Novel selective MMP-13 inhibitors reduce collagen degradation in bovine articular and human osteoarthritis cartilage explants

On-demand release of a selective MMP-13 blocker from an enzyme-responsive injectable hydrogel protects cartilage from degenerative progression in osteoarthritis

In osteoarthritis (OA), the degradation of cartilage is primarily driven by matrix metalloprotease-13 (MMP-13). Hence, the inhibition of MMP-13 has emerged as an attractive target for OA treatment. Among the various approaches that are being explored for MMP-13 regulation, blocking of the enzyme with specific binding molecules appears to be a more promising strategy for preventing cartilage degeneration. To enhance effectiveness and ensure patient compliance, it is preferable for the binding molecule to exhibit sustained activity when administered directly into the joint. Herein, we present an enzyme-responsive hydrogel that was designed to exhibit on-demand, the sustained release of BI-4394, a potent and highly selective MMP-13 blocker. The stable and compatible hydrogel was prepared using triglycerol monostearate. The efficacy of the hydrogel to prevent cartilage damage was assessed in a rat model of OA induced by anterior cruciate ligament transection (ACLT). The results revealed that in comparison to the rats administrated weekly with intra-articular BI-4394, the hydrogel implanted rats had reduced levels of inflammation and bone erosion. In comparison to untreated control, the cartilage in animals administered with BI-4394/hydrogel exhibited significant levels of collagen-2 and aggrecan along with reduced MMP-13. Overall, this study confirmed the potential of BI-4394 delivery using an enzyme-responsive hydrogel as a promising treatment option to treat the early stages of OA by preventing further cartilage degradation.

Screening of MMP-13 Inhibitors Using a GelMA-Alginate Interpenetrating Network Hydrogel-Based Model Mimicking Cytokine-Induced Key Features of Osteoarthritis In Vitro

Osteoarthritis (OA) is a chronic joint disease characterized by irreversible cartilage degradation. Current clinical treatment options lack effective pharmaceutical interventions targeting the disease's root causes. MMP (matrix metalloproteinase) inhibitors represent a new approach to slowing OA progression by addressing cartilage degradation mechanisms. However, very few drugs within this class are in preclinical or clinical trial phases. Hydrogel-based 3D in vitro models have shown promise as preclinical testing platforms due to their resemblance to native extracellular matrix (ECM), abundant availability, and ease of use. Metalloproteinase-13 (MMP-13) is thought to be a major contributor to the degradation of articular cartilage in OA by aggressively breaking down type II collagen. This study focused on testing MMP-13 inhibitors using a GelMA-alginate hydrogel-based OA model induced by cytokines interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α). The results demonstrate a significant inhibition of type II collagen breakdown by measuring C2C concentration using ELISA after treatment with MMP-13 inhibitors. However, inconsistencies in human cartilage explant samples led to inconclusive results. Nonetheless, the study highlights the GelMA-alginate hydrogel-based OA model as an alternative to human-sourced cartilage explants for in vitro drug screening.

Regulation of Peptidase Activity beyond the Active Site in Human Health and Disease

This comprehensive review addresses the intricate and multifaceted regulation of peptidase activity in human health and disease, providing a comprehensive investigation that extends well beyond the boundaries of the active site. Our review focuses on multiple mechanisms and highlights the important role of exosites, allosteric sites, and processes involved in zymogen activation. These mechanisms play a central role in shaping the complex world of peptidase function and are promising potential targets for the development of innovative drugs and therapeutic interventions. The review also briefly discusses the influence of glycosaminoglycans and non-inhibitory binding proteins on enzyme activities. Understanding their role may be a crucial factor in the development of therapeutic strategies. By elucidating the intricate web of regulatory mechanisms that control peptidase activity, this review deepens our understanding in this field and provides a roadmap for various strategies to influence and modulate peptidase activity.

Pathogenesis and therapeutic implications of matrix metalloproteinases in intervertebral disc degeneration: A comprehensive review

Intervertebral disc (IVD) degeneration (IDD) is a common disorder that affects the spine and is a major cause of lower back pain (LBP). The extracellular matrix (ECM) is the structural foundation of the biomechanical properties of IVD, and its degradation is the main pathological characteristic of IDD. Matrix metalloproteinases (MMPs) are a group of endopeptidases that play an important role in the degradation and remodeling of the ECM. Several recent studies have shown that the expression and activity of many MMP subgroups are significantly upregulated in degenerated IVD tissue. This upregulation of MMPs results in an imbalance of ECM anabolism and catabolism, leading to the degradation of the ECM and the development of IDD. Therefore, the regulation of MMP expression is a potential therapeutic target for the treatment of IDD. Recent research has focused on identifying the mechanisms by which MMPs cause ECM degradation and promote IDD, as well as on developing therapies that target MMPs. In summary, MMP dysregulation is a crucial factor in the development of IDD, and a deeper understanding of the mechanisms involved is needed to develop effective biological therapies that target MMPs to treat IDD.

Latest insights in disease-modifying osteoarthritis drugs development

Osteoarthritis (OA) is a prevalent and severely debilitating disease with an unmet medical need. In order to alleviate OA symptoms or prevent structural progression of OA, new drugs, particularly disease-modifying osteoarthritis drugs (DMOADs), are required. Several drugs have been reported to attenuate cartilage loss or reduce subchondral bone lesions in OA and thus potentially be DMOADs. Most biologics (including interleukin-1 (IL-1) and tumor necrosis factor (TNF) inhibitors), sprifermin, and bisphosphonates failed to yield satisfactory results when treating OA. OA clinical heterogeneity is one of the primary reasons for the failure of these clinical trials, which can require different therapeutic approaches based on different phenotypes. This review describes the latest insights into the development of DMOADs. We summarize in this review the efficacy and safety profiles of various DMOADs targeting cartilage, synovitis, and subchondral bone endotypes in phase 2 and 3 clinical trials. To conclude, we summarize the reasons for clinical trial failures in OA and suggest possible solutions.

