Faculty Bibliography

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.

PURPOSE: To determine how subchondral bone microarchitecture is altered in patients with mild knee osteoarthritis. MATERIALS AND METHODS: This study had Institutional Review Board approval. We recruited 24 subjects with mild radiographic knee osteoarthritis and 16 healthy controls. The distal femur was scanned at 7T using a high-resolution 3D FLASH sequence. We applied digital topological analysis to assess bone volume fraction, markers of trabecular number (skeleton density), trabecular network osteoclastic resorption (erosion index), plate-like structure (surface), rod-like structure (curve), and plate-to-rod ratio (surface-curve ratio). We used two-tailed t-tests to compare differences between osteoarthritis subjects and controls. RESULTS: 7T magnetic resonance imaging (MRI) detected deterioration in subchondral bone microarchitecture in both medial and lateral femoral condyles in osteoarthritis subjects as compared with controls. This was manifested by lower bone volume fraction (-1.03% to -5.43%, P < 0.04), higher erosion index (+8.49 to +22.76%, P < 0.04), lower surface number (-2.31% to -9.63%, P < 0.007), higher curve number (+6.85% to +16.93%, P < 0.03), and lower plate-to-rod ratio (-7.92% to -21.71%, P < 0.05). CONCLUSION: The results provide further support for the concept that poor subchondral bone quality is associated with osteoarthritis and may serve as a potential therapeutic target for osteoarthritis interventions.J. Magn. Reson. Imaging 2014. (c) 2014 Wiley Periodicals, Inc.

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

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)

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.

OBJECTIVE: To characterize the diversity and taxonomic relative abundance of the gut microbiota in patients with never-treated, recent-onset psoriatic arthritis (PsA). METHODS: High-throughput 16S ribosomal RNA pyrosequencing was utilized to compare the community composition of gut microbiota in patients with PsA (n = 16), patients with psoriasis of the skin (n = 15), and healthy, matched control subjects (n = 17). Samples were further assessed for the presence and levels of fecal and serum secretory IgA (sIgA), proinflammatory proteins, and fatty acids. RESULTS: The gut microbiota observed in patients with PsA and patients with skin psoriasis was less diverse when compared to that in healthy controls. This could be attributed to the reduced presence of several taxa. Samples from both patient groups showed a relative decrease in abundance of Coprococcus species, while samples from PsA patients were also characterized by a significant reduction in Akkermansia, Ruminococcus, and Pseudobutyrivibrio. Supernatants of fecal samples from PsA patients revealed an increase in sIgA levels and decrease in RANKL levels. Analysis of fatty acids revealed low fecal quantities of hexanoate and heptanoate in both patients with PsA and patients with psoriasis. CONCLUSION: Patients with PsA and patients with skin psoriasis had a lower relative abundance of multiple intestinal bacteria. Although some genera were concomitantly decreased in both conditions, PsA samples had a lower abundance of reportedly beneficial taxa. This gut microbiota profile in PsA was similar to that previously described in patients with inflammatory bowel disease and was associated with changes in specific inflammatory proteins unique to this group, and distinct from that in patients with skin psoriasis and healthy controls. Thus, the role of the gut microbiome in the continuum of psoriasis-PsA pathogenesis and the associated immune response merits further study.