Silva, Andreia

Abstract Aims Heart failure with preserved ejection fraction (HFpEF) is one of the most common forms of heart failure with no effective treatment. While chronic systemic inflammation, triggered by comorbidities, is a critical factor of HFpEF pathophysiology and a relevant target for therapy, mechanisms underlying inflammation remain poorly understood. Here, we aim to understand the upstream mechanisms driving inflammation, including immune dysregulation and cellular senescence. Methods and results ZSF1-Obese rats, a cardiometabolic model of HFpEF, were used to investigate systemic and cardiac inflammation, and to characterise the senescent program in immune, circulating endothelial and cardiac cells, before disease onset and onward. Using patient samples, we further evaluated the association between cellular senescence and diagnostic and prognostic markers of HFpEF. Finally, we administered a senolytic - Navitoclax - at two time-points, before and after the appearance of HFpEF. Conclusion ZSF1-Obese rats had increased immune and endothelial senescent cells in their peripheral blood and myocardium, together with exacerbated systemic inflammation and endothelial damage, compared to control ZSF1-Lean rats. Moreover, increased circulating senescent leucocytes were associated with markers of disease severity in patients with HFpEF. Senescent cell clearance decreased circulating B-type natriuretic peptide levels and attenuated inflammation, vascular remodelling, and cardiac fibrosis. Additionally, it improved renal function and reduced pulmonary oedema. Our findings suggest that senotherapeutics may improve the treatment for HFpEF by attenuating systemic effects of the disease whilst reducing cardiac fibrosis and endothelial rarefaction.

ABSTRACT The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell‐released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV‐associated functional activities. Finally, a checklist is provided with summaries of key points.