Efficacy of tocilizumab in patients with hand osteoarthritis: double blind, randomised, placebo-controlled, multicentre trial

Repurposing drugs for the treatment of osteoarthritis

OBJECTIVE

Currently, no disease-modifying therapies for osteoarthritis (OA) exist, and attempts to identify novel cellular targets have been challenging. Risk factors for OA include advanced age, obesity, and metabolic syndrome. This creates an attractive opportunity to repurpose existing drugs that are used to treat comorbidities commonly encountered in patients with OA, if those drugs possess OA disease modifying properties.

METHODS

This narrative review incorporates findings from knee or hand OA randomized clinical trials, post-hoc clinical trial analyses, prospective cohort studies, and observational data.

RESULTS

Drugs used for the treatment of rheumatoid arthritis (methotrexate; TNFa, IL-1, and IL-6 pathway inhibitors; hydroxychloroquine), atopic/allergic disease (anti-histamines), osteoporosis (bisphosphonates and vitamin D), type 2 diabetes (metformin and GLP-1 agonists), and cardiovascular disease (atorvastatin, fish oil, and beta blockers) were reviewed for their potential benefit in OA. This review outlines the successful attributes of repurposed drugs, the challenges in repurposing drugs, and strategies for future clinical trials to support OA drug repurposing. Potential drug candidates for OA may be identified through the use of existing datasets and via collaborations with researchers in other fields to include OA endpoints in future clinical trials.

CONCLUSION

Given the association of OA with several commonly treated comorbidities, drug repurposing is an appealing approach that could provide a favorable benefit-to-risk ratio for chronic OA treatment.

Systematic review and network meta-analysis on the efficacy and safety of parmacotherapy for hand osteoarthritis

OBJECTIVE

Hand osteoarthritis poses a significant health challenge globally due to its increasing prevalence and the substantial burden on individuals and the society. In current clinical practice, treatment options for hand osteoarthritis encompass a range of approaches, including biological agents, antimetabolic drugs, neuromuscular blockers, anti-inflammatory drugs, hormone medications, pain relievers, new synergistic drugs, and other medications. Despite the diverse array of treatments, determining the optimal regimen remains elusive. This study seeks to conduct a network meta-analysis to assess the effectiveness and safety of various drug intervention measures in the treatment of hand osteoarthritis. The findings aim to provide evidence-based support for the clinical management of hand osteoarthritis.

METHODS

We performed a comprehensive search across PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials was conducted until September 15th, 2022, to identify relevant randomized controlled trials. After meticulous screening and data extraction, the Cochrane Handbook's risk of bias assessment tool was applied to evaluate study quality. Data synthesis was carried out using Stata 15.1 software.

RESULTS

21 studies with data for 3965 patients were meta-analyzed, involving 20 distinct Western medicine agents. GCSB-5, a specific herbal complex that mainly regulate pain in hand osteoarthritis, showed the greatest reduction in pain [WMD = -13.00, 95% CI (-26.69, 0.69)]. CRx-102, s specific medication characterized by its significant effect for relieving joint stiffness symptoms, remarkably mitigated stiffness [WMD = -7.50, 95% CI (-8.90, -6.10)]. Chondroitin sulfate displayed the highest incidence of adverse events [RR = 0.26, 95% CI (0.06, 1.22)]. No substantial variation in functional index for hand osteoarthritis score improvement was identified between distinct agents and placebo.

CONCLUSIONS

In summary, GCSB-5 and CRx-102 exhibit efficacy in alleviating pain and stiffness in HOA, respectively. However, cautious interpretation of the results is advised. Tailored treatment decisions based on individual contexts are imperative.

Importance of IL-6 trans-signaling and high autocrine IL-6 production in human osteoarthritic chondrocyte metabolism

OBJECTIVE

Neutralization of Interleukin (IL)-6-signaling by antibodies is considered a promising tool for the treatment of osteoarthritis (OA). To gain further insight into this potential treatment, this study investigated the effects of IL-6-signaling and IL-6 neutralization on chondrocyte metabolism and the release of IL-6-signaling-related mediators by human chondrocytes.

DESIGN

Chondrocytes were collected from 49 patients with advanced knee/hip OA or femoral neck fracture. Isolated chondrocytes were stimulated with different mediators to analyze the release of IL-6, soluble IL-6 receptor (sIL-6R) and soluble gp130 (sgp130). The effect of IL-6 and IL-6/sIL-6R complex as well as neutralization of IL-6-signaling on the metabolism was analyzed.

RESULTS

OA chondrocytes showed high basal IL-6 production and release, which was strongly negatively correlated with the production of cartilage-matrix-proteins. Chondrocytes produced and released sIL-6R and sgp130. The IL-6/sIL-6R complex significantly increased nitric oxide, prostaglandin E2 and matrix metalloproteinase 1 production, decreased Pro-Collagen Type II and mitochondrial ATP production, and increased glycolysis in OA chondrocytes. Neutralization of IL-6-signaling by antibodies did not significantly affect the metabolism of OA chondrocytes, but blocking of glycoprotein 130 (gp130)-signaling by SC144 significantly reduced the basal IL-6 release.

CONCLUSION

Although IL-6 trans-signaling induced by IL-6/sIL-6R complex negatively affects OA chondrocytes, antibodies against IL-6 or IL-6R did not affect chondrocyte metabolism. Since inhibition of gp130-signaling reduced the enhanced basal release of IL-6, interfering with gp130-signaling may ameliorate OA progression because high cellular release of IL-6 correlates with reduced production of cartilage-matrix-proteins.

Intra-Articular Injection of Interleukin-8 Neutralizing Monoclonal Antibody Effectively Attenuates Osteoarthritis Progression in Rabbits

OBJECTIVE

Cytokines are implicated in the pathogenesis of osteoarthritis (OA), and this study aims to assess the therapeutic potential of an IL-8 neutralizing monoclonal antibody (mAb) for OA intervention.

DESIGN

The study employed a rabbit model of OA induced by anterior cruciate ligament transection (ACLT) surgery to investigate the effects of an interleukin (IL)-8 neutralizing mAb, with hyaluronic acid (HA) used as a positive control. Primary outcomes assessed in the rabbits included cartilage repair, synovitis, joint effusion, changes in footprints, and lower limb loading conditions.

RESULTS

Compared to HA, intra-articular injection of the IL-8 neutralizing mAb demonstrated a more pronounced attenuation of OA progression and enhancement of cartilage repair. We observed a reduction in synovitis and joint effusion, indications of bone marrow edema, as well as improvements in lower limb function. In knees treated with the neutralizing IL-8 mAb, there was a significant decrease in IL-8 levels within the synovial tissues.

