across the spectrum of glycemia

Obesity and type 2 diabetes are rapidly increasing in the adolescent population. We sought to determine whether adipokines, specifically leptin, C1q/TNF-related proteins 1 (CTRP1) and CTRP9, and the hepatokine fibroblast growth factor 21 (FGF21), are associated with obesity and hyperglycemia in a cohort of lean and obese adolescents, across the spectrum of glycemia. In an observational, longitudinal study of lean and obese adolescents, we measured fasting laboratory tests, oral glucose tolerance tests, and adipokines including leptin, CTRP1, CTRP9, and FGF21. Participants completed baseline and 2-year follow-up study visits and were categorized as lean (LC, lean control; n = 30), obese normoglycemic (ONG; n = 61), and obese hyperglycemic (OHG; n = 31) adolescents at baseline and lean (n = 8), ONG (n = 18), and OHG (n = 4) at follow-up. Groups were compared using ANOVA and regression analysis, and linear mixed effects modeling was used to test for differences in adipokine levels across baseline and follow-up visits. Results showed that at baseline, leptin was higher in all obese groups (P < 0.001) compared with LC. FGF21 was higher in OHG participants compared with LC (P < 0.001) and ONG (P < 0.001) and positively associated with fasting glucose (P < 0.001), fasting insulin (P < 0.001), Homeostasis Model Assessment-Insulin Resistance Index (HOMA-IR; P < 0.001), and hemoglobin A1c (HbA1c; P = 0.01). CTRP1 was higher in OHG compared with ONG (P = 0.03). CTRP9 was not associated with obesity or hyperglycemia in this pediatric cohort. At 2 years, leptin decreased in ONG (P = 0.003) and FGF21 increased in OHG (P = 0.02), relative to lean controls. Altered adipokine levels are associated with the inflammatory milieu in obese youth with and without hyperglycemia. In adolescence, the novel adipokine CTRP1 was elevated with hyperglycemia, whereas CTRP9 was unchanged in this cohort.NEW & NOTEWORTHY Leptin is higher in obese adolescents and FGF21 is higher in obese hyperglycemic adolescents. The novel adipokine CTRP1 is higher in obese hyperglycemic adolescents, whereas CTRP9 was unchanged in this adolescent cohort.

Non-Alcoholic Fatty Liver Disease in Obese Youth With Insulin Resistance and Type 2 Diabetes

Currently, Non-Alcoholic Fatty Liver Disease (NAFLD) is the most prevalent form of chronic liver disease in children and adolescents worldwide. Simultaneously to the epidemic spreading of childhood obesity, the rate of affected young has dramatically increased in the last decades with an estimated prevalence of NAFLD of 3%-10% in pediatric subjects in the world. The continuous improvement in NAFLD knowledge has significantly defined several risk factors associated to the natural history of this complex liver alteration. Among them, Insulin Resistance (IR) is certainly one of the main features. As well, not surprisingly, abnormal glucose tolerance (prediabetes and diabetes) is highly prevalent among children/adolescents with biopsy-proven NAFLD. In addition, other factors such as genetic, ethnicity, gender, age, puberty and lifestyle might affect the development and progression of hepatic alterations. However, available data are still lacking to confirm whether IR is a risk factor or a consequence of hepatic steatosis. There is also evidence that NAFLD is the hepatic manifestation of Metabolic Syndrome (MetS). In fact, NAFLD often coexist with central obesity, impaired glucose tolerance, dyslipidemia, and hypertension, which represent the main features of MetS. In this Review, main aspects of the natural history and risk factors of the disease are summarized in children and adolescents. In addition, the most relevant scientific evidence about the association between NAFLD and metabolic dysregulation, focusing on clinical, pathogenetic, and histological implication will be provided with some focuses on the main treatment options.

Dose-response relationship between serum fibroblast growth factor 21 and liver fat content in non-alcoholic fatty liver disease

BACKGROUND & AIM

Although serum fibroblast growth factor 21 (FGF21) levels are associated with liver fat content in non-alcoholic liver fat disease (NAFLD), the precise nature of the association remains undetermined. Therefore, this study aimed to explore the potential dose-response relationship between FGF21 and liver fat content in NAFLD.

METHODS

For this exploratory study from a randomized trial, 220 NAFLD patients with central obesity were recruited via community-based screening and randomly assigned to either control, moderate or vigorous-moderate exercise groups for 12 months. After this exercise intervention, patients were followed-up for a further 12 months. Serum FGF21 levels were measured by ELISA. Intrahepatic triglyceride (IHTG) content was determined by proton magnetic resonance spectroscopy.

RESULTS

Of the 220 patients, 149 (67.7%) were female; mean age was 53.9 ± 7.1 years and mean BMI was 28.0 ± 2.9 kg/m² for all patients. Baseline IHGT increased gradually (P = 0.029 for trend) according to baseline serum FGF21 quartiles 1, 2, 3 and 4 (212.3, 358.9, 538.7 and 793.5 pg/mL, respectively). On grouping the distribution of serum FGF21 level changes into quartiles at month 12, the relative IHTG loss increased as serum FGF21 levels were reduced (P = 0.004 for trend). A similar trend was observed at month 24 (P = 0.006 for trend). Multivariate linear regression analysis revealed that changes in serum FGF21 levels were independently associated with changes in IHTG at both month 12 [β (SE), 0.136 (0.118); P = 0.048] and month 24 [β (SE), 0.152 (0.139); P = 0.041]. Using restricted cubic spline regression, changes in serum FGF21 were strongly and positively associated with their corresponding relative IHTG loss at both month 12 and follow-up (P_overall = 0.017, P_non-linear = 0.044 and P_overall = 0.020, P_non-linear = 0.361, respectively, for dose-response).

