Mediation of the association between obesity and osteoarthritis by blood pressure, vessel wall stiffness and subclinical atherosclerosis

Objective

We investigated the role of blood pressure, vessel wall stiffness [pulse wave velocity (PWV)] and subclinical atherosclerosis markers [carotid intima-media thickness (cIMT), popliteal vessel wall thickness (pVWT)] as mediators of the association of obesity with OA.

Methods

We used cross-sectional data from a subset of the population-based NEO study (n = 6334). We classified clinical hand and knee OA by the ACR criteria, and structural knee OA, effusion and bone marrow lesions on MRI (n = 1285). cIMT was assessed with ultrasonography. pVWT was estimated on knee MRI (n = 1285), and PWV by abdominal velocity-encoded MRIs (n = 2580), in subpopulations. Associations between BMI and OA were assessed with logistic regression analyses, adjusted for age, sex and education. Blood pressure, cIMT, pVWT and PWV were added to the model to estimate mediation.

Results

The population consisted of 55% women, with a mean (s.d.) age of 56(6) years. Clinical hand OA was present in 8%, clinical knee OA in 10%, and structural knee OA in 12% of participants. BMI was positively associated with all OA outcomes. cIMT partially mediated the association of BMI with clinical hand OA [10.6 (6.2; 30.5)%], structural knee OA [3.1 (1.9; 7.3)%] and effusion [10.8 (6.0; 37.6)%]. Diastolic blood pressure [2.1 (1.6; 3.0)%] minimally mediated the association between BMI and clinical knee OA. PWV and pVWT did not mediate the association between BMI and OA.

Conclusions

cIMT and diastolic blood pressure minimally mediated the association of BMI with OA. This suggests that such mediation is trivial in the middle-aged population.

The association between psychological factors and pain exacerbations in hip osteoarthritis

OBJECTIVES

To evaluate the association between psychological factors and pain exacerbations in people with hip OA.

METHODS

Eligible participants with symptomatic hip OA were instructed to complete online questionnaires every 10 days over a 90-day follow-up period. In addition, they were required to complete the questionnaire whenever they perceived they were experiencing a hip pain exacerbation. Hip pain exacerbation was defined as an increase of 2 points in pain intensity compared with baseline on an 11-point numeric rating scale (0-10). The Depression, Anxiety and Stress Scale-21 Items, Positive and Negative Affect Schedule, Pain Catastrophizing Scale and Pain Self-Efficacy Questionnaire were used to evaluate psychological factors. The associations of these with risk of hip pain exacerbation were examined by conditional logistic regression.

RESULTS

Of 252 participants recruited, 131 (52.0%) contributed both case and control period data and were included in the analysis. A significant association was found between Pain Catastrophizing Scale overall score (1 point increase) with hip pain exacerbations (odds ratio: 1.07, 95% CI: 1.04, 1.11). An increase of a minimal important change (5.5 points) of Pain Self-Efficacy Questionnaire score was associated with a lower odds of pain exacerbations (odds ratio: 0.74, 95% CI: 0.65, 0.85). No significant associations were found between Depression, Anxiety and Stress Scale-21 Items or Positive and Negative Affect Schedule scores with hip pain exacerbations.

CONCLUSION

Both pain catastrophizing and pain self-efficacy beliefs were associated with pain exacerbations in people with hip OA, but other psychological factors including depression, anxiety and stress or positive and negative affects, were not associated with pain exacerbations.

Causal relationship of serum nutritional factors with osteoarthritis: a Mendelian randomization study

OBJECTIVES

OA is the most common form of arthritis worldwide and has a major impact on the quality of life among the older population. This study aimed at determining the potential causal effects of several serum nutritional factors on OA.

METHODS

A total of seven serum nutritional factors were identified from genome-wide association studies. Summary statistics for OA were obtained from UK Biobank (194 153 for women and 166 988 for men) and a large genome-wide association studies meta-analysis based on the European population (455 221, 393 873 and 403 124 for overall, hip and knee OA, respectively). Two-sample Mendelian randomization approach was used to estimate the causal association between the selected nutritional factors and the risk of OA.

RESULTS

The Mendelian randomization analyses suggested that serum calcium levels were inversely associated with overall OA (95% CI, 0.595, 0.850), hip OA (95% CI, 0.352, 0.799) and knee OA (95% CI, 0.461, 0.901). Serum retinol levels were also inversely associated with hip OA (95% CI, 0.257, 0.778). Moreover, sex-specific associations were observed between serum calcium levels (95% CI, 0.936, 0.998), iron levels (95% CI, 1.000, 1.012), selenium levels (95% CI, 0.923, 0.999) and OA in women.

CONCLUSION

In this study, an inverse causal association between serum calcium levels and OA was established. Serum retinol levels were inversely associated with hip OA. In addition, we provide evidence for the causal effect of serum calcium, iron and selenium on the risk of OA in women.

