Emerging therapeutic agents in osteoarthritis

In vitro and in vivo studies of the therapeutic potential of Tinospora crispa extracts in osteoarthritis: Targeting oxidation, inflammation, and chondroprotection

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing incidence of osteoarthritis (OA), especially among the elderly population, highlights the need for more efficacious treatments that go beyond mere symptomatic relief. Tinospora crispa (L.) Hook. f. & Thomson (TC) boasts a rich traditional heritage, widespread use in Ayurveda, traditional Chinese medicine (TCM), and diverse indigenous healing practices throughout Southeast Asia for treating arthritis, rheumatism, fever, and inflammation.

AIM OF THE STUDY

This study investigates the anti-inflammatory and chondroprotective potential of TC stem extracts, including ethanolic TC extract (ETCE) and aqueous TC extract (ATCE), in modulating OA pathogenesis through in vitro and in vivo approaches.

MATERIALS AND METHODS

The study utilized LC-MS/MS to identify key compounds in TC stem extracts. In vitro experiments assessed the antioxidative and anti-inflammatory properties of ETCE and ATCE in activated macrophages, while an in vivo monoiodoacetate (MIA)-induced OA rat model evaluated the efficacy of ETCE treatment. Key markers of oxidative stress, such as superoxide dismutase (SOD) and catalase (CAT), were assessed alongside pro-inflammatory cytokines TNF-α and IL-1β, and matrix-degrading enzymes, matrix metalloproteinase (MMP 13 and MMP 3), to evaluate the therapeutic effects of TC stem extracts on OA.

RESULTS

Chemical profiling of the extracts was conducted using LC-MS/MS in positive ionization, identifying seven compounds, including pseudolaric acid B, stylopine, and reticuline, which were reported for the first time in this species. The study utilized varying concentrations of TC stem extracts, specifically 6.25-25 μg/mL for in vitro assays and 500 mg/kg for in vivo studies. Our findings also revealed that both ETCE and ATCE exhibit dose-dependent reduction in reactive oxygen species (41%-52%) and nitric oxide (NO) levels (50% and 72%), with ETCE displaying superior antioxidative efficacy and marked anti-inflammatory properties, significantly reducing TNF-α and IL-6 at concentrations above 12.5 μg/mL. In the MIA-induced OA rat model, ETCE treatment notably outperformed ATCE, markedly lowering TNF-α (1.91 ± 0.37 pg/mL) and IL-1β (26.30 ± 3.68 pg/mL) levels and effectively inhibiting MMP 13 and MMP 3 enzymes. Furthermore, macroscopic and histopathological assessments, including ICRS scoring and OARSI grading, indicate that TC stem extracts reduce articular damage and proteoglycan loss in rat knee cartilage. These results suggest that TC stem extracts may play a role in preventing cartilage degradation and potentially alleviating inflammation and pain associated with OA, though further studies are needed to confirm these effects.

CONCLUSION

This study highlights the potential of TC stem extracts as a novel, chondroprotective therapeutic avenue for OA management. By targeting oxidative stress, pro-inflammatory cytokines, and cartilage-degrading enzymes, TC stem extracts promise to prevent cartilage degradation and alleviate inflammation and pain associated with OA.

Functional Nanomaterials for the Treatment of Osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease, affecting more than 595 million people worldwide. Nanomaterials possess superior physicochemical properties and can influence pathological processes due to their unique structural features, such as size, surface interface, and photoelectromagnetic thermal effects. Unlike traditional OA treatments, which suffer from short half-life, low stability, poor bioavailability, and high systemic toxicity, nanotherapeutic strategies for OA offer longer half-life, enhanced targeting, improved bioavailability, and reduced systemic toxicity. These advantages effectively address the limitations of traditional therapies. This review aims to inspire researchers to develop more multifunctional nanomaterials and promote their practical application in OA treatment.

Oxocarbon Acids and their Derivatives in Biological and Medicinal Chemistry

The biological and medicinal chemistry of the oxocarbon acids 2,3- dihydroxycycloprop-2-en-1-one (deltic acid), 3,4-dihydroxycyclobut-3-ene-1,2-dione (squaric acid), 4,5-dihydroxy-4-cyclopentene-1,2,3-trione (croconic acid), 5,6-dihydroxycyclohex- 5-ene-1,2,3,4-tetrone (rhodizonic acid) and their derivatives is reviewed and their key chemical properties and reactions are discussed. Applications of these compounds as potential bioisosteres in biological and medicinal chemistry are examined. Reviewed areas include cell imaging, bioconjugation reactions, antiviral, antibacterial, anticancer, enzyme inhibition, and receptor pharmacology.

