Development of an In Vitro Screening Assay to Test the Antiinflammatory Properties of Dietary Supplements and Pharmacologic Agents

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Abstract
Background: Monocytes and macrophages are critical in atherosclerosis and on stimulation secrete proinflammatory, proatherogenic cytokines such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β, 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 μg/L) and for different times (4, 12, and 24 h), and the secretion of proinflammatory cytokines (IL-1, IL-6, and TNF-α) was assessed. TNF-α secretion was maximum at the lowest LPS concentration (100 μg/L) and at shortest duration of incubation (4 h). Maximum secretion of IL-1β 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 (α-tocopherol, N-acetylcysteine, catechin and epigallocatechin gallate) as well as pharmacologic agents (statins, peroxisome proliferator-activated receptor-γ agonists, and an angiotensin II receptor blocker) significantly inhibited LPS-stimulated TNF-α release. Conclusions: The release of TNF-α after stimulation of THP-1 cells with LPS is a valid model system to test novel compounds for potential antiinflammatory effects.