There is growing evidence that gastroesophageal disease is influenced by the esophageal microbiome, and that commensal bacteria of the oropharynx, stomach, and colon are thought to have a role in modulatiing pathogenesis. These emerging hypotheses are based on observed changes in the composition of the esophageal ﬂora, notably, repeated observations: 1. There is an abundance of gram-positive bBacteria in the healthy esophagus. are more gram positive prevalent 2. The esophageal bacterial population becomes increasingly gram negative with disease progression. Associated with this shift to a more gram negative prevalence is an increase in the potential for the presence of antigenic lipopolysaccharide (LPS). The immunoreactivity of LPS endotoxin thought to promote susceptibility to inflammation and disease.
The pathogenesis of the more common diseases of the esophagus e.g. gastroesophageal reflux disease (GERD), esophageal dysmotility (achalasia), eosinophilic esophagitis (EoE), Barrett’s esophagus (BE), and esophageal cancer, are well-established. Emerging data suggest however, that these are all characterized by an immune-mediated inflammatory cascade, propogated by a dysbiotic state. Thereby, the ability of the healthy “normative state” to protect against foreign bacteria is compromised. This dysbiosis thereby can create adverse inflammatory or immunoregulatory responses with progression of disease.
In the normal healthy state, the esophageal microbiome is constituted in-part, by a multitude of gram positive bacteria, many of which produce antibacterial peptides called bacteriocins. Bacteriocins are selective and used to maintain population integrity by killing off foreign bacteria. When the “normative biome” is interrupted (e.g. antibiotics, medications, diet, environmental factors), the constitutional changes may allow a more hospitable imbalance favoring the proliferation of opportunistic pathogens. Therefore it seems rational that defining, perhaps that defining, perhaps cultivating, a protective bacterial community that could help prevent or mitigate inflammatory diseases of the esophagus. Furthermore, in conjunction with evidence demonstrating that some bacteriocins are cytotoxic or antiproliferative toward cancer cell lines, further exploration might provide a rich source of effective peptide-based drug targets.
Therapeutic options targeting the microbiome, including prebiotics, probiotics, antibiotics and bacteriocins, have been studied, albeit the attributable effects on the esophagus for the most part, have been unrecognized by clinicians. This review focuses on the current knowledge of the involvement of the microbiome in esophageal diseases (most notably GERD/Barrett’s esophagus/esophageal cancer) and identifies emerging new concepts for treatment.