Interferon-γ and tumor necrosis factor-α promote the ability of human placenta–derived mesenchymal stromal cells to express programmed death ligand-2 and induce the differentiation of CD4+ interleukin-10+ and CD8+ interleukin-10+ Treg subsets

Abstract Background aims Mesenchymal stromal cells (MSCs) and regulatory T cells (Treg) have been successfully used in treating autoimmune diseases accompanied by abundant inflammatory cytokines such as interferon (IFN)-γ and tumor necrosis factor (TNF)-α. Therefore, this work investigated the effects of IFN-γ and TNF-α on the ability of human placenta-derived mesenchymal stromal cells (hPMSCs) on inducing the differentiation of CD4+ interleukin (IL)-10+ and CD8+ IL-10+ Treg subsets. Methods Human PMSCs were co-cultured with T cells in the presence or absence of a trans-well system or anti- programmed death ligand-2 (PDL2) monoclonal antibody (mAb), respectively. CD4+ IL-10+ and CD8+ IL-10+ Treg subsets, as well as the levels of IL-10 in the supernatants, were detected on this basis. Examinations were conducted to explore the impact of IFN-γ and TNF-α on the expression of PDL2 in hPMSCs. In this process, flow cytometry, Western blot and reverse-transcriptase–polymerase chain reaction were used. Results CD4+ IL-10+ and CD8+ IL-10+ Treg subsets from T cells either non-activated or activated by use of phytohaemagglutinin (PHA) or CD3/CD28mAb significantly increased in the presence of hPMSCs. However, these levels markedly decreased after blocking the expression of PDL2 in hPMSCs. IL-10 followed the same pattern. Furthermore, the percentages of CD4+ IL-10+ and CD8+ IL-10+ T cells also sharply declined under the trans-well system, whereas the percentages as well as the expression of PDL2 in hPMSCs oppositely raised after hPMSCs pre-stimulated by IFN-γ and TNF-α. IFN-γ could promote the expression of PDL2 partly through the JAK/STAT signaling pathway. Conclusions IFN-γ and TNF-α could promote the ability of hPMSCs in inducing the differentiation of CD4+ IL-10+ and CD8+ IL-10+ Treg subsets and enhance the expression of PDL2 in hPMSCs. These would benefit the application of hPMSCs in clinical trials.