Gut–Brain–Skin Axis: From Mechanistic Insights to Translational Applications in Neurocosmetics

The gut–brain–skin axis is a proposed integrative framework describing interactions among the gastrointestinal tract, skin, and nervous system through neural, endocrine, immune, and microbial processes. Accumulating evidence has redefined the skin as a sophisticated neuro-immune-endocrine organ rather than a passive barrier, providing the fundamental mechanistic basis for the burgeoning interdisciplinary field of neurocosmetics. However, most existing reviews have focused on the unidirectional regulation from gut to skin and from brain to skin, lacking systematic analysis of the reverse signaling from skin to nervous system and its potential for cosmetic transformation. This article addresses this gap by providing a comprehensive, mechanism-oriented integrative discussion of the gut–brain–skin axis, with a focus on the ascending skin-to-central signal pathways and their significance for neurocosmetics. This review first establishes the gut–brain axis as the core framework for barrier organ-central nervous system crosstalk, then systematically delineates the key molecular and cellular mechanisms underlying the skin-brain axis—the central pillar of neurocosmetics. This article further identifies conserved regulatory hubs and shared pathological mechanisms that underlie the comorbidity of atopic dermatitis, depression, and irritable bowel syndrome. Building on this integrated framework, this review evaluates several mechanistically grounded neurocosmetic development strategies, identifies pressing translational challenges, and proposes priority directions for future research. In summary, this article provides an evidence-based framework for understanding how the gut–brain–skin axis underpins the scientific basis of neurocosmetics and proposes a translational skincare framework that integrates overall homeostasis, stress protection, and emotional health.