The role of oxidative stress in the development of knee osteoarthritis: A comprehensive research review

In vitro and in vivo studies of the therapeutic potential of Tinospora crispa extracts in osteoarthritis: Targeting oxidation, inflammation, and chondroprotection

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing incidence of osteoarthritis (OA), especially among the elderly population, highlights the need for more efficacious treatments that go beyond mere symptomatic relief. Tinospora crispa (L.) Hook. f. & Thomson (TC) boasts a rich traditional heritage, widespread use in Ayurveda, traditional Chinese medicine (TCM), and diverse indigenous healing practices throughout Southeast Asia for treating arthritis, rheumatism, fever, and inflammation.

AIM OF THE STUDY

This study investigates the anti-inflammatory and chondroprotective potential of TC stem extracts, including ethanolic TC extract (ETCE) and aqueous TC extract (ATCE), in modulating OA pathogenesis through in vitro and in vivo approaches.

MATERIALS AND METHODS

The study utilized LC-MS/MS to identify key compounds in TC stem extracts. In vitro experiments assessed the antioxidative and anti-inflammatory properties of ETCE and ATCE in activated macrophages, while an in vivo monoiodoacetate (MIA)-induced OA rat model evaluated the efficacy of ETCE treatment. Key markers of oxidative stress, such as superoxide dismutase (SOD) and catalase (CAT), were assessed alongside pro-inflammatory cytokines TNF-α and IL-1β, and matrix-degrading enzymes, matrix metalloproteinase (MMP 13 and MMP 3), to evaluate the therapeutic effects of TC stem extracts on OA.

RESULTS

Chemical profiling of the extracts was conducted using LC-MS/MS in positive ionization, identifying seven compounds, including pseudolaric acid B, stylopine, and reticuline, which were reported for the first time in this species. The study utilized varying concentrations of TC stem extracts, specifically 6.25-25 μg/mL for in vitro assays and 500 mg/kg for in vivo studies. Our findings also revealed that both ETCE and ATCE exhibit dose-dependent reduction in reactive oxygen species (41%-52%) and nitric oxide (NO) levels (50% and 72%), with ETCE displaying superior antioxidative efficacy and marked anti-inflammatory properties, significantly reducing TNF-α and IL-6 at concentrations above 12.5 μg/mL. In the MIA-induced OA rat model, ETCE treatment notably outperformed ATCE, markedly lowering TNF-α (1.91 ± 0.37 pg/mL) and IL-1β (26.30 ± 3.68 pg/mL) levels and effectively inhibiting MMP 13 and MMP 3 enzymes. Furthermore, macroscopic and histopathological assessments, including ICRS scoring and OARSI grading, indicate that TC stem extracts reduce articular damage and proteoglycan loss in rat knee cartilage. These results suggest that TC stem extracts may play a role in preventing cartilage degradation and potentially alleviating inflammation and pain associated with OA, though further studies are needed to confirm these effects.

CONCLUSION

This study highlights the potential of TC stem extracts as a novel, chondroprotective therapeutic avenue for OA management. By targeting oxidative stress, pro-inflammatory cytokines, and cartilage-degrading enzymes, TC stem extracts promise to prevent cartilage degradation and alleviate inflammation and pain associated with OA.

Intrauterine hyperglycemia induces SIRT3-mediated mitochondrial dysfunction: the fetal origin pathogenesis of precocious osteoarthritis

OBJECTIVE

Diabetes and other metabolic and inflammatory comorbidities are highly associated with osteoarthritis (OA). However, whether early-life hyperglycemia exposure affects susceptibility to long-term OA is still unknown. The purpose of this study was to explore the fetal origins of OA and provide insights into early-life safeguarding for individual health.

METHOD

This study utilized streptozotocin to induce intrauterine hyperglycemia and performed destabilization of the medial meniscus surgery on the knee joints of the offspring mice to induce accelerated OA. Cartilage degeneration-related markers, as well as the expression levels of mitochondrial respiratory chain complexes and mitophagy genes in the adult offspring mice, were investigated. In vitro, mitochondrial function and mitophagy of chondrocyte C28/I2 cells stimulated under high glucose conditions were also evaluated. The methylation levels of the sirt3 gene promoter region in the articular cartilage of intrauterine hyperglycemia-exposed offspring mice were further analyzed.

RESULTS

In this study, we found that the intrauterine hyperglycemic environment could lead to an increase in individual susceptibility to OA in late adulthood, mainly due to persistently low levels of Sirt3 expression. Downregulation of Sirt3 causes impaired mitophagy in chondrocytes and abnormal mitochondrial respiratory function due to a failure to clear aged and damaged mitochondria in a timely manner. Overexpressing Sirt3 at the cellular level or using Sirt3 agonists like Honokiol in mouse models can partially rescue mitophagy disorders caused by the hyperglycemic environment and thus alleviate the progression of OA.

CONCLUSION

Our study revealed a significantly increased susceptibility to OA in the gestational diabetes mellitus offspring, which is partly attributed to exposure to adverse factors in utero and ultimately to the onset of disease via epigenetic modulation.

Non-coding RNAs as regulators of autophagy in chondrocytes: Mechanisms and implications for osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease with multiple causative factors such as aging, mechanical injury, and obesity. Autophagy is a complex dynamic process that is involved in the degradation and modification of intracellular proteins and organelles under different pathophysiological conditions. Autophagy, as a cell survival mechanism under various stress conditions, plays a key role in regulating chondrocyte life cycle metabolism and cellular homeostasis. Non-coding RNAs (ncRNAs) are heterogeneous transcripts that do not possess protein-coding functions, but they can act as effective post-transcriptional and epigenetic regulators of gene and protein expression, thus participating in numerous fundamental biological processes. Increasing evidence suggests that ncRNAs, autophagy, and their crosstalk play crucial roles in OA pathogenesis. Therefore, we summarized the complex role of autophagy in OA chondrocytes and focused on the regulatory role of ncRNAs in OA-associated autophagy to elucidate the complex pathological mechanisms of the ncRNA-autophagy network in the development of OA, thus providing new research targets for the clinical diagnosis and treatment of OA.

Association between Dietary total antioxidant capacity and knee osteoarthritis: a case-control study in the Iranian Population

AIM

Knee osteoarthritis (KOA) is a prevalent chronic condition associated with significant pain, disability, and healthcare costs, particularly among the elderly population. Despite the considerable burden of KOA, effective treatment options for managing the condition's underlying causes remain limited. This case-control study aims to investigate the relationship between dietary total antioxidant capacity (DTAC) and knee osteoarthritis.

METHODS

This case-control study was conducted on 105 patients with confirmed KOA and 210 controls. KOA was diagnosed based on the American College of Rheumatology criteria. Dietary total antioxidant capacity (DTAC) was calculated based on the ferric-reducing antioxidant power method.

