Relationship of fibroblast growth factor 21 with baseline and new on-study microvascular disease in the Fenofibrate Intervention and Event Lowering in Diabetes study

Circulating AFABP, FGF21, and PEDF Levels as Prognostic Biomarkers of Sight-threatening Diabetic Retinopathy

CONTEXT

Adipocyte fatty acid-binding protein (AFABP), fibroblast growth factor 21 (FGF21), and pigment epithelium-derived factor (PEDF) are 3 diabetes-related biomarkers whose circulating levels had been shown to associate with nephropathy progression in Chinese patients with type 2 diabetes.

OBJECTIVE

Here, we evaluated and compared their prospective associations with the development of sight-threatening DR (STDR), another important diabetic microvascular complication.

METHODS

Baseline serum AFABP, PEDF, and FGF21 levels were measured in 4760 Chinese individuals with type 2 diabetes and without STDR at baseline. The associations of these biomarkers with incident STDR were analyzed using Cox regression analysis.

RESULTS

Among these 4760 participants (mean diabetes duration of 11 years and ≥ 50% with nonproliferative DR at baseline), 172 participants developed STDR over a median follow-up of 8.8 years. Participants with incident STDR had comparable baseline serum FGF21 levels but significantly higher baseline serum AFABP and PEDF levels (both P < .001) than those without. However, in multivariable Cox regression analysis, only serum AFABP remained independently associated with incident STDR (hazard ratio 1.28; 95% CI, 1.05-1.55; P = .013). The addition of serum AFABP to a clinical model of conventional STDR risk factors including diabetes duration, glycemic control, albuminuria, and baseline DR status significantly improved the c statistics (P < .001), net reclassification index (P = .0027), and integrated discrimination index (P = .033) in predicting incident STDR among participants without DR or with mild DR at baseline.

CONCLUSION

Among the 3 diabetes-related biomarkers, serum AFABP level appeared to be a more clinically useful biomarker for predicting incident STDR in type 2 diabetes.

Relationship of fibroblast growth factor 21 with the prevalence and progression of vascular and valvular calcification: Multi-ethnic study of atherosclerosis

BACKGROUND

Elevated circulating levels of fibroblast growth factor 21 (FGF21) are associated with cardiovascular disease (CVD). Therefore, we investigated the relationship of plasma FGF21 with calcification at different vascular and valvular sites.

METHODS

A total of 5786 participants, free of clinically apparent CVD at baseline and with valid data on plasma FGF21 and calcification (Agatston score, volume and density) at coronary arteries, thoracic arteries, mitral and aortic valves, and aortic valve ring, were included in the analysis. Vascular calcification was measured at 2-3 follow-up visits.

RESULTS

At baseline, higher FGF21 levels were associated with prevalent descending thoracic aortic calcification (DTAC) (prevalence ratio = 1.06 [95% CI 1.01-1.11] per SD increase in log-transformed unit, P = 0.016). Among participants without prevalent calcification, higher FGF21 levels were associated with incident DTAC (relative risk [RR] = 1.13 [95% CI 1.04-1.22], P = 0.002). Among all participants, higher FGF21 levels were also associated with the progression of DTAC score and volume (RR = 1.07 [95% CI 1.03-1.12] and 1.08 [95% CI 1.03-1.12] respectively, both P < 0.01). No significant association of FGF21 was found for prevalence (prevalence ratio = 0.89-1.05), incidence (RR = 0.97-1.16) and progression of calcification (RR = 0.94-1.14) at the other sites.

CONCLUSION

Higher FGF21 levels were associated with the presence, incidence and progression of DTAC. However, the magnitude of this association was similar to those of the non-significant associations of FGF21 levels with calcifications at other sites. Further research is needed to assess the potential of FGF21 as a biomarker for vascular calcification.

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

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

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.

