Protective effects of tumor necrosis factor-α blockade by adalimumab on articular cartilage and subchondral bone in a rat model of osteoarthritis

Effects of Etanercept on Experimental Osteoarthritis in Rats: Role of Histone Deacetylases

OBJECTIVE

Mounting evidence suggests that histone deacetylases (HDAC) inhibitors reduce cartilage destruction in animal models of osteoarthritis (OA). Tumor necrosis factor (TNF)-α-blocking treatment for OA may provide effective joint protection by slowing joint damage. To investigate the effects of intraperitoneal administration of etanercept (a TNF-α inhibitor) on OA development in rats and changes in the nociceptive behavior of rats and expression of HDACs, RUNX2, and MMP13 in cartilage.

METHODS

Induction of OA in Wistar rats was accomplished through anterior cruciate ligament transection (ACLT). One or five milligrams (mg) of etanercept was administered intraperitoneally for 5 consecutive weeks after ACLT to the ACLT + etanercept (1 and 5 mg/kg) groups. Nociceptive behavior and changes in knee joint width were analyzed. Cartilage was evaluated histologically and immunohistochemically.

RESULTS

ACLT + etanercept significantly improved mechanical allodynia and weight-bearing distribution compared to ACLT alone. In OA rats treated with etanercept, cartilage degeneration and synovitis were significantly less pronounced than those in ACLT rats. OA-affected cartilage also showed reduced expression of HDAC 6, 7, RUNX-2, and MMP-13 in response to etanercept but increased expression of HDAC4.

CONCLUSION

Our study demonstrated that etanercept therapy (1) attenuated the development of OA and synovitis in rats, (2) reduced nociception, and (3) regulated chondrocyte metabolism, possibly by inhibiting cell HDAC6 and HDAC7, RUNX2, and MMP13 and increasing HDAC4 expression. Based on new evidence, etanercept may have therapeutic potential in OA.

The role and intervention of mitochondrial metabolism in osteoarthritis

Osteoarthritis (OA), a prevalent degenerative joint disease, affects a substantial global population. Despite the elusive etiology of OA, recent investigations have implicated mitochondrial dysfunction as a significant factor in disease pathogenesis. Mitochondria, pivotal cellular organelles accountable for energy production, exert essential roles in cellular metabolism. Hence, mitochondrial dysfunction can exert broad-ranging effects on various cellular processes implicated in OA development. This comprehensive review aims to provide an overview of the metabolic alterations occurring in OA and elucidate the diverse mechanisms through which mitochondrial dysfunction can contribute to OA pathogenesis. These mechanisms encompass heightened oxidative stress and inflammation, perturbed chondrocyte metabolism, and compromised autophagy. Furthermore, this review will explore potential interventions targeting mitochondrial metabolism as means to impede or decelerate the progression of OA. In summary, this review offers a comprehensive understanding of the involvement of mitochondrial metabolism in OA and underscores prospective intervention strategies.

Effects of emulsified and non-emulsified palm tocotrienol on bone and joint health in ovariectomised rats with monosodium iodoacetate-induced osteoarthritis

Postmenopausal women are susceptible to osteoporosis and osteoarthritis. Tocotrienol, a bone-protective nutraceutical, is reported to prevent osteoarthritis in male rats. However, its efficacy on joint health in oestrogen deficiency has not been validated. Besides, data on the use of emulsification systems in enhancing bioavailability and protective effects of tocotrienol are limited. Ovariectomised adult female Sprague-Dawley rats (3 months old) were treated with refined olive oil, emulsified (EPT, 100 mg/kg/day with 25% vitamin E content), non-emulsified palm tocotrienol (NEPT, 100 mg/kg/day with 50% vitamin E content) and calcium carbonate (1% w/v in drinking water) plus glucosamine sulphate (250 mg/kg/day) for 10 weeks. Osteoarthritis was induced with monosodium iodoacetate four weeks after ovariectomy. Baseline control was sacrificed upon receipt, while the sham group was not ovariectomised and treated with refined olive oil. EPT and NEPT prevented femoral metaphyseal and subchondral bone volume decline caused by ovariectomy. EPT decreased subchondral trabecular separation compared to the negative control. EPT preserved stiffness and Young's Modulus at the femoral mid-shaft of the rats. Circulating RANKL was reduced post-treatment in the EPT group. Joint width was reduced in all the treatment groups vs the negative control. The EPT group's grip strength was significantly improved over the negative control and NEPT group. EPT also preserved cartilage histology based on several Mankin's subscores. EPT performed as effectively as NEPT in preventing osteoporosis and osteoarthritis in ovariectomised rats despite containing less vitamin E content. This study justifies clinical trials for the use of EPT in postmenopausal women with both conditions.

