BPIFA1 alleviates allergic rhinitis by regulating the NF‐κB signaling pathway and Treg/Th17 balance

Abstract Aim Allergic rhinitis (AR) is an allergic condition characterized by inflammation of the nasal mucosa. Bacterial permeability‐increasing family member A1 (BPIFA1) exhibits anti‐inflammatory properties; however, its impact on AR remains unclear. Aim of this study is to investigate the expression and function of BPIFA1 in AR and its influence on inflammation and immune regulation in a mouse model of AR induced by ovalbumin (OVA). Methods The expression of BPIFA1 was analyzed using quantitative real‐time PCR (qRT‐PCR) and immunohistochemistry (IHC). Morphological assessments of nasal mucosal tissues were conducted. Levels of inflammatory mediators in nasal lavage fluid (NALF) and serum were quantified using enzyme‐linked immunosorbent assay (ELISA) kits. Protein expressions of BPIFA1, phosphorylated and total p65 (p‐p65/p65), and IκBα were evaluated through Western blot analysis. The total cell counts, including epithelial cells, eosinophils, and lymphocytes in NALF, were determined using a hemocytometer. A mouse model of AR was established by OVA management. Results BPIFA1 expression was found to be reduced in the nasal mucosa tissues of patients with AR, suggesting a potential role in the disease's progression. We successfully developed a mouse model of AR, where BPIFA1 was similarly downregulated, indicating its possible involvement in modulating the NF‐κB signaling pathway. Overexpression of BPIFA1 in this model attenuated inflammation and allergic responses by inhibiting the NF‐κB pathway. Additionally, overexpression of BPIFA1 promoted the differentiation of regulatory T cells (Treg) and inhibited the differentiation of T helper 17 cells (Th17) in the NALF of AR mice, further demonstrating its regulatory impact on immune responses. The study confirmed that BPIFA1 upregulation reduced the levels of inflammatory cytokines TNF‐α and IL‐6, decreased infiltration of inflammatory cells, and modulated antigen‐specific immunoglobulin levels and histamine in serum. Conclusion BPIFA1 mitigated both inflammatory and allergic responses in AR mice induced by OVA through the modulation of the NF‐κB signaling pathway and the balance between regulatory T cells (Treg) and T helper 17 cells (Th17). These findings suggest that BPIFA1 could serve as a novel biomarker and therapeutic target for AR, offering potential for the development of targeted treatments to improve patient outcomes.