Oxidative stress in secondary osteoarthritis: from cartilage destruction to clinical presentation?

Functional β-TCP/MnO2 /PCL artificial periosteum promoting osteogenic differentiation of BMSCs by reducing locally reactive oxygen species level

Segmental bone defects caused by trauma, tumor resection or congenital malformations are often reconstructed with autologous, allogeneic bone grafts or artificial bone materials, of which, about 5% ~ 10% will have delayed healing or even nonunion of fractures. The loss of periosteum and excessive accumulation of ROS in fracture site leads to the aging of osteoblasts and the decline of their proliferation and differentiation, thus affecting the fracture healing process. In this study, we prepared a functional modified artificial periosteum β-TCP/MnO2 /PCL(β-TMP) by electrospinning with a function of catalyzing decomposition of H2 O2 . We examined the surface morphology of β-TMP, the concentration of Ca, P and Mn of β-TMP, as well as the diameter distribution range of nanofibers on β-TMP. Through X-ray diffraction patterns and Fourier transform infrared spectra, β-TMP was characterized and its hydrophilicity was tested. The release of Mn2+ and Ca2+ of 0.1 and 0.05% β-TMP in different pH values (7.4 and 5.5) determined by ICP. We also identified that β-TMP could reduce the level of ROS in cells by lowering the level of H2 O2 . 0%, 0.05% and 0.1% β-TMP displayed good cell compatibility, cell adhesion and cellular morphology in the condition with or without H2 O2 . 0.5% β-TMP showed compromised cell compatibility in normal condition, however, the compromised phenotypes could be partially rescued in the present of H2 O2 . Compared with 0%, 0.05% and 0.1% β-TMP displayed higher osteoblastic differentiation with or without H2 O2 in BMSCs as well as in MG-63. In sum, β-TMP helped osteogenesis and promoted repair of bone defects.

The effects of dietary patterns and food groups on symptomatic osteoarthritis: A systematic review

AIM

To systematically review current literature to determine the association between symptomatic osteoarthritis and dietary patterns, diet quality and food groups in adults aged ≥45 years.

METHODS

The review was registered on PROSPERO (CRD42021270891). Cochrane Central Library, Cumulative Index of Nursing and Allied Health Literature, Embase, Medline and Web of Science databases were searched. A total of 3816 records were identified. Eligible articles involved populations aged ≥45 years with symptomatic osteoarthritis, assessing dietary patterns, diet quality or food groups, with pain in joints as outcomes. The Joanna Briggs Institute Critical Appraisal Checklists were used for quality assessment. Grading of Recommendations, Assessment, Development and Evaluation was used to assess the certainty of evidence.

RESULTS

Six cohort studies were included. The Prudent dietary pattern and the Mediterranean dietary pattern reduced the progression of osteoarthritis symptoms. The Western dietary pattern increased symptomatic osteoarthritis progression. Increased total fibre consumption reduced symptomatic osteoarthritis progression and pain worsening, but the effects of fibre from each food group were inconclusive. Diet with high inflammatory potential increased risk of new onset symptomatic osteoarthritis, but the effects of overall diet quality were inconclusive.

CONCLUSIONS

The Prudent dietary pattern showed the highest protection on symptomatic osteoarthritis in adults aged 45 years and over. The body of evidence is limited, suggesting that further research is needed to corroborate the estimated effect at a high certainty of evidence, and to incorporate previously unstudied dietary patterns and food groups. Identifying the most beneficial dietary pattern may inform future guidelines for reducing symptomatic osteoarthritis in middle aged and older adults.

Sex-specific effects of calving season on joint health and biomarkers in Montana ranchers

BACKGROUND

Agricultural workers have a higher incidence of osteoarthritis (OA), but the etiology behind this phenomenon is unclear. Calving season, which occurs in mid- to late-winter for ranchers, includes physical conditions that may elevate OA risk. Our primary aim was to determine whether OA biomarkers are elevated at the peak of calving season compared to pre-season, and to compare these data with joint health survey information from the subjects. Our secondary aim was to detect biomarker differences between male and female ranchers.

METHODS

During collection periods before and during calving season, male (n = 28) and female (n = 10) ranchers completed joint health surveys and provided samples of blood, urine, and saliva for biomarker analysis. Statistical analyses examined associations between mean biomarker levels and survey predictors. Ensemble cluster analysis identified groups having unique biomarker profiles.

RESULTS

The number of calvings performed by each rancher positively correlated with plasma IL-6, serum hyaluronic acid (HA) and urinary CTX-I. Thiobarbituric acid reactive substances (TBARS), a marker of oxidative stress, was significantly higher during calving season than pre-season and was also correlated with ranchers having more months per year of joint pain. We found evidence of sexual dimorphism in the biomarkers among the ranchers, with leptin being elevated and matrix metalloproteinase-3 diminished in female ranchers. The opposite was detected in males. WOMAC score was positively associated with multiple biomarkers: IL-6, IL-2, HA, leptin, C2C, asymmetric dimethylarginine, and CTX-I. These biomarkers represent enzymatic degradation, inflammation, products of joint destruction, and OA severity.

CONCLUSIONS

The positive association between number of calvings performed by each rancher (workload) and both inflammatory and joint tissue catabolism biomarkers establishes that calving season is a risk factor for OA in Montana ranchers. Consistent with the literature, we found important sex differences in OA biomarkers, with female ranchers showing elevated leptin, whereas males showed elevated MMP-3.

Ginkgolide C slows the progression of osteoarthritis by activating Nrf2/HO-1 and blocking the NF-κB pathway

Osteoarthritis (OA) is driven by chronic low-grade inflammation and subsequent cartilage degradation. OA is the most prevalent degenerative joint disease worldwide, and its treatment remains a challenge. The aim of this study was to explore the potential effects and mechanism underlying the anti-OA properties of ginkgolide C (GC). Protective effects of GC on hydrogen peroxide (H2O2)-treated rat chondrocytes were evaluated using ELISA, qPCR, western blot analysis, flow cytometry, ROS detection and immunofluorescence in vitro. Ameliorating effects of GC on cartilage degeneration in rats were evaluated through behavioral assays, microcomputed tomography, histopathological analysis, western blot analysis and ELISA in vivo. In vitro, GC treatment inhibited the release of pro-apoptotic factors induced by H2O2 and promoted the release of the anti-apoptotic proteins. In addition, GC decreased the expression of matrix metalloproteinase (MMP3 and MMP13), thrombospondin motifs 4 (ADAMTS4), and inflammatory mediators inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), and SOX9 thereby inhibiting extracellular matrix (ECM) degradation. Mechanistically, GC exerts its anti-apoptotic and anti-inflammatory effects by upregulating the oxidative stress signaling Nrf2/HO-1 pathway and preventing p65 from binding to DNA. Similarly, In a rat model with post-traumatic OA (PTOA) induced by anterior cruciate ligament transection (ACLT), GC inhibited joint pain, cartilage destruction, and abnormal bone remodeling of subchondral bone. GC inhibited H2O2-induced chondrocyte apoptosis through Nrf2/HO-1 and NF-κB axis, exerted anti-inflammatory effects, and inhibited cartilage degeneration in rat OA. Our findings advanced the concept that GC may contribute to cartilage metabolism through anti-inflammatory and anti-apoptotic effects, and the identified GC is a potential therapeutic agent for the treatment of OA.

Omaveloxolone inhibits IL-1β-induced chondrocyte apoptosis through the Nrf2/ARE and NF-κB signalling pathways in vitro and attenuates osteoarthritis in vivo

Osteoarthritis (OA) is a common degenerative joint disease. Effective drugs that can halt or decelerate osteoarthritis progression are still lacking. Omaveloxolone is a semisynthetic oleanane triterpenoid exerting antioxidative and anti-inflammatory effects. The present study aims to determine whether omaveloxolone has a therapeutic effect on OA. Chondrocytes were treated with interleukin (IL)-1β to establish an OA cell model in vitro. Indicators of cell viability, oxidative stress, inflammation, cell apoptosis and extracellular matrix (ECM) degradation were investigated. Proteins related to the Nuclear factor erythroid derived-2-related factor 2 (Nrf2)/antioxidant response element (ARE) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signalling pathways were assessed using Western blotting. A destabilized medial meniscus surgery-induced OA rat model was used in vivo. Gait analysis, microcomputed tomography analysis, and histopathological and immunohistochemical analyses were performed to determine the therapeutic effect of omaveloxolone on attenuating osteoarthritis in vivo. The results showed that omaveloxolone exerts antioxidative, anti-inflammatory, antiapoptotic and anti-ECM degradation effects via activation of the Nrf2/ARE signalling pathway and inhibition of the NF-κB signalling pathway in chondrocytes in vitro and attenuates OA progression in vivo, suggesting that omaveloxolone may be a potential therapeutic agent for OA.

