Changes in mitochondrial stability during the progression of the Barrett's esophagus disease sequence.

BACKGROUND: Barrett's esophagus follows the classic step-wise progression of metaplasia-dysplasia-adenocarcinoma. While Barrett's esophagus is a leading known risk factor for esophageal adenocarcinoma, the pathogenesis of this disease sequence is poorly understood. Mitochondria are highly susceptible to mutations due to high levels of reactive oxygen species (ROS) coupled with low levels of DNA repair. The timing and levels of mitochondria instability and dysfunction across the Barrett's disease progression is under studied. METHODS: Using an in-vitro model representing the Barrett's esophagus disease sequence of normal squamous epithelium (HET1A), metaplasia (QH), dysplasia (Go), and esophageal adenocarcinoma (OE33), random mitochondrial mutations, deletions and surrogate markers of mitochondrial function were assessed. In-vivo and ex-vivo tissues were also assessed for instability profiles. RESULTS: Barrett's metaplastic cells demonstrated increased levels of ROS (p < 0.005) and increased levels of random mitochondrial mutations (p < 0.05) compared with all other stages of the Barrett's disease sequence in-vitro. Using patient in-vivo samples, Barrett's metaplasia tissue demonstrated significantly increased levels of random mitochondrial deletions (p = 0.043) compared with esophageal adenocarcinoma tissue, along with increased expression of cytoglobin (CYGB) (p < 0.05), a gene linked to oxidative stress, compared with all other points across the disease sequence. Using ex-vivo Barrett's metaplastic and matched normal patient tissue explants, higher levels of cytochrome c (p = 0.003), SMAC/Diablo (p = 0.008) and four inflammatory cytokines (all p values <0.05) were secreted from Barrett's metaplastic tissue compared with matched normal squamous epithelium. CONCLUSIONS: We have demonstrated that increased mitochondrial instability and markers of cellular and mitochondrial stress are early events in the Barrett's disease sequence.

A Barrett's esophagus registry of over 1000 patients from a specialist center highlights greater risk of progression than population-based registries and high risk of low grade dysplasia.

Barrett's esophagus (BE) arising from chronic gastro-oesophageal reflux (GERD) is the main pathologic precursor of esophageal adenocarcinoma (EAC). The risk of progression to high-grade dysplasia (HGD) and EAC is unclear, and recent population studies from Denmark and Northern Ireland suggest that this has been overestimated in the past. No data exist from the Republic of Ireland. A detailed clinical, endoscopic, and pathologic database was established in one center as a proposed pilot for a national registry, and initial and follow-up data were abstracted by a data manager. One thousand ninety-three patients were registered, 60 patients with HGD were excluded, leaving 1033, with a median age of 59 and 2 : 1 male to female ratio, and 3599 person-years of follow-up. The overall incidence of HGD/EAC was 1.33% per year overall, 0.85% if the first year is excluded. Within the first year after index endoscopy, 18 cases of HGD or EAC were identified, and 30 following the first year. Low-grade dysplasia (LGD) on index endoscopy was associated with an incidence of progression of 6.5% per year, and 3.1% when tertiary referrals were excluded. These data provide important demographic and clinical information on the population of Irish patients with BE, with incidence rates of progression higher than recently published population-based registry series, perhaps relating to sampling and pathological assessment. Low-grade dysplasia on initial biopsy is a significant proxy marker of risk of progression.