Knee Osteoarthritis Rats Research Articles

MiR-20 promotes cartilage repair in knee osteoarthritis rats via BMP2/Smad1 signaling pathway.

To explore the effect of micro ribonucleic acid (miR)-20b on knee osteoarthritis rats by regulating the bone morphogenetic protein 2 (BMP2)/Smad1 pathway, a total of 36 SD rats were randomly divided into normal group (n=12), model group (n=12) and miR-20b mimics group (n=12). The rats in normal group were fed normally, while those in model group and miR-20b mimics group were used to establish knee osteoarthritis models. After modeling, model group was not given any intervention, but miR-20b mimics group received intra-articular injection of miR-20b mimics once a day for 2 weeks. Basso, Beattie and Bresnahan (BBB) limb motor function scoring was performed at 1, 5, 7 and 14 days after the modeling, and samples were obtained after 2 weeks of intervention. Next, hematoxylin and eosin (H&E) staining was applied to observe tissue morphology, Markin's scoring was utilized to evaluate articular cartilage degeneration, and immunohistochemistry was employed to detect the expressions of BMP2 and Smad1. Thereafter, the expression of miR-20b was detected via qPCR, the content of cartilage oligomeric matrix protein (COMP) and C-telopeptide of type II collagen (CTX-II) was measured via enzyme-linked immunosorbent assay (ELISA), and the expressions of BMP2 and Smad1 proteins were examined via Western blotting (WB). BBB limb motor function scoring showed that compared with that in normal group, the BBB limb motor function score of rats in the other two groups was reduced (P<0.05). In comparison with that in model group, the BBB limb motor function score in miR-20b mimics group was increased from the 7th day after intervention (P<0.05). In addition, H&E staining results manifested that the articular surface in normal group was smooth and flat, with normal morphology, clear structure and no obvious damage. In model group, the articular surface was not smooth and uneven, and more articular cartilage fractures, morphological disorders and structural damages could be observed. Moreover, the articular surface in miR-20b mimics group was slightly damaged and smoother, and its morphology and structure were markedly improved in contrast to that in model group. The Markin's score in normal group was lower than that in model group and miR-20b mimics group (P<0.05), and it was overtly decreased in miR-20b mimics group in comparison with that in model group (P<0.05). Next, immunohistochemistry demonstrated that compared with normal group, the other two groups had lowered positive expressions of BMP2 and Smad1 (P<0.05). In comparison with model group, miR-20b mimics group exhibited notably raised positive expressions of BMP2 and Smad1 (P<0.05). Then it was found from qPCR results that the expression level of miR-20b in the other two groups was overtly reduced compared with that in normal group (P<0.05), and it was prominently elevated in miR-20b mimics group in contrast to that in model group (P<0.05). Besides, ELISA illustrated that the content of COMP and CTX-II in the cartilage tissues in the other two groups was evidently reduced compared with that in normal group (P<0.05), and it was increased prominently in miR-20b mimics group compared with that in model group (P<0.05). Finally, it was revealed by WB examination that the relative expression levels of BMP2 and Smad1 proteins in the other two groups markedly declined in comparison with those in normal group (P<0.05), and they were elevated in contrast to those in model group (P<0.05). MiR-20b can promote cartilage repair and improve articular function in knee osteoarthritis rats by up-regulating the BMP2/Smad1 signaling pathway.

Analysis of Molecular Changes and Features in Rat Knee Osteoarthritis Cartilage: Progress From Cellular Changes to Structural Damage

Objective Although knee osteoarthritis (KOA) is a common disease, there is a lack of specific prevention and early treatment methods. Hence, this study aimed to examine the molecular changes occurring at different stages of KOA to elucidate the dynamic nature of the disease. Design Using a low-force compression model and analyzing RNA sequencing data, we identified molecular changes in the transcriptome of knee joint cartilage, including gene expression and molecular pathways, between the cellular changes and structural damage stages of KOA progression. In addition, we validated hub genes using an external dataset. Results Gene set enrichment analysis (GSEA) identified the following pathways to be associated with KOA: “B-cell receptor signaling pathway,” “cytokine-cytokine receptor interaction,” and “hematopoietic cell lineage.” Expression analysis revealed 585 differentially expressed genes, with 579 downregulated and 6 upregulated genes. Enrichment and clustering analyses revealed that the main molecular clusters were involved in cell cycle regulation and immune responses. Furthermore, the hub genes Csf1r, Cxcr4, Cxcl12, and Ptprc were related to immune responses. Conclusions Our study provides insights into the dynamic nature of early-stage KOA and offers valuable information to support the development of effective intervention strategies to prevent the irreversible damage associated with KOA, thereby addressing a major clinical challenge.

