Protective effects of licofelone, a 5-lipoxygenase and cyclo-oxygenase inhibitor, versus naproxen on cartilage loss in knee osteoarthritis: a first multicentre clinical trial using quantitative MRI

Poly-beta-amino-ester licofelone conjugates development for osteoarthritis treatment

Disease-modifying osteoarthritis drugs (DMOADs) are a new therapeutic class for osteoarthritis (OA) prevention or inhibition of the disease development. Unfortunately, none of the DMOADs have been clinically approved due to their poor therapeutic performances in clinical trials. The joint environment has played a role in this process by limiting the amount of drug effectively delivered as well as the time that the drug stays within the joint space. The current study aimed to improve the delivery of the DMOADs into cartilage tissue by increasing uptake and retention time of the DMOADs within the tissue. Licofelone was used a model DMOAD due to its significant therapeutic effect against OA progression as shown in the recent phase III clinical trial. For this purpose licofelone was covalently conjugated to the two different A16 and A87 poly-beta-amino-ester (PBAEs) polymers taking advantage of their hydrolysable, cytocompatible, and cationic nature. We have shown cartilage uptake of the licofelone-PBAE conjugates increased 18 times and retention in tissues was prolonged by 37 times compared to the equivalent dose of the free licofelone. Additionally, these licofelone conjugates showed no detrimental effect on the chondrocyte viability. In conclusion, the cationic A87 and A16 PBAE polymers increased the amount of licofelone within the cartilage, which could potentially enhance the therapeutic effect and pharmacokinetic performance of this drug and other DMOADs clinically.

Machine Learning Approaches to the Prediction of Osteoarthritis Phenotypes and Outcomes

PURPOSE OF REVIEW

Osteoarthritis (OA) is a complex heterogeneous disease with no effective treatments. Artificial intelligence (AI) and its subfield machine learning (ML) can be applied to data from different sources to (1) assist clinicians and patients in decision making, based on machine-learned evidence, and (2) improve our understanding of pathophysiology and mechanisms underlying OA, providing new insights into disease management and prevention. The purpose of this review is to improve the ability of clinicians and OA researchers to understand the strengths and limitations of AI/ML methods in applications to OA research.

RECENT FINDINGS

AI/ML can assist clinicians by prediction of OA incidence and progression and by providing tailored personalized treatment. These methods allow using multidimensional multi-source data to understand the nature of OA, to identify different OA phenotypes, and for biomarker discovery. We described the recent implementations of AI/ML in OA research and highlighted potential future directions and associated challenges.

Clinical significance and management of meniscal extrusion in different knee pathologies: a comprehensive review of the literature and treatment algorithm

The menisci are crescent-shaped, fibrocartilaginous structures that play a crucial role in the load transition and distribution of the contact forces along the tibiofemoral articulation. Meniscal extrusion (ME) is a radiological finding, especially in magnetic resonance imaging (MRI) scans, for which there has been growing interest in recent years. ME, in the coronary plane, is defined as the maximum distance of the most distal end of the meniscus from the border of the tibial plateau, where the tibial eminences are the most prominent, without taking into account the osteophytes. Although there is still controversy in the literature in respect of the optimal cutoff value, a threshold of 3 mm is considered significant. ME has no specific clinical finding or sign and it is encountered in many knee pathologies. It is associated with either rapidly progressive knee osteoarthritis or early onset of knee osteoarthritis and increased morbidity. In this review, we delineate the clinical significance of ME in various knee pathologies, as well as when, why and how it should be managed. To the best of our knowledge, this is the first study to elaborate on these topics.

Serum Metabolomic Signatures for Knee Cartilage Volume Loss over 10 Years in Community-Dwelling Older Adults

Osteoarthritis (OA) is the most prevalent joint disorder characterized by joint structural pathological changes with the loss of articular cartilage as its hallmark. Tools that can predict cartilage loss would help identify people at high risk, thus preventing OA development. The recent advance of the metabolomics provides a new avenue to systematically investigate metabolic alterations in disease and identify biomarkers for early diagnosis. Using a metabolomics approach, the current study aimed to identify serum metabolomic signatures for predicting knee cartilage volume loss over 10 years in the Tasmania Older Adult Cohort (TASOAC). Cartilage volume was measured in the medial, lateral, and patellar compartments of the knee by MRI at baseline and follow-up. Changes in cartilage volume over 10 years were calculated as percentage change per year. Fasting serum samples collected at 2.6-year follow-up were metabolomically profiled using the TMIC Prime Metabolomics Profiling Assay and pairwise metabolite ratios as the proxies of enzymatic reaction were calculated. Linear regression was used to identify metabolite ratio(s) associated with change in cartilage volume in each of the knee compartments with adjustment for age, sex, and BMI. The significance level was defined at α = 3.0 × 10−6 to control multiple testing. A total of 344 participants (51% females) were included in the study. The mean age was 62.83 ± 6.13 years and the mean BMI was 27.48 ± 4.41 kg/m2 at baseline. The average follow-up time was 10.84 ± 0.66 years. Cartilage volume was reduced by 1.34 ± 0.72%, 1.06 ± 0.58%, and 0.98 ± 0.46% per year in the medial, lateral, and patellar compartments, respectively. Our data showed that the increased ratios of hexadecenoylcarnitine (C16:1) to tetradecanoylcarnitine (C14) and C16:1 to dodecanoylcarnitine (C12) were associated with 0.12 ± 0.02% reduction per year in patellar cartilage volume (both p < 3.03 × 10−6). In conclusion, our data suggested that alteration of long chain fatty acid β-oxidation was involved in patellar cartilage loss. While confirmation is needed, the ratios of C16:1 to C14 and C12 might be used to predict long-term cartilage loss.

A Machine Learning Model to Predict Knee Osteoarthritis Cartilage Volume Changes over Time Using Baseline Bone Curvature

The hallmark of osteoarthritis (OA), the most prevalent musculoskeletal disease, is the loss of cartilage. By using machine learning (ML), we aimed to assess if baseline knee bone curvature (BC) could predict cartilage volume loss (CVL) at one year, and to develop a gender-based model. BC and cartilage volume were assessed on 1246 participants using magnetic resonance imaging. Variables included age, body mass index, and baseline values of eight BC regions. The outcome consisted of CVL at one year in 12 regions. Five ML methods were evaluated. Validation demonstrated very good accuracy for both genders (R ≥ 0.78), except the medial tibial plateau for the woman. In conclusion, we demonstrated, for the first time, that knee CVL at one year could be predicted using five baseline BC region values. This would benefit patients at risk of structural progressive knee OA.

Restricting Branched-Chain Amino Acids within a High-Fat Diet Prevents Obesity

Obesity is a global pandemic, but there is yet no effective measure to control it. Recent metabolomics studies have identified a signature of altered amino acid profiles to be associated with obesity, but it is unclear whether these findings have actionable clinical potential. The aims of this study were to reveal the metabolic alterations of obesity and to explore potential strategies to mitigate obesity. We performed targeted metabolomic profiling of the plasma/serum samples collected from six independent cohorts and conducted an individual data meta-analysis of metabolomics for body mass index (BMI) and obesity. Based on the findings, we hypothesized that restriction of branched-chain amino acids (BCAAs), phenylalanine, or tryptophan may prevent obesity and tested our hypothesis in a dietary restriction trial with eight groups of 4-week-old male C57BL/6J mice (n = 5/group) on eight different types of diets, respectively, for 16 weeks. A total of 3397 individuals were included in the meta-analysis. The mean BMI was 30.7 ± 6.1 kg/m2, and 49% of participants were obese. Fifty-eight metabolites were associated with BMI and obesity (all p ≤ 2.58 × 10-4), linked to alterations of the BCAA, phenylalanine, tryptophan, and phospholipid metabolic pathways. The restriction of BCAAs within a high-fat diet (HFD) maintained the mice's weight, fat and lean volume, subcutaneous and visceral adipose tissue weight, and serum glucose and insulin at levels similar to those in the standard chow group, and prevented obesity, adipocyte hypertrophy, adipose inflammation, and insulin resistance induced by HFD. Our data suggest that four metabolic pathways, BCAA, phenylalanine, tryptophan, and phospholipid metabolic pathways, are altered in obesity and restriction of BCAAs within a HFD can prevent the development of obesity and insulin resistance in mice, providing a promising strategy to potentially mitigate diet-induced obesity.