Chondrocyte-specific genomic editing enabled by hybrid exosomes for osteoarthritis treatment

Rationale: A cell-specific delivery vehicle is required to achieve gene editing of the disease-associated cells, so the hereditable genome editing reactions are confined within these cells without affecting healthy cells. A hybrid exosome-based nano-sized delivery vehicle derived by fusion of engineered exosomes and liposomes will be able to encapsulate and deliver CRISPR/Cas9 plasmids selectively to chondrocytes embedded in articular cartilage and attenuate the condition of cartilage damage. Methods: Chondrocyte-targeting exosomes (CAP-Exo) were constructed by genetically fusing a chondrocyte affinity peptide (CAP) at the N-terminus of the exosomal surface protein Lamp2b. Membrane fusion of the CAP-Exo with liposomes formed hybrid CAP-exosomes (hybrid CAP-Exo) which were used to encapsulate CRISPR/Cas9 plasmids. By intra-articular (IA) administration, hybrid CAP-Exo/Cas9 sgMMP-13 entered the chondrocytes of rats with cartilage damages that mimicked the condition of osteoarthritis. Results: The hybrid CAP-Exo entered the deep region of the cartilage matrix in arthritic rats on IA administration, delivered the plasmid Cas9 sgMMP-13 to chondrocytes, knocked down the matrix metalloproteinase 13 (MMP-13), efficiently ablated the expression of MMP-13 in chondrocytes, and attenuated the hydrolytic degradation of the extracellular matrix proteins in the cartilage. Conclusion: Chondrocyte-specific knockdown of MMP-13 mitigates or prevents cartilage degradation in arthritic rats, showing that hybrid CAP-Exo/Cas9 sgMMP-13 may alleviate osteoarthritis.

lncRNA DLEU1 Modulates Proliferation, Inflammation, and Extracellular Matrix Degradation of Chondrocytes through Regulating miR-671-5p

Long noncoding RNAs (lncRNAs) have been shown to be involved in the development of osteoarthritis. However, the expression, function, and mechanism of DLEU1 in OA development remain largely unclear. The present reference demonstrates that DLEU1 is overexpressed in OA specimens compared to control cartilages. Inflammatory cytokines IL-1β, TNF-α, and IL-6 induce DLEU1 expression in chondrocytes. Ectopic expression of DLEU1 induces chondrocyte proliferation, degradation of ECM, and inflammation mediators such as IL-6, IL-8, and TNF-α secretion. Moreover, we demonstrated that DLEU1 targets miR-671-5p expression in chondrocytes. Overexpression of DLEU1 suppresses miR-671-5p expression in chondrocytes. The expression of miR-671-5p is decreased in OA specimens compared to control cartilages. There is a negative correlation between the expression of miR-671-5p and DLEU1 in OA specimens. Inflammatory mediators IL-1β, TNF-α, and IL-6 suppress miR-671-5p expression in OA specimens. Elevated expression of miR-671-5p suppresses chondrocyte proliferation, degradation of ECM, and secretion of inflammation mediators. DLEU1 overexpression promotes chondrocytes proliferation, degradation of ECM, and secretion of inflammation mediators via regulating miR-671-5p. These results suggested that DLEU1 acts as one destructive role in OA development via regulating miR-671-5p.

Long non-coding ribonucleic acid AFAP1-AS1 promotes chondrocyte proliferation via the miR-512-3p/matrix metallopeptidase 13 (MMP-13) axis

Long-chain non-coding RNAs are reported to be involved in cartilage damage. However, less research on the role of actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1) in osteoarthritis. To investigate AFAP1-AS1 function in osteoarthritis development, AFAP1-AS1 and miR-512-3p expression levels in osteoarthritis cartilage and cells were evaluated using RT-qPCR. The downstream target genes of AFAP1-AS1 and miR-512-3p were predicted and validated using luciferase reporter assays. Moreover, a knee osteoarthritis model was established by injecting monoiodoacetate into the knee joints of mice. The effects of AFAP1-AS1 and miR-512-3p on osteoarthritis chondrocyte proliferation and MMP-13, collagen II, and collagen IV expressions were detected in vivo using CCK-8 assay and Western blotting and RT-qPCR, respectively. AFAP1-AS1 expression was upregulated in osteoarthritis cartilage and cells. MiR-512-3p expression was downregulated in osteoarthritis cartilage. AFAP1-AS1 overexpression inhibited miR-512-3p expression in chondrocytes. Furthermore, AFAP1-AS1 over-expression promoted chondrocyte proliferation, and miR-512-3p mimic inhibited chondrocyte proliferation in vivo. AFAP1-AS1 overexpression reduced type II and type IV collagen expression, while miR-512-3p overexpression promoted type II and type IV collagen in vivo. AFAP1-AS1 overexpression enhanced MMP-13 expression in vivo. AFAP1-AS1 overexpression regulated chondrocyte proliferation by inhibiting miR-512-3p expression in vivo. AFAP1-AS1 could be a potential target to treat osteoarthritis by inhibiting miR-512-3p and subsequently inducing chondrocyte proliferation and regulating matrix synthesis.

Zn-containing Adhesives Facilitate Collagen Protection and Remineralization at the Resin-Dentin Interface: A Narrative Review

This is a narrative review of the literature assessing the potential effectiveness of doping dentin polymeric adhesives with zinc compounds in order to improve bonding efficacy, remineralization and protection against degradation. A literature search was conducted using electronic databases, such as PubMed, MEDLINE, DIMDI and Web of Science. Through our search, we found literature demonstrating that Zn-doped dentin adhesives promote protection and remineralization of the resin-dentin interfaces. The increased bioactivity has also facilitated dentinal tubules' occlusion by crystals' precipitation contributing to improved sealing efficacy of restorations. Loading dentin adhesives with zinc gives rise to an increase of both crystallinity of mineral and crosslinking of collagen. The main role of zinc, in dentin adhesives, is to inhibit collagen proteolysis. We concluded that zinc exerts a protective effect through binding at the collagen-sensitive cleavage sites of matrix-metalloproteinases (MMPs), contributing to dentin matrix stabilization. Zinc may not only act as a MMPs inhibitor, but also influence signaling pathways and stimulate metabolic effects in dentin mineralization and remineralization processes. Zn-doped adhesives increase the longevity of dentin bonding through MMPs inhibition. Zn poses a remineralization strategy in demineralized dentin.

The collagenases: are they tractable targets for preventing cartilage destruction in osteoarthritis?

