Probiotics in the Treatment and Prevention of Atopic Dermatitis

The environmental factors which may influence atopic diseases also include probiotics such as lactobacilli or bifidobacteria. They are defined as specific microbial cultures which confer health benefits by prophylactic or therapeutic effects. These effects include the stabilization of the intestinal barrier, stimulation of intestinal IgA production, and modulation of specific and nonspecific immune responses to environmental factors like allergens [3–6] . In the end probiotic bacteria lead to a reduction in Th2 cytokines and increased production of IL-10 and TGFby regulatory T cells [5, 6–9] . However, there are conflicting results, as recently reported by authors from Denmark [10] . They showed that certain probiotic strains can modify antigen-presenting cells to cause reduced activity of regulatory T cells. So far the results regarding the immunomodulatory effects of probiotics appear variable, which may be due to using different probiotic strains and different methods of stimulating cytokine production. Based on these findings probiotics have been considered to improve and prevent AD. The Finnish group headed by Isolauri (1997) was the first to show significant reduction in SCORAD (Scoring Atopic Dermatitis) in the probiotic group compared to a placebo group [11] . Four years later the same study group reported a positive effect Atopic dermatitis (AD) is the most common chronic inflammatory skin disease in infancy, which has increased steadily in the industrialized countries over the last 3 decades. Clinically the disease is characterized by dry skin, intractable pruritus and current relapses or chronic course which is associated with reduced quality of life for patients and their families. The therapy is mainly symptomatic and includes moisturizing the skin and topical anti-inflammatory treatment such as corticosteroids and calcineurin inhibitors. Additionally patients have to avoid irritants and allergens. The main cause of AD is still not clearly understood. Apparently, it is the result of a complex interaction between genetic and environmental factors leading to disturbed epidermal differentiation, impaired epidermal barrier function and dysbalance of the immune system. The latter is characterized by a disruption of the Th1/Th2 cytokine balance towards an activation of Th2 cells, which is followed by induction of IgE and the activation and recruitment of eosinophils. It has been suggested that the absence of the exposure to microbes in the early childhood predisposes an infant to develop atopic diseases (hygiene hypothesis) [1] . Furthermore, patients with AD have significantly increased colonization by superantigen-secreting Staphylococcus aureus , which is associated with immunosuppressive activity of regulatory T cells [2] . Published online: September 8, 2010