Fibroblast growth factor 21 (FGF21) inhibits macrophage-mediated inflammation by activating Nrf2 and suppressing the NF-κB signaling pathway

Fusion protein of FGF21 and elastin-like peptide improves wound healing in diabetic mice via inflammation modulation, collagen synthesis, and vascular network formation

Chronic-healing skin wounds are a common complication in diabetic individuals. To alleviate patient suffering, there is a pressing demand for more effective strategies to expedite the repair of diabetic wounds. Fibroblast growth factor 21(FGF21) has been proven to accelerate wound healing, but its stability and ability to assist in the healing of diabetic ulcers have not met expectations. Therefore, we have fused FGF21 with an elastin-like peptide (ELP) to create a recombinant fusion protein (abbreviated as "ELF") to increase the bioactivity and stability in vitro or in vivo. Our results demonstrated that ELF significantly improved the efficiency of FGF21 purification due to the inverse temperature responsive phase transition property of ELP. Meanwhile, the fusion strategy did not impair the structure of FGF21 or diminish its activity, as demonstrated by the highly similar secondary structure of ELF and FGF21, and their considerable inhibitory activity in the glucose consumption experiment of Huh-7 cells. An in vitro migration assay revealed that ELF promoted healing more effectively than either free FGF21 or ELP. Further in vivo study revealed the ability of ELF to improve skin wound healing quality, manifested by lower levels of inflammatory factors, more collagen formation and deposition, and the formation of robust vascular networks, though there was no significant difference in healing rate among the ELF, FGF21, and ELP groups. In conclusion, our study indicated that FGF21 and ELP fusion molecules could be developed as more efficient and cost-effective therapeutic strategies for diabetic wound healing.

FGF21 relieves calcium oxalate-induced cell injury, apoptosis, oxidative damage and ferroptosis of renal tubular epithelial cells through activating Nrf2 signaling pathway

Nephrolithiasis is a common urological disease accompanied by high morbidity worldwide. Evidences indicate that high-level CaOx crystals in the body can lead to renal tubular epithelial cell (RTEC) injury and RTEC injury is a critical precipitating factor for the formation of kidney stones. FGF21 has recently been revealed as the considerable marker in various kidney dysfunction and exerts the nephroprotective effects in various kidney diseases. This current study was formulated to fully elucidate the biological role of FGF21 in nephrolithiasis and probe into the intrinsic mechanisms underlying the protective effects of FGF21 against RTEC injury. In this work, HK-2 cells were incubated with 100 mg/ml COM for 24 h to establish in vitro RTEC injury model. COM-treated HK-2 cells were transfected with Oe-FGF21 to perform gain-of-function experiments. For rescue experiments, HK-2 cells were pretreated with 10 μM Nrf2 inhibitor ML385 for 24 h to thoroughly discuss the role of Nrf2 signaling in FGF21-mediating nephroprotective effects. It was verified that overexpression of FGF21 relieved COM-induced proliferation inhibition, cell injury, apoptosis, oxidative damage and ferroptosis of RTECs. ML385 treatment partially abolished the protective effects of FGF21 against COM injury in RTECs. In conclusion, up-regulation of FGF21 can relieve COM-induced proliferation inhibition, cell injury, apoptosis, oxidative damage and ferroptosis of RTECs through activating Nrf2 signaling pathway.

Mitigation of gestational diabetes-induced endothelial dysfunction through FGF21-NRF2 pathway activation involving L-Cystine

Gestational diabetes mellitus (GDM) disrupts glucolipid metabolism, endangering maternal and fetal health. Despite limited research on its pathogenesis and treatments, we conducted a study using serum samples from GDM-diagnosed pregnant women. We performed metabolic sequencing to identify key small molecule metabolites and explored their molecular interactions with FGF21. We also investigated FGF21's impact on GDM using blood samples from affected women. Our analysis revealed a novel finding: elevated levels of L-Cystine in GDM patients. Furthermore, we observed a positive correlation between L-Cystine and FGF21 levels, and found that L-Cystine induces NRF2 expression via FGF21 for a period of 96 h. Under high glucose (HG) conditions, FGF21 upregulates NRF2 and downstream genes NQO1 and EPHX1 via AKT phosphorylation induced by activation of IRS1, enhancing endothelial function. Additionally, we confirmed that levels of FGF21, L-Cystine, and endothelial function at the third trimester were effectively enhanced through appropriate exercise and diet during pregnancy in GDM patients (GDM + ED). These findings suggest FGF21 as a potential therapeutic agent for GDM, particularly in protecting endothelial cells. Moreover, elevated L-Cystine via appropriate exercise and diet might be a potential strategy to enhance FGF21's efficacy.

Enhanced Insulin Secretion Through Upregulation of Transcription Factors by Hydroalcoholic Extract of Securigera securidaca Seeds in Diabetic Animal Model

AIM

In previous studies, the researchers observed an increase in insulin secretion in STZ-treated diabetic rats following treatment with the hydroalcoholic extract of Securigera securidaca (HESS) seeds. This study focuses on the relationship between the antioxidant properties of HESS with changes in diabetic pancreatic tissue and the gene expression of factors that impact insulin secretion.

METHODS

In this controlled experimental study, three varying doses of HESS were administered to three groups of diabetic rats induced by STZ. Oxidative stress indicators like total antioxidant capacity (TAC), total oxidant status (TOS) and malondialdehyde were assessed in both pancreatic and liver tissues. Pancreatic histology was studied post-haematoxylin staining. Insulin and FGF21 levels in the blood were measured using the ELISA method. The expression of Nrf2 and FGF21 genes in the pancreas and liver, along with MafA and PDX-1 genes in the pancreas, was quantified using real-time PCR.

RESULTS

The administration of HESS in varying doses led to a dose-dependent rise in blood insulin levels and a decrease in blood glucose levels and oxidative stress. By reducing oxidative stress, HESS treatment lowered the heightened levels of NRF2 and FGF21 in the liver and pancreas of diabetic rats, improving pancreatic tissue health. As oxidative stress decreased, the expression of MafA and PDX1 genes in the pancreas approached levels seen in healthy rats.

CONCLUSION

HESS elicits an increase in insulin secretion through the mitigation of oxidative stress and tissue damage, as well as the modulation of gene expression related to the insulin transcription factors PDX-1 and MafA.

FGF21 agonists: An emerging therapeutic for metabolic dysfunction-associated steatohepatitis and beyond

The worldwide epidemics of obesity, hypertriglyceridemia, dyslipidaemia, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) represent a major economic burden on healthcare systems. Patients with at-risk MASH, defined as MASH with moderate or significant fibrosis, are at higher risk of comorbidity/mortality, with a significant risk of cardiovascular diseases and/or major adverse liver outcomes. Despite a high unmet medical need, there is only one drug approved for MASH. Several drug candidates have reached the phase III development stage and could lead to several potential conditional drug approvals in the coming years. Within the armamentarium of future treatment options, FGF21 analogues hold an interesting position thanks to their pleiotropic effects in addition to their significant effect on both MASH resolution and fibrosis improvement. In this review, we summarise preclinical and clinical data from FGF21 analogues for MASH and explore additional potential therapeutic indications.

FGF21 protects against ischaemia reperfusion injury in normal and fatty livers

BACKGROUND

Liver ischaemia/reperfusion (I/R) injury, which is an inevitable clinical problem of liver resection, liver transplantation and haemorrhagic shock. Fibroblast growth factor 21 (FGF21) was intimately coupled with multiple metabolic processes and proved to protect against apoptosis and inflammatory response in hepatocytes during hepatic I/R injury. However, the regulatory mechanisms of FGF21 in hepatic I/R injury remains unknown. Therefore, we hypothesize that FGF21 protects hepatic tissues from I/R injury.

METHODS

Blood samples were available from haemangiomas patients undergoing hepatectomy and murine liver I/R model and used to further evaluate the serum levels of FGF21 both in humans and mice. We further explored the regulatory mechanisms of FGF21 in murine liver I/R model by using FGF21-knockout mice (FGF21-KO mice) and FGF21-overexpression transgenic mice (FGF21-OE mice) fed a high-fat or ketogenic diet.

RESULTS

Our results show that the circulating levels of FGF21 were robustly decreased after liver I/R in both humans and mice. Silencing FGF21 expression with FGF21-KO mice aggravates liver injury at 6 h after 75 min of partial liver ischaemia, while FGF21-OE mice display alleviated hepatic I/R injury and inflammatory response. Compared with chow diet mice, exogenous FGF21 decreases the levels of aminotransferase, histological changes, apoptosis and inflammatory response in hepatic I/R injury treatment mice with a high-fat diet. Meanwhile, ketogenic diet mice are not sensitive to hepatic I/R injury.

