Baicalein attenuates ovalbumin-induced allergic rhinitis through the activation of nuclear receptor subfamily 4 group a member 1.

Baicalein, one of the major active flavonoids found in Scutellaria baicalensis, has been revealed to exhibit potent anti-inflammatory properties in allergic airway inflammation. This study aimed to explore the role of baicalein and its relevant mechanism in the treatment of allergic rhinitis (AR). The bioinformatics tools were used to predict the targets of baicalein and AR-related genes. AR mice were induced by ovalbumin (OVA) and treated with lentivirus-encapsulated knockdown of nuclear receptor subfamily 4 group A member 1 (NR4A1) or protein arginine N-methyltransferase 1 (PRMT1) plasmids and baicalein. IL-4/IL-13-induced human nasal mucosal epithelial cells (HNEpC) were transfected with knockdown of NR4A1 or PRMT1 plasmids and baicalein treatment. Baicalein alleviated AR-like symptoms and reduced the levels of immunoglobulin E, histamine, and LTC4 in serum and IL-4, IL-25, and IL-33 concentrations in nasal lavage fluids of mice induced with OVA by increasing NR4A1 expression. NR4A1 blocked the NFκB/p65 pathway by mediating transcriptional repression of PRMT1. Knockdown of PRMT1 overturned the effects of NR4A1 knockdown on IL-4/IL-13-induced HNEpC and OVA-induced mice. Collectively, these findings provide evidence that baicalein activation of NR4A1 mediates transcriptional repression of PRMT1 and relieves AR in mice by blocking the NFκB/p65 pathway.