OA Progression Research Articles

Comparison of radiographic and MRI osteoarthritis definitions and their combination for prediction of tibial cartilage loss, knee symptoms and total knee replacement: a longitudinal study

To describe the value of radiographic- and magnetic resonance imaging (MRI)-defined tibiofemoral osteoarthritis (ROA and MRI-OA, respectively) and in combination for predicting tibial cartilage loss, knee pain and disability and total knee replacement (TKR) in a population-based cohort. A radiograph and 1.5T MRI of the right knee was performed. ROA and MRI-OA at baseline were defined according to the Osteoarthritis Research Society International atlas and a published Delphi exercise, respectively. Tibial cartilage volume was measured over 2.6 and 10.7 years. Knee pain and disability were assessed at baseline, 2.6, 5.1 and 10.7 years. Right-sided TKRs were assessed over 13.5 years. Of 574 participants (mean 62 years, 49% female), 8% had ROA alone, 15% had MRI-OA alone, 13% had both ROA and MRI-OA. Having ROA (vs. no ROA) and MRI-OA (vs. no MRI-OA) predicted greater tibial cartilage loss over 2.6 years (-75.9 and-86.4mm3/year) and higher risk of TKR over 13.5 years (Risk Ratio [RR]: 15.0 and 10.9). Only MRI-OA predicted tibial cartilage loss over 10.7 years (-7.1mm3/year) and only ROA predicted onset and progression of knee symptoms (RR: 1.32-1.88). In participants with both MRI-OA and ROA, tibial cartilage loss was the greatest (over 2.6 years:-116.1mm3/year; over 10.7 years:-11.2mm3/year), and the onset and progression of knee symptoms (RR: 1.75-2.89) and risk of TKR (RR: 50.9) were the highest. The Delphi definition of MRI-OA is not superior to ROA for predicting structural or symptomatic OA progression but, combining MRI-OA and ROA has much stronger predictive validity.

Raman microspectroscopy demonstrates reduced mineralization of subchondral bone marrow lesions in knee osteoarthritis patients

IntroductionBone marrow lesions (BMLs) are frequently identified by MRI in the subchondral bone in knee osteoarthritis (KOA). BMLs are known to be closely associated with joint pain, loss of the cartilage and structural changes in the subchondral trabecular bone (SCTB). Despite this, understanding of the nature of BMLs at the trabecular tissue level is incomplete. Thus, we used Raman microspectroscopy to examine the biochemical properties of SCTB from KOA patients with presence or absence of BMLs (OA-BML, OA No-BML; respectively), in comparison with age-matched cadaveric non-symptomatic controls (Non-OA CTL). MethodsTibial plateau (TP) specimens were collected from 19 KOA arthroplasty patients (6-Male, 13-Female; aged 56–74 years). BMLs were identified ex-vivo by MRI, using PDFS- and T1-weighted sequences. The KOA specimens were then categorized into an OA-BML group (n = 12; containing a BML within the medial condyle only) and an OA No-BML group (n = 7; with no BMLs identified in the TP). The control (CTL) group consisted of Non-OA cadaveric TP samples with no BMLs and no macroscopic or microscopic evidence of OA-related changes (n = 8; 5-Male, 3-Female; aged 44–80 years). Confocal Raman microspectroscopy, with high spatial resolution, was used to quantify the biochemical properties of SCTB tissue of both the medial and the lateral condyle in each group. ResultsThe ratios of peak intensity and integrated area of bone matrix mineral (Phosphate (v1), Phosphate (v2) and Phosphate (v4)), to surrogates of the organic phase of bone matrix (Amide I, Proline and Amide III), were calculated. Within the medial compartment, the mineral:organic matrix ratios were significantly lower for OA-BML, compared to Non-OA CTL. These ratios were also significantly lower for the OA-BML medial compartment, compared to the OA-BML lateral compartment. There were no group or compartmental differences for Carbonate:Phosphate (v1, v2 and v4), Amide III (α-helix):Amide III (random-coil), Hydroxyproline:Proline, or Crystallinity. ConclusionAs measured by Raman microspectroscopy, SCTB tissue in BML zones in KOA is significantly less mineralized than the corresponding zones in individuals without OA. These data are consistent with those obtained using other methods (e.g. Fourier transform infrared spectroscopy; FTIR) and with the increased rate of bone remodeling observed in BML zones. Reduced mineralization may change the biomechanical properties of the trabecular bone in BMLs and the mechanical interaction between subchondral bone and its overlying cartilage, with potential implications for the development and progression of OA.

Undenatured Type II Collagen (UC-II) in Joint Health and Disease: A Review on the Current Knowledge of Companion Animals.

Simple SummaryOsteoarthritis (OA), the most common joint disease affecting humans and animals, is a painful, degenerative, and inflammatory disease that affects synovial joints and ultimately leads to loss of mobility. Non-pharmacological preventive approaches, several pharmaceutical therapeutic agents, and some medicines may reduce the progression of OA in animals. Many clinical and experimental studies have revealed that the undenatured form of type II collagen (UC-II) offers common health benefits to patients with OA.OA is quite common in companion animals, especially in large breed dogs and horses. Collagen, the most abundant protein of mammals, has specific connective tissue types for skin, bones, reticulate, basal lamina, bones, cell surfaces, while type II collagen (UC-II) forms the main structure of cartilage tissue. Even at the smaller dosages, UC-II has also been reported to be more effective than the glucosamine and chondroitin sulfate supplements, which are the supplements most frequently used in the market. In this review, we summarize the effects of UC-II on joint health and function in health and disease conditions in companion animals.

