Physiological and Pharmacological Roles of FGF21 in Cardiovascular Diseases

Correlation of circulating fibroblast growth factor 21 levels with inflammatory factors and the degree of coronary artery stenosis in patients with acute myocardial infarction

BACKGROUND

Fibroblast growth factor 21 (FGF21) is a secreted protein that plays an important role in atherosclerosis and pathological cardiac remodeling. However, the correlation between FGF21 and the degree of coronary artery stenosis and its potential role in acute myocardial infarction (AMI) remain unclear. We examined whether changes in FGF21 levels in AMI correlate with the degree of coronary artery stenosis and the levels of inflammatory factors, and preliminarily investigated the effects of FGF21 on inflammatory factor levels and myocardial injury in rats with AMI.

METHODS

Serum levels of FGF21 and inflammatory factors in the AMI group and control group were measured, and the correlation between FGF21 and clinical indicators and inflammatory factors was analyzed. The effects of FGF21 on cardiac function and inflammatory response were evaluated through echocardiography and measurement of inflammatory factors.

RESULTS

Multivariate logistic regression analysis showed that neutrophil percentage (NEUT%, odds ratio [OR]: 1.232; 95 % confidence interval [CI]: 1.028-1.477; p = 0.024) and FGF21 levels (OR: 2.063; 95 % CI: 1.187-3.586; p = 0.01) had independent effects on AMI. Spearman's rank correlation test showed that FGF21 levels were positively correlated with leukocyte count, NEUT%, neutrophil count, neutrophil to lymphocyte ratio, C-reactive protein, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), monocyte chemotactic protein-1 (MCP-1) and Gensini scores (p < 0.01), but negatively correlated with lymphocyte count (p < 0.01). FGF21 levels in myocardial tissues and serum levels of FGF21, IL-6, TNF-a, and MCP-1 were significantly higher in AMI rats than in the sham-operated group (p < 0.01). After overexpression of FGF21, serum levels of IL-6, TNF-a, and MCP-1 in rats were significantly decreased (p < 0.01), and cardiac function improved significantly.

CONCLUSIONS

FGF21 levels were independently associated with AMI and may be related to the severity of coronary artery stenosis. Overexpression of FGF21 reduced serum inflammatory factor levels and improved cardiac function in AMI rats.

Reversal of nonalcoholic fatty liver disease reduces the risk of cardiovascular disease among Korean

Nonalcoholic fatty liver disease (NAFLD) is considered an independent risk factor for the development of cardiovascular disease. However, the association between changes in NAFLD status and the risk of cardiovascular disease (CVD) remains uncertain. Starting January 1, 2013, participants were followed until the occurrence of CVD event, death, or December 31, 2020. This was a population-based cohort study that included data from adults aged ≥ 20, who underwent 2 consecutive health screenings from 2009 to 2012. NAFLD was defined as a Fatty Liver Index ≥ 60 at each screening. The primary endpoint was a CVD event, which encompassed ischemic heart disease and cerebrovascular disease. The association between changes in NAFLD status and the risk of CVD was determined using multivariable Cox proportional hazards regression. This cohort comprised 4656,305 adults with a median age of 53 years. During 36,396,968 person-years of follow-up, 238,933 (5.1%) CVD events were observed. Compared to patients with no NAFLD at both screenings, patients who developed NAFLD at the second screening exhibited an increased risk of CVD (adjusted hazard ratio, 1.15; 95% confidence interval, 1.13-1.17). In contrast, individuals who recovered from NAFLD at the second screening demonstrated a reduced CVD risk compared to those with persistent NAFLD (adjusted hazard ratio, 0.91; 95% confidence interval, 0.90-0.92). The reversal of NAFLD is associated with a reduced risk of CVD. Therefore, focusing on NAFLD treatment could serve as a clinical target for lowering CVD risk.

FGF21 protects against doxorubicin-induced cardiotoxicity by inhibiting connexin 43 ubiquitination

BACKGROUND

Fibroblast growth factor 21 (FGF21) regulates glycolipid metabolism and insulin homeostasis and acts as a cardioprotective factor by protecting against myocardial ischemia/reperfusion injury, hypertension, and vascular dysfunction. FGF21 has been reported to prevent Doxorubicin (Dox)-induced cardiotoxicity, and the related signaling pathway is worthy of further study. Connexin43 (Cx43) protein was reduced by Dox treatment, especially low phosphorylated form of Cx43. Thus the aim of study is to explore the protection effect of FGF21 on Dox induced cardiotoxicity by improving the expression of Cx43 and the involved signaling pathway.

METHODS AND RESULTS

FGF21 inhibited apoptosis in Dox-treated mice and cardiomyocytes. FGF21 increased the levels of connexin43 phosphorylated at serine (S) 282 (p-Cx43 S282) and total Cx43 to inhibit Dox-induced apoptosis. By RNA sequencing, we found that deubiquitinase monocyte chemoattractant protein-induced protein 1 (MCPIP1) expression was increased by FGF21. We further found that FGF21 induced the phosphorylation of fibroblast growth factor receptor 1 (FGFR1), extracellular signal-regulated kinase 1 and 2 (Erk1/2), and Elk. Phosphorylated Elk translocated to the nucleus and increased the expression of MCPIP1. Then, MCPIP1 bound neural precursor cell expressed developmentally downregulated protein 4 (Nedd4), an E3 ubiquitination ligase, as shown by co-immunoprecipitation (Co-IP), and suppressed Cx43 ubiquitination and degradation, competitively inhibiting the binding of Cx43 with Nedd4. Thus Nedd4 could not bind and ubiquitinate Cx43, leading to the up-regulation of Cx43 and phosphorylation of Cx43 at S282.

CONCLUSIONS

FGF21 inhibited the effects of Dox on cardiomyocytes by elevating the phosphorylation of Cx43 at S282 and total Cx43 expression. This study suggests a previously unknown mechanism for the FGF21-mediated enhancement of cardiomyocyte survival and provides an effective approach to protect against the adverse cardiac effects of Dox.

Fibroblast growth factor 21 attenuates ventilator-induced lung injury by inhibiting the NLRP3/caspase-1/GSDMD pyroptotic pathway

BACKGROUND

Ventilator-induced lung injury (VILI) is caused by overdistension of the alveoli by the repetitive recruitment and derecruitment of alveolar units. This study aims to investigate the potential role and mechanism of fibroblast growth factor 21 (FGF21), a metabolic regulator secreted by the liver, in VILI development.

