Clinical indications associated with new opioid use for pain management in the United Kingdom: using national primary care data

ABSTRACT

Prescription opioids for noncancer pain in the United Kingdom have increased over the past 2 decades, alongside associated harms. Policies addressing opioid prescribing must be tailored to individual patient needs with specific disease systems. The aim of this study was to evaluate clinical conditions associated with new opioid initiation in noncancer pain using nationally representative UK data. Primary care electronic health records from January 1, 2006, to September 31, 2021, were used from the Clinical Research Practice Datalink to identify incident opioid prescriptions. Patient histories were reviewed using code lists for opioid-related conditions with a 5-year look-back for chronic conditions and a 1-year look-back for surgical indications before opioid initiation. In total, 3,030,077 new opioid use episodes in 2,027,402 patients were identified, with 61% being women, 77% aged 45 years and older, and 48% from the highest deprivation quintile. Ten systems associated with opioid initiation were identified, which were not mutually exclusive, as patients could have opioids prescribed for multiple indications. The most common were musculoskeletal (80.8%), respiratory (57.6%), infections (30.4%), trauma/injury (20.4%), neurology (19.9%), and postsurgical indications (5.5%). Osteoarthritis (60.7%) and low back pain (41.0%) were the most frequent musculoskeletal conditions. Orthopedic surgeries accounted for 41.2% of all postsurgical indications. This is the first study in the United Kingdom evaluating large-scale national data to assess indications associated with opioid initiation. Nearly 3 quarters of new opioid prescriptions for noncancer pain were in patients with musculoskeletal conditions, often for conditions with limited evidence for opioid efficacy. These findings could inform targeted interventions and future policies to support nonpharmacological interventions in the most common conditions where opioid harms outweigh benefits.

Recent advances in osteoarthritis research: A review of treatment strategies, mechanistic insights, and acupuncture

Osteoarthritis (OA) is a chronic joint condition affecting millions worldwide, characterized by the gradual degeneration of joint cartilage, leading to pain, stiffness, and functional impairment. Although the pathogenesis of OA is not fully understood, the roles of inflammation, metabolic dysregulation, and biomechanical stress are increasingly recognized. Current treatments, including pharmacotherapy, physical therapy, and surgical interventions, aim to alleviate symptoms and improve quality of life, yet they face limitations and challenges. In recent years, researchers have explored a variety of new treatment strategies, such as molecular targeted therapy, biologic treatments, regenerative medicine, and lifestyle modifications, aiming to directly address the root causes and complex mechanisms of OA. This review aims to summarize the latest research advancements to provide fresh perspectives for clinical treatment and lay the foundation for future research and development of treatment strategies for OA.

The Etiology of Reduced Muscle Mass with Surgical and Pharmacological Weight Loss and the Identification of Potential Countermeasures

Obesity represents a major health crisis in the United States, significantly increasing risks for chronic diseases and generating substantial economic costs. While bariatric surgery and pharmacological interventions such as GLP-1 receptor agonists have been proven effective in achieving substantial weight loss and improving comorbid conditions, they also raise concerns about the unintended loss of fat-free mass, particularly muscle. This loss of muscle mass compromises physical functionality, quality of life, and long-term metabolic health, particularly in individuals with sarcopenic obesity or those at risk of frailty. To sustain strength, mobility, and metabolic function during weight loss interventions, the preservation of muscle mass is essential. However, current weight-loss strategies often fail to adequately address the need to maintain fat-free mass. This review explores the physiological mechanisms governing muscle mass, the impact of obesity and rapid weight loss on muscle protein turnover, and nutritional and age-based strategies that may help protect muscle during intentional weight reduction. By focusing on these critical countermeasures, this review aims to inform future clinical practice and research initiatives with the long-term goal of achieving effective weight loss through reduction in fat tissue while preserving skeletal muscle mass, enhancing health outcomes, and long-term functionality in patients undergoing significant weight reduction.

Hck promotes IL-1β-induced extracellular matrix degradation, inflammation, and apoptosis in osteoarthritis via activation of the JAK-STAT3 signaling pathway

We investigated role of haematopoietic cell kinase (Hck) in osteoarthritis (OA) and to explore the underlying mechanisms driving its effects. An OA animal model was established and after OA induction, rats received intra-articular injections of lentivirus twice a week for four weeks. Rats were divided into four groups: control (healthy rats without OA), OA model (rats with induced OA), OA + Len-si-NC (OA rats treated with a non-targeting control lentivirus), and OA + Len-si-Hck (OA rats treated with lentivirus targeting Hck). Blood samples were collected, and serum cytokine levels were measured using ELISA. Afterward, the rats were sacrificed for histological analysis and TUNEL assay. In vitro, IL-1β-treated human chondrocytes were transfected with Hck, and the effects on cell viability, apoptosis, ECM degradation, and JAK-STAT3 signaling were assessed. Colivelin, a JAK-STAT3 agonist, was used to confirm the pathway's involvement. Results indicated increased Hck expression in the cartilage tissues of OA rats and in IL-1β-stimulated chondrocytes. Silencing Hck in vivo reduced IL-6 and TNF-α levels, apoptosis, and preserved cartilage structure. In vitro, Hck knockdown in IL-1β-treated chondrocytes resulted in enhanced cell viability, reduced apoptosis, and decreased ECM degradation. Notably, the expression of MMP3 and MMP13 was significantly lowered, while collagen II and aggrecan levels were restored. Additionally, Hck knockdown inhibited JAK-STAT3 activation, which was evident from reduced levels of phosphorylated JAK1 and STAT3. The addition of colivelin reversed these effects, confirming that Hck mediates its effects through the JAK-STAT3 pathway. Overall, our findings indicate that Hck is critical in OA progression by promoting inflammation, apoptosis, and ECM degradation through the JAK-STAT3 signaling pathway activation.

Cellular and molecular mechanisms underlying obesity in degenerative spine and joint diseases

Degenerative spine and joint diseases, including intervertebral disc degeneration (IDD), ossification of the spinal ligaments (OSL), and osteoarthritis (OA), are common musculoskeletal diseases that cause pain or disability to the patients. However, the pathogenesis of these musculoskeletal disorders is complex and has not been elucidated clearly to date. As a matter of fact, the spine and joints are not independent of other organs and tissues. Recently, accumulating evidence demonstrates the association between obesity and degenerative musculoskeletal diseases. Obesity is a common metabolic disease characterized by excessive adipose tissue or abnormal adipose distribution in the body. Excessive mechanical stress is regarded as a critical risk factor for obesity-related pathology. Additionally, obesity-related factors, mainly including lipid metabolism disorder, dysregulated pro-inflammatory adipokines and cytokines, are reported as plausible links between obesity and various human diseases. Importantly, these obesity-related factors are deeply involved in the regulation of cell phenotypes and cell fates, extracellular matrix (ECM) metabolism, and inflammation in the pathophysiological processes of degenerative spine and joint diseases. In this study, we systematically discuss the potential cellular and molecular mechanisms underlying obesity in these degenerative musculoskeletal diseases, and hope to provide novel insights for developing targeted therapeutic strategies.

Disentangling the detrimental effects of local from systemic adipose tissue dysfunction on articular cartilage in the knee

OBJECTIVE

Obesity increases osteoarthritis (OA) risk due to adipose tissue dysfunction with associated metabolic syndrome and excess weight. Lipodystrophy syndromes exhibit systemic metabolic and inflammatory abnormalities similar to obesity without biomechanical overloading. Here, we used lipodystrophy mouse models to investigate the effects of systemic versus intra-articular adipose tissue dysfunction on the knee.

METHODS

Intra-articular adipose tissue development was studied using reporter mice. Mice with selective lipodystrophy of intra-articular adipose tissue were generated by conditional knockout (cKO) of Bscl2 in Gdf5-lineage cells, and compared with whole-body Bscl2 knockout (KO) mice with generalised lipodystrophy and associated systemic metabolic dysfunction. OA was induced by surgically destabilising the medial meniscus (DMM) and obesity by high-fat diet (HFD). Gene expression was analysed by quantitative RT-PCR and tissues were analysed histologically.

RESULTS

The infrapatellar fat pad (IFP), in contrast to overlying subcutaneous adipose tissue, developed from a template established from the Gdf5-expressing joint interzone during late embryogenesis, and was populated shortly after birth by adipocytes stochastically arising from Pdgfrα-expressing Gdf5-lineage progenitors. While female Bscl2 KO mice with generalised lipodystrophy developed spontaneous knee cartilage damage, Bscl2 cKO mice with intra-articular lipodystrophy did not, despite the presence of synovial hyperplasia and inflammation of the residual IFP. Furthermore, male Bscl2 cKO mice showed no worse cartilage damage after DMM. However, female Bscl2 cKO mice showed increased susceptibility to the cartilage-damaging effects of HFD-induced obesity.

CONCLUSION

Our findings emphasise the prevalent role of systemic metabolic and inflammatory effects in impairing cartilage homeostasis, with a modulatory role for intra-articular adipose tissue.

The Intra-Articular Delivery of a Low-Dose Adeno-Associated Virus-IL-1 Receptor Antagonist Vector Alleviates the Progress of Arthritis in an Osteoarthritis Rat Model

Background/Objectives: Interleukin-1 (IL-1) is a pivotal mediator in the pathological progression of osteoarthritis (OA), playing a central role in disease progression. However, the rapid clearance of IL-1 receptor antagonist (IL-1Ra) from the joints may hinder the efficacy of intra-articular IL-1Ra injections in reducing OA-associated pain or cartilage degradation. Methods: Sustaining sufficient levels of IL-1Ra within the joints via adeno-associated virus (AAV)-mediated gene therapy presents a promising therapeutic strategy for OA. In this study, we constructed an IL-1Ra expression cassette employing intron insertion in the coding sequence (CDS) region to enhance protein expression levels. Furthermore, we incorporated precisely targeted liver-specific microRNA (miRNA) sequences to specifically downregulate transgene expression within hepatic tissues, thereby ensuring more targeted and controlled regulation of gene expression. Results: A rat model of OA was employed to compare the efficacy of AAV5 and AAV9 for IL-1Ra delivery at both high and low doses. It was observed that low-dose, but not high-dose, AAV9-IL-1Ra resulted in a significant reduction in joint swelling, accompanied by a decrease in the diameter of the affected area and the preservation of biomarkers associated with trabecular bone integrity. Conclusions: These results highlight the great potential of AAV9-IL-1Ra in osteoarthritis therapy, with the promise of achieving long-term improvement through a single intra-articular injection.

