Faculty Bibliography

OBJECTIVE: Pro- and anti-inflammatory mediators, such as IL-1beta and IL1Ra, are produced by joint tissues in osteoarthritis (OA), where they may contribute to pathogenesis. We examined whether inflammatory events occurring within joints are reflected in plasma of patients with symptomatic knee osteoarthritis (SKOA). DESIGN: 111 SKOA subjects with medial disease completed a 24-month prospective study of clinical and radiographic progression, with clinical assessment and specimen collection at 6-month intervals. The plasma biochemical marker IL1Ra was assessed at baseline and 18 months; other plasma biochemical markers were assessed only at 18 months, including IL-1beta, TNFalpha, VEGF, IL-6, IL-6Ralpha, IL-17A, IL-17A/F, IL-17F, CRP, sTNF-RII, and MMP-2. RESULTS: In cross-sectional studies, WOMAC (total, pain, function) and plasma IL1Ra were modestly associated with radiographic severity after adjustment for age, gender and body mass index (BMI). In addition, elevation of plasma IL1Ra predicted joint space narrowing (JSN) at 24 months. BMI did associate with progression in some but not all analyses. Causal graph analysis indicated a positive association of IL1Ra with JSN; an interaction between IL1Ra and BMI suggested either that BMI influences IL1Ra or that a hidden confounder influences both BMI and IL1Ra. Other protein biomarkers examined in this study did not associate with radiographic progression or severity. CONCLUSIONS: Plasma levels of IL1Ra were modestly associated with the severity and progression of SKOA in a causal fashion, independent of other risk factors. The findings may be useful in the search for prognostic biomarkers and development of disease-modifying OA drugs.

Osteoarthritis (OA) is a highly prevalent, disabling joint disease with no existing therapies to slow or halt its progression. Cartilage degeneration hallmarks OA pathogenesis, and pannexin 3 (Panx3), a member of a novel family of channel proteins, is upregulated during this process. The function of Panx3 remains poorly understood, but we consistently observed a strong increase in Panx3 immunostaining in OA lesions in both mice and humans. Here, we developed and characterized the first global and conditional Panx3 knockout mice to investigate the role of Panx3 in OA. Interestingly, global Panx3 deletion produced no overt phenotype and had no obvious effect on early skeletal development. Mice lacking Panx3 specifically in the cartilage and global Panx3 knockout mice were markedly resistant to the development of OA following destabilization of medial meniscus surgery. These data indicate a specific catabolic role of Panx3 in articular cartilage and identify Panx3 as a potential therapeutic target for OA. Lastly, while Panx1 has been linked to over a dozen human pathologies, this is the first in vivo evidence for a role of Panx3 in disease. KEY MESSAGE: Panx3 is localized to cartilage lesions in mice and humans. Global Panx3 deletion does not result in any developmental abnormalities. Mice lacking Panx3 are resistant to the development of osteoarthritis. Panx3 is a novel therapeutic target for the treatment of osteoarthritis.

OBJECTIVE: Inflammatory mediators, such as PGE2 and IL-1beta, are produced by osteoarthritic joint tissues, where they may contribute to disease pathogenesis. We examined whether inflammation, reflected in plasma and peripheral blood leukocytes (PBLs) reflected presence of osteoarthritis (OA), progression or symptoms in patients with symptomatic knee osteoarthritis (SKOA). METHODS: SKOA patients were enrolled in a 24-month prospective study of radiographic progression. Standardized knee radiographs were obtained at baseline and 24 months. Biomarkers assessed at baseline included plasma lipids PGE2 and 15-HETE, and transcriptome analysis of PBLs by microarray and qPCR. RESULTS: Baseline PGE synthases (PGES) by PBL microarray gene expression, and plasma PGE2 distinguished SKOA patients from non-OA controls (AUCs 0.87 and 0.89 respectively, p<0.0001). Baseline plasma 15-HETE was significantly elevated in SKOA versus non-OA controls (p<0.019). In the 146 patients who completed the 24-month study, elevated baseline expression of IL-1beta, TNFalpha and COX-2 mRNA in PBLs predicted higher risk for radiographic progression by joint space narrowing (JSN). In a multivariate model, AUC point estimates of models containing COX-2 in combination with demographic traits overlap the confidence interval of the base model in two out of the three JSN outcome measures (JSN >0.0mm, >0.2mm and >0.5mm, AUC=0.62-0.67). CONCLUSION: Inflammatory plasma lipid biomarkers PGE2 and 15-HETE identify patients with SKOA. PBL inflammatory transcriptome identifies a subset of SKOA patients at higher risk for radiographic progression. These findings may reflect low-grade inflammation in OA and may be useful as diagnostic and prognostic biomarkers in clinical development of disease-modifying OA drugs

