Osteoarthritis, an inflammatory disease: potential implication for the selection of new therapeutic targets

Efficacy and predictive factors of response to intra-articular corticosteroids in knee osteoarthritis

In knee osteoarthritis (KOA), synovial inflammation is linked with pain, swelling and structural abnormalities. Intra-articular corticosteroids (IACS) have been considered for pain relief in subjects who are non-responders to standard therapy. However, the results vary across different studies. This review aims to determine efficacy of IACS in KOA by review of the existing data.

In several randomized controlled trials (RCTs), meta-analyses and uncontrolled studies a single IACS resulted in pain relief from 1 to a few weeks. In a few studies repeated IACS every three months provided a longer duration of pain relief and functional improvement in a proportion of patients. Baseline synovitis was predictor of treatment response in some but not all studies.

Based upon the existing data, IACS provides a short-term pain relief in a proportion of patients. Given, anti-inflammatory properties of IACS, it is likely to be more effective in subgroups of KOA who display inflammatory phenotype.

Beneficial effects of Vigna angularis extract in osteoporosis and osteoarthritis

In Asia, Vigna angularis (azuki bean) has been used as a traditional medicine to treat various diseases because of its biological properties. Osteoarthritis (OA) and osteoporosis (OP) are common regenerative bone diseases that are characterized by deterioration of joint and bone structure. In this study, we evaluated the effects of Vigna angularis extract (VAE) on monosodium iodoacetate (MIA)-induced OA and ovariectomy (OVX)-induced OP models. In the MIA-induced OA results, severe OA was alleviated by the administration of VAE. Extensive local damage in the cartilage and hemorrhagic and edematous of surrounding tissues were decreased by VAE treatment. Articular cartilage was almost intact except for a focal mild abrasion, and the surface was glistening, similar to that of the normal joint. In the OVX-induced OP results, bone mineral content (BMC) and bone mineral density (BMD) were recovered by VAE treatment, and it improved the microstructures of bone. These results show that VAE could inhibit OA and OP symptoms.

Exploring the Association of Innate Immunity Biomarkers With MRI Features in Both Early and Late Stages Osteoarthritis

Objective: To evaluate the association between biomarkers of innate immunity and the magnetic resonance imaging (MRI) features of earlier and later stages of knee osteoarthritis (KOA). Methods: From 139 and 20 participants with earlier and later stages of KOA, respectively, we analyzed knee MRIs scored using the Boston Leeds Osteoarthritis Knee Score (BLOKS) at recruitment with biomarkers. In paired serum (s) and synovial fluid (sf), we quantified three biomarkers related to innate immunity: lipopolysaccharide binding protein (LBP), CD14 and Toll-like receptor 4 (TLR4), and three proinflammatory biomarkers [interleukin-6 (IL6), IL8, and tumor necrosis factor alpha (TNFα)]. Results: In participants with earlier KOA, (s) LBP was statistically significantly associated with meniscal extrusion, and (sf) CD14 was associated with effusion after adjustment with age, sex, and body mass index. In participants with later stage of KOA, (sf) LBP was associated with effusion. (sf) CD14 was associated with cartilage loss and BML. In earlier stage of KOA, the proinflammatory biomarkers IL6, IL8, and TNFα were associated with most MRI features. Conclusion: Innate immunity biomarkers (s) LBP was associated with MRI meniscal extrusion; (sf) CD14 was associated with MRI synovial inflammation in earlier stage and BMLs in later stage of KOA. Associations between proinflammatory biomarkers and various MRI features in earlier stage of KOA were observed.

OPN Deficiency Increases the Severity of Osteoarthritis Associated with Aberrant Chondrocyte Senescence and Apoptosis and Upregulates the Expression of Osteoarthritis-Associated Genes

Objectives

A recent work has reported that the elevated osteopontin (OPN) levels in the articular cartilage and synovial fluid are correlated with the progressive osteoarthritis (OA) joint damage, and OPN has a protective effect against OA by suppressing the expressions of OA-associated genes. The present study examined whether the OPN deficiency was susceptible to OA through the regulation of chondrocyte senescence and apoptosis and the expressions of OA-associated genes.

Methods

The mRNA levels of COL2A1 and OPN were compared between human OA chondrocytes and normal chondrocytes. The effects of OPN siRNA on the SA-β-Gal expressions and the percentage of apoptotic chondrocytes were examined by using SA-β-Gal staining and apoptosis assay, and the effects on the expressions of COL2A1 and OA-associated genes (COL10A1, IL-1β, TNF-ɑ, MMP-13, and ADAMTS5) were examined by western blot analysis and quantitative real-time RT-PCR. Furthermore, an in vivo OA model was established to examine the effects of OPN siRNA on the senescence and apoptosis of OA chondrocytes and the expressions of OA-associated genes.

Results

The mRNA levels of COL2A1 and OPN were decreased in knee OA chondrocytes in comparison with those in normal chondrocytes. The OPN deficiency enhanced the senescence and apoptosis of OA chondrocytes and increased the expressions of COL10A1, IL-1β, TNF-ɑ, MMP-13, and ADAMTS5 but decreased the expression of COL2A1. Meanwhile, OPN deficiency could result in severe, accelerated OA in vivo, which was also associated with enhanced senescence and apoptosis of chondrocytes and elevated expressions of OA-associated genes.

Conclusions

The findings of this study suggest that the OPN deficiency can result in accelerated OA, which is associated with enhanced senescence and apoptosis of OA chondrocytes and the upregulated expressions of OA-associated genes.

Mechanism of Abnormal Chondrocyte Proliferation Induced by Piezo1-siRNA Exposed to Mechanical Stretch

Objective

To investigate the effect of small interfering RNA targeting mechanosensitive ion channel protein Piezo1 (Piezo1-siRNA) on abnormal chondrocyte proliferation exposed to mechanical stretch.

Methods

Construct and screen effective Piezo1-siRNA sequences and explore an appropriate method to transfect lentiviral vector into chondrocytes exposed to mechanical stretch. Western blot and RT-PCR were used to detect the mRNA and protein expression of Piezo1, Kif18A, and β-tubulin, respectively. Flow cytometry was used to measure the changes in the chondrocyte cycle. The proliferation of chondrocyte was evaluated by cell counting kit-8.

Results

According to the mRNA and protein expression of Piezo1, the effective siRNA sequence was successfully screened. Compared with the 0 h group, mechanical stretch upregulated the expression of Piezo1, Kif18A, and β-tubulin, resulting in chondrocyte cycle arrest and eventually inhibiting chondrocyte proliferation. Moreover, Piezo1-siRNA transfection effectively blocks this process and promotes the proliferation of chondrocyte.

Conclusion

Piezo1-siRNA can reduce the inhibition of chondrocyte proliferation induced by mechanical stretch via downregulating the expression of Kif18A and inhibiting the depolymerization of microtubules. Piezo1-siRNA plays a protective role in chondrocytes, which provides a potential method for the treatment of OA under abnormal mechanical stimulation.

Can low-dose methotrexate reduce effusion-synovitis and symptoms in patients with mid- to late-stage knee osteoarthritis? Study protocol for a randomised, double-blind, and placebo-controlled trial

BACKGROUND

Osteoarthritis (OA) is a common chronic disease in older adults. Currently, there are no effective therapies to reduce disease severity and progression of knee OA (KOA), particularly in mid- to late-stages. This study aims to examine the effect of methotrexate (MTX) on knee effusion-synovitis and pain in symptomatic patients with mid- to late-stage KOA.

METHODS/DESIGN

This protocol describes a multicentre randomised placebo-controlled clinical trial aiming to recruit 200 participants with mid- to late-stage symptomatic KOA and with effusion-synovitis grade of ≥ 2. Participants will be randomly allocated to the MTX group (start from 5 mg per week for the first 2 weeks and increase to 10 mg per week for the second 2 weeks and 15 mg per week for the remaining period if tolerated) or the placebo group. Primary outcomes are effusion-synovitis size measured by magnetic resonance imaging (MRI) and knee pain assessed by visual analogue scale (VAS). Secondary outcomes are signal intensity alteration within infrapatellar fat pad (IPFP) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total score and subscores, and the Outcome Measures in Rheumatology Arthritis Clinical Trials-Osteoarthritis Research Society International (OMERACT-OARSI) responders. Both intention-to-treat and per-protocol analyses will be performed.

DISCUSSION

If MTX intervention can relieve symptoms and reduce inflammation in patients with mid- to late-stage KOA, it has the potential for significant clinical and public health impact as this low-cost and commonly used intervention would delay the time to knee replacement, leading to substantial cost savings and improve quality of life.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03815448 . Registered on 21 January 2019.

