Ultrasound‑targeted microbubble destruction technology delivering β‑klotho to the heart enhances FGF21 sensitivity and attenuates heart remodeling post‑myocardial infarction

Fibroblast growth factor (FGF)21 is a peptide hormone that improves mitochondrial function and energy metabolism, and the deficiency of its co‑receptor β‑klotho (KLB) causes decreased FGF21 sensitivity. The present study examined whether the cardiac delivery of plasmids containing the KLB gene via ultrasound‑targeted microbubble destruction (UTMD) enhances the efficacy of FGF21 against heart failure post‑acute myocardial infarction (AMI). For this purpose, the levels of FGF21 in patients and rats with heart dysfunction post‑infarction were determined using ELISA. Sprague‑Dawley rats received the 3X UTMD‑mediated delivery of KLB@cationic microbubbles (KLB@CMBs) 1 week following the induction of AMI. Echocardiography, histopathology and biochemical analysis were performed at 4 weeks following the induction of AMI. The results revealed that patients with heart failure post‑infarction had higher serum FGF21 levels than the healthy controls. However, the downstream signal, KLB, but not α‑klotho, was reduced in the heart tissues of rats with AMI. As was expected, treatment with FGF21 did not substantially attenuate heart remodeling post‑infarction. It was found that decreased receptors KLB in the heart may result in the insensitivity to FGF21 treatment. In vivo, the UTMD technology‑mediated delivery of KLB@CMBs to the heart significantly enhanced the effects of FGF21 administration on cardiac remodeling and mitochondrial dysfunction in the rats following infarction. The delivery of KLB to the heart by UTMD and the administration of FGF21 attenuated mitochondrial impairment and oxidative stress by activating nuclear factor erythroid 2‑related factor 2 signals. On the whole, the present study demonstrates that the cardiac delivery of KLB significantly optimizes the cardioprotective effects of FGF21 therapy on adverse heart remodeling. UTMD appears a promising interdisciplinary approach with which to improve heart failure post‑myocardial infarction.

A strategy for oral delivery of FGF21 for mitigating inflammation and multi-organ damage in sepsis

Fibroblast growth factor 21 (FGF21) shows great therapeutic potential in metabolic, neurodegenerative and inflammatory diseases. However, current FGF21 administration predominantly relies on injection rather than oral ingestion due to its limited stability and activity post-gastrointestinal transit, thereby hindering its clinical utility. Milk-derived exosomes (mEx) have emerged as a promising vehicle for oral drug delivery due to their ability to maintain structural integrity in the gastrointestinal milieu. To address the challenge associated with oral delivery of FGF21, we encapsulated FGF21 within mEx (mEx@FGF21) to protect its activity post-oral administration. Additionally, we modified the surface of mEx@FGF21 by introducing transferrin (TF) to enhance intestinal absorption and transport, designated TF-mEx@FGF21. In vitro results demonstrated that the surface modification of TF promoted FGF21 internalization by intestinal epithelial cells. Orally administered TF-mEx@FGF21 showed promising therapeutic effects in septic mice. This study represents a practicable strategy for advancing the clinical application of oral FGF21 delivery.

LLF580, an FGF21 Analog, Reduces Triglycerides and Hepatic Fat in Obese Adults With Modest Hypertriglyceridemia

PURPOSE

To evaluate the safety and potential efficacy of LLF580, a genetically engineered variant of human fibroblast growth factor-21, for triglyceride lowering, weight loss, and hepatic fat reduction.

METHODS

A multicenter, double-blind, parallel design trial in obese, mildly hypertriglyceridemic adults randomized (1:1) to LLF580 300 mg or placebo subcutaneously every 4 weeks for 3 doses.

RESULTS

Of 64 randomized study participants, 61 (mean ± SD: age 45 ± 11 years, 49% male, 80/15/5% Caucasian/African American/other, body mass index 36.1 ± 3.8 kg/m2) received LLF580 (n = 30) or placebo (n = 31) at 7 research sites in the United States. LLF580 lowered serum triglycerides by 54% (least square mean placebo adjusted change from baseline), total cholesterol 7%, low-density lipoprotein cholesterol 12%, and increased high-density lipoprotein cholesterol 36% compared with placebo (all P < 0.001) over 12 weeks. Substantial reduction of liver fat of 52% over placebo (P < 0.001) was also demonstrated in the setting of improved liver function tests including alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase, the composite enhanced liver fibrosis score, and N-terminal type III collagen propeptide (all P < 0.05). Insulin and C-peptide levels and insulin resistance by homeostatic model assessment for insulin resistance were all lower, and adiponectin higher with LLF580 treatment compared with placebo, whereas fasting glucose and glycated hemoglobin were unchanged. Reductions in biomarkers of bone formation without differences in markers of bone resorption were observed. LLF580 was generally safe and well tolerated, except for higher incidence of generally mild to moderate gastrointestinal adverse effects.

CONCLUSIONS

In obese, mildly hypertriglyceridemic adults, LLF580 was generally safe and demonstrated beneficial effects on serum lipids, liver fat, and biomarkers of liver injury, suggesting it may be effective for treatment of select metabolic disorders including hypertriglyceridemia and nonalcoholic fatty liver disease. Assessments of longer term safety and efficacy are warranted.

CLINICALTRIALS.GOV IDENTIFIER

NCT03466203.

The Same Metabolic Response to FGF21 Administration in Male and Female Obese Mice Is Accompanied by Sex-Specific Changes in Adipose Tissue Gene Expression

The preference for high-calorie foods depends on sex and contributes to obesity development. Fibroblast growth factor 21 (FGF21) beneficially affects taste preferences and obesity, but its action has mainly been studied in males. The aim of this study was to compare the effects of FGF21 on food preferences and glucose and lipid metabolism in C57Bl/6J male and female mice with diet-induced obesity. Mice were injected with FGF21 or vehicle for 7 days. Body weight, choice between standard (SD) and high-fat (HFD) diets, blood parameters, and gene expression in white (WAT) and brown (BAT) adipose tissues, liver, muscles, and the hypothalamus were assessed. Compared to males, females had a greater preference for HFD; less WAT; lower levels of cholesterol, glucose, and insulin; and higher expression of Fgf21, Insr, Ppara, Pgc1, Acca and Accb in the liver and Dio2 in BAT. FGF21 administration decreased adiposity; blood levels of cholesterol, glucose, and insulin; hypothalamic Agrp expression, increased SD intake, decreased HFD intake independently of sex, and increased WAT expression of Pparg, Lpl and Lipe only in females. Thus, FGF21 administration beneficially affected mice of both sexes despite obesity-associated sex differences in metabolic characteristics, and it induced female-specific activation of gene expression in WAT.

Mussel-Inspired Surface Immobilization of Heparin on Magnetic Nanoparticles for Enhanced Wound Repair via Sustained Release of a Growth Factor and M2 Macrophage Polarization

Efficient reconstruction of a fully functional skin after wounds requires multiple functionalities of wound dressing due to the complexity of healing. In these regards, topical administration of functionalized nanoparticles capable of sustainably releasing bioactive agents to the wound site may significantly accelerate wound repair. Among the various nanoparticles, superparamagnetic iron oxide (Fe₃O₄) nanoparticles gain increasing attractiveness due to their intrinsic response to an external magnetic field (eMF). Herein, based on the Fe₃O₄ nanoparticle, we developed a fibroblast growth factor (bFGF)-loaded Fe₃O₄ nanoparticle using a simple mussel-inspired surface immobilization method. This nanoparticle, named as bFGF-HDC@Fe₃O₄, could stabilize bFGF in various conditions and exhibited sustained release of bFGF. In addition, an in vitro study discovered that bFGF-HDC@Fe₃O₄ could promote macrophage polarization toward an anti-inflammatory (pro-healing) M2 phenotype especially under eMF. Further, in vivo full-thickness wound animal models demonstrated that bFGF-HDC@Fe₃O₄ could significantly accelerate wound healing through M2 macrophage polarization and increased cell proliferation. Therefore, this approach of realizing sustained the release of the growth factor with magnetically macrophage regulating behavior through modification of Fe₃O₄ nanoparticles offers promising potential to tissue-regenerative applications.

FGF21 Enhances Therapeutic Efficacy and Reduces Side Effects of Dexamethasone in Treatment of Rheumatoid Arthritis

In order to investigate efficacy of FGF21 combine dexamethasone (Dex) on rheumatoid arthritis (RA) meanwhile reduce side effects of dexamethasone. We used combination therapy (Dex 15 mg/kg + FGF21 0.25 mg/kg, Dex 15 mg/kg + FGF21 0.5 mg/kg or Dex 15 mg/kg + FGF21 1 mg/kg) and monotherapy (Dex 15 mg/kg or FGF21 1 mg/kg) to treat CIA mice induced by chicken type II collagen, respectively. The effects of treatment were determined by arthritis severity score, histological damage, and cytokine production. The levels of oxidative stress parameters, liver functions, and other blood biochemical indexes were detected to determine FGF21 efficiency to side effects of dexamethasone. Oil red O was performed to detect the effects of FGF21 and dexamethasone on fat accumulation in HepG2 cells. The mechanism of FGF21 improves the side effects of dexamethasone which was analyzed by Western blotting. This combination proved to be therapeutically more effective than dexamethasone or FGF21 used singly. FGF21 regulates oxidative stress and lipid metabolism by upregulating dexamethasone-inhibited SIRT-1 and then activating downstream Nrf-2/HO-1and PGC-1. FGF21 and dexamethasone are highly effective in the treatment of arthritis; meanwhile, FGF21 may overcome the limited therapeutic response and Cushing syndrome associated with dexamethasone.

