OBJECTIVE: To analyze the differences in the effects of different mechanical stimuli on cells, cytokines, and proteins in synovial fluid of osteoarthritis joints, and to elucidate the indirect mechanism by which mechanical signals remodel the synovial fluid microenvironment through tissue cells. METHODS: Systematically integrate recent literature, focusing on the regulatory effects of different mechanical stimuli on the physicochemical properties of synovial fluid. Analyze the dynamic process by which mechanical stimuli regulate secretory and metabolic activities through tissue cells, thereby altering the physicochemical properties of cytokines and proteins. RESULTS: Appropriate mechanical stimuli activate mechanical signals in chondrocytes, macrophages, and synovial cells, thereby influencing cellular metabolic activities, including inhibiting the release of pro-inflammatory factors and promoting the secretion of anti-inflammatory factors, and regulating the expression of matrix and inflammation-related proteins such as cartilage oligomeric matrix protein, peptidoglycan recognition protein 4, and matrix metalloproteinases. CONCLUSION Mechanical stimuli act on tissue cells, indirectly reshaping the synovial fluid microenvironment through metabolic activities, thereby regulating the pathological process of osteoarthritis.
Humans ; Osteoarthritis/physiopathology* ; Synovial Fluid/chemistry* ; Chondrocytes/metabolism* ; Cytokines/metabolism* ; Macrophages/metabolism* ; Stress, Mechanical ; Cartilage Oligomeric Matrix Protein/metabolism* ; Matrix Metalloproteinases/metabolism* ; Synovial Membrane/cytology*

OBJECTIVE: To reveal the molecular basis of knee osteoarthritis (KOA) with Yang deficiency and blood stasis syndrome by analyzing the gene expression profiles in synovial fluid and blood of KOA patients with this syndrome. METHODS: A total of 80 KOA patients were recruited from October 2022 to June 2024, including 40 cases in the non-Yang deficiency and blood stasis group (27 males and 13 females), with an average age of (61.75±3.45) years old;and 40 cases in the Yang deficiency and blood stasis group (22 males and 18 females), with an average age of (62.00±2.76) years old. The levels of body mass index (BMI), high-density lipoprotein (HDL), low-density lipoprotein (LDL), fibrinogen, total cholesterol, and D-dimer were recorded and summarized. Blood and synovial fluid samples from patients were collected for gene expression profile microarray sequencing, and then PCR and immunohistochemistry were used for clinical verification on the patients' synovial fluid and cartilage samples. RESULTS: Logistic regression analysis showed that compared with KOA patients with non-Yang deficiency and blood stasis syndrome, those with Yang deficiency and blood stasis syndrome had increased BMI, LDL, fibrinogen, total cholesterol, and D-dimer, and decreased HDL, with a clear correlation between the two groups. There were 562 differential genes in the blood, among which 322 were up-regulated and 240 were down-regulated;755 differential genes were found in the synovial fluid, with 350 up-regulated and 405 down-regulated. KEGG signaling pathway analysis of synovial fluid revealed changes in lipid metabolism-related pathways, including cholesterol metabolism, fatty acid metabolism, and PPARG signaling pathway. Analysis of the involved differential genes identified 6 genes in synovial fluid that were closely related to lipid metabolism, namely LRP1, LPL, ACOT6, TM6SF2, DGKK, and PPARG. Subsequently, PCR and immunohistochemical verification were performed using synovial fluid and cartilage samples, and the results were consistent with those of microarray sequencing. CONCLUSION This study explores the clinical and genomic correlation between traditional Chinese medicine syndromes and knee osteoarthritis from the perspective of lipid metabolism, and proves that abnormal lipid metabolism is closely related to KOA with Yang deficiency and blood stasis syndrome from both clinical and basic aspects.
Humans ; Male ; Female ; Middle Aged ; Synovial Fluid/metabolism* ; Osteoarthritis, Knee/metabolism* ; Yang Deficiency/complications* ; Aged