Acupuncture reduces pain in rats with osteoarthritis by inhibiting MCP2/CCR2 signaling pathway

Acupuncture is an emerging alternative therapy that has been beneficial for the pain of osteoarthritis (OA). However, the underlying mechanism of protective effect remains unclear. MCP1/CCR2 axis can be stimulated in various periods of OA, and we hypothesize that acupuncture may treat OA by regulating the MCP1/CCR2 axis. This study aimed to explore the effect of acupuncture at points ST35 and ST36 on the effects of hyperalgesia and cartilage in OA rats including the expression of chemokines, nerve growth factor (NGF), and inflammatory-related proteins. OA was induced in male Sprague-Dawley rats by anterior cruciate ligament transection at the right knee. The first acupuncture intervention was performed on the seventh day after surgery and once a day for seven weeks. The knee-pain-related behaviors, histology, and related protein were examined in this study. We have found that electroacupuncture at ST35 and ST36 can significantly alleviate the hyperalgesia and cartilage degeneration as well as reducing nerve sprouting in OA knee joint. Moreover, acupuncture treatment may inhibit the MCP1/CCR2 axis as well as down-regulate inflaming factor and NGF in cartilage and synovial tissue. The data presented here indicate that acupuncture exerts a protective effect against hyperalgesia and cartilage degeneration, and the mechanism might involve in chemokines and NGF pathway.

Association between hyperuricemia, gout, urate lowering therapy, and osteoarthritis: A protocol for a systematic review and meta-analysis

INTRODUCTION

Osteoarthritis (OA), a chronic and degenerative joint disease characterized by articular cartilage degeneration, sclerosis of subchondral bone, and osteophyte formation, is deemed a leading cause of activity limitation and disability among the elderly people. Serum uric acid (UA) is a terminal metabolite of purine compound, while hyperuricemia (HU) and UA crystals are recognized causes of gout. Several studies have investigated the correlations between HU, gout and OA, but the findings are inconclusive. We are also concerned whether the urate lowering therapy (ULT) can become a potential treatment for OA and intend to undertake this meta-analysis to clarify the related hypotheses.

METHODS

Systematic literature search will be conducted on PubMed, Embase, and Web of Science to identify relevant studies up to February 2020 using appropriate search strategies. All citations and abstracts retrieved from literature search will be assessed by two reviewers independently. The Newcastle-Ottawa Scale or the Cochrane risk of bias assessment tool will be used as appropriate to assess the quality and the risk of bias of the included studies. The heterogeneity and the publication bias of the studies will be investigated accordingly.

RESULTS

We propose to undertake this meta-analysis as a feasible approach to clarify the associations between HU, gout or ULT, and OA.

DISCUSSIONS

This meta-analysis will help to strengthen our knowledge of the pathogenesis of OA and promote the development of preventive or treatment strategies.

REGISTRATION

PROSPERO registration number CRD42020168769.

Curcumin reinforces MSC-derived exosomes in attenuating osteoarthritis via modulating the miR-124/NF-kB and miR-143/ROCK1/TLR9 signalling pathways

Curcumin treatment was reported to delay the progression of OA, but its underlying mechanism remains unclear. In this study, we aimed to investigate the molecular mechanism underlying the role of curcumin in OA treatment. Accordingly, by conducting MTT and flow cytometry assays, we found that the exosomes derived from curcumin‐treated MSCs helped to maintain the viability while inhibiting the apoptosis of model OA cells. Additionally, quantitative real‐time PCR and Western blot assays showed that the exosomes derived from curcumin‐treated MSCs significantly restored the down‐regulated miR‐143 and miR‐124 expression as well as up‐regulated NF‐kB and ROCK1 expression in OA cells. Mechanistically, curcumin treatment decreased the DNA methylation of miR‐143 and miR‐124 promoters. In addition, the 3’ UTRs of NF‐kB and ROCK1 were proven to contain the binding sites for miR‐143 and miR‐124, respectively. Therefore, the up‐regulation of miR‐143 and miR‐124 in cellular and mouse OA models treated with exosomes remarkably restored the normal expression of NF‐kB and ROCK1. Consequently, the progression of OA was attenuated by the exosomes. Our results clarified the molecular mechanism underlying the therapeutic role of MSC‐derived exosomes in OA treatment.

Infrapatellar Fat Pad/Synovium Complex in Early-Stage Knee Osteoarthritis: Potential New Target and Source of Therapeutic Mesenchymal Stem/Stromal Cells

The infrapatellar fat pad (IFP) has until recently been viewed as a densely vascular and innervated intracapsular/extrasynovial tissue with biomechanical roles in the anterior compartment of the knee. Over the last decade, secondary to the proposition that the IFP and synovium function as a single unit, its recognized tight molecular crosstalk with emerging roles in the pathophysiology of joint disease, and the characterization of immune-related resident cells with varying phenotypes (e.g., pro and anti-inflammatory macrophages), this structural complex has gained increasing attention as a potential therapeutic target in patients with various knee pathologies including osteoarthritis (KOA). Furthermore, the description of the presence of mesenchymal stem/stromal cells (MSC) as perivascular cells within the IFP (IFP-MSC), exhibiting immunomodulatory, anti-fibrotic and neutralizing activities over key local mediators, has promoted the IFP as an alternative source of MSC for cell-based therapy protocols. These complementary concepts have supported the growing notion of immune and inflammatory events participating in the pathogenesis of KOA, with the IFP/synovium complex engaging not only in amplifying local pathological responses, but also as a reservoir of potential therapeutic cell-based products. Consequently, the aim of this review is to outline the latest discoveries related with the IFP/synovium complex as both an active participant during KOA initiation and progression thus emerging as a potential target, and a source of therapeutic IFP-MSCs. Finally, we discuss how these notions may help the design of novel treatments for KOA through modulation of local cellular and molecular cascades that ultimately lead to joint destruction.

TissueGene-C promotes an anti-inflammatory micro-environment in a rat monoiodoacetate model of osteoarthritis via polarization of M2 macrophages leading to pain relief and structural improvement

Osteoarthritis (OA) is the most common form of arthritis, characterized by cartilage destruction, pain and inflammation in the joints. Existing medications can provide relief from the symptoms, but their effects on the progression of the disease are limited. TissueGene-C (TG-C) is a novel cell and gene therapy for the treatment of OA, comprising a mixture of human allogeneic chondrocytes and irradiated cells engineered to overexpress transforming growth factor-β1 (TGF-β1). This study aims to investigate the efficacy and mechanism of action of TG-C in a rat model of OA. Using the monosodium-iodoacetate (MIA) model of OA, we examined whether TG-C could improve OA symptoms and cartilage structure in rats. Our results showed that TG-C provided pain relief and cartilage structural improvement in the MIA OA model over 56 days. In parallel with these long-term effects, cytokine profiles obtained on day 4 revealed increased expression of interleukin-10 (IL-10), an anti-inflammatory cytokine, in the synovial lavage fluid. Moreover, the increased levels of TGF-β1 and IL-10 caused by TG-C induced the expression of arginase 1, a marker of M2 macrophages, and decreased the expression of CD86, a marker of M1 macrophages. These results suggest that TG-C exerts a beneficial effect on OA by inducing a M2 macrophage-dominant micro-environment. Cell therapy using TG-C may be a promising strategy for targeting the underlying pathogenic mechanisms of OA, reducing pain, improving function, and creating a pro-anabolic micro-environment. This environment supports cartilage structure regeneration and is worthy of further evaluation in future clinical trials.

Resveratrol counteracts IL-1β-mediated impairment of extracellular matrix deposition in 3D articular chondrocyte constructs

When aiming at cell-based therapies in osteoarthritis (OA), proinflammatory conditions mediated by cytokines such as IL-1β need to be considered. In recent studies, the phytoalexin resveratrol (RSV) has exhibited potent anti-inflammatory properties. However, long-term effects on 3D cartilaginous constructs under inflammatory conditions with regard to tissue quality, especially extracellular matrix (ECM) composition, have remained unexplored. Therefore, we employed long-term model cultures for cell-based therapies in an in vitro OA environment and evaluated effects of RSV. Pellet constructs made from expanded porcine articular chondrocytes were cultured with either IL-1β (1-10 ng/ml) or RSV (50 μM) alone, or a cotreatment with both agents. Treatments were applied for 14 days, either directly after pellet formation or after a preculture period of 7 days. Culture with IL-1β (10 ng/ml) decreased pellet size and DNA amount and severely compromised glycosaminoglycan (GAG) and collagen content. Cotreatment with RSV distinctly counteracted the proinflammatory catabolism and led to partial rescue of the ECM composition in both culture systems, with especially strong effects on GAG. Marked MMP13 expression was detected in IL-1β-treated pellets, but none upon RSV cotreatment. Expression of collagen type I was increased upon IL-1β treatment and still observed when adding RSV, whereas collagen type X, indicating hypertrophy, was detected exclusively in pellets treated with RSV alone. In conclusion, RSV can counteract IL-1β-mediated degradation and distinctly improve cartilaginous ECM deposition in 3D long-term inflammatory cultures. Nevertheless, potential hypertrophic effects should be taken into account when considering RSV as cotreatment for articular cartilage repair techniques.

