The Therapeutic Potential of Polyphenols in Modulating Barrier Lipids, Microbiome Interactions, and Inflammatory...

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a complex pathogenesis involving epidermal barrier dysfunction, microbiome dysbiosis, and immune dysregulation. Despite significant advances in therapy, including biologics and targeted treatments, their use may be limited by adverse effects, highlighting the need for safe adjunctive strategies. Polyphenols are naturally occurring bioactive compounds that are abundant in plant-based foods and are known for their anti-inflammatory, antioxidant, and immunomodulatory properties, making them promising candidates for supportive AD management. This review integrates current evidence on the effects of polyphenols on epidermal barrier lipids, microbiome interactions, and key inflammatory pathways, including NF-κB and JAK/STAT signaling. Additionally, the role of polyphenols in modulating dendritic cell and neutrophil activity, and reducing reactive oxygen species (ROS) production and neutrophil extracellular trap (NET) formation, as well as their potential involvement in mitophagy regulation, is discussed. Polyphenols support epidermal barrier integrity by modulating the expression of key structural proteins, including filaggrin, involucrin, and loricrin, leading to a reduction in transepidermal water loss (TEWL). Furthermore, they interact bidirectionally with the gut microbiome, acting as metabolic substrates for beneficial bacteria and promoting the growth of short-chain fatty acid (SCFA)-producing species such as Lactobacillus, Bifidobacterium, and Akkermansia, while simultaneously inhibiting pathogenic strains. These findings highlight the role of polyphenols in maintaining microbiome homeostasis and supporting epidermal barrier integrity. The review encompasses findings from clinical studies, animal models, and mechanistic investigations, while also addressing limitations related to polyphenol bioavailability. Overall, polyphenols may represent a valuable adjunctive approach in AD management; however, further well-designed clinical and mechanistic studies are required to confirm their therapeutic potential.