Development of an in vitro screening assay to test the antiinflammatory properties of dietary supplements and pharmacologic agents

Background: Monocytes- and macrophages are critical in atherosclerosis and on stimulation secrete proinflammatory, proatherogenic cytokines such as tumor necrosi s factor (TNF)-alpha and interleukin (W-113, which have been shown to be present in atherosclerotic lesions. The aim of this study was to develop a rapid in vitro screening assay to test the antiinflammatory effects of different compounds. Methods and Results: THP-1 cells (human monocytic cell line) were stimulated with different concentrations of lipopolysaccharide (LPS; 0 to 1000 mu g/L) and for different times (4, 12, and 24 h), and the secretion of proinflammatory cytokines (IL-1, IL-6, and TNF-alpha) was assessed. TNF-alpha secretion was maximum at the lowest LPS concentration (100 fxg/L) and at shortest duration of incubation (4 h). Maximum secretion of IL-1/3 and IL-6 was achieved at 24 h with higher doses of LPS. Treatment of THP-1 with various test compounds such as dietary supplements (alpha-tocopherol, N-acetylcysteine, catechin and epigallocatechin gallate) as well as pharmacologic agents (statins, peroxisome proliferator-activated receptor-y agonists, and an angiotensin H receptor blocker) significantly inhibited LPS-stimulated TNF-alpha release. Conclusions: The release of TNF-alpha after stimulation of THP-1 cells with LPS is a valid model system to test novel compounds for potential antfinflammatory effects. (c) 2005 American Association for Clinical Chemistry