despite an overall inhibition in host cell protein synthesis. Stxl-induced enhancement of mRNA stability is involved in the induction of both IL-8 and GRO-e mRNA, and may be involved in superinduction. High concentrations of Stxl were required to induce ENA-78 mRNA (1-100 ,~g/mL), but Stxl can superinduce ENA-78 at lower concentrations (10 ng/ ml). Conclusion: Shiga toxins are able to increase mRNA levels of multiple C-X-C chemokines in lEGs, as well as protein expression of IL-8 and GRO-e, Increasing mRNA stability is at least one mechanism that is involved. Shiga toxin treatment results in accumulation of large amounts of ENA-78 and GRO-otmRNAs when cells are concomitantly exposed to TNF-ot. In the case of ENA-78, superinduction occurs even when induction does not. Taken tog~her, these data suggest that Stxl treatment of lEGs may stimulate a proinflammatory response similar to that seen with bacterial invasion. We hypothesize that the ribotoxic stress response is a pathway by which Shiga toxins can alter host signal transduction in intestinal epithelium, resulting in the production of multiple chemokine mRNAs. The potential roles of the Stx- induced ribotoxic stress response and chemokine induction and superinduction are discussed in relation to HUS pathogenesis. 3812 Increased Ion Transport Is Due To Upregulated CyclooxygenaseActivity In Salmonella Infected Human Intestinal Xenogrefls Lone S. Bertelsen, Guenther Paesold, Lars Eckmann, Kim E. Barrett, UCSD Sch of Medicine, San Diego, CA Enteric Salmonella infections are accompanied by marked inflammation and diarrhea, yet little is known about the effects of Salmonella on intestinal epithelial physiology. Since animal tissues are not optimal models due to significant species differences, and cell lines lack relevant cell-cell interactions, we have previously described a human-derived model using fetal intestinal tissues grown as xenografts in SCID mice. Here, we investigated effects of Salmonella typhimurium SL1344 on ion transport in such xenograffs. Harvested xenografts were stripped of seromuscular layers by blunt dissection, infected with Salmonella and mounted in modified Ussing chambers. S. typhimurium infection increased baseline ion transport compared to controls (40.5-+4.8 vs. 11.9-+8.5/~cm 2, n=6, p<O.01) at 1 h of infection, but no differences in conductance or gross changes in morphology were seen. Infection of xenografts in the presenceof indomethacin (10/~M) inhibited the increasein baselinesecretion by 85.7+6.9%, n = 8. Further, when xenografts were stimulated with either the Ca 2+-dependent agonist carbachol (CCh) (-52.1_+20.4 mV/cm2 vs -22.4_+11.4 mV/cm2, n =4, p<O.05) or the cAMP-dependent agonist prostaglandin E2 (PGE2) (-61.9-+9.2 mV/cm2 vs. -9.5_+8.2 mV/cm2, n=3, p<O.01), ion transport, measured as the decrease in potential difference (PD), was increased following 2 h of S. typhimurium infection compared to controls. This increase was diminished by 39.5_+13.6% and 42.2_+14.7%, n=3, for PGE2and CCh, respectively, in the presence of indomethacin. Western blot experiments revealedthat infection was accompanied by increased COX-2expression (151%, 223%, and 303%, at 30, 60, and 120 rain of infection, respectively, n = 2) compared to controls, with no change in COX-1 levels. Histological exami- nation of infected xenografts showed little or no appreciable invasion of the tissue by S. typhimurium up to 2 h. In summary, S. typhimurium rapidly increases basal as well as Ca 2+ and cAMP stimulated ion transport in human intestinal xenograffs. These effects are likely dependent on an increase in COX-2 levels. We conclude that Salmonella infection increases COX-2 expression in human intestinal tissue, and that this contributes to increased epithelial ion transport characteristic of infectious diarrhea. 