A functional role of flip in conferring resistance of Crohn's disease lamina propria lymphocytes to FAS-mediated apoptosis.
OBJECTIVE
There is evidence that, in Crohn's disease (CD), lamina propria T lymphocytes (LPLs) are resistant to FAS-mediated apoptosis and that this defect contributes to the mucosal T-cell accumulation. In this study we examined the functional role of Flip, a Flice inhibitor protein, in the resistance of CD LPL to FAS-mediated apoptosis.


METHODS
Biopsy specimens and LPLs were taken from CD and ulcerative colitis (UC) patients and normal controls and analyzed for Flip by Western blotting. We also examined whether inhibition of Flip by antisense oligonucleotide restored the susceptibility of CD LPLs to FAS-induced apoptosis. LPL apoptosis was assessed by flow cytometry.


RESULTS
After FAS stimulation, the rate of apoptosis of CD3+ LPLs was higher in normal controls and patients with UC than in patients with CD. Enhanced expression of both long and short Flip isoforms was seen in biopsy specimens and purified CD3+ and CD45RO+ LPLs of CD patients in comparison with UC patients and normal controls. No increase in Flip was documented in untreated celiac disease mucosa, thus suggesting the possibility that induction of Flip in the gut does not simply rely on the ongoing inflammation. Finally, we showed that inhibition of Flip by antisense oligonucleotide reverted the resistance of CD LPLs to FAS-induced apoptosis.


CONCLUSIONS
Data suggest a role for Flip in the resistance of CD LPLs to FAS-mediated apoptosis.
Dipartimento di Medicina Interna e Centro di Eccellenza per lo Studio Delle Malattie Complesse e Multifattoriali, Università Tor Vergata, Rome, Italy.
Ivan
I
Monteleone
Giovanni
G
Monteleone
Daniele
D
Fina
Roberta
R
Caruso
Carmelina
C
Petruzziello
Emma
E
Calabrese
Livia
L
Biancone
Francesco
F
Pallone
D017304:Annexin A5 / Q000032:analysis; D017209:Apoptosis / Q000502:physiology*; D001706:Biopsy; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D018929:Cell Culture Techniques; D003106:Colon / Q000473:pathology / Q000503:physiopathology; D003424:Crohn Disease / Q000473:pathology / Q000503:physiopathology*; D005434:Flow Cytometry; D006801:Humans; D007113:Immunity, Innate; D007413:Intestinal Mucosa / Q000473:pathology / Q000503:physiopathology; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D009092:Mucous Membrane / Q000166:cytology / Q000502:physiology*; D009504:Neutrophils / Q000473:pathology; D019014:fas Receptor / Q000502:physiology*
D017304:Annexin A5; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D047908:Intracellular Signaling Peptides and Proteins; D019014:fas Receptor