The Five-Year Incidence of Progression to Osteoarthritis and Total Joint Arthroplasty in Patients Prescribed Glucagon-Like Peptide 1 Receptor Agonists

BACKGROUND

Research has suggested that glucagon-like peptide-1 receptor agonists (GLP-1-RAs) may have therapeutic effects on osteoarthritis of the hip and knee, in addition to managing diabetes and obesity. However, there is a lack of understanding regarding the association between GLP-1-RA use and the diagnosis of osteoarthritis (OA) of the hip and knee.

METHODS

A collaborative network analytics platform was queried for obese diabetic (n = 1,094,198), obese nondiabetic (n = 916,235), and nonobese diabetic (n = 157,305) patients who had an index visit between 2015 and 2017. Patients who had pre-existing hip and/or knee OA were excluded. A 1:1 propensity score matching was used to balance GLP-1-RA use in stratified cohorts for age, sex, race, body mass index, and hemoglobin A1c. The primary outcomes were rates of progression to hip OA, knee OA, major joint injections, total hip arthroplasty, and total knee arthroplasty. Cox proportional hazards models determined hazard ratios (HRs) between cohorts prescribed and not prescribed GLP-1-RAs.

RESULTS

All patients had a five-year follow-up. Rates of progression to hip and knee OA were higher among the GLP-1-RA users in both obese diabetic (hip HR: 1.63, 95% confidence interval [CI]: 1.46 to 1.82; knee HR: 1.52, CI: 1.41 to 1.64) and nonobese diabetic (hip HR: 1.78, CI: 1.50 to 2.10; knee HR: 1.58, CI: 1.39 to 1.80) cohorts. These diabetic cohorts received higher rates of major joint injections, though there was no difference in rates of total hip arthroplasty or total knee arthroplasty. No differences in five-year outcomes were seen when comparing obese, nondiabetic patients who were prescribed GLP-1-RAs with obese, nondiabetic patients not exposed to GLP-1-RAs.

CONCLUSIONS

This five-year analysis found a greater risk of progression to hip and knee OA among obese and non-obese diabetic GLP-1-RA users. Further studies should explore GLP-1-RA effects upon glucose management, weight loss, and lower extremity arthritis development.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Interplay of Glucose Metabolism and Hippo Pathway in Chondrocytes: Pathophysiology and Therapeutic Targets

In this review, we explore the intricate relationship between glucose metabolism and mechanotransduction pathways, with a specific focus on the role of the Hippo signaling pathway in chondrocyte pathophysiology. Glucose metabolism is a vital element in maintaining proper chondrocyte function, but it has also been implicated in the pathogenesis of osteoarthritis (OA) via the induction of pro-inflammatory signaling pathways and the establishment of an intracellular environment conducive to OA. Alternatively, mechanotransduction pathways such as the Hippo pathway possess the capacity to respond to mechanical stimuli and have an integral role in maintaining chondrocyte homeostasis. However, these mechanotransduction pathways can be dysregulated and potentially contribute to the progression of OA. We discussed how alterations in glucose levels may modulate the Hippo pathway components via a variety of mechanisms. Characterizing the interaction between glucose metabolism and the Hippo pathway highlights the necessity of balancing both metabolic and mechanical signaling to maintain chondrocyte health and optimal functionality. Furthermore, this review demonstrates the scarcity of the literature on the relationship between glucose metabolism and mechanotransduction and provides a summary of current research dedicated to this specific area of study. Ultimately, increased research into this topic may elucidate novel mechanisms and relationships integrating mechanotransduction and glucose metabolism. Through this review we hope to inspire future research into this topic to develop innovative treatments for addressing the clinical challenges of OA.

Transcriptomics and metabolomics: Challenges of studying obesity in osteoarthritis

Objective

Obesity is a leading risk factor for both the incidence and progression of osteoarthritis (OA). Omic technologies, including transcriptomics and metabolomics are capable of identifying RNA and metabolite profiles in tissues and biofluids of OA patients. The objective of this review is to highlight studies using transcriptomics and metabolomics that contribute to our understanding of OA pathology in relation to obesity.

Design

We conducted a targeted search of PUBMED for articles, and GEO for datasets, published up to February 13, 2024, screening for those using high-throughput transcriptomic and metabolomic techniques to study human or pre-clinical animal model tissues or biofluids related to obesity-associated OA. We describe relevant studies and discuss challenges studying obesity as a disease-related factor in OA.

Results

Of the 107 publications identified by our search criteria, only 15 specifically used transcriptomics or metabolomics to study joint tissues or biofluids in obesity-related OA. Specific transcriptomic and metabolomic signatures associated with obesity-related OA have been defined in select local joint tissues, biofluids and other biological material. However, considerable challenges exist in understanding contributions of obesity-associated modifications of transcriptomes and metabolomes related to OA, including sociodemographic, anthropometric, dietary and molecular redundancy-related factors.

Conclusions

A number of additional transcriptomic and metabolomic studies are needed to comprehensively understand how obesity affects OA incidence, progression and outcomes. Integration of transcriptome and metabolome signatures from multiple tissues and biofluids, using network-based approaches will likely help to better define putative therapeutic targets that could enable precision medicine approaches to obese OA patients.

Bergenin protects against osteoarthritis by inhibiting STAT3, NF-κB and Jun pathways and suppressing osteoclastogenesis

Osteoarthritis (OA) is a chronic degenerative disease characterized by articular cartilage destruction and subchondral bone reconstruction in the early stages. Bergenin (Ber) is a cytoprotective polyphenol found in many medicinal plants. It has been proven to have anti-inflammatory, antioxidant, and other biological activities, which may reveal its potential role in the treatment of OA. This study aimed to determine the potential efficacy of Ber in treating OA and explore the possible underlying mechanism through network pharmacology and validation experiments. The potential co-targets and processes of Ber and OA were predicted by using network pharmacology, including a Venn diagram for intersection targets, a protein‒protein interaction (PPI) network to obtain key potential targets, and GO and KEGG pathway enrichment to reveal the probable mechanism of action of Ber on OA. Subsequently, validation experiments were carried out to investigate the effects and mechanisms of Ber in treating OA in vitro and vivo. Ber suppressed IL-1β-induced chondrocyte apoptosis and extracellular matrix catabolism by inhibiting the STAT3, NF-κB and Jun signalling pathway in vitro. Furthermore, Ber suppressed the expression of osteoclast marker genes and RANKL-induced osteoclastogenesis. Ber alleviated the progression of OA in DMM-induced OA mice model. These results demonstrated the protective efficacy and potential mechanisms of Ber against OA, which suggested that Ber could be adopted as a potential therapeutic agent for treating OA.

Systemic inflammatory biomarkers are novel predictors of all-cause and cardiovascular mortality in individuals with osteoarthritis: a prospective cohort study using data from the NHANES

BACKGROUND

Chronic inflammation may contribute to increased mortality risk in individuals with osteoarthritis (OA), but research on the prognostic value of inflammatory biomarkers is limited. We aimed to evaluate the associations of the systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI) with all-cause and cardiovascular mortality among US adults with OA.

METHODS

This cohort study included 3545 adults with OA aged ≥ 20 years from the National Health and Nutrition Examination Survey 1999-2020. The SII and SIRI were calculated using complete blood cell count data. Participants were categorized as having a higher or lower SII and SIRI using cutoff points derived by the maximally selected rank statistics method. Cox proportional hazards models, Fine-Gray competing risk regression models and time-dependent receiver operating characteristic (ROC) analysis were used to evaluate the associations between the SII/SIRI and mortality in OA patients.

RESULTS

Over a median follow-up of 5.08 (3.42-9.92) years, 636 (17.94%) deaths occurred, including 149 (4.20%) cardiovascular deaths. According to multivariable-adjusted models involving demographic, socioeconomic, and health factors, OA patients with a higher SII had a twofold greater risk of all-cause mortality than patients with a lower SII (HR 2.01; 95% CI: 1.50-2.68). Similarly, a higher SIRI was associated with an 86% increased risk of all-cause mortality relative to a lower SIRI (HR 1.86; 95% CI: 1.46-2.38). Similar to the trend found with all-cause mortality, patients with an elevated SII and SIRI had a 88% and 67% increased risk of cardiovascular mortality, respectively, compared to patients with a lower SII (HR 1.88; 95% CI: 1.16-3.03) and SIRI (HR 1.67; 95% CI: 1.14-2.44). Time-dependent ROC curves showed that both the SII and SIRI have moderate and valid performance in predicting short- and long-term mortality in patients with OA.

CONCLUSIONS

Higher SII and SIRI values were associated with greater all-cause and cardiovascular mortality among US adults with OA.

Dietary Inflammatory Index and Magnetic Resonance Imaging-Detected Knee Structural Change and Pain: A 10.7-Year Follow-up Study

OBJECTIVE

To determine whether the dietary inflammatory index (DII) scores were associated with knee structural changes and pain over a 10.7-year follow-up.

