Inhibition of inflammatory cytokine-induced response in human islet cells by withaferin A.
BACKGROUND
After islet cell transplantation, a substantial mass of islets are lost owing to nonspecific inflammatory reactions. Cytokine exposure before or after transplantation can upregulate expression of proinflammatory genes via the nuclear factor-kappaB signaling pathway, eventually resulting in islet loss.


OBJECTIVE
To test the effects of a naturally occurring nuclear factor-kappaB inhibitor, withaferin A, on regulation of inflammatory genes in human islets.


METHODS
Human pancreatic islets were isolated using a modified Ricordi protocol. Purified islets were cultured for 2 days. The effect of withaferin A treatment on islet cell viability was examined using the fluorescein diacetate-propidium iodide dye exclusion test, and on function using a static glucose stimulation assay. Islet cells were treated with a cytokine mixture (50 U/mL of interleukin-1beta, 1000 U/mL of tumor necrosis factor-alpha, and 1000 U/mL of interferon-gamma) for 48 hours with or without withaferin A, 1 microg/mL. Treated islets were used for real-time polymerase chain reaction (PCR) array analysis for expression of inflammatory genes, and expression of other selected genes was analyzed using real-time PCR with single primers.


RESULTS
Glucose stimulation and viability assays demonstrated that withaferin A was not toxic to islet cells. Of 84 inflammation-related genes examined using real-time PCR array analysis, 9 were significantly upregulated by cytokine treatment compared with the control group. However, addition of withaferin A to the culture significantly inhibited expression of all genes.


CONCLUSIONS
Withaferin A significantly inhibits the inflammatory response of islet cells with cytokine exposure.
Peng
H
H
Institute of Biomedical Studies, Baylor University, Waco, Texas, USA.
Olsen
G
G
Tamura
Y
Y
Noguchi
H
H
Matsumoto
S
S
Levy
M F
MF
Naziruddin
B
B
D002102:Cadaver; D018929:Cell Culture Techniques; D002469:Cell Separation / Q000379:methods; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D016207:Cytokines / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000517:prevention & control*; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D016381:Islets of Langerhans Transplantation / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014019:Tissue Donors; D054358:Withanolides / Q000494:pharmacology*
D016207:Cytokines; D054358:Withanolides; D005947:Glucose; C009684:withaferin A