Intra-articular Recombinant Human Proteoglycan 4 Mitigates Cartilage Damage After Destabilization of the Medial Meniscus in the Yucatan Minipig

Abstract

Background Lubricin, or proteoglycan 4 (PRG4), is a glycoprotein responsible for joint boundary lubrication. PRG4 has been previously shown to be down-regulated following traumatic joint injury such as a meniscal tear. There is preliminary evidence suggesting that intra-articular injection of PRG4 post-injury will reduce cartilage damage in rat models of surgically-induced post-traumatic osteoarthritis. Objective To determine the efficacy of intra-articular injection of full length recombinant human lubricin (rhPRG4) for reducing cartilage damage after medial meniscus destabilization (DMM) in a pre-clinical large animal model. Study Design Controlled laboratory study Methods Unilateral DMM was performed in 29 Yucutan minipigs. One week post-DMM, animals received 3 weekly intra-articular injections (3cc/injection): 1) rhPRG4 [1.3mg/ml; n=10], 2) rhPRG4+hyaluronan [1.3mg/ml rhPRG4 and 3mg/ml hyaluronan (~950 kDA); n=10], and 3) phosphate buffered saline [PBS; n=9]. Hind limbs were harvested 26 weeks post-surgery. Cartilage integrity was evaluated using macroscopic (India Ink) and microscopic (Safranin O-fast green and hematoxylin & eosin) scoring systems. Secondary outcomes evaluated using ELISA included PRG4 levels in synovial fluid, CTX-II concentrations in urine and serum, and IL-1β levels in synovial fluid and serum. Results The rhPRG4 group had significantly less macroscopic cartilage damage in the medial tibial plateau compared to the PBS group (p=.002). No difference was found between the rhPRG4+hyaluronan and PBS groups (p=.23). However, no differences in microscopic damage scores were observed between the three groups (p=.70). PRG4 production was elevated in the rhPRG4 group synovial fluid compared to the PBS group (p=.033). The rhPRG4 group presented significantly lower urinary CTX-II levels, but not serum levels, when compared to the PBS (p=.013) and rhPRG4+hyaluronan (p=.011) groups. In serum and synovial fluid, both rhPRG4 (p=.006; p=.017) and rhPRG4+hyaluronan groups (p=.009; p=.03) presented decreased IL-1β levels. Conclusion All groups exhibited significant cartilage degeneration following DMM surgery. However, animals treated with rhPRG4 had the least amount of cartilage damage and less inflammation, providing evidence that intra-articular injections of rhPRG4 may slow the progression of post-traumatic osteoarthritis. Clinical Relevance Patients with meniscal trauma are at high risk for post-traumatic osteoarthritis. This study demonstrates that an intra-articular injection regimen of rhPRG4 may attenuate cartilage damage following meniscal injury.

Glycosaminoglycan and Proteoglycan Biotherapeutics in Articular Cartilage Protection and Repair Strategies: Novel Approaches to Visco‐supplementation in Orthobiologics

“…High molecular weight HA has chondro-protective properties through its ability to inhibit degradative MMP production by chondrocytes stimulated with inflammatory mediators [135] and also modulate synoviocytes within the joint. The synergism of PRG4 and HA in joint lubrication, [100,139] chondro-protective efficacy of PRG4 in a model of OA [103] and in the regulation of inflammation/innate immunity in the joint, [96,138,140] has already been established. [136] PRG4 localizes HA at the articular cartilage surface and promotes boundary lubrication but also inhibits attachment of immune cells which could lead to local inflammatory conditions causing depolymerization of HA and impaired joint lubrication.…”

“…[93] Versican and aggrecan both form ternary complexes with HA and link protein in articular cartilage. [103] Biglycan, a SLRP with two CS/DS GAG chains, also has a prominent pericellular immunolocalization pattern in articular cartilage (Figure 9a) while decorin, has a single CS or DS chain and is distributed more prominently in the inter-territorial matrix ( Figure 9b). [93] Aggrecan, however, has a more widespread distribution, like perlecan, throughout the cartilage matrix which experiences compressive loading.…”

“…[133] PRG4 like HA also has anti-inflammatory [133] and cell directive properties. [96,100,103,137,138] Thus novel formulations of viscosupplements incorporating HA and PRG4 are worthy of further evaluation and may have a global joint protective effect in OA. [102] Alkyl HA derivatives are also effective at inhibiting MMP production and activation.…”

Cathepsin g degrades synovial fluid lubricin: relevance for osteoarthritis pathogenesis

“…Despite being one of the most common and disabling joint diseases, OA pathogenesis and development are still largely unknown. The success of introducing recombinant lubricin for OA treatment in animal models 40,41 , indicate a role of lubricin in OA pathogenesis. To date, improper lubricin post-translational modifications, including glycosylation profile change 42 , forming complex with other matrix proteins 43 , and proteolytic cleavages are all reported in OA.…”

Core-2 O-glycans are required for galectin-3 interaction with the osteoarthritis related protein lubricin

“…In rodent models, addition of lubricin has been shown to delay the progression of OA 24 . Intra-articular injections of rhPRG4 in guinea pigs 25 and Yucatan minipigs 25 with medial meniscal destabilization, a model system for posttraumatic OA, exhibited decreased cartilage damage and inflammation. Lubricin may therefore be a potential candidate for treatment of OA.…”