U-M scientist creates first model of dynamic relationship between H. pylori bacteria and their human hosts.
ANN ARBOR---Half of all American adults have an alien life form growing in their stomachs. Most of us will live our entire lives unaware that we have been colonized by Helicobacter pylori---a species of bacteria which usually produces no symptoms, but can cause ulcers and stomach cancer in some individuals.
For a bug that is so widespread in the human population, scientists know very little about H. pylori. To learn how it coexists for long periods of time with people, University of Michigan scientist Denise Kirschner, Ph.D., created a mathematical model, based on experimental evidence, of the symbiotic relationship between bacterium and host.
Results from the model were published in an article by Kirschner and Martin Blaser, M.D., of Vanderbilt University Medical Center in the July 20 issue of the Proceedings of the National Academy of Sciences.
While several mathematical models have been developed to study the HIV virus that causes AIDS, this is the first model for H. pylori, according to Kirschner.
"The most important factor in the relationship is the capacity of the host response to the bacteria," said Kirschner, an assistant professor of microbiology and immunology in the U-M Medical School. "Some people have the ability to flush the bug from their systems and some don't. We don't know why these individual differences exist and we don't understand exactly how the host responds to H. pylori's presence. The response may or may not be directly related to the immune system."
"Everything about the model works and is consistent with indirect experimental
data," Blaser said. "We describe the initial transition from one organism to a
bloom of organisms. Then as immunity kicks in, the organisms settle down and
reach equilibrium. In essence, bacteria and host are dancing together; each one
is signaling the other."
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Contact: Sally Pobojewski
pobo@umich.edu
734-647-1844
University of Michigan
20-Jul-1999