title: Stimulation of CD95-induced apoptosis in T-cells by a subtype specific neutral sphingomyelinase inhibitor.
abstract: Neutral sphingomyelinase (nSMase) has been supposed to be involved in the activation of anti-apoptotic genes and, thus, could well sustain autoimmune reactions by preventing activation induced death of autoreactive T-cells. When screening cellular extracts for SMase activity in the range between pH 6.5 and 8.5 various murine tissue samples as well as cell lines of murine and human origin displayed peaks of activity, both, at pH 7.0 and 8.0. In contrast, T-cells (human T-cell lymphoma and PHA stimulated murine lymph node cells) and monocytic leukemia cells were lacking SMase activity at pH 8.0. Only one peak of activity was found at pH 7.0. Recently we described an inhibitory compound, C11AG which selectively suppresses nSMase activity. In dose-response assays using cellular extracts the pH 7.0 nSMase turned out to be almost 100-fold more sensitive to the inhibitor than the pH 8.0 nSMase. In Jurkat T-cell lymphoma cells lacking the pH 8.0 nSMase, treatment with C11AG enhanced sensitivity to apoptosis: the concentration of CD95-specific antibody anti-APO1 could be lowered by six-fold in order to induce cell death. Concomitantly the expression of the anti-apoptotic protein A1 was found to be down-regulated. In the joints of arthritic mice, apoptosis of T-cells was stimulated after application of C11AG. Accordingly, C11AG displayed curative effects on experimental arthritis: swelling and inflammation were found to be significantly alleviated.
authors.affiliation: German Cancer Research Center, Abteilung Immunregulation und Tumorabwehr, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany. e.amtmann@dkfz.de
authors.forename: Eberhard
authors.initials: E
authors.lastname: Amtmann
authors.forename: Margot
authors.initials: M
authors.lastname: Zöller
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001169:Arthritis, Experimental / Q000276:immunology / Q000378:metabolism / Q000517:prevention & control; D015153:Blotting, Western; D002457:Cell Extracts; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003601:Cytotoxicity Tests, Immunologic; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006146:Guanidines / Q000494:pharmacology; D018922:HL-60 Cells; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019169:Jurkat Cells; D007624:KB Cells; D051379:Mice; D008811:Mice, Inbred DBA; D010835:Phytohemagglutinins / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D014018:Tissue Distribution; D019014:fas Receptor / Q000276:immunology* / Q000502:physiology
chemical_list: C500287:C11AG compound; D002457:Cell Extracts; D006146:Guanidines; D010835:Phytohemagglutinins; D019014:fas Receptor; D013108:Sphingomyelin Phosphodiesterase