AGA Abstracts a significant increase in PELI1 mRNA expression. PELI1 knock-down inhibited TLR2- mediated activation of NF-κB and the IL-8 promoter in response to Pam 2 CSK 4 and H. pylori LPS. Conversely, TRIB3 knock-down enhanced NF-κB and IL-8 promoter activity in response to Pam 2 CSK 4 and H. pylori LPS. Furthermore, over-expression of TRIB3 resulted in a dose dependent inhibition of the activating properties Pam 2 CSK 4 and H. pylori LPS. Conclusions: PELI1 positively regulates TLR2-mediated signaling in response to H. pylori LPS, while TRIB3 has a negative effect. Further studies are required to investigate the expression of these proteins in gastric epithelial cells from H. pylori-infected patients. By identifying new regulators of H. pylori-induced cell signaling events, potential therapeutic targets to treat H. pylori-associ- ated disease may be revealed. T1637 Gastric Carcinoma Patients Have a Specific Cytokine Profile Characterized By Strongly Increased Levels of Treg Cytokines, IL-1β, IL-6, IL-8 and IL-23 and Decreased Levels of IL-1α, IL-12p70, IFN-γ and TNF-α Dulciene M. Queiroz, Andreia Maria C. Rocha, Fabricio F. Melo, Gifone A. Rocha, Sérgio A. Batista H. pylori (HP) infection is the leading cause of gastric carcinoma (GC), the second cause of cancer mortality worldwide. Because GC is asymptomatic or oligosymptomatic in most of the cases, the diagnosis is delayed which contributes to the poor prognosis. Thus, finding bacterial and host markers that predict who will progress toward the disease is desirable. We evaluated the serum/tissue cytokine levels linked to the innate and adaptive immune responses in HP+ patients with gastritis (n=100), distal GC (n=100) and asymptomatic blood donors (BD, 150 HP+ and 50 HP-). HP and CagA status was determined by ELISA in BD. In the patients, cagA status was determined by PCR and cagA 3' variable region by PCR/ sequencing. Gastric tissue (pg/mg of protein) and serum (pg/mL) cytokine levels were determined by ELISA (Biosource). The cytokine profile of GC was characterized by significant (p<0.001) increased levels of TFGβ (16.0 and 26.1 fold more compared with gastritis and HP+BD, respectively), IL-10 (7.5 and 8.8) and IL-2 (4.0 and 5.7) and decreased IFNγ levels (2.4 and 3.7 fold less), being the IL-2 positively correlated with IL-10, suggesting a regulatory role for IL-2. The serum levels of IL-1β (3.7 and 5.8), IL-6 (11.6 and 4.7), IL-8 (9.3 and 10.9), and IL-23 (7.1 and 17.9) were also strongly augmented (p<0.001 for all), but the levels of pro-inflammatory cytokines related to the innate immune response [IL-1α (4.9 and 1.9 fold decreased in gastritis and BD respectively), IL-12p70 (1.7 and 1.9) TNFα (1.9 in gastritis)] were significantly decreased. Concerning the bacterium cagA EPIYA motifs, increased number of C segments was associated with GC (p<0.001). In the gastritis group, patients infected with HP strains containing more than one EPIYA-C segment had higher tissue (p=0.008) and serum (p=0.002) levels of IL-23 and serum levels of IL-12p70 (p= 0.02). In the GC patients the number of EPIYA-C segments was positively associated with IL-23 (p=0.01) and inversely associated with IFNγ (p=0.004).levels. cagA+ status was associ- ated with increased serum and tissue levels of IL-8 (p<0.001), IL-12p70 (p<0.001) and IL- 23 (p=0.02) as well as with gastric concentration of NFΚB (p<0.001). Otherwise, in the BD, cagA+ status was associated with increased levels of IL-8 (p<0.001) only. Concluding, patients with GC have a specific cytokine profile characterized by increased regulatory cytokines that may contribute for the decreased levels of some pro-inflammatory cytokines that are involved in defense against tumor. Also, cytokines associated with neutrophil recruitment, IL-8 and IL-23, were increased and associated with cagA status and EPIYA-C motif number.