RESULTS

The mean age and BMI of the participants were 53.6 ± 8.8 years old and 27.3 ± 2.7 kg/m2, respectively. The study participant's DTAC score ranged from 3.56 to 25.32 with a mean and SD of 12.46 ± 5.12. In the crude model, individuals in the highest quartile of DTAC score had 71% lower odds of having knee osteoarthritis compared to those in the first quartile (OR: 0.29, 95%CI: 0.15 to 0.58, P-trend < 0.001). These associations remained significant after adjustment for potential confounders including age, sex, energy intake, family history of osteoarthritis, vitamin D and calcium use, physical activity level, cigarette smoking and BMI. Although the odds of having knee osteoarthritis decreased with increasing quartiles of DTAC in both sexes, this relationship was stronger among males than females.

CONCLUSION

The results of this study showed that there was an inverse correlation between DTAC and KOA among the Iranian patients with KOA.

Aging and "Age-Related" Diseases - What Is the Relation?

The study explores the intricate relationship between aging and the development of noncommunicable diseases [NCDs], focusing on whether these diseases are inevitable consequences of aging or primarily driven by lifestyle factors. By examining epidemiological data, particularly from hunter-gatherer societies, the study highlights that many NCDs prevalent in modern populations are rare in these societies, suggesting a significant influence of lifestyle choices. It delves into the mechanisms through which poor diet, smoking, and other lifestyle factors contribute to systemic physiological imbalances, characterized by oxidative stress, insulin resistance and hyperinsulinemia, and dysregulation of the sympathetic nervous system, the renin-angiotensin-aldosterone system, and the immune system. The interplay between this pattern and individual factors such as genetic susceptibility, biological variability, epigenetic changes and the microbiome is proposed to play a crucial role in the development of a range of age-related NCDs. Modified biomolecules such as oxysterols and advanced glycation end products also contribute to their development. Specific diseases such as benign prostatic hyperplasia, Parkinson's disease, glaucoma and osteoarthritis are analyzed to illustrate these mechanisms. The study concludes that while aging contributes to the risk of NCDs, lifestyle factors play a crucial role, offering potential avenues for prevention and intervention through healthier living practices. One possible approach could be to try to restore the physiological balance, e.g. through dietary measures [e.g. Mediterranean diet, Okinawan diet or Paleolithic diet] in conjunction with [a combination of] pharmacological interventions and other lifestyle changes.

Research progress on nanotechnology of traditional Chinese medicine to enhance the therapeutic effect of osteoarthritis

Osteoarthritis (OA) is a prevalent chronic condition that primarily impacts the articular cartilage and surrounding bone tissue, resulting in joint inflammation and structural deterioration. The etiology of OA is multifaceted and intricately linked to the oxidative stress response of joint tissue. Oxidative stress (OS) in OA leads to the creation of reactive oxygen species (ROS) and other oxidizing agents, resulting in detrimental effects on chondrocytes. This oxidative damage diminishes the flexibility and robustness of cartilage, thereby expediting the progression of joint deterioration. Therefore, the antioxidant effect is crucial in the treatment of OA. Currently, a considerable number of components found in traditional Chinese medicine (TCM) have been scientifically demonstrated to exhibit remarkable antioxidant and anti-inflammatory properties. Nevertheless, the utilization of this program is considerably constrained as a result of intrinsic deficiencies, notably stability concerns. The successful amalgamation of TCM components with nanotechnology has properly tackled these concerns and enhanced the efficacy of therapeutic results. The objective of this study is to delineate the antioxidant characteristics of nano-TCM and assess the current inventory of literature pertaining to the application of nano-TCM in the treatment of OA. In conclusion, this paper will now turn to the constraints and potential avenues for the advancement of nano-TCM within the realm of OA therapy.

MST1 knockdown inhibits osteoarthritis progression through Parkin-mediated mitophagy and Nrf2/NF-κB signalling pathway

Osteoarthritis (OA) is a complicated disease that involves apoptosis and mitophagy. MST1 is a pro-apoptotic factor. Hence, decreasing its expression plays an anti-apoptotic effect. This study aims to investigate the protective effect of MST1 inhibition on OA and the underlying processes. Immunofluorescence (IF) was used to detect MST1 expression in cartilage tissue. Western Blot, ELISA and IF were used to analyse the expression of inflammation, extracellular matrix (ECM) degradation, apoptosis and mitophagy-associated proteins. MST1 expression in chondrocytes was inhibited using siRNA and shRNA in vitro and in vivo. Haematoxylin-Eosin, Safranin O-Fast Green and alcian blue staining were used to evaluate the therapeutic effect of inhibiting MST1. This study discovered that the expression of MST1 was higher in OA patients. Inhibition of MST1 reduced inflammation, ECM degradation and apoptosis and enhanced mitophagy in vitro. MST1 inhibition slows OA progression in vivo. Inhibiting MST1 suppressed apoptosis, inflammation and ECM degradation via promoting Parkin-mediated mitophagy and the Nrf2-NF-κB axis. The results suggest that MST1 is a possible therapeutic target for the treatment of osteoarthritis as its inhibition delays the progression of OA through the Nrf2-NF-κB axis and mitophagy.

Integrated Network Pharmacology and Experimental Validation Approach to Investigate the Mechanisms of Radix Rehmanniae Praeparata - Angelica Sinensis - Radix Achyranthis Bidentatae in Treating Knee Osteoarthritis

Background

Knee osteoarthritis (KOA) is a persistent degenerative condition characterized by the deterioration of cartilage. The Chinese herbal formula Radix Rehmanniae Praeparata- Angelica Sinensis-Radix Achyranthis Bidentatae (RAR) has often been used in effective prescriptions for KOA as the main functional drug, but its underlying mechanism remains unclear. Therefore, network pharmacology and verification experiments were employed to investigate the impact and mode of action of RAR in the treatment of KOA.

Methods

The destabilization of the medial meniscus model (DMM) was utilized to assess the anti-KOA effect of RAR by using gait analysis, micro-computed tomography (Micro-CT), and histology. Primary chondrocytes were extracted from the rib cartilage of a newborn mouse. The protective effects of RAR on OA cells were evaluated using a CCK-8 assay. The antioxidative effect of RAR was determined by measuring reactive oxygen species (ROS), superoxide dismutase (SOD), and glutathione (GSH) production. Furthermore, network pharmacology and molecular docking were utilized to propose possible RAR targets for KOA, which were further verified through experiments.