Exploring rutinoside's impact on inflammation in a rat knee OA model induced by monosodium iodoacetate (MIA)

Link of Video Abstract: https://youtu.be/Dl8sYvPfd6o Introduction: Osteoarthritis (OA) is a common joint disease characterized by persistent inflammation and cartilage breakdown. Monosodium iodoacetate (MIA) is often used to generate OA in rats. This study aims to explore the anti-inflammatory benefits of rutinoside, a natural flavonoid glycoside, in rats with MIA-induced knee OA. Methods: The male Wistar rats were divided into five groups (n = 6) and randomly allocated to one of five treatments: control, OA, rutinoside, glucosamine sulfate, and sodium diclofenac-treated group. 3 mg of monosodium iodoacetate (MIA) was injected intra-articularly into the knee joints of rats to induce osteoarthritis. Rutinoside, glucosamine sulfate, and sodium diclofenac were given daily for four weeks. Body weight, joint swelling, knee bend score, interleukin-1 (IL-1) levels, interleukin-8 (IL-8) levels, and C-terminal telopeptide type II collagen (CTX-II) levels were all assessed. Result: Rutinoside significantly decreased body weight loss, joint edema, and knee bend test scores compared to the untreated OA group. Furthermore, rutinoside was equally effective as glucosamine sulfate and sodium diclofenac in these parameters. The rutinoside, glucosamine sulfate, and sodium diclofenac groups had significantly lower IL-1, IL-8, and CTX-II levels than the untreated OA group. Conclusion: Rutinoside reduced inflammatory responses, lowered joint edema, and improved knee bend test scores in a rat model of MIA-induced osteoarthritis. Its efficacy in preventing illness was comparable to glucosamine sulfate and sodium diclofenac. More study is needed to better understand rutinoside's underlying mechanisms and long-term consequences for treating osteoarthritis.

The Potential Benefic Effect of Nicotinamide Riboside in Treating a Murine Model of Monoiodoacetate-Induced Knee Osteoarthritis.

Knee osteoarthritis (KOA), one of the most common orthopedic disorders concerning the adult population worldwide, is a condition characterized by progressive destruction of the articular cartilage and the presence of an inflammatory process. The aim of our study was to assess whether nicotinamide riboside (NR), a popular anti-aging supplement, can reduce the rate of cartilage destruction and alleviate the inflammatory response compared to the commonly prescribed collagen supplement in a murine monoiodoacetate (MIA)-induced KOA model. Twenty Wistar rats were randomly assigned to 4 groups: sham (S), MIA and NR, MIA and hydrolyzed collagen (HC), and MIA. At the end of the experiment, the right knees and blood samples were collected for histological assessment and biochemical evaluation of nitric oxide, malondialdehyde, total antioxidant capacity, reduced glutathione, glutathione peroxidase, superoxide dismutase, catalase, myeloperoxidase, and tumoral necrosis factor-alpha (TNF-α). The study determined that the treatment with NR in a similar dose with HC decreased blood/serum levels of oxidative stress biomarkers and the histological lesions in almost the same manner. The present findings suggest that NR may exhibit chondroprotective and anti-inflammatory effects in MIA-induced KOA in rats.

Comparison of the effect of moxibustion at "Zusanli" (ST36) on the polarization of synovial macrophages of knee joints in rats with knee osteoarthritis and rheumatoid arthritis.

To observe the similarities and differences of effects of moxibustion at "Zusanli" (ST36) on target tissues and macrophages polarization in knee osteoarthritis (KOA) and rheumatoid arthritis (RA) rats, and to summarize its efficacy and characteristics. Thirty rats were equally and randomly divided into control, KOA, RA, KOA+Moxi and RA+Moxi groups. The KOA model and RA model were induced by injection of sodium monoiodoacetate or Freund's complete adjuvant into the rats' knee joints, respectively. Rats of the KOA+Moxi and RA+Moxi groups received moxibustion stimulation at bilateral ST36 for 30 min, once a day for 21 days, beginning from the 7th day on after modeling. The contents of serum interleukin(IL)-1β and IL-10 were detected by ELISA. Histopathological changes (Markin score of the knee cartilage and synovial pathology score) of the knee joints were observed after HE staining. The polarization state of M1 and M2 macrophages in the synovial tissue of the knee joints was assessed by detecting the expression of CD86 and CD206 after immunofluorescence staining. Compared with the control group, the content of serum IL-1β, synovial pathology score, and synovial CD86 expression were significantly increased (P<0.01, P<0.05), while the content of serum IL-10 and synovial CD206 expression markedly decreased (P<0.01) in both KOA and RA groups；the Markin score was increased (P<0.01) in the KOA group. In comparison with the KOA group, the Markin score was obviously decreased (P<0.01), while the content of serum IL-10 and CD206 expression were apparently increased (P<0.01) in the KOA+Moxi group. No significant changes were found in the content of serum IL-1β, synovial pathology score and CD86 expression in the KOA+Moxi group relevant to the KOA group. In comparison with the RA group, the content of serum IL-1β, synovial pathology score, and CD86 expression were considerably decreased (P<0.01) in the RA+Moxi group. No marked differences were found in the serum IL-10 level, Markin score, and CD206 expression between RA+Moxi and RA model groups. The increased Markin score was significantly higher in the KOA group than in the RA group (P<0.01), but the increased synovial pathology score was significantly lower in the KOA group than in the RA group (P<0.01). Correspondingly, the effect of moxibustion at ST36 was significantly better in RA model than in KOA model in reducing serum IL-1β (P<0.05). Moxibustion at ST36 can effectively reduce cartilage injury of knee joint in rats with KOA and reduce synovial injury in rats with RA, which may be related with its effects in lowering IL-1β level in RA model by inhibiting the polarization of M1 macrophages, and up-regulating level of IL-10 in KOA model by promoting the polarization of M2 macrophages. However, the relevant mechanism needs to be further studied.

