Possible role of fibroblast growth factor 21 on atherosclerosis via amelioration of endoplasmic reticulum stress-mediated apoptosis in apoE−/− mice

Adipokines, adiposity, and atherosclerosis

Characterized by a surplus of whole-body adiposity, obesity is strongly associated with the prognosis of atherosclerosis, a hallmark of coronary artery disease (CAD) and the major contributor to cardiovascular disease (CVD) mortality. Adipose tissue serves a primary role as a lipid-storage organ, secreting cytokines known as adipokines that affect whole-body metabolism, inflammation, and endocrine functions. Emerging evidence suggests that adipokines can play important roles in atherosclerosis development, progression, as well as regression. Here, we review the versatile functions of various adipokines in atherosclerosis and divide these respective functions into three major groups: protective, deteriorative, and undefined. The protective adipokines represented here are adiponectin, fibroblast growth factor 21 (FGF-21), C1q tumor necrosis factor-related protein 9 (CTRP9), and progranulin, while the deteriorative adipokines listed include leptin, chemerin, resistin, Interleukin- 6 (IL-6), and more, with additional adipokines that have unclear roles denoted as undefined adipokines. Comprehensively categorizing adipokines in the context of atherosclerosis can help elucidate the various pathways involved and potentially pave novel therapeutic approaches to treat CVDs.

Exploring the Relationship of Perivascular Adipose Tissue Inflammation and the Development of Vascular Pathologies

Initially thought to only provide mechanical support for the underlying blood vessels, perivascular adipose tissue (PVAT) has now emerged as a regulator of vascular function. A healthy PVAT exerts anticontractile and anti-inflammatory actions on the underlying vasculature via the release of adipocytokines such as adiponectin, nitric oxide, and omentin. However, dysfunctional PVAT produces more proinflammatory adipocytokines such as leptin, resistin, interleukin- (IL-) 6, IL-1β, and tumor necrosis factor-alpha, thus inducing an inflammatory response that contributes to the pathogenesis of vascular diseases. In this review, current knowledge on the role of PVAT inflammation in the development of vascular pathologies such as atherosclerosis and hypertension was discussed.

The role of FGF21 in the pathogenesis of cardiovascular disease

ABSTRACT

The morbidity and mortality of cardiovascular diseases (CVDs) are increasing worldwide and seriously threaten human life and health. Fibroblast growth factor 21 (FGF21), a metabolic regulator, regulates glucose and lipid metabolism and may exert beneficial effects on the cardiovascular system. In recent years, FGF21 has been found to act directly on the cardiovascular system and may be used as an early biomarker of CVDs. The present review highlights the recent progress in understanding the relationship between FGF21 and CVDs including coronary heart disease, myocardial ischemia, cardiomyopathy, and heart failure and also explores the related mechanism of the cardioprotective effect of FGF21. FGF21 plays an important role in the prediction, treatment, and improvement of prognosis in CVDs. This cardioprotective effect of FGF21 may be achieved by preventing endothelial dysfunction and lipid accumulating, inhibiting cardiomyocyte apoptosis and regulating the associated oxidative stress, inflammation and autophagy. In conclusion, FGF21 is a promising target for the treatment of CVDs, however, its clinical application requires further clarification of the precise role of FGF21 in CVDs.

CREBH Systemically Regulates Lipid Metabolism by Modulating and Integrating Cellular Functions

Cyclic AMP-responsive element-binding protein H (CREBH, encoded by CREB3L3) is a membrane-bound transcriptional factor expressed in the liver and small intestine. The activity of CREBH is regulated not only at the transcriptional level but also at the posttranslational level. CREBH governs triglyceride metabolism in the liver by controlling gene expression, with effects including the oxidation of fatty acids, lipophagy, and the expression of apolipoproteins related to the lipoprotein lipase activation and suppression of lipogenesis. The activation and functions of CREBH are controlled in response to the circadian rhythm. On the other hand, intestinal CREBH downregulates the absorption of lipids from the diet. CREBH deficiency in mice leads to severe hypertriglyceridemia and fatty liver in the fasted state and while feeding a high-fat diet. Therefore, when crossing CREBH knockout (KO) mice with an atherosclerosis model, low-density lipoprotein receptor KO mice, these mice exhibit severe atherosclerosis. This phenotype is seen in both liver- and small intestine-specific CREBH KO mice, suggesting that CREBH controls lipid homeostasis in an enterohepatic interaction. This review highlights that CREBH has a crucial role in systemic lipid homeostasis to integrate cellular functions related to lipid metabolism.

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.

Adipokines and Inflammation: Focus on Cardiovascular Diseases

It is well established that adipose tissue, apart from its energy storage function, acts as an endocrine organ that produces and secretes a number of bioactive substances, including hormones commonly known as adipokines. Obesity is a major risk factor for the development of cardiovascular diseases, mainly due to a low grade of inflammation and the excessive fat accumulation produced in this state. The adipose tissue dysfunction in obesity leads to an aberrant release of adipokines, some of them with direct cardiovascular and inflammatory regulatory functions. Inflammation is a common link between obesity and cardiovascular diseases, so this review will summarise the role of the main adipokines implicated in the regulation of the inflammatory processes occurring under the scenario of cardiovascular diseases.

Metabolic Inflammation-A Role for Hepatic Inflammatory Pathways as Drivers of Comorbidities in Nonalcoholic Fatty Liver Disease?

Nonalcoholic fatty liver disease (NAFLD) is a global and growing health concern. Emerging evidence points toward metabolic inflammation as a key process in the fatty liver that contributes to multiorgan morbidity. Key extrahepatic comorbidities that are influenced by NAFLD are type 2 diabetes, cardiovascular disease, and impaired neurocognitive function. Importantly, the presence of nonalcoholic steatohepatitis and advanced hepatic fibrosis increase the risk for systemic comorbidity in NAFLD. Although the precise nature of the crosstalk between the liver and other organs has not yet been fully elucidated, there is emerging evidence that metabolic inflammation-in part, emanating from the fatty liver-is the engine that drives cellular dysfunction, cell death, and deleterious remodeling within various body tissues. This review describes several inflammatory pathways and mediators that have been implicated as links between NAFLD and type 2 diabetes, cardiovascular disease, and neurocognitive decline.