Results

In vivo, RAR significantly ameliorated DMM-induced KOA characteristics, such as subchondral bone sclerosis, cartilage deterioration, gait abnormalities, and the degree of knee swelling. In vitro, RAR stimulated chondrocyte proliferation and the expression of Col2a1, Comp, and Acan. Moreover, RAR treatment significantly reduced ROS accumulation in an OA cell model induced by IL-1β and increased the activity of antioxidant enzymes (SOD and GSH). Network pharmacology analysis combined with molecular docking showed that Mapk1 might be a key therapeutic target. Subsequent research showed that RAR could downregulate Mapk1 mRNA levels in IL-1β-induced chondrocytes and DMM-induced rats.

Conclusion

RAR inhibited extracellular matrix (ECM) degradation and oxidative stress response via the MAPK signaling pathway in KOA, and Mapk1 may be a core target.

The Histological and Biochemical Assessment of Monoiodoacetate-Induced Knee Osteoarthritis in a Rat Model Treated with Salicylic Acid-Iron Oxide Nanoparticles

Iron oxide nanoparticles (IONPs) represent an important advance in the field of medicine with application in both diagnostic and drug delivery domains, offering a therapeutic approach that effectively overcomes physical and biological barriers. The current study aimed to assess whether oral administration of salicylic acid-functionalized iron oxide nanoparticles (SaIONPs) may exhibit beneficial effects in alleviating histological lesions in a murine monoiodoacetate (MIA) induced knee osteoarthritis model. In order to conduct our study, 15 Wistar male rats were randomly distributed into 3 work groups: Sham (S), MIA, and NP. At the end of the experiments, all animals were sacrificed for blood, knee, and liver sampling. Our results have shown that SaIONPs reached the targeted sites and also had a chondroprotective effect represented by less severe histological lesions regarding cellularity, altered structure morphology, and proteoglycan depletion across different layers of the knee joint cartilage tissue. Moreover, SaIONPs induced a decrease in malondialdehyde (MDA) and circulating Tumor Necrosis Factor-α (TNF-α) levels. The findings of this study suggest the therapeutic potential of SaIONPs knee osteoarthritis treatment; further studies are needed to establish a correlation between the administrated dose of SaIONPs and the improvement of the morphological and biochemical parameters.

Cannabidiol-Loaded Solid Lipid Nanoparticles Ameliorate the Inhibition of Proinflammatory Cytokines and Free Radicals in an In Vitro Inflammation-Induced Cell Model

Cannabidiol (CBD) is a non-psychoactive compound derived from Cannabis sativa. It has demonstrated promising effects in combating inflammation and holds potential as a treatment for the progression of chronic inflammation. However, the clinical application of CBD is limited due to its poor solubility and bioavailability. This study introduces an effective method for preparing CBD-loaded solid lipid nanoparticles (CBD-SLNs) using a combination of low-energy hot homogenization and ultrasonication. We enhanced this process by employing statistical optimization with response surface methodology (RSM). The optimized CBD-SLN formulation utilizes glyceryl monostearate as the primary lipid component of the nanocarrier. The CBD-SLN formulation is screened as a potential tool for managing chronic inflammation. Stable, uniformly dispersed spherical nanoparticles with a size of 123 nm, a surface charge of -32.1 mV, an encapsulation efficiency of 95.16%, and a drug loading of 2.36% were obtained. The CBD-SLNs exhibited sustained release properties, ensuring prolonged and controlled CBD delivery, which could potentially amplify its therapeutic effects. Additionally, we observed that CBD-SLNs significantly reduced both reactive oxygen and nitrogen species and proinflammatory cytokines in chondrocyte and macrophage cell lines, with these inhibitory effects being more pronounced than those of free CBD. In conclusion, CBD-SLNs demonstrated superiority over free CBD, highlighting its potential as an effective delivery system for CBD.

Mechanisms of chondrocyte regulated cell death in osteoarthritis: Focus on ROS-triggered ferroptosis, parthanatos, and oxeiptosis

Osteoarthritis (OA) is a common chronic inflammatory degenerative disease. Since chondrocytes are the only type of cells in cartilage, their survival is critical for maintaining cartilage morphology. This review offers a comprehensive analysis of how reactive oxygen species (ROS), including superoxide anions, hydrogen peroxide, hydroxyl radicals, nitric oxide, and their derivatives, affect cartilage homeostasis and trigger several novel modes of regulated cell death, including ferroptosis, parthanatos, and oxeiptosis, which may play roles in chondrocyte death and OA development. Moreover, we discuss potential therapeutic strategies to alleviate OA by scavenging ROS and provide new insight into the research and treatment of the role of regulated cell death in OA.

Potential therapeutic strategies for osteoarthritis via CRISPR/Cas9 mediated gene editing

Osteoarthritis (OA) is an incapacitating and one of the most common physically degenerative conditions with an assorted etiology and a highly complicated molecular mechanism that to date lacks an efficient treatment. The capacity to design biological networks and accurately modify existing genomic sites holds an apt potential for applications across medical and biotechnological sciences. One of these highly specific genomes editing technologies is the CRISPR/Cas9 mechanism, referred to as the clustered regularly interspaced short palindromic repeats, which is a defense mechanism constituted by CRISPR associated protein 9 (Cas9) directed by small non-coding RNAs (sncRNA) that bind to target DNA through Watson-Crick base pairing rules where subsequent repair of the target DNA is initiated. Up-to-date research has established the effectiveness of the CRISPR/Cas9 mechanism in targeting the genetic and epigenetic alterations in OA by suppressing or deleting gene expressions and eventually distributing distinctive anti-arthritic properties in both in vitro and in vivo osteoarthritic models. This review aims to epitomize the role of this high-throughput and multiplexed gene editing method as an analogous therapeutic strategy that could greatly facilitate the clinical development of OA-related treatments since it's reportedly an easy, minimally invasive technique, and a comparatively less painful method for osteoarthritic patients.

Gentiopicroside ameliorates the lipopolysaccharide-induced inflammatory response and hypertrophy in chondrocytes

PURPOSE

This study aimed to evaluate the protective effects of gentiopicroside against lipopolysaccharide-induced chondrocyte inflammation.

METHODS

SW 1353 chondrosarcoma cells were stimulated with LPS (5 μg/ml) for 24 h and treated with different concentrations of gentiopicroside (GPS) for 24 h. The toxic effects of GPS on chondrocytes were determined using a CCK-8 assay and EdU staining. Western blotting, qPCR, and immunofluorescence analysis were used to examine the protective effect of GPS against the inflammatory response in chondrocytes induced by lipopolysaccharide (LPS). One-way ANOVA was used to compare the differences between the groups (significance level of 0.05).

RESULTS

The CCK-8 results showed that 10, 20 and 40 μM GPS had no significant toxic effects on chondrocytes; GPS effectively reduced the production of IL-1β and PGE2, reversed LPS-induced extracellular matrix degradation in cartilage by inhibiting the Stat3/Runx2 signaling pathway, and suppressed the hypertrophic transformation of SW 1353 chondrosarcoma cells.