Characterization of Non-Invasively Induced Post-Traumatic Osteoarthritis in Mice

The pathophysiology of post-traumatic arthritis (PTOA) is not fully understood. This study used non-invasive repetitive mechanical loading (ML) mouse models to study biochemical, biomechanical, and pain-related behavioral changes induced in mice. Mouse models reflected the effects of the early stages of PTOA in humans. For the PTOA model, cyclic comprehensive loading (9N) was applied to each mouse’s left knee joint. ML-induced biochemical and molecular changes were analyzed after loading completion. Cartilage samples were examined using gene expression analysis. Tissue sections were used in subsequent OA severity scoring. Biomechanical features and pain-related behavior were studied after 24 h and three weeks post-ML sessions to examine the development of PTOA. The loaded left knee joint showed a greater ROS/RNS signal than the right knee, which was not loaded. There was a significant increase in cartilage damage and MMP activity in the mechanically loaded joints relative to non-loaded control knee joints. Similarly, we found a difference in the viscoelastic tangent, which highlights significant changes in mechanical properties. Biochemical analyses revealed significant increases in total NO, caspase-3 activity, H₂O₂, and PGE2 levels. Gene expression analysis highlighted increased catabolism (MMP-13, IL-1β, TNF-α) with a concomitant decrease in anabolism (ACAN, COL2A1). Histopathology scores clearly indicated increases in OA progression and synovitis. The gait pattern was significantly altered, suggesting signs of joint damage. This study showed that biomechanical, biochemical, and behavioral characteristics of the murine PTOA groups are significantly different from the control group. These results confirm that the current mouse model can be considered for translational PTOA studies.

Zwitterionic polymer modified xanthan gum with collagen II-binding capability for lubrication improvement and ROS scavenging

High friction of damaged cartilage requires long-acting lubricated additive, which can also effectively scavenge reactive oxidative species (ROS) produced by mechanically stimulated chondrocytes. In this study, xanthan gum (XG) was grafted by poly (sulfobetaine methacrylate) (PSBMA) (the [XG]/[SBMA] molar ratio is 1:5 or 1:10), forming nanoparticles and then conjugated with collagen II-binding peptide, finally obtaining CBPXGSB1/5 or CBPXGSB1/10. Therein, the CBPXGSB1/5 was chosen as optimal lubricated additive. The results show that hydrated effect of PSBMA side chains endows CBPXGSB1/5 with favorable lubrication property (COF is 0.063). Furthermore, the CBPXGSB1/5 combining lubrication property and specific binding capability together may achieve the long-acting lubrication for injured cartilage in medical field. The CBPXGSB1/5 also possesses antioxidation verified by DPPH assay and exhibits synergistically enhanced ROS (OH, O₂^- and H₂O₂) scavenging. Besides, cytotoxicity experiment demonstrates that CBPXGSB1/5 has good biocompatibility. Therefore, multifunctional CBPXGSB1/5 developed here may have promising application potential in osteoarthritis treatment.

Differential regulation of the water channel protein aquaporins in chondrocytes of human knee articular cartilage by aging

Knee cartilage is in an aqueous environment filled with synovial fluid consisting of water, various nutrients, and ions to maintain chondrocyte homeostasis. Aquaporins (AQPs) are water channel proteins that play an important role in water exchange in cells, and AQP1, -3, and -4 are known to be expressed predominantly in cartilage. We evaluated the changes in AQP expression in chondrocytes from human knee articular cartilage in patients of different ages and identified the key factor(s) that mediate age-induced alteration in AQP expression. The mRNA and protein expression of AQP1, -3 and -4 were significantly decreased in fibrocartilage compared to hyaline cartilage and in articular cartilage from older osteoarthritis patients compared to that from young patients. Gene and protein expression of AQP1, -3 and -4 were altered during the chondrogenic differentiation of C3H10T1/2 cells. The causative factors for age-associated decrease in AQP included H₂O₂, TNFα, and HMGB1 for AQP1, -3, and -4, respectively. In particular, the protective effect of AQP4 reduction following HMGB1 neutralization was noteworthy. The identification of other potent molecules that regulate AQP expression represents a promising therapeutic approach to suppress cartilage degeneration during aging.

Hyaluronan as a Prominent Biomolecule with Numerous Applications in Medicine

Hyaluronan (HA) is a natural glycosaminoglycan present in many tissues of all vertebrates. HA has various biological functions, which are dependent on its molar mass. High-molar-mass HA has anti-angiogenic, immunosuppressive and anti-inflammatory properties, while low-molar-mass HA has opposite effects. HA has also antioxidative properties, however on the other hand it can be readily degraded by reactive oxygen species. For many years it has been used in treatment of osteoarthritis, cosmetics and in ophthalmology. In the last years there has been a growing interest of HA to also be applied in other fields of medicine such as skin wound healing, tissue engineering, dentistry and gene delivery. In this review we summarize information on modes of HA administration, properties and effects of HA in various fields of medicine including recent progress in the investigation of HA.

Plantamajoside Ameliorates Inflammatory Response of Chondrocytes via Regulating NF-κB/NLRP3 Inflammasome Pathway

The damage of articular cartilage in osteoarthritis involves the oxidative stress and inflammation. The aim of the present study was to explore the role of plantamajoside (PM) in chondrocytes and elucidate the underlying mechanism. The cell viability following treatment with PM or lipopolysac-charide (LPS) was assessed by cell counting kit-8 (CCK-8). Enzyme-Linked Immunosorbent Assay (ELISA) was supplied to determine the levels of pro-inflammatory cytokines. Moreover, the oxidative stress-related markers were evaluated via assay kits. TUNEL assay was employed to stain the apoptotic cells. The components of nuclear factor-κB (NF-κB) pathway and NLRP3 inflammasome were estimated by western blot analysis. LPS-insulted cell viability of ATDC5 was restored by PM. PM alleviated the inflammatory response and oxidative stress of ATDC5 cells induced by LPS. Furthermore, it was found that the apoptotic cells were reduced following PM treatment. The protein levels of NF-κB, IκB kinase β (IKKβ) and NLRP3 inflammasome were decreased by PM. These results suggested that PM protected the ATDC5 cells from LPS stimulation, alleviated the inflammatory response may through regulating the NF-κB and NLRP3 inflammasome.

Dopamine/Phosphorylcholine Copolymer as an Efficient Joint Lubricant and ROS Scavenger for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic joint disease and its progression and pathogenesis are highly associated with the significant increase of joint friction and overproduction of reactive oxygen species (ROS) in inflammation. Combination of ROS elimination and lubrication enhancement may provide a novel strategy for the treatment of OA. In the present study, a pure biomaterial and nondrug system P(DMA-co-MPC), synthesized via free radical copolymerization, was designed and developed for the first time using 2-methacryloxyethyl phosphorylcholine (MPC) as a bioinspired lubricant and N-(3,4-dihydroxyphenethyl)methacrylamide (DMA) as an ROS scavenger. Our results showed that the P(DMA-co-MPC) aggregates could efficiently eliminate the ROS radicals and provide good lubrication property by adjusting the molar ratio of DMA and MPC in the copolymer. It is attributed to the antioxidant function of the hydroquinone moiety in DMA and the hydration lubrication effect of the zwitterionic phosphocholine group in MPC. Furthermore, the in vitro experiments demonstrated that the P(DMA-co-MPC) showed good biocompatibility with MC3T3-E1 cells and intracellular anti-inflammatory property by inhibiting the production of ROS and regulating the expression levels of pro-inflammatory cytokines, pain-related gene, anabolic genes, and catabolic genes. In conclusion, the drug-free P(DMA-co-MPC) aggregates developed herein can achieve dual functions of lubrication enhancement and anti-inflammatory effect and thus they may be representative as promising candidates for the treatment of OA.

