Inflammation In Osteoarthritis Research Articles

Vitamin D Attenuates Pain and Cartilage Destruction in OA Animals via Enhancing Autophagic Flux and Attenuating Inflammatory Cell Death.

Osteoarthritis (OA) is the most common form of arthritis associated with ageing. Vitamin D has diverse biological effect on bone and cartilage, and observational studies have suggested it potential benefit in OA progression and inflammation process. However, the effect of vitamin D on OA is still contradictory. Here, we investigated the therapeutic potential of vitamin D in OA. Six-week-old male Wistar rats were injected with monosodium iodoacetate (MIA) to induce OA. Pain severity, cartilage destruction, and inflammation were measured in MIA-induced OA rats. Autophagy activity and mitochondrial function were also measured. Vitamin-D (1,25(OH)2D3) and celecoxib were used to treat MIA-induced OA rats and OA chondrocytes. Oral supplementation of vitamin D resulted in significant attenuations in OA pain, inflammation, and cartilage destruction. Interestingly, the expressions of MMP-13, IL-1β, and MCP-1 in synovial tissues were remarkably attenuated by vitamin D treatment, suggesting its potential to attenuate synovitis in OA. Vitamin D treatment in OA chondrocytes resulted in autophagy induction in human OA chondrocytes and increased expression of TFEB, but not LC3B, caspase-1 and -3, in inflamed synovium. Vitamin D and celecoxib showed a synergistic effect on antinociceptive and chondroprotective properties in vivo. Vitamin D showed the chondroprotective and antinociceptive property in OA rats. Autophagy induction by vitamin D treatment may be a promising treatment strategy in OA patients especially presenting vitamin D deficiency. Autophagy promoting strategy may attenuate OA progression through protecting cells from damage and inflammatory cell death.

A neutrophil cell membrane-biomimetic nanoplatform based on L-arginine nanoparticles for early osteoarthritis diagnosis and nitric oxide therapy.

Osteoarthritis (OA) is a common debilitating disease affecting articular joints for which no effective disease-modifying early diagnosis or medical therapy tools are currently available. The inefficient delivery of drugs into inflamed chondrocytes has restricted the development of anti-OA medication. Evidence has shown that inflammatory neutrophils possess the property of targeting inflammation via inflammatory tissue recruiting. Herein, we report neutrophil-cell-membrane-based biomimetic nanoparticles (NM-LANPs@Ru) as an OA theranostic nanoplatform; they act as a NO delivery system, coating neutrophil cell membrane onto the surface of self-assembled PEGylated L-arginine nanoparticles (LANPs) to act as a NO donor and loading a Ru complex to act as a ROS inducer. NM-LANPs@Ru demonstrated the specific targeting of inflamed OA with low toxicity, good NO release, and excellent fluorescence/photoacoustic (FL/PA) imaging properties. We showed that NM-LANPs@Ru exhibited enhanced cellular association in inflamed chondrocyte cells (C28/I2), much higher than NO release from ROS oxidized LA, and it improved the inhibition of the apoptosis of inflamed C28/I2 cells compared with control treatments. In vivo studies demonstrated that NM-LANPs@Ru effectively targeted inflamed OA, based on real-time dual-modal FL/PA imaging, eventually exhibiting its excellent anti-inflammatory activity. Our study may provide a new approach for the early diagnosis and treatment of osteoarthritis using a neutrophil-cell-membrane-based biomimetic nanoplatform for NO or drug delivery.

Hyaluronic Acid Modified Curcumin-Loaded Chitosan Nanoparticles Inhibit Chondrocyte Apoptosis to Attenuate Osteoarthritis via Upregulation of Activator Protein 1 and RUNX Family Transcription Factor 2.

