Therapeutic options for targeting inflammatory osteoarthritis pain

Nomilin targets the Keap1-Nrf2 signalling and ameliorates the development of osteoarthritis

Osteoarthritis (OA) is a long-term and inflammatory disorder featured by cartilage erosion. Here, we describe nomilin (NOM), a triterpenoid with inflammation modulatory properties in variety of disorders. In this study, we demonstrated the latent mechanism of NOM in alleviating the progress of OA both in vitro and in vivo studies. The results showed that NOM pre-treatment suppressed the IL-1β-induced over-regulation of pro-inflammation factors, such as NO, IL-6, PGE2 , iNOS, TNF-α and COX-2. Moreover, NOM also down-regulates the degradation of ECM induced by IL-1β. Mechanistically, the NOM suppressed NF-κB signalling via disassociation of Keap1-Nrf2 in chondrocytes. Furthermore, NOM delays the disease progression in the mouse OA model. To sum up, this research indicated NOM possessed a new potential therapeutic option in osteoarthritis.

GM-CSF in inflammation

GM-CSF is a potential therapeutic target in inflammation and autoimmunity. This study reviews the literature on the biology of GM-CSF, in particular that describing the research leading to clinical trials targeting GM-CSF and its receptor in numerous inflammatory/autoimmune conditions, such as rheumatoid arthritis.

Granulocyte–macrophage colony-stimulating factor (GM-CSF) has many more functions than its original in vitro identification as an inducer of granulocyte and macrophage development from progenitor cells. Key features of GM-CSF biology need to be defined better, such as the responding and producing cell types, its links with other mediators, its prosurvival versus activation/differentiation functions, and when it is relevant in pathology. Significant preclinical data have emerged from GM-CSF deletion/depletion approaches indicating that GM-CSF is a potential target in many inflammatory/autoimmune conditions. Clinical trials targeting GM-CSF or its receptor have shown encouraging efficacy and safety profiles, particularly in rheumatoid arthritis. This review provides an update on the above topics and current issues/questions surrounding GM-CSF biology.

Bone marrow mesenchymal stem cell-derived exosomes protect cartilage damage and relieve knee osteoarthritis pain in a rat model of osteoarthritis

Background

This study aimed to investigate the effect of bone marrow mesenchymal stem cell (BMSC)-derived exosome injection on cartilage damage and pain relief in both in vitro and in vivo models of osteoarthritis (OA).

Methods

The BMSCs were extracted from rat bone marrow of the femur and tibia. Chondrocytes were treated with IL-1β to establish the in vitro model of OA. Chondrocyte proliferation and migration were assessed by CCK-8 and transwell assay, respectively. A rat model of OA was established by injection of sodium iodoacetate. At 6 weeks after the model was established, the knee joint specimens and dorsal root ganglion (DRG) of rats were collected for histologic analyses. For pain assessment, paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were evaluated before model establishment and at 1, 2, 4, and 6 weeks after model establishment.

Results

Exosomes can be endocytosed with the chondrocytes in vitro. Exosome treatment significantly attenuated the inhibitory effect of IL-1β on the proliferation and migration of chondrocytes. Exosome pre-treatment significantly attenuated IL-1β-induced downregulation of COL2A1 and ACAN and upregulation of MMP13 and ADAMTS5. In the animal study, exosome treatment significantly upregulated COL2A1 protein and downregulated MMP13 protein in the cartilage tissue of the OA rat. At weeks 2, 4, and 6, the PWL value was significantly improved in the exosome-treated OA rats as compared with the untreated OA animals. Moreover, exosome treatment significantly alleviated the upregulation of CGRP and iNOS in the DRG tissue of OA rats.

Conclusion

BMSC-derived exosomes can effectively promote cartilage repair and extracellular matrix synthesis, as well as alleviate knee pain in the OA rats.

