Quercetin alleviates inflammation induced by porcine reproductive and respiratory syndrome virus in MARC-145 cells through the regulation of arachidonic acid and glutamine metabolism

Abstract Porcine reproductive and respiratory syndrome virus (PRRSV) infection causes severe inflammatory response and respiratory disease. Quercetin is among the widely occurring polyphenol, found abundantly in nature. Quercetin has anti-inflammatory, anti-oxidative and anti-viral properties. This study aimed to explore the effect and mechanism of quercetin on PRRSV induced inflammation in MARC-145 cells. Observing the cytopathic effect and measurements of inflammatory markers in MARC-145 cells collectively demonstrate that quercetin elicits a curative effect on PRRSV-induced inflammation. Liquid chromatography–mass spectrometry was further used for a non-targeted metabolic analysis of the the role of quercetin in the metabolic regulation of PRRSV inflammation in MARC-145 cells. It was shown that quercetin attenuated PRRSV-induced cytopathy in MARC-145 cells. We also found that quercetin inhibited PRRSV-induced mRNA expression of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6). Metabolomics analysis revealed that quercetin ameliorated PRRSV-induced inflammation. Pathway analysis results revealed that PRRSV-induced pathways including arachidonic acid metabolism, linoleic acid metabolism, glycerophospholipid metabolism, and alanine, aspartate, and glutamate metabolism were suppressed by quercetin. Moreover, we confirmed that quercetin inhibited the activation of NF-κB/p65 pathway, probably by attenuating PLA2, LOX and COX mRNA expression. These results provide a crucial insight into the molecular mechanism of quercetin in alleviating PRRSV-induced inflammation.