Comparative Analysis of the Microbiome across the Gut-Skin Axis in Atopic Dermatitis

Abstract

Atopic dermatitis (AD) is a refractory and relapsing skin disease with a complex and multifactorial etiology. Various congenital malformations and environmental factors are thought to be involved in the onset of the disease. The etiology of the disease has been investigated, with respect to clinical skin symptoms and systemic immune response factors. A gut microbiome-mediated connection between emotional disorders such as depression and anxiety, and dermatologic conditions such as acne, based on the comorbidities of these two seemingly unrelated disorders, has long been hypothesized. Many aspects of this gut-brain-skin integration theory have recently been revalidated to identify treatment options for AD with the recent advances in metagenomic analysis involving powerful sequencing techniques and bioinformatics that overcome the need for isolation and cultivation of individual microbial strains from the skin or gut. Comparative analysis of microbial clusters across the gut-skin axis can provide new information regarding AD research. Herein, we provide a historical perspective on the modern investigation and clinical implications of gut-skin connections in AD in terms of the integration between the two microbial clusters.

Keywords: atopic dermatitis; gut microbiome; gut–skin axis; skin microbiome.

Figure 1

Several potential pathways of the gut–skin axis in atopic dermatitis (AD). In particular, numerous studies have shown that toxins in the gut microbiome are a potential problem for AD patients. Intestinal microbes are known to influence the skin through immunological, metabolic, and neuroendocrine pathways. The effect of the skin microbiome on the intestinal immune system has been mainly investigated in the field of food allergies, which shows how skin microorganisms affect the gut of AD patients. Recently, skin exposure to ultraviolet B (UVB) was shown to change the gut microbiome.

Figure 2

Comparisons between traditional (conventional) and future therapeutic methods for AD. Previous studies mainly focused on AD pathogenesis related to three factors: genetic, immunological, and environmental. Recently, a new treatment of AD targeting the microbiome has been proposed based on the gut–skin axis as the microbiome factor of the skin and gut. The gut microbiome-based treatments include oral administration of probiotics, prebiotics and postbiotics, and the possibility of using phage therapy. The skin microbiome-based treatments include direct application of probiotics to the skin and immunotherapy. Further studies are required to apply these microbiome-based methods as future treatments, instead of the existing treatments. FMT, fecal microbiota transplantation.