Allergen immunotherapy improves the immunosuppressive effects of Treg cells to treat allergic rhinitis by reducing the proportion of PU-1+ Treg subtypes.

The goal was to explore the function of Tregs and their subtypes for the treatment of allergic rhinitis (AR) using allergen immunotherapy (AIT) as well as investigate the underlying mechanism.

A total of 31 healthy volunteers, 29 patients with AR, and 16 AR subjects receiving AIT were enrolled. The total nasal symptom scores (TNSSs) were computed. Estimation of serum levels of interleukin (IL)-17, IL-10, IL-6, IL-5, IL-4, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-2, and immunoglobulin E (IgE) was done.

In the peripheral blood of the participants in the 3 groups, alterations in the percentages of Th1/Th2/Th9/Th17/Tfh cells, Treg subtypes, Treg cells, and CD4+ T cells were assessed. Analysis was done on the relationships between TNSS, Treg cells, and Treg subtypes and the levels of different cytokines in the AIT and AR groups.

TNSS and levels of IgE, IL-5 and IL-6 in the AR group were considerably greater when compared to the control group. On the other hand, the levels of IL-10, IFN-γ, and IL-2 were substantially lower when compared to the control group. The levels of IL-6, IL-5, IgE, and TNSS in the AIT group were considerably lower than those in the AR group, while the levels of IL-10, IFN-γ, and IL-2 were profoundly higher. In the AR group, the proportions of Th1 cells, GATA3+ Tregs, and Tregs were considerably decreased than those in the control group, but the proportions of Th2 cells, T-bet+ Tregs, and PU-1+ Tregs were significantly elevated.

The proportions of Th1 cells and Tregs in the AIT group were considerably higher than those in the AR group, and the proportions of Th2 cells and PU-1+ Tregs were significantly lower. As per correlation assessment, the levels of IL-6, IL-5, sIgE, and TNSS were all negatively connected with Treg cell proportions, but levels of IL-10 and IL-2 were favorably correlated. The level of IL-6, level of IL-5, level of sIgE, and TNSS were all favorably connected with PU-1+ Treg cell proportions, whereas negatively correlated with IL-10 levels, IL-2 levels, and Treg cell proportions.

In AR patients, AIT can lower the percentage of PU-1+ Treg subtypes. The numbers of PU-1+ Treg cells may serve as a marker for the therapeutic impact of AIT on AR.