Antioxidant additives reduce reactive oxygen species production in articular cartilage during exposure to cryoprotective agents

High concentrations of cryoprotective agents (CPA) are required during articular cartilage cryopreservation but these CPAs can be toxic to chondrocytes. Reactive oxygen species have been linked to cell death due to oxidative stress. Addition of antioxidants has shown beneficial effects on chondrocyte survival and functions after cryopreservation. The objectives of this study were to investigate (1) oxidative stress experienced by chondrocytes and (2) the effect of antioxidants on cellular reactive oxygen species production during articular cartilage exposure to high concentrations of CPAs. Porcine cartilage dowels were exposed to a multi-CPA solution supplemented with either 0.1 mg/mL chondroitin sulfate or 2000 μM ascorbic acid, at 4 °C for 180 min (N = 7). Reactive oxygen species production was measured with 5 μM dihydroethidium, a fluorescent probe that targets reactive oxygen species. The cell viability was quantified with a dual cell membrane integrity stain containing 6.25 μM Syto 13 + 9 μM propidium iodide using confocal microscopy. Supplementation of CPA solutions with chondroitin sulfate or ascorbic acid resulted in significantly lower dihydroethidium counts (p < 0.01), and a lower decrease in the percentage of viable cells (p < 0.01) compared to the CPA-treated group without additives. These results indicated that reactive oxygen species production is induced when articular cartilage is exposed to high CPA concentrations, and correlated with the amount of dead cells. Both chondroitin sulfate and ascorbic acid treatments significantly reduced reactive oxygen species production and improved chondrocyte viability when articular cartilage was exposed to high concentrations of CPAs.

The value of serum total oxidant to the antioxidant ratio as a biomarker of knee osteoarthritis

BACKGROUND & AIMS

The balance between oxidants and antioxidants is known as oxidative balance, which is impaired in many disease conditions such as osteoarthritis (OA). In this study, we aimed to evaluate this balance in OA patients through the evaluation of the oxidant to the antioxidant ratio.

MATERIALS AND METHODS

A total of 62 knee OA patients and 20 age, sex, and BMI-matched healthy controls were included in this cross-sectional study. Serum total oxidant status (TOS) and total antioxidant capacity (TAC) were evaluated using the oxidation-reduction colorimetric assay. The TOS to TAC ratio (TOS/TAC) was evaluated as an estimate of the oxidant to antioxidant balance.

RESULTS

The mean TOS was 14.2 ± 2 μM in the healthy controls and 23.3 ± 7 μM in the OA patients (p < 0.001). The mean TAC was 38.8 ± 6.6 μM in the healthy subjects and 35.8 ± 12 μM in the OA patients (p = 0.33). The mean TOS/TAC was 0.38 ± 0.09 in the healthy subjects and 0.72 ± 0.3 in the OA patients (p < 0.0001). TOS/TAC value was capable of distinguishing OA patients from healthy controls with the sensitivity and specificity of 87.1% and 80%, respectively (p < 0.001). At the cutoff value of 0.46, positive TOS/TAC (>0.46) was identified in 100% of grade I patients, whereas it was negative in 27.3%, 16.7%, and 16.7% of grades II, III, and IV, respectively (p = 0.039).

CONCLUSION

In the knee OA, an equation of the serum TOS to TAC could be a good representative of oxidative balance than each component individually.

p66shc siRNA Nanoparticles Ameliorate Chondrocytic Mitochondrial Dysfunction in Osteoarthritis

Background

Osteoarthritis (OA) is the most common type of joint disease associated with cartilage breakdown. However, the role played by mitochondrial dysfunction in OA remains inadequately understood. Therefore, we investigated the role played by p66shc during oxidative damage and mitochondrial dysfunction in OA and the effects of p66shc downregulation on OA progression.

Methods

Monosodium iodoacetate (MIA), which is commonly used to generate OA animal models, inhibits glycolysis and biosynthetic processes in chondrocytes, eventually causing cell death. To observe the effects of MIA and poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles, histological analysis, immunohistochemistry, micro-CT, mechanical paw withdrawal thresholds, quantitative PCR, and measurement of oxygen consumption rate and extracellular acidification rate were conducted.

Results

p-p66shc was highly expressed in cartilage from OA patients and rats with MIA-induced OA. MIA caused mitochondrial dysfunction and reactive oxygen species (ROS) production, and the inhibition of p66shc phosphorylation attenuated MIA-induced ROS production in human chondrocytes. Inhibition of p66shc by PLGA-based nanoparticles-delivered siRNA ameliorated pain behavior, cartilage damage, and inflammatory cytokine production in the knee joints of MIA-induced OA rats.

Conclusion

p66shc is involved in cartilage degeneration in OA. By delivering p66shc-siRNA-loaded nanoparticles into the knee joints with OA, mitochondrial dysfunction-induced cartilage damage can be significantly decreased. Thus, p66shc siRNA PLGA nanoparticles may be a promising option for the treatment of OA.

Novel anti-inflammatory and chondroprotective effects of the human melanocortin MC1 receptor agonist BMS-470539 dihydrochloride and human melanocortin MC3 receptor agonist PG-990 on lipopolysaccharide activated chondrocytes

Human melanocortin MC1 and MC3 receptors expressed on C-20/A4 chondrocytes exhibit chondroprotective and anti-inflammatory effects when activated by melanocortin peptides. Nearly 9 million people in the UK suffer from osteoarthritis, and bacterial infections play a role in its development. Here, we evaluate the effect of a panel of melanocortin peptides with different selectivity for human melanocortin MC1 (α-MSH, BMS-470539 dihydrochloride) and MC3 ([DTrp⁸]-γ-MSH, PG-990) receptors and C-terminal peptide α-MSH_11-13(KPV), on inhibiting LPS-induced chondrocyte death, pro-inflammatory mediators and induction of anti-inflammatory proteins. C-20/A4 chondrocytes were treated with a panel of melanocortin peptides prophylactically and therapeutically in presence of LPS (0.1 μg/ml). The chondroprotective properties of these peptides determined by cell viability assay, RT-PCR, ELISA for detection of changes in inflammatory markers (IL-6, IL-8 and MMP-1, -3 and -13) and western blotting for expression of the anti-inflammatory protein heme-oxygenase-1. C-20/A4 expressed human melanocortin MC1 and MC3 receptors and melanocortin peptides elevated cAMP. LPS stimulation caused a reduction in C-20/A4 viability, attenuated by the human melanocortin MC1 receptor agonist BMS-470539 dihydrochloride, and MC3 receptor agonists PG-990 and [DTrp⁸]-γ-MSH. Prophylactic and therapeutic regimes of [DTrp⁸]-γ-MSH significantly inhibited LPS-induced modulation of cartilage-damaging IL-6, IL-8, MMPs -1,-3 and -13 mediators both prophylactically and therapeutically, whilst human melanocortin MC1 and MC3 receptor agonists promoted an increase in HO-1 production. In the presence of LPS, activation of human melanocortin MC1 and MC3 receptors provided potent chondroprotection, upregulation of anti-inflammatory proteins and downregulation of inflammatory and proteolytic mediators involved in cartilage degradation, suggesting a new avenue for osteoarthritis treatment.

