A1AT alleviates pancreas exocrine cells damage to transplanted islets in mice / 中华器官移植杂志

ABSTRACT

Objective To investigate the effect of alpha 1-antitrypsin (A1AT) concerning in reducing the injury of transplanted islets by pancreas exocrine cells and promoting proliferation of the pancreas B cells.Method The pancreases of mice were digested with collagenase,islets were isolated artificially,and pancreatic exocrine cells were collected.In purified islet group (n =6),100 islets were seeded into a 6 well culture plate.In experimental group(n =6),100 islets were co-cultured with equal volume of pancreas exocrine cells,and 0.5 mg/mL A1AT was added into a 6-well culture plate.In control group(n =6),100 islets were co-cultured with equal volume of pancreas exocrine cells.After 48 h,insulin content of islets in each well and trypsin concentration in the supernatant of each well were measured.The islets were cultured in low sugar and high sugar 1640 medium,then glucose stimulated insulin secretion (GSIS) test was carried out.In vivo,8-9-week old male BALB/C mice were induced with STZ (190 mg/kg body weight,i.p) to establish the diabetic model and randomly divided into two groups.In experimental(n =10) and control(n =10) groups,250 islets and the equal volume of pancreatic exocrine cells were transplanted into different regions of left kidney subcapsule,resepctively.The experimental group was injected with A1AT (83 mg/kg,qd,i.p) for 28 days after operation,and the control group was injected with the same amount of normal saline (qd,i.p) for 28 days.Both two groups were given EDU (5 μg/g,qd,i.p) for 28 days.The blood glucose level was monitored continually.Nephrectomies were performed after 28 days.The expression of anti-amylase antibodies in the renal subcapsule was detected by immunohistochemical staining,and the proliferation of islet beta cells was examined using immunofluorescence staining.Result Insulin levels and insulin stimulation index in the control group were decreased as compared with those in the purified islet group; those in the experimental group were higher than in the control group,but lower than in the purified islet group.Trypsin concentration in the control group was increased as compared with the purified islet group,that in the experimental group was lower than the control group,but higher than in the purified islet group (all P＜0.01).After islets transplantation,the blood glucose levels in control and experimental groups were normal,but those in the control group recovered later than in the experimental group (P＜0.01).At 3rd day after nephrectomy,the blood glucose levels were ＞21 mmol/L in both two groups.A large number of anti-amylase antibody-positive cells were found in the renal subcapsule in the control group while little seen in the experimental group after 28 days.The immunofluorescence showed that the insulin +/EDU + B cells in the experimental group were more than those in the control group.Conclusion Conclusion Co-culture of islets and pancreatic exocrine cells with A1AT can prevent islet cells from damage caused by trypsin.A1AT could inhibit the secretion of pancreatic amylase from pancreatic acinar cells and promote proliferation of islet beta cells.