Oxidative stress and inflammation in osteoarthritis pathogenesis: Role of polyphenols

Intra-Articular Injection of Rebamipide-Loaded Nanoparticles Attenuate Disease Progression and Joint Destruction in Osteoarthritis Rat Model: A Pilot Study

OBJECTIVE

Rebamipide has antioxidant effects and is a drug with a local rather than systemic mechanism of action. Oxidative stress and inflammation in chondrocytes are the major factors contributing to the development and progression of osteoarthritis (OA). Since OA is mainly developed in weight bearing or overused joints, the locally sustained therapy is effective for targeting inflammatory component of OA. We investigated the effects of intra-articular injection of rebamipide loaded nanoparticles (NPs) in OA rat model.

DESIGN

We fabricated rebamipide-loaded methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (mPEG-PDLLA) and poly(D, L-lactide-co-glycolide) (PLGA) NPs that allow the sustained release of rebamipide. In vitro, chondrocytes from rat were used to investigate the cytotoxicity and anti-inflammatory effect of rebamipide-loaded NPs. In vivo, monosodium iodoacetate (MIA)-induced OA rats were divided into 7 groups, consisting of healthy control rats and rats injected with MIA alone or in combination with NPs, rebamipide (1 mg)/NPs, rebamipide (10 mg)/NPs, rebamipide (10 mg) solution, or oral administration.

RESULTS

In vitro, rebamipide/NPs dose-dependently suppressed the mRNA levels of pro-inflammatory mediators, including interleukin (IL)-1β, IL-6, tumor necrosis factor-α, matrix metalloproteinase (MMP)-3, MMP-13, and cyclo-oxygenase-2. In vivo, the mRNA levels of pro-inflammatory components most markedly decreased in the intra-articularly injected rebamipide (10 mg)/NP group compared to other groups. Macroscopic, radiographic, and histological evaluations showed that the intra-articular injection of rebamipide/NPs inhibited cartilage degeneration more than rebamipide solution or rebamipide administration.

CONCLUSIONS

Using a chemically induced rat model of OA, intra-articular delivery of rebamipide was associated with decreased local and systemic inflammatory response decreased joint degradation and arthritic progression.

Do Pomegranate Hydrolyzable Tannins and Their Derived Metabolites Provide Relief in Osteoarthritis? Findings from a Scoping Review

Osteoarthritis (OA) is the most common form of arthritis affecting both the elderly and the middle-aged population. Although various therapeutics have been developed to arrest the structural deterioration of cartilage, the current treatments are limited to delay the progress of OA clinically. Therefore, it is pivotal to study new therapeutic agents for chondroprotection and the prevention of cartilage degeneration. Hydrolyzable tannin (HT)-containing foods aroused considerable interest in recent years for their relevant anti-inflammatory effects. The focus of this scoping review is to provide an overview of the evidence of the therapeutic potential of HTs and their metabolites in preventing or alleviating the course of OA. A broad search of PubMed and Scopus databases on this topic resulted in 156 articles. After the exclusion of reviews and not relevant records, 31 articles were retrieved. Although only some papers did not consider the biotransformation of HTs, most recent studies also have investigated the effect of HT metabolites. Further larger clinical trials, with an in-deep analysis of HT metabolization, are still needed to unravel the potential benefits of these compounds in OA, paving the way towards the development of a dietary strategy for the improvement of pro-inflammatory cytokine-induced chondrocyte dysfunctions and injuries.

ERK1/2-mediated activation of DRP1 regulates mitochondrial dynamics and apoptosis in chondrocytes

OBJECTIVE

To determine the Dynamin-related protein 1 (DRP1) regulation of mitochondrial fission in chondrocytes under pathological conditions, an area which is underexplored in osteoarthritis pathogenesis.

DESIGN

DRP1 protein expression was determined by immunohistochemistry (IHC) or immunofluorescence (IF) staining of cartilage sections. IL-1β-induced DRP1 mRNA expression in chondrocytes was quantified by qPCR and protein expression by immunoblotting. Mitochondrial fragmentation in chondrocytes was visualized by MitoTracker staining or IF staining of mitochondrial marker proteins or by transient expression of mitoDsRed. Mitochondrial reactive oxygen species (ROS) levels were determined by MitoSOX staining. Apoptosis was determined by lactate dehydrogenase (LDH) release assay, Caspase 3/7 activity assay, propidium iodide (PI), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining and IF staining of cleaved caspase 3. Cytochrome c release was determined by confocal microscopy. Surgical destabilization of the medial meniscus (DMM) was used to induce osteoarthritis (OA) in mice.

RESULTS

Expression of DRP1 and mitochondrial damage was high in human OA cartilage and in the joints of mice subjected to DMM surgery which also showed increased chondrocytes apoptosis. IL-1β-induced mitochondrial network fragmentation and chondrocyte apoptosis via modulation of DRP1 expression and activity and induce apoptosis via Bax-mediated release of Cytochrome c. Pharmacological inhibition of DRP1 activity by Mdivi-1 blocked IL-1β-induced mitochondrial damage and apoptosis in chondrocytes. Additionally, IL-1β-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) is crucial for DRP1 activation and induction of mitochondrial network fragmentation in chondrocytes as these were blocked by inhibiting ERK1/2 activation.

CONCLUSIONS

These findings demonstrate that ERK1/2 is a critical player in DRP1-mediated induction of mitochondrial fission and apoptosis in IL-1β-stimulated chondrocytes.

Timosaponin B-II alleviates osteoarthritis-related inflammation and extracellular matrix degradation through inhibition of mitogen-activated protein kinases and nuclear factor-κB pathways in vitro

Osteoarthritis (OA), an inflammatory response in chondrocytes, leads to extracellular matrix (ECM) degradation and cartilage destruction. Timosaponin B-II (TB-II) is the main bioactive component of Rhizoma Anemarrhenae with reported antioxidant and anti-inflammatory effects. This study investigated the anti-OA function and mechanism of TB-II on IL-1β-stimulated SW1353 cells and primary rat chondrocytes. We firstly screened the concentration of TB-II in SW1353 cells and primary rat chondrocytes using CCK-8 assay. Thereafter, SW1353 cells and chondrocytes were, respectively, pretreated with TB-II (20 and 40 μg/mL) and TB-II (10 and 30 μg/mL) for 24 h and then stimulated with interleukin 1β (IL-1β, 10 ng/mL) for another 24 hours. Results showed that TB-II suppressed the production of reactive oxygen species, the protein levels of inducible nitric oxide synthase and cyclooxygenase-2 in IL-1β-stimulated SW1353 cells and chondrocytes. IL-1β-induced high secretion levels of nitric oxide and prostaglandin 2, TNF-α, IL-6 and MCP-1 were down-regulated by TB-II treatment, indicating an anti-inflammatory effect of TB-II on OA in vitro condition. Moreover, TB-II weakened the mRNA and protein expression of (matrix metalloproteinase) MMPs including MMP-1, MMP-3, and MMP-13, indicating the protection of TB-II against ECM degradation. Mechanically, TB-II suppressed MAPKs and NF-κB pathways under IL-1β stimulation evidenced by the down-regulated protein expression of p-ERK, p-p38, p-JNK, p-p65 and the reduced translocation of p65 subunit to the nucleus. The present study demonstrated that TB-II might become a novel therapeutic agent for OA treatment through repressing IL-1β-stimulated inflammation, oxidative stress and ECM degradation via suppressing the MAPKs and NF-κB pathways.

Systematic review of the effects of pomegranate (Punica granatum) on osteoarthritis

Background: Considering limitations of the established osteoarthritis (OA) medications, attention to adjuvant and complementary treatments has increased in OA individuals. Recent investigations have reported advantages of pomegranate in OA and indicate that pomegranate can be a therapeutic option; nevertheless, no systematic review exists regarding OA and pomegranate. Therefore, we systematically studied accessible researches regarding pomegranate and OA in human, animal, and in vitro models and likely mechanistic pathways. Methods: Present systematic review study was recorded on the international prospective register of systematic reviews database. Electronic databases (Scopus, PubMed, Embase, WOS, ProQuest) and search engine Google Scholar were searched until February 2021. Search alerts were turned on to recognize papers published following the primary search. Two investigators independently searched using MESH and non-MESH words in title, abstract, and keywords. Inclusion criteria were related clinical, animal, and in vitro studies published in any language as a full text. Exclusion criteria were reviews, book chapters, conference abstracts, and articles regarding pomegranate in health problems other than OA. Hand searching was used to check the references or citations of eligible papers and grey literature (theses etc.) to find potential researches. Results: Twenty-three articles were included in our systematic review. Human, animal, and in vitro researches demonstrated favorable properties of pomegranate in improving clinical features and reducing inflammatory, oxidative stress, and apoptosis markers in OA. Conclusion: Present paper provides convincing evidence about the efficacy of pomegranate in OA and gives a justification for the importance of additional clinical studies.

