No abstract

Tissue accumulation of polymorphonuclear neutrophils (PMN) in Inflammatory Bowel disease (IBD) might be, in part, due to a delay in apoptotic processes associated with the effects of their specific growth factors and inflammatory cytokines. We addressed this hypothesis by examining the activity of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage CSF (GM-CSF) in the organ culture supernatants of colonic mucosal specimens and their regulatory effects on PMN apoptosis in patients with IBD. The contents of G-CSF and GM-CSF in the supernatants were measured by the enzyme-linked immunosorbent assays and PMN apoptosis was evaluated by acridine orange/ethidium bromide staining, respectively. Mucosal specimens obtained from patients with active IBD exhibited higher levels of G-CSF and GM-CSF activity than controls. Notably, the levels of G-CSF activity were approximately 1000-fold higher than those of GM-CSF activity. Freshly isolated PMN showed a time-related increase in the proportion of cells with characteristic features of apoptosis when they were incubated with the culture medium alone and exposure of PMN to recombinant G-CSF and GM-CSF caused a concentration-dependent inhibition of apoptosis. Incubation of PMN with the supernatants from patients with active IBD induced an inhibitory effect on PMN apoptosis; this effect was abrogated to a significant degree by pre-incubation of the supernatants with anti-G-CSF serum. This study suggests that PMN apoptosis may be delayed under the influence of soluble mediators, especially G-CSF, in the microenvironment of IBD-affected mucosa, thus providing possible mechanisms for tissue accumulation of PMN in IBD.

Enhanced IL-6/sIL-6R-mediated immune and inflammatory responses may be implicated, at least partly, in the continuation of intestinal inflammation in patients with IBD.

We examined secretion, mRNA expression, and histologic localization of interleukin-8 (IL-*) and growth-related gene product-alpha (GRO alpha) in the Helicobacter pylori-infected gastric antral mucosa. Antral biopsies were obtained from an area of endoscopically intact mucosa. Significantly higher levels of IL-8 and GRO alpha were secreted in organ cultures from patients with H. pylori infection, and their elevation was prominent in patients with duodenal ulcer. There was a significant association between these alpha-chemokine levels and histologic grades of activity, inflammation, and H. pylori density. In fresh antral biopsies, IL-8 and GRO alpha mRNA expression was detected more frequently in H. pylori-infected patients compared with those without infection. Immunofluorescence microscopy showed localization of IL-8 and GRO alpha proteins in gastric epithelial cells and infiltrating CD68+ macrophages. In the chemotaxis assay, a significant positive correlation was found between neutrophil migration induced by the organ culture supernatants and their contents of IL-8 and GRO alpha. After H. pylori eradication, a significant decrease was observed in IL-8 and GRO alpha levels detected in organ cultures. In conclusion, mucosal alpha-chemokine activity correlates well with histologic severity of H. pylori-associated antral gastritis and can be used to predict the effects of H. pylori eradication therapy.