BACKGROUND

Osteoarthritis (OA) is characterized by inflammation, joint immobility, and pain. Non-pharmacologic agents modulating pro-inflammatory mediator expression offer considerable promise as safe and effective treatments for OA. We previously determined the anti-inflammatory effect of an avocado/soybean unsaponifiables (ASU) and epigallocatechin gallate (EGCG) combination on prostaglandin E2 (PGE2) production and nuclear factor-kappa B (NF-κB) translocation. The aim of this study was to evaluate the effects of ASU + EGCG on pro-inflammatory gene expression.

FINDINGS

Articular chondrocytes from carpal joints of mature horses were pre-incubated for 24 hours with control media alone or ASU (8.3 μg/mL) + EGCG (40 ng/mL), followed by one hour activation with interleukin-1 beta (IL-1β, 10 ng/mL) and tumor necrosis factor-alpha (TNF-α, 1 ng/mL). Total cellular RNA was isolated and real-time PCR performed to measure IL-1β, TNF-α, interleukin-6 (IL-6), cyclooxygenase-2 (COX-2), and interleukin-8 (IL-8) gene expression. Intracellular localization of NF-κB was analyzed by immunohistochemistry and Western blot. Pre-treatment with ASU + EGCG significantly (P < 0.001) decreased gene expression of IL-1β, TNF-α, IL-6, COX-2, and IL-8 in cytokine-activated chondrocytes. Western blot and immunostaining confirmed NF-κB translocation inhibition.

CONCLUSIONS

We demonstrate that ASU + EGCG inhibits cytokine-induced gene expression of IL-1β, TNF-α, IL-6, COX-2, and IL-8 through modulation of NF-κB. Our results indicate that the activity of ASU + EGCG affects a wide array of inflammatory molecules in addition to decreasing PGE2 synthesis in activated chondrocytes. The responsiveness of chondrocytes to this combination supports its potential utility for the inhibition of joint inflammation.