Advances in Engineered Three-Dimensional (3D) Body Articulation Unit Models

Indeed, the body articulation units, commonly referred to as body joints, play significant roles in the musculoskeletal system, enabling body flexibility. Nevertheless, these articulation units suffer from several pathological conditions, such as osteoarthritis (OA), rheumatoid arthritis (RA), ankylosing spondylitis, gout, and psoriatic arthritis. There exist several treatment modalities based on the utilization of anti-inflammatory and analgesic drugs, which can reduce or control the pathophysiological symptoms. Despite the success, these treatment modalities suffer from major shortcomings of enormous cost and poor recovery, limiting their applicability and requiring promising strategies. To address these limitations, several engineering strategies have been emerged as promising solutions in fabricating the body articulation as unit models towards local articulation repair for tissue regeneration and high-throughput screening for drug development. In this article, we present challenges related to the selection of biomaterials (natural and synthetic sources), construction of 3D articulation models (scaffold-free, scaffold-based, and organ-on-a-chip), architectural designs (microfluidics, bioprinting, electrospinning, and biomineralization), and the type of culture conditions (growth factors and active peptides). Then, we emphasize the applicability of these articulation units for emerging biomedical applications of drug screening and tissue repair/regeneration. In conclusion, we put forward the challenges and difficulties for the further clinical application of the in vitro 3D articulation unit models in terms of the long-term high activity of the models.

Emodin Attenuates the ECM Degradation and Oxidative Stress of Chondrocytes through the Nrf2/NQO1/HO-1 Pathway to Ameliorate Rat Osteoarthritis

Osteoarthritis (OA) substantially reduces the quality of life of the elderly. OA therapy remains a challenge since no treatment options for its causes are so far available. Over recent years, researchers have speculated that emodin may represent a potential treatment strategy for OA. However, it remains unclear whether the mechanism of action of emodin is associated with the inhibition of OA-induced oxidative stress. In the present study, the potential antioxidant mechanism of action of emodin and its protective properties against the development of OA were investigated both in vitro and in vivo. In vitro, emodin inhibited the production of reactive oxygen species (ROS) in chondrocytes induced by hydrogen peroxide (H2O2) and reduced the expression of matrix metalloproteinase (MMP)3 and MMP13 in a concentration-dependent manner. It was found that emodin upregulated the Nrf2/NQO1/HO-1 pathway, thereby attenuating the effects of oxidative stress caused by OA. In a rat model of posttraumatic OA induced by anterior cruciate ligament transection (ACLT), emodin reduced the extent of joint swelling. Emodin attenuated oxidative damage in the cartilage by upregulating superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) activity, reducing malondialdehyde (MDA) concentration and inhibiting the expression of the extracellular matrix (ECM) degradation biomarkers cartilage oligomeric matrix protein (COMP), and C-terminal telopeptide of type I collagen (CTX-I) and type II collagen (CTX-II), thereby reducing cartilage damage. In summary, the present study indicates that emodin reduces ECM degradation and oxidative stress in chondrocytes via the Nrf2/NQO1/HO-1 pathway, thereby ameliorating OA in rats.

An anti-inflammatory diet intervention for knee osteoarthritis: a feasibility study

BACKGROUND

Knee osteoarthritis has an inflammatory component that is linked to pain and joint pathology, yet common non-surgical and non-pharmacological interventions (e.g., exercise, calorie restricting diets) do not typically target inflammation. We aimed to evaluate the feasibility of a telehealth delivered anti-inflammatory diet intervention for knee osteoarthritis.

METHODS

This 9-week single-arm feasibility study recruited participants aged 40-85 years with symptomatic knee osteoarthritis (inclusion criteria: average pain ≥4/10 or maximal pain ≥5/10 during past week). All participants received a telehealth-delivered anti-inflammatory dietary education intervention involving 1:1 consultations at baseline, 3- and 6-week follow-up. The diet emphasised nutrient-dense wholefoods and minimally processed anti-inflammatory foods and discouraged processed foods considered to be pro-inflammatory. The primary outcome of feasibility was assessed via: i) eligibility, recruitment and retention rates; ii) self-reported dietary adherence; iii) adverse events; and iv) treatment satisfaction. Post-intervention interviews evaluated the acceptability of the dietary intervention delivered via telehealth. Secondary outcomes included changes in self-reported body mass, Knee injury and Osteoarthritis Outcome Score (KOOS), health-related quality of life (EuroQoL-5D), analgesic use and global rating of change. Worthwhile effects were determined by the minimal detectable change (MDC) for all five KOOS-subscales (pain, symptoms, activities of daily living, sport/recreation, quality of life) being contained within the 95% confidence interval.

RESULTS

Forty-eight of seventy-three (66%) individuals screened were eligible and 28 enrolled over 2 months (82% female, mean age 66 ± 8 years, body mass index 30.7 ± 4.8 kg.m-2). Six participants withdrew prior to final follow-up (21% drop-out). Of those with final follow-up data, attendance at scheduled telehealth consultations was 99%. Self-reported adherence to diet during the 9-week intervention period: everyday = 27%, most of time = 68% and some of time = 5%. Two minor adverse events were reported. Change scores contained the MDC within the 95% confidence interval for all five KOOS subscales. Suggestions to improve study design and limit drop-out included an initial face-to-face consultation and more comprehensive habitual dietary intake data collection.

CONCLUSION

This study supports the feasibility of a full-scale randomised controlled trial to determine the efficacy of a primarily telehealth-delivered anti-inflammatory dietary education intervention in adults with symptomatic knee osteoarthritis.

TRIAL REGISTRATION

ACTRN12620000229976 prospectively on 25/2/2020.

Melatonin Promotes Antler Growth by Accelerating MT1-Mediated Mesenchymal Cell Differentiation and Inhibiting VEGF-Induced Degeneration of Chondrocytes

The sika deer is one type of seasonal breeding animal, and the growth of its antler is affected by light signals. Melatonin (MLT) is a neuroendocrine hormone synthesized by the pineal gland and plays an important role in controlling the circadian rhythm. Although the MLT/MT1 (melatonin 1A receptor) signal has been identified during antler development, its physiological function remains almost unknown. The role of MLT on antler growth in vivo and in vitro is discussed in this paper. In vivo, MLT implantation was found to significantly increase the weight of antlers. The relative growth rate of antlers showed a remarkable increased trend as well. In vitro, the experiment showed MLT accelerated antler mesenchymal cell differentiation. Further, results revealed that MLT regulated the expression of Collage type II (Col2a) through the MT1 binding mediated transcription of Yes-associated protein 1 (YAP1) in antler mesenchymal cells. In addition, treatment with vascular endothelial growth factor (VEGF) promoted chondrocytes degeneration by downregulating the expression of Col2a and Sox9 (SRY-Box Transcription Factor 9). MLT effectively inhibited VEGF-induced degeneration of antler chondrocytes by inhibiting the Signal transducers and activators of transcription 5/Interleukin-6 (STAT5/IL-6) pathway and activating the AKT/CREB (Cyclin AMP response-element binding protein) pathway dependent on Sox9 expression. Together, our results indicate that MLT plays a vital role in the development of antler cartilage.

The role of fibroblast growth factor 8 in cartilage development and disease

Fibroblast growth factor 8 (FGF‐8), also known as androgen‐induced growth factor (AIGF), is presumed to be a potent mitogenic cytokine that plays important roles in early embryonic development, brain formation and limb development. In the bone environment, FGF‐8 produced or received by chondrocyte precursor cells binds to fibroblast growth factor receptor (FGFR), causing different levels of activation of downstream signalling pathways, such as phospholipase C gamma (PLCγ)/Ca²⁺, RAS/mitogen‐activated protein kinase‐extracellular regulated protein kinases (RAS/MAPK‐MEK‐ERK), and Wnt‐β‐catenin‐Axin2 signalling, and ultimately controlling chondrocyte proliferation, differentiation, cell survival and migration. However, the molecular mechanism of FGF‐8 in normal or pathological cartilage remains unclear, and thus, FGF‐8 represents a novel exploratory target for studies of chondrocyte development and cartilage disease progression. In this review, studies assessing the relationship between FGF‐8 and chondrocytes that have been published in the past 5 years are systematically summarized to determine the probable mechanism and physiological effect of FGF‐8 on chondrocytes. Based on the existing research results, a therapeutic regimen targeting FGF‐8 is proposed to explore the possibility of treating chondrocyte‐related diseases.