A Cryoprotectant-Gel Composite Designed to Preserve Articular Cartilage during Frozen Osteoarticular Autograft Reconstruction for Malignant Bone Tumors: An Animal-Based Study

OBJECTIVE

We designed a highly adhesive cryoprotectant-gel composite (CGC), based on regular liquid-form cryoprotectant base (CB), aiming to protect cartilage tissue during frozen osteoarticular autograft reconstruction for high-grade sarcoma around the joint. This study aimed to evaluate its effectiveness in rat and porcine distal femur models.

DESIGN

Fresh articular cartilage samples harvested from distal rat and porcine femurs were divided into 4 test groups: untreated control group, liquid nitrogen (LN) freezing group, LN freezing group pretreated with CB (CB group), and LN freezing group pretreated with CGC (CGC group). Microscopic and macroscopic evaluation of cartilage condition, TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay, and apoptotic protein analysis of chondrocytes were performed to confirm our results.

RESULTS

In the rat model, CGC could prevent articular cartilage from roughness and preserve more proteoglycans when compared with the LN freezing and CB groups. Western blot analysis showed CGC could prevent cartilage from LN-induced apoptosis supported by caspase-3/8 apoptotic signaling cascade. Macroscopically, we observed CGC could reduce both articular clefting and loss of articular luminance after freezing in the porcine model. In both models, CGC could reduce articular chondrocytes from degeneration. Fewer TUNEL-positive apoptotic and more viable chondrocytes in cartilage tissue were observed in the CGC group in our animal models.

CONCLUSION

Our study proved that CGC could effectively prevent cartilage surface and chondrocytes from cryoinjury after LN freezing. Freezing articular cartilage surrounded with high concentration of CGC can be a better alternative to preserve articular cartilage during limb salvage surgery for malignant bone tumor.

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

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

New Trends in Pharmacological Treatments for Osteoarthritis

Osteoarthritis (OA) is the leading cause of function loss and disability among the elderly, with significant burden on the individual and society. It is a severe disease for its high disability rates, morbidity, costs, and increased mortality. Multifactorial etiologies contribute to the occurrence and development of OA. The heterogeneous condition poses a challenge for the development of effective treatment for OA; however, emerging treatments are promising to bring benefits for OA management in the future. This narrative review will discuss recent developments of agents for the treatment of OA, including potential disease-modifying osteoarthritis drugs (DMOADs) and novel therapeutics for pain relief. This review will focus more on drugs that have been in clinical trials, as well as attractive drugs with potential applications in preclinical research. In the past few years, it has been realized that a complex interaction of multifactorial mechanisms is involved in the pathophysiology of OA. The authors believe there is no miracle therapeutic strategy fitting for all patients. OA phenotyping would be helpful for therapy selection. A variety of potential therapeutics targeting inflammation mechanisms, cellular senescence, cartilage metabolism, subchondral bone remodeling, and the peripheral nociceptive pathways are expected to reshape the landscape of OA treatment over the next few years. Precise randomized controlled trials (RCTs) are expected to identify the safety and efficacy of novel therapies targeting specific mechanisms in OA patients with specific phenotypes.

