Teeth can give a lot of information about a person including age, identity, diet, and health. The health of your teeth can give clues to your overall health, and even give clues to health issues that did not originate in the mouth. Some conditions such as cardiovascular disease, respiratory infections, and diabetes are related to poor oral health. Now researchers from the University of Michigan (U-M) Medical and Dental School discovered that inflammatory bowel disease (IBD) that included Crohn’s disease and ulcerative colitis, may be the latest condition made worse by poor oral health.
The mouse study titled, “The intermucosal connection between the mouth and gut in commensal pathobiont-driven colitis,” is published in Cell and led by Nobuhiko Kamada, PhD, assistant professor of internal medicine in the division of gastroenterology.
IBD is a term for two conditions, Crohn’s disease and ulcerative colitis. It is characterized by inflammation of the gastrointestinal tract. The exact cause of IBD is unknown and affects an estimated three million adults in the United States.
During Kamada’s studies of the gut microbiome, he noted a link between an overgrowth of foreign bacterial species in the guts of people with IBD—bacteria that are normally found in the mouth. This prompted Kamada to contact the dental school to learn more. “I decided to approach the dental school to ask the question, does oral disease affect the severity of gastrointestinal diseases?”
“The precise mechanism by which oral infection contributes to the pathogenesis of extra-oral diseases remains unclear. Here, we report that periodontal inflammation exacerbates gut inflammation in vivo,” the researchers wrote.
The study revealed two pathways where oral bacteria worsened gut inflammation. In the first pathway, periodontitis leads to an imbalance in the normal healthy microbiome found in the mouth, with an increase of bacteria that cause inflammation to the gums. These bacteria then make their way to the gut.
“Periodontitis leads to expansion of oral pathobionts, including Klebsiella and Enterobacter species, in the oral cavity. Amassed oral pathobionts are ingested and translocate to the gut, where they activate the inflammasome in colonic mononuclear phagocytes, triggering inflammation,” noted the researchers.
“The normal gut microbiome resists colonization by exogenous, or foreign, bacteria,” explained Kamada. “However, in mice with IBD, the healthy gut bacteria are disrupted, weakening their ability to resist disease-causing bacteria from the mouth.”
The second pathway revealed that periodontitis activates the immune system’s T cells in the mouth. Those T cells travel to the gut where they, also worsen inflammation.
“In parallel, periodontitis results in generation of oral pathobiont-reactive Th17 cells in the oral cavity. Oral pathobiont-reactive Th17 cells are imprinted with gut tropism and migrate to the inflamed gut. When in the gut, Th17 cells of oral origin can be activated by translocated oral pathobionts and cause development of colitis, but they are not activated by gut-resident microbes.”
“This exacerbation of gut inflammation driven by oral organisms that migrate to the gut has important ramifications in emphasizing to patients the critical need to promote oral health as a part of total body health and wellbeing,” stated William Giannobile, the William K. and Mary Anne Najjar professor of dentistry, chair of the department of periodontics and oral medicine at the U-M School of Dentistry, and co-author of the study.
The researchers noted that their findings study implies that clinical outcomes in IBD may be improved by monitoring oral inflammation, and may give hope for those patients whose treatments fail and lead to reduced quality of life and eventual surgery.
