GPR84 and TREM-1 signaling contribute to the pathogenesis of reflux esophagitis.

Abdel-Aziz, H., M. Schneider, W. Neuhuber, A. M. Kassem, S. Khailah, J. Müller, H. G. E. deen, A. Khairy, M. T. Khayyal, A. Shcherbakova, et al., "GPR84 and TREM-1 signaling contribute to the pathogenesis of reflux esophagitis.", Molecular medicine (Cambridge, Mass.), 2015 Nov 24.


Gastro-esophageal reflux disease (GERD) is one of the most common disorders in gastroenterology. Patients present with or without increased acid exposure indicating a non-uniform etiology. Thus the common treatment with proton pump inhibitors (PPIs) fails to control symptoms in up to 40% of patients.To further elucidate the pathophysiology of the condition and explore new treatment targets, transcriptomics, proteomics and histological methods were applied to a surgically induced sub-chronic reflux esophagitis model in Wistar rats after treatment with either omeprazole (PPI) or STW5, a herbal preparation shown to ameliorate esophagitis without affecting refluxate pH. The normal human esophageal squamous cellline HET-1A and human endoscopic biopsies were used to confirm our findings to the G-protein coupled receptor (GPR) 84 in human tissue.Both treatments reduced reflux-induced macroscopic and microscopic lesions of the esophagi as well as known pro-inflammatory cytokines. Proteomic and transcriptomic analyses identified CINC1-3, MIP-1/3α, MIG, RANTES and IL-1β as prominent mediators in GERD. Most regulated cyto-/chemokines are linked to the TREM-1 signaling pathway. The fatty acid receptor GPR84 was up-regulated in esophagitis but significantly decreased in treated groups, a finding supported by Western blot and immunohistochemistry in both rat tissue and HET-1A cells. GPR84 was also found to be significantly up-regulated in patients with grade B reflux esophagitis.The expression of GPR84 in esophageal tissue and its potential involvement in GERD are reported for the first time. IL-8 (CINC1-3) and the TREM-1 signaling pathway are proposed, besides GPR84, to play an important role in the pathogenesis of GERD.