A Comprehensive Review on the Regulatory Action of TRP Channels: A Potential Therapeutic Target for Nociceptive Pain

The transient receptor potential (TRP) superfamily of ion channels in humans comprises voltage-gated, non-selective cation channels expressed both in excitable as well as non-excitable cells. Four TRP channel subunits associate to create functional homo- or heterotetramers that allow the influx of calcium, sodium, and/or potassium. These channels are highly abundant in the brain and kidney and are important mediators of diverse biological functions including thermosensation, vascular tone, flow sensing in the kidney and irritant stimuli sensing. Inherited or acquired dysfunction of TRP channels influences cellular functions and signaling pathways resulting in multifaceted disorders affecting skeletal, renal, cardiovascular, and nervous systems. Studies have demonstrated the involvement of these channels in the generation and transduction of pain. Based on the multifaceted role orchestrated by these TRP channels, modulation of the activity of these channels presents an important strategy to influence cellular function by regulating intracellular calcium levels as well as membrane excitability. Therefore, there has been a remarkable pharmaceutical inclination toward TRP channels as therapeutic interventions. Several candidate drugs influencing the activity of these channels are already in the clinical trials pipeline. The present review encompasses the current understanding of TRP channels and TRP modulators in pain and pain management.

Connection between Mesenchymal Stem Cells Therapy and Osteoclasts in Osteoarthritis

The use of mesenchymal stem cells constitutes a promising therapeutic approach, as it has shown beneficial effects in different pathologies. Numerous in vitro, pre-clinical, and, to a lesser extent, clinical trials have been published for osteoarthritis. Osteoarthritis is a type of arthritis that affects diarthritic joints in which the most common and studied effect is cartilage degradation. Nowadays, it is known that osteoarthritis is a disease with a very powerful inflammatory component that affects the subchondral bone and the rest of the tissues that make up the joint. This inflammatory component may induce the differentiation of osteoclasts, the bone-resorbing cells. Subchondral bone degradation has been suggested as a key process in the pathogenesis of osteoarthritis. However, very few published studies directly focus on the activity of mesenchymal stem cells on osteoclasts, contrary to what happens with other cell types of the joint, such as chondrocytes, synoviocytes, and osteoblasts. In this review, we try to gather the published bibliography in relation to the effects of mesenchymal stem cells on osteoclastogenesis. Although we find promising results, we point out the need for further studies that can support mesenchymal stem cells as a therapeutic tool for osteoclasts and their consequences on the osteoarthritic joint.

Identifying the shared genes and KEGG pathways of Resolvin D1-targeted network and osteoarthritis using bioinformatics

Osteoarthritis (OA) is a common chronic degenerative disease characterized by the loss of articular cartilage, which causes loss of joint function and reduce quality of life. Resolvin D1 (RvD1) has shown interesting anti-inflammatory effects; however, the mechanism of action of RvD1 in OA remains unclear. The aim of this study was to investigate the potential mechanism of RvD1 in OA by bioinformatics and partial in vitro mechanisms. Here, 106 shared differentially expressed genes (DEGs) were identified based on the GSE82107, GSE55235, GSE55457 dataset; 700 DEGs were identified based on GSE169077. Enrichment analyses of these genes were then successively conducted. RvD1-targeted genes and KEGG pathways are identified by STITCH. 27 shared KEGG pathways were identified among RvD1-targeted pathways and OA. Furthermore, cell apoptosis assay, western blotting, real-time fluorescent quantitative PCR (qRT-PCR), enzyme linked immunosorbent assay (ELISA) were used to confirm the expression levels of the key genes of shared Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways between RvD1-targeted and OA in IL-1β treated rat knee chondrocytes. The results showed that RvD1-targeted pathways and the expression of nuclear p65, p53, and p-JNK were inhibited in the RvD1 group compared with the IL-1β group. Thus, the findings indicate that RvD1 may inhibit the development of OA through NF/kB, p53, MAPK/JNK, PI3K-AKT signaling pathways, and act as a treatment for OA.

Multi‐method quantitative benefit‐risk assessment of treatments for moderate‐to‐severe osteoarthritis

Objective

Demonstrate how benefit‐risk profiles of systemic treatments for moderate‐to‐severe osteoarthritis (OA) can be compared using a quantitative approach accounting for patient preference.

