Capsaicin Modulates the Immune Cross Talk Between Human Mononuclears and Cells from Two Colon Carcinoma Lines

Abstract

ABSTRACTBackground: Capsaicin, the pungent alkaloid of the chili peppers, has gained a worldwide reputation. In addition to its culinary assets, capsaicin possesses analgesic, anti-inflammatory, antimicrobial, and even carcinopreventive properties. Considering the linkage between chronic inflammation and tumorigenesis, the aim of the study was to evaluate the role of capsaicin in the immune interplay between human peripheral blood mononuclear cells (PBMCs) and HT-29 or RKO cells from human colon carcinoma lines. Methods: PBMCs were incubated for 24 hours with either HT-29 or RKO cells and concentrations of capsaicin ranging between 10 and 200 µM. Subsequently, the generation of the following cytokines was examined: tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, interferon (IFN)-γ, IL-1ra, and IL-10. Results: Capsaicin caused a concentration-dependent inhibition of colon cancer cells proliferation but had no effect on PBMC viability. 200 µM of capsaicin suppressed the production of all cytokines tested. At lower concentrations, the secretion of TNF-α, IL-1β, IFN-γ, IL-10, and IL-1ra was inhibited concentration-dependently, whereas that of IL-6 was stimulated. Conclusions: Capsaicin causes a concentration-dependent alteration of the immune balance between PBMC and colon carcinoma cells expressed as an inhibited generation of inflammatory cytokines. These findings indicate the existence of an additional immunomodulatory mechanism by which this alkaloid may prevent tumor development.