Effect of Fibroblast Growth Factor 21 on the Development of Atheromatous Plaque and Lipid Metabolic Profiles in an Atherosclerosis-Prone Mouse Model

Fibroblast growth factor 21 (FGF21) is a hormonal regulator of lipid and glucose metabolism. We aimed to investigate the effect of an FGF21 analogue (LY2405319) on the development of atherosclerosis and its associated parameters. ApoE^−/− mice were fed an atherogenic diet for 14 weeks and were randomly assigned to control (saline) or FGF21 (0.1 mg/kg) treatment group (n = 10/group) for 5 weeks. Plaque size in the aortic arch/valve areas and cardiovascular risk markers were evaluated in blood and tissues. The effects of FGF21 on various atherogenesis-related pathways were also assessed. Atherosclerotic plaque areas in the aortic arch/valve were significantly smaller in the FGF21 group than in controls after treatment. FGF21 significantly decreased body weight and glucose concentrations, and increased circulating adiponectin levels. FGF21 treatment alleviated insulin resistance and decreased circulating concentrations of triglycerides, which were significantly correlated with plaque size. FGF21 treatment reduced lipid droplets in the liver and decreased fat cell size and inflammatory cell infiltration in the abdominal visceral fat compared with the control group. The monocyte chemoattractant protein-1 levels were decreased and β-hydroxybutyrate levels were increased by FGF21 treatment. Uncoupling protein 1 expression in subcutaneous fat was greater and fat cell size in brown fat was smaller in the FGF21 group compared with controls. Administration of FGF21 showed anti-atherosclerotic effects in atherosclerosis-prone mice and exerted beneficial effects on critical atherosclerosis pathways. Improvements in inflammation and insulin resistance seem to be mechanisms involved in the mitigation of atherosclerosis by FGF21 therapy.

Baseline HOMA IR and Circulating FGF21 Levels Predict NAFLD Improvement in Patients Undergoing a Low Carbohydrate Dietary Intervention for Weight Loss: A Prospective Observational Pilot Study

Background: Non-alcoholic fatty liver disease (NAFLD) is a major cause of liver disease. Very low-calorie ketogenic diets (VLCKD) represent a feasible treatment as they induce profound weight loss and insulin resistance (IR) improvement. Despite the recognized benefits on NAFLD deriving from pharmacological administration of fibroblast growth factor 21 (FGF21), whose endogenous counterpart is a marker of liver injury, little is known about its physiology in humans. Aim: To identify predictors of NAFLD improvement as reflected by the reduction of the non-invasive screening tool hepatic steatosis index (HSI) in obese patients undergoing a weight loss program. Methods: Sixty-five obese patients underwent a 90-day dietary program consisting of a VLCKD followed by a hypocaloric low carbohydrate diet (LCD). Anthropometric parameters, body composition, and blood and urine chemistry were assessed. Results: Unlike most parameters improving mainly during the VLCKD, the deepest HSI change was observed after the LCD (p = 0.02 and p < 0.0001, respectively). Baseline HOMA-IR and serum FGF21 were found to be positive (R = 0.414, p = 0009) and negative (R = 0.364, p = 0.04) independent predictors of HSI reduction, respectively. Conclusions: We suggest that patients with IR and NAFLD derive greater benefit from a VLCKD, and we propose a possible role of human FGF21 in mediating NAFLD amelioration following nutritional manipulation.

Demodex-induced Lupus miliaris disseminatus faciei: A case report

RATIONALE

Lupus miliaris disseminatus faciei (LMDF) is an inflammatory granulomatous skin disease without a clear etiology that frequently involves the middle area of the face and the upper eyelids. Pathological features of the disease include caseation necrosis and epithelioid granuloma. Consensus treatment for LMDF is currently unavailable.

PATIENT CONCERNS

A 47-year-old Chinese female patient who presented with facial pruritic, erythematous papules 8 months before this study. She was diagnosed with skin tuberculosis at another hospital and given antituberculosis medication. However, the treatment was not efficacious.

DIAGNOSES

In this study, the diagnosis of Demodex-induced LMDF was made by a dermatologist according to physical examination, skin biopsy pathology, and microscopic examination.

INTERVENTIONS

The patient was given ornidazole tablets (500 mg twice a day) and recombinant bovine basic fibroblast growth factor gel (0.2 g/cm twice a day) for an 8-week period.

OUTCOMES

Eight weeks after the treatment, the facial erythematous papules were improved, and no new skin lesions were observed. The patient showed no signs of recurrence during the 6-month follow-up.

LESSONS SUBSECTIONS

This case showed that ornidazole combined with recombinant bovine basic fibroblast growth factor gel might be useful in treatment of Demodex-induced LMDF. In addition, the results suggested that pathological caseation necrosis was caused by a series of inflammatory and immune responses to Demodex infection.

Immobilization of FGF on Poly(xylitol dodecanedioic Acid) Polymer for Tissue Regeneration

Fibroblast growth factor (FGF) plays a vital role in the repair and regeneration of most tissues. However, its low stability, short half-life, and rapid inactivation by enzymes in physiological conditions affect their clinical applications. Therefore, to increase the effectiveness of growth factors and to improve tissue regeneration, we developed an elastic polymeric material poly(xylitol dodecanedioic acid) (PXDDA) and loaded FGF on the PXDDA for sustained drug delivery. In this study, we used a simple dopamine coating method to load FGF on the surface of PXDDA polymeric films. The polydopamine-coated FGF-loaded PXDDA samples were then characterized using FTIR and XRD. The in vitro drug release profile of FGF from PXDDA film and cell growth behavior were measured. Results showed that the polydopamine layer coated on the surface of the PXDDA film enhanced the immobilization of FGF and controlled its sustained release. Human fibroblast cells attachment and proliferation on FGF-immobilized PXDDA films were much higher than the other groups without coatings or FGF loading. Based on our results, the surface modification procedure with immobilizing growth factors shows excellent application potential in tissue regeneration.

Modulation of the Systemic Immune Response in Suckling Rats by Breast Milk TGF-β2, EGF and FGF21 Supplementation

Breast milk is a rich fluid containing bioactive compounds such as specific growth factors (GF) that contribute to maturation of the immune system in early life. The aim of this study was to determine whether transforming growth factor-β2 (TGF-β2), epidermal growth factor (EGF) and fibroblast growth factor 21 (FGF21), compounds present in breast milk, could promote systemic immune maturation. For this purpose, newborn Wistar rats were daily supplemented with these GF by oral gavage during the suckling period (21 days of life). At day 14 and 21 of life, plasma for immunoglobulin (Ig) quantification was obtained and spleen lymphocytes were isolated, immunophenotyped and cultured to evaluate their ability to proliferate and release cytokines. The main result was obtained at day 14, when supplementation with EGF increased B cell proportion to reach levels observed at day 21. At the end of the suckling period, all GF increased the plasma levels of IgG1 and IgG2a isotypes, FGF21 balanced the Th1/Th2 cytokine response and both EGF and FGF21 modified splenic lymphocyte composition. These results suggested that the studied milk bioactive factors, mainly EGF and FGF21, may have modulatory roles in the systemic immune responses in early life, although their physiological roles remain to be established.

FGF21 Protects against Aggravated Blood-Brain Barrier Disruption after Ischemic Focal Stroke in Diabetic db/db Male Mice via Cerebrovascular PPARγ Activation

Recombinant fibroblast growth factor 21 (rFGF21) has been shown to be potently beneficial for improving long-term neurological outcomes in type 2 diabetes mellitus (T2DM) stroke mice. Here, we tested the hypothesis that rFGF21 protects against poststroke blood–brain barrier (BBB) damage in T2DM mice via peroxisome proliferator-activated receptor gamma (PPARγ) activation in cerebral microvascular endothelium. We used the distal middle cerebral occlusion (dMCAO) model in T2DM mice as well as cultured human brain microvascular endothelial cells (HBMECs) subjected to hyperglycemic and inflammatory injury in the current study. We detected a significant reduction in PPARγ DNA-binding activity in the brain tissue and mRNA levels of BBB junctional proteins and PPARγ-targeting gene CD36 and FABP4 in cerebral microvasculature at 24 h after stroke. Ischemic stroke induced a massive BBB leakage two days after stroke in T2DM mice compared to in their lean controls. Importantly, all abnormal changes were significantly prevented by rFGF21 administration initiated at 6 h after stroke. Our in vitro experimental results also demonstrated that rFGF21 protects against hyperglycemia plus interleukin (IL)-1β-induced transendothelial permeability through upregulation of junction protein expression in an FGFR1 activation and PPARγ activity elevation-dependent manner. Our data suggested that rFGF21 has strong protective effects on acute BBB leakage after diabetic stroke, which is partially mediated by increasing PPARγ DNA-binding activity and mRNA expression of BBB junctional complex proteins. Together with our previous investigations, rFGF21 might be a promising candidate for treating diabetic stroke.