WISP1 Protects Against Chondrocyte Senescence and Apoptosis by Regulating αvβ3 and PI3K/Akt Pathway in Osteoarthritis

Our study aimed at validating the effect of WISP1 on osteoarthritis (OA) and the pathway involved in the WISP1-induced protection against OA. The expression of WISP1 was measured by immunohistochemical analyses. We found that WISP1 expression was shown to be upregulated within human OA cartilage compared with controls. WISP1 expression was related to knee OA severity. rhWISP1 inhibited OA chondrocyte senescence and apoptosis in vitro, which was reversed by the αvβ3 antibody and PI3K/Akt inhibitor LY294002. WISP1 overexpression induced by knee injection of LiCI could also prevent the senescence and apoptosis of rat chondrocytes. Safranin-O staining and Mankin score revealed that WISP1 overexpression can protect rat chondrocytes from degeneration. Nearly opposite results were obtained in the treatment of ICG-001 and siRNA-WISP1 in vivo. These data strongly suggest that WISP1 can protect against the senescence and apoptosis of chondrocytes via modulating the αvβ3 receptor and PI3K/Akt signaling pathway within OA. Therefore, the development of specific activators of WISP1 may present the value of an underlying OA treatment.

The effects of TNF-alpha inhibition on cartilage: a systematic review of preclinical studies

OBJECTIVE

To report the most up-to-date evidence on the effects of tumour necrosis factor (TNF)-alpha inhibition on cartilage with a focus on its clinical relevance.

DESIGN

A systematic review was performed by searching PubMed, Embase and Cochrane Library databases. Inclusion criteria were studies of any level of evidence published in peer-reviewed journals reporting clinical or preclinical results written in English. Relative data were extracted and critically analysed. PRISMA guidelines were applied, and risk of bias was assessed as well as the methodological quality of the included studies.

RESULTS

13 studies were included after applying the inclusion and exclusion criteria. Three were in vitro human studies from osteoarthritis (OA) patients. Ten were animal modal studies including two in vitro studies, and eight in vivo studies. TNF-alpha inhibition in in vitro studies was generally reported beneficial due to the improved osteochondral viability, proliferation and chondrogenesis. In addition, TNF-alpha inhibition was noted to be beneficial in promoting the natural repair of osteochondral lesions and has a chondroprotective effect in in vivo studies.

CONCLUSION

Based on current evidence, TNF might have the potential to interfere with the healing process of chondral and osteochondral defects occurring naturally or in low inflammatory environment after a cartilage repair procedure. Therefore, the use of biological agents to inhibit its action in cartilage repair surgery could be beneficial, and this could translate into a promising therapy that improves the outcome of currently available cartilage procedures.

Early-Onset Osteoarthritis originates at the chondrocyte level in Hip Dysplasia

Subjects with developmental dysplasia of the hip (DDH) often show early-onset osteoarthritis (OA); however, the molecular mechanisms underlying this pathology are not known. We investigated whether cellular changes in chondrocytes from OA cartilage can be detected in chondrocytes from DDH cartilage before histological manifestations of degeneration. We characterized undamaged and damaged articular cartilage from 22 participants having hip replacement surgery with and without DDH (9 DDH-OA, 12 OA-only, one femoral fracture). Tissue immunostaining revealed changes in damaged OA-only cartilage that was also found in undamaged DDH-OA cartilage. Chondrocytes in situ from both groups show: (i) thicker fibers of vimentin intermediate filaments, (ii) clusters of integrin α₅β₁, (iii) positive MMP13 staining and (iv) a higher percentage of cells expressing the serine protease HtrA1. Further characterization of the extracellular matrix showed strong aggrecan and collagen II immunostaining in undamaged DDH cartilage, with no evidence of augmented cell death by activation of caspase 3. These findings suggest that early events in DDH cartilage originate at the chondrocyte level and that DDH cartilage may provide a novel opportunity to study these early changes for the development of therapeutic targets for OA.

