Comparative Analyses of Pharmaceuticals or Food Supplements Containing Chondroitin Sulfate: Are Their Bioactivities Equivalent?

Introduction

Oral supplementation of chondroitin sulfate (CS) and glucosamine (GlcN), symptomatic slow-acting molecules, is recommended by European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis and Musculoskeletal Diseases (ESCEO) and other European Union (EU) guidelines for the restoration of the articular cartilage surface in patients affected by osteoarthritis (OA). They are commercialized as pharmaceutical grade products and as food supplements in combination with plant extracts hyaluronic acid, methylsulfonylmethane, and other components. Food supplements do not need to undergo the strict regulatory controls of pharmaceutical grade products; thus, composition and contaminants that could be present may not be evidenced before commercialization and these uncertainties may give rise to concerns about the bioactivity of these formulations.

Methods

In this paper 10 different food supplements (FS) from diverse European countries were analyzed in comparison with two pharmaceutical grade products (Ph) using updated analytical approaches and biochemical cell-based assays. The purity, the titer, and the origin of CS in Ph and FS samples were initially assessed in order to successively compare the biological function. Both food supplements and pharmaceutical formulations were tested in vitro, using the same final CS concentration, on primary chondrocytes and synoviocytes in terms of (i) cell viability, (ii) activation of the NF-κB-mediated inflammation pathway, (iii) cartilage oligomeric matrix protein (COMP-2), IL-6, and IL-8 production.

Results

All the FS presented a certain insoluble fraction; the CS and the GlcN contents were lower than the declared ones in 9/10 and 8/10 samples, respectively. All FS contained keratan sulfate (KS) at up to 50% of the total glycosaminoglycan amount declared on the label. Primary cells treated with the samples diluted to present the same CS concentration in the medium showed cytotoxicity in 7/10 FS while Ph preserved viability and reduced NF-κB, COMP-2, and secreted inflammatory cytokines.

Conclusion

Among all samples tested, the pharmaceutical grade products demonstrated effective modulation of biomarkers counteracting the inflammation status and improving viability and the physiological condition of OA human primary chondrocyte and synoviocyte cells. In contrast to that, most FS were cytotoxic at the tested concentrations, and only 3/10 of them showed similarities to Ph sample behavior in vitro.

Funding

This work was partially supported by PON01_1226 NUTRAFAST, MIUR Ministero dell’Università e della Ricerca Scientifica. Bioteknet financed two short-term grants for graduate technicians. The journal’s Rapid Service and Open Access fees were funded by IBSA CH.

Protective effects of alogliptin against TNF-α-induced degradation of extracellular matrix in human chondrocytes

Osteoarthritis (OA) is a common debilitating disease most prevalent among the elderly population worldwide. Excessive degradation of the articular extracellular matrix is a pivotal event in the development of OA. Preventative treatments against the destruction of type II collagen and aggrecan, the two main components of the articular extracellular matrix, may serve as a novel therapy against the progression of OA. In the current study, we investigated whether the DPP-4 inhibitor alogliptin could prevent degradation of the articular extracellular matrix in human primary chondrocytes. Pretreatment with alogliptin successfully prevented degradation of type II collagen and aggrecan in a dose-dependent manner by reducing increased expression of MMP-1, -3, and -13 as well as ADAMTS-4 and -5 induced by treatment with TNF-α. Furthermore, pretreatment with alogliptin also reduced TNF-α-induced expression of IKKα/β, IκBα and NF-κB in human primary chondrocytes. This suggests that DPP-4 inhibitors such as alogliptin may be used as an effective preventative therapy against continued destruction of the articular extracellular matrix in OA.

Effect of glucosamine and its peptidyl-derivative on the production of extracellular matrix components by human primary chondrocytes

OBJECTIVE

Aim of this study is to investigate the effects of Glucosamine (GlcN) and its peptidyl-derivative, 2-(N-Acetyl)-L-phenylalanylamido-2-deoxy-β-D-glucose (NAPA), on extracellular matrix (ECM) synthesis in human primary chondrocytes (HPCs).

METHODS

Dose-dependent effect of GlcN and NAPA on Glycosaminoglycan (GAG), Collagen type II (Col2) and Small Leucine-Rich Proteoglycans (SLRPs) was examined by incubating HPCs, cultured in micromasses (3D), with various amounts of two molecules, administered as either GlcN alone or NAPA alone or GlcN plus NAPA (G + N). Immunohystochemical and immunofluorescent staining and biochemical analysis were used to determine the impact of the two molecules on ECM production. Gene expression analysis was performed by TaqMan Real-Time Polymerase Chain Reaction (PCR) assays.

RESULTS

The lowest concentration to which GlcN and NAPA were able to affect ECM synthesis was 1 mM. Both molecules administered alone and as G + N stimulated GAGs and SLRPs synthesis at different extent, NAPA and mainly G + N stimulated Col2 production, whereas GlcN was not effective. Both molecules were able to induce Insulin Growth Factor-I (IGF-I) and to stimulate SOX-9, whereas NAPA and G + N were able to up-regulate both Hyaluronic Acid Synthase-2 and Hyaluronic acid. Very interesting is the synergistic effect observed when chondrocyte micromasses were treated with G + N.

CONCLUSIONS

The observed anabolic effects and optimal concentrations of GlcN and NAPA, in addition to beneficial effects on other cellular pathways, previously reported, such as the inhibition of IKKα, could be useful to formulate new cartilage repair strategies.