Atopic Dermatitis Beyond the Skin Barrier: Precision Medicine Approaches to Immunological Profiling and Therapeutic Innovation.

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease characterized by substantial clinical and immunological heterogeneity. Once considered primarily a disorder of epidermal barrier dysfunction, AD is now recognized as a complex systemic inflammatory condition involving dysregulated immune responses, epithelial-derived signaling, neuroimmune interactions, and diverse molecular endotypes. Advances in molecular immunology have substantially improved understanding of the cytokine networks underlying disease pathogenesis and have accelerated the transition toward precision medicine approaches in AD. This narrative review summarizes current evidence regarding the immunopathogenesis of AD, focusing on the interplay between classical and emerging cytokine pathways, biomarker development, and recent therapeutic innovations. While interleukin (IL)-4 and IL-13 remain central drivers of type 2 inflammation and barrier impairment, additional mediators including IL-31, IL-33, IL-22, thymic stromal lymphopoietin (TSLP), and OX40/OX40L signaling, and the emerging Th9/IL-9 axis contribute to chronic inflammation, neuroimmune activation, epidermal remodeling, pruritus, and disease heterogeneity. Comparative evaluation of these pathways supports the identification of distinct immunological endotypes relevant to disease stratification and targeted therapy. The review further discusses current and emerging biomarkers associated with disease severity, therapeutic responsiveness, and inflammatory profiling, including cytokine signatures, serum biomarkers, and transcriptomic approaches. Recent advances in biologic therapies, Janus kinase (JAK) inhibitors, and novel cytokine-targeted interventions are discussed within the context of a precision medicine framework integrating immunological profiling, molecular endotyping, and mechanism-based therapeutic innovation. Continued advances in biomarker discovery, multi-omics technologies, and predictive therapeutic algorithms are expected to further refine disease stratification and support increasingly individualized management strategies for patients with AD.