Role of blood glucose in cytokine gene expression in early syngeneic islet transplantation

In islet transplantation, local production of cytokines at the grafted site may contribute to the initial nonspecific inflammation response. We have determined whether the metabolic condition of the recipient modulates the cytokine expression in islet grafts in the initial days after transplantation. Normoglycemic and hyperglycemic streptozotocin-diabetic Lewis rats were transplanted with 500 syngeneic islets, an insufficient beta cell mass to restore normoglycemia in hyperglycemic recipients. The expression of IL-1beta, TNF-alpha, IFN-gamma, IL-6, IL-10, and IL-4 genes was determined by real-time PCR in freshly isolated islets, in 24-h cultured islets and in islet grafts on days 1, 3, and 7 after transplantation. IL-1beta mRNA was strongly and similarly increased in normoglycemic and hyperglycemic groups on days 1, 3, and 7 after transplantation compared with freshly isolated and cultured islets. TNF-alpha mRNA was also strongly increased on day 1, and it remained increased on days 3 and 7. IL-6 and IL-10 were not detected in freshly isolated islets, but their expression was clearly enhanced in 24-h cultured islets and islet grafts. IL-6 was further increased in hyperglycemic grafts. IL-10 expression was increased in both normoglycemic and hyperglycemic grafts on day 1 after transplantation, and remained increased in hyperglycemic grafts compared to 24-h cultured islets. IFN-gamma mRNA was barely detected in a few grafts, and IL-4 mRNA was never detected. Thus, the inflammatory response in islet grafts was maximal on day 1 after transplantation, it was sustained, although at lower levels, on days 3 and 7, and it was partly enhanced by hyperglycemia

Short term culture with the caspases inhibitor z-VAD fmk reduces beta cell apoptosis in transplanted islets and improves the metabolic outcome of the graft

In the initial days after transplantation islets are particularly vulnerable and show increased apoptosis and necrosis. We have studied the effects of caspase inhibition on this early beta cell death in syngeneically transplanted islets. Streptozotocin-diabetic C57BL/6 mice were transplanted with 150 syngeneic islets, an insufficient mass to restore normoglycemia, preincubated with or without the pan-caspase inhibitor z-VAD. fmk 2 h before transplantation. Beta cell apoptosis was increased in control islets on day 3 after transplantation (0.28 ± 0.02%) compared with freshly isolated islets (0.08 ± 0.02%, p< 0.001), and was partially reduced in transplanted islets preincubated with z-VAD.fmk 200 μM (0.14 ± 0.02%, p = 0.003) or with z-VAD.fmk 500 μM (0.17 ± 0.01%, p = 0.012), but not with a lower z-VAD.fmk (100 μM) concentration. Diabetic mice transplanted with islets preincubated with z-VAD.fmk 500 μM showed an improved metabolic evolution compared with control and z-VAD.fmk 200 μM groups. The z-VAD.fmk 500 μM group showed an overall lower blood glucose after transplantation (p = 0.02), and at the end of the study blood glucose values were reduced compared with transplantation day (15.7 ± 3.6 vs. 32.5 ± 0.5 mmol/L, p = 0.001). In contrast, blood glucose was not significantly changed in control and z-VAD.fmk 200 μM groups. Four weeks after transplantation beta cell mass was higher in z-VAD.fmk 500 μM group (0.15 ± 0.02 mg) than in the control group (0.10 ± 0.02 mg) (p = 0.043). In summary, the treatment of freshly isolated islets with the caspase inhibitor z-VAD.fmk reduced the subsequent apoptosis of the islets once they were transplanted and improved the outcome of the graft

Lesió i protecció de les cèl·lules beta en el trasplantament d'illots pancreàtics