Fibroblast-like Synoviocytes-derived Exosomal PCGEM1 Accelerates IL-1β-induced Apoptosis and Cartilage Matrix Degradation by miR-142-5p/RUNX2 in Chondrocytes

Background: Long non-coding RNA (lncRNA) prostate cancer gene expression marker 1 (PCGEM1) has been revealed to participate in the pathogenesis of osteoarthritis (OA). However, the molecular mechanism of PCGEM1 regulating OA progression has not been fully elucidated.Methods: Fibroblast-like synoviocytes (FLSs) were isolated from synovium tissues of OA patients (OA-FLSs) and trauma donors (Normal-FLSs). The size and morphology of the isolated exosomes were analyzed by transmission electron microscopy and nanoparticle tracking analysis. Protein levels were analyzed by western blotting. Expression levels of PCGEM1, microRNA-142-5p (miR-142-5p), runt-related transcription factor 2 (RUNX2) mRNA, and OA related genes were assessed by qRT-PCR. Cell proliferation, viability, and apoptosis were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide or flow cytometry assays. The relationship between miR-142-5p and PCGEM1 or RUNX2 was verified by dual-luciferase reporter and/or RNA pull down assays.Results: PCGEM1 was overexpressed in OA cartilages and exosomes from OA-FLSs. Exosomal PCGEM1 from OA-FLSs facilitated IL-1β-induced apoptosis and cartilage matrix degradation in chondrocytes. MiR-142-5p was downregulated while RUNX2 was upregulated in OA cartilages. Exosomal PCGEM1 from OA-FLSs regulated RUNX2 expression by sponging miR-142-5p in IL-1β-induced chondrocytes. MiR-142-5p inhibitor offset exosomal PCGEM1 knockdown-mediated effects on the apoptosis and cartilage matrix degradation of IL-1β-induced chondrocytes. RUNX2 overexpression counteracted the suppressive effect of miR-142-5p mimic on apoptosis and cartilage matrix degradation of IL-1β-induced chondrocytes.Conclusion: Exosomal PCGEM1 from OA-FLSs facilitated IL-1β-induced apoptosis and cartilage matrix degradation in chondrocytes by sequestering miR-142-5p and upregulating RUNX2, which offered new insights into the pathogenesis of OA.

Downregulation of miR-892b inhibits the progression of osteoarthritis via targeting cyclin D1 and cyclin D2

BACKGROUNDS

Osteoarthritis (OA) is an orthopedic inflammatory disease which can cause functional disability and chronic pain. MiRNAs are known to play important roles in OA. To identify the targets for the treatment of OA, bioinformatics analysis was performed to explore differentially expressed miRNAs between OA and normal samples.

METHODS

Bioinformatics analysis was conducted to identify differentially expressed miRNAs. To mimic OA in vitro, primary chondrocytes were stimulated with IL-1β. Meanwhile, flow cytometry was performed to detect the cell apoptosis and cycle distribution. In addition, protein and mRNA expressions were detected by Western blot and RT-qPCR, respectively. Finally, in vivo model of OA was constructed to investigate the function of miR-892b in OA.

RESULTS

The data indicated that miR-892b was identified to be upregulated in OA samples. Additionally, miR-892b antagomir markedly reversed IL-1β-induced growth decline of chondrocytes via inhibiting the apoptosis. IL-1β notably elevated the expressions of MMP1 and MMP13 and downregulated the level of Aggrecan in chondrocytes, while miR-892b antagomir reversed these phenomena. Meanwhile, cyclin D1 and cyclin D2 were the direct targets of miR-892b. In addition, IL-1β-induced G1 phase arrest in chondrocytes was partially abolished by of miR-892b antagomir. In vivo study indicated miR-892b antagomir could significantly alleviate the symptom of OA in a rat model.

CONCLUSION

MiR-892b antagomir inhibits the progression of OA via targeting Cyclin D1 and Cyclin D2. Thus, our finding might supply a novel target for OA treatment.

Exosomal circ-BRWD1 contributes to osteoarthritis development through the modulation of miR-1277/TRAF6 axis

Background

Circular RNAs (circRNAs) can act as vital players in osteoarthritis (OA). However, the roles of circRNAs in OA remain obscure. Herein, we explored the roles of exosomal circRNA bromodomain and WD repeat domain containing 1(circ-BRWD1) in OA pathology.

Methods

In vitro model of OA was constructed by treating CHON-001 cells with interleukin-1β (IL-1β). Quantitative real-time polymerase chain reaction (qRT-PCR) assay was used for circ-BRWD1, BRWD, miR-1277, and TNF receptor-associated factor 6 (TRAF6) levels. RNase R assay was conducted for the feature of circ-BRWD1. Transmission electron microscopy (TEM) was employed to analyze the morphology of exosomes. Western blot assay was performed for protein levels. Cell Counting Kit-8 (CCK-8) assay, flow cytometry analysis, and 5-Ethynyl-2′-deoxyuridine (EDU) assay were adopted for cell viability, apoptosis, and proliferation, respectively. Enzyme-linked immunosorbent assay (ELISA) was carried out for the concentrations of interleukin-6 (IL-6) and interleukin-8 (IL-8). Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to analyze the interaction between miR-1277 and circ-BRWD1 or TRAF6.

