Faculty Bibliography

Background/Purpose : Osteoarthritis (OA) is a highly heterogeneous disease, which suggest that multiple endotypes exist. Identification and characterization of such endotypes may assist in precision medicine for identification of faster progressors whom may benefit from a given type of intervention. Recent published data have shown that SNPs in growth factors such as TGFbeta and GDF are associated with OA, which indicate that cartilage formation and repair play an important role in progression of OA. The aim was to determine whether a biomarker of type II collagen formation measured in serum, as a potential surrogate measure of cartilage formation, could predict radiographic progression in knee OA population. Subsequently, we investigated if such a proposed low cartilage formation/repair endotype was more responsive to a potential treatment of OA. Methods : hsPRO-C2, a measurement of the type II collagen pro-peptide, was measured in blood samples of two independent knee OA cohorts: 106 recruited at New York University (NYU cohort) and 147 from the phase III OA trial SMC021-2301 (clinicaltrial.gov: NCT00486434) evaluating the efficacy and safety of oral salmon calcitonin. Patients were dichotomized based on their baseline level of hsPRO-C2 and the mean difference in two-year radiographic progression (joint space narrowing (JSN)) was analyzed using ANCOVA adjusting for baseline demographics and clinical characteristics. Results : In the NYU cohort, baseline plasma hsPRO-C2 levels were negatively correlated with the progression of radiographic JSN (r = -0.26, p = 0.009). Quartile analysis demonstrated a significant difference in mean JSN from quartile 1 to 4 (0.51 mm versus -0.07 mm, p = 0.036, fig. 1). Knee OA patients with low hsPRO-C2 levels (<= 1.48 ng/mL) revealed significantly larger JSN compared to the individuals with high hsPRO-C2 levels ( > 1.48 ng/ mL) at 24 months (0.37 mm vs 0.02 mm, p = 0.042). In the SMC cohort, there was no significant treatment effect on the medial JSN over 2 years before stratification by hsPRO-C2; however, as observed in the NYU cohort, JSN was on average higher in the low hsPRO-C2 (<= 1.96 ng/mL) group compared to the high group ( > 1.96 ng/ mL). Furthermore, in the low baseline hsPRO-C2 subgroup, sCT-treated patients on average had a lower JSN compared to placebo patients (p < 0.05, fig. 2). The opposite trend was observed in patients with high baseline hsPRO-C2. Conclusion : Here we show that low levels of cartilage formation, measured by PRO-C2, were associated with radiographic progression and greater likelihood of response to a salmon calcitonin. Low PRO-C2 may provide a measure of an OA endotype with low background cartilage formation (at baseline) and higher capacity for repair when treated with a potential cartilage anabolic drug

Background/Purpose : Early treatment initiation in rheumatoid arthritis (RA) is fundamental to avoid chronic joint destruction and disability. Despite remarkable advances in RA therapeutics, oral methotrexate (MTX) remains the anchor drug and mainstay of treatment worldwide. However, MTX bioavailability has a wide inter-individual variability and >50% of patients with moderate or severe RA show no or suboptimal improvement in their symptoms in response to MTX. The reasons for these disparities in treatment response remain unclear. Prior studies have shown that the biotransformation of MTX is altered in germ-free and microbiome-depleted mice, prompting us to hypothesize that inter-individual differences in the human gut microbiome could impact drug bioavailability and thus clinical efficacy. We sought to determine differences in the microbiome of drug-naive, new onset RA (NORA) patients that could predict response to MTX therapy. Methods : We enrolled 27 drug-naive, NORA patients priori to MTX initiation (test cohort), and classified them as either MTX-responders (MTX-R; 39% of the cohort) or non-responders (MTX-NR; 61%) based on a stringent definition of clinical response (delta improvement of DAS28 >1.8 by month 4). We performed 16S rRNA gene and Shotgun Metagenomic sequencing on the baseline gut microbiomes of these NORA patients and confirmed the results in an independent validation cohort (n=31). NMR and LC-MS were performed in ex vivo incubations to measure the capacity of each NORA microbiome to metabolize MTX. Results : Our analysis revealed significant associations between the abundance of gut bacterial taxa and future MTX response. Patients that responded to therapy had significantly lower microbial diversity (p< 0.05). A significant difference in overall gut microbial community structure was also observed between groups (Bray-Curtis distance; PERMANOVA < 0.05). At the class level, we observed statistically higher abundance of Clostridia and lower abundance of Bacteroidia in MTX-NR (p< 0.05; q< 0.2). Furthermore, the baseline metagenome separated most MTX-R from MTX-NR (PCoA; PERMANOVA p< 0.05). We identified 8 microbial modules and 23 pathways, whose abundance significantly differed between groups (p< 0.05, q< 0.2), including genes related with purine and MTX metabolism, indicating a major difference in metabolic and biosynthetic potential between the microbiome of MTX-R and MTX-NR patients. Machine learning techniques were applied to this metagenomic data, resulting in a robust model based on bacterial gene abundance that accurately predicted response to MTX in an independent cohort. Finally, MTX available levels remaining after ex vivo incubation with distal gut samples from pre-treatment RA patients significantly correlated with the magnitude of future clinical response, suggesting a direct effect of the gut microbiome on MTX bioavailability and response to therapy. Conclusion : Together, these results provide the first step towards predicting response to oral MTX in NORA patients and support the utility of the gut microbiome as a prognostic tool and perhaps even as a target for manipulation in the treatment of rheumatic and autoimmune disease