FGF21 induces autophagy-mediated cholesterol efflux to inhibit atherogenesis via RACK1 up-regulation

Fibroblast growth factor 21 (FGF21) acts as an anti‐atherosclerotic agent. However, the specific mechanisms governing this regulatory activity are unclear. Autophagy is a highly conserved cell stress response which regulates atherosclerosis (AS) by reducing lipid droplet degradation in foam cells. We sought to assess whether FGF21 could inhibit AS by regulating cholesterol metabolism in foam cells via autophagy and to elucidate the underlying molecular mechanisms. In this study, ApoE^−/− mice were fed a high‐fat diet (HFD) with or without FGF21 and FGF21 + 3‐Methyladenine (3MA) for 12 weeks. Our results showed that FGF21 inhibited AS in HFD‐fed ApoE^−/− mice, which was reversed by 3MA treatment. Moreover, FGF21 increased plaque RACK1 and autophagy‐related protein (LC3 and beclin‐1) expression in ApoE^−/− mice, thus preventing AS. However, these proteins were inhibited by LV‐RACK1 shRNA injection. Foam cell development is a crucial determinant of AS, and cholesterol efflux from foam cells represents an important defensive measure of AS. In this study, foam cells were treated with FGF21 for 24 hours after a pre‐treatment with 3MA, ATG5 siRNA or RACK1 siRNA. Our results indicated that FGF21‐induced autophagy promoted cholesterol efflux to reduce cholesterol accumulation in foam cells by up‐regulating RACK1 expression. Interestingly, immunoprecipitation results showed that RACK1 was able to activate AMPK and interact with ATG5. Taken together, our results indicated that FGF21 induces autophagy to promote cholesterol efflux and reduce cholesterol accumulation in foam cells through RACK1‐mediated AMPK activation and ATG5 interaction. These results provided new insights into the molecular mechanisms of FGF21 in the treatment of AS.

The roles of FGF21 in atherosclerosis pathogenesis

FGF21 is a peptide hormone that regulates homeostasis of lipid and glucose as well as energy metabolism. It is mainly expressed and secreted in liver and adipose tissues, and it is expressed in lower amounts in the aorta. Recent clinical and preclinical studies indicate increased serum FGF21 levels in atherosclerosis patients. Also, FGF21 therapy has been reported to reduce the initiation and progression of atherosclerosis in animal models and in vitro studies. Moreover, growing evidence indicates that administration of exogenous FGF21 induces anti-atherosclerotic effects, because of its ability to reduce lipid profile, alleviation of oxidative stress, inflammation, and apoptosis. Therefore, FGF21 can not only be considered as a biomarker for predicting atherosclerosis, but also induce protective effects against atherosclerosis. Besides, serum levels of FGF21 increase in various diseases including in diabetes mellitus, hypertension, and obesity, which may be related to initiating and exacerbating atherosclerosis. On the other hand, FGF21 therapy significantly improves lipid profiles, and reduces vascular inflammation and oxidative stress in atherosclerosis related diseases. Therefore, further prospective studies are needed to clarify whether FGF21 can be used as a prognostic biomarker to identify individuals at future risk of atherosclerosis in these atherosclerosis-associated diseases. In this review, we will discuss the possible mechanism by which FGF21 protects against atherosclerosis.

FGF21 promotes functional recovery after hypoxic-ischemic brain injury in neonatal rats by activating the PI3K/Akt signaling pathway via FGFR1/β-klotho

Perinatal asphyxia often results in neonatal cerebral hypoxia-ischemia (HI), which is associated with high mortality and severe long-term neurological deficits in newborns. Currently, there are no effective drugs to mitigate the functional impairments post-HI. Previous studies have shown that fibroblast growth factor 21 (FGF21) has a potential neuroprotective effect against brain injury. However, the effect of FGF21 on neonatal HI brain injury is unclear. In the present study, both in vivo and in vitro models were used to assess whether recombinant human FGF21 (rhFGF21) could exert a neuroprotective effect after HI and explore the associated mechanism. The results showed that the rhFGF21 treatment remarkably reduced the infarct volume, ameliorated the body weight and improved the tissue structure after HI in neonatal rats. In addition, the rhFGF21 treatment lengthened the running endurance times in the rotarod test and decreased the mean escape latencies and increased the number of platform crossings in the Morris water maze test at 21 d post-HI insult. In contrast, the FGFR1 inhibitor PD173074 and PI3K inhibitor LY294002 partially reversed these therapeutic effects. In isolated primary cortical neurons, the rhFGF21 treatment protected primary neurons from oxygen-glucose deprivation (OGD) insult by inhibiting neuronal apoptosis and promoting neuronal survival. Both our in vivo and in vitro results reveal that rhFGF21 could inhibit neuronal apoptosis by activating the PI3K/Akt signaling pathway via FGF21/FGFR1/β-klotho complex formation. Therefore, rhFGF21 may be a promising therapeutic agent for promoting functional recovery after HI-induced neonatal brain injury.