MiR-1207-5p/CX3CR1 axis regulates the progression of osteoarthritis via the modulation of the activity of NF-κB pathway

BACKGROUND

Osteoarthritis (OA) is a prevalent chronic diseases characterized by formation of osteophytes and degradation of articular cartilage. Previous evidence has identified the regulatory effects of microRNAs (miRNAs) in OA. The goal of this study is to clearly explore the biological function of miR-1207-5p in OA.

METHODS

MiR-1207-5p and C-X3-C motif chemokine receptor 1 (CX3CR1) expression in OA cartilages were revealed by accessing to Gene Expression Omnibus database. In vitro OA model was established by lipopolysaccharide (LPS) stimulation. Western blot and quantitative real-time polymerase chain reaction were conducted to detect the expression level of genes. Cell counting kit-8 (CCK-8) and flow cytometric experiments were performed to investigate the proliferation and apoptosis capacities of CHON-001 cells. Bioinformatics analysis was applied to predict the binding site of miR-1207-5p and CX3CR1, the connections of which were ascertained using luciferase reporter assay.

RESULTS

MiR-1207-5p expression was decreased while CX3CR1 was increased in OA cartilages. Up-regulation of miR-1207-5p alleviated the LPS-induced damage in the view of cell proliferation, apoptosis and extracellular matrix (ECM) degradation. A target of miR-1207-5p CX3CR1, its down-regulation intensified the impacts of miR-1207-5p mimic, promoted proliferation and mitigated apoptosis. LPS exposure increased the protein expression of the phosphorylated IκBα and P65, and this phenomena was reversed due to miR-1207-5p up-regulation and CX3CR1 knockdown. The treatment of Betulinic acid (BA; an activator of nuclear factor-κB pathway) reversed the miR-1207-5p mimic-induced inhibitory effect on apoptosis in LPS-treated CHON-001.

CONCLUSION

Our results highlight that miR-1207-5p can prevent CHON-001 from LPS-stimulated injury, providing a novel biomarker for OA progression and further advancing treatment of OA.

Initial analgesic prescriptions for osteoarthritis in the United Kingdom, 2000–2016

Objectives

To examine trends in the initial prescription of commonly-prescribed analgesics and patient- as well as practice-level factors related to their selection in incident OA.

Methods

Patients consulting with incident clinical OA between 2000–2016 were identified within The Health Improvement Network in the United Kingdom (UK) general practice. Excluded were patients who had history of cancer or were prescribed the analgesics of interest within 6 months before diagnosis of OA. Initial analgesic prescription included oral non-selective NSAID, oral selective cyclooxygenase-2 inhibitor, topical NSAID, paracetamol, topical salicylate or oral/transdermal opioid within 1 month after OA diagnosis.

Results

∼44% of patients with incident OA (n = 125 696) were prescribed one of these analgesics. Incidence of oral NSAID prescriptions decreased whereas other analgesic prescriptions, including oral opioid prescriptions, increased (all P-for-trend < 0.001). Patients with a history of gastrointestinal disease were more likely to receive topical NSAIDs, paracetamol or oral/transdermal opioids. Only 38% of patients with history of gastrointestinal disease and 21% of patients without it had co-prescription of gastroprotective agent with oral NSAIDs. Oral/transdermal opioid prescription was higher among the elderly (≥65 years), women, obesity, current smoker, and patients with gastrointestinal, cardiovascular or chronic kidney disease. Prescription of oral opioids increased with social deprivation (P-for-trend < 0.05) and was highest in Scotland, whereas transdermal opioid prescription was highest in Northern Ireland (all P-for-homogeneity-test < 0.05).

Conclusion

The initial prescription pattern of analgesics for OA has changed over time in the UK. Co-prescription of gastroprotective agents with oral NSAIDs remains suboptimal, even among those with prior gastrointestinal disease.

