Cause of Itching in Atopic Dermatitis Unveiled

Researchers have determined the cause of inflammation and itching in individuals with atopic dermatitis, the most common form of eczema. In their study, staphylococci produced biofilms that occluded sweat ducts in patients with atopic dermatitis, which in turn activated toll-like receptor 2 (TLR2) and caused inflammation and itching.

Atopic dermatitis has both genetic and environmental components.

“This work outlines what the staphylococci are doing in the disease, which makes up the ‘environmental’ hit in a double-hit disease,” explained lead researcher Herbert B. Allen, MD, Professor and Chairman, Department of Dermatology, Drexel University College of Medicine, Philadelphia, PA. “Genetics is the other hit, with the filaggrin gene representing the main genetic abnormality.”

While previous research on the cause of inflammation and pruritus in patients with atopic dermatitis has mostly centered on the inflammation that is already present in the disease, “We were concerned with what happens before the ‘itch that rashes’ that occurs in atopic dermatitis,” noted Allen.

Researchers examined skin swabs from 40 individuals with atopic dermatitis. The swabs were taken from both lesional and nonlesional skin. These samples were compared with control samples.

All of the skin samples from patients with atopic dermatitis contained multidrug-resistant staphylococci and biofilm. In addition, TLR2, a protein that plays an important role in the innate immune system, was activated in the area immediately proximal to the blocked sweat ducts in those with atopic dermatitis who had lesions.

According to Allen, some unexpected results of the study include the findings that all of the species of staphylococci were multidrug resistant and were capable of making biofilms, that amyloid made up the infrastructure of biofilms, and that treating the stratum corneum with appropriate skin care helped treat the disease and prevent it from returning, among others.

“Even though bacteria and their biofilms are present, ordinary treatments with topical corticoids are successful in at least 95% of patients if good skin care is practiced—less soap, less hot water, less bathing, less scrubbing along with more moisturizing,” he pointed out.

“Skin careshould assume its important place in the treatment of this disease,” Allen noted when asked how he hopes the study findings may eventually affect the care of individuals with atopic dermatitis.

In terms of future research, Allen told Consultant360 that he is currently examining diseases that have eczema as part of their presentation and those that have not previously been considered eczema but have occluded sweat ducts with staphylococcal biofilms and activation of TLR2 on their pathology.

This study was published in JAMA Dermatology.

-Meredith Edwards White

Reference:

Allen HB, Vaze ND, Choi C, et al. The presence and impact of biofilm-producing staphylococci in atopic dermatitis. JAMA Dermatol. 2014 Jan 22. doi: 10.1001/jamadermatol.2013.8627. [Epub ahead of print]