Pancreatitis is an FGF21-deficient state that is corrected by replacement therapy

The exocrine pancreas expresses the highest concentrations of fibroblast growth factor 21 (FGF21) in the body, where it maintains acinar cell proteostasis. Here, we showed in both mice and humans that acute and chronic pancreatitis is associated with a loss of FGF21 expression due to activation of the integrated stress response (ISR) pathway. Mechanistically, we found that activation of the ISR in cultured acinar cells and mouse pancreata induced the expression of ATF3, a transcriptional repressor that directly bound to specific sites on the Fgf21 promoter and resulted in loss of FGF21 expression. These ATF3 binding sites are conserved in the human FGF21 promoter. Consistent with the mouse studies, we also observed the reciprocal expression of ATF3 and FGF21 in the pancreata of human patients with pancreatitis. Using three different mouse models of pancreatitis, we showed that pharmacologic replacement of FGF21 mitigated the ISR and resolved pancreatitis. Likewise, inhibition of the ISR with an inhibitor of the PKR-like endoplasmic reticulum kinase (PERK) also restored FGF21 expression and alleviated pancreatitis. These findings highlight the importance of FGF21 in preserving exocrine pancreas function and suggest its therapeutic use for prevention and treatment of pancreatitis.

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

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

Useful applications of growth factors for cardiovascular regenerative medicine

Novel advances for cardiovascular diseases (CVDs) include regenerative approaches for fibrosis, hypertrophy, and neoangiogenesis. Studies indicate that growth factor (GF) signaling could promote heart repair since most of the evidence is derived from preclinical models. Observational studies have evaluated GF serum/plasma levels as feasible biomarkers for risk stratification of CVDs. Noteworthy, two clinical interventional published studies showed that the administration of growth factors (GFs) induced beneficial effect on left ventricular ejection fraction (LVEF), myocardial perfusion, end-systolic volume index (ESVI). To date, large scale ongoing studies are in Phase I-II and mostly focussed on intramyocardial (IM), intracoronary (IC) or intravenous (IV) administration of vascular endothelial growth factor (VEGF) and fibroblast growth factor-23 (FGF-23) which result in the most investigated GFs in the last 10 years. Future data of ongoing randomized controlled studies will be crucial in understanding whether GF-based protocols could be in a concrete way effective in the clinical setting.

Therapeutic Angiogenesis

Myocardial ischemia and peripheral vascular disease persist as significant clinical problems despite improved medical, surgical, and endovascular therapies. Advances in our understanding of the biological mechanisms that govern capillary neovascularization and collateral artery growth have enabled molecular therapies for revascularizing ischemic tissues. Generally known as therapeutic angiogenesis, this review summarizes the essential pre-clinical research and the major clinical trials of molecular therapies for ischemic disease. Early clinical experience has established the proof of principle, however, inconsistent and modest improvements in clinical outcomes have exposed the complexity of neovascularization and problems with transitioning basic science to clinical applicability.

Effect of Intra-Articular Sprifermin vs Placebo on Femorotibial Joint Cartilage Thickness in Patients With Osteoarthritis: The FORWARD Randomized Clinical Trial

IMPORTANCE

Sprifermin is under investigation as a disease-modifying osteoarthritis drug.

OBJECTIVE

To evaluate the effects of sprifermin on changes in total femorotibial joint cartilage thickness in the more symptomatic knee of patients with osteoarthritis.

DESIGN, SETTING, AND PARTICIPANTS

FORWARD (FGF-18 Osteoarthritis Randomized Trial with Administration of Repeated Doses) was a 5-year, dose-finding, multicenter randomized clinical trial conducted at 10 sites. Eligible participants were aged 40 to 85 years with symptomatic, radiographic knee osteoarthritis and Kellgren-Lawrence grade 2 or 3. Enrollment began in July 2013 and ended in May 2014; the last participant visit occurred on May 8, 2017. The primary outcome at 2 years and a follow-up analysis at 3 years are reported.

INTERVENTIONS

Participants were randomized to 1 of 5 groups: intra-articular injections of 100 μg of sprifermin administered every 6 months (n = 110) or every 12 months (n = 110), 30 μg of sprifermin every 6 months (n = 111) or every 12 months (n = 110), or placebo every 6 months (n = 108). Each treatment consisted of weekly injections over 3 weeks.

MAIN OUTCOMES AND MEASURES

The primary end point was change in total femorotibial joint cartilage thickness measured by quantitative magnetic resonance imaging at 2 years. The secondary end points (of 15 total) included 2-year change from baseline in total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. The minimal clinically important difference (MCID) is unknown for the primary outcome; for total WOMAC score in patients with hip and knee osteoarthritis, the absolute MCID is 7 U (95% CI, 4 to 10 U) and the percentage MCID is 14% (95% CI, 9% to 18%).

RESULTS

Among 549 participants (median age, 65.0 years; 379 female [69.0%]), 474 (86.3%) completed 2-year follow-up. Compared with placebo, the changes from baseline to 2 years in total femorotibial joint cartilage thickness were 0.05 mm (95% CI, 0.03 to 0.07 mm) for 100 μg of sprifermin administered every 6 months; 0.04 mm (95% CI, 0.02 to 0.06 mm) for 100 μg of sprifermin every 12 months; 0.02 mm (95% CI, -0.01 to 0.04 mm) for 30 μg of sprifermin every 6 months; and 0.01 mm (95% CI, -0.01 to 0.03 mm) for 30 μg of sprifermin every 12 months. Compared with placebo, there were no statistically significant differences in mean absolute change from baseline in total WOMAC scores for 100 μg of sprifermin administered every 6 months or every 12 months, or for 30 μg of sprifermin every 6 months or every 12 months. The most frequently reported treatment-emergent adverse event was arthralgia (placebo: n = 46 [43.0%]; 100 μg of sprifermin administered every 6 months: n = 45 [41.3%]; 100 μg of sprifermin every 12 months: n = 50 [45.0%]; 30 μg of sprifermin every 6 months: n = 40 [36.0%]; and 30 μg of sprifermin every 12 months: n = 48 [44.0%]).

CONCLUSIONS AND RELEVANCE

Among participants with symptomatic radiographic knee osteoarthritis, the intra-articular administration of 100 μg of sprifermin every 6 or 12 months vs placebo resulted in an improvement in total femorotibial joint cartilage thickness after 2 years that was statistically significant, but of uncertain clinical importance; there was no significant difference for 30 μg of sprifermin every 6 or 12 months vs placebo. Durability of response also was uncertain.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01919164.

Fibroblast Growth Factor-21 Controls Dietary Protein Intake in Male Mice

Whereas carbohydrates and lipids are stored as glycogen and fat, there is no analogous inert storage form of protein. Therefore, continuous adjustments in feeding behavior are needed to match amino acid supply to ongoing physiologic need. Neuroendocrine mechanisms facilitating this behavioral control of protein and amino acid homeostasis remain unclear. The hepatokine fibroblast growth factor-21 (FGF21) is well positioned for such a role, as it is robustly secreted in response to protein and/or amino acid deficit. In this study, we tested the hypothesis that FGF21 feeds back at its receptors in the nervous system to shift macronutrient selection toward protein. In a series of behavioral tests, we isolated the effect of FGF21 to influence consumption of protein, fat, and carbohydrate in male mice. First, we used a three-choice pure macronutrient-diet paradigm. In response to FGF21, mice increased consumption of protein while reducing carbohydrate intake, with no effect on fat intake. Next, to determine whether protein or carbohydrate was the primary-regulated nutrient, we used a sequence of two-choice experiments to isolate the effect of FGF21 on preference for each macronutrient. Sweetness was well controlled by holding sucrose constant across the diets. Under these conditions, FGF21 increased protein intake, and this was offset by reducing the consumption of either carbohydrate or fat. When protein was held constant, FGF21 had no effect on macronutrient intake. Lastly, the effect of FGF21 to increase protein intake required the presence of its co-receptor, β-klotho, in neurons. Taken together, these findings point to a novel liver→nervous system pathway underlying the regulation of dietary protein intake via FGF21.

Fusion of fibroblast growth factor 21 to a thermally responsive biopolymer forms an injectable depot with sustained anti-diabetic action

Fibroblast growth factor 21 (FGF21) is under investigation as a type 2 diabetes protein drug, but its efficacy is impeded by rapid in vivo clearance and by costly production methods. To improve the protein's therapeutic utility, we recombinantly expressed FGF21 as a fusion with an elastin-like polypeptide (ELP), a peptide polymer that exhibits reversible thermal phase behavior. Below a critical temperature, ELPs exist as miscible unimers, while above, they associate into a coacervate. The thermal responsiveness of ELPs is retained upon fusion to proteins, which has notable consequences for the production and in vivo delivery of FGF21. First, the ELP acts as a solubility enhancer during E. coli expression, yielding active fusion protein from the soluble cell lysate fraction and eliminating the protein refolding steps that are required for purification of FGF21 from inclusion bodies. Second, the ELP's phase transition behavior is exploited for facile chromatography-free purification of the ELP-FGF21 fusion. Third, the composition and molecular weight of the ELP are designed such that the ELP-FGF21 fusion undergoes a phase transition triggered solely by body heat, resulting in an immiscible viscous phase upon subcutaneous (s.c.) injection and thereby creating an injectable depot. Indeed, a single s.c. injection of ELP-FGF21 affords up to five days of sustained glycemic control in ob/ob mice. The ELP fusion partner massively streamlines production and purification of FGF21, while providing a controlled release method for delivery that reduces the frequency of injection, thereby enhancing the pharmacological properties of FGF21 as a protein drug to treat metabolic disease.

