Extracellular localization of galectin-3 has a deleterious role in joint tissues.

In this study we examine the extracellular role of galectin-3 (gal-3) in joint tissues. Following intra-articular injection of gal-3 or vehicle in knee joints of mice, histological evaluation of articular cartilage and subchondral bone was performed. Further studies were then performed using human osteoarthritic (OA) chondrocytes and subchondral bone osteoblasts, in which the effect of gal-3 (0 to 10 microg/ml) was analyzed.

The shunt from the cyclooxygenase to lipoxygenase pathway in human osteoarthritic subchondral osteoblasts is linked with a variable expression of the 5-lipoxygenase-activating protein.

Osteoarthritis (OA) is characterized by articular cartilage degradation and hypertrophic bone changes with osteophyte formation and abnormal bone remodeling. Two groups of OA patients were identified via the production of variable and opposite levels of prostaglandin E2 (PGE2) or leukotriene B4 (LTB4) by subchondral osteoblasts, PGE2 levels discriminating between low and high subgroups. We studied whether the expression of 5-lipoxygenase (5-LO) or 5-LO-activating protein (FLAP) is responsible for the shunt from prostaglandins to leukotrienes.

Ten years in the life of an enzyme: the story of the human MMP-13 (collagenase-3).

In 1994, a new human matrix metalloproteinase (MMP) was identified and cloned. This enzyme displayed the structural characteristics of a collagenase and was named collagenase-3, or MMP-13 according to MMP nomenclature. This review describes the research advances in the understanding of the function/production of the human MMP-13 at the tissular, cellular, biochemical, and molecular levels.

Abnormal insulin-like growth factor 1 signaling in human osteoarthritic subchondral bone osteoblasts.

Insulin-like growth factor (IGF)-1 is a key factor in bone homeostasis and could be involved in bone tissue sclerosis as observed in osteoarthritis (OA). Here, we compare the key signaling pathways triggered in response to IGF-1 stimulation between normal and OA osteoblasts (Obs). Primary Obs were prepared from the subchondral bone of tibial plateaus of OA patients undergoing knee replacement or from normal individuals at autopsy.

Association of polymorphisms in the peroxisome proliferator-activated receptor gamma gene and osteoarthritis of the knee.

Objectives: To study the association between two common polymorphisms in the peroxisome proliferator-activated receptor gamma (PPARgamma) gene and susceptibility to, and severity of, osteoarthritis in a French-Canadian population.

Methods: Genomic DNA was obtained from 172 patients with osteoarthritis and 210 ethnically matched healthy controls. Genotyping for the polymorphisms in the PPARgamma gene (Pro12Ala and C1431T) was carried out using polymerase chain reaction-restriction fragment length polymorphism.

Identification in human osteoarthritic chondrocytes of proteins binding to the novel regulatory site AGRE in the human matrix metalloprotease 13 proximal promoter.

Objective: Matrix metalloprotease 13 (MMP-13) plays a major role in osteoarthritic (OA) processes. We previously identified the AG-rich element (AGRE) regulatory site (GAAAAGAAAAAG) in the proximal promoter of this gene. Electrophoretic mobility shift assays (EMSAs) done with nuclear extracts from OA chondrocytes showed the presence of 2 AGRE protein-binding complexes, the formation of which depended on the pathophysiologic state (high or low) of the cells; the low OA (L-OA) chondrocytes have low MMP-13 basal levels and high interleukin-1beta (IL-1beta) inducibility, and the high OA (H-OA) chondrocytes have high MMP-13 basal levels and low IL-1beta inducibility.

Licofelone reduces progression of structural changes in a canine model of osteoarthritis under curative conditions: effect on protease expression and activity.

Objective: We investigated the effectiveness of licofelone, a combined 5-lipoxygenase and cyclooxygenase inhibitor, on structural changes in the anterior cruciate ligament (ACL) experimental dog model of osteoarthritis (OA) under therapeutic conditions. The effect of drug treatment on the expression and activity of metalloproteases in the OA cartilage was also studied.

Methods: The cranial cruciate ligament of the right stifle joint was surgically sectioned in 14 dogs to create OA lesions.

Most recent developments in strategies to reduce the progression of structural changes in osteoarthritis: today and tomorrow.