Results

Circ-BRWD1 was increased in OA cartilage tissues, IL-1β-treated CHON-001 cells, and the exosomes derived from IL-1β-treated CHON-001 cells. Exosome treatment elevated circ-BRWD1 level, while exosome blocker reduced circ-BRWD1 level in IL-1β-treated CHON-001 cells. Silencing of circ-BRWD1 promoted cell viability and proliferation and repressed apoptosis, inflammation, and extracellular matrix (ECM) degradation in IL-1β-stimulated CHON-001 cells. For mechanism analysis, circ-BRWD1 could serve as the sponge for miR-1277 to positively regulate TRAF6 expression. Moreover, miR-1277 inhibition ameliorated the effects of circ-BRWD1 knockdown on IL-1β-mediated CHON-001 cell damage. Additionally, miR-1277 overexpression relieved IL-1β-induced CHON-001 cell injury, while TRAF6 elevation restored the impact.

Conclusion

Exosomal circ-BRWD1 promoted IL-1β-induced CHON-001 cell progression by regulating miR-1277/TRAF6 axis.

Auto-antibodies to post-translationally modified proteins in osteoarthritis

OBJECTIVE

Autoantibodies (AutoAbs) have been observed in osteoarthritis (OA) with broad antigenicity, although their prevalence and role remain unclear. Post-translational modification (PTMs) of proteins (oxidation, carbamylation, citrullination) is associated with synovitis and can lead to AutoAb development. Given the prevalence of synovitis, we explored whether AutoAbs to PTM-antigens are common in OA compared with rheumatoid arthritis (RA).

METHODS

Serum (n = 895) was obtained from healthy controls, OA and RA patients; and arthritic synovial fluid (SF, n = 290). ELISAs were used to quantify anti-citrullinated peptide (ACPA), anti-carbamylated protein (anti-CarP), anti-oxidized collagen (anti-ROS-CI/CII) antibodies.

RESULTS

In sera, positivity for PTM-antigens AutoAbs was observed at a lower frequency in OA with 64.1% (95%CI: 57.2-70.1%) more ACPA+ and 29.8% (21.0-37.3%) more anti-CarP + patients in RA (both P < 0.0001). Levels of ACPA, anti-CarP were also lower in OA (P < 0.0001). Anti-ROS-CII positivity was lower in OA compared to RA (16.6%, 4.8-28.6%) less frequent, P = 0.033) but not anti-native-CII. There was no impact of age/gender on AutoAbs associations with diseases either looking at positivity or levels. In SF, OA patients were often ACPA+ (45.9%) although less frequently than in RA (P = 0.004). Anti-CarP were rarely observed (<5% all samples). All collagen AutoAbs were more frequent in RA compared to OA (all P < 0.010) but only levels of anti-CII and anti-ROS-CII were significantly higher in they RA (P < 0.050).

CONCLUSION

Although the frequency of AutoAbs for PTM proteins were lower in OA sera compared to RA, a higher proportion of OA SF were positive. The relative retention of AutoAbs in the OA joint requires further investigation.

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

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

Acetabular margin changes in feline hip joints - Implications for radiologic diagnosis and development of osteoarthritis

The development and early morphological features of feline hip osteoarthritis (OA) are largely unknown. Tears in the acetabular labrum and at the chondrolabral transition zone are suggested to be important in the pathogenesis of human hip OA, but in cats such lesions have not been described. We investigated associations between computed tomography (CT)-detected joint changes and microscopic articular cartilage lesions, the distribution of detected changes, and histologically evaluated the acetabular margin (AM) in hip joints from 20 cats. Histologic evaluation was undertaken on at least one joint from each cat. CT-detected joint changes and articular cartilage lesions were graded and the histological appearance of CT-detected osteophytes evaluated. The majority of CT-detected lesions and cartilage lesions were mild. Whole-joint CT scores and AM osteophyte CT scores showed moderate to strong correlation with cartilage scores. The odds were higher for presence of CT-detected osteophytes in craniodorsal, cranial, cranioventral, ventral and dorsal AM regions. Peripheral acetabular regions showed higher cartilage lesion grades than central regions. Tears, seen as fissures/clefts, in labral and perilabral tissues were common. CT-detected AM osteophytes morphologically presented as pointed sclerotic bone, spur-shaped bone or rounded chondro-osteophytes. The results suggest that CT is a valuable tool for diagnosing early feline hip OA. CT-detected osteophytes showed variable histologic morphologies, which may implicate different disease mechanisms and/or disease stages. Tears in the AM could represent an early event in feline hip OA and this warrants further investigation.

Osteoarthritis: Novel Molecular Mechanisms Increase Our Understanding of the Disease Pathology

Although osteoarthritis (OA) is the most common musculoskeletal condition that causes significant health and social problems worldwide, its exact etiology is still unclear. With an aging and increasingly obese population, OA is becoming even more prevalent than in previous decades. Up to 35% of the world’s population over 60 years of age suffers from symptomatic (painful, disabling) OA. The disease poses a tremendous economic burden on the health-care system and society for diagnosis, treatment, sick leave, rehabilitation, and early retirement. Most patients also experience sleep disturbances, reduced capability for exercising, lifting, and walking and are less capable of working, and maintaining an independent lifestyle. For patients, the major problem is disability, resulting from joint tissue destruction and pain. So far, there is no therapy available that effectively arrests structural deterioration of cartilage and bone or is able to successfully reverse any of the existing structural defects. Here, we elucidate novel concepts and hypotheses regarding disease progression and pathology, which are relevant for understanding underlying the molecular mechanisms as a prerequisite for future therapeutic approaches. Emphasis is placed on topographical modeling of the disease, the role of proteases and cytokines in OA, and the impact of the peripheral nervous system and its neuropeptides.

