Circulating Fibroblast Growth Factor 21 Levels Research Articles

Regulation of Renal Cortical PPAR-alpha and Downstream Targets by Sodium Glucose Cotransporter, Type 2 Inhibition (SGLT2i) in High-Fat Fed Mice

SGLT2i has been shown to be protective of renal function and health in type 2 diabetes by unclear means. Recently we reported that empagliflozin (EMPA) treatment of mice on a high-fat diet (HFD) led to marked changes in the renal cortical lipidome, including significant upregulation of many carnitine species (11 species > 35% increased, all p < 0.05). Carnitines are critical in the oxidation of long-chain fatty acids by increasing their uptake into the mitochondria. The mechanism underlying this upregulation was unclear, but the peroxisome proliferator activated receptor, subtype alpha (PPARα) has been demonstrated to upregulate carnitines in other tissues. To the test the impact of EMPA (E) or control (C) treatment on renal cortical PPARα and downstream targets, male (M) and female (F) C57Bl6 mice were treated with HFD (60% by weight) ± EMPA (100 mg/kg·diet) for 12 weeks. EMPA caused a reduction in final body weight (20%) only in females. No differences were observed in final kidney weights (n = 16-18/group). Glomerular filtration rate (GFR) measured by FITC-sinistrin clearance showed a trend (p = 0.052 two-way ANOVA) for an increase by EMPA (mean ± sem, ml/min, n = 5-9): MC- 246 ± 13; ME- 291 ± 5; FC- 252 ± 13; and FE- 275 ± 36. Western blotting of cortex homogenates revealed a modest, insignificant rise in PPARα, itself with EMPA, and a higher overall abundance in females (p = 0.024 for sex, mean band density, % MC): MC-100 ± 14; ME- 108 ±11; FC- 123± 12, FE- 151± 18. Fibroblast growth factor 21 (FGF21) is a reported target of PPARα, and has been shown to be increased in liver in response to treatment with a PPARα agonist. However, FGF21 is also increased compensatorily in metabolic stress conditions, e.g., obesity. We found EMPA treatment substantially reduced circulating FGF21 levels in M, while F levels were low regardless of treatment (ng/ml): MC-3.28 ± 1.32; ME- 0.07 ± 0.027; FC- 0.19 ± 0.08, FE- 0.17 ± 0.08 (p = 0.031, 0.044, and 0.033, for treatment, sex, and interaction, respectively). FGF21 levels in liver, site of most production (measured in males only) was likewise reduced by EMPA (84%, p = 0.029, Mann-Whitney test). In contrast, no significant differences were found for renal cortical FGF21 levels. Previously, we showed PPARα whole-body knockout mice had higher renal expression of Na+K+ATPase, which was associated with higher blood pressure. Western blotting of EMPA-treated mice showed the α-1 subunit of Na+K+ATPase, a surrogate marker of proximal tubule transport activity, was significantly increased in the kidney cortex of EMPA-treated mice (band density % MC): MC-100 ± 26; ME- 145 ± 25; FC- 99 ± 22, FE- 175 ± 21 (p = 0.54, 0.016, and 0.52, for treatment, sex, and interaction, respectively). This was not associated with higher blood pressure in EMPA-treated mice, as measured by tail-cuff. Taken together, these findings do not suggest an overall increase in activity of PPARα in kidney or systemically (in liver) with EMPA. The upregulation of carnitine species in kidney may have resulted from an alternative mechanism. Additional studies are warranted to gauge the role of PPARα activation, emanating from a relatively fasted state, with SGLT2 inhibition, in the kidney and in regard to whole body metabolism. Supported by GHUCCTS (Howard and Georgetown, UL1TR001409) pilot award to CE. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Fructose-induced FGF21 secretion does not activate brown adipose tissue in Japanese young men: randomized cross-over and randomized controlled trials