Hyaluronic acid (HA) and curcumin (CUR) have been previously utilized for osteoarthritis (OA) treatment. CUR-loaded chitosan nanoparticles (CUR@CS NPs) and HA CUR@CS NPs were synthesized in our research to ascertain the synergistic impacts of HA and CUR-loaded NPs on OA treatment. CUR@CS NPs and HA CUR@CS NPs were synthesized with evaluation of their particle size, potential, PDI, encapsulation efficiency, drug loading and surface coating as well as HA binding rate. The in vitro CUR release curve and stability of HA-CUR@CS NPs were measured. Chondrocytes were isolated from the cartilages of OA patients, followed by cell uptake assay. The chondrocyte viability and apoptosis were determined. Subsequently, the knee OA model was established, followed by H&E, Safranin O/Fast green staining and micro-CT. HA CUR@CS NPs improved CUR stability and bioavailability. CUR@CS NPs and HA-CUR@CS NPs were successfully characterized and could further be internalized by chondrocytes. CUR@CS NPs promoted tBHP-induced chondrocyte viability and inhibited chondrocyte apoptosis. HA-CUR@CS NPs upregulated the AP-1 and RUNX2 transcription levels to activate Hedgehog pathway, which subsequently blocked the Notch pathway. Mechanically, HA-CUR@CS NPs sustained release and long-lasting effect and long-term retention in the joint cavity and downregulated the expression of several pro-inflammatory cytokines in vivo. HA-CUR@CS NPs exhibited superior effects in the preceding experiments than CUR@CS NPs. Altogether, HA-CUR@CS NPs may restrict inflammation and chondrocyte apoptosis in OA through upregulation of AP-1 and RUNX2.

Mast cells: A dark horse in osteoarthritis treatment

<abstract> <p>Mast cells are best known for their involvement in the pathogenesis of allergic reactions and inflammation. Due to the wide variety of activation methods and the various mediators that mast cells can synthesize and store, they can regulate all stages of the inflammatory process. There are a large amount of data describing the role of mast cells in the development of autoimmune rheumatoid arthritis, but their role in the development of inflammatory traumatic osteoarthritis remains poorly described. However, non-autoimmune cartilage damage is the main reason for joint replacement surgeries. As important regulators of the inflammatory process, mast cells could be an interesting target for the treatment of osteoarthritis. Herein, we summarize the knowledge about the role of mast cells in the pathogenesis of osteoarthritis and outline various approaches that, to varying degrees, seem promising for the correction of the disease.</p> </abstract>

Clinical significance of serum GPX2 levels in patients with osteoarthritis was suppressed and reduced inflammation of osteoarthritis through STAT3 function

The main alterations of osteoarthritis are degenerative lesions of articular cartilage and secondary hyperostosis. Despite the unclear pathogenic mechanism, experimental studies have confirmed that the incidence of osteoarthritis is closely associated with inflammation-related substances. In this study, we explored the significance of serum GPX2 levels in patients with osteoarthritis and the mechanism of GPX2 in the anti-inflammation effects in osteoarthritis. As a result, serum GPX2 level was down-regulated and there was a negative correlation between GPX2 levels and IL-1β levels in patients with osteoarthritis. Over-expression of GPX2 decreased the inflammatory levels and down-regulation of GPX2 increased inflammatory levels in vitro. In contrast, GPX2 combined and regulated STAT3 protein expression. Over-expression of GPX2 promoted ubiquitination-STAT3 protein expression to decrease p-STAT3 protein expression in vitro. The inhibition of STAT3 attenuated the anti-inflammation effects of GPX2 in osteoarthritis. Thus, we proposed that GPX2 was down-regulated in patients with osteoarthritis and GPX2 played vital roles in osteoarthritis for clinical diagnosis or therapy.

Defective Signal Transduction in Osteoarthritic Chondrocytes and Synovial Fibroblasts Should Become a Target for Drug Intervention

Although it has been known for some time that pro-inflammatory cytokines are an essential driver of synovial joint inflammation in osteoarthritis (OA), drugs [e.g. Anakinra, Tocilizumab, Tofacitinib, Adalibumab] that target the signal transduction pathways activated by these cytokines

Cinnamic Aldehyde, the main monomer component of Cinnamon, exhibits anti-inflammatory property in OA synovial fibroblasts via TLR4/MyD88 pathway.

