Quercetin alleviates Mycoplasma gallisepticum-induced inflammatory damage and oxidative stress through inhibition of TLR2/MyD88/NF-κB pathway in vivo and in vitro

Chronic respiratory disease (CRD) caused by Mycoplasma gallisepticum (MG) in chickens leads to enormous economic damage to the poultry industry yearly. The active components and mechanism of action of the traditional herbal remedy Ephedra houttuynia powder (EHP), which had been approved for clinical treatment against MG infection in China, remain unknown. In this study, the active components of EHP against MG were screened using a network pharmacological method, additionally, we studied the mechanism of action of the screened results (quercetin (QUE)). The findings demonstrated that QUE was an essential element of EHP against MG infection, effectively attenuating MG-induced oxidative stress and activation of the TLR2/MyD88/NF-κB pathway. Following QUE therapy, IL-1, IL-6, and TNF-α content and expression were downregulated, whereas IL-4 and IL-10 expression were upregulated, eventually suppressing the inflammatory response both in vitro and in vivo. Together, this study presents a strong rationale for using QUE as a therapeutic strategy to inhibit MG infection-induced inflammatory damage and oxidative stress.