Intraosseous injections of platelet rich plasma for knee bone marrow lesions treatment: one year follow-up.

Cartilage lesions are usually accompanied by subchondral bone alterations or bone marrow lesions (BMLs). BML associated with joint degeneration and cartilage lesions are considered to be predictors of rapidly progressing OA. Currently no existing treatment can fully halt OA progression. One of the approaches is an autologous, biological treatment based on the use of platelet rich plasma (PRP) injections. The purpose of this study is to assess the short-term effectiveness of intraosseous PRP injections, within the BML of individuals affected by OA, in ameliorating pain and improving knee functionality. The study involved 17 patients with an average age of 41.7 ± 14.3years old. OA stage was determined using the Kellgren-Lawrence grading system by performing radiographic scanning of the knee joint before surgical intervention. Patients with K-L grade 3 knee joint OA prevailed. Patient OA history varied between one and nineyears (average 5.2 ± 4.5years). Clinical and functional state of the knee were assessed by pain visual analogue scale (VAS) score, the Western Ontario and McMaster Universities Score (WOMAC), and the Knee Injury and Osteoarthritis Outcome Score (KOOS) which were filled out by patients previous to the surgical procedure at one, three, six and 12months post-operatively. Before surgery, in addition to standard blood tests, serum cartilage oligomeric matrix protein (COMP) levels were tested for all patients. Evaluation of preliminary results revealed a statistically significant reduction of pain based on the VAS score. A significant improvement was also observed in the patients' WOMAC score and in the overall KOOS score. Serum marker levels were initially elevated in our experimental patient group compared to the same marker in healthy control respondents, and continued to rise one month and three months following surgery, at six and 12month the level was similar as at three months. In our opinion, first COMP increasing can be caused by injection of platelet rich plasma. It is not adequate to interpret this growth in COMP levels as increased osteochondral degeneration. One year follow-up period showed good quality of life improvement, significant pain reduction, and essential MRI changes. The long-term observation of these cohort of patients combined with an analysis of MRI images is still ongoing.

Discovery and functional analysis of osteoarthritis susceptibility genes using pedigrees from a statewide population-based cohort

Purpose: Lack of understanding of the biological processes conferring susceptibility to OA and the paucity of animal models are key limitations to the development of effective therapies. Our goal is to discover molecular pathways that are vulnerability points for the development of OA and generate mouse models using human disease alleles. We discover these pathways by identifying rare gene mutations in coding sequences that have a strong effect on susceptibility to OA in families identified from a unique statewide population-based cohort, the Utah Population Database. From the family studies, we identify gene variants that we view as candidates for having a strong effect on OA susceptibility. To rapidly identify those candidate variants that measurably alter gene function, we quantitatively assay WT and variant gene functions in zebrafish embryos. We then determine whether and how the functionally altered genes confer susceptibility to OA in genetically modified mouse models. Methods: To discover pathways that when modified lead to strong and unambiguous susceptibility to OA, we analyzed the exomes of 50 unrelated families from the Utah Population Database that had a significant enrichment of shoulder OA, distal and proximal interphalangeal joint hand OA, erosive hand OA, and 1st metatarsophalangeal (MTP) joint foot OA. We use loss- and gain-of-function analyses in zebrafish to rapidly screen for gene variants that have a functional impact on protein activity. Finally, Crispr/Cas9 technology is used to introduce OA-associated disease alleles into the mouse where we analyze the how these mutations affect onset and progression of OA. Results: Our results indicate that we can use families to identify genes and pathways that confer strong susceptibility to the early stages of OA. Our approach has led to the discovery of candidate gene variants in families with different forms of OA that affect common pathways. These pathways include genes that regulate i) the proinflammatory response, ii) mechanotransduction/mechanosensation, iii) the TGF-b and Notch signaling pathways, and iv) collagen modification. We have identified mutations in the NOD-RIPK2 pathway in families with interphalangeal joint, erosive hand, and 1st MTP joint OA. The NOD-RIPK2 pathway is a central regulator of the proinflammatory response. We have shown the OA-associated variants have increased proinflammatory activity relative to the wildtype protein. Based on these findings, we propose the gene variants act dominantly as a gain-of-function allele to over-stimulate the inflammatory response to naturally occurring joint damage leading to OA. To test this hypothesis we introduced a single amino acid change, encoded by the RIPK2 disease allele, into an isogenic mouse. Current results indicate mice harboring the disease allele exhibit increased severity of OA when compared to controls. Erosive hand OA is characterized radiographically by centrally located interphalangeal joint erosions, and clinically by its rapid onset and progression. Genomic analysis of one family identified a rare coding variant in the procollagen galactosyltransferase COLGALT1. We are currently analyzing the functional impact of the COLGLAT1 gene variant in zebrafish and examining if collagen structure is disrupted in articular cartilage of mice with a Colgalt1 mutation. Conclusions: Our studies indicate that we can use families to identify genes and pathways that confer strong susceptibility to the early stages of OA. Our approach has led to the discovery of i) compelling novel candidate genes, ii) multiple genes that contribute to a common pathway, iii) and identification of common pathways altered in multiple forms of OA, iv) and to the generation of new mouse models of OA. Our genetic studies of families with OA and functional analyses in the mouse support our hypothesis that variation in the inflammatory response may be a key factor in susceptibility to OA. Our work is significant in that we have taken a novel approach to identify genes that when mutated have a significant impact on the onset or progression of OA. Developing new animal models with these susceptibility genes will be useful for discovery of therapeutic drugs.