Dietary Manipulations That Induce Ketosis Activate the HPA Axis in Male Rats and Mice: A Potential Role for Fibroblast Growth Factor-21

In response to an acute threat to homeostasis or well-being, the hypothalamic-pituitary-adrenocortical (HPA) axis is engaged. A major outcome of this HPA axis activation is the mobilization of stored energy, to fuel an appropriate behavioral and/or physiological response to the perceived threat. Importantly, the extent of HPA axis activity is thought to be modulated by an individual's nutritional environment. In this study, we report that nutritional manipulations signaling a relative depletion of dietary carbohydrates, thereby inducing nutritional ketosis, acutely and chronically activate the HPA axis. Male rats and mice maintained on a low-carbohydrate high-fat ketogenic diet (KD) exhibited canonical markers of chronic stress, including increased basal and stress-evoked plasma corticosterone, increased adrenal sensitivity to adrenocorticotropin hormone, increased stress-evoked c-Fos immunolabeling in the paraventricular nucleus of the hypothalamus, and thymic atrophy, an indicator of chronic glucocorticoid exposure. Moreover, acutely feeding medium-chain triglycerides (MCTs) to rapidly induce ketosis among chow-fed male rats and mice also acutely increased HPA axis activity. Lastly, and consistent with a growing literature that characterizes the hepatokine fibroblast growth factor-21 (FGF21) as both a marker of the ketotic state and as a key metabolic stress hormone, the HPA response to both KD and MCTs was significantly blunted among mice lacking FGF21. We conclude that dietary manipulations that induce ketosis lead to increased HPA axis tone, and that the hepatokine FGF21 may play an important role to facilitate this effect.

Once-weekly administration of a long-acting fibroblast growth factor 21 analogue modulates lipids, bone turnover markers, blood pressure and body weight differently in obese people with hypertriglyceridaemia and in non-human primates

AIMS

To assess the safety, tolerability, pharmacokinetics and pharmacodynamics of PF-05231023, a long-acting fibroblast growth factor 21 (FGF21) analogue, in obese people with hypertriglyceridaemia on atorvastatin, with or without type 2 diabetes.

METHODS

Participants received PF-05231023 or placebo intravenously once weekly for 4 weeks. Safety (12-lead ECGs, vital signs, adverse events [AEs], laboratory tests) and longitudinal weight assessments were performed. Blood samples were collected for pharmacokinetic and pharmacodynamic analyses. Cardiovascular safety studies were also conducted in telemetered rats and monkeys. Blood pressure (BP; mean, systolic and diastolic) and ECGs were monitored.

RESULTS

A total of 107 people were randomized. PF-05231023 significantly decreased mean placebo-adjusted fasting triglycerides (day 25, 33%-43%) and increased HDL cholesterol (day 25, 15.7%-28.6%) and adiponectin (day 25, 1574 to 3272 ng/mL) across all doses, without significant changes in body weight (day 25, -0.45% to -1.21%). Modest decreases from baseline were observed for N-terminal propeptides of type 1 collagen (P1NP) on day 25, although C-telopeptide cross-linking of type 1 collagen (CTX-1) increased minimally. Systolic, diastolic BP, and pulse rate increased in a dose- and time-related manner. There were 5 serious AEs (one treatment-related) and no deaths. Three participants discontinued because of AEs. The majority of AEs were gastrointestinal. PF-05231023 increased BP and heart rate in rats, but not in monkeys.

CONCLUSIONS

Once-weekly PF-05231023 lowered triglycerides markedly in the absence of weight loss, with modest changes in markers of bone homeostasis. This is the first report showing increases in BP and pulse rate in humans and rats after pharmacological administration of a long-acting FGF21 molecule.

Fgf21 regulates T-cell development in the neonatal and juvenile thymus

We have previously shown that Fibroblast growth factor 21 (Fgf21) is expressed in the thymus as well as in the liver. In line with this expression profile, Fgf21 was recently reported to protect against ageing-related thymic senescence by improving the function of thymic epithelial cells (TECs). However, the function of Fgf21 in the juvenile thymus remained to be elucidated. We investigated the physiological roles of Fgf21 in the juvenile thymus and found that young Fgf21 knockout mice, but not β-Klotho knockout mice nor adult Fgf21 knockout mice, showed a significant reduction in the percentage of single-positive CD4+ and CD8+ thymocytes without obvious alteration in TECs. Furthermore, treatment with recombinant FGF21 protein rescued the impairment in fetal thymus organ culture (FTOC) of Fgf21 knockout mice. Annexin V staining revealed FGF21 protein enhanced apoptosis of immature thymocytes undergoing selection process in FTOC, suggesting that FGF21 may facilitate the selection of developing T cells. Endocrine Fgf21 from the liver induced by metabolic stimulation did not affect juvenile thymocyte development. Our data suggest that Fgf21 acts as one of intrathymic cytokines in the neonatal and juvenile thymus, involving thymocyte development in a β-Klotho-independent manner.

A first-in-human, double-blind, randomised, placebo-controlled, dose ascending study of intra-articular rhFGF18 (sprifermin) in patients with advanced knee osteoarthritis

OBJECTIVES

To evaluate the safety of intra-articular sprifermin (primary), and to evaluate systemic exposure, biomarkers, histology, and other cartilage parameters in patients with advanced osteoarthritis (OA).

METHODS

This was a first-in-human, double-blind, randomised, placebo-controlled trial of single and multiple ascending doses of sprifermin from 3-300 μg in knee OA patients scheduled for total knee replacement. Patients were randomised 3:1 to sprifermin or placebo, injected into the target knee once or once weekly for 3 weeks, and followed-up for 24 weeks.

RESULTS

Fifty-five patients were treated with sprifermin, 25 with single and 30 with multiple doses, 18 received placebo. There was no clear difference between the active and placebo groups in incidence, severity, and nature of reported treatment emergent adverse events. Acute inflammatory reactions were slightly more common with sprifermin 300 μg, but none led to discontinuation. No clear difference was seen between placebo and sprifermin in physician-assessed local tolerability, pain, or swelling in the knee. No meaningful changes over time, or differences between treatment groups, were observed for safety laboratory parameters or ECG. Although individual abnormalities were observed, no patterns were evident suggesting a relation to treatment or potential safety concern. No systemic sprifermin exposure, anti-FGF18 antibodies, or clear-cut effects on systemic biomarkers were detected.

CONCLUSIONS

This first clinical trial of sprifermin revealed no serious safety concerns, although larger studies are needed. The possibility of positive effects of intra-articular sprifermin on histological and other cartilage parameters in knee OA also warrant further investigation.

Exercise-stimulated FGF23 promotes exercise performance via controlling the excess reactive oxygen species production and enhancing mitochondrial function in skeletal muscle

OBJECTIVE

Physical exercise induces many adaptive changes in skeletal muscle and the whole body and improves metabolic characteristics. Fibroblast growth-factor 23 (FGF23) is a unique member of the FGF family that acts as a hormone regulating phosphate metabolism, calcitriol concentration, and kidney functions. The role of FGF23 in exercise and skeletal muscle is largely unknown yet.

MATERIALS AND METHODS

C57BL/6J mice were exercised on a motor treadmill. Mice serum FGF23 levels; FGF23 mRNA expression in various organs including the liver, heart, skeletal muscle tissue, and thyroid; and FGF23 receptor Klotho mRNA expression were examined using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and immunoblotting, respectively, after a single bout of acute exercise (60min), exhaustive exercise, and chronic prolonged exercise (60min every day for one week). C57BL/6J mice were injected with recombinant FGF23 (100mg/kg, twice per day, i.p.) or vehicle control (saline) for 3days, and then the exercise performance, reactive oxygen species (ROS), H2O2 production, and mitochondrial functional biomarkers in muscle (gene expression of sirtuin 1, PPAR-δ, PGC-1α and mitochondrial transcription factor A [TFAM], and citrate synthase activity) were assayed.

RESULTS

Three forms of exercise, acute exercise, exhaustive exercise, and chronic exercise, increased serum FGF23 levels. However, only chronic exercise upregulated FGF23 mRNA and protein expression in skeletal muscle. FGF23 mRNA expression in the heart, liver, and thyroid was not affected. FGF23 protein was mainly located in the cytoplasm in skeletal muscle tissue and the localization of FGF23 was not altered by exercise. Exogenous FGF23 treatment significantly extended the time to exhaustion and reduced the exercise-induced ROS and H2O2 production. FGF23 treatment increased the mRNA level of PPAR-δ and citrate synthase activity, but did not influence the mRNA expression of sirtuin 1, PGC-1α, and TFAM in skeletal muscle.

