Probiotics Function in Preventing Atopic Dermatitis in Children

Abstract

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by relapsing eczematous injuries and severe pruritus. In the last few years, the AD prevalence has been increasing, reaching 20% in children and 10% in adults in high-income countries. Recently, the potential role of probiotics in AD prevention has generated considerable interest. As many clinical studies show, the gut microbiota is able to modulate systemic inflammatory and immune responses influencing the development of sensitization and allergy. Probiotics are used increasingly against AD. However, the molecular mechanisms underlying the probiotics mediated anti-allergic effect remain unclear and there is controversy about their efficacy. In this narrative review, we examine the actual evidence on the effect of probiotic supplementation for AD prevention in the pediatric population, discussing also the potential biological mechanisms of action in this regard.

Keywords: atopic dermatitis; children; prevention; probiotics.

Figure 1

Pathophysiology of Atopic Dermatitis.

Figure 2

Gut dysbiosis in atopic dermatitis. The image shows gut microbial alteration in patients with AD. It seems that they have reduction of the beneficial microbes such as Lactobacillus, Bifidobacaterium (A) and an increase of the proportions of E. coli, C. difficile and S. aureus (B). Metabolites of Bifidobacterium, Lactobacillus, etc. are able to suppress the expression of Th2 associated cytokines. The reduction of bacteria producing SCFAs leads to an inadequate production of Treg cells. E. coli can promote an intestinal inflammatory response thanks to LPS. C. difficile, S. aureus could be associated with increase of intestinal permeability and eosinophilic inflammation. AD: atopic dermatitis; SCFAs: short chain fatty acids; Treg: regulatory T; TLR4: tool like receptor 4; LPS: lipopolysaccharide.

Figure 3

Immunomodulatory effects of probiotics. Probiotics regulate the differentiation of immature DCs into mature or tolerogenic DCs in the presence of pro-inflammatory stimuli (TNF-α, IL-1, IL-6, LPS) or anti-inflammatory stimuli (TGF-β, IL 10) respectively. Inflammatory Th1 cells are produced in presence of Il-1, IL-6, IL-12, IFN-γ, TNF-α, instead anti-inflammatory Th2 cells in presence of IL-4, IL-5, IL-9, IL-10, IL-13, IL-33. Probiotics exert their immunomodulatory effects on allergic diseases balancing Th1/Th2 immune response stimulating Th1 and decreasing Th2 response through different cytokines’ secretion and inducing beneficial Treg cells to promote immune tolerance.