The Role Of Innate Lymphoid Cells(ILCs)and Th17/Treg Imbalance In The Pathogenesis Of Rheumatoid Arthritis

Objective:Rheumatoid arthritis(RA)is an autoimmune disease characterized by chronic inflammatory and progressive bone damage.Its clinical manifestations are morning stiffness,joint swelling,pain and deformity.It can also be complicated with heart,lung,kidney,nerve and blood vessel and other system diseases.RA is a disease that seriously endangers human health.The pathogenesis of RA involves a variety of immune cells and cytokines.The early onset of RA is related to the changes of innate and adaptive immune systems and the production of autoantibodies.Both innate and adaptive immune cells contribute to the persistence and development of a chronic inflammatory state in the late stage of the disease.Focusing on the immune cells involved in innate and adaptive immune response,this paper mainly studies the roles of innate lymphoid cells(ILCs),helper T(TH)17 cells,and regulatory T cells(Treg)in RA,aiming to provide new ideas for the pathogenesis of RA.Methods:A total of 79 RA patients were selected from July 2019 to December 2020 in the Department of Rheumatology and Immunology of The Affiliated Hospital of Jiangsu University.All the cases included in the study met the new RA classification standard jointly proposed by American College of Rheumatology(ACR)and European League against Rheumatism(EULAR)in 2010.Disease activity score-28(DAS28)were used to evaluate the degree of disease activity.Twenty-three healthy people were selected as negative control.The general clinical indexes such as ESR,CRP,RF,ACCP and IL-6 of the subjects were measured uniformly,and the proportion of CD4~+T cells,CD19~+B cells,natural killer(NK)cells,Th17,Treg,ILC1s,ILC2s and ILC3s in the whole blood of the subjects was detected by flow cytometry.The cytokines levels of IFN-γ,IL-4,IL-10,IL-17A,IL-22 and IL-33 in serum were detected by ELISA.Results:(1)Compared with the control group,there were no significant differences in sex and age in RA group.The levels of ESR,CRP and RF in RA group were significantly increased(P<0.01).ESR(r=0.564,P<0.01)and CRP(r=0.381,P<0.01)were positively correlated with DAS28.RF,ACCP and IL-6 had no correlation with DAS28.(2)Compared with the control group,the proportion of CD4~+T cells,CD19~+B cells,Th17cells,ILC2s and ILC3s were significantly increased in RA group;Treg cells and ILC1s were significantly decreased(P<0.05 or P<0.01).There were no significant changes in NK cells and total ILCs.(3)Compared with the control group,the level of IFN-γ,IL-4,IL-17A and IL-22 in RA group was significantly increased,while the level of IL-10 was significantly decreased(P<0.05or P<0.01),the level of IL-33 was not significantly changed.(4)According to DAS28,RA patients were divided into four groups:A1 group(remission group,DAS28<2.6,n=25),A2 group(low activity group,2.6≤DAS28≤3.2,n=19),A3 group(moderate activity group,3.2<DAS28≤5.1,n=27),A4 group(high activity group,DAS28>5.1,n=8).Compared with the control group,ESR of group A2,A3 and A4 were significantly increased(P<0.01),but there was no significant difference in group A1.Compared with the A1group,ESR of the A2,A3 and A4 groups were significantly increased,with statistical significance(P<0.05 or P<0.01).Compared with the control group,CRP and RF were significantly increased in group A1,A2,A3,and A4,but there were no significant difference between group A1,A2,A3 and A4.Compared with the control group,the proportion of Th17cells in A3 and A4 groups was significantly increased,the proportion of ILC2s in A2 and A4groups was significantly increased,the proportion of ILC3s in A4 group was significantly increased,and the proportion of Treg and ILC1s in A4 group was significantly decreased,with statistical significance(P<0.05 or P<0.01).There was no significant difference in the proportion of total ILCs among the five groups.Compared with the control group,the serum IL-17A level in A1,A2,A3 and A4 groups was significantly increased,while the serum IL-10level in A4 group was significantly decreased(P<0.05 or P<0.01).There were no significant differences in the level of IFN-γ,IL-4,IL-22 and IL-33 among all groups.Compared with the control group,the Th17/Treg ratio in A3 and A4 groups was significantly increased,with statistical significance(P<0.05),while the Th17/Treg ratio in A1 and A2 groups was not significantly changed.(5)Patients with RF<20IU/m L were classified as RF~-group,and those with RF>20IU/m L were classified as RF~+group.Compared with the control group,the percentage of Th17 cells in RF~-group and RF~+group increased significantly,the percentage of CD19~+B,ILC2s and ILC3s in RF~+group increased,while the percentage of ILC1s decreased significantly(P<0.05 or P<0.01).The percentage of CD4~+T,Treg,NK and total ILCs did not change significantly.Compared with the control group,the level of IL-17A in RF~-group and RF~+group increased significantly(P<0.05 or P<0.01),but the levels of IFN-γ,IL-4,IL-10,IL-22 and IL-33 had no significant difference.(6)Patients with ACCP<25RU/m L were classified as ACCP~-group and those with ACCP>25RU/m L as ACCP~+group.Compared with the control group,the proportion of CD19~+B,ILC2s and ILC3s in ACCP~+group increased,and the proportion of CD19~+B cells in ACCP~+group was higher than that in ACCP~-group,while the proportion of Treg and ILC1s decreased compared with the control group and the proportion of Th17 cells in ACCP~-group and ACCP~+group increased significantly(P<0.05 or P<0.01).Compared with the control group and ACCP~-group,the level of IL-17A in ACCP~+group increased significantly(P<0.05 or P<0.01),but the levels of IFN-γ,IL-4,IL-10,IL-22 and IL-33 had no significant difference.(7)Correlation analysis showed that there was a negative correlation between ILC2s and serum IL-33 level in RA patients(r=-0.515,P<0.01),and no significant correlation with other indexes such as age,DAS28,ESR,CRP,RF,ACCP,IL-6,CD4~+T cells,CD19~+B cells,Th17cells,Treg cells,IFN-γ,IL-4,IL-10,IL-17A,IL-22.The proportion of ILC1s and ILC3s cells had no significant correlation with the indexes above.There was a positive correlation between Th17 and IL-17A in RA patients(r=0.833,P<0.05),but no correlation between Th17 and other indexes.There was no correlation between Treg and the indexes above.Conclusion:CD4~+T cells,CD19~+B cells,Th17 cells,ILC2s and ILC3s were increased in peripheral blood of RA patients,while Treg cells and ILC1s were decreased.Moreover,Patients with different disease activity showed imbalance of Th17,Treg and ILC subsets.With the increase of disease activity,IL-17A increased and IL-10 decreased.CD19~+B cells,Th17 cells,Treg cells and ILC subsets were unbalanced in RA patients with RF or ACCP.CD19~+B cells,Th17 cells,Treg cells and ILC subsets may be involved in the production of RF and ACCP in RA patients.