Neuroimmune interactions in patients with inflammatory bowel diseases: Disease activity and clinical behavior based on Substance P serum levels

Background and aim: The neuropeptide Substance P, plays a key role in modulating neuroimmune interactions in patients with inflammatory bowel diseases. We analyzed Substance P serum levels in patients with ulcerative colitis and Crohn's disease, to detail the involvement of the neuropeptide in the pathophysiology of these disorders. Methods: Serum samples were collected from 61 patients with ulcerative colitis (24 with active and 37 with inactive disease), 66 patients with Crohn's disease (29 with active and 37 with inactive disease) and 45 healthy subjects, enrolled into the study. Neuropetide serum levels were measured by means of an ELISA/EIA. Associations with disease activity and patients clinical features were also taken into account. Results: Compared to controls, Substance P serum levels were significantly increased in both patients with ulcerative colitis and Crohn's disease, (p<0.001). In patients with ulcerative colitis, levels paralleled disease activity (p=0.014), and the amount of the neuropeptide was considerably decreased during clinical and endoscopic remission of the disease, (p=0.025). Conversely, median Substance P levels did not differ between patients with active and inactive Crohn's disease. However, levels of the neuropeptide were more often elevated in patients with inactive and stricturing/fistulizing Crohn's disease, (p=0.002). Conclusions: Data underline that Substance P might exerts important immunomodulatory functions in inflammatory bowel disease. This study suggests a potential role for Substance P serum levels in monitoring intestinal inflammation in patients with inflammatory bowel disease. © 2011 European Crohn's and Colitis Organisation.