Oxytocin Controls Chondrogenesis and Correlates with Osteoarthritis

This study investigated the relationship of oxytocin (OT) to chondrogenesis and osteoarthritis (OA). Human bone marrow and multipotent adipose-derived stem cells were cultured in vitro in the absence or presence of OT and assayed for mRNA transcript expression along with histological and immunohistochemical analyses. To study the effects of OT in OA in vivo, a rat model and a human cohort of 63 men and 19 women with hand OA and healthy controls, respectively, were used. The baseline circulating OT, interleukin-6, leptin, and oestradiol levels were measured, and hand X-ray examinations were performed for each subject. OT induced increased aggrecan, collagen (Col) X, and cartilage oligomeric matrix protein mRNA transcript levels in vitro, and the immunolabelling experiments revealed a normalization of Sox9 and Col II protein expression levels. No histological differences in lesion severity were observed between rat OA groups. In the clinical study, a multivariate analysis adjusted for age, body mass index, and leptin levels revealed a significant association between OA and lower levels of OT (odds ratio = 0.77; p = 0.012). Serum OT levels are reduced in patients with hand OA, and OT showed a stimulatory effect on chondrogenesis. Thus, OT may contribute to the pathophysiology of OA.

Decreased Serum Adiponectin Reflects Low Vitamin D, High Interleukin 6, and Poor Physical Performance in Knee Osteoarthritis

Obesity is a major contributor to deterioration of physical function toward sarcopenia in knee osteoarthritis (OA) due to its effect mediated through adipokines-derived molecules that have pro-/anti-inflammatory properties. This study aimed to investigate relationships of serum adiponectin, 25-hydroxyvitamin D (25(OH)D), interleukin (IL)-6, and physical performance in knee OA patients. A total of 175 knee OA patients and 52 healthy controls were recruited. Serum adiponectin, 25(OH)D, IL-6, biochemical markers, knee pain and functional scores, muscle strength, physical performance, metabolic parameters, and body composition were evaluated. Serum adiponectin levels were significantly higher in knee OA patients than that in controls, while its serum levels were significantly decreased in obese patients, especially those with sarcopenia. Furthermore, there were independent relationships of serum adiponectin with body composition parameters, knee pain scores, physical function tests, and metabolic parameters in knee OA patients. Besides, serum adiponectin levels were positively associated with 25(OH)D levels, and negatively correlated with C-reactive protein and IL-6 levels in knee OA. Additionally, low serum adiponectin could be used to distinguish knee OA patients with sarcopenic obesity from those without sarcopenic obesity. Circulating adiponectin levels may serve as a possible surrogate biomarker for exacerbated physical function in knee OA patients-particularly sarcopenic obesity.

Tumor Necrosis Factor Receptor Associated Factor 3 Modulates Cartilage Degradation through Suppression of Interleukin 17 Signaling

Interleukin 17A (IL-17A) is critical in the pathogenesis of autoimmune diseases through driving inflammatory cascades. However, the role of IL-17 in osteoarthritis (OA) is not well understood. Tumor necrosis factor-receptor-associated factor 3 (TRAF3) is a receptor proximal negative regulator of IL-17 signaling. It remains unclear whether TRAF3 exerts regulatory effects on cartilage degradation and contributes to the pathogenesis of OA. In this study, we found that TRAF3 notably suppressed IL-17-induced NF-κB and mitogen-activated protein kinase activation and, subsequently, the production of matrix-degrading enzymes. TRAF3 depletion enhanced IL-17 signaling, along with increased matrix-degrading enzyme production. In vivo, cartilage destruction caused by surgery-induced OA was alleviated markedly both in 1l17a-deficient mice and in TRAF3 transgenic mice. In contrast, silencing TRAF3 through adenoviruses worsened cartilage degradation in experimental OA. Moreover, the destructive effect of IL-17 on cartilage was abolished in TRAF3 transgenic mice in an IL-17 intra-articular injection animal model. Similarly, genetic deletion of IL-17 blocked TRAF3 knockdown-mediated promotion of cartilage destruction, suggesting that the protective effect of TRAF3 on cartilage is mediated by its suppression of IL-17 signaling. Collectively, our results suggest that TRAF3 negatively regulates IL-17-mediated cartilage degradation and pathogenesis of OA, and may serve as a potential new therapy target for OA.

The protective effect of myricitrin in osteoarthritis: An in vitro and in vivo study

Osteoarthritis (OA) is a long-term, chronic, progressive joint condition caused by a pathology characterized by the deterioration of joint cartilage and proliferation of subchondral bone. Myricitrin (Myr) is a flavonoid compound extracted from myrica rubra with potent anti-inflammatory properties, as demonstrated in various studies. However, the mechanisms by which Myr plays a protective role in OA are not completely understood. In this study, the anti-inflammatory properties and potential mechanisms of Myr on mouse chondrocytes treated with interleukin (IL) -1beta (β) were explored in vitro and the role of Myr in a mouse model of OA in vivo. The production of pro-inflammatory factors, such as IL-6, tumor necrosis factor alpha (TNF-α), prostaglandin E2 (PGE2) and nitric oxide (NO) were assessed by enzyme linked immunosorbent assay (ELISA) and the Griess reaction. Protein expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), Collagen-II, matrix metalloproteinase(MMP)-13, MMP-3, thrombospondin motifs 5(ADAMTS5), inhibitor ofnuclear factor kappa-B (IκB), p-IκB, p65, p-p65, c-jun-terminal kinase (JNK), p-JNK, extracellular regulated protein kinases (ERK), p-ERK, p38 and p-p38 were quantified using Western blot analysis. In the present study, we found that Myr inhibited IL-1β-induced production of NO and PGE2, expression of MMP-13, MMP-3 and ADAMTS5 and degradation of collagen-II in mouse chondrocytes. Mechanistically, Myr inhibited the activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) treated with IL-1β in mouse chondrocytes. In vivo, Myr decreased OA Research Society International (OARSI) scores in a surgically-induced mouse model of OA. These data suggest that Myr could be developed as a potential therapyfor OA.

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

OA is quite common in companion animals, especially in large breed dogs and horses. Collagen, the most abundant protein of mammals, has specific connective tissue types for skin, bones, reticulate, basal lamina, bones, cell surfaces, while type II collagen (UC-II) forms the main structure of cartilage tissue. Even at the smaller dosages, UC-II has also been reported to be more effective than the glucosamine and chondroitin sulfate supplements, which are the supplements most frequently used in the market. In this review, we summarize the effects of UC-II on joint health and function in health and disease conditions in companion animals.

Osteoarthritis is Prevented in Rats by Verbascoside via Nuclear Factor kappa B (NF-κB) Pathway Downregulation

Background

Cartilage degeneration during osteoarthritis (OA) most adversely affects the quality of life by hindering the movement. The present study investigated the role of verbascoside in the protection of cartilage degeneration induced by osteoarthritis.

Material/Methods

The enzyme-linked immunosorbent (ELISA) and western blot assays were used for determination of inflammatory cytokine secretion in serum and cartilage tissues, respectively.

Results

Treatment of the OA rats with verbascoside inhibited overproduction of interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-1β in serum as well as cartilage tissues. The expression of P2X7R and matrix metalloproteinase (MMP)-13 was much higher in the rats induced with OA. However, administration of verbascoside reversed the OA-induced upregulation of P2X7R and MMP-13 expression in the cartilage tissues. The OA-mediated increase in substance P (SP) and prostaglandin E2 (PGE2) expression was also reduced in the cartilage tissues by the verbascoside treatment. Western blot assay revealed that verbascoside treatment markedly decreased the activation of IκBα and NF-κB p65 in the OA rats.

Conclusions

Thus, verbascoside inhibited inflammatory cytokine secretion in the OA rats by targeting P2X7R expression, production of matrix metalloproteinase, PGE2 and downregulation of NF-κB signaling pathway. Therefore, verbascoside may be used as potent agent for osteoarthritis treatment.

