Immunopathogenesis of osteoarthritis

Stable sulforaphane protects against gait anomalies and modifies bone microarchitecture in the spontaneous STR/Ort model of osteoarthritis

Osteoarthritis (OA), affecting joints and bone, causes physical gait disability with huge socio-economic burden; treatment remains palliative. Roles for antioxidants in protecting against such chronic disorders have been examined previously. Sulforaphane is a naturally occurring antioxidant. Herein, we explore whether SFX-01®, a stable synthetic form of sulforaphane, modifies gait, bone architecture and slows/reverses articular cartilage destruction in a spontaneous OA model in STR/Ort mice. Sixteen mice (n=8/group) were orally treated for 3months with either 100mg/kg SFX-01® or vehicle. Gait was recorded, tibiae were microCT scanned and analysed. OA lesion severity was graded histologically. The effect of SFX-01® on bone turnover markers in vivo was complemented by in vitro bone formation and resorption assays. Analysis revealed development of OA-related gait asymmetry in vehicle-treated STR/Ort mice, which did not emerge in SFX-01®-treated mice. We found significant improvements in trabecular and cortical bone. Despite these marked improvements, we found that histologically-graded OA severity in articular cartilage was unmodified in treated mice. These changes are also reflected in anabolic and anti-catabolic actions of SFX-01® treatment as reflected by alteration in serum markers as well as changes in primary osteoblast and osteoclast-like cells in vitro. We report that SFX-01® improves bone microarchitecture in vivo, produces corresponding changes in bone cell behaviour in vitro and leads to greater symmetry in gait, without marked effects on cartilage lesion severity in STR/Ort osteoarthritic mice. Our findings support both osteotrophic roles and novel beneficial gait effects for SFX-01® in this model of spontaneous OA.

Pain relieving and protective effects of Astragalus hydroalcoholic extract in rat arthritis models

OBJECTIVES

The evaluation of the pharmacological profile of the dried 50% hydroalcoholic extract (50%HA) of Astragali radix in two different animal models of articular damage resembling osteoarthritis and rheumatoid arthritis.

METHODS

Sodium monoiodoacetate (MIA) or complete Freund's adjuvant (CFA) was intra-articular injected (day 0) in the rat tibiotarsal joint to induce damages mimicking osteoarthritis or rheumatoid arthritis. Pain measurements (responses to non-noxious and noxious stimuli, spontaneous pain, articular pain) were assessed on days 7 and 14. On day 14, the tibiotarsal joints were explanted in order to measure the diameter and to assess histological evaluations. Furthermore, the plasmatic concentrations of inflammatory and anti-inflammatory cytokines were measured.

KEY FINDINGS

A single administration of 50%HA (300 mg/kg per os) significantly reduced both MIA-induced pain and CFA-induced pain (78% and 96% pain relief, respectively). The repeated administration prevented the development of hypersensitivity on day 14. The haematoxylin/eosin staining revealed that 50% HA attenuated joint alterations in MIA-injected rats, and furthermore, the joint inflammatory infiltrate was reduced in both models (by about 50%). In CFA-treated rats, 50%HA lowered the plasmatic levels of the pro-inflammatory cytokines interleukin-1β and tumour necrosis factor-α as well as the joint diameter.

CONCLUSIONS

The 50% hydroalcoholic extract of Astragali radix is a valuable candidate for the adjuvant treatment of articular diseases.

Immunohistochemical characterization of early and advanced knee osteoarthritis by NF-κB and iNOS expression

This study was performed to determine the differences in grade of synovitis and expression of NF-κB and iNOS in knee synovial membrane between early and advanced stage of osteoarthritis (OA). Thirty synovial membrane intra-operative biopsies of patients (ten controls, ten with early and ten with advanced OA according to Kellgren-Lawrence radiological score) were immunohistochemically (NF-κB and iNOS) and hystologically (Krenn synovitis score) analyzed and correlated to WOMAC clinical score and pain duration. Krenn synovitis score of patients with radiologically early OA was significantly higher than in patients with advanced OA (p < 0.001). NF-κB expression in both synovial intima (p < 0.001) and subintima (p < 0.001) was also higher in early OA. iNOS expression in subintima was significantly higher in early than in advanced OA (p < 0.001), while in intima iNOS showed no statistical difference between groups (p = 0.07). The lymphocytic nodules, located in synovial subintima, were significantly higher in advanced OA when compared to early OA (p = 0.006) and the control group (p < 0.001). These results suggest that in early OA, there is a localized inflammation of the synovial membrane with high expression of NF-κB and iNOS. In advanced OA, number of expressed factors is reduced, with the exception of intima cells that highly express iNOS, reflecting the ongoing localized inflammatory process of lower degree. In advanced OA, the density of the resident cells is reduced and lymphocytic nodules appear, confirming the important role of adaptive immunity in later OA stage. Clinical significance of this study is better understanding possibilities of preventive measures for synovitis and OA advancement. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1990-1997, 2017.

Skin penetration and tissue permeation after topical administration of diclofenac

OBJECTIVE

Topical delivery of drugs is an alternative to oral administration, often with similar efficacy but potentially a more favorable tolerability profile. However, topical formulations need to be able to penetrate the skin and permeate to the target areas in quantities sufficient to exert a therapeutic effect. Many factors can affect this process, including the physicochemical properties of the drug, the formulation used, and the site and mode of application. It is believed that measurement of drug concentrations at the sites of action may be an indicator of their likely efficacy. This review addresses these issues, with reference to topically administered diclofenac in osteoarthritis.

METHODS

Articles relevant to this review were identified after a systematic search of Medline and Embase, using the key words "diclofenac", "topical administration" and "osteoarthritis" in the search strategy.

RESULTS

The sparse data available indicate that topical diclofenac can penetrate and permeate to deeper tissues, with a lower plasma to tissue ratio than oral diclofenac. The tissue diclofenac levels after topical delivery are sustained over time (at least several hours). However, there is not enough data to establish how diclofenac levels in the joint compare with IC₅₀ levels (50% of the maximum inhibition of prostaglandin synthesis) established following oral administration.

CONCLUSIONS

After topical application, diclofenac can penetrate the skin and permeate to deeper tissues, where it reaches a concentration that appears to be sufficient to exert a therapeutic effect. More robust methods are required for in vivo characterization to better estimate the clinical efficacy of topically applied drugs.

Honokiol improved chondrogenesis and suppressed inflammation in human umbilical cord derived mesenchymal stem cells via blocking nuclear factor-κB pathway

BACKGROUND

Cartilage degradation is the significant pathological process in osteoarthritis (OA). Inflammatory cytokines, such as interleukin-1β (IL-1β), activate various downstream mediators contributing to OA pathology. Recently, stem cell-based cartilage repair emerges as a potential therapeutic strategy that being widely studied, whereas, the outcome is still far from clinical application. In this study, we focused on an anti-inflammatory agent, honokiol, which is isolated from an herb, investigated the potential effects on human umbilical cord derived mesenchymal stem cells (hUC-MSCs) in IL-1β stimulation.

METHODS

Second passage hUC-MSCs were cultured for multi-differentiation. Flow cytometry, qRT-PCR, von Kossa stain, alcian blue stain and oil red O stain were used for characterization and multi-differentiation determination. Honokiol (5, 10, 25, 50 μM) and IL-1β (10 ng/ml) were applied in hUC-MSCs during chondrogenesis. Analysis was performed by MTT, cell apoptosis evaluation, ELISA assay, qRT-PCR and western blot.

RESULTS

hUC-MSC was positive for CD73, CD90 and CD105, but lack of CD34 and CD45. Remarkable osteogenesis, chondrogenesis and adipogenesis were detected in hUC-MSCs. IL-1β enhanced cell apoptosis and necrosis and activated the expression of caspase-3, cyclooxygenase-2 (COX-2), interleukin-6 (IL-6) and matrix metalloproteinase (MMP)-1, -9, 13 in hUC-MSCs. Moreover, the expression of SRY-related high-mobility group box 9 (SOX-9), aggrecan and col2α1 was suppressed. Honokiol relieved these negative impacts induced by IL-1β and suppressed Nuclear factor-κB (NF-κB) pathway by downregulating expression of p-IKKα/β, p-IκBα and p-p65 in dose-dependent and time-dependent manner.

CONCLUSIONS

Honokiol improved cell survival and chondrogenesis of hUC-MSCs and inhibited IL-1β-induced inflammatory response, which suggested that combination of anti-inflammation and stem cell can be a novel strategy for better cartilage repair.