Study design and setting

This study used a multimethod benefit‐risk modelling approach to quantifiably compare treatments of moderate‐to‐severe OA. In total four treatments and placebo were compared. Comparisons were based on four attributes identified as most important to patients. Patient Global Assessment of Osteoarthritis was included as a favourable effect. Unfavourable effects, or risks, included opioid dependence, nonfatal myocardial infarction and rapidly progressive OA leading to total joint replacement. Clinical data from randomized clinical trials, a meta‐analysis of opioid dependence and a long‐term study of celecoxib were mapped into value functions and weighted with patient preferences from a discrete choice experiment.

Results

Lower‐dose NGFi had the highest weighted net benefit‐risk score (0.901), followed by higher‐dose NGFi (0.889) and NSAIDs (0.852), and the lowest score was for opioids (0.762). Lower‐dose NGFi was the highest‐ranked treatment option even when assuming a low incidence (0.34% instead of 4.7%) of opioid dependence (ie, opioid benefit‐risk score 808) and accounting for both the uncertainty in clinical effect estimates (first rank probability 46% vs 20% for NSAIDs) and imprecision in patient preference estimates (predicted choice probability 0.26, 95% confidence interval [CI] 0.25‐0.28 vs 0.21, 95% CI 0.19‐0.23 for NSAIDs).

Conclusion

The multimethod approach to quantitative benefit‐risk modelling allowed the interpretation of clinical data from the patient perspective while accounting for uncertainties in the clinical effect estimates and imprecision in patient preferences.

Effects of type II collagen hydrolysates on osteoarthritis through the NF-κB, Wnt/β-catenin and MAPK pathways

Osteoarthritis (OA), a degenerative disease, has attracted extensive attention all over the world. In this study, a rat model involving medial meniscus resection (MMx) and anterior to medial collateral ligament (ACL) operation was successfully established to study the effects of bovine cartilage hydrolysates rich in type II collagen peptides (BIIP) on cartilage protection. The results of histological analysis indicated that oral administration of BIIP at doses of 200 and 500 mg kg^-1 d^-1 ameliorated cartilage degeneration. Moreover, the potential targets of BIIP affecting OA in vivo were studied by proteomics, and the effects of BIIP on OA through signaling pathways, such as NF-κB, Wnt/β-catenin and MAPK, were further explored at mRNA and protein levels. BIIP downregulated the expression of IL-6, RUNX2, NF-κB p65, HIF-2α, β-catenin and p-JNK, which may be the main factor leading to the prevention of OA. These results suggest that BIIP can be used as a novel potential substance of functional foods to exert chondroprotective action.

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.

p16INK4a-siRNA nanoparticles attenuate cartilage degeneration in osteoarthritis by inhibiting inflammation in fibroblast-like synoviocytes

In osteoarthritis (OA), chondrocytes in cartilage undergo phenotypic changes and senescence, restricting cartilage regeneration and favoring disease progression. Although senescence biomarker p16INK4a expression is known to induce aging by halting...

The Recovery of Cognitive and Affective Deficiencies Linked with Chronic Osteoarthritis Pain and Implicated Pathways by Slow-Releasing Hydrogen Sulfide Treatment

Chronic osteoarthritis pain is accompanied by several comorbidities whose treatment has not been completely resolved. The anti-inflammatory, analgesic, and antidepressant effects of slow-releasing hydrogen sulfide (H₂S) donors during osteoarthritic pain have been shown, but their actions in the accompanying memory impairment and anxious-like behaviors have not yet been demonstrated. Using female mice with chronic osteoarthritic pain, the effects of natural, diallyl disulfide (DADS) or synthetic, morpholin-4-ium 4-methoxyphenyl(morpholino) phosphinodithioate dichloromethane complex (GYY4137) slow-releasing H₂S donors, on associated cognitive and grip strength deficits and anxiodepressive-like behaviors, were assessed. Their effects on specific brain areas implicated in the modulation of pain and emotional responses were also determined. Results demonstrated an improvement in memory and grip strength deficits, as well as in the anxious-like behaviors associated with chronic pain in GYY4137 and/or DADS treated mice. The painkiller and antidepressant properties of both treatments were also established. Treatment with DADS and/or GYY4137 inhibited: oxidative stress in the amygdala; phosphoinositide 3-kinase overexpression in the amygdala, periaqueductal gray matter, and anterior cingulate cortex; protein kinase B activation in the amygdala and infralimbic cortex; up-regulation of inducible nitric oxide synthase in the amygdala, periaqueductal gray matter and infralimbic cortex and apoptotic responses in the amygdala. These results might explain the recovery of memory and grip strength and the inhibition of allodynia and associated anxiodepressive-like behaviors by these treatments. In conclusion, this study revealed new properties of slow-releasing H₂S donors in cognitive impairment and affective disorders linked with chronic osteoarthritis pain and their effects on the central nervous system.

