Background: Macrophages are the main players involved in inflammation. Intercellular
adhesion molecule-1 (ICAM-1) facilitates macrophage polarization prior to extravasation into inflamed
tissue. Piperine, a natural product derived from black pepper, possesses useful biological
and pharmacological activities. In the current study, the possible anti-inflammatory effect of piperine
on the expression of ICAM-1 on J774.1 murine macrophage cell line was investigated.
Methods: Lipopolysaccharide (LPS)-stimulated J774.1 cells were cultured in the presence of different
concentrations of piperine to examine the changes in ICAM-1 expression by real-time PCR
and flow cytometry.
Results: We found that piperine decreased ICAM-1 gene expression level from 2.4 ± 0.25 RFC
(relative fold change) in LPS-only treated cells to 0.85 ± 0.525 RFC at 1µg/ml (p<0.05), 0.43 ±
0.27 RFC at 10µg/ml (p<0.01), and 0.26 ± 0.25 RFC at 20µg/ml (p<0.01). In flow cytometry,
piperine at all concentrations significantly decreased ICAM-1 surface expressions (P<0.05). The
geometric mean fluorescence intensity (g-MFI) in LPS-only treated cells (792 ± 57.3) decreased to
482±70 g-MFI at 20 μg/ml piperine.
Conclusion: According to the results of this study, by decreasing the expression of ICAM-1, piperine
has been suggested to reduce inflammation and have the potential to provide therapeutic benefits
for immune-mediated diseases.