HCl-induced inflammatory mediators in esophageal mucosa increase migration and production of H2O2 by peripheral blood leukocytes.

Jie Ma, Annamaria Altomare, Suzanne M de la Monte, Ming Tong, Florian Rieder, Claudio Fiocchi, Jose Behar, Hideo Shindou, Piero Biancani, Karen M Harnett

Abstract

Exposure of esophageal mucosa to hydrochloric acid (HCl) is a crucial factor in the pathogenesis of reflux disease. We examined supernatant of HCl-exposed rabbit mucosa for inflammatory mediators enhancing migration of leukocytes and production of H2O2 as an indicator of leukocyte activation. A tubular segment of rabbit esophageal mucosa was tied at both ends to form a sac, which was filled with HCl-acidified Krebs buffer at pH 5 (or plain Krebs buffer as control) and kept oxygenated at 37° C. The medium around the sac (supernatant) was collected after 3 hours. Rabbit peripheral blood leukocytes (PBL) were isolated and sac supernatant was used to investigate PBL migration and H2O2 production. HCl-exposed esophageal mucosa released substance P (SP), CGRP, PAF and IL-8 into the supernatant. PBL migration increased in response to IL-8 or to supernatant of the HCl-filled mucosal sac. Supernatant-induced PBL migration was inhibited by IL-8 antibodies, and by antagonists for PAF (CV3988), or neurokinin 1 (i.e. SP) but not by a CGRP antagonist. Supernatant of the HCl-filled mucosal sac increased H2O2 release by PBL that was significantly reduced by CV3988 and by a SP antagonist, but was not affected by IL-8 antibodies or by a CGRP antagonist. IL-8, PAF and SP are important inflammatory mediators released by the esophageal mucosa in response to acid that promote PBL migration. In addition, PAF and SP induce production of H2O2 by PBL. These findings provide a direct link between acid exposure and the recruitment and activation of immune cells in esophageal mucosa.

  • leukocytes
  • PAF
  • substance P
  • IL-8