Role of peroxiredoxin 6 in the chondroprotective effects of microvesicles from human adipose tissue-derived mesenchymal stem cells

Background

Osteoarthritis (OA) is a joint disease characterized by cartilage degradation, low-grade synovitis and subchondral bone alterations. In the damaged joint, there is a progressive increase of oxidative stress leading to disruption of chondrocyte homeostasis. The modulation of oxidative stress could control the expression of inflammatory and catabolic mediators involved in OA. We have previously demonstrated that extracellular vesicles (EVs) present in the secretome of human mesenchymal stem cells from adipose tissue (AD-MSCs) exert anti-inflammatory and anti-catabolic effects in OA chondrocytes. In the current work, we have investigated whether AD-MSC EVs could regulate oxidative stress in OA chondrocytes as well as the possible contribution of peroxiredoxin 6 (Prdx6).

Methods

Microvesicles (MV) and exosomes (EX) were isolated from AD-MSC conditioned medium by differential centrifugation with size filtration. The size and concentration of EVs were determined by resistive pulse sensing. OA chondrocytes were isolated from knee articular cartilage of advanced OA patients. 4-Hydroxynonenal adducts, IL-6 and MMP-13 were determined by enzyme-linked immunosorbent assay. Expression of Prdx6 and autophagic markers was assessed by immunofluorescence and Western blotting. Prdx6 was downregulated in AD-MSCs by transfection with a specific siRNA.

Results

MV and to a lesser extent EX significantly reduced the production of oxidative stress in OA chondrocytes stimulated with IL-1β. Treatment with MV resulted in a dramatic upregulation of Prdx6. MV also enhanced the expression of autophagy marker LC3B. We downregulated Prdx6 in AD-MSCs by using a specific siRNA and then MV were isolated. These Prdx6-silenced MV failed to modify oxidative stress and the expression of autophagy markers. We also assessed the possible contribution of Prdx6 to the effects of MV on IL-6 and MMP-13 production. The reduction in the levels of both mediators induced by MV was partly reverted after Prdx6 silencing.

Conclusion

Our results indicate that EVs from AD-MSCs regulate the production of oxidative stress in OA chondrocytes during inflammation. Prdx6 may mediate the antioxidant and protective effects of MV.

The translational potential of this article: This study gives insight into the protective properties of EVs from AD-MSCs in OA chondrocytes. Our findings support the development of novel therapies based on EVs to prevent or treat cartilage degradation.

Development of Cdc2-like Kinase 2 Inhibitors: Achievements and Future Directions

Cdc2-like kinases (CLKs; CLK1-4) are associated with various neurodegenerative disorders, metabolic regulation, and viral infection and have been recognized as potential drug targets. Human CLK2 has received increasing attention as a regulator that phosphorylates serine- and arginine-rich (SR) proteins and subsequently modulates the alternative splicing of precursor mRNA (pre-mRNA), which is an attractive target for degenerative disease and cancer. Numerous CLK2 inhibitors have been identified, with several molecules currently in clinical development. The first CLK2 inhibitor Lorecivivint (compound 1) has recently entered phase 3 clinical trials. However, highly selective CLK2 inhibitors are rarely reported. This Perspective summarizes the biological roles and therapeutic potential of CLK2 along with progress on the development of CLK2 inhibitors and discusses the achievements and future prospects of CLK2 inhibitors for therapeutic applications.

ADAMTS5 in Osteoarthritis: Biological Functions, Regulatory Network, and Potential Targeting Therapies

ADAMTS5 is involved in the pathogenesis of OA. As the major aggrecanase-degrading articular cartilage matrix, ADAMTS5, has been regarded as a potential target for OA treatment. We here provide an updated insight on the regulation of ADAMTS5 and newly discovered therapeutic strategies for OA. Pathophysiological and molecular mechanisms underlying articular inflammation and mechanotransduction, as well as chondrocyte hypertrophy were discussed, and the role of ADAMTS5 in each biological process was reviewed, respectively. Senescence, inheritance, inflammation, and mechanical stress are involved in the overactivation of ADAMTS5, contributing to the pathogenesis of OA. Multiple molecular signaling pathways were observed to modulate ADAMTS5 expression, namely, Runx2, Fgf2, Notch, Wnt, NF-κB, YAP/TAZ, and the other inflammatory signaling pathways. Based on the fundamental understanding of ADAMTS5 in OA pathogenesis, monoclonal antibodies and small molecule inhibitors against ADAMTS5 were developed and proved to be beneficial pre-clinically both in vitro and in vivo. Recent novel RNA therapies demonstrated potentials in OA animal models. To sum up, ADAMTS5 inhibition and its signaling pathway–based modulations showed great potential in future therapeutic strategies for OA.