CCL17 in Inflammation and Pain

It has been reported that a GM-CSF→CCL17 pathway, originally identified in vitro in macrophage lineage populations, is implicated in the control of inflammatory pain, as well as arthritic pain and disease. We explore, in this study and in various inflammation models, the cellular CCL17 expression and its GM-CSF dependence as well as the function of CCL17 in inflammation and pain. This study used models allowing the convenient cell isolation from Ccl17^E/+ reporter mice; it also exploited both CCL17-dependent and unique CCL17-driven inflammatory pain and arthritis models, the latter permitting a radiation chimera approach to help identify the CCL17 responding cell type(s) and the mediators downstream of CCL17 in the control of inflammation and pain. We present evidence that 1) in the particular inflammation models studied, CCL17 expression is predominantly in macrophage lineage populations and is GM-CSF dependent, 2) for its action in arthritic pain and disease development, CCL17 acts on CCR4⁺ non-bone marrow-derived cells, and 3) for inflammatory pain development in which a GM-CSF→CCL17 pathway appears critical, nerve growth factor, CGRP, and substance P all appear to be required.

Differential Secretome Profiling of Human Osteoarthritic Synoviocytes Treated with Biotechnological Unsulfated and Marine Sulfated Chondroitins

Symptomatic slow-acting drugs (SYSADOA) are increasingly used as effective therapies for osteoarthritis, representing an attractive alternative to analgesics or non-steroidal anti-inflammatory drugs to relieve disease symptoms. Pharmaceutical preparations of chondroitin sulfate, derived from animal sources, alone or in combination with glucosamine sulfate, are widely recognized for their beneficial effect on osteoarthritis treatment. A growing interest has also been devoted to understanding the molecular mechanisms modulated by SYSADOA using -omic strategies, most of which rely on chondrocytes as a model system. In this work, by using an integrated strategy based on unbiased proteomics and targeted cytokine profiling by a multiplexed protein array, we identified differences in the secretomes of human osteoarthritic synoviocytes in response to biotechnological unsulfated, and marine sulfated chondroitins treatments. The combined strategy allowed the identification of candidate proteins showing both common and distinct regulation responses to the two treatments of chondroitins. These molecules, mainly belonging to ECM proteins, enzymes, enzymatic inhibitors and cytokines, are potentially correlated to treatment outcomes. Overall, the present results provide an integrated overview of protein changes in human osteoarthritic synoviocytes secretome associated to different chondroitin treatments, thus improving current knowledge of the biochemical effects driven by these drugs potentially involved in pathways associated to osteoarthritis pathogenesis.

Moderate Mechanical Stimulation Protects Rats against Osteoarthritis through the Regulation of TRAIL via the NF-κB/NLRP3 Pathway

The aim of this study was to examine exercise-related genes in articular cartilage identified through bioinformatics analysis to dissect the potential signaling pathway involved in mechanical stimulation in osteoarthritis (OA). To this end, we evaluated the GSE74898 dataset from the Gene Expression Omnibus database for exercise-related differentially expressed miRNAs (DE-miRNAs) using the R software package and predicted potential target genes for these miRNAs using miRTarBase. Functional annotation and pathway enrichment analysis were performed for these potential DE-miRNA targets. The effects of mechanical stimulation on the tumor necrosis factor-related apoptosis-induced ligand (TRAIL)/nuclear factor-kappa B (NF-κB)/nucleotide-binding and oligomerization domain-like receptor containing protein 3 (NLRP3) signaling pathway were evaluated in articular cartilage and chondrocytes. A total of 394 DE-miRNAs were identified (103 upregulated miRNAs; 291 downregulated miRNAs) in the cartilage of rats following treadmill exercise compared to the cartilage of unexercised control rats. Thus, mechanical stimulation could modulate the TRAIL/NF-κB/NLRP3 signaling pathway on OA. Histological and protein analysis demonstrated that moderate-intensity treadmill exercise could ameliorate OA through the downregulation of TRAIL. Furthermore, moderate cyclic tensile strain (CTS) could rescue chondrocytes from the effects of TRAIL via the inhibition of the nuclear translocation of NF-κB p65 and formation of NLRP3. Our findings indicate that moderate mechanical stimulation could ameliorate the degeneration of cartilage and chondrocyte damage through the inhibition of the TRAIL/NF-κB/NLRP3 pathway.

