Key Points Blood-induced joint damage is fully prevented by blocking IL-1β with a monoclonal antibody or receptor antagonist, not by TNFα blockade. IL-1β blockade prevents release of IL-6 but not TNFα from monocyte/macrophages, whereas TNFα blockade does not affect IL-1β or IL-6 release.

Several experimental models of osteoarthritis in rats are used to study the pathophysiology of osteoarthritis. Many mechanically induced models have the limitation that permanent joint instability is induced by, for example, ligament transection or meniscal damage. This permanent instability will counteract the potential beneficial effects of therapy. The groove model of osteoarthritis uses a one‐time trigger, surgically induced cartilage damage on the femoral condyles, and has been validated for the canine tibia‐femoral compartment. The present study evaluates this model for the rat knee joint. The articular cartilage of the weight bearing surface of both femoral condyles and trochlea were damaged (grooved) without damaging the underlying subchondral bone. Severity of joint degeneration was histologically assessed, in addition to patella cartilage damage, and subchondral bone characteristics by means of (contrast‐enhanced) micro‐CT. Mild histological degeneration of the surgically untouched tibial plateau cartilage was observed in addition to damage of the femoral condyles, without clear synovial tissue inflammation. Contrast enhanced micro‐CT demonstrated proteoglycan loss of the surgically untouched patella cartilage. Besides, a more sclerotic structure of the subchondral bone was observed. The tibia‐femoral groove model in a rat results in mild knee joint degeneration, without permanent joint instability and joint inflammation. This makes the rat groove model a useful model to study the onset and progression of post‐traumatic non‐inflammatory osteoarthritis, creating a relatively sensitive model to study disease modifying osteoarthritic drugs. © 2016 The Authors. Journal of Orthopaedic Research published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 35:496–505, 2017.

The results of current preliminary study suggest that IL4-10 FP has DMOAD potentials since it shows chondroprotective and anti-inflammatory effects in vitro, as well as potentially analgesic effect in a canine in vivo model of osteoarthritis.

SummaryThe combination of interleukin (IL)-4 and IL-10 protects against bloodinduced cartilage damage in vitro. It has been hypothesized that the combination of these cytokines is effective if applied early in the process of cartilage damage. The present study investigated whether a single intra-articular injection of IL-4 plus IL-10 immediately after a joint bleed limits cartilage damage in an in vivo haemophilia mouse model of blood-induced joint damage. Factor VIII knockout mice with severe haemophilia A were punctured once with a needle below the patella to induce a joint haemorrhage. Subsequently IL-4 plus IL-10 (n = 24) or vehicle (n = 24) was injected intra-articularly. After 35 days, the time needed for development of detectable joint degeneration, knee joints were examined for cartilage damage by macroscopic and microscopic evaluation. A single intra-articular injection of IL-4 plus IL-10 ameliorated progression of cartilage degeneration caused by a single joint bleed to a certain extent. No effect on inflammation was observed at this time point. A single intra-articular injection of IL-4 plus Il-10 directly after a single joint bleed limits progression of cartilage degeneration over time. Improved bioavailability (half-life) of both cytokines might improve their protective ability in the development of cartilage degeneration, and probably also inflammation.

Evidence is growing for the existence of an obesity-related phenotype of osteoarthritis in which low-grade inflammation and a disturbed metabolic profile play a role. The contribution of an obesity-induced metabolic dysbalance to the progression of the features of osteoarthritis upon mechanically induced cartilage damage was studied in a rat in vivo model. Forty Wistar rats were randomly allocated 1:1 to a standard diet or a high-fat diet. After 12 weeks, in 14 out of 20 rats in each group, cartilage was mechanically damaged in the right knee joint. The remaining six animals in each group served as controls. After a subsequent 12 weeks, serum was collected for metabolic state, subchondral bone changes assessed by μCT imaging, osteoarthritis severity determined by histology, and macrophage presence assessed by CD68 staining. The high-fat diet increased statistically all relevant metabolic parameters, resulting in a dysmetabolic state and subsequent synovial inflammation, whereas cartilage degeneration was hardly influenced. The high-fat condition in combination with mechanical cartilage damage resulted in a clear statistically significant progression of the osteoarthritic features, with increased synovitis and multiple large osteophytes. Both the synovium and osteophytes contained numerous CD68 positive cells. It is concluded that a metabolic dysbalance due to a high-fat diet increases joint inflammation without cartilage degeneration. The dysmetabolic state clearly accelerates progression of osteoarthritis upon surgically induced cartilage damage supported by inflammatory responses as demonstrated by histology and increased CD68 expressing cells localized on the synovial membrane and osteophytes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:881-890, 2018.

