Substance P receptor expression in patients with inflammatory bowel disease. Determination by three different techniques, i.e., storage phosphor autoradiography, RT-PCR and immunohistochemistry.

Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation accompanied by changes in motility. It is known that regulatory peptides like substance P (SP) are important pro-inflammatory peptides which are also involved in neuronal conduction. To get clues for new diagnostic and therapeutic approaches we describe the SP receptor (NK-1) distribution in IBD compared to control intestinal tissue, on mRNA and protein level by three complementary techniques. Autoradiography showed differences within the intestinal wall of control patients; mucosal binding was 17 fmol/g and muscular binding was significantly (p=0.01) higher (98 fmol/g). In inflamed specimens of patients with IBD mucosal SP binding was increased compared to controls (55+/-10 vs 18+/-4 fmol/g mucosa, p=0.002). However RT-PCR showed that the mRNA content of the NK-1 receptor in these samples was not increased. In non-inflamed samples of patients with Crohn's disease (CD) and ulcerative colitis (UC) SP binding was similar as in controls, while mRNA was significantly decreased in CD patients (0.7+/-0.02 vs 4.4+/-0.7, p=0.01) but not in UC patients (4.4+/-0.7 vs 4.1+/-1.4). Immunohistochemistry identified a broad spectrum of NK-1 receptor locations in control intestine. No aberrant expression in IBD was found. This study showed that although there was no difference in location of the SP receptors in IBD patients versus controls, the quantity of SP binding was significantly increased in the inflamed mucosa of IBD patients, while the mRNA level was not increased. Further a difference in mRNA level between non-inflamed tissue of CD and UC patients was shown, with mRNA in CD being lower. These changes in SP receptor expression during chronic inflammation suggest that SP receptors are a potential target for therapeutic regulation of the inflammatory response.

Gastrin releasing peptide receptor expression is decreased in patients with Crohn's disease but not in ulcerative colitis.

BACKGROUND: Gastrin releasing peptide (GRP) and neuromedin B are bombesin (BN)-like peptides involved in regulating motility and inflammation in the gastrointestinal tract, which may be useful in treating inflammatory bowel disease (IBD). Three bombesin-like peptide receptors have been reported, but no studies have investigated their localisation in normal and inflamed human intestine. AIM: To localise and characterise BN receptors in normal intestine and to see whether this is modified in IBD. METHODS: Full thickness intestinal tissue samples were collected from 13 patients with Crohn's disease (CD), 11 with ulcerative colitis (UC), and 19 controls. BN receptor expression was characterised and quantified with storage phosphor autoradiography using BN, GRP, neuromedin B, and the synthetic analogue BN(6-14) as ligands. RESULTS: Only BN receptor type 2 (high affinity for GRP) was present in intestinal tissue. Minimal BN binding was detected in the mucosa. In normal colonic smooth muscle, mean BN binding was 336 fmol/g tissue in longitudinal muscle, including the myenteric plexus, and 71 fmol/g in circular muscle. In CD, colonic smooth muscle BN binding was significantly decreased (longitudinal muscle, 106; circular muscle, 19 fmol/g), in contrast to UC (377 and 62 fmol/g, respectively). In CD, a small (not significant) decrease was seen in ileal muscle compared with controls (111 v 169 and 18 v 32 fmol/g tissue for longitudinal and circular muscle, respectively). CONCLUSIONS: Only the GRP receptor is expressed in human intestine; expression is highest in longitudinal muscle and myenteric plexus of the colon. Expression is decreased in inflamed and non-inflamed colon of CD, but not in UC.