Fibroblast growth factor 21 attenuates salt-sensitive hypertension-induced nephropathy through anti-inflammation and anti-oxidation mechanism

BACKGROUND

Patients with salt-sensitive hypertension are often accompanied with severe renal damage and accelerate to end-stage renal disease, which currently lacks effective treatment. Fibroblast growth factor 21 (FGF21) has been shown to suppress nephropathy in both type 1 and type 2 diabetes mice. Here, we aimed to investigate the therapeutic effect of FGF21 in salt-sensitive hypertension-induced nephropathy.

METHODS

Changes of FGF21 expression in deoxycorticosterone acetate (DOCA)-salt-induced hypertensive mice were detected. The influence of FGF21 knockout in mice on DOCA-salt-induced nephropathy were determined. Recombinant human FGF21 (rhFGF21) was intraperitoneally injected into DOCA-salt-induced nephropathy mice, and then the inflammatory factors, oxidative stress levels and kidney injury-related indicators were observed. In vitro, human renal tubular epithelial cells (HK-2) were challenged by palmitate acid (PA) with or without FGF21, and then changes in inflammation and oxidative stress indicators were tested.

RESULTS

We observed significant elevation in circulating levels and renal expression of FGF21 in DOCA-salt-induced hypertensive mice. We found that deletion of FGF21 in mice aggravated DOCA-salt-induced nephropathy. Supplementation with rhFGF21 reversed DOCA-salt-induced kidney injury. Mechanically, rhFGF21 induced AMPK activation in DOCA-salt-treated mice and PA-stimulated HK-2 cells, which inhibited NF-κB-regulated inflammation and Nrf2-mediated oxidative stress and thus, is important for rhFGF21 protection against DOCA-salt-induced nephropathy.

CONCLUSION

These findings indicated that rhFGF21 could be a promising pharmacological strategy for the treatment of salt-sensitive hypertension-induced nephropathy.

Fibroblast Growth Factor 21 and Metabolic Dysfunction in Women with a Prior Glucose-Intolerant Pregnancy

OBJECTIVE

We sought to determine if there is an association between fibroblast growth factor 21 (FGF21) levels and a history of gestational diabetes mellitus (GDM) in women with and without metabolic dysfunction, defined as a diagnosis of metabolic syndrome or type 2 diabetes (T2DM), 5 to 10 years following participation in a multiple cohort GDM study.

STUDY DESIGN

At 5 to 10 years after index pregnancy, women underwent a follow-up visit and were categorized as having no metabolic syndrome, metabolic syndrome, or T2DM. FGF21 levels were compared between women who did and did not have a history of GDM using multivariable linear regression.

RESULTS

Among 1,889 women, 950 underwent follow-up and 796 had plasma samples analyzed (413 GDM and 383 non-GDM). Total 30.7% of women had been diagnosed with T2DM or metabolic syndrome. Overall, there was no difference in median FGF21 levels in pg/mL between the prior GDM and non-GDM groups (p = 0.12), and the lack of association was observed across all three metabolic categories at follow-up (p for interaction = 0.70).

CONCLUSION

There was no association between FGF21 levels and prior history of mild GDM in women with and without metabolic dysfunction 5 to 10 years after the index pregnancy (ClinicalTrials.gov number, NCT00069576, original trial).

The serum fibroblast growth factor 21 is correlated with retinopathy in patients with type 2 diabetes mellitus

AIMS

despite advances in blood glucose control, the incidence of sight loss has not decreased in patients with diabetes. Several growth factors have been suggested as factors associated with diabetic retinopathy pathogenesis. In the current cross-sectional study, we examined the relationship between FGF21 and retinopathy as a microvascular complication of diabetes.

METHODS

Adult patients with type 2 diabetes mellitus (T2DM); were recruited and evaluated for retinopathy. Different clinical and biochemical factors, such as FGF21 were assessed and compared between groups.