Oleic acid induces A7r5 cell proliferation and migration associated with increased expression of HGF and p‑p38

The phenotypes and mechanisms underlying the proliferation and migration of vascular smooth muscle cells (VSMCs) induced by oleic acid (OA) are not completely understood. Therefore, the aim of the present study was to further elucidate the effects of OA on the proliferation and migration of VSMCs. Using A7r5 cells, the hepatocyte growth factor (HGF) inhibitor PHA665752 and the p38 MAPK inhibitor SB203580 were utilized, and Cell Counting Kit-8 (CCK-8) assays, Transwell assays, flow cytometry, ELISAs, western blotting and reverse transcription-quantitative PCR (RT-qPCR) were conducted to assess the effects of OA. CCK-8 assays indicated that OA promoted (at 5 and 50 µmol/l) or inhibited (at 800 µmol/l) A7r5 cell proliferation in a time- and concentration-dependent manner (P<0.05). Transwell assays revealed that OA also promoted (at 50 µmol/l) or inhibited (at 800 µmol/l) A7r5 cell migration (P<0.05). Moreover, cell-cycle analysis identified that 50 µmol/l OA reduced the cellular population in the G₀/G₁ phase and enhanced the cellular population in the S phase (P<0.05), whereas 800 µmol/l OA increased the cell number in the G₀/G₁ phase and decreased the cell number in the S phase (P<0.05). In addition, OA promoted (at 50 µmol/l) or inhibited (at 800 µmol/l) the expression level of HGF in A7r5 cells, as demonstrated via ELISA, western blotting and RT-qPCR analyses (P<0.05). It was also found that OA promoted (at 50 µmol/l) or inhibited (at 800 µmol/l) the expression level of phosphorylated (p)-p38 in A7r5 cells, as indicated by western blotting (P<0.05). Furthermore, the cell proliferation, migration and HGF expression induced by OA (50 µmol/l) were mitigated by treatment with PHA665752 (0.1 µmol/l) (P<0.05), and the cell proliferation, migration and p-p38 expression induced by OA (50 µmol/l) were mitigated by SB203580 (2 µmol/l) (P<0.05). Thus, the results suggested that OA served a role in the proliferation and migration of VSMCs via HGF and the p38 MAPK pathway. Moreover, the proliferation and migration of VSMCs induced by OA was associated with increased expression levels of HGF and p-p38. Taken together, OA, HGF and p38 MAPK may be potential therapeutic targets for the treatment of atherosclerosis.

Vitamin D receptor gene polymorphisms and osteoarthritis: a meta-analysis

OBJECTIVE

To investigate the association of vitamin D receptor (VDR) gene polymorphisms with OA susceptibility.

METHODS

Meta-analyses were performed using allelic contrast, contrast of homozygotes, and recessive and dominant models to clarify the association between OA and VDR ApaI, BsmI, TaqI and FokI polymorphisms. Odds ratio (OR) and the corresponding 95% CI were obtained, and subgroup analyses were performed based on the ethnicity and OA sites.

RESULTS

A total of 18 studies with 2983 OA patients and 4177 controls were included in this meta-analysis. There were statistically significant associations in the spine between OA susceptibility and the VDR BsmI (B vs b: OR = 1.25, 95% CI: 1.03, 1.53, P = 0.026; BB vs bb: OR = 1.56, 95% CI: 1.02, 2.37, P = 0.038) and TaqI (T vs t: OR = 0.73, 95% CI: 0.54, 0.99, P = 0.044; TT vs Tt + tt: OR = 0.63, 95% CI: 0.42, 0.95, P = 0.028) polymorphisms, but not for the other polymorphisms. A statistically significant association was found between the VDR FokI polymorphism and OA susceptibility in the knee in the recessive model contrast (FF vs Ff + ff: OR = 0.63, 95% CI: 0.42, 0.95, P = 0.028), but this result was only pooled from one study. However, no significant associations were found between the VDR ApaI polymorphism and OA. Besides, ethnic stratification also indicated that there was no significant association between VDR gene polymorphism and OA in Caucasians or Asians.

CONCLUSION

Our meta-analysis suggests that the VDR BsmI and TaqI polymorphisms are associated with OA susceptibility in the spine. However, the VDR ApaI polymorphism is not a significant genetic risk factor for OA.

Mendelian randomization provides evidence for a causal effect of higher serum IGF-1 concentration on risk of hip and knee osteoarthritis

Objectives

How insulin-like growth factor-1 (IGF-1) is related to OA is not well understood. We determined relationships between IGF-1 and hospital-diagnosed hand, hip and knee OA in UK Biobank, using Mendelian randomization (MR) to determine causality.

Methods

Serum IGF-1 was assessed by chemiluminescent immunoassay. OA was determined using Hospital Episode Statistics. One-sample MR (1SMR) was performed using two-stage least-squares regression, with an unweighted IGF-1 genetic risk score as an instrument. Multivariable MR included BMI as an additional exposure (instrumented by BMI genetic risk score). MR analyses were adjusted for sex, genotyping chip and principal components. We then performed two-sample MR (2SMR) using summary statistics from Cohorts for Heart and Aging Research in Genetic Epidemiology (CHARGE) (IGF-1, N = 30 884) and the recent genome-wide association study meta-analysis (N = 455 221) of UK Biobank and Arthritis Research UK OA Genetics (arcOGEN).

