Vitamin D plays a protective role in osteoarthritis by regulating AMPK/mTOR signalling pathway to activate chondrocyte autophagy.

OBJECTIVES: The deletion of chondrocyte autophagy seems to play a key role in the pathogenesis of osteoarthritis (OA). Patients with OA often have vitamin D (VD) deficiency, and VD supplementation can improve pain and alleviate the progression of joint structures in patients. In this study, we aimed to investigate whether VD could enhance autophagy by activating the adenosine monophosphate activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signalling pathway and protect against OA. METHODS: In this study, the levels of target proteins and genes were examined by western blot and qRT-PCR. Apoptotic cells were detected using TUNEL staining. Characteristics of autophagy were observed by LysoTracker red staining, mRFP-GFP-LC3 adenovirus transfection, and transmission electron microscopy. siRNA-mediated AMPK and mTOR knockdown were used to investigate the role of the AMPK/ mTOR signalling pathway in VD-induced autophagy. Haematoxylin and eosin and safranin-O/fast green staining were used detect cartilage alterations. RESULTS: We suggested that VD significantly reduced chondrocyte death and alleviated extracellular matrix degradation. Further studies showed that VD promoted the expression of the autophagy-related protein LC3II through the AMPK/mTOR signalling pathway in chondrocytes, activated lysosome activity, promoted the formation of autophagy-associated lysosomes, which played a crucial role in the degradation of intracellular organelles and maintained homeostasis. The anti-apoptotic effect of VD on chondrocytes was associated with the activation of autophagy. The group of AMPK-normal and mTOR-knockdown in the presence of VD inhibited chondrocyte apoptosis by promoting autophagy. CONCLUSIONS: This study highlights that VD can activate chondrocyte autophagy through the AMPK/mTOR signalling pathway.

Evaluating the causal effect of circulating proteome on the risk of osteoarthritis-related traits.

OBJECTIVES: This study aims to identify circulating proteins that are causally associated with osteoarthritis (OA)-related traits through Mendelian randomisation (MR)-based analytical framework. METHODS: Large-scale two-sample MR was employed to estimate the effects of thousands of plasma proteins on 12 OA-related traits. Additional analyses including Bayesian colocalisation, Steiger filtering analysis, assessment of protein-altering variants and mapping expression quantitative trait loci to protein quantitative trait loci were performed to investigate the reliability of the MR findings; protein-protein interaction, pathway enrichment analysis and evaluation of drug targets were conducted to deepen the understanding and identify potential therapeutic targets of OA. RESULTS: Dozens of circulating proteins were identified to have putatively causal effects on OA-related traits, and a majority of these proteins were either drug targets or considered druggable. CONCLUSIONS: Through MR analysis, we have identified numerous plasma proteins associated with OA-related traits, shedding light on protein-mediated mechanisms and offering promising therapeutic targets for OA.

Metformin attenuates osteoarthritis by targeting chondrocytes, synovial macrophages and adipocytes.

OBJECTIVE: To investigate the therapeutic effect and mechanism of metformin on knee OA in normal diet (ND) mice or high-fat diet (HFD)-induced obese mice. METHODS: Destabilization of the medial meniscus surgery was performed in ND mice or HFD mice, and metformin was administrated in drinking water or not. The changes of OA joint structure, infiltration and polarization of synovial macrophages and circulating and local levels of leptin and adiponectin were evaluated. In vitro, the effects of metformin on chondrocytes and macrophages, and of conditioned mediums derived from mouse abdominal fat on murine chondrogenic cell line ATDC5 and murine macrophage cell line RAW264.7, were detected. RESULTS: Metformin showed protective effects on OA, characterized by reductions on OARSI score [2.00, 95% CI (1.15, 2.86) for ND mice and 3.17, 95% CI (2.37, 3.96) for HFD mice] and synovitis score [1.17, 95% CI (0.27, 2.06) for ND mice and 2.50, 95% CI (1.49, 3.51) for HFD mice] after 10 weeks of treatment, and the effects were more significant in HFD mice than in ND mice. Mechanistically, in addition to decreasing apoptosis and matrix-degrading enzymes expression in chondrocytes as well as infiltration and pro-inflammatory differentiation of synovial macrophages, metformin reduced leptin secretion by adipose tissue in HFD mice. CONCLUSIONS: Metformin protects against knee OA which could be through reducing apoptosis and catabolism of chondrocytes, and suppressing infiltration and pro-inflammatory polarization of synovial macrophages. For obese mice, metformin has a greater protective effect in knee OA additionally through reducing leptin secretion from adipose tissue.