Effects and underlying mechanisms of food polyphenols in treating gouty arthritis: A review on nutritional intake and joint health

Gouty arthritis, one of the most severe and common forms of arthritis, is characterized by monosodium urate crystal deposition in joints and surrounding tissues. Epidemiological evidence indicates that gouty arthritis incidence is sharply rising globally. Polyphenols are found in many foods and are secondary metabolites in plant foods. The anti-inflammatory and antioxidant effects of food polyphenols have been extensively studied in many inflammatory chronic diseases. Research has suggested that many food polyphenols have excellent anti-gouty arthritis effects. The mechanisms mainly include (a) inhibiting xanthine oxidase activity; (b) reducing the levels of inflammatory cytokines and chemokines; (c) inhibiting the activation of signaling pathways and the NLRP3 inflammasome; and (d) reducing oxidative stress. This paper reviews the research progress and pathogenesis of gouty arthritis and introduces the mechanisms of food polyphenols in treating gouty arthritis, which aims to explore the potential of functional foods in the treatment of gouty arthritis. PRACTICAL APPLICATIONS: The incidence rate of gouty arthritis has increased sharply worldwide, which has seriously affected people's quality of life. According to the current research progress, food polyphenols alleviate gouty arthritis through anti-inflammatory and antioxidant effects. This paper reviews the research progress and molecular pathogenesis of gouty arthritis and introduces the mechanisms of food-derived polyphenols in the treatment of gouty arthritis, which is helpful to the prevention and treatment of gouty arthritis.

Phytochemicals Mediate Autophagy Against Osteoarthritis by Maintaining Cartilage Homeostasis

Osteoarthritis (OA) is a common degenerative joint disease and is a leading cause of disability and reduced quality of life worldwide. There are currently no clinical treatments that can stop or slow down OA. Drugs have pain-relieving effects, but they do not slow down the course of OA and their long-term use can lead to serious side effects. Therefore, safe and clinically appropriate long-term treatments for OA are urgently needed. Autophagy is an intracellular protective mechanism, and targeting autophagy-related pathways has been found to prevent and treat various diseases. Attenuation of the autophagic pathway has now been found to disrupt cartilage homeostasis and plays an important role in the development of OA. Therefore, modulation of autophagic signaling pathways mediating cartilage homeostasis has been considered as a potential therapeutic option for OA. Phytochemicals are active ingredients from plants that have recently been found to reduce inflammatory factor levels in cartilage as well as attenuate chondrocyte apoptosis by modulating autophagy-related signaling pathways, which are not only widely available but also have the potential to alleviate the symptoms of OA. We reviewed preclinical studies and clinical studies of phytochemicals mediating autophagy to regulate cartilage homeostasis for the treatment of OA. The results suggest that phytochemicals derived from plant extracts can target relevant autophagic pathways as complementary and alternative agents for the treatment of OA if subjected to rigorous clinical trials and pharmacological tests.

Pulsed electromagnetic field alleviates synovitis and inhibits the NLRP3/Caspase-1/GSDMD signaling pathway in osteoarthritis rats

Low-grade inflammation is a key mediator of the pathogenesis of Osteoarthritis (OA). Pulsed electromagnetic field (PEMF) can improve the symptoms of OA and potentially acts as an anti-inflammatory. The aim of this study was to investigate the effect of the PEMF on OA and its relationship with the NLRP3/Caspase-1/GSDMD signaling pathway.18 Three-month-old Sprague-Dawley (SD) rats were randomly divided into three groups (n = 6 per group): 1) OA group, 2) OA+PEMF group (OA with PEMF exposure), 3) Control group (sham operation with placebo PEMF). Rats in the OA and OA+PEMF groups were subjected to bilateral anterior cruciate ligament transection and ovariectomy. PEMF scheme: Pulse waveform, 3.82 mT, 8 Hz, 40 min/day, 5 days a week, for 12 weeks. The expression levels of NLRP3, Caspase-1, GSDMD, IL-1β, and MMP-13 were detected by qRT-PCR and Western blot. The pathological structures of OA were monitored with Safranin O/fast green staining and hematoxylin eosin staining. Our results showed that PEMF alleviated the degree of inflammation and degeneration of cartilage in rats with OA, based on the histopathological changes and decline of the expression of IL-1β and MMP-13. Moreover, the over-expression of NLRP3, Caspase-1, and GSDMD in the cartilage of the OA rats decreased after PEMF treatment. These results suggested that PEMF could be a highly promising noninvasive strategy to slow down the progression of OA and inhibition of the NLRP3/Caspase-1/GSDMD signaling pathway might be involved in the beneficial effect of PEMF.

Radiation-assisted reduction of graphene oxide by aloe vera and ginger and their antioxidant and anti-inflammatory roles against male mice liver injury induced by gamma radiation

A novel approach for graphene oxide reduction using γ-rays in the presence of natural antioxidants is revealed for biomedical applications.

Rhoifolin Loaded in PLGA Nanoparticles Alleviates Oxidative Stress and Inflammation In Vitro and In Vivo

Rhoifolin (ROF) is a bioactive plant flavonoid with potent antioxidant and anti-inflammatory activity. However, no delivery system has yet been developed for ROF to overcome its biopharmaceutical limitations. The purpose...

The protective effects of Olmesartan against interleukin-29 (IL-29)-induced type 2 collagen degradation in human chondrocytes

Osteoarthritis (OA) is a cartilage degenerative disease commonly observed in the elderly population and is pathologically characterized by the degradation of the cartilage extracellular matrix (ECM). Matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTSs) are critical enzymes involved in the degradation of ECM. Olmesartan is an inhibitor of the angiotensin II receptor developed for the treatment of hypertension, and recent studies show that it exerts anti-inflammatory effects in arthritis. The present study aimed to investigate the mechanism of the protective effect of Olmesartan on cartilage ECM degradation. Interleukin-29 (IL-29) is a novel inflammatory mediator involved in the inflammation and degradation of cartilage in OA, and human T/C-28a2 cells treated with it were the inflammatory model in vitro. We found that the degradation of type 2 collagens and aggrecans was induced by IL-29, accompanied by the upregulation of MMPs and ADAMTSs, but the presence of Olmesartan significantly ameliorated these increases. In addition, Olmesartan abolished IL-29- induced oxidative stress and elevated the expression level of TNF receptor-associated factor 6 (TRAF-6). Mechanistically, we showed that Olmesartan suppressed IL-29- caused inhibitor kappa B α (IκBα) expression and nuclear translocation of nuclear factor kappa-B (NF-κB) p65, indicating it suppressed the activation of the NF-κB pathway. Collectively, our data reveal that Olmesartan exerted a protective function on IL-29- induced type 2 collagen degradation in human chondrocytes.

25-Hydroxycholesterol-Induced Oxiapoptophagy in L929 Mouse Fibroblast Cell Line

25-hydroxycholesterol (25-HC) is an oxysterol synthesized from cholesterol by cholesterol-25-hydroxylase during cholesterol metabolism. The aim of this study was to verify whether 25-HC induces oxiapoptophagy in fibroblasts. 25-HC not only decreased the survival of L929 cells, but also increased the number of cells with condensed chromatin and altered morphology. Fluorescence-activated cell sorting results showed that there was a dose-dependent increase in the apoptotic populations of L929 cells upon treatment with 25-HC. 25-HC-induced apoptotic cell death was mediated by the death receptor-dependent extrinsic and mitochondria-dependent intrinsic apoptosis pathway, through the cascade activation of caspases including caspase-8, -9, and -3 in L929 cells. There was an increase in the levels of reactive oxygen species and inflammatory mediators such as inducible nitric oxide synthase, cyclooxygenase-2, nitric oxide, and prostaglandin E2 in L929 cells treated with 25-HC. Moreover, 25-HC caused an increase in the expression of beclin-1 and microtubule-associated protein 1A/1B-light chain 3, an autophagy biomarker, in L929 cells. There was a significant decrease in the phosphorylation of protein kinase B (Akt) in L929 cells treated with 25-HC. Taken together, 25-HC induced oxiapoptophagy through the modulation of Akt and p53 cellular signaling pathways in L929 cells.