Evaluation of plasma trace elements and oxidant/antioxidant status in Boerboel dogs with hip dysplasia

Changes in plasma concentrations of trace elements and oxidants/antioxidants were evaluated in twenty healthy Boerboels of both sexes and median age of 2 years. Antero-posterior and flexed lateral radiographs of the hip were obtained using digital x-ray machine and hip grading was done according to Fédération Cynologique Internationale (FCI) system. Blood was collected from the cephalic vein for determination of plasma concentrations of manganese (Mn), magnesium (Mg), copper (Cu), cobalt (Co), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPX) and Vitamin E. Correlation between the parameters was done using Pearson’s correlation. Eleven (11/20) of the Boerboel dogs had hip dysplasia (HD), comprising five (5/9) males and six (6/11) females. Plasma Mn, Cu and Co were insignificantly higher in Boerboels with normal hips than those with HD. MDA concentration was significantly (p<0.05) lower in Boerboels with normal hips (0.75 ± 0.84 µmol/L) than in dogs with HD (1.77 ± 0.78 µmol/L), while SOD was significantly (p<0.05) higher in Boerboels with normal hips (0.65 ± 0.22 U/ml) than with HD (0.32 ± 0.16 U/ml). It was concluded that there were differences in plasma oxidants/antioxidants between Boerboel dogs with normal hips and those with hip dysplasia suggesting their role in the pathogenesis of canine hip dysplasia

Osteoarthritis from evolutionary and mechanistic perspectives

Developmental osteogenesis and the pathologies associated with tissues that normally are mineralized are active areas of research. All of the basic cell types of skeletal tissue evolved in early aquatic vertebrates. Their characteristics, transcription factors, and signaling pathways have been conserved, even as they adapted to the challenge imposed by gravity in the transition to terrestrial existence. The response to excess mechanical stress (among other factors) can be expressed in the pathologic phenotype described as osteoarthritis (OA). OA is mediated by epigenetic modification of the same conserved developmental gene networks, rather than by gene mutations or new chemical signaling pathways. Thus, these responses have their evolutionary roots in morphogenesis. Epigenetic channeling and heterochrony, orchestrated primarily by microRNAs, maintain the sequence of these responses, while allowing variation in their timing that depends at least partly on the life history of the individual.

Multifaceted Protective Role of Glucosamine against Osteoarthritis: Review of Its Molecular Mechanisms

Osteoarthritis (OA) is a joint disease resulting from cartilage degeneration and causing joint pain and stiffness. Glucosamine exerts chondroprotective effects and effectively reduces OA pain and stiffness. This review aims to summarise the mechanism of glucosamine in protecting joint health and preventing OA by conducting a literature search on original articles. Current evidence has revealed that glucosamine exhibits anti-inflammatory effects by reducing the levels of pro-inflammatory factors (such as tumour necrosis factor-alpha, interleukin-1, and interleukin-6) and enhancing the synthesis of proteoglycans that retard cartilage degradation and improve joint function. Additionally, glucosamine improves cellular redox status, reduces OA-mediated oxidative damages, scavenges free radicals, upregulates antioxidant proteins and enzyme levels, inhibits the production of reactive oxygen species, and induces autophagy to delay OA pathogenesis. In conclusion, glucosamine prevents OA and maintains joint health by reducing inflammation, improving the redox status, and inducing autophagy in joints. Further studies are warranted to determine the synergistic effect of glucosamine with other anti-inflammatory and/or antioxidative agents on joint health in humans.

PROOXIDANT ACTIVITIES OF ANTIOXIDANTS AND THEIR IMPACT ON HEALTH

This review article is focused on the impact of antioxidants and prooxidants on health with emphasis on the type of antioxidants that should be taken. Medical researchers suggest that diet may be the solution for the control of chronic diseases such as cardiovascular complications, hypertension, diabetes mellitus, and different cancers. In this survey, we found scientific evidence that the use of antioxidants should be limited only to the cases where oxidative stress has been identified. This is often the case of specific population groups such as postmenopausal women, the elderly, infants, workers exposed to environmental pollutants, and the obese. Before starting any supplementation, it is necessary to measure oxidative stress and to identify and eliminate the possible sources of free radicals and thus increased oxidative stress.

Evidence of necroptosis in osteoarthritic disease: investigation of blunt mechanical impact as possible trigger in regulated necrosis

Joint injuries are highly associated with cell death and development of posttraumatic osteoarthritis (PTOA). The present study focused on necroptosis as a possible modality of chondrocyte death after cartilage trauma and its relevance in OA disease in general. For this purpose, apoptosis- and necroptosis-associated markers were determined in highly degenerated (ICRS ≥ 3) as well as macroscopically intact cartilage tissue (ICRS ≤ 1) by means of real-time PCR and immunohistochemistry (IHC). Moreover, influence of blunt trauma and/or stimulation with cycloheximide (CHX), TNF-a, and caspase-inhibitor zVAD were investigated in cartilage explants (ICRS ≤ 1). Further characterization of necroptosis was performed in isolated chondrocytes. We found that gene expression levels of RIPK3 (4.2-fold, P < 0.0001) and MLKL (2.7-fold, P < 0.0001) were elevated in highly degenerated cartilage tissue, which was confirmed by IHC staining. After ex vivo trauma and/or CHX/TNF stimulation, addition of zVAD further enhanced expression of necroptosis-related markers as well as release of PGE2 and nitric oxide, which was in line with increased cell death and subsequent release of intracellular HMGB1 and dsDNA in CHX/TNF stimulated chondrocytes. However, trauma and/or chemically induced cell death and subsequent release of pro-inflammatory mediators could be largely attenuated by RIPK1-inhibitor necrostatin 1 or antioxidant N-acetylcysteine. Overall, the study provided clear evidence of necroptotic cell death in OA disease. Moreover, a possible link between cartilage injury and necroptotic processes was found, depending on oxidative stress and cytokine release. These results contribute to further understanding of cell death in PTOA and development of novel therapeutic approaches.

Relationship between oxidative balance score and quality of life in patients with osteoarthritis: Data from the Korea National Health and Nutrition Examination Survey (2014-2015)

Osteoarthritis (OA) has a multifactorial etiology that includes oxidative stress. Oxidative balance score (OBS) is a well-known indicator of oxidative stress. However, the association between OBS and OA has not been assessed. Thus, this study aimed to investigate the associations of OBS with OA and quality of life (QOL) in patients with OA.By using data from the Korea National Health and Nutrition Examination Survey VI, patients previously diagnosed and/or treated by a physician were considered to have OA regardless of the affected joints. The control group was defined as participants without any form of chronic arthritis. OBS was calculated by combining 10 pro-oxidant and antioxidant factors through a baseline nutritional and lifestyle assessment. Higher OBS scores indicated a predominance of antioxidant exposure. Multivariable logistic regression was used to estimate the adjusted odds ratios (ORs) for OA, and the EuroQoL five-dimensional questionnaire (EQ5D) was used in patients with OA after adjusting for demographic factors and comorbidities.Among the 14,930 participants, 296 patients with OA, and 1,309 controls were included in the analysis. In the age- and sex-adjusted model, the OR of the total OBS for OA was significant. In the full model adjusted for age, sex, education, income, and comorbidities, the total OBS for OA was not significant. Only the non-dietary pro-oxidant OBS had a significant inverse association with OA. The patients with OA who had a high EQ5D score had a higher total OBS than those with a low EQ5D score. The OR of the total OBS for a high EQ5D score was 1.14 in the multivariable logistic regression model. As we analyzed the OBS as a categorical variable (reference = Q1), the ORs of the Q2, Q3, and Q4 (highest) total OBS were 1.43, 2.71, and 2.22, respectively.In the fully adjusted model, the total OBS was not associated with OA. However, a positive association was observed between the total OBS and QOL in the patients with OA, indicating that antioxidative status was associated with better QOL in patients with OA.

Comparative study of the effect of Thymus daenensis gel 5% and diclofenac in patients with knee osteoarthritis

Background: Osteoarthritis is a syndrome characterized by joint pain and reduced performance and efficien- cy in patient. Thymus daenensis has been used since old times for the treatment of bone and joint deformities and pain in traditional medicine.

Purpose: This study was conducted to examine traditional usages and pharmacological features of T. daen- ensis with respect to the effect of the plant in patients with osteoarthritis.

Methods: 120 patients with osteoarthritis were divided into 3 groups. Patients in each group were treated by 5% Thymus daenensis gel, 1% diclofenac gel, or placebo for 6 weeks, along with oral celecoxib capsules. Patients were assessed in different intervals, based on the VAS score for assessment of pain in the joint and different dimensions of WOMAC questionnaire.