CONCLUSION

Serum FGF21 is strongly associated with liver fat content in a dose-response manner in centrally obese NAFLD patients. These findings support the use of serum FGF21 as a biomarker of liver fat content in NAFLD.

FGF21 in obesity and cancer: New insights

The endocrine FGF21 was discovered as a novel metabolic regulator in 2005 with new functions bifurcating from the canonic heparin-binding FGFs that directly promote cell proliferation and growth independent of a co-receptor. Early studies have demonstrated that FGF21 is a stress sensor in the liver and possibly, several other endocrine and metabolic tissues. Hepatic FGF21 signals via endocrine routes to quench episodes of metabolic derangements, promoting metabolic homeostasis. The convergence of mouse and human studies shows that FGF21 promotes lipid catabolism, including lipolysis, fatty acid oxidation, mitochondrial oxidative activity, and thermogenic energy dissipation, rather than directly regulating insulin and appetite. The white and brown adipose tissues and, to some extent, the hypothalamus, all of which host a transmembrane receptor binary complex of FGFR1 and co-receptor KLB, are considered the essential tissue and molecular targets of hepatic or pharmacological FGF21. On the other hand, a growing body of work has revealed that pancreatic acinar cells form a constitutive high-production site for FGF21, which then acts in an autocrine or paracrine mode. Beyond regulation of macronutrient metabolism and physiological energy expenditure, FGF21 appears to function in forestalling the development of fatty pancreas, steato-pancreatitis, fatty liver, and steato-hepatitis, thereby preventing the development of advanced pathologies such as pancreatic ductal adenocarcinoma or hepatocellular carcinoma. This review is intended to provide updates on these new discoveries that illuminate the protective roles of FGF21-FGFR1-KLB signal pathway in metabolic anomalies-associated severe tissue damage and malignancy, and to inform potential new preventive or therapeutic strategies for obesity-inflicted cancer patients via reducing metabolic risks and inflammation.

Noninvasive diagnostic tools for pediatric NAFLD: where are we now?

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of liver disease in the pediatric population. It is a significant liver complication of obesity that also prominently affects children. Over the past decade, several noninvasive methods have been investigated for replacing liver biopsy to identify which children with NAFLD have nonalcoholic steatohepatitis (NASH) and fibrosis. These methods that aim to differentiate the type and extent of liver damage are based on two main different methodologies: a 'biological' approach centered on the quantification of circulating biomarkers; and a 'physical' approach established by analyzing different imaging data.

AREAS COVERED

In this review, we illustrate the state of the art and recent discoveries on noninvasive methods for the diagnosis of NAFLD, NASH, and advanced fibrosis.

EXPERT OPINION

Currently, noninvasive tests cannot diagnose NASH or determine the degree of fibrosis. However, several lines of evidence have suggested that if these tests are used in a complementary way with other laboratory tests and imaging they have the potential to be used to monitor progression of disease and response to therapy in pediatric NAFLD. Future scientific research will focus on combining these methods with multiple potential predictors of genetic susceptibility.

Higher increase degree of FGF21 post long-term interdisciplinary weight loss therapy preserves the free fat mass and rest metabolic rate in adolescents with obesity

Objective Fibroblast growth factor 21 (FGF21) is among the activators that can stimulate thermogenesis in the white adipose tissue and brown adipose tissue. People with obesity have elevated blood levels of FGF21, but also develop resistance to its action, impairing its beneficial role. Inversely, clinical treatments to weight loss has been pointed out as an important therapy for increasing and recovering sensitivity to FGF21. The aim was to analyse the effect of long-term weight loss interdisciplinary intervention on FGF21 and body composition. Subjects and methods Eighty-six post-pubertal obese adolescents (14-19 years-old), were submitted to 20 weeks of weight loss therapy (clinical, nutritional, psychological and physical exercise support). Anthropometric measures, body composition and rest metabolic rate (RMR) by bioelectrical impedance, and serum FGF21 sample by ELISA were evaluated. The adolescents were grouped according to FGF21 individual delta variations after therapy: Higher Increase (HI); lower increase (LI); lower decrease (LD); higher decrease (HD). Results All groups present weight loss. Only in FGF21 ≥ 76,5 pg/mL variation the free-fat-mass and rest metabolic rate were preserved and to others group these variables were significantly reduced. Conclusion High increase in FGF21 can contribute to preservation of FFM and RMR after weight loss therapy, could have important implications for energy balance regulation. Future studies are necessary to continue determining the role of magnitude effects of FGF21 levels in obesity to improve clinical practice, especially in paediatrics population.