Tert-Butylhydroquinone Prevents Oxidative Stress-Mediated Apoptosis and Extracellular Matrix Degradation in Rat Chondrocytes

Oxidative stress-induced chondrocyte apoptosis and degradation of the extracellular matrix (ECM) play an important role in the progression of osteoarthritis (OA). In addition, tert-butylhydroquinone (TBHQ) is an activator of the nuclear factor erythroid derived-2-related factor 2 (Nrf2). The present study aimed to determine the effectiveness of TBHQ in preventing the apoptosis of chondrocytes and degradation of the extracellular matrix, induced by oxidative stress, in vitro. Therefore, rat chondrocytes were exposed to 20 μM tert-butyl hydroperoxide (TBHP) for 24 h to establish an oxidative damage model, in vitro. Thereafter, cell viability was evaluated using the Cell Counting Kit-8 assay. Moreover, the level of ROS was determined through 2′,7′-dichlorofluorescein diacetate staining. The mitochondrial membrane potential of chondrocytes was also measured using JC-1. Furthermore, cell apoptosis was assessed through Annexin V-fluorescein isothiocyanate/propidium iodide staining. The study also performed Western blotting and qPCR to evaluate the expression of extracellular matrix components, matrix catabolic enzymes, and changes in signalling pathways. The results showed that 2.5 and 5 μM of TBHQ reduced the TBHP-induced generation of excessive ROS and improved cell viability. Additionally, 2.5 and 5 μM of TBHQ prevented mitochondrial damage and apoptosis in rat chondrocytes. Treatment with TBHQ also increased the mRNA and protein expression levels of aggrecan and collagen II. However, TBHQ reduced the mRNA and protein expression levels of matrix metalloproteinase 3 (MMP3) and matrix metalloproteinase 13 (MMP13) in rat chondrocytes. In addition, treatment with TBHQ enhanced the protein expression levels of Nrf2, NADPH quinone oxidoreductase 1 (NQO-1), and hemeoxygenase-1 (HO-1) in rat chondrocytes. The current study showed that TBHQ was not only effective in protecting against TBHP-induced oxidative stress but also inhibited the apoptosis of rat chondrocytes and degradation of the ECM by activating the Nrf2 pathway. The results therefore suggest that TBHQ holds potential for use in the treatment of OA.

An up to date on clinical prospects and management of osteoarthritis

The rising prevalence of osteoarthritis (OA) in the general population has necessitated the development of novel treatment options. It is critical to recognize the joint as a separate entity participating in degenerative processes, as well as the multifaceted nature of OA. OA is incurable because there is currently no medication that can stop or reverse cartilage or bone loss. As this point of view has attracted attention, more research is being directed toward determining how the various joint components are impacted and how they contribute to OA pathogenesis. Over the next few years, several prospective therapies focusing on inflammation, cartilage metabolism, subchondral bone remodelling, cellular senescence, and the peripheral nociceptive pathway are predicted to transform the OA therapy landscape. Stem cell therapies and the use of various biomaterials to target articular cartilage (AC) and osteochondral tissues are now being investigated in considerable detail. Currently, laboratory-made cartilage tissues are on the verge of being used in clinical settings. This review focuses on the update of clinical prospects and management of osteoarthritis, as well as future possibilities for the treatment of OA.

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Osteoarthritis (OA) is a general term that incorporates several different joint diseases.

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The exact pathophysiology of OA remains unclear.

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OA is incurable because there is currently no medication that can stop or reverse cartilage or bone loss.

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Nonsteroidal anti-inflammatory drugs are the most frequently prescribed medications to alleviate arthritic discomfort.

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Stem cell therapies to target articular cartilage and osteochondral tissues are now under investigation.

Identification of transcription factors and construction of a novel miRNA regulatory network in primary osteoarthritis by integrated analysis

Backgrounds

As osteoarthritis (OA) disease-modifying therapies are not available, novel therapeutic targets need to be discovered and prioritized. Here, we aim to identify miRNA signatures in patients to fully elucidate regulatory mechanism of OA pathogenesis and advance in basic understanding of the genetic etiology of OA.

Methods

Six participants (3 OA and 3 controls) were recruited and serum samples were assayed through RNA sequencing (RNA-seq). And, RNA-seq dataset was analysed to identify genes, pathways and regulatory networks dysregulated in OA. The overlapped differentially expressed microRNAs (DEMs) were further screened in combination with the microarray dataset GSE143514. The expression levels of candidate miRNAs were further validated by quantitative real-time PCR (qRT-PCR) based on the GEO dataset (GSE114007).

Results

Serum samples were sequenced interrogating 382 miRNAs. After screening of independent samples and GEO database, the two comparison datasets shared 19 overlapped candidate micRNAs. Of these, 9 up-regulated DEMs and 10 down-regulated DEMs were detected, respectively. There were 236 target genes for up-regulated DEMs and 400 target genes for those down-regulated DEMs. For up-regulated DEMs, the top 10 hub genes were KRAS, NRAS, CDC42, GDNF, SOS1, PIK3R3, GSK3B, IRS2, GNG12, and PRKCA; for down-regulated DEMs, the top 10 hub genes were NR3C1, PPARGC1A, SUMO1, MEF2C, FOXO3, PPP1CB, MAP2K1, RARA, RHOC, CDC23, and CREB3L2. Mir-584-5p-KRAS, mir-183-5p-NRAS, mir-4435-PIK3R3, and mir-4435-SOS1 were identified as four potential regulatory pathways by integrated analysis.

Conclusions

We have integrated differential expression data to reveal putative genes and detected four potential miRNA-target gene pathways through bioinformatics analysis that represent new mediators of abnormal gene expression and promising therapeutic targets in OA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04894-2.

Chlorogenic acid protects human chondrocyte C28/I2 cells from oxidative stress-induced cell death through activation of autophagy

AIMS

The development of osteoarthritis (OA), the most common form of arthritis, is commonly associated with oxidative stress. Indeed, the lack of antioxidant responses largely increases OA incidence. OA is a leading cause of disability in the elderly, which reduces the quality of life and places high socioeconomic burdens on them. Several polyphenolic compounds, including chlorogenic acid (CGA), have shown cytoprotective effects via their antioxidant activity, but the exact mechanism (s) remain elusive. In this study, we demonstrated how CGA protects human chondrocytes against H₂O₂-induced apoptosis.

MATERIALS AND METHODS

The cytoprotective effect by CGA in 500 μM hydrogen peroxide-treated C28/I2 cells was evaluated by cell viability, TUNEL assay, and Western blotting analyses, and autophagy assessment was further performed by AO and MDC staining and tandem mRFP-GFP fluorescence analyses.

KEY FINDINGS

Treatment of CGA to the human chondrocytes under oxidative stress significantly decreased apoptosis markers, such as cleaved caspase 3 and cleaved PARP, and increased anti-apoptotic marker Bcl-xL and the antioxidant response proteins NRF2 and NF-κB. Furthermore, CGA-dependent activation of antioxidant response proteins NRF2 and NF-κB and its protective effects in chondrocytes depended on autophagy. Indeed, CGA treatment and autophagy induction significantly decreased reactive oxygen species (ROS)-induced apoptosis.

SIGNIFICANCE

CGA exhibited the protective effect to human chondrocyte C28/I2 cells against oxidative stress-induced cell death by activating autophagy. These findings indicate that CGA is a potential therapeutic agent for the development of OA drugs.

A retrotransposon gag-like-3 gene RTL3 and SOX-9 co-regulate the expression of COL2A1 in chondrocytes

PURPOSE

Transposable elements are known to remodel gene structure and provide a known source of genetic variation. Retrotransposon gag-like-3 (RTL3) is a mammalian retrotransposon-derived transcript (MART) whose function in the skeletal tissue is unknown. This study aimed to elucidate the biological significance of RTL3 in chondrogenesis and type-II collagen (COL2A1) gene expression in chondrocytes.

MATERIALS AND METHODS

Expression of RTL3, SOX-9 and COL2A1 mRNAs was determined by TaqMan assays and the protein expression by immunoblotting. RTL3 and Sox-9 depletion in human chondrocytes was achieved using validated siRNAs. An RTL3 mutant (∆RTL3) lacking the zinc finger domain was created using in vitro mutagenesis. Forced expression of RTL3, ∆RTL3, and SOX-9 was achieved using CMV promoter containing expression plasmids. CRISPR-Cas9 was utilized to delete Rtl3 and create a stable ATDC5^Rlt3-/- cell line. Matrix deposition and Col2a1 quantification during chondrogenesis were determined by Alcian blue staining and Sircol™ Soluble Collagen Assay, respectively.

RESULTS

RTL3 is not ubiquitously expressed but showed strong expression in cartilage, chondrocytes and synoviocytes but not in muscle, brain, or other tissues analyzed. Loss-of-function and gain-of-function studies demonstrated a critical role of RTL3 in the regulation of SOX-9 and COL2A1 expression and matrix synthesis during chondrogenesis. Both RTL3 and SOX-9 displayed co-regulated expression in chondrocytes. Gene regulatory activity of RTL3 requires the c-terminal CCHC zinc-finger binding domain.