INTRODUCTION

The etiology and pathogenesis of osteoarthritis (OA) have been intensely investigated; however, the disease course and progression are not completely understood. A prominent role for interstitial collagenases is recognized in this degenerative process, hence strategies to target them are of major interest.

AREAS COVERED

The pathogenesis of OA, the role of interstitial collagenases (MMP-1, -8 and -13) and collagenase modifying drugs are examined and discussed. We reviewed relevant papers from PubMed and Google Scholar.

EXPERT OPINION

There is strong evidence for the therapeutic potential of MMP inhibitors in OA; however, they are not expected to impact the inflammatory process. Therefore, there is a need for a relative inhibitor of MMP-13 collagenase which possesses anti-inflammatory properties. The identification of novel broad-spectrum relative multiple peptidase inhibitors could provide desirable tools for the prophylaxis, cure, or treatment of diseases involving articular cartilage (AC) degradation, in particular OA.

Circ_0128846/miR-140-3p/JAK2 Network in Osteoarthritis Development

Circular RNAs (circRNAs) titrate the function of microRNAs (miRNAs), regulate transcription, and interfere with splicing. This study attempted to confirm the role of a novel circRNA circ_0128846 during osteoarthritis (OA) progression. Tissues and chondrocytes were isolated from OA patients. Overexpression and knockdown of target genes were generated using cell transfection and siRNA interference. Expression levels of genes were measured by qRT-PCR, Western blot, and immunohistochemistry, respectively. The interactions among circ_0128846, miR-140-3p, and JAK2 were verified by bioinformatics prediction, a dual-luciferase reporter assay, and RNA immunoprecipitation assay. The role of circ_0128846 in vivo was confirmed by the construction of experimental OA rats. Pathological changes were evaluated by hematoxylin and eosin and Safranin O staining. In OA patients, the level of circ_0128846 and JAK2 were up-regulated with down-regulated level of miR-140-3p. Circ_0128846 was principally located in the cytoplasm. Circ_0128846 silence enhanced cells viability, but reduced apoptosis rate and inflammatory response, which was obviously reversed by miR-140-3p knockdown. The overexpression of JAK2 reversed the effects of miR-140-3p on cell phenotypes. Circ_0128846 silence suppressed the level of MMP-13 and promoted the expression of collagen II by up-regulating miR-140-3p and down-regulating JAK2 in OA cells. Results of animal experiments demonstrated that circ_0128846 silence promoted collagen II expression and attenuated the OA progression by regulating the miR-140-3p/JAK2 axis. Circ_0128846 contributes to OA development through acting as a sponge RNA for miR-140-3p and thereby increasing JAK2 expression. Results indicated that targeting circ_0128846 may have the potential to alleviate OA progression.Abbreviations:circRNAs: Circular RNAs; miRNAs: microRNAs; OA: osteoarthritis; RIP: RNA immunoprecipitation; H&E: hematoxylin and eosin; ncRNAs: noncoding RNAs; ceRNA: competitive endogenous RNA; DMEM: Dulbecco's modified Eagle's medium; PBS: phosphate buffered saline; OE-circ_0128846: overexpression vector for circ_0128846; pcDNA3.1-JAK2: pcDNA3.1 overexpression vector for Janus kinase 2; NC: negative control; CCK-8: Cell Counting Kit-8; PI: propidium iodide; WT: Wild-type; mutants (MUT); SD rats: Sprague Dawley rats; DMM: destabilization of medial meniscus; IHC: immunohistochemistry; DAB: diaminobenzene; pre-Mrna: precursor mRNA.

Targeting Dysregulation of Metalloproteinase Activity in Osteoarthritis

Metalloproteinases were first identified as collagen cleaving enzymes and are now appreciated to play important roles in a wide variety of biological processes. The aberrant activity and dysregulation of the metalloproteinase family are linked to numerous diseases including cardiovascular and pulmonary diseases, chronic wounds, cancer, fibrosis and arthritis. Osteoarthritis (OA) is the most prevalent age-related joint disorder that causes pain and disability, but there are no disease-modifying drugs available. The hallmark of OA is loss of articular cartilage and elevated activities of matrix-degrading metalloproteinases are responsible. These enzymes do not exist in isolation and their activity is tightly regulated by a number of processes, such as transcription, proteolytic activation, interaction with their inhibitors, cell surface and extracellular matrix molecules, and endocytic clearance from the extracellular milieu. Here, we describe the functions and roles of metalloproteinase family in OA pathogenesis. We highlight recent studies that have illustrated novel mechanisms regulating their extracellular activity and impairment of such regulations that lead to the development of OA. We also discuss how to stop or slow down the degenerative processes by targeting aberrant metalloproteinase activity, which may in future become therapeutic interventions for the disease.

Sodium Monoiodoacetate Dose-Dependent Changes in Matrix Metalloproteinases and Inflammatory Components as Prognostic Factors for the Progression of Osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease that primarily affects people over 65 years old. During OA progression irreversible cartilage, synovial membrane and subchondral bone degradation is observed, which results in the development of difficult-to-treat chronic pain. One of the most important factors in OA progression is joint inflammation. Both proinflammatory and anti-inflammatory factors, as well as extracellular matrix degradation enzymes (matrix metalloproteinases (MMPs), play an important role in disease development. One of the most widely used animal OA models involves an intra-articular injection of sodium monoiodoacetate (MIA) directly into the joint capsule, which results in glycolysis inhibition in chondrocytes and cartilage degeneration. This model mimics the degenerative changes observed in OA patients. However, the dose of MIA varies in the literature, ranging from 0.5 to 4.8 mg. The aim of our study was to characterize grading changes after injection of 1, 2 or 3 mg of MIA at the behavioral and molecular levels over a 28-day period. In the behavioral studies, MIA injection at all doses resulted in a gradual increase in tactile allodynia and resulted in abnormal weight bearing during free walking sequences. At several days post-OA induction, cartilage, synovial membrane and synovial fluid samples were collected, and qPCR and Western blot analyses were performed. We observed significant dose- and time-dependent changes in both gene expression and protein secretion levels. Inflammatory factors (CCL2, CXCL1, IL-1β, COMP) increased at the beginning of the experiment, indicating a transient inflammatory state connected to the MIA injection and, in more severe OA, also in the advanced stages of the disease. Overall, the results in the 1 mg MIA group were not consistently clear, indicating that the lowest tested dose may not be sufficient to induce long-lasting OA-like changes at the molecular level. In the 2 mg MIA group, significant alterations in the measured factors were observed. In the 3 mg MIA group, MMP-2, MMP-3, MMP-9, and MMP-13 levels showed very strong upregulation, which may cause overly strong reactions in animals. Therefore, a dose of 2 mg appears optimal, as it induces significant but not excessive OA-like changes in a rat model.