CONCLUSION

These results demonstrate that exercise-stimulated FGF23 promotes exercise performance via controlling the excess ROS production and enhancing mitochondrial function in skeletal muscle, which reveals an entirely novel role of FGF23 in skeletal muscle.

Extracellular matrix-inspired growth factor delivery systems for bone regeneration

Growth factors are very promising molecules to enhance bone regeneration. However, their translation to clinical use has been seriously limited, facing issues related to safety and cost-effectiveness. These problems derive from the vastly supra-physiological doses of growth factor used without optimized delivery systems. Therefore, these issues have motivated the development of new delivery systems allowing better control of the spatiotemporal release and signaling of growth factors. Because the extracellular matrix (ECM) naturally plays a fundamental role in coordinating growth factor activity in vivo, a number of novel delivery systems have been inspired by the growth factor regulatory function of the ECM. After introducing the role of growth factors during the bone regeneration process, this review exposes different issues that growth factor-based therapies have encountered in the clinic and highlights recent delivery approaches based on the natural interaction between growth factor and the ECM.

Dual effects of fibroblast growth factor 21 on hepatic energy metabolism

The aim of this study was to investigate the mechanisms by which fibroblast growth factor 21 (FGF21) affects hepatic integration of carbohydrate and fat metabolism in Siberian hamsters, a natural model of adiposity. Twelve aged matched adult male Siberian hamsters maintained in their long-day fat state since birth were randomly assigned to one of two treatment groups and were continuously infused with either vehicle (saline; n=6) or recombinant human FGF21 protein (1 mg/kg per day; n=6) for 14 days. FGF21 administration caused a 40% suppression (P<0.05) of hepatic pyruvate dehydrogenase complex (PDC), the rate-limiting step in glucose oxidation, a 34% decrease (P<0.05) in hepatic acetylcarnitine accumulation, an index of reduced PDC flux, a 35% increase (P<0.05) in long-chain acylcarnitine content (an index of flux through β-oxidation) and a 47% reduction (P<0.05) in hepatic lipid content. These effects were underpinned by increased protein abundance of PD kinase-4 (PDK4, a negative regulator of PDC), the phosphorylated (inhibited) form of acetyl-CoA carboxylase (ACC, a negative regulator of delivery of fatty acids into the mitochondria) and the transcriptional co-regulators of energy metabolism peroxisome proliferator activated receptor gamma co-activator alpha (PGC1α) and sirtuin-1. These findings provide novel mechanistic basis to support the notion that FGF21 exerts profound metabolic benefits in the liver by modulating nutrient flux through both carbohydrate (mediated by a PDK4-mediated suppression of PDC activity) and fat (mediated by deactivation of ACC) metabolism, and therefore may be an attractive target for protection from increased hepatic lipid content and insulin resistance that frequently accompany obesity and diabetes.

A mutein of human basic fibroblast growth factor TGP-580 accelerates colonic ulcer healing by stimulating angiogenesis in the ulcer bed in rats

Previously, we reported that TGP-580, a mutein of human basic fibroblast growth factor (bFGF), accelerated the healing of gastric and duodenal ulcers in rats. In the present study, we examined the effect of TGP-580 on the healing of colonic ulcers. In male Sprague Dawley rats, ulcers were induced in the colon 6 cm from the anus by enema of 50 μl of 3% N-ethylmaleimide, a sulfhydryl alkylator. The lesions were examined under a dissecting microscope (x10). The concentration of bFGF in the ulcerated colon was measured by enzyme immunoassay, and both the distribution of bFGF and the density of microvessels in the ulcer bed were examined by immunohistochemical staining. The content of bFGF in the ulcerated colon was markedly increased associated with ulcer healing, and ulcer healing was significantly delayed by intravenous administration of a monoclonal antibody for bFGF (MAb 3H3) once daily for 10 days. In the ulcer bed, many cells such as fibroblasts, vascular endothelial cells and macrophages were positively stained with bFGF antiserum. TGP-580, human bFGF or dexamethasone was given intracolonally twice daily for 10 days, starting the day after ulcer induction. TGP-580 (0.2 - 20 μg/ml, 200 μl/rat) dose-dependently accelerated ulcer healing, and its effect was more than 10 times stronger than that of human bFGF. Density (μm/0.01 mm(2)) of microvessels in the ulcer bed was significantly increased by treatment with TGP-580, and there was a good correlation between the density of microvessels and the decrease of ulcerated area (R(2) = 0.633). On the other hand dexamethasone (20 μg/ml) inhibited angiogenesis in the ulcer bed and delayed ulcer healing. These results suggest that angiogenesis in the ulcer bed plays an important role in ulcer healing, and that bFGF mutein TGP-580 accelerated colonic ulcer healing, at least in part, by stimulating angiogenesis, whereas glucocorticoids may delay the healing by inhibiting angiogenesis.

FGF19 promotes progression of prostate cancer

BACKGROUND

Fibroblast growth factor (FGF) signaling pathways have been reported to play important roles in prostate cancer (PCa) progression. FGF19 is one of a subfamily of FGFs that circulate in serum and act in an endocrine manner. Our objective was to investigate its role in the progression of PCa.

METHODS

The effect of FGF19 on the proliferation and epithelial-mesenchymal transition of LNCaP and PC3 cells was examined using MTT assay and Western blotting. Serum concentration of FGF19 was measured by ELISA in 209 patients with PCa, and the association between clinicopathological features and the presence of FGF19-positive cells in tissues derived from 155 patients who undergone radical prostatectomy was investigated.

RESULTS

Under androgen-deprived conditions achieved by incubation in medium with FGF19, the expression of N-cadherin in LNCaP cells was enhanced, that of E-cadherin and caspase 3 was suppressed, and the viability of LNCaP and PC3 cells was significantly enhanced. Significantly higher levels of PSA were recorded in the group determined by immunohistochemistry staining to be FGF19-positive (P = 0.0046). The 5-year biochemical recurrence-free survival rate after radical prostatectomy was 46.4% in the FGF19-positive group and 70.0% in the FGF19-negative group (P = 0.0027). In multivariate analysis, the presence of FGF19-positive tissues was an independent factor for worse prognosis after radical prostatectomy (P = 0.0052). Serum FGF19 levels in high Gleason grade group were higher than that in low Gleason grade group (P = 0.0009).

CONCLUSIONS

FGF19 might be associated with biochemical recurrence after radical prostatectomy by promoting cell proliferation and epithelial-mesenchymal transition of PCa.

Feeder-free and xeno-free culture of human pluripotent stem cells using UCBS matrix

The ideal medium for human pluripotent stem cells (hPSCs) culture should be feeder-free, xeno-free, and completely defined. The present study aims to establish a new feeder-free and xeno-free system for culturing hPSCs. The system consists of the matrix, which was prepared from human umbilical cord blood serum (UCBS) and used to coat the culture plates, and the xeno-free medium, which was conventional serum-free hES medium supplemented with high concentrations of bFGF and Fibronectin. Compared with matrigel and mouse embryonic fibroblasts (MEFs), the UCBS matrix was proved to be equally suitable for the growth of hPSCs. After a series of experiments with different media and cytokins, the UCBS matrix was found worked the best with the basic medium (BM) supplemented with 20 ng/mL bFGF, 10 ug/mL fibronectin and Y-27632 for culture of hES cells. The hPSCs maintained normal karyotype, high proliferation rate and self-renewal ability after continuous culture more than 10 passages in this feeder-free and xeno-free system. Furthermore, a new human embryonic stem (hES) cell line was derived from discarded day 3 embryos in this newly developed culture system. In conclusion, this feeder-free and xeno-free system could not only be used to the culture hPSCs, but could also be used to derive new hES cell lines.

Pharmacokinetics (PK), pharmacodynamics (PD) and integrated PK/PD modeling of a novel long acting FGF21 clinical candidate PF-05231023 in diet-induced obese and leptin-deficient obese mice

Pharmacological administration of fibroblast growth factor 21 (FGF21) improves metabolic profile in preclinical species and humans. FGF21 exerts its metabolic effects through formation of beta-klotho (KLB)/FGF receptor 1c FGFR1c complex and subsequent signaling. Data from various in vitro systems demonstrate the intact C- and N-terminus of FGF21 is required for binding with KLB, and interaction with FGFR1c, respectively. However the relative roles of the termini for in vivo pharmacological effects are unclear. Here we report PF-05231023, a long-acting FGF21 analogue which is unique in that the half-life and subcutaneous (SC) bioavailability of the intact C-terminus are significantly different from those of the intact N-terminus (2 vs. 22 hr for half-life and 4~7 vs. ~50% SC bioavailability). Therefore, this molecule serves as a valuable tool to evaluate the relative roles of intact C-terminus vs. N-terminus in in vivo pharmacology studies in preclinical species. We determined the effects of PF-05231023 administration on body weight (BW) loss and glucose reduction during an oral glucose tolerance test (OGTT) following SC and intravenous (IV) administration in diet-induced obese (DIO) and leptin-deficient obese (ob/ob) mice, respectively. Our data show that the intact N-terminus of FGF21 in PF-05231023 appears to be sufficient to drive glucose lowering during OGTT and sustain BW loss in DIOs. Further, PK/PD modeling suggests that while the intact FGF21 C-terminus is not strictly required for glucose lowering during OGTT in ob/ob mice or for BW reduction in DIO mice, the higher potency conferred by intact C-terminus contributes to a rapid initiation of pharmacodynamic effects immediately following dosing. These results provide additional insight into the strategy of developing stabilized versions of FGF21 analogs to harness the full spectrum of its metabolic benefits.