CONCLUSION

Our study demonstrated that GPS significantly inhibited the LPS-induced inflammatory response and hypertrophic cellular degeneration in SW 1353 chondrosarcoma cells and is a valuable traditional Chinese medicine for the treatment of knee osteoarthritis.

Progress in Understanding Oxidative Stress, Aging, and Aging-Related Diseases

Under normal physiological conditions, reactive oxygen species (ROS) are produced through redox reactions as byproducts of respiratory and metabolic activities. However, due to various endogenous and exogenous factors, the body may produce excessive ROS, which leads to oxidative stress (OS). Numerous studies have shown that OS causes a variety of pathological changes in cells, including mitochondrial dysfunction, DNA damage, telomere shortening, lipid peroxidation, and protein oxidative modification, all of which can trigger apoptosis and senescence. OS also induces a variety of aging-related diseases, such as retinal disease, neurodegenerative disease, osteoarthritis, cardiovascular diseases, cancer, ovarian disease, and prostate disease. In this review, we aim to introduce the multiple internal and external triggers that mediate ROS levels in rodents and humans as well as the relationship between OS, aging, and aging-related diseases. Finally, we present a statistical analysis of effective antioxidant measures currently being developed and applied in the field of aging research.

The dysregulated autophagy in osteoarthritis: Revisiting molecular profile

The risk factors of osteoarthritis (OA) are different and obesity, lifestyle, inflammation, cell death mechanisms and diabetes mellitus are among them. The changes in the biological mechanisms are considered as main regulators of OA pathogenesis. The dysregulation of autophagy is observed in different human diseases. During the pathogenesis of OA, the autophagy levels (induction or inhibition) change. The supportive and pro-survival function of autophagy can retard the progression of OA. The protective autophagy prevents the cartilage degeneration. Moreover, autophagy demonstrates interactions with cell death mechanisms and through inhibition of apoptosis and necroptosis, it improves OA. The non-coding RNA molecules can regulate autophagy and through direct and indirect control of autophagy, they dually delay/increase OA pathogenesis. The mitochondrial integrity can be regulated by autophagy to alleviate OA. Furthermore, therapeutic compounds, especially phytochemicals, stimulate protective autophagy in chondrocytes to prevent cell death. The protective autophagy has ability of reducing inflammation and oxidative damage, as two key players in the pathogenesis of OA.

Research Progress on Injectable Microspheres as New Strategies for the Treatment of Osteoarthritis Through Promotion of Cartilage Repair

Osteoarthritis (OA) is a degenerative disease caused by a variety of factors with joint pain as the main symptom, including fibrosis, chapping, ulcers, and loss of cartilage. Traditional treatment can only delay the progression of OA, and classical delivery system have many side effects. In recent years, microspheres have shown great application prospects in the field of OA treatment. Microspheres can support cells, reproduce the natural tissue microenvironment in vitro and in vivo, and are an efficient delivery system for the release of drugs or biological agents, which can promote cell proliferation, migration, and differentiation. Thus, they have been widely used in cartilage repair and regeneration. In this review, preparation processes, basic materials, and functional characteristics of various microspheres commonly used in OA treatment are systematically reviewed. Then it is introduced surface modification strategies that can improve the biological properties of microspheres and discussed a series of applications of microsphere functionalized scaffolds in OA treatment. Finally, based on bibliometrics research, the research development, future potential, and possible research hotspots of microspheres in the field of OA therapy is systematically and dynamically evaluated. The comprehensive and systematic review will bring new understanding to the field of microsphere treatment of OA.

An esterase-cleavable persulfide donor with no electrophilic byproducts and a fluorescence reporter

Hydrogen sulfide (H2S) and associated sulfur species known as persulfide or sulfane sulfur are considered among the first responders to oxidative stress. However, tools that reliably generate these species without any potentially toxic byproducts are limited, and even fewer report the generation of a persulfide. Here, using a latent fluorophore embedded with N-acetylcysteine persulfide, we report a new tool that is cleaved by esterase to produce a persulfide as well as a fluorescence reporter without any electrophilic byproducts. The rate of formation of the fluorescence reporter is nearly identical to the rate of formation of the persulfide suggesting that the use of this probe eliminates the need for secondary assays that report persulfide formation. Symptomatic with persulfide generation, the newly developed donor was able to protect chondrocyte cells from oxidative stress.

Does Chronic Pancreatitis in Growing Pigs Lead to Articular Cartilage Degradation and Alterations in Subchondral Bone?

Chronic pancreatitis (CP), a progressive inflammatory disease, poses diagnostic challenges due to its initially asymptomatic nature. While CP's impact on exocrine and endocrine functions is well-recognized, its potential influence on other body systems, particularly in young individuals, remains underexplored. This study investigates the hypothesis that CP in growing pigs leads to alterations in articular cartilage and subchondral bone, potentially contributing to osteoarthritis (OA) development. Utilizing a pig model of cerulein-induced CP, we examined the structural and compositional changes in subchondral bone, articular cartilage, and synovial fluid. Histological analyses, including Picrosirius Red and Safranin-O staining, were employed alongside immuno-histochemistry and Western blotting techniques. Our findings reveal significant changes in the subchondral bone, including reduced bone volume and alterations in collagen fiber composition. Articular cartilage in CP pigs exhibited decreased proteoglycan content and alterations in key proteins such as MMP-13 and TGF-β1, indicative of early cartilage degradation. These changes suggest a link between CP and musculoskeletal alterations, underscoring the need for further research into CP's systemic effects. Our study provides foundational insights into the relationship between CP and skeletal health, potentially guiding future pediatric healthcare strategies for early CP diagnosis and management.

Protective Effect of Knee Postoperative Fluid on Oxidative-Induced Damage in Human Knee Articular Chondrocytes

The oxidative-stress-elicited deterioration of chondrocyte function is the initial stage of changes leading to the disruption of cartilage homeostasis. These changes entail a series of catabolic damages mediated by proinflammatory cytokines, MMPs, and aggrecanases, which increase ROS generation. Such uncontrolled ROS production, inadequately balanced by the cellular antioxidant capacity, eventually contributes to the development and progression of chondropathies. Several pieces of evidence show that different growth factors, single or combined, as well as anti-inflammatory cytokines and chemokines, can stimulate chondrogenesis and improve cartilage repair and regeneration. In this view, hypothesizing a potential growth-factor-associated action, we investigate the possible protective effect of post-operation knee fluid from patients undergoing prosthesis replacement surgery against ROS-induced damage on normal human knee articular chondrocytes (HKACs). To this end, HKACs were pre-treated with post-operation knee fluid and then exposed to H2O2 to mimic oxidative stress. Intracellular ROS levels were measured by using the molecular probe H2DCFDA; cytosolic and mitochondrial oxidative status were assessed by using HKACs infected with lentiviral particles harboring the redox-sensing green fluorescent protein (roGFP); and cell proliferation was determined by measuring the rate of DNA synthesis with BrdU incorporation. Moreover, superoxide dismutase (SOD), catalase, and glutathione levels from the cell lysates of treated cells were also measured. Postoperative peripheral blood sera from the same patients were used as controls. Our study shows that post-operation knee fluid can counteract H2O2-elicited oxidative stress by decreasing the intracellular ROS levels, preserving the cytosolic and mitochondrial redox status, maintaining the proliferation of oxidatively stressed HKACs, and upregulating chondrocyte antioxidant defense. Overall, our results support and propose an important effect of post-operation knee fluid substances in maintaining HKAC function by mediating cell antioxidative system upregulation and protecting cells from oxidative stress.