CONCLUSIONS

Our results identify a novel regulatory mechanism of COL2A1 expression in chondrocytes that may help to further understand the skeletal development and the pathogenesis of diseases with altered COL2A1 expression.

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

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

Enhancement of DUSP14 (dual specificity phosphatase 14) limits osteoarthritis progression by alleviating chondrocyte injury, inflammation and metabolic homeostasis

Osteoarthritis (OA) is a proverbial inflammatory degenerative joint disease associated with the acceleration of the aging process and is characterized by chondrocyte injury and articular cartilage degradation. Dual-specificity phosphatase 14 (Dusp14), a common member of the DUSP family, has been implicated in multiple inflammatory diseases and bone loss. Nevertheless, the function of DUSP14 in OA remains unclear. In the present study, down-regulation of DUSP14 was corroborated in anterior cruciate ligament transection (ACLT)-induced OA rats and interleukin-1β (IL-1β)-stimulated chondrocytes. Additionally, the gain of DUSP14 reversed IL-1β-induced inhibition of chondrocyte viability but attenuated cell apoptosis. Concomitantly, DUSP14 overexpression muted IL-1β-induced release of pro-inflammatory mediators NO and prostaglandin E2 (PGE2), as well as pro-inflammatory cytokine levels (IL-6 and TNF-α). Furthermore, up-regulation of DUSP14 overturned the effects of IL-1β on the inhibition of collagen II and aggrecan expression, and enhancement of A Disintegrin and Metalloproteinase with Thrombospondin Motifs 5 (ADAMTS5) and matrix metalloproteinases (MMPs; MMP3 and MMP-13). Mechanistically, DUSP14 elevation increased the p-Adenosine 5ʹ-monophosphate-activated protein activated protein kinase(AMPK), inhibitor of NF-κB (IκB) expression and decreased p-p65 NF-κB expression, indicating that DUSP14 might restore the AMPK-IκB pathway to restrain NF-κB signaling under IL-1β exposure. Notably, blockage of AMPK signaling muted the protective efficacy of DUSP14 elevation against IL-1β-induced inflammatory injury and metabolism disturbance in chondrocytes. Interestingly, histological evaluation substantiated that DUSP14 injection alleviated cartilage degradation in OA rats. Together, DUSP14 may ameliorate OA progression by affecting chondrocyte injury, inflammatory response and cartilage metabolism homeostasis, implying a promising therapeutic strategy against OA.

Fibroblast growth factor 21 (FGF21) alleviates senescence, apoptosis, and extracellular matrix degradation in osteoarthritis via the SIRT1-mTOR signaling pathway

Osteoarthritis (OA) is a complex condition that involves both apoptosis and senescence and currently cannot be cured. Fibroblast growth factor 21 (FGF21), known for its role as a potent regulator of glucose and energy metabolism, protects from various diseases, possibly by mediating autophagy. In the present study, the role of FGF21 in the progression of OA was investigated in both in vitro and in vivo experiments. In vitro, the results revealed that FGF21 administration alleviated apoptosis, senescence, and extracellular matrix (ECM) catabolism of the chondrocytes induced by tert-butyl hydroperoxide (TBHP) by mediating autophagy flux. Furthermore, CQ, an autophagy flux inhibitor, could reverse the protective effect of FGF21. It was observed that the FGF21-induced autophagy flux enhancement was mediated by the nuclear translocation of TFEB, which occurs due to the activation of the SIRT1-mTOR signaling pathway. The in vivo experiments demonstrated that FGF21 treatment could reduce OA in the DMM model. Taken together, these findings suggest that FGF21 protects chondrocytes from apoptosis, senescence, and ECM catabolism via autophagy flux upregulation and also reduces OA development in vivo, demonstrating its potential as a therapeutic agent in OA.

Effects of donkey milk on oxidative stress and inflammatory response

Donkey milk is gaining interest as a natural nutritional and medicinal product, mainly because its composition is similar to that of human milk, and it has some potential biological properties, such as antioxidant, anti-inflammatory, antiaging, antimicrobial, and anticancer properties. Considering the increasing prevalence of several chronic diseases related to oxidative stress and inflammation and the multiple beneficial properties and nutritional value of donkey milk, an up-to-date review of the current studies related to the antioxidative and anti-inflammatory abilities of donkey milk is necessary. Therefore, this review aims to discuss the relationship between inflammation and oxidative stress; and to further systematically review the progress of recent research on donkey milk, mainly including its nutritional value and functional properties. Particularly, we highlighted the anti-inflammatory and antioxidative properties of donkey milk using in vitro model, animal model, and the potential role of donkey milk in alleviating some chronic diseases related to inflammation. PRACTICAL APPLICATIONS: This paper was conducted on anti-inflammation and antioxidant activities of donkey milk and its related products, in addition to a summary of the relationship between oxidative stress and inflammation and the value of donkey milk. Donkey milk and its related products have been shown to scavenge reactive oxygen species, activate the antioxidant system, enhance immune function, and maintain the balance of intestinal flora in in vitro and in vivo models. This paper should provide a better understanding of the influences of oxidative stress and inflammation on host health and the biological functions and application of donkey milk, and will provide a certain basis for the nutritional regulation of several chronic diseases related to oxidative stress and inflammation. However, the underlying mechanism is poorly understood. In addition, few clinical studies have been performed to establish its multiple benefits in humans. Further research is warranted to evaluate its impacts on health at molecular levels.

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

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

Phytochemical Analysis and Anti-Inflammatory and Anti-Osteoarthritic Bioactive Potential of Verbascum thapsus L. (Scrophulariaceae) Leaf Extract Evaluated in Two In Vitro Models of Inflammation and Osteoarthritis

Osteoarthritis (OA) is a complex disease, source of pain and disability that affects millions of people worldwide. OA etiology is complex, multifactorial and joint-specific, with genetic, biological and biomechanical components. Recently, several studies have suggested a potential adjuvant role for natural extracts on OA progression, in terms of moderating chondrocyte inflammation and following cartilage injury, thus resulting in an overall improvement of joint pain. In this study, we first analyzed the phenylethanoid glycosides profile and the total amount of polyphenols present in a leaf aqueous extract of Verbascum thapsus L. We then investigated the anti-inflammatory and anti-osteoarthritic bioactive potential of the extract in murine monocyte/macrophage-like cells (RAW 264.7) and in human chondrocyte cells (HC), by gene expression analysis of specifics inflammatory cytokines, pro-inflammatory enzymes and metalloproteases. Six phenylethanoid glycosides were identified and the total phenolic content was 124.0 ± 0.7 mg gallic acid equivalent (GAE)/g of extract. The biological investigation showed that the extract is able to significantly decrease most of the cellular inflammatory markers, compared to both control cells and cells treated with Harpagophytum procumbens (Burch.) DC. ex Meisn, used as a positive control. Verbascum thapsus leaf aqueous extract has the potential to moderate the inflammatory response, representing an innovative possible approach for the inflammatory joint disease treatment.

Nrf2 Regulates CHI3L1 to Suppress Inflammation and Improve Post-Traumatic Osteoarthritis

Introduction

Post-traumatic osteoarthritis (PTOA) is an inflammatory condition that occurs following mechanical joint trauma and that results in joint degeneration. This study sought to evaluate the regulatory function of nuclear factor erythroid 2-related factor 2 (Nrf2) in a murine model of anterior cruciate ligament transection (ACLT)-induced PTOA and in an in vitro model of synoviocyte inflammation induced by LPS treatment with the goal of exploring the role of chitinase 3-like-1 (CHI3L1) in this pathogenic context.

Methods

PTOA model mice were intra-articularly injected with Nrf2 overexpression lentiviral vector, and safranin O-fast green staining as well as the Osteoarthritis Research Society International (OARSI) Scoring System were used to evaluate the severity of cartilage damage. Protein expression in the synovial tissue was evaluated by Western blotting, immunohistochemical staining, and ELISA. Additionally, murine synoviocytes were infected with Nrf2 overexpression lentivirus and stimulated with LPS. The levels of inflammatory cytokines were detected by ELISA. ROS levels were measured using dihydroethidium (DHE) dye.

