Faculty Bibliography

Osteoarthritis (OA) is often a progressive and disabling disease, which occurs in the setting of a variety of risk factors--such as advancing age, obesity and trauma--that collude to incite a cascade of pathophysiological events within joint tissues. An important emerging theme in OA is a broadening of focus from a disease of cartilage to one of the 'whole joint.' The synovium, bone and cartilage are each involved in pathological processes that lead to progressive joint degeneration. Additional themes that have emerged over the past decade are novel mechanisms of cartilage degradation and repair, the relationship between biomechanics and biochemical pathways, the importance of inflammation and the role of genetics. In this article, we review the molecular, clinical and imaging evidence that synovitis is not an 'incidental finding of OA', but plays a significant role in disease pathogenesis, and could therefore represent a target for future treatments

Purpose: Stem cell-based therapies aimed at introducing progenitor cells into cartilage lesions hold great promise for the restoration of damaged articular surfaces following joint injury or osteoarthritis. Key to the generation of a functional repair tissue is the controlled differentiation into the desired phenotype. To this end microRNAs (miRNAs) may be important molecules that regulate this process. By acting as transcriptional repressors, their modulation during differentiation may enable commitment to a specific lineage by suppressing the expression of other lineage markers. In this study we profiled MSCs for miRNA expression following induction into the chondrocyte (C), osteoblast (O) and smooth muscle (SM) lineages. Results: Human bone marrow-derived Mesenchymal Stem Cells (MSCs) were obtained from NIH, or from the discarded hips of patients undergoing joint replacement surgery. SM differentiation was induced by treating monolayer cultures with 1 mM thromboxane-A2 [DP1] in the presence of 0.25% serum. C differentiation was induced by seeding MSCs in aggregate cultures in the presence of dexamethasone and TGF-b1 (10 ng/ml). O differentiation was induced by treatment of monolayer cultures with dexamethasone, ascorbate and beta-glycerolphosphate. Profiling of miRNAs by microarray (Agilent) or QPCR (SA Biosciences) revealed differential regulation of miR-7 and miR-130b, among 376 probes. Following SM and C differentiation, miR-7 expression was down-regulated up to 6.9-fold and 3-fold respectively. Conversely, during O differentiation, its expression was induced approximately 7-fold. Analysis of theoretical mRNA targets using TargetScan online software (www.targetscan.org) identified conserved sites in several genes associated with chondrocyte and myoblast lineages. Putative chondrogenic targets were found to include COL2A1, IGFR1, and GDF5, while potential smooth muscle modulators included EGFR1, PIK3CD, IRS1/IRS2, KLF4, CNN3 and IGF1R. Following a similar trend to miR-7, miR-130b was down-regulated up to 3.2-fold and 3.1-fold in C and SM differentiation respectively, while O differentiation induced its expression 2-fold. TargetScan analysis identified putative chondrogenic targets, TGF-BRII, Sox5, BMP-2 and IGF1; Potential smooth muscle regulators included ESR1, TGF-BRII, MBLN1, TGFBR1 and IGF2BP1. Together these observations suggest that miR-7 and miR-130b act to negatively regulate myogenic and chondrogenic cell fates via regulation of lineage specific genes. Conclusion: Our findings suggest that miR-7 and miR-130b, via the targeting of lineage specific molecules, regulate cell fate in adult human MSCs by inhibiting smooth muscle and chondrocyte differentiation, thereby promoting 'default' differentiation into the osteoblast lineage. [DP1]0.25% FBS 24 hours prior to addition of 1.0mM of the TxA2 chemical analog U46619

Background: The role of nitric oxide (NO) in osteoarthritis (OA) is controversial. NO, particularly when metabolized to peroxynitrite, is a recognized mediator of inflammation, which induces catabolic effects and promotes chondrocyte apoptosis. Conversely, NO delivered at low concentrations by NO donors exerts anti-inflammatory effects. Cyclooxygenase-Inhibiting Nitric Oxide Donators (CINODs) are anti-inflammatory compounds designed to inhibit both COX-1 and COX-2 while releasing nitric oxide, an important modulator of vascular tone. We studied the effect of naproxen and the CINOD NCX 429 in human chondrocytes and cartilage tissues from OA patients, to understand whether NO donation from CINODs may modulate the inflammatory/metabolic response. Methods: The experiments were performed with human cartilage and chondrocytes isolated from OA cartilage. Isolated chondrocytes stimulated with IL-1beta to induce inflammation, followed by measurement of inflammatory and matrix parameters, such as iNOS, COX-2, MMP1 and 13, PGE2, NO, matrix metalloproteinases, collagen degradation and NF-B nuclear translocation. Reference NSAIDs naproxen and celecoxib were used in comparison to NCX 429 (10 and 50 muM), and incubated 16 h before IL-1beta challenge. Cartilage explants culture supernatants (untreated and treated with modulators) were harvested at 24 and 72 hours post-treatment. RNA was extracted from chondrocytes and estimated by qPCR. NF-B binding was assessed using Marligen Bioscience kit and both cytoplasm and nuclear p65 subunit of NF-B was also assessed by Western blot. Results: The reference NSAIDs and the CINOD similarly upregulated MMP1 but inhibited MMP13, showing comparable net effect on collagen degradation as assayed by CTX-II ELISA. They similarly inhibited ADAMTS4, but only 50 muM NCX 429 downregulated COX-2 expression. In isolated OA chondrocytes, NCX 429 (10 and 50 muM) significantly and completely inhibited IL-1beta-induced PGE2 production, and both the constitutive and IL-1beta-stimulated induction of NF-B activity. Western blot analysis of p65 subunit isolated from nuclear fraction showed that the cells treated with CINOD (both in unstimulated and IL-1beta stimulated cells) had increased p65 accumulation although decreased NF-B binding and also inhibited NF-B promoter mediated luciferase reporter assay. Conclusions: Reference NSAIDs and the CINOD NCX 429 appear to similarly modulate human OA chondrocytes, both in unstimulated and stimulated conditions. NO has been considered detrimental for chondrocytes; however, donation of low concentrations of NO is recognized to be beneficial in a variety of conditions. Here, the CINOD NCX 429 does not differ from reference NSAIDs, indicating that CINODs do not adversely affect chondrocytes via NO donation. In addition, NCX 429 showed inhibition of the NF-B signalling, therefore presenting interesting anti-inflammatory features to be further explored