Effect of tumor necrosis factor inhibition on spinal inflammation and spinal ankylosis in SKG mice

To prevent spinal progression in ankylosing spondylitis, initiating TNF-inhibitor treatment as early as possible is suggested. However, the outcomes are inconsistent in previous clinical studies. Here, we investigated the effect of TNF inhibition alone on spinal progression when used during arthritis development in a murine model. We injected 8-week-old SKG mice with curdlan (curdlan group). We injected adalimumab at 3 and 9 weeks after the first curdlan injection (ADA group). The clinical scores of peripheral arthritis decreased in the ADA group at 3 weeks after first adalimumab injection. Using positron emission tomography–magnetic resonance imaging and histologic examination, spinal inflammation was observed in the curdlan group, and was significantly deceased in the ADA group. However, spinal osteoblast activities by imaging using OsteoSense 680 EX and bone metabolism-related cytokines such as receptor activator of nuclear factor-kappa B ligand, osteoprotegerin, Dickkopf-1, and sclerostin levels except IL-17A level were not different between the two groups. We conclude that treating TNF inhibitor alone reduced peripheral arthritis score and spinal inflammation in curdlan-injected SKG mice but did not decrease the spinal osteoblast activity, suggesting little effect on spinal ankylosis.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Etanercept in patients with inflammatory hand osteoarthritis (EHOA): a multicentre, randomised, double-blind, placebo-controlled trial

Objective

Hand osteoarthritis is a prevalent disease with limited treatment options. Since joint inflammation is often present, we investigated tumour necrosis factor (TNF) as treatment target in patients with proven joint inflammation in a proof-of-concept study.

Methods

This 1-year, double-blind, randomised, multicentre trial (NTR1192) enrolled patients with symptomatic erosive inflammatory hand osteoarthritis. Patients flaring after non-steroidal anti-inflammatory drug washout were randomised to etanercept (24 weeks 50 mg/week, thereafter 25  mg/week) or placebo. The primary outcome was Visual Analogue Scale (VAS) pain at 24 weeks. Secondary outcomes included clinical and imaging outcomes (radiographs scored using Ghent University Scoring System (GUSS, n=54) and MRIs (n=20)).

Results

Of 90 patients randomised to etanercept (n=45) or placebo (n=45), respectively, 12 and 10 discontinued prematurely. More patients on placebo discontinued due to inefficacy (6 vs 3), but fewer due to adverse effects (1 vs 6). The mean between-group difference (MD) in VAS pain was not statistically significantly different (−5.7 (95% CI −15.9 to 4.5), p=0.27 at 24 weeks; − 8.5 (95% CI −18.6 to 1.6), p=0.10 at 1  year; favouring etanercept). In prespecified per-protocol analyses of completers with pain and inflammation at baseline (n=61), MD was −11.8 (95% CI −23.0 to −0.5) (p=0.04) at 1  year. Etanercept-treated joints showed more radiographic remodelling (delta GUSS: MD 2.9 (95% CI 0.5 to 5.4), p=0.02) and less MRI bone marrow lesions (MD −0.22 (95% CI −0.35 to −0.09), p = 0.001); this was more pronounced in joints with baseline inflammation.

Conclusion

Anti-TNF did not relieve pain effectively after 24 weeks in erosive osteoarthritis. Small subgroup analyses showed a signal for effects on subchondral bone in actively inflamed joints, but future studies to confirm this are warranted.

TNF‑α increases inflammatory factor expression in synovial fibroblasts through the toll‑like receptor‑3‑mediated ERK/AKT signaling pathway in a mouse model of rheumatoid arthritis