An in vitro cord formation assay identifies unique vascular phenotypes associated with angiogenic growth factors

Vascular endothelial growth factor (VEGF) plays a dominant role in angiogenesis. While inhibitors of the VEGF pathway are approved for the treatment of a number of tumor types, the effectiveness is limited and evasive resistance is common. One mechanism of evasive resistance to inhibition of the VEGF pathway is upregulation of other pro-angiogenic factors such as fibroblast growth factor (FGF) and epidermal growth factor (EGF). Numerous in vitro assays examine angiogenesis, but many of these assays are performed in media or matrix with multiple growth factors or are driven by VEGF. In order to study angiogenesis driven by other growth factors, we developed a basal medium to use on a co-culture cord formation system of adipose derived stem cells (ADSCs) and endothelial colony forming cells (ECFCs). We found that cord formation driven by different angiogenic factors led to unique phenotypes that could be differentiated and combination studies indicate dominant phenotypes elicited by some growth factors. VEGF-driven cords were highly covered by smooth muscle actin, and bFGF-driven cords had thicker nodes, while EGF-driven cords were highly branched. Multiparametric analysis indicated that when combined EGF has a dominant phenotype. In addition, because this assay system is run in minimal medium, potential proangiogenic molecules can be screened. Using this assay we identified an inhibitor that promoted cord formation, which was translated into in vivo tumor models. Together this study illustrates the unique roles of multiple anti-angiogenic agents, which may lead to improvements in therapeutic angiogenesis efforts and better rational for anti-angiogenic therapy.

[Therapeutic effect of fibroblast growth factor 21 on NAFLD in MSG-iR mice and its mechanism]

This study is to evaluate the therapeutic effect of fibroblast growth factor 21 (FGF21) on NAFLD in MSG-IR mice and to provide mechanism insights into its therapeutic effect. The MSG-IR mice with insulin resistance were treated with high dose (0.1 micromol.kg-1d-1) and low dose (0.025 micromol.kg-1d-1) of FGF21 once a day for 5 weeks. Body weight was measured weekly. At the end of the experiment, serum lipids, insulin and aminotransferases were measured. Hepatic steatosis was observed. The expression of key genes regulating energy metabolism were detected by real-time PCR. The results showed that after 5 weeks treatment, both doses of FGF21 reduced body weight (P<0.01), corrected dyslipidemia (P<0.01), reversed steatosis and restored the liver morphology in the MSG model mice and significantly ameliorated insulin resistance. Additionally, real-time PCR showed that FGF21 significantly reduced transcription levels of fat synthetic genes, decreased fat synthesis and promoted lipolysis and energy metabolism by up-regulating key genes of lipolysis, thereby liver fat accumulation was reduced and liver function was restored to normal levels. In conclusion, FGF21 significantly reduces body weight of the MSG-IR mice, ameliorates insulin resistance, reverses hepatic steatosis. These findings provide a theoretical support for clinical application of FGF21 as a novel therapeutics for treatment of NAFLD.

Fibroblast growth factor 21, the endocrine FGF pathway and novel treatments for metabolic syndrome

Diabetes and associated metabolic conditions have reached pandemic proportions worldwide, and there is a clear unmet medical need for effective and safe therapies. Fibroblast growth factor (FGF)21 is an atypical member of the FGF family. The ability of FGF21 to normalize glucose, lipid and energy homeostasis has attracted considerable interest as a potential therapeutic for treating diabetes and obesity. Many different engineering approaches have successfully improved the plasma half life, protein stability and solubility, as well as 'manufacturability' of FGF21. Novel approaches such as agonist antibodies to FGF21 receptor complexes have opened new opportunities previously unavailable. This review summarizes recent advances in understanding the functions, target tissues and receptors for FGF21. Furthermore, it provides an up-to-date appraisal of the approaches on therapeutic development targeting this pathway.

FGF19 action in the brain induces insulin-independent glucose lowering

Insulin-independent glucose disposal (referred to as glucose effectiveness [GE]) is crucial for glucose homeostasis and, until recently, was thought to be invariable. However, GE is reduced in type 2 diabetes and markedly decreased in leptin-deficient ob/ob mice. Strategies aimed at increasing GE should therefore be capable of improving glucose tolerance in these animals. The gut-derived hormone FGF19 has previously been shown to exert potent antidiabetic effects in ob/ob mice. In ob/ob mice, we found that systemic FGF19 administration improved glucose tolerance through its action in the brain and that a single, low-dose i.c.v. injection of FGF19 dramatically improved glucose intolerance within 2 hours. Minimal model analysis of glucose and insulin data obtained during a frequently sampled i.v. glucose tolerance test showed that the antidiabetic effect of i.c.v. FGF19 was solely due to increased GE and not to changes of either insulin secretion or insulin sensitivity. The mechanism underlying this effect appears to involve increased metabolism of glucose to lactate. Together, these findings implicate the brain in the antidiabetic action of systemic FGF19 and establish the brain’s capacity to rapidly, potently, and selectively increase insulin-independent glucose disposal.

Cellular mechanisms by which FGF21 improves insulin sensitivity in male mice

Fibroblast growth factor 21 (FGF21) is a potent regulator of glucose and lipid metabolism and is currently being pursued as a therapeutic agent for insulin resistance and type 2 diabetes. However, the cellular mechanisms by which FGF21 modifies insulin action in vivo are unclear. To address this question, we assessed insulin action in regular chow- and high-fat diet (HFD)-fed wild-type mice chronically infused with FGF21 or vehicle. Here, we show that FGF21 administration results in improvements in both hepatic and peripheral insulin sensitivity in both regular chow- and HFD-fed mice. This improvement in insulin responsiveness in FGF21-treated HFD-fed mice was associated with decreased hepatocellular and myocellular diacylglycerol content and reduced protein kinase Cε activation in liver and protein kinase Cθ in skeletal muscle. In contrast, there were no effects of FGF21 on liver or muscle ceramide content. These effects may be attributed, in part, to increased energy expenditure in the liver and white adipose tissue. Taken together, these data provide a mechanism by which FGF21 protects mice from lipid-induced liver and muscle insulin resistance and support its development as a novel therapy for the treatment of nonalcoholic fatty liver disease, insulin resistance, and type 2 diabetes.

[Therapeutic effect of fibroblast growth factor 21 on hypertension induced by insulin resistance]

This study is to evaluate the therapeutic effect of fibroblast growth factor 21 (FGF21) on hypertension induced by insulin resistance in rats and to provide mechanistic insights into its therapeutic effect. Male Sprague-Dawley (SD) rats were fed with high-fructose (10%) water to develop mild hypertensive models within 4 weeks, then randomized into 4 groups: model control, FGF21 0.25, 0.1 and 0.05 micromol x kg(-1) x d(-1) groups. Five age-matched normal SD rats administrated with saline were used as normal controls. The rats in each group were treated once a day for 4 weeks. Body weight was measured weekly, systolic blood pressure (SBP) was measured noninvasively using a tail-cuff method, insulin sensitivity was assessed using oral glucose tolerance test (OGTT) and HOMA-IR assay. At the end of the treatment, blood samples were collected, and blood glucose, serum cholesterol, serum triglyceride and serum insulin were measured. The results showed that blood pressure of the rats treated with different doses of FGF21 returned to normal levels [(122.2 +/- 3.5) mmHg, P < 0.01] after 4-week treatment, whereas, SBP of untreated (model control) rats maintained a high level [(142.5 +/- 4.5) mmHg] throughout the treatment. The observation of blood pressure in 24 h revealed that SBP of FGF21 treated-rats maintained at (130 +/- 4.5) mmHg vs. (143 +/- 5.5) mmHg for model control (P < 0.01). FGF21 treatment groups improved serum lipids obviously, total cholesterol (TC) and triglyceride (TG) levels decreased significantly to normal levels. The serum NO levels of three different doses FGF21 treatment group were significantly higher than that of the model control group [(7.32 +/- 0.11), (7.24 +/- 0.13), (6.94 +/- 0.08) vs. (6.56 +/- 0.19) micromol x L(-1), P < 0.01], and the degree of improvement showed obvious dose-dependent manner, indicating that FGF21 can significant increase serum NO in fructose-induced hypertension rat model and improve endothelial NO release function. The results of OGTT and HOMA-IR showed that insulin resistance state was significantly relieved in a dose-dependent manner. Thus, this study demonstrates that FGF21 significantly ameliorates blood pressure in fructose-induced hypertension model by relieving insulin resistance. This finding provides a theoretical support for clinical application of FGF21 as a novel therapeutics for treatment of essential hypertension.