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.

Matrix Metalloproteinase 13 Inhibitors for Modulation of Osteoclastogenesis: Enhancement of Solubility and Stability

Matrix metalloproteinase 13 (MMP-13) activity has been correlated to breast cancer bone metastasis. It has been proposed that MMP-13 contributes to bone metastasis through the promotion of osteoclastogenesis. To explore the mechanisms of MMP-13 action, we previously described a highly efficacious and selective MMP-13 inhibitor, RF036. Unfortunately, further pursuit of RF036 as a probe of MMP-13 in vitro and in vivo activities was not practical due to the limited solubility and stability of the inhibitor. Our new study has explored replacing the RF036 backbone sulfur atom and terminal methyl group to create inhibitors with more favorable pharmacokinetic properties. One compound, designated inhibitor 3, in which the backbone sulfur and terminal methyl group of RF036 were replaced by nitrogen and oxetane, respectively, had comparable activity, selectivity, and membrane permeability to RF036, while exhibiting greatly enhanced solubility and stability. Inhibitor 3 effectively inhibited MMP-13-mediated osteoclastogenesis but spared collagenolysis, and thus represents a next-generation MMP-13 probe applicable for in vivo studies of breast cancer metastasis.

Changes of type II collagenase biomarkers on IL-1β-induced rat articular chondrocytes

Osteoarthritis (OA) is characterized by progressive degeneration of cartilage, formation of cartilage at the cartilage edge, and remodeling of the subchondral bone. Pro-inflammatory cytokines [e.g., interleukin (IL)-1β] that induce inflammation and promote chondrocyte damage induce OA. Currently, the diagnosis of OA is commonly based on imaging examinations (e.g., X-ray) and evaluations of clinical symptoms; however, biomarkers that can effectively diagnose OA are currently not available. By studying the mechanism underlying OA cartilage injury and changes in the concentrations of the biomarkers procollagen type II carboxy-terminal propeptide (PIICP), collagen type-II C-telopeptide fragments (CTX-II), and type II collagen cleavage neoepitope (C2C) during pathogenesis, the present study established a theoretical basis for the evaluation and early diagnosis of OA. In an experiment, 10 ng/ml IL-1β was used to the treat chondrocyte-induced OA models in vitro for 0, 12, 24 and 48 h. Western blotting was used to detect the expression levels of matrix metalloproteinase (MMP)-3, MMP-13, and inducible nitric oxide synthase (iNOS) protein at each time-point. The concentrations of CTX-II, C2C, and PIICP in the cell culture supernatant were detected by ELISA kit. A biochemical kit was used to detect changes of nitric oxide (NO) in the cell culture supernatant. In addition, chondrocytes were treated with 10 ng/ml IL-1β for 0, 30, 60 and 90 min and the translocation and phosphorylation of the NF-κB pathway were investigated by western blotting. Following IL-1β stimulation, the NF-κB pathway was activated to increase the expression levels of MMPs and iNOS synthesis downstream of the pathway, resulting in an increased degradation of type II collagen (Col II). To sum up, pro-inflammatory IL-1β induced an OA chondrocyte model. During the development of OA, the expression of MMPs and NO increased and Col II was degraded.

CB2 agonism controls pain and subchondral bone degeneration induced by mono-iodoacetate: Implications GPCR functional bias and tolerance development

BACKGROUND AND PURPOSE

The endocannabinoid system became a promising target for osteoarthritis (OA) treatment. Functional selectivity of cannabinoids may increase their beneficial properties while reducing side effects. The aim of the present study was to evaluate the analgesic potential of two functionally biased CB2 agonists in different treatment regimens to propose the best pharmacological approach for OA management.

EXPERIMENTAL APPROACH

Two functionally selective CB2 agonists were administered i.p. - JWH133 (cAMP biased) and GW833972A (β-arrestin biased), in a chemically induced model of OA in rats. The drugs were tested in acute and chronic treatment regimens. Analgesic effects were assessed by pressure application measurement and kinetic weight bearing. X-ray microtomography was used for the morphometric analysis of the femur's subchondral bone tissue. Underlying biochemical changes were analysed via RT-qPCR.

KEY RESULTS

Dose-response studies established the effective dose for both JWH133 and GW833972A. In chronic treatment paradigms, JWH133 was able to elicit analgesia throughout the course of the experiment, whereas GW833972A lost its efficacy after 2 days of treatment. Later studies revealed improvement in subchondral bone architecture and decrement of matrix metalloproteinases and proinflammatory factors expression following JWH133 chronic treatment.

CONCLUSION AND IMPLICATIONS

Data presents analgesic and disease-modifying potential of CB2 agonists in OA treatment. Moreover, the study revealed more pronounced tolerance development for analgesic effects of the β-arrestin biased CB2 agonist GW833972A. These results provide a better understanding of the molecular underpinnings of the anti-nociceptive potential of CB2 agonists and may improve drug development processes for any cannabinoid-based chronic pain therapy.

Polymeric zinc-doped nanoparticles for high performance in restorative dentistry

OBJECTIVES

The aim was to state the different applications and the effectiveness of polymeric zinc-doped nanoparticles to achieve dentin remineralization.

DATA, SOURCES AND STUDY SELECTION

Literature search was conducted using electronic databases, such as PubMed, MEDLINE, DIMDI, Embase, Scopus and Web of Science. A narrative exploratory review was undertaken.

