Staph Infections & Eczema: What's the Connection?

Newswise ANN ARBOR, Mich. For the millions of people suffering from the intensely red, horribly itchy skin condition known as eczema, the only thing more maddening than their disease is the lack of understanding of what causes it, or makes it flare up from time to time.

Now, a new finding made by University of Michigan Medical School researchers and their colleagues may bring that understanding closer and could help lead to better treatments.

In a paper in Nature, the team reports that a toxin produced by the common bacteria Staphylococcus aureus popularly known as staph causes immune-system cells in the skin to react in a way that produces eczema-like rashes.

The release of the molecule, called delta toxin, by staph bacteria caused immune-related mast cells in the skin to release tiny granules that cause inflammation. But this didnt occur when skin was exposed to staph strains that lacked the gene for delta toxin.

This link between a specific S. aureus toxin and mast cell degranulation suggests a very specific mechanism, though its not enough to suggest delta toxin from staph bacteria by itself causes eczema, says senior author and U-M professor Gabriel Nunez, M.D. Genetic vulnerability likely also plays a role, he says.

The finding was made in mice, so its too soon to say that the same effect occurs in humans who suffer from eczema, also called atopic dermatitis. But the researchers did find significant levels of staph delta toxin in skin samples taken from patients with eczema.

Nunez, lead author Yuumi Nakamura, M.D., Ph.D., co-author Naohiro Inohara, Ph.D., and their colleagues hope their finding provides a new avenue for developing treatments to help the 15 to 30 percent of children, and 5 percent of adults who have eczema.

Some including patients have previously noted that eczema patients who take antibiotics for other conditions experience a lessening of eczema symptoms. But antibiotics have many drawbacks as long-term therapies for a chronic condition such as eczema most of all, the threat of contributing to the already serious issue of multi-drug resistant Staphylococcus aureus, or MRSA.

The research was funded by the National Institutes of Health, and involved NIH researchers who study S. aureus. Nunez notes that the initial hint of a link came totally by chance, as an incidental finding in an unrelated mast cell study they were conducting. They zeroed in on the little-understood delta toxin and began exploring its power to provoke mast cells to cause inflammation.

We know that 90 percent of patients with atopic dermatitis, also called eczema, have staph bacteria detectable on their skin, says Nunez, who is the Paul de Kruif Professor of Academic Pathology. But until now, it has not been suspected that the contribution was primary, because there was not a clear mechanistic link. Now we have evidence that there may indeed be a direct link.

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Staph Infections & Eczema: What's the Connection?