METHODS

Serum FGF21 concentrations were determined in patients undergoing mechanical ventilation during general anesthesia and in a mouse VILI model. Lung injury was compared between FGF21-knockout (KO) mice and wild-type (WT) mice. Recombinant FGF21 was administrated in vivo and in vitro to determine its therapeutic effect.

RESULTS

Serum FGF21 levels in patients and mice with VILI were significantly higher than in those without VILI. Additionally, the increment of serum FGF21 in anesthesia patients was positively correlated with the duration of ventilation. VILI was aggravated in FGF21-KO mice compared with WT mice. Conversely, the administration of FGF21 alleviated VILI in both mouse and cell models. FGF21 reduced Caspase-1 activity, suppressed the mRNA levels of Nlrp3, Asc, Il-1β, Il-18, Hmgb1 and Nf-κb, and decreased the protein levels of NLRP3, ASC, IL-1β, IL-18, HMGB1 and the cleaved form of GSDMD.

CONCLUSIONS

Our findings reveal that endogenous FGF21 signaling is triggered in response to VILI, which protects against VILI by inhibiting the NLRP3/Caspase-1/GSDMD pyroptosis pathway. These results suggest that boosting endogenous FGF21 or the administration of recombinant FGF21 could be promising therapeutic strategies for the treatment of VILI during anesthesia or critical care.

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

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

Brown adipose tissue as an endocrine organ: updates on the emerging role of batokines

Brown adipose tissue (BAT) remains active in adults, oxidizing fatty acids or glucose and releasing energy in the form of heat. Brown adipocytes and enhanced thermogenesis are targets for treating obesity and its comorbidities. BAT shows high synthesis activity and secretes several signaling molecules. The brown adipokines, or batokines, take action in an autocrine, paracrine, and endocrine manner. Batokines have a role in the homeostasis of the cardiovascular system, central nervous system, white adipose tissue, liver, and skeletal muscle and exert beneficial effects on BAT. The systemic function of batokines gives BAT an endocrine organ profile. Besides, the batokines Fibroblast Growth Factor-21, Vascular Endothelial Growth Factor A, Bone Morphogenetic Protein 8, Neuregulin 4, Myostatin, and Interleukin-6 emerge as targets to treat obesity and its comorbidities, deserving attention. This review outlines the role of six emerging batokines on BAT and their cross-talk with other organs, focusing on their physiological significance and diet-induced changes.

Fibroblast growth factor 21 is associated with widening QRS complex and prolonged corrected QT interval in patients with stable angina

BACKGROUND

Fibroblast growth factor 21 (FGF21) is produced by cardiac cells, may acts in an autocrine manner, and was suggested to has a cardioprotective role in atherosclerosis. Wide QRS complex and heart rate-corrected QT interval (QTc interval) prolongation are associated to dangerous ventricular arrhythmias and cardiovascular disease mortality. Yet, the role of FGF21 in cardiac arrhythmia has never been studied. The aim of the study was to investigate the relationship between plasma FGF21 and the QRS duration and QTc interval in patients with stable angina.

METHODS

Three hundred twenty-one consecutive stable angina patients were investigated. Plasma FGF21 was measured through ELISA, and each subject underwent 12-lead electrocardiography.

RESULTS

FGF21 plasma levels were positively associated with the QRS duration (β = 0.190, P = 0.001) and QTc interval (β = 0.277, P < 0.0001). With increasing FGF21 tertiles, the patients had higher frequencies of wide QRS complex and prolonged QTc interval. After adjusting for patients' anthropometric parameters, the corresponding odd ratios (ORs) for wide QRS complex of the medium and high of FGF21 versus the low of FGF21 were 1.39 (95% CI 0.51-3.90) and 4.41 (95% CI 1.84-11.59), respectively, and p for trend was 0.001. Furthermore, multiple logistic regression analysis also showed the corresponding odd ratios (ORs) for prolonged QTc interval of the medium and high of FGF21 versus the low of FGF21 were 1.02 (95% CI 0.53-1.78) and 1.93 (95% CI 1.04-3.60) respectively with the p for trend of 0.037. In addition, age- and sex-adjusted FGF21 levels were positively associated with fasting glucose, HbA1c, creatinine, and adiponectin, but negatively associated with albumin, and the estimated glomerular filtration rate.

CONCLUSIONS

This study indicates that plasma FGF21 is associated with wide QRS complex and prolonged corrected QT interval in stable angina patients, further study is required to investigate the role of plasma FGF21 for the underlying pathogenesis.

Towards harnessing the value of organokine crosstalk to predict the risk for cardiovascular disease in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Importantly, NAFLD increases the risk for cardiovascular disease (CVD). A causal relationship has been substantiated. Given the pandemic proportions of NAFLD, a reliable scoring system for predicting the risk of NAFLD-associated CVD is an urgent medical need. We here review cumulative evidence suggesting that systemically released organokines - especially certain adipokines, hepatokines, and cardiokines - may serve this purpose. The underlying rationale is that these signalers directly communicate between white adipose tissue, liver, and heart as key players in the pathogenesis of NAFLD and resultant CVD events. Moreover, evidence suggests that these organ-specific cytokines are secreted in a biologically predetermined, cascade-like pattern. Consequently, upon pinpointing organokines of relevance, we sketch requirements to establish an algorithm predictive of the CVD risk in patients with NAFLD. Such an algorithm, as to be consolidated in the form of an applicable equation, may be improved continuously by machine learning. To the best of our knowledge, such an option has not yet been considered. Establishing and implementing a reliable algorithm for determining the NAFLD-associated CVD risk has the potential to save many NAFLD patients from life-threatening CVD events.

