Microvascular lesions in reflux oesophagitis and Barrett's oesophagus

The utility of narrow band imaging in improving the endoscopic diagnosis of gastroesophageal reflux disease

BACKGROUND & AIMS

Narrow band imaging (NBI) facilitates mucosal surface evaluation and may improve the endoscopic diagnosis of gastroesophageal reflux disease (GERD). We investigated the utility of NBI in improving the endoscopic diagnosis of GERD when compared with conventional endoscopy.

METHODS

A total of 107 subjects (nonerosive reflux disease [NERD], 36; erosive reflux disease [ERD], 41; controls, 30) were recruited prospectively. The mucosal morphology at the squamocolumnar junction (SCJ) in GERD and controls was visualized using conventional endoscopy and NBI. The main outcome measurements were as follows: (1) The differences in mucosal morphology at the SCJ between conventional endoscopy and NBI; and (2) the differences in mucosal morphology at the SCJ between GERD and controls with NBI.

RESULTS

Micro-erosions, increased vascularity, and pit patterns at the SCJ not seen on conventional endoscopy were well seen with NBI. Compared with controls, ERD and NERD had a significantly higher prevalence of micro-erosions (ERD, 100%; NERD, 52.8%; controls, 23.3%), and increased vascularity (ERD, 95.1%; NERD, 91.7%; controls, 36.7%), but a lower prevalence of round pit pattern (ERD, 4.9%; NERD, 5.6%; controls, 70%). ERD and NERD were similar in terms of increased vascularity and pit patterns. Increased vascularity with absence of round pit pattern was useful to distinguish NERD from controls (sensitivity, 86.1%; specificity, 83.3%). Interobserver agreement was good for increased vascularity (kappa = 0.95) and micro-erosions (kappa = 0.89), but lower for pit pattern (kappa = 0.59).

CONCLUSIONS

NBI enhanced mucosal morphology at the SCJ and appeared useful for improving the endoscopic diagnosis of GERD.

Contribution of histology to the diagnosis of reflux disease

Histology in reflux disease is still regarded as having low sensitivity and specificity. During the last three decades several histological parameters have been developed, including thickness of basal cell layer, length of epithelial papillae, intraepithelial inflammatory cells and dilation of intercellular spaces. Unfortunately classification of these parameters was often not related to the clinical symptoms of the reflux affected individuals, proper control subjects were often missing and often no interobserver variation was given. Another reason for the proposed low value of biopsies is the fact that biopsies were often taken in a non-standardised way. Recent studies point towards an area of predominantly epithelial damage close to the lesser curvature or around the right oesophageal wall. In parallel, some large, careful studies carried out recently showed a good correlation with the clinical picture of reflux disease due to a standardised biopsy protocol and proper controls. But biopsies are not recommended in all routine classical cases of reflux disease since it is believed that little further information in addition to endoscopy can be obtained. However, histology can deliver much more information than the diagnosis of reflux induced lesions (e.g. the exclusion of malignancy or other oesophageal diseases).

Human esophageal microvascular endothelial cells respond to acidic pH stress by PI3K/AKT and p38 MAPK-regulated induction of Hsp70 and Hsp27

The heat shock response maintains cellular homeostasis following sublethal injury. Heat shock proteins (Hsps) are induced by thermal, oxyradical, and inflammatory stress, and they chaperone denatured intracellular proteins. Hsps also chaperone signal transduction proteins, modulating signaling cascades during repeated stress. Gastroesophageal reflux disease (GERD) affects 7% of the US population, and it is linked to prolonged esophageal acid exposure. GERD is characterized by enhanced and selective leukocyte recruitment from esophageal microvasculature, implying activation of microvascular endothelium. We investigated whether phosphatidylinositol 3-kinase (PI3K)/Akt and MAPK regulate Hsp induction in primary cultures of human esophageal microvascular endothelial cells (HEMEC) in response to acid exposure (pH 4.5). Inhibitors of signaling pathways were used to define the contribution of PI3K/Akt and MAPKs in the heat shock response and following acid exposure. Acid significantly enhanced phosphorylation of Akt and MAPKs in HEMEC as well as inducing Hsp27 and Hsp70. The PI3K inhibitor LY-294002, and Akt small interfering RNA inhibited Akt activation and Hsp70 expression in HEMEC. The p38 MAPK inhibitor (SB-203580) and p38 MAPK siRNA blocked Hsp27 and Hsp70 mRNA induction, suggesting a role for MAPKs in the HEMEC heat shock response. Thus acidic pH exposure protects HEMEC through induction of Hsps and activation of MAPK and PI3 kinase pathway. Acidic exposure increased HEMEC expression of VCAM-1 protein, but not ICAM-1, which may contribute to selective leukocyte (i.e., eosinophil) recruitment in esophagitis. Activation of esophageal endothelial cells exposed to acidic refluxate may contribute to GERD in the setting of a disturbed mucosal squamous epithelial barrier (i.e., erosive esophagitis, peptic ulceration).

