Pericyte loss initiates microvascular dysfunction in the development of diastolic dysfunction
Microvascular dysfunction has been proposed to drive heart failure with preserved ejection fraction (HFpEF), but the initiating molecular and cellular events are largely unknown. Our objective was to determine when microvascular alterations in HFpEF begin, how they contribute to disease progression, and how pericyte dysfunction plays a role herein. We aimed to assess microvascular dysfunction with respect to the development of cardiac dysfunction, in the Zucker fatty and spontaneously hypertensive (ZSF1) obese rat model of HFpEF at three time points: 6, 14, and 21 weeks of age. We found that pericyte loss was the earliest and strongest microvascular change, occurring before prominent echocardiographic signs of diastolic dysfunction were present. Pericytes were shown to be less proliferative and had a disrupted morphology at 14 weeks in the obese ZSF1 animals, who also exhibited an increased capillary luminal diameter and disrupted endothelial junctions. Pericytes exposed to oxidative stress in vitro showed downregulation of cell cycle associated pathways, and induced a pro-inflammatory state in endothelial cells upon co-culture. We propose pericytes are important for maintaining endothelial cell function, where loss of pericytes enhances the reactivity of endothelial cells to inflammatory signals and promotes microvascular dysfunction, thereby accelerating the development of HFpEF. Overall design: To identify the underlying mechanisms of pericyte dysfunction, we exposed human immortalised pericytes to oxidative stress for 24h and compared their gene expression profile to non-treated cells. DEG analysis erroneously used oxidative stress (OX) as control condition and non-oxidative stress (NOX) as experimental condition.