A family of proteins known as interferon lambdas produced by epithelial cells in the mouth serve to protect humans from viral infection, but the oral bacteria Porphyromonas gingivalis reduces the production and effectiveness of those important frontline defenders.

“Our studies identified certain pathogenic bacterial species, P. gingivalis, which cause periodontal disease, can completely suppress interferon production and severely enhance susceptibility to viral infection,” said Juhi Bagaitkar, assistant professor in the UofL Department of Oral Immunology and Infectious Disease. “These resident oral plaque bacteria play a key role in regulating anti-viral responses.”

Bagaitkar and Richard Lamont, professor and chair of the UofL Department of Oral Immunology and Infectious Disease, led the work, with first author Carlos J. Rodriguez-Hernandez and other colleagues at UofL and at Washington University in St. Louis. The findings were published

The mouth often is a gateway into the body for viruses that infect the gastrointestinal tract and lungs such as SARS-CoV-2, human immunodeficiency virus (HIV), herpes simplex and cancer-causing viruses such as human papillomavirus (HPV).

P. gingivalis, a common oral bacterium that causes periodontal disease, has been linked to numerous other diseases, including Alzheimer’s disease and rheumatoid arthritis. Recent clinical studies have shown that immune suppression in patients with periodontitis can enhance susceptibility to HIV, herpes simplex and HPV.

Improved understanding of how interferons provide broad antiviral protection and activate antiviral genes to protect us from viruses, as well as how P. gingivalis compromises their protection, may lead researchers to clinical approaches to increase that protection.

Research at UofL has revealed connections between P. gingivalis and multiple other diseases and conditions, including rheumatoid arthritis, Alzheimer’s disease and esophageal cancer.

Bagaitkar was one of the first junior faculty members whose research was supported by the Center of Biomedical Research Excellence (CoBRE) for research in microorganism disease research funded by the National Institute of General Medical Sciences.

“The UofL School of Dentistry is punching above its weight in securing National Institutes of Health research grants. This is an amazing achievement and a reflection of the tireless efforts of the talented research faculty,” said Dean T. Gerard Bradley, BDS, MS, DrMedDent.

Bradley says despite increased competition and tighter budgets, the school’s NIDCR research income exceeds $4 million. The ranking puts UofL’s School of Dentistry higher than a number of larger institutions such as The Ohio State University, Virginia Commonwealth University, University of Washington and State University of New York at Buffalo.

The success, he says, is a tangible outcome of a long-term strategic plan to increase the national and international stature of dental research, and basic science is integrated throughout the teaching and clinical missions of school. The research intensive Department of Oral Immunology and Infectious Disease, created by former dental dean John J. Sauk, DDS, MS, in 2015 drives extramurally-funded endeavors. 

“We have built a thematic research program that allows individual projects to be supported by several faculty with complementary expertise,” said Richard J. Lamont, PhD, chair of the Department of Oral Immunology and Infectious Diseases and Delta Dental Endowed Professor.

“Researchers are only successful when supported by the clinicians and administration,” said Donald R. Demuth, PhD, associate dean for research and a multi-funded basic and translational investigator. “It is evident that the overall culture of a school makes a significant contribution to research progress.”

Bradley says many challenges lie ahead in the harsh funding climate, but the school has positioned itself to remain competitive.

“Through the recent recruitment of two outstanding assistant professors, Huizhi Wang, PhD, and Juhi Bagaitkar, PhD, and the addition of Lisa Sandell, PhD, to the Department of Oral Immunology and Infectious Disease, we maintain optimism about future growth” he said. 

The School of Dentistry’s research advancement is consistent with increased national and international recognition, as faculty publish papers in high impact journals, serve on editorial boards and grant review panels, and receive invitations to speak at international conferences.