Inflammatory Biomarkers in the Assessment of Kidney Function Decline in Long COVID Syndrome

Long COVID (LC) is an inflammatory condition, affecting multiple organs, including kidneys. This study aims to identify a signature of inflammatory biomarkers that can predict, describe, and monitor kidney function decline in LC patients.

A single-center observational study was carried out at the COVID Center of University of Campania "L. Vanvitelli." Patients who survived the acute phase were invited for a follow-up visit at least 12 months after discharge. Based on the estimated glomerular filtration rate (eGFR), patients were categorized in three groups: group 1: eGFR >90 mL/min × 1.73 m2, group 2: eGFR 30-89 mL/min × 1.73 m2, and group 3: eGFR <30 mL/min × 1.73 m2. The multiplex ELLA platform was employed to quantify serum levels of inflammatory biomarkers including IL-6, IL-17, IL-10, IL-1β, PTX3, TNF-α, VCAM-1, ICAM-1, and E-selectin. Associations between each biomarker level and eGFR were analyzed.

A decline in the eGFR at follow-up compared to that at admission was observed. IL-6 levels increased significantly as the eGFR decreased across the groups. IL-17, IL-10, and VCAM1 levels were markedly elevated in group 3.

According to our results, IL-6, IL-17, IL-10, and VCAM1 constitute a biomarker signature associated with poorer renal prognosis in LC patients. The rise in IL-6 could drive an increase in IL-17, IL-10, and VCAM1, contributing to kidney function decline. These findings may help establish a clinical and laboratory framework to predict chronic kidney disease risk in LC. Furthermore, ELLA platform appears as a useful tool for inflammatory biomarker quantification in the clinical setting.