Oral intake of Streptococcus thermophil us improves knee osteoarthritis degeneration: A randomized, double-blind, placebo-controlled clinical study

This preliminary clinical study demonstrates the possibility of a new species of probiotic for improvement of the degeneration of knee osteoarthritis (KOA). TCI633 (Streptococcus thermophil us) is a newly founded bacterium from human breast milk, and it is able to produce hyaluronate (HA) in gastrointestinal (GI) tract. A recent study has proved that TCI633 can substantially alleviate synovial tissue inflammation and cartilage damage in the animal models, but so far it has never been applied in clinical intervention. In this study, we recruited 80 subjects and conducted 12 weeks clinical trial to validate the efficacy of TCI633 for improvement of the progression of KOA. TCI633 could improve serum collagen type II C-telopeptide (sCTX-II) and serum C-reactive protein (sCRP) by 41.58% and 39.58%, respectively, after the study. The improvement rates for sCTX-II and sCRP in TCI633 group were 54% and 57%, respectively, at 12 weeks. Compared to the results of placebo, the indistinct improvement progresses of sCTX-II and sCRP might be caused by the uneventful distribution of K/L populations between the TCI633 and placebo groups, a short term of study period, and few recruited subjects. Moreover, the results of Western Ontario and McMaster Universities (WOMAC) questionnaires show that TCI633 might retard the progression and development of KOA after the trial. In brief, this preliminary research may provide an alternative approach to the improvement of KOA by probiotics although more detailed investigations should be conducted for solid conclusions.

Autologous conditioned serum: clinical and functional results using a novel disease modifying agent for the management of knee osteoarthritis

Objective: The purpose of this study was to investigate the potential ability of autologous conditioned serum (ACS) to decrease pain and improve joint functionality in patients affected by knee osteoarthritis (OA). Methods: Fifteen patients with clinical and radiological signs of OA of the knee were recruited for this study. Each patient received 4 injections of ACS (Orthokine; orthogen, Dusseldorf, Germany) at the site of OA once per week for 4 weeks. Clinical and functional evaluation was performed using the VAS scale for pain, WOMAC scale and KSS functional and clinical scores before the first injection, at one week, at two weeks, at three weeks, at one month and at six months. Statistical analysis was done with the Wilcoxon Signed-Rank Test. Results: Our results show an improvement of all the evaluation scales at 6 months follow-up. Particularly, VAS scales among all patients decreased by 35.8% (p = .00148), KSS functional scores improved by 38.2% (p = .00148), KSS clinical scores improved by 28.9% (p = .00236) and WOMAC scores were reduced by 19.8% (p = .00188). Few adverse effects were observed in our sample. The most common complaint was pain and swelling in the subsequent days after performing the intra-articular injection. Only one patient reported rigidity following the injection of the ACS. Conclusion: Our results, in conjunction with preexisting studies in the medical literature regarding ACS, demonstrate the viability of this therapy for the treatment of knee OA, showing positive influence on pain and joint function without significant adverse effects.

Promotion of G1/S Transition and Inhibition of Inflammatory Cytokine Production by Hydroxypyridinone-Coumarin in Osteoarthritis Rats

BACKGROUND Osteoarthritis is a joint disorder characterized by articular cartilage degradation leading to joint stiffness and pain. The present study investigated the effect of hydroxypyridinone-coumarin on proliferation of chondrocytes. MATERIAL AND METHODS Chondrocyte proliferation was assessed by MTT assay, and distribution of cells in various phases of the cell cycle was determined using flow cytometry. RT-PCR and Western blot assays were used for assessment of mRNA and protein levels, respectively. Osteoarthritis was induced in the rats by injecting monosodium iodoacetate (5 mg/kg) by the intra-articular route. The rats in the treatment groups were intraperitoneally injected with 5, 10, or 15 mg/kg doses of hydroxypyridinone-coumarin alternately for 1 month. RESULTS The proliferation of chondrocytes was increased significantly (P<0.05) by treatment with hydroxypyridinone-coumarin in a concentration-based manner. The increase in chondrocyte proliferation by hydroxypyridinone-coumarin was maximum at 50 µM. Treatment with hydroxypyridinone-coumarin markedly increased chondrocyte population in S and G2/M phases, with subsequent reduction in G0/G1 phase. The cyclin D1, CDK4, and CDK6 levels in the chondrocytes were increased by treatment with hydroxypyridinone-coumarin. The production of IL-6, TNF-alpha, and IL-1ß in the osteoarthritis rats was markedly suppressed by hydroxypyridinone-coumarin. Treatment of the OA rats with hydroxypyridinone-coumarin markedly reduced the expression of IkappaB-alpha and NF-kappaB p65. CONCLUSIONS The present study revealed that the proliferative potential of chondrocytes is increased by hydroxypyridinone-coumarin through acceleration of G1/S transition. Moreover, hydroxypyridinone-coumarin treatment reduced inflammatory cytokine production in the osteoarthritis rats. Therefore, hydroxypyridinone-coumarin should be evaluated further for possible use in the treatment of osteoarthritis.

COL2A1 and Caspase-3 as Promising Biomarkers for Osteoarthritis Prognosis in an Equus asinus Model

Osteoarthritis (OA) is one of the most degenerative joint diseases in both human and veterinary medicine. The objective of the present study was the early diagnosis of OA in donkeys using a reliable grading of the disease based on clinical, chemical, and molecular alterations. OA was induced by intra-articular injection of 25 mg monoiodoacetate (MIA) as a single dose into the left radiocarpal joint of nine donkeys. Animals were clinically evaluated through the assessment of lameness score, radiographic, and ultrasonographic findings for seven months. Synovial fluid and cartilage samples were collected from both normal and diseased joints for the assessment of matrix metalloproteinases (MMPs) activity, COL2A1 protein expression level, and histopathological and immunohistochemical analysis of Caspase-3. Animals showed the highest lameness score post-induction after one week then decreased gradually with the progression of radiographical and ultrasonographic changes. MMP activity and COL2A1 and Caspase-3 expression increased, accompanied by articular cartilage degeneration and loss of proteoglycan. OA was successfully graded in Egyptian donkeys, with the promising use of COL2A1and Caspase-3 for prognosis. However, MMPs failed to discriminate between early and late grades of OA.

The Secretome Derived From Mesenchymal Stromal Cells Cultured in a Xeno-Free Medium Promotes Human Cartilage Recovery in vitro

Osteoarthritis (OA) is a disabling joint disorder causing articular cartilage degeneration. Currently, the treatments are mainly aimed to pain and symptoms relief, rather than disease amelioration. Human bone marrow stromal cells (hBMSCs) have emerged as a promising paracrine mechanism-based tool for OA treatment. Here, we investigate the therapeutic potential of conditioned media (CM) and extracellular vesicles (EVs) isolated from hBMSC and grown in a xeno-free culture system (XFS) compared to the conventional fetal bovine serum-culture system (FBS) in an in vitro model of OA. First, we observed that XFS promoted growth and viability of hBMSCs compared to FBS-containing medium while preserving their typical phenotype. The biological effects of the CM derived from hBMSC cultivated in XFS- and FBS-based medium were tested on IL-1α treated human chondrocytes, to mimic the OA enviroment. Treatment with CM derived from XFS-cultured hBMSC inhibited IL-1α-induced expression of IL-6, IL-8, and COX-2 by hACs compared to FBS-based condition. Furthermore, we observed that hBMSCs grown in XFS produced a higher amount of EVs compared to FBS-culture. The hBMSC-EVs not only inhibit the adverse effects of IL-1α-induced inflammation, but play a significant in vitro chondroprotective effect. In conclusion, the XFS medium was found to be suitable for isolation and expansion of hBMSCs with increased safety profile and intended for ready-to-use clinical therapies.

New Molecular Targets in the Therapy of Arthrosis Patients

Introduction: Arthrosis represents the progressive degeneration of the joint cartilage, accompanied by the narrowing of the articular space and inflammation, which affects 70% of the population after the age of 60. Research purpose: This paper reviews the opportunity of using proinflammatory cytokine inhibitors as a means of stopping the progress of arthrosis. Material and method: As a result to a research into various clinical trial registers (Arthritis Clinical Trials, Clinical Research and Drug Information) and on specialized e-platforms, 5 randomized, multicentric double-blind clinical studies have been identified, which monitored the efficiency of various biological molecules in the treatment of arthrosis (etanercept, adalimumab, litikizumab, fasinumab and tanezumab). Results: The current pharmacological interventions consist mainly in the prescription of analgesics (acetaminophen, opioid analgesics), non-steroidal and chondroprotective anti-inflammatories. The proinflammatory cytokine inhibitors are already widely used in the inflammatory joint diseases, such as the rheumatoid polyarthritis. Their introduction into the treatment of arthrosis blocks the disease’s etiopathogenic mechanisms. Discussions: Arthrosis physiopathology involves a series of systemic, biological, biochemical factors, molecular and enzymatic processes that generate minimum inflammation. IL-1b and TNF-α are two major cytokines produced by the synovial cells and chondrocytes, which are involved in the destruction of the cartilage matrix by stimulating the production of proteolytic enzymes (MMP and aggrecanase). Conclusions: The utilisation of proinflammatory cytokine inhibitors in arthrosis represents a therapeutic option that requires studies in order to establish whether the introduction of proinflammatory cytokine inhibitors in arthrosis therapy might slow down the disease’s etiopathogenic mechanisms.

