Synovial Fluid IL-6 Research Articles

Effects of human umbilical cord mesenchymal stem cell-derived exosomes in the rat osteoarthritis models.

Mesenchymal stem cells (MSCs) offer great potential for treatment of osteoarthritis (OA) by promoting articular cartilage regeneration via paracrine secretion of exosomes; however, the underlying mechanisms are not fully understood. This study aimed to explore the therapeutic effects of exosomes secreted by human umbilical cord-derived MSCs (hUC-MSCs) in rat models of OA and reveal the underlying mechanisms. UC-MSCs and UC-MSC-exosomes were prepared and identified by transmission electron microscopy and flow cytometry. IL-1β-induced OA chondrocytes and the operation and collagenase-induced OA rat models were established. The results of micro-computed tomography, histology, and immunohistochemistry showed that UC-MSC-exosomes promoted cartilage regeneration in OA rats. ELISA results showed that the levels of synovial fluid cytokines, TNF-α, IL-1β, and IL-6, were lower in exosome therapy group than control group in both OA rat models. Exosome treatment significantly downregulated the expression of MMP-13 and ADAMTS-5 in chondrocytes stimulated by IL-1β, and upregulated collagen II expression. These findings suggest that hUC-MSC-exosomes offer a promising option for the therapy for OA.

Pre-Operative Adiposity and Synovial Fluid Inflammatory Biomarkers Provide a Predictive Model for Post-Operative Outcomes Following Total Joint Replacement Surgery in Osteoarthritis Patients

A proportion of osteoarthritis (OA) patients are unsatisfied with post-operative outcomes following total joint replacement surgery (TJR), with insufficient pain relief or poor functional improvement. Predicting those who will have poor outcomes would be beneficial for patients and clinicians. The aim of this study was to determine the relationship between baseline anthropometric data and the concentration of pre-operative serum and peri-operative synovial fluid (SF) cytokines and 7-month post-operative outcomes in a cohort of knee and hip OA patients. 160 OA patients were recruited who were scheduled for TJR. The concentration of 24 cytokines was measured in blood and SF by multiplex assay. EQ5D index health status was assessed pre-operatively and at 7 months post-operatively. 13% of patients were identified as non-responders based on EQ5D index. Compared to responders, non-responders were of higher body mass index (BMI), had greater waist and hip circumference, and had higher levels of SF leptin but lower levels of SF resistin (p < 0.05). Linear regression analysis found a significant but weak relationship between pre-operative body weight and post-operative response (ΔEQ5D index; r = 0.222, p = 0.049). The combination of body weight with SF amphiregulin and SF IL-6 provided an improved predictive model of post-operative response (r = 0.470, p = 0.035).

Peptidoglycan in osteoarthritis synovial tissue is associated with joint inflammation

ObjectivesPeptidoglycan (PG) is an arthritogenic bacterial cell wall component whose role in human osteoarthritis is poorly understood. The purpose of this study was to determine if PG is present in synovial tissue of osteoarthritis patients at the time of primary total knee arthroplasty (TKA), and if its presence is associated with inflammation and patient reported outcomes.MethodsIntraoperative synovial tissue and synovial fluid samples were obtained from 56 patients undergoing primary TKA, none of whom had history of infection. PG in synovial tissue was detected by immunohistochemistry (IHC) and immunofluorescence microscopy (IFM). Synovial tissue inflammation and fibrosis were assessed by histopathology and synovial fluid cytokine quantification. Primary human fibroblasts isolated from arthritis synovial tissue were stimulated with PG to determine inflammatory cytokine response.ResultsA total of 33/56 (59%) of primary TKA synovial tissue samples were positive for PG by IHC, and PG staining colocalized with markers of synovial macrophages and fibroblasts by IFM. Synovial tissue inflammation and elevated IL-6 in synovial fluid positively correlated with PG positivity. Primary human fibroblasts stimulated with PG secreted high levels of IL-6, consistent with ex vivo findings. Interestingly, we observed a significant inverse correlation between PG and age at time of TKA, indicating younger age at time of TKA was associated with higher PG levels.ConclusionPeptidoglycan is commonly found in synovial tissue from patients undergoing TKA. Our data indicate that PG may play an important role in inflammatory synovitis, particularly in patients who undergo TKA at a relatively younger age.

