The immune system protects the body by responding to invading organisms. But how is an attack on useful resident microbes prevented? A pathway has now been identified that allows immune cells to sense and respond to beneficial bacteria.
The immune system performs a difficult balancing act. It must respond rapidly to dangerous microorganisms that threaten the host, yet also coexist peacefully with the large array of microorganisms that colonize barrier surfaces such as those of the skin and gut. Writing in
Cell, Linehan
et al.
1 examine the interactions between immune cells and a bacterium that normally resides on the skin, and identify a signalling pathway that governs the immune response to such microbes.
Most immunological research has focused on how immune cells recognize and eliminate viral and bacterial pathogens, and the insights obtained have led to the development of many immune-based therapies. However, attention has also turned to microbial communities at barrier surfaces and the long-term influence they exert on host immune responses. Accordingly, Linehan and colleagues studied the skin-dwelling bacterium
Staphylococcus epidermidis in mice and rhesus monkeys, as well as analysing human-tissue samples from the clinic.
