TNF-related apoptosis-inducing ligand death pathway-mediated human beta-cell destruction.
OBJECTIVE
The aim of this study is to investigate whether apoptosis in human beta cells can be related to the induction of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) pathway.


METHODS
We examined the expression of TRAIL and TRAIL receptors in two human pancreatic beta-cell lines and in human primary islet cells using RT-PCR assays and flow cytometric analyses and tested TRAIL-mediated beta-cell destruction in (51)Cr release cytotoxicity assays, Annexin-V and APO-DIREC assays.


RESULTS
Most of the human beta cells express TRAIL receptors-R1, -R2, -R3, -R4 and/or TRAIL. TRAIL induced much stronger cytotoxicity and apoptosis to beta-cell lines CM and HP62 than did FasL, TNF-alpha, LTalpha1beta2, LTalpha2beta1, LIGHT, and IFN-gamma. The cytotoxicity and apoptosis induced by TRAIL to beta-cell lines CM were inhibited competitively by soluble TRAIL receptors, R1, R2, R3 or R4. Treatment of these beta cells with antibodies against TRAIL receptors was able to block the cytotoxicity of TRAIL to these cells. Beta-cell antigen-specific CTL (CD4(+) and CD8(+)) clones express TRAIL, suggesting that these cells are potential sources of TRAIL-inducing beta-cell destruction. Normal primary islet cells from most donors are resistant to the cytotoxicity mediated by TRAIL. However, treatment with an inhibitor of protein synthesis (cycloheximide) or with an enzyme (PI-PLC) that can remove TRAIL-R3 from the islet-cell membrane was able to increase the susceptibility of TRAIL-resistant primary islet cells to the TRAIL death pathway.


CONCLUSIONS
The TRAIL death pathway is present and can function in human islet beta cells, but unidentified inhibitors of the TRAIL death pathway are present in normal islet cells.
Ou
D
D
Department of Pediatrics, University of British Columbia, Canada. daweiou@interchange.ubc.ca
Metzger
D L
DL
Wang
X
X
Huang
J
J
Pozzilli
P
P
Tingle
A J
AJ
D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D016923:Cell Death; D002478:Cells, Cultured; D002999:Clone Cells; D003470:Culture Media / Q000378:metabolism; D016207:Cytokines / Q000494:pharmacology; D004351:Drug Resistance / Q000502:physiology; D006801:Humans; D007515:Islets of Langerhans / Q000187:drug effects / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000494:pharmacology / Q000502:physiology*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology*
D051017:Apoptosis Regulatory Proteins; D003470:Culture Media; D016207:Cytokines; D008562:Membrane Glycoproteins; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha