Inhibition of cyclooxygenase-2 expression and prostaglandin E2 production in chondrocytes by avocado soybean unsaponifiables and epigallocatechin gallate

SummaryObjectiveTo evaluate the anti-inflammatory effect of the combination of avocado soybean unsaponifiables (ASU) and epigallocatechin gallate (EGCG) on cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) production in cytokine-activated equine chondrocytes.MethodsProduction of type II collagen and aggrecan was verified by immunohistochemistry and Western blot. Chondrocytes were incubated with: (1) control media alone, (2) ASU (4 μg/ml; 8.3 μg/ml), (3) EGCG (4, 40, 400 ng/ml), or (4) the combination of ASU and EGCG for 24 h. Cells were next incubated with control medium alone or with IL-1β (10 ng/ml) and TNF-α (1 ng/ml). COX-2 gene expression by real-time PCR analysis and NF-κB nuclear translocation by immunohistochemistry were performed after 1 h of incubation. PGE2 production was determined by immunoassay after 24 h of incubation.ResultsEquine chondrocytes responded to cytokine activation by up-regulated gene expression of COX-2 and increased PGE2 production. Activation was associated with NF-κB translocation. Individually, ASU and EGCG marginally inhibited COX-2 expression and PGE2 production in activated chondrocytes. In contrast, the combination of ASU and EGCG reduced COX-2 expression close to non-activated control levels and significantly inhibited PGE2 production. These reductions were statistically greater than those of ASU or EGCG alone. The inhibition of COX-2 expression and PGE2 production was associated with inhibition of NF-κB translocation.ConclusionThe present study demonstrates that the anti-inflammatory activity of ASU and EGCG is potentiated when used in combination. This combination may offer an attractive supplement or alternative to non-steroidal anti-inflammatory drugs (NSAIDs) in the management of osteoarthritis.