Abstract
Objective The study aim to investigate the role of microRNA-155 (miR-155) on the immunoregulatory function of bone marrow mesenchymal stem cells (MSCs). Methods MSCs were isolated from 2-week-old Sprague-Dawley rats and identified by flow cytometry using anti-CD29, anti-CD44, anti-CD34, and anti-CD45 antibodies. MSCs were transfected with miR155-mimics, miR155-inhibitor, and control oligos, respectively, and then cocultured with spleen mononuclear cells (SMCs). The mRNA levels of Th1, Th2, Th17, and Treg cell-specific transcription factors (Tbx21, Gata3, Rorc, and Foxp3, resp.) and the miR-155 target gene SOCS1 were detected by quantitative real-time PCR (qPCR) in SMCs. The proportion of CD4+ FOXP3+ Treg cells was detected by flow cytometry. In addition, the effects of MSCs transfected with miR-155 on the migration of rat SMCs were investigated by transwell chamber. Results CD29 and CD44 were expressed in MSCs, while CD34 and CD45 were negative. The percentage of CD4+ FOXP3+ Treg cells in the SMC population was significantly higher compared with that noted in SMCs control group (p < 0.001) following 72 hours of coculture with miR155-mimics-transfected SMCs. In contrast, the percentage of CD4+ FOXP3+ Treg cells in the SMCs cocultured with miR155-inhibitor-transfected MSCs was significantly lower compared with that noted in SMCs control group (p < 0.001). MiR155-mimics-transfected MSCs inhibited the expression of Tbx21, Rorc, and SOCS1, while the expression of Gata3 and Foxp3 was increased. In contrast to the downregulation of the aforementioned genes, miR155-inhibitor-transfected MSCs resulted in upregulation of Tbx21, Rorc, and SOCS1 expression levels and inhibition of Gata3 and Foxp3. In the transwell assay, miR155-mimics-transfected MSCs exhibited lower levels of SMCs migration, while the miR155-inhibitor-transfected MSCs demonstrated significantly higher levels of migration, compared with the blank control group (p < 0.01, resp.). Conclusion miR-155 favors the differentiation of T cells into Th2 and Treg cells in MSCs, while it inhibits the differentiation to Th1 and Th17 cells.
Highlights
Mesenchymal stem cells (MSCs) are multipotent stem cells which can be isolated from various sources including bone marrow, spleen, heart, and umbilical cord blood tissues [1, 2]
The results indicated that the isolated cells were CD44 and CD29 positive and CD34 and CD45 negative, indicating the isolation of pure MSCs that could be used for further experiments (Figure 1(c))
MiR-155 was reported to contribute to the immunosuppressive functions of MSCs by promoting the differentiation of T cells to anti-inflammatory Th2 and Tregs, while concomitantly inhibiting the differentiation to T helper 1 (Th1) and Th17 subpopulations
Summary
The study aim to investigate the role of microRNA-155 (miR-155) on the immunoregulatory function of bone marrow mesenchymal stem cells (MSCs). MSCs were transfected with miR155-mimics, miR155-inhibitor, and control oligos, respectively, and cocultured with spleen mononuclear cells (SMCs). The mRNA levels of Th1, Th2, Th17, and Treg cell-specific transcription factors (Tbx, Gata, Rorc, and Foxp, resp.) and the miR-155 target gene SOCS1 were detected by quantitative real-time PCR (qPCR) in SMCs. The proportion of CD4+ FOXP3+ Treg cells was detected by flow cytometry. MiR155-mimics-transfected MSCs inhibited the expression of Tbx, Rorc, and SOCS1, while the expression of Gata and Foxp was increased. In contrast to the downregulation of the aforementioned genes, miR155-inhibitor-transfected MSCs resulted in upregulation of Tbx, Rorc, and SOCS1 expression levels and inhibition of Gata and Foxp. Conclusion. miR-155 favors the differentiation of T cells into Th2 and Treg cells in MSCs, while it inhibits the differentiation to Th1 and Th17 cells
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