title: Soluble TNF-alpha but not transmembrane TNF-alpha sensitizes T cells for enhanced activation-induced cell death.
abstract: In addition to its proinflammatory effects, TNF-alpha exhibits immunosuppression. Here, we compared the capacities of transmembrane TNF-alpha (tmTNF) and soluble TNF-alpha (sTNF) in regulating expansion of activated T cells by apoptosis. Splenic CD4(+) T cells from wtTNF, TNF-alpha-deficient (TNF(-/-)) and TNF(-/-) mice expressing a non-cleavable mutant tmTNF showed comparable proliferation rates upon TCR-mediated stimulation. Activation-induced cell death (AICD), however, was significantly attenuated in tmTNF and TNF(-/-), compared with wtTNF CD4(+) T cells. Addition of sTNF during initial priming was sufficient to enhance susceptibility to AICD in tmTNF and TNF(-/-) CD4(+) T cells to levels seen in wtTNF CD4(+) T cells, whereas addition of sTNF only during restimulation failed to enhance AICD. sTNF-induced, enhanced susceptibility to AICD was dependent on both TNF receptors. The reduced susceptibility of tmTNF CD4(+) T cells for AICD was also evident in an in vivo model of adoptively transferred CD4(+) T-cell-mediated colonic inflammation. Hence, the presence of sTNF during T-cell priming may represent an important mechanism to sensitize activated T cells for apoptosis, thereby attenuating the extent and duration of T-cell reactivities and subsequent T-cell-mediated, excessive inflammation.
authors.affiliation: Institute of Pathology, Division of Experimental Pathology, University of Bern, Bern, Switzerland. stefan.mueller@dkf.unibe.ch
authors.forename: Stefan
authors.initials: S
authors.lastname: Müller
authors.forename: Silvia
authors.initials: S
authors.lastname: Rihs
authors.forename: Johanna M Dayer
authors.initials: JM
authors.lastname: Schneider
authors.forename: Bruno E
authors.initials: BE
authors.lastname: Paredes
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Seibold
authors.forename: Thomas
authors.initials: T
authors.lastname: Brunner
authors.forename: Christoph
authors.initials: C
authors.lastname: Mueller
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D049109:Cell Proliferation; D002469:Cell Separation; D003092:Colitis / Q000276:immunology; D005434:Flow Cytometry; D056747:Immunomodulation / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013601:T-Lymphocytes / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology* / Q000378:metabolism
chemical_list: D014409:Tumor Necrosis Factor-alpha