Abstract: Objective To observe the immunoregulatory effects of bone marrow mesenchymal stem cells (BM-MSCs) on the differentiation of helper T cell 17 (Th17) in vitro. Methods Mouse CD4+ na?ve T cells, which were co-cultured with isolated mouse BM-MSCs, were induced to differentiate into Th17 for 3 days. The percentage of induced CD4+IL-17+ Th17, concentration of cytokine IL-17 and expression level of specific transcription factor Rorγt were measured by flow cytometry, ELISA, qRT-PCR and Western blotting, respectively. In some experiment, neutralizing antibody of IL-10 (NA-IL-10) and NA-PGE2 were added into the co-culture system to test the induced rate of Th17. Results Mouse BM-MSCs secreted high levels of cytokines TGF-β and IL-6. The CD4+ na?ve T cells co-cultured with BM-MSCs produced less CD4+IL-17+ cells (2.5%±1.5%), lower concentration of IL-17 (23±3 ng/L) and decreased expression of Rorγt compared with control group (17.8%±4.2% and 268±27 ng/L, P﹤0.05). The concentration of IL-10 and PGE2 were gradually increased in the co-cultured group, and significantly higher than these of control group in the same time (P﹤0.05). When NA-IL-10 or NA-PGE2 added into the co-culture group, the CD4+ na?ve T cells produced more CD4+IL-17+ cells (2.0%±0.5% to 11.8%±2.5%，P﹤0.05), higher concentration of IL-17 (24±4 ng/L to 123±25 ng/L，P﹤0.05) and increased expression level of Rorγt compared with isotype antibody control group. Moreover, the cocktail of NA-IL-10 and NA-PGE2 could further augment the induced rate of Th17. Conclusion Although BM-MSCs secrete high levels of cytokines TGF-β and IL-6, which are essential for Th17 differentiation, BM-MSCs inhibit the differentiation of Th17 potentially through IL-10 and PGE2 in vitro.

Key words: bone marrow mesenchymal stem cell, na?ve T cell, helper T cell 17, differentiation