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 necrosis factor (TNF)-alpha and interleukin (IL)-1beta, 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 microg/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 microg/L) and at shortest duration of incubation (4 h). Maximum secretion of IL-1beta 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-gamma agonists, and an angiotensin II 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 antiinflammatory effects.