TME disk deplasmanında synovial sıvı pro-inflamatuar sitokinlerin ve klinik bulguların değerlendirilmesi

Aims: Temporomandibular disorders (TMD) are common musculoskeletal disease that affects the soft tissues and bone structures of the temporomandibular joint (TMJ). Inflammatory mediators play a critical role in the etiology of TMD by affecting various molecular mechanisms. This study aims to investigate the effect of pro-inflammatory cytokines on TMJ internal derangements and evaluate the relationship between clinical features.
 Methods: Patients who underwent arthrocentesis because of TMD were included in this study. Patients were divided into 2 groups according to anterior disc displacement with reduction (Group 1) and without reduction ( Group 2). Clinical findings before and after the arthrocentesis were evaluated retrospectively. Synovial fluid TNF-α, IL-1β, and IL-6 levels were analyzed with the ELISA method. 
 Results: A total of 28 patients were included, with 15 patients in Group 1 and 13 patients in Group 2. All patients were female with an average age of 30.75±14.9. The average pre-operative pain score was 6.6±1.95 in all patients. After the arthrocentesis, the average pain score was 2.0 ( 1.0 - 2.5) and the difference was significant (p

Knee Osteotomy Decreases Joint Inflammation Based on Synovial Histology and Synovial Fluid Analysis

To examine the biological changes in the joints of patients with knee osteoarthritis (OA) before and after around-knee osteotomy (AKO), focusing on synovial fluid (SF) and synovial pathological changes. Patients who underwent AKO for medial compartment knee OA between 2019 and 2021 were examined. SF and synovium were obtained at the time of AKO and plate removal after bone union (mean, 16.8 months [range: 11-38 months] postoperatively). SF volume and interleukin (IL)-6 concentrations in SF were assayed using enzyme-linked immunosorbent assay. Synovitis was assessed histologically using a semiquantitative scoring system. Macrophage infiltration was assessed by immunohistochemistry using a semiquantitative score for F4/80 expression. The M1/M2 ratio was calculated using percentage of cells positive for CD80 and CD163. The expression of proinflammatory cytokines was assessed by the percentage of IL-1β- and IL-6-positive cells. The number of vascular endothelial growth factor-positive luminal structures was counted to assess angiogenesis. The change in each parameter was compared before and after AKO using the Wilcoxon matched-pairs signed-rank test. Twenty-four knees of 21 patients were included. SF volume and IL-6 concentration significantly decreased postoperatively (12.6 ± 2.1 mL vs 4.2 ± 0.6 mL; P < .0001 and 50.5 ± 8.6 pg/mL vs 20.7 ± 3.8 pg/mL; P= .0001, respectively). A significant reduction in synovitis score (P= .0001), macrophage infiltration (P < .0003), M1/M2 ratio (P < .0007), angiogenesis (P < .0001), and the percentage of IL-1β- and IL-6-positive cells in the intima (P < .008 and P < .002, respectively) was found after AKO. SF volume and IL-6 concentrations in the SF decreased and inflammatory synovium pathology improved after AKO. In addition to biomechanical changes, the biological environment of the joint can be improved after AKO. Level IV, retrospective therapeutic case series.

Better post-operative outcomes at 1-year follow-up are associated with lower levels of pre-operative synovitis and higher levels of IL-6 and VEGFA in unicompartmental knee arthroplasty patients.

Osteoarthritis (OA) is associated with inflammation, and residual inflammation may influence outcomes following knee arthroplasty. This may be more relevant for patients undergoing unicompartmental knee arthroplasty (UKA) due to larger remaining areas of native tissue. This study aimed to: (1) characterise inflammatory profiles for medial UKA patients and (2) investigate whether inflammation markers are associated with post-operative outcomes. This prospective, observational study has national ethics approval. Bloods, synovial fluid, tibial plateaus and synovium were collected from medial UKA patients in between 1 January 2021 and 31 December 2021. Cytokine and chemokine concentrations in serum and synovial fluid (SF) were measured with multiplexed assays. Disease severity of cartilage and synovium was assessed using validated histological scores. Post-operative outcomes were measured with Oxford Knee Score (OKS), Forgotten Joint Score (FJS-12) and pain scores. The study included 35 patients. SF VEGFA was negatively correlated with pre-operative pain at rest (r -0.5, p = 0.007), and FJS-12 at six-week (r 0.44, p = 0.02), six-month (r 0.61, p < 0.01) and one-year follow-up (r 0.63, p = 0.03). Serum and SF IL-6 were positively correlated with OKS at early follow-up (serum 6weeks, r 0.39, p = 0.03; 6months, r 0.48, p < 0.01; SF 6weeks, r 0.35, p = 0.04). At six weeks, increased synovitis was negatively correlated with improvements in pain at rest (r -0.41, p = 0.03) and with mobilisation (r -0.37, p = 0.047). Lower levels of synovitis and higher levels of IL-6 and VEGFA were associated with better post-operative outcomes after UKA, which could be helpful for identifying UKA patients in clinical practice. Level IV case series.

