Low-fat yogurt alleviates the pro-inflammatory cytokine IL-1β-induced intestinal epithelial barrier dysfunction

Yogurt is a source of bioactive compounds and probiotic microorganisms that modify immunity and metabolism to benefit human health beyond nutrition. In this study, we examined the capacity of yogurt to prevent epithelial barrier disruption in vitro. Different preparations of yogurt were added apically to Caco-2 monolayers before IL-1β exposure. Dulbecco's modified Eagle medium containing 25% (vol/vol) low-fat yogurt prevented cytokine-induced transepithelial resistance reduction and increases to paracellular permeability measured with fluorescein isothiocyanate-dextran (4 kDa), whereas nonfat yogurt was unable to decrease paracellular permeability to fluorescein isothiocyanate-dextran. Moreover, the concentration of IL-8 in low-fat-yogurt-treated inflamed cells was decreased to 252.40 ± 27.24 pg/mL, which was lower than that of untreated, inflamed cells (407.20 ± 50.05 pg/mL), further indicating the anti-inflammatory roles of low-fat yogurt. The low-fat yogurt was able to downregulate the transcription of myosin light-chain kinase (MLCK) gene, but upregulate the expression of tight junction protein ZO-1 (TJP1). These findings indicate that low-fat yogurt can maintain intestinal barrier integrity better than nonfat yogurt after pro-inflammatory cytokine exposure.