BackgroundHuman brown adipose tissue (BAT) activity is associated with lower body fatness and favorable glucose metabolism. Previous studies reported that oral fructose loading induces postprandial fibroblast growth factor 21 (FGF21) secretion. FGF21 is a known inducer of adipose tissue thermogenesis; however, the effects of diet-induced FGF21 secretion on BAT thermogenesis remain to be elucidated.MethodsThe effects of both single load and daily consumption of fructose on BAT activity were examined using a randomized cross-over trial and a 2-week randomized controlled trial (RCT), respectively. In the cross-over trial, 15 young men consumed a single dose of fructose solution or water and then consumed the other on a subsequent day. The RCT enrolled 22 young men, and the participants were allocated to a group that consumed fructose and a group that consumed water daily for 2 weeks. BAT activity was analyzed using thermography with cold exposure. Plasma FGF21 level was determined by enzyme-linked immunosorbent assay.ResultsIn the cross-over single-load trial, plasma FGF21 levels were significantly increased at 2 h after oral fructose load (p < 0.01); however, there was no significant difference in BAT activity between the fructose load and drinking water. The 2-week RCT revealed that both plasma FGF21 levels and BAT activity were not significantly increased by daily fructose consumption compared to water. Correlation analyses revealed that BAT activity at the baseline and the final measurements were strongly and positively associated with the RCT (r = 0.869, p < 0.001). Changes in BAT activity were significantly and negatively correlated with changes in plasma glucose levels during the 2-week intervention (r = − 0.497, p = 0.022).ConclusionsOral fructose load induces a temporary increase in circulating FGF21 levels; however, this does not activate BAT thermogenesis in healthy young men. Further studies are needed to elucidate the effect of endogenous FGF21 on physiological function.Trial registrationThis study is registered with the University Hospital Medical Information Network in Japan (number 000051761, registered 1 August 2023, retrospectively registered, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000052680).

Increased circulating FGF21 level predicts the burden of metabolic demands and risk of vascular diseases in adults with type 2 diabetes

ObjectivesType 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by chronic hyperglycemia and metabolic stress, involved in the stepwise development of cardiovascular complications. Fibroblast growth factor 21 (FGF21) is a novel hepatokine involved in regulating glucose and lipid metabolism, and has been linked to the prediction, treatment, and improvement of prognosis in multiple cardiovascular diseases (CVDs). The aim of this study is to explore the relationship between FGF21 levels and vascular diseases (VDs) including carotid atherosclerosis (CAS) and hypertension (HP) in patients with T2DM.MethodsBaseline serum FGF21 was determined in a cross-sectional study of 701 patients with T2DM and 258 healthy control.ResultsThe morbidity of CAS was increased in T2DM patients with HP as compared with those without (p < 0.001). The average serum FGF21 level of healthy was [123.9 (67.2-219.3)]. Baseline FGF21 was significantly higher in those who developed CAS or HP than in those who did not [305.9 (177.2-508.4) vs. 197.2 (129.7-308.3) pg/mL, p < 0.001]. In addition, an elevated serum FGF21 was observed in T2DM patients with HP and CAS than that of T2DM patients with CAS or HP [550.5 (312.6-711.3) vs. 305.9 pg/mL, p < 0.001]. Serum FGF21 levels were positively correlated with body mass index and carotid intima media thicknes (p < 0.05), the association remained significant after adjusting for age and T2DM duration. Furthermore, the multinomial logistic regression showed that serum FGF21 was independently associated with CAS and HP in patients with T2DM after adjustment for demographic and traditional VDs risk factors (p < 0.001).ConclusionsBaseline FGF21 is elevated in VDs during diabetes, changes of serum FGF21 levels were appropriately matched to metabolic stress. FGF21can be used as an independent predictor for diagnosing VDs and predicting prognosis.

Association of plasminogen activator inhibitor-1 and fibroblastic growth factor 21 in 3 groups of type 2 diabetes: Without overweight/obesity, free of insulin resistance, and without hepatosteatosis.

The physiological effects of fibroblast growth factor 21 (FGF21), leading to beneficial metabolic outcomes, have been extensively revealed in recent decades. Significantly elevated serum levels of FGF21 in obesity and type 2 diabetes mellitus (T2DM) are referred to as FGF21 resistance. However, Asian population tend to develop metabolic disorders at a lesser degree of obesity than those of Western. This study aimed to explore factors potentially related to serum FGF21 according to the severity of metabolic disorders in patients with T2DM. This cross-sectional study included 176 T2DM patients. The patients were categorized according to whether they had hepatic steatosis (fatty liver index [FLI] ≥ 60), insulin resistance (homeostasis model assessment of insulin resistance [HOMA-R] ≥ median), and/or overweight/obesity (body mass index [BMI] ≥ 25.0 kg/m2). Independent predictors of serum FGF21 were determined using multiple linear regression analysis in these 3 groups of T2DM patients. Circulating FGF21 levels were correlated positively with BMI, abdominal fat areas, leptin, and plasminogen activator inhibitor-1 (PAI-1). After adjustment for potential confounders, multiple linear regression analysis identified leptin as a factor strongly associated with serum FGF21 levels in all patients. Moreover, PAI-1 was a significant predictor of FGF21 in those with FLI < 60, BMI < 25.0 kg/m2, and HOMA-R < median, while leptin was the only independent factor in each of their counterparts. The factors related to serum FGF21 differ according to the severity of metabolic disorders. FGF21 appears to be independently associated with PAI-1 in T2DM patients: without overweight/obesity, those free of insulin resistance, and those without hepatic steatosis.

