Neutrophils release soluble Fas ligand (sFasL), which can induce apoptosis in certain Fas-bearing cell types (Liles WC, Kiener PA, Ledbetter JA, Aruffo A, and Klebanoff SJ. J Exp Med 184: 429-440, 1996). We hypothesized that neutrophils could induce alveolar epithelial apoptosis via release of sFasL. A549 pulmonary adenocarcinoma cells expressed surface Fas and underwent cell death (10 +/- 7% viability) and DNA fragmentation (354 +/- 98% of control cells) when incubated with agonistic CD95/Fas monoclonal antibody (P < 0.05). Coincubation with human neutrophils induced significant A549 cell death at 48 (51 +/- 9% viability; P < 0.05) and 72 h (25 +/- 10%; P < 0.05) and increased DNA fragmentation (178 +/- 42% of control cells; P < 0.05), with morphological characteristics of apoptosis. The addition of antioxidants did not inhibit apoptosis. sFasL concentrations were maximally increased in coculture medium at 24 h (4.9 +/- 0.7 ng/ml; P < 0.05). Neutrophil-induced A549 cell apoptosis was blocked by inhibitory anti-Fas (42 +/- 6% of control cells; P < 0.05) and anti-FasL monoclonal antibodies (29 +/- 3%; P < 0.05). Human neutrophils and Fas similarly affected murine primary alveolar epithelial cell bilayers, and caspase activation occurred in response to Fas exposure. We conclude that neutrophils undergoing spontaneous apoptosis induce A549 cell death and DNA fragmentation, independent of the oxidative burst, that is mediated by sFasL.

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We describe intestinal metaplasia associated with H. pylori infection in children. Since atrophy usually precedes intestinal metaplasia in adults, we suggest that atrophy exists in children. High numbers of B lymphocytes and apoptosis in the surface epithelium are seen in patients with H. pylori infection and may be related to the development of atrophy and intestinal metaplasia.

Helicobacter pylori isolates vary between geographic regions. Certain H. pylori genotypes may be associated with disease outcome. Thirty-eight children underwent diagnostic upper endoscopy at four medical centers and were retrospectively analyzed to determine if H. pylori virulence genes were associated with endoscopic disease severity, histologic parameters, and host demographics. The H. pylori virulence genotype was analyzed by a reverse hybridization line probe assay and type-specific PCR. Endoscopic ulcers or erosions were found in 17 (45%) patients, with 13 (34%) of these patients having antral nodularity. Histological gastritis, of varying severity, was present in all children. Four patients harbored more than one H. pylori strain: one subject had both cagA ؉ and cagA-negative strains, while three patients harbored either two different cagA-negative strains (two children) or two cagA ؉ strains (one child). There were 28 (74%) cagA ؉ isolates; 19 were associated with the vacA s1b genotype, 7 were associated with the vacA s1a genotype, 1 was associated with the vacA s1c genotype, and 1 was associated with the s2 genotype. Of 14 cagA-negative isolates, 6 were vacA s2 genotype, 4 were vacA s1b, 3 were vacA s1a, and 1 was vacA s1c. Nine of ten (90%) Hispanics had similar H. pylori strains (vacA s1b,m1), and all Asian-Canadian children were infected by strains with vacA s1c genotype. No correlation between H. pylori strain and endoscopic or histopathologic abnormalities was found. This study provides a baseline framework of North American children and their H. pylori strains, serving as a powerful epidemiological tool for prospective investigations to better understand the transmission and evolution of diverse disease outcomes.