Osteoarthritis (OA), the most common of all arthritic conditions, is a social and financial burden to all nations. The most recent research has significantly advanced our understanding of the cause of OA and risk factors associated with it. These findings have provided useful information that has helped in the daily management of patients with OA.

New thoughts on the pathophysiology of osteoarthritis: one more step toward new therapeutic targets.

Osteoarthritis is considered an illness in which a complex interaction between the tissues of the joint plays a significant role in the initiation and/or progression of this pathophysiology. We do not yet completely understand all the factors that are responsible for initiating the degradation and loss of the articular tissues. This paper summarizes the novelties of three such mechanisms.

Degradation of small leucine-rich repeat proteoglycans by matrix metalloprotease-13: identification of a new biglycan cleavage site.

A major and early feature of cartilage degeneration is proteoglycan breakdown. Matrix metalloprotease (MMP)-13 plays an important role in cartilage degradation in osteoarthritis (OA). This MMP, in addition to initiating collagen fibre cleavage, acts on several proteoglycans.

Long term evaluation of disease progression through the quantitative magnetic resonance imaging of symptomatic knee osteoarthritis patients: correlation with clinical symptoms and radiographic changes.

The objective of this study was to further explore the cartilage volume changes in knee osteoarthritis (OA) over time using quantitative magnetic resonance imaging (qMRI). These were correlated with demographic, clinical, and radiological data to better identify the disease risk features. We selected 107 patients from a large trial (n = 1,232) evaluating the effect of a bisphosphonate on OA knees.

Differential regulation of the bone morphogenic protein antagonist chordin in human normal and osteoarthritic chondrocytes.

Objective: To investigate the distribution of the bone morphogenic protein (BMP) antagonist chordin in normal and osteoarthritic cartilage and synovial membranes, and its regulation in chondrocytes and synovial fibroblasts by inflammatory and growth factors.

Methods: Localisation of chordin in tissues was undertaken by immunohistochemistry and gene regulation was determined by real time polymerase chain reaction.

Results: In normal cartilage, chordin was found at low levels (mean (SD), 7.

Modulation of insulin-like growth factor 1 levels in human osteoarthritic subchondral bone osteoblasts.

Human osteoarthritis (OA) is characterized by cartilage loss, bone sclerosis, osteophyte formation and inflammation of the synovial membrane. We previously reported that OA osteoblasts (Ob) show abnormal phenotypic characteristics possibly responsible for bone sclerosis and that two subgroups of OA patients can be identified by low or high endogenous production of prostaglandin E2 (PGE2) by OA Ob. Here, we determined that the elevated PGE2 levels in the high OA subgroup were linked with enhanced cyclooxygenase-2 (COX-2) protein levels compared to normal and low OA Ob.

PD-0200347, an alpha2delta ligand of the voltage gated calcium channel, inhibits in vivo activation of the Erk1/2 pathway in osteoarthritic chondrocytes: a PKCalpha dependent effect.

Objective: To explore the in vivo effects of PD-0200347, an alpha(2)delta ligand of voltage gated Ca(2+) channels, on cell signalling in osteoarthritic (OA) chondrocytes from an experimental dog model, and examine the effect of PD-0200347 on the major signalling pathways involved in OA cartilage degradation.

Methods: OA was surgically induced in dogs by sectioning the anterior cruciate ligament. OA dogs were divided into three groups and treated orally with (a) placebo; (b) 15 mg/kg/day PD-0200347, or (c) 90 mg/kg/day PD-0200347.

The protective effect of licofelone on experimental osteoarthritis is correlated with the downregulation of gene expression and protein synthesis of several major cartilage catabolic factors: MMP-13, cathepsin K and aggrecanases.

This study sought to evaluate the levels of mRNA expression and protein synthesis of MMP-13, cathepsin K, aggrecanase-1 (ADAMTS-4), aggrecanase-2 (ADAMTS-5) and 5-lipoxygenase (5-LOX) in cartilage in the experimental anterior cruciate ligament (ACL) dog model of osteoarthritis (OA), and to examine the effects of treatment with licofelone, a 5-lipoxygenase (LOX)/cyclooxygenase (COX) inhibitor, on the levels of these catabolic factors. Sectioning of the ACL of the right knee was performed in three experimental groups: group 1 received no active treatment (placebo group); and groups 2 and 3 received therapeutic concentrations of licofelone (2.5 or 5.