Results: Pain level (P < 0.005), stiffness during the day (P < 0.05), morning stiffness (P < 0.05) and physi- cal performance (P < 0.05) were significantly different among the groups.

Conclusions: Thymus daenensis gel improves the symptoms in patients equal and without significant difference than diclofenac group. It can be argued that its use can produce a satisfactory effect on patients with osteoarthritis due to its low cost, easy access, the plant’s natively occurring in Iran.

lncRNA-CIR regulates cell apoptosis of chondrocytes in osteoarthritis

BACKGROUND AND OBJECTIVES

Osteoarthritis (OA) is a complex chronic degenerative joint disease involving oxidative stress, inflammation, and apoptosis of chondrocytes. As decoys of micro RNAs, long non-coding RNAs (lncRNAs) play important roles in various biological processes. This study was designed to investigate the interactions between lncRNA-CIR, chondrocyte apoptosis, and the molecular mechanisms underlying OA.

METHODS

Primary cultured chondrocytes were stressed using H₂ O₂ , IL-1β, or TNF-ɑ to simulate conditions found in OA. Quantitative real-time PCR was performed to detect miR-130a, lncRNA-CIR, and Bim mRNA expression levels. Western blot analysis was used to detect Bim protein expression levels. Reactive oxygen species (ROS) levels were assayed by detecting the fluorescent signal of 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). Cell apoptosis was measured with combined staining of PI and DAPI. lncRNA-CIR knockdown and miR-130a over-expression or inhibition were performed using small interfering RNAs, and miR-130 mimics or inhibitors, respectively.

RESULTS

lncRNA-CIR is significantly upregulated in OA patients, accompanied by downregulation of miR-130a and upregulation of Bim. Bio-informatics analysis predicted miR-130a as a target of both lncRNA-CIR and Bim. While lncRNA-CIR knockdown significantly increased the expression of Bim, miR-130a significantly suppressed Bim expression, with accompanying increases of ROS level, inflammatory mediator release, cell apoptosis, and relative luciferase activity.

CONCLUSIONS

The present findings demonstrated that the lncRNA-CIR/miR-130a/Bim axis is involved in oxidative stress-related apoptosis of chondrocytes in OA.

Superoxide dismutase 3 facilitates the chondrogenesis of bone marrow-derived mesenchymal stem cells

Articular cartilage defects are considered a major clinical problem because they cannot heal by themselves. To date, bone marrow-derived mesenchymal stem cells (BMSCs)-based therapy has been widely applied for cartilage repair. However, fibrocartilage was often generated after BMSC therapy; therefore, there is an urgent need to stimulate and maintain BMSCs chondrogenic differentiation. The specific role of superoxide dismutase 3 (SOD3) in chondrogenesis is unknown; therefore, the present study aimed to clarify whether SOD3 could facilitate the chondrogenic differentiation of BMSCs. We first evaluated SOD3 protein levels during chondrogenesis of BMSCs using plate cultures. We then tested whether SOD3 could facilitate chondrogenesis of BMSCs using knockdown or overexpression experiments. Increased SOD3 protein levels were observed during BMSCs chondrogenesis. SOD3 knockdown inhibited collagen type II alpha 1 chain (COL2A1), aggrecan (ACAN), and SRY-box 9 (SOX9) expression. Overexpression of SOD3 increased the levels of chondrogenesis markers (COL2A1, ACAN, and SOX9). Elevated superoxide anions were observed when SOD3 was knocked down. We concluded that SOD3 could facilitate chondrogenesis of BMSCs to improve cartilage regeneration.

Evaluation of monosodium iodoacetate dosage to induce knee osteoarthritis: Relation with oxidative stress and pain

AIM

To determine the dose of monosodium iodoacetate (MIA) required to induce oxidative stress, as well as pain and edema; to confirm the induction of knee osteoarthritis (OA) symptoms in rats by the presence of reactive oxygen species (ROS) and reduction of antioxidant agents; and to verify the presence of histopathological injury in these affected joints.

METHOD

Biological markers of oxidative stress, pain, knee edema, and cartilage degeneration provided by different doses of MIA (0.5; 1.0 or 1.5 mg) in rat knee joints were analyzed. The animal evaluations were conducted during 15 days for mechanical and cold hypersensitivity, spontaneous pain and edema. After that, blood serum, intra-articular lavage and structures of knee, spinal cord and brainstem were collected for biochemical analysis; moreover, the knees were removed for histological evaluation.

RESULTS

This study demonstrates that the highest dose of MIA (1.5 mg) increased the oxidative stress markers and reduced the antioxidant reactions, both in the focus of the lesion and in distant sites. MIA also induced the inflammatory process, characterized by pain, edema, increase in neutrophil count and articular damage.

CONCLUSION

This model provides a basis for the exploration of underlying mechanisms in OA and the identification of mechanisms that may guide therapy and the discovery of OA signals and symptoms.

Hydrostatic pressure-generated reactive oxygen species induce osteoarthritic conditions in cartilage pellet cultures

Osteoarthritis (OA) is one of the most common causes of disability and represents a major socio-economic burden. Despite intensive research, the molecular mechanisms responsible for the initiation and progression of OA remain inconclusive. In recent years experimental findings revealed elevated levels of reactive oxygen species (ROS) as a major factor contributing to the onset and progression of OA. Hence, we designed a hydrostatic pressure bioreactor system that is capable of stimulating cartilage cell cultures with elevated ROS levels. Increased ROS levels in the media did not only lead to an inhibition of glycosaminoglycans and collagen II formation but also to a reduction of already formed glycosaminoglycans and collagen II in chondrogenic mesenchymal stem cell pellet cultures. These effects were associated with the elevated activity of matrix metalloproteinases as well as the increased expression of several inflammatory cytokines. ROS activated different signaling pathways including PI3K/Akt and MAPK/ERK which are known to be involved in OA initiation and progression. Utilizing the presented bioreactor system, an OA in vitro model based on the generation of ROS was developed that enables the further investigation of ROS effects on cartilage degradation but can also be used as a versatile tool for anti-oxidative drug testing.

Epigenetic enzymes influenced by oxidative stress and hypoxia mimetic in osteoblasts are differentially expressed in patients with osteoporosis and osteoarthritis

Epigenetic mechanisms including posttranslational histone modifications and DNA methylation are emerging as important determinants of bone homeostasis. With our case-control study we aimed to identify which chromatin-modifying enzymes could be involved in the pathology of postmenopausal osteoporosis and osteoarthritis while co-regulated by estrogens, oxidative stress and hypoxia. Gene expression of HAT1, KAT5, HDAC6, MBD1 and DNMT3A affected by oxidative stress and hypoxia in an in vitro qPCR screening step performed on an osteoblast cell line was analysed in trabecular bone tissue samples from 96 patients. Their expression was significantly reduced in patients with postmenopausal osteoporosis and osteoarthritis as compared to autopsy controls and significantly correlated with bone mineral density and several bone histomorphometry-derived parameters of bone quality and quantity as well as indicators of oxidative stress, RANK/RANKL/OPG system and angiogenesis. Furthermore, oxidative stress increased DNA methylation levels at the RANKL and OPG promoters while decreasing histone acetylation levels at these two genes. Our study is the first to show that higher expression of HAT1, HDAC6 and MBD1 is associated with superior quantity as well as quality of the bone tissue having a more favourable trabecular structure.

Evidence for Transient Receptor Potential (TRP) Channel Contribution to Arthritis Pain and Pathogenesis

Based on clinical and preclinical evidence, Transient Receptor Potential (TRP) channels have emerged as potential drug targets for the treatment of osteoarthritis, rheumatoid arthritis, and gout. This review summarizes the relevant data supporting a role for various TRP channels in arthritis pain and pathogenesis, as well as the current state of pharmacological efforts to ameliorate arthritis symptoms in patient populations.

Does Obesity Explain the Effect of the Metabolic Syndrome on Complications Following Elective Lumbar Fusion? A Propensity Score Matched Analysis

STUDY DESIGN

Propensity score matched retrospective cohort study.

