Intraluminal pH and goblet cell density in Barrett's esophagus.

INTRODUCTION: Goblet cells in Barrett's esophagus (BE) vary in their density within the Barrett's segment. Exposure of Barrett's epithelium to bile acids is a major stimulant for goblet cell formation. The dissociation of bile acids into forms that penetrate Barrett's epithelium is known to be pH dependent. We hypothesized that variations in the esophageal luminal pH environment explains the variability in goblet cell density. The aim of this study was to correlate esophageal luminal pH with goblet cell density in patients with BE.
METHODS: A customized six-sensor pH catheter was positioned with the most distal sensor in the stomach and the remaining sensors located 1 cm below and 1, 3, 5, and 8 cm above the upper border of the lower esophageal sphincter in five normal subjects and six patients with long-segment BE. The luminal pH was measured by each sensor for 24-h and expressed as median pH. Patients with BE had four quadrant biopsies at levels corresponding to the location of the pH sensors. Goblet cell density was graded from 0 to 3 based on the number per high-power field.
RESULTS: In normal subjects, the median pH values recorded in the sensors within the lower esophageal sphincter (LES) and esophageal body were all above 5. In patients with BE, the median pH recorded by the sensor within the LES was 2.8 and increased progressively to 4.7 in the sensor at 8 cm above the LES. Goblet cell density was significantly lower in the distal Barrett's segment exposed to a median pH of 2.2 and increased in the proximal Barrett's segment exposed to a median pH of 4.4 (p = 0.003).
CONCLUSION: Patients with BE have a goblet cell gradient that correlates directly with an esophageal luminal pH gradient. This suggests that goblet cell differentiation is pH dependent and likely due to the effect of pH on bile acid dissociation.