Resistance training attenuates circulating FGF-21 and myostatin and improves insulin resistance in elderly men with and without type 2 diabetes mellitus: A randomised controlled clinical trial

Fibroblast growth factor 21 (FGF-21) and myostatin have been proposed to be potential therapeutic target for insulin resistance in age-related metabolic disorders including type 2 diabetes (T2D). Moreover, despite the potential metabolic effect of resistance training on insulin resistance, aging, and T2D; the effect of this type of exercise training on FGF-21 and myostatin in elderly men with and without T2D are unknown. Forty-four elderly men were assigned to either the RT training (RT; without T2D: 12, with TD2 = 10) or the control group (C; without T2D: 12, with TD2 = 10). The RT group performed 12-wk resistance training intervention, 3 days/wk, 10 repetitions with 70% 1RM. At the baseline, the elderly men with T2D had a higher FGF-21 (p = 0.002) and myostatin (p = 0.02) concentrations and lower muscle strength (p = 0.01) than the elderly men without T2D. RT resulted in significant decrease in FGF-21 and myostatin concentration and increase in muscle strength in both elderly men with and without T2D (P = 0.001, for all) as well as decrease in HOMA-IR in only elderly men without T2D (P = 0.001). There was no significant difference in the RT-induced FGF-21 reduction between elderly men with and without T2D (p = 0.77, p = 0.28, respectively), but, RT caused a larger reduction in circulating myostatin in elderly men without T2D than with T2D (P = 0.007). Taken together, our results demonstrated that 12 weeks of RT induced an overall significant reduction of FGF-21 and myostatin in elderly men with and without T2D; with higher reduction of myostatin in elderly men without T2D.

Fibroblast Growth Factor-21 to Adiponectin Ratio: A Potential Biomarker to Monitor Liver Fat in Children With Obesity

Background: There is a pressing need for effective and non-invasive biomarkers to track intrahepatic triglyceride (IHTG) in children at-risk for non-alcoholic fatty liver disease (NAFLD), as standard-of-care reference tools, liver biopsy and magnetic resonance imaging (MRI), are impractical to monitor the course disease. Objective: We aimed to examine the association between serum fibroblast growth factor (FGF)-21 to adiponectin ratio (FAR) and IHTG as assessed by MRI in children with obesity. Methods: Serum FGF21 and adiponectin levels and IHTG were measured at two time points (baseline, 6 months) in obese children enrolled in a clinical weight loss program. The association between percent change in FAR and IHTG at final visit was examined using a multiple linear regression model. Results: At baseline, FAR was higher in the subjects with NAFLD (n = 23, 35.8 ± 41.9 pg/ng) than without NAFLD (n = 35, 19.8 ± 13.7 pg/ng; p = 0.042). Forty-eight subjects completed both visits and were divided into IHTG loss (≥1% reduction than baseline), no change (within ±1% change), and gain (≥1% increase than baseline) groups. At 6 months, the percent change in FAR was different among the three groups (p = 0.005). Multiple linear regression showed a positive relationship between percent change in FAR and the final liver fat percent in sex and pubertal stage-similar subjects with NAFLD at baseline (slope coefficient 6.18, 95% CI 1.90-10.47, P = 0.007), but not in those without NAFLD. Conclusions: Higher value in percent increase in FAR is positively associated with higher level of IHTG percent value at 6 months in children with baseline NAFLD. FAR could be a potential biomarker to monitor the changes in IHTG in children with NAFLD.

Role of Hepatokines in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is closely associated with metabolic diseases like type 2 diabetes and obesity. In recent decades, accumulating evidence has revealed that the hepatokines, proteins mainly secreted by the liver, play important roles in the development of NAFLD by acting directly on the lipid and glucose metabolism. As a member of organokines, the hepatokines establish the communication between the liver and the adipose, muscular tissues. In this review, we summarize the current understanding of the hepatokines and how they modulate the pathogenesis of metabolic disorders especially NAFLD.

Fibroblast growth factor 21 in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of pathologies ranging from uncomplicated hepatic fat accumulation to a state of lobular inflammation and hepatocyte ballooning, known as non-alcoholic steatohepatitis (NASH). Currently, there are no reliable biomarkers or effective therapeutic options established for NAFLD. Nevertheless, there are several molecular targets in the pipeline, of which fibroblast growth factor 21 (FGF21) is one. FGF21 is secreted primarily from liver and has a plethora of metabolic functions. Pre-clinical and epidemiological studies indicate a relationship between circulating FGF21 levels and hepatic fat content in both mice and humans. Moreover, animal studies have clearly shown that aberrant FGF21 signalling is a key pathological step in the development and progression of NAFLD. A recent Phase II clinical trial demonstrated that administration of an FGF21 analogue significantly reduced hepatic fat in subjects with NASH. As such, FGF21 provides a novel target for future biomarker and therapeutic studies. This review appraises preclinical data to outline the current understanding of FGF21 function in both normal hepatic function and NAFLD. Epidemiological evidence is explored to delineate the relationship between circulating FGF21 levels and NAFLD in humans. Finally, we review the therapeutic effects of FGF21 in the treatment of NAFLD.