Medication Treatment Efficacy and Chronic Orofacial Pain

Chronic pain in the orofacial region has always been a vexing problem for dentists to diagnose and treat effectively. For trigeminal neuropathic pain, there are 3 medications (gabapentinoids, tricyclic antidepressants, and serotonin-norepinephrine reuptake inhibitors) to use plus topical anesthetics that have therapeutic efficacy. For chronic daily headaches (often migraine in origin), 3 prophylactic medications have reasonable therapeutic efficacy (β-blockers, tricyclic antidepressants, and antiepileptic drugs). The 3 Food and Drug Administration-approved drugs for fibromyalgia (pregabalin, duloxetine, and milnacipran) are not robust, with poor efficacy. For osteroarthritis, nonsteroidal anti-inflammatory drugs have therapeutic efficacy and when gastritis contraindicates them, corticosteriod injections are helpful.

Identification of key mRNAs and microRNAs in the pathogenesis and progression of osteoarthritis using microarray analysis

Osteoarthritis (OA) is a common type of disease affecting the joints that results from the breakdown of joint cartilage and the underlying bone; currently, its pathogenesis is still unclear. The aim of the present study was to identify key mRNAs and miRNAs involved in the pathogenesis and progression of OA using microarray analysis. The gene expression profile of GSE27492 was downloaded from the Gene Expressed Omnibus database, and included 49 arthritic mouse ankle samples collected at 6 time points (0, 1, 3, 7, 12 and 18 days) following the induction of arthritis via serum transfer. Differentially expressed genes (DEGs) were identified in ankle samples taken on days 1, 3, 7, 12 and 18 following serum transfer compared with day 0 samples, and overlapping DEGs in day 3, 7, 12 and 18 samples were identified. The Database for Annotation, Visualization and Integrated Discovery online tool was used to perform functional and pathway enrichment analyses of the overlapping DEGs. The miRWalk database was used to identify potential micro (mi) RNAs regulating the selected overlapping DEGs, and regulatory miRNA‑target mRNA pairs were obtained. The Cytoscape platform was used to establish and visualize the miRNA‑mRNA regulatory network. The present results revealed that 35, 103, 62 and 75 DEGs were identified in day 3, 7, 12 and 18 samples, respectively. A total of 17 overlapping DEGs were identified among the 4 sample sets, and revealed to be enriched in 14 gene ontology terms and 3 Kyoto Encyclopedia of Genes and Genomes pathways. miRWalk analysis identified 242 potential miRNA‑mRNA regulatory pairs and 211 nodes were revealed to be involved in the miRNA‑mRNA regulatory network. The present study identified potential genes, including C‑type lectin domain family 4 member D, chemokine (C‑X‑C motif) ligand 1 and C‑C motif chemokine ligand, and pathways, including chemokine signaling pathways, cytokine‑cytokine receptor interactions and nucleotide‑binding oligomerization domain‑like receptor signaling pathways, which may be involved in the pathogenesis and progression of OA. These findings may help elucidate the molecular mechanisms underlying OA pathophysiology, and may be useful for the development of novel therapeutic targets for the treatment of patients with OA.

β-NGF and β-NGF receptor upregulation in blood and synovial fluid in osteoarthritis

Osteoarthritis (OA) of the knee is the most common form of non-traumatic joint disease. Previous studies have shown the involvement of β-NGF and its receptors TrKA and p75NTR in OA-related pain, but their role in its pathogenesis is still unclear. The aim of our study was to investigate the amount of β-NGF and the expression levels of its receptors on cells isolated from synovial fluid and blood from OA patients who had undergone total knee arthroplasty, in order to check any possible correlation with the disease staging. Our results show a progressive stage-related increase of β-NGF and its receptors both in serum and synovial fluid. Furthermore, with respect to control subjects, OA patients show an increased amount of inflammatory monocytes along with an increased expression of β-NGF, TrKA and p75NTR. In conclusion, our study suggests a stage-related modulation of β-NGF and its receptors in the inflammatory process of OA.

An Ilomastat-CD Eye Drop Formulation to Treat Ocular Scarring

Purpose

The purpose of this study was to develop a topical matrix metalloproteinase inhibitor preparation for antiscarring therapy.

Methods

The broad spectrum matrix metalloproteinase inhibitor ilomastat was formulated using 2-hydroxypropyl-β-cyclodextrin in aqueous solution. In vitro activity of ilomastat-cyclodextrin (ilomastat-CD) was examined using fibroblasts seeded in collagen. Permeation of ilomastat-CD eye drop through pig eye conjunctiva was confirmed using Franz diffusion cells. Ilomastat-CD eye drop was applied to rabbit eyes in vivo, and the distribution of ilomastat in ocular tissues and fluids was determined by liquid chromatography-mass spectroscopy.

Results

The aqueous solubility of ilomastat-CD was ∼1000 μg/mL in water and 1400 μg/mL in PBS (pH 7.4), which is greater than ilomastat alone (140 and 160 μg/mL in water and PBS, respectively). The in vitro activity of ilomastat-CD to inhibit collagen contraction in the presence of human Tenon fibroblast cells was unchanged compared to uncomplexed ilomastat. Topically administered ilomastat-CD in vivo to rabbit eyes resulted in a therapeutic concentration of ilomastat being present in the sclera and conjunctiva and within the aqueous humor.

Conclusions

Ilomastat-CD has the potential to be formulated as an eye drop for use as an antifibrotic, which may have implications for the prevention of scarring in many settings, for example glaucoma filtration surgery.

Mefenamic acid decreases inflammation but not joint lesions in experimental osteoarthritis

Mefenamic acid is a non-steroidal anti-inflammatory drug able to control the symptoms of osteoarthritis (OA), but its effects on protection of cartilage and bone are still unclear. This study aimed to investigate whether the control of inflammation by mefenamic acid translates into decreased joint lesions in experimental OA in rats. OA was induced by injecting 1 mg of monosodium iodoacetate (MIA) into the joints of rats. The animals were treated with mefenamic acid (50 mg/kg, daily, oral gavage) either pre-MIA injection (preventive) or post-MIA injection (therapeutic). Joint swelling and hyperalgesia were evaluated at baseline and 1, 3, 14 and 28 days after induction of OA. Intra-articular lavage and kinetics of cell migration into the synovium were measured 3 and 28 days after OA induction. Histopathological analysis, Osteoarthritis Research Society International (OARSI) score, total synovium cells count, cartilage area and levels of proteoglycans in joints were also evaluated. Mefenamic acid prevented joint oedema and hyperalgesia induced by MIA in the acute phase (3 days) of the disease. In the chronic phase (28 days), preventive and therapeutic regimens decreased the number of mononuclear cells in the joint cavity. In contrast, thickening of the synovium, bone resorption, loss of cartilage and levels of proteoglycans were unaffected by mefenamic acid when it was administered either preventively or therapeutically. Thus, mefenamic acid had anti-inflammatory effects but did not reduce the progression of OA lesions, thereby indicating that it is only effective for symptomatic control of OA.

Effects of thermosensitive chitosan-gelatin based hydrogel containing glutathione on Cisd2-deficient chondrocytes under oxidative stress

Aging is considered as a primary risk factor in the development of osteoarthritis (OA) which associated with mitochondrial dysfunction and oxidative stress. CDGSH iron sulfur domain 2 (Cisd2) deficiency causes mitochondrial dysfunction and drive premature aging. In the present study, thermosensitive chitosan-gelatin based hydrogel containing glutathione was developed as injectable drug delivery system for administration by minimal invasive surgery for the treatment of OA. Cisd2 deficiency (Cisd2^-/-) mouse induced pluripotent stem cells-derived chondrocytes were established and characterized. The results suggested that 100μM of glutathione may be an optimal concentration to treat Cisd2^-/- chondrocytes without cytotoxicity. The developed hydrogel showed sustained release profile of the glutathione and could decrease the reactive oxygen species level. Post-treatment of glutathione-loaded hydrogel could rescue Cisd2^-/- chondrocytes from oxidative damage via increasing catalase activity, down-regulation of inflammation, and decreasing apoptosis. These results suggest that thermosensitive glutathione-loaded hydrogel may be a potential antioxidant therapeutic strategy for treating Cisd2^-/- chondrocytes in the near future.