[The long lasting effect of the murine fibroblast growth factor-21 on blood glucose control of diabetic animals]

Insulin is the most common medicine used for diabetic patients, unfortunately, its effective time is short, even the long-acting insulin cannot obtain a satisfactory effect. Fibroblast growth factor (FGF)-21 is a recently discovered glucose mediator and expected to be a potential anti-diabetic drug that does not rely on insulin. In this study, db/db mice were used as the type 2 diabetic model to examine whether mFGF-21 has the long-term blood lowering effect on the animal model. The results showed that mFGF-21 could stably maintain the blood glucose at normal level for a long-term in a dose-dependent manner. Administration of mFGF-21 once a day with three doses (0.125, 0.25 and 0.5 mg x kg(-1)) could maintain blood glucose of the model animals at normal level for at least 24 h. Administration of mFGF-21 every two days with the same doses could maintain blood glucose of the model animals at normal level for at least 48 h, although it took longer time for blood glucose to reach to normal level depending on doses used (twenty injections for 0.125 mg x kg(-1) and 0.25 mg x kg(-1) doses, ten injections for 0.5 mg x kg(-1) dose). Surprisingly, the blood glucose of the treated model animals still maintained at normal level for 24 h after the experiment terminated. Glycosylated hemoglobin level of the animals treated with mFGF-21, which represented long-term glucose status, decreased significantly compared to the control group and the insulin group. The results suggest that FGF-21 has potential to become a long-acting and potent anti-diabetic drug.

FGF21 requires βklotho to act in vivo

FGF21 has gradually become a focal point in metabolic research given its intriguing and complex biology and relevance to drug discovery. Despite the large amount of accumulated data, there remains a dearth of understanding of FGF21 physiology at the molecular/whole organism level. The scaffold protein βklotho (KLB) has previously been demonstrated in vitro to function as a co-factor permitting FGF21 mediated FGF receptor activation. However, the requirement for KLB in the propagation of FGF21 action in living animals has yet to be evaluated. To answer this question, we tested FGF21 in mice with total body ablation of KLB (KLBKO) and found no detectable activity. Firstly, we demonstrate that the disruption of KLB entirely abrogates acute FGF21 signaling in adipose tissue. We go on to show that this signaling defect translates to the absence of FGF21 mediated metabolic improvements in DIO mice. Indeed, KLBKO mice are totally refractory to FGF21-induced normalization of glucose homeostasis, attenuation of dyslipidemia, elevation of energy expenditure and weight loss. The lack of FGF21-driven effects was further substantiated at the transcriptional level with no FGF21 target gene signature detectable in adipose tissue and liver of KLBKO animals. Taken together our data show that KLB is a vital component of the FGF21 in vivo signaling machinery and is critically required for FGF21 action at the whole organism level.

Long-acting FGF21 has enhanced efficacy in diet-induced obese mice and in obese rhesus monkeys

Fibroblast growth factor 21 (FGF21), a hormone with short half-life, has consistently shown strong pharmacological efficacy. We first assessed the efficacy of murine recombinant FGF21 in C57BL6 lean mice for 5 wk. We then generated a long-acting FGF21 molecule by fusing a Fc to a variant of human recombinant FGF21 (hrFGF21) that contained two engineered mutations [L98R, P171G; Fc-FGF21(RG)] and tested it in C57BL6 diet-induced obese mice and obese rhesus monkeys. We compared its metabolic properties with those of the hrFGF21. Groups of diet-induced obese mice were treated for 36 d with different doses of hrFGF21 (01, 0.3, and 1 mg/kg twice daily) and with Fc-FGF21(RG) (2.3 mg/kg, every 5 d). Body weight, glucose, insulin, cholesterol, and triglyceride levels were decreased after treatment with either compound. A glucose tolerance test (GTT) was also improved. Obese rhesus monkeys were treated with hrFGF21 (once a day) and Fc-FGF21(RG) (once a week) in a dose-escalation fashion. Doses started at 0.1 and 0.3 mg/kg and ended at 3 and 5 mg/kg for hrFGF21 and Fc-FGF21(RG), respectively. Doses were escalated every 2 wk, and animals were followed up for a washout period of 3 wk. Body weight, glucose, insulin, cholesterol, and triglyceride levels and the GTT profile were decreased to a greater extent with Fc-FGF21(RG) than with hrFGF21. The PK-PD relationship of Fc-FGF21(RG) exposure and triglyceride reduction was also conducted with a maximum response model. In conclusion, in more than one species, Fc-FGF21(RG) chronically administered once a week showed similar or greater efficacy than hrFGF21 administered daily.

Fundamentals of FGF19 & FGF21 action in vitro and in vivo

Fibroblast growth factors 19 (FGF19) and 21 (FGF21) have emerged as key regulators of energy metabolism. Several studies have been conducted to understand the mechanism of FGF19 and FGF21 action, however, the data presented has often been inconsistent and at times contradictory. Here in a single study we compare the mechanisms mediating FGF19/FGF21 actions, and how similarities/differences in actions at the cellular level between these two factors translate to common/divergent physiological outputs. Firstly, we show that in cell culture FGF19/FGF21 are very similar, however, key differences are still observed differentiating the two. In vitro we found that both FGF's activate FGFRs in the context of βKlotho (KLB) expression. Furthermore, both factors alter ERK phosphorylation and glucose uptake with comparable potency. Combination treatment of cells with both factors did not have additive effects and treatment with a competitive inhibitor, the FGF21 delta N17 mutant, also blocked FGF19's effects, suggestive of a shared receptor activation mechanism. The key differences between FGF21/FGF19 were noted at the receptor interaction level, specifically the unique ability of FGF19 to bind/signal directly via FGFR4. To determine if differential effects on energy homeostasis and hepatic mitogenicity exist we treated DIO and ob/ob mice with FGF19/FGF21. We find comparable efficacy of the two proteins to correct body weight and serum glucose in both DIO and ob/ob mice. Nevertheless, FGF21 and FGF19 had distinctly different effects on proliferation in the liver. Interestingly, in vivo blockade of FGF21 signaling in mice using ΔN17 caused profound changes in glycemia indicative of the critical role KLB and FGF21 play in the regulation of glucose homeostasis. Overall, our data demonstrate that while subtle differences exist in vitro the metabolic effects in vivo of FGF19/FGF21 are indistinguishable, supporting a shared mechanism of action for these two hormones in the regulation of energy balance.

Lack of overt FGF21 resistance in two mouse models of obesity and insulin resistance

Circulating levels of fibroblast growth factor 21 (FGF21), a metabolic regulator of glucose, lipid, and energy homeostasis, are elevated in obese diabetic subjects, raising questions about potential FGF21 resistance. Here we report tissue expression changes in FGF21 and its receptor components, and we describe the target-organ and whole-body responses to FGF21 in ob/ob and diet-induced obese (DIO) mice. Plasma FGF21 concentrations were elevated 8- and 16-fold in DIO and ob/ob mice, respectively, paralleling a dramatic increase in hepatic FGF21 mRNA expression. Concurrently, expression levels of βKlotho, FGF receptor (FGFR)-1c, and FGFR2c were markedly down-regulated in the white adipose tissues (WAT) of ob/ob and DIO mice. However, dose-response curves of recombinant human FGF21 (rhFGF21) stimulation of ERK phosphorylation in the liver and WAT were not right shifted in disease models, although the magnitude of induction in ERK phosphorylation was partially attenuated in DIO mice. Whole-body metabolic responses were preserved in ob/ob and DIO mice, with disease models being more sensitive and responsive than lean mice to the glucose-lowering and weight-loss effects of rhFGF21. Endogenous FGF21 levels, although elevated in diseased mice, were below the half-maximal effective concentrations of rhFGF21, suggesting a state of relative deficiency. Hepatic and WAT FGF21 mRNA expression levels declined after rhFGF21 treatment in the absence of the increased expression levels of βKlotho and FGFR. We conclude that overt FGF21 resistance was not evident in the disease models, and increased hepatic FGF21 expression as a result of local metabolic changes is likely a major cause of elevated circulating FGF21 levels.

Silica-chitosan hybrid coating on Ti for controlled release of growth factors

A hybrid material composed of a silica xerogel and chitosan was coated on Ti for the delivery of growth-factors. Fibroblast growth factor (FGF) and green fluorescence protein were incorporated into the coatings for hard tissue engineering. Silica was chosen as a coating material because of its high surface area as well as its good bioactivity. Chitosan provides mechanical stability and contributes to the control of the release rate of the growth factors. When the chitosan composition was 30% or more, the hybrid coating was stable physically and mechanically. The release of the growth-factors, observed in phosphate buffer solution at 37°C, was strongly dependent on the coating material. The hybrid coating containing FGF showed significantly improved osteoblast cell responses compared to the pure xerogel coating with FGF or the hybrid coating without FGF. These results indicate that the hybrid coating is potentially very useful in enhancing the bioactivity of metallic implants by delivering growth-factors in a controlled manner.

Hormone administration promotes the epithelium healing in patients with recurrent corneal epithelial exfoliation

PURPOSE

To investigate the effects of hormone administration upon epithelium healing in patients with recurrent corneal epithelial exfoliation.

METHODS

The recurrence rate of 56 patients with recurrent corneal epithelial exfoliation was compared after 3-month follow up, 30 patients of whom received the basic treatment of bFGF and pressure bandage plus prednisone administration (combination treatment group, ie. A) and the other 26 patients received the basic treatment alone (single treatment group, ie. B).