Two-Dimensional and Three-Dimensional Cartilage Model Platforms for Drug Evaluation and High-Throughput Screening Assays

Osteoarthritis (OA) is a severely painful and debilitating disease of the joint, which brings about degradation of the articular cartilage and currently has few therapeutic solutions. Two-dimensional (2D) high-throughput screening (HTS) assays have been widely used to identify candidate drugs with therapeutic potential for the treatment of OA. A number of small molecules which improve the chondrogenic differentiation of progenitor cells for tissue engineering applications have also been discovered in this way. However, due to the failure of these models to accurately represent the native joint environment, the efficacy of these drugs has been limited in vivo. Screening systems utilizing three-dimensional (3D) models, which more closely reflect the tissue and its complex cell and molecular interactions, have also been described. However, the vast majority of these systems fail to recapitulate the complex, zonal structure of articular cartilage and its unique cell population. This review summarizes current 2D HTS techniques and addresses the question of how to use existing 3D models of tissue-engineered cartilage to create 3D drug screening platforms with improved outcomes. Impact statement Currently, the use of two-dimensional (2D) screening platforms in drug discovery is common practice. However, these systems often fail to predict efficacy in vivo, as they do not accurately represent the complexity of the native three-dimensional (3D) environment. This article describes existing 2D and 3D high-throughput systems used to identify small molecules for osteoarthritis treatment or in vitro chondrogenic differentiation, and suggests ways to improve the efficacy of these systems based on the most recent research.

The Efficacy and Safety of Disease-Modifying Osteoarthritis Drugs for Knee and Hip Osteoarthritis-a Systematic Review and Network Meta-Analysis

BACKGROUND

Osteoarthritis (OA) is common and burdensome for patients and health care systems. Our study purpose was to evaluate the long-term efficacy and safety of DMOADs in adults with knee and hip osteoarthritis.

METHODS

We searched Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and Web of Knowledge without language, publication, or date restrictions from inception through November 2018 for randomized controlled trials assessing 12 classes of DMOADs with at least 12 months of follow-up. Therapeutic effects were evaluated with pairwise and network meta-analysis. Outcomes included pain, function, minimum joint space width or cartilage volume, radiographic progression, and total joint replacement. Analyses were also performed for drug safety.

RESULTS

Twenty-eight randomized controlled trials with 11,890 patients were included. Glucosamine and chondroitin minimally improved both structure (minimum joint width or cartilage volume: network results: glucosamine: SMD 0.16; 95% CI [0.04, 0.28], chondroitin: SMD 0.21 [0.10, 0.32]) and symptoms (glucosamine: pain: - 0.15 [- 0.25, - 0.05]; function: - 0.17 [- 0.28, - 0.07], chondroitin: pain: - 0.06 [- 0.15, 0.03], and function: - 0.15 [- 0.26, - 0.03]). Strontium demonstrated improvement in structure (minimum joint width or cartilage volume: 0.20 [0.02, 0.38]), and vitamin D on symptoms (pain: - 0.15 [- 0.27, -0.03]; function: - 0.18 [- 0.31, - 0.06]). Although doxycycline also demonstrated a favorable efficacy ranking, its safety profile was poor (withdrawal: network relative risk 1.69 [1.03, 2.75]). The therapeutic effects of other medications were not ranked as highly.

DISCUSSION

Glucosamine and chondroitin yielded statistically significant but clinically questionable long-term benefit on structure and symptoms, though both had favorable safety profiles. Strontium improved structure, and vitamin D improved symptoms. Although doxycycline had a favorable efficacy ranking, its safety profile was poor. None of the 12 classes of drugs appears to have long-term clinically significant benefit.

Involvement of N-Methyl-D-Aspartate Receptors in the Anticonvulsive Effects of Licofelone on Pentylenetetrazole-Induced Clonic Seizure in Mice

BACKGROUND AND PURPOSE

Licofelone is a dual 5-lipoxygenase/cyclooxygenase inhibitor, with well-documented anti-inflammatory and analgesic effects, which is used for treatment of osteoarthritis. Recent preclinical studies have also suggested neuroprotective and anti-oxidative properties of this drug in some neurological conditions such as seizure and epilepsy. We have recently demonstrated a role for nitric oxide (NO) signaling in the anti-epileptic activity of licofelone in two seizure models in rodents. Given the important role of N-methyl-D-aspartate receptors (NMDARs) activation in the NO production and its function in the nervous system, in the present study, we further investigated the involvement of NMDAR in the effects of licofelone (1, 3, 5, 10, and 20 mg/kg, intraperitoneal [i.p.]) in an in vivo model of seizure in mice.

METHODS

Clonic seizures were induced in male NMRI mice by intravenous administration of pentylenetetrazol (PTZ).

RESULTS

Acute administration of licofelone exerted anticonvulsant effects at 10 (p<0.01) and 20 mg/kg (p<0.001). A combined treatment with sub-effective doses of the selective NMDAR antagonist MK-801 (0.05 mg/kg, i.p.) and licofelone (5 mg/kg, i.p.) significantly (p<0.001) exerted an anticonvulsant effect on the PTZ-induced clonic seizures in mice. Notably, pre-treatment with the NMDAR co-agonist D-serine (30 mg/kg, i.p.) partially hindered the anticonvulsant effects of licofelone (20 mg/kg).

CONCLUSIONS

Our data suggest a possible role for the NMDAR in the anticonvulsant effects of licofelone on the clonic seizures induced by PTZ in mice.

From Pathogenesis to Therapy in Knee Osteoarthritis: Bench-to-Bedside

Osteoarthritis (OA) is currently the most widespread musculoskeletal condition and primarily affects weight-bearing joints such as the knees and hips. Importantly, knee OA remains a multifactorial whole-joint disease, the appearance and progression of which involves the alteration of articular cartilage as well as the synovium, subchondral bone, ligaments, and muscles through intricate pathomechanisms. Whereas it was initially depicted as a predominantly aging-related and mechanically driven condition given its clear association with old age, high body mass index (BMI), and joint malalignment, more recent research identified and described a plethora of further factors contributing to knee OA pathogenesis. However, the pathogenic intricacies between the molecular pathways involved in OA prompted the study of certain drugs for more than one therapeutic target (amelioration of cartilage and bone changes, and synovial inflammation). Most clinical studies regarding knee OA focus mainly on improvement in pain and joint function and thus do not provide sufficient evidence on the possible disease-modifying properties of the tested drugs. Currently, there is an unmet need for further research regarding OA pathogenesis as well as the introduction and exhaustive testing of potential disease-modifying pharmacotherapies in order to structure an effective treatment plan for these patients.

A warning machine learning algorithm for early knee osteoarthritis structural progressor patient screening

Aim

In osteoarthritis (OA) there is a need for automated screening systems for early detection of structural progressors. We built a comprehensive machine learning (ML) model that bridges major OA risk factors and serum levels of adipokines/related inflammatory factors at baseline for early prediction of at-risk knee OA patient structural progressors over time.

Methods

The patient- and gender-based model development used baseline serum levels of six adipokines, three related inflammatory factors and their ratios (36), as well as major OA risk factors [age and bone mass index (BMI)]. Subjects (677) were selected from the Osteoarthritis Initiative (OAI) progression subcohort. The probability values of being structural progressors (PVBSP) were generated using our previously published prediction model, including five baseline structural features of the knee, i.e. two X-rays and three magnetic resonance imaging variables. To identify the most important variables amongst the 47 studied in relation to PVBSP, we employed the ML feature classification methodology. Among five supervised ML algorithms, the support vector machine (SVM) demonstrated the best accuracy and use for gender-based classifiers development. Performance and sensitivity of the models were assessed. A reproducibility analysis was performed with clinical trial OA patients.

Results

Feature selections revealed that the combination of age, BMI, and the ratios CRP/MCP-1 and leptin/CRP are the most important variables in predicting OA structural progressors in both genders. Classification accuracies for both genders in the testing stage (OAI) were >80%, with the highest sensitivity of CRP/MCP-1. Reproducibility analysis showed an accuracy ⩾92%; the ratio CRP/MCP-1 demonstrated the highest sensitivity in women and leptin/CRP in men.

Conclusion

This is the first time that such a framework was built for predicting knee OA structural progressors. Using this automated ML patient- and gender-based model, early prediction of knee structural OA progression can be performed with high accuracy using only three baseline serum biomarkers and two risk factors.