CONCLUSIONS

The IL-8 neutralizing mAb exhibits promising therapeutic potential in the management of OA by attenuating inflammation and facilitating cartilage repair. However, further investigations are warranted to comprehensively elucidate the underlying mechanisms, optimize treatment protocols, and ensure the long-term safety and efficacy of this innovative therapeutic approach.

Molecular mechanisms of pain in acute pancreatitis: recent basic research advances and therapeutic implications

Although severe abdominal pain is the main symptom of acute pancreatitis, its mechanisms are poorly understood. An emerging body of literature evidence indicates that neurogenic inflammation might play a major role in modulating the perception of pain from the pancreas. Neurogenic inflammation is the result of a crosstalk between injured pancreatic tissue and activated neurons, which leads to an auto-amplification loop between inflammation and pain during the progression of acute pancreatitis. In this review, we summarize recent findings on the role of neuropeptides, ion channels, and the endocannabinoid system in acute pancreatitis-related pain. We also highlight potential therapeutic strategies that could be applied for managing severe pain in this disease.

Hand osteoarthritis: A fresh look

Hand osteoarthritis (OA) has been the subject of numerous publications in recent years, particularly in the fields of imaging and therapeutics. The imaging studies revealed a good correlation between the presence of synovitis and/or subchondral edema and arthritic joint pain. Several randomized controlled trials (RCTs) have assessed the efficacy of biologics and conventional DMARDs in patients with symptomatic hand OA. No less than six RCTs have evaluated the symptomatic and, in some cases, structural efficacy of anti-IL-1, anti-TNF or anti-IL-6 drugs. Overall, the results of these trials were disappointing - none of them demonstrated superiority over placebo. There were also two negative trials with hydroxychloroquine. In the end, the only trial that was positive evaluated 10mg oral prednisone versus placebo for 6 weeks in patients with flares of hand OA and synovitis visible on ultrasound. While that trial confirms the role of inflammation in hand OA, it should obviously not encourage the long-term use of corticosteroids as a symptomatic treatment.

Arthritic Microenvironment-Dictated Fate Decisions for Stem Cells in Cartilage Repair

The microenvironment and stem cell fate guidance of post-traumatic articular cartilage regeneration is primarily the focus of cartilage tissue engineering. In articular cartilage, stem cells are characterized by overlapping lineages and uneven effectiveness. Within the first 12 weeks after trauma, the articular inflammatory microenvironment (AIME) plays a decisive role in determining the fate of stem cells and cartilage. The development of fibrocartilage and osteophyte hyperplasia is an adverse outcome of chronic inflammation, which results from an imbalance in the AIME during the cartilage tissue repair process. In this review, the sources for the different types of stem cells and their fate are summarized. The main pathophysiological events that occur within the AIME as well as their protagonists are also discussed. Additionally, regulatory strategies that may guide the fate of stem cells within the AIME are proposed. Finally, strategies that provide insight into AIME pathophysiology are discussed and the design of new materials that match the post-traumatic progress of AIME pathophysiology in a spatial and temporal manner is guided. Thus, by regulating an appropriately modified inflammatory microenvironment, efficient stem cell-mediated tissue repair may be achieved.

The Role of Genetics and Epigenetic Regulation in the Pathogenesis of Osteoarthritis

Osteoarthritis (OA) is progressive disease characterised by cartilage degradation, subchondral bone remodelling and inflammation of the synovium. The disease is associated with obesity, mechanical load and age. However, multiple pro-inflammatory immune mediators regulate the expression of metalloproteinases, which take part in cartilage degradation. Furthermore, genetic factors also contribute to OA susceptibility. Recent studies have highlighted that epigenetic mechanisms may regulate the expression of OA-associated genes. This review aims to present the mechanisms of OA pathogenesis and summarise current evidence regarding the role of genetics and epigenetics in this process.

Osteoarthritic chondrocytes undergo a glycolysis-related metabolic switch upon exposure to IL-1b or TNF

BACKGROUND

Osteoarthritis is an age-related disease that currently faces a lack of symptomatic treatment. Inflammation, which is mainly sustained by pro-inflammatory cytokines such as IL-1b, TNF, and IL-6, plays an important role in osteoarthritis progression. In this context, pro-inflammatory cytokines are widely used to mimic the inflammatory component of osteoarthritis in vitro. However, the therapeutic failures of clinical trials evaluating anti-cytokines drugs highlight the lack of overall understanding of the effects of these cytokines on chondrocytes.

METHODS

Here, we generated a comprehensive transcriptomic and proteomic dataset of osteoarthritic chondrocytes treated with these cytokines to describe their pro-inflammatory signature and compare it to the transcriptome of non-osteoarthritic chondrocytes. Then, the dysregulations highlighted at the molecular level were functionally confirmed by real-time cellular metabolic assays.

RESULTS

We identified dysregulation of metabolic-related genes in osteoarthritic chondrocytes but not in non-osteoarthritic chondrocytes. A metabolic shift, toward increased glycolysis at the expense of mitochondrial respiration, was specifically confirmed in osteoarthritic chondrocytes treated with IL-1b or TNF.

CONCLUSION

These data show a strong and specific association between inflammation and metabolism in osteoarthritic chondrocytes, which was not found in non-osteoarthritic chondrocytes. This indicates that the link between inflammation and metabolic dysregulation may be exacerbated during chondrocyte damage in osteoarthritis. Video Abstract.

What is new in pharmacological treatment for osteoarthritis?

Osteoarthritis (OA) is a degenerative joint disease in which structural changes of hyaline articular cartilage, subchondral bone, ligaments, capsule, synovium, muscles, and periarticular changes are involved. The knee is the most commonly affected joint, followed by the hand, hip, spine, and feet. Different pathological mechanisms are at play in each of these various involvement sites. Although systemic inflammation is more prominent in hand OA, knee and hip OA have been associated with excessive joint load and injury. As OA has varied phenotypes and the primarily affected tissues differ, treatment options must be tailored accordingly. In recent years, ongoing efforts have been made to develop disease-modifying options that halt or slow disease progression. Many are still in clinical trials, and as insights into the pathogenesis of OA evolve, novel therapeutic strategies will be developed. In this chapter, we provide an overview of the novel and emerging strategies in the management of OA.

