Cholera toxin subunit B inhibits IL-12 and IFN-{gamma} production and signaling in experimental colitis and Crohn's disease.
OBJECTIVE
Cholera toxin B subunit (CT-B) is a powerful modulator of immune responses. The authors have previously demonstrated that oral administration of recombinant CT-B (rCT-B) is able to prevent and cure the Crohn's disease (CD)-like trinitrobenzene sulfonic acid (TNBS) mediated colitis. In this study they extended their observations and examined if rCT-B interferes with the molecular signaling underlying the Th1 type response both in TNBS colitis and in ex vivo human CD explants.


METHODS
TNBS treated mice were fed with rCT-B, and IFN-gamma and IL-12 production by colonic lamina propria mononuclear cells (LPMC) was examined by ELISA. In vitro culture of mucosal explants from CD patients and non-inflammatory bowel disease controls, pre-incubated with rCT-B, were examined for IFN-gamma and IL-12 production by ELISA and semiquantitative reverse transcription polymerase chain reactions. STAT-1, -4, -6 activation and T-bet expression were examined following rCT-B treatment by western blotting both in TNBS treated mice and in human mucosal explants.


RESULTS
rCT-B significantly reduced IL-12 and IFN-gamma secretion by LPMC from TNBS treated mice. Consistent with this, rCT-B inhibited both STAT-4 and STAT-1 activation and downregulated T-bet expression. Inhibition of Th1 signaling by CT-B associated with no change in IL-4 synthesis and expression of active STAT-6 indicating that rCT-B does not enhance Th2 cell responses. Moreover, in vitro treatment of CD mucosal explants with rCT-B resulted in reduced secretion of IL-12/IFN-gamma and inhibition of STAT-4/STAT-1 activation and T-bet expression.


CONCLUSIONS
These studies indicate that CT-B inhibits mucosal Th1 cell signaling and suggest that rCT-B may be a promising candidate for CD therapy.
Coccia
E M
EM
Department of Infectious, Parasitic and Immune-mediated diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Remoli
M E
ME
Di Giacinto
C
C
Del Zotto
B
B
Giacomini
E
E
Monteleone
G
G
Boirivant
M
M
D000328:Adult; D000818:Animals; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000276:immunology*; D003092:Colitis / Q000276:immunology*; D003424:Crohn Disease / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D018928:Immunity, Mucosal; D007371:Interferon-gamma / Q000096:biosynthesis*; D018664:Interleukin-12 / Q000096:biosynthesis*; D007413:Intestinal Mucosa / Q000276:immunology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008875:Middle Aged; D009924:Organ Culture Techniques; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000276:immunology; D050797:STAT4 Transcription Factor; D015398:Signal Transduction / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology; D015534:Trans-Activators / Q000378:metabolism
D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D050797:STAT4 Transcription Factor; C494090:STAT4 protein, human; C494091:Stat4 protein, mouse; D015534:Trans-Activators; D018664:Interleukin-12; D007371:Interferon-gamma; D002772:Cholera Toxin