Comparative efficacy and safety of Chinese herbal medicine for knee osteoarthritis: A protocol for systematic review and network meta-analysis

BACKGROUND

Knee osteoarthritis (OA) is a major public health concern causing chronic disability as well as a substantial burden on health care and the economy. However, effective treatments for knee OA were still not available. Numerous clinical studies have suggested that Chinese herbal medicine (CHM) seems to be clinically effective in treating knee OA. Thus, this study aims to evaluate the efficacy and safety of CHM in the treatment of knee OA through a systematic review and network meta-analysis.

METHODS

A comprehensive search will be performed in PubMed, Cochrane Library, Embase, Web of Science, China National Knowledge Infrastructure, VIP Database, Wanfang Database, Chinese Biomedical Database, and 3 clinical trials registration websites, from the database inception to May 2021. Randomized controlled trials meeting the eligible criteria based on the PICOS framework will be included. All studies fulfilling the eligible criteria will be assessed for risk of bias using the Cochrane Collaboration's tool. The primary outcome will be the visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index, and total effective rate. The secondary outcome is the incidence of adverse events. Data analysis will be performed using Stata, Addis, and WinBUGS.

DISCUSSION

This study will provide a reliable evidence to assess effectiveness and safety of CHM for knee OA, which may provide guidance for clinical practice.

SYSTEMATIC REVIEW REGISTRATION

This study protocol has been registered on INPLASY202160060.

Osteoarthritis-Related Knee Pain Treated With Genicular Artery Embolization: A Systematic Review and Meta-analysis

BACKGROUND

Genicular artery embolization (GAE) is an innovative technique that has been investigated as a supplementary treatment method for chronic pain secondary to knee osteoarthritis (OA).

PURPOSE

To evaluate the current evidence on the effectiveness and safety of GAE for OA-related knee pain.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic literature search was conducted in the PubMed, Web of Science, EMBASE, and Scopus databases to identify studies related to knee OA treated with GAE. Treatment agents were categorized as Embozene, imipenem/cilastatin, resorbable microspheres, and polyvinyl alcohol. The main outcomes were the mean difference (MD) in pre- and postembolization pain based on the visual analog scale (VAS) or the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores as well as changes in the need for pain medication. Random- and fixed-effects models were applied for data analysis.

RESULTS

Of 379 initially inspected publications, 11 (N = 225 patients; 268 knees) were included in the final review. The quality of the studies was fair in 8 and poor in 3-categorized according to the National Institutes of Health quality assessment tool. Overall, 119, 72, 13, and 21 patients were treated with imipenem/cilastatin, Embozene, resorbable microspheres, and polyvinyl alcohol, respectively. Symptomatic improvement was reported in all studies. The pooled effect size, characterized by MD, showed a significant improvement in the VAS and WOMAC pain scores, with better functional status after GAE. Pre- versus postembolization MDs in VAS scores ranged from 32 within the first week to 58 after a 2-year follow-up (equivalent to 54% and 80% improvement, respectively). There was a similar trend in the overall WOMAC scores, with MDs ranging from 28.4 to 36.8 (about 58% and 85% improvement, respectively). GAE resulted in a decreased need for pain medication for knee OA, with a 27%, 65%, and 73% decline in the number of patients who used opioids, nonsteroidal anti-inflammatory drugs, and intra-articular hyaluronic acid injection, respectively (P < .00001 for all). No significant difference between embolic agents was seen with regard to post-GAE pain reduction. No severe or life-threatening complications were reported.

CONCLUSION

OA treated by GAE using different embolic particles can be considered generally safe, with good efficacy and no reported serious complications.

Efficacy and safety of sprifermin injection for knee osteoarthritis treatment: a meta-analysis

OBJECTIVE

To perform a meta-analysis comparing the structural progression and clinical symptom outcomes as well as adverse events experienced from intra-articular injections of sprifermin compared to a placebo treatment for patients with knee osteoarthritis (KOA).

METHOD

We systematically searched the literature for studies that compared long-term outcomes between sprifermin and placebo injections for KOA treatment. Meta-analysis was performed with RevMan5.3 using an inverse variance approach with fixed or random effects models. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated.