Immobilization by 21 days of bed rest results in type II collagen degradation in healthy individuals

OBJECTIVE

To investigate the effects of 21 days of bed rest immobilization (with and without exercise and nutrition interventions) on type II collagen biomarker concentrations in healthy individuals.

DESIGN

Twelve healthy male participants (age 34.2 ± 8.3 years; body mass index 22.4 ± 1.7 kg/m²) were exposed to 6 days ambulatory baseline data collection (BDC), 21 days head-down-tilt bed rest (HDT, CON) + interventions (HDT + resistive vibration exercise (2 times/week, 25 minutes): RVE; HDT + RVE + whey protein (0.6 g/kg body weight/day) and bicarbonate supplementation (90 mmol KHCO3/day: NeX), and 6 days of re-ambulation (R) in a cross-over designed study. The starting HDT condition was randomized (CON-RVE-NEX, RVE-NEX-CON, NEX-CON-RVE). Blood and urine samples were collected before, during, and after HDT. Serum concentrations (s) of CPII, C2C, C1,2C, and urinary concentrations (u) of CTX-II and Coll2-1NO2 were measured.

RESULTS

Twenty-one days of HDT resulted in increased sCPII (p < 0.001), sC2C (p < 0.001), and sC1,2C (p = 0.001) (highest increases: sCPII (+24.2% - HDT5), sC2C (+24.4% - HDT7), sC1,2C (+13.5% - HDT2). sC2C remained elevated at R+1 (p = 0.002) and R+6 (p < 0.001) compared to baseline. NeX led to lower sCPII (p < 0.001) and sC1,2C (p = 0.003) compared to CON. uCTX-II (second void and 24-hour urine) increased during HDT (p < 0.001, highest increase on HDT21: second void +82.8% (p < 0.001); 24-hour urine + 77.8% (p < 0.001). NeX resulted in lower uCTX-II concentrations in 24-hour urine (p = 0.012) compared to CON.

CONCLUSIONS

Twenty-one days of bed rest immobilization results in type II collagen degradation that does not recover within 6 days of resuming ambulation. The combination of resistive vibration exercise and protein/bicarbonate supplementation minimally counteracted this effect.

Therapeutic targets and potential delivery systems of melatonin in osteoarthritis

Osteoarthritis (OA) is a highly prevalent age-related musculoskeletal disorder that typically results in chronic pain and disability. OA is a multifactorial disease, with increased oxidative stress, dysregulated inflammatory response, and impaired matrix metabolism contributing to its onset and progression. The neurohormone melatonin, primarily synthesized by the pineal gland, has emerged as a promising therapeutic agent for OA due to its potential to alleviate inflammation, oxidative stress, and chondrocyte death with minimal adverse effects. The present review provides a comprehensive summary of the current understanding regarding melatonin as a promising pharmaceutical agent for the treatment of OA, along with an exploration of various delivery systems that can be utilized for melatonin administration. These findings may provide novel therapeutic strategies and targets for inhibiting the advancement of OA.

Buffering Mitigates Chondrocyte Oxidative Stress, Metabolic Dysfunction, and Death Induced by Normal Saline: Formulation of a Novel Arthroscopic Irrigant

For decades, surgeons have utilized 0.9% normal saline (NS) for joint irrigation to improve visualization during arthroscopic procedures. This continues despite mounting evidence that NS exposure impairs chondrocyte metabolism and compromises articular cartilage function. We hypothesized that chondrocyte oxidative stress induced by low pH is the dominant factor driving NS toxicity, and that buffering NS to increase its pH would mitigate these effects. Effects on chondrocyte viability, reactive oxygen species (ROS) production, and overall metabolic function were assessed. Even brief exposure to NS caused cell death, ROS overproduction, and disruption of glycolysis, pentose phosphate, and tricarboxylic acid (TCA) cycle pathways. NS also stimulated ROS overproduction in synovial cells that could adversely alter the synovial function and subsequently the entire joint health. Buffering NS with 25 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) significantly increased chondrocyte viability, reduced ROS production, and returned metabolite levels to near control levels while also reducing ROS production in synovial cells. These results confirm that chondrocytes and synoviocytes are vulnerable to insult from the acidic pH of NS and demonstrate that adding a buffering agent to NS averts many of its most harmful effects.

Anti-Inflammatory Activity of APPA (Apocynin and Paeonol) in Human Articular Chondrocytes

Osteoarthritis (OA) is a chronic joint disease leading to cartilage loss and reduction in the joint space which results in pain. The current pharmacological treatment of OA is inadequate and pharmacological interventions focus on symptom management. APPA, a combination of apocynin (AP) and paeonol (PA), is a potential drug for treating OA. The aim of this study was to analyze the effects of APPA on the modulation of the inflammatory response in chondrocytes. Samples were incubated with IL-1β and APPA, and their responses to proinflammatory cytokines, catabolic mediators and redox responses were then measured. The effect of APPA on mitogenesis was also evaluated. Results show that APPA attenuated the expression of IL-8, TNF-α, MMP-3, MMP-13, SOD-2 and iNOS, resulting in the protection of human articular cartilage. APPA decreased PGC-1α gene expression induced by IL-1β. APPA did not modulate the gene expression of Mfn2, Sirt-1 or Sirt-3. The overall findings indicate that APPA may be an effective treatment for OA by targeting several of the pathways involved in OA pathogenesis.

The research landscape of oxidative stress in osteoarthritis from 1998 to 2021: a systematic bibliometric analysis

OBJECTIVE

A substantial body of literature pertaining to oxidative stress in osteoarthritis (OA) has been published over the past few decades. However, a comprehensive systematic analysis in this field is currently lacking. The objective of this study was to perform a bibliometric analysis to visualize the current research hotspots and evolving trends associated with oxidative stress in OA, in order to contribute to a more comprehensive understanding of this field.