Comprehensive analysis on subchondral bone marrow lesions of human osteoarthritis by integrating bulk and single-cell transcriptomes.

OBJECTIVE: This study aims to demonstrate the cellular composition and underlying mechanisms in subchondral bone marrow lesions (BMLs) of knee osteoarthritis (OA). METHODS: BMLs were assessed by MRI Osteoarthritis Knee Score (MOAKS)≥2. Bulk RNA-sequencing (bulk-seq) and BML-specific differentially expressed genes (DEGs) analysis were performed among subchondral bone samples (including OA-BML=3, paired OA-NBML=3; non-OA=3). The hub genes of BMLs were identified by verifying in independent datasets and multiple bioinformatic analyses. To further estimate cell-type composition of subchondral bone, we utilized two newly developed deconvolution algorithms (MuSiC, MCP-counter) in transcriptomic datasets, based on signatures from open-accessed single-cell RNA sequencing (scRNA-seq). Finally, competing endogenous RNA (ceRNA) and transcription factor (TF) networks were constructed through multiple predictive databases, and validated by public non-coding RNA profiles. RESULTS: A total of 86 BML-specific DEGs (up 79, down 7) were identified. IL11 and VCAN were identified as core hub genes. The "has-miR-424-5p/lncRNA PVT1" was determined as crucial network, targeting IL11 and VCAN, respectively. More importantly, two deconvolution algorithms produced approximate estimations of cell-type composition, and the cluster of heterotopic-chondrocyte was discovered abundant in BMLs, and positively correlated with the expression of hub genes. CONCLUSION: IL11 and VCAN were identified as the core hub genes of BMLs, and their molecular networks were determined as well. We profiled the characteristics of subchondral bone at single-cell level and determined that the heterotopic-chondrocyte was abundant in BMLs and was closely linked to IL11 and VCAN. Our study may provide new insights into the microenvironment and pathological molecular mechanism of BMLs, and could lead to novel therapeutic strategies.

Longitudinal association of infrapatellar fat pad signal intensity alteration with biochemical biomarkers in knee osteoarthritis.

OBJECTIVE: To explore the longitudinal association of quantitative infrapatellar fat pad (IPFP) signal intensity alteration with OA-related biomarkers. METHODS: Eighteen OA-related biochemical biomarkers of 600 knee OA participants in the Foundation for the National Institutes of Health OA Biomarkers Consortium (FNIH) study were extracted. The quantitative IPFP signal intensity measures were acquired based on magnetic resonance imaging, including mean value [Mean (IPFP)] and standard deviation [sDev (IPFP)] of the whole IPFP signal intensity, median value [Median (H)] and upper quartile value [UQ (H)] of high signal intensity, the ratio of volume of high signal intensity to volume of whole IPFP signal intensity [Percentage (H)] and Clustering factor (H). The linear mixed-effect model was applied to determine the longitudinal associations between IPFP signal intensity alteration and biochemical biomarkers over 2 years. RESULTS: All IPFP measures except for Clustering factor (H) were positively associated with urine collagenase-cleaved type II collagen neoepitope (uC2C), urine C-terminal cross-linked telopeptide of type II collagen (uCTX-II), urine C-terminal cross-linked telopeptide of type I collagen-α (uCTX-Iα) and urine N-terminal cross-linked telopeptide of type I collagen (uNTX-I). Mean (IPFP), Median (H) and Percentage (H) were positively associated with the nitrated form of an epitope located in the triple helix of type II collagen (Coll2-1 NO2). Mean (IPFP), Median (H) and UQ (H) were positively associated with sCTX-I and uCTX-Iß. Positive associations between sDev (IPFP), Percentage (H) and serum hyaluronic acid (sHA) were found. CONCLUSION: Our results suggest a role of IPFP signal intensity alteration in joint tissue remodelling on a molecular level.

