Age of atopic dermatitis onset defines endotype of disease

MILAN — Adult-onset dermatitis has distinct TH1 activation compared with adults who have childhood-onset atopic dermatitis, showing two separate endotypes defined by age of onset.

“Classically, atopic dermatitis is considered a childhood disease; however, in the last 20 years, we realized there is another form of atopic dermatitis that affects the adult in which the first symptoms appear after 20 years of age,” Paola Facheris, PhD, a post-doctoral fellow in the laboratory of inflammatory skin diseases at the Icahn School of Medicine at Mount Sinai, told Healio.

At the European Academy of Dermatology and Venereology Congress, Facheris presented results of a study that analyzed lesional and non-lesional skin biopsies and blood samples from 15 adults with pediatric-onset AD, 15 adults with adult-onset AD and 15 age-matched healthy controls.

Paola Facheris

Using RNA sequencing, quantitative real-time PCR and immunohistochemistry, researchers looked at the pathways affected in each population.

Dysregulation and TH2/TH22 hyperactivation and barrier alterations were found in both atopic dermatitis populations, as compared with the healthy controls; however, those with adult-onset disease showed greater TH1 upregulation compared with those with disease that began in childhood.

Additionally, those with pediatric-onset AD had greater skin barrier impairment, a higher number of infiltrating T cells and dendritic cells and more inflammation.

“These two phenotypes of atopic dermatitis are different,” Facheris said. “Atopic dermatitis with adult-onset is a subtype of atopic dermatitis that is different from pediatric-onset atopic dermatitis, not only the clinical presentation in the risk factors, but also new modulations. This will allow the dermatologists to know more about the pathophysiology of this kind of atopic dermatitis and be able to choose the appropriate treatment for them.”