Bone Abstracts

Introduction: Meniscus plays an essential role in knee joint function providing stability and load transmission. In osteoarthritis (OA), a joint disease characterized by chronic synovitis and cartilage degeneration, pathological changes in the menisci are observed. However, whether menisci contribute to the progression of OA, the underlying mechanism for meniscus-cartilage communication is still unclear. In this study we analyzed systematically the response of meniscus and cartilage explants to a number of inflammatory mediators, in order to reveal their response similarity and highlight potential crosstalks and interactions.

Methods: OA cartilage and the lateral meniscus were harvested from two patients undergoing total knee arthroplasty. Meniscus and cartilage disks (3 mm diameter) were stimulated with inflammatory mediators ((IL-1α, IL-1β, IL-12α, CSF2) (50 ng/ml), (TNF-α, IL-6, CXCL7, IL-8, CCL2, CXCL10, IFN-γ, IL-3, MIA2, IL-4) (100 ng/ml) and GROα (500 ng/ml)) for 24 h. For each condition the release of different proteins (IL-1α, IL-1β, TNF-α, IL-6, CXCL7, GROα, IL-8, CCL2, CXCL10, IFN-γ, IL-3, IL-12α, MIA-2, CSF2, IL-4) was measured in the supernatant using custom multiplexed assays on a Luminex FlexMap 3D instrument.

Results: In both tissues the major inflammatory players (IL-1α, IL-1β, TNFα) were the strongest stimuli as expected. Meniscus responses were the same up to 73 and 50% with the cartilage ones for the first and the second donors respectively. Interestingly, meniscus under certain stimuli (IL-1α, IFN-γ, CSF2, IL-8) responded differently than cartilage by releasing five different cytokines while cartilage did not.

Conclusions: Our results indicate that meniscus is affected by its inflammatory environment and responds to it as actively as cartilage. Moreover, the release of different cytokines from meniscus and cartilage suggests that meniscus can be an active player in the progression of OA. These data support the hypothesis that significant crosstalk between these two knee compartments exist and anti-inflammatory therapies should take into consideration both tissues.