Fibroblast growth factor 21 reverses high‐fat diet‐induced impairment of vascular function via the anti‐oxidative pathway in ApoE knockout mice

Circulating endothelial progenitor cells (EPCs), which function in vascular repair, are the markers of endothelial dysfunction and vascular health. Fibroblast growth factor 21 (FGF21), a liver‐secreted protein, plays a crucial role in glucose homeostasis and lipid metabolism. FGF21 has been reported to attenuate the progression of atherosclerosis, but its impact on EPCs under high oxidative stress conditions remains unclear. In vitro studies showed that the β‐klotho protein was expressed in cultured EPCs and that its expression was upregulated by FGF21 treatment. Hydrogen peroxide (H₂O₂)‐induced oxidative stress impaired EPC function, including cell viability, migration and tube formation. Pretreatment with FGF21 restored the functions of EPCs after the exposure to H₂O₂. Administration of N(ω)‐nitro‐L‐arginine methyl ester (L‐NAME), an inhibitor of nitric oxide synthase, inhibited the effects of FGF21 in alleviating oxidative injury by suppressing endothelial nitric oxide synthase (eNOS). In an in vivo study, the administration of FGF21 significantly reduced total cholesterol (TC) and blood glucose levels in apolipoprotein E (ApoE)‐deficient mice that were fed a high‐fat diet (HFD). Endothelial function, as reflected by acetylcholine‐stimulated aortic relaxation, was improved after FGF21 treatment in ApoE‐deficient mice. Analysis of mRNA levels in the aorta indicated that FGF21 increased the mRNA expression of eNOS and upregulated the expression of the antioxidant genes superoxide dismutase (SOD)1 and SOD2 in ApoE‐deficient mice. These data suggest that FGF21 improves EPC functions via the Akt/eNOS/nitric oxide (NO) pathway and reverses endothelial dysfunction under oxidative stress. Therefore, administration of FGF21 may ameliorate a HFD‐induced vascular injury in ApoE‐deficient mice.

Genes and Longevity of Lifespan

Aging is a complex process indicated by low energy levels, declined physiological activity, stress induced loss of homeostasis leading to the risk of diseases and mortality. Recent developments in medical sciences and an increased availability of nutritional requirements has significantly increased the average human lifespan worldwide. Several environmental and physiological factors contribute to the aging process. However, about 40% human life expectancy is inherited among generations, many lifespan associated genes, genetic mechanisms and pathways have been demonstrated during last decades. In the present review, we have evaluated many human genes and their non-human orthologs established for their role in the regulation of lifespan. The study has included more than fifty genes reported in the literature for their contributions to the longevity of life. Intact genomic DNA is essential for the life activities at the level of cell, tissue, and organ. Nucleic acids are vulnerable to oxidative stress, chemotherapies, and exposure to radiations. Efficient DNA repair mechanisms are essential for the maintenance of genomic integrity, damaged DNA is not replicated and transferred to next generations rather the presence of deleterious DNA initiates signaling cascades leading to the cell cycle arrest or apoptosis. DNA modifications, DNA methylation, histone methylation, histone acetylation and DNA damage can eventually lead towards apoptosis. The importance of calorie restriction therapy in the extension of lifespan has also been discussed. The role of pathways involved in the regulation of lifespan such as DAF-16/FOXO (forkhead box protein O1), TOR and JNK pathways has also been particularized. The study provides an updated account of genetic factors associated with the extended lifespan and their interactive contributory role with cellular pathways.

Elevated Serum Fibroblast Growth Factor 21 Is Relevant to Heart Failure Patients with Reduced Ejection Fraction

Objective

The aim of this study was to evaluate the roles of fibroblast growth factor 21 (FGF21) in heart failure patients with reduced ejection fraction and its association with Heart Failure with reduced Ejection Fraction (HFrEF).

Methods

The level of FGF21 was measured by enzyme-linked immunosorbent assay (ELISA) in 199 subjects enrolled in this study, including 128 subjects with HFrEF and 71 control subjects. The mean follow-up time was 13.36 months. The left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) percentage were evaluated by the 2D echocardiography. Serum brain natriuretic peptide (BNP) was measured in the routine clinical laboratory.

Results

The serum FGF21 level was evidently higher in patients with HFrEF than in the control group (228.72 ± 24.04 vs. 171.60 ± 12.98, p < 0.001). After 1 year of follow-up, 61 patients (47.66%) with heart failure were readmitted to the hospital, including 8 deaths (13.11%). The AUC of the receiver operating characteristic (ROC) curve for the predictive value of FGF21 for prognosis was 0.964. Kaplan-Meier analysis results showed that there were significant differences in the 1-year mortality and heart failure readmission events between the grouped subjects. A poor prognosis was correlated with the serum level of FGF21, BNP, LVEDD, and LVEF, which was confirmed by the univariate Cox analysis.

Conclusion

FGF21 was independently associated with an increased risk of mortality and readmission HFrEF patients. Therefore, FGF21 has the potential to be a biomarker for the progression of HFrEF in patients.

Fibroblast growth factor-21 as a novel metabolic factor for regulating thrombotic homeostasis

Fibroblast growth factor-21 (FGF-21) performs a wide range of biological functions in organisms. Here, we report for the first time that FGF-21 suppresses thrombus formation with no notable risk of bleeding. Prophylactic and therapeutic administration of FGF-21 significantly improved the degree of vascular stenosis and reduced the thrombus area, volume and burden. We determined the antithrombotic mechanism of FGF-21, demonstrating that FGF-21 exhibits an anticoagulant effect by inhibiting the expression and activity of factor VII (FVII). FGF-21 exerts an antiplatelet effect by inhibiting platelet activation. FGF-21 enhances fibrinolysis by promoting tissue plasminogen activator (tPA) expression and activation, while inhibiting plasminogen activator inhibitor 1 (PAI-1) expression and activation. We further found that FGF-21 mediated the expression and activation of tPA and PAI-1 by regulating the ERK1/2 and TGF-β/Smad2 pathways, respectively. In addition, we found that FGF-21 inhibits the expression of inflammatory factors in thrombosis by regulating the NF-κB pathway.

FGF21 outperforms GDF15 as a diagnostic biomarker of mitochondrial disease in children

Several studies have shown serum fibroblast growth factor 21 (FGF21) and growth differentiation factor 15 (GDF15) levels are elevated in patients with mitochondrial disease (MD) where myopathy is a feature. In this study we investigated the utility of FGF21 and GDF15 as biomarkers for MD in a phenotypically and genotypically diverse pediatric cohort with suspected MD against a panel of healthy controls and non-mitochondrial disease controls with some overlapping clinical features. Serum was collected from 56 children with MD, 104 children with non-mitochondrial disease (27 neuromuscular, 26 cardiac, 21 hepatic, 30 renal) and 30 pediatric controls. Serum FGF21 and GDF15 concentrations were measured using ELISA, and their ability to detect MD was determined. Median FGF21 and GDF15 serum concentrations were elevated 17-fold and 3-fold respectively in pediatric MD patients compared to the healthy control group. Non-mitochondrial disease controls had elevated serum GDF15 concentrations while FGF21 concentrations were in the normal range. Elevation of GDF15 in a range of non-mitochondrial pediatric disorders limits its use as a MD biomarker. FGF21 was elevated in MD patients with a spectrum of clinical phenotypes, including those without myopathy. Serum FGF21 had an area under the receiver operating characteristic curve of 0.87, indicating good ability to discriminate between pediatric MD and healthy and non-mitochondrial disease controls. Triaging of pediatric MD patients by clinical phenotyping and serum FGF21 testing, followed by massively parallel sequencing, may enable more rapid diagnosis of pediatric MD.

