Exerkine dysregulation links visceral adiposity to skeletal muscle impairment in end-stage heart failure with reduced ejection fraction: proteomic evidence for a cardio-adipose-muscle axis.
BACKGROUND: Heart failure with reduced ejection fraction (HFrEF) is associated with profound alterations in body composition, skeletal muscle dysfunction, and impaired exercise capacity. Exerkines representing exercise-responsive signaling molecules released by skeletal muscle, adipose tissue, and other organs may mediate systemic metabolic communication between tissues. However, their role in advanced HFrEF and their relationship with adiposity and skeletal muscle characteristics remain poorly understood. METHODS: We studied 73 patients with end-stage HFrEF and 16 healthy controls. Body composition was assessed using computed tomography, including visceral (VAT), subcutaneous (SAT), and epicardial adipose tissue (EAT), as well as skeletal muscle quantity (psoas muscle index, PMI) and quality (psoas muscle density, PMD). Functional performance was evaluated using handgrip strength (HGT) and the 6-min walk test (6MWT). Circulating exerkines were quantified using the Olink technology. Associations between proteins and clinical variables were assessed using age- and creatinine-adjusted linear models with false discovery rate correction. RESULTS: Among patients with HFrEF, 36% were obese and 38% exhibited central obesity independent of BMI. Muscle strength and muscle quality were strongly associated with functional capacity. VAT correlated with muscle mass but not with muscle quality or performance. Compared with controls, HFrEF patients demonstrated elevated inflammatory and metabolic stress-related exerkines including CXCL8, CCL2, IL-6, TNF, IL-15, GDF15, FGF21, ANGPTL4, CTSB, DCN, and resistin. In contrast, proteins associated with muscle integrity and regenerative signaling (myostatin, BDNF, IL-7, SPARC) were significantly reduced. In HFrEF patients leptin strongly correlated with adiposity measures. Metabolic stress mediators (GDF15, IL-15, FGF21, CTSB) were inversely associated with muscle quality and functional performance, whereas myostatin positively correlated with muscle quality, strength, and exercise capacity. BDNF was inversely associated with frailty. CONCLUSIONS: Advanced HFrEF is characterized by a dysregulated exerkine network linking adiposity, skeletal muscle quality, and functional performance. Four biologically coherent axes were identified: a leptin-driven adiposity axis, a metabolic stress-muscle quality axis, a myostatin-related muscle function axis, and a neurotrophic frailty axis. These findings support the presence of a systemic cardio-adipose-muscle signaling network in end-stage HFrEF and identify candidate molecular mediators of sarcopenia and functional decline.