Isolation and characterization of human esophageal microvascular endothelial cells: mechanisms of inflammatory activation

Gastroesophageal reflux disease is the most common malady of the esophagus, affecting 7% of the United States population. Histological assessment demonstrates classic inflammatory mechanisms including selective leukocyte recruitment and hemorrhage, suggesting a prominent role for the microvasculature. We isolated and characterized human esophageal microvascular endothelial cells (EC) (HEMEC), examined inflammatory activation in response to cytokines, LPS, and acidic pH exposure, and identified signaling pathways that underlie activation. HEMEC displayed characteristic morphological and phenotypic features including acetylated LDL uptake. TNF-alpha/LPS activation of HEMEC resulted in upregulation of the cell adhesion molecules (CAM) ICAM-1, VCAM-1, E-selectin, and mucosal addressin CAM-1 (MAdCAM-1), increased IL-8 production, and enhanced leukocyte binding. Both acid and TNF-alpha/LPS activation lead to activation of SAPK/JNK in HEMEC that was linked to VCAM-1 expression and U-937 leukocyte adhesion. Expression of constitutive inducible nitric oxide synthase in HEMEC was in marked contrast to intestinal microvascular endothelial cells. In this study, we demonstrate that HEMECs are phenotypically and functionally distinct from lower gut-derived endothelial cells and will facilitate understanding of inflammatory mechanisms in esophageal inflammation.

Effects of long-term treatment with proton pump inhibitors in gastro-oesophageal reflux disease on the histological findings in the lower oesophagus

BACKGROUND

The application of hyperplasia of the basal cell layer and elongation of the papillae in the squamous epithelium of the distal oesophagus, as histological criteria for the diagnosis of gastro-oesophageal reflux disease (GORD), continues to be controversial. An unanswered question is whether these changes may regress under long-term treatment with proton pump inhibitors (PPI). This fact prompted us to investigate the effect of PPI treatment on the histological changes observed in the lower oesophagus.

METHODS

295 patients with endoscopically confirmed erosive GORD were investigated by endoscopy/biopsy prior to and during the course of a 12-month PPI treatment regimen (8 weeks acute treatment with 30 mg lansoprazole/day followed by long-term treatment with 15 or 30 mg lansoprazole or 20 mg omeprazole/day). The parameters studied were the frequency of ulcers and erosions and the hyperplasia of the basal cell layer and elongation of the papillae prior to treatment and on day 56 (D56), after 6 months (M6) and after 12 months (M12) of treatment.

RESULTS

In the various treatment groups, the results showed no statistically significant differences. Ulcers and erosions (prior to treatment 21% and 31%, respectively) were detected statistically significantly less frequently under PPI treatment (ulcers, D56: 1%, M6 and M12, 0%; erosions, D56: 2%, M6: 4%, M12, 3%). While high-grade hyperplasia of the basal cell layer and elongation of the papillae was found in 51% of the cases prior to treatment, the corresponding figures were only 3% (D56, M6) and 2% (M12). In contrast, the percentage of cases with normal oesophageal epithelium increased from 8% before treatment to 55% (D56), 66% (M6) and 63% (M12).

CONCLUSIONS

Our study shows not only that erosions and ulcers heal under PPI treatment, but also that hyperplasia of the basal cell layer and elongation of papillae in the squamous epithelium of the oesophageal mucosa may normalize, and are thus presumably not 'normal physiological variants'.

The biopsy diagnosis of gastroesophageal reflux disease, "carditis," and Barrett's esophagus, and sequelae of therapy

Histologic changes indicative of gastroesophageal reflux disease (GERD) are found on both sides of the squamocolumnar junction (Z-line). In the gastric cardia, inflammation is found as part of GERD in the absence of Helicobacter pylori or other causes of gastritis (carditis). The squamous mucosa is the location most likely to show inflammatory changes, such as neutrophils or eosinophils, close to the Z-line, whereas traditional reactive changes in the squamous mucosa are found only in biopsies taken at least 3 cm above the Z-line. Endoscopic criteria for GERD have a morphologic counterpart in capillary congestion and hemorrhage into the papillae, which have largely been ignored by pathologists as secondary to biopsy trauma. A biopsy protocol that maximizes the chances of detecting changes of GERD is suggested. The traditional definition of Barrett's esophagus as requiring 3 cm of glandular mucosa extending into the esophagus is no longer tenable. However, even the concept of short-segment Barrett's esophagus, in which less than 3 cm of intestinalized mucosa is present, often as tongues, is being challenged because random biopsies immediately distal to the Z-line may also show intestinal metaplasia when Barrett's esophagus is unsuspected endoscopically. Moreover, it is difficult or impossible to determine whether these changes indicate the earliest lesion of Barrett's esophagus or intestinal metaplasia in native cardiac mucosa. It is suggested that Barrett's esophagus be redefined as intestinal metaplasia in the lower esophagus. It is presently unclear whether patients with such minimal Barrett's epithelium are at increased risk for adenocarcinoma or require surveillance. Successful therapy for GERD results in healing of disease in squamous mucosa and may result in regression of Barrett's epithelium. In the stomach it may be associated with temporary regression of H. pylori and associated inflammation, migration of H. pylori into the oxyntic mucosa, hypertrophy and hyperplasia of parietal cells, and a variant of fundic gland polyps. Some patients may be at risk for accelerated atrophic gastritis if inflammation is present before therapy.