Cinnamon is a wildly used traditional Chinese herbal medicine for osteoarthritis (OA) treatment, but the underlying mechanism remains ambiguous. The purpose of this study is to explore the mechanism of cinnamic aldehyde (CA), a bioactive substance extracted from Cinnamon, on synovial inflammation in OA. A total of 144 CA‐OA co‐targeted genes were identified by detect databases (PubChem, HIT, TCMSP, TTD, DrugBank and GeneCards). The results of GO enrichment analysis indicated that these co‐targeted genes have participated in many biological processes including ‘inflammatory response’, ‘cellular response to lipopolysaccharide’, ‘response to drug’, ‘immune response’, ‘lipopolysaccharide‐mediated signalling pathway’, etc. KEGG pathway analysis showed these co‐targeted genes were mainly enriched in ‘Toll‐like receptor signalling pathway’, ‘TNF signalling pathway’, ‘NF‐kappa B signalling pathway’, etc. Molecular docking demonstrated that CA could successfully bind to TLR2 and TLR4. The results of in vitro experiments showed no potential toxicity of 10, 20 and 50 μM/L CA on human OA FLS, and CA can significantly inhibit the inflammation in LPS‐induced human FLS. Further experimental mechanism evidence confirmed CA can inhibited the inflammation in LPS‐induced human OA FLS via blocking the TLR4/MyD88 signalling pathway. Our results demonstrated that CA exhibited strong anti‐inflammation effect in OA FLS through blocking the activation of TLR4/MyD88 signalling pathway, suggesting its potential as a hopeful candidate for the development of novel agents for the treatment of OA.

Establishment of an Ex Vivo Inflammatory Osteoarthritis Model With Human Osteochondral Explants.

Osteoarthritis (OA) is the most common degenerative joint disease without clear pathophysiological mechanism and effective drugs for treatment. Although various animal models exist, the translation of the outcome into clinics remains difficult due to species differences. In this study, an ex vivo inflammatory OA model was induced using different concentrations of interleukin one beta (IL-1β) and tumor necrosis factor α (TNF-α) on explants from the human femoral head. In the inflammatory OA groups, the gene expression levels of cartilage catabolism (matrix metalloproteinase 1 (MMP1), matrix metalloproteinase 3 (MMP3)), and inflammation (interleukin 6 (IL-6), interleukin 8 (IL-8)) markers were significantly upregulated, while the anabolic genes (collagen 2 (COL2), aggrecan (ACAN), and proteoglycan 4 (PRG4)) were downregulated compared to the control group. The release of cytokines (IL-6, IL-8) and nitric oxide (NO) in the conditioned medium was also upregulated in inflammatory OA groups. The Safranin O/Fast Green staining showed loss of proteoglycan in the superficial zone cartilage after cytokine treatment. The results indicated that an ex vivo inflammation and degeneration model was successfully established using osteochondral explants from the human femoral head. This model can be used to elucidate the in-depth mechanism of inflammatory OA and to screen new drugs for OA treatment.

Effects of Obesity Reduction on Physical Function, Inflammation and Osteoarthritis in Older Adults

