Objective: To investigate the change of CD4(+) T cell activity in microRNA-126 (miR-126) knockdown (KD) mice and explore its significance.
Methods: The expression level of mature miR-126 in CD4(+) CD62L(+) T cells purified by magnetic-activated cell sorting (MACS) was analyzed by real-time PCR using specific probe. Furthermore, the expression levels of CD69, CD62L and CD44 molecules, as well as intracellular proliferating nuclear antigen Ki-67, in CD4(+) T cells in miR-126 KD mice were detected by fluorescence-activated cell sorting (FACS). Moreover, the apoptosis of CD4(+) T cells was analyzed by annexin V/PI staining assay combined with flow cytometry. Finally, the relative expressions of function-related cytokines including interleukine 4 (IL-4), IL-10, IL-12, transforming growth factor (TGF-β), interferon (IFN-γ) and tumor necrosis factor (TNF-α) in CD4(+) T cells were determined by real-time PCR.
Results: Compared with wild-type (WT) mice, the expression level of mature miR-126 in CD4(+) T cells in miR-126 KD mice was dramatically reduced. Furthermore, the proportion of CD62L(+) in CD4(+) T cells also decreased significantly, while the proportions of CD69(+), CD44(+) and Ki-67(+) cells were remarkably elevated. Meanwhile, the apoptosis proportion of CD4(+) T cells in vivo dropped dramatically in miR-126 KD mice. Finally, the mRNA expressions of IL-4 and IL-10 in CD4(+)T cells were significantly downregulated, but IL-12, TGF-β, TNF-α and IFN-γ mRNAs were obviously up-regulated.
Conclusion: miR-126 knockdown could significantly enhance the functional activity of CD4(+) T cells in vivo and promote cell differentiation into Th1 cells.