The Roles of FGF21 and ALCAT1 in Aerobic Exercise-Induced Cardioprotection of Postmyocardial Infarction Mice

Aerobic exercise mitigates oxidative stress and apoptosis caused by myocardial infarction (MI) even though the precise mechanisms remain completely elusive. In this study, we investigated the potential mechanisms of aerobic exercise in ameliorating the cardiac function of mice with MI. In vivo, MI was induced by left anterior descending (LAD) coronary artery ligation in wild-type mice, alcat1 knockout, and fgf21 knockout mice. The mice were exercised under a moderate-intensity protocol for 6 weeks at one week later post-MI. In vitro, H9C2 cells were treated with lentiviral vector carrying alcat1 gene, recombinant human FGF21 (rhFGF21), PI3K inhibitor, and H₂O₂ to explore the potential mechanisms. Our results showed that aerobic exercise significantly increased the FGF21 expression and decreased the ALCAT1 expression in the hearts of mice with MI. fgf21 knockout weakened the inhibitory effects of aerobic exercise on oxidative stress, endoplasmic reticulum (ER) stress, and apoptosis in mice with MI. Both/either alcat1 knockout and/or aerobic exercise improved cardiac function by inhibiting oxidative stress and apoptosis in the MI heart. rhFGF21 inhibited both H₂O₂ and overexpression of ALCAT1-induced oxidative stress and apoptosis by activating the PI3K/AKT pathway in H9C2 cells. In conclusion, our results showed that aerobic exercise alleviated oxidative stress and apoptosis by activating the FGF21/FGFR1/PI3K/AKT pathway or inhibiting the hyperexpression of ALCAT1, which ultimately improved the cardiac function in MI mice.

Fibroblast Growth Factor 21 Ameliorates NaV1.5 and Kir2.1 Channel Dysregulation in Human AC16 Cardiomyocytes

Infarcted myocardium is predisposed to cause lethal ventricular arrhythmias that remain the main cause of death in patients suffering myocardial ischemia. Liver-derived fibroblast growth factor 21 (FGF21) is an endocrine regulator, which exerts metabolic actions by favoring glucose and lipids metabolism. Emerging evidence has shown a beneficial effect of FGF21 on cardiovascular diseases, but the role of FGF21 on ventricular arrhythmias following myocardial infarction (MI) in humans has never been addressed. This study was conducted to investigate the pharmacological effects of FGF21 on cardiomyocytes after MI in humans. Patients with arrhythmia in acute MI and healthy volunteers were enrolled in this study. Serum samples were collected from these subjects on day 1 and days 7–10 after the onset of MI for measuring FGF21 levels using ELISA. Here, we found that the serum level of FGF21 was significantly increased on day 1 after the onset of MI and it returned to normal on days 7–10, relative to the Control samples. In order to clarify the regulation of FGF21 on arrhythmia, two kinds of arrhythmia animal models were established in this study, including ischemic arrhythmia model (MI rat model) and nonischemic arrhythmia model (ouabain-induced guinea pig arrhythmia model). The results showed that the incidence and duration time of ischemic arrhythmias in rhbFGF21-treated MI rats were significantly reduced at different time point after MI compared with normal saline-treated MI rats. Moreover, the onset of the first ventricular arrhythmias was delayed and the numbers of VF and maintenance were attenuated by FGF21 compared to the rhbFGF21-untreated group in the ouabain model. Consistently, in vitro study also demonstrated that FGF21 administration was able to shorten action potential duration (APD) in hydrogen peroxide-treated AC16 cells. Mechanically, FGF21 can ameliorate the electrophysiological function of AC16 cells, which is characterized by rescuing the expression and dysfunction of cardiac sodium current (I_Na) and inward rectifier potassium (I_k1) in AC16 cells induced by hydrogen peroxide. Moreover, the restorative effect of FGF21 on Na_V1.5 and Kir2.1 was eliminated when FGF receptors were inhibited. Collectively, FGF21 has the potential role of ameliorating transmembrane ion channels remodeling through the Na_V1.5/Kir2.1 pathway by FGF receptors and thus reducing life-threatening postinfarcted arrhythmias, which provides new strategies for antiarrhythmic therapy in clinics.

High-Level Serum Fibroblast Growth Factor 21 Concentration Is Closely Associated With an Increased Risk of Cardiovascular Diseases: A Systematic Review and Meta-Analysis

Background: The association between fibroblast growth factor 21 (FGF21) and cardiovascular disease (CVD) risk remains unclear. We conducted this systematic review and meta-analysis to evaluate the association between FGF21 and CVDs, and relevant vascular parameters.

Methods: PubMed and Web of Science databases were systematically searched to identify relevant studies published before March 2021. The FGF21 concentration was compared between individuals with and without CVDs. The effect of FGF21 on CVD risk was assessed by using hazard ratio (HR) and odds ratio (OR). The association between FGF21 and vascular parameters was assessed by Pearson's r. Study quality was assessed using Newcastle–Ottawa Scale and Joanna Briggs Institution Checklist.

Results: A total of 29,156 individuals from 30 studies were included. Overall, the serum FGF21 concentration was significantly higher in CVD patients (p < 0.001), especially for coronary artery disease (CAD) (p < 0.001) and hypertension (p < 0.001). The pooled OR (p = 0.009) and HR (p < 0.001) showed that the risk of CVDs increased with FGF21. The linear association between FGF21 and vascular parameters, including pulse wave velocity (r = 0.32), carotid intima-media thickness (r = 0.21), ankle-brachial index (r = 0.33), systolic blood pressure (r = 0.13), and diastolic blood pressure (r = 0.05), was insignificant. The incidence of overall CVDs (p = 0.03) was significantly higher in individuals with higher FGF21 levels.

Conclusion: High-level serum FGF21 concentration is closely associated with an increased risk of CVDs, which may be independent of vascular parameters. A standard FGF21 classification threshold needs to be established before clinical use for CVD risk assessment.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=241968, identifier: CRD42021241968.

