Atopic dermatitis, also known as eczema, affects as many as 10% of Americans, as well as 10% of their dogs. Now a new study from doctors and veterinarians at the University of Pennsylvania has uncovered a common characteristic of the human and canine forms of the disease–and it resides in the skin’s population of bacteria known as the “microbiome.”
In a study of 32 patients at Penn’s veterinary school, researchers found that dogs with atopic dermatitis had 10 times as much Staphylococcus bacteria on their skin as healthy dogs did. Levels of another bacterial species, Corynebacterium, also rose, according to a press release from Penn’s Perelman School of Medicine. At the same time, the quality of the skin’s protective barrier deteriorated.
The researchers discovered that in the dogs, the proliferation of the abnormal bacteria crowded out more harmless or even beneficial bacteria. But after a month or so of treatment with antibiotics, the diversity of the skin microbiome in the dogs returned to healthy levels, as did the skin’s protective barrier. Their research was published in the Journal of Investigative Dermatology.
The correlation between the bacterial overgrowth and the condition of the skin’s protective barrier was a new finding, according to the press release. But more research will be needed to determine whether the growth of the bacteria causes the deterioration or vice versa. The team is now initiating research to determine how antibiotic treatment causes bacteria to become resistant to the drugs.
Ideally, the scientists say, their research will provide key insights that will lead to the development of antibiotic-free treatments. “In both canine and human atopic dermatitis we hypothesize there is a similar relationship among skin barrier function, the immune system, and microbes,” said senior author Dr. Elizabeth A. Grice, an assistant professor of dermatology and microbiology at the Perelman School in the release. “The hope is that insights gained from this study and others like it will enable us one day to treat this condition by altering the skin’s microbiome without antibiotics.”
The knowledge that the disease process in atopic dermatitis is similar in dogs and people is an example of the promise of One Health, a movement that promotes research collaborations between veterinarians and scientists who study human health, says Charles Bradley, a lecturer and dermatopathologist at Penn’s vet school. “The findings highlight the importance of dogs as a model for human dermatitis and help lay the groundwork for new therapeutic strategies,” he said in the release. One potential strategy may be to transplant healthy microbiomes into patients with atopic dermatitis, he added.