The body’s defence army can amplify the danger signals when it senses DNA from bacteria as an intruder

Our bodies have an arsenal of weapons that attack and kill bacteria to stop them going on to cause infections. One of the weapons involved in this include a family of small molecules called defensins. Defensins are known to be able to create holes in bacterial cell walls resulting in their contents (including their DNA) spill out. Human β-defensin 3 (also called hBD3) is the best bacterial-killing defensin that has been discovered.

In a study using mouse and human cells, researchers at the University of Edinburgh’s MRC Centre for Inflammation Research and MRC IGMM HGU, led by Professor Julia Dorin have found that not only does β-defensin 3 kill bacteria effectively, but in the lab it also amplifies the response of specialised immune cells to the bacterial DNA. These immune cells recognise bacterial DNA as being different from their own DNA and produce a danger signal. As well as killing the bacteria, hBD3 can increase the danger signal, to allow stronger activation of the body’s alarm signals and other immune cells that are essential in the effective protection against infections (T and B cells).  This work is hoped to open new approaches to improve vaccination protocols (particularly those that use DNA-based vaccines) for protection against bacterial infections, even those that are antibiotic resistant.

This work was funded by Medical Research Council UK

Digital Object Identifier (DOI): 10.1002/eji.201646799

Paper published in the European Journal of Immunology (Wiley online library website)