Eosinophils within the healthy or inflamed human intestine produce substance P and vasoactive intestinal peptide

The purpose of this study was to show if inflammatory cells within healthy or diseased human intestinal mucosa produce some regulatory neuropeptides. First, inflammatory cells were isolated from the intestinal lamina propria of 11 patients with ulcerative colitis or Crohn's disease. Also collected were cells from anatomically normal intestine derived from five patients requiring bowel resection for diseases not related to inflammatory bowel disease. Extracts of these isolated cells contained authentic substance P (SP) and vasoactive intestinal peptide (VIP) as shown by RIA and their elution profiles on HPLC. Immunostaining of cells from nine of 13 additional patients localized immunoreactive SP and VIP to secretory granules within most mucosal eosinophils. No other cell types stained positive. Messenger RNA encoding SP and VIP was localized to lamina propria eosinophils by in situ hybridization. Mucosa inflammatory cells, from eight of nine more patients, cultured in vitro, released detectable amounts of VIP, but not SP. It is concluded that intestinal eosinophils produce SP and VIP. Since the eosinophils store and release more VIP than SP, it is possible that VIP is the preferred secretory product.