Purpose: We and others have demonstrated low grade inflammation exists in OA joint tissues, where it may contribute to disease pathogenesis. In the current studies we assessed whether inflammatory events occurring within joint tissues were reported in the peripheral blood leukocytes (PBLs) of patients with symptomatic knee OA (SKOA). Methods: PBL inflammatory gene expression (IL-1, TNFalpha, COX-2) was assessed in two independent cohorts of patients with SKOA, and a cohort of healthy control subjects: 1) 111 patients with tibiofemoral medial OA and 21 healthy volunteers from the NYUHJD Cohort, and 2) 200 patients from the OAI progression cohort who had "high quality radiographs", at both baseline and 24 months, and had KL2 or 3 in the signal knee at baseline. Radiographic progression was defined as narrowing of medial joint space width (JSW) in the signal knee between baseline and 24-months in each cohort. Radiographic progressors were defined as subjects who had JSN >0.0, 0.2 and 0.5mm over 24 months. For measuring predictive performance, we used the area under the curve (AUC) of a receiver operating characteristics (ROC). OAI SKOA subjects were dichotomized as radiographic non-progressors (JSN <0.0 mm) and progressors (JSN>0.0mm) for association studies. Results: Elevated PBL expression of IL-1, TNFalpha or COX-2 identified SKOA patients who were "fast progressors" (mean JSN 0= 0.71, 0.75 and 0.71 mm / 24 months, respectively) compared to patients with levels below the median. In a multivariable model, anthropometric traits alone (BMI, gender, age) did not predict progression, whereas addition of PBL gene expressions improved prediction of fast progressors (JSN>0.5mm). We next examined inflammatory gene expression in PBLs of radiographic progressors in the OAI cohort. Similar to the NYUHJD cohort, elevated expression of IL-1beta, TNFalpha and COX-2 mRNA distinguished radiographic progressors from non-progressors (Table 1). PBL IL-1beta expression found to be strongest predictor of all three radiographic progressors. In multivariate models that combine all three markers did not improve upon IL-1beta predictivity. We thus conclude that either the signal in TNFalpha and Cox-2 is already subsumed by IL-1beta and/or that it is not easy to capture the non-overlapping signals without increasing the sample size (i.e., fitting a stronger multivariate predictor will require more sample size). Conclusions: We identified, and confirmed in two cohorts, increased inflammatory gene expression (IL-1, TNFalpha or COX-2) by PBLs that predict radiographic progression in patients with SKOA. The data indicate that inflammatory events within joint tissues of patients with SKOA are reported in the peripheral blood. These PBL transcriptome signals of local joint inflammation merit further study as potential biomarkers for OA disease progression. (Table Presented)

Purpose: Obesity is a modifiable risk factor of knee osteoarthritis (KOA). While diet, exercise and other conservative treatments can have limited and often transient beneficial effects, an alternative strategy would target weight loss via surgery to delay or avoid joint replacement. Some retrospective data, including a study from our group, have in fact shown sustained improvement in KOA pain after bariatric surgery. We initiated a prospective study to evaluate painful KOA in the obese population, and track whether weight loss after bariatric surgery affects KOA-related pain and physical function. Methods: We screened consecutive patients prior to laparoscopic adjustable gastric banding (LAGB), sleeve gastrectomy, or gastric bypass (RYGB), at NYU Langone Medical Center and Bellevue Hospital Center. Patients age >21 with knee pain for >1 month and a visual analog scale pain score >30mm were enrolled, excluding those with lupus, rheumatoid arthritis, psoriatic arthritis, or psoriasis. Baseline pre-op assessments included x-rays for OA severity by Kellgren-Lawrence (KL) grade, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Western Ontario McMasters Universities Osteoarthritis Index (WOMAC) with a Likert scale calculated from the KOOS. Patients were consented for optional tissue collection (blood, urine and intra-operative adipose samples) for future biomarker analysis. They are (still) completing the questionnaires and being measured for BMI and % excess weight loss (%EWL) at 1,3,6 and 12 month post-op intervals. Results: In total, we screened 537 patients planning to have bariatric surgery, found that 309 (58%) of them reported knee pain - and enrolled 176who met criteria and consented for the study. Our cohort is 89.7% female, with a mean BMI of 43.6 kg/m2+/-7 (31.6-60.6), a mean age of 42.4 +/-11 (18-73), and radiographic severity as follows: KL0=43 (25%), KL1=34 (19%), KL2=38 (22%), KL3=34 (19%), KL4=27 (15%). The mean pre-op KOOS scores were 45.4 for pain and 46.0 for ADL (0=worst, 100=best), the mean pre-op WOMAC pain score (Likert scale) was 11 (0=best, 20=worst), and the mean overall WOMAC index was 52 (0=best, 96=worst). Before surgery, a higher KL correlated with symptoms; mean KOOS pain was 53.2, 48.1 and 36.7 for KL0, KL1-2, and KL3-4 (p=0.00002 for KL0 vs KL3-4, and p=0.0005 for KL1-2 vs KL3-4), with similar trends across other KOOS and WOMAC scores. Higher BMI also trended with worse pre-op knee symptoms, as the tertiles with the lowest and highest BMIs (31-39 and 46-61) had mean KOOS pain scores of 46.8 and 43.7 (p=0.37). While 23 ultimately decided against weight loss surgery, we are collecting post-operative data on the 153 patients (40 RYGB=26%, 93 sleeve=61%, 20 LAGB=13%). Improvement in average KOOS and WOMAC scores over baseline has been observed at all intervals (67, 71, 65, and 42 responses at 1,3,6,12 month visits), with more improvement farther after surgery. At 6 months post-op, mean KOOS scores available thus far improved 29 points for pain, with mean WOMAC pain and index improving by 6 and 22 points. The %EWL correlated with knee symptoms at each interval and for all followups combined, as the smallest and largest %EWL quartiles (4-29%, 54-92%) showed mean improvements of 18 and 31 points (p=0.03) in KOOS pain - mirrored across KOOS and WOMAC scores. RYGB and sleeve yielded higher %EWL than LAGB (44%, 43% vs. 37%) across all intervals, and greater improvement in mean KOOS and WOMAC scores (e.g. mean KOOS pain increased by 28, 29 and 8). Neither presence nor severity of KOA severity affected knee pain improvement from weight loss. Conclusions: These data suggest that bariatric surgery improves patients' KOA pain proportional to percent excess weight loss, with durability over time. RYGB and sleeve gastrectomy have more impact on knee symptoms than LAGB. While patients with worse KL grades report more baseline pain and disability, as expected, x-ray severity did not impact the response to surgical weight loss

