Avocado soybean unsaponifiables (ASU) suppress TNF-α, IL-1β, COX-2, iNOS gene expression, and prostaglandin E2 and nitric oxide production in articular chondrocytes and monocyte/macrophages

SummaryObjectiveTo evaluate the effects of avocado soybean unsaponifiables (ASU) on proinflammatory mediators in chondrocytes and monocyte/macrophage-like cells.DesignTo determine the dose response of ASU, chondrocytes (5 × 105 cells/well) were incubated at 5% CO2, 37°C for 72 h with (1) control media alone or (2) ASU at concentrations of 0.3, 0.9, 2.7, 8.3, and 25 μg/ml. Cells were activated with 20 ng/ml lipopolysaccharide (LPS) for 24 h and cell supernatants were analyzed for prostaglandin E2 (PGE2) and nitrite content. Chondrocytes and THP-1 monocyte/macrophages (5 × 105 cells/well) were incubated at 5% CO2, 37°C for 72 h with (1) control media alone or (2) ASU (25 μg/ml). One set of cells was activated for 1 h with LPS (20 ng/ml) for both reverse-transcriptase PCR and real-time PCR analysis of tumor necrosis factor-alpha (TNF-α), interleukin-1-beta (IL-1β), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) expression. One set of cells was activated for 24 h to analyze secreted PGE2 and nitrite levels in the cellular supernatant.ResultsASU reduced TNF-α, IL-1β, COX-2, and iNOS expression in LPS-activated chondrocytes to levels similar to nonactivated control levels. The suppression of COX-2 and iNOS expression was paralleled by a significant reduction in PGE2 and nitrite, respectively, in the cellular supernatant. ASU also reduced TNF-α and IL-1β expression in LPS-activated monocyte/macrophage-like cells.ConclusionThe present study demonstrates that the anti-inflammatory activity of ASU is not restricted to chondrocytes, but also affects monocyte/macrophage-like cells that serve as a prototype for macrophages in the synovial membrane. These observations provide a scientific rationale for the pain-reducing and anti-inflammatory effects of ASU observed in osteoarthritis patients.