RESULTS

91 T2DM patients with retinopathy, 93 T2DM patients without retinopathy, and 86 healthy control subjects were recruited. FGF21 was significantly different between the three groups (P<0.001). In the multivariate logistic regression model obesity, cholesterol, HbA1c, and FGF21 were associated with diabetic retinopathy. ROC curve analysis was used for establishing a cut-off FGF21 concentration to predict diabetic retinopathy. The area under the curve in this model was 0.992. The best cut-off point for predicting retinopathy based on FGF21 was greater than 312 pg/ml, with a sensitivity of 97.80% and specificity of 96.77%.

CONCLUSION

FGF21 was associated with diabetic retinopathy and can be suggested as a surrogate diagnostic marker in the diagnosis of this state.

The relationship of neutrophil elastase and proteinase 3 with risk factors, and chronic complications in type 2 diabetes: A Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) sub-study

INTRODUCTION

Neutrophil elastase (NE) and proteinase 3 (PR3) are novel inflammation biomarkers. We investigated their associations with chronic complications, determinants of biomarker levels and effects of fenofibrate in patients with type 2 diabetes mellitus (T2DM) from Fenofibrate Intervention and Event Lowering in Diabetes study.

METHODS

Plasma NE and PR3 levels were quantified at baseline (n = 2000), and relationships with complications over 5-years assessed. Effects of fenofibrate on biomarker levels (n = 200) were determined at four follow-up visits.

RESULTS

Higher waist-to-hip ratio, homocysteine and C-reactive protein and lower apoA-II were determinants of higher NE and PR3 levels. Higher NE levels were associated with on-trial stroke and cardiovascular mortality, and higher PR3 levels with on-trial stroke, but associations were not significant after adjustment for confounding factors. Although higher NE and PR3 levels were associated with baseline total microvascular disease, only NE levels were associated with on-trial neuropathy or amputation. These associations were not significant after adjusting for multiple comparisons. NE and PR3 levels did not change with fenofibrate.

CONCLUSIONS

In T2DM plasma NE and PR3 levels are associated with vascular risk factors, and total microvascular disease at baseline, but on rigorous analyses were not associated with on-trial complications. Levels were not changed by fenofibrate.

FGF21 and Chronic Kidney Disease

The global nephrology community recognizes the increasing burden of kidney disease and its poor health outcomes in the general population. Given this, strategies to establish early diagnosis, improve understanding of the natural course and develop novel therapeutic interventions to slow progression and reduce complications are encouraged. Fibroblast growth factor 21 (FGF21), a member of the endocrine FGF subfamily, has emerged as a master homeostasis regulator of local and systemic lipid, glucose and energy metabolism. In addition, FGF21 should be considered an autonomic and endocrine regulator of stress responses in general. Promising results has been shown in both dysmetabolic animal models and metabolic disease patients after pharmacological administration of FGF21 analogs. The association of FGF21 with renal function has been studied for more than ten years. However, the functional role of FGF21 in the kidney is still poorly understood. This review summarizes the biological effects of FGF21 and discusses what is currently known about this hormone and chronic kidney disease, highlighting important gaps that warrant further research.

Association between serum fibroblast growth factor 21 level and sight-threatening diabetic retinopathy in Chinese patients with type 2 diabetes

INTRODUCTION

We conducted this cross-sectional study to explore the relationship between serum fibroblast growth factor 21 (FGF21) level and sight-threatening diabetic retinopathy (STDR).

RESEARCH DESIGN AND METHODS

A total of 654 patients with type 2 diabetes were recruited. Diabetic retinopathy (DR) was evaluated by the bilateral retinal photography, and patients were assigned into groups of no DR (NDR) (n=345, 52.75%), non-sight-threatening diabetic retinopathy (NSTDR) (n=207, 31.65%), involving patients with mild or moderate non-proliferative retinopathy (NPDR) and STDR (n=102, 15.60%), including those with severe NPDR or proliferative diabetic retinopathy (PDR). Serum FGF21 levels were quantified by a sandwich ELISA. Patients were divided into quartiles according to their serum FGF21 level.