Association of the 3'UTR polymorphism (rs11665896) in the FGF21 gene with metabolic status and nutrient intake in children with obesity

Background Fibroblast growth factor 21 (FGF21) is considered an important regulator of lipid and glucose metabolism. However, the role of FGF21 in macronutrient intake and metabolic disease, particularly in pediatric population, still needs further clarification. This study aimed to evaluate the association of rs11665896 in the FGF21 gene with metabolic status and macronutrient intake in a cohort of Mexican children with obesity. Methods Eighty-four lean children and 113 children with obesity, from 8 to 11 years of age, were recruited. FGF21 rs11665896 was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Somatometric evaluations, nutrient intake, glucose, lipids, insulin and FGF21 serum levels were measured in the obesity group. Results The T allele of rs11665896 in the FGF21 gene was associated with obesity (odds ratio [OR] = 1.99, 95% confidence interval [CI] = 1.14-3.46; p = 0.0151). Subjects with obesity carrying the TT genotype consumed less lipids and more carbohydrates compared to other genotypes. Circulating FGF21 levels correlated negatively with carbohydrate intake (r = -0.232, p = 0.022) and positively with body weight (r = 0.269, p = 0.007), waist (r = 0.242, p = 0.016) and hip girth (r = 0.204, p = 0.042). FGF21 levels were lower in carriers of at least one T allele. Conclusions Genetic variants in FGF21 could influence metabolic status, food preferences and qualitative changes in nutritional behavior in children.

The FGF metabolic axis

Members of the fibroblast growth factor (FGF) family play pleiotropic roles in cellular and metabolic homeostasis. During evolution, the ancestor FGF expands into multiple members by acquiring divergent structural elements that enable functional divergence and specification. Heparan sulfate-binding FGFs, which play critical roles in embryonic development and adult tissue remodeling homeostasis, adapt to an autocrine/paracrine mode of action to promote cell proliferation and population growth. By contrast, FGF19, 21, and 23 coevolve through losing binding affinity for extracellular matrix heparan sulfate while acquiring affinity for transmembrane α-Klotho (KL) or β-KL as a coreceptor, thereby adapting to an endocrine mode of action to drive interorgan crosstalk that regulates a broad spectrum of metabolic homeostasis. FGF19 metabolic axis from the ileum to liver negatively controls diurnal bile acid biosynthesis. FGF21 metabolic axes play multifaceted roles in controlling the homeostasis of lipid, glucose, and energy metabolism. FGF23 axes from the bone to kidney and parathyroid regulate metabolic homeostasis of phosphate, calcium, vitamin D, and parathyroid hormone that are important for bone health and systemic mineral balance. The significant divergence in structural elements and multiple functional specifications of FGF19, 21, and 23 in cellular and organismal metabolism instead of cell proliferation and growth sufficiently necessitate a new unified and specific term for these three endocrine FGFs. Thus, the term "FGF Metabolic Axis," which distinguishes the unique pathways and functions of endocrine FGFs from other autocrine/paracrine mitogenic FGFs, is coined.

Can hepatokines be regarded as novel non-invasive serum biomarkers of intrahepatic lipid content in obese children?

PURPOSE

Hepatokines are proteins produced by the liver and involved in regulating glucose and lipid metabolism. However, their role as the biomarkers of intrahepatic lipid content is not clear. The aim of the study was to evaluate the serum concentration of selected hepatokines: fibroblast growth factor-21 (FGF-21), selenoprotein P (SELENOP) and sex hormone-binding globulin (SHBG) in obese children.

PATIENTS AND METHODS

The cross-sectional study included 86 obese children with suspected liver disease. Nonalcoholic fatty liver disease (NAFLD) was diagnosed in children with liver steatosis in ultrasound with elevated alanine aminotransferase (ALT) serum activity and excluded other liver diseases. The total intrahepatic lipid content (TILC) was assessed by magnetic resonance proton spectroscopy (¹H-MRS).

RESULTS

The concentration of FGF-21 and SELENOP was significantly higher and SHBG significantly lower in children with NAFLD compared to controls. Only FGF-21 level was significantly higher in NAFLD children than in obese patients without NAFLD. The significant positive correlation of FGF-21 with ALT, gamma glutamyltransferase (GGT), triglycerides, homeostatic model assessment-insulin resistance (HOMA-IR), the degree of liver steatosis in ultrasound and TILC in ¹H-MRS were found. The ability of serum FGF-21 to diagnose severe liver steatosis was significant.

CONCLUSIONS

FGF-21 can be considered as a suitable biomarker in predicting TILC and fatty liver in obese children.

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

CONTEXT

The relationship between plasma fibroblast growth factor 21 (FGF21), insulin resistance, and steatohepatitis has not been systematically assessed.

OBJECTIVE

To determine if higher plasma FGF21 is associated with worse steatohepatitis on liver biopsy in patients with nonalcoholic fatty liver disease (NAFLD).

DESIGN AND SETTING

Cross-sectional study in a university hospital.

PATIENTS INTERVENTIONS AND MAIN OUTCOME MEASURES

Patients with a body mass index >25 (n = 187) underwent: (i) euglycemic hyperinsulinemic clamp to assess tissue-specific insulin resistance (IR); (ii) liver magnetic resonance spectroscopy for intrahepatic triglyceride quantification, (iii) liver biopsy (if NAFLD present; n = 146); and (iv) fasting plasma FGF21 levels.

