Targeting the immune system could prevent or treat periodontal disease (PD), according to new research from the US.
The study by a team at the University of Pittsburgh, Pennsylvania—and published in Proceedings of the National Academy of Sciences—showed that delivering microparticles containing the immune-modulating compound CCL2 directly to the gums inhibited bone loss and sped up bone repair in a mouse model of PD.
“Treatment for PD has always focused on targeting bacteria, but bacteria don’t actually cause the disease,” senior author Dr Charles Sfeir said.
“Rather, they trigger PD by activating the immune system, which leads to inflammation and bone loss around teeth.
“Our study shows that it’s a two-way street: If we contain the immune system, we can shift the composition of bacteria and prevent the disease from happening or stop its progression.”
The researchers first induced PD in mice by tying a strand of silk around one of their molars. The silk quickly accumulates bacteria, inducing inflammation that starts to rapidly destroy bone around the teeth within just four days.
To see whether CCL2 could prevent PD or treat actively progressing disease, the researchers treated the animals with the microparticles at the same time as silk placement or four days afterwards. They also examined whether CCL2 would impact disease that was resolving on its own by treating mice with microparticles at the same time as they removed the silk.
In all three scenarios, the CCL2 therapy helped prevent or treat PD by reducing bone loss and improving bone repair.
This beneficial effect was driven by changes in macrophages, the white blood cells that kill microorganisms, remove dead cells and stimulate other immune cells. In PD, most macrophages are the inflammatory M1 type, but treatment with CCL2 shifted them to become the anti-inflammatory M2 type.
Injection of microparticles also altered the oral microbiome, reducing or preventing increases in the overall bacterial load and abundance of some bacteria species associated with PD.
“PD is an extremely widespread inflammatory disease that impacts many patients to varying degrees of severity,” Dr Sfeir said.
“This research is exciting because it has the potential to impact so many people.”
