Lactobacillus paracasei CNCM I-2116 (ST11) inhibits substance P-induced skin inflammation and accelerates skin barrier function recovery in vitro

Over the past few decades the number of people presenting reactive skin has increased in industrial countries. Skin inflammation mediated by neuropeptides and impaired skin barrier function are both underlying features of reactive skin conditions. Live microorganisms defined as probiotics have been successfully used to improve health status in humans. Beyond the effects on intestinal microbiota, some probiotic strains display potent immune-modulatory properties at the skin level. The aim of this study was to evaluate whether Lactobacillus paracasei CNCM-I 2116 (ST11) could modulate reactive skin-associated inflammatory mechanisms. The Caco-2/PBMC co-culture cell system was stimulated on the apical side with probiotics. The resulting medium collected from the basolateral compartment of the cell culture system, so called conditioned medium, was tested in ex vivo human abdominal plastic skin explant models of substance P-induced skin inflammation and skin barrier reconstruction. We show that ST11 was able to abrogate vasodilation, edema, mast cell degranulation and TNF-alpha release induced by substance P, compared to control. Moreover, using ex vivo skin organ culture, we show that ST11-conditioned medium induced a significantly faster barrier function recovery after SLS disruption, compared to control. These results support a beneficial role of ST11 on key biological processes associated with barrier function and skin reactivity.