RESULTS

There was a significant difference in serum FGF21 level among the three groups of patients (p<0.01). Compared with other quartiles (Q1-Q3), the patients in Q4 had a higher prevalence of DR and STDR (p<0.05). Compared with Q1, a positive association was observed between serum FGF21 level and DR in Q3 and Q4 (p<0.01). After adjusting for age, gender and other risk factors, serum FGF21 level in Q4 was found to be associated with increased risk of DR and STDR (p<0.01). Serum FGF21 level was noted as an independent risk factor for DR and STDR (p<0.01). Serum FGF21 level >478.76 pg/mL suggested the occurrence of DR and that level >554.69 pg/mL indicated STDR (p<0.01).

CONCLUSIONS

Serum FGF21 level was a biomarker for the risk of developing DR or STDR. The risk of STDR increased when the serum FGF21 level of patients with type 2 diabetes was >554.69 pg/mL.

Relationships of adipocyte-fatty acid binding protein and lipocalin 2 with risk factors and chronic complications in type 2 diabetes and effects of fenofibrate: A fenofibrate Intervention and event lowering in diabetes sub-study

AIMS

To investigate determinants of circulating levels of adipocyte-fatty acid binding protein (A-FABP) and lipocalin-2 (LCN2), their relationships with cardiovascular disease (CVD) and microvascular events, and effects of fenofibrate in type 2 diabetes (T2D).

METHODS

A-FABP and LCN2 were quantified in baseline plasma from 2000 T2D adults in a Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial sub-study and correlates thereof determined. In a subset (n = 200) adipokines were also measured on-trial.

RESULTS

Female sex, older age, higher body mass index (BMI), HbA1c, insulin resistance index, triglycerides, plasma creatinine and homocysteine, shorter diabetes duration, and use of oral hypoglycaemic agents alone were independent determinants of higher A-FABP. Higher BMI, fibrinogen and homocysteine, Caucasian race, and lower fasting glucose, HDL-cholesterol, apolipoprotein A-II and estimated glomerular filtration rate were independent predictors of higher LCN2 levels. Baseline A-FABP and LCN2 levels were associated with multiple new CVD and microvascular events over 5-years, though significance was lost after risk factor adjustment. Fenofibrate increased A-FABP but did not change LCN2 levels.

CONCLUSIONS

Baseline plasma A-FABP and LCN2 levels were associated with concurrent CVD risk factors, and on-trial chronic complications, likely mediated via traditional risk factors. Fenofibrate increased A-FABP modestly but did not affect LCN2 levels.

CLINICAL TRIAL REGISTRATION

ISRCTN 64783481.

Relationship of fibroblast growth factor 21 with kidney function and albuminuria: multi-ethnic study of atherosclerosis

BACKGROUND

Fibroblast growth factor 21 (FGF21) may play a role in the development of chronic kidney disease (CKD). We therefore investigated the relationship of plasma FGF21 levels with kidney function and albuminuria in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

The analysis included 5724 MESA participants ages 45-84 years between 2000 and 2002, free of clinically apparent cardiovascular disease (CVD). Participants were followed up in person at four additional clinic visits over 10 years. Plasma FGF21 levels were measured at baseline examination by enzyme-linked immunosorbent assay. Kidney function was assessed by estimated glomerular filtration rate (eGFR). Outcomes were urinary albumin:creatinine ratio (UACR) progression, incident CKD by eGFR (reaching eGFR <60 mL/min/1.73 m2 with eGFR loss rate ≥1 mL/min/1.73 m2 per year) and rapid kidney function decline (eGFR decline >5%/year).

RESULTS

At baseline, higher FGF21 levels, assessed as both continuous and categorical quartile variables, were significantly associated with lower eGFR and higher UACR, after adjusting for demographic, socioeconomic and other confounding factors [adjusted mean differences of -2.63 mL/min/1.73 m2 in eGFR and 0.134 in log normally transformed UACR (mg/g) for the highest FGF21 quartile compared with the lowest quartile, all P < 0.001]. However, in longitudinal analyses, baseline FGF21 levels did not predict incident CKD by eGFR, rapid kidney function decline or UACR progression. No significant interaction with sex and race/ethnicity was found (all P > 0.05).