Prevalence of medial meniscus extrusion in elderly persons -the bunkyo health study

Purpose: Meniscus function is important in knee osteoarthritis (knee OA), and aging-related dysfunction of meniscus is becoming a risk factor for the development and progression of knee OA. Recently, meniscal malposition, especially medial meniscus extrusion (MME), in addition to conventional meniscal damage is also attracting attention, and it has been shown that MME plays an important role for the incidence and progression of knee OA. However, the mechanism of the developmental process of MME is still remained unclear. In our recent study using T2 mapping MRI, MME was found in all cases with early stage knee OA patients who did not have meniscal lesion or tear. We also demonstrated that osteophyte consists of cartilage- and bone-parts, as osteophyte is formed by the process similar to the endochondral ossification. When cartilage-part of osteophyte, in addition to bone-parts, was evaluated, MME was coincided with the medial tibial osteophyte width in patients with early- to primary-stage knee OA (Arthritis Res Ther, 19:201, 2017). However, there is no report of the prevalence of MME in the general elderly cohort data. The purpose of this study was to examine the prevalence of MME among the elderly using a population-based cohort data. Methods: A total of 1,630 subjects aged between from 65 to 84 years of age participated in the Bunkyo Health Study during from November 2015 to September 2018. 1,191 subjects underwent both the plain radiograph in the standing position and MRI on knee joint (Hitachi, 0.3T). As 46 among 1,191 who showed lateral type of knee OA (femoro-tibial angle <173) were excluded, the remaining 1145 subjects (55.7% females, 72.9 years of age on average) were analyzed. A radiographic severity of knee OA was classified into four grades using the Kellgren-Lawrence (K/L) classification. FTA and medial joint space width (JSW) were measured with X-ray. The MME was evaluated according to whole organ magnetic resonance imaging score (WORMS). In addition, the position of the medial meniscus was measured for anomalies (1 mm or more was regarded as a position error), and 3 mm or more was defined as MME. A p-value less than 5% was considered to be statistically significant. All analyses were undertaken using the statistical package SPSS. Results: The severity of radiographic medial knee OA of the subjects in the present study was 16 (1.4%) for K/L 1, 986 (86.1%) for K/L 2, 106 (9.3%) for K/L 3, and 37 (3.2%) for K/L 4. Abnormal position of medial meniscus was detected in almost all cases (1,139 persons, 99.5%, 4.4±2.1mm on average). The MME was detected 842 persons (73.5%). Prevalence by generation of the MME was increased with each generation (p<0.001): 70.7% for 65-70 years of age, 74.1% for 70-75 years of age, 74.7% for 75-80 years of age, 79.9% >80 years of age. Abnormal position of the medial meniscus was associated with FTA (r = 0.18 p <0.001), JSW (r = -0.20 p <0.001), and age (r = 0.13 p <0.001). Conclusions: In the present population-based study, most of the subjects among the middle aged and elderly populations who did not require the medical treatment for their knee joint showed the K/L grade 2 of radiographic knee OA change. In elderly people over the age of 65 in Japan, most of the medial meniscus had an abnormal position, and more than 70% of medial meniscus categorizes to MME. In addition, the probability of MME becomes higher with age.

The association of knee bending and physical activity with incident pain and functional limitation over 4 years in knee osteoarthritis