Background Joint damage still causes significant morbidity in hemophilia. It results from synovial inflammation and direct cartilage-degenerating properties of blood components. Interleukin (IL)-4 and IL-10 have been shown to protect cartilage from blood-induced damage. Recently an IL4-10 fusion protein has been developed to combine the function of IL-4 and IL-10 and increase their bioavailability. Objectives In this study we evaluate whether this IL4-10 fusion protein protects against blood-induced joint damage. Methods In vitro, human cartilage explants were exposed to whole blood and simultaneously to a broad concentration range of the IL4-10 fusion protein. Effects on cartilage matrix turnover were compared with the individual cytokines. Moreover, the influence of the fusion protein and its individual components on IL-1β and IL-6 production was investigated. In hemophilia A mice, the effect of intra-articular treatment on synovitis and cartilage damage resulting from joint bleeding was evaluated by histochemistry. Results In vitro, the fusion protein prevented blood-induced cartilage damage in a dose-dependent manner, with equal effectiveness to the combination of the separate cytokines. In whole blood cultures 10 ng mL fusion protein completely blocked the production of IL-1β and IL-6 by monocytes/macrophages. In hemophilic mice, intra-articular injection of IL-4 and IL-10 did not influence synovitis or cartilage degeneration. In contrast, equimolar amounts of the fusion protein attenuated cartilage damage upon repeated joint bleeding, although synovial inflammation was hardly affected. Conclusions Overall, this study shows that the IL4-10 fusion protein prevents blood-induced cartilage damage in vitro and ameliorates cartilage degeneration upon joint bleeding in hemophilic mice.

No abstract

Objective An ideal disease modifying osteoarthritis drug (DMOAD) has chondroprotective, anti-inflammatory, and analgesic effects. This study describes the production and characterization of a canine IL4-10 fusion protein (IL4-10 FP) and evaluates its in vivo DMOAD activity in a canine model of osteoarthritis (OA). Design The canine Groove model was used as an in vivo model of degenerative knee OA. Six weeks after OA induction dogs were intra-articularly injected weekly, for ten weeks, with either IL4-10 FP or phosphate buffered saline (PBS). In addition to the use of human IL4-10 FP, canine IL4-10 FP was developed and characterized in vitro , and tested in vivo . Force plate analysis (FPA) was performed to analyze joint loading as a proxy measure for pain. After ten weeks dogs were euthanized and cartilage and synovial tissue samples were analyzed by histochemistry (OARSI scores) and biochemistry (cartilage proteoglycan turnover). Results Repetitive intra-articular injections with human IL4-10 FP led to antibody formation, that blocked its functional activity. Therefore, a canine IL4-10 FP was developed, which completely inhibited LPS-induced TNFα production by canine blood cells, and increased proteoglycan synthesis of canine cartilage in vitro (p = 0.043). In vivo , canine IL4-10 FP restored the, by OA impaired, joint loading (p = 0.002) and increased cartilage proteoglycan content (p = 0.029). Conclusions This first study on the potential DMOAD activity upon prolonged repeated treatment with IL4-10 FP demonstrates that a species-specific variant has anti-inflammatory and chondroprotective effects in vitro and chondroprotective and analgesic effects in vivo . These data warrant further research on the DMOAD potential of the IL4-10 FP.