Plain language summary

Machine learning model for early knee osteoarthritis structural progression Knee osteoarthritis is a well-known debilitating disease leading to reduced mobility and quality of life - the main causes of chronic invalidity. Disease evolution can be slow and span many years; however, for some individuals, the progression/evolution can be fast. Current treatments are only symptomatic and conventional diagnosis of osteoarthritis is not very effective in early identification of patients who will progress rapidly. To improve therapeutic approaches, we need a robust prediction model to stratify osteoarthritis patients at an early stage according to risk of joint structure disease progression.We hypothesize that a prediction model using a machine learning system would enable such an early identification of individuals for whom osteoarthritis knee structure will degrade rapidly. Data were from the Osteoarthritis Initiative, a National Institute of Health (United States) databank, and the robustness and generalizability of the developed model was further evaluated using osteoarthritis patients from an external cohort. Using the supervised machine learning system (support vector machine), we developed an automated patient- and gender-based model enabling an early clinical prognosis for individuals at high risk of structural progressive osteoarthritis. In brief, this model employed at baseline (when the subject sees a physician) easily obtained features consisting of the two main osteoarthritis risk factors, age and bone mass index (BMI), in addition to the serum levels of three molecules. Two of these molecules belong to a family of factors names adipokines and one to a related inflammatory factor. In brief, the model comprising a combination of age, BMI, and the ratios CRP/MCP-1 and leptin/CRP were found very robust for both genders, and the high accuracy persists when tested with an external cohort conferring the gender-based model generalizability. This study offers a new automated system for identifying early knee osteoarthritis structural progressors, which will significantly improve clinical prognosis with real time patient monitoring.

Discovery and Development of a Novel mPGES-1/5-LOX Dual Inhibitor LFA-9 for Prevention and Treatment of Chronic Inflammatory Diseases

Background

Non-steroidal anti-inflammatory drugs, cyclooxygenase (COX)-2 selective inhibitors, have been explored for prevention and treatment of several inflammatory chronic conditions including arthritis, and cancer. However, the long-term use of these drugs is associated with gastrointestinal, renal, and cardiovascular side effects. Later, COX/5-lipoxygenase (5-LOX) dual inhibitors (eg, licofelone) have been developed but did not enter into the market from the clinical trails due to COX-1/2 inhibition-associated side effects. Hence, targeting microsomal prostaglandin E synthase-1 (mPGES-1) and 5-LOX can be an ideal approach while sparing COX-1/2 activities for development of the next generation of anti-inflammatory drugs with better efficacy and safety.

Materials and Methods

In silico (molecular modelling) studies were used to design a mPGES-1/5-LOX dual inhibitory and COX-1/2 sparing lead molecule licofelone analogue-9 (LFA-9) by modifying the pharmacophore of licofelone. In vitro cell-free enzymatic (mPGES-1, 5-LOX, COX-1/2) assays using fluorometric/colorimetric methods and cell-based assays (LPS-induced PGE₂, LTB₄, and PGI₂ productions from macrophages) using ELISA technique, isothermal calorimetry, and circular dichroism techniques were performed to determine the mPGES-1/5-LOX inhibitory efficacy and selectivity. Anti-inflammatory efficacy of LFA-9 was evaluated using a carrageenan (inflammogen)-induced rat paw edema model. Infiltration/expression of CD68 immune cells and TNF-α in paw tissues were evaluated using confocal microscope and immunoblot analysis. Anti-cancer effect of LFA-9 was evaluated using colon spheroids in vitro.

Results

LFA-9 inhibited mPGES-1/5-LOX and their products PGE₂ and LTB₄, spared COX-1/2 and its product PGI₂. LFA-9 bound strongly with human mPGES-1/5-LOX enzymes and induced changes in their secondary structure, thereby inhibited their enzymatic activities. LFA-9 inhibited carrageenan-induced inflammation (70.4%) in rats and suppressed CD68 immune cell infiltration (P ≤ 0.0001) and TNF-α expression. LFA-9 suppressed colon tumor stemness (60.2%) in vitro through inhibition of PGE₂ (82%) levels.

Conclusion

Overall study results suggest that LFA-9 is a mPGES-1/5-LOX dual inhibitor and showed anti-inflammatory and colorectal cancer preventive activities, and warranted detailed studies.

Structure-based, multi-targeted drug discovery approach to eicosanoid inhibition: Dual inhibitors of mPGES-1 and 5-lipoxygenase activating protein (FLAP)

BACKGROUND

Due to the importance of both prostaglandins (PGs) and leukotrienes (LTs) as pro-inflammatory mediators, and the potential for eicosanoid shunting in the presence of pathway target inhibitors, we have investigated an approach to inhibiting the formation of both PGs and LTs as part of a multi-targeted drug discovery effort.

METHODS

We generated ligand-protein X-ray crystal structures of known inhibitors of microsomal prostaglandin E2 synthase-1 (mPGES-1) and the 5-Lipoxygenase Activating Protein (FLAP), with their respective proteins, to understand the overlapping pharmacophores. We subsequently used molecular modeling and structure-based drug design (SBDD) to identify hybrid structures intended to inhibit both targets.

RESULTS

This work enabled the preparation of compounds 4 and 5, which showed potent in vitro inhibition of both targets.

SIGNIFICANCE

Our findings enhance the structural understanding of mPGES-1 and FLAP's unique ligand binding pockets and should accelerate the discovery of additional dual inhibitors for these two important integral membrane protein drug targets.

Identification of the most important features of knee osteoarthritis structural progressors using machine learning methods

Objectives:

The aim was to identify the most important features of structural knee osteoarthritis (OA) progressors and classification using machine learning methods.

Methods:

Participants, features and outcomes were from the Osteoarthritis Initiative. Features were from baseline (1107), including articular knee tissues (135) assessed by quantitative magnetic resonance imaging (MRI). OA progressors were ascertained by four outcomes: cartilage volume loss in medial plateau at 48 and 96 months (Prop_CV_48M, 96M), Kellgren–Lawrence (KL) grade ⩾ 2 and medial joint space narrowing (JSN) ⩾ 1 at 48 months. Six feature selection models were used to identify the common features in each outcome. Six classification methods were applied to measure the accuracy of the selected features in classifying the subjects into progressors and non-progressors. Classification of the best features was done using an automatic machine learning interface and the area under the curve (AUC). To prioritize the top five features, sparse partial least square (sPLS) method was used.

Results:

For the classification of the best common features in each outcome, Multi-Layer Perceptron (MLP) achieved the highest AUC in Prop_CV_96M, KL and JSN (0.80, 0.88, 0.95), and Gradient Boosting Machine for Prop_CV_48M (0.70). sPLS showed the baseline top five features to predict knee OA progressors are the joint space width, mean cartilage thickness of the medial tibial plateau and sub-regions and JSN.

Conclusion:

In this comprehensive study using a large number of features (n = 1107) and MRI outcomes in addition to radiological outcomes, we identified the best features and classification methods for knee OA structural progressors. Data revealed baseline X-ray and MRI-based features could predict early OA knee progressors and that MLP is the best classification method.

Clinical relevance of biochemical and metabolic changes in osteoarthritis

Osteoarthritis (OA) is a multifactorial disease with huge phenotypic heterogeneity. The disease affects all tissues in the joint, and the loss of articular cartilage is its hallmark. The main biochemical components of the articular cartilage are type II collagen, aggrecan, and water. Transforming growth factor-beta (TGF-β) signaling is one of the signaling pathways that maintains the healthy cartilage. However, the two subpathways of the TGF-β signaling-TGF-β and bone morphogenetic proteins (BMP) subpathways, lose their balance in OA, resulting an increased expression of cartilage degradation enzymes including matrix metallopeptidase 13 (MMP13), cathepsin B (CTSB), and cathepsin K (CTSK) and a decreased expression of aggrecan (ACAN). Thus, restoring the balance of two subpathways might provide a new avenue for treating OA patients. Further, metabolic changes are seen in OA and can be used to distinguish different subtypes of OA patients. Metabolomics studies showed that at least three endotypes of OA can be distinguished: 11% of OA patients are characterized by an elevated blood butyryl carnitine, 33% of OA patients have significant reduced arginine concentration, and 56% with metabolic alteration in phospholipid metabolism. While these findings need to be confirmed, they are promising personalized medicine tools for OA management.