Wogonin, a plant derived small molecule, exerts potent anti-inflammatory and chondroprotective effects through the activation of ROS/ERK/Nrf2 signaling pathways in human Osteoarthritis chondrocytes

Osteoarthritis (OA), characterized by progressive destruction of articular cartilage, is the most common form of human arthritis. Here, we evaluated the potential chondroprotective and anti-inflammatory effects of Wogonin, a naturally occurring flavonoid, in IL-1β-stimulated human OA chondrocytes and cartilage explants. Wogonin completely suppressed the expression and production of inflammatory mediators including IL-6, COX-2, PGE₂, iNOS and NO in IL-1β-stimulated OA chondrocytes. Further, Wogonin exhibits potent chondroprotective potential by switching the signaling axis of matrix degradation from catabolic towards anabolic ends and inhibited the expression, production and activities of matrix degrading proteases including MMP-13, MMP-3, MMP-9, and ADAMTS-4 in OA chondrocytes, and blocked the release of s-GAG and COL2A1 in IL-1β-stimulated OA cartilage explants. Wogonin also elevated the expression of cartilage anabolic factors COL2A1 and ACAN in chondrocytes and inhibited the IL-1β-mediated depletion of COL2A1 and proteoglycan content in the matrix of cartilage explants. The suppressive effect of Wogonin was not mediated through the inhibition of MAPKs or NF-κB activation. Instead, Wogonin induced mild oxidative stress through the generation of ROS and depletion of cellular GSH, thereby modulating the cellular redox leading to the induction of Nrf2/ARE pathways through activation of ROS/ERK/Nrf2/HO-1-SOD2-NQO1-GCLC signaling axis in OA chondrocytes. Molecular docking studies revealed that Wogonin can disrupt KEAP-1/Nrf-2 interaction by directly blocking the binding site of Nrf-2 in the KEAP-1 protein. Genetic ablation of Nrf2 using specific siRNA, significantly abrogated the anti-inflammatory and chondroprotective potential of Wogonin in IL-1β-stimulated OA chondrocytes. Our data indicates that Wogonin exerts chondroprotective effects through the suppression of molecular events involved in oxidative stress, inflammation and matrix degradation in OA chondrocytes and cartilage explants. The study provides novel insights into the development of Nrf2 as a promising candidate and Wogonin as a therapeutic agent for the management of OA.

A Polyphenol-rich Pomegranate Fruit Extract Suppresses NF-κB and IL-6 Expression by Blocking the Activation of IKKβ and NIK in Primary Human Chondrocytes

Pomegranate fruit extract (PE) rich in polyphenols has been shown to exert chondroprotective effects, but the mechanism is not established. Here, we used an in vitro model of inflammation in osteoarthritis (OA) to investigate the potential of PE to suppress interleukin 1 beta (IL-1β)-stimulated expression of inflammatory cytokine IL-6, generation of reactive oxygen species (ROS) levels, and investigated the mechanism of NF-κB inhibition by analyzing the activation of the kinases upstream of IκBα in primary human chondrocytes. Total and phosphorylated forms of kinases and expression of IL-6 were determined at protein and mRNA levels by western immunoblotting and Taqman assay, respectively. Dihydrorhodamine 123 staining estimated ROS generation. Pomegranate fruit extract inhibited the mRNA and protein expression of IL-6, generation of ROS, and inhibited the IL-1β-mediated phosphorylation of inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ), expression of IKKβ mRNA, degradation of IκBα, and activation and nuclear translocation of NF-κB/p65 in human chondrocytes. Importantly, phosphorylation of NF-κB-inducing kinase was blocked by PE in IL-1β-treated human OA chondrocytes. Taken together, these data suggest that PE exerts the chondroprotective effect(s) by suppressing the production of IL-6 and ROS levels. Inhibition of NF-κB activation by PE was blocked via modulation of activation of upstream kinases in human OA chondrocytes. Copyright © 2017 John Wiley & Sons, Ltd.

Females with Unexplained Joint Pain Following Total Joint Arthroplasty Exhibit a Higher Rate and Severity of Hypersensitivity to Implant Metals Compared with Males: Implications of Sex-Based Bioreactivity Differences

BACKGROUND

Recent studies indicate that females demonstrate an increased risk of experiencing adverse local tissue reactions, aseptic loosening, and revision after primary metal-on-metal hip resurfacing arthroplasty compared with males; the underlying biological mechanisms responsible for sex discrepancies in implant failure remain unclear. In addition to anatomical and biomechanical sex differences, there may be inherent immunological disparities that predispose females to more aggressive adaptive immune reactivity to implant debris, i.e., metal sensitivity.

METHODS

In this retrospective study, we analyzed sex-associated rates and levels of metal sensitization in 1,038 male and 1,575 female subjects with idiopathic joint pain following total joint arthroplasty (TJA) who were referred for in vitro metal-sensitivity testing.

RESULTS

Females demonstrated a significantly higher rate and severity of metal sensitization compared with males. The median lymphocyte stimulation index (SI) among males was 2.8 (mean, 5.4; 95% confidence interval [CI], 4.9 to 6.0) compared with 3.5 (mean, 8.2; 95% CI, 7.4 to 9.0) among females (p < 0.05). Forty-nine percent of females had an SI of ≥4 (reactive) compared with 38% of males, and the implant-related level of pain was also significantly (p < 0.0001) higher among females (mean, 6.8; 95% CI, 6.6 to 6.9) compared with males (mean, 6.1; 95% CI, 6.0 to 6.3).

CONCLUSIONS

In a select group of patients who had joint pain following TJA and no evidence of infection and who were referred for metal-sensitivity testing, females exhibited a higher level of pain and demonstrated a higher rate and severity (as measured by lymphocyte SI) of metal sensitization compared with males.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

In vitro modulation of the behavior of adhering macrophages by medications is biomaterial-dependent

After implantation of a biomaterial, an inflammatory response involving macrophages is induced. The behavior of macrophages depends on their phenotype, and by directing macrophage polarization unwanted effects may be avoided. In this study, the possibility to modulate the behavior of macrophages activated by biomaterials was assessed in an in vitro model. Primary human monocytes were seeded on polyethylene terephthalate, polypropylene and polylactic acid yarns, and treated with medications frequently used by patients: rapamycin, dexamethasone, celecoxib or pravastatin. Modulation of the adhering macrophages with rapamycin resulted in a generally pro-inflammatory effect. Dexamethasone caused an overall anti-inflammatory effect on the macrophages cultured on either material, while celecoxib only affected macrophages adhering to polyethylene terephthalate and polylactic acid. Pravastatin increased the pro-inflammatory genes of macrophages cultured on polypropylene and polylactic acid. Pairwise comparison revealed that macrophages adhering to polylactic acid seemed to be more susceptible to phenotype modulation than when adhering to polypropylene or polyethylene terephthalate. The data show that macrophages activated by the biomaterials can be modulated, yet the degree of the modulatory capacity depends on the type of material. Combined, this model provides insights into the possibility of using a medication in combination with a biomaterial to direct macrophage behavior and thereby possibly avoid unwanted effects after implantation.

A wogonin-rich-fraction of Scutellaria baicalensis root extract exerts chondroprotective effects by suppressing IL-1β-induced activation of AP-1 in human OA chondrocytes

Osteoarthritis (OA) is a common joint disorder with varying degrees of inflammation and sustained oxidative stress. The root extract of Scutellaria baicalensis (SBE) has been used for the treatment of inflammatory and other diseases. Here, we performed activity-guided HPLC-fractionation of SBE, identified the active ingredient(s) and investigated its chondroprotective potential. We found that the Wogonin containing fraction-4 (F4) was the most potent fraction based on its ability to inhibit ROS production and the suppression of catabolic markers including IL-6, COX-2, iNOS, MMP-3, MMP-9, MMP-13 and ADAMTS-4 in IL-1β-treated OA chondrocytes. OA chondrocytes treated with F4 in the presence of IL-1β showed significantly enhanced expression of anabolic genes ACAN and COL2A1. In an in vitro model of cartilage degradation treatment with F4 inhibited s-GAG release from IL-1β-treated human cartilage explants. The inhibitory effect of F4 was not mediated through the inhibition of MAPKs and NF-κB activation but was mediated through the suppression of c-Fos/AP-1 activity at transcriptional and post transcriptional levels in OA chondrocytes. Purified Wogonin mimicked the effects of F4 in IL-1β-stimulated OA chondrocytes. Our data demonstrates that a Wogonin-rich fraction of SBE exert chondroprotective effects through the suppression of c-Fos/AP-1 expression and activity in OA chondrocytes under pathological conditions.

