Effect of FK506 on the immunosuppression of mesenchymal stem cells induced by interferon-γ and tumor necrosis factor-α

Abstract

Objective To investigate the mechanism of immunosuppressant FK506 on the immunesuppression of mesenchymal stem cells ( MSCs) induced by interferon ( IFN) -γ and tumor necrosis factor (TNF)-α. Methods MSCs pretreated with inflammatory cytokines were co-cultured with mice spleen cells. After incubation with FK506 for 72 h, proliferation of spleen cells was measured by methyl thiazol tetrazolium (MTT) assay and the apoptosis was assessed by flow cytometry. Real-time polymerase chain reaction (PCR) was used to detect the major molecule that mediated the immunosuppression of MSCs and the effect of FK506 on the molecule. Results MSCs pretreated with inflammatory cytokines could inhibit the proliferation of spleen cells and increase the apoptosis of spleen cells, and the apoptosis rate was (53. 5 ±2. 5) % , which was higher than that of MSCs pretreated with IFN-γ or TNF-α and control group ( P ＜0. 05), and IFN-γ and TNF-α upregulated inducible nitric oxide synthase (iNOS) expression in MSCs significantly, and this immunosuppression could also be antagonized by a specific inhibitor 1400W. However,FK506 could inhibit iNOS expression in MSCs pretreated with IFN-γ and TNF-α, the inhibition of spleen cells proliferation by MSCs was reduced significantly, and the apoptosis rate of spleen cells was reduced to (44. 3 ±3. 2)% (P＜0. 05). Conclusion FK506 inhibits the immunosuppression of MSCs through downregulation of iNOS expression in MSCs pretreated with IFN-γ and TNF-α. Key words: Mesenchymal stem cells; Inflammation; Immunosuppression; FK506