CONCLUSIONS

The circulating contents of FGF21 are decreased during liver warm I/R injury and exogenous FGF21 exerts hepatoprotective effects on hepatic I/R injury. Thus, FGF21 regulates hepatic I/R injury and may be a key therapeutic target.

Fibroblast growth factor signaling in macrophage polarization: impact on health and diseases

Fibroblast growth factors (FGFs) are a versatile family of peptide growth factors that are involved in various biological functions, including cell growth and differentiation, embryonic development, angiogenesis, and metabolism. Abnormal FGF/FGF receptor (FGFR) signaling has been implicated in the pathogenesis of multiple diseases such as cancer, metabolic diseases, and inflammatory diseases. It is worth noting that macrophage polarization, which involves distinct functional phenotypes, plays a crucial role in tissue repair, homeostasis maintenance, and immune responses. Recent evidence suggests that FGF/FGFR signaling closely participates in the polarization of macrophages, indicating that they could be potential targets for therapeutic manipulation of diseases associated with dysfunctional macrophages. In this article, we provide an overview of the structure, function, and downstream regulatory pathways of FGFs, as well as crosstalk between FGF signaling and macrophage polarization. Additionally, we summarize the potential application of harnessing FGF signaling to modulate macrophage polarization.

Relationship of postprandial fibroblast growth factor 21 with lipids, inflammation and metabolic dysfunction-associated fatty liver disease during oral fat tolerance test

Introduction

Metabolic dysfunction-associated fatty liver disease (MAFLD) is closely associated with serum fibroblast growth factor (FGF) 21; however, previous studies have typically focused on the static fasting state, and the relationships between postprandial FGF21 levels, postprandial metabolic status, and MAFLD remain unclear. Therefore, we measured postprandial lipids, inflammatory factors, and FGF21 levels in MAFLD and further analyzed their relationship using an oral fat tolerance test (OFTT).

Patients and methods

In total, 103 non-diabetic adult volunteers, including 46 patients with MAFLD, were included in this study. All participants underwent the OFTT. Venous blood samples were collected at 0, 2, 4, and 6 h. Circulating total cholesterol (TC), triglyceride (TG), free fatty acid (FFA), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), interleukin-6(IL-6), tumor necrosis factor-α(TNF-α), hypersensitive-C reactive protein(hs-CRP) and FGF21 were assessed.

Results

Serum FGF21 significantly increased in the fasting state (P < 0.05) and showed a biphasic change of first decreasing and then increasing in MAFLD during the OFTT. The postprandial levels of TG, TC, LDL-C, FFA, IL-6, TNF-α and hs-CRP were significantly increased in MAFLD (P < 0.05). After adjusting for multiple factors, the FGF21 incremental area under the curve (iAUC) was linearly correlated with the FFA iAUC, TG iAUC, and IL-6 iAUC (P < 0.05) and was an independent factor for MAFLD (P < 0.05, OR=1.403).

Conclusion

Dyslipidemia and excessive inflammation in MAFLD are associated to FGF21 levels in the postprandial period. An abnormal postprandial FGF21 response may be an important mechanism of MAFLD.

MHO or MUO? White adipose tissue remodeling

In this review, we delve into the intricate relationship between white adipose tissue (WAT) remodeling and metabolic aspects in obesity, with a specific focus on individuals with metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO). WAT is a highly heterogeneous, plastic, and dynamically secreting endocrine and immune organ. WAT remodeling plays a crucial role in metabolic health, involving expansion mode, microenvironment, phenotype, and distribution. In individuals with MHO, WAT remodeling is beneficial, reducing ectopic fat deposition and insulin resistance (IR) through mechanisms like increased adipocyte hyperplasia, anti-inflammatory microenvironment, appropriate extracellular matrix (ECM) remodeling, appropriate vascularization, enhanced WAT browning, and subcutaneous adipose tissue (SWAT) deposition. Conversely, for those with MUO, WAT remodeling leads to ectopic fat deposition and IR, causing metabolic dysregulation. This process involves adipocyte hypertrophy, disrupted vascularization, heightened pro-inflammatory microenvironment, enhanced brown adipose tissue (BAT) whitening, and accumulation of visceral adipose tissue (VWAT) deposition. The review underscores the pivotal importance of intervening in WAT remodeling to hinder the transition from MHO to MUO. This insight is valuable for tailoring personalized and effective management strategies for patients with obesity in clinical practice.

Fibroblast Growth Factor 21 Relieves Lipopolysaccharide-Induced Acute Lung Injury by Suppressing JAK2/STAT3 Signaling Pathway

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a life-threatening disease without an effective drug at present. Fibroblast growth factor 21 (FGF21) was reported to be protective against inflammation in metabolic disease in recent studies. However, the role of FGF21 in ALI has been rarely investigated. In this study, it was found that the expression of FGF21 was markedly increased in lung tissue under lipopolysaccharide (LPS) stimulation in vivo, whereas it was decreased in lung epithelial cells under LPS stimulation in vitro. Therefore, our research aimed to elucidate the potential role of FGF21 in LPS-induced ALI and to detect possible underlying mechanisms. The results revealed that the deficiency of FGF21 aggravated pathological damage, inflammatory infiltration, and pulmonary function in LPS-induced ALI, while exogenous administration of FGF21 improved these manifestations. Moreover, through RNA sequencing and enrichment analysis, it was unveiled that FGF21 might play a protective role in LPS-induced ALI via JAK2/STAT3 signaling pathway. The therapeutic effect of FGF21 was weakened after additional usage of JAK2 activator in vivo. Further investigation revealed that FGF21 significantly inhibited STAT3 phosphorylation and impaired the nuclear translocation of STAT3 in vitro. In addition, the aggravation of inflammation caused by silencing FGF21 can be alleviated by JAK2 inhibitor in vitro. Collectively, these findings unveil a potent protective effect of FGF21 against LPS-induced ALI by inhibiting the JAK2/STAT3 pathway, implying that FGF21 might be a novel and effective therapy for ALI.

The role of microglial activation on ischemic stroke: Modulation by fibroblast growth factors

Stroke is one of the devastating clinical conditions that causes death and permanent disability. Its occurrence causes the reduction of oxygen and glucose supply, resulting in events such as inflammatory response, oxidative stress, and apoptosis in the brain. Microglia are brain-resident immune cells in the central nervous system (CNS) that exert diverse roles and respond to pathological process after an ischemic insult. The discovery of fibroblast growth factors (FGFs) in mammals, resulted to the findings that they can treat experimental models of stroke in animals effectively. FGFs function as homeostatic factors that control cells and hormones involved in metabolism, and they also regulate the secretion of proinflammatory (M1) and anti-inflammatory (M2) cytokines after stroke. In this review, we outline current evidence of microglia activation in experimental models of stroke focusing on its ability to exacerbate damage or repair tissue. Also, our review sheds light on the pharmacological actions of FGFs on multiple targets to regulate microglial modulation and highlighted their theoretical molecular mechanisms to provide possible therapeutic targets, as well as their limitations for the treatment of stroke. DATA AVAILABILITY: Not applicable.

Biomarkers of aging in frailty and age-associated disorders: State of the art and future perspective

According to the Geroscience concept that organismal aging and age-associated diseases share the same basic molecular mechanisms, the identification of biomarkers of age that can efficiently classify people as biologically older (or younger) than their chronological (i.e. calendar) age is becoming of paramount importance. These people will be in fact at higher (or lower) risk for many different age-associated diseases, including cardiovascular diseases, neurodegeneration, cancer, etc. In turn, patients suffering from these diseases are biologically older than healthy age-matched individuals. Many biomarkers that correlate with age have been described so far. The aim of the present review is to discuss the usefulness of some of these biomarkers (especially soluble, circulating ones) in order to identify frail patients, possibly before the appearance of clinical symptoms, as well as patients at risk for age-associated diseases. An overview of selected biomarkers will be discussed in this regard, in particular we will focus on biomarkers related to metabolic stress response, inflammation, and cell death (in particular in neurodegeneration), all phenomena connected to inflammaging (chronic, low-grade, age-associated inflammation). In the second part of the review, next-generation markers such as extracellular vesicles and their cargos, epigenetic markers and gut microbiota composition, will be discussed. Since recent progresses in omics techniques have allowed an exponential increase in the production of laboratory data also in the field of biomarkers of age, making it difficult to extract biological meaning from the huge mass of available data, Artificial Intelligence (AI) approaches will be discussed as an increasingly important strategy for extracting knowledge from raw data and providing practitioners with actionable information to treat patients.

