Extragastric Gastrointestinal Manifestations of Helicobacter Pylori: Friend or Foe?

Since it was first identified in 1982, Helicobacter pylori has continued to draw attention far beyond its role in peptic ulcer disease and is now associated with a myriad of immune-mediated diseases, both inside the gastrointestinal tract (GIT), such as mucosa-associated lymphoid tissue lymphoma, and systemic diseases, such as H. pylori-associated immune thrombocytopenia. This association has ignited research into the mechanisms of H. pylori pathogenicity, especially regarding its role within a multitude of diseases outside the GIT. Despite controversies, a growing body of evidence has begun to establish potential associations between H. pylori and extragastric GIT pathologies; H. pylori has recently been associated with luminal diseases, such as inflammatory bowel diseases and coeliac disease, as well as pancreatic, hepatobiliary, and malignant diseases of the GIT. Despite the lack of conclusive evidence regarding the mechanisms of these relationships, studies have found strong associations, like the case of H. pylori and coeliac disease, while others have not discovered such connections. In addition, while studies have established positive associations between H. pylori and various extragastric diseases, other studies have found the pathogen to play a protective role in disease development. This review comments on the latest evidence that addresses the role of H. pylori in non-gastric gastrointestinal diseases, and establishes the nature of these relationships and the implications of H. pylori eradication from a clinical perspective.