17beta-Estradiol protects isolated human pancreatic islets against proinflammatory cytokine-induced cell death: molecular mechanisms and islet functionality.
BACKGROUND
Proinflammatory cytokines (PIC) (interleukin-1beta, interferon-gamma, and tumor necrosis factor alpha) are released after intraportal islet transplantation lead to functional suppression and islet apoptosis. Estradiol has been shown to promote survival of cells undergoing PIC-induced apoptosis. In this study, we evaluated the effects of estradiol on isolated human pancreatic islet (IHPI) survival after exposure to PIC and analyzed potential mechanisms of action.


METHODS
Hand-picked, freshly isolated IHPI were incubated with PIC and estradiol. Viability was analyzed from single islet cells stained with ethidium bromide and acridine orange, apoptosis using a quantitative kit, NF-kappaB nuclear translocation using a promoter-Luciferase NF-kappaB responsive construct, mitochondrial permeability transition using the ApoAlert Mitochondrial kit, and caspase 9 by a fluorometric assay. In vitro functionality was examined by static incubation, and a limited number of islets were transplanted in nonobese diabetic, severe combined immunodeficient mice.


RESULTS
17beta-Estradiol induced a dose-dependent increase in islet viability, an effect partially reversed by the estrogen receptor antagonist ICI 182,780. In vitro, islets treated with estradiol presented higher stimulation index. Euglycemia was achieved in 6 of 12 animals that received estradiol-treated islets compared with 1 of 12 control animals. Lower NF-kappaB nuclear translocation, cytochrome release, and caspase 9 activation occurred in islets treated with estradiol.


CONCLUSIONS
Estradiol promoted IHPI survival and improved functionality after PIC exposure in vitro and in vivo after transplantation. The molecular mechanisms involved included a decrease in NF-kappaB nuclear translocation, decrease in mitochondrial cytochrome release, and caspase 9 activation. The use of estradiol might be beneficial in clinical islet transplantation.
Contreras
Juan L
JL
Transplant Center, University of Alabama at Birmingham, Birmingham, AL, USA. Juan.Contreras@ccc.uab.edu.
Smyth
Cheryl A
CA
Bilbao
Guadalupe
G
Young
Carlton J
CJ
Thompson
J Anthony
JA
Eckhoff
Devin E
DE
D000818:Animals; D001692:Biological Transport; D001786:Blood Glucose / Q000032:analysis; D016923:Cell Death / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D016207:Cytokines / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000601:surgery; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000601:surgery; D004958:Estradiol / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D018836:Inflammation Mediators / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects*; D016381:Islets of Langerhans Transplantation; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D016328:NF-kappa B / Q000378:metabolism
D001786:Blood Glucose; D016207:Cytokines; D018836:Inflammation Mediators; D007328:Insulin; D016328:NF-kappa B; D004958:Estradiol; D005947:Glucose