TNF-Related Apoptosis-Inducing Ligand Death Pathway-Mediated Human Beta-Cell Destruction

Abstract

Aims/hypothesis. The aim of this study is to investigate whether apoptosis in human beta cells can be related to the induction of the tumor necrosis factorrelated 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-α, LTα1β2, LTα2β1, LIGHT, and IFN-γ. 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 betacell 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 isletcell membrane was able to increase the susceptibility of TRAIL-resistant primary islet cells to the TRAIL death pathway. Conclusion/interpretation. 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. [Diabetologia (2002[Diabetologia ( ) 45:1678[Diabetologia ( -1688

CEBPA exerts a specific and biologically important proapoptotic role in pancreatic β cells through its downstream network targets

“…TNFRSF10B was previously shown to be part of the apoptotic cascade triggered by CEBPA in a rat liver stellate cell line (Wang X et al. , 2009); it also was demonstrated to positively control TRAIL-mediated apoptosis of pancreatic β cells (Ou et al. , 2002).…”

Immune‐mediated β‐cell death in type 1 diabetes: lessons from human β‐cell lines

“…Previously, sera from patients with T1D containing islet cell antibodies (ICA) failed to react with this cell line [31], casting doubt on its antigenicity and β-cell likeness. Still, along with the human insulinoma cell line, CM [20], HP62 cells have continued to be tested as β cells in cytotoxicity assays, with responses similar to those of primary islet cells [32,33]. …”

“…The mechanism of CTL killing was not elucidated; however, transfection of the cell lines with B7-H4, an inhibitory co-signal molecule expressed on the cell surface, decreased the percent specific lysis measured, indicating that the GAD-reactive T cells killed the β cells by a mechanism requiring direct cell contact. The CM insulinoma cell line has been valuable as a β-cell model in a wide range of in vitro assays [32,33,35–39], including studies aiming to understand the effect of genetic splice variants on β-cell function [40], but not without criticism [41,42]. In addition to poor GSIS, several chromosomal abnormalities were noted in CM cells.…”

“…Only TNFα was cytotoxic to HP62 (~15% cell death) but not to CM, and the mechanism of killing remains unresolved [32]. Other groups have reported that treatment for primary islets with cytokines can trigger different apoptotic pathways.…”

Diabetes mellitus and apoptosis: inflammatory cells

“…Similarly, TRAIL-knockout mice displayed enhanced islet inflammation and earlier onset of diabetes following low doses of the b-cell toxin streptozotocin (STZ) [51]. Although most normal primary islet cells express all four TRAIL receptors [52], primary islets isolated from donors are resistant to TRAIL-induced apoptosis [53]. This may be due to the ratio of TRAIL death to decoy receptors on these cells.…”