Age-related decline in rectal mucosal lymphocytes and mast cells

Abstract

Previous studies have shown that irritable bowel syndrome declines with age and is more common in women. Recent reports suggest that some diarrhoea predominant irritable bowel syndrome patients have low-grade inflammation with increased numbers of mucosal T lymphocytes, 5-hydroxytryptamine (5-HT) containing enteroendocrine cells and mast cells. To determine whether there are age or gender-related changes in mucosal T lymphocytes, mast cells or enteroendocrine cells which might explain these findings. Forty healthy volunteers (20 subjects below 55 years of age and 20 above 55 years) free from gastro-intestinal symptoms or disease answered detailed bowel symptom questionnaires and underwent sigmoidoscopy, rectal biopsy and colonic transit measurement. Biopsies were immunostained and quantified for lamina propria and intra-epithelial T lymphocytes, mast cells and 5-HT and peptide YY enteroendocrine cells. There was a reduction in lamina propria T lymphocyte counts (P = 0.018), crypt intra-epithelial T lymphocytes (P = 0.014) and mast cells (P = 0.02) in the > 55 year group. Enteroendocrine cell numbers did not decline with age and were not related to colonic transit. There were no gender differences between any of the cells quantified. Lymphocyte and mast cell numbers decline with age in normal large bowel mucosa. Reduced numbers of mucosal inflammatory cells may influence the low-grade inflammatory response to luminal antigens and contribute to the reduction of irritable bowel syndrome observed in older subjects.