Implication of Human Bacterial Gut Microbiota on Immune-Mediated and Autoimmune Dermatological Diseases and Their Comorbidities: A Narrative Review

Plain Language Summary The gut microbiota is defined as the collection of microbes (bacteria, fungi, archaea, and viruses) inhabiting the human gut. If healthy, it allows the maintenance of several crucial physiological functions, such as the ability to regulate the immune system. Accordingly, increasing evidence has pointed out a condition of imbalance in the gut microbial community (dysbiosis) in several autoimmune/immune mediated dermatological conditions. Specific gut dysbioses have also been reported to correlate with clinical and prognostic parameters of such diseases. In this review, the current knowledge and the possible pathogenic implications of bacterial gut microbiota composition assessed through advanced techniques in systemic lupus erythematosus, atopic dermatitis, psoriasis, and alopecia areata are discussed. Furthermore, evidence of a potential role of specific gut microbiota signatures affecting the clinical course and main associated diseases is also reviewed. In this scenario, an increased knowledge of gut microbiota composition and functions in autoimmune/immune mediated dermatological diseases might suggest additional treatments besides conventional therapies, and predict clinical evolution and comorbidities association. During the last decade, the advent of modern sequencing methods (next generation techniques, NGS) has helped describe the composition of the human gut microbiome, enabling us to understand the main characteristics of a healthy gut microbiome and, conversely, the magnitude of its disease-related changes. This new knowledge has revealed that healthy gut microbiota allow the maintenance of several crucial physiological functions, such as the ability to regulate the innate and adaptive immune systems. Increasing evidence has pointed out a condition of dysbiosis in several autoimmune/immune mediated dermatological conditions and specific gut microbial signatures have also been reported to correlate with clinical and prognostic parameters of such diseases. Based on a literature search of relevant published articles, this review debates the current knowledge and the possible pathogenic implications of bacterial gut microbiota composition assessed through NGS techniques in systemic lupus erythematosus, atopic dermatitis, psoriasis, and alopecia areata. Evidence of a potential role of specific gut microbiota signatures in modulating the clinical course of such diseases and their main comorbidities has been also reviewed.

Automated summary

The gut microbiota, composed of bacteria, fungi, archaea, and viruses, plays a crucial role in maintaining various physiological functions, including immune system regulation. Dysbiosis in the gut microbial community is commonly observed in autoimmune/immune mediated dermatological conditions, with specific microbial signatures correlating with clinical parameters. Understanding the composition and functions of gut microbiota in such diseases may lead to new treatment approaches and insights into disease progression and comorbidities.