Expression and regulation of microsomal prostaglandin E synthase-1 in human osteoarthritic cartilage and chondrocytes.

Objective: Elevated production of prostaglandin E2 (PGE2) plays an important role in the pathogenesis of arthritis. Recently, an inducible microsomal prostaglandin E synthase-1 (mPGES-1) was identified. This enzyme is functionally coupled with cyclooxygenase-2 (COX-2) and converts the COX product PGH2 to PGE2.

Leukotriene and prostaglandin synthesis pathways in osteoarthritic synovial membranes: regulating factors for interleukin 1beta synthesis.

Objective: To study the mechanisms responsible for the cross-talk between lipoxygenase (LOX) and cyclooxygenase (COX) pathways in human osteoarthritic (OA) synovial explants, and to confirm the arachidonic acid (AA) shunting phenomenon and its influence on interleukin 1beta (IL-1beta) synthesis.

Methods: Synovial membrane explants were cultured in the absence or presence of different drugs that inhibit COX and/or LOX activities. Concentrations of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), lipoxin A4 (LXA4), and IL-1beta were measured.

Subchondral and trabecular bone metabolism regulation in canine experimental knee osteoarthritis.

Objective: To determine trabecular and subchondral bone metabolic changes in experimental canine osteoarthritis (OA).

Methods: OA was induced in 19 dogs by transection of the anterior cruciate ligament (ACL) of the right knee through a stab wound. Dogs were sacrificed at 8 (n=7) and 12 weeks (n=12) after surgery.

Endothelin-1 in osteoarthritic chondrocytes triggers nitric oxide production and upregulates collagenase production.

The mechanism of endothelin-1 (ET-1)-induced nitric oxide (NO) production, MMP-1 production and MMP-13 production was investigated in human osteoarthritis chondrocytes. The cells were isolated from human articular cartilage obtained at surgery and were cultured in the absence or presence of ET-1 with or without inhibitors of protein kinase or LY83583 (an inhibitor of soluble guanylate cyclase and of cGMP). MMP-1, MMP-13 and NO levels were then measured by ELISA and Griess reaction, respectively.

Superiority of the gastroduodenal safety profile of licofelone over rofecoxib, a COX-2 selective inhibitor, in dogs.

This study assessed the gastroduodenal safety profile of licofelone, a new nonsteroidal anti-inflammatory drug with dual inhibitory activity against 5-lipoxygenase and cyclo-oxygenase (COX), by using endoscopic evaluations and by comparing licofelone to rofecoxib, a selective COX-2 inhibitor. Twenty-one dogs underwent blinded gastroduodenoscopies, during which the mucosa of the gastroduodenal tract was assessed and scored. Blood analyses were monitored on days 0 (baseline), 14, 28, 42, and 56.

Oral treatment with PD-0200347, an alpha2delta ligand, reduces the development of experimental osteoarthritis by inhibiting metalloproteinases and inducible nitric oxide synthase gene expression and synthesis in cartilage chondrocytes.

Objective: To examine the in vivo effects of PD-0200347, an alpha(2)delta ligand of voltage-activated Ca(2+) channels and a compound chemically related to pregabalin and gabapentin, on the development of cartilage structural changes in an experimental dog model of osteoarthritis (OA). The effects of PD-0200347 on the major pathways involved in OA cartilage degradation, including matrix metalloproteinases (MMPs) and the inducible form of nitric oxide synthase (iNOS), were also studied.

Methods: OA was surgically induced in dogs by sectioning the anterior cruciate ligament.

Pioglitazone, a peroxisome proliferator-activated receptor gamma agonist, reduces the progression of experimental osteoarthritis in guinea pigs.

Objective: To evaluate the in vivo therapeutic effect of pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, on the development of lesions in a guinea pig model of osteoarthritis (OA), and to determine the influence of pioglitazone on the synthesis of matrix metalloproteinase 13 (MMP-13) and interleukin-1beta (IL-1beta) in articular cartilage.

Methods: The OA model was created by partial medial meniscectomy of the right knee joint. The guinea pigs were divided into 4 treatment groups: unoperated animals that received no treatment (normal), operated animals (OA guinea pigs) that received placebo, OA guinea pigs that received oral pioglitazone at 2 mg/kg/day, and OA guinea pigs that received oral pioglitazone at 20 mg/kg/day.