FGF21 serum levels are related to insulin resistance, metabolic changes and obesity in Mexican people living with HIV (PLWH)

Background

Antiretroviral therapy has significantly improved prognosis in treatment against HIV infection, however, prolonged exposure is associated to cardiovascular diseases, lipodystrophy, type 2 diabetes, insulin resistance, metabolic alteration, as obesity which includes the accumulation of oxidative stress in adipose tissue. FGF21 is a peptide hormone that is known to regulate glucose and lipid metabolism. FGF21 is expressed and secreted primarily in the liver and adipose tissue, promoting oxidation of glucose/fatty acids and insulin sensitivity. Alterations in FGF21 may be associated with the development of insulin resistance, metabolic syndrome and cardiovascular disease. We hypothesized that FGF21 protein levels are associated with metabolic abnormalities, placing special attention to the alterations in relation to the concurrence of overweight/obesity in people living with HIV (PLWH).

Design

Serum FGF21 was analyzed in 241 subjects, 160 PLWH and 81 unrelated HIV-uninfected subjects as a control group. Clinical records were consulted to obtain CD4+ cell counting and number of viral RNA copies. Serum FGF21 levels were tested for correlation with anthropometric and metabolic parameters; glucose, cholesterol, HDL, LDL, VLDL, triglycerides, insulin and indexes of atherogenesis and insulin resistance (HOMA).

Results

The participants were classified into four groups: (i) PLWH with normal weight, (ii) PLWH with overweight/obesity, (iii) HIV-uninfected with normal weight, and (iv) HIV-uninfected with overweight/obesity.

Insulin levels were higher in normal-weight PLWH than in the HIV-uninfected group but not statistically significant, however, for the overweight/obesity PLWH group, insulin levels were significantly higher in comparison with the other three groups (p<0.0001). For FGF21, serum levels were slightly higher in the overweight/obesity groups in both patients and controls.

In HIV-infected subjects, FGF21 levels showed a strong positive correlation with triglycerides, insulin levels and insulin resistance with a p-value <0.0001. In the seronegative group, FGF21 was only correlated with weight and waist circumference, showing an important association of FGF21 levels with the degree of obesity of the individuals.

Conclusion

Insulin resistance and FGF21 elevations were observed in overweight-obese PLWH. FGF21 elevation could be viewed as a compensation mechanism as, in the control group, FGF21 correlations appeared to be confined to weight and waist circumference. This can be explained based on the action of FGF21 promoting the uptake of glucose in adipose tissue. In PLWH, FGF21 was low, possibly as a result of a change in adiposity leading to a metabolic disruption.

The Multifunctional Contribution of FGF Signaling to Cardiac Development, Homeostasis, Disease and Repair

The current focus on cardiovascular research reflects society’s concerns regarding the alarming incidence of cardiac-related diseases and mortality in the industrialized world and, notably, an urgent need to combat them by more efficient therapies. To pursue these therapeutic approaches, a comprehensive understanding of the mechanism of action for multifunctional fibroblast growth factor (FGF) signaling in the biology of the heart is a matter of high importance. The roles of FGFs in heart development range from outflow tract formation to the proliferation of cardiomyocytes and the formation of heart chambers. In the context of cardiac regeneration, FGFs 1, 2, 9, 16, 19, and 21 mediate adaptive responses including restoration of cardiac contracting rate after myocardial infarction and reduction of myocardial infarct size. However, cardiac complications in human diseases are correlated with pathogenic effects of FGF ligands and/or FGF signaling impairment. FGFs 2 and 23 are involved in maladaptive responses such as cardiac hypertrophic, fibrotic responses and heart failure. Among FGFs with known causative (FGFs 2, 21, and 23) or protective (FGFs 2, 15/19, 16, and 21) roles in cardiac diseases, FGFs 15/19, 21, and 23 display diagnostic potential. The effective role of FGFs on the induction of progenitor stem cells to cardiac cells during development has been employed to boost the limited capacity of postnatal cardiac repair. To renew or replenish damaged cardiomyocytes, FGFs 1, 2, 10, and 16 were tested in (induced-) pluripotent stem cell-based approaches and for stimulation of cell cycle re-entry in adult cardiomyocytes. This review will shed light on the wide range of beneficiary and detrimental actions mediated by FGF ligands and their receptors in the heart, which may open new therapeutic avenues for ameliorating cardiac complications.

Serum Levels of Fibroblast Growth Factor 21 Are Positively Associated with Aortic Stiffness in Patients with Type 2 Diabetes Mellitus

Aortic stiffness (AS), assessed using carotid–femoral pulse wave velocity (cfPWV), is associated with cardiovascular disease in type 2 diabetes mellitus (T2DM). The relationship between serum fibroblast growth factor 21 (FGF-21) and AS in T2DM patients was evaluated. Fasting serum FGF-21 levels of 130 T2DM patients were measured using an enzyme immunoassay kit. A validated tonometry system was used to measure cfPWV (>10 m/s indicated AS). Of these T2DM patients, 34.6% were defined as the AS group. T2DM patients with AS were older; exhibited higher systolic blood pressure, diastolic blood pressure, and body fat mass; higher triglyceride, fasting glucose, glycosylated hemoglobin, and creatinine levels; higher urine albumin-to-creatinine ratios and serum FGF-21 levels; and lower estimated glomerular filtration rates. The FGF-21 level (odds ratio = 1.005, 95% confidence interval: 1.002–1.009, p = 0.002) as well as systolic blood pressure was an independent predictor of AS and positively correlated to cfPWV values (β = 0.369, p < 0.001) in T2DM patients. For T2DM patients, serum FGF-21 level could be a predictor for AS.

Advances in Biological Functions and Clinical Studies of FGF21

Fibroblast growth factor 21 (FGF21) regulates many crucial biological processes in human and mammals, particularly metabolic modulation and protective effect after injury. Therefore, determining complex regulatory mechanisms and elucidating the signaling pathway may greatly promote the prevention, diagnosis, and treatment of related injury and metabolic diseases. This review focused on the metabolic modulation and protective effect of FGF21 and summarized the molecular mechanisms and clinical research developments.

Fibroblast Growth Factor 21 Correlates with the Prognosis of Dilated Cardiomyopathy

OBJECTIVES

The goal of this study was to evaluate whether serum fibroblast growth factor 21 (FGF21) levels can be used to predict the prognosis of dilated cardiomyopathy (DCM).

