title: Tumor necrosis factor-alpha production by human islets leads to postisolation cell death.
abstract: BACKGROUND
  Recent successes in islet transplantation highlight the importance of islet isolation by experienced centers and minimization of cell injury as crucial to the achievement of insulin independence. Islet injury may manifest as cell death by apoptosis, shorter graft survival, and the need for retransplantation. Although an inflammatory cytokine response at the graft site is known to inhibit engraftment, recent evidence indicates that islet cells may contribute to this response.
  
  
  METHODS
  Isolated human islets were cultured for up to one week in serum-free CMRL-1066 with 25 microM of tumor necrosis factor (TNF)alpha inhibitor RDP58. Gene expression was measured by reverse transcriptase polymerase chain reaction, apoptosis and TNFalpha secretion by enzyme-linked immunosorbent assay and enzyme-linked immunospot, and islet function by stimulated insulin secretion.
  
  
  RESULTS
  Isolation induced a twofold increase in TNFalpha expression between days one and three (P<0.05), while TNFalpha secretion peaked at day one. RDP58 reduced TNFalpha secretion by 70.6% (P<0.02), though TNFalpha gene expression was unaffected. RDP58 reduced the frequency of TNFalpha-secreting islets by 64.4% (P<0.05) and reduced apoptotic levels by 26.4% within 24 hr postisolation (P<0.05). The reduction in apoptosis was maintained throughout the week (P<0.01), while apoptosis increased in control cultures. Finally, RDP58-treated islets displayed increased insulin secretion in response to both elevated glucose (1915.0+/-396.6 vs. 825.3+/-261.1 mU/L, P<0.01) and secretagogues (2294.3+/-529.5 vs. 939.8+/-333.7 mU/L, P<0.02).
  
  
  CONCLUSIONS
  These data demonstrate that intraislet cytokine production should be considered as a factor leading to islet cell death postisolation and postengraftment, and strategies aimed at countering islet cytokine production represent a novel target for improving islet viability and function.
authors.affiliation: Department of Surgery, McGill University, Montréal, Québec, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Hanley
authors.forename: Shuqing
authors.initials: S
authors.lastname: Liu
authors.forename: Mark
authors.initials: M
authors.lastname: Lipsett
authors.forename: Mauro
authors.initials: M
authors.lastname: Castellarin
authors.forename: Lawrence
authors.initials: L
authors.lastname: Rosenberg
authors.forename: Jean
authors.initials: J
authors.lastname: Tchervenkov
authors.forename: Steven
authors.initials: S
authors.lastname: Paraskevas
mesh_terms: D000328:Adult; D017209:Apoptosis; D002102:Cadaver; D016923:Cell Death / Q000502:physiology*; D002478:Cells, Cultured; D017931:DNA Primers; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000494:pharmacology; D014019:Tissue Donors; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D017931:DNA Primers; D007328:Insulin; D010455:Peptides; D014409:Tumor Necrosis Factor-alpha; C092373:allotrap