Sa.126. FTY720 Ameliorates Pathogen DrivenIleitis in C57BL/6 Mice by Impeding LymphocyteTraffickingDaniel Mielcarz,1 David Foureau,1 Laurence Menard,1 JavierOchoa-Repáraz,1 Dominique Buzoni-Gatel,2 Lloyd Kasper.11Dartmouth Medical School, Lebanon, NH; 2Institut Pasteur-INRA, Paris, France

We investigated the effect of impeding lymphocytetrafficking with FTY720 in the immune regulation of anexperimental model of pathogen-driven inflammatory boweldisease (IBD). Inbred B6 mice develop an acute necrotizingileitis 7-9 days following oral infection with Toxoplasmagondii. A hallmark of this ileitis is a massive infiltration oflymphocytes and subsequent production of Th1 cytokines.The parasite driven ileitis has both morphologic andimmunologic features consistent with human Crohn's dis-ease. FTY720 is a sphingosine-1-phosphate (S1P) analoguethat binds to S1P receptors. Lymphocytes require signalingthrough S1P1 to leave the lymph node following encounterwith antigen. Treatment with FTY720 reduced clinical signsof ileitis in T. gondii infected mice, as demonstrated byreduced weight loss as well as fewer morphologic andpathologic changes associated with inflammation in thesmall intestine. Chimeric mice were generated in which thehematopoietic cells were GFP+ in order to visualize thetrafficking of lymphocytes following infection and treat-ment. FTY720 treated mice showed reduced numbers ofCD4+ lymphocytes in both the small intestinal lamina propriaand in the brain following infection. Reduced Th1 cytokineexpression as well as an increased parasite burden in thesmall intestine was observed in the FTY720 treated group.Interestingly, the brain parasite burden of treated miceshowed a lower parasite burden indicating an inhibition oflymphotcyte trafficking by FTY720. These results indicatethat FTY720 may be a promising treatment for IBD.

doi:10.1016/j.clim.2008.03.347

Sa.127. Expression of FOXP3+CD4+CD25+Regulatory T Cells in Patients with InflammatoryBowel DiseaseSara Ciullini Mannurita, Eleonora Gambineri, Lucia Bianchi,Gloria Serena, Paolo Lionetti, Anna Maria Gelli, ChiaraAzzari, Maurizio de Martino. University of Florence,Florence, Italy

FOXP3+CD4+CD25+ regulatory T cells play a key role inregulation of immune responses. To date there are few studiesthat describes their potential function in human inflammatorybowel disease (IBD), although it has been demonstrated thatthis T cells subset can prevent experimental murine colitis. Inthis study 14 patients affected by IBD (9 patients withUlcerative Colitis and 5 with Crohn's disease), and 8 healthysubjects were enrolled. Peripheral blood mononuclear cells(PBMCs) were analysed by flow cytometry to evaluate FOXP3+CD4+CD25+ regulatory T cells. First the frequency of CD4+CD25+bright lymphocytes subset was examined, then we

evaluated FOXP3 expression calculating the mean fluores-cence intensity (MFI). Statistic analysis was performed byStudent's t-test. We observed a higher CD4+CD25+brightexpression in IBD patients than in healthy subjects (3,13±1,26% vs 1,50±0.53%, p=0,002), but a lower FOXP3 expressionboth in CD4+CD25+ total population (MFI=5,19±1,8 vs 7,20±1,79 pb0.05) and in CD4+CD25+bright subset (MFI=9,56±2,83vs 13,80±3,96 pb0.02) in IBD patients compared to healthysubjects. Moreover this analysis was performed comparingeach group of patients affected by the same disease with thenormal subjects and similar results were obtained. Althoughpatients with IBD showed an increased number of CD4+CD25+bright, probably due to a steady-state activation, lower FOXP3levels were found in this cell subset compared to healthysubjects, suggesting that impaired expression of FOXP3 maybe responsible of the immune imbalance in IBD. Furtherstudies to confirm these preliminary findings and to testFOXP3 function both on peripheral blood and mucosallymphocytes are currently ongoing.

doi:10.1016/j.clim.2008.03.348

Sa.128. Simultaneous Oral Gluten and MicrobialExposure Increases Systemic Cytokine Suppressionin a MHC Class II Dependent MannerSusan Barton, Eric Marietta, Marshall Behrens, MelissaJacobson, Kerryl Piper, Joseph Murray, Chella David. MayoClinic, Rochester, MN

Celiac disease (CD) is an autoimmune enteropathy of theproximal small bowel that is strongly associated with DQ2/DQ8 HLA genotypes. Prevotella organisms have been identi-fied in increased numbers in the stool of celiac patients. In anattempt to develop a murine model of enteropathy for CD,Prevotella species (PS) and Prevotella melaninogenica (PM)cultured from the proximal small bowel of celiac diseasepatients were introduced via oral gavages into AeoDQ8transgenic mice with or without the introduction of oralgluten feeding. All the mice had been weaned and maintainedon a gluten free diet. The three experimental groups were: nobacteria and no dietary gluten (control group), bacteria alone,and bacteria plus initiation of a gluten-containing diet. Noenteropathy developed. Rather there was high level suppres-sion of the following cytokines in the sera in both series afterthe administration of both dietary gluten and bacteria (meanreduction): IFNγ (↓51%), IL-12p70 (↓56%), IL-17 (↓64%), TNFa(↓62%), IL-6 (↓61%), IL-10 (↓61%), IL-13 (↓64%). In comparison,Aeo-/- mice had decreased suppression of serum cytokineswhen co-administered gluten and bacteria. This would suggesta role for MHC class II. Feeding PS or PM bacteria with dietarygluten resulted in an increase in splenic CD4+CD25-FoxP3+ T-cells. These findings suggest that there is systemic cytokinesuppression generated in response to simultaneous gluten andmicrobial antigen exposure in the context of the glutensensitive associated MHC genotype DQ8 that may reflect agluten augmented probiotic effect.

doi:10.1016/j.clim.2008.03.349

S122 Abstracts