Objective  To investigate the regulating function of human gingival mesenchymal stem cell (GMSC) on the proliferation and differentiation of B cells and its underlying molecular mechanism.

  Methods  GMSC were isolated and B cells were isolated from peripheral blood. GMSC or fibroblasts were co-cultured with B cells in vitro and assigned into the GMSC group and fibroblast group. The proliferation of B cells was detected in two groups. The expression of IgG1 and IgM in the cell supernatants was measured between two groups. The secretion of interleukin (IL)-6, Perforin, interferon (IFN)-γ and tumor necrosis factor (TNF)-α was compared between two groups. The expression levels ofIL-10 and transforming growth factor (TGF)-β in B cells were detected between two groups. The expression of PC-1 in B cells was measured in two groups. The signaling pathway involved with the regulating effect of GMSC on B cell function was investigated. The regulating effect of GMSC on the role of B cells in activating T cell function was assessed.

  Results  Compared with the fibroblast group, the proliferation of B cells was significantly weakened in the GMSC group (P < 0.05). Co-culture of GMSC and B cells significantly inhibited the secretion of IgG1 and IgM from B cells and the secretion ofIL-6, Perforin, IFN-γ and TNF-α (all P < 0.05). Compared with the fibroblast group, the secretion of IL-10 and TGF-βwas significantly higher in the GMSC group (both P < 0.05). The expression level of PC-1 in the GMSC group was significantly down-regulated (P < 0.05). After adding ALK5, an inhibitor of TGF-β receptor, the inhibitory effect of GMSC upon B cells was significantly weakened (P < 0.05). Compared with the fibroblast group, the ability of B cells to activate and proliferate T cells was significantly attenuated in the GMSC group (P < 0.05).

  Conclusions  GMSC can inhibit B cells and their mediated immune responses. The activation of B cells and other related functions can be suppressed through the TGF-β signaling pathway.