Results

We determined that the overexpression of Nrf2 was sufficient to reduce cartilage degradation in the context of PTOA in vivo, and we observed a significant decrease in the expression of matrix metalloproteinase 13 (MMP13) in the articular cartilage of samples from mice overexpressing Nrf2 relative to control mice. Synovial CHI3L1 expression and serum TNF-α, IL-1β, and IL-6 levels were reduced in animals overexpressing this transcription factor relative to PTOA model controls. Consistent with these findings, murine synoviocytes treated with LPS exhibited dose-dependent increases in ROS, TNF-α, IL-1β, IL-6, Nrf2, and CHI3L1 levels, whereas Nrf2 overexpression was sufficient to suppress these increases.

Conclusion

Our data indicated that Nrf2 negatively regulates CHI3L1, suggesting that this signaling axis may regulate PTOA progression and may thus be a viable therapeutic target in individuals affected by this condition.

Curcumin nanoformulations to combat aging-related diseases

Aging increases the susceptibility to a diverse set of diseases and disorders, including neurodegeneration, cancer, diabetes, and arthritis. Natural compounds are currently being explored as alternative or complementary agents to treat or prevent aging-related malfunctions. Curcumin, a phytochemical isolated from the spice turmeric, has garnered great interest in recent years. With anti-oxidant, anti-inflammatory, anti-microbial, and other physiological activities, curcumin has great potential for health applications. However, the benefits of curcumin are restricted by its low bioavailability and stability in biological systems. Curcumin nanoformulations, or nano-curcumin, may overcome these limitations. This review discusses different forms of nano-curcumin that have been evaluated in vitro and in vivo to treat or prevent aging-associated health impairments. We describe current barriers for the routine use of curcumin nanoformulations in the clinic. Our review highlights outstanding questions and future work that is needed to ensure nano-curcumin is efficient and safe to lessen the burden of aging-related health problems.

Resveratrol attenuates manganese-induced oxidative stress and neuroinflammation through SIRT1 signaling in mice

Exposure to excess levels of manganese (Mn) leads to neurotoxicity. Increasing evidence demonstrates that oxidative stress and neuroinflammation are important pathological causes of neurotoxicity. Resveratrol (Rsv), a sirtuin-1 (SIRT1) activator, plays an important role in neuroprotection. However, the molecular mechanisms of Rsv alleviating Mn-induced oxidative stress and neuroinflammation are not fully understood. To evaluate whether Rsv treatment relieves the oxidative stress and neuroinflammation in the hippocampus after Mn exposure through SIRT1 signaling, C57BL/6 adult mice were exposed to MnCl2 (200 μmol/kg), Rsv (30 mg/kg), and EX527 (5 mg/kg). Our results showed that administering MnCl2 for 6 weeks caused behavioral impairment and nerve cell injury in hippocampal tissue, which was related to oxidative stress and neuroinflammation. Activating Mn-induced JNK and inhibiting SIRT1 increased the phosphorylated and acetylated levels of NF-κB and STAT3, respectively. However, Rsv reduced the phosphorylated and acetylated levels of NF-κB and STAT3, and attenuated Mn-induced oxidative stress and inflammatory cytokines by activating SIRT1 signaling. Most importantly, EX527, a potent SIRT1 inhibitor, inactivated SIRT1, which prevented Rsv from exerting its beneficial effects. Taken together, our findings revealed that Rsv alleviated Mn-induced oxidative stress and neuroinflammation in adult mice by activating SIRT1.

Blocking HOTAIR protects human chondrocytes against IL-1β-induced cell apoptosis, ECM degradation, inflammatory response and oxidative stress via regulating miR-222-3p/ADAM10 axis

BACKGROUND

Long non-coding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) contributes to cartilage damages including osteoarthritis (OA). While, its role and mechanism in chondrocytes is incompletely clear.

METHODS

HOTAIR, microRNA (miR)-222-3p and ADAM metalloproteinase-like domain 10 (ADAM10) expressions were detected by real-time quantitative PCR and western blotting. The interaction between miR-222-3p and HOTAIR or ADAM10 was confirmed by dual-luciferase reporter assay. Cell injury was measured by MTS method, flow cytometry, western blotting, enzyme-linked immunosorbent assay for collagen Type II, type X, sex determining region Y-box 9 (SOX9), matrix metalloproteinase (MMP)-13, interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α, and special assay kits for malondialdehyde (MDA), reactive oxygen species (ROS) and superoxide dismutase (SOD).

RESULTS

HOTAIR was highly expressed in human OA cartilages and IL-1β-induced OA model in immortalized chondrocytes (C-28/I2). Under IL-1β stress, blocking HOTAIR was responsible to high mitochondrial activity and low early apoptosis rate, accompanied with increased B cell lymphoma (Bcl)-2 and LC3B-II/I proteins, boosted IL-10 and SOD productions, suppressed cleaved caspase-3 and p62 proteins, and decreased MDA and ROS levels, as well as elevated secretions of Type II collagen, Type X collagen, SOX9, MMP-13, IL-6, and TNF-α. Moreover, miR-222-3p was a target of HOTAIR, and its overexpression and knockdown could suppress and aggravate IL-1β-induced chondrocytes injury. Furthermore, restoring ADAM10, a target gene of miR-222-3p, counteracted the protective role of miR-222-3p upregulation.

CONCLUSION

HOTAIR might contribute to IL-1β-induced chondrocytes death, inflammation, extracellular matrix degradation, and oxidative stress in OA via miR-222-3p/ADAM10 axis.

The Implication of Reactive Oxygen Species and Antioxidants in Knee Osteoarthritis

Knee osteoarthritis (KOA) is a chronic multifactorial pathology and a current and essential challenge for public health, with a negative impact on the geriatric patient's quality of life. The pathophysiology is not fully known; therefore, no specific treatment has been found to date. The increase in the number of newly diagnosed cases of KOA is worrying, and it is essential to reduce the risk factors and detect those with a protective role in this context. The destructive effects of free radicals consist of the acceleration of chondrosenescence and apoptosis. Among other risk factors, the influence of redox imbalance on the homeostasis of the osteoarticular system is highlighted. The evolution of KOA can be correlated with oxidative stress markers or antioxidant status. These factors reveal the importance of maintaining a redox balance for the joints and the whole body's health, emphasizing the importance of an individualized therapeutic approach based on antioxidant effects. This paper aims to present an updated picture of the implications of reactive oxygen species (ROS) in KOA from pathophysiological and biochemical perspectives, focusing on antioxidant systems that could establish the premises for appropriate treatment to restore the redox balance and improve the condition of patients with KOA.

Hsa_circ_0032131 knockdown inhibits osteoarthritis progression via the miR-502-5p/PRDX3 axis

Osteoarthritis (OA) is a chronic disease characterized by progressive loss of cartilage and failure of the diarthrodial joint. Circular RNAs (circRNAs) are known to participate in the pathogenesis of multiple diseases, including OA. We investigated the functions of hsa_circ_0032131, a circRNA upregulated in OA, using CHON-001 cells and an in vivo OA rat model. CHON-001 cells were treated with interleukin (IL)-1β to mimic OA in vitro. IL-1β-induced inhibition of CHON-001 growth was reversed by silencing hsa_circ_0032131. In addition, hsa_circ_0032131 knockdown reversed IL-1β-induced activation of Trx1, Cyclin D and PRDX3, whereas overexpression of PRDX3, a direct target of miR-502-5p, reversed this effect. Hsa_circ_0032131 served as a competing endogenous RNA for miR-502-5p. Moreover, knockdown of hsa_circ_0032131 attenuated OA symptoms in vivo by inactivating the STAT3 signaling pathway. Thus, silencing of hsa_circ_0032131 inhibited the progression of OA by inactivating the miR-502-5p/PRDX3/Trx1/STAT3 axis, which highlights its potential as a therapeutic target for OA.