Fibroblast Growth Factor 21 Attenuates Vascular Calcification by Alleviating Endoplasmic Reticulum Stress Mediated Apoptosis in Rats

Fibroblast growth factor 21 (FGF21), a hormone with multiple metabolic properties, has proven to be pleiotropic biological effects and may play pivotal role in numerous cardiovascular and metabolic diseases in the future. Vascular calcification (VC) is a concomitant pathological process of various cardiovascular and metabolic diseases. However, the effects of FGF21 on VC remain unclear. Therefore, in this research, we aimed to explore the roles and mechanisms of FGF21 in VC induced by vitamin D₃ plus nicotine (VDN) treatment rats. After 28 days VDN treatment, the calcium overload was confirmed by blood pressure, ultrasound imaging, calcium content, ALP activity and aortic pathological characteristics. In terms of FGF21, exogenous FGF21 can ameliorate the elevation of blood pressure, aortic calcification and related injury in VC rats. To investigate the mechanisms of FGF21 on VC, the endoplasmic reticulum stress (ERS) mediated apoptosis pathways were tested. As a method to detect apoptosis, the increased positive TUNEL staining cells were alleviated by FGF21 treatment. Furthermore, exogenous FGF21 can suppress the increased ERS chaperone, GRP78, in the calcified aortas. In the three pathways of ERS mediated apoptosis, we found CHOP pathway and caspase-12 pathway were involved in the treatment of FGF21, but not p-JNK/JNK pathway. Our study proved for the first time that FGF21 can inhibit the progress of VC by alleviating ERS mediated apoptosis in rats. FGF21 might be a new target for preventing and treating VC.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

Circulating level of fibroblast growth factor 21 is independently associated with the risks of unstable angina pectoris

There is increasing evidence that serum adipokine levels are associated with higher risks of cardiovascular diseases. As an important adipokine, fibroblast growth factor 21 (FGF21) has been demonstrated to be associated with atherosclerosis and coronary artery disease (CAD). However, circulating level of FGF21 in patients with angina pectoris has not yet been investigated. Circulating FGF21 level was examined in 197 patients with stable angina pectoris (SAP, n=66), unstable angina pectoris (UAP, n=76), and control subjects (n=55) along with clinical variables of cardiovascular risk factors. Serum FGF21 concentrations on admission were significantly increased more in patients with UAP than those with SAP (Ln-FGF21: 5.26 ± 0.87 compared with 4.85 ± 0.77, P<0.05) and control subjects (natural logarithm (Ln)-FGF21: 5.26 ± 0.87 compared with 4.54 ± 0.72, P<0.01). The correlation analysis revealed that serum FGF21 concentration was positively correlated with the levels of cardiac troponin I (cTnI) (r²  =  0.026, P=0.027) and creatine kinase-MB (CK-MB) (r²  =  0.023, P= 0.04). Furthermore, FGF21 level was identified as an independent factor associated with the risks of UAP (odds ratio (OR): 2.781; 95% CI: 1.476–5.239; P=0.002), after adjusting for gender, age, and body mass index (BMI). However, there were no correlations between serum FGF21 levels and the presence of SAP (OR: 1.248; 95% CI: 0.703–2.215; P=0.448). The present study indicates that FGF21 has a strong correlation and precise predictability for increased risks of UAP, that is independent of traditional risk factors of angina pectoris.

Protection Effect of Exogenous Fibroblast Growth Factor 21 on the Kidney Injury in Vascular Calcification Rats

Background:

Chronic kidney disease (CKD) is closely related to the cardiovascular events in vascular calcification (VC). However, little has known about the characteristics of kidney injury caused by VC. Fibroblast growth factor 21 (FGF21) is an endocrine factor, which takes part in various metabolic actions with the potential to alleviate metabolic disorder diseases. Even FGF21 has been regarded as a biomarker in CKD, the role of FGF21 in CKD remains unclear. Therefore, in this study, we evaluate the FGF21 on the kidney injury in VC rats.

Methods:

The male Sprague-Dawley rats were divided into three groups: (1) control group, (2) Vitamin D3 plus nicotine (VDN)-induced VC group, (3) FGF21-treated VDN group. After 4 weeks, the rats were killed and the blood was collected for serum creatinine, urea nitrogen, calcium, and phosphate measurement. Moreover, the renal tissues were homogenized for alkaline phosphatases (ALPs) activity and calcium content. The levels of FGF21 protein were measured by radioimmunoassay. The levels of β-Klotho and FGF receptor 1 (FGFR1) protein were measured by enzyme-linked immunosorbent assay (ELISA). The structural damage and calcifications in aortas were stained by Alizarin-red S. Moreover, the structure of kidney was observed by hematoxylin and eosin staining.

Results:

The renal function impairment caused by VDN modeling was ameliorated by FGF21 treatment, inhibited the elevated serum creatinine and urea level by 20.5% (34.750 ± 4.334 μmol/L vs. 27.630 ± 2.387 μmol/L) and 4.0% (7.038 ± 0.590 mmol/L vs. 6.763 ± 0.374 mmol/L; P < 0.01), respectively, together with the structural damages of glomerular atrophy and renal interstitial fibrosis. FGF21 treatment downregulated the ALP activity, calcium content in the kidney of VC rats by 42.1% (P < 0.01) and 11.7% (P < 0.05) as well as ameliorated the aortic injury and calcification as compared with VDN treatment alone group, indicating an ameliorative effect on VC. ELISA assays showed that the expression of β-Klotho, a component of FGF21 receptor system, was increased in VDN-treated VC rats by 37.4% (6.588 ± 0.957 pg/mg vs. 9.054 ± 0.963 pg/mg; P < 0.01), indicating an FGF21-resistant state. Moreover, FGF21 treatment downregulated the level of β-Klotho in renal tissue by 16.7% (9.054 ± 0.963 pg/mg vs. 7.544 ± 1.362 pg/mg; P < 0.05). However, the level of FGFR1, the receptor of FGF21, kept unchanged under VDN and VDN plus FGF21 administration (0.191 ± 0.0376 ng/mg vs. 0.189 ± 0.032 ng/mg vs. 0.181 ± 0.034 ng/mg; P > 0.05).