METHODS

This study used data from a prospective population-based cohort study (mean age 63 years, 51% female) in which 1,099, 875, 768, and 566 participants completed assessments at baseline, 2.6, 5.1, and 10.7 years, respectively. T1-weighted and T2-weighted magnetic resonance imaging was performed to measure cartilage volume (CV) and bone marrow lesions (BMLs) at baseline and 10.7 years. The Western Ontario and McMaster Universities Osteoarthritis Index pain questionnaire was used to measure knee pain at each visit. Pain trajectories ("minimal pain," "mild pain," and "moderate pain") were previously identified. Baseline energy-adjusted DII (E-DII) scores were calculated. Linear, log-binomial regression, linear mixed-effects modeling, and multi-nominal logistic regression were used for analyses.

RESULTS

The mean ± SD E-DII score at baseline was -0.48 ± 1.39. In multivariable analyses, higher E-DII scores were not associated with tibial CV loss or BML size increase except for medial tibial BML size increase. Higher E-DII scores were associated with a higher pain score (β = 0.21; 95% confidence interval [CI] 0.004-0.43) and an increased risk of belonging to the "moderate pain" compared to the "minimal pain" trajectory group (relative risk ratio 1.19; 95% CI 1.02-1.39).

CONCLUSION

A proinflammatory diet, as indicated by a higher DII score, may be associated with a greater pain score and higher risk of more severe pain trajectory over 10 years. However, inconsistent findings related to structural changes suggest a discordance between the potential impact of diet on structural damage and pain in knee OA.

Effect of weight loss on knee joint synovitis over 48 months and mediation by subcutaneous fat around the knee: data from the Osteoarthritis Initiative

BACKGROUND

Obesity influences the development of osteoarthritis via low-grade inflammation. Progression of local inflammation (= synovitis) increased with weight gain in overweight and obese women compared to stable weight. Synovitis could be associated with subcutaneous fat (SCF) around the knee. Purpose of the study was to investigate the effect of weight loss on synovitis progression and to assess whether SCF around the knee mediates the relationship between weight loss and synovitis progression.

METHODS

We included 234 overweight and obese participants (body mass index [BMI] ≥ 25 kg/m2) from the Osteoarthritis Initiative (OAI) with > 10% weight loss (n = 117) or stable overweight (< ± 3% change, n = 117) over 48 months matched for age and sex. In magnetic resonance imaging (MRI) at baseline and 48 months, effusion-synovitis and Hoffa-synovitis using the MRI Osteoarthritis Knee Score (MOAKS) and average joint-adjacent SCF (ajSCF) were assessed. Odds-ratios (ORs) for synovitis progression over 48 months (≥ 1 score increase) were calculated in logistic regression models adjusting for age, sex, baseline BMI, Physical Activity Scale for the Elderly (PASE), and baseline SCF measurements. Mediation of the effect of weight loss on synovitis progression by local SCF change was assessed.

RESULTS

Odds for effusion-synovitis progression decreased with weight loss and ajSCF decrease (odds ratio [OR] = 0.61 and 0.56 per standard deviation [SD] change, 95% confidence interval [CI] 0.44, 0.83 and 0.40, 0.79, p = 0.002 and 0.001, respectively), whereas odds for Hoffa-synovitis progression increased with weight loss and ajSCF decrease (OR = 1.47 and 1.48, CI 1.05, 2.04 and 1.02, 2.13, p = 0.024 and 0.038, respectively). AjSCF decrease mediated 39% of the effect of weight loss on effusion-synovitis progression.

CONCLUSIONS

Effusion-synovitis progression was slowed by weight loss and decrease in local subcutaneous fat. Hoffa-synovitis characterized by fluid in the infrapatellar fat pad increased at the same time, suggesting a decreasing fat pad rather than active synovitis. Decrease in local subcutaneous fat partially mediated the systemic effect of weight loss on synovitis.

Syringic acid promotes cartilage extracellular matrix generation and attenuates osteoarthritic cartilage degradation by activating TGF-β/Smad and inhibiting NF-κB signaling pathway

Osteoarthritis (OA) is a common chronic degenerative disease which is characterized by the disruption of articular cartilage. Syringic acid (SA) is a phenolic compound with anti-inflammatory, antioxidant, and other effects including promoting osteogenesis. However, the effect of SA on OA has not yet been reported. Therefore, the purpose of our study was to investigate the effect and mechanism of SA on OA in a mouse model of medial meniscal destabilization. The expressions of genes were evaluated by qPCR or western blot or immunofluorescence. RNA-seq analysis was performed to examine gene transcription alterations in chondrocytes treated with SA. The effect of SA on OA was evaluated using destabilization of the medial meniscus model of mice. We found that SA had no obvious toxic effect on chondrocytes, while promoting the expressions of chondrogenesis-related marker genes. The results of RNA-seq analysis showed that extracellular matrix-receptor interaction and transforming growth factor-β (TGF-β) signaling pathways were enriched among the up-regulated genes by SA. Mechanistically, we demonstrated that SA transcriptionally activated Smad3. In addition, we found that SA inhibited the overproduction of lipopolysaccharide-induced inflammation-related cytokines including tumor necrosis factor-α and interleukin-1β, as well as matrix metalloproteinase 3 and matrix metalloproteinase 13. The cell apoptosis and nuclear factor-kappa B (NF-κB) signaling were also inhibited by SA treatment. Most importantly, SA attenuated cartilage degradation in a mouse OA model. Taken together, our study demonstrated that SA could alleviate cartilage degradation in OA by activating the TGF-β/Smad and inhibiting NF-κB signaling pathway.

Identification of Key Ubiquitination-Related Genes and Their Association with Immune Infiltration in Osteoarthritis Based on the mRNA-miRNA Network

Osteoarthritis (OA) is a prevalent degenerative joint disease that is closely associated with functions of ubiquitination and immune cells, yet the mechanism remains ambiguous. This study aimed to find core ubiquitination-related genes and their correlative immune infiltration in OA using weighted gene co-expression network analysis (WGCNA). The ubiquitination-related genes, datasets GSE55235 and GSE143514 were obtained from open databases. WGCNA got used to investigate key co-expressed genes. Then, we screened differentially expressed miRNAs by "limma" package in R, and constructed mRNA-miRNA network. We conducted function enrichment analysis on the identified genes. CIBERSORT was then utilized to analyze the relevance between immune infiltration and genes. Lastly, RT-qPCR was further used to verify the prediction of bioinformatics. A sum of 144 ubiquitination-related genes in OA were acquired. Enrichment analysis indicated that obtained genes obviously involved in mTOR pathway to regulate the OA development. GRB2 and SEH1L and L-arginine synergistically regulate the mTOR signaling pathway in OA. Moreover, GRB2 and SEH1L were remarkably bound up with immune cell infiltration. Additionally, GRB2 expression was upregulated and SEH1L level was downregulated in the OA development by RT-qPCR experiment. The present study identified GRB2 and SEH1L as key ubiquitination-related genes which were involved in immune infiltration in OA patients, thereby providing new drug targets for OA.

4,8-Dicarboxyl-8,9-iridoid-1-glycoside inhibits apoptosis in human osteoarthritis chondrocytes via enhanced c-MYC-mediated cholesterol metabolism in vitro

BACKGROUND

Osteoarthritis (OA) is a degenerative disease related to cholesterol metabolism disorders. However, current therapies for OA are insufficient and no convincing disease-modifying OA drugs exist. Therefore, we aimed to elucidate the mechanism by which borojoa iridoid glycoside (BIG) inhibits chondrocyte apoptosis in OA.

METHODS

Borojoa pulp was heated to 70 °C, and the main active substance in borojoa, BIG, was extracted by fractionation at an ultraviolet 254-nm absorption peak. Chondrocytes were identified by immunohistochemistry and visualized by immunofluorescence confocal microscopy. The proliferation of chondrocytes cultured with BIG was determined by MTS assay. The apoptosis of chondrocytes cultured with BIG was tested by Annexin V-FITC/PI, and the cytokine, protein, and cholesterol levels in chondrocytes were detected by ELISA, RT‒qPCR, Western blot, and biochemistry analyses. Protein‒protein interactions were verified by a coimmunoprecipitation (Co-IP) assay.

RESULTS

BIG promoted chondrocyte proliferation and reduced apoptosis in vitro. BIG induced an alteration of the total RNA profiles in chondrocytes, and bioinformatic analysis showed that BIG inhibited chondrocyte apoptosis by promoting c-MYC expression; KEGG analysis confirmed that BIG-inhibited apoptosis was enriched in the cell cycle pathway. Flow cell cycle experiments confirmed that BIG promoted chondrocyte proliferation by significantly increasing the S phase cell number. The c-MYC inhibitor 10058-F4 stimulated the increased expression of IL-1β, IL-6, TNF-α, and AGEs and suppressed the cholesterol metabolism, which promoted chondrocyte apoptosis and autophagy. Co-IP analysis showed that BIG promoted the interaction of c-MYC and CH25H, Bcl-2, which suggests that BIG could inhibit chondrocyte apoptosis in part by enhancing c-MYC-mediated cholesterol metabolism.

CONCLUSIONS

This study confirmed that BIG promotes chondrocyte proliferation and inhibits apoptosis and autophagy, and BIG improving OA is associated with cholesterol metabolism. The results identify a potential mechanism by which BIG enhances c-MYC-mediated CH25H regulation of cholesterol metabolism in vitro and suggest that BIG might be a promising new drug against OA.

Risk of metabolic abnormalities in osteoarthritis: a new perspective to understand its pathological mechanisms

Although aging has traditionally been viewed as the most important risk factor for osteoarthritis (OA), an increasing amount of epidemiological evidence has highlighted the association between metabolic abnormalities and OA, particularly in younger individuals. Metabolic abnormalities, such as obesity and type II diabetes, are strongly linked to OA, and they affect both weight-bearing and non-weight-bearing joints, thus suggesting that the pathogenesis of OA is more complicated than the mechanical stress induced by overweight. This review aims to explore the recent advances in research on the relationship between metabolic abnormalities and OA risk, including the impact of abnormal glucose and lipid metabolism, the potential pathogenesis and targeted therapeutic strategies.