RESULTS

No patients showed recurrence in the combination treatment group. But there were 20 patients (76.92%) in the basic treatment group recurred. χ² test showed that χ²=35.9. The two groups had significant difference regarding the recurrence of corneal epithelial exfoliation (P<0.01).

CONCLUSION

For the patients with recurrent corneal epithelial exfoliation, hormone administration should be considered to reduce the recurrence and protect the function of cornea as a supplement to the basic treatment.

Bioactive scaffolds for engineering vascularized cardiac tissues

Functional vascularization is a key requirement for the development and function of most tissues, and most critically cardiac muscle. Rapid and irreversible loss of cardiomyocytes during cardiac infarction directly results from the lack of blood supply. Contractile cardiac grafts, engineered using cardiovascular cells in conjunction with biomaterial scaffolds, are an actively studied method for cardiac repair. In this article, we focus on biomaterial scaffolds designed to mediate the development and maturation of vascular networks, by immobilized growth factors. The interactive effects of multiple vasculogenic factors are discussed in the context of cardiac tissue engineering.

Obesity is a fibroblast growth factor 21 (FGF21)-resistant state

OBJECTIVE

Fibroblast growth factor 21 (FGF21) is a key mediator of fatty acid oxidation and lipid metabolism. Pharmacological doses of FGF21 improve glucose tolerance, lower serum free fatty acids, and lead to weight loss in obese mice. Surprisingly, however, FGF21 levels are elevated in obese ob/ob and db/db mice and correlate positively with BMI in humans. However, the expected beneficial effects of endogenous FGF21 to increase glucose tolerance and reduce circulating triglycerides are absent in obesity.

RESEARCH DESIGN AND METHODS

To test the hypothesis that obesity is a state of FGF21 resistance, we evaluated the response of obese mice to exogenous FGF21 administration. In doing this, we assessed the impact of diet-induced obesity on FGF21 signaling and resultant transcriptional events in the liver and white adipose tissue. We also analyzed the physiologic impact of FGF21 resistance by assessing serum parameters that are acutely regulated by FGF21.

RESULTS

When obese mice are treated with FGF21, they display both a significantly attenuated signaling response as assessed by extracellular mitogen-activated protein kinase 1 and 2 (ERK1/2) phosphorylation as well as an impaired induction of FGF21 target genes, including cFos and EGR1. These effects were seen in both liver and fat. Similarly, changes in serum parameters such as the decline in glucose and free fatty acids are attenuated in FGF21-treated DIO mice.

CONCLUSIONS

These data demonstrate that DIO mice have increased endogenous levels of FGF21 and respond poorly to exogenous FGF21. We therefore propose that obesity is an FGF21-resistant state.

Fibroblast growth factor 21 action in the brain increases energy expenditure and insulin sensitivity in obese rats

OBJECTIVE

The hormone fibroblast growth factor 21 (FGF21) exerts diverse, beneficial effects on energy balance and insulin sensitivity when administered systemically to rodents with diet-induced obesity (DIO). The current studies investigate whether central FGF21 treatment recapitulates these effects.

RESEARCH DESIGN AND METHODS

After preliminary dose-finding studies, either saline vehicle or recombinant human FGF21 (0.4 microg/day) was infused continuously for 2 weeks into the lateral cerebral ventricle of male Wistar rats rendered obese by high-fat feeding. Study end points included measures of energy balance (body weight, body composition, food intake, energy expenditure, and circulating and hepatic lipids) and glucose metabolism (insulin tolerance test, euglycemic-hyperinsulinemic clamp, and hepatic expression of genes involved in glucose metabolism).

RESULTS

Compared with vehicle, continuous intracerebroventricular infusion of FGF21 increased both food intake and energy expenditure in rats with DIO, such that neither body weight nor body composition was altered. Despite unchanged body fat content, rats treated with intracerebroventricular FGF21 displayed a robust increase of insulin sensitivity due to increased insulin-induced suppression of both hepatic glucose production and gluconeogenic gene expression, with no change of glucose utilization.

CONCLUSIONS

FGF21 action in the brain increases hepatic insulin sensitivity and metabolic rate in rats with DIO. These findings identify the central nervous system as a potentially important target for the beneficial effects of FGF21 in the treatment of diabetes and obesity.

FGF23 decreases renal NaPi-2a and NaPi-2c expression and induces hypophosphatemia in vivo predominantly via FGF receptor 1

Fibroblast growth factor-23 (FGF23) is a phosphaturic hormone that contributes to several hypophosphatemic disorders by reducing the expression of the type II sodium-phosphate cotransporters (NaPi-2a and NaPi-2c) in the kidney proximal tubule and by reducing serum 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] levels. The FGF receptor(s) mediating the hypophosphatemic action of FGF23 in vivo have remained elusive. In this study, we show that proximal tubules express FGFR1, -3, and -4 but not FGFR2 mRNA. To determine which of these three FGFRs mediates FGF23's hypophosphatemic actions, we characterized phosphate homeostasis in FGFR3(-/-) and FGFR4(-/-) null mice, and in conditional FGFR1(-/-) mice, with targeted deletion of FGFR1 expression in the metanephric mesenchyme. Basal serum phosphorus levels and renal cortical brush-border membrane (BBM) NaPi-2a and NaPi-2c expression were comparable between FGFR1(-/-), FGFR3(-/-), and FGFR4(-/-) mice and their wild-type counterparts. Administration of FGF23 to FGFR3(-/-) mice induced hypophosphatemia in these mice (8.0 +/- 0.4 vs. 5.4 +/- 0.3 mg/dl; p < or = 0.001) and a decrease in renal BBM NaPi-2a and NaPi-2c protein expression. Similarly, in FGFR4(-/-) mice, administration of FGF23 caused a small but significant decrease in serum phosphorus levels (8.7 +/- 0.3 vs. 7.6 +/- 0.4 mg/dl; p < or = 0.001) and in renal BBM NaPi-2a and NaPi-2c protein abundance. In contrast, injection of FGF23 into FGFR1(-/-) mice had no effects on serum phosphorus levels (5.6 +/- 0.3 vs. 5.2 +/- 0.5 mg/dl) or BBM NaPi-2a and NaPi-2c expression. These data show that FGFR1 is the predominant receptor for the hypophosphatemic action of FGF23 in vivo, with FGFR4 likely playing a minor role.

The core protein of growth plate perlecan binds FGF-18 and alters its mitogenic effect on chondrocytes

Fibroblast growth factor-18 (FGF-18) has been shown to regulate the growth plate chondrocyte proliferation, hypertrophy and cartilage vascularization necessary for endochondral ossification. The heparan sulfate proteoglycan perlecan is also critical for growth plate chondrocyte proliferation. FGF-18 null mice exhibit a skeletal dwarfism similar to that of perlecan null mice. Growth plate perlecan contains chondroitin sulfate (CS) and heparan sulfate (HS) chains and FGF-18 is known to bind to heparin and to heparan sulfate from some sources. We used cationic filtration and immunoprecipitation assays to investigate the binding of FGF-18 to perlecan purified from the growth plate and to recombinant perlecan domains expressed in COS-7 cells. FGF-18 bound to perlecan with a K(d) of 145 nM. Near saturation, approximately 103 molecules of FGF-18 bound per molecule of perlecan. At the lower concentrations used, FGF-18 bound with a K(d) of 27.8 nM. This binding was not significantly altered by chondroitinase nor heparitinase digestion of perlecan, but was substantially and significantly reduced by reduction and alkylation of the perlecan core protein. This indicates that the perlecan core protein (and not the CS nor HS chains) is involved in FGF-18 binding. FGF-18 bound equally to full-length perlecan purified from the growth plate and to recombinant domains I-III and III of perlecan. These data indicate that low affinity binding sites for FGF-18 are present in cysteine-rich regions of domain III of perlecan. FGF-18 stimulated 3H-thymidine incorporation in growth plate chondrocyte cultures derived from the lower and upper proliferating zones by 9- and 14-fold, respectively. The addition of perlecan reversed this increased incorporation in the lower proliferating chondrocytes by 74% and in the upper proliferating cells by 37%. These results suggest that perlecan can bind FGF-18 and alter the mitogenic effect of FGF-18 on growth plate chondrocytes.

The fasting polypeptide FGF21 can enter brain from blood

FGF21 recently has been proposed as a missing link in the biology of fasting, raising the question of whether it directly reaches the brain. We used multiple time-regression analysis to quantify the influx rate of this polypeptide across the blood-brain barrier (BBB), size-exclusion chromatography to examine degradation, capillary depletion to differentiate entry into brain parenchyma from retention in the microvasculature, and measurement of efflux rate to determine a possible confounding effect on measurement of entry. FGF21 was 94% intact in serum and 75% in brain 10 min after intravenous bolus delivery. Its influx rate was 0.23+/-0.12 microl/g-min, nearly four times faster than that of the vascular marker albumin. At 10 min, about 0.5% of the administered FGF21 was present in a gram of brain tissue. Of this, 70% reached the parenchyma of the brain. Co-injection of excess FGF21 failed to inhibit the influx, showing a lack of saturation. Efflux, which occurred at the same rate as the bulk reabsorption of cerebrospinal fluid, also was not saturable. In summary, FGF21 shows significant, non-saturable, unidirectional influx across the BBB.