MSC Attenuates Dry Eye Associated With CGNHD By Regulating The Balance Of Th17and Treg Cell

Objective:To evaluate the safety and efficacy of mesenchymal stromal cell (MSC) for treatment of dry eye associated with chronic graft-versus-host disease (cGVHD), and to assess the immunomodulatory effect of MSC on regulatory dendritic cell (DCreg) in order to elucidate the underlying molecular mechanisms of MSC treatment.Methods:Eighteen patients with dry eye associated with cGVHD were enrolled in this study. After allogeneic hematopoietic stem cell transplantation (HSCT), all the enrolled patients suffered from dry eye associated with cGVHD. Their dry eye symptoms continued despite they had been treated with artificial lubricants and standard immunosuppressive agents. Patients received intravenously in vitro expanded bone marrow (BM)-derived MSC. Dry eye symptom scoring (NIH consensus criteria), Schirmer test, breakup time of tear film (BUT) and Ocular Surface Disease Index scoring were examined before and after MSC infusion. The levels of CD80, CD86, CD40and the ratio of Thl7cells and Treg cells were detected by flow cytometry. We further performed co-culture assay of MSC and mature DC (maDC) obtained form mouse. The changes of CD80, CD86and CD40, immunophenotyping of maDC, were detected by flow cytometry. The plasmatic levels of IL-6, IL-12, IL-10and TGF-P were measured by enzyme-linked immunosorbent assay (ELISA). In addition, mixed lymphocyte culture (MLC) was performed to find the proliferation of lymphocytes cultured with maDC or MSC-DC. The percents of Th17cells and Treg cells in MLC were also detected by flow cytometry.Results:Ten patients (55.55%) had symptom abatement after MSCs treatment with3patients having a complete recession and7having a partial recession. Significant improvement was observed in dry eyes scores, Schirmer test results, BUT results and OSDI scores. Clinical improvement was accompanied by decreasing levels of CD80, CD86and CD40. The patients had significantly lower levels of Thl7cells, while had higher levels of Treg with a descendent ratio between Th17and Treg cells. In vitro, the CD40, CD80and CD86were all decreased after MSC and DC co-culturing, accompanied by increasing CD11b and Jagged2. The novel DC subset, called as Jagged2high CD11bhigh MSC-DCreg, can secret more IL-10and TGF-β while less IL-6and IL-12, associated with less CD4+IL-17A Thl7cells and more CD4+CD25+Foxp3+Treg cells compared with maDC.Conclusions:Transfusion of MSCs expanded in vitro improved dry eye symptoms in some (55.55%) patients with dry eye secondary to cGVHD who were refractory to other immunosuppressive medications. MSCs appear to exert their immunosuppressive effect by triggering the generation of Jagged2high CD11bhigh MSC-DCreg, secreting more IL-10and TGF-β while less IL-6and IL-12, which possibly regulate CD4+IL-17A Th17cells and CD4+CD25+Foxp3+Treg cells towards Treg cells. Targeting the enhancement of Jagged2high CD11bhigh MSC-DCreg may be a beneficial approach to treating dry eye secondary to cGVHD.