Osteoarthritis is a type of joint disease that may lead to other joint diseases. Previous research has demonstrated that tumor necrosis factor (TNF)‑α is associated with osteoarthritis activity and pathology. The possible mechanisms of the TNF‑α‑mediated signaling pathway have not been clearly elaborated in synovial fibroblasts. The present study aimed to investigate the potential mechanisms of TNF‑α in a mouse model of iodoacetate‑induced osteoarthritis. Reverse transcription‑quantitative polymerase chain reaction, ELISA, western blotting and immunohistochemistry were performed to evaluate the role of TNF‑α in the progression of osteoarthritis. The results revealed that the serum levels of TNF‑α, interleukin (IL)‑1β, IL‑4 and IL‑6 were significantly upregulated in a mouse model of iodoacetate‑induced osteoarthritis compared with healthy mice (P<0.01). TNF‑α, IL‑1β, IL‑4 and IL‑6 mRNA and protein levels were also significantly upregulated in synovial fibroblasts in the experimental mice (P<0.01). It was demonstrated that TNF‑α increased pro‑inflammation factors matrix metalloproteinase (MMP)‑3, MMP‑9, nuclear factor (NF)‑κB and receptor activator of NF‑κB ligand (RANKL) in synovial fibroblasts. It was also observed that the toll‑like receptor (TLR)‑3 was significantly upregulated and extracellular signal‑regulated kinase (ERK) and protein kinase B (AKT) were significantly downregulated in synovial fibroblasts in osteoarthritis mice (P<0.01). An in vitro assay demonstrated that TNF‑α inhibitor decreased mRNA and protein levels of IL‑1β, IL‑4 and IL‑6 in synovial fibroblasts. The knockdown of TLR‑3 abolished the TNF‑α upregulated mRNA and protein levels of IL‑1β, IL‑4 and IL‑6 in synovial fibroblasts. In addition, the knockdown of TLR‑3 also reversed TNF‑α‑upregulated ERK and AKT expression in synovial fibroblasts. In vivo assays demonstrated that TNF‑α inhibitor significantly decreased the deposition of IL‑1β, IL‑4 and IL‑6 as well as bone destruction and significantly increased the body weight and osteoarthritis score for osteoarthritic mice (P<0.01). TNF‑α inhibitor decreased TLR‑3 and significantly increased the expression and phosphorylation of ERK and AKT in articular cartilage (P<0.01). In conclusion the results of the present study indicate that TNF‑α serves an essential role in synovial fibroblasts in osteoarthritis, suggesting that inhibition of TNF‑α may decrease inflammation via the TLR‑3‑mediated ERK/AKT signaling pathway in a mouse model of monosodium iodoacetate‑induced osteoarthritis.

Autologous Chondrocyte Implantation in Osteoarthritic Surroundings: TNFα and Its Inhibition by Adalimumab in a Knee-Specific Bioreactor

BACKGROUND

Autologous chondrocyte implantation (ACI) fails in up to 20% of cases. Advanced intra-articular degeneration paired with an inflammatory environment may be closely related to implantation failure. Certain cytokines have been identified to play a major role during early osteoarthritis.

PURPOSE

To investigate the effects of tumor necrosis factor α (TNFα) and its potential inhibition by adalimumab on cartilage regeneration in an in vitro model of ACI.

STUDY DESIGN

Controlled laboratory study.

METHODS

Bovine articular chondrocytes were cultivated and transferred at passage 3 to fibrin-polyurethane scaffolds. Constructs were loaded by compression (10%-20% scaffold height) and shear (±25°) in a fully characterized multiaxial load (L) bioreactor to simulate clinical ACI or were subjected to free swelling (FS) conditions for a duration of 2 weeks. TNFα (20 ng/mL), adalimumab (10 µg/mL), or both were added to the medium. To assess the outcome, DNA, GAG (glycosaminoglycan), and total collagen were quantified, and gene expression of anabolic (collagen 2, aggrecan, cartilage oligomeric protein, proteoglycan 4), catabolic (matrix metalloproteinases [MMP] 3 and 13), dedifferentiation (collagen 1), and hypertrophy (collagen 10) markers and proinflammatory cytokines (TNFα, IL-1β) was analyzed. Histological evaluation was performed with safranin O/fast green, toluidine blue, and immunohistochemistry of collagen 1 and 2. Apoptosis was analyzed by immunolabeling of anti-active caspase 3. For statistical evaluation, nonparametric tests were chosen with a significance level of P < .05.

RESULTS

A general downregulation of anabolic and upregulation of catabolic markers was detected in the TNFα groups. Collagen 2 was suppressed by TNFα (FS, P = .029; L, P = .006), while MMP 3 was significantly upregulated (FS, P = .035; L, P = .001). Dynamic loading induced a chondrogenic response, which could not fully antagonize the effect of the cytokine. Adalimumab antagonized all effects of TNFα. The histological and immunohistochemical assessments demonstrated less matrix formation in the cytokine-only groups. TNFα induced apoptosis, and this effect was increased by loading.

