Recombinant Klotho administration after myocardial infarction reduces ischaemic injury and arrhythmias by blocking intracellular calcium mishandling and CaMKII activation.

Ischaemic heart disease (IHD) remains a major cause of death and morbidity. Klotho is a well-known anti-ageing factor with relevant cardioprotective actions, at least when renal dysfunction is present, but its actions are much less known when renal function is preserved. This study investigated Klotho as a biomarker and potential novel treatment of IHD-associated complications after myocardial infarction (MI) under preserved renal function. Association between circulating Klotho levels and cardiac injury was investigated in patients after ST-elevation MI (STEMI). Biochemical, in vivo and in vitro cardiac function and histological and molecular studies were performed to determine the effect of recombinant Klotho in the failing hearts of mice after MI. We demonstrated that STEMI patients showed lower systemic Klotho levels, with the lowest Klotho tertile in those patients with higher N-terminal pro B-type natriuretic peptide (NT-proBNP) levels. Mice also showed a decrease in systemic Klotho levels after MI induction. Furthermore, recombinant Klotho administration in mice reduced infarct area and attenuated cardiac hypertrophy and fibrosis. We also demonstrated that Klotho treatment prevented reduction in ejection fraction and MI-related ECG changes, including prolonged QRS, JT, QTc, and T