Vincent Richards, PhD, MSc, an assistant professor of biological sciences at Clemson University, has received a $1.85 million grant from the National Institute of Dental and Craniofacial Research (NIDCR) to study the association between tooth decay and HIV infection in a population of children from Nigeria.
The study comes after preliminary results indicated a higher incidence of dental caries in HIV-positive children whose immune systems are compromised by the virus. Partnered with the finding that HIV infection alters the distribution of microbes in the gut microbiome, Richards’ study intends to characterize the oral microbes that might contribute to tooth decay.
“The plaque that accumulates on the surface of your teeth is a very complicated microbial community,” said Richards. “In some of my previous papers, we looked at teeth in progressive stages of caries, from a completely healthy tooth to a full blown, big cavity. What we saw was that the species changed and that you do indeed have some bacteria that are associated with health and some with disease.”
For example, Streptococcus mutans feeds on sugar and releases acids in response, dissolving enamel and initiating cavities. But Streptococcus sanguinis counteracts the effects of S mutans by raising pH levels at the tooth surface. Studies suggest this propensity for tooth decay is only heightened in HIV-infected individuals, promoting Richards to collaborate with researchers from Nigeria, site of the world’s second largest HIV epidemic.
Modupe Coker, PhD, MPH, BDS, an adjunct assistant professor of epidemiology at the Dartmouth School of Medicine, will collect plaque samples and cheek swabs and also gather information on diet and white blood cell counts from children enrolled in the study at a teaching hospital in Nigeria. The samples then will be sent back to Richards for analysis.
Richards and his colleagues will use the fast and inexpensive methods of high-throughput genetic sequencing to detail which microbial species are prevalent in the plaque samples. These analyses also will measure gene expression of the microbes to determine how HIV infection influences what proteins are being synthesized and how those proteins are affecting the metabolic pathways involved in tooth decay.
The end product, Richards said, will be a personalized approach to oral health that could mitigate the risk of tooth decay, not just for HIV-infected children, but for everyone.
“One of the future directions of this study is that we will be able to overlay the child’s genetic makeup, the microbiome data we’ve got and other info on diet and white blood cell counts so that when you go to the doctor, they can say, ‘You’re this genotype and you’ve got this microbiome and you’re also HIV infected, which means you’re highly predisposed to caries, so you better go for your dental checkup. You really can’t let it go,” Richards said.
Richards believes the results could improve prevention and intervention strategies by creating oral therapies that disrupt bacteria’s ability to form plaque. Information from the study will also help researchers understand the interplay between adaptive immunity—the strategic immune response that prompts the immune system to build resistance against specific pathogens—and the development of caries.
Personalized medicine, Richards said, will be an integral component of these strategies that he hopes will translate into an improved quality of life for children suffering with HIV infections.
The study, “Oral Microbiomes and dental Caries in a Human Immunodeficiency Virus Infected Population,” is supported by a five-year, R-01 grant from NIDCR.