Mechanisms of Peripheral and Central Sensitization in Osteoarthritis Pain

Pain, the primary symptom of osteoarthritis (OA), reduces both the quality and quantity of life for patients. The pathophysiology of OA pain is complex and often difficult to explain solely by radiological structural changes. One reason for this discrepancy is pain sensitization (peripheral sensitization [PS] and central sensitization [CS]) in OA. Thus, an understanding of pain sensitization is important when considering treatment strategies and development for OA pain. In recent years, pro-inflammatory cytokines, nerve growth factors (NGFs), and serotonin have been identified as causative agents that induce peripheral and central sensitization and are becoming therapeutic targets for OA pain. However, the characteristics of the clinical manifestations of pain sensitization elicited by these molecules remain unclear, and it is not well understood who among OA patients should receive the therapeutic intervention. Thus, this review summarizes evidence on the pathophysiology of peripheral and central sensitization in OA pain and the clinical features and treatment options for this condition. While the majority of the literature supports the existence of pain sensitization in chronic OA pain, clinical identification and treatment of pain sensitization in OA are still in their infancy, and future studies with good methodological quality are needed.

Cartilage calcification in osteoarthritis: mechanisms and clinical relevance

Pathological calcification of cartilage is a hallmark of osteoarthritis (OA). Calcification can be observed both at the cartilage surface and in its deeper layers. The formation of calcium-containing crystals, typically basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPP) crystals, is an active, highly regulated and complex biological process that is initiated by chondrocytes and modified by genetic factors, dysregulated mitophagy or apoptosis, inflammation and the activation of specific cellular-signalling pathways. The links between OA and BCP deposition are stronger than those observed between OA and CPP deposition. Here, we review the molecular processes involved in cartilage calcification in OA and summarize the effects of calcium crystals on chondrocytes, synovial fibroblasts, macrophages and bone cells. Finally, we highlight therapeutic pathways leading to decreased joint calcification and potential new drugs that could treat not only OA but also other diseases associated with pathological calcification.

An update on the use of conventional and biological disease-modifying anti-rheumatic drugs in hand osteoarthritis

Osteoarthritis (OA) is a highly prevalent condition worldwide associated with pain, progressive disability, reduced participation in social activities, and impaired quality of life. Despite its growing burden, the therapeutic options are still limited and almost exclusively addressed to symptoms' management, while no disease-modifying OA drugs able to prevent or retard disease progression are actually available. For these reasons, in the last decades, relevant efforts to find new potential therapeutic targets in OA have been made and a number of existing conventional and biological disease-modifying anti-rheumatic drugs (DMARDs), including hydroxychloroquine (HCQ), methotrexate (MTX), tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6 inhibitors, commonly used to treat inflammatory rheumatic diseases, have been repurposed for the treatment of OA and explored also in hand osteoarthritis (HOA). The current narrative review was aimed to provide a comprehensive and updated understanding of the possibilities and the criticisms related to the treatment of HOA with conventional and biological DMARDs. Unfortunately, therapy with conventional and biologic drugs in HOA has not achieved the expected success, despite a rationale for their use exists. Thus, our findings outline the urgent need to enhance the exploration of HOA basic molecular mechanisms to find new potential therapeutic targets, personalized for each patient, and appropriate for the different subsets of HOA and for the different phases of disease.

Osteoarthritis of hand joints: prevalence, risk factors, phenotypes, diagnosis, treatment

Osteoarthritis is the most common rheumatic disease, accompanied by constant pain and dysfunction of the joints, the progression of which leads to a deterioration in the quality of life and often to disability of patients. The article presents the prevalence, predictors of development and progression of osteoarthritis of the hand joints (OHJ). Clinical classification of OHJ, clinical picture depending on the localization of the process, topical features of involvement of the hand joints in different types of OHJ are given. Clinical, laboratory and instrumental methods for diagnosing of the disease, classification and diagnostic criteria are described, much attention is paid to modern principles of OHJ therapy in accordance with Russian clinical guidelines, as well as EULAR and ACR recommendations.

Age-related mechanisms in the context of rheumatic disease

Ageing is characterized by a progressive loss of cellular function that leads to a decline in tissue homeostasis, increased vulnerability and adverse health outcomes. Important advances in ageing research have now identified a set of nine candidate hallmarks that are generally considered to contribute to the ageing process and that together determine the ageing phenotype, which is the clinical manifestation of age-related dysfunction in chronic diseases. Although most rheumatic diseases are not yet considered to be age related, available evidence increasingly emphasizes the prevalence of ageing hallmarks in these chronic diseases. On the basis of the current evidence relating to the molecular and cellular ageing pathways involved in rheumatic diseases, we propose that these diseases share a number of features that are observed in ageing, and that they can therefore be considered to be diseases of premature or accelerated ageing. Although more data are needed to clarify whether accelerated ageing drives the development of rheumatic diseases or whether it results from the chronic inflammatory environment, central components of age-related pathways are currently being targeted in clinical trials and may provide a new avenue of therapeutic intervention for patients with rheumatic diseases.

Effect of disease-modifying anti-rheumatic drugs in osteoarthritis: A meta-analysis

OBJECTIVE

Osteoarthritis (OA) displays features of systemic and local inflammation, suggesting that DMARDs used in rheumatoid arthritis could potentially also be effective in OA. However, studies of the effects of DMARDs in OA have yielded conflicting data, and have been insufficiently large to draw conclusions. In this meta-analysis, we aimed to estimate the effect of DMARDs - such as methotrexate, hydroxychloroquine, TNF, and IL-1 inhibitors - on OA.

METHODS

We searched for relevant articles of randomized controlled trials published up to March 2022, using Pubmed, EMBASE, and the Cochrane Library. Studies were reviewed in accordance with PRISMA 2020 guidelines. The effects of DMARDs on OA outcomes (symptoms, quality of life, ESR) were expressed as the standardized mean difference.

RESULTS

We retrieved 29 references. Among these, 23 randomized controlled trials compared the effects of DMARDs versus placebo or other treatments on disease activity, including 1143 DMARD-treated OA patients and 1155 OA patients in the control group. We found statistically significant improvement of pain and stiffness with methotrexate, especially in knee OA. TNF inhibitors improved the swollen joint count in hand OA, and inflammation parameters, without change in pain, stiffness, or function. Hydroxychloroquine and IL-1 inhibitors were not effective.

CONCLUSION

Overall, the presently available data regarding the effects of DMARDs on OA symptoms intensity are disappointing. Only methotrexate might have an analgesic effect, especially in knee OA, which warrants further investigation.