OBJECTIVES

Obesity is a major confounder in determining the independent effect of metabolic syndrome (MetS) on complications after spinal surgery. The purpose of this study is to differentiate MetS from obesity as an independent influence on perioperative outcomes after elective lumbar spine fusion.

METHODS

One- to 3-level posterior spinal fusion cases were identified from the 2011-2014 American College of Surgeons' National Surgical Quality Improvement Program. To determine the effects of MetS outside of obesity itself, patients with MetS were first compared to a no-MetS cohort and then to an obese-only no-MetS cohort. Two propensity score matches based on demographics, comorbidities, surgical complexity, and diagnosis were used to match patients in 1:1 ratios and compare outcomes. Logistic regression with propensity score adjustment was further utilized as a secondary method of reducing selection bias.

RESULTS

Out of 18 605 patients that met criteria for inclusion, 1903 (10.2%) met our definition of MetS. Patients with MetS had a higher rate of wound complications (3.8% vs 2.7% obese no MetS, P = .045; vs 2.6% no MetS, P = .035), readmissions (7.4% vs 2.2% obese no MetS, P < .001; vs 4.6% no MetS, P < .001), and extended length of stay (29.1% vs 23.9% obese no MetS, P < .001; vs 23.5% no MetS, P < .001). Patients with MetS were more likely to experience a wound complication (odds ratio = 1.47, 95% confidence interval = 1.02-2.12) or readmission (odds ratio = 1.48, 95% confidence interval = 1.22-1.80).

CONCLUSIONS

Even after controlling for obesity, MetS is an independent risk factor for adverse short-term outcomes. These findings have various implications for preoperative risk stratification and reduction strategies.

Sargassum serratifolium Extract Attenuates Interleukin-1β-Induced Oxidative Stress and Inflammatory Response in Chondrocytes by Suppressing the Activation of NF-κB, p38 MAPK, and PI3K/Akt

Osteoarthritis (OA) is a degenerative joint disease that is characterized by irreversible articular cartilage destruction by inflammatory reaction. Among inflammatory stimuli, interleukin-1β (IL-1β) is known to play a crucial role in OA pathogenesis by stimulating several mediators that contribute to cartilage degradation. Recently, the marine brown alga Sargassum serratifolium has been reported to exhibit antioxidant and anti-inflammatory effects in microglial and human umbilical vein endothelial cell models using lipopolysaccharide and tumor necrosis factor-α, but its beneficial effects on OA have not been investigated. This study aimed to evaluate the anti-osteoarthritic effects of ethanol extract of S. serratifolium (EESS) in SW1353 human chondrocytes and, in parallel, primary rat articular chondrocytes. Our results showed that EESS effectively blocked the generation of reactive oxygen species in IL-1β-treated SW1353 and rat primary chondrocytes, indicating that EESS has a potent antioxidant activity. EESS also attenuated IL-1β-induced production of nitric oxide (NO) and prostaglandin E₂, major inflammatory mediators in these cells, which was associated with the inhibition of inducible NO synthase and cyclooxygenase-2 expression. Moreover, EESS downregulated the level of gene expression of matrix metalloproteinase (MMP)-1, -3 and -13 in SW1353 chondrocytes treated with IL-1β, resulting in their extracellular secretion reduction. In addition, the IL-1β-induced activation of nuclear factor-kappa B (NF-κB) was restored by EESS. Furthermore, EESS reduced the activation of p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathways upon IL-1β stimulation. These results indicate that EESS has the potential to exhibit antioxidant and anti-inflammatory effects through inactivation of the NF-κB, p38 MAPK, and PI3K/Akt signaling pathways. Collectively, these findings demonstrate that EESS may have the potential for chondroprotection, and extracts of S. serratifolium could potentially be used in the prevention and treatment of OA.

α-Lipoic Acid Potentiates the Anti-Inflammatory Activity of Avocado/Soybean Unsaponifiables in Chondrocyte Cultures

Objective Pro-inflammatory mediators such as prostaglandin E-2 (PGE₂) play major roles in the pathogenesis of osteoarthritis (OA). Although current pharmacologic treatments reduce inflammation, their prolonged use is associated with deleterious side effects prompting the search for safer and effective alternative strategies. The present study evaluated whether chondrocyte production of PGE₂ can be suppressed by the combination of avocado/soybean unsaponifiables (ASU) and α-lipoic acid (LA). Design Chondrocytes from articular cartilage of equine joints were incubated for 24 hours with: (1) control media, (2) ASU, (3) LA, or (4) ASU + LA combination. Cells were activated with lipopolysaccharide (LPS), interleukin 1β (IL-1β) or hydrogen peroxide (H₂O₂) for 24 hours and supernatants were immunoassayed for PGE₂. Nuclear factor-kappa B (NF-κB) analyses were performed by immunocytochemistry and Western blot following 1 hour of activation with IL-1β. Results LPS, IL-1β, or H₂O₂ significantly increased PGE₂ production. ASU or LA alone suppressed PGE₂ production in LPS and IL-1β activated cells. Only LA alone at 2.5 µg/mL was inhibitory in H₂O₂-activated chondrocytes. ASU + LA inhibited more than either agent alone in all activated cells. ASU + LA also inhibited the IL-1β induced nuclear translocation of NF-κB. Conclusions The present study provides evidence that chondrocyte PGE₂ production can be inhibited by the combination of ASU + LA more effectively than either ASU or LA alone. Inhibition of PGE₂ production is associated with the suppression of NF-κB translocation. The potent inhibitory effect of ASU + LA on PGE₂ production could offer a potential advantage for a combination anti-inflammatory/antioxidant approach in the management of OA.

Drug-Free ROS Sponge Polymeric Microspheres Reduce Tissue Damage from Ischemic and Mechanical Injury

The inherent antioxidant function of poly(propylene sulfide) (PPS) microspheres (MS) was dissected for different reactive oxygen species (ROS), and therapeutic benefits of PPS-MS were explored in models of diabetic peripheral arterial disease (PAD) and mechanically induced post-traumatic osteoarthritis (PTOA). PPS-MS (∼1 μm diameter) significantly scavenged hydrogen peroxide (H2O2), hypochlorite, and peroxynitrite but not superoxide in vitro in cell-free and cell-based assays. Elevated ROS levels (specifically H2O2) were confirmed in both a mouse model of diabetic PAD and in a mouse model of PTOA, with greater than 5- and 2-fold increases in H2O2, respectively. PPS-MS treatment functionally improved recovery from hind limb ischemia based on ∼15-25% increases in hemoglobin saturation and perfusion in the footpads as well as earlier remodeling of vessels in the proximal limb. In the PTOA model, PPS-MS reduced matrix metalloproteinase (MMP) activity by 30% and mitigated the resultant articular cartilage damage. These results suggest that local delivery of PPS-MS at sites of injury-induced inflammation improves the vascular response to ischemic injury in the setting of chronic hyperglycemia and reduces articular cartilage destruction following joint trauma. These results motivate further exploration of PPS as a stand-alone, locally sustained antioxidant therapy and as a material for microsphere-based, sustained local drug delivery to inflamed tissues at risk of ROS damage.

Spinacia oleracea extract attenuates disease progression and sub-chondral bone changes in monosodium iodoacetate-induced osteoarthritis in rats

Background

Spinacia oleracea is an important dietary vegetable in India and throughout the world and has many beneficial effects. It is cultivated globally. However, its effect on osteoarthritis that mainly targets the cartilage cells remains unknown. In this study we aimed to evaluate the anti-osteoarthritic and chondro-protective effects of SOE on chemically induced osteoarthritis (OA).

Methods

OA was induced by intra-patellar injection of monosodium iodoacetate (MIA) at the knee joint in rats. SOE was then given orally at 250 and 500 mg.kg^− 1 day^− 1 doses for 28 days to these rats. Anti-osteoarthritic potential of SOE was evaluated by micro-CT, mRNA and protein expression of pro-inflammatory and chondrogenic genes, clinically relevant biomarker’s and behavioural experiments.