Background: There is a lack of objective diagnostic modalities that identify patients at risk for severe osteoarthritis (OA), which complicates the development of disease-modifying OA drugs. The biochemical marker, high-sensitive PRO-C2 (hsPRO-C2)¹, is a measure of the propeptide of type IIB collagen and a blood measure of cartilage formation.
Objective(s): The aim of this study was to determine whether hsPRO-C2 could predict radiographic progression in a knee OA population and stratify patients into high and low risk for joint destruction.
Method(s): Subjects with varying degrees of symptomatic knee OA (n=106) were included from a New York University (NYU) progression cohort. Radiographic progression was assessed by medial joint space narrowing (JSN), based on the change in joint space width (JSW), of the signal knee at baseline and at 24months. Baseline plasma type II collagen formation biomarker (hsPRO-C2) levels were measured. Association between baseline hsPRO-C2 and JSN was analyzed by Pearson's correlation, corrected for age, sex, BMI, race, baseline JSW, and non-steroids antiinflammatory drugs (NSAID) use. Subjects were divided into quartiles of equal size depending on the hsPRO-C2 levels, and the difference in JSN was investigated. The median level of baseline hsPRO-C2 (1.48 ng/ml) was used as a cut-off for stratifying all the subjects. The difference in JSN over 24 months was investigated in patients dichotomized based on median level. The values were compared with two-way analysis of covariates (ANCOVA).
Result(s): Baseline plasma hsPRO-C2 levels were negatively correlated with the progression of radiographic joint space narrowing over 24 months (r =-0.26, p = 0.009) after adjustment for confounders (Figure 1A). Quartile analysis demonstrated a decreasing trend of hsPRO-C2 in the radiographic progression from quartile 1 to 4 (Figure 1B). One-way ANOVA revealed a significant difference in mean JSN between quartiles 1 and 4 (0.5073 mm versus-0.0691 mm, p = 0.036, Figure 1B). JSN was significantly larger in the low hsPRO-C2 patients (0.3710 mm) com pared to the high hsPRO-C2 patients (0.0195 mm) (Figure 2).
Conclusion(s): These data suggest that symptomatic knee OA subjects with lower levels of hsPRO-C2 at baseline presented more radiographic medial JSN progression as compared to the subjects with higher levels of hsPRO-C2. The biomarker hsPRO-C2 may be useful for predicting OA progression