Objective Based on 25 indicators including immune factors, cell count classification, and smear results of the knee joint fluid, machine learning models were established to distinguish between osteoarthritis (OA) and rheumatoid arthritis (RA). Methods 100 OA and 40 RA patients scheduled for total knee arthroplasty were enrolled respectively. Each patient's knee joint fluid was collected preoperatively. Nucleated cells were counted and classified. The expression levels of immune factors, including tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, IL-8, IL-15, matrix metalloproteinase 3 (MMP3), MMP9, MMP13, rheumatoid factor (RF), serum amyloid A (SAA), C-reactive protein (CRP), and others were measured. Smears and microscopic classification of all the immune factors were performed. Independent influencing factors for OA or RA were identified using univariate binary logistic regression, Lasso regression, and multivariate binary logistic regression. Based on the independent influencing factors, three machine learning models were constructed which are logistic regression, random forest, and support vector machine. Receiver operating characteristic curve (ROC), calibration curve and decision curve analysis (DCA) were used to evaluate and compare the models. Results A total of 5 indicators in the knee joint fluid were screened out to distinguish OA and RA, which were IL-1β(odds ratio(OR)=10.512, 95× confidence interval (95×CI) was 1.048-105.42, P=0.045), IL-6 (OR=1.007, 95×CI was 1.001-1.014, P=0.022), MMP9 (OR=3.202, 95×CI was 1.235-8.305, P=0.017), MMP13 (OR=1.002, 95× CI was 1-1.004, P=0.049), and RF (OR=1.091, 95×CI was 1.01-1.179, P=0.026). According to the results of ROC, calibration curve and DCA, the accuracy (0.979), sensitivity (0.98) and area under the curve (AUC, 0.996, 95×CI was 0.991-1) of the random forest model were the highest. It has good validity and feasibility, and its distinguishing ability is better than the other two models. Conclusion The machine learning model based on immune factors in the knee joint fluid holds significant value in distinguishing OA and RA. It provides an important reference for the clinical early differential diagnosis, prevention and treatment of OA and RA.
Humans ; Arthritis, Rheumatoid/metabolism* ; Machine Learning ; Male ; Female ; Middle Aged ; Aged ; Synovial Fluid/immunology* ; Osteoarthritis, Knee/metabolism* ; Knee Joint/metabolism* ; ROC Curve ; Diagnosis, Differential

Humans ; Synovial Fluid ; MicroRNAs/genetics* ; Exosomes/genetics* ; Osteoarthritis/genetics* ; Synovial Membrane

OBJECTIVE: To investigate the relationship between trace elements in synovial fluid and cartilage and severity of knee osteoarthritis (KOA). METHODS: Patients with KOA who underwent knee arthrocentesis or total knee arthroplasty (TKA) were recruited based on inclusion criteria between June 2021 and December 2021. Synovial fluid samples were obtained during knee arthrocentesis and TKA, and participants were divided into the mild group (grading Ⅰ/Ⅱ) and the severe group (grading Ⅲ/Ⅳ) according to the Kellgren-Lawrence grading (K-L grading). Cartilage samples with different degrees of wear were collected during the TKA from the same patient and were divided into mild wear (0-1 point) and severe wear (2-4 points) groups based on the Pelletier score. The contents of copper (Cu), zinc (Zn), and manganese (Mn) in synovial fluid and cartilage were evaluated by inductively coupled plasma mass spectrometry, and the differences between groups were compared. RESULTS: A total of 33 synovial fluid samples were collected, including 19 specimens from 14 patients who underwent knee arthrocentesis of mild group, with 5 bilateral sides knee arthrocentesis in them, and 14 specimens from 14 TKA patients of severe group. The patients were significantly younger in the mild group than in the severe group ( P<0.05), but there was no significant difference in gender or body mass index between the two groups ( P>0.05). Nineteen pairs of cartilage samples with mild and severe wear were collected from severe KOA patients (K-L grading Ⅲ and Ⅳ), including 9 males and 10 females, with an average age of 70.4 years (range, 58-80 years). The body mass index ranged from 21.2 to 30.7 kg/m ², with an average of 25.6 kg/m ². The content of Zn in synovial fluid and cartilage from KOA patients was the highest, followed by Cu, and Mn was the lowest. The Cu content in synovial fluid was significantly higher in the severe group than in the mild group ( P<0.05), and in the severe wear group than in the mild wear group ( P<0.05). There was no significant difference in Zn and Mn content between the two groups ( P>0.05). CONCLUSION The Cu content increases with the severity of cartilage wear in patients with KOA.
Male ; Female ; Humans ; Aged ; Osteoarthritis, Knee/surgery* ; Synovial Fluid ; Trace Elements ; Knee Joint/surgery* ; Cartilage, Articular ; Zinc

