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

Objective: To evaluate the effects of avocado soybean unsaponifiables (ASU) on proinflammatory mediators in chondrocytes and monocyte/ macrophage-like cells. Design: To determine the dose response of ASU, chondrocytes (5 x 10(5) cells/well) were incubated at 5% CO2, 37 degrees 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 mu g/ml. Cells were activated with 20 ng/ml lipopolysaccharide (LPS) for 24 h and cell supernatants were analyzed for prostaglandin E-2 (PGE(2)) and nitrite content. Chondrocytes and THP-1 monocyte/macrophages (5 x 105 cells/well) were incubated at 5% CO2, 37 degrees C for 72 h with (1) control media alone or (2) ASU (25 mu g/ml). One set of cells was activated for I h with LPS (20 ng/ml) for both reverse-transcriptase PCR and real-time PCR analysis of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 -beta (IL-1 beta), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (NOS) expression. One set of cells was activated for 24 h to analyze secreted PGE2 and nitrite levels in the cellular supernatant. Results: ASU reduced TNF-alpha, IL-1 beta, COX-2, and NOS expression in LPS-activated chondrocytes to levels similar to nonactivated control levels. The suppression of COX-2 and NOS expression was paralleled by a significant reduction in PGE(2) and nitrite, respectively, in the cellular supernatant. ASU also reduced TNF-a and IL-1 expression in LPS-activated monocyte/macrophage-like cells. Conclusion: The 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. (c) 2007 OsteoArthritis Research Society International. Published by Elsevier Ltd. All rights reserved.