Immunology: Injury prone

In Notable Advances 2010, on Nature Medicine:

For years, doctors have puzzled over the molecular similarities between how the body's immune system reacts to both internal tissue trauma and external microbial infections. Now, scientists have chalked up the common inflammatory response to the shared evolutionary origin of mitochondria and bacteria.

Researchers from the Beth Israel Deaconess Medical Center in Boston tested the blood plasma of 15 trauma patients and found circulating components of mitochondrial DNA and proteins known as formyl peptides. Further dissecting the immune response, the researchers showed these components bind to formyl peptide receptor-1 and Toll-like receptor 9 on the surface of immune cells known as neutrophils, promoting their activation and attracting them to the site of injury (Nature 464, 104–108, 2010).

Notably, these same receptors and signaling pathways are also triggered by invading bacteria, leading to a robust inflammatory response resembling sepsis.