(CNPq/FAPEMIG) T1638 The Role of Mast Cells in Vaccine-Induced Protective Immunity Against Helicobacter pylori Hua Ding, Thomas G. Blanchard, John Nedrud, Barry K. Wershil, Steven J. Czinn Aims: Mast cells play a role in host defense against bacteria by several different mechanisms in addition to IgE-mediated degranulation. Bacteria and host cytokines influence mast cell to recruit neutrophils through the production of TNFα. The goal of this study is to evaluate the contribution of mast cells to H. pylori immunity in a model of vaccine-induced protection. Methods: Mast cell deficient Kitsl/sl-d and control mice were immunized with 100μg H. pylori sonicate and 5μg cholera toxin and challenged by oral gavage with 1 x 107 CFU H. pylori SS1 strain. Stomachs were collected at multiple time points for quantitative culture of H. pylori, histological evaluation of granulocytes, and for measurement of IL-17, TNFα, CD4, Ly-6G and F4/80 mRNA by real-time PCR. Recall assays were performed on spleen cells of some immunized/unchallenged mice. For In Vitro studies, bone marrow derived mast cells (2 x 105 cells) were stimulated with lysate from H. pylori SS1, H. felis, or one of five other H. pylori strains (based on cagA or vacA gene status). Supernatants were collected at 3, 6, 24 and 48 hours for detection of TNFα, IFNγ, IL-10, CXCL1/KC, MIP-2 and LIX by ELISA. Results: Bacterial clearance was observed at two weeks post challenge in mast cell deficient mice. Bacterial load was reduced in immunized wild type mice by 4.0 log CFU and by 1.4 log CFU in deficient mice. No mast cells were observed in Kitsl/sl-d mice. The number of neutrophils in the gastric mucosa of immune Kitsl/sl-d mice was lower than that in immune wild type mice, although the difference was not significant. Immunized mast cell deficient and wild type mouse spleen cells both produced IFNγ in response to stimulation. IL-17, TNF-α and CD4 mRNA levels in gastric tissues were significantly lower in immune Kitsl/sl-d mice compared to wild type mice (p<0.05). F4/80 (macrophage) and Ly-6G (neutrophils) mRNA was lower in Kitsl/sl-d mice compared to wild type mice, but not significantly. TNF-α, CXCL1/KC, MIP-2 and LIX level were detected in the supernatants after 24 hours in a dose-dependent manner, but there were no detectable IFNγ and IL-10 products. TNFα was observed in the supernatant of cells stimulated with H.felis and all strains of H. pylori. Conclusions: Mast cells contribute vaccine-induced protective immunity against H. pylori but are not essential for reducing the bacterial load, and lack of mast cells does not diminish the memory T cell response to immunization. Mast cells can be stimulated to produce TNFα, KC, and MIP-2 with H. pylori lysate through a non-IgE mediated pathway and may play a role in promoting the inflammation that ultimately eradicates H. pylori. A-548 AGA Abstracts T1639 Helicobacter pylori vacA Intermediate Region i1 Strains Are Associated with More Severe Histological Features of Chronic Gastritis and Increased Gastric Carcinoma Risk in Portugal Rui M. Ferreira, Fatima Carneiro, Darren Letley, John C. Atherton, Ceu Figueiredo Background and Aims: The Helicobacter pylori vacuolating cytotoxin gene vacA is present in all strains and is polymorphic at the signal (s) and mid (m) regions. Functionally, vacA s1/m1 strains cause more extensive vacuolation and in a wider range of epithelial cell lines than s1/m2 strains, and s2/m2 strains are non-vacuolating. Clinically, vacA s1/m1 strains are associated with gastric atrophy, intestinal metaplasia and gastric carcinoma. Recently, a new polymorphic region within vacA designated intermediate (i) region, was described as a major determinant of vacA toxicity, and vacA i1 strains were associated with gastric carcinoma. The aim of this study was to characterize the vacA i region in strains infecting Portuguese patients in order to explore the relationship between i region genotypes and (1) the histological features of gastritis, and (2) the risk for gastric carcinoma. Materials and Methods: 154 H. pylori-infected patients were studied, 106 with chronic gastritis and 48 with gastric carcinoma. Histological parameters were scored according to the updated Sydney system. DNA isolated from gastric biopsies and from surgical specimens was used directly for PCR. Genotypes were determined by reverse hybridization on a line probe assay for vacA s and m regions, and by type-specific PCR for vacA i region. Results: vacA i region was successfully genotyped in 97.4% strains. 