CONCLUSIONS

Our study does not support a role of FGF21 as a biomarker for predicting kidney function decline or albuminuria in adults free of clinically apparent CVD at baseline.

Organokines in disease

Studies have linked obesity, metabolic syndrome, type 2 diabetes, cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD) and dementia. Their relationship to the incidence and progression of these disease states suggests an interconnected pathogenesis involving chronic low-grade inflammation and oxidative stress. Metabolic syndrome represents comorbidities of central obesity, insulin resistance, dyslipidemia, hypertension and hyperglycemia associated with increased risk of type 2 diabetes, NAFLD, atherosclerotic CVD and neurodegenerative disease. As the socioeconomic burden for these diseases has grown signficantly with an increasing elderly population, new and alternative pharmacologic solutions for these cardiometabolic diseases are required. Adipose tissue, skeletal muscle and liver are central endocrine organs that regulate inflammation, energy and metabolic homeostasis, and the neuroendocrine axis through synthesis and secretion of adipokines, myokines, and hepatokines, respectively. These organokines affect each other and communicate through various endocrine, paracrine and autocrine pathways. The ultimate goal of this review is to provide a comprehensive understanding of organ crosstalk. This will include the roles of novel organokines in normal physiologic regulation and their pathophysiological effect in obesity, metabolic syndrome, type 2 diabetes, CVD, NAFLD and neurodegenerative disorders.

Relationship of fibroblast growth factor 21 with subclinical atherosclerosis and cardiovascular events: Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

Fibroblast growth factor 21 (FGF21) has been suggested as a novel biomarker for cardiovascular disease (CVD), especially in people with high CVD risk. However, it is not known whether FGF21 is a CVD biomarker in an initially healthy cohort. We therefore investigated the relationship of plasma FGF21 levels with measures of subclinical atherosclerosis and cardiovascular events in Multi-Ethnic Study of Atherosclerosis participants without known CVD at baseline.

METHODS

A total of 5788 participants had plasma FGF21 levels measured at the baseline exam (2000-2002). Carotid intima-media thickness (IMT), ankle-brachial index (ABI) and coronary artery calcification (CAC) were measured at baseline. Participants were followed up for incident CVD events over a median period of 14 years.

RESULTS

In cross-sectional analyses adjusting for socio-demographic variables, participants with higher FGF21 levels had higher carotid IMT, lower ABI, and higher prevalence of CAC (p < 0.001). However, these associations were not significant after simultaneously adjusting for demographic, socioeconomic and lifestyle factors, traditional CVD risk factors, and biomarkers of inflammation and hemostasis. Among 5768 patients with follow-up data, 820 developed incident CVD endpoints. Higher baseline FGF21 levels were not associated with the risk for incident CVD endpoints after adjusting for multiple confounding factors (odds ratio 1.03; 95% confidence interval, 0.94-1.12, per SD increase in ln-transformed FGF21 levels).

CONCLUSIONS

Although FGF21 has been suggested as a CVD biomarker for people with high CVD risk, our findings do not support a role of FGF21 as a CVD biomarker in those without a history of CVD.

Fibroblast growth factor 21 association with subclinical atherosclerosis and arterial stiffness in type 2 diabetes

AIM

To evaluate the association of serum FGF21 with subclinical atherosclerosis and pulse wave velocity, a marker of arterial stiffness, in type 2 diabetes Egyptian patients.

PATIENTS AND METHODS

Fasting serum FGF21 was measured in 120 type 2 diabetes patients without clinical atherosclerotic cardiovascular disease (mean age 51.1 ± 7.7 years; 63.3 women). In addition to basic laboratory tests, serum adiponectin and ultrasonographic examination of CIMT, ankle brachial index (ABI) and carotid-femoral pulse wave velocity (cfPWV) were performed.