METHODS AND RESULTS

Patients were divided into three groups: (i) No NAFLD (n = 41); (ii) No nonalcoholic steatohepatitis (NASH) (patients with isolated steatosis or borderline NASH; n = 52); and (iii) NASH (patients with definite NASH; n = 94). Groups were well-matched for age/sex, prevalence of type 2 diabetes mellitus, and hemoglobin A1c. During euglycemic hyperinsulinemic insulin clamp, insulin sensitivity in skeletal muscle and adipose tissue worsened from No NAFLD to NASH (both P < 0.001). Plasma FGF21 levels correlated inversely with insulin sensitivity in adipose tissue (r = -0.17, P = 0.006) and skeletal muscle (r = -0.23, P = 0.007), but not with liver insulin sensitivity. Plasma FGF21 was higher in patients with NASH (453 ± 262 pg/mL) when compared with the No NASH (341 ± 198 pg/mL, P = 0.03) or No NAFLD (325 ± 289 pg/mL, P = 0.02) groups. Plasma FGF21 increased with the severity of necroinflammation (P = 0.02), and most significantly with worse fibrosis (P < 0.001), but not with worsening steatosis (P = 0.60).

CONCLUSIONS

Plasma FGF21 correlates with severity of steatohepatitis, in particular of fibrosis, in patients with NASH. Measurement of FGF21 may help identify patients at the highest risk of disease progression.

Circulating FGF21 Levels in Human Health and Metabolic Disease

Human fibroblast growth factor 21 (FGF21) is primarily produced and secreted by the liver as a hepatokine. This hormone circulates to its target tissues (e. g., brain, adipose tissue), which requires two components, one of the preferred FGF receptor isoforms (FGFR1c and FGFR3c) and the co-factor beta-Klotho (KLB) to trigger downstream signaling pathways. Although targeting FGF21 signaling in humans by analogues and receptor agonists results in beneficial effects, e. g., improvements in plasma lipids and decreased body weight, it failed to recapitulate the improvements in glucose handling shown for many mouse models. FGF21's role and metabolic effects in mice and its therapeutic potential have extensively been reviewed elsewhere. In this review we focus on circulating FGF21 levels in humans and their associations with disease and clinical parameters, focusing primarily on obesity and obesity-associated diseases such as type-2 diabetes. We provide a comprehensive overview on human circulating FGF21 levels under normal physiology and metabolic disease. We discuss the emerging field of inactivating FGF21 in human blood by fibroblast activation protein (FAP) and its potential clinical implications.

The SGLT2 Inhibitor Dapagliflozin Reduces Liver Fat but Does Not Affect Tissue Insulin Sensitivity: A Randomized, Double-Blind, Placebo-Controlled Study With 8-Week Treatment in Type 2 Diabetes Patients

OBJECTIVE

The aim of this study was to investigate tissue-specific effects of dapagliflozin on insulin sensitivity and liver and body fat in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

This randomized, double-blind, parallel group, placebo-controlled study recruited 32 patients with type 2 diabetes. Enrolled patients were to have HbA_1c 6.5-10.5% (48-91 mmol/mol) and ≥3 months of stable treatment with metformin, dipeptidyl peptidase 4 inhibitor, or their combination. Patients were randomized 1:1 to receive 10 mg dapagliflozin or placebo daily for 8 weeks. Before and after the intervention, tissue insulin sensitivity was measured using [¹⁸F]-fluorodeoxyglucose and positron emission tomography during hyperinsulinemic-euglycemic clamp. Liver proton density fat fraction (PDFF) and adipose tissue volumes were assessed using MRI, and blood biomarkers were analyzed.

RESULTS

After 8 weeks, glycemic control was improved by dapagliflozin (placebo-corrected change in HbA_1c -0.39%, P < 0.01), but whole-body glucose uptake was not increased (P = 0.90). Tissue-specific insulin-stimulated glucose uptake did not change in skeletal muscle, liver, myocardium, or white and brown adipose tissue, and endogenous glucose production remained unaffected. However, there were significant placebo-corrected decreases in liver PDFF (-3.74%, P < 0.01), liver volume (-0.10 L, P < 0.05), visceral adipose tissue volume (-0.35 L, P < 0.01), interleukin-6 (-1.87 pg/mL, P < 0.05), and N-terminal prohormone of brain natriuretic peptide (-96 ng/L, P = 0.03).

CONCLUSIONS

In this study, 8 weeks of treatment with dapagliflozin reduced liver PDFF and the volume of visceral adipose tissue in obese patients with type 2 diabetes. Although glycemic control was improved, no effect on tissue-level insulin sensitivity was observed.