Purpose: Engaging in knee bending activities, e.g. climbing stairs, kneeling, or squatting, is a risk factor for the incidence and progression of knee OA and may be deleterious for knee pain. However, engaging in some knee bending activities is, in general, beneficial for lower extremity strength, which is related to future functional outcomes. Similar benefits to physical function are observed with physical activity (PA), e.g. walking. Knee bending activities and PA can co-occur, yet little is known about the joint association of knee bending and PA with pain and functional limitation. Therefore, the purpose of this study was to investigate the joint association of knee bending and objectively-measured PA with incident pain and functional limitation in adults with or at risk for knee OA. Methods: We used data from the 48-month and 96-month visits of the Osteoarthritis Initiative (OAI), a large cohort study of adults with or at risk for knee OA. Knee bending activities and objectively-measured PA (steps/day) exposures were collected at the 48-month visit (baseline). Knee bending was measured using four Yes/No questions used to determine study eligibility: climbing up a total of 10 or more flights of stairs, kneeling 30 minutes or more, squatting 30 minutes or more, and lifting or moving objects weighing 25 pounds or more by hand. Positive responses were summed and categorized as Low Bending (0-1 Yes responses) and High Bending (2-4 Yes responses). PA was measured with an Actigraph GT1M accelerometer and was separately dichotomized into Steps Active and Steps Inactive using 6000 steps/day, based on previous studies showing this is a meaningful threshold for preventing functional limitation. To investigate the joint association of knee bending and PA, we created a four-level exposure variable: (1) Steps Inactive & Low Bending, (2) Steps Active & Low Bending, (3) Steps Inactive & High Bending, (4) Steps Active & High Bending. Incident pain and functional limitation outcomes were assessed at the 96-month visit. VAS Pain (0-10) was dichotomized using patient acceptable symptom state levels, with a score of 3/10 as the cutoff for meaningful pain. Functional limitation was defined using slow gait speed from a 20-meter walk test (<1.22 m/s) which represents the inability to safely cross a timed street intersection. To determine the association of our four-level knee bending and PA exposure with incident pain and functional limitation, we used binary logistic regression to calculate risk ratios (RR) and 95% confidence intervals (95% CI), adjusting for potential confounders at baseline. Results: Of the adults with knee bending and valid accelerometry data who were free of meaningful pain (n = 1268) and functional limitation (n = 1307) at the 48-month visit, 1115 (age: 62.9 ± 8.4 years old, sex: 50.5% female, BMI: 28.0 ± 4.5 kg/m2) had all outcomes at the 96-month visit. Of those, 393 adults reported 0 or 1 knee bending activities and 722 adults reported 2 to 4 knee bending activities. 826 adults reported engaging in at least 1 knee bending activity on at least 2-3 days of the week. Steps Active & High Bending had 23% reduced risk for incident slow gait speed compared with Inactive & Low Bending, which met statistical significance (Adjusted RR [95% CI]: 0.77 [0.68 - 0.88]). Similarly sized protective effects that met statistical significance were found for the Steps Active & Low Bending and the Steps Inactive & High Bending groups with slow gait speed (Table 1B). There was no significant association between any of the exposure groups with incident pain above a patient acceptable symptom state (Table 1A). Conclusions: Adults who were active or engaged in 2 or more knee bending activities were at reduced risk for functional limitation 4 years later, with the greatest risk reduction seen in the Steps Active & High Bending group. We did not find knee bending activities and/or PA to be associated with incident knee pain above a patient acceptable symptom state. Despite the relationship between knee bending and progression of knee OA, these findings suggest that engaging in more knee bending activities, regardless of PA level, is not adversely related to pain or physical function.

The Role of Synovium in the Onset and Progression Of OA

The Role of Synovium in the Onset and Progression Of OA

Incidence and progression of ankle osteoarthritis: the Johnston county osteoarthritis project

Purpose: Osteoarthritis involving the ankles has been relatively understudied. We have previously demonstrated associations of older age, obesity, and prior injury with prevalent radiographic ankle OA (rAOA) in a community-based cohort (Lateef 2017), but little is known about ankle OA incidence and progression over time. The current project assessed the incidence and progression of ankle OA from the third (2013-2015, baseline) to the fourth (2016-18) follow-up (mean 3.5 years later) in the Johnston County OA Project.

Plantar pressure-based auditory feedback facilitated gait retraining to reduce KAM - A LONGITUDINAL feasibility study

Purpose: The knee adduction moment (KAM) is a surrogate measure of the ratio of knee compartmental loads that associates with the progression of medial knee OA. Multiple gait modifications have been developed to alter KAM, however, a strategy to promote learning of these gait modifications is lacking. A wireless pressure-detecting shoe insole (OpenGo, Moticon) contained in a standardized flexible shoe (FlexOA, Dr. Comfort), a smartphone, and a customized app were employed to facilitate gait retraining at home.

Prevalence and effect of medial meniscus tear in elderly persons -the bunkyo health study

Purpose: The meniscus has a function of dispersing the mechanical load applied to the knee joint. It has been recently revealed that meniscal tear is frequently observed in middle aged and elderly people with/without knee osteoarthritis (knee OA). Meniscal damage leads to the stress concentration to the joints and is, thus, it is becoming clear that meniscus damage is a risk factor for the onset and progression of knee OA. In resent MRI based cohort data, the prevalence of medial meniscal tear with no symptom in middle-aged and elderly is reported to be 28%. However, there is no similar report from large-scale cohort data for the prevalence of meniscus tear and the effect of meniscus tear for pain and mobility in elderly peoples. The purpose of this cross-sectional study was to examine the prevalence of meniscal tear and the effect of meniscus tear for pain and mobility in elderly people. Methods: A total of 1,630 subjects aged between from 65 to 84 years of age participated in the Bunkyo Health Study during from November 2015 to September 2018. 1,191 subjects underwent both the plain radiograph in the standing position and MRI on knee joint (Hitachi, 0.3T). As 46 among 1,191 subjects who showed lateral type of knee OA (femoro-tibial angle <173) were excluded, the remaining 1145 subjects (55.7% females, 72.9 years of age on average) were analyzed. A radiographic severity of knee OA was classified into four grades using the Kellgren-Lawrence (K/L) classification. The medial meniscal tear was evaluated according to MRI Osteoarthritis Knee Score (MOAKS). The linear lesion, which reached the femoral cartilage and / or the tibial cartilage, the complete root tear, and the empty meniscus were defined as a meniscus tear. The region of the medial meniscal tear was described with each five sections (anterior, body, posterior, posterior horn and root) using coronal and sagittal proton density weighted fat suppression (PDFS) images. A p-value less than 5% was considered to be statistically significant. All analyses were undertaken using the statistical package SPSS. Results: The severity of radiographic medial knee OA of the subjects in the present study was 16 (1.4%) for K/L 1, 986 (86.1%) for K/L 2, 106 (9.3%) for K/L 3, and 37 (3.2%) for K/L 4. Medial meniscus lesions were also detected in almost all cases (1144 cases, 99.8%). The medial meniscus tears were detected 453 persons (39.6%; K/L 1: 31.3%, K/L 2: 35.2%, K/L 3: 65.1%, K/L 4: 86.5%). Prevalence of the medial meniscus tears were increased with each generation (p<0.001): 31.8% for 65∼70 years of age, 40.0% for 70∼75 of age, 47.6% for 75∼80 years of age, 52.2% for >80 years of age. The risk of existing medial meniscus tear was significantly higher in K/L 3 and 4 group compared to K/L 1 and 2 group. (odds ratio: 4.6, 95%CI 3.1-6.8). The region of medial meniscus tear was 11.7% in anterior, 27.4% in body, 25.4% in posterior, 62.7% in posterior horn and root. In comparison between with and without medial meniscus tear, the medial meniscus tear group showed larger FTA, larger pain VAS and lower walk speed (adjusted age, BMI and sex, p<0.001, respectively). Conclusions: In the present population-based study, most of the subjects among the middle aged and elderly populations who did not require the medical treatment for their knee joint showed the K/L grade 2 of radiographic knee OA change. In addition, almost all the subjects had medial meniscus lesion, and nearly half of the subjects had medial meniscus tear. In addition, the probability of medial meniscal tears increased with age. The frequency of pain awareness and walking inability also increased with the prevalence of medial meniscus tear.