Results

A total of 332 092 adults in UK Biobank had complete data. Their mean (s.d.) age was 56.5 (8.0) years and 54% were female. IGF-1 was observationally related to a reduced odds of hand OA [odds ratio per doubling = 0.87 (95% CI 0.82, 0.93)], and an increased odds of hip OA [1.04 (1.01, 1.07)], but was unrelated to knee OA [0.99 (0.96, 1.01)]. Using 1SMR, we found strong evidence for an increased risk of hip [odds ratio per s.d. increase = 1.57 (1.21, 2.01)] and knee [1.30 (1.07, 1.58)] OA with increasing IGF-1 concentration. By contrast, we found no evidence for a causal effect of IGF-1 concentration on hand OA [0.98 (0.57, 1.70)]. Results were consistent when estimated using 2SMR and in multivariable MR analyses accounting for BMI.

Conclusion

We have found evidence that increased serum IGF-1 is causally related to higher risk of hip and knee OA.

LncRNA MEG3 Protects Chondrocytes From IL-1β-Induced Inflammation via Regulating miR-9-5p/KLF4 Axis

Background

Osteoarthritis (OA) is a chronic degenerative disease of the joints characterized by articular cartilage damage, subchondral bone remodeling, osteophyte formation, and inflammatory changes. This work aims to investigate the protective role of long non-coding RNA (lncRNA) maternally expressed 3 (MEG3) against the apoptosis of chondrocytes.

Methods

Chondrocyte cell lines, CHON-001, and ATDC5 were treated with different doses of interleukin-1β (IL-1β) to mimic the inflammatory response during OA pathogenesis. Quantitative real-time polymerase chain reaction was performed to measure MEG3, miR-9-5p, and Krüppel-like factor 4 (KLF4) mRNA expression levels. MEG3 and KLF4 overexpression plasmids, MEG3 shRNA, miR-9-5p mimics, and miR-9-5p inhibitors were transfected into the cells. Cell counting kit-8, wound healing assay, and flow cytometry were conducted to determine cell viability, migration, and apoptotic rate. Dual-luciferase reporter assay was adopted to verify the targeting relationships among MEG3, miR-9-5p, and KLF4. Western blot was used to detect KLF4 protein expression. Enzyme-linked immunosorbent assay was employed to measure the levels of inflammatory factors.

Results

MEG3 expression in chondrocytes was down-regulated by the stimulation of IL-1β, and MEG3 negatively regulated miR-9-5p expression but positively regulated KLF4 expression. MEG3 overexpression strengthened the viability and migration of CHON-001 and ATDC5 cells but restrained the apoptosis and inflammatory response, while MEG3 knockdown had opposite effects. miR-9-5p inhibition or KLF4 overexpression could counteract the effects of MEG3 knockdown on chondrocytes. Besides that, MEG3 was proved to be a molecular sponge for miR-9-5p, and KLF4 was verified as the target of miR-9-5p.

Conclusion

MEG3 can promote chondrocyte proliferation and migration and inhibit apoptosis and inflammation by sponging miR-9-5p to induce KLF4 expression, which provides a promising therapy target for OA treatment.

Engeletin Protects Against TNF-α-Induced Apoptosis and Reactive Oxygen Species Generation in Chondrocytes and Alleviates Osteoarthritis in vivo

Purpose

Osteoarthritis (OA) is a progressive disease characterized by pain and impaired joint functions. Engeletin is a natural compound with anti-inflammatory and antioxidant effects on other diseases, but the effect of engeletin on OA has not been evaluated. This study aimed to elucidate the protective effect of engeletin on cartilage and the underlying mechanisms.

Methods

Chondrocytes were isolated from rat knee cartilage, and TNF-α was used to simulate OA in vitro. After treatment with engeletin, the expression of extracellular matrix (ECM) components (collagen II and aggrecan) and matrix catabolic enzymes (MMP9 and MMP3) was determined by Western blotting and qPCR. Chondrocyte apoptosis was evaluated using Annexin V-FITC/PI and flow cytometry. Apoptosis-related proteins (Bax, Bcl-2, and cleaved caspase-3) were evaluated by Western blotting. The mitochondrial membrane potential of chondrocytes was measured with JC-1, and intracellular reactive oxygen species (ROS) levels were determined with DCFH-DA. Changes in signaling pathways (Nrf2, NF-κB and MAPK) were evaluated by Western blotting. In vivo, anterior cruciate ligament transection (ACLT) was used to induce the rat OA model, and engeletin was administered intraarticularly. The therapeutic effect of engeletin was analyzed by histopathological analysis.

Results

Pretreatment with engeletin alleviated TNF-α-induced inhibition of ECM components (collagen II and aggrecan) and upregulation of matrix catabolic enzymes (MMP9 and MMP3). Engeletin ameliorated chondrocyte apoptosis by inhibiting Bax expression and upregulating Bcl-2 expression. Engeletin maintained the mitochondrial membrane potential of chondrocytes and scavenged intracellular ROS by activating the Nrf2 pathway. The NF-κB and MAPK pathways were inhibited by treatment with engeletin. In vivo, ACLT-induced knee OA in rats was alleviated by intraarticular injection of engeletin.