838-P: Reversion of Nonalcoholic Steatohepatitis by Skeletal-Muscle Directed FGF21 Gene Therapy

Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease, which is driven by the global obesity and type 2 diabetes epidemic. NASH is characterized by liver inflammation and fibrosis that can progress to cirrhosis, liver failure, cancer and death. Currently, NASH is an unmet medical need. Recent studies revealed the therapeutic potential of fibroblast growth factor 21 (FGF21) analogues/mimetics against NASH in pre-clinical models and in human patients, although periodic administrations are required and immunological responses may raise due to the use of engineered, non-native, proteins. Here, we demonstrated that adeno-associated viral (AAV) vector-mediated-FGF21 genetic engineering of skeletal muscle of high-fat diet-fed obese and insulin-resistant mice resulted in increased circulating levels of native FGF21. AAV-FGF21-treatment normalized liver fat content, liver inflammatory and fibrotic markers and counteracted hepatocyte damage, consistent with NASH resolution. It also precluded progression from NASH to cirrhosis and hepato-cellular carcinoma. Moreover, circulating FGF21 reversed adipose tissue hypertrophy and inflammation, increased energy expenditure, normalized glycemia and insulinemia, and increased insulin sensitivity. Scale-up of muscular FGF21 gene transfer to large animals also successfully resulted in long-term secretion of biologically active FGF21 and therapeutic effects in key target tissues, in the absence of adverse events. All these results point out the potential of the AAV-FGF21-mediated gene therapy to treat NASH and support the clinical translation of the approach. Disclosure V. Jimenez: None. V. Sacristán: None. C. Jambrina: None. M. Jaén: None. S.A. Munoz: None. E. Casana: None. M. Garcia: None. I. Grass: None. X. Leon: None. I. Elias: None. A. Ribera: None. G. Elias: None. V. Sanchez: None. A. Casellas: None. T. Ferré: None. M. Molas: None. F. Bosch: None.

1651-P: Elevated FGF21 Levels after Total Pancreatectomy and in Response to Single-Dose Glucagon Receptor Antagonism in Humans

Fibroblast growth factor 21 (FGF21) is a liver-secreted peptide hormone reportedly improving metabolic homeostasis, partly via reduced hunger for sugar, fat, protein and alcohol. Exogenous glucagon has been shown to increase circulating FGF21 levels, but the role of endogenous glucagon for the control of FGF21 secretion remains unknown. To elucidate the relationship between endogenous glucagon and FGF21 in humans, we investigated the effect of chronic pancreatic glucagon depletion and acute glucagon receptor antagonism, respectively, on FGF21 levels. Nine totally pancreatectomized subjects (7 men, 2 women, age 61.3 ± 10.3 years, BMI 22.6 ± 4.8 kg/m2) and 9 matched control subjects (6 men, 3 women, age 65.9 ± 8.8 years, BMI 23.9 ± 2.7 kg/m2) underwent two randomized, double-blinded test days 24 hours after single-dose oral administration of either the glucagon receptor antagonist LY2409021 (300 mg) or placebo. FGF21 levels were measured both in the fasting state and in response to an oral glucose tolerance test (OGTT). The pancreatectomized patients exhibited significantly increased mean fasting FGF21 levels compared to the control subjects (493 ± 429 vs 108 ± 58 pg/mL, P=0.02). In the control subjects, administration of LY2409021 significantly increased mean fasting levels of FGF21 (216 ± 117 vs 108 ± 58 pg/mL, P=0.004) whereas fasting FGF21 levels in the pancreatectomized patients were unaffected by LY2409021. In both groups, FGF21 levels increased in response to the OGTT, with no significant treatment effect of LY2409021. Our results suggest that both chronic glucagon depletion and acute antagonism of the glucagon receptor mediate an increase in FGF21 levels in humans, pointing to direct or indirect effects of glucagon as important regulators of FGF21 secretion. Disclosure M.F.G.Grøndahl: Speaker's Bureau; Novo Nordisk A/S. T.Vilsbøll: Consultant; AstraZeneca, Boehringer Ingelheim Inc., Gilead Sciences, Inc., Eli Lilly and Company, Mundipharma, Merck &amp; Co., Inc., Novo Nordisk A/S, Sanofi, Sun Pharmaceutical Industries Ltd., Bristol-Myers Squibb Company. F.K.Knop: Advisory Panel; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Novo Nordisk, Sanofi, Consultant; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Novo Nordisk, Sanofi, Research Support; Novo Nordisk, Zealand Pharma A/S, Speaker's Bureau; AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Novo Nordisk, Sanofi, Lundbeck. C.T.Juel: None. A.Lund: Speaker's Bureau; Novo Nordisk. S.Haedersdal: Consultant; Novo Nordisk. M.M.Andersen: None. J.S.Svenningsen: None. M.Gillum: None. B.Hartmann: Stock/Shareholder; Bainan Biotech. J.J.Holst: Advisory Panel; Novo Nordisk A/S, Eli Lilly and Company, Board Member; Bainan Biotech, Antag Therapeutics, Consultant; Alphasights, Eli Lilly and Company, ShouTi Pharma Inc., Zealand Pharma A/S, Other Relationship; Novo Nordisk, Novo Nordisk Pharma, Mayo Clinic, Boehringer-Ingelheim, Scohia Pharma Inc., Research Support; ARLA, European Union, Novo Nordisk Foundation. Funding Aase and Ejnar Danielsen's Foundation; Novo Nordisk Foundation (LY2409021); Eli Lilly and Company

