Gut–Skin Axis: Current Knowledge of the Interrelationship between Microbial Dysbiosis and Skin Conditions

Abstract

The microbiome plays an important role in a wide variety of skin disorders. Not only is the skin microbiome altered, but also surprisingly many skin diseases are accompanied by an altered gut microbiome. The microbiome is a key regulator for the immune system, as it aims to maintain homeostasis by communicating with tissues and organs in a bidirectional manner. Hence, dysbiosis in the skin and/or gut microbiome is associated with an altered immune response, promoting the development of skin diseases, such as atopic dermatitis, psoriasis, acne vulgaris, dandruff, and even skin cancer. Here, we focus on the associations between the microbiome, diet, metabolites, and immune responses in skin pathologies. This review describes an exhaustive list of common skin conditions with associated dysbiosis in the skin microbiome as well as the current body of evidence on gut microbiome dysbiosis, dietary links, and their interplay with skin conditions. An enhanced understanding of the local skin and gut microbiome including the underlying mechanisms is necessary to shed light on the microbial involvement in human skin diseases and to develop new therapeutic approaches.

Microbiome Modulation as a Therapeutic Approach in Chronic Skin Diseases

“…Acne is a chronic skin disease, affecting the pilosebaceous units, with multifactorial pathogenesis including hormonal influence, the immunological state of the host, diet, deregulation of insulin-like growth factor, excessive sebum production and FoxO1 deficiency [152,153]. Considering the pathogenesis of acne, Cutibacterium acnes has been implicated as an important pathogenic factor.…”

Intestinal Inflammation Breaks Established Immune Tolerance to a Skin Commensal

“…While the three tissues affected in these studiesjoint, eye, and kidneys-are not heavily-colonized by microbes, we examined the connection between the intestinal tract and skin, which both harbor large and diverse microbial communities capable of influencing host immunity. The concept of linked gut and skin dysbiosis has been a topic of conjecture as relates to disease pathogenesis (De Pessemier et al 2021;O'Neill et al, 2016;Salem et al, 2018). However, the few studies that have tackled the mechanistic connection between immunity at these two barrier sites have focused on anaphylaxis and allergy (Leyva-Castillo et al 2019, Oyoshi et al 2011, Rigoni et al 2020.…”

Human Microbiota Network: Unveiling Potential Crosstalk between the Different Microbiota Ecosystems and Their Role in Health and Disease

“…Just as there is communication between the human cells, bacteria also communicate between the different niches where they are established [ 118 ], as well as with the human cells [ 119 , 120 ]. As expected, since its harbors the vast majority of the microorganisms, the gut microbiota is the main core of communication, and it seems plausible that the main interplay is established between gut microbiota and the others through the well-described gut-liver axis [ 121 ], gut–brain axis [ 122 ], gut–skin axis [ 123 ], and oral–gut axis [ 124 ]. On the other hand, other authors have shown crosstalk between different regions in which the gut microbiota is not involved, such as the oral–pulmonary axis [ 69 ].…”