Conclusions:

In the present study, FGF21 was observed to ameliorate the kidney injury in VDN-induced VC rats. FGF21 might be a potential therapeutic factor in CKD by cutting off the vicious circle between VC and kidney injury.

Low Plasma Levels of Fibroblast Growth Factor-21 in Patients with Peripheral Artery Disease

AIM

Fibroblast growth factor-21 (FGF-21) is a metabolic regulator with beneficial effects on glucolipid metabolism. Since FGF-21 has lipid-lowering, anti-inflammatory and anti-oxidant properties, it may play a protective role against atherosclerosis. However, blood FGF-21 levels in coronary artery disease (CAD) or peripheral artery disease (PAD) have not been elucidated.

METHODS

We measured plasma FGF-21 levels in 417 patients undergoing coronary angiography, who also had ankle-brachial index test for PAD screening.

RESULTS

CAD was found in 224 patients (1-vessel [1-VD], n=92; 2-vessel [2-VD], n=65; 3-vessel disease [3-VD], n=67). No significant difference was found in the FGF-21 levels between 224 patients with CAD and 193 without CAD (median 26.0 vs. 25.9 pg/mL). FGF-21 levels in 4 groups of CAD(-), 1-VD, 2-VD, and 3-VD were 25.9, 37.2, 19.4, and 0.0 pg/mL. FGF-21 tended to be highest in 1-VD and lowest in 3-VD, but the difference did not reach statistical significance. PAD was found in 38 patients. Compared to the 379 patients without PAD, 38 with PAD had CAD more often (87% vs. 50%), especially 3-VD (P＜0.001). FGF-21 levels were lower in patients with PAD than in those without PAD (0.0 vs. 30.7 pg/mL, P＜0.02). In multivariate analysis, the FGF-21 level was an independent factor for PAD, but not for CAD. Odds ratio for PAD was 2.13 (95%CI=1.01-4.49) for a low FGF-21 level (＜15.6 pg/mL).

CONCLUSION

No significant difference was found in the FGF-21 levels between patients with and without CAD. However, FGF-21 levels were low in patients with PAD, and were a factor for PAD independent of atherosclerotic risk factors.

Fibroblast growth factor 21 inhibits atherosclerosis in apoE-/- mice by ameliorating Fas-mediated apoptosis

Background

FGF21 is a critical endogenous regulator in energy homeostasis and systemic glucose and lipid metabolism. Despite intensive study of the metabolic functions of FGF21, its important role in heart disease needs further exploration. Apoptosis induced by ox-LDL in vascular endothelial cells is an important step in the progress of atherosclerosis.

Methods

The effects of FGF21 treatment on apoptosis induced by ox-LDL were tested in HUVECs. The role of FGF21 in atherosclerosis was studied by evaluating its function in apolipoprotein E double knockout (apoE−/−) mice.

Results

We found that apoptosis in HUVECs was alleviated by FGF21 treatment. The effects of FGF21 were independent of the ERK1/2 pathway and were mediated through inhibition of the Fas signaling pathway. FGF21 suppressed the development of atherosclerosis, and the administration of FGF21 ameliorated Fas-mediated apoptosis in apoE−/− mice.

Conclusion

FGF21 protects against apoptosis in HUVECs by suppressing the expression of Fas; furthermore, FGF21 alleviated atherosclerosis by ameliorating Fas-mediated apoptosis in apoE−/− mice.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0846-x) contains supplementary material, which is available to authorized users.

CREBH Regulates Systemic Glucose and Lipid Metabolism

The cyclic adenosine monophosphate (cAMP)-responsive element-binding protein H (CREBH, encoded by CREB3L3) is a membrane-bound transcriptional factor that primarily localizes in the liver and small intestine. CREBH governs triglyceride metabolism in the liver, which mediates the changes in gene expression governing fatty acid oxidation, ketogenesis, and apolipoproteins related to lipoprotein lipase (LPL) activation. CREBH in the small intestine reduces cholesterol transporter gene Npc1l1 and suppresses cholesterol absorption from diet. A deficiency of CREBH in mice leads to severe hypertriglyceridemia, fatty liver, and atherosclerosis. CREBH, in synergy with peroxisome proliferator-activated receptor α (PPARα), has a crucial role in upregulating Fgf21 expression, which is implicated in metabolic homeostasis including glucose and lipid metabolism. CREBH binds to and functions as a co-activator for both PPARα and liver X receptor alpha (LXRα) in regulating gene expression of lipid metabolism. Therefore, CREBH has a crucial role in glucose and lipid metabolism in the liver and small intestine.

Serum FGF21 Is Associated with Future Cardiovascular Events in Patients with Coronary Artery Disease

Objectives: To investigate whether serum fibroblast growth factor 21 (FGF21) levels can be used to predict the future development of major adverse cardiovascular events (MACEs). Methods: This study included 253 patients who received subsequent follow-up, and complete data were collected for 234 patients. Independent predictors of MACEs were identified by using the Cox proportional-hazards regression analysis. The prognostic value of FGF21 levels for MACEs was evaluated by Kaplan-Meier survival analysis. Results: Of 229 patients finally enrolled in the analysis, 27/60 without coronary artery disease (CAD) at baseline experienced a MACE, and 132/169 patients with CAD at baseline experienced a MACE. Among patients with CAD at baseline, serum FGF21 levels were significantly higher in patients with MACEs (p < 0.05) than in patients without MACEs. Kaplan-Meier survival analysis showed patients with a higher serum FGF21 had a significantly lower event-free survival (p = 0.001) than those with a lower level. Further Cox proportional-hazards regression analysis, including the traditional risk factors for cardiovascular disease, showed that serum FGF21 was an independent predictor of MACE occurrence. Conclusions: In patients with CAD at baseline, an elevated serum FGF21 level was associated with the development of a MACE in the future.

