Fibroblast growth factor-23 and the risk of cardiovascular diseases and mortality in the general population: A systematic review and dose-response meta-analysis

Fibroblast Growth Factors in Cardiovascular Disease

Despite advancements in managing traditional cardiovascular risk factors, many cardiovascular diseases (CVDs) persist. Fibroblast growth factors (FGFs) have emerged as potential diagnostic markers and therapeutic targets for CVDs. FGF1, FGF2, and FGF4 are primarily used for therapeutic angiogenesis. Clinical applications are being explored based on animal studies using approaches such as recombinant protein administration and adenovirus-mediated gene delivery, targeting patients with coronary artery disease and lower extremity arterial disease. Although promising results have been observed in animal models and early-stage clinical trials, further studies are required to assess their therapeutic potential. The FGF19 subfamily, consisting of FGF19, FGF21, and FGF23, act via endocrine signaling in various organs. FGF19, primarily expressed in the small intestine, plays important roles in glucose, lipid, and bile acid metabolism and has therapeutic potential for metabolic disorders. FGF21, found in various tissues, improves glucose metabolism and insulin sensitivity, suggesting potential for treating obesity and diabetes. FGF23, primarily secreted by osteocytes, regulates vitamin D and phosphate metabolism and serves as an important biomarker for chronic kidney disease and CVDs. Thus, FGFs holds promise for both therapeutic and diagnostic applications in metabolic and cardiovascular diseases. Understanding the mechanisms of FGF may pave the way for novel strategies to prevent and manage CVDs, potentially addressing the limitations of current treatments. This review explores the roles of FGF1, FGF2, FGF4, and the FGF19 subfamily in maintaining cardiovascular health. Further research and clinical trials are crucial to fully understand the therapeutic potential of FGFs in managing cardiovascular health.

Cardiovascular health in pediatric patients with X-linked hypophosphatemia under two years of burosumab therapy

Introduction

X-linked hypophosphatemia (XLH) is caused by an inactivating mutation in the phosphate-regulating endopeptidase X-linked (PHEX) gene whose defective product fails to control phosphatonin fibroblast growth factor 23 (FGF23) serum levels. Although elevated FGF23 levels have been linked with detrimental cardiac effects, the cardiologic outcomes in XLH patients have been subject to debate. Our study aimed to evaluate the prevalence and severity of cardiovascular morbidity in pediatric XLH patients before, during, and after a 2-year treatment period with burosumab, a recombinant anti-FGF23 antibody.

Methods

This prospective observational study was conducted in a tertiary medical center, and included 13 individuals with XLH (age range 0.6-16.2 years) who received burosumab every 2 weeks. Clinical assessment at treatment initiation and after .5, 1, and 2 years of uninterrupted treatment included anthropometric measurements and cardiologic evaluations (blood pressure [BP], electrocardiogram, conventional echocardiography, and myocardial strain imaging).

Results

The linear growth of all patients improved significantly (mean height z-score: from -1.70 ± 0.80 to -0.96 ± 1.08, P=0.03). Other favorable effects were decline in overweight/obesity rates (from 46.2% to 23.1%) and decreased rates of elevated BP (systolic BP from 38.5% to 15.4%; diastolic BP from 38.5% to 23.1%). Electrocardiograms revealed no significant abnormality throughout the study period. Cardiac dimensions and myocardial strain parameters were within the normative range for age at baseline and remained unchanged during the study period.

Conclusion

Cardiologic evaluations provided reassurance that 2 years of burosumab therapy did not cause cardiac morbidity. The beneficial effect of this treatment was a reduction in cardiovascular risk factors, as evidenced by the lower prevalence of both overweight/obesity and elevated BP.