Effects of platelet-rich plasma on subchondral bone marrow edema and biomarkers in synovial fluid of knee osteoarthritis

BackgroundThe aim of the study was to investigate the effect of platelet-rich plasma (PRP) on subchondral bone marrow edema (BME) and the level of biomarkers in synovial fluid of the knee osteoarthritis. MethodsEighty-one patients with symptomatic knee osteoarthritis were randomly divided into two groups according to the number of inpatients. Forty-five cases were treated with intra-articular injection of PRP (PRP group), 36 cases were treated with sodium hyaluronate (SH group), and the clinical effects were evaluated using the Visual Analogue Scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. The changes of subchondral BME were assessed by magnetic resonance imaging (MRI) before and after treatment. The levels of TNFα, IL-6, MCP-1, MMP-1, MMP-3, and MMP-9 in synovial fluid were also detected. ResultsAll the patients completed the corresponding treatment and were followed up for 12 months without serious complications. After the treatment, the VAS and WOMAC scores of the two groups were significantly decreased, and the difference was statistically significant at different time points (P < 0.05). The VAS and WOMAC scores of the PRP group were better than those of the SH group (P < 0.05). MRI showed that the subchondral bone edema of the two groups were reduced in varying degrees, and the reduction was more noticeable in the PRP group (P < 0.05). The levels of TNFα, IL-6, MCP-1, MMP-1, MMP-3, and MMP-9 in two groups were decreased, and the difference was statistically significant at different time points (P < 0.05). However, the levels of TNFα, IL-6, MCP-1, MMP-1, MMP-3, and MMP-9 in the PRP group were significantly lower than those in the SH group (P < 0.05). ConclusionsIntra-articular injection of PRP can significantly reduce the subchondral BME and the level of biomarkers in synovial fluid of the symptomatic knee osteoarthritis.

Сellular composition and cytokine profile of synovial fluid in rheumatoid arthritis

Rheumatoid arthritis (RA) ranks first among chronic joint diseases. The disease often affects people at their working age, being accompanied by significant decrease in the life quality of patients and their early disability. Rheumatoid arthritis is an immunoinflammatory rheumatic disease. Therefore, the immune system provides evolving focus of primary damage, its persistence and periodic exacerbation. Elucidation of intercellular relationships mediated by cytokines at various stages of the chronic inflammatory process is required in order to develop immunotherapeutic approaches, aimed for both recovery from exacerbations and maintenance of remission state. Purpose of our study was to evaluate cellular composition and cytokine profile of synovial fluid in the patients with rheumatoid arthritis at acute phase and in remission state.We have studied the samples of synovial fluid taken in 60 patients with rheumatoid arthritis, with 30 subjects being at acute stage of the disease, and 30 patients in remission. Cellular composition and cytokine profile were assessed in the clinical samples. There were 21 women and 9 men at the acute stage (57.0±15.4 years old), with the disease duration of 8.55±6.9 years. The average age of 19 women and 11 men examined in remission state was 53.5±10.9 years, with comparable duration of illness (6.9±5.8 years). The leukocyte phenotyping was performed with a CytoFLEX flow cytometer (Beckman Coulter, USA). The cytokine contents were measured by enzyme immunoassay using a standard set of reagents from the “Proteinovy Contour” LLC (Russia). The results were registered by a Multiscan photometer (Labsystems, Finland).During the disease exacerbation, the leukocyte contents in synovial fluid increased 2.4-fold, as compared to the remission values. The cellular infiltrate was represented by neutrophils, whereas the contents of lymphocytes and monocytes did not change. Increased migration of neutrophils was accompanied by an 8-fold increase in TNFα levels, compared with remission state, and IL-1β levels were increased by 6.3 times. The absolute number of CD3+T lymphocytes, CD16+CD56+B cells, and CD3-CD19+NK during exacerbation was similar to the remission levels. However, the number of T cell subpopulations was changed, i.e., the number of CD4+ lymphocytes was decreased, and CD8+ cell counts were increased, like as numbers of Treg lymphocytes and NKT cells which showed a significant increase. A 4.3-fold increase in the IL-4 concentration during the RA exacerbation suggested the predominance of Th2 immune response. During remission, the concentrations of IL-6 and IFNγ in synovial fluid were increased, respectively, by 1.5 times and by 2.5 times, which is typical for activated Th1 response.