RESULTS

Patients with subclinical atherosclerosis have higher serum FGF21 than those without (218 ± 66.8 pg/mL Vs 170 ± 43.1 pg/mL, P < 0.001). FGF21 correlated positively with CIMT and cfPWV (P < 0.001) regardless of patient gender. In logistic regression analysis, circulating FGF21 was found to be an independent predictor for subclinical atherosclerosis (P = 0.023) in addition to dyslipidemia, hypertension and adiponectin. FGF21 was also found to be an independent determinant of cfPWV in stepwise multiple regression analysis. ROC curve analysis was done and cutoff high risk FGF21 level of 184 pg/mL for the prediction of subclinical atherosclerosis with a sensitivity and specificity of 66.7%.

CONCLUSIONS

Serum FGF21 levels correlated with carotid intima media thickness and predict subclinical atherosclerosis. Serum FGF21 is also correlated positively with cfPWV and arterial stiffness in type 2 diabetes patients.

FGF Family: From Drug Development to Clinical Application

Fibroblast growth factor (FGF) belongs to a large family of growth factors. FGFs use paracrine or endocrine signaling to mediate a myriad of biological and pathophysiological process, including angiogenesis, wound healing, embryonic development, and metabolism regulation. FGF drugs for the treatment of burn and ulcer wounds are now available. The recent discovery of the crucial roles of the endocrine-acting FGF19 subfamily in maintaining homeostasis of bile acid, glucose, and phosphate further extended the activity profile of this family. Here, the applications of recombinant FGFs for the treatment of wounds, diabetes, hypophosphatemia, the development of FGF receptor inhibitors as anti-neoplastic drugs, and the achievements of basic research and applications of FGFs in China are reviewed.

Fibroblast growth factor 21 in cardio-metabolic disorders: a systematic review and meta-analysis

BACKGROUND

Fibroblast growth factor 21 is a signalling protein involved in cell differentiation, morphogenesis, proliferation and metabolism. Recent studies have associated increased levels of FGF21 in the development of cardiovascular diseases, whereas others have reported no significant associations. Therefore, this systematic review and meta-analysis evaluated the value in predicting the risk of cardio-metabolic disorders and mortality.

METHODS

PubMed and EMBASE were searched until 5th September 2017 for studies that evaluated the roles of FGF21 levels in cardio-metabolic disorders.

RESULTS

A total of 183 and 301 entries were retrieved; 24 studies met the inclusion criteria. Four studies were identified by an additional search. Therefore, 28 studies were included in the final meta-analysis. High FGF21 levels significantly predicted the incidence of coronary artery disease (hazard ratio [HR]: 1.29; 95% confidence interval [CI]: 1.06-1.55; P < 0. 01; I² = 48%) and the risk of metabolic syndrome (HR: 1.70, 95% CI: 1.35-2.15; P < 0.0001 I² = 24%). In diabetes mellitus, FGF21 predicted disease incidence or progression (HR: 1.35, 95% CI: 1.06-1.72, P < 0.05, I² = 69%) and worsening renal failure (HR: 1.06, 95% CI: 1.03-1.09, P < 0.0001, I² = 47%). FGF21 also predicted all-cause mortality (HR: 3.00, 95% CI: 1.23-7.33; P < 0.05; I² = 51%), and cardiovascular mortality (HR: 2.33, 95% CI: 1.08-4.99, P < 0.05, I² = 75%).

CONCLUSION

FGF21 significantly predicts the incidence of coronary artery disease, the risks of metabolic syndrome, diabetes mellitus and renal progression in diabetes. It also predicted all-cause and cardiovascular mortality.

Baseline Circulating FGF21 Concentrations and Increase after Fenofibrate Treatment Predict More Rapid Glycemic Progression in Type 2 Diabetes: Results from the FIELD Study

BACKGROUND

It is not known whether circulating fibroblast growth factor 21 (FGF21) concentrations are associated with glycemic progression in patients with established type 2 diabetes. This study reports this relationship in type 2 diabetes patients participating in the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial.

