NF-kappaB protects Behçet's disease T cells against CD95-induced apoptosis up-regulating antiapoptotic proteins.
OBJECTIVE
To determine whether prolongation of the inflammatory reaction in patients with Behçet's disease (BD) is related to apoptosis resistance and is associated with the up-regulation of antiapoptotic factors.


METHODS
The percentage of cell death was evaluated by flow cytometry in peripheral blood mononuclear cells from 35 patients with BD and 30 healthy volunteers. The expression levels of antiapoptotic factors and NF-kappaB regulatory proteins were measured using Western blotting and immunohistochemical analyses. To down-regulate NF-kappaB nuclear translocation, BD T lymphocytes were exposed in vitro to thalidomide and subjected to transfection with NF-kappaB small interfering RNA.


RESULTS
Although CD95 is highly expressed in BD T cells, the absence of sensitivity to CD95-induced apoptosis observed may be attributable to the inhibitory action of antiapoptotic genes. Immunoblot analysis for major antiapoptotic proteins showed considerable up-regulation of the short form of cellular FLIP (cFLIP) and Bcl-x(L) in BD activated T cells, while levels of Bcl-2, caspase 3, and caspase 8 in activated T cells from patients with BD were comparable with those in activated T cells from normal donors. Moreover, expression of IKK and IkappaB was up-regulated, whereas NF-kappaB translocated to the nucleus in BD T cells, suggesting that NF-kappaB activation may modulate the expression of antiapoptotic genes. Interestingly, thalidomide and NF-kappaB small interfering RNA down-regulated cFLIP and Bcl-x(L) expression levels and sensitized BD activated T cells to CD95-induced apoptosis.


CONCLUSIONS
Taken together, these results indicate that NF-kappaB contributes to the regulation of the apoptosis-related factors and death receptors leading to apoptosis resistance in BD T cell subsets. Our results suggest that NF-kappaB plays a crucial role in the pathogenesis of BD, and that its pharmacologic control could represent a key strategy in modulating specific immune-mediated disease.
Università di Palermo, Palermo, Italy.
Matilde
M
Todaro
Monica
M
Zerilli
Giovanni
G
Triolo
Flora
F
Iovino
Mariella
M
Patti
Antonina
A
Accardo-Palumbo
Francesca
F
di Gaudio
Maria Caterina
MC
Turco
Antonello
A
Petrella
Ruggero
R
de Maria
Giorgio
G
Stassi
D000328:Adult; D017209:Apoptosis / Q000276:immunology*; D001528:Behcet Syndrome / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D016328:NF-kappa B / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D013792:Thalidomide / Q000494:pharmacology; D014162:Transfection; D015854:Up-Regulation; D051020:bcl-X Protein; D019014:fas Receptor / Q000276:immunology*
C494811:BCL2L1 protein, human; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D051020:bcl-X Protein; D019014:fas Receptor; D013792:Thalidomide