Synovial tissue metabolomic profiling reveal biomarkers of synovial inflammation in patients with osteoarthritis

ObjectiveInflammatory responses are associated with changes in tissue metabolism. Prior studies find altered metabolomic profiles in both the synovial fluid (SF) and serum of osteoarthritis subjects. Our study determined the metabolomic profile of synovial tissue (ST) and SF of individuals with osteoarthritis (OA) and its association with synovial inflammation. Design37 OA ST samples were collected during joint replacement, 21 also had SF. ST samples were fixed in formalin for histological analysis, cultured (explants) for cytokine analysis by enzyme-linked immunosorbent assay, or snap-frozen for metabolomic analysis. ST samples were categorized by Krenn synovitis score and picrosirius red. CD68 and vimentin expression was assessed by immunohistochemistry and semi-quantified using Image J. Proton-nuclear magnetic resonance (1H NMR) was used to acquire a spectrum from ST and SF samples. Chenomx NMR suite 8.5 was used for metabolite identification and quantification. Metaboanalyst 5.0, SPSS v26, and R (v4.1.2) were used for statistical analysis. Results42 and 29 metabolites were detected in the ST and SF respectively by 1H NMR. Only 3 metabolites, lactate, dimethylamine, and creatine positively correlated between SF and ST. ST concentrations of several metabolites (lactate, alanine, fumarate, glutamine, glycine, leucine, lysine, methionine, trimethylamine N-oxide, tryptophan and valine) were associated with synovitis score, mostly to the lining score. IL-6, acetoacetate, and tyrosine in SF predicted high Krenn synovitis scores in ST. ConclusionMetabolomic profiling of ST identified metabolic changes associated with inflammation. Further studies are needed to determine whether metabolomic profiling of synovial tissue can identify new therapeutic targets in osteoarthritis.

IL-36γ in enthesitis-related juvenile idiopathic arthritis and its association with disease activity.

IL-36 has been implicated in the pathogenesis of spondyloarthropathies (SpA) like psoriasis and inflammatory bowel disease. Enthesitis-related arthritis (ERA) category of juvenile idiopathic arthritis is a form of juvenile SpA, however, no data is available on the role of IL-36 in this disease. IL-36α, β, γ and IL-36R mRNA expression in blood and synovial fluid mononuclear cells and IL-36α, γ, IL-36Ra, IL-6, and IL-17 levels were measured in serum and synovial fluid (SF). IL-36γ production by fibroblast-like synoviocytes (FLS) upon stimulation with pro-inflammatory cytokines and its effect on FLS were also studied. mRNA levels of IL-36α, IL-36γ, and IL-36R were increased in PBMCs of ERA patients as compared to healthy controls however only IL-36γ was measurable in the serum of one-third of patients. In SFMCs, all four mRNA were detectable but were lower than RA patients. SF IL-36γ levels correlated with disease activity score (r = 0.51, P < 0.0001), SF IL-6 (r = 0.4, P = 0.0063) and IL-17 levels (r = 0.57, P = 0.0018). Pro-inflammatory cytokines increased the expression of IL-36γ and IL-6 in FLS cultures. SFs from five ERA patients also increased expressions of IL-36γ and IL-6 in FLS which could be blocked by using IL-36Ra. This suggests that pro-inflammatory cytokines aid in the upregulation of IL-36γ which in turn may upregulate the expression of IL-6. This might lead to a positive feedback loop of inflammation in ERA. Association of SF levels of IL-36γ with disease activity further supports this possibility. IL-36Ra based therapy may have a role in ERA.

Alleviation of Papain-Induced Osteoarthritis by Recombinant Human Endostatin via Downregulation of Matrix Metalloproteinase-13, Interleukin-1 and Interleukin-6 in Rats

Osteoarthritis (OA) is a degenerative disease of joints commonly occurring in the elderly and middleaged people. This study aimed to investigate the effect of recombinant human endostatin (rhEndo) on OA and the levels of MMP-13, IL-1 and IL-6 in the synovial fluid in osteoarthritis rats. OA models were made by injecting 4% papain into the knee joint cavity of rats once every three days for three times. The models were then injected subcutaneously with rhEndo and examined six weeks later for the Mankin scores and levels of MMP-13, IL-1 and IL-6 using ELISA. Compared with control, the Mankin score as well as the levels of IL-1, IL-6 and MMP-13 were significantly increased in the models (0.30 vs. 5.80, 1.12 vs. 12.84 pg/ mL, 12.22 vs. 43.82 pg/ mL and 0.23 vs. 26.31 ng/ mL). Following treatment with 4 mg/kg rhEndo, the Mankin score in model decreased to 0.90, meanwhile, the levels of IL-1, IL-6 and MMP-13 decreased significantly to 0.79 pg/ mL, 2.89 pg/mL and 1.17 ng/mL, respectively, in a dose dependent manner. Therefore, rhEndo can alleviate osteoarthritis by reducing MMP-13, IL-1 and IL-6 expression in rats.

Val109Asp Polymorphism of the Omentin-1 Gene and Incidence of Knee Osteoarthritis in a Chinese Han Population: A Correlation Analysis.