The relationship of circulating fibroblast growth factor 21 levels with incident atrial fibrillation: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

Elevated circulating levels of fibroblast growth factor 21 (FGF21) are associated with multiple cardiovascular disease (CVD) risk factors and incident events. Previous small cross-sectional studies, mainly in Chinese populations, have suggested FGF21 may play a role in the development of atrial fibrillation (AF). We therefore investigated the relationship of FGF21 levels with incident AF in participants free of clinically apparent CVD at baseline in a large, multi-ethnic cohort.

METHODS

A total of 5729 participants of four major ethnic groups (Caucasian, African American, Hispanic American, and Chinese American) from the Multi-Ethnic Study of Atherosclerosis (MESA), who were free of AF and had plasma FGF21 levels measured by ELISA at the baseline exam, were included in the analysis. Participants were followed up for incident AF over a median period of 12.9 years. Cox proportional hazards regression analysis was used.

RESULTS

Among the 5729 participants, 778 participants developed incident AF. Participants with incident AF had significantly higher baseline FGF21 levels than those without incident AF (median = 166.0 and 142.8 pg/mL, p < 0.001). After adjusting for possible confounders, including demographic, socioeconomic and lifestyle factors, traditional CVD risk factors and circulating inflammatory markers, higher baseline FGF21 levels did not predict incident AF over the follow up period. There was no effect modification by sex or ethnicity.

CONCLUSIONS

Baseline FGF21 levels were not associated with the development of AF in an ethnically diverse population followed long-term. Our findings do not support an important role of FGF21 in AF development.

Fibroblast Growth Factor 21-Metabolic Role in Mice and Men

Since its identification in 2000, the interest of scientists in the hepatokine fibroblast growth factor (FGF) 21 has tremendously grown, and still remains high, due to a wealth of very robust data documenting this factor's favorable effects on glucose and lipid metabolism in mice. For more than ten years now, intense in vivo and ex vivo experimentation addressed the physiological functions of FGF21 in humans as well as its pathophysiological role and pharmacological effects in human metabolic disease. This work produced a comprehensive collection of data revealing overlaps in FGF21 expression and function but also significant differences between mice and humans that have to be considered before translation from bench to bedside can be successful. This review summarizes what is known about FGF21 in mice and humans with a special focus on this factor's role in glucose and lipid metabolism and in metabolic diseases, such as obesity and type 2 diabetes mellitus. We highlight the discrepancies between mice and humans and try to decipher their underlying reasons.

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.

Regulation of longevity by FGF21: Interaction between energy metabolism and stress responses

Fibroblast growth factor 21 (FGF21) is a hormone-like member of FGF family which controls metabolic multiorgan crosstalk enhancing energy expenditure through glucose and lipid metabolism. In addition, FGF21 acts as a stress hormone induced by endoplasmic reticulum stress and dysfunctions of mitochondria and autophagy in several tissues. FGF21 also controls stress responses and metabolism by modulating the functions of somatotropic axis and hypothalamic-pituitary-adrenal (HPA) pathway. FGF21 is a potent longevity factor coordinating interactions between energy metabolism and stress responses. Recent studies have revealed that FGF21 treatment can alleviate many age-related metabolic disorders, e.g. atherosclerosis, obesity, type 2 diabetes, and some cardiovascular diseases. In addition, transgenic mice overexpressing FGF21 have an extended lifespan. However, chronic metabolic and stress-related disorders involving inflammatory responses can provoke FGF21 resistance and thus disturb healthy aging process. First, we will describe the role of FGF21 in interorgan energy metabolism and explain how its functions as a stress hormone can improve healthspan. Next, we will examine both the induction of FGF21 expression via the integrated stress response and the molecular mechanism through which FGF21 enhances healthy aging. Finally, we postulate that FGF21 resistance, similarly to insulin resistance, jeopardizes human healthspan and accelerates the aging process.

Fibroblast growth factor 21 plays an inhibitory role in vascular calcification in vitro through OPG/RANKL system

Vascular calcification is prevalent and associated with adverse outcome without available therapy. The benefits of fibroblast growth factor (FGF)-21 on metabolism and atherosclerosis make it a promising therapeutic agent for vascular calcification. We investigated the effects of FGF21 on vascular smooth muscle cell (VSMC) calcification by culturing rat VSMCs in a calcifying medium for 9days. FGF21 markedly attenuated mineral deposition and apoptosis at the indicated time points. In the presence of FGF21, the expression levels of osteoblastic protein including bone morphogenic protein-2, alkaline phosphatase(ALP), runt-related transcription factor(RUNX)-2 and nuclear factor-kappa B ligand (RANKL) were down-regulated, whereas the expression of osteoprotegerin (OPG) increased. Knockdown of OPG significantly impaired inhibition of FGF21 on apoptosis and the expression of pro-apoptotic genes including caspase-3 and Bax and osteoblastic -promoting markers including ALP, RUNX-2 and RANKL. Furthermore, FGF21 facilitated the phosphoryl of AKT but suppressed P38, while OPG knockdown attenuated the effects. LY29400 (inhibitor of PI3K) abrogated the activation of PI3K/AKT and SB203580 (inhibitor of P38) abolished the inhibition of FGF21 on P38, while alteration was observed in the expression of RUNX-2. FGF21 inhibited VSMCs calcification via OPG/RANKL system, and through P38 andPI3K/AKT pathways.

Endoplasmic Reticulum Stress in Arterial Smooth Muscle Cells: A Novel Regulator of Vascular Disease

Cardiovascular disease continues to be the leading cause of death in industrialised societies. The idea that the arterial smooth muscle cell (ASMC) plays a key role in regulating many vascular pathologies has been gaining importance, as has the realisation that not enough is known about the pathological cellular mechanisms regulating ASMC function in vascular remodelling. In the past decade endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) have been recognised as a stress response underlying many physiological and pathological processes in various vascular cell types. Here we summarise what is known about how ER stress signalling regulates phenotypic switching, trans/dedifferentiation and apoptosis of ASMCs and contributes to atherosclerosis, hypertension, aneurysms and vascular calcification.