Pro-Inflammatory Biomarkers Combined with Body Composition Display a Strong Association with Knee Osteoarthritis in a Community-Based Study

Knee osteoarthritis (KOA) is one of the most common progressive, age-dependent chronic degenerative joint diseases. KOA often develops as a result of a gradual articular cartilage loss caused by its wear and tear. Numerous studies suggest that the degradation of the knee joint involves inflammatory components. This process is also associated with body composition, particularly being overweight and muscle mass loss. The present study aimed to search for novel circulating KOA inflammatory biomarkers, taking into account body composition characteristics. To this aim, we recruited 98 patients diagnosed and radiologically confirmed with KOA and 519 healthy controls from the Arab community in Israel. A panel of soluble molecules, related to inflammatory, metabolic, and musculoskeletal disorders, was measured by ELISA in plasma samples, while several body composition parameters were assessed with bioimpedance analysis. Statistical analysis, including multivariable logistic regression, revealed a number of the factors significantly associated with KOA, independently of age and sex. The most significant independent associations [OR (95% CI)] were fat body mass/body weight index-1.56 (1.20-2.02), systemic immune-inflammation index-4.03 (2.23-7.27), circulating vaspin levels-1.39 (1.15-1.68), follistatin/FSTL1 ratio-1.32 (1.02-1.70), and activin A/FSTL1 ratio-1.33 (1.01-1.75). Further clinical studies are warranted to confirm the relevance of these KOA-associated biological factors. Hereafter, they could serve as reliable biomarkers for KOA in the general human population.

Low-frequency whole-body vibration can enhance cartilage degradation with slight changes in subchondral bone in mice with knee osteoarthritis and does not have any morphologic effect on normal joints

PURPOSES

To evaluate the effects of low frequency whole-body vibration (WBV) on degeneration of articular cartilage and subchondral bone in mice with destabilization of the medial meniscus (DMM)induced osteoarthritis(OA) and mice with normal knee.

METHODS

Ten-week-old C57BL/6J male mice received DMM on right knees, while the left knees performed sham operation. There were six groups: DMM, SHAM DMM, DMM+WBV,SHAM DMM+WBV, DMM+ NON-WBV and SHAM DMM+NON-WBV. After four weeks, the knees were harvested from the DMM and SHAM DMM group. The remaining groups were treated with WBV (10 Hz) or NON-WBV. Four weeks later, the knees were harvested. Genes, containing Aggrecan(Acan) and CollagenⅡ(Col2a1), Matrix Metalloproteinases 3 and 13(MMP3,13), TNFα and IL6, were measured and staining was also performed. OA was graded with OARSI scores, and tibial plateaubone volume to tissue volume ratio(BV/TV), bone surface area to bone volume ratio (BS/BV), trabecular number(Tb.N) and trabecular thickness separation(TS) between groups were analyzed.

RESULTS

Increased OARSI scores and cartilage degradation were observed after WBV. BV/TV, Tb.N and TS were not significant between the groups. Significant reductions were observed in MMP3, MMP13, Col2a1, Acan, TNFα and IL6 in the DMM+WBV compared to SHAM DMM+WBV group. BV/TV, BS/BV, Tb.N, TS and OARSI scores were not significantly changed in the left knees. IL6 expression in the SHAM DMM+WBV group was significantly increased compared with the SHAM DMM+ NON-WBV group, while Col2a1, Acan and MMP13 expression decreased.

CONCLUSION

WBV accelerated cartilage degeneration and caused slight changes in subchondral bone in a DMM-induced OA model. WBV had no morphologic effect on normal joints.

Identification of Andrographolide as a novel FABP4 inhibitor for osteoarthritis treatment

BACKGROUND AND PURPOSE

Fatty acid binding protein 4 (FABP4) has been identified as a contributor to cartilage degradation in osteoarthritis (OA) patients, and inhibiting FABP4 using small molecules has emerged as a promising approach for developing OA drugs. Our previous research showed that Andrographis paniculata, a medicinal plant, strongly inhibits FABP4 activity. This led us to hypothesize that Andrographis paniculata ingredients might have protective effects on OA cartilage through FABP4 inhibition.

METHODS

We analyzed scRNA-seq data from joint tissue of OA patients (GSE152805; GSE145286) using Scanpy 1.9.1 and Single Cell Portal. We conducted docking analysis of FABP4 inhibitors using Autodock Vina v.1.0.2. We evaluated the anti-FABP4 activity using a fluorescence displacement assay and measured the fatty acid oxidation (FAO) activity using the FAOBlue assay. We used H₂DCF-DA to measure reactive oxygen species (ROS) levels. We studied signaling pathways using bulk RNA sequencing and western blot analysis in human C28/I2 chondrocytes. We evaluated anti-OA activity in monosodium iodoacetate (MIA)-induced rats.

RESULTS

We identified Andrographolide (AP) as a novel FABP4 inhibitor. Bulk RNA-sequencing analysis revealed that FABP4 upregulated FAO and ROS in chondrocytes, which was inhibited by AP. ROS generation activated the NF-κB pathway, leading to overexpression of a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4), which is a responsible factor for cartilage degradation in OA patients. AP inhibited FABP4, thereby reducing the overexpression of ADAMTS4 by inhibiting the NF-κB pathway. In MIA rats, AP treatment reduced the overexpression of ADAMTS4, repaired cartilage and subchondral bone, and promoted cartilage regeneration.

CONCLUSION

Our results indicate that the inhibition of FABP4 activity by AP explains the anti-OA properties of Andrographis paniculata by protecting against cartilage degradation in OA patients. Additionally, our findings suggest that AP may be a promising therapeutic agent for OA treatment due to its ability to alleviate cartilage damage and bone erosion.

Targeting the Inflammatory Hallmarks of Obesity-Associated Osteoarthritis: Towards Nutraceutical-Oriented Preventive and Complementary Therapeutic Strategies Based on n-3 Polyunsaturated Fatty Acids

Obesity (Ob), which has dramatically increased in the last decade, is one of the main risk factors that contribute to the incidence and progression of osteoarthritis (OA). Targeting the characteristics of obesity-associated osteoarthritis (ObOA) may offer new chances for precision medicine strategies in this patient cohort. First, this review outlines how the medical perspective of ObOA has shifted from a focus on biomechanics to the significant contribution of inflammation, mainly mediated by changes in the adipose tissue metabolism through the release of adipokines and the modification of fatty acid (FA) compositions in joint tissues. Preclinical and clinical studies on n-3 polyunsaturated FAs (PUFAs) are critically reviewed to outline the strengths and weaknesses of n-3 PUFAs' role in alleviating inflammatory, catabolic and painful processes. Emphasis is placed on potential preventive and therapeutic nutritional strategies based on n-3 PUFAs, with a focus on ObOA patients who could specifically benefit from reformulating the dietary composition of FAs towards a protective phenotype. Finally, tissue engineering approaches that involve the delivery of n-3 PUFAs directly into the joint are explored to address the perspectives and current limitations, such as safety and stability issues, for implementing preventive and therapeutic strategies based on dietary compounds in ObOA patients.

Preliminary exploration of method for screening efficacy markers compatibility in TCM prescriptions based on Q-markers: Anti-inflammatory activity of Dachaihu decoction as an example

ETHNOPHARMACOLOGICAL RELEVANCE

Dachaihu Decoction (DD), a classic Chinese herbal prescription, is composed of radix of Bupleurum chinense DC. (Chaihu), radix of Scutellaria baicalensis Georgi (Huangqin), radix of Paeonia lactiflora Pall. (Baishao), rhizoma of Pinellia ternata (Thunb.) Breit. (Banxia), fructus of Citrus aurantium L. (Zhishi), rhizoma of Zingiber officinale Rosc. (Shengjiang), fructus of Ziziphus jujuba Mill. (Dazao) and rhizoma of Rheum officinale Baill. (Dahuang). DD has the traditional effects of soothing the liver, relieving depression and clearing heat from the stomach, and is mainly used to treat heat stagnation in the liver and stomach.

AIM OF THE STUDY

Dachaihu decoction (DD), a classic prescription commonly used in clinical practice for the treatment of pancreatitis and cholecystitis. Although its pharmacological effects are clear, the efficacy components and mechanism of action remain intricate and difficult to clarify.

MATERIALS AND METHODS

The action targets and components of the anti-inflammatory activity of DD were predicted by network pharmacology; the effective components and targets were verified by HPLC and qPCR; the efficacy markers of DD were further screened by in vitro experiments; the pharmacological value of DD and its components compatibility were evaluated by in vitro experiments.

RESULTS

The key targets MMP9, JAK2, MAP2K1 and NR3C1 were screened by network pharmacology; HPLC analysis showed that paeoniflorin, naringin, hesperidin, neohesperidin, baicalin, wogonoside, baicalein and saikosaponin B₂ were identified as potential efficacy markers of DD; molecular docking combined with qPCR verification suggested that baicalin, naringin, neohesperidin, hesperidin and baicalein and wogonoside had certain ability to regulate above targets; in vitro studies revealed that paeoniflorin, naringin, hesperidin, neohesperidin, baicalin, wogonoside, baicalein and saikosaponin B₂ could inhibit the release of NO, pancreatic lipase and α-glucosidase; after comprehensive comparison and analysis, naringin, hesperidin, neohesperidin, baicalin, wogonoside, baicalein and saikosaponin B₂ were selected as the efficacy markers of DD; in vivo studies indicated that DD and its efficacy markers (components compatibility) had definite therapeutic effects on guinea pigs with cholecystitis.

CONCLUSIONS

The efficacy markers of DD including naringin, hesperidin, neohesperidin, baicalin, wogonoside, baicalein and saikosaponin B₂ can be used as components compatibility to exert anti-inflammatory activity. In addition, a method for obtaining the compatibility of efficacy markers by simplifying the prescription is initially established.

