Scientists are still unraveling the mystery of why skin conditions like eczema cause people to itch.
One known cause is inflammation, which gets worse as people scratch and their skin becomes damaged. But there may be another trigger for itchiness, according to a study published Wednesday in the journal Cell: a bacterium called Staphylococcus aureus.
Researchers from Harvard Medical School found that the bacterium can directly activate nerve cells in mice.
“What was surprising is that in some situations where there was very little inflammation, we could still see the mice scratching. It turns out, the reason is that the bacteria was directly acting on nerve fibers that produce itch,” said a co-author of the study, Isaac Chiu, an associate professor of immunology at Harvard Medical School.
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Before the study, scientists were aware that S. aureus was associated with eczema, but the exact link was unclear. The new research found that once S. aureus invades a mouse's skin, it releases an enzyme called V8. That, in turn, activates a protein called PAR1, which is located on nerve cells in the skin. The activated protein sends a signal to the brain that makes the mouse itchy — and prompts it to start scratching.
Lab experiments involving human nerve cells showed the same mechanism is possible in people, but the researchers aren’t sure yet whether the findings directly translate.
Read the full story on NBCNews.com here.