Association of serum levels of inflammatory markers and adipokines with joint symptoms and structures in participants with knee osteoarthritis.

OBJECTIVE: To investigate the longitudinal associations of serum inflammatory markers and adipokines with joint symptoms and structures in participants with knee OA. METHODS: Two hundred participants (46.5% female, mean age 63.1 years, mean BMI 29.5 kg/m2) from Tasmania, part of the VIDEO (Vitamin D Effect on OA) study, were randomly selected in the current study. Serum levels of 19 biomarkers, scores of WOMAC and MRI-assessed knee structures were evaluated at baseline and month 24. The patterns of biomarkers were derived from principal component analysis and their association with knee symptoms and structures were examined using adjusted generalized estimating equations. RESULTS: Five components explained 78% of the total variance. IL-1ß, -2, -4, -6, -8, -17 A, -17 F, -21, -22 and -23 loaded the highest on the first component, which was associated with increased bone marrow lesions (BMLs) and WOMAC dysfunction score. IL-10, -12 and GM-CSF loaded on the second component, which was associated with increased cartilage volume, and decreased effusion synovitis and WOMAC scores. Leptin, adipsin and CRP loaded on the third component, which was positively associated with WOMAC scores. Resistin loaded on the fourth component, which was associated with increased BMLs and cartilage defects. Apelin-36 and adiponectin loaded on the fifth component, which was associated with increased BMLs. CONCLUSION: Various inflammatory and metabolic components were associated differently with joint symptoms and structural changes in knee OA, suggesting a complex inflammatory and metabolic interrelationship in the pathogenesis of knee OA.

Signal intensity alteration and maximal area of pericruciate fat pad are associated with incident radiographic osteoarthritis: data from the Osteoarthritis Initiative.

OBJECTIVE: To determine whether pericruciate fat pad (PCFP) signal intensity alteration and maximal area are associated with incident radiographic osteoarthritis (ROA) over 4 years in the Osteoarthritis Initiative (OAI) study. METHODS: Participants were from the Osteoarthritis Initiative (OAI) study. Case knees (n = 355) were defined by incident ROA between 12 and 48 months visits and were matched by sex, age, and radiographic status with control knees (n = 355). Magnetic resonance images (MRIs) were used to assess PCFP signal intensity alteration and PCFP maximal area at P0 (time of onset of ROA), P-1 (1 year prior to P0), and baseline. Conditional logistic regression analyses were applied to assess associations between PCFP measures and the risk of incident ROA. RESULTS: The mean age of participants was 60.1 years and 66.9% were women. In multivariable analyses, PCFP signal intensity alteration measured at three time points (OR [95%CI]: 1.28 [1.10-1.50], 1.52 [1.30-1.78], 1.50 [1.27-1.76], respectively) and PCFP maximal area (OR [95%CI]: 1.21 [1.03-1.42], 1.27 [1.07-1.52], 1.37 [1.15-1.62], respectively) were significantly associated with incident ROA. CONCLUSIONS: PCFP signal intensity alteration and maximal area were associated with incident ROA over 4 years, implying that they may have roles to play in ROA. KEY POINTS: • Pericruciate fat pad signal intensity alteration and maximal area were associated with incident ROA, implying that they may have roles to play in ROA.

Metformin use and associated risk of total joint replacement in patients with type 2 diabetes: a population-based matched cohort study.

