The regulatory effect of IFN-gamma or IL-17a primed limbal mesenchymal stem cells on lymphocytes immune response

Abstract

Purpose : The cornea is a transparent, avascular tissue that covers the front portion of the eye. In pathologic and highly inflammatory conditions, the entire ocular surface is at risk for persistent scarring and visual loss. Despite all the treatment strategies, no effective solution has been found for patients with severe corneal injuries. Mesenchymal stem cells (MSCs) are of particular interest for the treatment of immune-related diseases owing to their immunosuppressive properties. Priming with proinflammatory cytokines improve the immunosuppressive function of MSCs. The purpose of our study is to identify the immunosuppressive effect of interferon (IFN)-γ and Interleukin (IL)17A primed Limbal- MSCs (LMSCs) on lymphocyte response. Methods : LMSCs were isolated from cadaveric corneoscleral rims and cultured in DMEM with penicillin-streptomycin and fetal bovine serum. LMSCs were characterized and differentiated in passage 3. The lymphocytes were isolated from peripheral venous blood of healthy controls (n=10). LMSCs were stimulated with IFN-γ or IL-17A for 48 hours. At the end of this period, peripheral blood mononuclear cells of healthy individuals were isolated and cultured with or without stimulated LMSCs for 72 hours. The cultures were stimulated with anti-CD3 and anti-CD28 antibodies. After 72 hours, lymphocytes were collected and analyzed for proliferation assay, cell viability assay with Annexinv/PI, Fas, FasL and CD4+CD25+FoxP3+T regulatory cell ratio via flow cytometry. Results : Our results demonstrated that IFN-γ or IL-17A stimulated LMSCs suppressed the proliferation of T lymphocytes compared to unstimulated LMSCs cultures and it was statistically significant (P<0.05, P<0.05, respectively). IFN-γ stimulated LMSCs suppressed the Annexin V and Fas expression compared to unstimulated LMSCs cultures (P<0.05) but IL-17A stimulated LMSCs did not reduce the AnnexinV and Fas expression significantly compared to unstimulated LMSCs cultures (P>0.05). IFN- γ stimulated LMSCs increased T regulatory cell frequency compared to unstimulated LMSCs cultures (P<0.05). Conclusions : Our data showed that stimulated LMSCs especially IFN-γ decreased lymphocyte proliferation and apoptosis while increased the T regulatory cell ratio. We believe that LMScs could potentially be a source for future treatment strategies of inflammatory conditions particularly corneal disease.