Potential of thermoresponsive hydrogel as an alternative therapy for rat knee osteoarthritis.

Osteoarthritis is a degenerative condition that is highly prevalent and primarily affects the joints. The knee is the most commonly affected site, impacting the lives of over 300 million individuals worldwide. This study presents a potential solution to address the unmet need for a minimally invasive technique in the treatment of osteoarthritis: a biocompatible, injectable, and thermoresponsive hydrogel. In comparison to commercially available products such as lyophilized platelets, dextrose, and triamcinolone, the thermoresponsive hydrogel exhibits significantly superior performance in dynamic behaviors, including print area, stability, and step cycle, when tested on rats with knee osteoarthritis. However, it demonstrates similar treatment efficacy to these products in static behaviors, as observed through histopathological and immunohistochemical analysis. Therefore, the thermoresponsive hydrogel holds promise as an effective alternative therapy for osteoarthritis. Moreover, by blending the hydrogel with drugs, controlled and sustained release can be achieved, thereby facilitating the long-term management of osteoarthritis symptoms.

Development of a Novel Rat Knee Osteoarthritis Model Induced by Medial Meniscus Extrusion.

The medial meniscus extrusion (MME) is associated with increased stress on the knee joint, which leads to cartilage degeneration. To evaluate the etiology of knee osteoarthritis, it is extremely important to create animal models of the disease that more closely resemble actual clinical conditions in terms of symptomatology, molecular biology, and histology. This study aimed to create a clinically relevant model of MME in rats. Behavioral, molecular biological, and histological changes in the newly developed rat MME model were compared with those in sham and medial meniscus transection and medial collateral ligament transection (MMT) models to examine the characteristics of this model. In the MME rat model, behavioral evaluation shows abnormalities in gait compared with the other 2 groups, and molecular biological evaluation of the infrapatellar synovia of rats shows that gene expression of inflammatory cytokines, matrix-degrading enzymes, and pain-related nerve growth factor was increased compared with the sham group. Furthermore, histological evaluation reveals that cartilage degeneration was the most severe in the MME group. The newly developed MME model reproduced the characteristic pathology of MME in clinical practice, such as severe pain, inflammation, and rapid progression of osteoarthritis. The MME model, which might more closely mimic human knee osteoarthritis (OA), could be a useful model for elucidating the pathophysiology and considering therapeutic management for knee OA.

Bixa orellana ethyl acetate fraction and its isolated compound ellagic acid attenuate the progression of MIA-induced osteoarthritis in rat knees

Osteoarthritis (OA) is a pathology that is characterized by progressive erosion of articular cartilage. In this context, medicinal plants have become relevant tools regarding their potential role in the prevention and treatment of OA, being safe and effective. The aim of this work was investigate the therapeutic efficacy of the ethyl acetate fraction of Bixa orellana leaves (BoEA) and ellagic acid (ElAc) for the therapeutic treatment of OA induced by monosodium iodoacetate (MIA) in rats. The plant material was extracted via maceration with 70 % hydroalcoholic solvent (BoHE). The ethyl acetate (BoEA) fraction was by solvents in increasing order of polarity. The ElAc was identified and isolated in BoEA using high performance liquid chromatography (HPLC-DAD) and analytical curve. The OA was induced using MIA in the right knee at the knee joint. Doses of BoEA and ElAc were administered daily (every 24 h, orally) at concentrations of 50, 100 and 50 mg/kg, respectively, for 28 days after induced OA. We evaluated the animals through clinical and radiological examinations every 7 days and, on the 29th day, the animals were euthanized, the joints being removed for histopathological analysis and the serum for cytokine analysis. BoEA and ElAc compounds reduced inflammation and nociception in OA and were as effective as indomethacin in clinical parameters of joint discomfort and allodynia in rats, in addition to showing improvements in radiological and histopathological images, acting on the progress of cartilage deterioration, proving properties related to anti-inflammatory and analgesic processes, being important allies for new therapeutic interventions for the treatment of OA.