Management of hand osteoarthritis: from an US evidence-based medicine guideline to a European patient-centric approach

Hand osteoarthritis is the most common joint condition and is associated with significant morbidity. It is of paramount importance that patients are thoroughly assessed and examined when complaining of hand stiffness, pain, deformity or disability and that the patient's concerns and expectations are addressed by the healthcare professional. In 2019 the American College of Rheumatology and Arthritis Foundation (ACR/AF) produced guidelines which included recommendations for the treatment of hand osteoarthritis. An ESCEO expert working group (including patients) was convened and composed this paper with the aim to assess whether these guidelines were appropriate for the treatment of hand osteoarthritis therapy in Europe and whether they met with the ESCEO patient-centered approach. Indeed, patients are the key stakeholders in healthcare and eliciting the patient's preference is vital in the context of an individual consultation but also for informing research and policy-making. The patients involved in this working group emphasised the often-neglected area of aesthetic changes in hand osteoarthritis, importance of developing pharmacological therapies which can alleviate pain and disability and the need of the freedom to choose which approach (out of pharmacological, surgical or non-pharmacological) they wished to pursue. Following robust appraisal, it was recommended that the ACR/AF guidelines were suitable for a European context (as described within the body of the manuscript) and it was emphasised that patient preferences are key to the success of individual consultations, future research and future policy-making.

A systematic literature review informing the consensus statement on efficacy and safety of pharmacological treatment with interleukin-6 pathway inhibition with biological DMARDs in immune-mediated inflammatory diseases

Objectives

Informing an international task force updating the consensus statement on efficacy and safety of biological disease-modifying antirheumatic drugs (bDMARDs) selectively targeting interleukin-6 (IL-6) pathway in the context of immune-mediated inflammatory diseases.

Methods

A systematic literature research of all publications on IL-6 axis inhibition with bDMARDs published between January 2012 and December 2020 was performed using MEDLINE, EMBASE and Cochrane CENTRAL databases. Efficacy and safety outcomes were assessed in clinical trials including their long-term extensions and observational studies. Meeting abstracts from ACR, EULAR conferences and results on clinicaltrials.gov were taken into consideration.

Results

187 articles fulfilled the inclusion criteria. Evidence for positive effect of IL-6 inhibition was available in various inflammatory diseases such as rheumatoid arthritis, juvenile idiopathic arthritis, giant cell arteritis, Takayasu arteritis, adult-onset Still’s disease, cytokine release syndrome due to chimeric antigen receptor T cell therapy and systemic sclerosis-associated interstitial lung disease. Newcomers like satralizumab and anti-IL-6 ligand antibody siltuximab have expanded therapeutic approaches for Castleman’s disease and neuromyelitis optica, respectively. IL-6 inhibition did not provide therapeutic benefits in psoriatic arthritis, ankylosing spondylitis and certain connective tissue diseases. In COVID-19, tocilizumab (TCZ) has proven to be therapeutic in advanced disease. Safety outcomes did not differ from other bDMARDs, except higher risks of diverticulitis and lower gastrointestinal perforations. Inconsistent results were observed in several studies investigating the risk for infections when comparing TCZ to TNF-inhibitors.

Conclusion

IL-6 inhibition is effective for treatment of several inflammatory diseases with a safety profile that is widely comparable to other bDMARDs.

Emerging injectable therapies for osteoarthritis

Osteoarthritis (OA) affects more than 240 million people worldwide. In 2016, the Osteoarthritis Research Society International submitted a report to the United States Food and Drug Administration highlighting OA as a 'serious' disease, and appealed for the urgent development and review of new therapies to address a significant unmet need. Despite this, international guidelines for the treatment of OA have been largely unchanged for over a decade. There is now an updated understanding that OA is more than simply a non-inflammatory 'wear-and-tear' process involving articular cartilage. Based on this, potential emerging therapies are being developed that target novel inflammatory, pain, and regeneration pathways. Drugs targeting the latter are being lauded as 'Disease-Modifying Osteoarthritis Drugs' - a concept which has so far proved elusive in OA research. While this review does not recommend a change in current practice, it should prompt readers to rethink the OA treatment paradigm. The global pandemic has added another layer of consideration when managing patients with OA. At a time when there is more strain on hospital systems, there is a need to expand our pharmacological armamentarium in order to manage OA without elective surgery and hospital admission.

Interleukin-6 signaling mediates cartilage degradation and pain in posttraumatic osteoarthritis in a sex-specific manner

Osteoarthritis (OA) and posttraumatic OA (PTOA) are caused by an imbalance in catabolic and anabolic processes in articular cartilage and proinflammatory changes throughout the joint, leading to joint degeneration and pain. We examined whether interleukin-6 (IL-6) signaling contributed to cartilage degradation and pain in PTOA. Genetic ablation of Il6 in male mice decreased PTOA-associated cartilage catabolism, innervation of the knee joint, and nociceptive signaling without improving PTOA-associated subchondral bone sclerosis or chondrocyte apoptosis. These effects were not observed in female Il6^-/- mice. Compared with wild-type mice, the activation of the IL-6 downstream mediators STAT3 and ERK was reduced in the knees and dorsal root ganglia (DRG) of male Il6^-/- mice after knee injury. Janus kinases (JAKs) were critical for STAT and ERK signaling in cartilage catabolism and DRG pain signaling in tissue explants. Whereas STAT3 signaling was important for cartilage catabolism, ERK signaling mediated neurite outgrowth and the activation of nociceptive neurons. These data demonstrate that IL-6 mediates both cartilage degradation and pain associated with PTOA in a sex-specific manner and identify tissue-specific contributions of downstream effectors of IL-6 signaling, which are potential therapeutic targets for disease-modifying OA drugs.

Relative Efficacy and Safety of Anti-Inflammatory Biologic Agents for Osteoarthritis: A Conventional and Network Meta-Analysis

Previous studies have consistently revealed that both local and systemic inflammations are the key to the onset and progression of osteoarthritis (OA). Thus, anti-inflammatory biologic agents could potentially attenuate the progression of OA. We conducted this meta-analysis to examine the efficacy and safety of ant-inflammatory biologic agents among OA patients. Methods: Five databases were searched for randomized controlled trials (RCTs) comparing biologics with placebo or each other in OA patients. Data of pain, physical function, stiffness, and adverse events (AEs) were extracted for a conventional and a Bayesian network meta-analysis. Results: 15 studies with data for 1566 patients were analyzed. In the conventional meta-analysis, etanercept (SMD −0.47; 95% CI −0.89, −0.05) and infliximab (SMD −2.04; CI −2.56, −1.52) were superior to placebo for knee pain. In the network meta-analysis, infliximab was superior to all the other biologic agents in improving pain (vs. hyaluronic acid (SMD −22.95; CI −34.21, −10.43), vs. adalimumab (SMD −21.71; CI −32.65, −11.00), vs. anakinra (SMD −24.63; CI −38.79, −10.05), vs. canakinumab (SMD −32.83; CI −44.45, −20.68), vs. etanercept (SMD −18.40; CI −29.93, −5.73), vs. lutikizumab (SMD −25.11; CI −36.47, −14.78), vs. naproxen (SMD −30.16; CI −41.78, −17.38), vs. tocilizumab (SMD −24.02; CI −35.63, −11.86) and vs. placebo (SMD −25.88; CI −34.87, −16.60)). No significant differences were observed between biologics and placebo regarding physical function, stiffness, and risk of AEs. Conclusions: The findings suggest that infliximab may relieve pain more than other biological agents in OA patients. No significant differences were observed between biologics and placebo regarding physical function, stiffness, and risk of AEs. The results must be interpreted cautiously; therefore, further randomized controlled trials are warranted.