ObjectiveTo investigate the correlation of the Val109Asp polymorphism of the omentin-1 gene with the risk and severity of knee osteoarthritis (KOA) in a Chinese Han population.MethodsThis study enrolled 383 patients with primary KOA and 460 healthy controls. The genotypes were determined by the detection of single nucleotide polymorphism. To explore the interaction between omentin-1 gene polymorphism and obesity and age, the body mass index (BMI) of 25 kg/m2 and the age of 55 years old were preset as the cut-off value of stratified analysis. Furthermore, enzyme-linked immunosorbent assay was used to determine the levels of omentin-1, interleukin (IL)-1β, IL-6 in peripheral blood and synovial fluid and the contents of IL-1β, IL-6, metalloproteinase (MMP)-13 and collagen (COL)-II in the supernatant of knee joint cartilage tissue.ResultsThe Val109Asp polymorphism of the omentin-1 gene showed no obvious correlation with KOA. Compared with Asp/Asp genotype carriers with BMI <25 kg/m2 and age <55 years old, Val109 allele carriers with BMI≥25 kg/m2 and age ≥55 years old had obviously increased risk of KOA (adjusted OR = 1.416, p = 0.042; adjusted OR = 1.735, p = 0.038, respectively). In the KOA group, only the omentin-1 levels were significantly lower in the plasma and synovial fluid of Ala/Ala genotype carriers than in those of Asp/Asp genotype carriers. Meanwhile, the proportion of patients with moderate–severe K-L Classification, the levels of IL-1β, IL-6 in synovial fluid and the expression levels of IL-1β, IL-6 and MMP-13 in cartilage tissue significantly increased (p < 0.05). By contrast, the expression level of COL-II in cartilage tissue significantly decreased (p < 0.05).ConclusionsThe Val109Asp polymorphism of the omentin-1 gene may not be the primary pathogenic factor of KOA in Chinese. The Val/Val genotype can be regarded as a potential biomarker for the risk of KOA progression.

Hsa_circ_0134111 promotes osteoarthritis progression by regulating miR-224-5p/CCL1 interaction.

Mechanical, metabolic, inflammatory, and immune factors contribute to the development of osteoarthritis (OA), a joint disease characterized by cartilage destruction. The circular RNA (circRNA) hsa_circ_0134111 is upregulated in the cartilage of OA patients; however, its potential role in OA pathogenesis and progression remains unexplored. In this study, the effects of hsa_circ_0134111 knockdown were evaluated in primary human chondrocytes treated with IL-1β to simulate OA, as well as in a rat model of OA. Hsa_circ_0134111 expression was upregulated in IL-1β-stimulated chondrocytes. CCK-8 and flow cytometry assays showed that hsa_circ_0134111 knockdown reversed IL-1β-induced cell decline by inhibiting apoptosis. Following prediction analysis of circRNA and miRNA targets, dual-luciferase reporter and silencing/overexpression assays suggested that a regulatory network composed of hsa_circ_0134111, miR-224-5p, and CCL1 modulates IL-1β-mediated OA-like effects in chondrocytes. Accordingly, CCL1 overexpression abrogated the prosurvival effects of hsa_circ_0134111 knockdown in vitro. Moreover, hsa_circ_0134111 silencing in vivo alleviated cartilage destruction in an OA rat model, decreased IL-6 and TNF-α levels in synovial fluid, and downregulated CCL1 expression in the affected joints. These results suggest that hsa_circ_0134111 contributes to OA development by binding to miR-224-5p, thereby releasing the inhibition that miR-224-5p exerts over CCL1.

Research on the Effect of p35 for Secretion of Proinflammatory Factor and Apoptosis of Chondrocyte in Chondrocytopathic Articular Fluid

To study on the effect of transcriptional regulation factor as p35 for secretion of proinflammatory factor and apoptosis of chondrocyte in chondrocytopathic articular fluid so as to improve the chondropathy. The fifty SD rats were selected for our study. It was divided into three groups including A group (control group), B group (chondrocytopathic model group of osteoarthritis) and C group (transcriptional regulation factor as p35 intervention group. The samples were collected after intervention in sixteen weeks. The sampling position was cartilage tissue of rat leg. It was adopted for immunohistochemical inspection and histopathology examination. At the same time the synovial fluid was collected. The concentration of TNF-α and IL-6 was detected. And the expression of mRNA in gene related with apoptosis was detected. The chondrocyte morphology of rats in A group was normal. The chondrocyte was damaged and goblet cell was reduced in B group. The infiltrating inflammatory cells in C group were less than in B group from pathological results. And the goblet cells in C group was increased than in B group. The expression of TNF-α, Bax, NF-κB, IL-6: B group &gt; C group &gt; A group. The expression of Bcl-2: A group &gt; C group &gt; B group. The transcriptional regulation factor as p35 related with anti-apoptosis could regulate the level of inflammatory factor as TNF-α and IL-6 in synovial fluid and restrain the lesion and apoptosis of chondrocyte.