Age-related increases in chronic inflammation lead to reduced physical function via damage to muscle and joints and contribute to osteoarthritis (OA) risk. Obesity in older adults with OA further exacerbates inflammatory damage. Whether obesity reduction can lessen inflammation and improve OA is unknown; however, novel biomarkers may provide an answer. We completed a 6-mo. weight loss intervention (-500 kcal/day), studying blood biomarkers of inflammation and cartilage damage along with physical function in obese older adults with (OA+; n=39) and without an OA diagnosis (OA-; n=20). Participants were aged > 60 yrs (mean = 70.2±6.0) and obese (BMI =34.6±4.7 kg/m2). At endpoint, weight loss was -6.3±4.0% and -5.8±4.1% in OA+ and OA-, respectively, with no group difference. Change scores for function for OA+ and OA- were: Short Physical Performance Battery score (+1.7±1.3 and +2.1±1.5), 8 ft up and go (-0.7±1.0 and -0.9±1.12 sec) and 6 min walk (+31.4±105.1 and +39.5±57.4 meters). All improved from baseline (p<0.05), with no group difference. Concerning blood biomarkers, there was a decrease (p<0.05) in cartilage oligomeric matrix protein (COMP: OA biomarker), indicating a potential benefit for OA. Change in COMP also differed between groups; OA- had a greater (p<0.05) reduction than OA+. Pooled results showed improved adiponectin (p<0.05), with no group difference. There were no changes for CRP, CTX-1, IL-6 and TNF-α. Our novel findings link early intervention with better reduction of OA risk and inflammation in obese older adults and also show important benefits for improved physical function regardless of OA status.

Trelagliptin ameliorates IL-1β-impaired chondrocyte function via the AMPK/SOX-9 pathway

Chondrocyte dysregulation plays a critical role in the development of osteoarthritis (OA). The pro-inflammatory cytokine interleukin-1β (IL-1β) activates chondrocytes and degrades the structural extracellular matrix (ECM). These events are the important mechanism of OA. Trelagliptin, a selective inhibitor of dipeptidyl Peptidase 4 (DPP-4) used for the treatment of type 2 diabetes mellitus (T2DM), has displayed a wide range of anti-inflammatory capacities. The effects of Trelagliptin in OA and chondrocytes have not been tested before. Here, we show that Trelagliptin mitigates IL-1β-induced production of inflammatory cytokines such as interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor-alpha (TNF-α) in human chondrocytes. Trelagliptin ameliorates IL-1β-induced oxidative stress by reducing the generation of reactive oxygen species (ROS). Particularly, the presence of Trelagliptin prevents IL-1β-induced reduction of Acan genes and the protein Aggrecan. Moreover, we show that Trelagliptin restores IL-1β-induced reduction of SOX-9 and that the knockdown of SOX-9 abolishes the protective effects of Trelagliptin. Mechanistically, we demonstrate that AMPK is required for the amelioration of Trelagliptin on SOX-9- reduction by IL-1β. Collectively, our study demonstrates that the DPP-4 inhibitor Trelagliptin has a protective effect on chondrocyte function. Trelagliptin may have the potential role to antagonize chondrocyte-derived inflammation in OA.

Thermoresponsive polymeric dexamethasone prodrug for arthritis pain

Intra-articular (IA) glucocorticoids (GC) are commonly used for clinical management of both osteoarthritis and rheumatoid arthritis, but their efficacy is limited by the relatively short duration of action and associated side effects. To provide sustained efficacy and to improve the safety of GCs, we previously developed a N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-based dexamethasone (Dex) prodrug. Serendipitously, we discovered that, by increasing the Dex content of the prodrug to unusually high levels, the aqueous solution of the polymeric prodrug becomes thermoresponsive, transitioning from a free-flowing liquid at 4 °C to a hydrogel at 30 °C or greater. Upon IA injection, the prodrug solution forms a hydrogel (ProGel-Dex) that is retained in the joint for more than 1 month, where it undergoes gradual dissolution, releasing the water-soluble polymeric prodrug. The released prodrug is swiftly internalized and intracellularly processed by phagocytic synoviocytes to release free Dex, resulting in sustained amelioration of joint inflammation and pain in rodent models of inflammatory arthritis and osteoarthritis. The low molecular weight (6.8 kDa) of the ProGel-Dex ensures rapid renal clearance once it escapes the joint, limiting systemic GC exposure and risk of potential off-target side effects. The present study illustrates the translational potential of ProGel-Dex as a potent opioid-sparing, locally delivered adjuvant analgesic for sustained clinical management of arthritis pain and inflammation. Importantly, the observed thermoresponsive properties of the prodrug establishes ProGel as a platform technology for the local delivery of a broad spectrum of therapeutic agents to treat a diverse array of pathological conditions.