Associations between obesity, diabetes mellitus, and cardiovascular disease with progression states of knee osteoarthritis (KOA)

BACKGROUND

Data on common comorbidities targeting at different progression states of knee osteoarthritis (KOA) in continuous time are limited.

AIMS

To examine the associations between obesity, diabetes mellitus (DM), and cardiovascular disease (CVD) with the progression of KOA.

METHODS

Data were obtained from the Osteoarthritis Initiative for up to 48 months. Progression states of KOA were defined as (1) normal; (2) asymptomatic radiographic KOA (RKOA, Kellgren-Lawrence grade ≥ 2 in at least one knee); (3) only knee symptoms; (4) symptomatic KOA (SxKOA, a combination of RKOA and knee symptoms in the same knee). A multi-state Markov model was used to investigate the associations while accounting for potential confounders.

RESULTS

Participants with obesity had an increased risk of developing RKOA [normal to asymptomatic RKOA, adjusted hazard ratio (aHR) 1.55, 95% confidence interval (95% CI) (1.07, 2.24); only knee symptoms to SxKOA, aHR 2.25, 95% CI (1.60, 3.18)], and an increased risk of developing knee symptoms [normal to only knee symptoms, aHR 1.45, 95% CI (1.15, 1.83); asymptomatic RKOA to SxKOA, aHR 1.33, 95% CI (1.16, 1.52)]. DM was also significantly associated with development of RKOA or knee symptoms [normal to asymptomatic RKOA, aHR 1.92, 95% CI (1.12, 3.30); normal to only knee symptoms, aHR 1.78, 95% CI (1.12, 2.84)]. Knee symptoms were less likely to be relieved among participants with CVD, compared with those without [only knee symptoms to normal, aHR 0.60, 95% CI (0.38, 0.94)].

CONCLUSIONS

Obesity, DM and CVD are associated with an increased risk for SxKOA progression. Common comorbidities should be considered to prevent KOA development.

The effect of interactions between BMI and sustained depressive symptoms on knee osteoarthritis over 4 years: data from the osteoarthritis initiative

BACKGROUND

To assess the compound effects of BMI and sustained depressive symptoms on changes in knee structure, cartilage composition, and knee pain over 4 years using statistical interaction analyses.

METHODS

One thousand eight hundred forty-four individuals from the Osteoarthritis Initiative Database were analyzed at baseline and 4-year follow-up. Individuals were categorized according to their BMI and presence of depressive symptoms (based on the Center for Epidemiological Studies Depression Scale (threshold≥16)) at baseline and 4-year follow-up. 3 T MRI was used to quantify knee cartilage T₂ over 4 years, while radiographs were used to assess joint space narrowing (JSN). Mixed effects models examined the effect of BMI-depressive symptoms interactions on outcomes of cartilage T₂, JSN, and knee pain over 4-years.

RESULTS

The BMI-depressive symptoms interaction was significantly associated with knee pain (p < 0.001) changes over 4 years, but not with changes in cartilage T₂ (p = 0.27). In women, the BMI-depressive symptoms interaction was significantly associated with JSN (p = 0.01). In a group-based analysis, participants with obesity and depression had significantly greater 4-year changes in knee pain (coeff._{(obesity + depression vs. no_obesity + no_depression)} = 4.09, 95%CI = 3.60-4.58, p < 0.001), JSN (coeff. = 0.60, 95%CI = 0.44-0.77, p < 0.001), and cartilage T₂ (coeff. = 1.09, 95%CI = 0.68-1.49, p < 0.001) than participants without depression and normal BMI.

CONCLUSIONS

The compound effects of obesity and depression have greater impact on knee pain and JSN progression compared to what would be expected based on their individual effects.

Exosomal miR-93-5p regulated the progression of osteoarthritis by targeting ADAMTS9

Osteoarthritis (OA) is a type of common degenerative joint disorder, in which adipose mesenchymal stem cells (ADSCs) and the secreted exosomes play an important role. The purpose of this study was to investigate the role and mechanism of exosomes derived from ADSCs (ADSC-exos) in OA. The gradient of IL-1β concentration was designed to construct the articular chondrocyte model of arthritic mice. The expression of miR-93-5p and ADAMTS9 in articular chondrocytes was detected by reverse transcription quantitative polymerase chain reaction. Dual luciferase reporter gene assay was performed to verify the interaction between them. Monodansylcadaverine staining was used to visualize the autophagosome formation and cell apoptosis was analyzed by flow cytometry. ADSC-exos were authenticated by transmission electron microscope and western blot assay. miR-93-5p was found to be downregulated in IL-1β-treated articular chondrocytes compared with OA cartilage while ADAMTS9 was upregulated, which was identified as a direct target gene of miR-93-5p. Silencing of ADAMTS9 attenuated the effects of miR-93-5p. Exosomal miR-93-5p can reduce the release of inflammatory factors in mouse arthritis cell models. This study first described the mechanism under that ADSC-exos inhibited inflammation and alleviated OA through the innovative targets miR-93-5p/ADAMTS9 signal axis. This provided a new method for the treatment of OA.

Neuromodulation as a Potential Disease-Modifying Therapy for Osteoarthritis

PURPOSE OF REVIEW

The following review discusses the therapeutic potential of targeting the autonomic nervous system (ANS) for osteoarthritis (OA) treatment and encourages the field to consider the candidacy of bioelectronic medicine as a novel OA treatment strategy.

RECENT FINDINGS

The study of OA pathogenesis has focused on changes occurring at the joint level. As such, treatments for OA have been aimed at the local joint environment, intending to resolve local inflammation and decrease pain. However, OA pathogenesis has shown to be more than joint wear and tear. Specifically, OA-related peripheral and central sensitization can prompt neuroplastic changes in the nervous system beyond the articular joint. These neuroplastic changes may alter physiologic systems, like the neuroimmune axis. In this way, OA and related comorbidities may share roots in the form of altered neuroimmune communication and autonomic dysfunction. ANS modulation may be able to modify OA pathogenesis or reduce the impact of OA comorbidities. Moreover, blocking chronic nociceptive drive from the joint may help to prevent maladaptive nervous system plasticity in OA.

Protein Changes After 6 weeks of Walking and the Relationship to Pain in Adults with Knee Osteoarthritis

Background: Knee osteoarthritis (KOA) affects 22.9% of individuals over the age of 40 and causes significant pain and disability. Pain is the most prevalent and troublesome symptom of KOA leading patients to seek medical interventions for relief. Knee osteoarthritis pain has both peripheral and central mechanisms that vary by individual. Non-pharmacological pain management strategies such as walking is the first step in reducing KOA pain. However, initiation of a walking regime can induce knee pain for some and the mechanism by which habitual walking reduces KOA pain is unclear. Purpose: The purpose of this study was to use a discovery proteomics approach and quantitative sensory testing (QST) to determine the molecular changes that occur after habitual walking and their relationship to pain sensitivity. Research Design and Study Sample: We conducted a pre-test/post-test study using QST to measure neurophysiological parameters at the knee and contralateral forearm and examined platelet protein signatures before and after 6 weeks of walking 3 days per week for 30 minutes among six adults with KOA and six healthy controls. Results: Knee pain sensitivity did not change significantly after 6 weeks of walking among either KOA or healthy participants. However, forearm pressure pain sensitivity decreased for both groups after walking, indicating reduction in central pain pathways. Protein signatures showed downregulation of immune and inflammatory, pathways among KOA participants after walking which were upregulated in healthy controls. Conclusion: These differences may contribute differences in centralized pain thresholds seen between KOA and healthy participants.

Does preoperative physiotherapy improve outcomes in patients undergoing total knee arthroplasty? A systematic review

OBJECTIVE

To systematically review the scientific literature and to investigate the effectiveness of preoperative rehabilitation on subjective and objective outcomes after total knee arthroplasty (TKA) when compared with patients in a control group.

DATA SOURCES

A search was conducted in PubMed, PubMed Central, Embase, Cochrane Library and Physiotherapy Evidence Database databases in May 2021.

STUDY SELECTION

randomized controlled trials (RCTs) were reviewed if they compared a preoperative physiotherapy exercise intervention with no intervention group for patients undergoing TKA for severe Osteoarthritis (OA). A total of 24 RCTs were included at the end of the evaluation process. By the end of the evaluation process, a total of 24 RCTs were included.

DATA EXTRACTION

Two authors independently screened the literature, extracted data, and assessed the quality of included studies. The outcomes were knee extension, knee flexion, pain Visual Analogue Scale (VAS), overall Western Ontario and McMaster Universities OA Index, 6 min walking test, and Timed Up and Go test.

RESULTS

The majority of the studies included in this systemic review demonstrated a comparable trend of long-term postoperative improvement of knee extension strength, VAS, range of movement and functional scores, and those of quality of life between two groups. Many studies showed a significant improvement in terms of preoperative pain, length of hospital stay and functional performance shortly after the operation, but all studies failed to show a prolonged effect on knee motion or patient function between 3 and 12 months.

CONCLUSIONS

Low to moderate evidence from mostly small RCTs demonstrated that preoperative physiotherapy interventions reduce pain and improve functional performance for patients with knee OA prior shortly after the TKA.

Correlation of systemic metabolic inflammation with knee osteoarthritis

PURPOSE

The aim of this study was to analyze local and systematic inflammatory status in knee osteoarthritis (KOA), focusing on intra-articular and remote adipose tissue depots, and to explore its potential association with metabolic syndrome (MetS).

METHODS

Patients (n = 27) with end-stage KOA were enrolled in the study and samples from infrapatellar fat pad (IFP), synovium, subcutaneous adipose tissue (SAT), synovial fluid (SF), and serum were collected. In homogenates from the tissues, mRNA expression of developmental endothelial locus-1 (DEL-1) was determined. Interleukin 6 (IL-6) and interleukin 8 (IL-8) were measured in tissues and SF and serum samples by enzyme-linked immunosorbent assay.