RESULTS

Eight studies were included. Overall, there was significantly less improvement of WOMAC total scores in patients receiving sprifermin, compared with the placebo (mean difference (MD) = 3.23, 95% CI 0.76-5.69; I² = 0%; P = 0.01). Further, sprifermin injection patients gained more, and lost less, cartilage thickness and volume in total femorotibial joint (cartilage thickness: standardized mean differences (SMD) = 0.55, 95% CI 0.26-0.84; I² = 78%; P = 0.0002; cartilage volume: SMD = 0.39, 95% CI 0.20-0.58; I² = 49%; P < 0.0001). Changes in the cartilage surface morphology of the medial tibio-femoral joint (MD = -0.30, 95% CI -0.44 to -0.16; I² = 0%; P < 0.0001) and patello-femoral joint (MD = -0.22; 95% CI -0.37 to -0.07; I² = 0%; P = 0.004) showed a significant difference between the sprifermin and placebo injections. Moreover, there were no significant differences between sprifermin and the placebo in the risk of treatment-emergent adverse events (OR = 1.05; 95% CI 0.52-2.14; I² = 48%; P = 0.89).

CONCLUSION

The data from the included studies provide strong evidence to determine the effect of intra-articular sprifermin on joint structure in individuals with KOA and show no specific adverse effects. Nevertheless, intra-articular sprifermin did not likely have any positive effect on symptom alleviation.

miR-137 targets the inhibition of TCF4 to reverse the progression of osteoarthritis through the AMPK/NF-κB signaling pathway

Purpose: To explore the regulatory mechanism of miR-137 and transcription factor 4 (TCF4) in the progression of osteoarthritis (OA).

Patients and Methods: The expressions of miR-137 and TCF4 were detected in OA cartilage tissue, chondrocytes and OA rat cartilage tissue. miR-137 and TCF4 were up-regulated or down-regulated and transfected into chondrocytes and OA rat cartilage tissue. The gene expression, protein level, cell proliferation, apoptosis and inflammatory factors were detected, respectively. LPS and anterior cruciate ligament transection (ACLT) on the right knee were used to induce chondrocyte inflammation and establish rat OA model, respectively.

Results: miR-137 was low expressed in cartilage tissue of OA group, while TCF4 expression and protein level were significantly higher, showing significant negative correlation. In LPS group, chondrocyte activity was significantly inhibited, cell apoptosis ability was significantly enhanced, and the levels of inflammatory factors TNF-α, IL-1β, IL-6 were significantly increased. However, the above results were significantly improved after the up-regulation of miR-137 or down-regulation of TCF4. Double luciferase report revealed that miR-137 and TCF4 had targeted relationship. LPS induced activation of AMPK/NF-κB pathway and higher level of apoptosis. AMPK/NF-κB pathway inhibitor C could inhibit activation of this pathway, and up-regulation of miR-137 or down-regulation of TCF4 could significantly weaken the regulation of LPS on the pathway and apoptosis. Analysis of OA rat model showed that over-expression of miR-137 could inhibit up-regulation of inflammatory factors and activation of AMPK/NF-κB pathway.

Conclusion: miR-137 targets the inhibition of TCF4 to reverse the progression of OA through the AMPK/NF-κB signaling pathway.

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.

Anti-Inflammatory and Analgesic Effects of TRPV1 Polypeptide Modulator APHC3 in Models of Osteo- and Rheumatoid Arthritis

Arthritis is a widespread inflammatory disease associated with progressive articular surface degradation, ongoing pain, and hyperalgesia causing the development of functional limitations and disability. TRPV1 channel is one of the high-potential targets for the treatment of inflammatory diseases. Polypeptide APHC3 from sea anemone Heteractis crispa is a mode-selective TRPV1 antagonist that causes mild hypothermia and shows significant anti-inflammatory and analgesic activity in different models of pain. We evaluated the anti-inflammatory properties of APHC3 in models of monosodium iodoacetate (MIA)-induced osteoarthritis and complete Freund’s adjuvant (CFA)-induced rheumatoid monoarthritis in comparison with commonly used non-steroidal anti-inflammatory drugs (NSAIDs) such as diclofenac, ibuprofen, and meloxicam. Subcutaneous administration of APHC3 (0.1 mg/kg) significantly reversed joint swelling, disability, grip strength impairment, and thermal and mechanical hypersensitivity. The effect of APHC3 was equal to or better than that of reference NSAIDs. Protracted treatment with APHC3 decreased IL-1b concentration in synovial fluid, reduced inflammatory changes in joints, and prevented the progression of cartilage degradation. Therefore, polypeptide APHC3 has the potential to be an analgesic and anti-inflammatory substance for the alleviation of arthritis symptoms.

