Background/Purpose:  In our previous study, the transcriptome profiles of CD4⁺T cells from 13 active RA cases and 9 healthy controls were accessed by microarrays. a total of 1496 differential genes were identified. To investigate whether these significant differential genes were regulated by miRNAs, further studies were carried out for the new regulating effect of miRNAs in CD4⁺T cell, the results not only benefit to understanding the pathogenesis of RA, but also explore a new strategy for immunotherapy of RA.

Methods: Peripheral blood CD4⁺T cells isolated from RA patients and healthy individuals were performed by microarray analysis. The selected candidate genes and miRNA were validated by quantitative real-time PCR (qPCR). Dual luciferase reporter assay system and western blot were used to validate the direct function of miR-30a and SOCS3. In order to determine whether miR-30a affects IL-6 or IFN-r-mediated JAK-STAT pathway by targeting SOCS3. We transfected a synthetic miR-30a mimic or its inhibitor in Jurcat cells, Western Blot was used to detect the SOCS3 and STAT3 protein level after stimulated by IL-6 or IFN-r. To investigate the potential differentiation effect of miR-30a, we over-expressed miR-30a in naïve T cell, and T cell subsets were tested by Flow cytometry. To further show that miR-30a plays a significant role in RA pathogenesis, we constructed CIA models, the synthesis miR-30a antagomir or NC antagomir were injected by tail vein respectively. After injection for 70 days, H&E staining and micro-computed tomography (micro-CT) confirmed that the inflammatory infiltration and bone erosion was reduced in the group of miR-30a antagomir CIA mice compared to the control group.

Results: MiR-30a expression increased in RA patients compared to controls, and it markedly repressed the reporter activity of the 3’untranslated regions (UTRs) of SOCS3, mutation of the 3’ UTRs of the repressed gene confirmed that SOCS3 was the target of miR-30a. Consistent with the reporter assays, the expressions of endogenous SOCS3 protein were decreased in 293T cells by over-expression of miR-30a mimic. Over expression of miR-30a increased the phosphorylation level of STAT3, which may be regulated by the IL-6/IFN-r-mediated JAK-STAT activation pathway. Th1 subsets was remarkable higher in naïve T cells transfected by miR-30a mimic, which suggested that miR-30a may promote the differentiation of CD4⁺T cells, but had no effect in the proliferation. In our animal experiment, the clinical core of CIA mice were lower in the miR-30a antagomir mice (micro-CT) confirmed that inflammatory infiltration and bone erosion were relieved in the miR-30a antagomir mice.

Conclusion: Over expression of miR-30a in CD4+T cell inhibited the protein level of SOCS3 and promoted the differentiation of Th1 cell, which may be regulated by the IL-6/IFN-r-mediated JAK-STAT pathway. The results also provide evidence that down-regulating expression of miR-30a in CIA mice decreased the arthritis score, as well as reduce the degree of bone erosion and cell invasion.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/microrna-30a-promotes-the-inflammatory-response-of-rheumatoid-arthritis-by-regulating-th1-cell-differentiation/