Vildagliptin and caloric restriction for cardioprotection in pre-diabetic rats

Long-term high-fat diet (HFD) consumption causes cardiac dysfunction. Although calorie restriction (CR) has been shown to be useful in obesity, we hypothesized that combined CR with dipeptidyl peptidase-4 (DPP-4) inhibitor provides greater efficacy than monotherapy in attenuating cardiac dysfunction and metabolic impairment in HFD-induced obese-insulin resistant rats. Thirty male Wistar rats were divided into 2 groups to be fed on either a normal diet (ND, n = 6) or a HFD (n = 24) for 12 weeks. Then, HFD rats were divided into 4 subgroups (n = 6/subgroup) to receive just the vehicle, CR diet (60% of mean energy intake and changed to ND), vildagliptin (3 mg/kg/day) or combined CR and vildagliptin for 4 weeks. Metabolic parameters, heart rate variability (HRV), cardiac mitochondrial function, left ventricular (LV) and fibroblast growth factor (FGF) 21 signaling pathway were determined. Rats on a HFD developed insulin and FGF21 resistance, oxidative stress, cardiac mitochondrial dysfunction and impaired LV function. Rats on CR alone showed both decreased body weight and visceral fat accumulation, whereas vildagliptin did not alter these parameters. Rats in CR, vildagliptin and CR plus vildagliptin subgroups had improved insulin sensitivity and oxidative stress. However, vildagliptin improved heart rate variability (HRV), cardiac mitochondrial function and LV function better than the CR. Chronic HFD consumption leads to obese-insulin resistance and FGF21 resistance. Although CR is effective in improving metabolic regulation, vildagliptin provides greater efficacy in preventing cardiac dysfunction by improving anti-apoptosis and FGF21 signaling pathways and attenuating cardiac mitochondrial dysfunction in obese-insulin-resistant rats.

Impact of fibroblast growth factor 21 on the secretome of human perivascular preadipocytes and adipocytes: a targeted proteomics approach

CONTEXT

Perivascular adipose tissue (PVAT) is suggested to impact on vascular cells via humoral factors, possibly contributing to endothelial dysfunction and atherosclerosis.

OBJECTIVE

To address whether the hepatokine fibroblast growth factor (FGF) 21 affects the PVAT secretome.

METHODS

Human perivascular (pre)adipocytes were subjected to targeted proteomics and whole-genome gene expression analysis.

RESULTS

Preadipocytes, as compared to adipocytes, secreted higher amounts of inflammatory cytokines and chemokines. Adipocytes released higher amounts of adipokines [e.g. adipisin, visfatin, dipeptidyl peptidase 4 (DPP4), leptin; p < 0.05, all]. In preadipocytes, omentin 1 release was 1.28-fold increased by FGF-21 (p < 0.05). In adipocytes, FGF-21 reduced chemerin release by 5% and enhanced DPP4 release by 1.15-fold (p < 0.05, both). FGF-21 altered the expression of four secretory genes in preadipocytes and of 18 in adipocytes (p < 0.01, all).

CONCLUSION

The hepatokine FGF-21 exerts secretome-modulating effects in human perivascular (pre)adipocytes establishing a new liver-PVAT-blood vessel axis that possibly contributes to vascular inflammation and atherosclerosis.

Naringenin ameliorates hypoxia/reoxygenation-induced endoplasmic reticulum stress-mediated apoptosis in H9c2 myocardial cells: involvement in ATF6, IRE1α and PERK signaling activation

Naringenin, a flavanone mainly derived from grapes and citrus fruits, has been reported to exhibit cardioprotective effects. Accumulating evidence has confirmed that endoplasmic reticulum (ER) stress-mediated apoptosis participates in the process of myocardial ischemia/reperfusion injury and inhibiting ER stress is a potential therapeutic target/strategy in preventing cardiovascular diseases. Herein, the current study was designed to investigate whether naringenin protects H9c2 myocardial cells against hypoxia/reoxygenation (H/R) injury via attenuating ER stress or ER stress-mediated apoptosis. Our results showed that naringenin treatment resulted in obvious increases in the viability of H9c2 cells and the expression of Bcl-2 (anti-apoptotic protein), and decreases in the morphological changes of apoptotic cells, the activity of caspase-3 and the expression of Bax (pro-apoptotic protein) in H/R-treated H9c2 cells, implying the protective effects of naringenin against H/R-induced injury. In addition, naringenin also significantly reversed H/R-induced ER stress as evidenced by the up-regulation of Glucose-regulated protein 78, C/EBP homologous protein and Cleaved caspase-12 proteins. Meanwhile, naringenin remarkably reversed H/R-induced the increases in the expression of cleaved activating transcription factor 6 (ATF6) and phosphorylation levels of phospho-extracellular regulated protein kinases (PERK) and inositol-requiring enzyme-1α (IRE1α) in H9c2 cells. Finally, we found that ATF6 siRNA, PERK siRNA or IRE1α siRNA abolished H/R-induced cytotoxicity and apoptosis in H9c2 cells. In conclusion, these results confirmed that ER stress-mediated apoptosis contributes to the protection effects of naringenin against H/R injury, which is potentially involved in ATF6, IRE1α and PERK signaling activation.