BACKGROUND:To investigate the expression of vascular adhesion protein-1 (VAP-1) in joint tissues and serum in symptomatic knee osteoarthritis (SKOA) patients and examine whether VAP-1 levels predict increased risk of disease severity in a cross-sectional study. METHODS:Baseline VAP-1 expression and soluble VAP-1 (sVAP-1) levels were assessed in the synovium synovial fluid and in the serum in cohorts of patients with tibiofemoral medial knee OA and healthy subjects. Standardized fixed-flexion poster anterior knee radiographs scored for Kellgren-Lawrence (KL) grade (0-4) and medial joint space width (JSW). KL1/2 vs. KL3/4 scores defined early and advanced radiographic severity, respectively. Biochemical markers assessed in serum or synovial fluids (SF) comprised sVAP-1, interleukin 1 receptor antagonist (IL-1Ra), interleukin 6 (IL-6), soluble receptor for advanced glycation end-products (sRAGE), C-C motif chemokine ligand 2 (CCL2), C-C motif chemokine ligand 4 (CCL4), cluster of differentiation 163 (CD163), high sensitivity C-reactive protein (hsCRP), and matrix metalloproteinases (MMPs)-1,-3,-9. Associations between biomarkers and radiographic severity KL1/2 vs. KL3/4 (logistic regression controlling for covariates) and pain (Spearman correlation) were evaluated. RESULTS:Elevated levels of sVAP-1 observed in OA synovial fluid and VAP-1 expression in synovium based on immunohistochemical, microarray, and real-time quantitative polymerase chain reaction (qRT-PCR) analyses. However, serum sVAP-1 levels in OA patients were lower than in controls and inversely correlated with pain and inflammation markers (hsCRP and soluble RAGE). Soluble VAP-1 levels in serum were also lower in radiographically advanced (KL3/4) compared with early KL1/2 knee SKOA patients. CONCLUSION/CONCLUSIONS:Local (synovial fluid) semicarbazide-sensitive amine oxidase (SSAO)/sVAP-1 levels were elevated in OA and correlated with radiographic severity. However, systemic (serum) sVAP-1 levels were lower in SKOA patients than normal and inversely correlated with pain and inflammation markers. Serum sVAP-1 levels were higher in early (KL1/2) compared with advanced (KL3/4) SKOA patients.

OBJECTIVE:To validate a radial imaging spin-echo diffusion tensor (RAISED) sequence for high-resolution diffusion tensor imaging (DTI) of articular cartilage at 3 T. METHODS:The RAISED sequence implementation is described, including the used non-linear motion correction algorithm. The robustness to eddy currents was tested on phantoms, and accuracy of measurement was assessed with measurements of temperature-dependent diffusion of free water. Motion correction was validated by comparing RAISED with single-shot diffusion-weighted echo-planar imaging (EPI) measures. DTI was acquired in asymptomatic subjects (n = 6) and subjects with doubtful (Kellgren-Lawrence [KL] grade 1, n = 9) and mild (KL = 2, n = 9) symptomatic knee osteoarthritis (OA). MD and FA values without correction, and after all corrections, were calculated. A test-retest evaluation of the DTI acquisition on three asymptomatic and three OA subjects was also performed. RESULTS:The root mean squared coefficient of variation of the global test-restest reproducibility was 3.54% for MD and 5.34% for FA. MD was significantly increased in both femoral condyles (7-9%) of KL 1 and in the medial (11-17%) and lateral (10-12%) compartments of KL 2 subjects. Averaged FA presented a trend of lower values with increasing KL grade, which was significant for the medial femoral condyle (-11%) of KL 1 and all three compartments in KL 2 subjects (-18 to -11%). Group differences in MD and FA were only significant after motion correction. CONCLUSION/CONCLUSIONS:The RAISED sequence with the proposed reconstruction framework provides reproducible assessment of DTI parameters in vivo at 3 T and potentially the early stages of the disease in large regions of interest. KEY POINTS/CONCLUSIONS:• DTI of articular cartilage is feasible at 3T with a multi-shot RAISED sequence with non-linear motion correction. • RAISED sequence allows estimation of the diffusion indices MD and FA with test-retest errors below 4% (MD) and 6% (FA). • RAISED-based measurement of DTI of articular cartilage with non-linear motion correction holds potential to differentiate healthy from OA subjects.