METHODS

241 patients with DCM and 80 control subjects were recruited and followed up for an average of 16.12 months. A 2-dimensional (2-D) echocardiography technique was performed to calculate the left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF) percentages. The levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and creatinine were measured in routine clinical laboratory tests. Serum FGF21 levels were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The levels of serum FGF21 were significantly higher in the DCM groups than in the control groups (225.85 ± 32.57 vs. 145.36 ± 30.57, p < 0.001). Serum FGF21 levels were positively correlated with the NYHA functional classification of heart failure (HF) (r = 0.610, p < 0.001) and NT-proBNP levels (r = 0.741, p < 0.001). Moreover, a negative correlation was observed between the serum FGF21 levels and the LVEF (r = -0.402, p < 0.001). FGF21, NT-proBNP, the LVEF and a history of atrial fibrillation (AF) correlated significantly with NYHA class IV (p < 0.05). The AUC of NT-proBNP for predicting NYHA class IV in DCM patients was greater than that of FGF21 (0.830 vs. 0.772, p < 0.001). Overall, 133 patients with DCM were recorded at the end point. Kaplan-Meier analysis results showed that the survival probability of those individuals with high levels of FGF21 and NT-proBNP was significantly lower than of those with low levels of these factors (p < 0.001). In the multivariate Cox analysis, FGF21 (HR 2.561; 95% CI 1.705-3.849) and NT-proBNP (HR 4.458; 95% CI 2.645-7.513) were independent predictors of a poor prognosis in DCM patients.

CONCLUSIONS

Serum FGF21 levels were associated with the risk factors, severity, and prognosis of DCM. Therefore, FGF21 may serve as a novel biomarker for the prognosis of DCM.

A review of fibroblast growth factor 21 in diabetic cardiomyopathy

FGF21 (fibroblast growth factor 21) is a regulator of metabolism and performs an important role in glucose and lipid metabolism and the maintenance of energy balance. FGF21 is principally expressed in the liver, but it can also be found in the pancreas, skeletal muscle, and adipose tissue. It is known that levels of serum FGF21 are significantly elevated in obese, insulin-resistant patients, and those with metabolic syndrome. Elevated levels of FGF21 in serum during the early stages of various metabolic diseases are considered a compensatory response by the organism. Therefore, FGF21 is considered a hormone in response to stress and an early diagnostic marker of disease. Diabetic cardiomyopathy is a special type of cardiac complication, characterized as a chronic myocardial disorder caused by diabetes. The pathological process includes increased oxidative stress, energy metabolism in myocardial cells, an inflammatory response, and myocardial cell apoptosis. A growing body of evidence suggests that FGF21 has the potential to be an effective drug for the treatment of diabetic cardiomyopathy. Here, we review recent progress on the characteristics of FGF21 in its protective role, especially in pathological processes such as suppressing apoptosis in the myocardium, reducing inflammation in cardiomyocytes, reducing oxidative stress, and promoting fatty acid oxidation. In addition, we explore the possibility that diabetic cardiomyopathy can be delayed through the application of FGF21, providing possible therapeutic targets of the disease.

Fibroblast growth factor 21 inhibited ischemic arrhythmias via targeting miR-143/EGR1 axis

Ventricular arrhythmia is the most common cause of sudden cardiac death in patients with myocardial infarction (MI). Fibroblast growth factor 21 (FGF21) has been shown to play an important role in cardiovascular and metabolic diseases. However, the effects of FGF21 on ventricular arrhythmias following MI have not been addressed yet. The present study was conducted to investigate the pharmacological action of FGF21 on ventricular arrhythmias after MI. Adult male mice were administrated with or without recombinant human basic FGF21 (rhbFGF21), and the susceptibility to arrhythmias was assessed by programmed electrical stimulation and optical mapping techniques. Here, we found that rhbFGF21 administration reduced the occurrence of ventricular tachycardia (VT), improved epicardial conduction velocity and shorted action potential duration at 90% (APD90) in infarcted mouse hearts. Mechanistically, FGF21 may improve cardiac electrophysiological remodeling as characterized by the decrease of INa and IK1 current density in border zone of infarcted mouse hearts. Consistently, in vitro study also demonstrated that FGF21 may rescue oxidant stress-induced dysfunction of INa and IK1 currents in cultured ventricular myocytes. We further found that oxidant stress-induced down-regulation of early growth response protein 1 (EGR1) contributed to INa and IK1 reduction in post-infarcted hearts, and FGF21 may recruit EGR1 into the SCN5A and KCNJ2 promoter regions to up-regulate NaV1.5 and Kir2.1 expression at transcriptional level. Moreover, miR-143 was identified as upstream of EGR1 and mediated FGF21-induced EGR1 up-regulation in cardiomyocytes. Collectively, rhbFGF21 administration effectively suppressed ventricular arrhythmias in post-infarcted hearts by regulating miR-143-EGR1-NaV1.5/Kir2.1 axis, which provides novel therapeutic strategies for ischemic arrhythmias in clinics.

The relationship of circulating fibroblast growth factor 21 levels with pericardial fat: The Multi-Ethnic Study of Atherosclerosis

Previous small studies have reported an association between circulating fibroblast growth factor 21 (FGF21) levels and pericardial fat volume in post-menopausal women and high cardiovascular disease (CVD) risk patients. In this study, we investigated the relationship of FGF21 levels with pericardial fat volume in participants free of clinical CVD at baseline. We analysed data from 5765 men and women from the Multi-Ethnic Study of Atherosclerosis (MESA) with both pericardial fat volume and plasma FGF21 levels measured at baseline. 4746 participants had pericardial fat volume measured in at least one follow-up exam. After adjusting for confounding factors, ln-transformed FGF21 levels were positively associated with pericardial fat volume at baseline (β = 0.055, p < 0.001). When assessing change in pericardial fat volume over a mean duration of 3.0 years using a linear mixed-effects model, higher baseline FGF21 levels were associated with higher pericardial fat volume at baseline (2.381 cm³ larger in pericardial fat volume per one SD increase in ln-transformed FGF21 levels), but less pericardial fat accumulation over time (0.191 cm³/year lower per one SD increase in ln-transformed FGF21 levels). Cross-sectionally, higher plasma FGF21 levels were significantly associated with higher pericardial fat volume, independent of traditional CVD risk factors and inflammatory markers. However, higher FGF21 levels tended to be associated with less pericardial fat accumulation over time. Nevertheless, such change in pericardial fat volume is very modest and could be due to measurement error. Further studies are needed to elucidate the longitudinal relationship of baseline FGF21 levels with pericardial fat accumulation.