Comparative Effect between Infiltration of Platelet-rich Plasma and the Use of Corticosteroids in the Treatment of Knee Osteoarthritis: A Prospective and Randomized Clinical Trial

Objectives  This study aimed to analyze the efficacy of platelet-rich plasma obtained from the peripheral, autologous blood of the patients in pain complaints reduction and functional improvement of knee osteoarthritis compared with the standard treatment with injectable corticosteroid, such as triamcinolone.

Methods  The patients were followed-up clinically at the preinfiltrative visit, with quantitative evaluation using the Knee Society Score (KSS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and the Kellgren and Lawrence scales. In addition, they were reevaluated with the same scales after 1 month and 6 months of intervention with 2.5 mL of triamcinolone acetate or 5 mL of platelet-rich plasma. The study was performed on 50 patients with knee osteoarthritis treated at the Medical Specialty Center and randomly divided into equivalent samples for each therapy.

Results  The present study verified the reduction of pain scores, such as the WOMAC score, and elevations of functional scales, such as the KSS, evidenced in 180 days when using platelet-rich plasma, a therapy that uses the autologous blood of the patient and has fewer side effects.

Conclusion  Although both platelet-rich plasma and corticosteroid therapies have been shown to be effective in the reduction pain complaints and functional recovery, there was a statistically significant difference between them at 180 days. According to the results obtained, platelet-rich plasma presented longer-lasting effects within 180 days in the treatment of knee osteoarthritis.

Acute Synovitis after Trauma Precedes and is Associated with Osteoarthritis Onset and Progression

Osteoarthritis (OA) is a whole-joint disease characterized by cartilage destruction, subchondral bone sclerosis, osteophyte formation, and synovitis. However, it remains unclear which part of the joint undergoes initial pathological changes that drives OA onset and progression. In the present study, we investigated the longitudinal alterations of the entire knee joint using a surgically-induced OA mouse model. Histology analysis showed that synovitis occurred as early as 1 week after destabilization of the medial meniscus (DMM), which preceded the events of cartilage degradation, subchondral sclerosis and osteophyte formation. Importantly, key pro-inflammatory cytokines such as IL-1β, IL-6, TNFα, and Ccl2, major matrix degrading enzymes including Adamts4, Mmp3 and Mmp13, as well as nerve growth factor (NGF), all increased significantly in both synovium and articular cartilage. It is notable that the inductions of these factors in synovium are far more extensive than those in articular cartilage. Results from behavioral tests demonstrated that sensitization of knee joint pain developed after 8 weeks, later than histological and molecular changes. In addition, the nanoindentation modulus of the medial tibiae decreased 4 weeks after DMM surgery, simultaneous with histological OA signs, which is also later than appearance of synovitis. Collectively, our data suggested that synovitis precedes and is associated with OA, and thus synovium may be an important target to intervene in OA treatment.

NF-κB Phosphorylation Inhibition Prevents Articular Cartilage Degradation in Osteoarthritis Rats via 2-Aminoquinoline

Background

Osteoarthritis is a chronic degenerative disease of the joints that is common in older people worldwide. The characteristic features of osteoarthritis include cartilage degradation, synovitis, and remodelling of subchondral bone. The present study investigated the effect of 2-aminoquinoline on knee articular cartilage degradation in an osteoarthritis rat model.

Material/Methods

The rat model of osteoarthritis was established in Wistar rats by intra-articular injection of monosodium iodoacetate. The rats were randomly divided into 6 groups of 10 rats each: a normal control group, an untreated group, and 4 (5, 10, 15 and 20 mg/kg) treatment groups. The rats in treatment groups received 5, 10, 15, or 20 mg/kg doses of 2-aminoquinoline on day 2 of monosodium iodoacetate injection.

Results

The 2-aminoquinoline treatment of monosodium iodoacetate-injected rats markedly decreased weight-bearing asymmetry, inhibited edema formation, and improved paw withdrawal thresholds. The expression of inflammatory cytokines was markedly higher in the osteoarthritis rats. Treatment with 2-aminoquinoline led to a significant reduction in inflammatory cytokine expression in osteoarthritis rats in a dose-dependent manner. In osteoarthritis rats, the expressions of prostaglandin E2 (PGE2), matrix metalloproteinase-13 (MMP-13), and substance P were also higher in comparison to the control group. The 2-aminoquinoline treatment supressed PGE2, MMP-13, and substance P levels in osteoarthritis rats. Moreover, the expression of phosphorylated nuclear factor kappaB (p-NF-κB) was markedly higher in the untreated rats. However, activation of NF-κB was downregulated in the osteoarthritis rats by treatment with 2-aminoquinoline.

Conclusions

The present study demonstrated that 2-aminoquinoline prevents articular cartilage damage in osteoarthritis rats through inhibition of inflammatory factors and downregulation of NF-κB activation, suggesting that 2-aminoquinoline would be effective in treatment of osteoarthritis.

Identification and functional analysis of long non-coding RNAs in the synovial membrane of osteoarthritis patients

Osteoarthritis (OA), the most common chronic joint disease in the elderly, has become a significant economic burden for families and societies worldwide. Although treatments are continually improving, current drugs only target joint pain, with no effective therapies modifying OA progression. Long noncoding RNAs (lncRNAs), which have received increasing attention in recent years, are abnormally expressed in OA cartilage. In the present study, weighted coexpression network analysis (WGCNA) was applied to identify modules related to certain OA clinical traits. In total, 4404 coding genes and 161 lncRNAs were differentially expressed based on two OA expression profile data sets and normal control samples. Subsequently, 11 independent modules were acquired, and the green module, with a total of 49 hub genes, was identified as the most relevant to OA. These hub genes were validated using the GSE12021 data set. There was only one lncRNA among the hub genes, namely, NONHSAG034351. Thus, we further explored the function of NONHSAG034351‐related genes in the network. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that NONHSAG034351‐associated genes are involved in the response to lipopolysaccharide, angiogenesis, tumour necrosis factor (TNF) signalling, and mitogen‐activated protein kinase (MAPK) signalling pathways. In conclusion, we identified modules through WGCNA related to OA clinical traits. NONHSAG034351, the only hub‐lncRNA, was downregulated in OA synovial tissue and might play a significant role in the pathological progression of this disease. Our findings have important clinical implications and could provide novel biomarkers that indicate the molecular mechanisms of OA and act as potential therapeutic targets.

Significance of this study

Long noncoding RNAs (lncRNAs) have been reported to be abnormally expressed in osteoarthritis (OA), which is the most common chronic joint disease among the elderly. In the present study, we report the expression profiles of lncRNAs in OA and the identification of modules through WGCNA related to OA clinical traits. NONHSAG034351, the only hub‐lncRNA identified to be downregulated in the synovial tissue of OA patients, might play a significant role in the pathological progression of OA. Furthermore, our findings provide novel biomarkers associated with the molecular mechanisms underlying OA pathogenesis, thus implying potential therapeutic targets with important clinical implications.

Human Synovia Contains Trefoil Factor Family (TFF) Peptides 1-3 Although Synovial Membrane Only Produces TFF3: Implications in Osteoarthritis and Rheumatoid Arthritis

Objective: Trefoil factor family peptide 3 (TFF3) has been shown to support catabolic functions in cases of osteoarthritis (OA). As in joint physiology and diseases such as OA, the synovial membrane (SM) of the joint capsule also plays a central role. We analyze the ability of SM to produce TFF compare healthy SM and its secretion product synovial fluid (SF) with SM and SF from patients suffering from OA or rheumatoid arthritis (RA). Methods: Real-time PCR and ELISA were used to measure the expression of TFFs in healthy SM and SM from patients suffering from OA or RA. For tissue localization, we investigated TFF1-3 in differently aged human SM of healthy donors by means of immunohistochemistry, real-time PCR and Western blot. Results: Only TFF3 but not TFF1 and -2 was expressed in SM from healthy donors as well as cases of OA or RA on protein and mRNA level. In contrast, all three TFFs were detected in all samples of SF on the protein level. No significant changes were observed for TFF1 at all. TFF2 was significantly upregulated in RA samples in comparison to OA samples. TFF3 protein was significantly downregulated in OA samples in comparison to healthy samples and cases of RA significantly upregulated compared to OA. In contrast, in SM TFF3 protein was not significantly regulated. Conclusion: The data demonstrate the production of TFF3 in SM. Unexpectedly, SF contains all three known TFF peptides. As neither articular cartilage nor SM produce TFF1 and TFF2, we speculate that these originate with high probability from blood serum.