Clinical efficacy of repeated intra-articular pulsed radiofrequency for the treatment of knee joint pain and its effects on inflammatory cytokines in synovial fluid of patients.

The application value of repeated intra-articular pulsed radiofrequency for the treatment of knee joint pain has remained to be determined. To investigate this, a total of 64 patients with chronic knee joint pain admitted to Caoxian People's Hospital (Caoxian, Chine) between October 2016 and May 2018 were enrolled in the present study and analyzed prospectively. The patients were randomly divided into a control group, receiving treatment with a single intra-articular pulsed radiofrequency through the knee joint (n=32), and an experimental group, receiving multiple intra-articular pulsed radiofrequency treatments through the knee joint (n=32). The visual analog scale score (VAS), clinical efficacy and adverse reactions prior to and after treatment were compared between the two treatments. Synovial fluid cytokines were measured using ELISA prior to and after treatment. After the treatment, the control group and the experimental group both had a lower VAS (P<0.001) and the control group had a higher VAS and lower pain relief than the experimental group (P<0.001). The control group had a total effectiveness rate of 78.13%, with 13 patients experiencing complete relief (40.63%), 12 patients exhibiting a marked improvement (37.5%) and 7 patients reporting no effects (21.87%). The experimental group had a total effectiveness rate of 90.63%, with 18 patients (56.25%) being cured, 11 patients having a marked effect (34.37%) and 3 patients reporting no effects (9.38%). The experimental group had a higher incidence of adverse reactions than the control group (P<0.05). After treatment, the two groups had decreased IL-6, IL-10 and TNF-α levels in the knee joint synovial fluid (P<0.05), with the experimental group having lower cytokine levels than the control group (P<0.05). These results indicated that repeated intra-articular pulsed radiofrequency is an effective method for the treatment of knee joint pain and may be used in clinical practice.

Clinical and molecular associations with outcomes at 2 years after acute knee injury: a longitudinal study in the Knee Injury Cohort at the Kennedy (KICK).

SummaryBackgroundJoint injury is a major risk factor for osteoarthritis and provides an opportunity to prospectively examine early processes associated with osteoarthritis. We investigated whether predefined baseline demographic and clinical factors, and protein analytes in knee synovial fluid and in plasma or serum, were associated with clinically relevant outcomes at 2 years after knee injury.MethodsThis longitudinal cohort study recruited individuals aged 16–50 years between Nov 1, 2010, and Nov 28, 2014, across six hospitals and clinics in London, UK. Participants were recruited within 8 weeks of having a clinically significant acute knee injury (effusion and structural injury on MRI), which was typically treated surgically. We measured several predefined clinical variables at baseline (eg, time from injury to sampling, extent and type of joint injury, synovial fluid blood staining, presence of effusion, self-reported sex, age, and BMI), and measured 12 synovial fluid and four plasma or serum biomarkers by immunoassay at baseline and 3 months. The primary outcome was Knee Injury and Osteoarthritis Outcome Score (KOOS4) at 2 years, adjusted for baseline score, assessed in all patients. Linear and logistic regression models adjusting for predefined covariates were used to assess associations between baseline variables and 2-year KOOS4. This study is registered with ClinicalTrials.gov, number NCT02667756.FindingsWe enrolled 150 patients at a median of 17 days (range 1–59, IQR 9–26) after knee injury. 123 (82%) were male, with a median age of 25 years (range 16–50, IQR 21–30). 98 (65%) of 150 participants completed a KOOS4 at 2 (or 3) years after enrolment (50 participants were lost to follow-up and two were withdrawn due to adverse events unrelated to study participation); 77 (51%) participants had all necessary variables available and were included in the core variable adjusted analysis. In the 2-year dataset mean KOOS4 improved from 38 (SD 18) at baseline to 79 (18) at 2 years. Baseline KOOS4, medium-to-large knee effusion, and moderate-to-severe synovial blood staining and their interaction significantly predicted 2-year KOOS4 (n=77; coefficient −20·5, 95% CI −34·8 to −6·18; p=0·0060). The only predefined biomarkers that showed independent associations with 2-year KOOS4 were synovial fluid MCP-1 (n=77; −0·015, 0·027 to −0·004 per change in 1 pg/mL units; p=0·011) and IL-6 (n=77; −0·0005, −0·0009 to −0·0001 per change in 1 pg/mL units; p=0·017). These biomarkers, combined with the interaction of effusion and blood staining, accounted for 39% of outcome variability. Two adverse events occurred that were linked to study participation, both at the time of blood sampling (one presyncopal episode, one tenderness and pain at the site of venepuncture).InterpretationThe combination of effusion and haemarthrosis was significantly associated with symptomatic outcomes after acute knee injury. The synovial fluid molecular protein response to acute knee injury (best represented by MCP-1 and IL-6) was independently associated with symptomatic outcomes but not with structural outcomes, with the biomarkers overall playing a minor role relative to clinical predictors. The relationship between symptoms and structure after acute knee injury and their apparent dissociation early in this process need to be better understood to make clinical progress.FundingVersus Arthritis, Kennedy Trust for Rheumatology Research, and NIHR Oxford Biomedical Research Centre.