Conclusion

Engeletin ameliorated OA in vitro and in vivo. It may be a potential therapeutic drug for OA.

MK801 regulates the expression of key osteoarthritis factors in osteoarthritis synovial fibroblasts through complement C5

BACKGROUND

Osteoarthritis is currently one of the most common chronic diseases. As life expectancy increases, its prevalence and incidence are expected to rise. At present, more and more evidences prove the correlation between the complement system and osteoarthritis (OA). This study aims to investigate complement C5's influence on the effect of MK801 on osteoarthritis synovial fibroblasts (OA-SFs).

METHODS

We used IL-1b to induce OA-SFs derived from mice to obtain OA-SFs. And we performed RT-PCR and Western Blot assays to evaluate the expression levels of associated mRNA and protein. The alteration of MAC expression on OA-SFs cell membrane was evaluated by immunofluorescence assay. The expression of related inflammatory factors of OA-SFs was evaluated by ELISA experiment.

RESULTS

MK801 could significantly inhibit the expression of osteoarthritis (OA) marker factors, such as: membrane attack complex (MAC), tumor necrosis factor-α (TNF-α) and matrix metalloproteinase-13 (MMP13). Meanwhile, MK801 can significantly inhibit the expression of complement C5 (C5) in OA-SFs. Immunofluorescence assay showed that MAC expression on OA-SFs cell membrane was significantly inhibited by MK801. The nucleo-plasmic separation experiment demonstrated that MK801 could significantly inhibit the activation of Nuclear factor-κB (NF-κB) signaling pathway in OA-SFs. Futhermore, koncking down the expression of C5 reversed the inhibition MK801 on the expression of OA-SFs inflammatory factors.

CONCLUSIONS

These results illustrated two points: first, MK801 inhibited the generation of MAC and the release of inflammation factors in OA-SFs through C5; second: MK801 inhibited the activation of NF-κB signaling pathway in OA-SFs.

Two-year clinical outcomes of autologous microfragmented adipose tissue in elderly patients with knee osteoarthritis: a multi-centric, international study

PURPOSE

The aim of this study is to evaluate the outcomes of autologous microfragmented adipose tissue (MFAT) injection in elderly patients with knee osteoarthritis (OA). We hypothesized that MFAT knee infiltration for the treatment of knee OA would yield good clinical results out to two years follow-up.

METHODS

Multi-centric, international, open-label study conducted by orthopedic surgery, and/or regenerative medicine facilities utilizing patient registries. Subjects recruited for eligibility. The primary outcome measure was Knee Injury and Osteoarthritis Outcome Score (KOOS). Outcomes and patient factors were compared to baseline, at six, 12, and 24 months. Statistical models were used to assess KOOS subscores and probability of exceeding the Minimally Clinically Important Difference (MCID) or Patient Acceptable Symptom State (PASS), and to assess the effect of the treatment variables on KOOS - Pain.

RESULTS

Seventy-five patients, 120 primary treatments, mean age 69.6 years, (95%CI 68.3-70.9), BMI 28.4 (95%CI 27.3-29.6), with KL grade 2 to 4 knee OA treated with a single MFAT injection. KL grades 2 (15.1%), 3 (56.3%), and 4 (28.6%), with 20.8% of knees having previously undergone surgery. Patients with KL grade 2 disease had the best results in KOOS - Pain (P = 0.001), at six, 12, and 24 months. Including advanced KL grade 3 and 4 osteoarthritis patients, significant functional and quality of life success was seen in 106/120 treatments (88.3%, 66 patients) at all follow-up time points. Fourteen treatments (11.7%, 9 patients) failed prior to the study endpoint.

CONCLUSION

This study shows that a single-dose MFAT injection leads to clinical, functional, and quality of life improvement at two years in elderly patients, in KL grades 2 to 4 of knee osteoarthritis. These findings provide evidence that this treatment modality could be a safe and effective option to other commonly available treatments in carefully selected patients.

MicroRNA-200b relieves LPS-induced inflammatory injury by targeting FUT4 in knee articular chondrocytes in vitro

Osteoarthritis (OA), characterized by the degeneration of articular cartilage, is a major problem in aging populations, and cartilage chondrocytes have been indicated to serve a curial role in the progression of OA. MicroRNA-200b-3p (miR-200b) was preliminarily identified to participate in OA. However, its role and mechanism of action in injured chondrocytes in OA remain unclear to date. In the present study, lipopolysaccharide (LPS)-treated cells isolated from normal knee articular cartilage were used to mimic inflammatory injury of OA chondrocytes. Cell viability, apoptosis and inflammatory responses were detected using Cell Counting Kit-8, flow cytometry and enzyme-linked immunosorbent assay, respectively. The expression levels of miR-200b and fucosyltransferase-4 (FUT4) were measured by reverse transcription-quantitative PCR and western blotting. The association between miR-200b and FUT4 was verified using TargetScan software, dual-luciferase reporter assay and RNA immunoprecipitation. The results indicated that LPS treatment decreased cell viability of primary chondrocytes, and increased apoptosis rate and production of IL-1β, IL-6 and TNF-α. The expression level of miR-200b was downregulated, and that of FUT4 was upregulated in OA cartilage tissues and LPS-treated normal chondrocytes compared with normal cartilage tissues and chondrocytes. Overexpression of miR-200b via transfection with miR-200b mimic inhibited the apoptosis rate and reduced the levels of IL-1β, IL-6 and TNF-α in LPS-stimulated chondrocytes. However, the suppressive effect of miR-200b overexpression on the LPS-induced inflammatory injury in chondrocytes was reversed by the restoration of FUT4 levels. Notably, FUT4 was indicated to be a downstream target of miR-200b and was negatively regulated by miR-200b. Taken together, the results of the current study indicated that miR-200b protected chondrocytes from LPS-induced inflammatory injury in vitro by targeting FUT4. These findings revealed the miR-200b/FUT4 axis as a potential candidate to target the degeneration of cartilages, thereby inhibiting the progression of OA.

