Effect of a Herbal-Leucine mix on the IL-1β-induced cartilage degradation and inflammatory gene expression in human chondrocytes

Nahid Akhtar,Tariq M Haqqi,Mark Js Miller

doi:10.1186/1472-6882-11-66

Abstract

BackgroundConventional treatments for the articular diseases are often effective for symptom relief, but can also cause significant side effects and do not slow the progression of the disease. Several natural substances have been shown to be effective at relieving the symptoms of osteoarthritis (OA), and preliminary evidence suggests that some of these compounds may exert a favorable influence on the course of the disease. The objective of this study was to investigate the anti-inflammatory/chondroprotective potential of a Herbal and amino acid mixture containing extract of the Uncaria tomentosa, Boswellia spp., Lepidium meyenii and L-Leucine on the IL-1β-induced production of nitric oxide (NO), glycosaminoglycan (GAG), matrix metalloproteinases (MMPs), aggrecan (ACAN) and type II collagen (COL2A1) in human OA chondrocytes and OA cartilage explants.MethodsPrimary OA chondrocytes or OA cartilage explants were pretreated with Herbal-Leucine mixture (HLM, 1-10 μg/ml) and then stimulated with IL-1β (5 ng/ml). Effect of HLM on IL-1β-induced gene expression of iNOS, MMP-9, MMP-13, ACAN and COL2A1 was verified by real time-PCR. Estimation of NO and GAG release in culture supernatant was done using commercially available kits.ResultsHLM tested in these in vitro studies was found to be an effective anti-inflammatory agent, as evidenced by strong inhibition of iNOS, MMP-9 and MMP-13 expression and NO production in IL-1β-stimulated OA chondrocytes (p < 0.05). Supporting these gene expression results, IL-1β-induced cartilage matrix breakdown, as evidenced by GAG release from cartilage explants, was also significantly blocked (p < 0.05). Moreover, in the presence of herbal-Leucine mixture (HLM) up-regulation of ACAN and COL2A1 expression in IL-1β-stimulated OA chondrocytes was also noted (p < 0.05). The inhibitory effects of HLM were mediated by inhibiting the activation of nuclear factor (NF)-kB in human OA chondrocytes in presence of IL-1β.ConclusionOur data suggests that HLM could be chondroprotective and anti-inflammatory agent in arthritis, switching chondrocyte gene expression from catabolic direction towards anabolic and regenerative, and consequently this approach may be potentially useful as a new adjunct therapeutic/preventive agent for OA or injury recovery.

Highlights

Conventional treatments for the articular diseases are often effective for symptom relief, but can cause significant side effects and do not slow the progression of the disease
Chondrocytes with the Herbal-Leucine mixture (HLM) (1 and 5 μg/ml) showed 84-89% decrease in the level of matrix metalloproteinases (MMPs)-9 mRNA expression (p < 0.05), compared to OA chondrocytes not treated with the HLM but were stimulated with IL-1b alone
Pretreatment of chondrocytes with HLM significantly inhibited the MMP-9 production in IL-1b-stimulated OA chondrocytes (64%, Figure 3C; p < 0.05). This inhibition in MMP-9 production was noted when chondrocytes were pre-treated with MG132, a known nuclear factor (NF)-kB inhibitor, which inhibited the MMP-9 production by 47% (Figure 3C; p < 0.05)

Summary

Introduction

Conventional treatments for the articular diseases are often effective for symptom relief, but can cause significant side effects and do not slow the progression of the disease. Osteoarthritis (OA) is the most common form of joint disease that evolves from local inflammatory disease to a chronic process with variable degree of inflammation and degeneration of articular cartilage that results in exposure of underlying bone, pain and cartilage samples is believed to contribute to OA pathogenesis [3,4]. IL-1 receptor antagonist, a natural competitor of IL-1, suppresses cartilage loss, further supporting the role of IL-1 in cartilage breakdown [7]. Both IL-1 and mechanical loading of cartilage increase nitric oxide (NO) production [8,9] by up-regulating the expression of inducible nitric oxide synthase gene (iNOS). Medicinal plants are often cheaper, locally available and consumable

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