Objective: To explore the function and role of innate lymphoid cells in the pathogenesis of systemic lupus erythematosus (SLE) at different disease activity levels. Methods: From Nov 2017 to May 2018, 40 patients with SLE and 15 age-matched healthy non-immune-related diseases controls were enrolled from Anhui provincial hospital. According to the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)-2K, the patients were divided into active group (n=20) and remission group (n=20). The frequency of ILCs, B cells, CD4+T and CD8+T cells from peripheral blood mononuclear cells (PBMCs) was detected by flow cytometry. The subsets of ILCs in each group were compared with the subsets of B cells and T cell respectively. The levels of IL-4, IL-33 and IFN-γ in each group were tested by ELISA. Result: Compared with the control group, ILC1 percentage was significantly increased in SLE active group [(22.33%±2.52%) vs (14.56%±1.28%), P=0.018 1]; ILC2 percentage was decreased significantly in both remission group [(19.67%±1.83%) vs (42.48%±3.46%), P<0.000 1] and active group [(8.67%±0.83%) vs (19.67%±1.83%), P<0.000 1]; ILC3 percentage was decreased significantly in active group [(5.72%±1.08%) vs (14.35%±2.40%), P=0.001 3]. SLEDAI score was negatively correlated with the percentage of ILC2 (P=0.023 9) in all patients. The percentage of ILCs in the remission group (P=0.046 2) and activity group (P=0.003 7) were both increased significantly. Moreover, the percentage of ILC2 in active group was negatively correlated with CD4+T cells (P=0.030 8), and the serum IgG was negatively correlated with ILC2% in all patients (P=0.013 8). Compared with control group or remission group, the levels of IFN-γ (F=10.91, P=0.000 1) and IL-4 (F=6.046, P=0.004 7) in active group were remarkable higher. However, IL-33 was significantly reduced in active group (F=6.645, P=0.002 7). The percentage of ILC2 (r=0.154 3, P=0.028 8) and ILC3 (r=0.313 6, P=0.001 1) in all patients with SLE were positively correlated with the level of IL-4. Conclusion: The percentage of ILCs is related to disease activity, and ILCs play a "double-edged" role in the pathogenesis of SLE. Its function and mechanism are worth further exploration.
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