PPARgamma Modulates CD4⁺ T-Cell Differentiation and Allergic Inflammation in Allergic Rhinitis: A Potential...

Objectives: Given the emerging role of peroxisome proliferator-activated receptor gamma (PPARgamma) in immune regulation and the increasing prevalence of allergic rhinitis (AR), we sought to understand how modulation of the PPARgamma pathway impacts the balance of CD4⁺ T-cell subsets, particularly regulatory T cells (Tregs) and T helper (TH)1, TH2, and TH17 cells, which are key players in the pathogenesis of AR. This knowledge is crucial for developing novel therapeutic strategies targeting the PPARgamma-CD4⁺ T-cell axis to manage AR more effectively. Methods: We used PPARgamma^f/fLyz2-Cre mice for PPARgamma deletion. In an ovalbumin (OVA)-induced AR mouse model, PPARgamma^+/-f/fLyz2-Cre mice were assessed for allergic symptoms, splenic Tregs, and nasal eosinophils. Additionally, the effects of a PPARgamma agonist on the polarization of naïve CD4⁺ T cells were examined. Results:PPARgamma^+/-f/fLyz2-Cre mice showed worsened allergic symptoms, reduced splenic Tregs, and increased nasal mucosa eosinophilic infiltration. PPARgamma agonist treatment promoted naïve CD4⁺ T-cell polarization into Tregs and inhibited their differentiation into TH1, TH2, and TH17 subsets. Conclusions: Our findings indicate that PPARgamma plays a crucial role in regulating TH-cell subsets in AR. PPARgamma agonists could be a potential therapeutic strategy to mitigate allergic inflammation in AR by promoting Treg development and suppressing pathogenic TH-cell responses.