Elevated serum FGF21 is an independent predictor for adverse events in hemodialysis patients from two large centers: a prospective cohort study

Introduction: We explored the relationship and the predictive value of serum fibroblast growth factor 21 (FGF21) with all-cause mortality, major adverse cardiovascular events (MACEs) and pneumonia in hemodialysis (HD) patients.Methods: A total of 388 Chinese HD patients from two HD centers were finally enrolled in this prospective cohort study (registration number: ChiCTR 1900028249) between January 2018 and December 2018. Serum FGF21 was detected. Patients were followed up with a median period of 47 months to record the MACEs and pneumonia until death or 31 December 2022.Results: The incidence of all-cause mortality, MACEs and pneumonia in HD patients were 20.6%, 29.6%, and 34.8%, respectively. The optimal cutoffs for FGF21 to predict all-cause mortality, MACEs and pneumonia were 437.57 pg/mL, 216.99 pg/mL and 112.79 pg/mL. Multivariate Cox regression analyses showed that FGF21, as a categorical variable, was an independent predictor for all-cause mortality, MACEs and pneumonia (HR, 3.357, 95% CI, 2.128-5.295, p < 0.001; HR, 1.575, 95% CI, 1.046-2.371, p = 0.029; HR, 1.784; 95% CI, 1.124-2.830; p = 0.014, respectively). The survival nomogram, MACEs-free survival nomogram and pneumonia-free survival nomogram based on FGF21 constructed for individualized assessment of HD patients had a high C-index with 0.841, 0.706 and 0.734.Conclusion: Higher serum FGF21 is an independent predictor of all-cause mortality, MACEs and pneumonia in HD patients.

rhFGF-21 accelerates corneal epithelial wound healing through the attenuation of oxidative stress and inflammatory mediators in diabetic mice

Diabetic keratopathy, commonly associated with a hyperactive inflammatory response, is one of the most common eye complications of diabetes. The peptide hormone fibroblast growth factor-21 (FGF-21) has been demonstrated to have anti-inflammatory and antioxidant properties. However, whether administration of recombinant human (rh) FGF-21 can potentially regulate diabetic keratopathy is still unknown. Therefore, in this work, we investigated the role of rhFGF-21 in the modulation of corneal epithelial wound healing, the inflammation response, and oxidative stress using type 1 diabetic mice and high glucose-treated human corneal epithelial cells. Our experimental results indicated that the application of rhFGF-21 contributed to the enhancement of epithelial wound healing. This treatment also led to advancements in tear production and reduction in corneal edema. Moreover, there was a notable reduction in the levels of proinflammatory cytokines such as TNF-α, IL-6, IL-1β, MCP-1, IFN-γ, MMP-2, and MMP-9 in both diabetic mouse corneal epithelium and human corneal epithelial cells treated with high glucose. Furthermore, we found rhFGF-21 treatment inhibited reactive oxygen species production and increased levels of anti-inflammatory molecules IL-10 and SOD-1, which suggests that FGF-21 has a protective role in diabetic corneal epithelial healing by increasing the antioxidant capacity and reducing the release of inflammatory mediators and matrix metalloproteinases. Therefore, we propose that administration of FGF-21 may represent a potential treatment for diabetic keratopathy.

San Huang Xiao Yan recipe modulates the HMGB1-mediated abnormal inflammatory microenvironment and ameliorates diabetic foot by activating the AMPK/Nrf2 signalling pathway

BACKGROUND

Diabetic foot (DF) is one of the serious complications of diabetes and lacks of therapeutic drugs. Abnormal and chronic inflammation promoting foot infection and wound healing delay are the main pathogenesis of DF. The traditional prescription San Huang Xiao Yan Recipe (SHXY) has been used in the clinical treatment of DF for several decades as approved hospital experience prescription and showed remarkable therapeutic effect, but the mechanisms by which SHXY treats DF are still unclear.

PURPOSE

Objectives of this study were to investigate SHXY anti-inflammatory effect on DF and explore the molecular mechanism for SHXY.

METHODS

We detected the effects of SHXY on DF in C57 mouse and SD rat DF models. Animal blood glucose, weight and wound area were detected every week. Serum inflammatory factors were detected by ELISA. H&E and Masson's trichrome were used to observe tissue pathology. Single-cell sequencing data reanalysis revealed the role of M1 macrophages in DF. Venn analysis showed the co-target genes between DF M1 macrophages and compound-disease network pharmacology. Western blotting was used to explored target protein expression. Meanwhile, RAW264.7 cells were treated with drug-containing serum of SHXY to further unravel the roles of target proteins during high glucose-induced inflammation in vitro. The Nrf2 inhibitor ML385 was used on RAW 264.7 cells to further explore the relationship between Nrf2, AMPK and HMGB1. The main components of SHXY were analysed by HPLC. Finally, the treatment effect of SHXY on DF were detected on rat DF model.

RESULTS

In vivo, SHXY can ameliorate inflammatory, accelerate wound healing and upregulate expression of Nrf2, AMPK and downregulate of HMGB1. Bioinformatic analysis showed that M1 macrophages were the main inflammatory cell population in DF. Moreover, the Nrf2 downstream proteins HO-1 and HMGB1 were potential DF therapeutic targets for SHXY. In vitro, we also found that SHXY increased AMPK and Nrf2 protein levels and downregulated HMGB1 expression in RAW264.7 cells. Inhibiting the expression of Nrf2 impaired the inhibition effect of SHXY on HMGB1. SHXY promoted Nrf2 translocation into the nucleus and increased the phosphorylation of Nrf2. SHXY also inhibited HMGB1 extracelluar release under high glucose. In rat DF models, SHXY also exhibited significant anti-inflammatory effect.

CONCLUSION

The SHXY activated AMPK/Nrf2 pathway to suppress abnormal inflammation on DF via inhibiting HMGB1 expression. These findings provide novel insight into the mechanisms by which SHXY treats DF.

The potential effect of metformin on fibroblast growth factor 21 in type 2 diabetes mellitus (T2DM)

Fibroblast growth factor 21 (FGF21) is a peptide hormone mainly synthesized and released from the liver. FGF21 acts on FGF21 receptors (FGFRs) and β-Klotho, which is a transmembrane co-receptor. In type 2 diabetes mellitus (T2DM), inflammatory disorders stimulate the release of FGF21 to overcome insulin resistance (IR). FGF21 improves insulin sensitivity and glucose homeostasis. Metformin which is used in the management of T2DM may increase FGF21 expression. Accordingly, the objective of this review was to clarify the metformin effect on FGF21 in T2DM. FGF21 level and expression of FGF2Rs are dysregulated in T2DM due to the development of FGF21 resistance. Metformin stimulates the hepatic expression of FGF21/FGF2Rs by different signaling pathways. Besides, metformin improves the expression of β-Klotho which improves FGF21 sensitivity. In conclusion, metformin advances FGF21 signaling and decreases FGF21 resistance in T2DM, and this might be an innovative mechanism for metformin in the enhancement of glucose homeostasis and metabolic disorders in T2DM patients.

Serum Fibroblast Growth Factor-21 Discriminates Between Decompensated Alcohol-Associated Cirrhosis and Severe Alcohol-Associated Hepatitis

INTRODUCTION

We hypothesized that fibroblast growth factor-21 (FGF-21) would be highly expressed in patients with alcohol-associated hepatitis (AH) and could be a novel and biologically relevant predictive biomarker to reliably distinguish severe AH and decompensated alcohol-associated cirrhosis (AC).

METHODS

We identified a discovery cohort of 88 subjects with alcohol-associated liver disease (ALD) of varying disease severity from our ALD repository. Our validation cohort consisted of 37 patients with a biopsy-proven diagnosis of AH, AC, or absence of ALD with Model for End-Stage Liver Disease scores ≥10. Serum from both groups during index hospitalization was assayed for FGF-21 by ELISA. We performed receiver operating characteristic analysis and prediction modeling in both cohorts to discriminate between AH and AC in high Model for End-Stage Liver Disease (≥20) patients.

RESULTS

In both cohorts, FGF-21 concentrations were highest in subjects with moderate to severe AH compared with those having alcohol use disorder or AC (mean: 2,609 pg/mL, P < 0.0001). The discovery cohort area under the curve of FGF-21 between AH and AC was 0.81 (95% confidence interval: 0.65-0.98, P < 0.01). In the validation cohort, FGF-21 levels were higher in severe AH compared with AC (3,052 vs 1,235 pg/mL, P = 0.03), and the area under the curve was 0.76 (95% confidence interval: 0.56-0.96, P < 0.03). A survival analysis showed that patients with FGF-21 serum levels in the second interquartile had the highest survival compared with all other quartiles.

DISCUSSION

FGF-21 performs well as a predictive biomarker to distinguish severe AH from AC and may be helpful in the management and clinical investigation of patients with severe alcohol-associated liver diseases.

