Luteolin Ameliorates Allergic Rhinitis in Mice through Modulating T Cell Subset Imbalance, Endoplasmic Reticulum Stress, and NLRP3 Inflammasome Axes

Luteolin (LO) possesses pharmacological benefits like anti-inflammatory, antioxidant, and immune-boosting properties. This study aims to clarify the effect of LO on allergic rhinitis (AR) and its mechanisms and provide new insights for the clinical application of LO. A mouse model for AR was developed through ovalbumin (OVA) stimulation. AR mice were gavaged with saline, low, medium, and high concentrations of LO, and montelukast. Nasal symptoms and scores were evaluated. The levels of OVA-specific immunoglobulins (OVA-sIgs), T helper cells (Th1, Th2, Th17), regulatory T cells (Tregs) cytokines, along with proinflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA). Histopathological alterations were observed utilizing hematoxylin-eosin staining. Interleukin (IL)-1β and IL-18 levels were assessed through immunohistochemistry. Flow cytometry measured the percentage of T lymphocytes. The levels of endoplasmic reticulum stress (ERS)-related and NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-related mRNAs and proteins were analyzed through reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. LO reduced nasal symptom scores in AR mice, upregulated OVE-sIgG2a levels, and downregulated OVE-sIgE, OVE-sIgG1, and histamine levels. After the administration of LO, AR mice showed an increase in Th1 and Treg cytokines levels, while Th2 and Th17 cytokines levels were reduced. LO ameliorated the splenic T cell subset imbalance and attenuated inflammatory cell infiltration. LO reduced the levels of ERS-related and NLRP3 inflammasome activation-related mRNAs and proteins in the nasal mucosa. LO ameliorated AR symptoms by regulating T cell subset imbalance, hindering ERS and NLRP3 inflammasome activation.