Modulation of GCN2/eIF2α/ATF4 Pathway in the Liver and Induction of FGF21 in Young Goats Fed a Protein- and/or Phosphorus-Reduced Diet.

Mammals respond to amino acid (AA) deficiency by initiating an AA response pathway (AAR) that involves the activation of general control nonderepressible 2 (GCN2), phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), and activation of transcription factor 4 (ATF4). In this study, the effects of protein (N) and/or phosphorus (P) restriction on the GCN2/eIF2α/ATF4 pathway in the liver and the induction of fibroblast growth factor 21 (FGF21) in young goats were investigated. An N-reduced diet resulted in a decrease in circulating essential AA (EAA) and an increase in non-essential AA (NEAA), as well as an increase in hepatic mRNA expression of GCN2 and ATF4 and protein expression of GCN2. Dietary N restriction robustly increased both hepatic FGF21 mRNA expression and circulating FGF21 levels. Accordingly, numerous significant correlations demonstrated the effects of the AA profile on the AAR pathway and confirmed an association. Furthermore, activation of the AAR pathway depended on the sufficient availability of P. When dietary P was restricted, the GCN2/eIF2α/ATF4 pathway was not initiated, and no increase in FGF21 was observed. These results illustrate how the AAR pathway responds to N- and/or P-reduced diets in ruminants, thus demonstrating the complexity of dietary component changes.

High circulating fibroblast growth factor-21 levels as a screening marker in fatty pancreas patients.

The study aimed to detect the serum levels of fibroblast growth factor-21 (FGF-21) in fatty pancreas (FP) patients and to investigate their potential clinical value. We screened patients with FP using transabdominal ultrasound. The anthropometric, biochemical and serum levels of FGF-21 were compared between the FP group and the normal control (NC) group. A receiver operating characteristic (ROC) curve was used to evaluate the predictive value of serum FGF-21 for FP patients. Compared with the NC group, body mass index, fasting blood glucose levels, uric acid levels and cholesterol levels of the FP group were significantly higher, while the high-density lipoprotein level was lower. In addition, levels of serum FGF-21, resistin, leptin and tumor necrosis factor-α were significantly higher than those in the NC group, while the serum adiponectin level was lower. Pearson analysis showed serum FGF-21 levels in FP patients were negatively correlated with leptin. The ROC curve showed the best critical value of the serum FGF-21 level in FP patients was 171 pg/mL (AUC 0.744, P=0.002, 95% confidence intervals 0.636-0.852). Serum FGF-21 was closely related to fatty pancreas. Detecting serum FGF-21 levels may help identify the population susceptible to FP.

Abstract 365: Targeting FGF21 inhibits tumor growth and attenuates cachexia in experimental colorectal cancer

