title: Defect in activation-induced cell death in non-obese diabetic (NOD) T lymphocytes.
abstract: Activation-induced cell death (AICD) represents a major means of peripheral tolerance induction, eliminating effector cells. NOD mice, a widely used model for autoimmune diabetes, are characterized by high levels of circulating T lymphocytes and by resistance to several apoptosis-inducing signals. The aim of this study was to analyse AICD in peripheral NOD T lymphocytes. First, we demonstrated in an in vitro AICD model that NOD T lymphocytes are more resistant to AICD (64+/-2%) compared to non-autoimmune C57BL/6 T lymphocytes (73+/-2%), but also diabetes-resistant NOR T lymphocytes (76+/-3%, P<0.05). Moreover, both CD4(+)and CD8(+)subsets were affected. Analysis of the cellular and molecular pathways revealed lower caspase 8 levels, a central caspase proximally involved in the AICD-pathway (fluorescence of 258+/-47 in NOD vs. 441+/-16 in NOR and 414+/-61 in C57BL/6 T lymphocytes, P<0.05). Gene expression analysis using real-time RT-PCR additionally revealed low expression of Fas and FasL, the death receptor system activating caspase 8 and contributing to AICD. Additionally, low IL-2 levels, together with high TGFbeta and Bclx-L levels, confirm the presence of a NOD-specific AICD-resistance profile. In conclusion, we present cellular and molecular evidence for disturbed AICD mechanisms in NOD T lymphocytes. This resistance in AICD may contribute to defective tolerance induction to autoantigens in NOD mice.
authors.affiliation: Laboratory for Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Decallonne
authors.forename: Evelyne
authors.initials: E
authors.lastname: van Etten
authors.forename: Annapaula
authors.initials: A
authors.lastname: Giulietti
authors.forename: Kristina
authors.initials: K
authors.lastname: Casteels
authors.forename: Lutgart
authors.initials: L
authors.lastname: Overbergh
authors.forename: Roger
authors.initials: R
authors.lastname: Bouillon
authors.forename: Chantal
authors.initials: C
authors.lastname: Mathieu
mesh_terms: D000818:Animals; D017209:Apoptosis; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000473:pathology*; D053222:Fas Ligand Protein; D005260:Female; D015870:Gene Expression; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000235:genetics; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D011236:Prediabetic State / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology*; D016212:Transforming Growth Factor beta / Q000235:genetics; D051020:bcl-X Protein; D019014:fas Receptor / Q000235:genetics
chemical_list: C494812:Bcl2l1 protein, mouse; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D051020:bcl-X Protein; D019014:fas Receptor; C505526:Casp8 protein, mouse; D053181:Caspase 8; D020169:Caspases