BACKGROUND: It is uncertain whether metformin use is associated with reduced risk of joint replacement in patients with type 2 diabetes mellitus. We aimed to establish whether metformin use was associated with a reduced risk of total knee replacement (TKR) or total hip replacement (THR) among these patients. METHODS: We selected patients with type 2 diabetes mellitus that was diagnosed between 2000 and 2012 from the Taiwan National Health Insurance Research Database. We used prescription time-distribution matching and propensity-score matching to balance potential confounders between metformin users and nonusers. We assessed the risks of TKR or THR using Cox proportional hazards regression. RESULTS: We included 20 347 participants who were not treated with metformin and 20 347 who were treated with metformin, for a total of 40 694 participants (mean age 63 yr, standard deviation 11 yr; 49.8% were women) after prescription time-distribution matching. Compared with participants who did not use metformin, those who used metformin had lower risks of TKR or THR (adjusted hazard ratio [HR] 0.70, 95% confidence interval [CI] 0.60-0.81 for TKR or THR; adjusted HR 0.71, 95% CI 0.61-0.84 for TKR; adjusted HR 0.61, 95% CI 0.41-0.92 for THR) after adjustment for covariates. Propensity-score matching analyses (10 163 participants not treated with metformin v. 10 163 treated with metformin) and sensitivity analyses using inverse probability of treatment weighting and competing risk regression showed similar results. INTERPRETATION: Metformin use in patients with type 2 diabetes mellitus was associated with a significantly reduced risk of total joint replacement. Randomized controlled clinical trials in patients with osteoarthritis are warranted to determine whether metformin is effective in decreasing the need for joint replacement.

Quadriceps strength is negatively associated with knee joint structural abnormalities-data from osteoarthritis initiative.

OBJECTIVE: The aim of this study was to explore the longitudinal associations between baseline quadriceps strength and knee joint structural abnormalities in knee osteoarthritis (KOA). METHODS: This study is a longitudinally observational study based on Osteoarthritis Initiative (OAI) cohort, including men and women aged 45-79. Quadriceps strength was measured by isometric knee extension testing at baseline. Knee joint structural abnormalities, including cartilage damage, bone marrow lesions (BMLs), effusion-synovitis and Hoffa-synovitis, were evaluated by Magnetic Resonance Imaging Osteoarthritis Knee Score (MOAKS) at baseline and 1-year follow-up. Generalized estimating equations were employed to examine the associations between quadriceps strength and knee structural abnormalities. All analyses were stratified by sex. RESULTS: One thousand three hundred thirty-eight participants (523 men and 815 women) with a mean age of 61.8 years and a mean BMI of 29.4 kg/m2 were included in this study. For men, no significantly longitudinal association of quadriceps strength with structural abnormalities was detected. In contrast, quadriceps strength was significantly and negatively associated with changes in cartilage damage and BMLs in lateral patellofemoral joint (PFJ) (cartilage damage: OR: 0.91, 95% CI 0.84 to 0.99, P = 0.023; BMLs: OR: 0.85, 95% CI 0.74 to 0.96, P = 0.011) and effusion-synovitis (OR = 0.88, 95% CI 0.78 to 0.99, P = 0.045) among females longitudinally. Higher quadriceps strength was significantly associated with less progression of lateral PFJ cartilage damage, BMLs and effusion-synovitis in females. CONCLUSIONS: Higher quadriceps strength was associated with changes in cartilage damage and BMLs within the lateral PFJ and effusion-synovitis among females, suggesting the potential protective role of quadriceps strength on joint structures in women.

Can metformin relieve tibiofemoral cartilage volume loss and knee symptoms in overweight knee osteoarthritis patients? Study protocol for a randomized, double-blind, and placebo-controlled trial.