Distinct murine cartilage microbial DNA signatures are seen in high fat diet-induced obesity and aging

Purpose: The strongest nongenetic risk factors for primary knee OA are advanced age and obesity. We have previously demonstrated that human cartilage exhibits a microbial DNA signature which changes in association with the development and progression of knee OA. In this study, we hypothesized that aging and obesity, known to cause gut microbiome shifts, would also produce shifts in cartilage microbial DNA patterns in mice.

Pathology associations between different joint tissues are injury specific: a histopathological comparison of murine acl injury models

Purpose: Osteoarthritis involves disruption of joint homeostasis and the normal mechanobiological cross-talk between different joint tissues. Anterior cruciate ligament (ACL) injury models induce significant pathological change in tissues throughout the knee joint but unique spatial and temporal patterns of OA progression have been observed in different models: surgical versus non-surgical. Understanding the interaction between different tissue pathologies within the joint, and if this differs depending on injury mechanism, may provide important information regarding the onset and progression of post-traumatic OA, as well as considerations for tissue specific treatment targets.

Age and oxidative stress regulate NRF2 homeostasis in human articular chondrocytes

Purpose: An age related increase in reactive oxygen species generation and/or a decrease in antioxidant capacity can lead to oxidative stress conditions which can contribute to OA development and progression. Activation of Nuclear factor erythroid-2-related factor 2 (Nrf2) is required for the phase 2 antioxidant gene response and therefore contributes to intracellular redox balance and prevention of oxidation stress. The purpose of this study was (1) to investigate the effect of oxidative stress on regulation of Nrf2 in younger (<40 yrs) and older (>60 yrs) human chondrocytes and (2) to examine the effect of Nrf2 depletion and Nrf2 activation on chondrocyte antioxidant status.

A human joint-on-a-chip as alternative to animal models in osteoarthritis

Purpose: Molecular mechanisms of OA onset and progression are still poorly understood. Standard in vitro models as well as animal models still face limitations concerning human predictability. Consequently, therapeutic approaches to restore compromised cartilage tissue or decelerate disease progression of OA have not been identified yet.

Impact of controlling abnormal joint movement on the effectiveness of subsequent exercise intervention in mouse model of early knee osteoarthritis