METHODS

The raw data pertaining to oxidative stress in OA, published between 1998 and 2021, were obtained from the Web of Science Core Collection database (WoSCC). In order to provide comprehensive results across multiple dimensions, various bibliometric software tools were employed to quantify and analyze the research focuses and trends regarding oxidative stress in OA.

RESULTS

A total of 1178 original articles and reviews on oxidative stress in OA were included, with China and the USA emerging as the primary driving forces in this research field. Notably, Wenzhou Medical University stood out as the most prolific institution in terms of publication volume. Blanco FJ was the most prolific author, and the journal with the most publications was Osteoarthritis and Cartilage. The analysis of keyword burst detection revealed that the investigation of chondrocyte senescence induced by oxidative stress was the most frequent.

CONCLUSION

The burgeoning body of literature pertaining to oxidative stress in OA has experienced a consistent growth over the past few decades, and this field will garner widespread attention and in-depth investigation. The frontier of chondrocyte senescence, as revealed by bibliometric analyses, represents a special focus of this field, with potential as a vital therapeutic target for OA.

Genetic liability for diet-derived circulating antioxidants, oxidative stress, and risk of osteoarthritis: a Mendelian randomization study

Background

Although well-documented, the causal relationships between diet-derived circulating antioxidants, oxidative stress, and osteoarthritis (OA) are equivocal. The objective of this study is to employ two-sample Mendelian randomization (MR) to investigate possible causal relationships among dietary-derived circulating antioxidants, oxidative stress damage indicators, and OA risk.

Methods

Single-nucleotide polymorphisms for diet-derived circulating antioxidants (ascorbate, β-carotene, lycopene, retinol, and α-and γ-tocopherol), assessed as absolute levels and metabolites, as well as oxidative stress injury biomarkers (GSH, GPX, CAT, SOD, albumin, and total bilirubin), were retrieved from the published data and were used as genetic instrumental variables. Summary statistics for gene-OA associations were obtained from publicly available and two relatively large-scale GWAS meta-analyses to date. The inverse-variance weighting method was utilized as the primary MR analysis. Moreover, multivariable MR was used to determine if mediators (BMI and smoking) causally mediated any connection. Furthermore, for each exposure, MR analyses were conducted per outcome database and then meta-analyzed.

Results

Genetically predicted absolute retinol level was causally associated with hip OA risk [odds ratios (ORs) = 0.40, 95% confidence interval (CI) = 0.24-0.68, FDR-corrected p = 0.042]. Moreover, genetically predicted albumin level was causally associated with total OA risk (OR = 0.80, 95% CI = 0.75-0.86, FDR-corrected p = 2.20E-11), as well as the risk of hip OA (OR = 0.75, 95% CI = 0.68-0.84, FDR-corrected p = 1.38E-06) and knee OA (OR = 0.82, 95% CI = 0.76-0.89, FDR-corrected p = 4.49E-06). In addition, MVMR confirmed that the effect of albumin on hip OA is independent of smoking initiation, alcoholic drinks per week, and moderate-to-vigorous physical activity levels but may be influenced by BMI.

Conclusion

Evidence from our study supports a potentially protective effect of high levels of retinol and albumin on OA risk.

Physical activity modifies the association of the composite dietary antioxidant index with all-cause mortality in the US osteoarthritis population

Background

It remains unclear how antioxidant intake affects all-cause mortality in osteoarthritis (OA) patients. In this prospective cohort study, we aim to explore the association of the Composite Dietary Antioxidant Index (CDAI) with all-cause mortality and investigate the interaction of physical activity (PA) and CDAI on all-cause mortality in OA populations.

Methods

A total of 3,197 adults with OA in the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2018 were included in this study. Death outcomes were obtained from National Death Index (NDI) records. Multivariable Cox regression analyses with cubic spines were applied to estimate the association of CDAI with all-cause mortality. The interaction between CDAI and PA on all-cause mortality was further assessed in stratified analysis and interaction tests.

Results

The hazard ratios for all-cause mortality were 0.95 (0.77-1.17) for Q2, 0.75 (0.59-0.97) for Q3, and 0.71 (0.55-0.92) for Q4 (P for trend <0.001), compared with the lowest quartile of CDAI. A negative linear association was found between CDAI and all-cause mortality. In the stratified analyses, CDAI was negatively associated with all-cause mortality in the insufficient PA group. While in the low and sufficient PA group, there were nonlinear relationships of CDAI with all-cause mortality.

Conclusion

A negative linear relationship was observed between CDAI and all-cause mortality in OA patients, and this association was significantly modified by PA. Higher intake of dietary antioxidants might be the interventional objective to reduce the risk of all-cause mortality in the US OA population.

Knee osteoarthritis: Current status and research progress in treatment (Review)

Knee osteoarthritis (KOA) is a common chronic articular disease worldwide. It is also the most common form of OA and is characterized by high morbidity and disability rates. With the gradual increase in life expectancy and ageing population, KOA not only affects the quality of life of patients, but also poses a burden on global public health. OA is a disease of unknown etiology and complex pathogenesis. It commonly affects joints subjected to greater loads and higher levels of activity. The knee joint, which is the most complex joint of the human body and bears the greatest load among all joints, is therefore most susceptible to development of OA. KOA lesions may involve articular cartilage, synovium, joint capsule and periarticular muscles, causing irreversible articular damage. Factors such as mechanical overload, inflammation, metabolism, hormonal changes and ageing serve key roles in the acceleration of KOA progression. The clinical diagnosis of KOA is primarily based on combined analysis of symptoms, signs, imaging and laboratory examination results. At present, there is no cure for KOA and the currently available therapies primarily focus on symptomatic treatment and delay of disease progression. Knee replacement surgery is typically performed in patients with advanced disease. The current study presents a review of epidemiological characteristics, risk factors, histopathological manifestations, pathogenesis, diagnosis, treatment modalities and progress in KOA research.

Dietary total antioxidant capacity is associated with lower disease severity and inflammatory and oxidative stress biomarkers in patients with knee osteoarthritis

BACKGROUND

This study was designed to evaluate the association between dietary total antioxidant capacity and clinical and biochemical variables in patients with osteoarthritis.

METHODS

This cross-sectional study was conducted among 160 patients with mild-to-moderate knee osteoarthritis. The Likert version of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC Index) was used to assess the severity of clinical symptoms in patients with knee osteoarthritis. The secondary outcomes included inflammatory and oxidative stress biomarkers. The participants' usual diets were assessed using a food frequency questionnaire (FFQ), and the dietary total antioxidant capacity (TAC) was calculated based on the ferric reducing antioxidant power method. Additionally, clinical and biochemical variables were evaluated using standard methods.

