Mineralocorticoid receptor-antagonism prevents COVID-19-dependent glycocalyx damage

Abstract

Proinflammatory cytokines target vascular endothelial cells during COVID-19 infections. In particular, the endothelial glycocalyx (eGC), a proteoglycan-rich layer on top of endothelial cells, was identified as a vulnerable, vasoprotective structure during infections. Thus, eGC damage can be seen as a hallmark in the development of endothelial dysfunction and inflammatory processes. Using sera derived from patients suffering from COVID-19, we could demonstrate that the eGC became progressively worse in relation to disease severity (mild vs severe course) and in correlation to IL-6 levels. This could be prevented by administering low doses of spironolactone, a well-known and highly specific aldosterone receptor antagonist. Our results confirm that SARS-CoV-2 infections cause eGC damage and endothelial dysfunction and we outline the underlying mechanisms and suggest potential therapeutic options.

Fig. 1

COVID-19 (C19) sera treatment damages the endothelial glycocalyx (eGC). A Endothelial cells were incubated with 10% sera from C19 patients with mild symptoms (patients 21–59) for 24 h. Analysis of the eGC by atomic force microscopy showed eGC damage with a reduced eGC height in a range of 81.6 nm to 130.1 nm compared to 220.7 nm of the control group (N = 3, n = 5–6; **** (all patients) p < 0.0001 vs. control). B Sera from a second patient cohort with severe SARS-CoV-2 infection and mandatory intensive care (patients 14–37) were incubated with endothelial cells for 24 h. Here, eGC height was further damaged, reducing eGC height in a range of 57.7 nm to 90.1 nm compared to 175.6 nm under control conditions (N = 3, n = 3–5; ** (all patients) p < 0.01 vs. control). C Average eGC height of control, C19 mild, and C19 severe are shown. C19 treatment leads to a reduction in eGC height by 48.9 and 60.8% compared to control in C19 mild and C19 severe, respectively (N = 3, n = 9–12, ****p < 0.0001). D IL-6 levels in mild and severe C19 patients were analyzed. In C19 patients, IL-6 increases compared to the healthy control reference level (7 ng/L). IL-6 was significantly higher in severe than in mild C19 samples

Fig. 2

Treatment with spironolactone attenuates COVID-19 (C19)-induced endothelial glycocalyx (eGC) damage. A Sera from COVID-19 patients (mild course) were pooled and used for 24 h stimulation (10%) on endothelial cells. Treatment with C19 sera damaged the eGC and reduced height by 46% compared to treatment with healthy control sera. Coincubation with spironolactone strongly diminished the detrimental COVID-19 effect on eGC height within the C19-treated group (N = 3, n = 4–8; ****p < 0.0001). B Exemplary WGA stainings of HUVECs treated with 10% control or C19 sera with and without additional spironolactone incubation (100 nM). C WGA stainings were used to validate atomic force microscope measurements. Reduced eGC height in C19-treated cells was confirmed by decreased WGA fluorescence intensity compared to the control group. Spironolactone treatment strongly attenuated this effect (N = 3, n = 3–4, *p < 0.05, ****p < 0.0001)