Oral PHGG ameliorates atopic dermatitis-like dermatitis with concurrent modulation of colonic IgA and cecal microbiota: implications for the gut–skin axis

초록

BACKGROUND Atopic dermatitis (AD) is increasingly recognized as a systemic inflammatory disorder linked to intestinal immune and microbiome dysregulation. However, whether dietary galactomannan fibers can mitigate AD through coordinated modulation of the gut–skin axis remains unexplored. This study investigated the anti-atopic potential of orally administered partially hydrolyzed guar gum (PHGG), a low-viscosity, fermentable galactomannan enriched in low-mass oligosaccharides (mannose/galactose ratio of 1.87). RESULTS In TNF-α/IFN-γ-stimulated HaCaT keratinocytes, PHGG (100–400 μg mL−1) suppressed IL-6, IL-8, and MCP-1 secretion and down-regulated AD-relevant mediators, including TARC, MDC, RANTES, and TSLP. In TNF-α-challenged Caco-2 cells, PHGG reduced IL-8 and MCP-1 and partially restored barrier-associated transcripts (TJP1, TJP2, OCLN, CLDN1) and MUC2. In 2,4-dinitrochlorobenzene (DNCB)-induced AD BALB/c mice, oral PHGG (100–400 mg kg−1 d−1) attenuated lesion severity, epidermal hyperplasia, collagen loss, and mast cell infiltration without adverse effects on body weight or organ weights. PHGG reduced circulating immunoglobulins and inflammatory cytokines, suppressed skin type 2 helper T-cell (Th2)-associated mediators, and restored colonic immune homeostasis, as evidenced by increased immunoglobulin A (IgA) and decreased interleukin 1 beta (IL-1β) and IL-6. Cecal 16S rRNA profiling revealed that PHGG shifted dysbiotic microbial signatures toward fiber-responsive Bacteroidales lineages (e.g., Muribaculaceae, Alistipes, Rikenellaceae) and partially normalized community structure in beta-diversity analyses. CONCLUSION These findings demonstrate that oligosaccharide-enriched PHGG ameliorates AD-like inflammation through concurrent modulation of cutaneous immune responses, colonic mucosal immunity, and gut microbial community structure, supporting a gut–skin axis mechanism. Future studies quantifying microbial metabolites are warranted to establish causal mediators of gut-to-skin signaling. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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