Results

In vitro cell free and cell based assays indicated that SOE acts as a strong anti-oxidant and an anti-inflammatory agent. Histological analysis of knee joints at the end of the experiment by safranin-o and toluidine blue staining established its protective effect. Radiological data corroborated the findings with improvement in the joint space and irregularity of the articular and atrophied femoral condyles and tibial plateau. Micro-CT analysis of sub-chondral bone indicated that SOE had the ability to mitigate OA effects by increasing bone volume to tissue volume (BV/TV) which resulted in decrease of trabecular pattern factor (Tb.Pf) by more than 200%. SOE stimulated chondrogenic marker gene expression with reduction in pro-inflammatory markers. Purified compounds isolated from SOE exhibited increased Sox-9 and Col-II protein expression in articular chondrocytes. Serum and urine analysis indicated that SOE had the potential to down-regulate glutathione S-transferase (GST) activity, clinical markers of osteoarthritis like cartilage oligometric matrix protein (COMP) and CTX-II. Overall, this led to a significant improvement in locomotion and balancing activity in rats as assessed by Open-field and Rota rod test.

Conclusion

On the basis of in vitro and in vivo experiments performed with Spinacea oleracea extract we can deduce that SOE has the ability to alleviate the MIA induced deleterious effects.

Electronic supplementary material

The online version of this article (10.1186/s12906-018-2117-9) contains supplementary material, which is available to authorized users.

Nrf2/ARE pathway attenuates oxidative and apoptotic response in human osteoarthritis chondrocytes by activating ERK1/2/ELK1-P70S6K-P90RSK signaling axis

Nrf2, a redox regulated transcription factor, has recently been shown to play a role in cartilage integrity but the mechanism remains largely unknown. Osteoarthritis (OA) is a multifactorial disease in which focal degradation of cartilage occurs. Here, we studied whether Nrf2 exerts chondroprotective effects by suppressing the oxidative stress and apoptosis in IL-1β stimulated human OA chondrocytes. Expression of Nrf2 and its target genes HO-1, NQO1 and SOD2 was significantly high in OA cartilage compared to normal cartilage and was also higher in damaged area compared to smooth area of OA cartilage of the same patient. Human chondrocytes treated with IL-1β resulted in robust Nrf2/ARE reporter activity, which was inhibited by pretreatment with antioxidants indicating that Nrf2 activity was due to IL-1β-induced ROS generation. Ectopic expression of Nrf2 significantly suppressed the IL-1β-induced generation of ROS while Nrf2 knockdown significantly increased the basal as well as IL-1β-induced ROS levels in OA chondrocytes. Further, Nrf2 activation significantly inhibited the IL-1β-induced activation of extrinsic and intrinsic apoptotic pathways as determined by inhibition of DNA fragmentation, activation of Caspase-3,-8,-9, cleavage of PARP, release of cytochrome-c, suppression of mitochondrial dysfunction and mitochondrial ROS production in OA chondrocytes. Nrf2 over-expression in OA chondrocytes increased the expression of anti-apoptotic proteins while pro-apoptotic proteins were suppressed. Importantly, Nrf2 over-expression activated ERK1/2 and its downstream targets-ELK1, P70S6K and P90RSK and suppressed the IL-1β-induced apoptosis whereas inhibition of ERK1/2 activation abrogated the protective effects of Nrf2 in OA chondrocytes. Taken together, our data demonstrate that Nrf2 is a stress response protein in OA chondrocytes with anti-oxidative and anti-apoptotic function and acts via activation of ERK1/2/ELK1-P70S6K-P90RSK signaling axis. These activities of Nrf2 make it a promising candidate for the development of novel therapies for the management of OA.

Sargassum serratifolium attenuates RANKL-induced osteoclast differentiation and oxidative stress through inhibition of NF-κB and activation of the Nrf2/HO-1 signaling pathway

Sargassum serratifolium C. Agardh is a marine brown alga that has long been used as an ingredient for food and medicine by many people living along Asian coastlines. Recently, various beneficial effects of extracts or compounds isolated from S. serratifolium have been reported, but their efficacies against bone destruction are unclear. Therefore, in this study, we investigated the inhibitory property of an ethanol extract of S. serratifolium (EESS) on osteoclast differentiation by focusing on the receptor activator of nuclear factor-κB ligand (RANKL)-stimulated osteoclastogenesis model using RAW 264.7 macrophages. Our results demonstrated that EESS reduced RANKL-induced osteoclast differentiation in RAW 264.7 cells, by inhibiting tartrate-resistant acid phosphatase (TRAP) activity and destroying the F-actin ring formation. EESS also attenuated RANKL-induced expressions of key osteoclast-specific genes, such as nuclear factor of activated T cells cytoplasmic 1 (NFATC1), TRAP, cathepsin K and matrix metalloproteinase-9. These effects were mediated by impaired nuclear translocation of nuclear factor (NF)-κB and suppression of IκB-α degradation. In addition, EESS effectively inhibited the production of reactive oxygen species (ROS) by RANKL, which was associated with enhanced expression of nuclear translocation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Overall, our findings provide evidence that EESS suppresses RANKL-induced osteoclastogenesis and oxidative stress through suppression of NF-κB and activation of Nrf2/HO-1 signaling pathway, indicating that S. serratifolium has a potential application the prevention and treatment of osteoclastogenic bone disease.

Myrtol improves post-traumatic knee osteoarthritis by regulation of reactive oxygen species, transforming growth factor β1 and apoptosis in a mouse model

The present study tested whether myrtol improves post-traumatic knee osteoarthritis (PTKO) by regulating the reactive oxygen species (ROS), transforming growth factor β1 (TGF-β1) and apoptosis in a mouse model. PTKO model mice were administered with 150, 300 or 450 mg/kg myrtol for 8 weeks. ELISA analysis was used to measure tumor necrosis factor-α, interleukin-6, malondialdehyde, superoxide dismutase, reactive oxygen species and TGF-β1 levels. Caspase-3 and Bax protein expressions were analyzed using western blot analysis. In the current study, treatment with myrtol improved the tissue damage and osteoarthritis score, while it also reversed the subchondral bone thickness, subchondral bone density, trabecular bone volume/relative trabecular bone volume ratio and trabecular bone spacing in PTKO mice. The activity of tumor necrosis factor α, interleukin-6, TGF-β1, malondialdehyde, superoxide dismutase and ROS were effectively inhibited, and the protein expression of caspase-3 and Bax were clearly suppressed by treatment with myrtol in a mouse model of PTKO. In conclusion, the results demonstrated that myrtol treatment improved PTKO through the suppression of inflammation, oxidative stress, ROS, TGF-β1 and Bax/caspase-3 in mice, and myrtol may be a potential agent for clinical therapy.

Oxidative stress, consequences and ROS mediated cellular signaling in rheumatoid arthritis

There are numerous extra- and intra-cellular processes involved in the production of reactive oxygen species (ROS). Augmented ROS generation can cause the damage of biomolecules such as proteins, nucleic acid and lipids. ROS act as an intracellular signaling component and is associated with various inflammatory responses, chronic arthropathies, including rheumatoid arthritis (RA). It is well documented that ROS can activate different signaling pathways having a vital importance in the patho-physiology of RA. Hence, understanding of the molecular pathways and their interaction might be advantageous in the development of novel therapeutic approaches for RA.

The role of Mediterranean diet and its components on the progress of osteoarthritis

Osteoarthritis is the most common, incurable joint disease. The rapid pace of the disease has adverse consequences in the quality of patient's life, while affecting healthcare systems. The research interest is focused on cost-effective and without side-effects methods to reduce the symptoms and improve the quality of life. Several dietary factors have been linked to the health of cartilage tissue, inflammatory processes and the progress of osteoarthritis. Mediterranean diet (MD) is a dietary pattern that was adopted by people living around the Mediterranean sea. This term first appeared in 1950, by Ancel Keys. It's characterized by high consumption of vegetables, unprocessed grains, fruits, legumes, seeds, modest consumption of fish and poultry and olive oil is the principal fat source. Emerged data emphasize the beneficial effects of MD against chronic inflammation, metabolic complications and chronic diseases. There are few studies investigating the effect of MD against osteoarthritis, but apparent evidence is encouraging, this highlights the need for further research of the relationship between MD and osteoarthritis. The purpose of this work is a literature review between the effect of MD and its components and the progress of osteoarthritis.

