Disease Proof

Salomon Amar at Boston University Medical Center in Massachusetts and his colleagues infected both lean and obese mice with Porphyromonas gingivalis, a bacterium that causes gum disease, and then studied how their bodies coped. Some of the mice were infected directly in the gum area; others had the bacterium injected into their bloodstream. In both cases, fat mice were slower to kill the bacterium because their immune response was blunted: immune cells called macrophages produced fewer cytokines - chemicals that would usually draw in other immune cells to fight off infection. Within 10 days of infection, obese mice infected at the gum also showed 40 per cent more bone loss in their tooth sockets.