Serum adipokines/related inflammatory factors and ratios as predictors of infrapatellar fat pad volume in osteoarthritis: Applying comprehensive machine learning approaches

OBJECTIVE

The infrapatellar fat pad (IPFP) has been associated with knee osteoarthritis onset and progression. This study uses machine learning (ML) approaches to predict serum levels of some adipokines/related inflammatory factors and their ratios on knee IPFP volume of osteoarthritis patients.

METHODS

Serum and MRI were from the OAI at baseline. Variables comprised the 3 main osteoarthritis risk factors (age, gender, BMI), 6 adipokines, 3 inflammatory factors, and their 36 ratios. IPFP volume was assessed on MRI with a ML methodology. The best variables and models were identified in Total-cohort (n = 678), High-BMI (n = 341) and Low-BMI (n = 337), using a selection approach based on ML methods.

RESULTS

The best model for each group included three risk factors and adipsin/C-reactive protein combined for Total-cohort, adipsin/chemerin; High-BMI, chemerin/adiponectin HMW; and Low-BMI, interleukin-8. Gender separation improved the prediction (13-16%) compared to the BMI-based models. Reproducibility with osteoarthritis patients from a clinical trial was excellent (R: female 0.83, male 0.95). Pseudocodes based on gender were generated.

CONCLUSION

This study demonstrates for the first time that the combination of the serum levels of adipokines/inflammatory factors and the three main risk factors of osteoarthritis could predict IPFP volume with high reproducibility, with the superior performance of the model accounting for gender separation.

Spontaneous dog osteoarthritis - a One Medicine vision

Osteoarthritis (OA) is a global disease that, despite extensive research, has limited treatment options. Pet dogs share both an environment and lifestyle attributes with their owners, and a growing awareness is developing in the public and among researchers that One Medicine, the mutual co-study of animals and humans, could be beneficial for both humans and dogs. To that end, this Review highlights research opportunities afforded by studying dogs with spontaneous OA, with a view to sharing this active area of veterinary research with new audiences. Similarities and differences between dog and human OA are examined, and the proposition is made that suitably aligned studies of spontaneous OA in dogs and humans, in particular hip and knee OA, could highlight new avenues of discovery. Developing cross-species collaborations will provide a wealth of research material and knowledge that is relevant to human OA and that cannot currently be obtained from rodent models or experimentally induced dog models of OA. Ultimately, this Review aims to raise awareness of spontaneous dog OA and to stimulate discussion regarding its exploration under the One Medicine initiative to improve the health and well-being of both species.

Osteoarthritis occurs spontaneously in pet dogs, which often share environmental and lifestyle risk-factors with their owners. This Review aims to stimulate cooperation between medical and veterinary research under the One Medicine initiative to improve the welfare of dogs and humans.

Dogs have many analogous spontaneous diseases that result in end-stage osteoarthritis (OA).

Inbreeding and the predisposition of certain dog breeds for OA enable easier identification of candidate genetic associations than in outbred humans.

Dog OA subtypes offer a potential stratification rationale for aetiological differences and alignment to analogous human OA phenotypes.

The relatively compressed time course of spontaneous dog OA offers longitudinal research opportunities.

Collaboration with veterinary researchers can provide tissue samples from early-stage OA and opportunities to evaluate new therapeutics in a spontaneous disease model.

Awareness of the limitations and benefits of using clinical veterinary patients in research is important.

In vivo protective effect of adipsin-deficiency on spontaneous knee osteoarthritis in aging mice

The adipokine adipsin is an emerging mediator of human osteoarthritis (OA) progression. Here, we investigated its in vivo role in the development of spontaneous OA in aging mice. We compared articular knee joint morphology, histology in knee cartilage, synovial membrane, subchondral bone, meniscus, and anterior cruciate ligament (ACL); and chondrogenesis in the ACL from adipsin-deficient (Df^-/-) and wild-type (Df^+/+) 20-week- and 20-month-old mice. Serum levels of a panel of adipokines, inflammatory factors, and metalloproteases known to be implicated in OA were investigated. Data first revealed that the early manifestation of OA appeared in the ACL of 20-week-old mice, progressing to severe alterations in the 20 month-old wild-type mice. Further results demonstrated that adipsin-deficiency protected the articular tissues from spontaneous OA progression and triggered significantly higher serum levels of the adipokines adiponectin and FGF-21 while lowering levels of the inflammatory factor interleukin 6 (IL-6) in both young and old mice. This work further underlines the clinical relevance of adipsin as a novel therapeutic approach of human OA. Moreover, this study shows the potential beneficial effect of the adipokine FGF-21 against OA, and provides support for this factor to be a new biomarker and/or target of primary OA therapeutic avenues.

Serum lysophosphatidylcholines to phosphatidylcholines ratio is associated with symptomatic responders to symptomatic drugs in knee osteoarthritis patients

Background

Identification of the optimal treatment for a given patient is of paramount importance. This is of particular relevance in osteoarthritis (OA) because of the high prevalence of the disease, extensive heterogeneity of the disease, and need for long-term treatment. The aim of the study was to examine whether serum lysophosphatidylcholines (lysoPCs) to phosphatidylcholines (PCs) ratio can predict clinical response to licofelone and naproxen treatments in symptomatic knee OA patients.

Methods

One hundred fifty-eight OA patients who completed the study according to protocol (ATP) of a previous 24-month clinical trial cohort comparing the effect of licofelone vs. naproxen in symptomatic knee OA patients were included. Symptomatic responses to either treatments were classified according to the OARSI-OMERACT criteria based on the WOMAC scores at 24 months. Total concentrations of PCs and lysoPCs were measured in the serum samples collected before the initiation of the treatments, and the lysoPCs to PCs ratio was calculated. Student’s t test was utilized to compare the difference in the ratio of lysoPCs to PCs between the symptomatic responders and non-responders. Logistic regression was utilized to adjust for the potential confounders. Receiver operating characteristic (ROC) analysis was performed to identify the optimal cutoff of the ratio for prediction.

Results

Data showed that 61.4% of the patients symptomatically responded to licofelone and naproxen and 38.6% were deemed as therapeutic failures (non-responders). There was no difference in responders between licofelone and naproxen (p = 0.87). Responders had a significantly higher lysoPCs to PCs ratio than non-responders (0.097 ± 0.003 vs. 0.085 ± 0.003; p = 0.006). Patients with a ratio greater than the optimal cutoff of 0.088 had 2.93 times more likely to respond to licofelone and naproxen (p = 0.002).

Conclusions

Serum lysoPCs to PCs ratio is a marker for response to licofelone and naproxen and may aid in the personalized treatment to knee OA.

Fully automated patellofemoral MRI segmentation using holistically nested networks: Implications for evaluating patellofemoral osteoarthritis, pain, injury, pathology, and adolescent development

PURPOSE

Our clinical understanding of the relationship between 3D bone morphology and knee osteoarthritis, as well as our ability to investigate potential causative factors of osteoarthritis, has been hampered by the time-intensive nature of manually segmenting bone from MR images. Thus, we aim to develop and validate a fully automated deep learning framework for segmenting the patella and distal femur cortex, in both adults and actively growing adolescents.

METHODS

Data from 93 subjects, obtained from on institutional review board-approved protocol, formed the study database. 3D sagittal gradient recalled echo and gradient recalled echo with fat saturation images and manual models of the outer cortex were available for 86 femurs and 90 patellae. A deep-learning-based 2D holistically nested network (HNN) architecture was developed to automatically segment the patella and distal femur using both single (sagittal, uniplanar) and 3 cardinal plane (triplanar) methodologies. Errors in the surface-to-surface distances and the Dice coefficient were the primary measures used to quantitatively evaluate segmentation accuracy using a 9-fold cross-validation.

RESULTS

Average absolute errors for segmenting both the patella and femur were 0.33 mm. The Dice coefficients were 97% and 94% for the femur and patella. The uniplanar, relative to the triplanar, methodology produced slightly superior segmentation. Neither the presence of active growth plates nor pathology influenced segmentation accuracy.

CONCLUSION

The proposed HNN with multi-feature architecture provides a fully automatic technique capable of delineating the often indistinct interfaces between the bone and other joint structures with an accuracy better than nearly all other techniques presented previously, even when active growth plates are present.