The FGF21-adiponectin axis in controlling energy and vascular homeostasis

Whole-body energy metabolism and cardiovascular homeostasis are tightly controlled processes that involve highly coordinated crosstalk among distal organs. This is mainly achieved by a large number of hormones released from each organ. Among them, fibroblast growth factor 21 (FGF21) and adiponectin have recently gained considerable attention, since both of them possess multiple profound protective effects against a myriad of cardio-metabolic disorders. Despite their distinct structures and production sites, these two hormones share striking functional similarity. This dichotomy is recently reconciled by the demonstration of the FGF21-adiponectin axis. In adipocytes, both transcription and secretion of adiponectin are strongly induced by FGF21, which is partially dependent on PPARγ activity. Furthermore, the glucose-lowering, lipid-clearing, and anti-atherosclerotic functions of FGF21 are diminished in adiponectin-null mice, suggesting that adiponectin serves as an obligatory mediator of FGF21-elicited metabolic and vascular benefits. However, in both animals and human subjects with obesity, circulating FGF21 levels are increased whereas plasma adiponectin concentrations are reduced, perhaps due to FGF21 resistance, suggesting that dysfunctional FGF21-adiponectin axis is an important contributor to the pathogenesis of obesity-related cardio-metabolic syndrome. The FGF21-adiponectin axis protects against a cluster of cardio-metabolic disorders via mediating multi-organ communications, and is a promising target for therapeutic interventions of these chronic diseases.

Implication of hepatokines in metabolic disorders and cardiovascular diseases

The liver is a central regulator of systemic energy homeostasis and has a pivotal role in glucose and lipid metabolism. Impaired gluconeogenesis and dyslipidemia are often observed in patients with nonalcoholic fatty liver disease (NAFLD). The liver is now recognized to be an endocrine organ that secretes hepatokines, which are proteins that regulate systemic metabolism and energy homeostasis. Hepatokines are known to contribute to the pathogenesis of metabolic syndrome, NAFLD, type 2 diabetes (T2DM), and cardiovascular diseases (CVDs). In this review, we focus on the roles of two major hepatokines, fetuin-A and fibroblast growth factor 21 (FGF21), as well as recently-redefined hepatokines, such as selenoprotein P, angiopoietin-like protein 4 (ANGPTL4), and leukocyte cell-derived chemotaxin 2 (LECT2). We also assess the biology and molecular mechanisms of hepatokines in the context of their potential as therapeutic targets for metabolic disorders and cardiovascular diseases.

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The roles of hepatokines such as fetuin-A, FGF21, selenoprotein P, ANGPTL4, and LECT2

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The molecular mechanisms of hepatokines in metabolic disorders and CVD

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Hepatokines as therapeutic strategies for metabolic disorders and CVD

Physiological and Pharmacological Roles of FGF21 in Cardiovascular Diseases

Cardiovascular disease (CVD) is one of the most severe diseases in clinics. Fibroblast growth factor 21 (FGF21) is regarded as an important metabolic regulator playing a therapeutic role in diabetes and its complications. The heart is a key target as well as a source of FGF21 which is involved in heart development and also induces beneficial effects in CVDs. Our review is to clarify the roles of FGF21 in CVDs. Strong evidence showed that the development of CVDs including atherosclerosis, coronary heart disease, myocardial ischemia, cardiac hypertrophy, and diabetic cardiomyopathy is associated with serum FGF21 levels increase which was regarded as a compensatory response to induced cardiac protection. Furthermore, administration of FGF21 suppressed the above CVDs. Mechanistic studies revealed that FGF21 induced cardiac protection likely by preventing cardiac lipotoxicity and the associated oxidative stress, inflammation, and apoptosis. Normally, FGF21 induced therapeutic effects against CVDs via activation of the above kinases-mediated pathways by directly binding to the FGF receptors of the heart in the presence of β-klotho. However, recently, growing evidence showed that FGF21 induced beneficial effects on peripheral organs through an indirect way mediated by adiponectin. Therefore whether adiponectin is also involved in FGF21-induced cardiac protection still needs further investigation.

Effects of fibroblast growth factor 21 on the heart

Fibroblast growth factor 21 (FGF21) is a novel polypeptide ligand that has been shown to be involved in several physiological and pathological processes including regulation of glucose and lipids as well as reduction of arteriosclerotic plaque formation in the great vessels. It has also been shown to exert cardioprotective effects in myocardial infarction, cardiac ischemia-reperfusion injury, cardiac hypertrophy and diabetic cardiomyopathy. Moreover, FGF21 protects the myocardium and great arteries by attenuating remodeling, inflammation, oxidative stress and also promoting the energy supply to the heart through fatty acid β-oxidation. This growing evidence emphasizes the important roles of FGF21 in cardioprotection. This review comprehensively summarizes and discusses the consistent and inconsistent findings regarding the beneficial effects of FGF21 on the heart available from both basic research and clinical reports. The details of the signaling, biological and pharmacological effects of FGF21 with regard to its protection of the heart are also presented and discussed in this review.

FGF21 Revolutions: Recent Advances Illuminating FGF21 Biology and Medicinal Properties

The biology of fibroblast growth factor 21 (FGF21) has evolved through its first decade at a revolutionary pace with dramatic refinements in this relatively short span of time. This field is poised now with a deeper understanding of its specific physiological role, pathological ramifications for its inappropriate function, and a much-enriched context of the complex hormonal network in which it serves to regulate metabolism. As a derivative of these discoveries, the application of FGF21 as a medicinal agent has emerged with structurally optimized protein-based analogs being preclinically explored in multiple species, and, more recently, through clinical studies. These novel findings set a foundation for ongoing inquiries that structure future research into this intriguing protein.

Mesenchymal Stem Cells Stabilize Atherosclerotic Vulnerable Plaque by Anti-Inflammatory Properties

Background and objectives

Formation and progression of atherosclerotic vulnerable plaque (VP) is the primary cause of many cardio-cerebrovascular diseases such as acute coronary syndrome and stroke. It has been reported that bone marrow mesenchymal stem cells (MSC) exhibit protective effects against many kinds of diseases including myocardial infarction. Here, we examined the effects of intravenous MSC infusion on a VP model and provide novel evidence of its influence as a therapy in this animal disease model.

