ILC3-like ILC2 subset increases in minimal persistent inflammation after acute type II inflammation of allergic rhinitis and inhibited by Biminkang: Plasticity of ILC2 in minimal persistent inflammation

Abstract Minimal persistent inflammation (MPI), the local inflammation that occurs after an acute type II immune response in patients with allergic rhinitis (AR), is responsible for airway hyperreactivity and the recurrence of AR. Innate lymphoid cells (ILCs) play a crucial role in mucosal immune homeostasis, but the changes of ILC subsets in the MPI stage remain unclear. In this study, the levels of ILC-secreting cytokines in nasal lavages were analyzed from 19 AR patients and 8 healthy volunteers. AR and MPI model mice were established to study the ILC subsets. The results showed that IL-17A was significantly increased in nasal lavage of AR patients in the MPI stage by MSD technology. When compared with the AR model mice, the frequency of IL-13+ILC2 in the nasal mucosa and lungs decreased, while IL-5+ILC2 remain high in MPI model mice. A part of the IL-5+ILC2 subset displayed ILC3-like characteristics with elevated RORγt, IL-17A and IL-23R expression. Especially, these ILC3-like ILC2 exhibited up-regulation of GATA3+RORγt+ were increased in MPI model mice. After the treatment of Biminkang, the frequencies of IL-5+ILC2, IL-17A+ILC3, and GATA3+RORγt+ILC3-like ILC2 were significantly reduced, and IL-23R expression was also decreased on ILC3-like-ILC2 subset. These results suggested that the elevated IL-17A in the MPI stage has been related to or at least partly due to the increased of ILC3-like ILC2. Biminkang could effectively decrease IL-17A+ILC3 and inhibit ILC3-like ILC2 subset in the MPI stage. Biminkang is effective in administrating MPI by regulating airway ILC homeostasis.