The ratio adipsin/MCP-1 is strongly associated with structural changes and CRP/MCP-1 with symptoms in obese knee osteoarthritis subjects: data from the Osteoarthritis Initiative

OBJECTIVE

There is a need to identify reliable biomarkers that can predict knee osteoarthritis (OA) progression. We investigated a panel of adipokines and some related inflammatory factors alone and their ratios for their associative value at assessing cartilage volume loss over time and symptoms in obese [High body mass index (BMI)] and non-obese (Low BMI) OA subjects.

DESIGN

Human OA serum was from the Osteoarthritis Initiative Progression subcohort. Baseline levels of adiponectin (high and low molecular weight forms), adipsin, chemerin, leptin, visfatin, C-reactive protein (CRP), interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) were evaluated with specific assays. Cartilage volume was assessed at baseline and 48 months by quantitative magnetic resonance imaging (MRI), and symptoms using baseline Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. Data were analysed by linear regression with confounding factors at baseline, followed by multiple comparison adjustment.

RESULTS

The levels of the nine biomarkers and their ratios (36) were studied. Among High BMI subjects, only the ratio adipsin/MCP-1 was associated with cartilage volume loss over time in the lateral compartment [β, -2.95; 95% confidence interval (CI), -4.42, -1.49; P = 0.010], whereas MCP-1 was associated with WOMAC pain (-1.74; -2.75, -0.73; P = 0.030) and the ratio CRP/MCP-1 with WOMAC pain (0.76; 0.37, 1.14; P = 0.023), function (2.43; 1.20, 3.67; P = 0.020) and total (3.29; 1.58, 5.00; P = 0.027). No associations were found for biomarkers or ratios in Low BMI OA.

CONCLUSION

In this study, the ratio adipsin/MCP-1 was found to be associated with the knee structural changes and that of CRP/MCP-1 with symptoms in obese OA subjects. Our data further underline the relevance of ratios as biomarkers to a stronger association to OA progression and symptoms.

Activation of The Phosphatidylcholine to Lysophosphatidylcholine Pathway Is Associated with Osteoarthritis Knee Cartilage Volume Loss Over Time

To identify serum biomarker(s) for predicting knee cartilage volume loss over time, we studied 139 knee osteoarthritis (OA) patients from a previous 24-month clinical trial cohort. Targeted metabolomic profiling was performed on serum collected at baseline. The pairwise metabolite ratios as proxies for enzymatic reaction were calculated and used in the analysis. Cartilage volume loss between baseline and 24 months was assessed quantitatively by magnetic resonance imaging (MRI). Data revealed an association between the serum ratio of lysophosphatidylcholine 18:2 (lysoPC 18:2) to phosphatidylcholine 44:3 (PC44:3) and the cartilage volume loss in the lateral compartment (β = -0.21 ± 0.04, p = 8.53*10^-7) and with joint degradation markers, COMP (r = 0.32, p = 0.0002) and MMP1 (r = 0.26, p = 0.002). The significance remained after adjustment for age, sex, BMI, diabetes, hypertension, dyslipidemia, and the treatment taken in the original study. As the ratio indicated the over activation of the conversion pathway of PC to lysoPC catalyzed by phospholipase A₂ (PLA₂), we assessed and found that a specific PLA₂, PLA₂G5, was significantly increased in human OA cartilage and synovial membrane (85% and 19% respectively, both p < 0.04) compared to controls, and its overexpression correlated with IL-6 (r = 0.63, p = 0.0008). Our data suggest that the serum lysoPC 18:2 to PC44:3 ratio is highly associated with a greater risk of cartilage volume loss of the knee and warrants further investigation in an independent cohort.

Association of Pharmacological Treatments With Long-term Pain Control in Patients With Knee Osteoarthritis: A Systematic Review and Meta-analysis

IMPORTANCE

Even though osteoarthritis is a chronic and progressive disease, pharmacological agents are mainly studied over short-term periods, resulting in unclear recommendations for long-term disease management.

OBJECTIVE

To search, review, and analyze long-term (≥12 months) outcomes (symptoms, joint structure) from randomized clinical trials (RCTs) of medications for knee osteoarthritis.

DATA SOURCES AND STUDY SELECTION

The databases of MEDLINE, Scopus, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials were searched until June 30, 2018 (MEDLINE alerts through August 31, 2018) for RCTs of patients with knee osteoarthritis that had treatment and follow-up lasting 1 year or longer.

DATA EXTRACTION AND SYNTHESIS

Data at baseline and at the longest available treatment and follow-up of 12 months' duration or longer (or the change from baseline) were extracted. A Bayesian random-effects network meta-analysis was performed.

MAIN OUTCOMES AND MEASURES

The primary outcome was the mean change from baseline in knee pain. Secondary outcomes were physical function and joint structure (the latter was measured radiologically as joint space narrowing). Standardized mean differences (SMDs) and mean differences with 95% credibility intervals (95% CrIs) were calculated. Findings were interpreted as associations when the 95% CrIs excluded the null value.

RESULTS

Forty-seven RCTs (22 037 patients; mean age range, mostly 55-70 years; and a higher mean proportion of women than men, around 70%) included the following medication categories: analgesics; antioxidants; bone-acting agents such as bisphosphonates and strontium ranelate; nonsteroidal anti-inflammatory drugs; intra-articular injection medications such as hyaluronic acid and corticosteroids; symptomatic slow-acting drugs in osteoarthritis such as glucosamine and chondroitin sulfate; and putative disease-modifying agents such as cindunistat and sprifermin. Thirty-one interventions were studied for pain, 13 for physical function, and 16 for joint structure. Trial duration ranged from 1 to 4 years. Associations with decreases in pain were found for the nonsteroidal anti-inflammatory drug celecoxib (SMD, -0.18 [95% CrI, -0.35 to -0.01]) and the symptomatic slow-acting drug in osteoarthritis glucosamine sulfate (SMD, -0.29 [95% CrI, -0.49 to -0.09]), but there was large uncertainty for all estimates vs placebo. The association with pain improvement remained significant only for glucosamine sulfate when data were analyzed using the mean difference on a scale from 0 to 100 and when trials at high risk of bias were excluded. Associations with improvement in joint space narrowing were found for glucosamine sulfate (SMD, -0.42 [95% CrI, -0.65 to -0.19]), chondroitin sulfate (SMD, -0.20 [95% CrI, -0.31 to -0.07]), and strontium ranelate (SMD, -0.20 [95% CrI, -0.36 to -0.05]).

CONCLUSIONS AND RELEVANCE

In this systematic review and network meta-analysis of studies of patients with knee osteoarthritis and at least 12 months of follow-up, there was uncertainty around the estimates of effect size for change in pain for all comparisons with placebo. Larger RCTs are needed to resolve the uncertainty around efficacy of medications for knee osteoarthritis.

Disease-modifying drugs in osteoarthritis: current understanding and future therapeutics

INTRODUCTION

Osteoarthritis (OA) is a leading cause of pain and disability among adults with a current prevalence of around 15% and a predicted prevalence of 35% in 2030 for symptomatic OA. It is increasingly recognized as a heterogeneous multi-faceted joint disease with multi-tissue involvement of varying severity. Current therapeutic regimens for OA are only partially effective and often have significant associated toxicities. There are no disease-modifying drugs approved by the regulatory bodies. Areas covered: We reviewed the opportunities within key OA pathogenetic mechanism: cartilage catabolism/anabolism, pathological remodeling of subchondral bone and synovial inflammation to identify targeted disease-modifying osteoarthritis drugs, based on compounds currently in Phase II and III stages of clinical development in which x-ray and/or MRI was used as the structural outcome with/without symptomatic outcomes according to regulatory requirements. Expert opinion: Given the heterogeneity of the OA disease process and complex overlapping among these phenotypes, a 'one size fits all' approach used in most clinical trials would unlikely be practical and equally effective in all patients, as well as in all anatomical OA sites. On the other hand, it is a challenge to develop a targeted drug with high activity, specificity, potency, and bioavailability in the absence of toxicity for long-term use in this chronic disease of predominantly older adults. Further research and insight into evaluation methods for drug-targeted identification of early OA and specific characterization of phenotypes, improvement of methodological designs, and development/refinement of sensitive imaging and biomarkers will help pave the way to the successful discovery of disease-modifying drugs and the optimal administration strategies in clinical practice.

High in vivo levels of adipsin lead to increased knee tissue degradation in osteoarthritis: data from humans and animal models

Objective

This study explored the role of the adipokine adipsin in OA.