RESULTS

The mean age of the participants was 57.2 ± 8.1 years, and 55.6% of them were females. The dietary TAC scores in this study ranged from 3.67 to 24.72, with a mean of 12.05 ± 5.3. We found a significant inverse trend between the dietary TAC score and the total Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score (P = 0.001), as well as the WOMAC stiffness (P = 0.008) and WOMAC physical function scores (P = 0.001). Furthermore, dietary TAC was inversely associated with serum concentrations of interleukin-6 (IL-6) (β = - 0.18, P = 0.020), tumor necrosis factor-α (TNF-α) (β = - 0.67, P < 0.001), matrix metalloproteinase-1 (MMP-1) (β = - 0.33, P < 0.001), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) (β = - 0.22, P = 0.005) levels.

CONCLUSION

The results of this study demonstrate an inverse association between dietary total antioxidant capacity and clinical and biochemical variables in patients with osteoarthritis.

Bioinformatics identification and integrative analysis of ferroptosis-related key lncRNAs in patients with osteoarthritis

BACKGROUND

Ferroptosis and dysregulation of long non-coding RNA (lncRNA) have been described to be strictly relevant to the pathogenesis of osteoarthritis (OA). However, the connection between ferroptosis and lncRNA in OA is poorly appreciated. Herein, we investigated the functional contribution of lncRNA markers correlated with the progression of human OA by comprehensive bioinformatics analysis of a panoramic network of competing endogenous RNA (ceRNA) based on ferroptosis-related genes (FRGs).

METHODS

FRGs-related competing endogenous RNA (ceRNA) networks were generated using differentially expressed genes based on OA-related whole transcriptome data from the Gene Expression Omnibus (GEO) database via starBase, miRTarBase, and miRWalk databases. The pivotal lncRNAs were ascertained by topological features (degree, betweenness, and closeness) and subceRNA networks were re-visualized. The expression difference of pivotal lncRNAs was verified by quantitative real-time polymerase chain reaction (qRT-PCR). The latent molecular mechanisms of the global ceRNA and subceRNA networks were uncovered by the R package clusterProfiler-based enrichment analysis.

RESULTS

A total of 98 dysregulated lncRNA-miRNA-mRNA regulatory relationships were attained in the FRGs-related panoramic ceRNA network of OA, covering 26 mRNAs, 20 miRNAs, and 20 lncRNAs. Three lncRNAs (AC011511.5, AL358072.1, and C9orf139) were ascertained as the central lncRNAs in the panoramic ceRNA network. Functional ensemble analysis illustrated that both the panoramic ceRNA network and the subceRNA network were integrally affiliated with the immune-inflammatory response, oxygen homeostasis, and cell death (apoptosis, autophagy, and ferroptosis).

CONCLUSION

Comprehensive bioinformatics analysis of the FRGs-related ceRNA network determined three molecular biomarkers of lncRNAs that might be affiliated with OA progression.

Biomimetic Hyaluronic Acid-Based Brush Polymers Modulate Chondrocyte Homeostasis via ROS/Ca2+/TRPV4

Bionic mimics using natural cartilage matrix molecules can modulate the corresponding metabolic activity by improving the microenvironment of chondrocytes. A bionic brush polymer, HA/PX, has been found to reverse the loss of cartilage extracellular matrix (ECM) and has promising applications in the clinical treatment of osteoarthritis (OA). However, the unknown bioremediation mechanism of HA/PX severely hinders its clinical translation. In OA, the massive loss of the ECM may be attributed to a decrease in transient receptor potential vanilloid 4 (TRPV4) activity, which affects reactive oxygen species (ROS) clearance and [Ca2+]i signaling, initiating downstream catabolic pathways. In this study, we investigated the bioremediation mechanism of HA/PX in a model of interleukin 1β (IL-1β)-induced inflammation. Through TRPV4, HA/PX reduced ROS accumulation in chondrocytes and enhanced [Ca2+]i signaling, reflecting a short-term protection capacity for chondrocytes. In addition, HA/PX balanced the metabolic homeostasis of chondrocytes via TRPV4, including promoting the secretion of type II collagen (Col-II) and aggrecan, the major components of the ECM, and reducing the expression of matrix metal-degrading enzyme (MMP-13), exerting long-term protective effects on chondrocytes. Molecular dynamics (MD) simulations showed that HA/PX could act as a TRPV4 activator. Our results suggest that HA/PX can regulate chondrocyte homeostasis via ROS/Ca2+/TRPV4, thereby improving cartilage regeneration. Because the ECM is a prevalent feature of various cell types, HA/PX holds promising potential for improving regeneration and disease modification for not only cartilage-related healthcare but many other tissues and diseases.

An Integrated View of Stressors as Causative Agents in OA Pathogenesis

Cells in the body are exposed to dynamic external and internal environments, many of which cause cell damage. The cell's response to this damage, broadly called the stress response, is meant to promote survival and repair or remove damage. However, not all damage can be repaired, and sometimes, even worse, the stress response can overtax the system itself, further aggravating homeostasis and leading to its loss. Aging phenotypes are considered a manifestation of accumulated cellular damage and defective repair. This is particularly apparent in the primary cell type of the articular joint, the articular chondrocytes. Articular chondrocytes are constantly facing the challenge of stressors, including mechanical overloading, oxidation, DNA damage, proteostatic stress, and metabolic imbalance. The consequence of the accumulation of stress on articular chondrocytes is aberrant mitogenesis and differentiation, defective extracellular matrix production and turnover, cellular senescence, and cell death. The most severe form of stress-induced chondrocyte dysfunction in the joints is osteoarthritis (OA). Here, we summarize studies on the cellular effects of stressors on articular chondrocytes and demonstrate that the molecular effectors of the stress pathways connect to amplify articular joint dysfunction and OA development.

Implication of Cellular Senescence in Osteoarthritis: A Study on Equine Synovial Fluid Mesenchymal Stromal Cells

Osteoarthritis (OA) is described as a chronic degenerative disease characterized by the loss of articular cartilage. Senescence is a natural cellular response to stressors. Beneficial in certain conditions, the accumulation of senescent cells has been implicated in the pathophysiology of many diseases associated with aging. Recently, it has been demonstrated that mesenchymal stem/stromal cells isolated from OA patients contain many senescent cells that inhibit cartilage regeneration. However, the link between cellular senescence in MSCs and OA progression is still debated. In this study, we aim to characterize and compare synovial fluid MSCs (sf-MSCs), isolated from OA joints, with healthy sf-MSCs, investigating the senescence hallmarks and how this state could affect cartilage repair. Sf-MSCs were isolated from tibiotarsal joints of healthy and diseased horses with an established diagnosis of OA with an age ranging from 8 to 14 years. Cells were cultured in vitro and characterized for cell proliferation assay, cell cycle analysis, ROS detection assay, ultrastructure analysis, and the expression of senescent markers. To evaluate the influence of senescence on chondrogenic differentiation, OA sf-MSCs were stimulated in vitro for up to 21 days with chondrogenic factors, and the expression of chondrogenic markers was compared with healthy sf-MSCs. Our findings demonstrated the presence of senescent sf-MSCs in OA joints with impaired chondrogenic differentiation abilities, which could have a potential influence on OA progression.