Striking a new path in reducing cartilage breakdown: combination of antioxidative therapy and chondroanabolic stimulation after blunt cartilage trauma

Cartilage injury can trigger crucial pathomechanisms, including excessive cell death and expression of matrix‐destructive enzymes, which contribute to the progression of a post‐traumatic osteoarthritis (PTOA). With the intent to create a novel treatment strategy for alleviating trauma‐induced cartilage damage, we complemented a promising antioxidative approach based on cell and chondroprotective N‐acetyl cysteine (NAC) by chondroanabolic stimulation. Overall, three potential pro‐anabolic growth factors – IGF‐1, BMP7 and FGF18 – were tested comparatively with and without NAC in an ex vivo human cartilage trauma‐model. For that purpose, full‐thickness cartilage explants were subjected to a defined impact (0.59 J) and subsequently treated with the substances. Efficacy of the therapeutic approaches was evaluated by cell viability, as well as various catabolic and anabolic biomarkers, representing the present matrix turnover. Although monotherapy with NAC, FGF18 or BMP7 significantly prevented trauma‐induced cell dead and breakdown of type II collagen, combination of NAC and one of the growth factors did not yield significant benefit as compared to NAC alone. IGF‐1, which possessed only moderate cell protective and no chondroprotective qualities after cartilage trauma, even reduced NAC‐mediated cell and chondroprotection. Despite significant promotion of type II collagen expression by IGF‐1 and BMP7, addition of NAC completely suppressed this chondroanabolic effect. All in all, NAC and BMP7 emerged as best combination. As our findings indicate limited benefits of the simultaneous multidirectional therapy, a sequential application might circumvent adverse interferences, such as suppression of type II collagen biosynthesis, which was found to be reversed 7 days after NAC withdrawal.

An overview of the role of lipid peroxidation-derived 4-hydroxynonenal in osteoarthritis

BACKGROUND

Over the years, many theories have been proposed and examined to better explain the etiology and development of osteoarthritis (OA). The characteristics of joint destruction are one of the most important aspects in disease progression. Therefore, investigating different factors and signaling pathways involved in the alteration of extracellular matrix (ECM) turnover, and the subsequent catabolic damage to cartilage holds chief importance in understanding OA development. Among these factors, reactive oxygen species (ROS) have been at the forefront of the physiological and pathophysiological OA investigation.

FINDINGS

In the last decades, research studies provided an enormous volume of data supporting the involvement of ROS in OA. Most interestingly, published data regarding the effect of exogenous antioxidant therapy in OA lack conclusive results from clinical trials to back up in vitro data. Accordingly, it is rational to suggest that there are other reactive species in OA that are not taken into account. Thus, our present review is focused on our current understanding of the involvement of lipid peroxidation-derived 4-hydroxynonenal (HNE) in OA.

CONCLUSION

Our findings, like those in the literature, illustrate the central role played by HNE in the regulation of a number of factors involved in joint homeostasis. HNE could thus be considered as an attractive therapeutic target in OA.

Adherence to a Mediterranean diet is associated with lower prevalence of osteoarthritis: Data from the osteoarthritis initiative

BACKGROUND & AIMS

The Mediterranean diet appears to be beneficial for several medical conditions, but data regarding osteoarthritis (OA) are not available. The aim of this study was to investigate if adherence to the Mediterranean diet is associated with a lower prevalence of OA of the knee in a large cohort from North America.

METHODS

4358 community-dwelling participants (2527 females; mean age: 61.2 years) from the Osteoarthritis Initiative were included. Adherence to the Mediterranean diet was evaluated through a validated Mediterranean diet score (aMED) categorized into quartiles (Q). Knee OA was diagnosed both clinically and radiologically. The strength of the association between aMED (divided in quartiles) and knee OA was investigated through a logistic regression analysis and reported as odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for potential confounders.

RESULTS

Participants with a higher adherence to Mediterranean diet had a significantly lower prevalence of knee OA compared to those with lower adherence (Q4: 25.2% vs. Q1: 33.8%; p < 0.0001). Using a logistic regression analysis, adjusting for 10 potential confounders with those in the lowest quartile of aMED as reference, participants with the highest aMED had a significant reduction in presence of knee OA (OR, 0.83; 95% CIs: 0.69-0.99, p = 0.04). Among the individual components of Mediterranean diet, only higher use of cereals was associated with lower odds of having knee OA (OR: 0.76; 95%CI: 0.60-0.98; p = 0.03).

CONCLUSIONS

Higher adherence to a Mediterranean diet is associated with lower prevalence of knee OA. This remained when adjusting for potential confounders.

Lysophosphatidylcholines to phosphatidylcholines ratio predicts advanced knee osteoarthritis

OBJECTIVE

To identify novel biomarker(s) for predicting advanced knee OA.

METHODS

Study participants were derived from the Newfoundland Osteoarthritis Study and the Tasmania Older Adult Cohort Study. All knee OA cases were patients who underwent total knee replacement (TKR) due to primary OA. Metabolic profiling was performed on fasting plasma. Four thousand and eighteen plasma metabolite ratios that were highly correlated with that in SF in our previous study were generated as surrogates for joint metabolism.

RESULTS

The discovery cohort included 64 TKR cases and 45 controls and the replication cohorts included a cross-sectional cohort of 72 TKR cases and 76 controls and a longitudinal cohort of 158 subjects, of whom 36 underwent TKR during the 10-year follow-up period. We confirmed the previously reported association of the branched chain amino acids to histidine ratio with advanced knee OA (P = 9.3 × 10(-7)) and identified a novel metabolic marker-the lysophosphatidylcholines (lysoPCs) to phosphatidylcholines (PCs) ratio-that was associated with advanced knee OA (P = 1.5 × 10(-7)) after adjustment for age, sex and BMI. When the subjects of the longitudinal cohort were categorized into two groups based on the optimal cut-off of the ratio of 0.09, we found the subjects with the ratio ⩾0.09 were 2.3 times more likely to undergo TKR than those with the ratio <0.09 during the 10-year follow-up (95% CI: 1.2, 4.3, P = 0.02).

CONCLUSION

We identified the ratio of lysoPCs to PCs as a novel metabolic marker for predicting advanced knee OA. Further studies are required to examine whether this ratio can predict early OA change.

Increased arterial stiffness in patients with end-stage osteoarthritis: a case-control study

BACKGROUND

Both osteoarthritis (OA) and cardiovascular diseases (CVD) are prevalent conditions which often co-exist. Vascular involvement in the pathogenesis of these diseases, as well as increased cardiovascular risk in OA patients give occasion to investigate arterial stiffness in OA. The aim of this study was to establish associations between OA and arterial stiffness.

METHODS

The characteristics of arterial stiffness were measured with Sphygmocor and HDI devices in 48 patients (age 63 ± 7 years (mean ± SD)) with end-stage OA awaiting knee and hip replacement and in 49 age and gender matched controls (61 ± 7 years). Independent Student's t-test or the Mann-Whitney U test was used to compare means between the groups. Correlation between variables was determined using Pearson's or Spearman's correlation analysis and stepwise multiple regression analysis.

RESULTS

Carotid-femoral pulse wave velocity (car-fem PWV) was increased in the patients with OA compared to the controls (9.6 ± 2.4 and 8.4 ± 1.9 m/s, p = 0.015 respectively). High-sensitivity C-reactive protein and white blood cells count were significantly higher in the OA patients compared with the controls (1.80 ± 1.10 and 1.48 ± 1.32 mg/l, p = 0.042; 6.5 ± 1.5 and 5.6 ± 1.9 10(9)/l, p = 0.001 respectively). In multiple regression analysis age (p < 0.001), mean arterial blood pressure (p = <0.001) and OA status (p = 0.029) were found to be independent predictors of car-fem PWV.

CONCLUSIONS

This study showed that patients with OA had increased aortic stiffness compared to non-OA controls. The potential link between arterial stiffening and OA suggests that vascular alterations are involved in OA pathogenesis and could be responsible for increased cardiovascular risk in end-stage OA patients.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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