Penn Dental Study Shows Early Challenges to Immune System Disrupt Oral Health

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Jul 31, 2025, 09:41 ET

PHILADELPHIA, July 31, 2025 /PRNewswire/ -- Once viewed only as infectious invaders, bacteria are now understood to play an important role in overall health. After the gut, the mouth is the second most diverse human microbial system. However, it has been vastly overshadowed by the focus on the microbiome of the gut.

Now, a collaborative team including Modupe O. Coker of Penn Dental Medicine has investigated the stability of the oral microbiome in children living with HIV and those exposed to the virus but uninfected by it. Their findings, published in Microbiome, challenge the conventional belief that a stable microbiome is important for overall health and offer insights into how early immune challenges shape not only oral health but also systemic health.

In their study, above-the-gum-line plaque samples were collected across three time points from children in Nigeria. This included children living with HIV, children perinatally exposed to HIV but uninfected by the virus, and children not exposed to the virus. All children living with HIV were receiving highly active antiretroviral treatment.

The research team mapped the front-to-back distribution of the microbial communities in the mouth and determined the association of HIV status and cavity-related bacterial species and intraspecies variants. They also calculated the degree of microbial turnover across the three time points to determine microbial stability or volatility.

In the gut, microbial stability over time is good. But, this study showed the opposite was true in the mouth—children unexposed to HIV exhibited higher turnover over time than those who had been exposed to HIV, suggesting that the oral microbiomes of children exposed to HIV might be less able to adapt to changes in environmental conditions.

Additionally, Coker adds, lower turnover was associated with higher frequencies of bacteria that cause cavities, increasing the risk in this population.

The study also showed that the microbial communities in children exposed to and infected by HIV were more homogeneous. While in normal circumstances, there are distinct differences between the bacteria is the front and back of the mouth.

As Coker explains, these results give a clue into the broader question of how an early-life disruption to systemic health—such as prenatal exposure to HIV—can impact the oral microbiome.

"As a translational scientist, I hope we can keep looking at novel ways to use this information to understand disease and to prevent or treat it."