The potential therapeutic effect of statins in multiple sclerosis: beneficial or detrimental effects

Multiple sclerosis (MS) is a chronic progressive disabling disease of the central nervous system (CNS) characterized by demyelination and neuronal injury. Dyslipidemia is observed as one of the imperative risk factors involved in MS neuropathology. Also, chronic inflammation in MS predisposes to the progress of dyslipidemia. Therefore, treatment of dyslipidemia in MS by statins may attenuate dyslipidemia-induced MS and avert MS-induced metabolic changes. Therefore, the present review aimed to elucidate the possible effects of statins on the pathogenesis and outcomes of MS. Statins adversely affect the cognitive function in MS by decreasing brain cholesterol CoQ10, which is necessary for the regulation of neuronal mitochondrial function. However, statins could be beneficial in MS by shifting the immune response from pro-inflammatory Th17 to an anti-inflammatory regulatory T cell (Treg). The protective effect of statins against MS is related to anti-inflammatory and immunomodulatory effects with modulation of fibrinogen and growth factors. In conclusion, the effects of statins on MS neuropathology seem to be conflicting, as statins seem to be protective in the acute phase of MS through anti-inflammatory and antioxidant effects. However, statins lead to detrimental effects in the chronic phase of MS by reducing brain cholesterol and inhibiting the remyelination process.

Performance and Metabolic, Inflammatory, and Oxidative Stress-Related Parameters in Early Lactating Dairy Cows with High and Low Hepatic FGF21 Expression

Induction of FGF21 expression in the liver and a significant increase in plasma FGF21 concentration have been demonstrated in cows during early lactation, but knowledge about the function of FGF21 in dairy cows remains limited. In order to improve the understanding of the physiological role of FGF21 in dairy cows, the present study aimed to investigate differences in metabolic pathways between dairy cows with high and low hepatic expression of FGF21 at week 1 of lactation (n = 8/group) by liver transcriptomics, targeted plasma metabolomics, and analysis of inflammatory and oxidative stress-related parameters. Dry matter intake, energy balance, milk yield, and energy-corrected milk yield at days 8−14 postpartum did not differ between cows with high and low hepatic FGF21 expression. However, cows with high FGF21 expression showed an upregulation of genes involved in endoplasmic reticulum stress, inflammation, and nuclear factor E2-related factor 2 (Nrf2)-dependent cytoprotection compared to cows with low FGF21 expression at week 1 postpartum (p < 0.05). Concentrations of important antioxidants (tocopherols, β-carotene, and glutathione) in the liver and plasma, trolox equivalent antioxidant capacity in plasma, concentrations of oxidative stress-related compounds (thiobarbituric acid-reactive substances and protein carbonyls), and levels of most acute phase proteins at week 1 postpartum did not differ between cows with high or low FGF21 expression. Moreover, among a total of >200 metabolites assayed in the plasma, concentrations of only 7 metabolites were different between cows with high or low FGF21 expression (p < 0.05). Overall, the results showed that cows with high and low FGF21 hepatic expression had only moderate differences in metabolism, but FGF21 might be important in the adaptation of dairy cows to stress conditions during early lactation.

Extract of Wheatgrass and Aronia Mixture Ameliorates Atopic Dermatitis-Related Symptoms by Suppressing Inflammatory Response and Oxidative Stress In Vitro and In Vivo

Atopic dermatitis is regulated by the production of pro-inflammatory cytokines and chemokines via the nuclear factor kappa B or mitogen-activated protein kinase signaling pathways, as well as, the release of oxidative stress-related factors via the NF-E2 p45-related factor 2 signaling pathway. Both wheatgrass (Triticum aestivum L., TA) and aronia (Aronia melanocarpa, AR) are known for their anti-inflammatory and antioxidant properties, however, the anti-inflammatory and antioxidant effects of TA and AR (TAAR) mixture extract have not been elucidated in an atopic dermatitis model. In this study, we assessed the inhibitory effects and underlying molecular mechanism of TAAR extract against lipopolysaccharide-induced inflammation and tumor necrosis factor-α/interferon-γ-induced inflammation and oxidative stress in vitro. We also investigated the alleviating effect of TAAR extract on DNCB-induced atopic dermatitis-like skin lesions in mice in vivo. We found that TAAR extract treatment inhibited inflammatory mediators in both RAW 264.7 cells and HaCaT cells, and increased the expression of oxidative stress defense enzymes in HaCaT cells. Furthermore, treatment of the DNCB-induced mouse model with TAAR extract ameliorated the overall symptoms of atopic dermatitis. Therefore, TAAR extract as a novel natural therapeutic agent may be used for the treatment of atopic dermatitis.

The elevation of fibroblast growth factor 21 is associated with generalized periodontitis in patients with treated metabolic syndrome

BACKGROUND

Fibroblast growth factor 21 (FGF21) is closely associated with metabolic syndrome (MetS). An alteration of FGF21 is possibly affected by periodontitis. The present study aimed to investigate the levels of serum FGF21 in MetS patients with generalized periodontitis and its association with periodontal and metabolic parameters.

METHODS

One hundred forty-six MetS patients were recruited from the CORE (Cohort Of patients at a high Risk for Cardiovascular Events) Thailand registry. All participants received general data interviewing, periodontal examination and blood collection for measurement of FGF21 levels and biochemistry parameters. Periodontitis was defined according to the new classification and divided into two groups of localized periodontitis and generalized periodontitis.

RESULTS

FGF21 was significantly higher in generalized periodontitis group when compared with localized periodontitis group (p <  0.05). The significant correlation was observed between FGF21 and variables including number of remaining teeth, mean clinical attachment loss, hypertriglyceridemia and low high-density lipoprotein cholesterol. The elevation of serum FGF21 was associated with presence of generalized periodontitis after adjusting of covariate factors (OR = 27.12, p = 0.012).

CONCLUSIONS

The elevation of serum FGF21 might be a potential biomarker for MetS patients who have risk of generalized periodontitis.

Glucose and lipopolysaccharide differentially regulate fibroblast growth factor 21 in healthy male human volunteers - A prospective cross-over trial

Fibroblast growth factor 21 (FGF21) affects the regulation of metabolism. Additionally, anti-inflammatory properties are attributed to FGF21, and studies in animals and humans show conflicting results. This study aimed to investigate how FGF21 is affected by glucose and lipopolysaccharide (LPS) in humans. Therefore, FGF21 was measured eight times at different time points within 48 h in this prospective cross-over trial after glucose and LPS on two different study days. The study included ten healthy, non-smoking male subjects aged 18-40. Repeated measures analysis of variance and paired t-test as post hoc analysis were applied. The administration of glucose and LPS resulted in a significant difference in regulating FGF21 (p < 0.001). After glucose administration, FGF21 declined sharply at 360 min, with a subsequent steep increase that exceeded baseline levels. LPS induced a drop in FGF21 after 180 min, while the baseline concentrations were not reached. After 180 min and 24 h, a statistically significant difference was demonstrated after adjusting the Bonferroni-Holm method. So, our results support the hypothesis that glucose and LPS differentially affect the human expression of FGF21 over 48 h.

Emerging roles of fibroblast growth factor 21 in critical disease

In spite of the great progress in the management of critical diseases in recent years, its associated prevalence and mortality of multiple organ failure still remain high. As an endocrine hormone, fibroblast growth factor 21 (FGF21) functions to maintain homeostasis in the whole body. Recent studies have proved that FGF21 has promising potential effects in critical diseases. FGF21 has also been found to have a close relationship with the progression of critical diseases and has a great predictive function for organ failure. The level of FGF21 was elevated in both mouse models and human patients with sepsis or other critical illnesses. Moreover, it is a promising biomarker and has certain therapeutic roles in some critical diseases. We focus on the emerging roles of FGF21 and its potential effects in critical diseases including acute lung injury/acute respiratory distress syndrome (ALI/ARDS), acute myocardial injury (AMI), acute kidney injury (AKI), sepsis, and liver failure in this review. FGF21 has high application value and is worth further studying. Focusing on FGF21 may provide a new perspective for the management of the critical diseases.

The Nrf2 in Obesity: A Friend or Foe?

Obesity and its complications have become serious global health concerns recently and increasing work has been carried out to explicate the underlying mechanism of the disease development. The recognized correlations suggest oxidative stress and inflammation in expanding adipose tissue with excessive fat accumulation play important roles in the pathogenesis of obesity, as well as its associated metabolic syndromes. In adipose tissue, obesity-mediated insulin resistance strongly correlates with increased oxidative stress and inflammation. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been described as a key modulator of antioxidant signaling, which regulates the transcription of various genes coding antioxidant enzymes and cytoprotective proteins. Furthermore, an increasing number of studies have demonstrated that Nrf2 is a pivotal target of obesity and its related metabolic disorders. However, its effects are controversial and even contradictory. This review aims to clarify the complicated interplay among Nrf2, oxidative stress, lipid metabolism, insulin signaling and chronic inflammation in obesity. Elucidating the implications of Nrf2 modulation on obesity would provide novel insights for potential therapeutic approaches in obesity and its comorbidities.