Long non-coding RNA LINC00265 promotes proliferation, apoptosis, and inflammation of chondrocytes in osteoarthritis by sponging miR-101-3p

Long non-coding RNAs (lncRNAs) play a part in a wide variety of diseases, including osteoarthritis (OA). This study was designed to investigate the biological role of lncRNA LINC00265 in OA and its underlying mechanisms. We examined the levels of LINC00265 and miR-101-3p using RT-qPCR, inflammatory factors using ELISA, and caspase-3, c-caspase-3, Bcl-2, Bax, and MMP-13 levels using Western blot in normal and OA chondrocytes, analysed the relationship between LINC00265 and miR-101-3p using bioinformatics analysis and luciferase reporter assays, performed loss- and gain-of-function analyses. The results showed that (1) LINC00265 expression was increased in OA chondrocytes, (2) si-LINC00265 inhibited OA chondrocyte apoptosis and inflammation, and (3) LINC00265 overexpression promoted normal and OA chondrocyte apoptosis and inflammation. Furthermore, we predicted and confirmed that miR-101-3p was a target of LINC00265. LINC00265 negatively regulated miR-101-3p in OA chondrocytes and LINC00265 promoted OA and normal chondrocyte apoptosis via miR-101-3p. Overall, lncRNA LINC00265 regulates chondrocyte apoptosis by acting as a sponge of miR-101-3p in OA.

Translation of the 2018 EULAR recommendations for physical activity in people with inflammatory arthritis and osteoarthritis and linguistic validation in German-speaking countries with healthcare professionals

Regular physical activity is beneficial for people with rheumatic diseases and one of the cornerstones in its management. Based on the international recommendations of the World Health Organization for the general population, the "2018 EULAR recommendations for physical activity in people with inflammatory arthritis and osteoarthritis" provide evidence-based recommendations on the prescription, performance, and implementation of physical activity exercises in this population for the first time. Translation of the 2018 EULAR recommendations into German and linguistic validation in Germany, Austria and Switzerland. Aprofessional translation of the EULAR recommendations into the German language was performed and revised by German-speaking experts from all three countries. The translation was validated by healthcare professionals consisting of rheumatologists, occupational therapists, physiotherapists, nurses, and medical assistants in afield test. In each of the three countries, eight structured interviews were conducted on comprehensibility, wording, completeness, and feasibility. The experts then discussed changes until consensus was reached and indicated the level of agreement with the final translation. The translation of the EULAR recommendations was substantially revised. Based on the results of the cognitive test, formulations were adapted in order to increase comprehensibility. The level of agreement between10 (SD0.0) and8.9 (SD1.5) was very high. The final German version of the EULAR recommendations is comprehensible and accepted across all three German-speaking countries. It can help to improve the structure and clarity of the handling of physical activity and promote physical activity for healthcare providers and patients.

Lay version of the 2018 EULAR recommendations for physical activity in people with inflammatory arthritis and osteoarthritis : Translation into German and linguistic validation in German-speaking countries with people affected

Physical activity and exercise are beneficial for people with rheumatic diseases; however, recommendations for the management of rheumatoid arthritis (RA), spondyloarthritis (SpA) and hip- and knee osteoarthritis (HOA/KOA) are usually unspecific with respect to mode and dose of exercise. This is why the 2018 EULAR recommendations for physical activity in people with inflammatory arthritis and osteoarthritis were formulated. The recommendations consist of 4 overarching principles and 10recommendations. These were also published as alay version in the English language. Translation of the lay version into German and its linguistic validation in Austria, Germany and Switzerland. Aprofessional translation was reviewed by the authors, including people with, RA, SpA, HOA/KOA from the three German-speaking countries, which provided aprefinal lay version. Subsequently, eight interviews with people with RA, SpA, HOA/KOA were conducted in each country to evaluate understandability, wording, completeness and feasibility of the prefinal lay version. Finally, the authors, i.e. those with RA, SpA, and osteoarthritis, anonymously rated their agreement to the final lay version on a0-10 scale. The professional translation was substantially revised by the authors and based on the interviews. Formulations were adapted to increase readability and understandability and specify statements. Comments that would have changed content or structure were not considered. Average agreement with the particular recommendations was between10 (SD0) and7.6 (SD1.67). For people with RA/SpA/HOA/KOA the EULAR physical activity recommendations should be available in their mother language. The final German lay version is valid and accepted across all three German-speaking countries. Thus, the physical activity recommendations can be provided to people with rheumatic diseases in an understandable and feasible way.

