PPARγ Agonist And Insulin Reduced The Expression Of TIPE2 And Cell Apoptosis Both In Vivo And Vitro Inducing By High Glucose And Aβ1-40 Through Inhibiting Inflammatory Reaction

Aims:Tumor necrosis factor-a induced protein 8 like-2 (TIPE2) is a novel member of TNFAIP8 family, which is necessary for negative growth control and homeostasis of immune system. Meanwhile TIPE2 can activate caspase-8 to promote the cell apoptosis mediated by Fas protein and induced by activated T cell. But the regulatory mechanism of TIPE2 and its relationship with cell apoptosis are not clear. The effects of common antidiabetics such as peroxisome proliferator activated receptor y (PPARy) agonist Rosiglitazone and insulin on TIPE2 have not been reported. The purpose of this study is to explore the role and regulatory mechanism of TIPE2 and cell apoptosis in diabetic central nervous system injury, and seek for effective pharmaceutical interventions.Methods:(1) The 3-month-old Wistar rats were selected as 3Wistar group, the GK rats were devided into 3-month-old GK rats (3GK group),6-month-old GK rats (6GK group), rosiglitazone treated 6-month-old GK rats (RSG+6GK group) and insulin treated 6-month-old GK rats (INS+6GK group).(2) Use immunohistochemistry (IHC) to observe the quantity and feature of TIPE2 expression in different rats’brains. Use RT-PCR and Western Blot respectively to detect the mRNA and protein level of TIPE2 in different rats’brains. Use immunofluorescence (IH) to observe the numbers of apoptotic cells in different rats’brains.(3) Use different concentration of glucose, rosiglitazone, pioglitazone, fibrillous Aβ1-40 and Aβ1-40 oligomer intervening the primary cultured rat hippocampal neurons. Then the cells randomly divided into 10 groups were exposed to pairwise combined intervention at medium concentration.(4) Use RT-qPCR and Western Blot respectively to detect the mRNA and protein level of TIPE2 in different groups of cells. Use flow cytometry to analyze the index of apoptotic cells.(5)A11 the data are presented as mean±SD (standard deviation). The GraphPrism 5 was used to analysis. Comparison between several groups is analyzed by one-way analysis of variance, comparison between two groups is analyzed by t-test and the correlation is analyzed by Person analysis correlation. All the analysis is with P<0.05 as statistical significance.Results:(1) The TIPE2 was mainly expressed in the cytoplasm of neurons, activated microglias and microvessel walls. The expression of TIPE2 displays a marked difference in different groups.3GK group is significantly higher than 3Wistar group (P<0.05),6GK group is significantly higher than 3GK group (P<0.05), RSG+6GK group and INS+6GK group are significantly lower than 6GK group (P<0.05).(2) The percentages of TUNEL-positive cells was significantly higher in 3GK group compared to that in 3Wistar group (P<0.05), significantly higher in 6GK group compared to that in 3GK group (P<0.05), were significantly lower in RSG+6GK group and INS+6GK group compared to that in 6GK group (P<0.O5).(3) The amount of apoptotic cells was positively correlated with the expression of TIPE2 (P<0.05, r=0.9421).(4) The expression of TIPE2 in the primary cultured rat hippocampal neurons can be promoted by glucose, rosiglitazone, pioglitazone, fibrillous Aβ1-40, Aβ1-40 oligomer individually (P<0.05).(5) The joint interventions of glucose and different forms of Aβ1-40 upregulated the expression of TIPE2 significantly (P<0.05), compared with individual intervention. PPARy agonist such as Rosiglitazone and Pioglitazone reduce the expression of TIPE2 induced by glucose, fibrillous Aβ1-40, Aβ1-40 oligomer (P<0.05).(6) Glucose intervened the cells led to cell apoptosis (P<0.05). Different forms of Aβ1-40 such as fibrillous Aβ1-40 and Aβ1-40 oligomer individually intervened the cells accelerated cell death (P<0.05).(7) The joint interventions of glucose and different forms of Aβ1-40 upregulated the cell apoptosis significantly (P<0.05), compared with individual intervention, rosiglitazone and pioglitazone both suppressed the cell apoptosis and cell death that accelerated by glucose and Aβ1-40 (P<0.05).Conclusion:(1) As the age growth and the progression of diabetes mellitus course, the expression of TIPE2 and cell apoptosis presented gradually increasing, prompting that the TIPE2 participate in diabetic central nervous system injury.(2)The rosiglitazone and insulin can reduce the expression of TIPE2 and cell apoptosis in the GK rats’brain, prompting the common antidiabetics can both reduce the glucose and inhibit the inflammation reaction.(3) The amount of apoptotic cells was positively correlated with the expression of TIPE2, prompting that TIPE2 promotes cell apoptosis in brain.(4) The joint interventions of glucose and different forms of Aβ1-40 induce the expression of TIPE2 and cell apoptosis in the primary cultured rat hippocampal neurons more than glucose, fibrillous Aβ1-40 and Aβ1-40 oligomer treated individually. That prompts the diabetes caused diabetic central nervous system injury by both high glucose and Aβ1-40.(5)The rosiglitazone and pioglitazone both suppressed the expression of TIPE2 and cell apoptosis that accelerated by glucose and Aβ1-40, prompting that the PPARy agonist inhibit the diabetic central nervous system injury caused by both high glucose and Aβ1-40.