Cartilage articulaire normal : anatomie, physiologie, métabolisme, vieillissement

Intra-Articular Hyaluronic Acid and Chondroitin Sulfate: Pharmacokinetic Investigation in Osteoarthritic Rat Models

Background

Viscosupplementation of synovial fluid with intra-articular (IA) injections of hyaluronic acid (HA) is widely used for symptomatic treatment of osteoarthritis (OA). Herein we present HCS, a new combination of chemicals, associating HA and chondroitin sulfate (CS), both members of the glycosaminoglycan (GAGs) family, which are major components of the joint. HA provides viscosity to the synovial fluid and CS provides elasticity to the cartilage. Reduced levels of HA and CS are observed in OA joints and are associated with progressive cartilage damage and loss.

Objective

The objective of the study was to evaluate the pharmacokinetic (PK) properties of both HA and CS after IA administration in a validated OA animal model.

Methods

Motion impairment measurements and histological examinations were used to validate the ability of an IA injection of mono-iodoacetate (MIA) in the knee of rats to induce OA symptoms. Then, the PK properties of HA and CS after IA administration were characterized and each active ingredient was independently profiled: HA was labeled with tritium (3H-HA) and CS was labeled with carbon 14. (14C-CS) The final radio-labeled solution reproduced the cold HCS formulation.

Results

Four male Sprague-Dawley rats received a 1 mg MIA injection on day 1, then motor impairment was monitored from day 4 to day 18. Chondrocyte necrosis, loss of GAGs and other cartilage damage were observed. Twelve other rats received a MIA IA injection on day 1 then a radio-labeled HCS IA injection (50 µL) on day 8. Plasma and knee cartilage were collected postadministration and the terminal half-life was similar in both matrices (about 5 days), for both 3H-HA and 14C-CS.

Conclusions

Despite differences in their molecular size, HA and CS showed PK behavior similarly characterized by prolonged residence inside the joint and slow release in plasma, favoring long-term beneficial effects. (Curr Ther Res Clin Exp. 2020; 92:XXX-XXX).

C2K77 ELISA detects cleavage of type II collagen by cathepsin K in equine articular cartilage

OBJECTIVES

Develop a species-specific ELISA for a neo-epitope generated by cathepsin K cleavage of equine type II collagen to: (1) measure cartilage type II collagen degradation by cathepsin K in vitro, (2) identify cytokines that upregulate cathepsin K expression and (3) compare cathepsin K with matrix metalloproteinase (MMP) collagenase activity in stimulated cartilage explants and freshly isolated normal and osteoarthritic (OA) articular cartilages.

DESIGN

A new ELISA (C2K77) was developed and tested by measuring the activity of exogenous cathepsin K on equine articular cartilage explants. The ELISA was then employed to measure endogenous cathepsin K activity in cultured cartilage explants with or without stimulation by interleukin-1 beta (IL-1β), tumour necrosis-alpha (TNF-α), oncostatin M (OSM) and lipopolysaccharide (LPS). Cathepsin K activity in cartilage explants (control and osteoarthritic-OA) and freshly harvested cartilage (control and OA) was compared to that of MMPs employing C2K77 and C1,2C immunoassays.

RESULTS

The addition of Cathepsin K to normal cartilage caused a significant increase (P < 0.01) in the C2K77 epitope release. Whereas the content of C1,2C, that reflects MMP collagenase activity, was increased in media by the addition to cartilage explants of TNF-α and OSM (P < 0.0001) or IL-1β and OSM (P = 0.002), no change was observed in C2K77 which also unchanged in OA cartilages compared to normal.

CONCLUSIONS

The ELISA C2K77 measured the activity of cathepsin K in equine cartilage which was unchanged in OA cartilage. Cytokines that upregulate MMP collagenase activity had no effect on endogenous cathepsin K activity, suggesting a different activation mechanism that requires further study.