Abstract Background: Colorectal cancer (CRC) is frequently accompanied by cachexia, an uncured multi-organ wasting syndrome, debilitating musculoskeletal health, physical function, and overall survival. Fibroblast growth factor 21 (FGF21) is a modulator of musculoskeletal health and metabolism and has been associated with CRC risk and progression. Here, we investigated the effects of tumor derived FGF21 on musculoskeletal health in CRC. Methods: Plasma from CRC patients and preclinical models of CRC (C26, MC38) were assessed for circulating FGF21 levels, and CRC cell lines (C26, MC38, HCT116) were screened for FGF21 expression. Using CRISPR/Cas9 technology, FGF21 was deleted from MC38 cells (KO-MC38). 8-week-old male C57BL/6J mice were subcutaneously injected (1.0x106) with wild-type (WT-MC38) or FGF21-/- (KO-MC38) MC38 tumor cells, while experimental control animals received saline (n = 10-13/group). Animals underwent electrophysiological testing to obtain motor unit number estimation (MUNE) 48 hours prior to euthanasia and were assessed for maximum plantarflexion torque 24 hours prior to euthanasia. At the time of euthanasia, plasma was collected for assessment of systemic FGF21, while tumors and skeletal muscles (gastrocnemius, quadriceps, and tibialis anterior) were excised and weighed. Femur bones were processed for microcomputed tomography (µCT) imaging and analysis. Results: CRC patients and MC38 tumor hosts demonstrated elevated circulating plasma FGF21 (p&amp;lt;0.05) compared to controls. Gene expression of CRC cells revealed an 11-fold increase of FGF21 in MC38 compared to C26 and HCT116 cells. WT-MC38 tumor hosts had elevated plasma FGF21 (4-fold; p&amp;lt;0.05) compared to control, which was unchanged in KO-MC38 hosts. In line with the development of cachexia, WT-MC38 hosts displayed reductions in muscle mass (gastrocnemius: -5%; p&amp;lt;0.05, quadriceps: -10%; p&amp;lt;0.01, tibialis anterior: -8%; p&amp;lt;0.01), MUNE (-31%; p&amp;lt;0.01), and plantarflexion torque (-10%; p&amp;lt;0.05). Meanwhile, µCT of femur bones demonstrated reductions in trabecular bone volume fraction (BV/TV: -30%; p&amp;lt;0.05) and cortical cross-sectional thickness (Cs.Th: -14%; p&amp;lt;0.05) in WT-MC38 hosts compared to experimental controls. Conversely, when compared to WT-MC38, KO-MC38 hosts had preserved skeletal muscle mass (gastrocnemius: +7%; p&amp;lt;0.01, quadriceps: +13%; p&amp;lt;0.001, tibialis anterior: +8%; p&amp;lt;0.001), MUNE (+47%; p&amp;lt;0.01), plantarflexion torque (+8%; p&amp;lt;0.05), and bone mass (BV/TV: +69%; p&amp;lt;0.001, Cs.Th: +23%; p&amp;lt;0.001). Strikingly, the mass of KO-MC38 tumors was reduced 75% (p&amp;lt;0.01) compared to WT-MC38 tumors. Conclusion: Our data suggest that targeting CRC-derived FGF21 halts tumor growth, resulting in preservation of musculoskeletal health and function. Thus, counteracting tumor-derived FGF21 may serve as a therapeutic intervention against the progression of cancer and cancer-associated cachexia. Citation Format: Fabrizio Pin, Anika Shimonty, Joshua Robert Huot. Targeting FGF21 inhibits tumor growth and attenuates cachexia in experimental colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 365.

Fibroblast growth factor 21 is an independent predictor of prevalent and incident obstructive sleep apnea

Fibroblast growth factor 21 (FGF21) is a metabolic regulator and a potential biomarker of metabolic diseases. Limited data are available on the association between FGF21 and obstructive sleep apnea (OSA), which is considered as a manifestation of metabolic syndrome. In the present cross-sectional and longitudinal analyses, the FGF21 level was associated with OSA. This analysis of two clinical cohorts is the first to show that the FGF21 level increased significantly with OSA severity and was an independent predictor of incident OSA in Chinese adults. The circulating FGF21 level could serve as a potential serum biomarker of OSA and its comorbidities and thus aid risk evaluation and early intervention.

Effect of Aerobic Exercise Training on Circulating Fibroblast Growth Factor-21 Response to Glucose Challenge in Overweight and Obese Men: A Pilot Study

Fibroblast growth factor-21 (FGF21) is a liver-derived hormone that lowers blood glucose. Although aerobic exercise training also lowers blood glucose, its effect on circulating FGF21levels remains obscure. This study aimed to examine the effect of aerobic exercise training on serum FGF21 levels in overweight and obese men. A total of 14 overweight/obese men were included in the analyses. Participants attended supervised aerobic exercise training for 12 weeks (three times per week) and completed the standard oral glucose tolerance test pre- and post-exercise training. Plasma glucose, serum insulin, and serum FGF21 levels were measured at fasting and 60 and 120 min after glucose loading. The exercise training reduced plasma glucose and serum FGF21 levels during glucose loading (p<0.05). The change in the area under the curve of plasma glucose was positively correlated with that in the area under the curve of serum FGF21 (r s =0.569, p=0.034). Lowering postprandial circulating FGF21 levels may be associated with the improved glucose tolerance induced by habitual aerobic exercise in overweight and obese men.

Obesity-resistance of UCP1-deficient mice associates with sustained FGF21 sensitivity in inguinal adipose tissue.

