Pathogenic mechanisms of postinfectious functional gastrointestinal disorders: results 3 years after gastroenteritis.

Functional gastrointestinal disorders (FGID) may appear after acute gastroenteritis. The aim of this study was to evaluate the possible mechanisms (inflammation, visceral hypersensitivity, psychological and immunogenetic factors) related to the development of postinfectious (PI) FGID 3 years after a Salmonella outbreak. Biopsies of the antrum, and right- and left colon from 16 PI-FGID patients, 8 PI control patients, and 18 healthy controls (H-controls) were processed for immunohistochemistry, cytokines, and mast-cell electron microscopy. DNA was typed for cytokine gene polymorphisms. Visceral sensitivity (satiety test and rectal barostat) and psychological factors (SCL-90 and vital events) were assessed. The number of mast cells and T lymphocytes was similar among the groups in all locations. Mast cells within 5 microm of nerve fibers of both PI groups were increased compared to H-controls: (stomach: 5.6+/-1.2 versus 6.6+/-1.5 versus 2.5+/-1.1; right colon: 9.7+/-1.3 versus 8.0+/-1.3 versus 4.1+/-1.7; left colon: 8.9+/-0.9 versus 8.5+/-1.8 versus 2.2+/-2.0 per field) (p<0.05). No differences in the production of IL-1beta, IL-1ra, IL-6, and IL-10 or in their genotypes were found. PI-FGID patients showed a lower pain threshold to rectal distention (29+/-2 versus 37+/- 2 mmHg; p<0.05). Scores for anxiety (0.63+/-0.11 versus 0.28+/-0.14) and somatization (1.01+/-0.15 versus 0.45+/-0.15) were higher in PI-FGID patients than in PI controls (p<0.05). The number of stressful life events was not significantly different between both PI groups. Three years after salmonellosis, PI-FGID patients showed no evidence of inflammation in the gastric or colonic mucosa, but visceral sensitivity and anxiety/somatization levels were increased. The close anatomical mast cell-nerve fibers relation does not seem to be related to the FGID but to the infection itself.