THE ROLE OF JNK IN THE PROINFLAMMATORY ACTION OF THE SARS-CoV-2 PROTEIN ORF3a

Abstract

Introduction: Coronavirus disease 2019 (COVID-19) is a contagious respiratory infection caused by the novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A significant contributor to the pathogenesis of COVID-19 is the SARS-CoV-2 regulatory protein open reading frame 3a (ORF3a), which drives an excessive inflammatory response associated with adverse clinical outcomes and mortality. Notably, c-Jun N-terminal kinase (JNK), a part of the mitogen-activated protein kinase (MAPK) family, is essential in orchestrating the cellular innate and adaptive immune response initiated by diverse viral infections.

Aim: This study aims to elucidate the involvement of JNK in the proinflammatory response induced by SARS-CoV-2 ORF3a in the H460 non-small cell lung cancer cell line, specifically focusing on the expression of proinflammatory cytokines IL-1β and IL-8.

Material and Methods: The H460 cell line was transfected with a DNA plasmid encoding the SARS-CoV-2 ORF3a. Pharmacological inhibition of JNK in H460 cells was achieved using JNK inhibitor SP600215. The expression of p-JNK and JNK was confirmed by immunoblotting, while RT-qPCR was used to quantify IL-1β and IL-8 mRNA levels. Student's t-test was used for statistical analysis.

Results: H460 cells expressing SARS-CoV-2 ORF3a displayed a significant increase in JNK phosphorylation and IL-1β and IL-8 mRNA levels, as verified by immunoblot analysis and RT-qPCR respectively (p <0.05). Subsequently, JNK inhibition in SARS-CoV-2 ORF3a -expressing cells resulted in a significant reduction of IL-1β and IL-8 mRNA expression (p <0.05), thus confirming its involvement in the proinflammatory response elicited by SARS-CoV-2 ORF3a.

Conclusion: The results of our study demonstrated that JNK plays a crucial role in the expression of proinflammatory cytokines IL-1β and IL-8 triggered by SARS-CoV-2 ORF3a. Therefore, targeted JNK inhibition holds promise for mitigating SARS-CoV-2 ORF3a-driven inflammation and providing innovative treatment alternatives for severe COVID-19 cases.