LncRNA FER1L4 is dysregulated in osteoarthritis and regulates IL-6 expression in human chondrocyte cells

Osteoarthritis (OA) is the most prevalent joint disease and is one of the major causes of disability in the world. There has been an increase in the incidence of OA, which is associated with an aging population, sedentary lifestyle, and reduced physical activity. Due to the complex OA pathogenesis, there are limited diagnostic tools. OA is a degenerative joint disorder with a recognized inflammatory component, usually described as abnormal expression of inflammatory factors. For instance, interleukin 6 (IL‐6) has been shown to be upregulated in serum and synovial fluid among patients with OA. Most of the inflammatory factors have been associated with the expression of long noncoding RNAs (lncRNAs). However, the role of the novel lncRNA Fer-1-like protein 4 (FER1L4) in OA is yet to be determined. Here, we interrogated the expression profile of FER1L4 in patients with OA to define its potential application as a diagnostic marker. We collected synovial fluid and blood samples from both OA cases and normal controls. Using qRT-PCR, we evaluated the expression of FER1L4 in plasma and synovial fluid. On the other hand, the expression of IL-6 in plasma and synovial fluid was assessed using ELISA. Besides, the effect of age, gender or disease stage in the expression of the FER1L4 in plasma was also estimated. Moreover, the receiver operating characteristic (ROC) curves were used to determine the impact of FER1L4 in OA cases compared with the normal controls. In addition, we analyzed the correlation between FER1L4 and IL-6 through Pearson correlation analysis. Also, IL-6 expression in overexpressed FER1L4 samples was detected in chondrocytes through western blot analysis, while FER1L4 expression following endogenous IL-6 exposure was detected by qRT-PCR. Our data showed that whereas lncRNA FER1L4 is downregulated in OA patients, IL‐6 is upregulated. The plasma FER1L4 levels among the OA cases were suppressed with disease progression and old age, and the down-regulation could efficiently discriminate OA patients from normal subjects. In addition, upregulation of FER1L4 inhibited IL‐6 expression in human chondrocyte cells, and treatment with different concentrations of exogenous IL‐6 did not affect the expression of FER1L4. Taken together, our data demonstrates that FER1L4 could efficiently identify OA cases from normal subjects, and can also modulate the expression of IL‐6 in human chondrocytes.

Changes of synovial fluid biomarker levels after opening wedge high tibial osteotomy in patients with knee osteoarthritis

The purpose of this study was to evaluate the effects of high tibial osteotomy (HTO) on the biological status of knee osteoarthritis (OA) using joint markers in synovial fluid (SF). Fifty patients with medial compartmental OA of the knee who underwent opening wedge HTO were enrolled. Paired SF samples from the affected knee and arthroscopic evaluation of articular cartilage were collected at the time of HTO surgery and the time of plate removal (postoperative 17±4 months). The concentrations of the following SF biomarkers were measured: interleukin (IL)-1β, IL-6, IL-8, IL-10, tumour necrosis factor-α, matrix metalloproteinase (MMP)-2, MMP-3, MMP-9, MMP-13, vascular endothelial growth factor (VEGF), and cartilage oligomeric matrix protein (COMP). The Knee Society Score (KSS) and hip-knee-ankle (HKA) angle were assessed before and 2 years after HTO. The KSS knee and function scores were significantly improved after HTO (mean changes of 36.4 and 23.7, respectively). The mean HKA angle was altered from mechanical varus (-8.6°) to valgus (5.2°). Concentrations of IL-6, IL-8, MMP-2, MMP-3, MMP-13, VEGF, and COMP in SF were significantly decreased after HTO (mean changes of-49.1%,-30.2%,-31.1%,-26.3%,-30.8%,-42.5%, and-13.7% from preoperative baseline, respectively). The cartilage status was improved in 19 cases (38%) after HTO. However, changes of all biomarkers were not significantly different between subjects with and without an improved cartilage status. SF levels of biochemical markers for cartilage degradation and synovial inflammation were altered after HTO, suggesting an improvement in the OA disease state.