Protective effects of the novel amine-oxidase inhibitor multi-target drug SZV 1287 on streptozotocin-induced beta cell damage and diabetic complications in rats

Diabetes mellitus is a common metabolic disease leading to hyperglycemia due to insufficient pancreatic insulin production or effect. Amine oxidase copper containing 3 (AOC3) is an enzyme that belongs to the semicarbazide-sensitive amine oxidase family, which may be a novel therapeutic target to treat diabetic complications. We aimed to explore the effects of AOC3 inhibition and to test the actions of our novel AOC3 inhibitor multi-target drug candidate, SZV 1287, compared to a selective reference compound, LJP 1207, in an 8-week long insulin-controlled streptozotocin (STZ)-induced (60 mg/kg i.p.) rat diabetes model. Both AOC3 inhibitors (20 mg/kg, daily s.c. injections) were protective against STZ-induced pancreatic beta cell damage determined by insulin immunohistochemistry and radioimmunoassay, neuropathic cold hypersensitivity measured by paw withdrawal latency decrease from 0 °C water, and retinal dysfunction detected by electroretinography. SZV 1287 showed greater inhibitory effects on beta cell damage, and reduced retinal apoptosis shown by histochemistry. Mechanical hypersensitivity measured by aesthesiometry, cardiac dysfunction and nitrosative stress determined by echocardiography and immunohistochemistry/Western blot, respectively, serum Na⁺, K⁺, fructosamine, and urine microalbumin, creatinine, total protein/creatinine ratio alterations did not develop in response to diabetes. None of these parameters were influenced by the treatments except for SZV 1287 reducing serum fructosamine and LJP 1207 increasing urine creatinine. We provide the first evidence for protective effects of AOC3 inhibition on STZ-induced pancreatic beta cell damage, neuropathic cold hypersensitivity and diabetic retinal dysfunction. Long-term treatment with our novel multi-target analgesic candidate, SZV 1287, is safe and effective also under diabetic conditions.

Differential gene expression in skin RNA of horses affected with degenerative suspensory ligament desmitis

BACKGROUND

Equine degenerative suspensory ligament desmitis (DSLD) is a systemic connective tissue disorder first identified in Peruvian Paso horses but afflicting other horse breeds as well. Inappropriate accumulation of proteoglycans in connective tissues, most prominently in tendons and ligaments, leads to progressive and debilitating lameness and pain. It is largely unknown what drives the overproduction of proteoglycans, but our previous studies suggest involvement of bone morphogenetic protein 2 (BMP2), a member of the transforming growth factor-β (TGFβ) family, impacting synthesis of proteoglycans. To identify potential players in pathogenesis of DSLD a new approach utilizing next generation sequencing was undertaken.

METHODS

Next generation sequencing was performed using RNA extracted from skin biopsies of six control Peruvian Pasos and six horses with DSLD (4 Peruvian Pasos and 2 warmbloods). The CuffDiff result sets were validated with algorithms used to run them. This was based on the determined false discovery rates derived from the P values adjusted for multiple testing for any given result.

RESULTS

Bioinformatics analysis of transcriptomes revealed differential expression of over 1500 genes, including increased expression of genes for several growth factors (most prominently BMP2, FGF5, CTGF, many members of the EGF family), and mediators of signaling (Fos, Myc, MAPK system), and keratins. Two genes encoding for enzymes involved in synthesis of hyaluronan were also overexpressed. Gene expression was decreased for protein cores of many proteoglycans, several growth factors, most collagens, and many peptides with immune function.

CONCLUSIONS

The overexpression of BMP2 correlates well with our previous data. However, the decrease in expression of numerous proteoglycans was unexpected. A mutation in a gene of a less characterized proteoglycan and/or glycosyltransferase with subsequent increased production of hyaluronan and/or a proteoglycan(s) undetected in our study could account for the systemic proteoglycan deposition. Decreased collagen gene expression indicates abnormal connective tissue metabolism. The increased expression of keratin genes and FGF5 supports reports of skin abnormalities in DSLD. Underexpression of immune function genes corresponds with lack of inflammation in DSLD tissues. Finally, though the proteoglycan and/or glycosaminoglycan abundant in DSLD has not been identified, we validated our previous data, including overexpression of BMP2, and systemic nature of DSLD due to disturbed metabolism of the extracellular matrix.