CONCLUSIONS

Polymeric nanospheres (NPs) were efficiently loaded with zinc. NPs sequestered calcium and phosphate in the presence of silicon, and remained effectively embedded at the hybrid layer. NPs incorporation did not alter bond strength and inhibited MMP-mediated dentin collagen degradation. Zn-loaded NPs remineralized the hybrid layer inducing a generalized low-carbonate substitute apatite precipitation, chemically crystalline with some amorphous components, and an increase in mechanical properties was also promoted. Viscoelastic analysis determined that dentin infiltrated with Zn-NPs released the stress by breaking the resin-dentin interface and creating specific mineral formations in response to the energy dissipation. Bacteria were scarcely encountered at the resin-dentin interface. The combined antibacterial and remineralizing effects, when Zn-NPs were applied, reduced biofilm formation. Zn-NPs application at both cervical and radicular dentin attained the lowest microleakage and also promoted durable sealing ability. The new zinc-based salt minerals generated covered the dentin surface totally occluding cracks, porosities and dentinal tubules.

CLINICAL SIGNIFICANCE

Zinc-doped NPs are proposed for effective dentin remineralization and tubular occlusion. This offers new strategies for regeneration of eroded cervical dentin, effective treatment of dentin hypersensitivity and in endodontically treated teeth previous to the canal filling. Zn-NPs also do reduce biofilm formation due to antibacterial properties.

PTH1-34 inhibited TNF-α expression and antagonized TNF-α-induced MMP13 expression in MIO mice

This study aims to investigate the effects and mechanisms of parathyroid hormone [1-34] (PTH1-34) on TNF-α-stimulated mice chondrocytes, as well as cartilage from a meniscus injury induced osteoarthritis (MIO) mice model. The C57BL/6J mice received medial meniscectomy, and then administrated with PTH1-34. The results showed that PTH1-34 administration decreased secondary allodynia and the pain-related transcripts. The IHC, ELISA, Micro-CT imaging and histopathology analysis revealed the significantly improved subchondral plate thickness and bone porosity, the reduced pro-inflammatory cytokines in serum and joint fluid. In vitro, mice chondrocyte was treated with TNF-α or co-cultured with synovial cells. The results showed that TNF-α markedly upregulated the MMP13 expression, and the ERK1/2, NF-κB or PI3K signaling pathway inhibitors could reverse the induction effect of TNF-α on expression of MMP13 in chondrocytes. PTH1-34 alone has no effect on the expression of MMP13 and NF-κB signaling pathways, but the PTH1-34 could reverse the induction effect of TNF-α on MMP13 expression and NF-κB signaling pathway activation in chondrocytes. In addition, PTH1-34 administration inhibited the expression of TNF-α and MMP13, and chondrocyte viability, while the PKA repressor reversed the effect of PTH1-34 in chondrocytes co-cultured with synovial cells. In conclusion, PTH1-34 has an obvious analgesic and anti-inflammatory effect, inhibits the matrix synthesis and alleviates the progression of osteoarthritis. In vitro, PTH1-34 inhibited TNF-α expression and antagonized TNF-α-induced MMP13 expression via the PKA pathway and the NF-κB signaling pathways, respectively.

Inhibition of GPR17 with pranlukast protects against TNF-α-induced loss of type II collagen in ATDC5 cells

Osteoarthritis (OA) is a common joint disease affecting millions of elderly people worldwide. However, the mechanism of OA is complicated and remains poorly understood. Thus, a safe and effective therapeutic strategy has yet to be developed. G protein-coupled receptor 17 (GPR17) is an orphan receptor that is widely distributed in the central nervous system (CNS). GPR17 has become a target for the treatment of inflammation in brain diseases. In this study, we demonstrate that GPR17 is expressed in ATDC5 cells and is increased in response to TNF-α exposure. We also found that antagonism of GPR17 with pranlukast significantly inhibited oxidative stress by downregulating the intracellular level of reactive oxygen species (ROS) and increasing the activity of super oxide dismutase (SOD) against TNF-α. Interestingly, treatment with pranlukast prevented TNF-α-induced reduction of type II collagen. Additionally, knockdown of GPR17 with siRNA ameliorated TNF-α-induced loss of type II collagen, suggesting the importance of the role of GPR17 in mediating the impairment of type II collagen. Blockage of GPR17 with pranlukast suppressed the expression of matrix metalloproteinases 3 (MMP-3) and matrix metalloproteinases 13 (MMP-13), which contribute to the degradation of type II collagen. Pranlukast also prevented the activation of the JAK2/STAT1/IRF-1 signaling pathway, thereby suppressing the expression of pro-inflammatory cytokines and enzymes. Furthermore, pranlukast rescued TNF-α-induced reduced SOX-9 expression. Together, our data indicate that GPR17 might be a potential target for the treatment of OA.

Selective MMP-13 Inhibitors: Promising Agents for the Therapy of Osteoarthritis

Osteoarthritis (OA) is an age-related degenerative disease, which is characterized by chronic joint pain, inflammation and the damage of joint cartilage. At present, steroidal drugs and nonsteroidal anti-inflammatory drugs (NSAIDS), selective cyclooxygenase-2 (COX-2) inhibitors, are the first-line drugs for the treatment of OA. However, these drugs could lead to some cardiovascular side effects. Therefore, it is urgent to develop novel agents for the treatment of OA. Matrix metalloproteinase-13 (MMP-13), an important member of matrix metalloproteinases (MMPs) family, plays a vital role by degrading type II collagen in articular cartilage and bone in OA. It is noted that MMP-13 is specially expressed in the OA patients, and not in normal adults. In addition, broadspectrum MMP inhibitors could result in some painful and joint-stiffening side effects, called musculoskeletal syndrome (MSS) in the clinical trials. Thus, developing selective MMP-13 inhibitors is a potential strategy for the therapy of OA. In this review, we summarize the recent progress of selective MMP-13 inhibitors including two subfamilies, namely zinc-binding and non-zinc-binding selective MMP-13 inhibitors.

Lunasin abrogates the expression of matrix metalloproteinases and reduction of type II collagen

Impairment of type II collagen caused by MMPs in response to overproduction of IL-1β is an important step in the pathological progression of osteoarthritis (OA). Lunasin, a well-known peptide present in the soybean, has displayed a positive impact on numerous physiological functions. Little information in the effects of lunasin on cartilage degradation has been sought in clinical research before. Here, we report that lunasin suppressed the increase in MMP-3 and MMP-13 caused by IL-1β. In addition, we found that lunasin could prevent the decrease in TIMP-1 and TIMP-2 expressions caused by IL-1β. Notably, lunasin suppressed reduction of type II collagen, the basis for articular cartilage. Lunasin also attenuated activation of the JAK2/STAT1/IRF-1 pathway. These effects of lunasin suggest that it might become a promising therapeutic agent for chondro-protective therapy.

