UB Member of "Salivation Army" Looks at Link Between Saliva and Good and Bad Bacteria in Mouth

BUFFALO, N.Y. -- An oral biologist working in a field that has dubbed itself the "salivation army," Stefan Ruhl says many of his colleagues prefer more glamorous research topics than his chosen area of investigation.

But Ruhl, an assistant professor in the Department of Oral Biology, School of Dental Medicine, says surprisingly little is known about the biological mechanisms by which saliva -- or "spit" -- plays a crucial role in oral health.

"The mouth is the main entrance to the body's interior and saliva plays a role not only in helping to process food, but also in protecting the inner surfaces of the mouth," says Ruhl, who joined the UB faculty last fall after nearly 10 years on the faculty at the University of Regensburg, Germany.

"Every day we swallow about a liter of saliva," he adds, "so it must have some physiological function."

Ruhl's specific interests center on the interaction in the mouth of saliva and oral microbes, or "microflora" -- bacteria that can boost resistance to harmful pathogens, including those that cause such conditions as gastritis, a leading cause of stomach ulcers and even stomach cancer.

"There are certain molecules in saliva that protect," he says. "And then there are others -- mostly proteins -- that support the establishment of a good or beneficial microflora. This creates a milieu, or environment, that protects the host from the settlement of pathogens. If you hadn't the good bacteria, you would get fungal diseases and viral diseases much more, so saliva is important in modulating microbial colonization."

But, he says there remains much to explore about the relationship between harmful bacteria and saliva. For instance, Ruhl points out that research he performed at the University of Regensburg found some but no clear connection between the presence of Helicobacter pylori -- a bacteria that causes chronic gastritis, stomach ulcers and cancer -- in the mouth versus the stomach of patients visiting a gastroenterology practice, illustrating just how unclear the connection between oral bacteria and more serious forms of infection remains in many patients. The problem is similar to the yet unexplained observation that some people can eat a lot of sweets and remain immune from the cavities that plague their more cautious counterparts, he says, noting that different patients simply seem more susceptible to certain bacteria than others.

"There remain unexplored host factors," he adds, "and one of them could be saliva."

Ruhl suspects the proteins in human saliva that act as receptor sites for specific bacteria -- some beneficial, some harmful -- are the key to the mystery. While in Germany, he participated in a project funded by the German Research Foundation and the German Society of Dental Oral and Craniomandibular Sciences to identify the myriad proteins found in human saliva, as well as to investigate the mechanics by which they repel or attract specific bacteria, including not only Helicobacter pylori, but also protective microflora such as oral viridans streptococci and actinomyces.

"The basic idea behind all of this is to know which structures are responsible for adhesion of these bacteria," he says. "Looking into the future, [researchers] could maybe then design analogues…to prevent colonization by bad bacteria -- the pathogens -- or enforce colonization by physiological microflora."

Ruhl also has served as project leader on a $1.2 million, multi-institute collaborative grant from the Medical Faculty of the University of Regensburg in which his team investigated the absorption of salivary proteins and adhesion of bacteria on various chemically modified surfaces. The ultimate goal of the project, he says, was to discover materials and chemical treatments to prolong the life of various biomaterials -- such as crowns, bridges, fillings and dental or medical implants -- by repelling the harmful bacteria that cause infections at the base of such devices.

The recipient of degrees equivalent to a D.D.S. and Ph.D. in immunology from Georg-August University of Göttingen, Ruhl's first experience working in the United States came 20 years ago as a guest researcher with the National Institute of Dental and Craniofacial Research (NIDCR) in Bethesda, Md. In 1989, he joined the Division of Cytokine Biology at the federal Food and Drug Administration as a visiting associate, and later returned to the NIDCR -- also as a visiting associate -- in the laboratory of microbial ecology.

The birth of his first son, Lorenz, prompted his return to Germany in 1995. But Ruhl says that after 10 years in Germany -- during which he often visited the United States for both academic conferences and family vacations -- returning to the U.S. felt like the right choice, both personally and professionally.

"In Germany," he says, "there is no such institution as an oral biology department -- they always try to combine it with a clinic -- but people get torn apart if they have to do too many things at once and can't excel at any of them. It was always my dream to return to an oral biology group and devote myself to research because it's where I feel I can contribute something significant."

Ruhl's current position includes teaching -- this semester he helps teach a graduate course on the biological basis of oral disease -- but he no longer performs clinical work and says that UB's emphasis on research in his field is much stronger than Regensburg's.

"One reason I applied here is because UB was one of the first universities in the United States -- probably worldwide -- to found an oral biology department," he says. "It's one of the prime places for oral biology, particularly in the area where I'm working."

A resident of Williamsville, Ruhl is now the father of three sons -- Lorenz, 14; Christian, 12; and Leander, 7, with his wife, Christina. Before he made the final decision to join the UB faculty, Ruhl says his family took a grand tour of New York State that included stops along the Hudson River and in the Adirondacks, as well as the Thousand Islands and Ellicottville.

"We like the Finger Lakes region, the Great Lakes, the skiing areas -- so far there's been nothing negative," he says. "We like the life in Buffalo."