'Multimorbidity' as the manifestation of network disturbances

We argue that 'multimorbidity' is the manifestation of interconnected physiological network processes within an individual in his or her socio-cultural environment. Networks include genomic, metabolomic, proteomic, neuroendocrine, immune and mitochondrial bioenergetic elements, as well as social, environmental and health care networks. Stress systems and other physiological mechanisms create feedback loops that integrate and regulate internal networks within the individual. Minor (e.g. daily hassles) and major (e.g. trauma) stressful life experiences perturb internal and social networks resulting in physiological instability with changes ranging from improved resilience to unhealthy adaptation and 'clinical disease'. Understanding 'multimorbidity' as a complex adaptive systems response to biobehavioural and socio-environmental networks is essential. Thus, designing integrative care delivery approaches that more adequately address the underlying disease processes as the manifestation of a state of physiological dysregulation is essential. This framework can shape care delivery approaches to meet the individual's care needs in the context of his or her underlying illness experience. It recognizes 'multimorbidity' and its symptoms as the end product of complex physiological processes, namely, stress activation and mitochondrial energetics, and suggests new opportunities for treatment and prevention. The future of 'multimorbidity' management might become much more discerning by combining the balancing of physiological dysregulation with targeted personalized biotechnology interventions such as small molecule therapeutics targeting specific cellular components of the stress response, with community-embedded interventions that involve addressing psycho-socio-cultural impediments that would aim to strengthen personal/social resilience and enhance social capital.

Harpagoside suppresses IL-6 expression in primary human osteoarthritis chondrocytes

There is growing evidence in support of the involvement of inflammatory response in the pathogenesis of osteoarthritis (OA). Harpagoside, one of the bioactive components of Harpagophytum procumbens (Hp), has been shown to possess anti-inflammatory properties. Here we used an in vitro model of inflammation in OA to investigate the potential of harpagoside to suppress the production of inflammatory cytokines/chemokines such as IL-6 and matrix degrading proteases. We further investigated the likely targets of harpagoside in primary human OA chondrocytes. OA chondrocytes were pre-treated with harpagoside before stimulation with IL-1β. mRNA expression profile of 92 cytokines/chemokines was determined using TaqMan Human Chemokine PCR Array. Expression levels of selected mRNAs were confirmed using TaqMan assays. Protein levels of IL-6 and MMP-13 were assayed by ELISA and immunoblotting. Total protein levels and phosphorylation of signaling proteins were determined by immunoblotting. Cellular localization of IL-6 and c-Fos was performed by immunofluorescence and confocal microscopy. DNA binding activity of c-FOS/AP-1 was determined by ELISA. Harpagoside significantly altered the global chemokine expression profile in IL-1β-stimulated OA chondrocytes. Expression of IL-6 was highly induced by IL-1β, which was significantly inhibited by pre-treatment of OA chondrocytes with harpagoside. Harpagoside did not inhibit the IL-1β-induced activation of NF-κB and C/EBPβ transcription factors but suppressed the IL-1β-triggered induction, phosphorylation, and DNA binding activity of c-FOS, one of the main components of AP-1 transcription factors. Further, harpagoside significantly inhibited the expression of MMP-13 in OA chondrocytes under pathological conditions. siRNA-mediated knockdown of IL-6 resulted in suppressed expression and secretion of MMP-13 directly linking the role of IL-6 with MMP-13 expression. Taken together, the present study suggests that harpagoside exerts a significant anti-inflammatory effect by inhibiting the inflammatory stimuli mediated by suppressing c-FOS/AP-1 activity in OA chondrocytes under pathological conditions. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:311-320, 2017.

A Role for Soluble IL-6 Receptor in Osteoarthritis

Interleukin-6 (IL-6) is one of several pro-inflammatory cytokines present at elevated levels in the synovial fluid of individuals with confirmed clinical diagnosis of rheumatoid arthritis (RA) and osteoarthritis (OA). The mechanism of action of IL-6 was shown to involve its capacity to interact with a membrane-bound IL-6 receptor (mIL-6Rα), also known as the "classical" IL-6 pathway, or through its interaction with a soluble IL-6 receptor (sIL-6R) termed the "trans-signaling" pathway. Activation of downstream signaling is transduced via these IL-6 receptors and principally involves the Janus Kinase/Signal Transduction and Activators of Transcription (JAK/STAT) signaling pathway that is further regulated by glycoprotein-130 (gp130) interacting with the IL-6/mIL-6R complex. Phosphorylation of STAT proteins via JAK activation facilitates STAT proteins to act as transcription factors in inflammation. However, the biological function(s) of the sIL-6R in human chondrocytes requires further elucidation, although we previously showed that exogenous sIL-6R significantly suppressed the synthesis of neutrophil gelatinase-associated lipocalin (NGAL) in the immortalized line of human chondrocytes, C28/I2. NGAL was shown to regulate the activity of matrix metalloproteinase-9 (MMP-9), whose activity is crucial in OA for the destruction of articular cartilage. The "shedding" of sIL-6R from the plasma membrane is carried out by a family of enzymes known as A Distintegrin and Metalloproteinase (ADAM), which are also elevated in OA. In this paper, we have systematically reviewed the role played by IL-6 in OA. We have proposed that sIL-6R may be an important target for future drug development in OA by ameliorating cartilage extracellular protein degradation.

Evaluation of serum cytokines in cats with and without degenerative joint disease and associated pain

Degenerative joint disease is common in cats, with signs of pain frequently found on orthopedic examination and radiographs often showing evidence of disease. However, understanding of the pathophysiology of degenerative joint disease and associated pain remains limited. Several cytokines have been identified as having a role in pain in humans, but this has not been investigated in cats. The present study was performed to use a multiplex platform to evaluate the concentration of 19 cytokines and chemokines in serum samples obtained from cats with and without degenerative joint disease and associated pain. Samples from a total of 186 cats were analyzed, with cats representing a range of severity on radiographic and orthopedic evaluations and categorized by degenerative joint disease scores and pain scores. Results showed that cats with higher radiographic degenerative joint disease scores have higher serum concentrations of IL-4 and IL-8, while cats with higher orthopedic exam pain scores have higher concentrations of IL-8, IL-2, and TNF-α; increased concentration of IL-8 in degenerative joint disease and pain may be confounded by the association with age. Discriminant analysis was unable to identify one or more cytokines that distinguish between groups of cats classified based on degenerative joint disease score category or pain score category. Finally, cluster analysis driven by analyte concentrations shows separation of groups of cats, but features defining the groups remain unknown. Further studies are warranted to investigate any changes in cytokine concentrations in response to analgesic therapies, and further evaluate the elevations in cytokine concentrations found here, particularly focused on studies of local cytokines present in synovial fluid.

Circulating T helper 9 cells and increased serum interleukin-9 levels in patients with knee osteoarthritis

The purpose of this study was to examine the roles of T helper 9 (Th9) cells and the serum interleukin (IL)-9 level in the pathogenesis of osteoarthritis (OA). The numbers of IL-9(+) CD4(+) CD8(-) T cells, interferon (IFN)-γ+ CD4(+) CD8(-) T cells, IL-4(+) CD4(+) CD8(-) T cells, and IL-17A(+) CD4(+) CD8(-) T cells in 25 OA patients and 13 healthy controls (HC) were examined by flow cytometry. The serum concentrations of IL-9, IL-4, IL-17A, and IFN-γ were also determined. The numbers of CD4(+) CD45RO(+) T cells, Th9 cells, Th1 cells, and Th17 cells in OA patients were significantly higher than those in HCs. Furthermore, serum IL-9, IL-17A, and IFN-γ levels in OA patients were higher than those in HCs. The number of Th9 cells was positively correlated with the number of Th17 cells in OA patients. Furthermore, greater numbers of Th9 cells were positively associated with elevated C-reactive protein, and both Th9 cells and IL-9 levels were positively correlated with the Western Ontario and McMaster Universities Osteoarthritis index in OA patients. Th9 cell numbers and IL-9 levels are correlated with OA patient symptoms and joint functionality and may be a marker of disease activity.

