Anti-inflammatory and barrier-restoring effects of heat-killed Lactiplantibacillus plantarum postbiotics in an in vitro model of atopic dermatitis

Abstract Aims Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by damage to the epidermal barrier. This study explores the potential of postbiotics as therapeutic agents for AD by evaluating their effects on inflammation-induced keratinocytes. Methods and results Lactiplantibacillus plantarum strains isolated from Kimchi, a traditional Korean fermented food, were heat-treated and used as postbiotic candidates. Three postbiotic candidates were selected and evaluated for their antimicrobial activity, antioxidant capacity, and cellular effects. Postbiotics exhibited antimicrobial activity against skin inflammation–related bacteria and demonstrated strong antioxidant capacity. In addition, they positively modulated pro-inflammatory cytokines (IL-6, IL-8, TSLP) and skin barrier–related genes (INV, FLG, LOR) in keratinocytes stimulated with TNF-α/IFN-γ. Conclusions Heat-killed postbiotics from L. plantarum showed antimicrobial, antioxidant activities, suppressed inflammatory cytokines, and enhanced skin barrier function. These results suggest their potential as therapeutic agents for AD and related skin conditions.