3813 Determinants of inducible Heat Shock Protein Expression in Normal Colonic Mucosa: Role of Immune and Enteric Bacterial Flora in Regulating Hsp72 and Hsp25 Expression Keishi Kojima, Mark W. Musch, Hongyu Ren, David R. Boone, Averil Ma, Eugene B. Chang, Univ of Chicago, Chicago, IL BACKGROUND: Inducible heat shock proteins (hsp), particularly hsp72 and hsp25, have an important role in protecting the viability and function of intestinal epithelial cells against inflammation-associated injury. Interestingly, they are "constitutively" and predominantly expressed by surface epithelium of normal colonic mucnsa, i.e. cells closest to the relatively hostile luminal environment. AIMS: Becausethe expression of these proteins often require environmental stimuli, we explored the possibility that immune and/or bacterially-derived signals are determinants of inducible hsp expression in colonocytes. METHODS: The expression of inducible hsp72 and hsp25 and constitutive hsc73 were studied in intestinal mucosa of immunodeficient RAG-1-/- mice and control and germ-free gnotobiotic C57BL/6 (B6, back- ground strain) mice, as well as in murine colonic (YAMC) epithelial cells in vitro. YAMC cell monolayers were co-cultured with splenic or lamina propria lymphocytes (LPLs) activated by anti-CD3 and CD28 antibody. RESULTS:By western blot and immunohistochemistry, inducible hsp72 and hsp25 are expressed in the normal colonic epithelium, but not small intestine. In contrast, in RAG-1 -/ mice, colonic hsp72 expression was decreased, hsp25 increased, and hsc73 unchanged. Interestingly, in germ-free gnotobiotic B6 mice, hsp72 expression was slightly increased and hsp25 expression exhibited a greater increase, suggesting additional factors. Following induced differentiation of YAMC, a small amount of hsp72 and hsp25 was expressed under basal condition. Co-culture with activated splenocytes or LPLs significantly increased inducible hsp expression compared to co-culture with non-activated immune cells. Furthermore, IL-2, TNF-o~and tL-lO also induced both hsps, whereas IL-4 had no effect. The IL-2 effect was significantly inhibited by IL-2 blocking antibody. CONCLUSIONS: The expression of colonic hsp72 in situ appearsto be dependenton cytokines provided by colonic lymphocytes, whereas the role enteric bacterial flora still remains undefined. We believe these activating signals are important in maintaining inducible hsp expression of normal colonocytes, rendering them more resistant to potentially injurious agents or conditions. 3814 The Infection with Helicobacterpylori cag-PAl+ Strains Modulates in vivo Interleukin-4 mRNA Expression in Human Gastric Mucosa Barbara Orsini, Barbara Ottanelli, Univ of Florence, Florence italy; Stefano Censini, Chiron Vaccines, Siena Italy; Giulia Pellegrini, Monica Nuti, Manuela Ortolani, Elisabetta Surrenti, Stefano Milani, Calogero Surrenti, Univ of Florence, Florence italy Background Intedeukin-4 (tL-4) is a pleiotropic cytokine that plays a critical role in the regulation of human immune response. We investigated IL-4 mRNA expression in human gastric mucosa in relation to the infection with Helicobacterpylori (Hp)strains carrying the pathogenicity island cag (cag-PAI), a 40 Kb DNA locus responsible for increased virulence. Methods cag-PAI status was determined by PCR directly on gastric antrum biopsies from 15 Hp+ patients with non- ulcer dyspepsia (NUD). Four healthy volunteers were also recruited as controls.Three genes were selected in cagl ° region (cagA, cagE, cagl) and two (cagT, virB11 homologue)were chosen in cagll° region, respectively.The presence of IS605, the presence/absence and genetic organization of cag-PAI were also established. IL-4 gene tran- scription was analyzedby ISH with ~S-UTP RNA probes. A computerized video image analyzer was used to measure the authoradiographic signal for IL-4. The severity and the activity of gastritis were evaluated in accordance with the updated Sydney system. Hp density was also determined by IF for Urease. Results cag-PAI was present in 9/15 (60%) NUD patients. IL- 4 mRNA expression was observed exclusively in gastric cells of the surface of epithelium and pits in controls. In addition to this site, all Hp+ patients showed many non-epithelial cells expressing IL-4 mRNA in the lamina propria. The intensity of the autoradiographic signal was decreased in cag-PAI+ patients as compared with cag-PAl-, both on epithelial and non- epithelial cells (p < 0.005). The grade of inflammation and Hp density were enhanced in cap PAl + patients ( p< 0.005). Conclusion Our data, documenting a modulation of the inflamma- tory response in cag-PAI+ infections by a decrease of IL-4 mRNA expression, suggest that ca#-PAI genes may be of importance with regard to the clinical outcome of Hp infection. 