Prescription-grade crystalline glucosamine sulfate as an add-on therapy to conventional treatments in erosive osteoarthritis of the hand: results from a 6-month observational retrospective study

Objective

To evaluate the efficacy of prescription-grade Crystalline Glucosamine Sulfate (pCGS) as an add-on treatment to conventional therapy, compared to usual therapy alone, in patients with erosive osteoarthritis of the hand (EHOA).

Methods

This 6-month retrospective case–control study included patients with concomitant knee osteoarthritis and symptomatic EHOA. Participants were stratified into two groups based on whether or not pCGS (1500 mg/day) was added to the conventional therapy (education and training in ergonomic principles, exercise and use on-demand of symptomatic drugs) for hand osteoarthritis. Patients were evaluated at baseline, after 3 and 6 months. Primary outcomes were the change from baseline to month 6 in Visual Analogue Scale (VAS) hand pain and in Functional Index for Hand Osteoarthritis (FIHOA) score. A set of secondary parameters was also evaluated.

Results

123 patients were included as follows: 67 treated with pCGS in addition to conventional therapy (pCGS Group) and 56 with conventional therapy alone (Control Group). After 6 months a significant difference in VAS and in FIHOA score (p < 0.01 and p < 0.001, respectively) was observed in favor of pCGS Group. Similar results were found for morning stiffness duration (p < 0.05), health assessment questionnaire (p < 0.01) and physical and mental component score of 36-item short form (p < 0.05 and p < 0.001, respectively). A significant reduction of symptomatic drug consumption at 3 and 6 months was reported in the pCGS Group (p < 0.001). No serious adverse event was recorded in both groups.

Conclusions

Despite all the limitations inherent to an observational study, our results suggest the potential effectiveness of pCGS, when used in combination with conventional therapy in EHOA. Further randomized placebo-controlled trials are needed to confirm these positive findings.

Trial Registration

ClinicalTrials.gov, http://www.clinicaltrials.gov, date of registration: February 2, 2022, NCT05237596. The present trial was retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40520-022-02151-7.

Repurposed and investigational disease-modifying drugs in osteoarthritis (DMOADs)

In spite of a major public health burden with increasing prevalence, current osteoarthritis (OA) management is largely palliative with an unmet need for effective treatment. Both industry and academic researchers have invested a vast amount of time and financial expense to discover the first diseasing-modifying osteoarthritis drugs (DMOADs), with no regulatory success so far. In this narrative review, we discuss repurposed drugs as well as investigational agents which have progressed into phase II and III clinical trials based on three principal endotypes: bone-driven, synovitis-driven and cartilage-driven. Then, we will briefly describe the recent failures and lessons learned, promising findings from predefined post hoc analyses and insights gained, novel methodologies to enhance future success and steps underway to overcome regulatory hurdles.

The Role of Interleukin-4 and Interleukin-10 in Osteoarthritic Joint Disease: A Systematic Narrative Review

OBJECTIVE

A fusion protein of interleukin-4 and interleukin-10 (IL4-10 FP) was developed as a disease-modifying osteoarthritis drug (DMOAD), and chondroprotection, anti-inflammation, and analgesia have been suggested. To better understand the mechanisms behind its potential as DMOAD, this systematic narrative review aims to assess the potential of IL-4, IL-10 and the combination of IL-4 and IL-10 for the treatment of osteoarthritis. It describes the chondroprotective, anti-inflammatory, and analgesic effects of IL-4, IL-10, and IL4-10 FP.

DESIGN

PubMed and Embase were searched for publications that were published from 1990 until May 21, 2021 (moment of search). Key search terms were: Osteoarthritis, Interleukin-4, and Interleukin-10. This yielded 2,479 hits, of which 43 were included in this review.

RESULTS

IL-4 and IL-10 showed mainly protective effects on osteoarthritic cartilage in vitro and in vivo, as did IL4-10 FP. Both cytokines showed anti-inflammatory effects, but also proinflammatory effects. Only in vitro IL4-10 FP showed purely anti-inflammatory effects, indicating that proinflammatory effects of one cytokine can be counteracted by the other when given as a combination. Only a few studies investigated the analgesic effects of IL-4, IL-10 or IL4-10 FP. In vitro, IL-4 and IL4-10 FP were able to decrease pain mediators. In vivo, IL-4, IL-10, and IL4-10 FP were able to reduce pain.

CONCLUSIONS

In conclusion, this review describes overlapping, but also different modes of action for the DMOAD effects of IL-4 and IL-10, giving an explanation for the synergistic effects found when applied as combination, as is the case for IL4-10 FP.

Synovial inflammation in osteoarthritis progression

Osteoarthritis (OA) is a progressive degenerative disease resulting in joint deterioration. Synovial inflammation is present in the OA joint and has been associated with radiographic and pain progression. Several OA risk factors, including ageing, obesity, trauma and mechanical loading, play a role in OA pathogenesis, likely by modifying synovial biology. In addition, other factors, such as mitochondrial dysfunction, damage-associated molecular patterns, cytokines, metabolites and crystals in the synovium, activate synovial cells and mediate synovial inflammation. An understanding of the activated pathways that are involved in OA-related synovial inflammation could form the basis for the stratification of patients and the development of novel therapeutics. This Review focuses on the biology of the OA synovium, how the cells residing in or recruited to the synovium interact with each other, how they become activated, how they contribute to OA progression and their interplay with other joint structures.

