Nerve growth factor and Trk high affinity receptor (TrkA) gene expression in inflammatory bowel disease

Abstract

BACKGROUND Nerve growth factor (NGF), a target derived factor for survival and maintenance of peripheral and central neurones, has been implicated in several chronic inflammatory processes. AIMS To analyse the concomitant presence of NGF and its high affinity receptor TrkA in patients undergoing surgery for Crohn's disease (CD) and ulcerative colitis (UC). PATIENTS CD tissues were obtained from 33 patients and UC tissue samples from 12 patients undergoing surgery. Normal intestinal tissue samples were obtained from 30 individuals through an organ donor programme. METHODS Expression of NGF and TrkA was studied by northern blot analysis. Using in situ hybridisation and immunohistochemistry, the respective mRNA moieties and proteins were localised. Western blot analysis was used to confirm the specificity of NGF and TrkA antibodies. RESULTS In CD, NGF mRNA was increased in 60% (2.4-fold; pCONCLUSIONS The concomitant enhanced expression of NGF and its receptor suggests activation of this pathway in chronic inflammation in CD and UC. The presence of NGF and TrkA in both neural and non-neural structures in CD and UC supports the hypothesis that neuroimmune interactions occur and are activated in both disorders.