METHODS

Plasma FGF21 was quantified in 9697 study participants. Among patients with lifestyle-only glucose control measures at baseline, glycemic progression was defined as the initiation of oral hypoglycemic agents or insulin therapy. We assessed the relationship of FGF21 concentrations with glycohemoglobin (Hb A1c), the homeostasis model assessment of β-cell function (HOMA-B) and insulin resistance (HOMA-IR), and glycemic progression.

RESULTS

Among 2584 patients with lifestyle-only glycemic therapy at baseline, plasma FGF21 concentrations were positively associated with HOMA-IR (5.1% increase per 100% increase in FGF21 concentrations). Patients with higher baseline plasma FGF21 concentrations had higher risk of glycemic progression over a 5-year period (P = 0.02), but the association was not significant after further adjusting for alanine aminotransferase (ALT) enzyme activity. During the fenofibrate active run-in phase, higher tertiles of fenofibrate-induced increase in FGF21 concentrations were associated with higher risk of glycemic progression (adjusted hazards ratio = 1.09 and 1.18 for tertiles 2 and 3, respectively, P for trend = 0.01), even after adjusting for ALT enzyme activity. This association was statistically significant in the fenofibrate group only (P = 0.01).

CONCLUSIONS

Higher baseline and fenofibrate-induced increase in FGF21 concentrations predict more rapid glycemic progression in type 2 diabetes patients. This association may be partly explained by hepatic function.

The U-shaped relationship between fibroblast growth factor 21 and microvascular complication in type 2 diabetes mellitus

AIMS

The aim of this study was to investigate the relationship between serum FGF21 level and all microvascular complication including cardiac autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total 227 T2DM patients were enrolled and serum FGF21 levels were assessed. Diabetic retinopathy, nephropathy, peripheral neuropathy (DPN), and CAN were evaluated.

RESULTS

The prevalence of retinopathy and nephropathy among the FGF21 tertiles was significantly different (p=0.001, p=0.006, respectively), whereas no difference was found in the prevalence of DPN and CAN. In multivariate analysis, the odds ratio (OR) for the presence of retinopathy was 0.08 for the FGF21 second tertile when compared with the first tertile (p=0.029). OR of retinopathy in third tertile group was lower than first tertile and higher than second tertile, but statistically insignificant. Crude OR for nephropathy was 0.34 for the second FGF21 tertile, when compared with the first tertile (p=0.015). However, FGF21 level was not significantly associated with nephropathy after multivariable adjustment.

CONCLUSIONS

In the present study, there was no association between diabetic nephropathy, DPN, and CAN and serum FGF21 levels. However, we found a U-shaped relationship between both lower and higher serum FGF21 levels and diabetic retinopathy. This result suggests that the very low serum FGF21 level itself may associate with diabetic retinopathy and also relatively elevated serum FGF21 level may be a compensatory increase to protect against microvascular injury.

Fibroblast growth factor 21 - a key player in cardiovascular disorders?

Fibroblast growth factor 21 (FGF21) is a newly discovered adipokine, synthesized by several organs, mostly by the liver, which was introduced as a potent metabolic regulator and insulin-sensitizing factor. Numerous animal studies have demonstrated that FGF21 improves glucose and lipids metabolism and exerts anti-inflammatory effects. However, data obtained from human studies have shown contradictory results, in which circulating FGF21 levels were often elevated in obesity, dyslipidemia, type 2 diabetes (DM2) and other conditions connected with insulin resistance. This increase in basal FGF21 concentrations observed in patients with obesity and other conditions related to insulin resistance was being explained as a compensatory response to the underlying metabolic disturbances or tissue resistance to FGF21 action. Furthermore, the results of clinical trials have shown that increased FGF21 concentrations were associated with increased cardiovascular (CV) risk and had a prognostic value in CV outcomes. In recent years, it has been reported that FGF21 may exert cardioprotective effects. This mini-review aims to summarize the current state of knowledge about the role of FGF21 in CV disorders, and discuss the molecular mechanism underlying the anti-atherogenic properties of this compound.

