Effects of triclosan on cytokine production by human immune cells in vitro
Mai Homburg, María Teresa Martín Monreal, Åse Krogh Rasmussen, Claus Henrik Nielsen, Hanne Frederiksen, Marya Morevati, Ulla Feldt‐Rasmussen
Abstract
BACKGROUND: Triclosan, an antibacterial agent with structural similarity to thyroxine, is used in personal and industrial products. Increasing evidence demonstrates a negative influence of triclosan on both the endocrine and the immune system. OBJECTIVES: The aim of this in vitro study was to characterize the effect of triclosan on cytokine responses of peripheral blood mononuclear cells (PBMCs). METHODS: Human PBMCs were exposed to triclosan and stimulated with lipopolysaccharide (LPS) or phytohemagglutinin-L (PHA-L) to stimulate primarily monocytes/macrophages of the innate immune system and T lymphocytes of the adaptive immune system, respectively, for 20-22 h. Cell viability was assessed. The cytokine response was quantified. Triclosan was measured in cell homogenate. RESULTS: The LPS-induced secretion of interleukin (IL)-1β and IL-10 by PBMCs was enhanced by co-incubation with 0.003, 0.3 and 3.0 µM triclosan, while the induced secretion of tumor necrosis factor (TNF)-α and IL-6 increased after co-incubation with 3.0 µM triclosan. The PHA-L-induced secretion of IL-2 was inhibited after co-exposure to 3.0 µM triclosan and of several further cytokines after co-exposure to 9.0 µM triclosan. The percentage of dead cells was increased in cultures incubated with 9 µM triclosan. After incubation of PBMCs with triclosan, triclosan was detected intracellularly. DISCUSSION: Our observations indicate a dose-dependent uptake of triclosan in PBMCs, and that triclosan enhances the cytokine secretion by LPS-stimulated PBMC, while inhibiting the pro-inflammatory response by PHA-stimulated PBMCs. Further investigations of the effect of triclosan are needed to uncover the potential risk of exposure to triclosan.