Targeting cellular senescence as a novel treatment for osteoarthritis

Cellular senescence is associated with normal development and wound healing, but has also been implicated in the pathogenesis of numerous aging-related diseases including osteoarthritis (OA). Treatment strategies for OA are being developed that target senescent cells and the paracrine and autocrine secretions of the senescence-associated secretory phenotype (SASP). The field of potential therapies continues to expand as new mechanistic targets of cell senescence and the SASP are identified. Ongoing pre-clinical and clinical studies of drugs targeting cellular senescence yield significant promise, but have yet to demonstrate long-term efficacy. Therapeutic targeting of senescence is challenged by the diverse phenotypes of senescent cells, which can vary depending on age, species, tissue source, and type of physiologic stressor. Accordingly, there remains considerable demand for more studies to further develop and assess senotherapeutics as disease-modifying treatments for OA.

Efficacy and safety of biologic agents for the treatment of osteoarthritis: a meta-analysis of randomized placebo-controlled trials

Background:

We aimed to evaluate the efficacy and safety of biologic agents targeting three main cytokines, that is, nerve growth factor (NGF), interleukin-1 (IL-1), and tumor necrosis factor-α (TNF-α), for osteoarthritis (OA) treatment.

Methods:

Databases (PubMed, Embase, and Cochrane Library) and ClinicalTrials.gov were systematically searched for randomized placebo-controlled trials (RCTs) of biologic agents from inception to November 15, 2020. The outcomes were the mean change in pain, function scores, and the risk of adverse effects (AEs).

Results:

Out of the 28 studies with 29 RCTs (8555 individuals) included, biologic agents were superior to placebo in pain relief (standardized mean difference [SMD] = 0.28, 95% confidence interval [CI] = 0.17–0.38, p < 0.001) and function improvement (SMD = 0.30, 95% CI = 0.18–0.43, p < 0.001). The incidence of any AEs (risk ratio [RR] = 1.09, 95% CI = 1.05–1.14, p < 0.001) and discontinuations due to AEs (RR = 1.39, 95% CI = 1.05–1.83, p = 0.021) were higher following treatment with biologic agents while no significant difference was found in serious AEs. Subgroup analyses showed that NGF inhibitors provided superior pain relief (SMD = 0.36, 95% CI = 0.26–0.47, p < 0.001) and function improvement (SMD = 0.41, 95% CI = 0.30–0.51, p < 0.001), whereas IL-1 inhibitors and TNF-α inhibitors did not. Meanwhile, NGF inhibitors increased the incidence of any AEs (RR = 1.12, 95% CI = 1.07–1.17, p < 0.001) and discontinuations due to AEs (RR = 1.48, 95% CI = 1.07–2.06, p = 0.018). IL-1 inhibitors and TNF-α inhibitors showed no difference in safety compared with placebo.

Conclusions:

The efficacy and safety of biologic agents vary by mechanism of action. NGF inhibitors can relieve OA-related pain and improve function but involve safety concerns. IL-1 inhibitors and TNF-α inhibitors are relatively safe options but with limited efficacy.

Drug Repurposing to Target Neuroinflammation and Sensory Neuron-Dependent Pain

Around 20% of the American population have chronic pain and estimates in other Western countries report similar numbers. This represents a major challenge for global health care systems. Additional problems for the treatment of chronic and persistent pain are the comparably low efficacy of existing therapies, the failure to translate effects observed in preclinical pain models to human patients and related setbacks in clinical trials from previous attempts to develop novel analgesics. Drug repurposing offers an alternative approach to identify novel analgesics as it can bypass various steps of classical drug development. In recent years, several approved drugs were attributed analgesic properties. Here, we review available data and discuss recent findings suggesting that the approved drugs minocycline, fingolimod, pioglitazone, nilotinib, telmisartan, and others, which were originally developed for the treatment of different pathologies, can have analgesic, antihyperalgesic, or neuroprotective effects in preclinical and clinical models of inflammatory or neuropathic pain. For our analysis, we subdivide the drugs into substances that can target neuroinflammation or substances that can act on peripheral sensory neurons, and highlight the proposed mechanisms. Finally, we discuss the merits and challenges of drug repurposing for the development of novel analgesics.

Effect of Transcutaneous Vagus Nerve Stimulation in Erosive Hand Osteoarthritis: Results from a Pilot Trial

Beyond its effect on vegetative functions, the activation of the vagus nerve inhibits inflammation and reduces pain signaling. The aim of this open-label pilot study was to determine the efficacy and tolerance of transcutaneous auricular VNS (taVNS) on erosive hand osteoarthritis (EHOA) symptoms. Symptomatic EHOA patients with hand pain VAS ≥ 40/100 mm and ≥1 interphalangeal swollen joint(s) were included. The taVNS was performed for 4 weeks using an auricular electrode applied one hour per day and connected to a TENS device with pre-established settings. Clinical efficacy was evaluated by changes between baseline and at 4 weeks with hand pain VAS and the functional index FIHOA score, using a Wilcoxon t-test. The treatment tolerance was also evaluated. Eighteen patients (median age 69 years old, 83% women) were analyzed. At baseline, hand pain VAS was 60 mm [IQR 50; 78.2] and FIHOA 15 [10.7; 20.2]. After 4 weeks, taVNS significantly reduced hand pain VAS, with a median decrease of 23.5 mm [7.7; 37.2] (p = 0.001), as well as FIHOA, with a median decrease of 2 points [0.75; 5.2] (p = 0.01). No serious adverse events were reported. One patient stopped taVNS because of auricular discomfort. This first proof-of-concept trial indicated that taVNS is feasible and may decrease joint inflammation and clinical symptoms in EHOA, arguing for a randomized controlled study versus sham stimulation.

Erosive Hand OsteoArthritis (EHOA): analysis of consecutive patients presenting with EHOA in a hospital-based rheumatology practice and its implications for an upcoming interventional study

INTRODUCTION

Erosive Hand OsteoArthritis (EHOA) is a common rheumatological problem. We aim to determine characteristics of EHOA patients: comorbidities, radiographic erosivity and pain experienced after being diagnosed, in order to find which of these are potentially relevant in upcoming interventional trials.

METHOD

Retrospective analysis of EHOA patients within the electronic database in one centre, with a telephone interview on pain as experienced even exceeding 12 months after being diagnosed.

RESULTS

Eighty-four non-academic EHOA patients were found: 89% females (median age 69 years), 11% males (similar age distribution). Kellgren-Lawrence (KL) erosivity scores in both sexes were comparable; DIPs scored higher than PIP's. Comorbid conditions were crystal-induced arthritis, rheumatoid arthritis (RA) and psoriatic arthritis (PsA) in 8%, 5% and 1%, respectively; seropositivity for rheumatoid factor and anti-citrullinated protein antibodies in 8% and 1% respectively. Pain worst experienced often exceeded a visual analogue score of 5.0, but was unrelated to the total KL score. Some pain reduction was reached with non-steroidals (perorally/transcutaneously) as deduced from continued use in 1 in 3.