Methods

Control and OA articular tissues, cells and serum were obtained from human individuals. Serum adipsin levels of human OA individuals were compared with cartilage volume loss as assessed by MRI at 48 months. Human adipsin expression was determined by PCR, its production in tissues by immunohistochemistry, and in SF and serum by a specific assay. OA was surgically induced in wild-type (Df+/+) and adipsin-deficient (Df-/-) mice, and synovial membrane and cartilage processed for histology and immunohistochemistry.

Results

Adipsin levels were significantly increased in human OA serum, SF, synovial membrane and cartilage compared with controls, but the expression was similar in chondrocytes, synoviocytes and osteoblasts. Multivariate analysis demonstrated that human serum adipsin levels were significantly associated (P = 0.045) with cartilage volume loss in the lateral compartment of the knee. Destabilization of the medial meniscus-Df-/- mice showed a preservation of the OA synovial membrane and cartilage lesions (P ⩽ 0.026), the latter corroborated by the decreased production of cartilage degradation products and proteases (P ⩽ 0.047). The adipsin effect is likely due to a deficient alternative complement pathway (P ⩽ 0.036).

Conclusion

In human OA, higher serum adipsin levels were associated with greater cartilage volume loss in the lateral compartment, and adipsin deficiency led to a preservation of knee structure. Importantly, we documented an association between adipsin and OA synovial membrane and cartilage degeneration through the activation of the complement pathway. This study highlights the clinical relevance of adipsin as a valuable biomarker and potential therapeutic target for OA.

Investigational drugs for the treatment of osteoarthritis, an update on recent developments

INTRODUCTION

Osteoarthritis (OA) is the leading cause of pain, loss of function, and disability among elderly, with the knee the most affected joint. It is a heterogeneous condition characterized by complex and multifactorial etiologies which contribute to the broad variation in symptoms presentation and treatment responses that OA patients present. This poses a challenge for the development of effective treatment on OA.

AREAS COVERED

This review will discuss recent development of agents for the treatment of OA, updating our previous narrative review published in 2015. They include drugs for controlling local and systemic inflammation, regulating articular cartilage, targeting subchondral bone, and relieving pain.

EXPERT OPINION

Although new OA drugs such as monoclonal antibodies have shown marked effects and favorable tolerance, current treatment options for OA remain limited. The authors believe there is no miracle drug that can be used for all OA patients'; treatment and disease stage is crucial for the effectiveness of drugs. Therefore, early diagnosis, phenotyping OA patients and precise therapy would expedite the development of investigational drugs targeting at symptoms and disease progression of OA.

Pyrrolizine-5-carboxamides: Exploring the impact of various substituents on anti-inflammatory and anticancer activities

Towards optimization of the pyrrolizine-5-carboxamide scaffold, a novel series of six derivatives (4a-c and 5a-c) was prepared and evaluated for their anti-inflammatory, analgesic and anticancer activities. The (EZ)-7-cyano-6-((4-hydroxybenzylidene)amino)-N-(p-tolyl)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (4b) and (EZ)-6-((4-chlorobenzylidene)-amino)-7-cyano-N-(p-tolyl)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (5b) bearing the electron donating methyl group showed the highest anti-inflammatory activity while (EZ)-6-((4-chlorobenzylidene)amino)-7-cyano-N-phenyl-2,3-dihydro-1H-pyrrolizine-5-carboxamide (5a) was the most active analgesic agent. Cytotoxicity of the new compounds was evaluated against the MCF-7, A2780 and HT29 cancer cell lines using the MTT assay. Compounds 4b and 5b displayed high anticancer activity with IC50 in the range of 0.30-0.92 μmol L-1 against the three cell lines, while compound (EZ)-N-(4-chlorophenyl)-7-cyano-6-((4-hydroxybenzylidene)-amino)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (4c) was the most active against MCF-7 cells (IC50 = 0.08 μmol L-1). Both the anti-inflammatory and anticancer activities of the new compounds were dependent on the type of substituent on the phenyl rings. Substituents with opposite electronic effects on the two phenyl rings are preferable for high cytotoxicity against the MCF-7 and A2780 cells. COX inhibition was suggested as the molecular mechanism of the anti-inflammatory activity of the new compounds while no clear relationship could be observed between COX inhibition and anticancer activity. Compound 5b, the most active against the three cell lines, induced dose-dependent early apoptosis with 0.1-0.2 % necrosis in MCF-7 cells. New compounds showed promising drug-likeness scores while the docking study revealed high binding affinity to COX-2. Taken together, this study highlighted the significant impact of the substituents on the anti-inflammatory and anticancer activity of pyrrolizine-5-carboxamides, which could help in further optimization to discover good leads for the treatment of cancer and inflammation.

Impact of oral osteoarthritis therapy usage among other risk factors on knee replacement: a nested case-control study using the Osteoarthritis Initiative cohort

BACKGROUND

The aim of this study was to measure the association between exposure to commonly used oral osteoarthritis (OA) therapies and relevant confounding risk factors on the occurrence of knee replacement (KR), using the Osteoarthritis Initiative (OAI) database.

METHODS

In this nested case-control design study, participants who had a KR after cohort entry were defined as "cases" and were matched with up to four controls for age, gender, income, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, Kellgren-Lawrence grade, and duration of follow up. Exposure to oral OA therapies (acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase-2 (COX-2) inhibitors, narcotics, and glucosamine/chondroitin sulfate) was determined within the 3 years prior to the date of the KR. Conditional regression analyses were performed to estimate the association between KR and exposure to oral OA therapies and other potential confounding risk factors.

RESULTS

A total of 218 participants who underwent a KR (cases) were matched to 540 controls. The median time to KR was 4.3 years among cases. The majority in both groups were Caucasian with mean age of 69 years and 61% were female. Numerically, cases were more exposed to acetaminophen, NSAIDs, and COX-2 inhibitors. Exposure to narcotics and glucosamine/chondroitin sulfate was relatively similar between cases and controls. No significant association was found between the occurrence of KR and exposure to any of the oral OA therapies within the 3 years prior to KR. A significantly higher occurrence of KR was found in Caucasian subjects (OR 1.84; 95% CI, 1.13-2.99; p = 0.015) and subjects with body mass index (BMI) ≥ 27 kg/m² (OR 1.65; 95% CI, 1.06-2.58; p = 0.027).

CONCLUSION

This study provides evidence that the main risk factors leading to KR are disease severity, symptoms and high BMI. Importantly, exposure to oral OA therapies was not associated with the occurrence of KR.

Emerging Treatment Models in Rheumatology: Challenges for Osteoarthritis Trials

At a time when advancing understanding of osteoarthritis (OA) has created opportunities for new treatments, development of treatments has remained considerably behind advances in other rheumatic diseases. We describe elements of trial design and measurements that have inhibited success and offer suggestions that may help break the log jam. Among the problems with trials that include pain as an outcome measure are reliance on a single, non-optimal pain outcome, overestimation of likely effects of treatments on pain, and failure to identify patient subgroups most likely to respond to specific treatments. With regard to the use of structure modification as an outcome measure, demonstrating structure modification is often highly challenging, even with the use of magnetic resonance imaging. Many OA patients have advanced disease that is unlikely to respond to treatments that prevent cartilage loss. Further, prevention of cartilage loss and reduction of pain correlate weakly at best, and in at least some patients, reduction in pain may actually increase joint damage, making it impossible to demonstrate dual treatment effects on structure and pain in such scenarios. For structure outcomes, treatment effects on pain-sensitive structures such as bone and synovium may be more achievable than preventing cartilage loss. We suggest that changes in trial design related to some of these issues may increase the chances that new exciting and effective OA treatments will become available.

Current status and future prospects for disease modification in osteoarthritis

OA is a chronic, progressive and disabling joint disease, leading to a poor quality of life and an enormous social and economic burden. Current therapies for OA patients remain limited, which creates an area of huge unmet medical need. For some time, researchers have been looking for approaches that can inhibit the structural progression of OA. A variety of potential disease-modifying OA drugs have been developed, targeting cartilage, inflammatory pathways or subchondral bone. In addition, non-pharmacological therapies, including joint distraction and weight loss, draw increasing attention, with some showing disease-modifying potential. Thus we performed a comprehensive review to discuss the current status of disease-modifying therapies in OA and appraise the potentials of emerging novel agents.

