The effect of mesenchymal stem cells on dynamic changes of T cell subsets in experimental autoimmune uveoretinitis

Abstract

Mesenchymal stem cells (MSCs) are being explored extensively as a promising treatment for autoimmune diseases. We have recently reported that MSCs could ameliorate experimental autoimmune uveoretinitis (EAU) in rats. In this study, we examined further the effects of MSCs on the dynamics of T cell subsets in both eye and spleen and their cytokine production during the course of EAU. We focused on when and where the MSCs had inhibitory effects on T helper type 1 (Th1) and Th17 cells and how long the inhibitory effect lasted, in order to provide more mechanistic evidence for MSCs on the treatment of uveitis. Compared to the control group, administration of MSCs decreased the production of Th1 and Th17 cytokines significantly, while the production of Th2 and regulatory T cell (T(reg)) cytokines [interleukin (IL)-10 and transforming growth factor (TGF)-β] was elevated during the entire course of EAU. Correspondingly, the dynamic levels of IL-17 in the aqueous humour (AqH) were reduced in MSC-treated rats. Moreover, the ratio of Th17/T(reg) cells in both spleen and eye was decreased. These results provide powerful evidence that MSCs can regulate negatively both Th1 and Th17 responses and restore the balance of Th17/T(regs) in the whole course of EAU, which is important for the regression of the disease.

© 2013 British Society for Immunology.

Figures

Figure 1

Effects of mesenchymal stem cells (MSCs) on the clinical development and histological changes of autoimmune uveoretinitis (EAU). In the group treated simultaneously with immunization the rats developed mild disease with a delayed onset, and the differences between MSC-treated and vehicle-treated conditions were statistically significant from day 6 (a). The group treated on day 12 after immunization also showed significant improvement, which started from day 14 (b). Histological examinations revealed that MSC-treated eyes displayed less inflammation and tissue damage than those of phosphate-buffered saline (PBS)-treated (control) eyes at all time-points (Fig. 1c,d).

Figure 2

Dynamic effects of mesenchymal stem cells (MSCs) on cytokine expression in the group treated simultaneously with immunization. In the control group, the expression levels of T helper type 1 (Th1) and Th17 cytokines [interleukin (IL)-2, interferon (IFN)-γ, IL-6 and IL-17] began to increase on day 6, reached a peak on day 12 and decreased gradually on days 15 and 20; the expression levels of Th2 and regulatory T cell (Treg) cytokines [IL-4, IL-10 and transforming growth factor (TGF)-β] were at a higher level on day 6, decreased at the peak of disease and then increased again when inflammation started to resolve on days 15 and 20. MSCs reduced significantly the productions of IL-2, IFN-γ, IL-6 and IL-17 compared to the control group at all time-points (P < 0·05).

Figure 3

Dynamic effects of mesenchymal stem cells (MSCs) on cytokine expression in the delay-treated group. Therapeutic administration of MSCs at the peak of the disease also reduced significantly the cytokine production released by R16-specific T helper type 1 (Th1) and Th17 cells (P < 0·05), while the production of Th2 and regulatory T cell (Treg) cytokines was elevated on days 15 and 20 post-immunization (P < 0·05).

Figure 4

Cytokine release in the aqueous humour (AqH). In the control group, the production of interferon (IFN)-γ and interleukin (IL)-17 in AqH increased from day 6 and reached a peak on day 12, then decreased gradually on days 15 and 20 post-immunization, and both preventive and therapeutic administration of mesenchymal stem cells (MSCs) decreased the levels of IFN-γ and IL-17 in the AqH at all time-points (a,b,d,e). IL-10 in AqH was high at the early stage of autoimmune uveoretinitis (EAU), but decreased when EAU reached a peak and then increased again when the disease started to resolve, and both preventive and therapeutic administration of MSCs elevated the level of IL-10 in AqH at all time-points (P < 0·05) (c,f).

Figure 5

Dynamic effects of mesenchymal stem cells (MSCs) on T helper type 17 (Th17) and regulatory T cell (Treg) cells from spleen and eye. In the control group, Th17 cells from spleen and eye presented the same trend as the autoimmune uveoretinitis (EAU) course (P < 0·05, a–d), while Tregs in the spleen and the eye presented the opposite trend to the EAU course (P < 0·05, e–h). By contrast, MSCs, when given at either days 0 or 12 post-immunization, decreased significantly the number of Th17 cells and increased the number of Tregs in both spleen and eye compared with the control group at all time-points (P < 0·05).