Notoginsenoside R1 alleviates the inflammation of osteoarthritis by activating the Nrf2/HO-1 signalling pathway in vitro and in vivo

• Inflammation plays a vital role in the progression of osteoarthritis. • Notoginsenoside R1 reduces IL-1β-induced inflammation and ameliorate osteoarthritis progression. • Nrf/HO-1 signaling pathway is activated in the treatment of Notoginsenoside R1. Osteoarthritis (OA) is a major articular degenerative disease characterized by local chronic inflammation and cartilage degeneration. Notoginsenoside R1 (NR1) is one of the bioactive compounds of Panax notoginseng with multiple pharmacological activities. In this study, we investigated the protective effect of NR1 on OA. Rat primary chondrocytes were treated with 10 ng/ml interleukin (IL)-1β to induce an OA-like phenotype in vitro followed by treatment with NR1. The results showed that the IL-1β-induced increased expression of tumor necrosis factor (TNF)-α, IL-6, and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was inhibited by NR1. In addition, NR1 downregulated the expression of matrix degrading enzymes and alleviated the degradation of extracellular matrix (ECM). Moreover, activation of the nuclear factor-erythroid 2-related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway was observed after NR1 treatment, which further inhibited the IL-1β-induced activation of the nuclear factor-κB (NF-κB) pathway. Knee OA was induced in rats in vivo by anterior cruciate ligament transaction (ACLT), and NR1 was then administered to rats by gavage. The results revealed that NR1 reduced cartilage degeneration and OA scores of the knee. In conclusion, the present study indicated that NR1 alleviates the inflammation of osteoarthritis by activating the Nrf2/HO-1 signaling pathway, indicating that NR1 may be a potential drug for OA therapy.

C1q/TNF-related protein-9 suppresses inflammation in synovial cells from patients with osteoarthritis

Objective Synovial inflammation contributes to cartilage degeneration and osteoarthritis (OA) development. Targeting the inflammation process may provide a promising strategy for OA treatment. It has been demonstrated that C1q/tumour necrosis factor-related protein-9 (CTRP9) has immunosuppression capabilities. Thus, we conducted this study to investigate the role of CTRP9 in OA and its therapeutic potential. Method The expression level of CTRP9 was quantified in peripheral blood mononuclear cells (PBMCs), serum, and synovial cells (SCs) isolated from OA patients by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. The relationship between the expression level of CTRP9 and the disease activity of OA was determined. The inflammation-suppressing effects of CTRP9 were assessed in vitro. Results The expression level of CTRP9 was increased in the PBMCs and serum of OA compared to healthy controls. The serum level of CTRP9 was found to be positively correlated with erythrocyte sedimentation rate, C-reactive protein, and visual analogue scale score. In addition, CTRP9 protein suppressed the expression of pro-inflammatory cytokines, including tumour necrosis factor-α, interleukin-6, and interleukin-1β, in PBMCs and SCs in vitro. CTRP9 was increased in OA patients and positively correlated with the disease activity. The recombinant CTRP9 had inflammation-suppressing activities in vitro. Conclusion CTRP9 may have therapeutic potential for treating OA. Osteoarthritis (OA) is characterized as cartilage destruction resulting from synovial inflammation (1–6). According to the clinical symptoms and levels of inflammation, OA has been divided into primary generalized osteoarthritis (PGOA) and erosive inflammatory osteoarthritis (EIOA) (7). The only available treatment for OA is joint replacement. Thus, it is necessary to develop novel and effective therapeutic strategies to treat OA. Because synovial inflammation contributes to OA development, targeting the inflammation process may provide a promising strategy for OA treatment. Previous investigations showed that pro-inflammatory factors promoted OA development (8–10), while anti-inflammatory factors suppressed it (11–14). Thus, we conducted the present study to investigate the role of C1q/tumour necrosis factor-related protein-9 (CTRP9), an anti-inflammatory factor (15), in OA, and its therapeutic potential.