Subjects and methods

Thirty healthy male New Zealand white rabbits were randomly divided into a MSC, VP or stable plaque (SP) group (n = 10/group) and received high fat diet and cold-induced common carotid artery intimal injury with liquid nitrogen to form atherosclerotic plaques. Serum hs-CRP, TNF-α, IL-6 and IL-10 levels were measured by ELISA at 1, 2, 3, 7, 14, 21 and 28 days after MSC transplantation. The animals were sacrificed at 4 weeks after MSC transplantation. Lesions in the right common carotid were observed using H&E and Masson staining, and the fibrous cap/lipid core ratio of atherosclerotic plaques were calculated. The expression of nuclear factor κB (NF-κB) and matrix metalloproteinase 1, 2, 9 (MMP-1,2,9) in the plaque were detected using immunohistochemistry, and apoptotic cells in the plaques were detected by TUNEL. In addition, the level of TNF-α stimulated gene/protein 6 (TSG-6) mRNA and protein were measured by quantitative Real-Time PCR and Western blotting, respectively.

Results

Two rabbits in the VP group died of lung infection and cerebral infarction respectively at 1 week after plaque injury by liquid nitrogen. Both H&E and Masson staining revealed that the plaques from the SP and MSC groups had more stable morphological structure and a larger fibrous cap/lipid core ratio than the VP group. Serum hs-CRP, TNF-α and IL-6 were significantly down-regulated, whereas IL-10 was significantly up-regulated in the MSC group compared with the VP group. .Immunohistochemistry analysis revealed that NF-κB and MMP expression was reduced in the MSC and SP groups compared to the VP group. Cell apoptosis decreased significantly in both the MSC and SP groups in comparison to the VP group. TSG-6 mRNA and protein expression were higher in the plaques of the MSC group compared to the VP and SP groups.

Conclusions

Our study results suggest that MSC transplantation can effectively stabilize vulnerable plaques in atherosclerotic rabbits. This may potentially offer a new clinical application of MSC in atherosclerosis.

Serum fibroblast growth factor 21 levels is associated with lower extremity atherosclerotic disease in Chinese female diabetic patients

Background

Fibroblast growth factor 21 (FGF21) is an emerging metabolic regulator associated with glucose and lipid metabolism, and it is still unclear whether FGF21 is related to atherosclerosis. Here, we explored the potential link between FGF21 and lower extremity atherosclerotic disease (LEAD) in type 2 diabetic patients.

Methods

A cross-sectional study was conducted on 504 type 2 diabetic patients (283 men, 221 women). LEAD was defined by Ankle-brachial index (ABI) <0.9 and lower extremity arterial plaque evaluated by color Doppler ultrasound. Serum FGF21 concentrations were quantified by a sandwich enzyme-linked immunosorbent assay.

Results

The total FGF21 levels of male and female patients had no significant differenence ((299.14(177.31-534.49) vs 362.50(214.01-578.73), P=0.516). Serum FGF21 levels in LEAD group were significantly higher than non-LEAD group in females (385.34(243.89-661.54) vs 313.13(156.38-485.79), P=0.006), while not in male patients (295.52(177.09-549.64) vs 342.09 (198.70-549.87), P=0.613). In diabetic women, subjects with LEAD had significantly higher serum FGF21 regardless of non-alcoholic fatty liver disease (NAFLD) (P < 0.05). And serum FGF21 levels were positively correlated with waist circumference and systolic blood pressure after adjusted for age and BMI (r=0.198, P=0.004; r=0.152, P=0.027; respectively). Moreover, FGF21 was independently tied to femoral intima-media thickness (FIMT) (β=0.208, P=0.031). After adjusted for other LEAD risk factors, FGF21 was demonstrated to be an independent risk factor for LEAD in type 2 diabetic women (OR, 1.106; 95%CI 1.008-1.223; P=0.028). In addition, FGF21 was negatively correlated with estradiol in premenopausal diabetic women (r=−0.368, P=0.009). After adjusted for estradiol, serum FGF21 levels were still positively associated with FIMT in premenopausal diabetic women (r=0.381, P=0.007). In diabetic men, serum FGF21 levels were correlated with triglyceride and C-reactive protein even after adjusted for age and BMI (r=0.204, P=0.001; r=0.312, P < 0.001; respectively). However, serum FGF21 was not an independent impact factor for LEAD in men (P > 0.05).

Conclusions

Serum FGF21 level independently and positively links LEAD in Chinese women with type 2 diabetes. The gender difference may be due to different estrogen levels.

The role of fibroblast growth factor 21 in the pathogenesis of non-alcoholic fatty liver disease and implications for therapy

Non-alcoholic fatty liver disease (NAFLD) includes a cluster of liver disorders ranging from simple fatty liver to non-alcoholic steatohepatitis (NASH) and cirrhosis. Due to its liver and vascular complications, NAFLD has become a public health problem with high morbidity and mortality. The pathogenesis of NAFLD is considered a "multi-hit hypothesis" that involves lipotoxicity, oxidative stress, endoplasmic reticulum stress, a chronic inflammatory state and mitochondrial dysfunction. Fibroblast growth factor 21 (FGF21) is a member of the fibroblast growth factor family with multiple metabolic functions. FGF21 directly regulates lipid metabolism and reduces hepatic lipid accumulation in an insulin-independent manner. Several studies have shown that FGF21 can ameliorate the "multi-hits" in the pathogenesis of NAFLD. The administration of FGF21 reverses hepatic steatosis, counteracts obesity and alleviates insulin resistance in rodents and nonhuman primates. Using several strategies, we show that the reversal of simple fatty liver and NASH is mediated by activation of the FGF21 signaling pathway. In this review, we describe the molecular mechanisms involved in the onset and/or progression of NAFLD, and review the current literature to highlight the therapeutic procedures associated with the FGF21 signaling pathway for simple fatty liver and NASH, which are the two most important types of NAFLD.