Klotho regulates myocardial function in living human slices and cardiorenal phenotype in Klotho-deficient swine model
I Ornek, L Wang, C dAlessio, J Hamers, A Dendorfer, E Wolf, E Kemter, D Reichart, M Heinig, P Sen, D MerkusAbstract
Background
Cardiorenal syndrome is an increasing burden in older adults, and early cardiac involvement often includes coronary microvascular dysfunction contributing to heart failure. Klotho is a kidney-derived factor that declines with age and is linked to increased cardiovascular risk, yet its role in early cardiorenal dysfunction and the benefit of Klotho restoration remain unclear.
Purpose
To explore the role of Klotho in cardiorenal syndrome using a Klotho deficient swine model and to test soluble Klotho (sKl) effects in failing human myocardium
Methods
Explanted left ventricular (LV) slices from 8 patients with elevated BNP and frequent renal dysfunction (GFR <60 mL/min in 75% of patients) were cultured in biomimetic chambers under continuous electromechanical stimulation and treated with 3.4 mM sKl for 2 weeks. Contractile kinetics and calcium handling were assessed by time-to-peak contraction and post-pause potentiation. NanoString pathway profiling was done in 5 human samples, selected targets validated by qRT-PCR. 9-month-old α-Klotho haploinsufficient swine (Kl⁺/⁻) and wild-type controls underwent echocardiography, PV-loop analysis, and coronary flow reserve measurements. Cardiac and renal tissues were analyzed for fibrosis and oxidative stress (8-hydroxy-2′-deoxyguanosine). Single-nuc transcriptomics was performed on LV subendocardial tissue.
Results
Slices from explanted heart showed prolonged time-to-peak during 2 weeks culture, whereas those treated with sKl preserved contractile kinetics and enhanced post-pause potentiation, indicating improved calcium handling (Fig1A&B). NanoString analysis revealed sKl modulates extracellular matrix (ECM), oxidative stress response, and angiotensin signaling pathways, supported by decreased MMP9 and AGTR1 and increased α-SMA and COL1A1 expression (Fig1C-D). Under H2O2-induced oxidative stress, sKl improved post-pause potentiation and showed a trend toward increased force, and reduced GPX3 expression toward control levels (Fig1F&G). In vivo, novel Kl⁺/⁻ swine model showed reduced E/A ratio, and coronary flow reserve, indicating diastolic and microvascular dysfunction and increased LV diastolic/systolic diameter showed dilated LV in swine (Fig2A-D). Single-nuc sequencing showed downregulation of FGFR1 in cardiomyocytes and reduced ICAM1/VCAM1 expression in endothelial cells, suggesting a coordinated impairment in Klotho–FGF signaling and vascular integrity (Fig2E-G).
Conclusion
sKl preserves contractile kinetics and improves calcium handling in failing human myocardium while regulating pathways related to extracellular matrix organization, oxidative stress responses, and angiotensin signaling. Complimentary in vivo findings in Kl+/− swine, link Klotho deficiency to diastolic dysfunction, microvascular impairment, and cardiorenal pathology, supporting the Klotho axis as promising target in cardiorenal disease.figure1figure2