Immune Mediators in Osteoarthritis: Infrapatellar Fat Pad-Infiltrating CD8+ T Cells Are Increased in Osteoarthritic Patients with Higher Clinical Radiographic Grading

Osteoarthritis is a condition of joint failure characterized by many pathologic changes of joint-surrounding tissues. Many evidences suggest the role of both innate and adaptive immunity that interplay, resulting either in initiation or in progression of osteoarthritis. Adaptive immune cells, in particular T cells, have been demonstrated to play a role in the development of OA in animal models. However, the underlying mechanism is yet unclear. Our aim was to correlate the frequency and phenotype of tissue-infiltrating T cells in the synovial tissue and infrapatellar fat pad with radiographic grading. Our results show that CD8+ T cells are increased in osteoarthritic patients with higher radiographic grading. When peripheral blood CD8+ T cells were examined, we show that CD8+ T cells possess a significantly higher level of activation than its CD4+ T cell counterpart (P < 0.0001). Our results suggest a role for CD8+ T cells and recruitment of these activated circulating peripheral blood CD8+ T cells to the knee triggering local inflammation within the knee joint.

Osteoarthritis: from pathogenic mechanisms and recent clinical developments to novel prospective therapeutic options

Osteoarthritis (OA) is a degenerative joint disease that, despite recent progress, has no curative treatment. Considerable research has recently been initiated to identify new potential therapeutic targets. In this review, we will set forth some of the major discoveries in the past 5 years, notably those dealing with the identification of pathogenic factors [hypoxia-inducible factors (HIFs), complement, transforming growth factor (TGF)-β and zinc-ZIP8]. New drugs and concepts currently in clinical development [anti-nerve growth factor (NGF), mesenchymal stromal cells and fibroblast growth factor (FGF)-18] will then be addressed. Finally, we will consider prospective avenues that could lead to mid-to-long-term developments of novel therapeutic concepts, notably those dealing with autophagy regulation and induced pluripotent stem cells.

Aerobic training modulates T cell activation in elderly women with knee osteoarthritis

Osteoarthritis of the knee (kOA) is a disease that mainly affects the elderly and can lead to major physical and functional limitations. However, the specific effects of walking, particularly on the immune system, are unknown. Therefore, this study aimed to analyze the effect of 12 weeks of walking (3×/week) on the leukocyte profile and quality of life (QL) of elderly women with kOA. Sixteen women (age: 67±4 years, body mass index: 28.07±4.16 kg/m²) participated in a walking program. The variables were assessed before and after 12 weeks of training with a progressively longer duration (30–55 min) and higher intensity (72–82% of HRmax determined using a graded incremental treadmill test). The QL was assessed using the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), and blood samples were collected for analysis with a cell counter and the San Fac flow cytometer. Walking training resulted in a 47% enhancement of the self-reported QL (P<0.05) and a 21% increase in the VO₂max (P<0.0001) in elderly women with kOA. Furthermore, there was a reduction in CD4+ cells (pre=46.59±7%, post=44.58±9%, P=0.0189) and a higher fluorescence intensity for CD18+CD4+ (pre=45.30±10, post=64.27±33, P=0.0256) and CD18⁺CD8⁺ (pre=64.2±27, post=85.02±35, P=0.0130). In conclusion, the walking program stimulated leukocyte production, which may be related to the immunomodulatory effect of exercise. Walking also led to improvements in the QL and physical performance in elderly women with kOA.

Sucrose, But Not Glucose, Blocks IL1-β-Induced Inflammatory Response in Human Chondrocytes by Inducing Autophagy via AKT/mTOR Pathway

Pathogenesis of osteoarthritis (OA) is multifactorial but interleukin-1β (IL-1β) is known to be an important mediator of cartilage degradation. Autophagy is an essential cellular homeostasis mechanism and has been proposed to protect against cartilage degradation and chondrocyte death under pathological conditions. We investigated the role of autophagy activated by sucrose, a natural disaccharide, in suppressing inflammatory mediator's expression and cell death under pathological conditions in human chondrocytes. Autophagy activation was investigated by Western blotting for LC3 and Beclin-1, immunofluorescence staining for LC3 puncta, and measuring autophagic flux. Activation of mTOR, AKT, and P70S6K was evaluated by Western blotting. Chondrocyte apoptosis was evaluated by propidium iodide (PI) staining using flowcytometry, expression of Bax by Western blotting, gene expression by TaqMan assays and caspase 3/7 activity was measured using a luminescence-based assay. We found that sucrose-induced active autophagy in OA chondrocytes in vitro was dependent on the activation of AKT/mTOR/P70S6K signaling pathways but was independent of reactive oxygen species (ROS) production. Sucrose activated autophagy blocked IL-1β-induced apoptosis and mRNA expression of MMP-13, COX-2, and IL-6 in human OA chondrocytes. Glucose or fructose, the two metabolites of sucrose, failed to induce autophagy indicating that autophagy was specifically mediated by sucrose. In conclusion, sucrose attenuated IL-1β induced apoptosis and the expression of catabolic mediators by inducing autophagy, and the autophagy in part was mediated through the activation of AKT/mTOR/P70S6K signaling pathway in human OA chondrocytes. J. Cell. Biochem. 118: 629-639, 2017. © 2016 Wiley Periodicals, Inc.

Preparation of Low Molecular Weight Chondroitin Sulfates, Screening of a High Anti-Complement Capacity of Low Molecular Weight Chondroitin Sulfate and Its Biological Activity Studies in Attenuating Osteoarthritis

Chondroitin sulfate (CS) plays important roles in the complement system. However, the CS structure is complicated due to different sources and the number and positions of sulfate groups. The objective of this study was to prepare different low molecular weight chondroitin sulfates (LMWCSs) and to investigate the biological activity in anti-complement capacity. A series of LMWCSs was prepared from different sources and characterized by ultraviolet-visible (UV) spectroscopy, high-performance liquid chromatography (HPLC), size exclusion chromatography-multiangle laser light scattering (SEC-MALLS) and nuclear magnetic resonance (NMR) spectroscopy. Hemolytic, anti-complement 3 deposition capacity and cell viability assays were carried out to investigate the biological activities in vitro. The results showed that LMWCS prepared from shark cartilage with the oxidative degradation method (LMWCS-S-O) had the best anti-complement capacity. LMWCS-S-O could inhibit the alternative pathway of the complement system and protect chondrocytes from cell death. The attenuating effect of LMWCS-S-O on Osteoarthritis (OA) was investigated by destabilization of the medial meniscus (DMM) model in vivo. Functional wind-up, histological and C5b-9 analyses were used to evaluate the treatment effect on the OA model. In vivo results showed that LMWCS-S-O could attenuate OA. LMWCS-S-O with a high content of ΔDi-2,6diS and ΔDi-6S could be used for attenuating OA through regulating the complement system.

The effect of pomegranate juice on clinical signs, matrix metalloproteinases and antioxidant status in patients with knee osteoarthritis

BACKGROUND

Osteoarthritis (OA) is one of the commonest forms of musculoskeletal disorders that leads to joint degeneration and has a major impact on patients' quality of life. Experimental and in vitro studies have suggested the protective roles of pomegranate juice (PJ) as a rich antioxidant source for mitigating cartilage inflammation. In this interventional study, 38 patients with knee OA were randomly divided into two groups: PJ or control for 6 weeks to evaluate the effect of this intervention on clinical signs, inflammation and antioxidant status.

RESULTS

Significant decreases in Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) total score (P = 0.01), stiffness score (P = 0.00) and physical function score (P = 0.01) were observed in PJ group after the intervention. The means of serum levels of matrix metalloproteinase (MMP)-13 was significantly decreased (P = 0.02) and glutathione peroxidase was increased in the intervention group compared with the control group after the study period (P = 0.02).

CONCLUSIONS

According to the findings of this clinical trial, PJ consumption can improve physical function and stiffness, decrease breakdown cartilage enzymes and increase antioxidant status in patients with knee OA. © 2016 Society of Chemical Industry.