Purpose: Moderate mechanical stress is necessary for preserving the cartilage. Recent evidence from animal models of surgically induced OA indicates that the progression of cartilage degeneration can be delayed by moderate exercise. On the other hand, joint instability induces excessive mechanical stress contributes to OA onset and progression. The anterior cruciate ligament transection (ACL-T) model, which is a commonly used animal model of surgically induced OA. In contrast, the controlled abnormal joint movement (CAJM) model, proposed by (Murata et al. 2017) and (Onitsuka et al. 2018) involves ACL-T followed by another surgical procedure to re-stabilize the joint and reduce joint instability. In the CAJM model, the expression of inflammatory factors and cartilage matrix degrading factors is suppressed, joint instability is reduced, and progression to OA is slower. We hypothesized that exercise intervention is more effective at preventing the degeneration of articular cartilage in knee OA if joint instability is controlled. Methods: This study used 28 adults (12-week-old) ICR male mice. The mice were divided into 4 experimental groups: ACL-T without exercise intervention, CAJM without exercise intervention, ACL-T with exercise intervention (ACL-T/Ex), and CAJM with exercise intervention (CAJM/Ex). For mice assigned to CAJM groups, a 25-gauge needle was used to create bone tunnels in the anterior portion of the proximal tibia and in the posterior portion of the femoral condyle in order to decrease the anterior translation of the tibia onto the femur. Subsequently, 4-0 nylon thread was passed through the bone tunnels to compensate for ACL function and help control the anterior translation of the tibia. To assess knee joint instability, the anterior drawer test was performed using a constant force spring (0.05 kgf; Sanko Spring Co., Ltd., Fukuoka, Japan) and a soft X-ray device (M-60; Softex Co., Ltd., Kanagawa, Japan). Mice allocated to the exercise groups (ACL-T/Ex and CAJM/Ex) were exercised on a rodent treadmill, were exercised on the treadmill at a constant speed of 18 m/min for 30 min/d, 3 d/wk, for 4 weeks. Thin sections (7 μm) were cut in the sagittal plane, stained with safranin-O/fast green, and subjected to histology evaluation to estimate the degree of cartilage damage. Two independent observers (T Kano and KO) per- formed OARSI scoring on a scale of 8 stages (0, 0.5, 1-6), and the average value was retained. To evaluate the expression of IL-1βand MMP-13, we performed immuno- histochemical staining using the avidin-biotinylated enzyme complex method. For analysis, we calculated the ratio between the number of IL-1β- or MMP-13-positive cells and the number of chondrocytes in an articular cartilage area of 10000 μm2 (100 μm × 100 μm). Results: Joint instability was quantified using X-ray radiography with the anterior drawer test (Fig. 1A).Compared with the ACL-T and ACL-T/Ex groups, the CAJM and CAJM/Ex groups had significantly lower anterior displacement of the tibia (p<0.05) (Fig. 1B).In the ACL-T/Ex group, marked surface fibrillation and reduction in cartilage thickness were noted in the posterior part of the articular cartilage, together with a significantly higher OARSI score than that noted for the other 3 groups (p<0.001) (Fig. 2). With regard to inflammation, IL-1β-positive cells were confirmed from the cartilage surface layer to the deep layer in the ACL-T, CAJM, and ACL-T/Ex groups but not in the CAJM/Ex group (Fig. 3A). The percentage of IL-1β- positive cells in the anterior part of the cartilage was significantly higher in the ACL-T and ACL-T/Ex groups than in the CAJM/Ex group, the percentage of IL-1β-positive cells in the posterior part of the cartilage was significantly higher for the ACL-T and ACL-T/Ex groups than for the CAJM/Ex group (p<0.05) (Fig. 3B). Similarly, MMP-13-positive cells were confirmed in the ACL-T and ACL-T/Ex groups, compared with very weak MMP-13 expression in the CAJM and CAJM/Ex groups (Fig. 3A). However, while no significant difference among the four groups was noted in terms of the percentage of MMP-13-positive cells in the anterior part of the cartilage, the percentage of MMP-13-positive cells in the posterior part of the cartilage was significantly higher for the ACL-T/Ex group than for the CAJM/Ex group (p=0.02) (Fig. 3C). Conclusions: Previous studies reported that exercise alone could delay the progress of OA. However, our present Results indicate that the internal environment of the joint strongly modulates the effect of exercise, sometimes completely canceling the benefit. In other words, when prescribing exercise, we need to consider the internal environment of the knee joint.In the clinical setting, these findings may trans- late in the need to consider an intervention to correct abnormal joint movement before prescribing physical exercise in the treatment of OA.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Study TPX-100-5: Significant reduction in femoral bone shape change 12 months after IA TPX-100 correlates with tibiofemoral cartilage stabilization

Purpose: Bone shape changes occur as part of normal aging in the knee. However, the rate of change and degree of pathologic deformation of bone is strikingly increased in knee OA. Based on data from the Osteoarthritis Initiative, pathologic three-dimensional (3D) changes in the femur have been shown to precede measurable thinning of tibiofemoral cartilage and to predict progression of OA, including total knee arthroplasty. Study TPX-100-5 was designed to compare 3D femoral shape changes in knees 6 and 12 months after IA TPX-100 or placebo in subjects with bilateral moderate to severe knee OA, and to analyze relationships between cartilage thickness and bone shape change from baseline to 12-month follow up.