Effect of infusion irrigation with different irrigating solutions on transient receptor potential vanilloid 5 and intra-articular inflammation in a post-traumatic osteoarthritis rabbit model

BackgroundThe incidence of post-traumatic osteoarthritis (PTOA) after anterior cruciate ligament reconstruction (ACLR) is high, but there is still a lack of intra-operative preventive measures. This study aimed to evaluate the effect of different irrigating solutions continuous irrigation on intra-articular inflammation and cartilage degeneration.Methods 66 New Zealand rabbits were randomly divided into normal (N) group, no treatment (NT) group, sodium chloride (NaCl) group, magnesium sulfate (MgSO4) group, and calcium chloride (CaCl2) group. The right knee joint of the experimental group was utilized to construct the model of PTOA, and the left side was utilized as the normal control group. At different time points postoperatively, the blood concentration of hemoglobin and Mg2 + , the synovial fluid concentration of IL-1 β, TNF-α, tartrate-resistant acid phosphatase-5b (TRAP-5b), and Type II Collagen, the gene expression of IL-1 β and MMP-3, and the protein expression of TRPV5 and CaM were detected. Pearson′s linear correlation was employed to identify the possible relationship between the expression of TRAP-5b and the expression of IL-1β, IL-6, TNF-α, and Type II collagen. The hematoxylin and eosin staining (HE), Masson’s trichrome staining, and Alcian blue staining were performed at postoperative 35 days. Osteoarthritis Scoring (OA score) comprised categories including Alcian blue staining, cartilage histology, the cellular density of cartilage, degree of cell disintegration, and formation of chondrocyte cluster were blindly scored by trained researchers at postoperative 35 days.ResultsThere was no statistical difference (P > 0.05) in the hemoglobin concentration between different groups. The concentration of serum Mg2+ in the MgSO4 group was higher than that of the other three groups (P < 0.05) on the same day of operation, then gradually decreased. The expression of IL-1 β, IL-6, and TRAP-5b in synovial fluid increased 5 days after the operation, decreased at 15 days, and then increased again with time in the NT group, NaCl group, and NT group and NaCl group. At 35 days after the operation, the expression of IL-1 β, IL-6, TRAP-5b, and type II collagen in the MgSO4 group were lower than that in the other three groups (except group N) (P < 0.05).The correlation analysis results showed that the TRAP-5b levels correlated positively with IL-1 β, IL-6, TNF-α, and type II collagen concentrations. The histological examination revealed that the surface smoothness of cartilage, the morphology of chondrocytes, the arrangement of collagen fibers, and the density of proteoglycan in the MgSO4 group were better than those in other experimental groups. At 35 days postoperatively, the gene expression of IL-1 β and MMP-3 and the protein expression of CaM and TRPV5 in synovium in the MgSO4 group was lower than that in the NaCl group and CaCl2 group.ConclusionIntra-operative irrigation with magnesium sulfate solution can inhibit the inflammatory factors and the expression of TRPV5, which can also reduce collagen loss and delay cartilage degeneration. Therefore, the use of magnesium sulfate in intra-operative irrigation may be an ideal choice to prevent PTOA.

Synovial fluid IL-1\u03b2 appears useful for the diagnosis of chronic periprosthetic joint infection

PurposeThe purpose of this study was to investigate the role of synovial fluid interleukin (IL)-1β in diagnosing chronic periprosthetic joint infection (PJI) and to identify the optimal threshold of synovial fluid IL-1β for differentiating chronic PJI from aseptic failure after knee and hip arthroplasties.MethodsBetween January 2019 and December 2019, we prospectively included patients scheduled to have a revision surgery for chronic PJI or aseptic failure after total joint arthroplasty. Then, synovial IL-1β was additionally measured along with routine preoperative diagnostic serum and synovial biomarkers. The receiver operating characteristic (ROC) curves and area under the curve (AUC) were analyzed for each biomarker to determine diagnostic efficacy.ResultsOf the 93 patients included, their demographic data were not found to be statistically significant. The median synovial IL-1β levels were significantly higher in the chronic PJI group than in the aseptic group (894.73 pg/mL vs. 34.49 pg/mL, P<0.01). The AUC for synovial fluid IL-1β was 0.991, which was higher than serum ESR (0.627) and CRP (0.712). The optimal threshold value for detecting chronic PJI of synovial IL-1β was 312.7 pg/mL, with a sensitivity of 97.3% and a specificity of 94.64%. And the combined measurement of synovial fluid IL-1β and synovial fluid PMN% can led to a specificity of 1, and a negative predictive value (NPV) of 1.ConclusionsThe present study demonstrated that synovial fluid IL-1β is a valuable biomarker for detection of chronic PJI. The combination of synovial fluid IL-1β and PMN% led to an improvement in specificity compared with evaluation of each single index.Trial registrationThis study was prospectively registered on the Chinese Clinical Trial Registry (a non-profit organization, established according to both the WHO International Clinical Trials Register Platform Standard and Ottawa Group Standard), and the registering number was ChiCTR1800020440. Registered on December 29, 2018.