Curcumin Supplementation Enhances Bone Marrow Mesenchymal Stem Cells to Promote the Anabolism of Articular Chondrocytes and Cartilage Repair

Mesenchymal stem cells derived from bone marrows (BMSCs) and curcumin derived from turmeric were used for osteoarthritis (OA) treatment, respectively. We invested the effects of curcumin supplementation for BMSC therapeutic effects. In vitro, rat BMSCs were identified by dual-immunofluorescent staining of CD44 and CD90, and flow cytometry. Primary articular chondrocytes were identified by toluidine blue staining and immunofluorescent staining of Col2a1. EdU incorporation, migration assay, real-time quantitative polymerase chain reaction, and Western blot analyses were performed to evaluate the alterations of chondrocytes cocultured with BMSCs. In vivo, the rat model of OA was established by monoiodoacetic acid. After intra-articular injection of allogeneic BMSCs, articular cartilage damage and OA progression were evaluated by histological staining, and Osteoarthritis Research Society International and Mankin score evaluation. Although curcumin alone did not improve cell viability of primary articular chondrocytes, it promoted proliferation and migration of chondrocytes when cocultured with BMSCs. Meanwhile, the expression of anabolic genes in chondrocytes was remarkably increased both at mRNA and protein levels. In OA rats, curcumin and BMSCs cooperated to greatly promote articular cartilage repair and retard OA progression. Therefore, curcumin supplementation enhanced the BMSC function for the proliferation and migration of articular chondrocytes, and anabolic gene expression of extracellular matrix in articular chondrocytes in vitro, and the generation of articular cartilage in vivo. Our study shed light on the potential clinical application of curcumin cooperated with BMSCs in cartilage repair for OA treatment.

Feasibility of high dose medical exercise therapy in patients with long-term symptomatic knee osteoarthritis

Purpose: High repetition high dose medical exercise therapy (MET) is a promising treatment for patients with musculoskeletal pain. However, little is known regarding the feasibility of MET in patients with symptomatic knee osteoarthritis (OA). The aim of this study was to investigate the feasibility of MET in patients with symptomatic knee pain with radiographic verified OA.Methods: Patients with symptomatic knee osteoarthritis were recruited to a group-based high repetitive high dose MET intervention for 12 weeks in a primary health care setting. Indicators of feasibility included processes (recruitment, program adherence, and exercise compliance), and scientific feasibility (safety and pain evaluated by using the Visual Analogue Scale (VAS)).Results: Out of 31 individuals with symptomatic knee OA, 29 (93%) were included in this study. A total of 26 patients (90%) completed the intervention and 83% reached an attendance rate of ≥30 treatments. No adverse events were reported, and a majority of the patients reported a pain intensity <30 mm (VAS) throughout the intervention period. The results showed a 70% reduction of median pain intensity between baseline (33 mm, IQR: 39), and post-assessment (10 mm, IQR: 25, P = .003).Conclusion: These findings support an overall positive feasibility of MET for patients with symptomatic knee OA. The results also demonstrated that achieving a high dose of exercises might be challenging for this population. Thus, individual variations in exercise dose may be a confounding factor when evaluating high dose MET in future clinical studies.

Potential efficacy of dendritic cell immunomodulation in the treatment of osteoarthritis

Dendritic cells (DCs) are a cluster of heterogeneous antigen-presenting cells that play a pivotal role in both innate and adaptive immune responses. Rare reports have discussed their role in OA immunopathogenesis. Recently, DCs derived from the synovial fluid of OA mice were shown to have increased expression of toll-like receptors. Moreover, from in vitro studies it was concluded that DCs derived from OA patients had secreted high levels of inflammatory cytokines. Likewise, a significant increase in CD123+BDCA-2 plasmacytoid DCs has been observed in the synovial fluid of OA patients. Furthermore, DCs have a peripheral tolerance potential and can become regulatory under specific circumstances. This could be exploited as a promising tool to eliminate immunoinflammatory manifestations in OA disease. In this review, the potential roles DCs could play in OA pathogenesis have been described. In addition, suggestions for the development of new immunotherapeutic strategies involving intra-articular injections of tolerogenic plasmacytoid DCs for treating OA inflammations have been made.