BACKGROUND: Osteoarthritis (OA) is the most common joint disease, and is most frequently seen in the knees. However, there is no effective therapy to relieve the progression of knee OA. Metformin is a safe, well-tolerated oral medication that is extensively used as first-line therapy for type 2 diabetes. Previous observational studies and basic researches suggested that metformin may have protective effects on knee OA, which needs to be verified by clinical trials. This study, therefore, aims to examine the effects of metformin versus placebo on knee cartilage volume loss and knee symptoms in overweight knee OA patients by a randomized controlled trial over 24 months. METHODS: This protocol describes a multicenter, randomized, double-blind, and placebo-controlled clinical trial aiming to recruit 262 overweight knee OA patients. Participants will be randomly allocated to the two arms of the study, receiving metformin hydrochloride sustained-release tablets or identical inert placebo for 24 months (start from 0.5 g/day for the first 2 weeks, and increase to 1 g/day for the second 2 weeks, and further increase to 2 g/day for the remaining period if tolerated). Primary outcomes will be changes in tibiofemoral cartilage volume and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score over 24 months. Secondary outcomes will be changes in visual analogue scale (VAS) knee pain, tibiofemoral cartilage defects, effusion-synovitis volume, and tibiofemoral bone marrow lesions maximum size over 24 months. The primary analyses will be intention-to-treat analyses of primary and secondary outcomes. Per-protocol analyses will be performed as the secondary analyses. DISCUSSION: If metformin is proved to slow knee cartilage volume loss and to relieve knee symptoms among overweight knee OA patients, it will have the potential to become a disease modifying drug for knee OA. Metformin is a convenient intervention with low cost, and its potential effects on slowing down the structural progression and relieving the symptoms of knee OA would effectively reduce the disease burden worldwide. TRIAL REGISTRATION: ClinicalTrials. gov NCT05034029 . Registered on 30 Sept 2021.

Associations of blood pressure and arterial stiffness with knee cartilage volume in patients with knee osteoarthritis.

OBJECTIVE: To describe the associations of blood pressure and arterial stiffness with knee cartilage volume in patients with knee OA. METHODS: A secondary analysis was performed on the data from participants in a randomized controlled trial that identified the effects of vitamin D supplementation on knee structures and symptoms among patients with symptomatic knee OA. Brachial and central blood pressure, arterial stiffness indicators and knee cartilage volume were measured at baseline and the 2 year follow-up. Associations were assessed using generalized estimating equations. RESULTS: Among 231 participants (average age 63.2 years), 48.9% were females. Higher supine systolic and diastolic pressures were significantly associated with lower tibial cartilage volume (systolic: lateral ß -6.23, medial ß -5.14, total ß -11.35 mm3/mmHg; diastolic: lateral ß -10.25, medial ß -11.29, total ß -21.50 mm3/mmHg). Higher supine systolic pressure was associated with lower femoral cartilage volume (lateral ß -17.35, total ß -28.31 mm3/mmHg). Central systolic pressure and arterial stiffness indicators (including pulse wave velocity, central pulse pressure and peripheral pulse pressure) were largely not associated with knee cartilage volume; however, higher augmentation index was associated with lower tibial and femoral cartilage volume (tibial: medial ß -8.24, total ß -19.13 mm3/%; femoral: lateral ß -23.70, medial ß -26.42, total ß -50.12 mm3/%). CONCLUSIONS: Blood pressure and arterial stiffness are associated with knee cartilage volume at several sites in knee OA patients. This supports that blood pressure and arterial stiffness may involve in the progression of knee OA.

Osteoarthritic infrapatellar fat pad aggravates cartilage degradation via activation of p38MAPK and ERK1/2 pathways.