OBJECTIVE: To examine the expression of chemokine receptor CCR10 on monocytes/macrophages in the joints of patients with rheumatoid arthritis (RA), and to investigate the role of chemokine CCL28 and its receptor CCR10 in the migration of RA monocytes and its mechanism. METHODS: The expression of CCR10 in synovial tissues from 8 RA patients, 4 osteoarthritis (OA) patients, and 4 normal controls was analyzed by immunohistochemistry, and cell staining was scored on a 0-5 scales. Flow cytometry was used to measure the percentage of CCR10 positive cells in CD14⁺ monocytes from peripheral blood of 26 RA patients and 20 healthy controls, as well as from synovial fluid of 15 RA patients. The chemotactic migration of monocytes from RA patients and healthy controls in response to CCL28 was evaluated using an in vitro Transwell system. Western blotting was conducted to assess phosphorylation of the extracellular signal-regulated kinase (ERK) and protein kinase B (Akt) pathways in RA monocytes upon CCL28 treatment. RESULTS: CCR10 was predominantly expressed in RA synovial lining cells and sublining macrophages, endothelial cells, and lymphocytes. CCR10 expression was significantly increased on lining cells and sublining macrophages in RA synovial tissue compared with OA and normal synovial tissue (both P < 0.01). The patients with RA had markedly elevated expression of CCR10 on peripheral blood CD14⁺ monocytes compared with the healthy controls [(15.6±3.0)% vs. (7.7±3.8)%, P < 0.01]. CCR10 expression on synovial fluid monocytes from the RA patients was (32.0±15.0)%, which was significantly higher than that on RA peripheral blood monocytes (P < 0.01). In vitro, CCL28 caused significant migration of CD14⁺ monocytes from peripheral blood of the RA patients and the healthy controls at concentrations ranging from 10-100 μg/L (all P < 0.01). The presence of neutralizing antibody to CCR10 greatly suppressed CCL28-driven chemotaxis of RA monocytes (P < 0.01). Stimulation of RA monocytes with CCL28 induced a remarkable increase in phosphorylation of ERK and Akt (both P < 0.05). ERK inhibitor (U0126) and phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002) strongly reduced the migration of RA monocytes in response to CCL28 (both P < 0.01). CONCLUSION RA patients had increased CCR10 expression on peripheral blood, synovial fluid, and synovial tissue monocytes/macrophages. CCL28 ligation to CCR10 promoted RA monocyte migration through activation of the ERK and PI3K/Akt signaling pathways. The CCL28-CCR10 pathway could participate in monocyte recruitment into RA joints, thereby contributing to synovial inflammation and bone destruction.
Humans ; Monocytes/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Endothelial Cells/metabolism* ; Phosphatidylinositol 3-Kinases/metabolism* ; Arthritis, Rheumatoid ; Synovial Membrane ; Chemokines, CC/metabolism* ; Synovial Fluid ; Osteoarthritis ; Receptors, CCR10/metabolism*