Targeting formyl peptide receptor 1 of activated macrophages to monitor inflammation of experimental osteoarthritis in rat

Macrophages play a crucial role in the pathogenesis of osteoarthritis (OA). In this study, the feasibility of a formyl peptide receptor 1 (Fpr1)-targeting peptide probe cFLFLF-PEG-(64) Cu via positron emission tomography (PET) imaging was investigated for detection of macrophage activity during development of OA. Monoiodoacetate (MIA) was intraarticularly injected into the knee joint of Sprague-Dawley rats to induce OA. Five days later, cFLFLF-PEG-(64) Cu (∼7,400 kBq/rat) was injected into the tail vein and microPET/CT imaging was performed to assess the OA inflammation by detecting infiltration of macrophages by Fpr1 expression. In addition, a murine macrophage cell line RAW264.7 and two fluorescent probes cFLFLF-PEG-cyanine 7 (cFLFLF-PEG-Cy7) and cFLFLF-PEG-cyanine 5 (cFLFLF-PEG-Cy5) were used to define the binding specificity of the peptide to macrophages. It was found with the MIA model that the maximal standard uptake values (SUVmax ) for right (MIA treated) and left (control) knees were 17.96 ± 5.45 and 3.00 ± 1.40, respectively. Histological evaluation of cryomicrotome sections showed that Fpr1 expression, cFLFLF-PEG-Cy5 binding, and tartrate-resistant acid phosphatase activity were elevated in the injured synovial membranes. The in vitro experiments demonstrated that both fluorescent peptide probes could bind specifically to RAW264.7 cells, which was blocked by cFLFLF but not by the scramble peptide. The findings highlighted the use of cFLFLF-PEG-(64) Cu/PET as an effective method potentially applied for detection and treatment evaluation of OA. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1529-1538, 2016.

Expression profile of cytokines and chemokines in osteoarthritis patients: Proinflammatory roles for CXCL8 and CXCL11 to chondrocytes

There are interactions between immune response and destruction of articular cartilage/synovial tissue in osteoarthritis (OA), which leads to chronic inflammation and systemic failure of joints. However, the role of immunological factors in the pathogenesis of OA has not been fully elucidated. In this study, expressions of 47 cytokines and chemokines were tested in the peripheral bloods and synovial fluids from 13 normal controls (NCs) and 31 OA patients. The primary chondrocytes, which were isolated from cartilages of OA patients, were stimulated by recombinant CXCL8 and CXCL11 to analyze the proliferation, cytokine secretion, and signaling pathways. The levels of IL-17A, CXCL8, CXCL9, and CXCL11 were elevated in the serum and synovial fluids of OA patients. Moreover, expressions of CXCL8 and CXCL11 were remarkably increased in the synovial fluids of late stage OA. Stimulation of CXCL8/11 resulted in the reduction of primary chondrocytes proliferation with downregulation of G2-M stage but elevation of S stage and apoptosis cells. The secretions of proinflammatory cytokines and MMPs were also increased upon stimulation. Furthermore, CXCL8/11 stimulation induced the higher expressions of phosphorylated STAT3, NF-kB p50 and JNK, but not p38MAPK or ERK1/2. Our findings suggested that CXCL8 and CXCL11 promoted the apoptosis and suppressed the proliferation of chondrocytes probably via influencing JAK-STAT, NF-kB and JNK MAPK signaling pathway and enhancing the expressions of other proinflammatory cytokines. CXCL8/11 may aggravate the disease progression of OA, and may also be served as new therapeutic targets for treatment of OA.

Low-grade inflammation as a key mediator of the pathogenesis of osteoarthritis

Osteoarthritis (OA) has long been viewed as a degenerative disease of cartilage, but accumulating evidence indicates that inflammation has a critical role in its pathogenesis. Furthermore, we now appreciate that OA pathogenesis involves not only breakdown of cartilage, but also remodelling of the underlying bone, formation of ectopic bone, hypertrophy of the joint capsule, and inflammation of the synovial lining. That is, OA is a disorder of the joint as a whole, with inflammation driving many pathologic changes. The inflammation in OA is distinct from that in rheumatoid arthritis and other autoimmune diseases: it is chronic, comparatively low-grade, and mediated primarily by the innate immune system. Current treatments for OA only control the symptoms, and none has been FDA-approved for the prevention or slowing of disease progression. However, increasing insight into the inflammatory underpinnings of OA holds promise for the development of new, disease-modifying therapies. Indeed, several anti-inflammatory therapies have shown promise in animal models of OA. Further work is needed to identify effective inhibitors of the low-grade inflammation in OA, and to determine whether therapies that target this inflammation can prevent or slow the development and progression of the disease.

Novel effects of sarcopenic osteoarthritis on metabolic syndrome, insulin resistance, osteoporosis, and bone fracture: the national survey

This study compared the effects sarcopenic osteoarthritis on metabolic syndrome, insulin resistance, osteoporosis, and bone fracture. By using national survey data, we suggest that the relationship between sarcopenia and metabolic syndrome or insulin resistance is potentiated by the severity of osteoarthritis and is independent of body weight.

INTRODUCTION

Sarcopenia and osteoarthritis are known risk factors for metabolic syndrome. However, their combined effects on metabolic syndrome, insulin resistance and osteoporosis remain uncertain.

METHODS

We used data from the fifth Korean National Health and Nutrition Examination Survey using a total of 3158 adults (age >50 years). Sarcopenia was defined as a skeletal muscle index score (appendicular skeletal muscle mass/body weight) within the fifth percentile of sex-matched younger reference participants. Radiographic knee osteoarthritis was defined as a Kellgren-Lawrence (K-L) grade of 2 or greater. Metabolic syndrome was diagnosed using the National Cholesterol Education Program criteria. Insulin resistance was evaluated using the homeostasis model assessment-estimated insulin resistance index (HOMA-IR). Osteoporosis was defined using the World Health Organization T-score criteria.

RESULTS

In multivariable logistic regression analysis, the sarcopenic osteoarthritis group had a higher odds ratio (OR) for metabolic syndrome (OR = 11.00, 95 % confidential interval (CI) = 2.12-56.99, p = 0.013) than the non-sarcopenic osteoarthritis (OR = 1.02, 95 % CI = 0.65-1.62, p = 0.972) and sarcopenic non-osteoarthritis groups (OR = 7.15, 95 % CI = 1.57-32.53, p = 0.027). Similarly, sarcopenic osteoarthritis had a greater OR of highest HOMA-IR quartiles (OR = 8.19, 95 % CI = 2.03-33.05, p = 0.003) than the other groups. Overall, the association between the K-L grade and body mass index was significant; however, this significance was lower in individuals with sarcopenia and was lost in those with sarcopenic osteoarthritis. Additionally, osteoporosis and bone fracture were not associated to sarcopenic osteoarthritis (p > 0.05).

CONCLUSIONS

These results suggest that the relationship between sarcopenia and metabolic syndrome or insulin resistance is potentiated by the severity of osteoarthritis and is independent of body weight.

Interleukin-29 Enhances Synovial Inflammation and Cartilage Degradation in Osteoarthritis

We have recently shown that IL-29 was an important proinflammatory cytokine in pathogenesis of rheumatoid arthritis (RA). Inflammation also contributes to the pathogenesis of osteoarthritis (OA). The aim of this study was to investigate the effect and mechanism of IL-29 on cytokine production and cartilage degradation in OA. The mRNA levels of IL-29 and its specific receptor IL-28Ra in peripheral blood mononuclear cells (PBMCs) were significantly increased in OA patients when compared to healthy controls (HC). In the serum, IL-29 protein levels were higher in OA patients than those in HC. Immunohistochemistry revealed that both IL-29 and IL-28Ra were dramatically elevated in OA synovium compared to HC; synovial fibroblasts (FLS) and macrophages were the main IL-29-producing cells in OA synovium. Furthermore, recombinant IL-29 augmented the mRNA expression of IL-1β, IL-6, IL-8, and matrix-metalloproteinase-3 (MMP-3) in OA FLS and increased cartilage degradation when ex vivo OA cartilage explant was coincubated with OA FLS. Finally, in OA FLS, IL-29 dominantly activated MAPK and nuclear factor-κB (NF-κB), but not Jak-STAT and AKT signaling pathway as examined by western blot. In conclusion, IL-29 stimulates inflammation and cartilage degradation by OA FLS, indicating that this cytokine is likely involved in the pathogenesis of OA.