Deletion of 12/15-lipoxygenase accelerates the development of aging-associated and instability-induced osteoarthritis

OBJECTIVE

12/15-Lipoxygenase (12/15-LOX) catalyzes the generation of various anti-inflammatory lipid mediators, and has been implicated in several inflammatory and degenerative diseases. However, there is currently no evidence that 12/15-LOX has a role in osteoarthritis (OA). The aim of this study was to investigate the role of 12/15-LOX in the pathogenesis of OA.

METHODS

The development of aging-associated and destabilization of the medial meniscus (DMM)-induced OA were compared in 12/15-LOX-deficient (12/15-LOX-/-) and wild-type (WT) mice. The extent of cartilage damage was evaluated by histology. The expression of OA markers was evaluated by immunohistochemistry and RT-PCR. Cartilage explants were stimulated with IL-1α in the absence or presence of the 12/15-LOX metabolites, 15-hydroxyeicosatetraenoic acids (15-HETE), 13-hydroxyoctadecadienoic acid (13-HODE) or lipoxin A4 (LXA4), and the levels of matrix metalloproteinases-13 (MMP-13), Nitric oxide (NO) and prostaglandin E₂ (PGE₂) were determined. The effect of LXA4 on the progression of OA was evaluated in wild type (WT) mice.

RESULTS

The expression of 12/15-LOX in cartilage increased during the progression of DMM-induced OA and with aging in WT mice. Cartilage degeneration was more severe in 12/15-LOX-/- mice compared to WT mice in both models of OA, and this was associated with increased expression of MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs, aggrecanases (ADAMTS5), inducible NO synthases (iNOS), and mPGES-1. Treatment of cartilage explants with 12/15-LOX metabolites, suppressed IL-1α-induced production of MMP-13, NO and PGE₂, with LXA4 being the most potent. Intra-peritoneal injection of LXA4 reduced the severity of DMM-induced cartilage degradation.

CONCLUSIONS

These data suggest an important role of 12/15-LOX in the pathogenesis of OA. They also suggest that activation of this pathway may provide a novel strategy for prevention and treatment of OA.

Developing anti-inflammatory therapeutics for patients with osteoarthritis

OA is the most common joint disorder in the world, but there are no approved therapeutics to prevent disease progression. Historically, OA has been considered a wear-and-tear joint disease, and efforts to identify and develop disease-modifying therapeutics have predominantly focused on direct inhibition of cartilage degeneration. However, there is now increasing evidence that inflammation is a key mediator of OA joint pathology, and also that the link between obesity and OA is not solely due to excessive load-bearing, suggesting therefore that targeting inflammation in OA could be a rewarding therapeutic strategy. In this review we therefore re-evaluate historical clinical trial data on anti-inflammatory therapeutics in OA patients, highlight some of the more promising emerging therapeutic targets and discuss the implications for future clinical trial design.

EULAR recommendations for the use of imaging in the clinical management of peripheral joint osteoarthritis

The increased information provided by modern imaging has led to its more extensive use. Our aim was to develop evidence-based recommendations for the use of imaging in the clinical management of the most common arthropathy, osteoarthritis (OA). A task force (including rheumatologists, radiologists, methodologists, primary care doctors and patients) from nine countries defined 10 questions on the role of imaging in OA to support a systematic literature review (SLR). Joints of interest were the knee, hip, hand and foot; imaging modalities included conventional radiography (CR), MRI, ultrasonography, CT and nuclear medicine. PubMed and EMBASE were searched. The evidence was presented to the task force who subsequently developed the recommendations. The strength of agreement for each recommendation was assessed. 17 011 references were identified from which 390 studies were included in the SLR. Seven recommendations were produced, covering the lack of need for diagnostic imaging in patients with typical symptoms; the role of imaging in differential diagnosis; the lack of benefit in monitoring when no therapeutic modification is related, though consideration is required when unexpected clinical deterioration occurs; CR as the first-choice imaging modality; consideration of how to correctly acquire images and the role of imaging in guiding local injections. Recommendations for future research were also developed based on gaps in evidence, such as the use of imaging in identifying therapeutic targets, and demonstrating the added value of imaging. These evidence-based recommendations and related research agenda provide the basis for sensible use of imaging in routine clinical assessment of people with OA.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Chondroitin sulfate efficacy versus celecoxib on knee osteoarthritis structural changes using magnetic resonance imaging: a 2-year multicentre exploratory study

Background

In osteoarthritis (OA) treatment, although chondroitin sulfate (CS) was found in a number of studies using radiography to have a structure-modifying effect, to date CS use is still under debate. A clinical study using quantitative magnetic resonance imaging (qMRI) is therefore of the utmost importance. Here we report data from a 24-month, randomised, double-blind, double-dummy, controlled, comparative exploratory study of knee OA. The primary endpoint was to determine the effect of CS 1200 mg/day versus celecoxib 200 mg/day on cartilage volume loss (CVL) in the lateral compartment over time as measured by qMRI. Secondary endpoints included assessment of the OA structural changes and signs and symptoms of OA.

Methods

qMRI was performed at baseline and at 12 and 24 months. CVL, bone marrow lesion size, and synovial thickness were evaluated using qMRI. The primary statistical analysis was carried out on the modified intention-to-treat (mITT) population (n = 138) using chi-squared, Fisher’s exact, Wilcoxon Mann–Whitney, and Student’s t tests and analysis of covariance. Analyses were also conducted on the according-to-protocol (ATP; n = 120) population.

Results

In the adjusted mITT analysis, compared with celecoxib treatment, patients treated with CS had a significant reduced CVL at 24 months in the medial compartment (celecoxib –8.1 % ± 4.2, CS –6.3 % ± 3.2; p = 0.018) and medial condyle (–7.7 % ± 4.7, –5.5 % ± 3.9; p = 0.008); no significant effect was seen in the lateral compartment. In the ATP population, CS reduced CVL in the medial compartment at 12 months (celecoxib –5.6 % ± 3.0, CS –4.5 % ± 2.6; p = 0.049) and 24 months (celecoxib –8.4 % ± 4.2, CS –6.6 % ± 3.3; p = 0.021), and in the medial condyle at 24 months (celocoxib –8.1 % ± 4.7, CS –5.7 % ± 4.0; p = 0.010). A trend towards a statistically reduced synovial thickness (celecoxib +17.96 ± 33.73 mm, CS –0.66 ± 22.72 mm; p = 0.076) in the medial suprapatellar bursa was observed in CS patients. Both groups experienced a marked reduction in the incidence of patients with joint swelling/effusion and in symptoms over time. Data showed similar good safety profiles including cardiovascular adverse events for both drugs.

Conclusion

This study demonstrated, for the first time in a 2-year randomised controlled trial using qMRI, the superiority of CS over celecoxib at reducing CVL in knee OA patients.

Trial registration

ClinicalTrials.gov NCT01354145. Registered 13 May 2011.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1149-0) contains supplementary material, which is available to authorized users.

Low-grade inflammation as a key mediator of the pathogenesis of osteoarthritis

Osteoarthritis (OA) has long been viewed as a degenerative disease of cartilage, but accumulating evidence indicates that inflammation has a critical role in its pathogenesis. Furthermore, we now appreciate that OA pathogenesis involves not only breakdown of cartilage, but also remodelling of the underlying bone, formation of ectopic bone, hypertrophy of the joint capsule, and inflammation of the synovial lining. That is, OA is a disorder of the joint as a whole, with inflammation driving many pathologic changes. The inflammation in OA is distinct from that in rheumatoid arthritis and other autoimmune diseases: it is chronic, comparatively low-grade, and mediated primarily by the innate immune system. Current treatments for OA only control the symptoms, and none has been FDA-approved for the prevention or slowing of disease progression. However, increasing insight into the inflammatory underpinnings of OA holds promise for the development of new, disease-modifying therapies. Indeed, several anti-inflammatory therapies have shown promise in animal models of OA. Further work is needed to identify effective inhibitors of the low-grade inflammation in OA, and to determine whether therapies that target this inflammation can prevent or slow the development and progression of the disease.

Magnetic Resonance Imaging of Articular Cartilage

The emergence of newer pharmacotherapeutic agents and surgical cartilage resurfacing techniques is driving the need for imaging modalities capable of early, accurate, and reproducible lesion detection. Magnetic resonance imaging (MRI) has emerged as a noninvasive tool for direct 2-dimensional (2D) and 3-dimensional (3D) assessment of the articular cartilage in both clinical and research settings. MRI has largely overcome the shortcomings of the current gold standard, radiography, by allowing for the detection of preclinical disease and subtle early abnormalities prior to the onset of radiographic disease, when damage is still reversible. Current MRI techniques are either morphological (2D/3D qualitative and quantitative techniques) or compositional (matrix-assessment techniques that detect macromolecular changes prior to morphological changes). MRI is evolving as a complete answer to our cartilage-imaging requirements of lesion description, treatment planning, and outcome measurement as well as in various research settings.