Including Fibroblast Growth Factor-21 in Combined Biomarker Panels Improves Predictions of Liver Steatosis Severity in Children

Background: Previous studies reported conflicting results regarding the association between fibroblast growth factor-21 (FGF-21) and non-alcoholic fatty liver disease (NAFLD). This study aimed to evaluate the feasibility of combining FGF-21, obesity indices, and biochemical tests for predicting high-grade liver steatosis in children. Methods: A total of 203 children and adolescents aged 5-18 years were enrolled, and their anthropometric data, body composition, liver ultrasound score for NAFLD (range, 0-6), biochemical test results, and FGF-21, leptin, and adiponectin levels were analyzed. Children were categorized according to body mass index (BMI) and NAFLD scores. Univariate analysis and multivariate linear regression were used to identify independent predictors for the degree of liver steatosis. The accuracy of the models was also evaluated using a receiver-operating characteristic (ROC) curve. Results: FGF-21 levels were significantly higher in subjects with high-grade liver steatosis (P < 0.001). In obese and overweight children, regression analysis indicated that higher BMI and higher gamma-glutamyl transferase (γ-GT), triglycerides (TG), and FGF-21 levels were independent risk factors strongly correlated with NAFLD scores. FGF-21 combined with any of the above parameters showed a larger area under the ROC (AUROC, 0.861-0.873) than either parameter used alone. Overall, the best performance was obtained by combing FGF-21, γ-GT, and TG, with an AUROC of 0.871, specificity of 82.54%, and sensitivity of 83.78% for predicting high-grade liver steatosis. Conclusion: BMI, FGF-21, γ-GT, and TG levels were strongly correlated with liver steatosis severity. Including FGF-21 in the biomarker panels may improve the accuracy for identifying obese and overweight children with high-grade liver steatosis.

Exploration of serum sensitive biomarkers of fatty liver in dairy cows

Serum proteins are sensitive with diseases in dairy cows, and some of them could be used as biomarkers for fatty liver. This study aimed to explore serum biomarkers for fatty liver in dairy cows. A total of 28 early lactating dairy cows were chosen from a commercial dairy herds, liver samples were collected for determining concentration of triacylglycerol (TAG), and serum samples were collected for measuring fibroblast growth factor-21 (FGF-21), adiponectin, Lipoprotein-associated phospholipase A2 (LP-PLA2), and hemoglobin (Hb). Dairy cows were divided into fatty liver (liver TAG > 5%, wet weight) and control group (liver TAG < 5%, wet weight). Concentration of FGF-21 was greater in fatty liver cows, while the concentration of LP-PLA2 and Hb was less. The concentration of FGF-21 and total Hb had strong correlation with the liver TAG as well as good prediction power (kappa value = 0.79 and 0.58, respectively). These results suggested that the serum concentration of FGF-21 and total Hb could be potentially used as fatty liver biomarkers in lactating dairy cows.

Effects of dapagliflozin and n-3 carboxylic acids on non-alcoholic fatty liver disease in people with type 2 diabetes: a double-blind randomised placebo-controlled study

AIMS/HYPOTHESIS

The EFFECT-II study aimed to investigate the effects of dapagliflozin and omega-3 (n-3) carboxylic acids (OM-3CA), individually or combined, on liver fat content in individuals with type 2 diabetes and non-alcoholic fatty liver disease (NAFLD).

METHODS

This randomised placebo-controlled double-blind parallel-group study was performed at five clinical research centres at university hospitals in Sweden. 84 participants with type 2 diabetes and NAFLD were randomly assigned 1:1:1:1 to four treatments by a centralised randomisation system, and all participants as well as investigators and staff involved in the study conduct and analyses were blinded to treatments. Each group received oral doses of one of the following: 10 mg dapagliflozin (n = 21), 4 g OM-3CA (n = 20), a combination of both (n = 22) or placebo (n = 21). The primary endpoint was liver fat content assessed by MRI (proton density fat fraction [PDFF]) and, in addition, total liver volume and markers of glucose and lipid metabolism as well as of hepatocyte injury and oxidative stress were assessed at baseline and after 12 weeks of treatment (completion of the trial).

RESULTS

Participants had a mean age of 65.5 years (SD 5.9), BMI 31.2 kg/m² (3.5) and liver PDFF 18% (9.3). All active treatments significantly reduced liver PDFF from baseline, relative changes: OM-3CA, -15%; dapagliflozin, -13%; OM-3CA + dapagliflozin, -21%. Only the combination treatment reduced liver PDFF (p = 0.046) and total liver fat volume (relative change, -24%, p = 0.037) in comparison with placebo. There was an interaction between the PNPLA3 I148M polymorphism and change in liver PDFF in the active treatment groups (p = 0.03). Dapagliflozin monotherapy, but not the combination with OM-3CA, reduced the levels of hepatocyte injury biomarkers, including alanine aminotransferase, aspartate aminotransferase, γ-glutamyl transferase (γ-GT), cytokeratin (CK) 18-M30 and CK 18-M65 and plasma fibroblast growth factor 21 (FGF21). Changes in γ-GT correlated with changes in liver PDFF (ρ = 0.53, p = 0.02). Dapagliflozin alone and in combination with OM-3CA improved glucose control and reduced body weight and abdominal fat volumes. Fatty acid oxidative stress biomarkers were not affected by treatments. There were no new or unexpected adverse events compared with previous studies with these treatments.

