A new randomized clinical trial published in JAMA Dermatology explores the effectiveness of oral probiotics in treating atopic dermatitis.
Atopic dermatitis is a chronic inflammatory skin disease estimated to occur in up to 20% of children around the world. In addition to recurrent bouts of intense inflammation and itching, children with atopic dermatitis are more likely to develop other disorders such as asthma and chronic sinusitis.
The intense inflammation of atopic dermatitis is associated with an imbalanced immune response caused by a higher ratio of T helper 2 cells compared to T helper 1 cells. T helper cells play an important role in the immune system. The imbalance of T helper cells increases the activity of Immunoglobulin E (IgE), an antibody that plays a key role in allergic reactions.
Past studies have suggested a link between the disruption of intestinal barriers and the inflammation characteristic of atopic dermatitis that is T helper 2 dominant. Patients with atopic dermatitis have shown reduced numbers of certain types of gut bacteria that release high amounts of butyrate and propionate. These two compounds have anti-inflammatory properties and help maintain intestinal barrier integrity.
Link Between Gut Bacteria and Imbalanced Immune Response
Due to the connection between gut bacteria composition and imbalanced immune responses, a team of Spanish researchers set out to determine whether oral probiotics can be effective in treating atopic dermatitis. Their work was recently published in JAMA Dermatology.
A randomized double-blind placebo-controlled intervention trial was carried out over a period of 12 weeks at a dermatology centre in Spain. A total of 50 children from 4 to 17 years old with moderate AD took part in the study. In order to reduce the number of confounding factors, any patients that had used immunosuppressive drugs or antibiotics shortly before the trial, or had diagnoses of intestinal bowel disease or bacterial infection, were excluded.
The main outcome measured was the Scoring Atopic Dermatitis (SCORAD) index, which records the intensity and extent of atopic dermatitis symptoms. Researchers also recorded the number of days of topical steroid use needed during flare-ups. Children in the treatment group received a daily maltodextrin capsule containing probiotic strains of Bifidobacterium lactis, B. longum and Lactobacillus casei for the 12 week treatment period, while those in the placebo group took a pill containing only maltodextrin.
Improvements After Taking Probiotics
After follow up, children in the treatment group showed a greater reduction in SCORAD index scores. A total of 96% of patients who took the probiotic capsule showed improvements in the SCORAD index compared to only 46% of patients on placebo. Children in the treatment group also required a significantly lower number of days of topical steroids to treat flare-ups of atopic dermatitis.
The study is limited by its relatively short follow-up period and its single-centre design. Additionally, although the duration of corticosteroid use was recorded during flare-ups, the dosage was not. The researchers note that these results are of limited applicability to groups other than those studied, and how this may affect patients of different age groups or with different geographic diets is yet to be determined. Future trials will be necessary to explore these limitations. Nevertheless, this important trial demonstrates that probiotics may be an effective and safe additional treatment to reduce the SCORAD index and topical steroid use in children with atopic dermatitis.
Written by Agustin Dominguez Iino, BSc
Reference: Navarro-López V et al. Effect of Oral Administration of a Mixture of Probiotic Strains on SCORAD Index and Use of Topical Steroids in Young Patients With Moderate Atopic Dermatitis: A Randomized Clinical Trial. JAMA Dermatology. 2017 Nov 8. doi: 10.1001/jamadermatol.2017.3647.