Changes in type 2 innate lymphoid cells and serum cytokines in sublingual immunotherapy in pediatric patients with allergic rhinitis

Background Type 2 innate lymphoid cells (ILC2) are upregulated in childhood allergic rhinitis (AR) and are associated with AR severity. This study aimed to investigate changes in the ILC2 milieu in pediatric patients with AR after sublingual immunotherapy (SLIT).Methods Forty- pediatric patients with AR received house dust mite (HDM) allergen extract for SLIT group and thirty pediatric patients received placebo in the study, respectively. The levels of ILC2, ILC2-related cytokines (IL-5/IL-13) and their transcription factors (GATA binding protein 3, retinoic acid-related orphan receptor alpha) in the circulation were assessed after 1- and 2-year SLIT. Moreover, peripheral blood mononuclear cells (PBMCs) in patients were prepared and stimulated by recombinant thymic stromal lymphopoietin, IL-25, and IL-33 after 2-year SLIT. Subsequently, the levels of ILC2, IL-5, and IL-13 were tested.Results The frequency of ILC2 and the levels of their transcription factors in the circulation were significantly decreased after SLIT in the SLIT group. The levels of ILC2-related cytokines in the SLIT group showed the same trend. The frequency of ILC2 was positively correlated with transcription factors and cytokines after SLIT. SLIT was observed to reduce the ability of HDM sensitization to generate the ILC2 milieu in PBMCs.Conclusions Changes in the ILC2 milieu may be correlated with the curative effect and immune regulation function of SLIT. Our results suggested that the regulatory effect on ILC2 is part of the therapeutic mechanism of SLIT.