[cat] El trasplantament d'illots pancreàtics pot ser una bona teràpia per els malalts amb diabetis mellitus de tipus 1, però hi ha alguns problemes que cal solventar abans que sigui un tractament estès. Un d'aquests problemes bàsics és la limitada disponibilitat d'òrgans, així com la pèrdua de teixit trasplantat, que es produeix tant per el rebuig com per la fallida del trasplantament. Se sap que en els primers dies posteriors al trasplantament hi ha una pèrdua d'aproximadament el 60% de la massa beta trasplantada. També es coneix que en el primer moment després del trasplantament es produeix una reposta inflamatòria inespecífica que podria ser la responsable parcial d'aquesta pèrdua. L'objectiu de l'estudi ha estat el de descriure els fenòmens inflamatoris que es produeixen en l'empelt en aquests primers dies. Més en concret, l'expressió de citocines inflamatòries i si l'expressió d'aquestes citocines estava condicionada per l'estat metabòlic del receptor, així com l'efecte de la inhibició de l'apoptosi de les cel·lules beta trasplantades. Per això, es van trasplantar animals singènics amb una massa beta insuficient per a restablir la normoglucèmia i es va mesurar l'expressió de diferents citocines inflamatòries en l'empelt. El primer dia després del trasplantament es produeix una resposta inflamatòria que dóna lloc a una elevada expressió dels gens de les citocines IL-1beta, IL-6, TNF-alfa i IL-10, i es manté, tot i que a nivells més baixos, durant la primera setmana del trasplantament. En aquests primers dies també es detecta en l'empelt la presència de les proteïnes de IL-1beta i iNOS (principal mediador de l'acció citotòxica d'IL-1beta), que principalment són expressades per els macròfags de l'empelt. La hiperglucèmia del receptor modifica de manera parcial la resposta inflamatòria, augmentant l'expressió de TNF-alfa, IL-6 i IL-10. Per a examinar l'efecte de la inhibició de l'apoptosi, es va trasplantar una massa subòptima d'illots tractats amb l'inhibidor de les caspases z-VAD.fmk a animals hiperglucèmics. Es va poder observar com aquest tractament reduïa de manera parcial l'apoptosi de les cèl·lules beta trasplantades i feia que la massa beta trasplantada es mantingués a llarg termini, la qual cosa es reflexava en una millor evolució metabòlica dels animals diabètics trasplantats.[eng] Islet transplantation is limited by the insufficient supply of islet tissue, a problem that is further aggravated by the high number of islets required for successful transplantation. Islets are particularly vulnerable in the initial days after transplantation, when more than half of the islet tissue may be lost due to increased beta-cell apoptosis and necrosis. Non-specific inflammation at the grafted site could play a role in the initial fate of transplanted islets. The aims of the study were to determine the expression of pro- and anti-inflammoymoy palaboymatory cytokine genes in the initial days after syngeneic islet transplantation, whether blood glucose modulates their expression in islet grafts, and the effect of initial apoptosis inhibition in transplanted beta cells. The inflammatory response in islet grafts was maximal on day 1 after transplantation when cytokine genes of IL-1beta, TNF-alfa, IL-6 and IL-10 were detected. It was sustained, although at lower levels, on days 3 and 7, and it was partly enhanced by hyperglycemia. At this moment, IL-1beta and iNOS proteins were also detected in, mainly, macrophages of the graft. To study the effect of apoptosis inhibition, a subobtimal beta cell mass were transplanted to hyperglycemic animals. Islets were previously incubated with caspase inhibitor, z-VAD.fmk. The treatment of freshly isolated islets with the caspase inhibitor educed the subsequent apoptosis of the islets once they were transplanted and improved the outcome of the graft

Role of blood glucose in cytokine gene expression in early syngeneic islet transplantation

In islet transplantation, local production of cytokines at the grafted site may contribute to the initial nonspecific inflammation response. We have determined whether the metabolic condition of the recipient modulates the cytokine expression in islet grafts in the initial days after transplantation. Normoglycemic and hyperglycemic streptozotocin-diabetic Lewis rats were transplanted with 500 syngeneic islets, an insufficient beta cell mass to restore normoglycemia in hyperglycemic recipients. The expression of IL-1beta, TNF-alpha, IFN-gamma, IL-6, IL-10, and IL-4 genes was determined by real-time PCR in freshly isolated islets, in 24-h cultured islets and in islet grafts on days 1, 3, and 7 after transplantation. IL-1beta mRNA was strongly and similarly increased in normoglycemic and hyperglycemic groups on days 1, 3, and 7 after transplantation compared with freshly isolated and cultured islets. TNF-alpha mRNA was also strongly increased on day 1, and it remained increased on days 3 and 7. IL-6 and IL-10 were not detected in freshly isolated islets, but their expression was clearly enhanced in 24-h cultured islets and islet grafts. IL-6 was further increased in hyperglycemic grafts. IL-10 expression was increased in both normoglycemic and hyperglycemic grafts on day 1 after transplantation, and remained increased in hyperglycemic grafts compared to 24-h cultured islets. IFN-gamma mRNA was barely detected in a few grafts, and IL-4 mRNA was never detected. Thus, the inflammatory response in islet grafts was maximal on day 1 after transplantation, it was sustained, although at lower levels, on days 3 and 7, and it was partly enhanced by hyperglycemia

