Novel Method Uses Sebum to Diagnose Infant Atopic Dermatitis

Eczema is an inflammatory skin condition that often affects infants as young as one to two months. Among the various types of eczema seen in infants, early-onset atopic dermatitis (AD), characterized by psychological stress and sleep disorders, is particularly concerning. 

Studies have identified that if left untreated, AD can increase the risk of allergic diseases such as food allergies and asthma—a progression also known as the “atopic march”. Early diagnosis and intervention of early-onset AD are needed to ensure the infant’s psychological and physical health.

However, it can be difficult to diagnose AD in infants as young as one or two months. Besides parents’ reluctance to seek medical advice and the infant’s inability to express their symptoms, the diagnosis may be influenced by the doctor’s subjectivity and experience. Moreover, the use of accurate yet invasive diagnostic procedures for AD, such as skin biopsies, is difficult in infants. There is, thus, a need for new methods of diagnosing AD that are objective and noninvasive.

Using sebum to study AD pathogenesis

In an earlier study led by project leader Takayoshi Inoue, PhD, from the Biological Science Research division at Kao Corporation, researchers had identified that sebum contains measurable levels of human mRNA molecules. They hypothesized that analyzing the genetic expression of such RNA-containing sebum samples could reveal the molecular features of AD and its underlying pathogenesis.

Based on this discovery, the researchers developed a novel analytical method—called RNA monitoring—that enables human skin transcriptome analysis of the mRNA in sebum collected from the skin using a simple oil-blotting film.

Efficacy of sebum biomarkers

In this study, published recently in the Journal of the European Academy of Dermatology and Venereology, the researchers verified the usefulness of this novel RNA-monitoring method. This study was conducted in collaboration with Kiwako Yamamoto-Hanada, MD, PhD, and Yukihiro Ohya, MD, PhD, of the National Center for Allergy Research at the National Center for Child Health and Development, Japan. The main objective of this study was to determine if sebum-RNA could provide reliable biomarkers for the detection of early-onset AD in infants.

The study population comprised a prospective cohort of 98 one- and two-month-old infants. In some of these infants, AD was diagnosed according to the United Kingdom Working Party’s criteria. The researchers first collected sebum from the facial skin of all participating infants using a single oil-blotting film, in a noninvasive and easy procedure. Next, mRNA in skin surface lipids (SSLs) were extracted for performing transcriptome analysis, and lastly, subjected to data analysis for identifying the underlying molecular features of early-onset AD in infants.

The analysis revealed several genes showing varying expression in infants with and without AD. Specifically, the researchers observed that one-month-old infants with AD had lower expression of genes related to lipid metabolism and synthesis, tight junctions, antimicrobial peptides, and keratinization, and higher expression of genes related to T helper (Th2-, Th17-, and Th22)-type immune responses.

Significance of study findings

These molecular changes in barrier function and inflammatory markers characterizing AD were not reported in earlier literature, especially in one-month-old infants, mainly owing to the invasiveness of common diagnostic procedures.

Most importantly, the team observed that sebum-RNA could be used to detect the onset of AD well in advance, via changes in the levels of these markers. Explains Yamamoto-Hanada, “Our results confirm that the RNA-monitoring method is useful for the early detection of AD in infants and may also be used for their treatment monitoring in the future.”

Hopefully, the availability of this simple, objective, and noninvasive diagnostic option for AD will encourage parents of infants with AD to opt for early consultation and therapeutic intervention of the condition. “Infants often have multiple eczemas and experience repeated exacerbations and remissions. With our method, the timely treatment of early-onset AD can be realized, enabling an improvement in the quality of life for infants with AD and their families,” says Yamamoto-Hanada.

- This press release was originally published on the Kao Corporation website