Prolonged islet isograft survival in NOD mice treated with islet antigen-specific regulatory T cells

Abstract

Objective To investigate the survival of islet isograft in NOD mice treated with islet antigen-specific regulatory T cells.Methods GAD-65 antigen pulsed immature dendritic cells (imDC) were used to induce naive T cells into islet antigen-specific regulatory T cells.NOD mice which had progressed to type 1 diabetes (T1DM),as the recipients,received islet isografts (500 IEQ) under renal capsule from NOD mice without T1DM.In NOD mice in control group without transplantation,the changes in blood glucose (BG) were observed.NOD mice in simple islet transplantation group were given islet isograft without Treg infusion.In experiment group,NOD mice were infused with 1 × 106 islet antigen-specific regulatory T cells on the 1st day before transplantation,subsequently underwent islet isotransplantation.The survival of the islet isograft was evaluated by BG levels and the pathological changes were observed.Results BG levels were sustained above 11.1 mmol/L in control group.In simple islet transplantation group,BG level was decreased to the normal level in 1 ～2 days after transplantation,and began to rebound in 7～ 17 days posttransplantation and maintained at the preoperative level.The mean survival of the islet isograft in the NOD mice was (12.2 ± 2.6) day;In experiment group,BG level was decreased to the normal level in 1 ～2 days after transplantation,rebounded above 11.1 mmol/L in some mice on the 27th day after transplantation,and rebounded above 11.1 rnmol/L on the 43th day in all mice.The mean survival of the islet isograft in the NOD mice was (35.2 ± 4.3) days,which was significantly prolonged compared to simple islet transplantation group (P＜ 0.01).In simple islet transplantation group,the islet isograft was infiltrated by many lymph cells and damaged severely,and only few residual islet cells secreted insulin without complete islet existing in insulin staining.The islet isograft in experiment group was intact on the 15th day,with little lymph cell infiltration and a great number of islets secreting insulin.Conclusion Infusion of islet antigen-specific regulatory T cells induced by imDC and islet antigen GAD-65 in vitro could delay the destruction of autoimmune system and prolong the islet isograft survival in NOD mice. Key words: Islets of Langerhans; T-Lymphocytes, regulatory; Diabetes mellitus,type 1