Role of blood glucose in cytokine gene expression in early syngeneic islet transplantation

In islet transplantation, local production of cytokines at the grafted site may contribute to the initial nonspecific inflammation response. We have determined whether the metabolic condition of the recipient modulates the cytokine expression in islet grafts in the initial days after transplantation. Normoglycemic and hyperglycemic streptozotocin-diabetic Lewis rats were transplanted with 500 syngeneic islets, an insufficient beta cell mass to restore normoglycemia in hyperglycemic recipients. The expression of IL-1beta, TNF-alpha, IFN-gamma, IL-6, IL-10, and IL-4 genes was determined by real-time PCR in freshly isolated islets, in 24-h cultured islets and in islet grafts on days 1, 3, and 7 after transplantation. IL-1beta mRNA was strongly and similarly increased in normoglycemic and hyperglycemic groups on days 1, 3, and 7 after transplantation compared with freshly isolated and cultured islets. TNF-alpha mRNA was also strongly increased on day 1, and it remained increased on days 3 and 7. IL-6 and IL-10 were not detected in freshly isolated islets, but their expression was clearly enhanced in 24-h cultured islets and islet grafts. IL-6 was further increased in hyperglycemic grafts. IL-10 expression was increased in both normoglycemic and hyperglycemic grafts on day 1 after transplantation, and remained increased in hyperglycemic grafts compared to 24-h cultured islets. IFN-gamma mRNA was barely detected in a few grafts, and IL-4 mRNA was never detected. Thus, the inflammatory response in islet grafts was maximal on day 1 after transplantation, it was sustained, although at lower levels, on days 3 and 7, and it was partly enhanced by hyperglycemia

B-cell death and mass in syngeneically transplanted islets exposed to short and long-term hyperglycemia

We studied the effects of hyperglycemia on beta-cell death and mass in syngeneically transplanted islets. Six groups of STZ-induced diabetic C57BL/6 mice were transplanted with 100 syngeneic islets, an insufficient beta-cell mass to restore normoglycemia. Groups 1, 2, and 3 remained hyperglycemic throughout the study. Groups 4, 5, and 6 were treated with insulin from day 7 before transplantation to day 10 after transplantation. After insulin discontinuation, group 6 mice achieved definitive normoglycemia. Grafts were harvested at 3 (groups 1 and 4), 10 (groups 2 and 5), and 30 (groups 3 and 6) days after transplantation. On day 3, the initially transplanted beta-cell mass (0.13 +/- 0.01 mg) was dramatically and similarly reduced in the hyperglycemic and insulin-treated groups (group 1: 0.048 +/- 0.002 mg; group 4: 0.046 +/- 0.007 mg; P < 0.001). Extensive islet necrosis (group 1: 30.7%; group 4: 26.8%) and increased beta-cell apoptosis (group 1: 0.30 +/- 0.05%; group 4: 0.42 +/- 0.07%) were found. On day 10, apoptosis remained increased in both hyperglycemic and insulin-treated mice (group 2: 0.44 +/- 0.09%; group 5: 0.48 +/- 0.08%) compared with normal pancreas (0.04 +/- 0.03%; P < 0.001). In contrast, on day 30, beta-cell apoptosis was increased in grafts exposed to sustained hyperglycemia (group 3: 0.37 +/- 0.03%) but not in normoglycemic mice (group 6: 0.12 +/- 0.02%); beta-cell mass was selectively reduced in islets exposed to hyperglycemia (group 3: 0.046 +/- 0.02 mg; group 6: 0.102 +/- 0.009 mg; P < 0.01). In summary, even in optimal conditions, approximately 60% of transplanted islet tissue was lost 3 days after syngeneic transplantation, and both apoptosis and necrosis contributed to beta-cell death. Increased apoptosis and reduced beta-cell mass were also found in islets exposed to chronic hyperglycemia, suggesting that sustained hyperglycemia increased apoptosis in transplanted beta-cells