3815 The Effects of Chronic Schistosomiasis on Murine Holicobactnr Induced Gastritis Jean E. Crabtree, Michelle Court, St James's Hosp, Leeds United Kingdom; Marjorie M. Walker, Imperial Coil Sch of Medicine, London United Kingdom; Patricia S. Coulson, York Univ, York United Kingdom; Sian Coggle, Imperial Coil Sch of Medicine, London United Kingdom; Philip A. Robinson, Danuta Sosnoskwa, St James's Hosp, Leeds United Kingdom; John L. Telford, Chiton Vaccines, Siena italy Introduction: In developing countries coinfection with multiple bacterialand parasitic pathogens is common. Divergent immune polarizing effects (Thl/Th2) or cross reacting antigens in co- infecting pathogens may modulate the outcome of gastric Helicobacter infection. Aims: To assessthe effects of Schistosomamansoniinfection on Helicobacterinduced gastric pathology in a mouse model. Methods: Female C57BL/6 mice were infected percutaneously with 25 S. mansoni cercariae. Three weeks later S. mansoni infected mice and uninfected controls were orally challenged 3 times with H. fells. At 10 weeks animals were sacrificed and H. fells infection confirmed by biopsy urease test and histology. Gastric pathology was scored for 4 regions, the cardia, corpus, transitional zone and antrum. In parallel experiments S. mansoni worm pairs were counted following portal perfusion and hepatic schistosome ova quantified histopathologically and by tissue digestion. Results: The gastric mucosa of uninfected and S. mansoni infected mice was histologically normal. Comparison of the gastric pathology in H. fells versus H. felis/S, mansoni infected animals showed that bacterial density (mean --- SEM 6.8--0.94 v 6.0-+0.5), activity (5.3-+2.33 v 4.38-+1.65) and chronic (7.11-+0.87 v 6.87-+1.06) inflammatory scores were not significantly different. In contrast atrophy and mucous cell hyperplasia were observed in 4/8 (50%) of co-infected mice and in 0/9 (0%) of mice with H. fells infection (p < 0.03, Fisher's exact test), in 3 of 4 dual infected mice with atrophy schistosome ova were present in the gastric mucosa. No significant differences in S. mansoni worm burden or density of hepatic ova were observed in H. fells infected and uninfected mice. Conclusions: These studies show that co-infection with S. mansoniincreases Helicobacter-induced atrophy and mucous cell hyperplasia. This may be a consequence of cross-reacting anti-Lewis X antibodies induced by S. mansoniinfection. This study was funded by the European Commission 3816 Correlation Between CD4 Count and H, pylori in HIV+ Patients Ana Luiza Wemeck-Silva, Ruth Moreira Leite, Marco Zambrano Nunez, Univ of Sag Paulo - AIDS's House, Sag Paulo Brazil; Aytan Miranda Sipahi, Ademon O M C Damiao, Univ of Sag Paulo - Scb of Medicine, Sag Paulo Brazil; David Everson Uip, Univ of Sag Paulo - AIDS's House, Sag Paulo Brazil Background and Aim: Some investigators have claimed that HIV + patients with CD4 count > 200 have a higher prevalence of H. pylori infection than those with CD4 count < 200 (Cacciarelli et al., 1996, Paolo et al., 1997). However, this is not universally accepted (Talal et al., 1999). Thus, we have studied this possible correlation in a large group of HIV+ patients, much greater than the usual numbers presented in the previous studies. Material and Methods: 628 (334 men and 194 women), mean age 38, RIV+ patients with epigastric pain, underwent upper endoscopy (EGD). None of the patients were taking proton pump inhibitor. All of them had CD4 counts measured.Two antrum biopsies were taken and examined after hematoxylin-eosin and Giemsa staining. Results: EGD: Gastric mucosa hiperemia without erosion in 207 (39.3%) and with erosion in 94 (17.8%), ulcer in 10 (1.8%), ulcerative lesions in 3 (0.6%). Duodenal erosions in 97 (18.5%) and ulcer in 14 (2.6%). Histology: Chronic active gastritis in 459 (86.9%). In the group with CD4 > 200 (n=360), the frequency of H. pylori was 38.3%. In patients with CD4 count -< 200 (n = 168), H. pylori infection was seen in 19.0% (p< 0.01). Conclusion: We found a direct correlation between CD4 count and H. pylori infection in HIV+ patients. Since patients with low CD4 count take many antibiotics, the antibiotic inhibitory effect is difficult to eliminate. However, most of the patients with CD4 < 200 in our study have taken trimethoprim/sulfamethoxazole which does not erradicate the A-707