OBJECTIVE: To observe the effect of Miao medicinal acupuncture therapy on transient receptor potential vanilloid (TRPV) channel in knee joint synovial tissue of the rabbits with knee osteoarthritis (KOA) model and to explore the mechanism of Miao medicinal acupuncture therapy in treatment of KOA. METHODS: Of 34 New Zealand male rabbits, 6 rabbits were selected randomly as the normal group. KOA model was established in the rest rabbits by injecting a mixture of papain and L-cysteine in right knee joints. The 24 successfully modeled rabbits were randomized into a model group, a Miao medicinal acupuncture therapy group, a dermal needle group and a smearing group, 6 rabbits in each one. In the Miao medicinal acupuncture therapy group, Miao medicinal acupuncture therapy was adopted, in which, the roller type of dermal needle was used on the surface of right knee joint [a rectangle shape formed by "Xuehai" (SP 10), "Liangqiu" (ST 34), "Yanglingquan" (GB 34) and "Yinlingquan" (SP 9)], rolling in a " shape, on which, Miao medicinal solution was smeared in advance. In the dermal needle group, the rolling stimulation was exerted on the right the right knee joint surface with the roller type of dermal needle. In the smearing group, Miao medicinal solution was smeared on the right knee joint surface. The intervention was given once every two days, 3 times weekly and the intervention was exerted consecutively for 4 weeks. Successively, on day 1, 21, 28, 35, 42 and 49 of experiment, paw withdrawal threshold (von Frey threshold) after mechanical stimulation was detected in the rabbits. HE staining was adopted to observe the histomorphological changes of the right knee joint cartilage in the rabbits. ELISA was used to determine the contents of interleukin-1 (IL-1β) and tumor necrosis factor-α (TNF-α) in the right knee synovial fluid. Western blot method and real-time PCR were used to determine the relative expressions of protein and mRNA of TRPV1 and TRPV4 in knee synovial tissue of the rabbits. RESULTS: Compared with the normal group, on day 49 of experiment, von Frey threshold was reduced significantly in the rabbits of the model group ( CONCLUSION Miao medicinal acupuncture therapy plays a role in treatment of KOA probably through inhibiting the expressions of IL-1β and TNF-α of knee synovial fluid and down-regulating the expressions of protein and mRNA of TRPV1 and TRPV4 in knee synovial tissue.
Acupuncture Therapy ; Animals ; Knee Joint ; Male ; Osteoarthritis, Knee/therapy* ; Rabbits ; Synovial Fluid ; Transient Receptor Potential Channels

OBJECTIVE: To observe the therapeutic effects of different waves of electroacupuncture (EA) on knee osteoarthritis (KOA), and to explore the mechanism of different waves of EA on promoting cartilage repair. METHODS: Ninety- seven patients with KOA were randomly divided into a dilatational wave group (32 cases, 2 cases dropped off), a continuous wave group (32 cases, 2 cases dropped off) and a discontinuous wave group (33 cases, 3 cases dropped off). The same acupoints of Xuehai (SP 10), Liangqiu (ST 34), Dubi (ST 35) and Neixiyan (EX-LE 4) were selected in the three groups. The dilatational wave (frequency of 2 Hz/10 Hz) was used in the dilatational wave group, the continuous wave (frequency of 10 Hz) was used in the continuous wave group, and the discontinuous wave (frequency of 10 Hz) was used in the discontinuous wave group. All the needles were retained for 30 min. All the treatment was given 3 times a week (on Monday, Wednesday and Friday) for 4 weeks. Lysholm knees scoring scale (LKSS) was used to evaluate the knee joint function before and after treatment, and the content of transforming growth factor-β1 (TGF-β1) in the joint effusion before and after treatment was determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Compared before treatment, the total score and each score of LKSS were increased after treatment in the three groups (all <0.05). The improvements of total score, pain score, instability score, swelling score of LKSS in the continuous wave group and the dilatational wave group were superior to those in the discontinuous wave group (all <0.05). The content of TGF-β1 in the joint effusion in each group was increased after treatment (<0.05), and the improvement in dilatational wave group was superior to thoes in the continuous wave group and the discontinuous wave group (all <0.05). CONCLUSION The three different waves of EA could all improve the clinical symptoms of KOA, which may promote cartilage repair by increasing TGF-β1 content. The dilatational wave had the best overall effect, which can be used as a clinical optimal treatment.
Acupuncture Points ; Electroacupuncture ; Humans ; Knee Joint ; Osteoarthritis, Knee ; therapy ; Synovial Fluid ; chemistry ; Transforming Growth Factor beta1 ; analysis ; Treatment Outcome