OBJECTIVE: This study aimed to investigate the biochemical effects of osteoarthritic infrapatellar fat pad (IPFP) on cartilage and the underlying mechanisms. METHODS: Human IPFP and articular cartilage were collected from end-stage osteoarthritis (OA) patients during total knee arthroplasty. IPFP-derived fat-conditioned medium (FCM) was used to stimulate human primary chondrocytes and cartilage explants. Functional effect of osteoarthritic IPFP was explored in human primary chondrocytes and articular cartilage in vitro and ex vivo. Activation of relative pathways and its effects on chondrocytes were assessed through immunoblotting and inhibition experiments, respectively. Neutralization test was performed to identify the main factors and their associated pathways responsible for the effects of IPFP. RESULTS: Osteoarthritic IPFP-derived FCM significantly induced extracellular matrix (ECM) degradation in both human primary chondrocytes and cartilage explants. Several pathways, such as NF-κB, mTORC1, p38MAPK, JNK, and ERK1/2 signaling, were significantly activated in human chondrocytes with osteoarthritic IPFP-derived FCM stimulation. Interestingly, inhibition of p38MAPK and ERK1/2 signaling pathway could alleviate the detrimental effects of FCM on chondrocytes, while inhibition of other signaling pathways had no similar results. In addition, IL-1ß and TNF-α instead of IL-6 in osteoarthritic IPFP-derived FCM played key roles in cartilage degradation via activating p38MAPK rather than ERK1/2 signaling pathway. CONCLUSION: Osteoarthritic IPFP induces the degradation and inflammation of cartilage via activation of p38MAPK and ERK1/2 pathways, in which IL-1ß and TNF-α act as the key factors. Our study suggests that modulating the effects of IPFP on cartilage may be a promising strategy for knee OA intervention.

[Analysis of behaviors on household food safety and its influencing factors among caregivers of children aged 3-12 years old in Chinese three Provinces and Municipality].

OBJECTIVE: To understand behaviors and influence factors on household food safety among caregivers of child aged 3-12 years old. METHODS: A total of 12 449 caregivers of children aged 3-12 years were selected using random sampling method in Shanghai Municipality, Sichuan and Hebei Provinces from September 2018 to December 2018. A city and a rural district were chosen from each region points, respectively, then 3-4 kindergartens and 2-3 primary schools were randomly selected. A self-administrated questionnaire was distributed to parents and collected timely, focused on the information of behaviors on food safety. Binary logistic regression was used to multiple-factor regression analysis on food safety behavior of children caregivers. RESULTS: The average score of household food safety behaviors in three provinces was 13.5(11.0-16.0), and the pass rate of correct behavior was 47.8%. The main problems included the correct defrost of frozen food(3.4%), the storage of food with anti-rat, cockroach, fly facilities(12.8%), never eat leftovers or if leftovers in the refrigerator at home, thoroughly heating(26.3%), and the preparation of raw and cooked food using separate cutting boards/knives(32.4%). Multivariate Logistic regression analysis showed that the pass rate of correct behavior in Hebei was lower than that in Shanghai, the odds ratio(OR) was 0.873(95%CI 0.794-0.960); parents aged 31-40, 41-50 and above of 50 was higher than that of parents aged 18-30, OR were 1.391(95%CI 1.247-1.552), 1.836(95%CI 1.589-2.121) and 1.954(95%CI 1.269-3.009), respectively; the education level of junior college and above was higher than that of primary school and below, OR was 1.392(95%CI 1.088-1.781) and 1.466(95%CI 1.148-1.870), respectively; the median and high level of family economic income were higher than the low level of income, with an OR value of 1.396(95%CI 1.260-1.547) and 2.543(95%CI 2.069-3.126), respectively; the incidence of food poisoning in the past six months was higher than that without food poisoning, with an OR value of 1.639(95%CI 1.336-2.010). CONCLUSION: The correct behaviors level on food safety is relative low.

Extracellular Vesicles in Infrapatellar Fat Pad from Osteoarthritis Patients Impair Cartilage Metabolism and Induce Senescence.