Metabolic diseases represent the major health burden of our modern society. With the need of novel therapeutic approaches, fibroblast growth factor 21 (FGF21) is a promising target, based on metabolic improvements upon FGF21 administration in mice and humans. Endogenous FGF21 serum levels, however, are increased during obesity-related diseases, suggesting the development of FGF21 resistance during obesity and thereby lowering FGF21 efficacy. In uncoupling protein 1 knockout (UCP1 KO) mice, however, elevated endogenous FGF21 levels mediate resistance against diet-induced obesity. Here, we show that after long-term high fat diet feeding (HFD), circulating FGF21 levels become similarly high in obese wildtype and obesity-resistant UCP1 KO mice, suggesting improved FGF21 sensitivity in UCP1 KO mice. To test this hypothesis, we injected FGF21 after long-term HFD and assessed the metabolic and molecular effects. The UCP1 KO mice lost weight directly upon FGF21 administration, whereas body weights of WT mice resisted weight loss in the initial phase of the treatment. The FGF21 treatment induced expression of liver Pck1, a typical FGF21-responsive gene, in both genotypes. In iWAT, FGF21-responsive genes were selectively induced in UCP1 KO mice, strongly associating FGF21-sensitivity in iWAT with healthy body weights. Thus, these data support the concept that FGF21-sensitivity in adipose tissue is key for metabolic improvements during obesogenic diets.

FGF21 response to sucrose is associated with BMI and dorsal striatal signaling in humans.

This study examined associations between BMI and dietary sugar intake with sucrose-induced fibroblast growth factor 21 (FGF21) and whether circulating FGF21 is associated with brain signaling following sucrose ingestion in humans. A total of 68 adults (29 male; mean [SD), age 23.2 [3.8] years; BMI 27.1 [4.9] kg/m2 ) attended visits after a 12-hour fast. Plasma FGF21 was measured at baseline and at 15, 30, and 120 minutes after sucrose ingestion (75 g in 300 mL of water). Brain cerebral blood flow responses to sucrose were measured using arterial spin labeling magnetic resonance imaging. Higher circulating FGF21 levels were associated with reduced blood flow in the striatum in response to sucrose (β = -7.63, p = 0.03). This association was greatest among persons with healthy weight (β = -15.70, p = 0.007) and was attenuated in people with overweight (β = -4.00, p = 0.63) and obesity (β = -12.45, p = 0.13). BMI was positively associated with FGF21 levels in response to sucrose (β = 0.53, p = 0.02). High versus low dietary sugar intake was associated with greater FGF21 responses to acute sucrose ingestion in individuals with healthy weight (β = 8.51, p = 0.04) but not in individuals with overweight or obesity (p > 0.05). These correlative findings support evidence in animals showing that FGF21 acts on the brain to regulate sugar consumption through a negative feedback loop.

Association of serum fibroblast growth factor 21 with kidney function in a population-based Chinese cohort.

Fibroblast growth factor 21 (FGF21) plays a role in kidney disease. Circulating FGF21 levels are associated with kidney function and progression in patients with type 2 diabetes (T2D). However, the association between FGF21 and kidney function in the general population is still lacking. The aim of this study was to determine the association between FGF21 and kidney function and its progression in a Chinese cohort.A total of 2425 participants from a population-based survey of diabetes and metabolic syndrome in Pinggu, Beijing, were included in the baseline analysis. After a median follow-up of 12 months, 2402 participants with baseline estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 were analyzed in the longitudinal study. The progression of kidney function was defined as an eGFR decline exceeding 3.3% per year. Serum FGF21 levels were measured using an enzyme-linked immunosorbent assay at baseline.Male sex, body mass index (BMI), homeostasis model assessment of insulin resistance, higher levels of low-density lipoprotein cholesterol (LDL-c), uric acid, and FGF21 were associated with increased odds of a lower eGFR at baseline. The association of FGF21 with lower eGFR was independent of all the potential confounders in multivariable logistic regression (odds ratio, 1.005; 95% confidence interval 1.002–1.008). However, FGF21 was not associated with eGFR decline in the longitudinal analysis (odds ratio, 1.000; 95% confidence interval 0.998–1.001).Increased serum FGF21 levels were independently associated with lower eGFR in this nonmedicated general population. FGF21 could be a biomarker of kidney function in the general population.

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

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. 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. 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. 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.

Circulating fibroblast growth factor 21 links hemodynamics with kidney function in middle-aged and older adults: A mediation analysis.

Altered hemodynamics are commonly observed in individuals with declining renal function; however, the pathophysiological mechanisms linking renal dysfunction and hemodynamics have not been fully elucidated. Fibroblast growth factor 21 (FGF21), which upregulates sympathetic nerve activity, can alter systemic hemodynamics, and its level can increase as renal function declines. This study aimed to determine the associations among circulating FGF21 levels, hemodynamics, and renal function in middle-aged and older adults. In a total of 272 middle-aged and older adults (age range: 46-83 years), estimated glomerular filtration rate (eGFR), hemodynamics (brachial and aortic blood pressure and aortic pulse wave velocity [PWV]), and serum FGF21 levels were measured. For mediation analysis, hemodynamic parameters were entered as outcomes. eGFR or log-transformed urinary albumin and creatinine ratio (UACR) and log-transformed serum FGF21 levels were set as the predictors and mediator, respectively. According to multivariable regression models after adjusting for potential covariates, serum FGF21 levels were significantly associated with brachial systolic blood pressure (β = 0.140), pulse pressure (β = 0.136), and aortic PWV (β = 0.144). Mediation analyses showed that serum FGF21 levels significantly mediated the relationship of eGFR with brachial systolic blood pressure (indirect effect [95% confidence interval]: -0.032 [-0.071, -0.002]), pulse pressure (-0.019 [-0.041, -0.001]), and aortic PWV (-0.457 [-1.053, -0.021]) and the relationship of UACR with aortic PWV (7.600 [0.011, 21.148]). These findings suggest that elevated circulating FGF21 levels partially mediate the association of elevated blood pressure and/or aortic stiffness with renal dysfunction in middle-aged and older adults.