PURPOSE: Sodium chloride (NaCl) has been proposed as a driving factor in autoimmune diseases through the induction of pathogenic CD4+ T helper cells that produce interleukin-17 (Th17 cells). This study investigated the effects of NaCl on inflammatory arthritis in mice and humans. MATERIALS AND METHODS: Collagen-induced arthritis (CIA) mice were fed a normal or high-salt diet ad libitum, and clinical and histologic features of arthritis were evaluated. The proportion of Th17 cells in the spleens of CIA mice fed a normal or high-salt diet was evaluated by flow cytometry, and the expression of IL-17 in joints and intestines was determined by immunohistochemical staining. We also analyzed the effect of NaCl on Th17 differentiation from peripheral blood monocytes of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and evaluated the contents of sodium and IL-17 in the synovial fluid of RA and OA patients. RESULTS: NaCl increased murine and human Th17 cell differentiation in a dose-dependent manner. Clinical and histological arthritis was more severe in the high-salt-fed CIA mice, compared to control CIA mice. The proportion of Th17 cells among splenocytes was higher in CIA mice fed a high-salt diet. Expression of synovial and intestinal IL-17 was also higher in high-salt-fed CIA mice. Comparison of synovial fluid between RA patients and OA patients revealed that Na+ and IL-17 were more abundant in RA synovial fluid. CONCLUSION: This study suggests that NaCl can aggravate arthritis by affecting Th17 differentiation. Accordingly, limiting salt intake may be helpful for treating inflammatory arthritis, such as RA.
Animals ; Arthritis* ; Arthritis, Experimental ; Arthritis, Rheumatoid ; Autoimmune Diseases ; Diet ; Flow Cytometry ; Humans ; Interleukin-17 ; Intestines ; Joints ; Mice ; Monocytes ; Osteoarthritis ; Sodium Chloride* ; Sodium* ; Spleen ; Synovial Fluid ; T-Lymphocytes, Helper-Inducer ; Th17 Cells

Calcium pyrophosphate (CPP) crystals can present as acute inflammatory arthritis which is known as an acute CPP crystal arthritis. Although monocytes/macrophages have been shown to play a role in the initiation of crystal-mediated inflammatory responses, differences in their phenotypes between acute CPP crystal arthritis and acute gouty arthritis have not yet been investigated. We examined the immunological characteristics of synovial monocytes/macrophages in patients with acute CPP crystal and acute gouty arthritis. CD14⁺CD3⁻CD19⁻CD56⁻ cell frequencies in synovial fluid mononuclear cells (SFMCs) were measured. Expression of pro- and anti-inflammatory cytokines and markers was determined. The SFMCs were dominated by a population of monocytes/macrophages in acute CPP crystal arthritis similar to that in acute gout. Synovial monocytes/macrophages showed the phenotypes of infiltrated monocytes as shown by expression of CD88, C-C chemokine receptor type 2, myeloid-related protein (MRP)8 and MRP14 but not proto-oncogene tyrosine-protein kinase MER. Comparatively, the CD14⁺ cells from patients with acute CPP crystal arthritis had similar high levels of IL-1β and TNF-α production but significantly lower expression of IL-10 and M2 marker (CD163). The monocytes/macrophages had the capacity to produce IL-8 in response to CPP crystals. Proinflammatory features were more dominant in monocytes/macrophages during acute CPP crystal arthritis than those during acute gouty arthritis.
Arthritis ; Arthritis, Gouty ; Calcium Pyrophosphate ; Calcium ; Cytokines ; Gout ; Humans ; Interleukin-10 ; Interleukin-8 ; Macrophages ; Monocytes ; Phenotype ; Phosphotransferases ; Proto-Oncogenes ; Synovial Fluid