53 (35.3%) cases were multiple for vacA s, m, or i regions. In the 97 cases of single vacA genotypes, 42 (43.3%) were s1/m1, 45 (46.4%) were s2/m2, and 10 (10.3%) were s1/m2. In agreement with previous descriptions, s1/m1 strains were predominantly i1 (41/42) and only one s1/i2/m1 strain was found. Also, the great majority of s2/m2 strains were i2 (44/45) and a single s1/i2/m1 strain was found. s1/m2 strains were genotyped as i1 (9/10) or i2 (1/10). In chronic gastritis patients, vacA i1 strains were significantly associated with higher degrees of corpus chronic inflammation and polymorphonuclear activity (P=0.0006 and P=0.002, respectively). vacA i1 strains were also associated with the presence of corpus and antral epithelial damage (both P<0.0001), and with glandular atrophy and intestinal metaplasia (P=0.0016 and P=0.0043, respectively). No associations were observed between i region genotypes and H. pylori colonization density. vacA s1, m1, and i1 strains were strongly associated with gastric carcinoma (all P<0.0001). Conclusions: H. pylori vacA i1 strains are associated with more severe histological features of chronic gastritis and increased gastric carcinoma risk in the Portuguese population. Acknowledgments: Fundação Calouste Gulbenkian (Proj. 76448) T1640 Structure-Function and Clinical Relationships of Helicobacter pylori vacA Hiroaki Ogiwara, Mitsushige Sugimoto, Tomoyuki Ohno, Ratha-korn Vilaichone, Varocha Mahachai, David Y. Graham, Yoshio Yamaoka Introduction: The vacuolating cytotoxin of Helicobacter pylori, VacA, induces cytoplasmic vacuolation in gastric epithelial cells. The vacA intermediate (i) region is suggested to be a third polymorphic determinant of VacA activity with the prevalence of vacA i1 genotype reported to be higher in gastric cancer and peptic ulcer than in non-ulcer dyspepsia in Western population. We studied whether a deletion of approximately 81-bp between vacA i- and middle (m) region (denoted as d-region) in the vacA gene is associated with 1) other vacA genotypes, 2) with clinical outcome, and/or 3) with gastric mucosal injury in Western and East Asian populations. Methods: We used PCR to examine the vacA signal (s), m-, i- and d-region genotypes and cagA status in H. pylori isolated from Western (n = 266) and East Asian (n = 244) and their association with gastroduodenal diseases and histological scoring. Results: Overall, the vacA s-, m-, i- and d-region genotypes as well as cagA status were significantly correlated with one another among Western strains. In East Asian countries, the relationships between vacA genotypes and clinical outcomes or histopathological changes could not be examined because of the high prevalence of high one genotype. In Western countries, strains with vacA s1, m1, i1 or d1 (no deletion) genotype were significantly associated with gastric cancer compared with presence of the s2, m2, i2 or d2 genotypes, respectively (adjusted OR [95% CI] = 3.17 [1.07-9.45] for s1, 10.65 [3.36-31.35] for m1, 8.57 [2.85-25.81] for i1, and 8.04 [2.67-24.16] for d1). The putative high virulent vacA s- , m-, i- and d-region genotypes was associated with a significantly enhanced neutrophil infiltration as well as with gastric atrophy using univariant analysis; whereas in multiple linear regression analysis only the vacA d-region genotype was significantly associated with neutrophil infiltration and gastric atrophy in both the antrum and the corpus. Conclusions: The genotype of the vacA d-region may be a marker for high risk of clinically significant gastroduodenal diseases. However, future studies using isogenic d-region mutated strains will be necessary to understand the biological roles of the d-region. T1641 The Role of Homb in the Clinical Outcomes of Helicobacter pylori Infection Sung Woo Jung, Mitsushige Sugimoto, David Y. Graham, Yoshio Yamaoka Introduction: The hom family of Helicobacter pylori proteins is a small paralogous family that contains a C-terminal alternating hydrophobic motif and characteristic signal sequences typical of outer membrane proteins. The homB gene has been suggested as a novel virulence factor. However, there are only a few studies investigating the role of homB on H. pylori related disease. We investigated the relationship between the presence of homB and clinical outcome. Methods: We evaluated the presence of the homA, homB and cagA genes in 276 strains isolated in the US and Colombian populations (126 with gastritis, 86 with duodenal ulcer and 64 with gastric cancer) by a PCR. The results were compared with the clinical presentation. Results: The prevalence of the homA and homB genes was 61.2% and 62.3%, respectively. The prevalence of homB gene was higher in gastric cancer strains (71.9%) than in duodenal ulcer strains (54.7%) (p = 0.03). The presence of cagA was weakly, but significantly correlated with the presence of homB (r = 0.304, p < 0.01). The prevalence of cagA+homB+ strains was also significantly higher in gastric cancer strains (67.2%) than that in duodenal ulcer strains (50%) (p = 0.04), while cagA+homB- strains showed a tendency to favor duodenal