Fewer United States rheumatologists perform or utilize musculoskeletal ultrasound (MSUS) than those in Europe, though this disparity is narrowing. To document perceptions and use of MSUS in the U.S. rheumatology community, we sent an anonymous electronic survey to American College of Rheumatology (ACR) physicians and tailored versions to fellows and program directors. A separately-conducted survey was sent to a smaller group of rheumatologists already utilizing MSUS. Acknowledging survey bias, we found that 20% of rheumatologists and fellows who responded are utilizing MSUS, and those using it primarily do so for diagnosis and injection guidance. Many rheumatologists across the country think that ultrasound should become a standard tool in rheumatology training, practice, and research. Despite an inherent survey bias likely overstating interest in MSUS, this study is valuable as the first to document this trend among U.S. rheumatologists

OBJECTIVE:To examine effects of the COX-2 inhibitor market withdrawals on NSAID utilization among patients at increased risk of gastrointestinal (GI) and cardiovascular (CV) toxicities. METHODS:A prospective cohort study was conducted using patients enrolled in the Consortium of Rheumatology Researchers of North America (CORRONA) Registry. The study population included rheumatoid arthritis (RA) and psoriatic arthritis (PsA) patients prescribed NSAIDs by rheumatologists from 1/1/2003 to 12/31/2005. Three cohorts were defined based on calendar year. The primary outcome assessed whether or not an NSAID gastroprotective strategy was prescribed. Secondary outcomes included rates of COX-2 inhibitor utilization and gastroprotective co-therapy utilization, stratified by the presence of cardiac and GI risk factors. RESULTS:NSAID gastroprotection utilization decreased from 65.1% in 2003 to 47.7% (p<0.001) in 2005. COX-2 inhibitor use decreased from 55.1% to 29.2% (p<0.001), whereas nonselective NSAIDs (nsNSAIDs) use increased from 50.2% to 73.9% (p=<0.01). Among patients with two or more risk factors for NSAID related GI bleeding, gastroprotection decreased from 74.4% in 2003 to 60.9% (p<0.01). For patients with two or more CV risk factors from 2003 to 2005, COX-2 inhibitor utilization decreased significantly, whereas nsNSAID utilization increased significantly.CONCLUSIONS:The COX-2 inhibitor withdrawals resulted in a rapid decline in NSAID gastroprotection prescribed by participating U.S. rheumatologists despite the availability of other gastroprotective options. Channeling toward nsNSAID use was widespread, including among patients at increased CV risk. Longer term follow-up is required to determine the clinical significance of these changes in NSAID prescribing, particularly for NSAID-related GI and CV-related toxicities

In osteoarthritis (OA) articular chondrocytes undergo phenotypic changes culminating in the progressive loss of cartilage from the joint surface. The molecular mechanisms underlying these changes are poorly understood. Here we report enhanced (approximately 7-fold) expression of F-spondin, a neuronal extracellular matrix glycoprotein, in human OA cartilage (P<0.005). OA-specific up-regulation of F-spondin was also demonstrated in rat knee cartilage following surgical menisectomy. F-spondin treatment of OA cartilage explants caused a 2-fold increase in levels of the active form of TGF-beta1 (P<0.01) and a 10-fold induction of PGE2 (P<0.005) in culture supernatants. PGE2 induction was found to be dependent on TGF-beta and the thrombospondin domain of the F-spondin molecule. F-spondin addition to cartilage explant cultures also caused a 4-fold increase in collagen degradation (P<0.05) and a modest reduction in proteoglycan synthesis (approximately 20%; P<0.05), which were both TGF-beta and PGE2 dependent. F-spondin treatment also led to increased secretion and activation of MMP-13 (P<0.05). Together these studies identify F-spondin as a novel protein in OA cartilage, where it may act in situ at lesional areas to activate latent TGF-beta and induce cartilage degradation via pathways that involve production of PGE2.