Shifting Bacterial Communities In The Stomach

Changes to the microbial community of the stomach may be the reason behind why conditions that are related are associated with different risk levels and types of gastric tumors as published in PLOS Pathogens.

Infections or autoimmune diseases with Helicobacter pylori bacteria can damage the stomach and reduce gastric acid secretions. They may have similar effects but each of these conditions is associated with an increased risk of a different type of gastric tumor. Medications called proton pump inhibitors will also reduce gastric acid secretion without increasing the risk of cancer.

Stomachs are known to be host to bacterial communities. The reduction in gastric acids can alter the environment in the stomach causing changes in the types and levels of microbes found within the stomach. It was hypothesized by researchers at the University of Liverpool that the microbes that are found to be living within the stomach may explain the differences in tumor risk associated with the different causes to the reduction of gastric acids.

Stomach biopsies were taken from 95 individuals with different conditions. The samples were analyzed to investigated how tumor risks were influenced by changes in microbial communities. To determine which bacterial species were living within the stomachs of individuals that were healthy, had reduced gastric acid secretions, and were receiving PPIs the researchers used genetic sequencing techniques.

It was found that individuals with autoimmune disease had increased levels of bacteria and diversity as those of healthy individuals with different types of dominate bacteria in the community. Individuals with H.pylori infection had decreased levels and less types of bacteria than those of healthy individuals. Individuals receiving PPIs had similar microbial communities as seen in those of healthy individuals, even with reduced secretions.

Each type of patient had dominant biochemical processes associated with the communities that were observed by the researchers. These differences and their effects on the stomach may explain why autoimmune disease is more typically associated with neuroendocrine tumors, and H. pylori is more typically associated with the cancer gastric adenocarcinoma. 3 specific conditions were all observed to result in decreased acid levels, causing different changes to the composition of the bacteria found in the stomach.

These findings could be used to be built upon to eventually lead to the development of new methods that may possibly prevent cancer with the manipulation of the microbial communities within the stomach.