Quercetin alleviates rat osteoarthritis by inhibiting inflammation and apoptosis of chondrocytes, modulating synovial macrophages polarization to M2 macrophages

Osteoarthritis (OA) is a progressive joint disorder that is primarily characterized by the degeneration and destruction of the articular cartilage. Cartilage matrix degradation, production of proinflammatory mediators, chondrocyte apoptosis and activation of macrophages in the synovial are involved in OA pathogenesis. Current non-surgical therapies for OA mainly aim at relieving pain but can barely alleviate the progression of OA. Quercetin, a naturally occurring flavonoid has shown potent anti-inflammatory effects, however, its effects and underlying mechanisms on OA have seldom been systematically illuminated. In this study, we explored the protective effects of quercetin on repairing OA-induced cartilage injuries and its possible mechanisms. In vitro, quercetin remarkably suppressed the expression of matrix degrading proteases and inflammatory mediators, meantime promoted the production of cartilage anabolic factors in interleukin-1β-induced (IL-1β) rat chondrocytes. In addition, quercetin exhibited anti-apoptotic effects by decreasing intracellular reactive oxygen species (ROS), restoring mitochondrial membrane potential (MMP) and inhibiting the Caspase-3 pathway in apoptotic rat chondrocytes. Moreover, quercetin induced M2 polarization of macrophages and upregulated the expression of transforming growth factor β (TGF-β) and insulin-like growth factor (IGF), which in turn created a pro-chondrogenic microenvironment for chondrocytes and promoted the synthesis of glycosaminoglycan (GAG) in chondrocytes. In vivo, intra-articular injection of quercetin alleviated the degradation of the cartilage and the apoptosis of chondrocytes in a rat OA model. Moreover, the expression of TGF-β1 and TGF-β2 in the synovial fluid and the ratio of M2 macrophages in the synovial membrane were elevated. In summary, our study proves that quercetin exerts chondroprotective effects by inhibiting inflammation and apoptosis of chondrocytes, modulating synovial macrophages polarization to M2 macrophages and creating a pro-chondrogenic environment for chondrocytes to enhance cartilage repair under OA environment. It is suggested that quercetin may serve as a potential drug for OA treatment.

Accelerated post traumatic osteoarthritis in a dual injury murine model

OBJECTIVE

Joint injury involving destabilisation of the joint and damage to the articular cartilage (e.g., sports-related injury) can result in accelerated post-traumatic osteoarthritis (PTOA). Destabilised medial meniscotibial ligament (DMM) surgery is one of the most commonly used murine models and whilst it recapitulates Osteoarthritis (OA) pathology, it does not necessarily result in multi-tissue injury, as occurs in PTOA. We hypothesised that simultaneous cartilage damage and joint destabilisation would accelerate the onset of OA pathology.

METHODS

OA was induced in C57BL/6 mice via (a) DMM, (b) microblade scratches of articular cartilage (CS) or (c) combined DMM and cartilage scratch (DCS). Mice were culled 7, 14 and 28 days post-surgery. Microcomputed tomography (μCT) and histology were used to monitor bone changes and inflammation. Dynamic weight bearing, an indirect measure of pain, was assessed on day 14.

RESULTS

Osteophytogenesis analysis via μCT revealed that osteophytes were present in all groups at days 7 and 14 post-surgery. However, in DCS, osteophytes were visually larger and more numerous when compared with DMM and cartilage scratch (CS). Histological assessment of cartilage at day 14 and 28, revealed significantly greater damage in DCS compared with DMM and CS. Furthermore, a significant increase in synovitis was observed in DCS. Finally, at day 14 osteophyte numbers correlated with changes in dynamic weight bearing.

CONCLUSION

Joint destabilisation when combined with simultaneous cartilage injury accelerates joint deterioration, as seen in PTOA. Thus, DCS provides a novel and robust model for investigating multiple pathological hallmarks, including osteophytogenesis, cartilage damage, synovitis and OA-related pain.

Downregulating Akt/NF-κB signaling and its antioxidant activity with Loureirin A for alleviating the progression of osteoarthritis: In vitro and vivo studies

Osteoarthritis(OA) is one of the most common diseases in orthopedics. It is characterized by degeneration of articular cartilage and chronic inflammation. In this study, we aim to elucidate the mechanism of Loureirin A's therapeutic effect in OA progression. In vitro, Loureirin A pretreatment can significantly inhibit production of NO, PGE2, COX-2, TNF-α, iNOS andIL-6 induced by IL-1β in mouse articular chondrocytes. Moreover, Loureirin A suppressed the expression of matrix metalloproteinase-9(MMP-9), which leads to degradation of the extracellular matrix. The degradation of aggrecan and type II collagen protein in the extracellular matrix (ECM) stimulated by IL-1β was reversed. For signal pathway research, Loureirin A dramatically inhibited the phosphorylation of AKT and subsequent NF-κB entering into the nucleus caused by IL-1β in chondrocytes. Besides, a number of related indicators suggested that Loureirin A has a strong antioxidant activity in the treatment of osteoarthritis via increasing content of SOD2 and suppressing MDA and ROS. In addition, in vivo study demonstrated that Loureirin A could ameliorated the progression of OA in mice DMM model In conclusion, all results showed that Loureirin A may be a potential therapeutic candidate for the OA.

Angiopoietin-like 2 upregulation promotes human chondrocyte injury via NF-κB and p38/MAPK signaling pathway

Several cellular and molecular processes participate in the pathologic changes of osteoarthritis (OA). However, the core molecular regulators of these processes are unclear, and no effective treatment for OA disease has been developed so far. ANGPTL2 is well known for its tissue remolding and pro-inflammation properties. However, the role of ANGPTL2 in osteoarthritis (OA) still remains unclear. To explore the expression level of ANGPTL2 in human OA cartilage and investigate the function of ANGPTL2 in human chondrocytes injury, qRT-PCR, western blot and immunohistochemistry were employed to investigate the expression of ANGPTL2 between human OA and normal cartilage samples. Next, human primary chondrocytes were treated with IL-1β to mimic OA progress in vitro, and the expression of ANGPTL2 were tested by qRT-PCR and western blot. Furthermore, the effect of ANGPTL2 in the expression of pro-inflammation cytokines (IL-1β, IL-6), proteolytic enzymes (MMP-1, MMP-13) and component of the cartilage matrix (COL2A1 and aggrecan) in human primary chondrocyte were explored by gain-of-function and loss-of-function methods. Finally, the nuclear factor kappa B (NF-κB) and p38/MAPK signaling pathways were also tested by western blot analysis. In this study, firstly, the expression level of ANGPTL2 was elevated both in human OA cartilage samples and IL-1β stimulated human chondrocytes. Secondly, ANGPTL2 upregulation promotes extracellular matrix (ECM) degradation and inflammation mediator production in human chondrocytes. Finally, ANGPTL2 activated the NF-κB and p38/MAPK signaling pathways via integrin α5β1. This study, for the first time, highlights that ANGPTL2 secreted by human chondrocytes plays a negative role in the pathogenesis of osteoarthritis, and it may be a potential therapeutic target in OA.

Long Non-Coding RNA (LncRNA) CAIF is Downregulated in Osteoarthritis and Inhibits LPS-Induced Interleukin 6 (IL-6) Upregulation by Downregulation of MiR-1246

Background

Osteoarthritis (OA) affects about 40% of people older than 40 years of age, and the mechanism is not well understood. Long non-coding RNA (lncRNA) CAIF is a recently identified critical player in myocardial infarction, while its role in other human diseases is unclear. The present study aimed to investigate the role of CAIF in OA.

Material/Methods

Levels of CAIF in synovial fluid of OA patients (n=60) and healthy controls (n=60) were measuring by performing quantitative real-time polymerase chain reaction (qRT-PCR). MiR-1246 and interleukin (IL)-6 levels in synovial fluid were measured by performing qRT-PCR and enzyme-linked immunosorbent assay (ELISA), respectively. Cell apoptosis analysis was performed after CHON-001 cells were treated with 500 mg/mL lipopolysaccharide (LPS) for 24 hours.