Infrapatellar fat pad (IPFP) is closely associated with the development and progression of knee osteoarthritis (OA), but the underlying mechanism remains unclear. Here, it is find that IPFP from OA patients can secret small extracellular vesicles (sEVs) and deliver them into articular chondrocytes. Inhibition the release of endogenous osteoarthritic IPFP-sEVs by GW4869 significantly alleviated IPFP-sEVs-induced cartilage destruction. Functional assays in vitro demonstrated that IPFP-sEVs significantly promoted chondrocyte extracellular matrix (ECM) catabolism and induced cellular senescence. It is further demonstrated that IPFP-sEVs induced ECM degradation in human and mice cartilage explants and aggravated the progression of experimental OA in mice. Mechanistically, highly enriched let-7b-5p and let-7c-5p in IPFP-sEVs are essential to mediate detrimental effects by directly decreasing senescence negative regulator, lamin B receptor (LBR). Notably, intra-articular injection of antagomirs inhibiting let-7b-5p and let-7c-5p in mice increased LBR expression, suppressed chondrocyte senescence and ameliorated the progression of experimental OA model. This study uncovers the function and mechanism of the IPFP-sEVs in the progression of OA. Targeting IPFP-sEVs cargoes of let-7b-5p and let-7c-5p can provide a potential strategy for OA therapy.

Spermidine ameliorates osteoarthritis via altering macrophage polarization.

OBJECTIVE: Spermidine (SPD) is an anti-aging natural substance, and it exerts effects through anti-apoptosis and anti-inflammation. However, the specific protective mechanism of SPD in osteoarthritis (OA) remains unclear. Here, we explored the role of SPD on the articular cartilage and the synovial tissue, and tested whether the drug would regulate the polarization of synovial macrophages by in vivo and in vitro experiments. METHODS: By constructing an OA model in mice, we preliminarily explored the protective effect of SPD on the articular cartilage and the synovial tissue. Meanwhile, we isolated and cultured human primary chondrocytes and bone marrow-derived macrophages (BMDMs), and prepared a conditioned medium (CM) to explore the specific protective effect of SPD in vitro. RESULTS: We found that SPD alleviated cartilage degeneration and synovitis, increased M2 polarization and decreased M1 polarization in synovial macrophages. In vitro experiments, SPD inhibited ERK MAPK and p65/NF-κB signaling in macrophages, and transformed macrophages from M1 to M2 subtypes. Interestingly, SPD had no direct protective effect on chondrocytes in vitro; however, the conditioned medium (CM) from M1 macrophages treated with SPD promoted the anabolism and inhibited the catabolism of chondrocytes. Moreover, this CM markedly suppressed IL-1ß-induced p38/JNK MAPK signaling pathway activation in chondrocytes. CONCLUSIONS: This work provides new perspectives on the role of SPD in OA. SPD does not directly target chondrocytes, but can ameliorate the degradation of articular cartilage through regulating M1/M2 polarization of synovial macrophages. Hence, SPD is expected to be the potential therapy for OA.

The association between anterior cruciate ligament degeneration and incident knee osteoarthritis: Data from the osteoarthritis initiative.

Background: Though anterior cruciate ligament (ACL) tear has been widely accepted as an important accelerator for knee osteoarthritis (KOA), the role of intrinsic ACL degeneration in developing KOA has not been fully investigated. Purpose: To determine whether ACL degeneration, in the absence of ACL tear, is associated with incident KOA over 4 years. Study design: Cohort study; Level of evidence, 2. Methods: Participants' knees in this nested case-control study were selected from the Osteoarthritis Initiative (OAI) study, with Kellgren-Lawrence grading (Kellgren-Lawrence grading) of 0 or 1 â€‹at baseline (BL). Case knees which had incident KOA (KLG ≥2) over 4 years, were matched 1:1 with control knees by gender, age and radiographic status. ACL signal intensity alteration (0-3 scale) and volume were assessed as compositional feature and morphology of ACL degeneration, using knee MRI at P0 (time of onset of incident KOA), P-1 (1 year prior to P0) and baseline. Conditional logistic regression was applied to analyze the association between measures of ACL degeneration and incident KOA. Results: 337 case knees with incident KOA were matched to 337 control knees. Participants were mostly female (68.5%), with an average age of 59.9 years old. ACL signal intensity alterations at BL, P-1 and P0 were significantly associated with an increased odds of incident KOA respectively (all P for trend ≤0.001). In contrast, ACL volumes were not significantly associated with incident KOA at any time points. Conclusions: ACL signal intensity alteration is associated with increased incident KOA over 4 years, whereas ACL volume is not.The translational potential of this article: This paper focused on ACL signal intensity alteration which could better reflect ACL degeneration rather than ACL tear during the progression of KOA and explored this topic in a nested case-control study. Utilizing MR images from KOA participants, we extracted the imaging features of ACL. In addition, we established a semi-quantitative score for ACL signal intensity alteration and found a significant correlation between it and KOA incidence. Our findings confirmed that the more severe the ACL signal intensity alteration, the stronger relationship with the occurrence of KOA. This suggests that more emphasis should be placed on ACL degeneration rather than ACL integrity in the future.