Fibroblast growth factor-21 alleviates hypoxia/reoxygenation injury in H9c2 cardiomyocytes by promoting autophagic flux

Fibroblast growth factor (FGF)-21, a member of the family of FGFs, exhibits protective effects against myocardial ischemia and ischemia/reperfusion injury; it is also an enhancer of autophagy. However, the mechanisms underlying the protective role of FGF-21 against cardiomyocyte hypoxia/reoxygenation (H/R) injury remain unclear. The present study aimed to investigate the effect of FGF-21 on H9c2 cardiomyocyte injury induced by H/R and the mechanism associated with changes in autophagy. Cultured H9c2 cardiomyocytes subjected to hypoxia were treated with a vehicle or FGF-21 during reoxygenation. The viability of H9c2 rat cardiomyocytes was measured using Cell Counting Kit-8 and trypan blue exclusion assays. The contents of creatine kinase (CK) and creatine kinase isoenzymes (CK-MB), cardiac troponin I (cTnT), cardiac troponin T (cTnI) and lactate dehydrogenase (LDH) in culture medium were detected with a CK, CK-MB, cTnT, cTnI and LDH assay kits. The protein levels were examined by western blot analysis. Autophagic flux was detected by Ad-mCherry-GFP-LC3B autophagy fluorescent adenovirus reagent. The results indicated that FGF-21 alleviated H/R-induced H9c2 myocardial cell injury and enhanced autophagic flux during H/R, and that this effect was antagonized by co-treatment with 3-methyladenine, an autophagy inhibitor. Furthermore, FGF-21 increased the expression levels of Beclin-1 and Vps34 proteins, but not of mechanistic target of rapamycin. These data indicate that FGF-21 treatment limited H/R injury in H9c2 cardiomyocytes by promoting autophagic flux through upregulation of the expression levels of Beclin-1 and Vps34 proteins.

FGF21 protects human umbilical vein endothelial cells against high glucose-induced apoptosis via PI3K/Akt/Fox3a signaling pathway

AIMS

Diabetic macroangiopathy is the main cause of morbidity and mortality in patients with diabetes. Endothelial cell injury is a pathological precondition for diabetic macroangiopathy. Fibroblast growth factor 21 (FGF21) is a key metabolic regulator which has recently been suggested to protect cardiac myocytes and vascular cells against oxidative stress-induced injury in vitro and vivo. In this study, we aimed to investigate the protective capacity of FGF21 in human umbilical vein endothelial cells (HUVECs) against high glucose (HG)-induced apoptosis via phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt)/FoxO3a pathway.

METHODS

The cell viability was examined by CCK-8 assay, Intracellular ROS levels were measured by the detection of the fluorescent product formed by the oxidation of DCFH-DA, Apoptosis was analyzed using Hoechst 33258 nuclear staining and Flow Cytometry Analysis (FCA), the expression of protein were detected by Western blot.

RESULTS

Results show that pretreating HUVECs with FGF21 before exposure to HG increases cell viability, while decreasing apoptosis and the generation of reactive oxygen species. Western blot analysis shows that HG reduces the phosphorylation of Akt and FoxO3a, and induces nuclear localization of FoxO3a. The effects were significantly reversed by FGF21 pre-treatment. Furthermore, the protective effects of FGF21 were prevented by PI3K/Akt inhibitor LY294002.

CONCLUSIONS

Our data demonstrates that FGF21 protects HUVECs from HG-induced oxidative stress and apoptosis via the activation of PI3K/Akt/FoxO3a signaling pathway.

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.

Thermogenic capacity of human periaortic adipose tissue is transformed by body weight

The anatomical location of adipose tissue might have direct implications for its functionality and risk of cardiovascular disease. Adipose tissue surrounding blood vessels may be thermogenically more active in specific areas of the body, releasing substances that regulate vascular metabolism. In humans, the phenotypic characteristics of adipose tissue surrounding the aorta and the cardiovascular disease risk that it might entail remain largely unknown. Here, we compared thermogenesis-related molecular features of human periaortic adipose tissue samples with those of subcutaneous adipose tissue, obtained by sternotomy from 42 patients undergoing cardiovascular surgery. To determine the expression of genes related to energy expenditure and the levels of some adipokines, histological examinations, quantitative PCR, and protein expression measurements in adipocyte precursor cells were performed. Periaortic adipocytes were smaller than those from subcutaneous tissue. Moreover, weight gain induced periaortic adipocyte hypertrophy (r = -0.91, p<0.01). Compared to subcutaneous tissue, adiponectin, FABP4, IL-4 and IL-6 was decreased in periaortic adipocytes, whereas FGF21, UCP-1, PGC-1a, CITED1, Omentin and TFAM (Mitochondrial protein) increased. Upon analyzing patients’ clinical conditions, it emerged that the levels of PGC-1a both in male (r = -0.48 p<0.04) and female (r = -0.61, p<0.05) and TFAM in male (r = -0.72, p<0.0008) and female (r = -0.86, p<0.002) decreased significantly with progressive weight gain. However, no differences were observed in patients with diabetes mellitus 2 or Hyperlipidemia. Adipocytes surrounding the ascending aorta present markers of major thermogenic activity than those in subcutaneous tissue. Nevertheless, this characteristic might change, due to unfavorable metabolic conditions such as obesity, which is a risk factor for cardiovascular disease.