Bibliometric analysis of fibroblast growth factor 21 research over the period 2000 to 2021

Background: Fibroblast growth factor 21 (FGF-21) is an evolutionarily conserved protein that plays multiple roles in metabolic regulation. Over the past two decades, numerous studies have deepened our understanding of its various functions and its pharmacological value. Nevertheless, most clinical trials have not achieved the desired results, which raises issues regarding its clinical value. In this bibliometric analysis, we evaluated the state of FGF-21 research over the last 20 years and identified important topics, achievements, and potential future directions.

Methods: Publications related to FGF-21 were collected from the Web of Science Core Collection-Science Citation Index Expanded. HistCite, VOSviewer, and CiteSpace were used for bibliometric analysis and visualization, including the analysis of annual publications, leading countries, active institutions and authors, core journals, co-cited references, and keywords.

Results: Altogether, 2,490 publications related to FGF-21 were obtained. A total of 12,872 authors from 2,628 institutions in 77 countries or regions reported studies on FGF-21. The United States of America was the most influential country in FGF-21 research. Alexei Kharitonenkov, Steven A. Kliewer, and David J. Mangelsdorf were the most influential scholars, and endocrinology journals had a core status in the field. The physiological roles, clinical translation, and FGF-21-based drug development were the main topics of research, and future studies may concentrate on the central effects of FGF-21, FGF-21-based drug development, and the effects of FGF-21 on non-metabolic diseases.

Conclusion: The peripheral metabolic effects of FGF-21, FGF-21-based drug development, and translational research on metabolic diseases are the three major topics in FGF-21 research, whereas the central metabolic effects of FGF-21 and the effects of FGF-21 on metabolic diseases are the emerging trends and may become the following hot topics in FGF-21 research.

Wogonin, a Compound in Scutellaria baicalensis, Activates ATF4–FGF21 Signaling in Mouse Hepatocyte AML12 Cells

Fibroblast growth factor 21 (FGF21), which is mainly synthesized and secreted by the liver, plays a crucial role in systemic glucose and lipid metabolism, ameliorating metabolic diseases. In this study, we screened the WAKANYAKU library derived from medicinal herbs to identify compounds that can activate Fgf21 expression in mouse hepatocyte AML12 cells. We identified Scutellaria baicalensis root extract and one of its components, wogonin, as an activator of Fgf21 expression. Wogonin also enhanced the expression of activating transcription factor 4 (ATF4) by a mechanism other than ER stress. Knockdown of ATF4 by siRNA suppressed wogonin-induced Fgf21 expression, highlighting its essential role in wogonin’s mode of action. Thus, our results indicate that wogonin would be a strong candidate for a therapeutic to improve metabolic diseases by enhancing hepatic FGF21 production.

Hepatocyte-Secreted Autotaxin Exacerbates Nonalcoholic Fatty Liver Disease Through Autocrine Inhibition of the PPARα/FGF21 Axis

BACKGROUND & AIMS

The prevalence of nonalcoholic fatty liver disease (NAFLD) has reached epidemic proportions globally as a result of the rapid increase in obesity. However, there is no Food and Drug Administration-approved pharmacotherapy available for NAFLD. This study investigated the role of autotaxin, a secreted enzyme that hydrolyzes lysophosphatidylcholine to produce lysophosphatidic acid (LPA), in the pathogenesis of NAFLD and to explore whether genetic or pharmacologic interventions targeting autotaxin ameliorate NAFLD.

METHODS

The clinical association of autotaxin with the severity of NAFLD was analyzed in 125 liver biopsy-proven NAFLD patients. C57BL/6N mice or fibroblast growth factor 21 (FGF21)-null mice were fed a high-fat diet or a choline-deficient diet to investigate the role of the autotaxin-FGF21 axis in NAFLD development by hepatic knockdown and antibody neutralization. Huh7 cells were used to investigate the autocrine effects of autotaxin.

RESULTS

Serum autotaxin levels were associated positively with histologic scores and NAFLD severity. Hepatocytes, but not adipocytes, were the major contributor to increased circulating autotaxin in both patients and mouse models with NAFLD. In mice, knocking-down hepatic autotaxin or treatment with a neutralizing antibody against autotaxin significantly reduced high-fat diet-induced NAFLD and high fat- and choline-deficient diet-induced nonalcoholic steatohepatitis and fibrosis, accompanied by a marked increase of serum FGF21. Mechanistically, autotaxin inhibited the transcriptional activity of peroxisome proliferator-activated receptor α through LPA-induced activation of extracellular signal-regulated kinas, thereby leading to suppression of hepatic FGF21 production. The therapeutic benefit of anti-autotaxin neutralizing antibody against NAFLD was abrogated in FGF21-null mice.

CONCLUSIONS

Liver-secreted autotaxin acts in an autocrine manner to exacerbate NAFLD through LPA-induced suppression of the peroxisome proliferator-activated receptor α-FGF21 axis and is a promising therapeutic target for NAFLD.

The Hypoglycemic Effect of JinQi Jiangtang Tablets Is Partially Dependent on the Palmatine-Induced Activation of the Fibroblast Growth Factor Receptor 1 Signaling Pathway

JinQi Jiangtang tablet (JQJTT) is a Chinese patent medicine that has been shown to be beneficial for patients with diabetes both preclinically and clinically; however, the molecular mechanism underlying the effects of JQJTT remains unclear. In this study, surface plasmon resonance fishing was employed to identify JQJTT constituent molecules that can specifically bind to fibroblast growth factor receptor 1 (FGFR1), leading to the retrieval of palmatine (PAL), a key active ingredient of JQJTT. In vivo and in vitro experiments demonstrated that PAL can significantly stimulate FGFR1 phosphorylation and upregulate glucose transporter type 1 (GLUT-1) expression, thereby facilitating glucose uptake in insulin resistance (IR) HepG2 cells as well as alleviating hyperglycemia in diabetic mice. Our results revealed that PAL functions as an FGFR1 activator and that the hypoglycemic effect of JQJTT is partially dependent on the PAL-induced activation of the FGFR1 pathway. In addition, this study contributed to the understanding the pharmacodynamic basis and mechanism of action of JQJTT and provided a novel concept for future research on PAL.

SNAI1 is upregulated during muscle regeneration and represses FGF21 and ATF3 expression by directly binding their promoters

During skeletal myogenesis, the zinc-finger transcription factors SNAI1 and SNAI2, are expressed in proliferating myoblasts and regulate the transition to terminally differentiated myotubes while repressing pro-differentiation genes. Here, we demonstrate that SNAI1 is upregulated in vivo during the early phase of muscle regeneration induced by bupivacaine injury. Using shRNA-mediated gene silencing in C2C12 myoblasts and whole-transcriptome microarray analysis, we identified a collection of genes belonging to the endoplasmic reticulum (ER) stress pathway whose expression, induced by myogenic differentiation, was upregulated in absence of SNAI1. Among these, key ER stress genes, such as Atf3, Ddit3/Chop, Hspa5/Bip, and Fgf21, a myokine involved in muscle differentiation, were strongly upregulated. Furthermore, by promoter mutant analysis and Chromatin immune precipitation assay, we demonstrated that SNAI1 represses Fgf21 and Atf3 in proliferating myoblasts by directly binding to multiple E boxes in their respective promoter regions. Together, these data describe a new regulatory mechanism of myogenic differentiation involving the direct repressive action of SNAI1 on ER stress and Fgf21 expression, ultimately contributing to maintaining the proliferative and undifferentiated state of myoblasts.

Organokines in Rheumatoid Arthritis: A Critical Review

Rheumatoid arthritis (RA) is a systemic autoimmune disease that primarily affects the joints. Organokines can produce beneficial or harmful effects in this condition. Among RA patients, organokines have been associated with increased inflammation and cartilage degradation due to augmented cytokines and metalloproteinases production, respectively. This study aimed to perform a review to investigate the role of adipokines, osteokines, myokines, and hepatokines on RA progression. PubMed, Embase, Google Scholar, and Cochrane were searched, and 18 studies were selected, comprising more than 17,000 RA patients. Changes in the pattern of organokines secretion were identified, and these could directly or indirectly contribute to aggravating RA, promoting articular alterations, and predicting the disease activity. In addition, organokines have been implicated in higher radiographic damage, immune dysregulation, and angiogenesis. These can also act as RA potent regulators of cells proliferation, differentiation, and apoptosis, controlling osteoclasts, chondrocytes, and fibroblasts as well as immune cells chemotaxis to RA sites. Although much is already known, much more is still unknown, principally about the roles of organokines in the occurrence of RA extra-articular manifestations.