Results

We found that CAIF in synovial fluid was downregulated in OA patients and inversely correlated with miR-1246 and IL-6. Downregulated CAIF distinguished OA patients from healthy controls. In cells of chondrogenic cell line CHON-001, CAIF overexpression mediated the inhibited expression of miR-1246 and secretion of IL-6, while miR-1246 overexpression reduced the effects of CAIF overexpression on IL-6 secretion. In addition, CAIF overexpression inhibited the apoptosis of CHON-001 cells under LPS treatment, while miR-1246 overexpression attenuated the effects of CAIF overexpression.

Conclusions

Therefore, CAIF may downregulate miR-1246 to improve OA.

Quantitative Signal Intensity Alteration in Infrapatellar Fat Pad Predicts Incident Radiographic Osteoarthritis: The Osteoarthritis Initiative

OBJECTIVE

To determine whether infrapatellar fat pad (IPFP) signal intensity measures are predictive of incident radiographic osteoarthritis (ROA) over 4 years in the Osteoarthritis Initiative study.

METHODS

Case knees (n = 355), as defined by incident ROA, were matched 1:1 with control knees, according to sex, age, and radiographic status. T2-weighted magnetic resonance images were assessed at P0 (the visit when incident ROA was observed on a radiograph), P1 (1 year prior to P0), and baseline and used to assess IPFP signal intensity semiautomatically. Conditional logistic regression analyses were performed to assess the risk of incident ROA associated with IPFP signal intensity alteration, after adjustment for covariates.

RESULTS

The mean age of the participants was 60.2 years, and most (66.7%) were female and overweight (mean body mass index 28.3 kg/m² ). Baseline IPFP measures including the mean value and standard deviation of IPFP signal intensity, the mean value and standard deviation of IPFP high signal intensity, median and upper quartile values of IPFP high signal intensity, and the clustering effect of high signal intensity were associated with incident knee ROA over 4 years. All P1 IPFP measures were associated with incident ROA after 12 months. All P0 IPFP signal intensity measures were associated with ROA.

CONCLUSION

The quantitative segmentation of high signal intensity in the IPFP observed in our study confirms the findings of previous work based on semiquantitative assessment, suggesting the predictive validity of semiquantitative assessment of IPFP high signal intensity. The IPFP high signal intensity alteration could be an important imaging biomarker to predict the occurrence of ROA.

Therapeutic Use of Scoparia dulcis Reduces the Progression of Experimental Osteoarthritis

Pain is recognized as one of the main symptoms in knee osteoarthritis and is the main reason why patients seek medical attention. Scoparia dulcis has been popularly used to relieve discomfort caused by various painful conditions. The objective of the study is to evaluate the analgesic and anti-inflammatory effect of the crude extract of S. dulcis, in an experimental model of osteoarthritis. The experiment was performed with Wistar rats divided into 4 groups with 5 animals each: healthy, saline, crude extract, and meloxicam groups. Knee osteoarthritis was induced by intra-articular injection of sodium mono-iodoacetate. First, clinical parameters of pain were assessed at days 0, 5, 10, 15, and 20 after induction. Second, the potential cyclooxygenase inhibition was evaluated, and the cytokines of the synovial fluid were quantified. An in silico test and Molecular Docking tests were performed. A histopathological evaluation was made on articular cartilage with safranin O staining. The results showed that a 15-day treatment with crude extract reduced edema, spontaneous pain, peripheral nociceptive activity, and proinflammatory cytokines in the synovial fluid. The highest inhibition of cyclooxygenase 2 in the crude extract occurred at 50 µg/mL. The crude extract of S. dulcis presents therapeutic potential for the treatment of osteoarthritis due to its anti-inflammatory and anti-nociceptive action.

Dysregulated integrin αVβ3 and CD47 signaling promotes joint inflammation, cartilage breakdown, and progression of osteoarthritis

Osteoarthritis (OA) is the leading cause of joint failure, yet the underlying mechanisms remain elusive, and no approved therapies that slow progression exist. Dysregulated integrin function was previously implicated in OA pathogenesis. However, the roles of integrin αVβ3 and the integrin-associated receptor CD47 in OA remain largely unknown. Here, transcriptomic and proteomic analyses of human and murine osteoarthritic tissues revealed dysregulated expression of αVβ3, CD47, and their ligands. Using genetically deficient mice and pharmacologic inhibitors, we showed that αVβ3, CD47, and the downstream signaling molecules Fyn and FAK are crucial to OA pathogenesis. MicroPET/CT imaging of a mouse model showed elevated ligand-binding capacities of integrin αVβ3 and CD47 in osteoarthritic joints. Further, our in vitro studies demonstrated that chondrocyte breakdown products, derived from articular cartilage of individuals with OA, induced αVβ3/CD47-dependent expression of inflammatory and degradative mediators, and revealed the downstream signaling network. Our findings identify a central role for dysregulated αVβ3 and CD47 signaling in OA pathogenesis and suggest that activation of αVβ3 and CD47 signaling in many articular cell types contributes to inflammation and joint destruction in OA. Thus, the data presented here provide a rationale for targeting αVβ3, CD47, and their signaling pathways as a disease-modifying therapy.

The Adipokine Network in Rheumatic Joint Diseases

Rheumatic diseases encompass a diverse group of chronic disorders that commonly affect musculoskeletal structures. Osteoarthritis (OA) and rheumatoid arthritis (RA) are the two most common, leading to considerable functional limitations and irreversible disability when patients are unsuccessfully treated. Although the specific causes of many rheumatic conditions remain unknown, it is generally accepted that immune mechanisms and/or uncontrolled inflammatory responses are involved in their etiology and symptomatology. In this regard, the bidirectional communication between neuroendocrine and immune system has been demonstrated to provide a homeostatic network that is involved in several pathological conditions. Adipokines represent a wide variety of bioactive, immune and inflammatory mediators mainly released by adipocytes that act as signal molecules in the neuroendocrine-immune interactions. Adipokines can also be synthesized by synoviocytes, osteoclasts, osteoblasts, chondrocytes and inflammatory cells in the joint microenvironment, showing potent modulatory properties on different effector cells in OA and RA pathogenesis. Effects of adiponectin, leptin, resistin and visfatin on local and systemic inflammation are broadly described. However, more recently, other adipokines, such as progranulin, chemerin, lipocalin-2, vaspin, omentin-1 and nesfatin, have been recognized to display immunomodulatory actions in rheumatic diseases. This review highlights the latest relevant findings on the role of the adipokine network in the pathophysiology of OA and RA.

Inhibiting the PI3K/AKT/NF-κB signal pathway with nobiletin for attenuating the development of osteoarthritis: in vitro and in vivo studies

Osteoarthritis (OA), an age-related degenerative disease, is characterized by progressive degradation of the articular cartilage. There is increasing evidence that nobiletin (NOB) exerts special biological functions in a variety of diseases. However, whether it protects against OA remains unknown. In this study, we investigated the anti-inflammatory and chondroprotective effects of NOB on IL-1β-induced human OA chondrocytes and in the surgical DMM mice OA models. In vitro, NOB treatment completely suppressed the overproduction of pro-inflammatory mediators, including PGE2, NO, COX-2, iNOS, TNF-α and IL-6 in IL-1β-induced human OA chondrocytes. Moreover, NOB exerted a potent inhibitory effect on the expression of MMP-13 and ADAMTS-5 as well as the degradation of aggrecan and collagen-II, which leads to the degradation of the extracellular matrix. Furthermore, NOB dramatically suppressed the IL-1β-stimulated phosphorylation of PI3K/Akt and activation of NF-κB in human OA chondrocytes. In addition, treatment with NOB not only prevented the destruction of cartilage and the thickening of subchondral bone but also relieved synovitis in mice OA models. In conclusion, our study suggests that NOB holds novel therapeutic potential for the treatment of OA.

The role of radiography and MRI for eligibility assessment in DMOAD trials of knee OA

Currently, no disease-modifying osteoarthritis drugs (DMOADs) have been approved. Past clinical trials have failed for several reasons, including the commonly applied definition of eligibility based on radiographic assessment of joint structure. In the context of precision medicine, finding the appropriate patient for a specific treatment approach will be of increasing relevance. Phenotypic stratification by use of imaging at the time of determining eligibility for clinical trials will be paramount and cannot be achieved using radiography alone. Furthermore, identification of joints at high risk of rapid progression of osteoarthritis is needed in order to enable a more efficient DMOAD trial design. In addition, joints at high risk of collapse need to be excluded at screening. The use of MRI might offer advantages over radiography in this context. Technological advances and simplified image assessment address many of the commonly perceived barriers to the application of MRI to assessment of eligibility for DMOAD clinical trials.

