Vascular remodelling in a mouse model of heart failure with preserved ejection fraction.

Heart failure (HF) with preserved ejection fraction (HFpEF) is a complex syndrome characterized by symptoms of HF despite normal left ventricular function. It now accounts for >50% of all HF cases, with the only effective treatment (morbidity benefit) so far being sodium-glucose co-transporter-2 inhibitors, finerenone and tirzepatide. Recently, vascular dysfunction has been highlighted as one of the main pathophysiological mechanisms of HFpEF. Recently, a 'two-hit' experimental model of HFpEF was described in which mice fed a high-fat diet (HFD) and l-NAME developed a phenotype that mimics human HFpEF. We further characterize this model by assessing vascular remodelling in the aorta, carotid and femoral arteries. C57BL/6N mice aged 11-12 weeks were fed a HFD and water supplemented with l-NAME 1.5 g/L for 15 weeks. These mice manifested increased body weight and blood pressure, glucose and exercise intolerance, and cardiac structural and functional alterations consistent with HFpEF. Morphometric analyses were performed in the aorta, carotid and femoral arteries, revealing increased media thickness and media-to-lumen ratios. Moreover, we detected evidence of fibrosis in the middle layer of the aorta. A correlation between increased aortic remodelling and fibrosis with diastolic dysfunction was observed. Vascular reactivity studies using wire myography uncovered impaired vasoconstriction and vasodilatation responses, suggesting aortic stiffness. We also detected the presence of a senescence-like phenotype in the aortic wall. Together, these data offer valuable contributions to understanding the vascular mechanisms underlying HFpEF. KEY POINTS: Heart failure with preserved ejection fraction (HFpEF) represents >50% of heart failure patients. Despite its growing prevalence, the aetiology of HFpEF continues to be incompletely understood, mainly due to the lack of reliable animal models. An HFpEF mouse model, obtained by feeding mice a high-fat diet and exposing them to l-NAME, reproduces the majority of the clinical features observed in HFpEF patients. Possible vascular alterations elicited by this model remain unknown. Here, we report that HFpEF mice manifest aortic, carotid and femoral artery remodelling. The aorta also harboured fibrosis plus impaired vasodilatation and vasoconstriction responses. Aortic remodelling and fibrosis correlated with diastolic dysfunction. The aorta from HFpEF mice harboured increased p53, IL-6 and VCAM-1 protein levels, suggesting a senescence-like phenotype. These data reveal that this HFpEF mouse model displays vascular alterations similar to those reported in HFpEF patients. These findings unveil novel insights into the vascular remodelling of HFpEF and, furthermore, validate a reliable animal model that can be used to study HFpEF aetiology and potentially develop future therapeutic approaches.