OBJECTIVE:Phenotypic changes of chondrocytes toward hypertrophy might be fundamental in the pathogenesis of OA, of which type X collagen (Col10) is a well-known marker. The purpose was to develop a specific immunoassay for blood quantification of a newly identified neo-epitope of type X collagen to assess its diagnostic value for radiographic knee osteoarthritis (OA). METHODS:A neo-epitope of Col10 was identified in urine samples from OA patients. A monoclonal antibody against the neo-epitope was produced in Balb/C mice. The enzyme responsible for the cleavage was identified. Immunohistochemical detection of this neo-epitope was performed on human OA cartilage. An immunoassay (Col10neo) was developed and quantified in two clinical studies: the C4Pain-003 and the NYU OA progression study. ROC curve analysis was carried out to evaluate the discriminative power of Col10neo between OA and RA. RESULTS:A neo-epitope specific mAb was produced. The Cathepsin K-generated neo-epitope was localized to the pericellular matrix of chondrocytes, while its presence was extended and more prominent in superficial fibrillation in the cartilage with advanced degradation. In the C4Pain study, a higher level of Col10neo was seen in subjects with greater KL grade. The group of the highest tertile of Col10neo included more subjects with KL3-4. In the NYU study, Col10neo was statistically higher in OA than control or RA. ROC curve analysis revealed area under the curve was 0.88 (95% CI 0.81-0.94). CONCLUSION/CONCLUSIONS:Our findings indicate that Col10neo linked to hypertrophic chondrocytes could be used as a diagnostic biochemical marker for knee OA.

OBJECTIVE: To investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ABT-981, a human dual variable domain immunoglobulin simultaneously targeting interleukin (IL)-1alpha and IL-1beta, in patients with knee osteoarthritis. METHOD: This was a randomized, double-blind, placebo-controlled, single-center study of multiple subcutaneous (SC) injections of ABT-981 in patients with mild-to-moderate osteoarthritis of the knee (NCT01668511). Three cohorts received ABT-981 (0.3, 1, or 3 mg/kg) or placebo every other week for a total of 4 SC injections, and one cohort received ABT-981 (3 mg/kg) or placebo every 4 weeks for a total of 3 SC injections. Assessment of safety and tolerability were the primary objectives. A panel of serum and urine biomarkers of inflammation and joint degradation were evaluated. RESULTS: A total of 36 patients were randomized (ABT-981, n=28; placebo, n=8); 31 (86%) completed the study. Adverse event (AE) rates were comparable between ABT-981 and placebo (54% vs 63%). The most common AE reported with ABT-981 versus placebo was injection site erythema (14% vs 0%). ABT-981 significantly reduced absolute neutrophil count and serum concentrations of IL-1alpha/IL-1beta, high-sensitivity C-reactive protein, and matrix metalloproteinase (MMP)-derived type 1 collagen. Serum concentrations of MMP-derived type 3 collagen and MMP-degraded C-reactive protein demonstrated decreasing trends with ABT-981. Antidrug antibodies were found in 37% of patients but were not associated with the incidence or severity of AEs. CONCLUSION: ABT-981 was generally well tolerated in patients with knee osteoarthritis and engaged relevant tissue targets, eliciting an anti-inflammatory response. Consequently, ABT-981 may provide clinical benefit to patients with inflammation-driven osteoarthritis.

Perturbations of the intestinal microbiome have been observed in patients with new-onset and chronic autoimmune inflammatory arthritis. However, it is currently unknown whether these alterations precede the development of arthritis or are rather a consequence of disease. Modulation of intestinal microbiota by oral antibiotics or germ-free condition can prevent arthritis in mice. Yet, the therapeutic potential of modulation of the microbiota after the onset of arthritis is not well characterized. We here show that the intestinal microbial community undergoes marked changes in the preclinical phase of collagen induced arthritis (CIA). The abundance of the phylum Bacteroidetes, specifically families S24-7 and Bacteroidaceae was reduced, whereas Firmicutes and Proteobacteria, such as Ruminococcaceae, Lachnospiraceae and Desulfovibrinocaceae, were expanded during the immune-priming phase of arthritis. In addition, we found that the abundance of lamina propria Th17, but not Th1, cells is highly correlated with the severity of arthritis. Elimination of the intestinal microbiota during established arthritis specifically reduced intestinal Th17 cells and attenuated arthritis. These effects were associated with reduced serum amyloid A expression in ileum and synovial tissue. Our observations suggest that intestinal microbiota perturbations precede arthritis, and that modulation of the intestinal microbiota after the onset of arthritis may offer therapeutic opportunities.