Extracellular vesicles as novel approaches for the treatment of osteoarthritis: a narrative review on potential mechanisms.

Osteoarthritis (OA) is a progressive degeneration of articular cartilage with involvement of synovial membrane, and subchondral bone. Current treatment approaches have focused on controlling the OA symptoms, pain, and inflammation. Recently, cell-based therapies, including the application of stem cells such as mesenchymal stem cells (MSCs), have been introduced for restoration of the articular cartilage. Despite promising outcomes, there are some limitations in the application of MSCs for OA treatment. It has been demonstrated that the regenerative potential of stem cells is related to the production of paracrine factors. Extracellular vehicles (EVs), the main component of cell secretome, are membrane-bounded structures that deliver biologically active agents. The delivery of molecules (e.g., nucleic acids, proteins, and lipids) leads to cell-to-cell communication and the alteration of cell functions. In this review, general characteristics of EVs, as well as their potential mechanisms in the prevention and treatment of OA were considered. Based on in vitro and in vivo studies, EVs have shown to contribute to cartilage regeneration via suppression of degenerative factors and regulation of chondrocyte function in the synthesis of extracellular matrix components. Also, they inhibit the progression of OA or protect the cartilage from degradation via their impact on inflammatory cytokines. The different signaling pathways of EVs against the pathologic features of OA were summarized in this review. According to the results obtained from several investigations, more investigations should be design to prove the safety and effectiveness of EVs in the treatment and prevention of OA progression.

Modeling In Vitro Osteoarthritis Phenotypes in a Vascularized Bone Model Based on a Bone-Marrow Derived Mesenchymal Cell Line and Endothelial Cells.

The subchondral bone and its associated vasculature play an important role in the onset of osteoarthritis (OA). Integration of different aspects of the OA environment into multi-cellular and complex human, in vitro models is therefore needed to properly represent the pathology. In this study, we exploited a mesenchymal stromal cell line/endothelial cell co-culture to produce an in vitro human model of vascularized osteogenic tissue. A cocktail of inflammatory cytokines, or conditioned medium from mechanically-induced OA engineered microcartilage, was administered to this vascularized bone model to mimic the inflamed OA environment, hypothesizing that these treatments could induce the onset of specific pathological traits. Exposure to the inflammatory factors led to increased network formation by endothelial cells, reminiscent of the abnormal angiogenesis found in OA subchondral bone, demineralization of the constructs, and increased collagen production, signs of OA related bone sclerosis. Furthermore, inflammation led to augmented expression of osteogenic (alkaline phosphatase (ALP) and osteocalcin (OCN)) and angiogenic (vascular endothelial growth factor (VEGF)) genes. The treatment, with a conditioned medium from the mechanically-induced OA engineered microcartilage, also caused increased demineralization and expression of ALP, OCN, ADAMTS5, and VEGF; however, changes in network formation by endothelial cells were not observed in this second case, suggesting a possible different mechanism of action in inducing OA-like phenotypes. We propose that this vascularized bone model could represent a first step for the in vitro study of bone changes under OA mimicking conditions and possibly serve as a tool in testing anti-OA drugs.