Profile of Matrix-Remodeling Proteinases in Osteoarthritis: Impact of Fibronectin

The extracellular matrix (ECM) is a complex and specialized three-dimensional macromolecular network, present in nearly all tissues, that also interacts with cell surface receptors on joint resident cells. Changes in the composition and physical properties of the ECM lead to the development of many diseases, including osteoarthritis (OA). OA is a chronic degenerative rheumatic disease characterized by a progressive loss of synovial joint function as a consequence of the degradation of articular cartilage, also associated with alterations in the synovial membrane and subchondral bone. During OA, ECM-degrading enzymes, including urokinase-type plasminogen activator (uPA), matrix metalloproteinases (MMPs), and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs), cleave ECM components, such as fibronectin (Fn), generating fibronectin fragments (Fn-fs) with catabolic properties. In turn, Fn-fs promote activation of these proteinases, establishing a degradative and inflammatory feedback loop. Thus, the aim of this review is to update the contribution of ECM-degrading proteinases to the physiopathology of OA as well as their modulation by Fn-fs.

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.

ACY-1215 exhibits anti-inflammatory and chondroprotective effects in human osteoarthritis chondrocytes via inhibition of STAT3 and NF-κB signaling pathways

Cartilage degeneration is a basic pathological feature of osteoarthritis (OA), and there is growing evidence that it is associated with inflammation. ACY-1215, a selective HDAC6 inhibitor, has been reported to have anti-inflammatory effects. Here, we investigated the anti-inflammatory and chondroprotective effects of ACY-1215 in IL-1β-stimulated human primary chondrocytes and C28/I2 cells. The results suggested that ACY-1215 can markedly suppress the expression of inflammatory factors, including IL-1β and IL-6 in human primary chondrocytes and C28/I2 cells. Furthermore, ACY-1215 exerts potent chondroprotection through the amelioration of cartilage degradation by inhibiting the expression of matrix-degrading proteases, including MMP-1 and MMP-13 in chondrocytes. These effects may be related to ACY-1215 induced down-regulation of NF-κB and STAT3 pathways in OA chondrocytes. Taken together, our results show that ACY-1215 may be a potential and promising therapeutic drug for the management of OA.

Chondrocyte and mesenchymal stem cell derived engineered cartilage exhibits differential sensitivity to pro-inflammatory cytokines

Tissue engineering is a promising approach for the repair of articular cartilage defects, with engineered constructs emerging that match native tissue properties. However, the inflammatory environment of the damaged joint might compromise outcomes, and this may be impacted by the choice of cell source in terms of their ability to operate anabolically in an inflamed environment. Here, we compared the response of engineered cartilage derived from native chondrocytes and mesenchymal stem cells (MSCs) to challenge by TNFα and IL-1β in order to determine if either cell type possessed an inherent advantage. Compositional (extracellular matrix) and functional (mechanical) characteristics, as well as the release of catabolic mediators (matrix metalloproteinases [MMPs], nitric oxide [NO]) were assessed to determine cell- and tissue-level changes following exposure to IL-1β or TNF-α. Results demonstrated that MSC-derived constructs were more sensitive to inflammatory mediators than chondrocyte-derived constructs, exhibiting a greater loss of proteoglycans and functional properties at lower cytokine concentrations. While MSCs and chondrocytes both have the capacity to form functional engineered cartilage in vitro, this study suggests that the presence of an inflammatory environment is more likely to impair the in vivo success of MSC-derived cartilage repair. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2901-2910, 2018.

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.

Current status and future prospects for disease modification in osteoarthritis

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

Clinical Implications of Compounds Designed to Inhibit ECM-Modifying Metalloproteinases

Remodeling of the extracellular matrix (ECM) is crucial in development and homeostasis, but also has a significant role in disease progression. Two metalloproteinase families, the matrix metalloproteinases (MMPs) and a disintegrin and metalloproteases (ADAMs), participate in the remodeling of the ECM, either directly or through the liberation of growth factors and cell surface receptors. The correlation of MMP and ADAM activity to a variety of diseases has instigated numerous drug development programs. However, broad-based and Zn²⁺ -chelating MMP and ADAM inhibitors have fared poorly in the clinic. Selective MMP and ADAM inhibitors have been described recently based on (a) antibodies or antibody fragments or (b) small molecules designed to take advantage of protease secondary binding sites (exosites) or allosteric sites. Clinical trials have been undertaken with several of these inhibitors, while others are in advanced pre-clinical stages.

Second Generation Triple-Helical Peptide Inhibitors of Matrix Metalloproteinases

The design of selective matrix metalloproteinase (MMP) inhibitors that also possess favorable solubility properties has proved to be especially challenging. A prior approach using collagen-model templates combined with transition state analogs produced a first generation of triple-helical peptide inhibitors (THPIs) that were effective in vitro against discrete members of the MMP family. These THPI constructs were also highly water-soluble. The present study sought improvements in the first generation THPIs by enhancing thermal stability and selectivity. A THPI selective for MMP-2 and MMP-9 was redesigned to incorporate non-native amino acids (Flp and mep), resulting in an increase of 18 °C in thermal stability. This THPI was effective in vivo in a mouse model of multiple sclerosis, reducing clinical severity and weight loss. Two other THPIs were developed to be more selective within the collagenolytic members of the MMP family. One of these THPIs was serendipitously more effective against MMP-8 than MT1-MMP and was utilized successfully in a mouse model of sepsis. The THPI targeting MMP-8 minimized lung damage, increased production of the anti-inflammatory cytokine IL-10, and vastly improved mouse survival.