CONCLUSIONS/INTERPRETATION

Combined treatment with dapagliflozin and OM-3CA significantly reduced liver fat content. Dapagliflozin monotherapy reduced all measured hepatocyte injury biomarkers and FGF21, suggesting a disease-modifying effect in NAFLD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02279407 FUNDING: The study was funded by AstraZeneca.

Apoptosis and non-alcoholic fatty liver diseases

The number of patients with nonalcoholic fatty liver diseases (NAFLD) including nonalcoholic steatohepatitis (NASH), has been increasing. NASH causes cirrhosis and hepatocellular carcinoma (HCC) and is one of the most serious health problems in the world. The mechanism through which NASH progresses is still largely unknown. Activation of caspases, Bcl-2 family proteins, and c-Jun N-terminal kinase-induced hepatocyte apoptosis plays a role in the activation of NAFLD/NASH. Apoptotic hepatocytes stimulate immune cells and hepatic stellate cells toward the progression of fibrosis in the liver through the production of inflammasomes and cytokines. Abnormalities in glucose and lipid metabolism as well as microbiota accelerate these processes. The production of reactive oxygen species, oxidative stress, and endoplasmic reticulum stress is also involved. Cell death, including apoptosis, seems very important in the progression of NAFLD and NASH. Recently, inhibitors of apoptosis have been developed as drugs for the treatment of NASH and may prevent cirrhosis and HCC. Increased hepatocyte apoptosis may distinguish NASH from NAFLD, and the improvement of apoptosis could play a role in controlling the development of NASH. In this review, the association between apoptosis and NAFLD/NASH are discussed. This review could provide their knowledge, which plays a role in seeing the patients with NAFLD/NASH in daily clinical practice.

Effects of Sex Hormone Treatment on the Metabolic Syndrome in Transgender Individuals: Focus on Metabolic Cytokines

CONTEXT

Hormonal treatment in transgender persons affects many components of the metabolic syndrome (MS).

OBJECTIVE

To determine the role of direct hormonal effects, changes in metabolic cytokines, and body composition on metabolic outcomes.

DESIGN, SETTING, AND PARTICIPANTS

24 transwomen and 45 transmen from the European Network for the Investigation of Gender Incongruence were investigated at baseline and after 12 months of hormonal therapy.

OUTCOME MEASURES

Best predictors for changes in components of MS, applying least absolute shrinkage and selection operator regression.

RESULTS

In transwomen, a decrease in triglyceride levels was best explained by a decrease in fat mass and an increase in fibroblast growth factor 21 (FGF-21); the decrease in total and low-density lipoprotein cholesterol levels was principally due to a decrease in resistin. A decrease in high-density lipoprotein cholesterol depended on an inverse association with fat mass. In contrast, in transmen, an increase in low-density lipoprotein cholesterol was predicted by a decrease in FGF-21 and an increase in the waist/hip ratio; a decrease in the high-density lipoprotein/total cholesterol ratio depended on a decline in adiponectin levels. In transwomen, worsened insulin resistance and increased early insulin response seemed to be due to a direct treatment effect; however, improvements in hepatic insulin sensitivity in transmen were best predicted by a positive association with chemerin, resistin, and FGF-21 and were inversely related to changes in the waist/hip ratio and leptin and adipocyte fatty acid-binding protein levels.

CONCLUSIONS

The effects of hormonal therapy on different components of the MS are sex-specific and involve a complex interplay of direct hormonal effects, changes in body composition, and metabolic cytokine secretion.

Adiposity Is a Key Correlate of Circulating Fibroblast Growth Factor-21 Levels in African Males with or without Type 2 Diabetes Mellitus

BACKGROUND

Fibroblast growth factor-21 is an endocrine regulator with therapeutic and diagnostic potential. The levels and pattern of circulating FGF-21 have been described mainly in European and Asian populations. Given its strong association with adiposity, and the reported ethnic variabilities in body composition, examining FGF-21 in an African population is crucial.

METHODS

We measured levels of circulating FGF-21 in 207 overweight and obese Tanzanian males with or without type 2 diabetes mellitus (T2DM), and using statistical approaches, we explored their relationship with anthropometric and biochemical parameters.

RESULTS

Consistent with previous reports from European and Asian populations, we found higher levels of FGF-21 in people with T2DM compared to those without the disease. Based on statistical models, measures of adiposity explained up to 59% of the variability in FGF-21 levels in the circulation.

CONCLUSION

Levels of circulating FGF-21 in overweight and obese African males are higher in T2DM and strongly correlate with measures of adiposity.