RESULTS

Fifteen patients fulfilled MetS criteria (w-MetS group) and 12 did not (non-MetS). In the entire population, IL-6 levels were significantly higher in IFP compared to synovium (median (interquartile range), 26.05 (26.16) vs. 15.75 (14.8) pg/mg of total protein, p = 0.043), but not to SAT (17.89 (17.9) pg/mg); IL-8 levels were significantly higher in IFP (17.3 (19.3) pg/mg) and SAT (24.2 (26) pg/mg) when compared to synovium (8.45 (6.17) pg/mg) (p = 0.029 and < 0.001, respectively). Significantly higher IL-6 concentrations in SF were detected in w-MetS patients compared to non-MetS (194.8 (299) vs. 64.1 (86.9) pg/ml, p = 0.027). Finally, DEL-1 mRNA expression was higher in IFP compared to synovium (eightfold, p = 0.019).

CONCLUSIONS

Our findings support the critical role of IFP in knee joint homeostasis and progression of KOA. Furthermore, in KOA patients w-MetS, SAT is thought to play an important role in intra-knee inflammation via secretion of soluble inflammatory mediators, such as IL-6.

Depressive symptoms and multi-joint pain partially mediate the relationship between obesity and opioid use in people with knee osteoarthritis

OBJECTIVES

To assess the relation of obesity to opioid use in people with or at risk of knee osteoarthritis (OA), and the extent to which this association is mediated by number of painful joints or depressive symptoms.

METHODS

We used data from the Multicenter Osteoarthritis Study, a longitudinal cohort of older adults with or at risk of knee OA. Opioid use was identified by prescription medications and self-report. Obesity was defined as BMI ≥ 30 kg/m2. Multi-joint pain was assessed using a standardized body homunculus, and depressive symptoms using the Center for Epidemiological Studies Depression scale. We quantified the direct and indirect effect of obesity on opioid use through the number of painful joints or depressive symptoms using causal mediation analysis by natural-effects models.

RESULTS

We studied 2,335 participants (mean age: 68; mean BMI 31 kg/m2; 60% women). Persons with obesity had ∼50% higher odds of opioid use than those without. Estimates of indirect (mediated) effect by the number of painful joints and depressive symptoms suggested an increased odds of opioid use by 34% (odds ratio [OR] = 1.34, 95% CI: 1.04, 1.70) and 35% (OR 1.35, 95% CI: 1.05, 1.71), respectively, in obese vs non-obese individuals. The total effect of obesity on opioid use was higher in women than in men.

CONCLUSIONS

Multi-joint pain and depressive symptoms partially explained greater opioid use among obese persons with knee OA, demonstrating that the negative impact of obesity on knee OA extends beyond its influence on knee pain and structural progression.

Innate/Inflammatory Bioregulation of Surfactant Protein D Alleviates Rat Osteoarthritis by Inhibiting Toll-Like Receptor 4 Signaling

Osteoarthritis (OA) is a deteriorating disease of cartilage tissues mainly characterized as low-grade inflammation of the joint. Innate immune molecule surfactant protein D (SP-D) is a member of collectin family of collagenous Ca²⁺-dependent defense lectins and plays a vital role in the inflammatory and innate immune responses. The present study investigated the SP-D-mediated innate/inflammatory bioregulation in OA and explored the underlying molecular mechanism. Transcriptome analysis revealed that SP-D regulated genes were strongly enriched in the inflammatory response, immune response, cellular response to lipopolysaccharide (LPS), PI3K-Akt signaling, Toll-like receptor (TLR) signaling, and extracellular matrix (ECM)-receptor interaction pathways. Knockdown of the SP-D gene by the recombinant adeno-associated virus promoted the macrophage specific markers of CD68, F4/80 and TLR4 in the articular cartilage in vivo. SP-D alleviated the infiltration of synovial macrophages and neutrophils, and inhibited TLR4, TNF-α and the phosphorylation of PI3K, Akt and NF-κB p65 in cartilage. SP-D suppressed cartilage degeneration, inflammatory and immune responses in the rat OA model, whilst TAK-242 strengthened this improvement. In in vitro conditions, SP-D pre-treatment inhibited LPS-induced overproduction of inflammation-correlated cytokines such as IL-1β and TNF-α, and suppressed the overexpression of TLR4, MD-2 and NLRP3. SP-D prevented the LPS-induced degradation of ECM by down-regulating MMP-13 and up-regulating collagen II. Blocking of TLR4 by TAK-242 further enhanced these manifestations. We also demonstrated that SP-D binds to the TLR4/MD-2 complex to suppress TLR4-mediated PI3K/Akt and NF-κB signaling activation in chondrocytes. Taken together, these findings indicate that SP-D has chondroprotective properties dependent on TLR4-mediated PI3K/Akt and NF-κB signaling and that SP-D has an optimal bioregulatory effect on the inflammatory and innate responses in OA.

Adipokine Signaling Pathways in Osteoarthritis

Osteoarthritis (OA) is a debilitating joint disease that affects millions of individuals. The pathogenesis of OA has not been fully elucidated. Obesity is a well-recognized risk factor for OA. Multiple studies have demonstrated adipokines play a key role in obesity-induced OA. Increasing evidence show that various adipokines may significantly affect the development or clinical course of OA by regulating the pro/anti-inflammatory and anabolic/catabolic balance, matrix remodeling, chondrocyte apoptosis and autophagy, and subchondral bone sclerosis. Several signaling pathways are involved but still have not been systematically investigated. In this article, we review the cellular and molecular mechanisms of adipokines in OA, and highlight the possible signaling pathways. The review suggested adipokines play important roles in obesity-induced OA, and exert downstream function via the activation of various signaling pathways. In addition, some pharmaceuticals targeting these pathways have been applied into ongoing clinical trials and showed encouraging results. However, these signaling pathways are complex and converge into a common network with each other. In the future work, more research is warranted to further investigate how this network works. Moreover, more high quality randomised controlled trials are needed in order to investigate the therapeutic effects of pharmaceuticals against these pathways for the treatment of OA. This review may help researchers to better understand the pathogenesis of OA, so as to provide new insight for future clinical practices and translational research.

Continuous care intervention with carbohydrate restriction improves physical function of the knees among patients with type 2 diabetes: a non-randomized study

Background

In a previous study, we assessed a novel, remotely monitored carbohydrate restricted diet regimen including nutritional ketosis in patients with type 2 diabetes and reported significant improvements in weight, glycemic control, abdominal fat and inflammation from baseline to 2 years. Knee outcome measures were collected as a secondary outcome in the trial. This study aims to assess the effect of this intervention on knee functional scores and to identify if changes in weight, central abdominal fat (CAF), glycemic status and high sensitivity C-reactive protein (hsCRP) were associated with its improvement.

Methods

This prospective analysis included continuous care intervention (CCI, n = 173) and usual care (UC, n = 69) trial participants with type 2 diabetes that reported knee pain at baseline. Knee outcome measures included the Knee injury and Osteoarthritis Outcome Score (KOOS) pain, symptoms, activities of daily living (ADL), sports and recreation function, and knee-related quality of life subscales, and total KOOS score were assessed from baseline to 2 years. Missing data at each time point were replaced with multiple imputation under the assumption of missing at random. To assess if the primary analysis of the knee scores changed under plausible missing not at random assumptions, sensitivity analysis was also performed using pattern mixture models. In CCI, we also assessed factors associated with the improvement of knee scores.

Results

In the primary analysis, CCI participants demonstrated a statistically significant improvement in total KOOS and all KOOS individual subscale scores at 1 year and maintained through 2 years as opposed to UC patients who showed no significant changes from baseline to 2 years. The significant improvement in total KOOS and its individual subscale scores from baseline to 2 years remained relatively stable in CCI in the sensitivity analysis under different missing not at random scenarios confirming the robustness of the findings from the primary analysis. Approximately 46% of the CCI participants met the 10 points minimal clinically important change at 2 years. A reduction in CAF was associated with improvement in total KOOS and KOOS ADL, while a decrease in hsCRP was associated with improvement in KOOS symptoms scores.

Conclusion

A very low carbohydrate intervention including nutritional ketosis resulted in significant improvements in knee pain and function among patients with T2D. The improvements in knee function were likely secondary to a reduction in central adiposity and inflammation. Future research on the applicability of this intervention in radiographically confirmed OA patients is important.

Trial registration

Clinical trial registration: NCT02519309 (10/08/2015).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05258-0.

The Efficacy of High-Intensity Preoperative Physiotherapy Training on Postoperative Outcomes in Greek Patients Undergoing Total Knee Arthroplasty: A Quasi-Experimental Study

Purpose: Several studies have shown that patients with severe osteoarthritis (OA) of the knee can reduce their knee pain, improve their quadriceps strength, and improve their functional ability through regular exercise training. The purpose of this study was to investigate the efficacy of a six-week supervised high-intensity preoperative training program on muscle strength, functional performance, and patient-reported outcomes in patients undergoing total knee arthroplasty (TKA).

Methods: Ninety-eight patients scheduled for unilateral TKA for severe OA were allocated to an intervention group (N = 49) who completed a six-week preoperative training program, five days per week prior to surgery, and a control group (N=49) who did not follow any preoperative training program. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Physical Functioning Scale of the Short Form-36 questionnaire (SF-36), Knee Injury and Osteoarthritis Outcome Score (KOOS), quadriceps strength, 20-meter walk test, and 30-second chair stand test were assessed at six weeks before surgery (T0), just before surgery (T1), four weeks (T2) and finally 12 weeks (T3) after TKA.

Results: Of 98 patients included in our study, 10 individuals withdrew from the study at different stages. Finally, 44 patients were allocated to the intervention group and 44 patients to the control group. When comparing the changes from baseline to the primary test points at T1, T2, and T3, we found a significant group difference in favor of the intervention group for quadriceps strength (<0.001, 0.001, 0.009), 20-meter walk test (<0.001, 0.023, 0.032), 30-second chair stand test (0.001, <0.001, <0.001) and all patient-reported outcomes WOMAC (<0.001, 0.001, 0.007) except from KOOS that showed significant difference only at T1 (<0.001) at T2 (0.048) but not at T3 (0.087).