Dextran sulfate-triamcinolone acetonide conjugate nanoparticles for targeted treatment of osteoarthritis

Osteoarthritis (OA) is a synovial inflammatory condition characterized by cartilage destruction and osteophyte formation. Macrophages play a central role in OA pathogenesis by producing proinflammatory cytokines. Intra-articular corticosteroid administration can relieve refractory pain and inflamed effusion of knee joints. However, limitations, such as rapid clearance from the joint space, potential damage to articular cartilage, and accelerated joint degeneration, may hamper the clinical application of corticosteroids. In this study, we reported the design and preparation of dextran sulfate-triamcinolone acetonide conjugate (DS-TA) nanoparticles (NPs) for treating OA by specifically targeting scavenger receptor class A (SR-A) on activated macrophages. We verified the excellent targeting specificity of DS-TA NPs to SR-A by flow cytometry and confocal laser scanning microscopy. DS-TA NPs were found to effectively reduce the viability of activated macrophages (RAW 264.7 cells) and the expression of proinflammatory cytokines. Intra-articular injection of DS-TA NPs effectively alleviated the structural damages to the joint cartilage, as confirmed in histopathological analysis. Additionally, DS-TA NPs decreased the expression of proinflammatory cytokines, including IL-1β, IL-6, and TNF-α, in the cartilage tissue. Thus, DS-TA NPs are a potential therapeutic nanomedicine for the targeted treatment of OA.

Angiogenesis stimulated by elevated PDGF-BB in subchondral bone contributes to osteoarthritis development

Increased subchondral bone angiogenesis with blood vessels breaching the tidemark into the avascular cartilage is a diagnostic feature of human osteoarthritis. However, the mechanisms that initiate subchondral bone angiogenesis remain unclear. We show that abnormally increased platelet-derived growth factor-BB (PDGF-BB) secretion by mononuclear preosteoclasts induces subchondral bone angiogenesis, contributing to osteoarthritis development. In mice after destabilization of the medial meniscus (DMM), aberrant joint subchondral bone angiogenesis developed during an early stage of osteoarthritis, before articular cartilage damage occurred. Mononuclear preosteoclasts in subchondral bone secrete excessive amounts of PDGF-BB, which activates platelet-derived growth factor receptor-β (PDGFR-β) signaling in pericytes for neo-vessel formation. Selective knockout of PDGF-BB in preosteoclasts attenuates subchondral bone angiogenesis and abrogates joint degeneration and subchondral innervation induced by DMM. Transgenic mice that express PDGF-BB in preosteoclasts recapitulate pathological subchondral bone angiogenesis and develop joint degeneration and subchondral innervation spontaneously. Our study provides the first evidence to our knowledge that PDGF-BB derived from preosteoclasts is a key driver of pathological subchondral bone angiogenesis during osteoarthritis development and offers a new avenue for developing early treatments for this disease.

Targeting GM-CSF for collagenase-induced osteoarthritis pain and disease in mice

OBJECTIVES

Pharmacological options for treating osteoarthritis (OA) are limited and alternative treatments are required. Given the clinical data indicating that granulocyte macrophage-colony stimulating factor (GM-CSF) may be a therapeutic target in human OA, we evaluated different treatment regimens with a neutralizing anti-GM-CSF monoclonal antibody (mAb) in an experimental OA model to determine their effectiveness on amelioration of pain and disease.

METHODS

The collagenase-induced osteoarthritis (CiOA) model was induced in C57BL/6 mice, followed by different treatment regimens of anti-GM-CSF mAb or isotype control. Anti-CCL17 mAb treatment was also administered continually during the late stage of CiOA. Pain-related behavior (change in weight distribution of hind limbs), and disease (cartilage damage and osteophyte size) were assessed.

