Oral Bacteria Invades Gut Of Liver Cirrhosis Patients

The gut microbiota of liver cirrhosis patients is disrupted, with a large influx of normally harmless bacteria found in the mouth.

AsianScientist (Jul 25, 2014) – A metagenomic study has shown that the gut of liver cirrhosis patients is invaded by bacteria normally found in the mouth. The study documenting these findings has been published in Nature.

The ability to conduct high throughput sequencing and advanced metagenomic analytical techniques have spurred the investigation of the role that the gut microbiota plays in chronic diseases. Diverse diseases ranging from obesity to inflammatory bowel disease and diabetes have all been associated with changes in gut bacteria composition.

The present study, led by Professor Li Lanjuan at Zhejiang University, shows that changes in the gut microbiota are also associated with liver cirrhosis. Liver cirrhosis is the scarring of the liver seen in patients with advanced liver disease. Caused by factors such as hepatitis infection, alcohol abuse and obesity, liver cirrhosis is an irreversible chronic disease, with liver transplantation being the only option for patients at the late stage of disease.

Prof. Li and her group investigated the bacterial composition of 98 Chinese patients with liver cirrhosis compared to 83 healthy controls. In agreement with existing data, they found that healthy individuals had a similar composition and diversity of microbiota, even when compared to a study involving a Danish population. However, patients with liver cirrhosis had much fewer types of bacteria, with an average of 389,000 genes compared to 497,000 genes in the healthy controls.

Significantly, the authors were able to identify 15 microbial genes which discriminate between healthy and cirrhotic patients with high specificity. These genes could be used as a marker to monitor and prevent liver cirrhosis.

A closer analysis of bacterial species showed that liver cirrhosis patients had a disproportionately high number of commensal bacterial normally found in the mouth, such as Veillonella and Streptococcus. The authors suggested that altered bile production by the cirrhosis-damaged livers rendered the gut more permissible to foreign bacteria and allowed oral bacteria to invade the gut via food. Furthermore, patients with higher amounts of oral bacteria in the gut were shown to have worse symptoms, suggesting that the invading bacteria actively play a role in the progression of the disease.

The article can be found at: Qin et al. (2014) Alterations of the Human Gut Microbiome in Liver Cirrhosis.

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Rebecca did her PhD at the National University of Singapore where she studied how macrophages integrate multiple signals from the toll-like receptor system. She was formerly the editor-in-chief of Asian Scientist Magazine.

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