Erosive hand osteoarthritis phenotype: clinical and proteomic characterization

Purpose: Erosive hand osteoarthritis (EHOA) is often considered a more severe form of hand OA that includes pain and inflammation. However, more data are needed regarding the different hand OA phenotypes, especially erosive and non-erosive, to conclude if they represent two different subsets of hand OA or even different degrees of affectation of the same disease. The purpose of this work is to define a specific clinical pattern of patients with EHOA and identify putative biochemical markers associated with this phenotype. Methods: This cross-sectional study was conducted in the Prospective Cohort of Osteoarthritis A Coruna (PROCOAC). This cohort consists of 1136 subjects, from which 834 were diagnosed of hand OA following ACR criteria. After reviewing the x-rays, the cohort was split into patients with and without erosive hand OA. Then, both clinical and demographic data within each group were subsequently analyzed. A Univariate analysis comparing different variables between both groups, followed by a stepwise regression logistic regression analysis was performed to characterize the clinical pattern of EHOA. The identification of biochemical markers was carried out following a two-step workflow: in a first discovery phase, a proteomic approach based on peptide labelling with Isobaric tags for relative and absolute quantitation (iTRAQ) was employed using two different sets of sera (n=20) from EHOA or non-EHOA patients. In a second validation phase an independent set of 346 individual serum samples from the PROCOAC cohort (EHOA, n=127; non-EHOA, n= 219) was used to quantify serum concentrations of the extracellular matrix protein 1 (ECM1) by ELISA. The Mann-Whitney test was carried out in order to look for significant differences between EHOA and non-EHOA groups. All the statistical analyses were performed using SPSS software v.24. Results: The univariate analysis showed that EHOA patients were younger (p<0.001), smokers (p=0.011), with lower both body mass index (p=0.006) and arterial hypertension (p=0.002); increased frequency of inflammatory symptoms in hands (p<0.001), more presence of nodular hand OA (p=0.001) but lower frequency of other forms of hand OA, specially thumb-base (p=0.005) and metacarpophalangeal (p=0.036). In addition, these patients also showed a lower number of damaged joints (p<0.001), specially the knee (p<0.001). The stepwise logistic regression model (Table 1) confirmed the strong association of age (OR=0.963;95%CI=0.937-0.989;p=0.005), inflammatory symptoms (OR=4.575;95%CI=2.621-7.985;p<0.001), increased prevalence of nodal OA (OR=2.125;95%CI=1.118-4.037;p=0.021) and, in patients over 64 years old, MetS (OR=2.029;95%CI=1.183-3.478;p=0.010) with the erosive phenotype. In addition, erosive patients show a lower prevalence of knee OA (OR=0.416;95%CI=0.252-0.687;p=0.001) and to carry this phenotype at baseline does not confer a significant increased risk for radiographic knee OA progression over time). Regarding the proteomic analysis for the identification of potential biomarkers associated with the EHOA phenotype, a total of 257 different proteins were identified in the serum samples with more than two peptides and a total score ≥2 at 95% confidence. Thirty-six proteins were found quantitatively altered between those patients with or without EHOA. A significant reduction (p=0.029) of ECM1 concentrations was found in the serum from patients with the EHOA phenotype (0.154 ± 0.010 μg/ml vs 0.169 ± 0.007 μg/ml) (Figure 1). Conclusions: A specific clinical pattern of patients with EHOA has been defined. It has been associated with altered levels of 36 proteins in serum. Particularly, decreased amounts of ECM1 have been found in patients with this erosive phenotype.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

GG genotype of SNP RS12107036 in TP63 gene increases the risk of rapidly progressive osteoarthritis of the knee. data from the osteoarthritis initiative

Purpose: There is a need to identify patients that experience the rapid progressive phenotype of Osteoarthritis (RPOA) to include them in clinical trials and to implement prevention strategies. During the last years, nuclear single nucleotide polymorphisms (SNPs) have been associated with both susceptibility and progression of the disease, but not with the rapid progression phenotype. Our aim is to analyze the influence of previously knee OA-associated nuclear SNPs on the risk of RPOA of the knee in patients of the OAI. Methods: We selected Caucasian patients from the OAI that were subsequently assigned into three different groups (252 patients each) based on the following criteria: i) rapid progressors, with baseline KL grade 0, 1 in at least one knee and increase up to KL≥ 3 during 48-month follow-up period; or baseline KL grade 2 in at least one knee and increase up to KL 4 or total knee replacement (TKR) during the follow-up. ii) no-rapid progressors, with baseline KL grade 0, 1 in at least one knee and increase up to KL 2 during 48-month follow-up period; or baseline KL grade 2 in at least one knee and increase up to KL 3 during the follow-up. iii) no-progressors, with KL grade 0, 1 or 2 at baseline in at least one knee and bilaterally stable during 48-month follow-up period. Additionally, these groups were re-categorized into two groups: non-progressors and progressors (pooling no-rapid and rapid progressors). Preliminary chi-square analyses and binary and multinomial logistic regression models adjusted by gender, age, body mass index (BMI), contralateral OA, previous injury in target knee and WOMAC pain, were performed. Nuclear SNPs were previously assigned using mini-sequencing techniques. The analyses were performed using IBM SPSS Statistics v24. Results: In this study we analyzed the effect of 7 SNPs that had been strongly associated with knee OA susceptibility in different GWAS studies: rs11177, rs4730250, rs11842874, rs12107036, rs8044769, rs10948172 and rs143383. Chi-square analyses showed that the frequency distribution of rs12107036 was significantly different between groups (p=0,028), being the GG genotype over-represented in the rapid-progressors group and the AA genotype in the non-progressors group (Figure 1). The binary logistic regression showed that G allele appeared significantly over-represented in the (pooled) progressors group when compared with non-progressors (OR 1,682; 95% CI: 1,148-2,463; p=0,008), regardless of gender (OR 2,049; 95% CI 1,478-2,842; p <0,001), BMI (OR 1,085; 95% CI 1,044-1,127; p<0,001), contralateral knee OA (OR 1,400; 95% CI 1,009-1,942; p=0,044), previous injury (OR 1,723; 95% CI 1,223-2,429; p=0,002) and WOMAC pain (OR 1,102; 95% CI 1,033-1,177; p=0,003) (Table 1). On the other hand the multinomial logistic regression showed that, in addition to age (OR 1,064; 95% CI: 1,041-1,088; p<0,001) and previous injury in target knee (OR 1,523; 95% CI: 1,047-2,216; p=0,028), the GG genotype (OR 1,574; 95% CI: 1,039-2,382; p=0,032) emerged as a potential risk factor for the rapid progression phenotype when compared with non-rapid progressors (Table 2). Conclusions: The G allele of the nuclear SNP rs12107036 increases the risk of knee OA progression. Depending on the number of copies of the risk allele the level of progression increases, being the GG genotype a risk factor for the rapidly progressive phenotype of the knee. The assignment of this nuclear polymorphism could be useful as complementary genetic biomarker for the early identification of this OA phenotype.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Synovial inflammation in anterior cruciate ligament injury knees in mice: surgical vs non-surgical models

