Associations of Serum Levels of cGAMP in the Context of COVID-19 Infection, Atherosclerosis, Sterile Inflammation, and Functional Endothelial Biomarkers in Patients With Coronary Heart Disease and Healthy Volunteers

Abstract: Background: COVID-19 is associated with various changes in immunity, including signaling through the pattern-recognition receptors (PRR). However, the role of these processes is poorly understood. The present study aimed to evaluate the relationships of the serum levels of the cyclic dinucleotide 2’3’-cyclic GMP-AMP (cGAMP) marker of PRR activation with immunoglobulin G antibodies against severe acute respiratory syndrome-linked coronavirus (IgG-SARS)-positive status and endothelial dysfunction in apparently healthy subjects and in patients with coronary heart disease (CHD). Methods: The present study investigated selected groups from two cohorts, including cohort 1 of 307 healthy volunteers and cohort 2 of 218 CHD patients. COVID-19 infection was confirmed by the detection of IgG-SARS against SARS-CoV-2 S1 protein receptor-binding domain. Cohort 1 (24–69 years of age; 44.8 ± 8.6 years; 80.4% men) was examined for systematic coronary risk evaluation by European Society of Cardiology (SCORE) starting from 2019 before the onset of the COVID-19 pandemic. Cohort 2 (63±10.9 years of age, 54% men) was processed starting from 2017 (three years prior to the COVID-19 pandemic) in a hospital setting to undergo coronary angiography to assess coronary lesions as Gensini score. The levels of cGAMP and endothelial markers (nitrate and nitrite combined as NOx and endothelin-1) were assessed in the serum to evaluate the associations with IgG-SARS status, SCORE, and extent of coronary lesions by correlation and receiver operating characteristic (ROC) analyses. Results: Serum cGAMP did not discriminate between SARS-positive and SARS-negative healthy subject of cohort 1. Moreover, the level of cGAMP was not associated with endothelial biomarkers in healthy subjects. However, serum cGAMP was associated with atherosclerosis in cohort 2 in patients with CHD (area under the curve (AUC) 0.69; 95% CI 0.587-0.806; P=0.001), indicating that serum cGAMP was lower in patients with coronary stenosis compared to that in patients without coronary lesions. Conclusions: Low levels of serum cGAMP were associated with atherosclerosis and markers of endothelial dysfunction in patients with CHD. However, cGAMP was not associated with endothelial biomarkers or IgG-SASR immune status in healthy subjects, suggesting that cGAMP may be a new biomarker of coronary lesions in the context of sterile inflammation.