Coptisine Prevented IL-β-Induced Expression of Inflammatory Mediators in Chondrocytes

Interleukin 1β (IL-1β) is a pleiotropic pro-inflammatory cytokine that plays a critical role in the development of osteoarthritis (OA). Coptisine is an isoquinoline alkaloid extracted from Coptidis rhizome and has been reported to possess anti-inflammatory activity. However, the anti-inflammatory effects of coptisine on interleukin-1 beta (IL-1β)-stimulated chondrocytes have not been reported. Therefore, the aim of this study was to investigate the effects of coptisine on IL-1β-induced inflammation in human articular chondrocytes. Our results showed that coptisine greatly inhibited the production of nitric oxide (NO) and prostaglandin E2 (PGE2), as well as suppressed the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in human OA chondrocytes induced by IL-1β. It also inhibited the expression of matrix metalloproteinase-3 (MMP-3) and MMP-13 in IL-1β-stimulated human OA chondrocytes. Furthermore, coptisine significantly inhibited the IL-1β-induced NF-kB activation in human OA chondrocytes. Taken together, these data suggest that coptisine inhibits the IL-1β-induced inflammatory response by suppressing the NF-kB signaling pathway. Thus, coptisine may be a potential agent in the treatment of OA.

In vivo evaluation of Mg-6Zn and titanium alloys on collagen metabolism in the healing of intestinal anastomosis

There is a great clinical need for biodegradable materials, which were used as pins of circular staplers, for gastrointestinal reconstruction in medicine. In this work we compared the effects of the Mg-6Zn and the titanium alloys on collagen metabolism in the healing of the intestinal tract in vivo. The study included Sprague-Dawley rats and their effect was compared on rat's intestinal tract, using serum magnesium, radiology, and immunohistochemistry in vivo. Radiographic and scanning electron microscope evaluation confirmed the degradation by Mg-6Zn alloy during the implantation period. Biochemical measurements including serum magnesium, creatinine, blood urea nitrogen and glutamic-pyruvic-transaminase proved that degradation of Mg-6Zn alloy showed no impact on serum magnesium and the function of other important organs. Superior to titanium alloy, Mg-6Zn alloy enhanced the expression of collagen I/III and relatively suppressed the expression of MMP-1/-13 in the healing tissues, leading to more mature collagen formation at the site of anastomosis. In conclusion, Mg-6Zn alloy performed better than titanium alloy on collagen metabolism and promoted the healing of intestinal anastomosis. Hence, Mg-6Zn may be a promising candidate for use of stapler pins for intestinal reconstruction in the clinically.

Functional characterization of selective exosite-binding inhibitors of matrix metalloproteinase-13 (MMP-13) – experimental validation in human breast and colon cancer

Considering the pathological significance of MMP-13 in breast and colon cancers, exosite-based inhibition of the C-terminal hemopexin (Hpx) domain could serve as an alternative strategy to develop selective inhibitors for MMP-13.Two of six lead compounds, compound 5 (2,3-dihydro-1,4-benzodioxine-5-carboxylic acid) and compound 6 (1-acetyl-4-hydroxypyrrolidine-2-carboxylic acid) exhibited considerable inhibitory activity against MMP-13. Complementing to this study, we have also shown the gene expression levels of MMP-13 within the subtypes of colon and breast cancers classified from patients’ tissue samples to provide a better understanding on which subtype of breast cancer patients would get benefited by MMP-13 inhibitors.Our current results show that compounds 5 and 6 could effectively inhibit MMP-13 and provide specific therapeutic possibilities in the treatment of inflammatory disorders and cancers. The characterization of these lead compounds would provide a better mechanistic understanding of exosite-based inhibition of MMP-13, which could overcome the challenges in the identification of other MMP catalytic domain-specific inhibitors.

Potential of Pseudoshikonin I Isolated from Lithospermi Radix as Inhibitors of MMPs in IL-1β-Induced SW1353 Cells

Pseudoshikonin I, the new bioactive constituent of Lithospermi radix, was isolated from this methanol extract by employing reverse-phase medium-pressure liquid chromatography (MPLC) using acetonitrile/water solvent system as eluents. The chemical structure was determined based on spectroscopic techniques, including 1D NMR (¹H, ¹³C, DEPT), 2D NMR (gCOSY, gHMBC, gHMQC), and QTOF/MS data. In this study, we demonstrated the effect of pseudoshikonin I on matrix-metalloproteinase (MMPs) activation and expression in interleukin (IL)-1β-induced SW1353 chondrosarcoma cells. MMPs are considered important for the maintenance of the extracellular matrix. Following treatment with PS, active MMP-1, -2, -3, -9, -13 and TIMP-2 were quantified in the SW1353 cell culture supernatants using a commercially available ELISA kit. The mRNA expression of MMPs in SW1353 cells was measured by RT-PCR. Pseudoshikonin I treatment effectively protected the activation on all tested MMPs in a dose-dependent manner. TIMP-2 mRNA expression was significantly upregulated by pseudoshikonin I treatment. Overall, we elucidated the inhibitory effect of pseudoshikonin on MMPs, and we suggest its use as a potential novel anti-osteoarthritis agent.

SAR Studies of Exosite-Binding Substrate-Selective Inhibitors of A Disintegrin And Metalloprotease 17 (ADAM17) and Application as Selective in Vitro Probes

ADAM17 is implicated in several debilitating diseases. However, drug discovery efforts targeting ADAM17 have failed due to the utilization of zinc-binding inhibitors. We previously reported discovery of highly selective nonzinc-binding exosite-targeting inhibitors of ADAM17 that exhibited not only enzyme isoform selectivity but synthetic substrate selectivity as well ( J. Biol. Chem. 2013, 288, 22871). As a result of SAR studies presented herein, we obtained several highly selective ADAM17 inhibitors, six of which were further characterized in biochemical and cell-based assays. Lead compounds exhibited low cellular toxicity and high potency and selectivity for ADAM17. In addition, several of the leads inhibited ADAM17 in a substrate-selective manner, which has not been previously documented for inhibitors of the ADAM family. These findings suggest that targeting exosites of ADAM17 can be used to obtain highly desirable substrate-selective inhibitors. Additionally, current inhibitors can be used as probes of biological activity of ADAM17 in various in vitro and, potentially, in vivo systems.