CONCLUSIONS

In many EHOA patients, there is an unmet need regarding the treatment of pain, which per se was not directly correlated with erosivity score. Future studies may be designed considering the aforementioned characteristics, acting on the inflammatory process resulting in PIP/DIP erosions, with the exclusion of RA and PsA in order to get a clean study on EHOA. Several studies with monoclonal antibodies have been performed but demonstrated ineffectivity on the outcome of pain. Hope glooms with the arrival of innovative small molecules that may reach EHOA target cells. Key Points • Erosive handOA is a common problem in non-academic rheumatology; it is often associated with significant pain in both sexes exceeding a VASpain of 5.0 even years after being diagnosed; 1 in 3 found some relief in non-steroidals perorally/transcutaneously. • Future studies will have to focus on (episodic) inflammatory hand OA resulting in proven erosivity (EHOA) located in PIP plus DIP joints and may have to exclude comorbid active crystal-induced arthritis as well as rheumatoid/psoriatic arthritis and possibly even RF/ACPA seropositivity in order to get a clean study on EHOA. • As several big monoclonals have failed in EHOA, we may have to search for promising new drugs within the group of small molecules. These will have to show a significant pain-reducing effect and preferably also a disease-modifying osteoarthritis drug (DMOAD) effect.

Osteoarthritis year in review 2021: epidemiology & therapy

This "Year in review" presents a selection of research themes and individual studies from the clinical osteoarthritis (OA) field (epidemiology and therapy) and includes noteworthy descriptive, analytical-observational, and intervention studies. The electronic database search for the review was conducted in Medline, Embase and medRxiv (15th April 2020 to 1st April 2021). Following study screening, the following OA-related themes emerged: COVID-19; disease burden; occupational risk; prediction models; cartilage loss and pain; stem cell treatments; novel pharmacotherapy trials; therapy for less well researched OA phenotypes; benefits and challenges of Individual Participant Data (IPD) meta-analyses; patient choice-balancing benefits and harms; OA and comorbidity; and inequalities in OA. Headline study findings included: a longitudinal cohort study demonstrating no evidence for a harmful effect of non-steroidal anti-inflammatory drugs (NSAIDs) in terms of COVID-19 related deaths; a Global Burden of Disease study reporting a 102% increase in crude incidence rate of OA in 2017 compared to 1990; a longitudinal study reporting cartilage thickness loss was associated with only a very small degree of worsening in pain over 2 years; an exploratory analysis of a non-OA randomised controlled trial (RCT) finding reduced risk of total joint replacement with an Interleukin -1β inhibitor (canakinumab); a significant relationship between cumulative disadvantage and clinical outcomes of pain and depression mediated by perceived discrimination in a secondary analysis from a RCT; worsening socioeconomic circumstances were associated with future arthritis diagnosis in an innovative natural experiment (with implications for unique research possibilities arising from the COVID-19 pandemic context).

Overview of First-Line and Second-Line Pharmacotherapies for Osteoarthritis with Special Focus on Intra-Articular Treatment

Osteoarthritis (OA) can be defined as the result of pathological processes of various etiologies leading to damage to the articular structures. Although the mechanism of degenerative changes has become better understood due to the plethora of biochemical and genetic studies, the drug that could stop the degenerative cascade is still unknown. All available forms of OA therapy are based on symptomatic treatment. According to actual guidelines, comprehensive treatment of OA should always include a combination of various therapeutic options aimed at common goals, which are pain relief in the first place, and then the improvement of function. Local treatment has become more common practice, which takes place between rehabilitation and pharmacological treatment in the hierarchy of procedures. Only in the case of no improvement and the presence of advanced lesions visible in imaging tests, should surgery be considered. Currently, an increasing number of studies are being published suggesting that intra-articular injections may be as effective or even more effective than non-steroidal anti-inflammatory drugs (NSAIDs) and result in fewer systemic adverse events. The most commonly used preparations are hyaluronic acid (HA), glucocorticosteroids (GS), and also platelet-rich plasma (PRP) in recent years. This review aims to present the mechanism of action and clinical effectiveness of different pharmacological options in relieving pain and improving functions in OA as well as the emerging approach in intra-articular treatment with PRP.

Intra Articular Ozone Modulates Inflammation and Has Anabolic Effect on Knee Osteoarthritis: IL-6 and IGF-1 as Pro-Inflammatory and Anabolic Biomarkers

Objectives: (1) to demonstrate the anti-inflammatory and anabolic effect of Ozone by determining in serum samples the biochemical levels of IL-6 and IGF-1 in knee osteoarthritis (OA) patients in a real world rehabilitation setting; (2) to differentiate Ozone effect in diabetic (DM)/obese and non-DM/non-obese patients; (3) to evaluate clinical effectiveness by visual analog scale (VAS) and WOMAC scale, and biochemical effect by C-reactive protein (CRP), uric acid and erythrocyte sedimentation rate (ESR). Material and methods: 65 patients with knee OA Kellgren Lawrence (KL) grade 2 or more were analyzed in a retrospective observational study. The study ran from January 2018 to September 2021. Inclusion criteria: (a) patients 18 years or older; (b) with knee OA KL 2° or more; (c) biochemical analysis before-and-after treatment; (d) pain more than 3 on VAS. Exclusion Criteria: (a) previous knee surgery; (b) favism; (c) pregnancy; (d) any other disease that originates lack of collaboration for infiltration. Primary Outcome variables: (a) IL-6; (b) IGF-1 in diabetes mellitus (DM)/obese and non-DM/non-obese patients; both before-and-after Ozone treatment. Secondary Outcome variables: (a) CRP, (b) ESR, (c) uric acid, (d) VAS pain, (e) WOMAC pain, function and stiffness. Ozone protocol consisted of four sessions (once a week) of an intra-articular infiltration of 20 mL (20 µg/mL concentration) of a gas mixture of Oxygen-Ozone 95-5% (produced by Ozone generator Ozonosan-α Plus®). For biochemical evaluation, SNIBE MAGLUMI ™ IL-6 (CLIA) and SNIBE MAGLUMI ™ IGF-1 (CLIA) kits were used. CRP and uric acid were analyzed by a Abbott Alinity c kit; and ESR was evaluated by DIESSE VES MATIC CUBE 30. Results: There is a linear correlation between age and OA severity. IL-6 decreased both in DM and non-DM patients and in all OA KL grades (from 2.70 to 1.59 pg/mL). IGF-1 decreased in total group (OA + DM + obesity) from 112.09 to 107.19 ng/mL. When only non-DM/non-obese knee OA patients were analyzed, Ozone improved IGF-1 levels (from 100.17 to 102.03 ng/mL). Ozone decreased CRP, ESR, uric acid, and improved VAS pain, WOMAC pain, function and stiffness (p < 0.05). Conclusions: Ozone is a valid option for the management of knee osteoarthritis in a real world rehabilitation setting, because of its anti-inflammatory, metabolic and anabolic properties. Ozone tends to downregulate pro-inflammatory IL-6 cytokine. Ozone has a metabolic/hypoglycemic effect on obese/diabetic knee osteoarthritis patients by reducing IGF-1. Ozone has an anabolic effect on non-diabetic/non-obese patients by improving IGF-1. Ozone reduces other biomarkers of inflammation (CRP, ESR and uric acid) and improves, pain, function and quality of life.