B-cell death and mass in syngeneically transplanted islets exposed to short and long-term hyperglycemia

We studied the effects of hyperglycemia on beta-cell death and mass in syngeneically transplanted islets. Six groups of STZ-induced diabetic C57BL/6 mice were transplanted with 100 syngeneic islets, an insufficient beta-cell mass to restore normoglycemia. Groups 1, 2, and 3 remained hyperglycemic throughout the study. Groups 4, 5, and 6 were treated with insulin from day 7 before transplantation to day 10 after transplantation. After insulin discontinuation, group 6 mice achieved definitive normoglycemia. Grafts were harvested at 3 (groups 1 and 4), 10 (groups 2 and 5), and 30 (groups 3 and 6) days after transplantation. On day 3, the initially transplanted beta-cell mass (0.13 +/- 0.01 mg) was dramatically and similarly reduced in the hyperglycemic and insulin-treated groups (group 1: 0.048 +/- 0.002 mg; group 4: 0.046 +/- 0.007 mg; P < 0.001). Extensive islet necrosis (group 1: 30.7%; group 4: 26.8%) and increased beta-cell apoptosis (group 1: 0.30 +/- 0.05%; group 4: 0.42 +/- 0.07%) were found. On day 10, apoptosis remained increased in both hyperglycemic and insulin-treated mice (group 2: 0.44 +/- 0.09%; group 5: 0.48 +/- 0.08%) compared with normal pancreas (0.04 +/- 0.03%; P < 0.001). In contrast, on day 30, beta-cell apoptosis was increased in grafts exposed to sustained hyperglycemia (group 3: 0.37 +/- 0.03%) but not in normoglycemic mice (group 6: 0.12 +/- 0.02%); beta-cell mass was selectively reduced in islets exposed to hyperglycemia (group 3: 0.046 +/- 0.02 mg; group 6: 0.102 +/- 0.009 mg; P < 0.01). In summary, even in optimal conditions, approximately 60% of transplanted islet tissue was lost 3 days after syngeneic transplantation, and both apoptosis and necrosis contributed to beta-cell death. Increased apoptosis and reduced beta-cell mass were also found in islets exposed to chronic hyperglycemia, suggesting that sustained hyperglycemia increased apoptosis in transplanted beta-cells

Short term culture with the caspases inhibitor z-VAD fmk reduces beta cell apoptosis in transplanted islets and improves the metabolic outcome of the graft

In the initial days after transplantation islets are particularly vulnerable and show increased apoptosis and necrosis. We have studied the effects of caspase inhibition on this early beta cell death in syngeneically transplanted islets. Streptozotocin-diabetic C57BL/6 mice were transplanted with 150 syngeneic islets, an insufficient mass to restore normoglycemia, preincubated with or without the pan-caspase inhibitor z-VAD. fmk 2 h before transplantation. Beta cell apoptosis was increased in control islets on day 3 after transplantation (0.28 ± 0.02%) compared with freshly isolated islets (0.08 ± 0.02%, p< 0.001), and was partially reduced in transplanted islets preincubated with z-VAD.fmk 200 μM (0.14 ± 0.02%, p = 0.003) or with z-VAD.fmk 500 μM (0.17 ± 0.01%, p = 0.012), but not with a lower z-VAD.fmk (100 μM) concentration. Diabetic mice transplanted with islets preincubated with z-VAD.fmk 500 μM showed an improved metabolic evolution compared with control and z-VAD.fmk 200 μM groups. The z-VAD.fmk 500 μM group showed an overall lower blood glucose after transplantation (p = 0.02), and at the end of the study blood glucose values were reduced compared with transplantation day (15.7 ± 3.6 vs. 32.5 ± 0.5 mmol/L, p = 0.001). In contrast, blood glucose was not significantly changed in control and z-VAD.fmk 200 μM groups. Four weeks after transplantation beta cell mass was higher in z-VAD.fmk 500 μM group (0.15 ± 0.02 mg) than in the control group (0.10 ± 0.02 mg) (p = 0.043). In summary, the treatment of freshly isolated islets with the caspase inhibitor z-VAD.fmk reduced the subsequent apoptosis of the islets once they were transplanted and improved the outcome of the graft