November 05, 2002 10:32 AM ET
By Merritt McKinney
NEW YORK (Reuters Health) - Bacteria that live in the intestine play an essential role in the development of blood vessels in the gut, Missouri researchers report. When researchers at Washington University School of Medicine in St. Louis raised mice in a bacteria-free environment, blood vessels in the gut did not develop until the mice were exposed to bacteria.
In an interview with Reuters Health, senior author Dr. Jeffrey I. Gordon said, "Developmental processes, such as those that we have studied, are not the exclusive responsibility of the host," for example the mouse or human body. "Environmental factors, such as gut bacteria, play an important role," he said.
That the body contains bacteria, or flora, that are helpful is not a new idea, according to Gordon.
"We have this vast community of microbes that colonize from the moment of our birth," he said. Gordon added that these microbes "bring to us a great bunch of metabolic traits that we haven't developed."
Until this latest research, led by first author Dr. Thaddeus S. Stappenbeck, it was not known that bacteria were essential for forming blood vessels in the gut. The investigators made this discovery when they compared blood vessel growth in normal mice and mice that grew up without any bacteria in the small intestine.
The growth of blood vessels in the gut was not nearly as extensive in germ-free mice as in normal mice, the researchers report in the online early edition of the journal Proceedings of the National Academy of Sciences. But normal vessel development was restored 10 days after the researchers colonized the germ-free mice with bacteria called Bacteroides thetaiotaomicron.
Next, Gordon and his colleagues discovered that antibacterial intestinal cells called Paneth cells interact with bacteria to promote the growth of blood vessels. When they genetically engineered mice to lack Paneth cells, blood vessel growth was much less extensive.
The next step, Gordon said in the interview, is to "recreate and dissect out the pathway by which bacteria are able to stimulate angiogenesis," or the formation of new blood vessels. By understanding how gut bacteria promote angiogenesis in the gut, it may be possible to identify compounds and targets that are useful for treating illnesses that affect the gut, Gordon said.
"We should turn within and look at the microbes we live with," the St. Louis researcher said.
SOURCE: Proceedings of the National Academy of Sciences Early Edition 2002;10.1073/pnas.202604299.