Acute sleep loss alters circulating fibroblast growth factor 21 levels in humans: A randomised crossover trial.

The hormone fibroblast growth factor 21 (FGF21) modulates tissue metabolism and circulates at higher levels in metabolic conditions associated with chronic sleep-wake disruption, such as type 2 diabetes and obesity. In the present study, we investigated whether acute sleep loss impacts circulating levels of FGF21 and tissue-specific production, and response pathways linked to FGF21. A total of 15 healthy normal-weight young men participated in a randomised crossover study with two conditions, sleep loss versus an 8.5-hr sleep window. The evening before each intervention, fasting blood was collected. Fasting, post-intervention morning skeletal muscle and adipose tissue samples underwent quantitative polymerase chain reaction and DNA methylation analyses, and serum FGF21 levels were measured before and after an oral glucose tolerance test. Serum levels of FGF21 were higher after sleep loss compared with sleep, both under fasting conditions and following glucose intake (~27%-30%, p=0.023). Fasting circulating levels of fibroblast activation protein, a protein which can degrade circulating FGF21, were not altered by sleep loss, whereas DNA methylation in the FGF21 promoter region increased only in adipose tissue. However, even though specifically the muscle exhibited transcriptional changes indicating adverse alterations to redox and metabolic homeostasis, no tissue-based changes were observed in expression of FGF21, its receptors, or selected signalling targets, in response to sleep loss. In summary, we found that acute sleep loss resulted in increased circulating levels of FGF21 in healthy young men, which may occur independent of a tissue-based stress response in metabolic peripheral tissues. Further studies may decipher whether changes in FGF21 signalling after sleep loss modulate metabolic outcomes associated with sleep or circadian disruption.

P–389 The relationship between serum hormone profiles and missed abortion in humans

Abstract Study question Are circulating profiles of metabolic-related hormones also associated with the missed abortion (MA) in humans? Summary answer Serum levels of fatty acid-binding protein–4 (FABP4) and fibroblast growth factor 21 (FGF21) are positively associated with MA. What is known already A cluster of endocrine hormones, including FABP4, FGF21, adiponectin, lipocalin–2 (LCN2), exhibit pleiotropic effects on regulating systematic metabolism. Serum levels of them are associated with gestational obesity and diabetes and affect pregnancy outcomes, however, the relationship between their circulating profiles and MA is under-investigated. Study design, size, duration 78 patients with MA and 86 healthy pregnant subjects matching on maternal age and body mass index (BMI) were nested from a prospective cohort in the Chinese population. Participants/materials, setting, methods Fasting serum samples from all participants were collected to test their serum levels of FGF21, FABP4, adiponectin, and LCN2 by enzyme-linked immunosorbent assay method (ELISA). Main results and the role of chance There were no significant differences in circulating profiles of adiponectin and LCN2 between MA patients and healthy pregnant subjects. By contrast, circulating levels of FGF21 and FABP4 were significantly and independently elevated in patients with MA relative to control cases even after adjusting confounding factors (for FGF21: MA: 28.96 ± 2.17 ng/ml; HP: 19.18 ± 1.12 ng/ml, P &amp;lt; 0.001, for FABP4: MA: 152.50 ± 9.31 pg/ml; HP: 90.86 ± 4.14 pg/ml, P &amp;lt; 0.001). Linear regression analysis showed, FGF21 raised every 10 pg/ml contributed to a 24% (95% CI: 15% - 34%) increase in the risk of MA, whereas the OR of FABP4 for the risk of MA was 1.052 (95% CI: 1.022 –1.088). Furthermore, using serum FGF21 level or FABP4 levels discriminated MA from healthy controls with an area under the operating characteristic’s curve (AUROC) of 0.81 (95% CI 0.76–0.92) and 0.70 (95% CI 0.62 - 0.78), respectively. Limitations, reasons for caution The study is limited by the sample size. In addition, our results were based-on Chinese population, whether it could be observed in other ethics group remain to be investigated. Meanwhile, the cause-effect relationship between increased serum FGF21 level and MA remains to be explored. Wider implications of the findings: Our data would suggest that serum levels of FGF21 and FABP4 are associated with MA. Moreover, circulating FGF21 levels may serve as a potential diagnostic biomarker for the recognition of M. Trial registration number IRB Ref. No.: KY201913