A matrix metalloproteinase-generated neoepitope of CRP can identify knee and multi-joint inflammation in osteoarthritis

ObjectiveTo compare C-reactive protein (CRP) and matrix metalloproteinase-generated neoepitope of CRP (CRPM) as biomarkers of inflammation and radiographic severity in patients with knee osteoarthritis.MethodsParticipants with symptomatic osteoarthritis (n=25) of at least one knee underwent knee radiographic imaging and radionuclide etarfolatide imaging to quantify inflammation of the knees and other appendicular joints. For purposes of statistical analysis, semi-quantitative etarfolatide and radiographic imaging scores were summed across the knees; etarfolatide scores were also summed across all joints to provide a multi-joint synovitis measure. Multiple inflammation and collagen-related biomarkers were measured by ELISA including CRP, CRPM, MMP-generated neoepitopes of type I collagen and type III collagen in serum (n=25), and CD163 in serum (n=25) and synovial fluid (n=18).ResultsBMI was associated with CRP (p=0.001), but not CRPM (p=0.753). Adjusting for BMI, CRP was associated with radiographic knee osteophyte score (p=0.002), while CRPM was associated with synovitis of the knee (p=0.017), synovitis of multiple joints (p=0.008), and macrophage marker CD163 in serum (p=0.009) and synovial fluid (p=0.03). CRP correlated with MMP-generated neoepitope of type I collagen in serum (p=0.045), and CRPM correlated with MMP-generated neoepitope of type III collagen in serum (p<0.0001). No biomarkers correlated with age, knee pain, or WOMAC pain.ConclusionsTo our knowledge, this is the first time that CRPM has been shown to be associated with knee and multi-joint inflammation based on objective imaging (etarfolatide) and biomarker (CD163) measures. These results demonstrate the capability of biomarker measurements to reflect complex biological processes and for neoepitope markers to more distinctly reflect acute processes than their precursor proteins. CRPM is a promising biomarker of local and systemic inflammation in knee OA that is associated with cartilage degradation and is independent of BMI. CRPM is a potential molecular biomarker alternative to etarfolatide imaging for quantitative assessment of joint inflammation.

Regulation of Tumor Necrosis Factor-α by Peptide Lv in Bone Marrow Macrophages and Synovium.

Background: Bone marrow-derived monocytes/macrophages are recruited into synovial tissue, where they contribute to synovial inflammation in osteoarthritis through inflammatory cytokine production. Recent studies have suggested that V-Set and transmembrane domain-containing 4 (VSTM4) and its fragment, peptide Lv, exhibit immunosuppressive activity on T cells and vascular endothelial growth factor (VEGF)-like activity, respectively. Given that evidence suggests that VEGF may play a role in macrophage function, we investigated peptide Lv-mediated regulation of inflammatory cytokines in bone marrow macrophages (BMMs) and synovial inflammation.Method: To investigate the effects of peptide Lv, BMMs were stimulated with vehicle, LPS, or LPS + peptide Lv, and Tnfa, Il1b, Il6, and Ifng expression were evaluated using quantitative PCR (qPCR). TNF-α and IFN-γ production was measured using ELISA. To examine the effect of peptide Lv deficiency on macrophages and synovitis, peptide Lv-deficient mice were generated using genome editing. LPS-induced Tnfa and Ifng expression and TNF-α and IFN-γ production were evaluated in BMM isolated from wild-type and peptide Lv-deficient mice. Additionally, Tnfa and Ifng expression levels were compared between wild-type and peptide Lv-deficient mice before and after knee injury.Results: Peptide Lv suppressed the LPS-mediated elevation in TNF-α and IFN-γ. LPS stimulation significantly increased TNF-α and IFN-γ production in BMM derived from peptide Lv-deficient mice compared to wild-type mice. Synovial TNF-α expression in the injured knee was elevated in peptide Lv-deficient compared to wild-type mice.Conclusion: Peptide Lv suppressed TNF-α in macrophages and plays a role in synovial inflammation. Thus, peptide Lv may be a useful therapeutic target for synovitis.