New developments in osteoarthritis pharmacological therapies

OA is an increasingly common, painful condition with complex aetiology and limited therapies. Approaches to expanding our therapeutic armamentarium have included repurposing existing therapies used for other rheumatological conditions, modifying existing OA preparations to enhance their benefits, and identifying new therapeutics. HCQ and low-dose MTX have been unsuccessful in improving hand OA pain or reducing structural progression. Anti-IL-6 and anti-GM-CSF also did not improve symptoms in hand OA trials, but IL-1 remains an intriguing target for large-joint OA, based on reduced joint replacements in a post hoc analysis from a large cardiovascular disease trial. The peripheral nociceptive pathway appears an attractive target, with mAbs to nerve growth factor and IA capsaicin demonstrating efficacy; tropomyosin receptor kinase A inhibitors are at an earlier stage of development. Limited evidence suggests pharmacological therapies can modify cartilage and bone structural progression, though evidence of synchronous symptom benefits are lacking.

Prospective Association Between Inflammatory Markers and Knee Cartilage Volume Loss and Pain Trajectory

Introduction

Inflammation has been suggested to be involved in the pathogenesis of osteoarthritis and pain. We sought to explore the associations between inflammatory serum markers and magnetic resonance imaging-defined long-term structural change and pain trajectory.

Methods

A total of 169 randomly selected participants (mean age 63 years; 47% female) from a prospective cohort study were included in this study. Circulating levels of interleukin 6 (IL-6), tumour necrosis factor alpha (TNF-α) and high-sensitivity C-reactive protein (CRP) were measured at baseline. A knee MRI scan was performed to measure cartilage volume (CV) and bone marrow lesions (BMLs) at baseline and at 10.7 years. Knee pain at four visits was measured by the WOMAC pain questionnaire, and pain trajectories were identified using group-based trajectory modelling. Linear, log-binomial and multi-nominal logistic regression were used for the analyses.

Results

IL-6 was associated with lateral but not medial tibial CV loss (β = − 0.25% per annum, per standard deviation [SD] log pg/ml; P < 0.05) in the multivariate analysis. IL-6 was also associated with a ‘Moderate pain’ trajectory (relative risk ratio 1.93 per SD log pg/ml; 95% confidence interval 1.02–3.65) relative to the ‘Minimal pain’ trajectory group. There was no significant association of TNF-α and CRP with CV loss and pain trajectory groups with the exception of a beneficial relationship between CRP and medial tibial CV loss (β = 0.20% per annum, per SD log mg/l). No association between inflammatory markers and change in BML size was observed.

Conclusions

IL-6 was independently associated with compartment-specific CV loss and worse pain trajectory, but the other markers studied were not, suggesting that components of inflammation are implicated in the pathogenesis of cartilage loss and developing a worse pain course.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40122-021-00341-1.

Aging, Cell Senescence, the Pathogenesis and Targeted Therapies of Osteoarthritis

Osteoarthritis (OA) is a chronic, debilitating joint disease characterized by progressive destruction of articular cartilage. For a long time, OA has been considered as a degenerative disease, while recent observations indicate the mechanisms responsible for the pathogenesis of OA are multifaceted. Aging is a key factor in its development. Current treatments are palliative and no disease modifying anti-osteoarthritis drugs (DMOADs) are available. In addition to articular cartilage degradation, cellular senescence, synovial inflammation, and epigenetic alterations may all have a role in its formation. Accumulating data demonstrate a clear relationship between the senescence of articular chondrocytes and OA formation and progression. Inhibition of cell senescence may help identify new agents with the properties of DMOADs. Several anti-cellular senescence strategies have been proposed and these include sirtuin-activating compounds (STACs), senolytics, and senomorphics drugs. These agents may selectively remove senescent cells or ameliorate their harmful effects. The results from preclinical experiments and clinical trials are inspiring. However, more studies are warranted to confirm their efficacy, safety profiles and adverse effects of these agents.

The Development of Disease-Modifying Therapies for Osteoarthritis (DMOADs): The Evidence to Date

Osteoarthritis (OA) is a complex heterogeneous articular disease with multiple joint tissue involvement of varying severity and no regulatory-agency-approved disease-modifying drugs (DMOADs). In this review, we discuss the reasons necessitating the development of DMOADs for OA management, the classifications of clinical phenotypes or molecular/mechanistic endotypes from the viewpoint of targeted drug discovery, and then summarize the efficacy and safety profile of a range of targeted drugs in Phase 2 and 3 clinical trials directed to cartilage-driven, bone-driven, and inflammation-driven endotypes. Finally, we briefly put forward the reasons for failures in OA clinical trials and possible steps to overcome these barriers.

Osteoarthritis: Novel Molecular Mechanisms Increase Our Understanding of the Disease Pathology

Although osteoarthritis (OA) is the most common musculoskeletal condition that causes significant health and social problems worldwide, its exact etiology is still unclear. With an aging and increasingly obese population, OA is becoming even more prevalent than in previous decades. Up to 35% of the world’s population over 60 years of age suffers from symptomatic (painful, disabling) OA. The disease poses a tremendous economic burden on the health-care system and society for diagnosis, treatment, sick leave, rehabilitation, and early retirement. Most patients also experience sleep disturbances, reduced capability for exercising, lifting, and walking and are less capable of working, and maintaining an independent lifestyle. For patients, the major problem is disability, resulting from joint tissue destruction and pain. So far, there is no therapy available that effectively arrests structural deterioration of cartilage and bone or is able to successfully reverse any of the existing structural defects. Here, we elucidate novel concepts and hypotheses regarding disease progression and pathology, which are relevant for understanding underlying the molecular mechanisms as a prerequisite for future therapeutic approaches. Emphasis is placed on topographical modeling of the disease, the role of proteases and cytokines in OA, and the impact of the peripheral nervous system and its neuropeptides.