Helicobacter pylori bacteria have been giving us ulcers since prehistoric times. This long-term relationship is so tight that researchers have been able to track human migration by looking at what strains of H. pylori we carry. Although it’s usually a benign relationship, in a small number of cases it can cause ulcers or even increase the risk for stomach cancer.
It’s easy to think of H. pylori as an invader that must be stopped. But sometimes it’s worthwhile to think of our bodies as ecosystems and bacteria, like H. pylori, as plucky survivors that use ingenious methods to get by.
When we change our focus this way, we can discover, as did Stanford microbiologist Manuel Amieva, MD, PhD, that the microbe isn’t just adapting to us, it's adapting us to them. A recent paper of Amieva’s in Gastroenterology shows that the bacteria may be actively modifying stem cells in our stomachs, changing these critical cells' behavior to suit H. pylori’s needs.
Amieva’s lab discovered tiny colonies of H. pylori, some consisting of only a few bacteria, hidden away at the bottom of the glands that line the stomach, right next to critical stem cells. These constantly dividing stem cells are what replenish the epithelial cells that line the stomach. As I explained in a press release about the study:
This unanticipated finding shed light on how H. pylori could influence cells to turn cancerous. Cancer is thought to develop slowly as the cell acquires mutations in the DNA that override cellular controls and increase cell proliferation. Even though H. pylori had been shown to manipulate cellular controls, the mature stomach’s epithelial cells don’t live long enough to acquire mutations.
Amieva showed a protein injected by the bacteria sent the stem cells into overdrive, resulting in extra-long, inflamed glands. That sort of uncontrolled cell division leads to mutations that over time can turn a stem cell cancerous.
Obviously these insights may lead new understanding of how to detect and fight stomach cancer. But Amieva is also interested in the techniques that H. pylori has developed to manipulate stem cells.
“The bacteria have been experimenting on us since we were humans,” he told me. “I think they have a lot of knowledge about us that we are tapping into.”
Kim Smuga-Otto is a student in UC Santa Cruz’s science communication program and a writing intern in the medical school’s Office of Communication and Public Affairs.
Previously: Image of the Week: Helicobacter pylori colonizing the stomach and Treating an infection to prevent a cancer: H. pylori and stomach cancer
Photo, of bacteria (in green) colonizing the base of the stomach glands, courtesy for the Amieva lab