Neutrophil-mediated injury to gastric mucosal surface cells.

Neutrophils (PMNs) have been implicated in the pathogenesis of gastritis. This study evaluates the magnitude and mode of PMN-mediated damage to gastric mucosal surface cells (GSC) in a system independent of vascular and neural factors. Rabbit GSC were freshly isolated and preloaded with 51Cr. GSC were then incubated for 1 hr or 4 hr with freshly isolated human PMNs at varying effector-to-target cell ratios. Injury to GSC was assessed as percent specific 51Cr released and by electron microscopy. We found minimal GSC injury using nonactivated PMNs. Incubation with PMNs activated with formylmethionyl-leucyl-phenylalanine (FMLP), however, resulted in significant GSC injury at the 20:1 PMN/GSC ratio, 33.2 +/- 1.8% 51Cr release (P < 0.001 compared to nonactivated PMNs). Electron microscopy revealed well-preserved gastric surface cells after exposure to nonstimulated PMNs. GSC exposed to activated PMNs (20:1 PMN/GSC ratio) were severely injured. Proteinase inhibitors and dimethylsulfoxide failed to diminish PMN-mediated GSC injury. Conversely, superoxide dismutase (SOD) inhibited GSC injury by more than 50% (P < 0.001). In addition, glutathione peroxidase inhibited injury by 84% (P < 0.001). These data suggest that neutrophil-mediated injury to gastric surface cells in vitro involves superoxide anion and hypochlorous acid and not neutral trypsinlike proteinases or hydroxyl radicals.

A neutrophil chemotactic factor present in H. pylori but absent in H. mustelae.

This study was designed to compare the capabilities of Helicobacter pylori and Helicobacter mustelae to generate neutrophil chemotactic activity (NCA) in vitro. H. pylori and H. mustelae were grown in parallel cultures under identical conditions. The cultures were washed and transferred to saline solution for 3 hr to avoid detecting nonspecific chemotactic activity from culture media. Supernatants were subjected to size-exclusion HPLC. All peaks from HPLC were collected and assayed for NCA. Peaks having significant NCA were subjected to gel electrophoresis. H. pylori generated 85.9 +/- 1.7% NCA compared to only 41.6 +/- 2.5% for H. mustelae (P < 0.001). The HPLC peak containing the highest NCA from H. pylori revealed a band on gel electrophoresis at approximately 10.5 kDa. This band was not present on gels from H. mustelae. We conclude that H. pylori produces a neutrophil chemotactic factor lacking from H. mustelae. This offers an explanation for the histologic difference between gastritides caused by these organisms.

Neutrophil chemotaxis in gastric mucosa. A signal-to-response comparison.

This prospective study compares levels of neutrophil chemotactic activity (NCA) in gastric juice to the neutrophil count in gastric biopsies. Sixty-three male patients enrolled in the study and had antral biopsies following collection of gastric juice during esophagogastroduodenoscopy. Biopsies were examined for the magnitude of gastritis, tissue PMN count, and presence of Helicobacter pylori. Secretions were assayed for neutrophil chemotactic activity. Results show an increase in NCA and in tissue PMN counts with increasing severity of gastritis. H. pylori-positive patients had higher levels of NCA and PMN than H. pylori-negative patients. Wide variability in NCA levels preclude a direct correlation between NCA and PMN counts.

Cholecystographic agents and sulfobromophthalein inhibit the binding of L-thyroxine to plasma membranes of rat hepatocytes.

Cholecystographic agents and sulfobromophthalein (BSP) cause a major discharge of labeled T4 from the liver in man in vivo. In the present study we sought to determine if this discharge is partially due to inhibition of T4 binding to plasma membrane sites. Plasma membranes were isolated from hepatocytes of female Sprague-Dawley rats, and 5'-nucleotidase levels were measured to demonstrate plasma membrane viability. Specific binding of T4 (Ka, 1.01 X 10(8) M) was confirmed by displacement of labeled T4 by unlabeled hormone (10(-10)-10(-5) M). Displacement of labeled hormone was also produced by addition of tyropanoate, iopanoate, ipodate, or BSP. At 5-mM concentrations of inhibitor, the Ka for T4 declined to 4.00 X 10(7) M with BSP, 5.07 X 10(7) M with ipodate, 5.62 X 10(7) M with tyropanoate, and 7.43 X 10(7) M with iopanoate. Thus, a portion of the discharge of hepatic T4 after administration of these agents may be due to competitive inhibition of binding to plasma membrane sites.