Dietary Klebsormidium sp. Supplementation Improves Growth Performance, Antioxidant and Anti-Inflammatory Status, Metabolism, and Mid-Intestine Morphology of Litopenaeus Vannamei

Filamentous microalga Klebsormidium sp. has huge potential to become a natural and healthy additive in aquatic feed since it contains various bioactive nutrients, such as linoleic acid (LA), carotenoids, and chlorophylls. Therefore, an eight-week feeding experiment was performed to evaluate the effects of dietary Klebsormidium sp. on the growth performance, antioxidant and anti-inflammatory status, metabolism, and mid-intestine morphology of Litopenaeus vannamei. Two isonitrogenous and isolipid diets supplemented with and without 5% Klebsormidium sp. were prepared. Results showed that L. vannamei fed with Klebsormidium sp. had better growth performance and feed utilization by optimizing mid-intestine morphology and improving the carbohydrate metabolism. In addition, Klebsormidium sp. also enhanced the antioxidant capacity of L. vannamei by downregulating antioxidant parameters (hepatopancreas T-SOD, hepatopancreas GSH-PX, hemolymph T-SOD, hemolymph MDA) and RNA expression levels of antioxidant genes (gsh-px and cat). Furthermore, the supplementations of dietary Klebsormidium sp. significantly improved hepatopancreas health by downregulating RNA expression levels of pro-inflammatory related genes (relish and rho). Therefore, a dose of 5% Klebsormidium sp. is recommended for the daily diet of L. vannamei to improve the growth performance, antioxidant and anti-inflammatory status, metabolism, and mid-intestine morphology of shrimp.

CRISPR-Cas9-based genome-wide screening identified novel targets for treating sorafenib-resistant hepatocellular carcinoma: a cross-talk between FGF21 and the NRF2 pathway

The treatment of hepatocellular carcinoma (HCC) has been dominated by multikinase inhibitors for more than a decade. However, drug resistance can severely restrict the efficacy of these drugs. Using CRISPR/CAS9 genome library screening, we evaluated Kelch-like ECH-associated protein 1 (KEAP1) as a key regulator of sorafenib's susceptibility in HCC. We also investigated whether KEAP1's knockdown can stabilize nuclear factor (erythroid-derived 2)-like 2 (NRF2) protein levels that led to sorafenib's resistance, including an NRF2 inhibitor that can synergize with sorafenib to abolish HCC's growth in vitro and in vivo. Furthermore, we clarified that fibroblast growth factor 21 (FGF21) is an important downstream regulator of NRF2 in HCC. Intriguingly, we observed that FGF21 bound to NRF2 through the C-terminus of FGF21, thereby stabilizing NRF2 by reducing its ubiquitination and generating a positive feedback loop in sorafenib-resistant HCC. These findings, therefore, propose that targeting FGF21 is a promising strategy to combat HCC sorafenib's resistance.

Brite Adipocyte FGF21 Attenuates Cardiac Ischemia/Reperfusion Injury in Rat Hearts by Modulating NRF2

Although the optimal therapy for myocardial infarction includes reperfusion to restore blood flow to the ischemic area, myocardial injury after ischemia/reperfusion usually leads to an inflammatory response, oxidative stress, and cardiomyocyte apoptosis. In this study, rat adipose-derived stem cells were differentiated into low-thermogenic beige adipocytes (LBACs) and high-thermogenic beige adipocytes (HBACs) to study the different cardioprotective effects of heterogeneous expression of brown adipocytes. We found that antioxidant and antiapoptotic factors in H9c2 cardiomyocytes were upregulated by high levels of secreted FGF21 in HBAC conditioned medium (HBAC-CM), whereas FGF21 in HBAC-CM did not affect antioxidative or antiapoptotic cell death in H9c2 cardiomyocytes with Nrf2 knockdown. These results show that NRF2 mediates antioxidative and antiapoptotic effects through the HBAC-secreted factor FGF21. Consistent with this finding, the expression of antioxidant and antiapoptotic genes was upregulated by highly secreted FGF21 after HBAC-CM treatment compared to LBAC-CM treatment in H9c2 cardiomyocytes via NRF2 activation. Furthermore, HBAC-CM significantly attenuated ischemic rat heart tissue injury via NRF2 activation. Based on these findings, we propose that HBAC-CM exerts beneficial effects in rat cardiac ischemia/reperfusion injury by modulating NRF2 and has potential as a promising therapeutic agent for myocardial infarction.

Early Investigational and Experimental Therapeutics for the Treatment of Hypertriglyceridemia

Hypertriglyceridemia has been identified as a risk factor for cardiovascular disease and acute pancreatitis. To date, there are only few drug classes targeting triglyceride levels such as fibrates and ω-3 fatty acids. These agents are at times insufficient to address very high triglycerides and the residual cardiovascular risk in patients with mixed dyslipidemia. To address this unmet clinical need, novel triglyceride-lowering agents have been in different phases of early clinical development. In this review, the latest and experimental therapies for the management of hypertriglyceridemia are presented. Specifically, ongoing trials evaluating novel apolipoprotein C-III inhibitors, ω-3 fatty acids, as well as fibroblast growth 21 analogues are discussed.

Nrf2/ARE axis signalling in hepatocyte cellular death

The Nrf2-ARE transcriptional pathway plays an important role amongst cellular defence systems regulating and ensuring adequacy of redox responses and oxidant signalling factors. Hepatocyte cellular death and injury is a prominent feature underlying liver pathologies. Diverse endogenous molecules and targets contribute to the outcome of cell survival and the consequent mode of cell death. Several research efforts focused on the confirmation of Nrf2 presence in cell death and its vital necessity against cell compromise, however, little they comprehend of such participation. Hepatocyte cell death modes discussed in this review including autophagy, apoptosis, necrosis, ferroptosis, pyroptosis, fibrosis and others, vary in response of the stimuli burdened. The current review presents a handful of highlights and crosstalk involved in the communication of Nrf2 signalling network with the "up to date" reported hepatocyte cell death modes and their underling mechanisms, and addressing key cellular networks of hepatocyte fate, through a perspective of Nrf2 as a critical transcriptional factor. Collectively, labelling the cross-transduction of Nrf2-ARE axis with key cell execution pathways could provide insights to therapeutic interventions and better research outcomes.

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.

Non-Alcoholic Fatty Liver Disease in HIV/HBV Patients - a Metabolic Imbalance Aggravated by Antiretroviral Therapy and Perpetuated by the Hepatokine/Adipokine Axis Breakdown

Non-alcoholic fatty liver disease (NAFLD) is strongly associated with the metabolic syndrome and is one of the most prevalent comorbidities in HIV and HBV infected patients. HIV plays an early and direct role in the development of metabolic syndrome by disrupting the mechanism of adipogenesis and synthesis of adipokines. Adipokines, molecules that regulate the lipid metabolism, also contribute to the progression of NAFLD either directly or via hepatic organokines (hepatokines). Most hepatokines play a direct role in lipid homeostasis and liver inflammation but their role in the evolution of NAFLD is not well defined. The role of HBV in the pathogenesis of NAFLD is controversial. HBV has been previously associated with a decreased level of triglycerides and with a protective role against the development of steatosis and metabolic syndrome. At the same time HBV displays a high fibrogenetic and oncogenetic potential. In the HIV/HBV co-infection, the metabolic changes are initiated by mitochondrial dysfunction as well as by the fatty overload of the liver, two interconnected mechanisms. The evolution of NAFLD is further perpetuated by the inflammatory response to these viral agents and by the variable toxicity of the antiretroviral therapy. The current article discusses the pathogenic changes and the contribution of the hepatokine/adipokine axis in the development of NAFLD as well as the implications of HIV and HBV infection in the breakdown of the hepatokine/adipokine axis and NAFLD progression.

