Pasteurized Akkermansia muciniphila HB05 improves ultraviolet B-induced skin dehydration and barrier dysfunction in SKH-1 hairless mice

Ultraviolet B (UVB) radiation is a major environmental stressor that disrupts epidermal hydration, impairs barrier integrity, and accelerates photoaging through oxidative and inflammatory mechanisms. Although the metabolic and immunomodulatory benefits of Akkermansia muciniphila have been extensively investigated, its role in skin health remains largely unknown. In particular, the effects of pasteurized A. muciniphila on UVB-induced skin dehydration or barrier dysfunction have not been systematically evaluated. In this study, we investigated the protective effects of pasteurized A. muciniphila HB05 (HB05P) produced via a low-temperature inactivation process, which has enhanced stability and safety, guaranteed cell content, and preserved bioactivity. In UVB-exposed human keratinocytes and SKH-1 hairless mice, HB05P significantly ameliorated UVB-induced epidermal dehydration and wrinkle formation and restored the expression of skin barrier- and hydration-associated genes, such as filaggrin, aquaporins, and collagen type I alpha 1. Additionally, HB05P attenuated UVB-triggered inflammatory responses and restored antioxidant enzyme activities. Western blot and immunohistochemical analyses revealed attenuation of JNK and p38 phosphorylation and decreased nuclear factor kappa B (NFκB) p65 nuclear translocation, indicating an association between HB05P treatment and reduced mitogen-activated protein kinase and NFκB signaling pathway activation. Collectively, these preclinical findings identified HB05P as a candidate paraprobiotic ingredient with promising potential to improve skin hydration and barrier function under photodamaging conditions. This study provides the first experimental evidence supporting the investigation of pasteurized A. muciniphila for skin health.