Enteric Helicobacter and H. pylori in chronic inflammation and cancer of the hepatobiliary tract and pancreas
Sammanfattning: The Helicobacter genus now consists of at least 26 species, with additional novel species in the process of being validated. Beyond the impact of H. pylori and human health, considerable research has focused on other Helicobacter species isolated from humans and animals and the associated natural diseases that range from subclinical inflammation to cancer in the gastrointestinal and hepatobiliary tract. The aims of this study were to investigate whether gastric (H. pylori) and enteric Helicobacter species are present and detectable in the human biliary tree and liver and to explore a possible association between these microbes and human liver and pancreas disease. Several Helicobacter species are very difficult to culture from biological samples. Therefore, PCR-based detection methods were preferred. PCR- and nucleic acid-based analyses to detect Helicobacter in fresh as well as formalin-fixed paraffin embedded preserved human tissue specimen were optimised. A multiplex PCR-denaturating gradient gel/DNA-sequencing technique that allows identification of many fastidious and non-culturable gastric and enteric Helicobacter was developed and evaluated on gastrointestinal tissue of laboratory rodents, colonised by various Helicobacter species. The presence of Helicobacter species DNA in liver transplant specimen of patients with PSC, PBC, NCLC, and normal liver correlated strongly to chronic cholestatic liver disease. H. pylori and Helicobacter sp. ‘liver’-related gene sequences were also detected in liver tissue from patients with hepatocellular- and cholangiocarcinoma, whereas liver tissue from patients with resected liver metastases from colorectal cancers were negative. Children diagnosed with various chronic liver diseases, liver toxicity damage and systemic diseases were frequently positive for the genus Helicobacter. 16S rDNA analyses showed similarity to H. pylori and the enteric species H. ganmani. H. ganmani was detected in children with chronic liver diseases. Helicobacter species were found to be associated with pancreatic cancer, but was not detectable in samples of benign pancreatic diseases and histologically normal pancreas. Unexpectedly, PCR products from stomach specimen of pancreatic cancer patients were related to sequences of enteric H. bilis, H. hepaticus, and H. ganmani. In summary, this thesis explores PCR-based methodology to detect fastidious Helicobacter species and the association between Helicobacter species and human chronic liver and pancreatic diseases.
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