Conclusions: Our study demonstrated that a six-week preoperative physiotherapy training program supervised by a physiotherapist before TKA is efficacious for decreasing knee pain, improving knee function, and enhancing daily living activities.

Associations between adipokines gene polymorphisms and knee osteoarthritis: a meta-analysis

Background

Adipokines gene polymorphisms are speculated to be associated with the risk of knee osteoarthritis (OA), but evidence remains conflicting. This study therefore aimed to examine whether associations exist between adipokines gene polymorphisms and knee OA by considering the evidence collected from eligible studies through a meta-analysis.

Methods

A systematic search was performed on PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang up to March 31, 2020. Meta-analysis was carried out by focusing on the associations between adipokines gene polymorphisms and knee OA with the allele model, dominant model, and recessive model.

Results

The present meta-analysis included 5 eligible studies for ADIPOQ rs1501299 with 1,021 cases and 1,097 controls, 3 eligible studies for ADIPOQ rs2241766 with 549 cases and 544 controls, 3 eligible studies for LEPR rs1137101 with 808 cases and 856 controls, 2 eligible studies for VISFATIN rs4730153 with 339 cases and 680 controls and 2 eligible studies for VISFATIN rs16872158 with 339 cases and 680 controls. Significant association was observed between LEPR rs1137101 and knee OA in the overall population (recessive: OR = 0.40, 95% CI 0.21–0.79). Limited data revealed that associations may exist between ADIPOQ rs2241766 and knee OA in Asians (dominant: OR = 1.35, 95% CI 1.03–1.78), between VISFATIN rs4730153 and knee OA in Asians (allele: OR = 0.58, 95% CI 0.41–0.83; dominant: OR = 0.57, 95% CI 0.39–0.83), and between VISFATIN rs16872158 and knee OA in Asians (allele: OR = 1.84, 95% CI 1.26–2.68; dominant: OR = 1.94, 95% CI 1.31–2.89).

Conclusions

Adipokines gene polymorphisms may be associated with knee OA. The association was observed in LEPR rs1137101 in the present study. In addition, limited data revealed that associations may also exist in ADIPOQ rs2241766, VISFATIN rs4730153 and VISFATIN rs16872158.

Prospero registration

CRD42020187664.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05111-4.

Circular RNA CCDC66 Regulates Osteoarthritis Progression by Targeting miR-3622b-5p

OBJECTIVE

CircCCDC66 is involved in cancer progression, but its role in osteoarthritis (OA) remains unknown. This study was carried out to explore the biological role of circCCDC66 in OA and its underlying mechanism.

METHODS

The expression levels of miR-3622b-5p and circCCDC66 in OA cartilage tissues were detected by qRT-PCR. Cell Counting Kit-8 (CCK8) and flow cytometry were used to detect the chondrocyte viability and apoptosis. The expression of chondrocyte inflammatory factors (IL-6 and TNF-α) was measured by ELISA. The target genes of circCCDC66 and miR-3622b-5p were analyzed by bioinformatics analysis and luciferase reporter gene assay. The relationship between circCCDC66 and miR-3622b-5p was analyzed by bioinformatics analysis and luciferase reporter gene assay.

RESULTS

It was found that circCCDC66 expression in OA cartilage tissues was upregulated. CircCCDC66 overexpression inhibited proliferation and promoted apoptosis of chondrocytes and increased IL-6 and TNF-α levels in chondrocytes. miR-3622b-5p was predicted to be a downstream target gene of circCCDC66, and circCCDC66 overexpression inhibited miR-3622b-5p expression in chondrocytes. Moreover, miR-3622b-5p expression was downregulated in OA cartilage tissues. miR-3622b-5p overexpression increased chondrocyte proliferation, inhibited chondrocyte apoptosis, and enhanced the expression of IL-6 and TNF-α in chondrocytes. In addition, circCCDC66 overexpression enhanced SIRT3 expression in chondrocytes, while miR-3622b-5p overexpression inhibited SIRT3 expression in chondrocytes.

CONCLUSION

CircCCDC66 promoted OA chondrocyte apoptosis by regulating the miR-3622b-5p/SIRT3 axis. CircCCDC66 may be a new therapeutic target of OA.

Dual protective role of velutin against articular cartilage degeneration and subchondral bone loss via the p38 signaling pathway in murine osteoarthritis

Osteoarthritis (OA) is a common degenerative joint condition associated with inflammation and characterized by progressive degradation of the articular cartilage and subchondral bone loss in the early stages. Inflammation is closely associated with these two major pathophysiological changes in OA. Velutin, a flavonoid family member, reportedly exerts anti-inflammatory effects. However, the therapeutic effects of velutin in OA have not yet been characterized. In this study, we explore the effects of velutin in an OA mouse model. Histological staining and micro-CT revealed that velutin had a protective effect against cartilage degradation and subchondral bone loss in an OA mouse model generated by surgical destabilization of the medial meniscus (DMM). Additionally, velutin rescued IL-1β-induced inflammation in chondrocytes and inhibited RANKL-induced osteoclast formation and bone resorption in vitro. Mechanistically, the p38 signaling pathway was found to be implicated in the inhibitory effects of velutin. Our study reveals the dual protective effects of velutin against cartilage degradation and subchondral bone loss by inhibiting the p38 signaling pathway, thereby highlighting velutin as an alternative treatment for OA.

Prevention of Osteoarthritis Progression by Statins, Targeting Metabolic and Inflammatory Aspects: A Review

Background and purpose:

Several traditional risk factors of atherosclerosis such as age, obesity, and altered lipid metabolism are shared with osteoarthritis (OA). Metabolic abnormalities and atheromatous vascular disease are linked with systemic inflammation and progression of OA. Hence, treatment of OA with statins is expected to improve metabolic abnormalities and prevent OA progression. Many studies which have addressed this issue found inconsistent results. This review aims to elucidate the effect of statins in OA by summarizing the existing data.

Methods:

Potential studies in English language published in Medline/PubMed, Scopus and Google Scholar since 2000 were searched by using keywords such as osteoarthritis, statins, progression, treatment, prevalence, synovitis, pain. Fourteen papers were found to be relevant and were summarised.

Results:

Data regarding symptomatic effect of statins in OA are scarce and the results varied from no effect to a small improvement or even increased risk of pain in knee OA. However, most studies on the incidence and progression of OA found a significant decreased risk of incident OA, as well as reduced risk of radiographic progression in statin users vs. non-users. Factors such as patient adherence, duration of treatment, and higher cumulative statin doses were associated with greater efficacy.

Conclusion:

Existing data indicate a preventing effect of statin therapy on OA progression. However, unless a formal meta-analysis with weight analysis is made, a conclusion cannot be drawn.

Adipose Tissue-Derived Mesenchymal Stem Cells as a Potential Restorative Treatment for Cartilage Defects: A PRISMA Review and Meta-Analysis

Cartilage defects are a predisposing factor for osteoarthritis. Conventional therapies are mostly palliative and there is an interest in developing newer therapies that target the disease’s progression. Mesenchymal stem cells (MSCs) have been suggested as a promising therapy to restore hyaline cartilage to cartilage defects, though the optimal cell source has remained under investigation. A PRISMA systematic review was conducted utilising five databases (MEDLINE, EMBASE, Cochrane Library, Scopus, Web of Science) which identified nineteen human studies that used adipose tissue-derived MSC (AMSC)-based therapies, including culture-expanded AMSCs and stromal vascular fraction, to treat cartilage defects. Clinical, imaging and histological outcomes, as well as other relevant details pertaining to cartilage regeneration, were extracted from each study. Pooled analysis revealed a significant improvement in WOMAC scores (mean difference: −25.52; 95%CI (−30.93, −20.10); p < 0.001), VAS scores (mean difference: −3.30; 95%CI (−3.72, −2.89); p < 0.001), KOOS scores and end point MOCART score (mean: 68.12; 95%CI (62.18, 74.05)), thus showing improvement. The studies in this review demonstrate the safety and efficacy of AMSC-based therapies for cartilage defects. Establishing standardised methods for MSC extraction and delivery, and performing studies with long follow-up should enable future high-quality research to provide the evidence needed to bring AMSC-based therapies into the market.

Clusterin Is Associated with Systemic and Synovial Inflammation in Knee Osteoarthritis

OBJECTIVES

This study aimed to determine possible associations between transcriptional and translational levels of clusterin (CLU) in the systemic and local joint environments with the severity of knee osteoarthritis (OA) and to investigate CLU mRNA expression in knee OA fibroblast-like synoviocytes (FLSs) stimulated with tumor necrosis factor-α.

DESIGN

Circulating and synovial fluid CLU levels in 259 knee OA patients were quantified using an enzyme-linked immunosorbent assay. Relative CLU mRNA expression in 50 knee OA synovial tissues and 4 knee OA FLSs was determined using real-time polymerase chain reaction.

RESULTS

Plasma CLU levels of knee OA patients were significantly higher than paired synovial fluid samples. Compared with early-stage knee OA patients, those with advanced-stage OA had considerably increased plasma and synovial fluid CLU levels. There were significant positive associations of plasma and synovial fluid CLU levels with radiographic severity of knee OA. Plasma CLU levels were directly correlated with its synovial fluid levels and high-sensitivity C-reactive protein levels in the patients. Receiver-operating characteristic curve analysis unveiled the potential utility of plasma CLU as a novel biomarker for knee OA severity (AUC = 0.80), with a sensitivity of 71.4% and a specificity of 73.3%. Marked upregulation of CLU mRNA expression was observed in both the inflamed synovial tissues and FLSs of knee OA.

CONCLUSION

Increased CLU mRNA and protein levels in the systemic and local joint environments of knee OA might reflect knee OA severity, especially systemic and synovial inflammation.

