Atopic dermatitis (AD), a chronic inflammatory skin condition, primarily manifests through symptoms such as redness, swelling, and itchy rashes. It predominantly affects individuals genetically predisposed to the condition. The presentation of symptoms is influenced by a complex interplay among the immune system, environmental factors, and gut microbiota, with many aspects of this intricate relationship yet to be fully uncovered. Recent studies have shed light on critical elements contributing to AD severity. For instance, changes in gut microbiota composition have been linked to exacerbated disease symptoms, while environmental triggers like allergens and pollution can aggravate the condition. Genetic predispositions also play a critical role in susceptibility to AD, and emerging treatments such as dietary adjustments and faecal transplantation show promise in managing the disease.

The understanding of these interconnected factors is crucial for advancing our comprehension of AD and serves as a foundation for developing new therapeutic approaches, as discussed in a collaborative review article from the International Journal of Molecular Sciences. This research, conducted by teams from the University of São Paulo (USP) and Federal University de São Paulo (UNIFESP) in Brazil, delves into these dynamics, showcasing the global effort in tackling this complex condition.

Often referred to as atopic eczema, AD impacts approximately 7%-10% of adults and 20%-25% of children, with no clear consensus on its prevalence between genders. The frequency of AD has significantly risen in the 21st century, a trend attributed to various factors, including genetic and autoimmune influences, compromised skin barrier function, viral infections, changes in gut microbiome composition, dietary habits, and lifestyle alterations.

A notable hypothesis posits that the surge in AD cases in developing regions might stem from reduced exposure to beneficial bacteria, potentially affecting immune system maturation. In this critical process, the immune system evolves its response following initial microbial contact.

The review underscores the pivotal role of gut microbiota in recent AD research. According to Sabri Saeed Sanabani, a researcher at the Institute of Tropical Medicine (IMT-USP) and the article’s senior author, the gut microbiome is integral not only for regulating 70% of the immune system but also for maintaining the integrity of the skin barrier and gastrointestinal tract structure. It is crucial in nutrient absorption and energy balance and is directly connected to the skin through the gut axis.

Recent findings suggest that disturbances in gut microbiome composition can lead to AD pathogenesis. Research indicates an increased presence of pathogenic bacteria like Clostridium difficile, Escherichia coli, and Staphylococcus aureus, alongside a reduced abundance of beneficial bacteria such as Bifidobacteria and Bacteroides, which produce short-chain fatty acids (SCFAs). A decrease in SCFA levels is often linked with intestinal inflammation in otherwise healthy individuals.

Genetic research, particularly genome-wide association studies (GWAS), continues to identify genetic variants associated with AD susceptibility and progression. Notably, mutations in the filaggrin gene (FLG), vital for maintaining skin barrier integrity, have been identified as a significant risk factor for AD. However, it remains unclear whether alterations in the gut microbiome are genetically determined.

Although not fully understood, the role of environmental factors in AD is acknowledged in the context of how allergens, irritants, pollution, and microbial exposure can undermine skin barrier function and disrupt gut microbiome balance.

The review discusses promising therapeutic approaches targeting epigenetic changes and modulating gut microbiome diversity through dietary interventions, probiotics, prebiotics, and faecal transplants. These innovative treatments hold the potential to revolutionize the management of atopic dermatitis, offering new hope for patients and healthcare professionals alike.

As with all comprehensive reviews, the primary aim is to analyze existing scientific literature, confirm what is known, and identify gaps that require further investigation, as explained by Sanabani. This ongoing research is pivotal for paving the way towards more effective and targeted treatments for atopic dermatitis.

More information: Rodrigo Pessôa et al, The Interaction between the Host Genome, Epigenome, and the Gut–Skin Axis Microbiome in Atopic Dermatitis, International Journal of Molecular Sciences. DOI: 10.3390/ijms241814322

Journal information: International Journal of Molecular Sciences Provided by Fundação de Amparo à Pesquisa do Estado de São Paulo