RESULTS

Blocking GM-CSF only during early synovitis in CiOA prevented pain and disease development. Once OA pain was established, regardless of the treatment regimen, anti-GM-CSF mAb treatment rapidly and efficiently ameliorated it; however, unless the treatment was continued, pain returned and disease progressed. Continual late stage blockade of GM-CSF was able to ameliorate pain (between-group difference: -6.567; 95% confidence interval (CI): -10.12, -3.011) and suppress cartilage damage (P = 0.0317, 95% CI: -1.75, -0.0556). Continual late stage blockade of CCL17 showed similar effects on pain and disease development.

CONCLUSIONS

Early and short-term GM-CSF neutralization is effective at preventing CiOA pain and disease development but, once pain is evident, continual GM-CSF blockade is required to prevent pain from returning and to suppress disease progression in mice. These data reinforce the potential benefits of anti-GM-CSF (and anti-CCL17) mAb therapy in OA and should inform further clinical trials.

Role of Signal Transduction Pathways and Transcription Factors in Cartilage and Joint Diseases

Osteoarthritis and rheumatoid arthritis are common cartilage and joint diseases that globally affect more than 200 million and 20 million people, respectively. Several transcription factors have been implicated in the onset and progression of osteoarthritis, including Runx2, C/EBPβ, HIF2α, Sox4, and Sox11. Interleukin-1 β (IL-1β) leads to osteoarthritis through NF-ĸB, IκBζ, and the Zn²⁺-ZIP8-MTF1 axis. IL-1, IL-6, and tumor necrosis factor α (TNFα) play a major pathological role in rheumatoid arthritis through NF-ĸB and JAK/STAT pathways. Indeed, inhibitory reagents for IL-1, IL-6, and TNFα provide clinical benefits for rheumatoid arthritis patients. Several growth factors, such as bone morphogenetic protein (BMP), fibroblast growth factor (FGF), parathyroid hormone-related protein (PTHrP), and Indian hedgehog, play roles in regulating chondrocyte proliferation and differentiation. Disruption and excess of these signaling pathways cause genetic disorders in cartilage and skeletal tissues. Fibrodysplasia ossificans progressive, an autosomal genetic disorder characterized by ectopic ossification, is induced by mutant ACVR1. Mechanistic target of rapamycin kinase (mTOR) inhibitors can prevent ectopic ossification induced by ACVR1 mutations. C-type natriuretic peptide is currently the most promising therapy for achondroplasia and related autosomal genetic diseases that manifest severe dwarfism. In these ways, investigation of cartilage and chondrocyte diseases at molecular and cellular levels has enlightened the development of effective therapies. Thus, identification of signaling pathways and transcription factors implicated in these diseases is important.

Macrophage: A Potential Target on Cartilage Regeneration

Cartilage lesions and osteoarthritis (OA) presents an ever-increasing clinical and socioeconomic burden. Synovial inflammation and articular inflammatory environment are the key factor for chondrocytes apoptosis and hypertrophy, ectopic bone formation and OA progression. To effectively treat OA, it is critical to develop a drug that skews inflammation toward a pro-chondrogenic microenvironment. In this narrative and critical review, we aim to see the potential use of immune cells modulation or cell therapy as therapeutic alternatives to OA patients. Macrophages are immune cells that are present in synovial lining, with different roles depending on their subtypes. These cells can polarize to pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes, being the latter associated with wound-healing by the production of ARG-1 and pro-chondrogenic cytokines, such as IL-10, IL-1RA, and TGF-b. Emerging evidence reveals that macrophage shift can be determined by several stimuli, apart from the conventional in vitro IL-4, IL-13, and IL-10. Evidences show the potential of physical exercise to induce type 2 response, favoring M2 polarization. Moreover, macrophages in contact with oxLDL have effect on the production of anabolic mediators as TGF-b. In the same direction, type II collagen, that plays a critical role in development and maturation process of chondrocytes, can also induce M2 macrophages, increasing TGF-b. The mTOR pathway activation in macrophages was shown to be able to polarize macrophages in vitro, though further studies are required. The possibility to use mesenchymal stem cells (MSCs) in cartilage restoration have a more concrete literature, besides, MSCs also have the capability to induce M2 macrophages. In the other direction, M1 polarized macrophages inhibit the proliferation and viability of MSCs and impair their ability to immunosuppress the environment, preventing cartilage repair. Therefore, even though MSCs therapeutic researches advances, other sources of M2 polarization are attractive issues, and further studies will contribute to the possibility to manipulate this polarization and to use it as a therapeutic approach in OA patients.

