Relationship of serum markers of cartilage metabolism to imaging and clinical outcome measures of knee joint structure.

Background: Biomarkers of cartilage metabolism have prognostic potential.

Objective: To examine whether serum cartilage biomarkers, cartilage oligomeric matrix protein (COMP), N-propeptide of type IIA procollagen (PIIANP), type II collagen breakdown product (collagen type-II cleavage (C2C)) predict cartilage volume loss and knee joint replacement.

Methods: 117 subjects with knee osteoarthritis (OA) had MRI at baseline and 2 years.

Ligands for retinoic acid receptors are elevated in osteoarthritis and may contribute to pathologic processes in the osteoarthritic joint.

Objective: Vitamin A derivatives, including all-trans-retinoic acid (ATRA), have a well-established role during skeletal development and limb formation and have been shown to have profound effects on chondrocyte phenotype. The aim of this study was to elucidate the effects of retinoids and components of the retinoid metabolic pathway on chondrocyte phenotype in the tibiofemoral joints of patients with osteoarthritis (OA), to show that the retinoids can have multiple effects relevant to the OA disease process.

Methods: Human explant tissue and a chondrocyte-like cell line were treated with ATRA, and the responses of 4 key markers of chondrocyte phenotype were analyzed.

Nurr1 dependent regulation of pro-inflammatory mediators in immortalised synovial fibroblasts.

Background: Nurr1 is an orphan member of the nuclear receptor superfamily; these orphan receptors are a group for which a ligand has yet to be identified. Nurr1 has been shown to regulate the expression of a small number of genes as a monomeric, constitutively active receptor. These Nurr1 regulated genes are primarily associated with dopamine cell maturation and survival.