Natural and Anthropogenic Drivers of Acidification in Large Estuaries

Oceanic uptake of anthropogenic carbon dioxide (CO₂) from the atmosphere has changed ocean biogeochemistry and threatened the health of organisms through a process known as ocean acidification (OA). Such large-scale changes affect ecosystem functions and can have impacts on societal uses, fisheries resources, and economies. In many large estuaries, anthropogenic CO₂-induced acidification is enhanced by strong stratification, long water residence times, eutrophication, and a weak acid-base buffer capacity. In this article, we review how a variety of processes influence aquatic acid-base properties in estuarine waters, including coastal upwelling, river-ocean mixing, air-water gas exchange, biological production and subsequent aerobic and anaerobic respiration, calcium carbonate (CaCO₃) dissolution, and benthic inputs. We emphasize the spatial and temporal dynamics of partial pressure of CO₂ (pCO₂), pH, and calcium carbonate mineral saturation states. Examples from three large estuaries-Chesapeake Bay, the Salish Sea, and Prince William Sound-are used to illustrate how natural and anthropogenic processes and climate change may manifest differently across estuaries, as well as the biological implications of OA on coastal calcifiers.

Foot orthoses for first metatarsophalangeal joint osteoarthritis: study protocol for the FORT randomised controlled trial

Background

First metatarsophalangeal (MTP) joint osteoarthritis (OA) is a painful and debilitating condition affecting nearly one in 10 people aged over 50 years. Non-drug, non-surgical treatments are recommended by OA clinical guidelines, yet there have only ever been two randomised controlled trials (RCTs) evaluating such strategies in people with first MTP joint OA. Foot orthoses are a common non-drug, non-surgical strategy used by allied health professionals for people with first MTP joint OA, however, it is unknown whether these devices are effective in improving the symptoms associated with the condition. This clinical trial aimed to determine whether contoured foot orthoses lead to greater reductions in first MTP joint pain on walking compared to sham flat insoles in people with first MTP joint OA.

Methods

The FORT trial (Foot ORthoses for big Toe joint osteoarthritis) is a two-arm participant- and assessor-blinded, multi-site RCT conducted in Melbourne, Sydney, Brisbane and the Gold Coast, Australia. We are recruiting 88 community-dwelling people with symptomatic radiographic first MTP joint OA. Following baseline assessment, participants are randomized to receive either: i) contoured foot orthoses; or ii) sham flat insoles following baseline assessment. Participants have two visits with a study podiatrist where they are provided with their allocated insoles, to be worn daily for 12 weeks at all times when wearing shoes. The primary outcome is self-reported first MTP joint pain on walking (numerical rating scale), assessed at baseline and 12 weeks. Secondary outcomes include additional measures of first MTP joint and foot pain, physical function, quality of life, participant-perceived global ratings of change (pain and function), and level of physical activity.

Discussion

This study will provide novel evidence about whether contoured foot orthoses improve pain and other symptoms compared to sham insoles in people with first MTP joint OA. Outcomes will help to inform clinical guidelines and practice about the use of foot orthoses for managing symptoms in this under-researched group of people with OA.

Trial registration

Prospectively registered with the Australian New Zealand Clinical Trials Registry (reference: ACTRN12619000926134) on 3/07/2019.

Current and emerging treatments for albinism

Albinism is a group of rare inherited disorders arising from impairment of melanin biosynthesis. The reduction of melanin synthesis leads to hypopigmentation of the skin and eyes. A wide range of ophthalmic manifestations arise from albinism, including reduction of visual acuity, nystagmus, strabismus, iris translucency, foveal hypoplasia, fundus hypopigmentation, and abnormal decussation of retinal ganglion cell axons at the optic chiasm. Currently, albinism is incurable, and treatment aims either surgically or pharmacologically to optimize vision and protect the skin; however, novel therapies that aim to directly address the molecular errors of albinism, such as l-dihydroxyphenylalanine and nitisinone, are being developed and have entered human trials though with limited success. Experimental gene-based strategies for editing the genetic errors in albinism have also met early success in animal models. The emergence of these new therapeutic modalities represents a new era in the management of albinism. We focus on the known genetic subtypes, clinical assessment, and existing and emerging therapeutic options for the nonsyndromic forms of albinism.

TWIST1-MicroRNA-10a-MAP3K7 Axis Ameliorates Synovitis of Osteoarthritis in Fibroblast-like Synoviocytes

Synovitis refers to the inflammation of the synovial membrane and is commonly detected in patients with osteoarthritis (OA). Recent reports have suggested that microRNAs (miRNAs) could be a promising target for diagnosis and prognosis in OA. This study examines the effect of microRNA-10a (miR-10a) in fibroblast-like synoviocyte (FLS)-mediated synovitis obtained from patients with OA. Expression of miR-10a is negatively associated with the severity of synovitis. miR-10a inhibited proliferation, migration, and secretion of pro-inflammatory cytokines of OA-FLS that were obtained from OA patients in vitro. By using a patient-derived xenograft (PDX) model, miR-10a repressed proliferation of OA-FLSs and production of OA synovium-derived pro-inflammatory cytokines in vivo. Twist Family BHLH Transcription Factor 1 (TWIST1) and mitogen-activated protein kinase kinase kinase 7 (MAP3K7) were identified as an upstream regulator and direct target of miR-10a in OA-FLSs, respectively. Nuclear factor κB (NF-κB) signaling pathway, a downstream pathway of MAP3K7, was also repressed by miR-10a in OA-FLSs. To summarize, the TWIST1-miR-10a-MAP3K7-NF-κB pathway mediates the development of synovitis in OA. miR-10a functions as an anti-inflammatory mediator in OA-FLS.