We investigated the role of periostin, an extracellular matrix protein, in the pathophysiology of osteoarthritis (OA). In OA, dysregulated gene expression and phenotypic changes in articular chondrocytes culminate in progressive loss of cartilage from the joint surface. The molecular mechanisms underlying this process are poorly understood. We examined periostin expression by immunohistochemical analysis of lesional and nonlesional cartilage from human and rodent OA knee cartilage. In addition, we used small interfering (si)RNA and adenovirus transduction of chondrocytes to knock down and up-regulate periostin levels, respectively, and analyzed its effect on matrix metalloproteinase (MMP)-13, a disintegrin and MMP with thrombospondin motifs (ADAMTS)-4, and type II collagen expression. We found high periostin levels in human and rodent OA cartilage. Periostin increased MMP-13 expression dose [1-10 microg/ml (EC50 0.5-1 mug/ml)] and time (24-72 h) dependently, significantly enhanced expression of ADAMTS4 mRNA, and promoted cartilage degeneration through collagen and proteoglycan degradation. Periostin induction of MMP-13 expression was inhibited by CCT031374 hydrobromide, an inhibitor of the canonical Wnt/beta-catenin signaling pathway. In addition, siRNA-mediated knockdown of endogenous periostin blocked constitutive MMP-13 expression. These findings implicate periostin as a catabolic protein that promotes cartilage degeneration in OA by up-regulating MMP-13 through canonical Wnt signaling.-Attur, M., Yang, Q., Shimada, K., Tachida, Y., Nagase, H., Mignatti, P., Statman, L., Palmer, G., Thorsten, K., Beier, F., Abramson, A. B. Elevated expression of periostin in human osteoarthritic cartilage and its potential role in matrix degradation via matrix metalloproteinase-13.

The aims of this study are to compare plasma levels of IL17A, A/F, and F biomarkers in RA patients versus controls, and to determine responsiveness to methotrexate (MTX), anti-TNFs, and abatacept. We selected plasma samples from RA cohorts consisting of a cross-sectional RA cohort (N = 78) not receiving DMARDs at the time of sampling, as well as from longitudinal drug start cohorts (N = 71 patients) with pre/post samples including anti-TNF, abatacept, and MTX-treated patients. We assayed IL-17A, IL-17F, and IL17-A/F using a highly sensitive immunoassay system. Plasma levels of IL-17A, IL-17A/F, and IL-17F were all significantly increased in RA versus controls. The difference was largest in IL-17F, with median IL-17F levels in RA patients being approximately 18-fold higher than controls (81 pg/mL in RA vs. 4.4 pg/mL in controls, p < 0.001). Among the forms of IL-17, only IL-17F was decreased after therapy in the MTX cohort (p = 0.006), abatacept cohort (p < 0.001), and anti-TNF cohorts (p = 0.02), whereas IL-17A and IL-17A/F were not significantly decreased for any of the three drug cohorts. Synovial fluid analysis demonstrated higher IL-17F levels in RA (p = 0.016) than healthy controls. These results suggest a specific role for IL-17F in human RA pathogenesis and as a therapeutic target.