Interleukin-1β induced Stress Granules Sequester COX-2 mRNA and Regulates its Stability and Translation in Human OA Chondrocytes

Enhanced and immediate expression of cyclooxygenase-2 (COX-2) mRNA is observed in IL-1β-stimulated OA chondrocytes but the synthesis of protein found significantly delayed. Here we investigated the role of stress granules (SGs), ribonucleoprotein complexes that regulate mRNA translation, in the delayed translation of COX-2 mRNAs in IL-1β-stimulated OA chondrocytes. Stimulation of human chondrocytes with IL-1β activated the stress response genes and the phosphorylation of eIF2α that triggered the assembly of SGs. Using combined immunofluorescence staining of SGs markers and COX-2 protein, RNA fluorescence in situ hybridization and RNA immunoprecipitation, the COX-2 mRNAs were found sequestered in SGs in IL-1β-stimulated OA chondrocytes. No increase in COX-2 protein expression was observed during the persistence of SGs but enhanced expression of COX-2 protein was noted upon clearance of the SGs. Inhibition of SGs clearance blocked COX-2 mRNA translation whereas blocking the assembly of SGs by TIA-1 depletion resulted in rapid and increased production of COX-2 and PGE2. Our findings show for the first time assembly of SGs and sequestration of COX-2 mRNAs in human OA chondrocytes under pathological conditions. Post-transcriptional regulation of COX-2 mRNAs translation by SGs indicates a role in IL-1β-mediated catabolic response that could be therapeutically targeted in OA.

Leukocyte-Rich Platelet-Rich Plasma Injections Do Not Up-Modulate Intra-Articular Pro-Inflammatory Cytokines in the Osteoarthritic Knee

Introduction

The presence of leukocytes in platelet concentrates is deemed to cause deleterious effects when injected intra articularly. The aim of this study is to analyse both local and systemic effects induced by leukocyte-rich Platelet-rich Plasma (PRP) injections through a proteomic characterization of serial synovial fluid and blood samples obtained from subjects treated for knee OA. Secondary aim was to compare the effects on knee homeostasis and systemic response with those obtained with visco-supplementation.

Methods

Thirty-six OA patients treated either by autologous L-PRP or HA intra-articular knee injections, administered in series of three at one-week intervals, were analyzed. Just before the injection, 1 ml of synovial fluid was collected through the same needle way. In the same time, a peripheral blood sample was obtained and plasma separated. A further peripheral blood sample was collected at 2, 6, and 12 months. L-PRP, plasma and synovial fluid were tested by multiplex bead-based sandwich immunoassay by means of the Bio-Plex suspension array system (Bio-Rad Laboratories) for the presence of pro- and anti-inflammatory cytokines (IL-1beta, IL-6, IL-8, IL-17 and IL-4, IL-10, IL-13) and growth factors (FGF-b, HGF, PDGF-AB/BB).

Results

In general, pro-inflammatory cytokine levels were similar at basal condition and after treatment whereas anti-inflammatory ones were nearly undetectable. L-PRP administration did not modulate significant changes of cytokine concentrations either in synovial fluid or plasma, whatever the time points analyzed. No different trend was observed between L-PRP and HA administration in terms of pro- and anti-inflammatory cytokines, as well as growth factors.

Conclusions

In contrast with the evidence reported by “in vitro” studies, where a cellular pro-inflammatory response appears to be induced by the presence of leukocytes, these results suggest that the presence leukocyte-rich PRP doesn’t induce a relevant in vivo up regulation of pro-inflammatory mediators.

Macroscopical, Histological, and In Vitro Characterization of Nonosteoarthritic Versus Osteoarthritic Hip Joint Cartilage

Osteoarthritis (OA) might affect chondrocyte culture characteristics and complement expression. Therefore, this study addressed the interrelation between macroscopical and microscopical structure, complement expression, and chondrocyte culture characteristics in non-OA and OA cartilage. Femoral head cartilage samples harvested from patients with femoral neck fractures (FNFs) and OA were analyzed for macroscopical alterations using an in-house scoring system, graded histologically (Mankin score), and immunolabeled for complement regulatory proteins (CRPs) and receptors. Morphology of monolayer cultured chondrocytes isolated from a subset of samples was assessed. The macroscopical score distinguished the FNF and OA cartilage samples and correlated significantly with the histological results. Chondrocyte phenotype from FNF or OA cartilage differed. Complement receptor C5aR, CRPs CD55 and CD59, and weakly receptor C3AR were detected in the investigated FNF and OA cartilage, except for CD46, which was detected in only two of the five investigated donors. The in-house score also allows inexperienced observers to distinguish non-OA and OA cartilage for experimental purposes.

Cartilage tissue engineering: From biomaterials and stem cells to osteoarthritis treatments

Articular cartilage is a non-vascularized and poorly cellularized connective tissue that is frequently damaged as a result of trauma and degenerative joint diseases such as osteoarthrtis. Because of the absence of vascularization, articular cartilage has low capacity for spontaneous repair. Today, and despite a large number of preclinical data, no therapy capable of restoring the healthy structure and function of damaged articular cartilage is clinically available. Tissue-engineering strategies involving the combination of cells, scaffolding biomaterials and bioactive agents have been of interest notably for the repair of damaged articular cartilage. During the last 30 years, cartilage tissue engineering has evolved from the treatment of focal lesions of articular cartilage to the development of strategies targeting the osteoarthritis process. In this review, we focus on the different aspects of tissue engineering applied to cartilage engineering. We first discuss cells, biomaterials and biological or environmental factors instrumental to the development of cartilage tissue engineering, then review the potential development of cartilage engineering strategies targeting new emerging pathogenic mechanisms of osteoarthritis.

Fractalkine (CX3CL1): a biomarker reflecting symptomatic severity in patients with knee osteoarthritis

BACKGROUND

Elevated serum and synovial fluid (SF) fractalkine (CX3CL1) levels have been detected in patients with knee osteoarthritis (OA). The current study was carried out to investigate the association between serum and SF fractalkine levels with symptomatic severity in patients with knee OA.

METHOD

One hundred ninety-three patients with OA and 182 healthy controls were enrolled in this study. The symptomatic severity was assessed by the Western Ontario McMaster University Osteoarthritis scores.

RESULTS

Fractalkine levels in SF and serum were both positively associated with self-reported greater pain and physical disability.

CONCLUSIONS

Fractalkine in SF and serum may serve as a biomarker for reflecting symptomatic severity. Therapeutic interventions that target fractalkine signaling pathways to delay OA-related symptoms deserve further study.

A Network Pharmacology Approach to Uncover the Pharmacological Mechanism of XuanHuSuo Powder on Osteoarthritis

As the most familiar type of arthritis and a chronic illness of the joints, Osteoarthritis (OA) affects a great number of people on the global scale. XuanHuSuo powder (XHSP), a conventional herbal formula from China, has been extensively applied in OA treatment. Nonetheless, its pharmacological mechanism has not been completely expounded. In this research, a network pharmacology approach has been chosen to study the pharmacological mechanism of XHSP on OA, and the pharmacology networks were established based on the relationship between four herbs found in XHSP, compound targets, and OA targets. The pathway enrichment analysis revealed that the significant bioprocess networks of XHSP on OA were regulation of inflammation, interleukin-1β (IL-1β) production and nitric oxide (NO) biosynthetic process, response to cytokine or estrogen stimuli, and antiapoptosis. These effects have not been reported previously. The comprehensive network pharmacology approach developed by our research has revealed, for the first time, a connection between four herbs found in XHSP, corresponding compound targets, and OA pathway systems that are conducive to expanding the clinical application of XHSP. The proposed network pharmacology approach could be a promising complementary method by which researchers might better evaluate multitarget or multicomponent drugs on a systematic level.

A New Application of Parallel Synthesis Strategy for Discovery of Amide-Linked Small Molecules as Potent Chondroprotective Agents in TNF-α-Stimulated Chondrocytes

As part of an effort to profile potential therapeutics for the treatment of inflammation-related diseases, a diversity of amide-linked small molecules was synthesized by using parallel synthesis strategy. Moreover, these new compounds were also evaluated for their inhibitory effects on nitric oxide (NO) by using tumor necrosis factor alpha (TNF-α)-induced inflammatory responses in chondrocytes. Among the tested compounds, N-(3-chloro-4-fluorophenyl)-2-hydroxybenzamide (HS-Ck) was the most potent inhibitor of NO production and inducible nitric oxide synthase (iNOS) expression in TNF-α-stimulated chondrocytes. In addition, our biological results indicated that HS-Ck might suppress the expression levels of iNOS and matrix metalloproteinases-13 (MMP-13) activities through downregulating the activation of nuclear factor kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT-3) transcriptional factors. Therefore, the parallel synthesis was successful used to develop a new class of potential anti-inflammatory agents as chondroprotective candidates for the treatment of osteoarthritis.

