UVB Treatment Increased Bacterial Diversity in Atopic Dermatitis Patients

Astrid Haaskjold Lossius, MD, PhD

A recent investigation into the treatment of atopic dermatitis with narrow-band ultraviolet B (nb-UVB) light found that the treatment resulted in changes in the skin microbiota towards higher diversity in affected patients.

However, the microbiota of the nose and throat were not altered.

Investigators led by Astrid Haaskjold Lossius, MD, PhD, Institute of Clinical Medicine, University of Oslo, noted that the notion of atopic dermatitis being driven by microbial abnormalities had never been fully elucidated in previous studies.

However, previous data showed that colonization of the skin with Staphylococcus aureus in patients with atopic dermatitis is frequent, with studies showing that UVB treatment decreases the relative abundance of the bacteria in children and adults with the disease.

As such, Lossius and colleagues investigated the changes in the skin, nose, and throat microbiota with 16S rRNA gene sequencing before and after 6 to 8 weeks of full-body nb-UVB treatment in adult patients with atopic dermatitis.

The Methods

Investigators recruited 16 patients with atopic dermatitis to evaluate the efficacy of UVB treatment. Prior to inclusion, patients avoided systemic antibiotics and immunosuppressive therapy for 4 weeks.

Patients were also asked to avoid using topical immunosuppressive therapy and topical anti-bacterial therapy for 2 weeks.

Investigators assessed disease severity and morbidity with scoring tools that included the Eczema Area and Severity Index (EASI), the SCORing Atopic Dermatitis (SCORAD) index, the Patient-Oriented Eczema Measure (POEM), and the Dermatology Life Quality Index (DLQI).

Patients participated in structured interviews, and saliva was collected in OrageneTM DNA saliva sampling kits and tested for 3 of the most common mutations in the genes encoding filaggrin (FLG), including R501X, R2447X, and 2282del4.

Investigators utilized the Dermalight® 80 MED-tester to administer the nb-UVB minimal erythema dose (MED), with 1 lesion with active atopic dermatitis having been chosen for each patient.

The lesions were irradiated with 1 MED on days 0, 2, and 4 with the small, hand-held nb-UVB device, Dermalight® 80, and patients underwent full-body nb-UVB 3 times a week for 6–8 weeks, with incremental dosages, with a total of 12–25 treatments.

Non-lesioned skin samples from the nose and throat of each patient were also obtained.

The Findings

Lossius and investigators observed several shifts towards higher diversity in the microbiota of lesioned skin in patients after 6-8 weeks of treatment.

The team also reported a trend of lower alpha diversity on lesioned skin as opposed to non-lesioned skin before UVB treatment, though they deemed this not significant.

The microbiota of non-lesioned skin and of the nose and throat remained unchanged. After only 3 treatments with nb-UVB, no significant changes in the microbiota were observed.

Lossius and colleagues noted small sample size of their study, considering it the main limitation. They added that increased study on the “complex interplay” between the skin microbiota and the immune system in patients with atopic dermatitis could result in improvements to individualized treatment.

“The changes in lesioned skin appeared after clinical remission was evident, suggesting that the microbial changes are secondary, rather than primary, in the pathogenesis of AD,” the team wrote.

The study, "Shifts in the Skin Microbiota after UVB Treatment in Adult Atopic Dermatitis," was published online in Karger Publishers.