Interleukin-37 relieves allergic inflammation in a house dust mite allergic rhinitis murine model

The purpose of this study was to investigate the effects of interleukin-37 (IL-37) on a Dermatophagoides farinae (Der f)-induced murine model of allergic rhinitis (AR). BALB/c mice, except the control groups, were sensitized intraperitoneally and challenged intranasally with Der f (Der f group). The IL-37 and IL-37+anti-CD25 groups were administered IL-37 intranasally. The IL-37+anti-CD25 groups were administered anti-CD25 monoclonal antibody intraperitoneally before challenge. Allergic symptoms and the average eosinophil number were counted. The levels of cytokines and transcription factors in the nasal mucosa were measured by Real-Time polymerase chain reaction (PCR) and western blotting. The levels of Der f-specific immunoglobulin E (IgE) were measured. The CD4⁺CD25⁺Foxp3⁺T cells among splenic mononuclear cells were analyzed by flow cytometry. The allergic symptom scores and Der f-specific IgE levels were lower in the IL-37 group compared to the Der f group. Additionally, the levels of the transcription factor GATA-3 and ROR-γt and those of the cytokines IL-4, IL-5, IL-13, and IL-17, representing both T helper (Th)2 and Th17 responses, were lower in the IL-37 group in comparison with the Der f group. However, the Th1 response was not suppressed after administration of IL-37. IL-37 increased the IL-10 level; however, Real-Time PCR, western blotting, and flow cytometry results showed the limited action of IL-37 on CD4+CD25+Foxp3+T cells. This study demonstrates that intranasal IL-37 can suppress Th2 and Th17 responses in an AR murine model. Furthermore, these data suggest that IL-10 is increased, but CD4⁺CD25⁺Foxp3⁺T cells are not correlated with the IL-37-induced mechanism.