Faculty Bibliography

OBJECTIVE: To determine if inhibition of inducible nitric oxide synthase (iNOS) with cindunistat hydrochloride maleate slows progression of osteoarthritis (OA) METHODS: This 2-year, multinational, double-blind, placebo-controlled trial enrolled patients with symptomatic knee OA (Kellgren and Lawrence Grade (KLG) 2 or 3). Standard OA therapies were permitted throughout. Patients were randomly assigned to cindunistat (50 or 200 mg/day) or placebo. Randomisation was stratified by KLG. Radiographs to assess joint space narrowing (JSN) were acquired using the modified Lyon-schuss protocol at baseline, week 48 and 96. RESULTS: Of 1457 patients (50 mg/day, n=485; 200 mg/day, n=486; placebo, n=486), 1048 (71.9%) completed the study. Patients were predominantly women; 56% had KLG3. The primary analysis did not demonstrate superiority of cindunistat versus placebo for rate of change in JSN. In KLG2 patients, JSN after 48 weeks was lower with cindunistat 50 mg/day versus placebo (p=0.032). Least-squares mean+/-SE JSN with cindunistat 50 mg/day ( -0.048+/-0.028 mm) and 200 mg/day (-0.062+/-0.028 mm) were 59.9% (95% CI 6.8% to 106.9%) and 48.7% (95% CI -8.4% to 93.9%) of placebo, improvement was not maintained at 96 weeks. No improvement was observed for KLG3 patients at either time-point. Cindunistat did not improve joint pain or function, but was generally well tolerated. CONCLUSIONS: Cindunistat (50 or 200 mg/day) did not slow the rate of JSN versus placebo. After 48-weeks, KLG2 patients showed less JSN; however, the improvement was not sustained at 96-weeks. iNOS inhibition did not slow OA progression in KLG3 patients. CLINICAL TRIAL LISTING: NCT00565812.

PURPOSE OF REVIEW: Identification of patients at risk for incident disease or disease progression in osteoarthritis remains challenging, as radiography is an insensitive reflection of molecular changes that presage cartilage and bone abnormalities. Thus there is a widely appreciated need for biochemical and imaging biomarkers. We describe recent developments with such biomarkers to identify osteoarthritis patients who are at risk for disease progression. RECENT FINDINGS: The biochemical markers currently under evaluation include anabolic, catabolic, and inflammatory molecules representing diverse biological pathways. A few promising cartilage and bone degradation and synthesis biomarkers are in various stages of development, awaiting further validation in larger populations. A number of studies have shown elevated expression levels of inflammatory biomarkers, both locally (synovial fluid) and systemically (serum and plasma). These chemical biomarkers are under evaluation in combination with imaging biomarkers to predict early onset and the burden of disease. SUMMARY: Prognostic biomarkers may be used in clinical knee osteoarthritis to identify subgroups in whom the disease progresses at different rates. This could facilitate our understanding of the pathogenesis and allow us to differentiate phenotypes within a heterogeneous knee osteoarthritis population. Ultimately, such findings may help facilitate the development of disease-modifying osteoarthritis drugs (DMOADs).

BACKGROUND: The purpose was to determine the relationship between the cartilage volumes in different regions of the femur and tibia, and the lengths of contacts between the meniscus and cartilage. The rationale was that less meniscal contact would make the cartilage more susceptible to loss of volume due to degeneration and wear. METHODS: Fifty MRI scans of osteoarthritic knees at varying degrees of severity were obtained. Computer models of the cartilage layers of the distal femur and proximal tibia were generated, from which cartilage volumes and thicknesses were calculated for different regions. The lengths of meniscal contact and heights were measured in frontal and sagittal views. RESULTS: Cartilage loss progressed initially on the central and inner regions of the distal femur, and on the tibia in the region uncovered by the meniscus. As the cartilage volume decreased further, the wear spread medially, and to a lesser extent anteriorly and posteriorly. There were inverse relations between the loss of volume on both the femur and tibia, and the meniscal contacts and heights. CONCLUSIONS: Cartilage loss initially occurred where there was direct contact between the cartilage of the femur and tibia. The meniscus did not prevent this, nor prevent the spread of the wear medially. This may have been due to the progressive reduction of cartilage-meniscal contact as the meniscus subluxed or lost substance, as the cartilage loss and deformity progressed. This suggested that the meniscus was not able to ameliorate the forces and pressures on the cartilage surfaces to prevent degeneration.

