CWRU dental researcher's NIDCR grant targets oral bacteria and fetal death link

July 8th, 2013
A new four-year, $1.58 million grant from the National Institute of Dental and Craniofacial Research, will allow a Case Western Reserve University School of Dental Medicine researcher to advance her work linking oral bacteria to fetal death.

The grant will support a study by Yiping Han, professor of periodontics that focuses on the prevalent oral bacteria, Fusobacterium, and several of its subspecies. The bacteria keeps the mouth's natural disease defenses working, but can also cause diseases when they enter the bloodstream and travel throughout the body, including the placenta, umbilical cord and fetus.

In prior research, Han has linked the bacteria to stillbirth, post-birth sepsis and premature births due to inflammation in the placenta, which is supposed to be bacteria-free.

Of Fusobacterium's five subspecies, two have mechanisms that allow them to leave the mouth and travel to other parts of the body, including the placenta.

"We are interested in why more of some subspecies are found in the uterus and placenta, but others never leave the mouth," Han said. "We have to find out why, and then stop them."

Until they have an answer, Han urges everyone—not just pregnant women—to maintain their oral health.

In another recent study, Han and Xiaowei Wang, postdoctoral scholar in Han's lab, found that atherosclerotic disease, adverse pregnancy outcomes, rheumatoid arthritis, inflammatory bowel disease, colorectal cancer and respiratory tract infections all had oral bacteria connections.

"Almost every disease in research literature reviewed has the presence of Fusobacterium at the diseased site," Han concluded in the study.

About 700 species of bacteria live in the mouth, according to Han. Some will never leave that environment. But others, like Fusobacterium, have developed the ability to slip between cells in blood vessel walls to enter the blood and establish "colonies" in various parts of the body—which Han has described as a key that opens the door, allowing other oral bacteria in.

Once a colony is established, Han explained, it triggers the biochemical process that creates inflammation that can develop into plaque in the heart, erosion of the bone in arthritis or bacteria in the lungs that can cause a newborn's death.

Fusobacterium also have a mechanism to attach to cell walls and set the body's immune response in motion.

Once the bacteria cause inflammation, the researchers said, they become bona fide pathogens that incite diseases.

Han, who has researched oral bacteria's link to adverse pregnancy outcomes for a decade, has made a number of discoveries over the years.

By using DNA tracking, she has linked the bacteria found in a stillborn baby to plaque in the mother's mouth. In mouse models and cord blood from human babies, Han used new DNA testing to discover many more oral bacteria are present in the placenta, amniotic fluid and cord blood than previously thought. Many of these bacteria cannot be found with traditional culture testing of amniotic fluid or blood.

The ability to identify and properly treat the bacteria could potentially prevent diseases and save lives, Han said.

Provided by Case Western Reserve University

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