Lactobacillus paracasei CNCM I-5220-derived postbiotic counteracts skin inflammation and protects skin barrier integrity

IntroductionSkin inflammation and damage of skin barrier integrity contribute to the pathogenesis of inflammatory skin diseases such as psoriasis and atopic dermatitis. Nowadays, there is a growing interest in alternative and complementary strategies to counteract skin inflammation and treat dermatologic conditions. ObjectivesPostbiotics, metabolites released during bacterial fermentation, exert anti-inflammatory proprieties and contribute to the maintenance of epithelial barrier integrity. Therefore, we investigated the effect of LP-PBL, a novel Lactobacillus paracasei CNCM I-5220-derived postbiotic, in controlling skin inflammation and protecting the skin barrier. MethodsWe performed RNA-sequencing on Poly(I:C)-stimulated keratinocytes and investigated LP-PBL efficacy in regulating pro-inflammatory cytokine release. The production of most relevant cytokines was demonstrated by ELISA. Then, we tested postbiotic lenitive efficacy on healthy volunteers irritated skin. We compared the effect of a postbiotic-containing cream formulation versus placebo on sodium lauryl sulphate treated skin. ResultsWe demonstrate that LP-PBL has anti-inflammatory activity by modulating Poly(I:C)-dependent inflammatory pathways and pro-inflammatory cytokine release in keratinocytes. The postbiotic inhibited the upregulation of interleukin (IL)-23A, which is overexpressed in psoriatic skin, and of IL-33 and thymic stromal lymphopoietin (TSLP) that are upregulated in atopic dermatitis. Moreover, it increased filaggrin and zonula occludens (ZO)-1 expression in Poly(I:C)-stimulated keratinocytes, suggesting beneficial effects on inflamed and damaged skin. Consistently, a clinical test on healthy volunteers showed that topic LP-PBL treatment significantly reduced skin redness upon sodium lauryl sulphate challenge compared to placebo, leading to a rapid recovery of the irritated skin. ConclusionOverall, we demonstrated the protective role of LP-PBL on the skin, both in vitro and in the clinical test, suggesting that postbiotic topical application could represent an innovative and promising strategy to counteract skin inflammation and preserve skin barrier integrity.