OBJECTIVE.: To profile the subgingival oral microbiota abundance and diversity in never-treated, new-onset rheumatoid arthritis (NORA) patients. METHODS.: Periodontal disease (PD) status, clinical activity and sociodemographic factors were determined in patients with NORA, chronic RA (CRA) and healthy subjects. Massively parallel pyrosequencing was used to compare the composition of subgingival microbiota and establish correlations between presence/abundance of bacteria and disease phenotypes. Anti-P. gingivalis antibodies were tested to assess prior exposure. RESULTS.: The more advanced forms of periodontitis are already present at disease onset in NORA patients. The subgingival microbiota of NORA is distinct from controls. In most cases, however, these differences can be attributed to PD severity and are not inherent to RA. The presence and abundance of P. gingivalis is directly associated with PD severity as well, is not unique to RA, and does not correlate with anti-citrullinated peptide antibody (ACPA) titers. Overall exposure to P. gingivalis is similar in RA and controls, observed in 78.4% and 83.3%, respectively. Anaeroglobus geminatus correlated with ACPA/RF presence. Prevotella and Leptotrichia species are the only characteristic taxa in the NORA group irrespective of PD status. CONCLUSIONS.: NORA patients exhibit a high prevalence of PD at disease onset, despite their young age and paucity of smoking history. The subgingival microbiota of NORA patients is similar to CRA and healthy subjects of comparable PD severity. Although colonization with P. gingivalis correlates with PD severity, overall exposure is similar among groups. The role of A. geminatus and Prevotella/Leptotrichia species in this process merits further study.

Objective: Non-steroidal anti-inflammatory drugs (NSAIDs) that are prescribed for treatment of osteoarthritis (OA) symptoms including pain and inflammation target the production eicosanoids which exhibit numerous functions in various cell types. In these studies, we have (a) identified the diverse eicosanoid pathways that are activated in human chondrocytes of normal and OA cartilage, (b) delineated the modulation of eicosanoids in the presence of NSAIDS and selective COX-2 inhibitors, and (c) characterized eicosanoid products and various transcripts modulated by various inhibitors of eicosanoids in human OA cartilage by gene expression arrays. Methods: Immunoassay analysis of culture supernatants were utilized to determine the spectrum of eicosanoids derived from both the cyclooxygenase (COX) and lipoxygenase (LOX) pathways of normal and human OA cartilage in ex-vivo conditions. Human OA cartilage was incubated in ex-vivo conditions to examine spontaneous or IL-1 induced production of eicosanoids in the presence of various COX inhibitors. Gene expression analysis was performed to analyze the expression of mRNA in the presence and absence of COX-2 inhibitors in OA cartilage in ex-vivo conditions. Results: Normal and OA human cartilage explants produced multiple eicosanoids of the COX and LOX pathways. PGF1alpha, PGF2alpha, PGE2 > TXB2, PGD2, and LTB4 were spontaneously generated by normal and OA cartilage. Among these, elevated levels of PGE2 and LTB4 were generated in OA as compared to normal cartilage. IL-1 treatment further enhanced these eicosanoids production. Treatment of OA cartilage explants with cyclooxygenase inhibitors (celecoxib & indomethacin) augmented LTB4 accumulation by 2- to 4-fold. A follow-up pharmacogenomic analysis identified approximately 90 cytokine and growth factor related transcripts that were modulated following selective COX-2 inhibition. Conclusion: These studies for the first time demonstrate that normal and OA cartilage generates multiple and differential eicosanoid products. Inhibition of the COX- pathway in human OA cartilage caused accumulation of end products (LTB4) of the 5LO pathway. Furthermore, celecoxib, a selective COX-2 inhibitor, regulated numerous genes in cartilage, which are linked to the NFkB and AP-1 pathways at the mRNA level. In conclusion, these experiments demonstrate the complex and pleotropic role of eicosanoids in human cartilage homeostasis and pathophysiology of OA.

OBJECTIVE: To address the role of the nuclear receptor 4A (NR4A) family of orphan nuclear receptors in synoviocyte transformation, hyperplasia, and regulation of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in models of inflammatory arthritis. METHODS: NR4A messenger RNA levels in synovial tissue and primary synoviocytes were measured by quantitative reverse transcription-polymerase chain reaction (RT-PCR). NR4A2 was stably overexpressed in normal synoviocytes, and cell proliferation, survival, anchorage-independent growth, migration, and invasion were monitored in vitro. MMP and TIMP expression levels were analyzed by quantitative RT-PCR, and MMP-13 promoter activity was measured using reporter assays. Stable depletion of endogenous NR4A levels was achieved by lentiviral transduction of NR4A short hairpin RNA (shRNA), and the effects on proliferation, migration, and MMP-13 expression were analyzed. RESULTS: NR4A2 was expressed at elevated levels in normal, OA, and RA synovial tissue and in primary RA synoviocytes. Tumor necrosis factor alpha (TNFalpha) rapidly and selectively induced expression of NR4A2 in synoviocytes. Ectopic expression of NR4A2 in normal synoviocytes significantly increased proliferation and survival, promoted anchorage-independent growth, and induced migration and invasion. MMP-13 gene expression was synergistically induced by NR4A2 and TNFalpha, while expression of TIMP-2 was antagonized. NR4A2 directly transactivated the proximal MMP-13 promoter, and a point mutation in the DNA binding domain of NR4A2 abolished transcriptional activation. Depletion of endogenous NR4A receptors with shRNA reduced synoviocyte proliferation, migration, and MMP-13 expression. CONCLUSION: The orphan nuclear receptor NR4A2 is a downstream mediator of TNFalpha signaling in synovial tissue. NR4A2 transcriptional activity contributes to the hyperplastic and invasive phenotype of synoviocytes that leads to cartilage destruction, suggesting that this receptor may show promise as a therapeutic target in inflammatory arthritis.