Monocytes, Macrophages, and Their Potential Niches in Synovial Joints - Therapeutic Targets in Post-Traumatic Osteoarthritis?

Synovial joints are complex structures that enable normal locomotion. Following injury, they undergo a series of changes, including a prevalent inflammatory response. This increases the risk for development of osteoarthritis (OA), the most common joint disorder. In healthy joints, macrophages are the predominant immune cells. They regulate bone turnover, constantly scavenge debris from the joint cavity and, together with synovial fibroblasts, form a protective barrier. Macrophages thus work in concert with the non-hematopoietic stroma. In turn, the stroma provides a scaffold as well as molecular signals for macrophage survival and functional imprinting: “a macrophage niche”. These intricate cellular interactions are susceptible to perturbations like those induced by joint injury. With this review, we explore how the concepts of local tissue niches apply to synovial joints. We introduce the joint micro-anatomy and cellular players, and discuss their potential interactions in healthy joints, with an emphasis on molecular cues underlying their crosstalk and relevance to joint functionality. We then consider how these interactions are perturbed by joint injury and how they may contribute to OA pathogenesis. We conclude by discussing how understanding these changes might help identify novel therapeutic avenues with the potential of restoring joint function and reducing post-traumatic OA risk.

Tert-butylhydroquinone attenuates osteoarthritis by protecting chondrocytes and inhibiting macrophage polarization

Aims

Tert-butylhydroquinone (tBHQ) has been identified as an inhibitor of oxidative stress-induced injury and apoptosis in human neural stem cells. However, the role of tBHQ in osteoarthritis (OA) is unclear. This study was carried out to investigate the role of tBHQ in OA.

Methods

OA animal model was induced by destabilization of the medial meniscus (DMM). Different concentrations of tBHQ (25 and 50 mg/kg) were intraperitoneally injected in ten-week-old female mice. Chondrocytes were isolated from articular cartilage of mice and treated with 5 ng/ml lipopolysaccharide (LPS) or 10 ng/ml interleukin 1 beta (IL-1β) for 24 hours, and then treated with different concentrations of tBHQ (10, 20, and 40 μM) for 12 hours. The expression levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in blood were measured. The expression levels of interleukin 6 (IL-6), IL-1β, and tumour necrosis factor alpha (TNF-α) leptin in plasma were measured using enzyme-linked immunoabsorbent assay (ELISA) kits. The expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signalling pathway proteins, and macrophage repolarization-related markers, were detected by western blot.

Results

Tert-butylhydroquinone significantly attenuated cartilage destruction in DMM-induced mice in vivo. It demonstrated clear evidence of inhibiting IL-1β-induced chondrocyte apoptosis, inflammation, and differentiation defect in vitro. Meanwhile, tBHQ inhibited LPS-induced activation of NF-κB and MAPK signalling pathways, and also inhibited LPS-induced reactive oxygen species production and macrophages repolarization in vitro.

Conclusion

Taken together, tBHQ might be a potential therapeutic strategy for protecting against OA development.

Cite this article: Bone Joint Res 2021;10(11):704–713.

Cartilage tissue miR-214-3p regulates the TrkB/ShcB pathway paracrine VEGF to promote endothelial cell migration and angiogenesis

BACKGROUND

This study was designed to explore the mechanisms through which chondrocytes regulated endothelial cell migration and angiogenesis in osteoarthritis (OA).

METHODS

The expressions of related genes of OA were detected by Western blot and real-time quantitative PCR. Chondrocytes were co-cultured with endothelial cells, and migration as well as angiogenesis rates, and vascular endothelial growth factor (VEGF) secretion of the cells were detected. The relationship between miRNA and TrkB were analyzed by bioinformatics analysis, RNA immunoprecipitation and dual-luciferase assays. The effects of miRNA on the histopathology of the OA mice were determined.

RESULTS

The expressions of NGF, TrkA, TrkB, and ShcB were increased significantly in OA patients. IL-1β promoted the expressions of TrkA, TrkB, and ShcB in chondrocytes and inhibited the expressions of chondrogenic differentiation markers, but shTrkB partially reversed IL-1β-mediated chondrogenic differentiation. Overexpression of TrkB promoted cell migration, angiogenesis, and VEGF levels, while silencing ShcB reversed the regulation of TrkB. Moreover, chondrocytes miR-214-3p regulated endothelial cell migration and angiogenesis by targeting TrkB paracrine VEGF to activate PI3K/Akt pathway proteins. In addition, overexpressed miR-214-3p improved collagenase-induced cartilage and synovial damage in OA mice.

CONCLUSION

The activation of TrkB/ShcB signaling pathway paracrine VEGF is mediated by miR-214-3p in chondrocytes and it regulates endothelial cell migration and angiogenesis in the development of OA.

High-Intensity Interval Training for Knee Osteoarthritis: A Pilot Study

OBJECTIVE

To assess the feasibility and changes in outcomes of a 12-week high-intensity interval training (HIIT) program in individuals with symptomatic knee osteoarthritis (OA).

METHODS

The single-arm trial included 29 participants (mean ± SD age 63 ± 7 years; 66% women; 66% obese). Measures of participant flow, adherence, and tolerability were collected. Pain, function, and balance were assessed at baseline, 6 weeks, and 12 weeks using the Western Ontario and McMaster Universities Osteoarthritis Index, 20-m fast-paced walk test, 30-second chair-stand test, stair-climb test, timed up and go test, and single leg stance. Cardiorespiratory fitness, strength, and body composition were evaluated using peak oxygen consumption (VO2 peak), isometric knee extensor/flexor strength, and dual-energy x-ray absorptiometry, respectively. HIIT was completed two times/week (cycling or treadmill) and consisted of 10 repetitions of 1-minute bouts at 90% VO2 peak, with 1-minute rest periods. Separate multivariable-adjusted linear mixed models were fit for each outcome with fixed effects of time, age, sex, body mass index, and random effects of baseline values to estimate mean changes and 95% confidence intervals (CIs) between baseline and 12-week assessments.

RESULTS

Recruitment aligned with the anticipated enrollment rate, adherence was 70%, and no adverse events were reported. At 12 weeks, improvements were observed for most outcomes, with notable mean changes for the 20-m fast-paced walk (-1.13 [95% CI -1.61 to -0.64] seconds), 30-second chair-stand (2.6 [1.8-3.4] stands), and VO2 peak (0.14 [0.03-0.24] liters/minute).

CONCLUSION

In this 12-week pilot study, HIIT improved multiple aspects of health in individuals with knee OA; larger studies are needed.

COL3A1 and MMP9 Serve as Potential Diagnostic Biomarkers of Osteoarthritis and Are Associated With Immune Cell Infiltration

Background

Osteoarthritis (OA) is one of the most common age-related degenerative diseases. In recent years, some studies have shown that pathological changes in the synovial membrane occur earlier than those in the cartilage in OA. However, the molecular mechanism of synovitis in the pathological process of OA has not been elucidated. This study aimed to identify novel biomarkers associated with OA and to emphasize the role of immune cells in the pathogenesis of OA.

Methods

Microarray datasets were obtained from the Gene Expression Omnibus (GEO) and ArrayExpress databases and were then analyzed using R software. To determine differential immune cell subtype infiltration, the CIBERSORT deconvolution algorithm was used. Quantitative reverse transcription PCR (qRT-PCR) was used to determine the relative expressions of selected genes. Besides, Western blotting was used to assess the protein expression levels in osteoarthritic chondrocytes.

Results

After analyzing the database profiles, two potential biomarkers, collagen type 3 alpha 1 chain (COL3A1), and matrix metalloproteinase 9 (MMP9), associated with OA were discovered, which were confirmed by qRT-PCR and Western blotting. Specifically, the results revealed that, as the concentration of IL-1β increased, so did the gene and protein expression levels of COL3A1 and MMP9.

Conclusion

The findings provide valuable information and direction for future research into novel targets for OA immunotherapy and diagnosis and aids in the discovery of the underlying biological mechanisms of OA pathogenesis.

Inhibition of sphingosine 1-phosphate protects mice against chondrocyte catabolism and osteoarthritis

OBJECTIVE

Cartilage loss observed in osteoarthritis (OA) is prevented when osteoclasts in the subchondral bone are inhibited in mice. Here, we investigated the role of the osteoclast secretome and of the lipid mediator sphingosine 1-phosphate (S1P) in chondrocyte metabolism and OA.

MATERIALS AND METHODS

We used SphK1^LysMCre and wild type mice to assess the effect of murine osteoclast secretome in chondrocyte metabolism. Gene and protein expressions of matrix metalloproteinase (Mmp) were quantified in chondrocytes and explants by RT-qPCR and Western blots. SphK1^LysMCre mice or wild type mice treated with S1P₂ receptor inhibitor JTE013 or anti-S1P neutralizing antibody sphingomab are analyzed by OA score and immunohistochemistry.

RESULTS

The osteoclast secretome increased the expression of Mmp3 and Mmp13 in murine chondrocytes and cartilage explants and activated the JNK signaling pathway, which led to matrix degradation. JTE013 reversed the osteoclast-mediated chondrocyte catabolism and protected mice against OA, suggesting that osteoclastic S1P contributes to cartilage damage in OA via S1P/S1P₂ signaling. The activity of sphingosine kinase 1 (SphK1) increased with osteoclast differentiation, and its expression was enhanced in subchondral bone of mice with OA. The expression of Mmp3 and Mmp13 in chondrocytes was low upon stimulation with the secretome of Sphk1-lacking osteoclasts. Cartilage damage was significantly reduced in SphK1^LysMCre mice, but not the synovial inflammation. Finally, intra-articular administration of sphingomab inhibited the cartilage damage and synovial inflammation.

CONCLUSIONS

Lack of S1P in myeloid cells and local S1P neutralization alleviates from osteoarthritis in mice. These data identify S1P as a therapeutic target in OA.