Exhausting circ_0136474 and Restoring miR-766-3p Attenuate Chondrocyte Oxidative Injury in IL-1β-Induced Osteoarthritis Progression Through Regulating DNMT3A

Circular RNA circ_0136474 is a new contributor of human osteoarthritis (OA) by suppressing chondrocyte proliferation. However, its role and mechanism in OA chondrocyte injury remain ill defined. Herein, we performed real-time quantitative PCR to detect RNA expression of circ_0136474, microRNA (miR)-766-3p, and DNA methyltransferase 3A (DNMT3A) and utilized Western blotting to measure protein expression of DNMT3A, matrix metalloproteinase-1 (MMP1), MMP13, collagen II, proliferating cell nuclear antigen (PCNA) and B cell lymphoma (Bcl)-2, and Bcl-2-associated X protein (Bax). Direct interaction between miR-766-3p and circ_0136474 or DNMT3A was confirmed by bioinformatics algorithms, dual-luciferase reporter assay, and RNA immunoprecipitation. Functional experiments including cell counting kit-8 assay, flow cytometry, and special assay kits were employed to measure oxidative injury in interleukin (IL)-1β-induced OA-like chondrocytes. First, IL-1β administration induced cell viability inhibition, collagen II suppression, and promotion of MMP1 and MMP13 in human chondrocyte CHON-001 cells. Expression of circ_0136474 and DNMT3A was upregulated, and miR-766-3p was downregulated in human OA cartilages and IL-1β-induced CHON-001 cells. Functionally, both blocking circ_0136474 and upregulating miR-766-3p could rescue cell viability and levels of PCNA, Bcl-2, reduced glutathione (GSH), and total superoxide dismutase (SOD), and attenuate apoptosis rate and levels of Bax, reactive oxygen species (ROS), and lipid peroxidation malondialdehyde (MDA). Mechanically, circ_0136474 served as miR-766-3p sponge to govern miR-766-3p-targeted DNMT3A expression. Accidently, restoring DNMT3A counteracted the miR-766-3p upregulation role, and silencing miR-766-3p weakened circ_0136474 knockdown effect in IL-1β-induced CHON-001 cells. In conclusion, exhausting circ_0136474 could mitigate OA chondrocyte oxidative injury through regulating miR-766-3p/DNMT3A axis.

Reactive Oxygen Species Mediate Low Back Pain by Upregulating Substance P in Intervertebral Disc Degeneration

Reactive oxygen species (ROS) are thought to have a strong correlation with a number of intervertebral disc (IVD) diseases. Here, we aimed to determine whether ROS represent an etiology of low back pain (LBP) during IVD degeneration. Thirty degenerated intervertebral disc samples were obtained from patients, and ROS levels were quantified using dihydroethidium (DHE) staining. The results suggested a significant correlation between the ROS level and the severity of LBP. Subsequently, a puncture-induced LBP model was established in rats, and ROS levels significantly increased compared with those in the sham surgery group, accompanied with severe puncture-induced IVD degeneration. In addition, when ROS levels were increased by H₂O₂ administration or decreased by NAC treatment, the rats showed increased or decreased LBP, respectively. Based on this evidence, we further determined that stimulation with H₂O₂ in nucleus pulposus cells (NPCs) in vivo or in vitro resulted in upregulation of substance P (SP), a peptide thought to be involved in the synaptic transmission of pain, and that the severity of LBP decreased when SP levels were increased by exogenous SP administration or neutralized via aprepitant treatment in the IVDs of rats. In conclusion, ROS are primary inducers of LBP based on clinical and animal data, and the mechanism involves ROS stimulation of NPCs to secrete SP, which is a critical neurotransmitter peptide, to promote LBP in IVDs. Therefore, reducing the level of ROS with specific drugs and inhibiting SP may be alternative methods to treat LBP in the clinic.

Xanthohumol Attenuated Inflammation and ECM Degradation by Mediating HO-1/C/EBPβ Pathway in Osteoarthritis Chondrocytes

Osteoarthritis (OA) is the most frequent and disabling disease in developed countries. The progressive degeneration of articular cartilage characterized as thinner and erosive. Inflammation is well-known to be involved in OA development. However, there are no effective therapeutic strategies to cure it. Xanthohumol (XH) is a natural prenylflavonoid isolated from hops and beer. The protective activity of XH against OA chondrocytes inflammation and ECM degradation is unclear. In this article, we found that XH significantly inhibited inflammatory responses, attenuated catabolic enzymes expression, and ameliorated ECM degradation, as showed by decreased production of NO, PGE2, TNFα, and IL-6, decreased expression of MMP-3/-13 and ADAMTS-4/-5, and increased expression of collagen-II and aggrecan. In addition, XH activated HO-1 signaling and attenuated IL-1β-induced C/EBPβ. XH promoted the interaction between HO-1 and C/EBPβ, inhibiting the nuclear translocation of C/EBPβ. HO-1 knockdown could abrogate the protective effects of XH in IL-1β-treated chondrocytes. Collectively, XH attenuated inflammatory responses and ECM degradation by mediating HO-1 and C/EBPβ signaling pathways in osteoarthritis chondrocytes.

Puerarin inhibits the development of osteoarthritis through antiinflammatory and antimatrix-degrading pathways in osteoarthritis-induced rat model

Puerarin is an isoflavone isolated from the medicinal plant Pueraria lobata. The purpose of this study was to study the antiinflammatory and antimatrix-degrading effects of puerarin in a rat osteoarthritis (OA) model and its protective effects on joints. The rat OA model was established by anterior cruciate ligament transection (ACLT) surgery. Rats (n = 40) were divided into nontreated OA, OA + celecoxib (2.86 mg/kg), OA + puerarin (50 and 100 mg/kg), and control groups. Two weeks after surgical induction, puerarin was administered by gavage daily for 8 weeks. After 8 weeks, macroscopic observation and histopathological images showed that cartilage damage was reduced after puerarin and celecoxib treatment, the intensity of Safranin O staining was high, and the OARSI scores were significantly reduced compared to the OA group. Puerarin reduced the expression of MMP-3, MMP-13, ADAMTS-5, and COX-2 in the cartilage tissue of ACLT rats, inhibited the production of IL-1β, IL-6, and TNF-α inflammatory factors, increased Type II collagen content, and altered the expression of serum OA cartilage degradation/bone turnover biomarkers (CTX-I, CTX-II, COMP, and PIINP). Based on these findings, we speculate that puerarin supplement to attain recovery from OA damage.

Therapeutic Potential of Bioactive Compounds in Honey for Treating Osteoarthritis

Dysregulation of joint tissue homeostasis induces articular degenerative changes and musculoskeletal diseases such as osteoarthritis. This pathology represents the first cause of motor disability in individuals over 60 years of age, impacting their quality of life and the costs of health systems. Nowadays, pharmacological treatments for cartilage disease have failed to achieve full tissue regeneration, resulting in a functional loss of the joint; therefore, joint arthroplasty is the gold standard procedure to cure this pathology in severe cases of Osteoarthritis. A different treatment is the use of anti-inflammatory drugs which mitigate pain and inflammation in some degree, but without significant inhibition of disease progression. In this sense, new therapeutic alternatives based on natural compounds have been proposed to delay osteoarthritis progression, particularly those agents that regulate articular homeostasis. Preclinical studies have shown a therapeutic application of honey and its bioactive compounds, ranging from treating wounds, coughs, skin infections, and are also used as a biological stimulant by exerting antioxidant and anti-inflammatory properties. In this article, we reviewed the current medicinal applications of honey with particular emphasis on its use regulating articular homeostasis by inhibiting inflammation and oxidative stress.

Phgdh serves a protective role in Il‑1β induced chondrocyte inflammation and oxidative‑stress damage

The primary pathological changes observed in osteoarthritis (OA) involve inflammation and degeneration of chondrocytes. 3‑phosphoglycerate dehydrogenase (Phgdh), a rate‑limiting enzyme involved in the conversion of 3‑phosphoglycerate to serine, serves as a crucial molecular component of cell growth and metabolism. However, its effects on chondrocytes in OA have not been determined. In the present study, a rat model of OA was used to investigate the expression levels of Phgdh in vivo and in vitro. Additionally, the role of Phgdh in extracellular matrix (ECM) synthesis, inflammation, apoptosis and oxidative stress levels of chondrocytes was detected in vitro. Phgdh expression was decreased in OA, and Phgdh overexpression promoted ECM synthesis, decreased levels inflammatory cytokines, such as Il‑6, TNF‑α, a disintegrin and metalloproteinase with thrombospondin motifs 5 and MMP13, and decreased apoptosis. Furthermore, expression of Phgdh effectively increased expression levels of the cellular antioxidant enzymes catalase and superoxide dismutase 1, and decreased the levels of reactive oxygen species in chondrocytes; and this may have been regulated by a Kelch like ECH associated protein 1/nuclear factor erythroid 2‑related factor 2 axis. Taken together, these results suggest that Phgdh may be used to manage the progression of OA.