Non-Classical Effects of FGF23: Molecular and Clinical Features

This article reviews the role of fibroblast growth factor 23 (FGF23) protein in phosphate metabolism, highlighting its regulation of vitamin D, parathyroid hormone, and bone metabolism. Although it was traditionally thought that phosphate-calcium homeostasis was controlled exclusively by parathyroid hormone (PTH) and calcitriol, pathophysiological studies revealed the influence of FGF23. This protein, expressed mainly in bone, inhibits the renal reabsorption of phosphate and calcitriol formation, mediated by the α-klotho co-receptor. In addition to its role in phosphate metabolism, FGF23 exhibits pleiotropic effects in non-renal systems such as the cardiovascular, immune, and metabolic systems, including the regulation of gene expression and cardiac fibrosis. Although it has been proposed as a biomarker and therapeutic target, the inhibition of FGF23 poses challenges due to its potential side effects. However, the approval of drugs such as burosumab represents a milestone in the treatment of FGF23-related diseases.

Fibroblast growth factor 23 independently predicts adverse outcomes after an acute coronary syndrome

AIMS

Abnormalities of mineral metabolism (MM) have been related to cardiovascular disorders. There are no reports on the prognostic role of MM after an acute coronary syndrome (ACS). We aim to assess the prognostic role of MM after an ACS.

METHODS AND RESULTS

Plasma levels of components of MM [fibroblast growth factor 23 (FGF23), calcidiol, parathormone, klotho, and phosphate], high-sensitivity C-reactive protein, and N-terminal-pro-brain natriuretic peptide were measured in 1190 patients at discharge from an ACS. The primary outcome was a combination of acute ischaemic events, heart failure (HF) and death. Secondary outcomes were the separate components of the primary outcome. Age was 61.7 ± 12.2 years, and 77.1% were men. Median follow-up was 5.44 (3.03-7.46) years. Two hundred and ninety-four patients developed the primary outcome. At multivariable analysis FGF23 (hazard ratio, HR 1.18 [1.08-1.29], P < 0.001), calcidiol (HR 0.86 [0.74-1.00], P = 0.046), previous coronary or cerebrovascular disease, and hypertension were independent predictors of the primary outcome. The predictive power of FGF23 was homogeneous across different subgroups of population. FGF23 (HR 1.45 [1.28-1.65], P < 0.001) and parathormone (HR 1.06 1.01-1.12]; P = 0.032) resulted as independent predictors of HF. FGF23 (HR 1.21 [1.07-1.37], P = 0.002) and calcidiol (HR 0.72 [0.54-0.97), P = 0.028) were independent predictors of death. No biomarker predicted acute ischaemic events. FGF23 predicted independently the primary outcome in patients with estimated glomerular filtration rate > 60 mL/min/1.73 m2 .

CONCLUSIONS

FGF23 and other components of MM are independent predictors of HF and death after an ACS. This effect is homogeneous across different subgroups of population, and it is not limited to patients with chronic kidney disease.

FGF23 and klotho at the intersection of kidney and cardiovascular disease

Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD). As CKD progresses, CKD-specific risk factors, such as disordered mineral homeostasis, amplify traditional cardiovascular risk factors. Fibroblast growth factor 23 (FGF23) regulates mineral homeostasis by activating complexes of FGF receptors and transmembrane klotho co-receptors. A soluble form of klotho also acts as a 'portable' FGF23 co-receptor in tissues that do not express klotho. In progressive CKD, rising circulating FGF23 levels in combination with decreasing kidney expression of klotho results in klotho-independent effects of FGF23 on the heart that promote left ventricular hypertrophy, heart failure, atrial fibrillation and death. Emerging data suggest that soluble klotho might mitigate some of these effects via several candidate mechanisms. More research is needed to investigate FGF23 excess and klotho deficiency in specific cardiovascular complications of CKD, but the pathophysiological primacy of FGF23 excess versus klotho deficiency might never be precisely resolved, given the entangled feedback loops that they share. Therefore, randomized trials should prioritize clinical practicality over scientific certainty by targeting disordered mineral homeostasis holistically in an effort to improve cardiovascular outcomes in patients with CKD.