CONCLUSION

TNFα does negatively affect chondrogenesis under simulated ACI conditions. Both dynamic load and, more potentially, adalimumab showed the capability of antagonizing the negative effects.

CLINICAL RELEVANCE

Catabolic cytokine suppression (ie, TNFα inhibition) combined with compression and shear load may best meet the conditions for chondrogenesis in an osteoarthritic environment.

Efficacy and safety of adalimumab by intra-articular injection for moderate to severe knee osteoarthritis: An open-label randomized controlled trial

Objective

To evaluate the efficacy and safety of adalimumab (ADA) versus hyaluronic acid (HA) by intra-articular injection for moderate to severe knee osteoarthritis.

Methods

Fifty-six consecutive patients with moderate to severe knee osteoarthritis were randomly allocated to either the ADA group or HA group. On day 0, patients in the ADA group received 10 mg of ADA by intra-articular injection, while those in the HA group received 25 mg of HA. All patients received celecoxib at 200 mg/day for 4 weeks. The pain visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Patient Global Assessment (PGA), and Physician Global Assessment (PhGA) scores were assessed.

Results

At baseline, the pain VAS, WOMAC, PGA, and PhGA scores were similar between the two groups. The decrease in the pain VAS score, WOMAC pain score, WOMAC physical function score, and WOMAC total score from baseline to week 4 were greater in the ADA than HA group. A greater decrease in the PGA and PhGA scores from baseline to week 4 was noted in the ADA than HA group. No difference in adverse events was observed between the two groups.

Conclusion

ADA by intra-articular injection was effective and tolerated for moderate to severe knee osteoarthritis.

A comparative study of effect of autograft compared with allograft anterior cruciate ligament reconstruction on expressions of LOXs and MMPs

The present study aimed to compare the effect of autograft or allograft anterior cruciate ligament (ACL) reconstruction on the expressions of lipoxygenases (LOXs) and matrix metalloproteinases (MMPs) in a New Zealand white rabbit model. New Zealand white rabbits were divided randomly into control, sham, autograft and allograft groups. At the 4th and 8th week after operation, biomechanical testing was performed to measure the primary length, cross-sectional area, maximum tensile load and stiffness of ACL, and HE staining was used to observe cell morphology and fibre alignment of ACL. At the 2nd, 4th and 8th week after operation, quantitative real-time PCR (qRT-PCR), Western blotting and immunohistochemistry were applied to detect LOXs and MMPs expressions, and expressions of adenomatous polyposis coli (APC)/Wnt signalling pathway-related proteins. At the 4th and 8th week after operation, the maximum tensile load and stiffness were higher in the autograft group than in the allograft group, and the values at the 8th week were higher than those at the 4th week after operation. The fibroblast proliferation in the allograft group was more significant than that in the autograft group. Compared with the control group, LOXs and MMPs expressions and the positive expression rates of LOXs and MMPs proteins were elevated, and the values in the allograft group were higher than those in the autograft group at all time points. At 8th week after operation, compared with the autograft group, Wnt expression was higher and APC expression was lower in the allograft group. Autograft and allograft ACL reconstruction can promote LOXs and MMPs expressions by activating the APC/Wnt signalling pathway.

Monoclonal antibodies for the treatment of osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a multifactorial chronic joint disease, and so far, there are no approved disease-modifying anti-OA drugs (DMOADs). There is an urgent need to develop therapies for different phenotypes of OA. Monoclonal antibodies (mAb) may slow structural progression, control inflammation and relieve pain, and thus have the potential to be DMOADs. Areas covered: In this review, the authors searched the literature on PubMed, EMBASE and the Cochrane Library using keywords, including mAbs, biological agents, OA and osteoarthritis, electronically up to May 2016. They also included abstracts of international conferences. Furthermore, they reviewed experimental and clinical studies of various mAbs targeting different pathological mechanisms of OA, including ADAMTS, Interleukine-1, tumour necrosis factor, never growth factor and vascular endothelial growth factor. Expert opinion: MAbs for the treatment of OA are under intense investigation and the results for some mAbs (e.g., anti-nerve growth factor mAbs, anti- vascular endothelial growth factor mAbs) are promising. The authors believe that mAb therapy can be a targeted therapeutic approach for the treatment of OA. Future clinical trials are required to evaluate the therapeutic efficacy of these agents by the appropriate selection of specific phenotype for targeted therapy based on the mechanism of drug action.