3'-Sialyllactose Protects SW1353 Chondrocytic Cells From Interleukin-1β-Induced Oxidative Stress and Inflammation

Osteoarthritis (OA) is a major degenerative joint disease. Oxidative stress and inflammation play key roles in the pathogenesis of OA. 3'-Sialyllactose (3'-SL) is derived from human milk and is known to regulate a variety of biological functions related to immune homeostasis. This study aimed to investigate the therapeutic mechanisms of 3'-SL in interleukin-1β (IL-1β)-treated SW1353 chondrocytic cells. 3'-SL potently suppressed IL-1β-induced oxidative stress by increasing the levels of enzymatic antioxidants. 3'-SL significantly reversed the IL-1β mediated expression levels of reactive oxygen species in IL-1β-stimulated chondrocytic cells. In addition, 3'-SL could reverse the increased levels of inflammatory markers such as nitrite, prostaglandin E2, inducible nitric oxide synthase, cyclooxygenase-2, IL-1β, and IL-6 in IL-1β-stimulated chondrocytic cells. Moreover, 3'-SL significantly inhibited the apoptotic process, as indicated by the downregulation of the pro-apoptotic protein Bax, upregulation of the anti-apoptotic protein Bcl-2 expression, and significant reduction in the number of TUNEL-positive cells in the IL-1β-treated chondrocytic cells. Furthermore, 3'-SL reversed cartilage destruction by decreasing the release of matrix metalloproteinases (MMP), such as MMP1, MMP3, and MMP13. In contrast, 3'-SL significantly increased the expression levels of matrix synthesis proteins, such as collagen II and aggrecan, in IL-1β-treated chondrocytic cells. 3'-SL dramatically suppressed the activation of mitogen-activated protein kinases (MAPK) and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways, which are related to the pathogenesis of OA. Taken together, our data suggest that 3'-SL alleviates IL-1β-induced OA pathogenesis via inhibition of activated MAPK and PI3K/AKT/NF-κB signaling cascades with the downregulation of oxidative stress and inflammation. Therefore, 3'-SL has the potential to be used as a natural compound for OA therapy owing to its ability to activate the antioxidant defense system and suppress inflammatory responses.

Facile Synthesis of Hollow MnO2 Nanoparticles for Reactive Oxygen Species Scavenging in Osteoarthritis

Osteoarthritis (OA) is a progressive degenerative joint disease whose molecular mechanism has not been revealed clearly, and there is still no effective approach to cure OA completely. Recently, reactive oxygen species (ROS) are exposed as an important mediator of OA's inflammatory response, and it has been regarded as a therapeutic target for OA treatment. MnO₂ nanoparticles possess good biocompatibility and can act as an artificial nanoenzyme to scavenge ROS in various diseases effectively. In this study, the modified Stöber method was applied to synthesize hollow MnO₂ (H-MnO₂) and H-MnO₂ was modified with NH₂-PEG-NH₂, which possesses excellent biological stability and biocompatibility. It induced a change in the articular cartilage structure changes in vivo, with the knee tissue staining and micro-CT scanning of the whole knee suggesting that H-MnO₂ nanoparticles could effectively remove ROS and significantly relieve the inflammatory response of OA without obvious side effects. This study reveals the therapeutic effects of MnO₂-based nanomedicine toward OA, which provides potential alternative therapeutic options for patients with inflammation tissue.

Essential Oils for Bone Repair and Regeneration-Mechanisms and Applications

Although bone possesses a remarkable capacity for self-remodeling and self-healing of small defects, the continuously increasing growth of bone diseases in the elderly population is becoming a significant burden, affecting individual life quality and society. Conventional treatment options involve surgical procedures for repair and reconstruction, local debridement, autografts or allografts, bone transport, Masquelet's two-stage reconstructions, and vascularized bone transplants. However, as such approaches often lead to disruptions of bone-regeneration processes and microbial contaminations and are often inefficient, researchers focus on developing bone-regenerative strategies and identifying novel therapeutic agents that could aid the bone-healing process. In this regard, plant-derived biocompounds, especially essential oils (EOs), have received great scientific attention in recent years, owing to their antioxidant, anti-inflammatory, and antimicrobial effects. Current studies focus on either the direct application of EOs on bone tissue or the introduction of EOs as bioactive compounds in bone scaffolds or as coatings for bone implants. Some of the EOs investigated involve St. John's wort, rosemary, thyme, ylang, white poplar, eucalyptus, lavender, and grape seed. In this context, the present paper aims to provide an overview of the main mechanisms involved in bone repair and regeneration and the potential of EOs to address and enhance these mechanisms.

Enzyme-Assisted Extraction to Obtain Phenolic-Enriched Wine Lees with Enhanced Bioactivity in Hypertensive Rats

The antihypertensive effect of the soluble fraction of wine lees (WL) from Cabernet variety grapes was recently reported by our group. This blood pressure (BP)-lowering effect was attributed to the presence of flavanols and anthocyanins. In this context, phenolic-enriched wine lees (PWL) could potentially exhibit a stronger bioactivity. Therefore, the aim of this study was to obtain a soluble fraction of WL with increased phenolic content and evaluate its functionality. The PWL were obtained using an enzyme-assisted extraction based on the hydrolysis of WL proteins with Flavourzyme^®. They contained 57.20% more total phenolic compounds than WL, with anthocyanins and flavanols being the largest families present. In addition, PWL also showed greater angiotensin-converting enzyme inhibitory and antioxidant activities. Finally, the antihypertensive activity of the PWL was evaluated in spontaneously hypertensive rats. A single dose of 5 mL/kg body weight of PWL showed a greater BP-lowering effect than the one shown by WL. Moreover, this antihypertensive effect was more prolonged than the one produced by the antihypertensive drug Captopril. These results demonstrate that enzymatic protein hydrolysis is a useful method to maximize the extraction of phenolic compounds from WL and to obtain extracts with enhanced functionalities.

Associations between diet quality and knee joint structures, symptoms and systemic abnormalities in people with symptomatic knee osteoarthritis

BACKGROUND & AIMS

The evidence of benefiting from a high-quality diet for knee osteoarthritis (OA) joint structures, symptoms, and systemic abnormalities is limited. Clarifying the relationship between diet quality and knee OA could provide useful information for knee OA management. To investigate the associations between diet quality and knee joint structures, symptoms, lower limb muscle strength, depressive symptoms, and quality of life in people with knee OA.

METHODS

This study was a post-hoc, exploratory analysis using data from a randomized controlled trial in symptomatic knee OA participants with a follow-up time of 24 months. In brief, eligible participants of the original study were aged 50-79 years, had symptomatic knee OA, and had a pain of 20-80 mm on a 100-mm visual analog scale. After excluding the patients without information on diet quality, 392 participants were included in this post-hoc analysis. Diet quality was assessed at baseline using the Australian Recommended Food Score (ARFS) which includes subscores of vegetable, fruit, grain, dairy products, fat, and alcohol. Knee joint structures (including cartilage volume, cartilage defect, bone marrow lesions, and effusion-synovitis volume assessed by magnetic resonance imaging), OA symptoms, lower limb muscle strength, depressive symptoms, and quality of life were assessed at baseline and follow up. Mixed-effects models were used to assess the associations of diet quality with those outcomes.

RESULTS

Diet quality mainly reflect diet variety within the core food was not associated with knee structures and OA symptoms, but was associated with greater lower limb muscle strength (β = 0.66, P = 0.001), lower depressive symptom (β = -0.08, P = 0.001), and better quality of life (β = -0.06, P = 0.002). In further analyses of food group-based sub-scores, only the vegetable sub-score had the similar associations with lower limb muscle strength (β = 1.03, P = 0.004), depressive symptom (β = -0.17, P < 0.001), and quality of life (β = -0.14, P < 0.001).

CONCLUSIONS

Higher diet quality, mainly vegetable diet quality, is associated with greater lower limb muscle strength, less depressive symptoms, and higher quality of life in knee OA patients, suggesting higher diet quality may have protective effects on knee OA.

Schisandrol A Suppresses Catabolic Factor Expression by Blocking NF-κB Signaling in Osteoarthritis

Schisandrol A possesses pharmacological properties and is used to treat various diseases; however, its effects on osteoarthritis (OA) progression remain unclear. Here, we investigated Schisandrol A as a potential therapeutic agent for OA. In vitro, Schisandrol A effects were confirmed based on the levels of expression of catabolic factors (MMPs, ADAMTS5, and Cox2) induced by IL-1β or Schisandrol A treatment in chondrocytes. In vivo, experimental OA in mice was induced using a destabilized medial meniscus (DMM) surgical model or oral gavage of Schisandrol A in a dose-dependent manner, and demonstrated using histological analysis. In vitro and in vivo analyses demonstrated that Schisandrol A inhibition attenuated osteoarthritic cartilage destruction via the regulation of Mmp3, Mmp13, Adamts5, and Cox2 expression. In the NF-κB signaling pathway, Schisandrol A suppressed the degradation of IκB and the phosphorylation of p65 induced by IL-1β. Overall, and Schisandrol A reduced the expression of catabolic factors by blocking NF-κB signaling and prevented cartilage destruction. Therefore, Schisandrol A attenuated OA progression, and can be used to develop novel OA drug therapies.