Ursodeoxycholic acid alleviates atopic dermatitis-associated inflammatory responses in HaCaT and RBL-2H3 cells and DNCB/DFE-treated mice

Aims: Ursodeoxycholic acid (UDCA) is a hydrophilic dihydroxy bile acid used for cholestatic liver disease and exhibits antioxidant, antitumor, and anti-inflammatory effects. However, its potential effects on atopic dermatitis (AD) have not been elucidated. This study aimed to evaluate the efficacy of UDCA in inhibiting the inflammatory response and alleviating lesions in AD -like mice. Main methods: To investigate the efficacy of UDCA in AD -like inflammatory responses, tumor necrosis factoralpha (TNF- alpha)- and interferon -gamma (IFN- gamma)-stimulated HaCaT cells and anti-dinitrophenyl immunoglobulin E (DNP-IgE)- and human serum albumin (HSA)-stimulated RBL-2H3 cells were used to investigate the levels of inflammatory factors and their mechanisms. AD -like lesions were induced by applying DNCB/DFE to mice. The effect of UDCA administration in AD -like mice was analyzed by assessing organ weight, serum IgE and inflammatory cytokine levels, and histopathological changes using immunohistochemical and immunofluorescent staining. Key findings: In HaCaT cells, UDCA significantly diminished TARC, MDC, MCP -1, and IL -6 expression by inhibiting the phosphorylation of nuclear NF- kappa B and cytoplasmic I kappa B, and also increased the levels of skin barrier protein. In RBL-2H3 cells, UDCA reduced beta-hexosaminidase and IL -4 levels. In AD -like mice, UDCA suppressed organ hypertrophy, ear edema, SCORAD index, DFE-specific IgE levels, inflammatory cytokine levels, skin hypertrophy, mast cell invasion, skin barrier loss, and thymic stromal lymphopoietin-positive areas. Significance: UDCA suppressed the expression of pro -inflammatory cytokines by keratinocytes and mast cells. It also alleviated atopy by suppressing symptoms without organ toxicity in AD -like mice. UDCA may be an effective and safe treatment for AD.