New strategies for targeting matrix metalloproteinases

The development of matrix metalloproteinase (MMP) inhibitors has often been frustrated by a lack of specificity and subsequent off-target effects. More recently, inhibitor design has considered secondary binding sites (exosites) to improve specificity. Small molecules and peptides have been developed that bind exosites in the catalytic (CAT) domain of MMP-13, the CAT or hemopexin-like (HPX) domain of MT1-MMP, and the collagen binding domain (CBD) of MMP-2 and MMP-9. Antibody-based approaches have resulted in selective inhibitors for MMP-9 and MT1-MMP that target CAT domain exosites. Triple-helical “mini-proteins” have taken advantage of collagen binding exosites, producing a family of novel probes. A variety of non-traditional approaches that incorporate exosite binding into the design process has yielded inhibitors with desirable selectivities within the MMP family.

Characterization of selective exosite-binding inhibitors of matrix metalloproteinase 13 that prevent articular cartilage degradation in vitro

Matrix metalloproteinase 13 (MMP-13) has been shown to be the main collagenase responsible for degradation of articular cartilage during osteoarthritis and therefore represents a target for drug development. As a result of high-throughput screening and structure-activity relationship studies, we identified a novel, highly selective class of MMP-13 inhibitors (compounds 1 (Q), 2 (Q1), and 3 (Q2)). Mechanistic characterization revealed a noncompetitive nature of these inhibitors with binding constants in the low micromolar range. Crystallographic analyses revealed two binding modes for compound 2 in the MMP-13 S1' subsite and in an S1/S2* subsite. Type II collagen- and cartilage-protective effects exhibited by compounds 1, 2, and 3 suggested that these compounds might be efficacious in future in vivo studies. Finally, these compounds were also highly selective when tested against a panel of 30 proteases, which, in combination with a good CYP inhibition profile, suggested low off-target toxicity and drug-drug interactions in humans.

Anti-inflammatory and chondroprotective activity of (+)-α-pinene: structural and enantiomeric selectivity

Previous studies have suggested that α-pinene, a common volatile plant metabolite, may have anti-inflammatory effects in human chondrocytes, thus exhibiting potential antiosteoarthritic activity. The objective of this study was to further characterize the potential antiosteoarthritic activity of selected pinene derivatives by evaluating their ability to modulate inflammation and extracellular matrix remodeling in human chondrocytes and to correlate the biological and chemical properties by determining whether the effects are isomer- and/or enantiomer-selective. To further elucidate chemicopharmacological interactions, the activities of other naturally occurring monoterpenes with the pinane nucleus were also investigated. At noncytotoxic concentrations, (+)-α-pinene (1) elicited the most potent inhibition of the IL-1β-induced inflammatory and catabolic pathways, namely, NF-κB and JNK activation and the expression of the inflammatory (iNOS) and catabolic (MMP-1 and -13) genes. (-)-α-Pinene (2) was less active than the (+)-enantiomer (1), and β-pinene (3) was inactive. E-Pinane (4) and oxygenated pinane-derived compounds, pinocarveol (5), myrtenal (6), (E)-myrtanol (7), myrtenol (8), and (Z)-verbenol (9), were less effective or even completely inactive and more cytotoxic than the pinenes tested (1-3). The data obtained show isomer- and enantiomer-selective anti-inflammatory and anticatabolic effects of α-pinene in human chondrocytes, (+)-α-pinene (1) being the most promising for further studies to determine its potential value as an antiosteoarthritic drug.

Small molecule inhibitors of WNT/β-catenin signaling block IL-1β- and TNFα-induced cartilage degradation

Introduction

In this study, we tested the ability of small molecule inhibitors of WNT/β-catenin signaling to block interleukin 1β (IL-1β)- and tumor necrosis factor α (TNFα)-induced cartilage degradation. Proinflammatory cytokines such as IL-1β and TNFα are potent inducers of cartilage degradation by upregulating matrix metalloproteinase (MMP) expression and activity. Because WNT/β-catenin signaling was found to be involved in IL-1β- and TNFα-induced upregulation of MMP activity, we hypothesized that inhibition of WNT/β-catenin signaling might block IL-1β- and TNFα-induced cartilage degradation. We tested the effect of small molecules that block the interaction between β-catenin and TCF/Lef transcription factors on IL-1β- and TNFα-induced cartilage degradation in mouse fetal metatarsals.

Methods

We used mouse fetal metatarsals treated with IL-1β and TNFα as an ex vivo model for cytokine-induced cartilage degradation. Metatarsals were treated with IL-1β and TNFα in combination with the small molecules PKF115-584, PKF118-310 and CGP049090 at different concentrations and then harvested them for histological and gene expression analysis.

Results

We found that IL-1β- and TNFα-induced cartilage degradation in mouse fetal metatarsals was blocked by inhibiting WNT/β-catenin signaling using small molecule PKF115-584 and partially using CGP049090 dose-dependently. In addition, we found that PKF115-584 blocked IL-1β- and TNFα-induced MMP mRNA expression, but did not reverse the inhibitory effect of IL-1β on the expression of cartilage anabolic genes.

Conclusion

In this study, we show that inhibition of WNT/β-catenin signaling by small molecules can effectively prevent IL-1β- and TNFα-induced cartilage degradation by blocking MMP expression and activity. Furthermore, we elucidate the involvement of WNT/β-catenin signaling in IL-1β- and TNFα-induced cartilage degradation.

CIINE Reflects Collagenase-Specific CII Breakdown in Cartilage Explant and Whole Body of Canine

To evaluate collagenase inhibitors for the treatment of osteoarthritis and to correlate them with clinical pathology, canine cartilage explant and anterior cruciate ligament transection (ACLT) models were examined by quantifying the CII neoepitope (CIINE). This peptide is a putative marker for collagenase-specific type II collagen (CII) degradation, which is a critical step in osteoarthritis pathology.

The concentration of CIINE in supernatants of canine cartilage explants showed increase upon IL-1β—stimulation and collagenase inhibitors suppressed this elevation of CIINE. In the canine ACLT model, levels of CIINE in urine (uCIINE) increased as lesions of knee joint cartilage developed and decreased in response to collagenase inhibitors.

Our results suggest that CIINE reflects collagenase-specific CII degradation in canine explants and whole bodies. It is anticipated that these data will establish a tool for clarifying and bridging the efficacy and mechanism of collagenase inhibitors at the preclinical stage of drug discovery.