Serum fibroblast growth factor 21 concentrations in type 2 diabetic retinopathy patients

AIMS/PURPOSE

Fibroblast growth factor 21 (FGF21) is a major metabolic regulator in the body that has been shown to be elevated in a number of metabolic disturbances including type 2 diabetes mellitus (T2DM) and the metabolic syndrome. However, little is known regarding the circulating levels of FGF21 in type 2 diabetic retinopathy (T2DR) and its association with the severity of the condition.

METHODS

In a cross-sectional setting, 142 individuals, consisting of (1) T2DM patients without T2DR, (2) T2DM patients with T2DR, and (3) healthy control subjects were recruited for this study. Various clinical and biochemical parameters were assessed and entered for analysis.

RESULTS

Serum FGF21 levels were significantly elevated in T2DM subjects without retinopathy (103.50 [75.75] pg/mL) compared with healthy controls (99.00 [126.75] pg/mL). Circulating FGF21 levels were comparable across different stages of T2DR (233.00 [109.00] for nonproliferative type 2 diabetic retinopathy [NPT2DR] vs. 215.00 [122.00] for proliferative type 2 diabetic retinopathy [PT2DR] groups, P=361). FGF21, triglycerides, and duration of diabetes mellitus were significantly associated with T2DM in baseline models. However, after adjustment for potential confounders, in the final multivariate model, FGF21 emerged as the only significant factor associated with T2DM (OR=13.772, 95% CI=3.062-61.948, P=001).

CONCLUSIONS

Serum FGF21 concentrations are markedly elevated in patients with T2RN. The association between FGF21 and T2DR appears to be independent of the effects of potential confounding variables. These findings may suggest FGF21 as a novel surrogate diagnostic biomarker in initial stages of T2DR (particularly with FGF21 values above 135.5pg/mL).

Biomarkers in Diabetic Retinopathy

There is a global diabetes epidemic correlating with an increase in obesity. This coincidence may lead to a rise in the prevalence of type 2 diabetes. There is also an as yet unexplained increase in the incidence of type 1 diabetes, which is not related to adiposity. Whilst improved diabetes care has substantially improved diabetes outcomes, the disease remains a common cause of working age adult-onset blindness. Diabetic retinopathy is the most frequently occurring complication of diabetes; it is greatly feared by many diabetes patients. There are multiple risk factors and markers for the onset and progression of diabetic retinopathy, yet residual risk remains. Screening for diabetic retinopathy is recommended to facilitate early detection and treatment. Common biomarkers of diabetic retinopathy and its risk in clinical practice today relate to the visualization of the retinal vasculature and measures of glycemia, lipids, blood pressure, body weight, smoking, and pregnancy status. Greater knowledge of novel biomarkers and mediators of diabetic retinopathy, such as those related to inflammation and angiogenesis, has contributed to the development of additional therapeutics, in particular for late-stage retinopathy, including intra-ocular corticosteroids and intravitreal vascular endothelial growth factor inhibitors ('anti-VEGFs') agents. Unfortunately, in spite of a range of treatments (including laser photocoagulation, intraocular steroids, and anti-VEGF agents, and more recently oral fenofibrate, a PPAR-alpha agonist lipid-lowering drug), many patients with diabetic retinopathy do not respond well to current therapeutics. Therefore, more effective treatments for diabetic retinopathy are necessary. New analytical techniques, in particular those related to molecular markers, are accelerating progress in diabetic retinopathy research. Given the increasing incidence and prevalence of diabetes, and the limited capacity of healthcare systems to screen and treat diabetic retinopathy, there is need to reliably identify and triage people with diabetes. Biomarkers may facilitate a better understanding of diabetic retinopathy, and contribute to the development of novel treatments and new clinical strategies to prevent vision loss in people with diabetes. This article reviews key aspects related to biomarker research, and focuses on some specific biomarkers relevant to diabetic retinopathy.