Effect of nonfat dry milk and major whey components on interleukin-6 and interleukin-8 production in human intestinal epithelial-like Caco-2 cells

Bovine nonfat dry milk (NDM) and major whey components (lactose, alpha-lactalbumin, and beta-lactoglobulin) were evaluated for their effects on IL-6 and IL-8 production in human intestinal-like Caco-2 cells unstimulated or stimulated with IL-1 beta. All the whey components investigated and NDM induced IL-6 production by Caco-2 cells; the most significant increase was observed with beta-lactoglobulin. In the case of IL-1 beta-stimulated cells, neither NDM nor the major whey components investigated contributed to the induction of IL-6 production after they were stimulated. Induction of IL-8 production by both alpha-lactalbumin and beta-lactoglobulin was higher than that by lactose and NDM; alpha-lactalbumin was a more potent inducer of IL-8 than beta-lactoglobulin and IL-1 beta alone in both unstimulated and stimulated cells. In Caco-2 cells that were stimulated with IL1-beta, NDM and all the major whey components investigated had a synergistic effect on induction of IL-8 production, indicating that IL-8 induction was amplified by prior stimulation of cells by IL-1 beta. This synergistic effect was not observed with IL-6. Our results suggest that immunomodulatory properties of milk components may be affected by other complex events in the gut.