Purpose: Anterior-cruciate-ligament (ACL) rupture is one of the most common knee injuries, resulting in pain, disability, and increased risk of developing OA. However, only ∼50% of individuals with ACL rupture develop OA, and the factors underlying this variable risk remain unclear. Changes in joint stability as a result of ACL deficiency drive mechanobiological dysfunction and the development of OA. However, specific factors are known to increase OA risk such as concurrent injury to the meniscus, cartilage, and subchondral bone. Also, the degree of initial joint inflammation and its resolution are implicated in long-term outcomes. Surgical and nonsurgical models of ACL rupture in mice result in similar joint instability but distinct risks or trajectories of OA. We used these two models to investigate if differences in synovial inflammatory response are associated with this risk of OA disease progression Methods: Ten-week-old, male C57BL/6 mice were randomly assigned to ACL transection (ACLT), ACL rupture (ACLR), sham-surgery or uninjured groups. Mice in the ACLT and sham-operated groups were subjected to anaesthesia, right unilateral medial arthrotomy, patella luxation, and fat-pad elevation to visualise the ACL, at which time the surgeon was informed to transect or spare the ACL before joint closure. Uninjured and ACLR animals were anaesthetised, the latter having a single compressive load (9-12N) to posteriorly displace the femur and traumatically rupture the ACL. Animals were housed in mixed injury groups (up to 5/cage) and allowed unrestricted activity. At 1, 2, 4 and 8 weeks post-injury, mice were euthanised and joints harvested for fixation, paraffin embedding, sectioning and OA histopathology scoring (n=7/group/timepoint); or synovial tissue (en bloc fat-pad, synovial lining and joint capsule anterior to the collateral ligaments) isolation for RNA extraction and quantitative RT-PCR analysis of cytokines (IL1, IL6, TNF), inflammatory cell markers (CD11b, CD4, CD8), and enzymes implicated in OA pathophysiology (ADAMTS4, ADAMTS5, MMP3, MMP9, MMP13) (n=6/group/time point). Results: ACL injury resulted in progressive OA pathology with cartilage pathology significantly greater in ACLR compared with ACLT at 2 and 4 weeks (p<0.001), but by 8 weeks was equivalent in the two models; posterior osteochondral erosion significantly worse in ACLR than ACLT at 4 and 8 weeks (p<0.01); and osteophyte size (p<0.001) and maturity (p<0.01) greater at 1 and 2 weels in ACLR compared with ACLT. Synovitis was increased acutely in both ACL-injuries and then decreased with time, with ACLT>ACLR (p=0.003) at week-1 but similar thereafter; both still greater than uninjured joints through to week 8 (p<0.001). Sham and ACLT had similar synovitis scores until week 8 when the latter was more severe. Despite histomorphological similarities in synovitis in ACLT and ACLR, there were differences in gene expression patterns. Synovial expression of TNF, CD11b and CD8 was unchanged at any time when comparing between groups. Surgery alone (ACLT and Sham) increased synovial IL6 (week-1: ACLT p=0.02, Sham p<0.001 vs uninjured) while ACLR did not. While CD4 was also increased by surgery (week-1 and -2: ACLT p<0.01, Sham p<0.05 vs uninjured), it was also increased in ACLR versus uninjured at these times (p<0.05; Figure 1). ADAMTS5 expression was not detected in synovial tissue, and MMP9 mRNA did not differ between groups. In contrast, ADAMTS4, MMP3, and MMP13 expression were increased by surgery (ACLT/Sham) and ACLR at week-1 and -2 compared with uninjured joint, although both surgeries>ACLR (Table 1). Conclusions: While both models caused joint instability, OA trajectory and ultimate severity were greater in ACLR. In contrast, surgery induced greater histo-pathological synovitis acutely but was similar in both injuries thereafter. There was a difference in the “phenotype” of the synovial inflammation in the two injury models. In ACLT there was upregulation of IL6 not evident in ACLR but similar to Sham, suggesting this was a response to surgery and wound healing. While helper T-cell (CD4) increase was greater in ACLT and Sham, this also occurred in ACLR suggesting a role of adaptive immunity in OA after nonsurgical injury. Expression of ADAMTS4, MMP3 and MMP13 were similarly increased acutely in both injury models, suggesting synovial tissues as a source of these enzymes implicated in the structural pathology of OA. While their expression was not correlated with ultimate pathological severity they may be broad-spectrum target across varying phenotypes of post-traumatic OA. Our data suggest that synovitis severity per se was not associated with differential OA risk with ACL injury; it likely still contributes to long-term OA structural pathology.View Large Image Figure ViewerDownload Hi-res image Download (PPT)