Culture expanded primary chondrocytes have potent immunomodulatory properties and do not induce an allogeneic immune response

OBJECTIVE

Allogeneic cell therapies, such as mesenchymal stromal cells (MSC), which have potent regenerative and anti-inflammatory potential are being investigated as a therapy for osteoarthritis (OA) and cartilage injury. Here we describe another potential source of regenerative and anti-inflammatory allogeneic cells, culture expanded primary chondrocytes (CEPC). In direct comparison to allogeneic MSC, we extensively assess the immunological interactions of CEPC in an allogeneic setting.

METHODS

Chondrocytes were isolated from rat articular cartilage and cultured in normoxic or hypoxic conditions. In vitro co-culture assays with allogeneic lymphocytes and macrophages were used to assess the immunomodulatory capacities of the chondrocytes, followed by immune response analysis by flow cytometry, ELISA and qPCR.

RESULTS

CEPC showed reduced induction of proliferation, activation and cytotoxic granzyme B expression in allogeneic T cells. Importantly, exposure to pro-inflammatory cytokines did not increase CEPC immunogenicity despite increases in MHC-I. Furthermore, CEPC had a potent ability to suppress allogeneic T cell proliferation, which was dependent on nitric oxide production. This suppression was contact independent in hypoxia cultured CEPC. Finally, chondrocytes were shown to have the capacity to modulate pro-inflammatory macrophage activity by reducing MHC-II expression and TNF-α secretion.

CONCLUSION

These data indicate the potential use of allogeneic chondrocytes in OA and cartilage defects. The lack of evident immunogenicity, despite exposure to a pro-inflammatory environment, coupled with the immunomodulatory ability indicates that these cells have the potential to evade the host immune system and suppress inflammation, thus potentially facilitating the resolution of OA induced inflammation and cartilage regeneration.

Aberrant levels of natural IgM antibodies in osteoarthritis and rheumatoid arthritis patients in comparison to healthy controls

Natural IgM antibodies (nIgM) are polyreactive autoantibodies that have diverse roles in regulating autoimmunity, systemic inflammation and removal of oxidized low-density lipoproteins (oxLDL). We hypothesized that aberrant states of nIgM may exist in persons with osteoarthritis (OA) and rheumatoid arthritis (RA). Herein, we characterized and compared the levels of nIgM specific for phosphorylcholine (anti-PC), double-stranded DNA (anti-dsDNA), and galactosyl (anti-Gal) in persons with OA, RA and healthy controls (HC). Levels of anti-PC nIgM in OA patients were significantly lower than both HC and RA patients in an age-adjusted analysis (P<0.05). In contrast, anti-Gal nIgM levels were significantly higher in RA patients than OA patients (P<0.05) and markedly increased in comparison to HC. Anti-PC nIgM significantly correlated with anti-dsDNA and anti-Gal nIgM levels in HC and RA (P<0.05) but not in OA patients. Elevated CRP levels were associated with RA conditions and old ages in general. There was no significant correlation between anti-PC nIgM and CRP or oxLDL levels. Our study highlights for the first time the evidence of aberrant state of nIgM in human OA compared to healthy individuals that implicates a deficiency in immune responses to oxLDL which may contribute to the metabolic syndromes in the development of OA.

Biologic basis of osteoarthritis: state of the evidence

PURPOSE OF REVIEW

Evidence accumulated since 2010 indicates that human osteoarthritis should now be reclassified as a systemic musculoskeletal disease rather than a focal disorder of synovial joints.

RECENT FINDINGS

Inflammation was seen as the key component promoting synovitis as well as progression of cartilage and bone destruction in osteoarthritis. Thus, metabolic-triggered inflammation involving cytokines, adipokines, abnormal metabolites, acute phase reactants and even complement, all appear to play major roles in osteoarthritis pathophysiology. Immune-mediated inflammation involving T cells and B cells as well as macrophages is now considered a common finding in osteoarthritis synovial tissue. Many experimental and clinical analyses showed that the proinflammatory cytokines, which stimulate matrix metalloproteinase and a disintegrin and metalloproteinase with thrombospondin motif gene transcription in normal and osteoarthritis human chondrocyte cultures, are also present at significantly elevated levels in the synovial fluid of osteoarthritis patients compared with nonarthritic synovial fluids.

SUMMARY

Human osteoarthritis is a systemic musculoskeletal disorder involving activation of innate and adaptive immune systems accompanied by inflammation exemplified by the elevated production of proinflammatory cytokines, which play a significant role in the progression of the disease. The future of novel therapies for osteoarthritis should consider developing drug development strategies designed to inhibit proinflammatory cytokine-induced signal transduction. These strategies have been successful in the development of drugs for the treatment of rheumatoid arthritis.

The role of MCP-1-CCR2 ligand-receptor axis in chondrocyte degradation and disease progress in knee osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a common arthritic disease and multifactorial whole-joint disease. Interactions of chemokines and OA is inadequately documented.

RESULTS

In vivo and in vitro studies were conducted to investigate monocyte chemoattractant protein 1 (MCP-1) and receptor chemokine (C-C motif) receptor 2 (CCR2) in chondrocyte degradation and cartilage degeneration. Chondrocytes from 16 OA patients and 6 normal controls were involved in this study. After stimulation of MCP-1, the expression of MCP-1 and CCR2 increased significantly (P < 0.001) and the expression of MMP-13 also increased (P < 0.05). MCP-1 stimulation also induced (or enhanced) the apoptosis of OA chondrocytes (P < 0.05). Additionally, the degradation of cartilage matrix markers (metalloproteinase 3 and 13, MMP3 and MMP13) in the culture medium of normal chondrocytes was also assessed. Furthermore, intra-articular injection of MCP-1 in mouse knees induced cartilage degradation and the CCR2 antagonist did not impede cartilage destroy in rats knees of monosodium iodoacetate (MIA) model.

CONCLUSIONS

The results of this study demonstrate that the MCP-1-CCR2 ligand-receptor axis plays a special role in the initiation and progression of OA pathology. Patients with ambiguous etiology can gain some insight from the MCP-1-CCR2 ligand-receptor axis.

Differential Interactive Effects of Cartilage Traumatization and Blood Exposure In Vitro and In Vivo

BACKGROUND

Sport injuries of the knee often lead to posttraumatic arthritis. In addition to direct damage of the cartilage, trauma-associated intra-articular bleeding may cause hemarthrosis. Both blood exposure and trauma are known to induce cell death and inflammation and to enhance proteoglycan release in cartilage.

HYPOTHESIS

Blood exposure increases chondrocyte death as well as inflammatory and degenerative processes in traumatized cartilage.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human macroscopically intact osteoarthritic (OA) cartilage explants were impacted by a drop-tower system (0.59 J) and cultivated with or without 10% blood. Interactive effects were studied concerning cell survival, gene expression, and the release of mediators over 24 hours and 96 hours. To evaluate the effects of trauma and hemarthrosis in vivo, a newly established blunt cartilage trauma model in the rabbit was used. Treatment of the knee joints of mature New Zealand White rabbits consisted of the following groups: control (C), arthrotomy (A), arthrotomy with cartilage trauma (AT; 1.0 J), and arthrotomy with cartilage trauma and blood injection (ATH). After 1 and 12 weeks, inflammatory mediators in the synovial fluid and histological changes of the cartilage were determined, and immunohistological staining was performed.

RESULTS

The in vitro studies revealed a significant additional or synergistic effect of blood exposure on trauma-induced chondrocyte death, interleukin (IL)-1β and prostaglandin-E2 (PGE2) release, and matrix metalloproteinase (MMP)/pro-MMP level. Singular arthrotomy in vivo induced a temporary inflammation. Histologically, cartilage trauma caused significant OA changes that were not aggravated by an additional hemarthrosis. Trauma led to a persistent deposition of terminal complement complex (TCC), being enhanced by hemarthrosis. However, trauma-induced formation of osteophytes and arthrotomy-induced elevation of tumor necrosis factor-α release were reduced by hemarthrosis.

CONCLUSION

While blood exposure clearly aggravated trauma-induced OA processes in the in vitro model, a singular blood injection revealed heterogeneous effects in vivo, enhancing TCC deposition but reducing trauma-induced osteophyte formation while the histological score of traumatized cartilage was not further impaired.

CLINICAL RELEVANCE

The results of this study indicate that a singular, limited bleeding event might not exacerbate early trauma-induced cartilage degeneration in joint injuries. An early removal of intra-articular blood may not prevent the final resulting cartilage damage.