Independent Association of Serum Fibroblast Growth Factor 21 Levels With Impaired Liver Enzymes in Hyperthyroid Patients

Fibroblast growth factor 21 (FGF21) is identified as a potential biomarker for liver diseases. However, information is limited regarding serum FGF21 and impaired liver function in hyperthyroidism. We aim to determine the potential association of serum FGF21 levels with impaired liver enzymes in hyperthyroid patients. In this case-control study, 105 normal subjects and 122 overt hyperthyroid patients were included. Among them, 41 hyperthyroid patients who obtained euthyroid status after thionamide treatment received second visit. Serum FGF21 levels were determined using the ELISA method. Compared to the normal subjects, patients with hyperthyroidism had significantly elevated serum liver enzymes, including alanine transaminase (ALT) (p < 0.001), aspartate aminotransferase (AST) (p < 0.001) levels, as well as FGF21 levels (p < 0.001). Further analysis showed serum FGF21 (p < 0.05), as well as thyroid hormone (TH) free T3 (p < 0.05), free T4 (p < 0.05) levels were higher in hyperthyroid patients with impaired liver enzymes than in those with normal liver enzymes. After reversal of hyperthyroid state, elevated serum FGF21 levels in hyperthyroid patients declined significantly (p < 0.001), with a concomitant decrease in serum ALT (p < 0.001), AST (p < 0.001) levels. Correlation analysis showed close correlation between FGF21 and ALT (p < 0.002), AST (p < 0.012), free T3 (p < 0.001), free T4 (p < 0.001). Further logistic regression analysis revealed FGF21 is significantly associated with elevated ALT [Odds Ratio, OR 1.79, (95% confidence interval, CI), (1.30-2.47), P < 0.001], AST [1.59 (1.07-2.34), p < 0.020]. After adjustment of potential confounders, the association between FGF21 and elevated ALT remained significant [1.42 (1.01-1.99), p < 0.043]. In conclusion, serum FGF21 is independently associated with impaired liver enzymes in hyperthyroid patients.

Plasma Levels of Myonectin But Not Myostatin or Fibroblast-Derived Growth Factor 21 Are Associated with Insulin Resistance in Adult Humans without Diabetes Mellitus

BACKGROUND

Myokines are a group of protein mediators produced by skeletal muscle under stress or physical exertion. Even though their discovery and effects in cell culture and animal models of disease have elicited great enthusiasm, very little is known about their role in human metabolism. We assessed whether plasma concentrations of three known myokines [myonectin, myostatin, and fibroblast-derived growth factor 21 (FGF-21)] would be associated with direct and indirect indicators of insulin resistance (IR) in individuals who did not have a diagnosis of diabetes.

METHODS

We studied 81 adults of both sexes comprising a wide range of body adiposity and insulin sensitivity. All participants underwent a thorough clinical assessment and a 5-point oral glucose tolerance test with calculation of multiple IR and insulin sensitivity indices. Twenty-one of them additionally underwent a hyperinsulinemic-euglycemic clamp with determination of steady-state whole-body insulin-stimulated glucose disposal ("M"). We compared plasma myokine concentrations across quartiles of IR indices and clinical IR surrogates, and explored the correlation of each myokine with the M-value.

RESULTS

Plasma myonectin levels increased monotonically across quartiles of the incremental area under the insulin curve (higher values indicate more IR) (p-trend = 0.021) and decreased monotonically across quartiles of the insulin sensitivity index (ISI - higher values indicate less IR) (p-trend = 0.012). After multivariate adjustment for other relevant determinants of IR (body mass index, age, and sex), the negative association of myonectin with ISI persisted (standardized beta = -0.235, p = 0.023). Myostatin was not associated with any clinical IR indicator or direct IR index measure. In multivariate analyses, FGF-21 showed a trend toward a positive correlation with glucose disposal that did not reach statistical significance (standardized beta = 0.476, p = 0.091).

CONCLUSION

The secretion of myonectin may constitute an attempt at a compensatory mechanism against IR in humans.

Fibroblast growth factor 21 decreases after liver fat reduction via growth hormone augmentation

OBJECTIVE

Fibroblast growth factor 21 (FGF21) ameliorates steatohepatitis but is increased in humans with fatty liver, potentially due to compensatory mechanisms and/or FGF21 resistance. Further, animal models suggest that GH increases serum FGF21. Tesamorelin, a growth hormone releasing hormone agonist, reduces liver fat in HIV-infected individuals. The objectives of this study were to investigate changes in FGF21 during tesamorelin treatment, to elucide the interplay between FGF21, GH augmentation, and liver fat reduction in humans.

METHODS

50 HIV-infected men and women with increased abdominal adiposity participated in this randomized, placebo-controlled trial of tesamorelin, 2mg vs. identical placebo daily for six months. Fasting laboratory measures, liver fat by 1H-magnetic resonance spectroscopy, and visceral adipose tissue (VAT) by computed tomography were obtained. Euglycemic hyperinsulinemic clamp was performed in a randomly selected subset.

RESULTS

At baseline, serum log10 FGF21 was significantly associated with log10 liver fat (r=0.32, p=0.03). Log10 FGF21 tended to decrease in the tesamorelin group compared to placebo (p=0.06). Among the entire cohort, reductions in FGF21 were significantly associated with reductions in liver fat (ρ=0.41, p=0.01), log10 gamma glutamyl tran speptidase (GGT, r=0.40, p=0.009), and FIB4 index (r=0.37, p=0.02).

CONCLUSIONS

In HIV-infected individuals, FGF21 is significantly positively associated with liver fat. FGF21 decreases in association with reductions in liver fat, GGT, and FIB4, suggesting that FGF21 is upregulated in the context of steatosis and steatohepatitis and is reduced when these conditions improve. Moreover, these data suggest that tesamorelin improves liver fat via pathways other than increasing serum FGF21.

TRIAL REGISTRATION

clinicaltrials.govNCT01263717.