Integrating Radiomics and Neural Networks for Knee Osteoarthritis Incidence Prediction.

OBJECTIVE: Accurately predicting knee osteoarthritis (KOA) is essential for early detection and personalized treatment. We aimed to develop and test an MRI-based Joint Space Radiomic Model (JS-RM) to predict radiographic KOA incidence through neural networks by integrating meniscus and femorotibial cartilage radiomic features. METHODS: In the Osteoarthritis Initiative cohort, knees without radiographic KOA at baseline but at high risk for radiographic KOA were included. Case knees developed radiographic KOA whereas control knees did not over 4-year. We randomly split the knees into development and test cohorts (D/T=8/2) and extracted features from baseline 3D-DESS-sequence MRI. Model performance was evaluated using an area under the receiver operating characteristic curve (AUC), sensitivity, and specificity in both cohorts. Nine resident surgeons performed the reader experiment without/with the JS-RM aid. RESULTS: Our study included 549 knees in the development cohort (275 cases vs. 274 controls) and 137 knees in the test cohort (68 cases vs. 69 controls). In the test cohort, JS-RM had a favorable accuracy for predicting the radiographic KOA incidence with an AUC of 0.931 (95%CI: 0.876-0.963), a sensitivity of 84.4% (95%CI: 83.9%-84.9%), and a specificity of 85.6% (95%CI: 85.2%-86.0%). The mean specificity and sensitivity of resident surgeons through MRI reading in predicting radiographic KOA incidence were increased from 0.474 (95%CI: 0.333-0.614) and 0.586 (95%CI: 0.429-0.743) without the assistance of JS-RM to 0.874 (95%CI: 0.847-0.901) and 0.812 (95%CI: 0.742-0.881) with JS-RM assistance, respectively (p<.001). CONCLUSION: JS-RM integrating the features of the meniscus and cartilage showed improved predictive values in radiographic KOA incidence.

Bio-responsive and multi-modality imaging nanomedicine for osteoarthritis theranostics.

Osteoarthritis (OA) is one of the most common joint diseases currently, characterized by the gradual degradation of cartilage, remodeling of subchondral bone, development of synovitis, degenerative alterations in the menisci, and formation of osteophytes. Generally, loss of articular cartilage is the most common pathological manifestation of OA. However, owing to the lack of blood vessels and nerves, the damaged cartilage is unable to execute self-repair. Therefore, early detection and treatment of cartilage lesions are extremely vital. Given that precise diagnosis and therapeutic strategy are indispensable from the basic pathological features of OA, an ideal therapeutic strategy should cater to the specific features of the OA microenvironment to achieve disease-modifying therapy. To date, nanomedicine presents an opportunity to achieve the precisely targeted delivery of agents and stimuli-sensitive release at the optimum dose, which may be coupled with a controlled release profile and reduced side effects. This review mainly summarizes inherent and microenvironment traits of OA and outlines stimuli-responsive nanotherapies, including internal bio-responsive (e.g., reactive oxygen species, pH, and protease) and external (e.g., photo stimuli, temperature, ultrasound, and magnetic field) responsive nanotherapies. Furthermore, multi-targeted therapeutic strategies combined with multi-modality imaging are also discussed. In general, future exploration of more novel stimuli-responsive nanotherapies that can be used for early diagnosis and cartilage targeting may help ameliorate OA-related cartilage damage, decrease pain, and promote joint function.