Quercetin alleviates LPS-induced inflammatory response in dairy cow lamellar keratinocytes through PI3K/Akt/NF-κB signaling pathway

Dairy cow laminitis causes severe economic losses and animal welfare issues in dairy farms globally. Current clinical interventions for laminitis remain limited in terms of safety and efficacy, which poses significant challenges to pasture-based productivity. Previous studies demonstrated that the activation of PI3K/Akt and NF-κB signaling pathways is a crucial mechanism promoting inflammatory damage and lamellar tissue degradation, providing potential targets for the development of novel therapeutic agents for treating dairy cow laminitis. Quercetin, an accessible and inexpensive flavonoid, exhibits diverse biological activities, including anti-inflammatory, antioxidant, and metabolic-modulatory effects. The present study aimed to elucidate the anti-inflammatory mechanism of quercetin in LPS-induced inflammatory response in dairy cow lamellar keratinocytes. Our results showed that quercetin at a concentration of 25 µM effectively downregulated the mRNA expression of inflammatory factors, including TNF-α, IL-6, IL-1β, CXCL-1, CXCL-6, COX-2, and iNOS in association with elevated expression of IL-10. Concurrently, quercetin inhibited the activation of the PI3K/Akt and NF-κB signaling pathways. Further experiments demonstrated that co-treatment with ammonium pyrrolidinedithiocarbamate (PDTC, an NF-κB inhibitor) significantly potentiated the inhibitory effect of quercetin on the protein expression of p-IκBα and p-p65. This result confirmed that quercetin exerts its anti-inflammatory effect by targeting and modulating the NF-κB signaling pathway. Additionally, Akt overexpression markedly alleviated quercetin-induced suppression of both p-IκBα/p-p65 protein expression and the mRNA transcription of downstream pro-inflammatory factors (TNF-α, IL-6, and IL-1β) but further increased quercetin-enhanced IL-10 expression. In contrast, combined Akt silencing and quercetin treatment further reduces the activation of the NF-κB signaling pathway. In conclusion, our findings demonstrate that quercetin alleviates the inflammatory response in LPS-induced dairy cow lamellar keratinocytes by modulating the PI3K/Akt/NF-κB signaling pathway. This study provides experimental evidence for the potential application of quercetin in the prevention and treatment of dairy cow laminitis.