Circulating fibroblast growth factor 21, renal function, and aortic hemodynamics in middle‐aged and older adults: a mediation analysis

Introduction A decline in renal function is associated with aortic stiffening and hypertension. However, the pathophysiological mechanisms behind the relation between renal dysfunction and altered aortic hemodynamics have not been fully elucidated. Fibroblast growth factor 21 (FGF21), which is an endocrine substance that is mainly secreted from the liver, has been reported to alter aortic hemodynamics via upregulation of sympathetic nerve activity. On the other hand, it has been demonstrated that circulating FGF21 levels were increased with decline of renal function. These findings have led us to hypothesize that elevated circulating levels of FGF21 may mediate the link between renal dysfunction, advanced aortic stiffness, and elevated blood pressure. Therefore, this study aimed to determine whether circulating FGF21 levels may mediate altered aortic hemodynamics in middle-aged and older adults with declined renal function. Methods Two-hundred ninety-nine middle-aged and older adults (age range: 46-83 years, percentage of men: 36%) were included in this study. To assess renal function, the estimated glomerular filtration rate (eGFR) was measured. The range of eGFR was 18 to 145 mL/min/1.73m2. Aortic blood pressure was measured by applanation tonometry. Aortic stiffness was measured by carotid-femoral pulse wave velocity (cfPWV) using a standard procedure. Serum FGF21 levels were measured by ELISA. In the mediation analysis, aortic blood pressure and stiffness (cfPWV) were entered as outcomes respectively. The predictor and mediator were set for eGFR and log-transformed serum FGF21 levels respectively. Results Serum FGF21 levels were significantly correlated with aortic pulse pressure (r = 0.200) and cfPWV (r = 0.326). Moreover, eGFR was negatively correlated with aortic pulse pressure (r = −0.188) and cfPWV (r = −0.390). In multivariable regression models adjusting for the potential covariates including age, sex, body mass index, heart rate, current smoking status, anti-hypertensive, lipid lowering, and hypoglycemic medication use, serum FGF21 level was independently associated with aortic pulse pressure (β = 0.132) and cfPWV (β = 0.173). The mediation analysis demonstrated that serum FGF21 significantly mediates the relations of eGFR with aortic pulse pressure (indirect effect [95% CI]: −0.018 [−0.036, −0.003]) and cfPWV (−0.592 [−1.122, −0.184]). The percentages of these indirect effects were 33% and 34% of the total effect respectively. Conclusion The present study showed that circulating FGF21 level is independently associated with aortic hemodynamic parameters in middle-aged and older adults. Also, mediation analysis demonstrated that circulating FGF21 level mediated the association of renal function with aortic pulse pressure and stiffness. These findings suggest that elevated blood pressure and advanced aortic stiffness with decreased renal function may be partly mediated by the elevated circulating level of FGF21 in middle-aged and older adults.

Methionine restriction alleviates age-associated cognitive decline via fibroblast growth factor 21

Methionine restriction (MR) extends lifespan and delays the onset of aging-associated pathologies. However, the effect of MR on age-related cognitive decline remains unclear. Here, we find that a 3-month MR ameliorates working memory, short-term memory, and spatial memory in 15-month-old and 18-month-old mice by preserving synaptic ultrastructure, increasing mitochondrial biogenesis, and reducing the brain MDA level in aged mice hippocampi. Transcriptome data suggest that the receptor of fibroblast growth factor 21 (FGF21)-related gene expressions were altered in the hippocampi of MR-treated aged mice. MR increased FGF21 expression in serum, liver, and brain. Integrative modelling reveals strong correlations among behavioral performance, MR altered nervous structure-related genes, and circulating FGF21 levels. Recombinant FGF21 treatment balanced the cellular redox status, prevented mitochondrial structure damages, and upregulated antioxidant enzymes HO-1 and NQO1 expression by transcriptional activation of Nrf2 in SH-SY5Y cells. Moreover, knockdown of Fgf21 by i.v. injection of adeno-associated virus abolished the neuroprotective effects of MR in aged mice. In conclusion, the MR exhibited the protective effects against age-related behavioral disorders, which could be partly explained by activating circulating FGF21 and promoting mitochondrial biogenesis, and consequently suppressing the neuroinflammation and oxidative damages. These results demonstrate that FGF21 can be used as a potential nutritional factor in dietary restriction-based strategies for improving cognition associated with neurodegeneration disorders.