Fibroblast growth factor 21 inhibition aggravates cardiac dysfunction in diabetic cardiomyopathy by improving lipid accumulation

Diabetic cardiomyopathy (DCM) is one of the major causes of morbidity and mortality in diabetic patients. Recent studies have demonstrated an increased level of fibroblast growth factor 21 (FGF21) in the plasma of DCM patients, and FGF21 has been proven to be a cardiovascular protector of the heart. The present study aimed to further investigate the pathogenic role of FGF21 in DCM, hypothesizing that a lack of FGF21 may promote the progression of DCM by regulating the lipid metabolism, cardiac hypertrophy and cardiac fibrosis, thus deteriorating the cardiac dysfunction. A total of 44 mice were randomly assigned into the normal (n=6), DCM (n=6), normal + scrambled siRNA (n=6), DCM + scrambled siRNA (n=6), normal + FGF21 siRNA (n=10) and DCM + FGF21 siRNA (n=10) groups. Type 1 diabetes mellitus was induced to mice in the DCM groups by streptozotocin injection, while FGF21 expression was inhibited by FGF21 siRNA. Normal and DCM mice administrated with scrambled siRNA were respectively regarded as the controls for the normal + FGF21 siRNA and DCM + FGF21 siRNA groups. In the DCM group, FGF21 inhibition promoted cardiac hypertrophy and fibrosis, and the expression levels of their indicators, including atrial natriuretic factor, α-skeletal actin, collagen type I and III, and transforming growth factor-β, increased, leading to further decreased cardiac function. In addition, FGF21 inhibition in DCM mice elevated the quantity of lipid droplets and the concentration of heart triglycerides, plasma triglycerides and cholesterol levels, accompanied by downregulation of peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) and upregulation of cluster of differentiation (CD)36. Thus, the results indicated that FGF21 inhibition exacerbates the cardiac dysfunction by aggravating the lipid accumulation through regulating the expression levels of PGC-1α and CD36. In conclusion, it is suggested that FGF21 may be a potentially useful agent in the treatment of DCM.

Fibroblast growth factor 21: a regulator of metabolic disease and health span

Fibroblast growth factor 21 (FGF21) is a potent endocrine regulator with physiological effects on glucose and lipid metabolism and thus garners much attention for its translational potential for the management of obesity and related metabolic syndromes. FGF21 is mainly expressed in several metabolically active tissue organs, such as the liver, adipose tissue, skeletal muscle, and pancreas, with profound effects and therapeutic relevance. Emerging experimental and clinical data point to the demonstrated metabolic benefits of FGF21, which include, but are not limited to, weight loss, glucose and lipid metabolism, and insulin sensitivity. In addition, FGF21 also acts directly through its coreceptor β-klotho in the brain to alter light-dark cycle activity. In this review, we critically appraise current advances in understanding the physiological actions of FGF21 and its role as a biomarker of various metabolic diseases, especially type 2 diabetes mellitus. We also discuss the potentially exciting role of FGF21 in improving our health and prolonging our life span. This information will provide a fuller understanding for further research into FGF21, as well as providing a scientific basis for potentially establishing health care guidelines for this promising molecule.

Association between circulating fibroblast growth factor 21 and mortality in end-stage renal disease

Fibroblast growth factor 21 (FGF21) is an endocrine factor that regulates glucose and lipid metabolism. Circulating FGF21 predicts cardiovascular events and mortality in type 2 diabetes mellitus, including early-stage chronic kidney disease, but its impact on clinical outcomes in end-stage renal disease (ESRD) patients remains unclear. This study enrolled 90 ESRD patients receiving chronic hemodialysis who were categorized into low- and high-FGF21 groups by the median value. We investigated the association between circulating FGF21 levels and the cardiovascular event and mortality during a median follow-up period of 64 months. A Kaplan-Meier analysis showed that the mortality rate was significantly higher in the high-FGF21 group than in the low-FGF21 group (28.3% vs. 9.1%, log-rank, P = 0.034), while the rate of cardiovascular events did not significantly differ between the two groups (30.4% vs. 22.7%, log-rank, P = 0.312). In multivariable Cox models adjusted a high FGF21 level was an independent predictor of all-cause mortality (hazard ratio: 3.98; 95% confidence interval: 1.39–14.27, P = 0.009). Higher circulating FGF21 levels were associated with a high mortality rate, but not cardiovascular events in patient with ESRD, suggesting that circulating FGF21 levels serve as a predictive marker for mortality in these subjects.

Endothelial-to-mesenchymal transition: A novel therapeutic target for cardiovascular diseases

Endothelial-to-mesenchymal transition (EndMT) is a complex biological process in which endothelial cells lose their specific markers and acquire a mesenchymal or myofibroblastic phenotype. Similar to epithelial-to-mesenchymal transition (EMT), EndMT can be induced by multiple stimulants such as cytokines and metabolic factors that play crucial roles in the development of the cardiovascular system. Recent studies have demonstrated that EndMT may play a significant role in the pathogenesis of cardiovascular diseases (CVDs), and may represent a novel therapeutic target for cardiovascular remodeling and fibrotic disorders. The exact molecular mechanisms involved in cardiovascular pathogenesis that occur as a result of EndMT, however, are not fully explained. In this review, we reveal the multiple intercellular mechanisms of EndMT including stimulants, signaling pathways, and seek to explore the relationship between this biological process, cardiovascular system development, and CVDs that may lead to new therapeutic strategies for the treatment of CVDs.

Adipokines and cardiovascular disease: A comprehensive review

Adipokines are peptides that signal the functional status of adipose tissue to the brain and other target organs. In adipose tissue dysfunction, adipokine secretion is altered, and this can contribute to a spectrum of obesity-associated conditions including cardiovascular disease. Some adipokines have anti-inflammatory and cardioprotective effects (omentin, apelin, adiponectin). Others are pro-inflammatory with negative impact on cardiovascular function (leptin, visfatin, resistin, adipocyte fatty-acid-binding protein). In the first part, this article reviews the endocrine functions of adipose tissue in general, effects of the distribution and composition of fat tissue, and the roles of cortisol and the renin-angiotensin-aldosterone system in the development of the inflammatory state of addipose tissue. In the second part, the known cardiovascular effects of different adipokines and their clinical potential are discussed in detail.

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.

The Role of PPARγ in Cardiovascular Diseases

The peroxisome proliferator-activated receptors (PPAR) belong to the nuclear superfamily of ligand-activated transcription factors. PPARγ acts as a nutrient sensor that regulates several homeostatic functions. Its disruption can lead to vascular pathologies, disorders of fatty acid/lipid metabolism and insulin resistance. PPARγ can modulate several signaling pathways connected with blood pressure regulation. Firstly, it affects the insulin signaling pathway and endothelial dysfunction by modulation of expression and/or phosphorylation of signaling molecules through the PI3K/Akt/eNOS or MAPK/ET-1 pathways. Secondly, it can modulate gene expression of the renin- angiotensin system – cascade proteins, which potentially slow down the progression of atherosclerosis and hypertension. Thirdly, it can modulate oxidative stress response either directly through PPAR or indirectly through Nrf2 activation. In this context, activation and functioning of PPARγ is very important in the regulation of several disorders such as diabetes mellitus, hypertension and/or metabolic syndrome.