Adipokines, Hepatokines and Myokines: Focus on Their Role and Molecular Mechanisms in Adipose Tissue Inflammation

Chronic low-grade inflammation in adipose tissue (AT) is a hallmark of obesity and contributes to various metabolic disorders, such as type 2 diabetes and cardiovascular diseases. Inflammation in ATs is characterized by macrophage infiltration and the activation of inflammatory pathways mediated by NF-κB, JNK, and NLRP3 inflammasomes. Adipokines, hepatokines and myokines - proteins secreted from AT, the liver and skeletal muscle play regulatory roles in AT inflammation via endocrine, paracrine, and autocrine pathways. For example, obesity is associated with elevated levels of pro-inflammatory adipokines (e.g., leptin, resistin, chemerin, progranulin, RBP4, WISP1, FABP4, PAI-1, Follistatin-like1, MCP-1, SPARC, SPARCL1, and SAA) and reduced levels of anti-inflammatory adipokines such as adiponectin, omentin, ZAG, SFRP5, CTRP3, vaspin, and IL-10. Moreover, some hepatokines (Fetuin A, DPP4, FGF21, GDF15, and MANF) and myokines (irisin, IL-6, and DEL-1) also play pro- or anti-inflammatory roles in AT inflammation. This review aims to provide an updated understanding of these organokines and their role in AT inflammation and related metabolic abnormalities. It serves to highlight the molecular mechanisms underlying the effects of these organokines and their clinical significance. Insights into the roles and mechanisms of these organokines could provide novel and potential therapeutic targets for obesity-induced inflammation.

(-)-Methyl-Oleocanthal, a New Oleocanthal Metabolite Reduces LPS-Induced Inflammatory and Oxidative Response: Molecular Signaling Pathways and Histones Epigenetic Modulation

The antioxidant and anti-inflammatory responses of (−)-methyl-oleocanthal (met-OLE), a new metabolite of the extra virgin olive oil (EVOO) phenolic oleocanthal (OLE), were explored in lipopolysaccharide (LPS)-induced murine peritoneal macrophages. Possible signaling pathways and epigenetic modulation of histones were studied. Met-OLE inhibited LPS-induced intracellular reactive oxygen species (ROS) and nitrite (NO) production and decreased the overexpression of the pro-inflammatory enzymes COX-2, mPGES-1 and iNOS in murine macrophages. In addition, met-OLE was able to significantly decrease the activation of p38, JNK, and ERK mitogen-activated protein kinases (MAPKs) and blocked canonical and non-canonical inflammasome signaling pathways. On the contrary, met-OLE upregulated haem oxigenase 1 (HO-1) and nuclear factor (erythroid-derived 2)-like 2 (Nrf-2) expression in treated cells. Finally, met-OLE pretreated spleen cells counteracted LPS induction, preventing H3K18 acetylation or H3K9 and H3K27 demethylation. Overall, these results provide novel mechanistic insights into the beneficial effects of met-OLE regarding the regulation of the immune–inflammatory response through epigenetic changes in histone markers. This revealing evidence suggests that the methylated metabolite of OLE may contribute significantly to the beneficial effects that are associated with the secoiridoid-related compound and the usual consumption of EVOO.

Dimethyl itaconate attenuates palmitate-induced insulin resistance in skeletal muscle cells through the AMPK/FGF21/PPARδ-mediated suppression of inflammation

AIM

Itaconate (ITA), a derivative of the tricarboxylic acid cycle, has been documented to have a direct antimicrobial effect by inhibiting isocitrate lyase and suppressing proinflammatory cytokines in LPS-treated macrophages. However, the effects of dimethyl ITA (DITA), a membrane-permeable derivative of ITA, on insulin signaling and inflammation in skeletal muscle in an obese state remain to be elucidated. Thus, this study was designed to investigate the effects of DITA on the impairment of insulin signaling and inflammation in palmitate-treated C2C12 myocytes.

MATERIALS AND METHODS

Western blotting was used to determine the expression of insulin signaling associated genes, inflammatory markers, fibroblast growth factor 21 (FGF21), and PPARδ expression, as well as AMPK phosphorylation in mouse skeletal muscle cells. Secreted proinflammatory cytokine levels were detected by enzyme-linked immunosorbent assay. Insulin signaling was assessed by glucose uptake assay.

KEY FINDINGS

Treating C2C12 myocytes with DITA attenuated palmitate-induced aggravation of insulin signaling markers, such as insulin receptor substrate-1 (IRS-1) and Akt phosphorylation and inflammatory markers, such as NFκB and IκB phosphorylation. AMPK phosphorylation, as well as PPARδ and myokine FGF21 expression, were enhanced in C2C12 myocytes by DITA treatment. siRNA-mediated suppression of AMPK or FGF21 expression abolished the effects of DITA on insulin resistance and inflammation in palmitate-treated C2C12 myocytes.

SIGNIFICANCE

In sum, DITA suppresses inflammation through the AMPK/FGF21/PPARδ signaling, thereby alleviating insulin resistance in palmitate-treated C2C12 myocytes. The current study appears to be an essential basis for performing animal experiments to develop insulin resistance therapeutics.

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.

Lower melanoma pulmonary metastatic burden in obese mice: role of FGF-21

Obesity is a risk factor for malignant melanoma. The lungs are main target organs for metastization and their immune response is a key modulator of this mechanism. The concept that the metastatic potential of some types of cancer is reduced or inhibited by obesity, known as the obesity paradox, drives major concerns on the prognosis of metastasized patients. The aim of this study was to investigate how high-fat diet (HFD)-induced obesity affects melanoma metastization. C57Bl6/J mice were fed with HFD or standard diet for 180 days and inoculated intravenously with B16F10 melanoma cells. Upon 21 days of inoculation, lung tissue of overweight and lean mice was assessed for histology and immunohistochemistry assays. Adipokine antibody arrays were performed in mice serum. In vitro RAW 264.7 macrophage cultures were established and incubated with FGF-21 and/or lipopolysaccharide (LPS). Conditioned media was added to B16F10 cells for viability quantification. HFD-fed mice presented a reduced number of metastases with lower proliferative rates. The high content of inflammatory foci observed in noninoculated obese mice was significantly decreased upon B16F10 inoculation, concurrent with a slight fibrosis reduction. Plasma levels of fibroblast growth factor-21 (FGF-21), an endocrine regulator, were elevated in noninoculated HFD mice and the expression of FGF receptor 1 (FGFR-1) was significantly upregulated after inoculation. FGF-21 reduced melanoma viability in LPS-stimulated macrophages. Altogether, these findings suggest that higher amounts of FGF-21 are able to counterbalance the proinflammatory effects associated with obesity, protecting the lungs from melanoma metastization.

Fibroblast Growth Factor 21 Protects Against Atrial Remodeling via Reducing Oxidative Stress

Aim: The structural and electrical changes in the atrium, also known as atrial remodeling, are the main characteristics of atrial fibrillation (AF). Fibroblast growth factor 21 (Fgf21) is an important endocrine factor, which has been shown to play an important role in cardiovascular diseases. However, the effects of Fgf21 on atrial remodeling have not been addressed yet. The purpose of the present study is to evaluate the effects of Fgf21 on atrial remodeling.

Methods and Results: Adult mice were treated with Ang II, and randomly administrated with or without Fgf21 for 2 weeks. The susceptibility to AF was assessed by electrical stimulation and optical mapping techniques. Here, we found that Fgf21 administration attenuated the inducibility of atrial fibrillation/atrial tachycardia (AF/AT), improved epicardial conduction velocity in the mice atria. Mechanistically, Fgf21 protected against atrial fibrosis and reduced oxidative stress of the atria. Consistently, in vitro study also demonstrated that Fgf21 blocked the upregulation of collagen by Tgf-β in fibroblasts and attenuated tachypacing-induced oxidative stress including reactive oxygen species (ROS), Tgf-β, and ox-CaMKII in atrial myocytes. We further found that Fgf21 attenuated oxidative stress by inducing antioxidant genes, such as SOD2 and UCP3. Fgf21 also improved tachypacing-induced myofibril degradation, downregulation of L-type calcium channel, and upregulation of p-RyR2, which implicated protective effects of Fgf21 on structural and electrical remodeling in the atria. Moreover, Nrf2 was identified as a downstream of Fgf21 and partly mediated Fgf21-induced antioxidant gene expression in atrial myocytes.

Conclusion: Fgf21 administration effectively suppressed atrial remodeling by reducing oxidative stress, which provides a novel therapeutic insight for AF.

Identification of Fibroblast Activation Protein as an Osteogenic Suppressor and Anti-osteoporosis Drug Target

Osteogenic suppressors such as Sclerostin not only regulate skeletal development and regeneration but also serve as anti-osteoporosis drug targets. However, very few druggable suppressors have been identified due to limited understanding of the molecular mechanisms governing osteogenesis. Here, we show that fibroblast activation protein (Fap), a serine protease inhibited by the bone growth factor Osteolectin, is an osteogenic suppressor. Genetic deletion of Fap significantly ameliorates limb trabecular bone loss during aging. Pharmacological inhibition of Fap significantly promotes bone formation and inhibits bone resorption in wild-type mice by differentially regulating canonical Wnt and nuclear factor κB (NF-κB) pathways. Pharmacological inhibition of Fap promotes osteoblast differentiation, inhibits osteoclast differentiation, and significantly attenuates osteoporosis in ovariectomized mice. Epistasis analyses in zebrafish show that Osteolectin functions as an endogenous inhibitor of Fap to promote vertebrae mineralization. Taken together, we identify Fap as an important osteogenic suppressor and a potential drug target to treat osteoporosis.

