Insulin-Like growth factor-II (IGF-II) prevents proinflammatory cytokine-induced apoptosis and significantly improves islet survival after transplantation.
BACKGROUND
The early loss of functional islet mass (50-70%) due to apoptosis after clinical transplantation contributes to islet allograft failure. Insulin-like growth factor (IGF)-II is an antiapoptotic protein that is highly expressed in β-cells during development but rapidly decreases in postnatal life.


METHODS
We used an adenoviral (Ad) vector to overexpress IGF-II in isolated rat islets and investigated its antiapoptotic action against exogenous cytokines interleukin-1β- and interferon-γ-induced islet cell death in vitro. Using an immunocompromised marginal mass islet transplant model, the ability of Ad-IGF-II-transduced rat islets to restore euglycemia in nonobese diabetic/severe combined immunodeficient diabetic recipients was assessed.


RESULTS
Ad-IGF-II transduction did not affect islet viability or function. Ad-IGF-II cytokine-treated islets exhibited decreased cell death (40% ± 2.8%) versus Ad-GFP and untransduced control islets (63.2% ± 2.5% and 53.6% ± 2.3%, respectively). Ad-IGF-II overexpression during cytokine treatment resulted in a marked reduction in terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive apoptotic cells (8.3% ± 1.4%) versus Ad-GFP control (41% ± 4.2%) and untransduced control islets (46.5% ± 6.2%). Western blot analysis confirmed that IGF-II inhibits apoptosis via activation of the phosphatidylinositol 3-kinase/Akt signaling pathway. Transplantation of IGF-II overexpressing islets under the kidney capsule of diabetic mice restored euglycemia in 77.8% of recipients compared with 18.2% and 47.5% of Ad-GFP and untransduced control islet recipients, respectively (P<0.05, log-rank [Mantel-Cox] test).


CONCLUSIONS
Antiapoptotic IGF-II decreases apoptosis in vitro and significantly improved islet transplant outcomes in vivo. Antiapoptotic gene transfer is a potentially powerful tool to improve islet survival after transplantation.
Renal Transplantation and Immunobiology Laboratory, The Royal Adelaide Hospital, Adelaide, South Australia, Australia.
Amy
A
Hughes
Daisy
D
Mohanasundaram
Svjetlana
S
Kireta
Claire F
CF
Jessup
Chris J
CJ
Drogemuller
P Toby H
PT
Coates
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D005260:Female; D015316:Genetic Therapy; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D007371:Interferon-gamma / Q000494:pharmacology; D053583:Interleukin-1beta / Q000494:pharmacology; D016381:Islets of Langerhans Transplantation / Q000401:mortality*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D014161:Transduction, Genetic
D016207:Cytokines; D053583:Interleukin-1beta; D007335:Insulin-Like Growth Factor II; D007371:Interferon-gamma; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt