SARS-CoV-2 Spike S1 subunit triggers pericyte and microvascular dysfunction in human pancreatic islets

The COVID-19 pandemic has profoundly affected human health, yet the mechanisms underlying its impact on metabolic and vascular systems remain incompletely understood. Clinical evidence suggests that SARS-CoV-2 directly disrupts vascular homeostasis, with perfusion abnormalities observed in various tissues. The pancreatic islet, a key endocrine mini-organ reliant on its microvasculature for optimal function, may be particularly vulnerable. Studies have proposed a link between SARS-CoV-2 infection and islet dysfunction, but the mechanisms remain unclear. Here, we investigated how SARS-CoV-2 spike S1 protein affects human islet microvascular function. Using confocal microscopy and living pancreas slices from non-diabetic organ donors, we show that a SARS-CoV-2 spike S1 recombinant protein activates pericytes — key regulators of islet capillary diameter and beta cell function—and induces capillary constriction. These effects are driven by a loss of angiotensin-converting enzyme 2 (ACE2) from pericytes’ plasma membrane, impairing ACE2 activity and increasing local angiotensin II levels. Our findings highlight islet pericyte dysfunction as a potential contributor to the diabetogenic effects of SARS-CoV-2 and offer new insights into the mechanisms linking COVID-19, vascular dysfunction and diabetes.