NADPH oxidase 4 deficiency attenuates experimental osteoarthritis in mice

OBJECTIVE

Low-grade inflammation plays a pivotal role in osteoarthritis (OA) through exposure to reactive oxygen species (ROS). In chondrocytes, NADPH oxidase 4 (NOX4) is one of the major ROS producers. In this study, we evaluated the role of NOX4 on joint homoeostasis after destabilisation of the medial meniscus (DMM) in mice.

METHODS

Experimental OA was simulated on cartilage explants using interleukin-1β (IL-1β) and induced by DMM in wild-type (WT) and NOX4 knockout (NOX4^-/-) mice. We evaluated NOX4 expression, inflammation, cartilage metabolism and oxidative stress by immunohistochemistry. Bone phenotype was also determined by micro-CT and histomorphometry.

RESULTS

Whole body NOX4 deletion attenuated experimental OA in mice, with a significant reduction of the OARSI score at 8 weeks. DMM increased total subchondral bone plate (SB.Th), epiphysial trabecular thicknesses (Tb.Th) and bone volume fraction (BV/TV) in both NOX4^-/- and wild-type (WT) mice. Interestingly, DDM decreased total connectivity density (Conn.Dens) and increased medial BV/TV and Tb.Th only in WT mice. Ex vivo, NOX4 deficiency increased aggrecan (AGG) expression and decreased matrix metalloproteinase 13 (MMP13) and collagen type I (COL1) expression. IL-1β increased NOX4 and 8-hydroxy-2'-deoxyguanosine (8-OHdG) expression in WT cartilage explants but not in NOX4^-/-. In vivo, absence of NOX4 increased anabolism and decreased catabolism after DMM. Finally, NOX4 deletion decreased synovitis score, 8-OHdG and F4/80 staining following DMM.

CONCLUSION

NOX4 deficiency restores cartilage homoeostasis, inhibits oxidative stress, inflammation and delays OA progression after DMM in mice. These findings suggest that NOX4 represent a potential target to counteract for OA treatment.

Dendrobine Alleviates Cellular Senescence and Osteoarthritis via the ROS/NF-κB Axis

Osteoarthritis (OA) is a degenerative joint disease characterized by low-grade inflammation and cartilage degradation. Dendrobine (DEN) is reported to inhibit inflammation and oxidative stress in some diseases, but its role in chondrocyte senescence and OA progress has not yet been elucidated. Our study aimed to explore the protective effects of DEN on OA both in vitro and in vivo. We found that DEN inhibited extracellular matrix (ECM) degradation and promoted ECM synthesis. Meanwhile, DEN inhibited senescence-associated secretory phenotype (SASP) factors expression and senescence phenotype in IL-1β-treated chondrocytes. Furthermore, DEN improved mitochondrial function and reduced the production of intracellular reactive oxygen species (ROS). Also, DEN suppressed IL-1β-induced activation of the NF-κB pathway. Further, using NAC (ROS inhibitor), we found that DEN might inhibit NF-κB cascades by reducing ROS. Additionally, X-ray, micro-CT, and histological analyses in vivo demonstrated that DEN significantly alleviated cartilage inflammation, ECM degradation, and subchondral alterations in OA progression. In conclusion, DEN inhibits SASP factors expression and senescence phenotype in chondrocytes and alleviated the progression of OA via the ROS/NF-κB axis, which provides innovative strategies for the treatment of OA.

Biological Functions of Selenoprotein Glutathione Peroxidases (GPXs) and their Expression in Osteoarthritis

Purpose

In order to further study the biological functions of glutathione peroxidases (GPXs) and their expression level in patients with osteoarthritis (OA), we fully explored the potential relationship between GPXs and OA. This will provide new ideas for basic biological studies and therapeutic strategies for OA patients.

Patients and Methods

In this study, bioinformatics techniques were used to explore the biological functions of five GPXs. The core genes related to the biological functions of GPXs were identified by constructing a protein-protein interaction network (PPI). In addition, we utilized microarray data in public databases to analyze the expression levels of GPXs in OA patients and healthy controls. Finally, we used quantitative real-time polymerase chain reaction (qRT-PCR) to detect the expression of GPXs in OA patients and controls to validate our bioinformatic analysis results.

Results

Enrichment analysis showed GPXs were mainly enriched in the glutathione metabolic pathway and participate in the biological process of oxidative stress response, and further play an antioxidant role. The PPI network indicated that superoxide dismutase 1 (SOD1), superoxide dismutase 2(SOD2) and catalase (CAT) were the core proteins of this network. GPX1 was regulated by the greatest number of miRNAs. Experiments showed that the expression of GPX1 was elevated in OA patients compared with controls.

Conclusion

GPXs play an important antioxidant role in oxidative stress response. The expression of GPX1 was elevated in peripheral blood mononuclear cells (PBMCs) of OA patients. The changes of GPXs in OA patients may regulate the level of oxidative stress, which may influence synovial lesions and chondrocyte apoptosis.

Naturally derived injectable hydrogels with ROS-scavenging property to protect transplanted stem cell bioactivity for osteoarthritic cartilage repair

Intra-articular injection of adipose mesenchymal stem cells (ADSCs) is a potential alternative to the treatment of osteoarthritis (OA) and has aroused great interest of clinical researchers. However, the hostile microenvironment in the joint cavity, characterized by reactive oxygen species (ROS) accumulation and excessive inflammation, disturbs the bioactivity of the transplanted stem cells. The (-)-epigallocatechin-3-O-gallate (EGCG), a green tea catechin, has attracted the researchers' attention owing to its powerful ROS-scavenging and antioxidant properties. In this study, to avoid rapid degradation and/or depletion of EGCG, we prepare a long-lasting injectable hydrogel by EGCG and hyaluronic acid (HA). The naturally derived hydrogels with excellent biocompatibility and durable retention time can capture the redundant ROS continuously and efficiently, thus protecting ADSCs from ROS-mediated death and bioactivity inhibition, including cell survival, proliferation and chondrogenic differentiation. Intra-articular injection of this ADSCs loaded hydrogel significantly induced synovial macrophages polarization to M2 phenotype, decreased pro-inflammatory cytokines (e.g., IL-1β, MMP-13, and TNF-α) expression, promoted cartilage matrix formation, and repaired cartilage destruction in OA. This stem cell-protected hydrogel delivery strategy showed superior efficacy than ADSCs delivering or EGCG-HA injection singly, which providing a potential alternative strategy for OA management.