Up Up-regulation of Soluble Programmed Death Ligand 1 (PD L1) Level as a Potential COVID-19 Severity-Associated Bio-parameter

Abstract

Programmed cell death protein 1 (PD-1) may be in a position to interact hydrophobically with the spike glycoprotein or its epitopes of SARS-CoV-2, which, in addition to the neuroinvasive capability it possesses, triggers hyperactivation of the Program Death Ligand1.  A case-control study (67 COVID-19 patients and 23 healthy controls) was conducted to detect the role of soluble Program Death-Ligand1 (sPDL-1). The sPD-L1 serum concentrations were measured with an ELISA kit, while the SARS-CoV-2 infection was determined earlier via a real-time PCR evaluation kit. The findings demonstrated that median sPD-L1 levels in patients were substantially more significant compared to healthy controls (1349 vs. 737.8 pg/ml; p < 0.0001). Most patients were considered high producers of sPD-L1 (> median=990.8 pg/ml) compared to controls (65.7%; p=0.001). Receiver operating characteristic curve analysis indicated that an sPDL-1 level of more than 887.6 pg/ml distinguishes patients from control (area under the curve = 0.831; p < 0.0001) and is considered an excellent indicator that distinguishes patients with different severity at risk (area under the curve = 0.91; p < 0.0001). The sPD-L1 levels showed a significant relationship with the severity of infection by COVID-19 (p < 0.0001), which were significantly increased with C-reactive protein (CRP) (p = 0.021) and Ferritin levels, making both of them a promising prognostic marker for infection progress. The sPD-L1 had a crucial role in the progression of infection along with SARS-CoV-2 wild type and their variants, and future studies are required to inhibit sPD-L1 based-interferons expression.