# Skim Milk Culture of Lactobacillus johnsonii SBT0309 Increases Intestinal Alkaline Phosphatase Activity and Inhibits Lipopolysaccharide-Induced Interleukin-8 Production in Intestinal Epithelial Cells

## TL;DR

A fermented milk made with Lactobacillus johnsonii SBT0309 boosts intestinal enzyme activity and reduces inflammation in intestinal cells.

## Contribution

Identifies a specific fermented milk that activates intestinal alkaline phosphatase and reduces LPS-induced inflammation in intestinal cells.

## Key findings

- LJ0309 SC significantly increased IAP gene expression and protein levels in Caco-2 cells.
- LJ0309 SC inhibited IL-8 secretion in LPS-stimulated Caco-2 cells.
- LJ0309 SC increased IAP activity and gene expression in Drosophila midgut.

## Abstract

Background/Objectives: Intestinal alkaline phosphatase (IAP) is an enzyme expressed in the intestinal brush border, which may exert anti-inflammatory effects by detoxifying lipopolysaccharides (LPSs), thereby preventing metabolic disorders. Various food components have been reported to influence IAP activity. However, few studies have evaluated the effects of fermented milk on IAP activity. In this study, we aimed to investigate fermented milk with high IAP-activating capacity and investigate its effect. Methods: We screened a skim milk culture (SC), a fermented milk model, using differentiated Caco-2 cells. We investigated the effect of SC on IAP activity and gene expression in the Drosophila midgut. Quantitative PCR and immunoblot assays were conducted to examine gene and protein levels. Results: Among the SC samples from different lactic acid bacteria or bifidobacteria, the SC of Lactobacillus johnsonii SBT0309 (LJ0309 SC) demonstrated a particularly strong capacity to activate IAP in Caco-2 cells, demonstrated by significantly increased IAP gene expression and protein levels in Caco-2 cells. Additionally, LJ0309 SC inhibited increased secretion of IL-8 in LPS-stimulated Caco-2 cells. Finally, in Drosophila melanogaster fed LJ0309 SC, we observed an increase in both IAP activity and gene expression in the midgut. Conclusions: LJ0309 SC increased IAP activity and gene expression in both Caco-2 cells and the Drosophila midgut, and inhibited the inflammatory response in LPS-stimulated Caco-2 cells. Although further in vivo studies are required, LJ0309 SC might help to ameliorate LPS-induced inflammation and disease via IAP activation.