Expression of Transient Receptor Potential Vanilloid 1, 4 Ion Channels in the Human Gastric Mucosa

Pathophysiological classification of gastritis is a controversial issue, which is still inconsistent in the literature. The importance of sensory-immune interactions in these processes have recently been emphasized with special focus on Transient Receptor Potential ion channels, such as Vanilloid 1, 4 and Ankyrin 1 (TRPV1, TRPV4, TRPA1) localized predominantly on capsaicin-sensitive peptidergic sensory nerves. They are activated by a variety of exogenous spices and endogenous inflammatory mediators and play an important role in thermo and pain sensation, as well as neurogenic inflammation. They have also been described on several non-neural cells, but their functional significance is unknown. Therefore, we aimed to investigate the expression of these TRP receptors in the human gastric mucosa and their alterations in chronic gastritis. Gastric mucosal biopsies were collected during upper gastrointestinal endoscopy from patients with different symptoms and complaints. Non-inflamed control and chronic gastritis samples with (IM +) or without intestinal metaplasia (IM -) were selected after histopathological evaluation. The isolated RNA samples were reversed transcribed and quantitative polymerase chain reactions were performed. TRPV1, TRPV4, and TRPA1 specific primers were used to amplify genes of interest, while beta-2-microglobulin and ribosomal protein L29 primers were used to amplify the reference genes. Messenger RNAs of TRPV1, TRPV4 and TRPA1 were all similarly detectable in the non-inflamed, as well as in the chronically inflamed gastric mucosa samples. However, it should be mentioned that the average Ct values of the reactions suggest a lower expression for TRPV4 and TRPA1 mRNA compared to that of TRPV1. Relative expressions of the TRPV1 were by 0.2- and 0.45 folds less abundant in the IM + and IM- gastritis samples, respectively, than in the control samples. In the IM- gastric samples TRPA1 and TRPV4 transcription levels did not show alterations. Interestingly, in IM + samples a 1.46-fold increase of TRPA1, whereas a 0.68-fold decrease of TRPV4 mRNA expressions were detectable compared to the control samples, but these alterations were not statistically significant. Further investigations are in process to analyze the expression of these receptors in reactive and chronic active gastritis, as well as to determine their localization with immunohistochemistry and functional relevance using animal models. Support: Richter Gedeon Talentum Foundation; SROP