Fibroblast growth factor 21 in dairy cows: current knowledge and potential relevance

Fibroblast growth factor 21 (FGF21) has been identified as an important regulator of carbohydrate and lipid metabolism, which plays an important role for metabolic regulation, particularly under conditions of energy deprivation or stress conditions. Dairy cows are subjected to a negative energy balance and various kinds of stress particularly during the periparturient phase and during early lactation. It has been shown that the plasma concentration of FGF21 in dairy cows is dramatically increased at parturition and remains high during the first weeks of lactation. This finding suggests that FGF21 might exert similar functions in dairy cows than in other species, such as mice or humans. However, the role of FGF21 in dairy cows has been less investigated so far. Following a brief summary of the previous findings about the function of FGF21 in humans and mice, the present review aims to present the current state of knowledge about the role of FGF21 in dairy cows. The first part of the review deals with the tissue localization of FGF21 and with conditions leading to an upregulation of FGF21 expression in the liver of dairy cows. In the second part, the influence of nutrition on FGF21 expression and the role of FGF21 for metabolic diseases in dairy cows is addressed. In the third part, findings of exogenous FGF21 application on metabolism in dairy cows are reported. Finally, the potential relevance of FGF21 in dairy cows is discussed. It is concluded that FGF21 might be of great importance for metabolic adaptation to negative energy balance and stress conditions in dairy cows. However, further studies are needed for a better understanding of the functions of FGF21 in dairy cows.

Macrophage Responses to Environmental Stimuli During Homeostasis and Disease

Work over the last 40 years has described macrophages as a heterogeneous population that serve as the frontline surveyors of tissue immunity. As a class, macrophages are found in almost every tissue in the body and as distinct populations within discrete microenvironments in any given tissue. During homeostasis, macrophages protect these tissues by clearing invading foreign bodies and/or mounting immune responses. In addition to varying identities regulated by transcriptional programs shaped by their respective environments, macrophage metabolism serves as an additional regulator to temper responses to extracellular stimuli. The area of research known as "immunometabolism" has been established within the last decade, owing to an increase in studies focusing on the crosstalk between altered metabolism and the regulation of cellular immune processes. From this research, macrophages have emerged as a prime focus of immunometabolic studies, although macrophage metabolism and their immune responses have been studied for centuries. During disease, the metabolic profile of the tissue and/or systemic regulators, such as endocrine factors, become increasingly dysregulated. Owing to these changes, macrophage responses can become skewed to promote further pathophysiologic changes. For instance, during diabetes, obesity, and atherosclerosis, macrophages favor a proinflammatory phenotype; whereas in the tumor microenvironment, macrophages elicit an anti-inflammatory response to enhance tumor growth. Herein we have described how macrophages respond to extracellular cues including inflammatory stimuli, nutrient availability, and endocrine factors that occur during and further promote disease progression.

(-)-Loliolide Isolated from Sargassum horneri Suppressed Oxidative Stress and Inflammation by Activating Nrf2/HO-1 Signaling in IFN-γ/TNF-α-Stimulated HaCaT Keratinocytes

The present study evaluated the effects of (-)-loliolide isolated from Sargassum horneri (S. horneri) against oxidative stress and inflammation, and its biological mechanism in interferon (IFN)-γ/tumor necrosis factor (TNF)-α-stimulated HaCaT keratinocytes. The results showed that (-)-loliolide improved the cell viability by reducing the production of intracellular reactive oxygen species (ROS) in IFN-γ/TNF-α-stimulated HaCaT keratinocytes. In addition, (-)-loliolide effectively decreased the expression of inflammatory cytokines (interleukin (IL)-4 IL-6, IL-13, IFN-γ and TNF-α) and chemokines (CCL11 (Eotaxin), macrophage-derived chemokine (MDC), regulated on activation, normal T cell expressed and secreted (RANTES), and thymus and activation-regulated chemokine (TARC)), by downregulating the expression of epidermal-derived initial cytokines (IL-25, IL-33 and thymic stromal lymphopoietin (TSLP)). Furthermore, (-)-loliolide suppressed the activation of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling, whereas it activated nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling. Interestingly, the cytoprotective effects of (-)-loliolide against IFN-γ/TNF-α stimulation were significantly blocked upon inhibition of HO-1. Taken together, these results suggest that (-)-loliolide effectively suppressed the oxidative stress and inflammation by activating the Nrf2/HO-1 signaling in IFN-γ/TNF-α-stimulated HaCaT keratinocytes.

FGF21 attenuates hypoxia‑induced dysfunction and inflammation in HPAECs via the microRNA‑27b‑mediated PPARγ pathway

Pulmonary arterial hypertension (PAH), is a chronic and progressive disorder characterized by pulmonary vascular remodeling, including endothelial cell dysfunction and inflammation. MicroRNAs (miRNAs or miRs) play an important role in the development of PAH. In addition, fibroblast growth factor 21 (FGF21) has been found to have marked anti-dysfunction and anti-inflammatory properties. Therefore, the present study aimed to investigate the latent effects of FGF21 against PAH through the miR-27b/peroxisome proliferator-activated receptor γ (PPARγ) axis. Human pulmonary arterial endothelial cells (HPAECs) subjected to hypoxia were used as PAH models. The results revealed that PPARγ expression was downregulated and miR-27b expression was upregulated in the HPAECs exposed to hypoxia. Luciferase assay suggested that PPARγ was a target gene of miR-27b. Furthermore, miR-27b inhibited the expression of the PPARγ gene, thereby aggravating hypoxia-induced HPAEC dysfunction. Moreover, miR-27b activated the nuclear factor-κB signaling pathway and the expression of inflammatory factors [interleukin (IL)-1β, IL-6 and tumor necrosis factor-α] by targeting PPARγ. In addition, the expression of miR-27b decreased following treatment of the hypoxia-exposed HPAECs with FGF21. Furthermore, FGF21 alleviated hypoxia-induced HPAEC dysfunction and inflammation by inhibiting miR-27b expression and thereby promoting PPARγ expression. On the whole, the findings of the present study suggest that FGF21 may serve as a therapeutic target for managing PAH through the miR-27b-mediated PPARγ pathway.

Effects of interleukin-1 antagonism and corticosteroids on fibroblast growth factor-21 in patients with metabolic syndrome

Fibroblast growth factor-21 (FGF21) is elevated in patients with the metabolic syndrome. Although the exact underlying mechanisms remain ill-defined, chronic low-grade inflammation with increased Interleukin-(IL)-1β expression may be responsible. The aim of this study was to investigate effects of two different anti-inflammatory treatments (IL-1 antagonism or high-dose corticosteroids) on FGF21 in patients with the metabolic syndrome. This is a secondary analysis of two interventional studies in patients with obesity and features of the metabolic syndrome. Trial A was an interventional trial (n = 73) investigating short-term effects of the IL-1 antagonist anakinra and of dexamethasone. Trial B was a randomized, placebo-controlled, double-blinded trial (n = 67) investigating longer-term effects of IL-1 antagonism. In total, 140 patients were included in both trials. Median age was 55 years (IQR 44-66), 26% were female and median BMI was 37 kg/m² (IQR 34-39). Almost half of the patients were diabetic (45%) and had increased c-reactive protein levels of 3.4 mg/L. FGF21 levels correlated with fasting glucose levels, HOMA-index, C-peptide levels, HbA1c and BMI. Short-term treatment with anakinra led to a reduction of FGF21 levels by - 200 pg/mL (95%CI - 334 to - 66; p = 0.004). No effect was detectable after longer-term treatment (between-group difference: - 8.8 pg/mL (95%CI - 130.9 to 113.3; p = 0.89). Acute treatment with dexamethasone was associated with reductions of FGF21 by -175 pg/mL (95%CI - 236 to - 113; p < 0.001). Anti-inflammatory treatment with both, IL-1 antagonism and corticosteroids reduced FGF21 levels at short-term in individuals with the metabolic syndrome.Trial registration: ClinicalTrials.gov Identifiers NCT02672592 and NCT00757276.

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

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

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MR suppresses age-associated cognitive impairment.

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MR improves synapse ultrastructure and mitochondrial biogenesis in the hippocampus.

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FGF21 is required for the beneficial effects of MR.

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FGF21 activates Nrf2 signaling and alleviates neuroinflammation and oxidative stress.