The GDF-5 mutant M1673 exerts robust anabolic and anti-catabolic effects in chondrocytes

The growth and differentiation factor 5 (GDF‐5) is known to play a key role in cartilage morphogenesis and homeostasis, and a single‐nucleotide polymorphism in its promoter sequence was found to be associated with osteoarthritis (OA). In addition, GDF‐5 was shown to promote extracellular matrix (ECM) production in healthy chondrocytes, to stimulate chondrogenesis of mesenchymal stem cells (MSCs) and to protect against OA progression in vivo. Therefore, GDF‐5 appears to be a promising treatment for osteoarthritis. However, GDF‐5 also promotes osteogenesis and hypertrophy, limiting its therapeutic utility. To circumvent this, a GDF‐5 mutant with lower hypertrophic and osteogenic properties was engineered: M1673. The present study aimed to evaluate and compare the effects of GDF‐5 and M1673 on primary porcine and human OA chondrocytes. We found that both GDF‐5 and M1673 can robustly stimulate ECM accumulation, type II collagen and aggrecan expression in porcine and human OA chondrocytes in 3D culture. In addition, both molecules also down‐regulated MMP13 and ADAMTS5 expression. These results suggest that M1673 retained the anabolic and anti‐catabolic effects of GDF‐5 on chondrocytes and is an alternative to GDF‐5 for osteoarthritis.

Translational strategies in drug development for knee osteoarthritis

Osteoarthritis (OA) is a common disease worldwide with large unmet medical needs. To bring innovative treatments to OA patients, we at Merck have implemented a comprehensive strategy for drug candidate evaluation. We have a clear framework for decision-making in our preclinical pipeline, to design our clinical proof-of-concept trials for OA patients. We have qualified our strategy to define and refine dose and dosing regimen, for treatments administered either systemically or intra-articularly (IA). We do this through preclinical in vitro and in vivo studies, and by back-translating results from clinical studies in OA patients.

ADAMTS-5: A difficult teenager turning 20

A Disintegrin And Metalloproteinase with ThromboSpondin motif (ADAMTS)-5 was identified in 1999 as one of the enzymes responsible for cleaving aggrecan, the major proteoglycan in articular cartilage. Studies in vitro, ex vivo and in vivo have validated ADAMTS-5 as a target in osteoarthritis (OA), a disease characterized by extensive degradation of aggrecan. For this reason, it attracted the interest of many research groups aiming to develop a therapeutic treatment for OA patients. However, ADAMTS-5 proteoglycanase activity is not only involved in the dysregulated aggrecan proteolysis, which occurs in OA, but also in the physiological turnover of other related proteoglycans. In particular, versican, a major ADAMTS-5 substrate, plays an important structural role in heart and blood vessels and its proteolytic processing by ADAMTS-5 must be tightly regulated. On the occasion of the 20th anniversary of the discovery of ADAMTS-5, this review looks at the evidence for its detrimental role in OA, as well as its physiological turnover of cardiovascular proteoglycans. Moreover, the other potential functions of this enzyme are highlighted. Finally, challenges and emerging trends in ADAMTS-5 research are discussed.

Increasing the Medium Osmolarity Reduces the Inflammatory Status of Human OA Chondrocytes and Increases Their Responsiveness to GDF-5

The environment surrounding chondrocytes changes drastically in osteoarthritis (OA). For instance, the osmolarity in cartilage (ranging from 350 to 460 mOsm in healthy tissue) decreases during the progression of OA, reaching 270 mOsm. The objective of this study was to evaluate how osmolarity influences human OA chondrocytes. For this purpose, the osmolarity of the culture medium (340 mOsm) was increased to 380, 420 or 460 mOsm and its effect on the phenotype, matrix production, protease expression, cytokine release and growth and differentiation factor-5 (GDF-5) receptor expression in human OA chondrocytes was evaluated in a monolayer. Afterwards, the same parameters, as well as the responsiveness to GDF-5, were evaluated in 3D culture at 340 and 380 mOsm. Our results revealed that increasing the medium osmolarity increased matrix production but also reduced cytokine release, type I collagen and protease expression. It was also demonstrated that at 380 mOsm, the response to GDF-5 in 3D culture was more robust than at 340 mOsm. For the first time, it was established that a decreased osmolarity plays a role in sustaining inflammation and catabolic activities in OA chondrocytes and decreases their responsiveness to GDF-5. This indicates that osmolarity is a critical aspect of OA pathobiology.