Background/Purpose: Systemic lupus erythematosus (SLE) is an autoimmune disease that is characterized by a large number of autoantibodies and multiple organs damage. T follicular helper(Tfh) cell is a subtype of CD4⁺T cells that is characterized by high expression of CXCR5, ICOS, PD-1, Bcl-6 and IL-21, and assisting B cells to produce antibodies. Previous studies have reported increased numbers of circulating Tfh cells in patients with SLE, which play an important role in the development and progression of SLE. However, the mechanism of abnormal differentiation of Tfh cells in SLE is not yet clear. Numerous studies have reported that microRNAs (miRNAs) were involved in the differentiation and function-related genes regulation of various immune cells, contributing to autoimmune diseases. In this study, we investigated the role of miRNA-21 (miR-21) in regulating the aberrant differentiation of Tfh cells in SLE patients.

Methods: This study was approved by the ethical committee of the Second Xiangya Hospital of Central South University and written informed consent was obtained from all subjects. 24 SLE patients and 24 healthy controls were recruited. CD4⁺ T cells and naive CD4⁺ T cells were isolated by magnetic beads. All patients fulfilled at least 4 of the SLE classification criteria of the American College of Rheumatology. RT-qPCR were used to detect miR-21 and genes expression. Naive CD4⁺ T cells were transfected with miR-21 Agomir or Agomir negative control, and were induced to differentiate into Tfh cells under Tfh cells polarized-condition. SLE CD4⁺ T cells were transfected with miR-21 Antagomir or Antagomir negative control, and then were stimulated by anti-CD3/CD28. The percentage of Tfh cells was detected by flow cytometry. Western blot were used to detect the protein expression level of FOXP1 gene. Student’s t-test for equality of means was used to compare values. P-values < 0.05 were considered as significant.

Results: Compared with healthy controls, the expression of miR-21, CXCR5, PD1, BCL6 and IL21in CD4⁺ T cells of SLE patients was significantly increased (P<0.001). miR-21 expression levels positively correlated with SLEDAI scores in SLE patients. Compared with Agomir negative control, the percentage of Tfh cells was significantly increased in naive CD4⁺ T cells transfected with miR-21 Agomir under Tfh cells polarized-condition, and the expression levels of miR-21, CXCR5, PD1, BCL6 and IL21 were up-regulated significantly. Compared with Antagomir negative control, the percentage of Tfh cells was reduced in SLE CD4⁺ T cells transfected with miR-21 Antagomir, and the expression levels of miR-21, CXCR5, PD1, BCL6 and IL21 were also decreased significantly. The protein level of FOXP1, a negative regulator of Tfh cells differentiation, was significantly decreased in CD4⁺ T cells of healthy controls transfected with Agomir and was increased in CD4⁺ T cells of SLE patients transfected with miR-21Antagomir compared with negative controls respectively.

Conclusion: miR-21 expression was increased in CD4⁺ T cells of SLE patients, which contributes to the aberrantly increased Tfh cells in SLE patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-effect-of-mirna-21-overexpression-on-the-aberrant-t-follicular-helper-cells-differentiation-in-systemic-lupus-erythematosus/