Role of Fat-Soluble Vitamins in Osteoarthritis Management

Osteoarthritis (OA) is a chronic degenerative joint disease, in which metabolic imbalance in bone is observed. The pathological mechanism of metabolic imbalance is not clear yet, but the nutritional factors, particularly the vitamins, might be intrinsic to the development and progression of OA. In this review article, we have explored databases such as PubMed, Scopus, and Google Scholar articles until the beginning of 2017 and reviewed the role of fat-soluble vitamins in pathological and therapeutic aspects of OA. Vitamin D plays an important role in the development and maintenance of the skeleton, as well as bone and cartilage metabolism, and its deficiency is implicated in the pathological process of OA. Vitamin E enhances chondrocyte growth and exhibits an anti-inflammatory activity, as well as plays an important role in the prevention of cartilage degeneration. In human OA cartilage, vitamin K deficiency produces abnormal growth plate calcification and inappropriate mineralization of cartilage. Thus, these fat-soluble vitamins play a key role in the pathophysiology of OA, and supplementation of these vitamins may provide innovative approaches for OA management. However, vitamin A has a different role, which is a regulator of cartilage and skeletal formation. When metabolite levels of vitamin A are elevated in synovial fluid, they appear to drive OA development. The role of inhibitors of vitamin A here remains unclear. More investigations are needed to examine the effects of fat-soluble vitamins on the various molecular pathways of OA, as well as to assess the efficacy and safety of their usage clinically.

Association of UCMA levels in serum and synovial fluid with severity of knee osteoarthritis

AIM

Osteoarthritis (OA) is one of the most common joint diseases causing physical disability in the aged population. OA pathogenesis is not fully known and yet there are no effective therapeutic options against OA. Upper Zone of Growth Plate and Cartilage Matrix Associated (UCMA) is a member of vitamin K-dependent protein family, and is involved in inflammation, cardiovascular diseases, cancer, and OA. In the present study, our aim was to detect serum and synovial fluid (SF) levels of UCMA and to analyze their correlation with radiographic findings and symptomatic severity in OA patients as well as the correlation between oxidative stress levels and SF UCMA levels.

METHODS

Forty OA patients with cartilage degeneration and 20 patients with other knee joint disorders (non-OA control) were included in the present study. We used the Kellgren-Lawrence (KL) classification and Western Ontario McMaster University Osteoarthritis Index (WOMAC) scores to assess radiographic grading and symptomatic severity of OA, respectively. UCMA levels were measured in SF and serum. And also oxidative stress markers were analyzed in SF.

RESULTS

SF UCMA levels of OA patients were higher compared to those of the non-OA control group and were positively correlated with radiographic finding and symptomatic severity of OA. However, there was no significant correlation between oxidative markers of SF and the KL grade, WOMAC scores, and SF UCMA levels in OA patients.

CONCLUSION

There is a close connection between UCMA SF levels and symptomatic and radiographic severities of knee OA. Therefore, UCMA can be a promising biomarker in the diagnosis and/or prognosis of OA disease.

Protective Effects of Sweroside on IL-1β-Induced Inflammation in Rat Articular Chondrocytes Through Suppression of NF-κB and mTORC1 Signaling Pathway

Sweroside (SW), as a bioactive herbal ingredient, has anti-inflammatory effects. Protective effects of SW on IL-1β-stimulated articular chondrocytes, however, has not been fully understood. This study was to explore the anti-inflammatory effects and further to investigate the possible mechanism underlying SW effect on IL-1β-stimulated rat articular chondrocytes. Rat articular chondrocytes were cultured with or without SW for 1 h, and then stimulated with IL-1β for 24 h. ELISA analysis was used to measure the production of NO and PGE2. Western blot was to detect the expression of iNOS and COX-2. Furthermore, the mRNA expression of MMP-1, MMP3, MMP13, and ADAMTS-5 were measured by q-PCR. These results demonstrated that SW significantly inhibited IL-1β-induced NO and PGE2 production, as well as MMP-1, MMP3, MMP13, and ADAMTS-5 mRNA expression. Moreover, SW also suppressed IL-1β-induced NF-κB activation and iκ-B degradation, S6K1 and S6 phosphorylation. In conclusion, these results strongly demonstrated that the anti-inflammatory activity of SW is in part mediated by suppressing NF-κB and mTORC1 signaling, which was expected to be a promising drug target of osteoarthritis therapy.

Editorial Commentary: Could Biological Treatments Be the Game-Changing Factor for Osteoarthritis?

The realization of the presence of an inflammatory component in cartilage degeneration together with the promising application of platelet-rich plasma and amnion as "healing agents" opened a new window of opportunity for biological treatments in osteoarthritis. If the goal is to delay or even cease the degenerative process, then treating the cause rather than the symptom is a key factor for this biological intervention to be successful. As new biological agents arise, there are 3 crucial milestones that need to be met in laboratory and clinical studies: safety, reasonable cost, and improved effectiveness in comparison with alternatives.

Anti-inflammatory and anti-osteoarthritis effects of Cm-02 and Ck-02

Osteoarthritis (OA) is a common degenerative joint disease characterized by progressive deterioration of articular cartilage. There have been reports that small molecule inhibitors have anti-osteoarthritis effects; however, the effects of 3-(4-chloro-2-fluorophenyl)-6-(2,4-difluorophenyl)-2H-benzo[e] [1,3]oxazine-2,4(3H)-dione (Cm-02) and 6-(2,4-difluorophenyl)-3-(3,4-difluorophenyl)-2H-benzo[e] [1,3]oxazine-2,4(3H)-dione (Ck-02), small molecule inhibitors which share many structural similarities with quercetin (a potent anti-inflammatory flavonoid), remain unclear. In this study, TNF-α-stimulated porcine and human chondrocyte models were used to investigate the inhibitory effects of Cm-02 and Ck-02 on the molecular mechanisms underlying the anti-OA effects. TNF-α was used to stimulate porcine and human chondrocytes to mimic immunomodulatory potency in-vitro. Anti-osteoarthritic effects were characterized in terms of protein and mRNA levels associated with the pathogenesis of OA. We also examined (1) the inducible nitric oxide synthase (iNOS)-nitric oxide (NO) system in cultured chondrocytes, (2) matrix metalloproteinases (MMPs) in cultured chondrocytes, and (3) aggrecan degradation in cartilage explants. Finally, we tested the activation of nuclear factor-kappaB (NF-κB), interferon regulatory factor-1 (IRF-1), and activate the protein-1 (AP-1), and we tested the signal transduction and activation of transcription-3 (STAT-3). Our results indicate that, in chondrocytes, Cm-02 and Ck-02 inhibit TNF-α induced NO production, iNOS, MMP, the expression of disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), and the enzyme activity of MMP-13. Furthermore, both Cm-02 and Ck-02 were found to stimulate TNF-α, which has been shown to suppress the activation of several transcription factors, including NF-κB, STAT-3, and IRF-1 in porcine and human chondrocytes. Cm-02 and Ck-02 were also found to help prevent the release of proteoglycans from cartilage explants. Our findings demonstrate that both Cm-02 and Ck-02 have potent anti-inflammatory activities and the ability to protect cartilage in an OA cell model. These findings indicate that Cm-02 and Ck-02 have the potential to be further developed for the therapeutic treatment of OA.

Conditioned Serum Enhances the Chondrogenic and Immunomodulatory Behavior of Mesenchymal Stem Cells

Osteoarthritis is one of the most common chronic health conditions associated with pain and disability. Advanced therapies based on mesenchymal stem cells have become valuable options for the treatment of these pathologies. Conditioned serum (CS, “Orthokine”) has been used intra-articularly for osteoarthritic patients. In this work, we hypothesized that the rich content on anti-inflammatory proteins and growth factors of CS may exert a beneficial effect on the biological activity of human adipose-derived mesenchymal stem cells (hAdMSCs). In vitro studies were designed using hAdMSCs cocultured with CS at different concentrations (2.5, 5, and 10%). Chondrogenic differentiation assays and immunomodulatory experiments using in vitro-stimulated lymphocytes were performed. Our results demonstrated that CS significantly enhanced the differentiation of hAdMSCs toward chondrocytes. Moreover, hAdMSCs pre-sensitized with CS reduced the lymphocyte proliferation as well as their differentiation toward activated lymphocytes. These results suggest that in vivo coadministration of CS and hAdMSCs may have a beneficial effect on the therapeutic potential of hAdMSCs. Moreover, these results indicate that intra-articular administration of CS might influence the biological behavior of resident stem cells increasing their chondrogenic differentiation and inherent immunomodulatory activity. To our knowledge, this is the first in vitro study reporting this combination.