LncRNA LUADT1 regulates miR-34a/SIRT1 to participate in chondrocyte apoptosis

It is known that miR-34a can promote the apoptosis of chondrocytes, which directly contribute to osteoarthritis (OA). Through bioinformatics analysis, we found that long noncoding RNA LUADT1 may interact with miR-34a. We, therefore, further investigate the interactions between them in osteoarthritis. We found that LUADT1 was downregulated, while miR-34a was upregulated in OA synovial fluid. Correlation analysis revealed no significant correlation between them. Overexpression experiment also revealed no significant effects of LUADT1 and miR-34a on the expression of each other. However, the dual-luciferase assay showed that LUADT1 and miR-34a can directly interact with each other. Moreover, LUADT1 overexpression led to the upregulation of SIRT1, which is a downstream target of miR-34a. Cell apoptosis showed that LUADT1 and SIRT1 overexpression led to decreased, while miR-34a led to increased apoptotic rates of chondrocytes. Therefore, LUADT1 regulates miR-34a/SIRT1 to participate in chondrocyte apoptosis.

Enhanced T-type calcium channel 3.2 activity in sensory neurons contributes to neuropathic-like pain of monosodium iodoacetate-induced knee osteoarthritis

The monosodium iodoacetate knee osteoarthritis model has been widely used for the evaluation of osteoarthritis pain, but the pathogenesis of associated chronic pain is not fully understood. The T-type calcium channel 3.2 (CaV3.2) is abundantly expressed in the primary sensory neurons, in which it regulates neuronal excitability at both the somata and peripheral terminals and facilitates spontaneous neurotransmitter release at the spinal terminals. In this study, we investigated the involvement of primary sensory neuron-CaV3.2 activation in monosodium iodoacetate osteoarthritis pain. Knee joint osteoarthritis pain was induced by intra-articular injection of monosodium iodoacetate (2 mg) in rats, and sensory behavior was evaluated for 35 days. At that time, knee joint structural histology, primary sensory neuron injury, and inflammatory gliosis in lumbar dorsal root ganglia, and spinal dorsal horn were examined. Primary sensory neuron-T-type calcium channel current by patch-clamp recording and CaV3.2 expression by immunohistochemistry and immunoblots were determined. In a subset of animals, pain relief by CaV3.2 inhibition after delivery of CaV3.2 inhibitor TTA-P2 into sciatic nerve was investigated. Knee injection of monosodium iodoacetate resulted in osteoarthritis histopathology, weight-bearing asymmetry, sensory hypersensitivity of the ipsilateral hindpaw, and inflammatory gliosis in the ipsilateral dorsal root ganglia, sciatic nerve, and spinal dorsal horn. Neuronal injury marker ATF-3 was extensively upregulated in primary sensory neurons, suggesting that neuronal damage was beyond merely knee-innervating primary sensory neurons. T-type current in dissociated primary sensory neurons from lumbar dorsal root ganglia of monosodium iodoacetate rats was significantly increased, and CaV3.2 protein levels in the dorsal root ganglia and spinal dorsal horn ipsilateral to monosodium iodoacetate by immunoblots were significantly increased, compared to controls. Perineural application of TTA-P2 into the ipsilateral sciatic nerve alleviated mechanical hypersensitivity and weight-bearing asymmetry in monosodium iodoacetate osteoarthritis rats. Overall, our findings demonstrate an elevated CaV3.2 expression and enhanced function of primary sensory neuron-T channels in the monosodium iodoacetate osteoarthritis pain. Further study is needed to delineate the importance of dysfunctional primary sensory neuron-CaV3.2 in osteoarthritis pain.

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

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