Long Intergenic Noncoding RNAs Mediate the Human Chondrocyte Inflammatory Response and Are Differentially Expressed in Osteoarthritis Cartilage

OBJECTIVE

To identify long noncoding RNAs (lncRNAs), including long intergenic noncoding RNAs (lincRNAs), antisense RNAs, and pseudogenes, associated with the inflammatory response in human primary osteoarthritis (OA) chondrocytes and to explore their expression and function in OA.

METHODS

OA cartilage was obtained from patients with hip or knee OA following joint replacement surgery. Non-OA cartilage was obtained from postmortem donors and patients with fracture of the neck of the femur. Primary OA chondrocytes were isolated by collagenase digestion. LncRNA expression analysis was performed by RNA sequencing (RNAseq) and quantitative reverse transcriptase-polymerase chain reaction. Modulation of lncRNA chondrocyte expression was achieved using LNA longRNA GapmeRs (Exiqon). Cytokine production was measured with Luminex.

RESULTS

RNAseq identified 983 lncRNAs in primary human hip OA chondrocytes, 183 of which had not previously been identified. Following interleukin-1β (IL-1β) stimulation, we identified 125 lincRNAs that were differentially expressed. The lincRNA p50-associated cyclooxygenase 2-extragenic RNA (PACER) and 2 novel chondrocyte inflammation-associated lincRNAs (CILinc01 and CILinc02) were differentially expressed in both knee and hip OA cartilage compared to non-OA cartilage. In primary OA chondrocytes, these lincRNAs were rapidly and transiently induced in response to multiple proinflammatory cytokines. Knockdown of CILinc01 and CILinc02 expression in human chondrocytes significantly enhanced the IL-1-stimulated secretion of proinflammatory cytokines.

CONCLUSION

The inflammatory response in human OA chondrocytes is associated with widespread changes in the profile of lncRNAs, including PACER, CILinc01, and CILinc02. Differential expression of CILinc01 and CIinc02 in hip and knee OA cartilage, and their role in modulating cytokine production during the chondrocyte inflammatory response, suggest that they may play an important role in mediating inflammation-driven cartilage degeneration in OA.

Structural effects of sprifermin in knee osteoarthritis: a post-hoc analysis on cartilage and non-cartilaginous tissue alterations in a randomized controlled trial

BACKGROUND

A recent publication on efficacy of Sprifermin for knee osteoarthritis (OA) using quantitatively MRI-defined central medial tibio-femoral compartment cartilage thickness as the structural primary endpoint reported no statistically significant dose response. However, Sprifermin was associated with statistically significant, dose-dependent reductions in loss of total and lateral tibio-femoral cartilage thickness. Based on these preliminary promising data a post-hoc analysis of secondary assessment and endpoints was performed to evaluate potential effects of Sprifermin on semi-quantitatively evaluated structural MRI parameters. Aim of the present analysis was to determine effects of sprifermin on several knee joint tissues over a 12 month period.

METHODS

1.5 T or 3 T MRIs were acquired at baseline and 12 months follow-up using a standard protocol. MRIs were read according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS) scoring system (in 14 articular subregions) by four muskuloskeletal radiologists independently. Analyses focused on semiquantitative changes in the 100 μg subgroup and matching placebo of multiple MRI-defined structural alterations. Analyses included a delta-subregional and delta-sum approach for the whole knee and the medial and lateral tibio-femoral (MTFJ, LTFJ), and patello-femoral (PFJ) compartments, taking into account number of subregions showing no change, improvement or worsening and changes in the sum of subregional scores. Mann-Whitney - Wilcoxon tests assessed differences between groups.

RESULTS

Fifty-seven and 18 patients were included in the treatment and matched placebo subgroups. Less worsening of cartilage damage was observed from baseline to 12 months in the PFJ (0.02, 95 % confidence interval (CI) (-0.04, 0.08) vs. placebo 0.22, 95 % CI (-0.05, 0.49), p = 0.046). For bone marrow lesions (BMLs), more improvement was observed from 6 to 12 months for whole knee analyses (-0.14, 95 % CI (-0.48, 0.19) vs. placebo 0.44, 95 % CI (-0.15, 1.04), p = 0.042) although no significant effects were seen from the baseline visit, or in Hoffa-synovitis, effusion-synovitis, menisci and osteophytes.

CONCLUSIONS

In this post-hoc analysis cartilage showed less worsening from baseline to 12 months in the PFJ, and BMLs showed more improvement from 6 to 12 months for the whole knee.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01033994 .

Comparative pain reduction of oral non-steroidal anti-inflammatory drugs and opioids for knee osteoarthritis: systematic analytic review

OBJECTIVE

Summarize the comparative effectiveness of oral non-steroidal anti-inflammatory drugs (NSAIDs) and opioids in reducing knee osteoarthritis (OA) pain.

METHODS

Two reviewers independently screened reports of randomized controlled trials (RCTs), published in English between 1982 and 2015, evaluating oral NSAIDs or opioids for knee OA. Included studies were at least 8 weeks duration, conducted in Western Europe, the Americas, New Zealand, or Australia, and reported baseline and follow-up pain using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain subscale (0-100, 100-worst). Effectiveness was evaluated as reduction in pain, accounting for study dropout and heterogeneity.

RESULTS

Twenty-seven treatment arms (nine celecoxib, four non-selective NSAIDs [diclofenac, naproxen, piroxicam], eleven less potent opioids [tramadol], and three potent opioids [hydromorphone, oxycodone]) from 17 studies were included. NSAID and opioid studies reported similar baseline demographics and efficacy withdrawal rates; NSAID studies reported lower baseline pain and toxicity withdrawal rates. Accounting for efficacy-related withdrawals, all drug classes were associated with similar pain reductions (NSAIDs: -18; less potent opioids: -18; potent opioids: -19). Meta-regression did not reveal differential effectiveness by drug class but found that study cohorts with a higher proportion of male subjects and worse mean baseline pain had greater pain reduction. Similarly, results of the network meta-analysis did not find a significant difference in WOMAC Pain reduction for the three analgesic classes.

CONCLUSION

NSAIDs and opioids offer similar pain relief in OA patients. These data could help clinicians and patients discuss likely benefits of alternative analgesics.

The natural dual cyclooxygenase and 5-lipoxygenase inhibitor flavocoxid is protective in EAE through effects on Th1/Th17 differentiation and macrophage/microglia activation

Prostaglandins and leukotrienes, bioactive mediators generated by cyclooxygenases (COX) and 5-lipoxygenase (5-LO) from arachidonic acid, play an essential role in neuroinflammation. High levels of LTB4 and PGE2 and increased expression of COX and 5-LO, as well as high expression of PGE2 receptors were reported in multiple sclerosis (MS) patients and in experimental autoimmune encephalomyelitis (EAE). Prostaglandins and leukotrienes have an interdependent and compensatory role in EAE, which led to the concept of therapy using dual COX/5-LO inhibitors. The plant derived flavocoxid, a dual COX/5-LO inhibitor with anti-inflammatory and antioxidant properties, manufactured as a prescription pharmaconutrient, was reported to be neuroprotective in models of transient ischemic stroke and brain injury. The present study is the first report on prophylactic and therapeutic effects of flavocoxid in EAE. The beneficial effects correlate with reduced expression of proinflammatory cytokines and of COX2 and 5-LO in spinal cords and spleens of EAE mice. The protective mechanisms include: 1. reduction in expression of MHCII/costimulatory molecules and production of proinflammatory cytokines; 2. promotion of the M2 phenotype including IL-10 expression and release by macrophages and microglia; 3. inhibition of Th1 and Th17 differentiation through direct effects on T cells. The direct inhibitory effect on Th1/Th17 differentiation, and promoting the development of M2 macrophages and microglia, represent novel mechanisms for the flavocoxid anti-inflammatory activity. As a dual COX/5-LO inhibitor with antioxidant properties, flavocoxid might be useful as a potential therapeutic medical food agent in MS patients.