The role of progranulin in arthritis

Progranulin (PGRN) is a growth factor with a unique beads-on-a-string structure that is involved in multiple pathophysiological processes, including anti-inflammation, tissue repair, wound healing, neurodegenerative diseases, and tumorigenesis. This review presents up-to-date information concerning recent studies on the role of PGRN in inflammatory arthritis and osteoarthritis, with a special focus on the involvement of the interactions and interplay between PGRN and tumor necrosis factor receptor (TNFR) family members in regulating such musculoskeletal diseases. In addition, this paper highlights the applications of atsttrin, an engineered protein comprising three TNFR-binding fragments of PGRN, as a promising intervention in treating arthritis.

Chondroprotective effects of alpha-lipoic acid in a rat model of osteoarthritis

OBJECTIVE

The purpose of this study was to investigate whether alpha-lipoic acid (ALA) confers a chondroprotective effect on articular cartilage in rats with monosodium iodoacetate (MIA)-induced osteoarthritis (OA).

METHODS

Fifty male SD rats were divided into five groups, including SHAM-operated, MIA-induced OA, and three experimental groups treated with 50-, 100-, or 200-mg/kg ALA. After 14 d of ALA treatment, rats were sacrificed for joint macroscopic and histology assessments. The gene and protein expressions of markers related to chondrocyte phenotype, caspase proteins, NADPH oxidase 4 (Nox4), p22(phox), activation of nuclear factor-κB (NF-κB), and endoplasmic reticulum (ER) stress were measured by Western blot analyses or qRT-PCR.

RESULTS

The results showed that MIA injection successfully induced OA by causing cartilage degeneration. Morphological and histological examinations demonstrated that ALA treatment, especially 200 mg/kg of ALA, significantly ameliorated cartilage degeneration in rats with MIA-induced OA. ALA could effectively increase the levels of the collagen type II and aggrecan genes and inhibit apoptosis-related proteins expression. ALA reduced biomakers of oxidative damage and over-expression levels of Nox4 and p22(phox). ALA also suppressed ER stress and inhibited the activation of NF-κB pathway. Moreover, ALA obviously inhibited TNF-α secretion and Wnt/β-catenin signaling way.

CONCLUSION

These findings indicated that ALA might be a potential therapeutic agent for the protection of articular cartilage against progression of OA through inhibition of oxidative stress, ER stress, inflammatory cytokine secretion, and Wnt/β-catenin activation.

New discovery rarely runs smooth: an update on progranulin/TNFR interactions

Progranulin (PGRN) is a growth factor implicated in various pathophysiological processes, including wound healing, inflammation, tumorigenesis, and neurodegeneration. It was previously reported that PGRN binds to tumor necrosis factor receptors (TNFR) and has therapeutic effects in inflammatory arthritis (Tang et. al, in Science 332:478-484, 2011); however, Chen et al. reported their inability to demonstrate the PGRN-TNFR interactions under their own conditions (Chen et. al, in J Neurosci 33:9202-9213, 2013). A letter-to-editor was then published by the original group in response to the Chen et al. paper that discussed the reasons for the latter's inability to recapitulate the interactions. In addition, the group published follow-up studies that further reinforced and dissected the interactions of PGRN-TNFR. Recently, the dispute about the legitimacy of PGRN-TNFR interactions appears to be finally settled with independent confirmations of these interactions in various conditions by numerous laboratories. This review presents a chronological update on the story of PGRN-TNFR interactions, highlighting the independent confirmations of these interactions in various diseases and conditions.