Non-weight-bearing exercise attenuates papain-induced knee osteoarthritis in rats via the TLR4/MyD88/NF-κB signaling pathway

Background and AimKnee osteoarthritis (KOA) is characterized by joint wear and degeneration. Unfortunately, the medical community currently lacks effective treatment options for this disease. Suspension exercise therapy is considered an effective form of non-weight-bearing exercise for treating KOA. However, its mechanism of intervention in KOA is unclear. Therefore, this study aimed to evaluate the protective effects of non-weight-bearing exercise on rats with KOA and attempted to explore the underlying mechanisms.MethodsIn this study, a papain-induced KOA model was constructed, and the pathological changes in cartilage tissue were observed by hematoxylin and eosin (H&E) staining and scored according to the Mankin scoring principle. The serum levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were detected by enzyme-linked immunosorbent assay. Reverse transcription–quantitative polymerase chain reaction and Western blotting were used to detect the expression of mRNA and proteins in the TLR4/MyD88/NF-κB signaling pathway.ResultsH&E staining and Mankin score data confirmed that non-weight-bearing exercise significantly improved articular cartilage degradation compared with that in the model group. Further, we observed that non-weight-bearing exercise differentially reduced serum levels of IL-1β, IL-6, and TNF-α. Mechanistically, non-weight-bearing exercise downregulated gene and protein expression of TLR4, MyD88, and NF-κB in cartilage tissue.ConclusionNon-weight-bearing exercise resulted in the progression of KOA by modulating the TLR4/MyD88/NF-κB signaling pathway and decreasing the levels of the inflammatory cytokines IL-1β, IL-6, and TNF-α to slow down the degeneration of articular cartilage.

Cangxi Tongbi Capsules promote chondrocyte autophagy by regulating circRNA＿0008365/miR-1271/p38 MAPK pathway to inhibit development of knee osteoarthritis

To investigate the mechanism by which Cangxi Tongbi Capsules promote chondrocyte autophagy to inhibit knee osteoarthritis(KOA) progression by regulating the circRNA＿0008365/miR-1271/p38 mitogen-activated protein kinase(MAPK) pathway. The cell and animal models of KOA were established and intervened with Cangxi Tongbi Capsules, si-circRNA＿0008365, si-NC, and Cangxi Tongbi Capsules combined with si-circRNA＿0008365. Flow cytometry and transmission electron microscopy were employed to determine the level of apoptosis and observe autophagosomes, respectively. Western blot was employed to reveal the changes in the protein levels of microtubule-associated protein light chain 3(LC3)Ⅱ/Ⅰ, Beclin-1, selective autophagy junction protein p62/sequestosome 1, collagen Ⅱ, a disintegrin and metalloproteinase with thrombospondin motifs 5(ADAMTS-5), and p38 MAPK. The mRNA levels of circRNA＿0008365, miR-1271, collagen Ⅱ, and ADAMTS-5 were determined by qRT-PCR. Hematoxylin-eosin staining was employed to reveal the pathological changes of the cartilage tissue of the knee, and enzyme-linked immunosorbent assay to measure the levels of interleukin-1β(IL-1β) and tumor necrosis factor-alpha(TNF-α). The chondrocytes treated with IL-1β showed down-regulated expression of circRNA＿0008365, up-regulated expression of miR-1271 and p38 MAPK, lowered autophagy level, increased apoptosis rate, and accelerated catabolism of extracellular matrix. The intervention with Cangxi Tongbi Capsules up-regulated the expression of circRNA＿0008365, down-regulated the expression of miR-1271 and p38 MAPK, increased the autophagy level, decreased the apoptosis rate, and weakened the catabolism of extracellular matrix. However, the effect of Cangxi Tongbi Capsules was suppressed after interfering with circRNA＿0008365. The in vivo experiments showed that Cangxi Tongbi Capsules dose-dependently inhibited the p38 MAPK pathway, enhanced chondrocyte autophagy, and mitigated articular cartilage damage and inflammatory response, thereby inhibiting the progression of KOA in rats. This study indicated that Cangxi Tongbi Capsules promoted chondrocyte autophagy by regulating the circRNA＿0008365/miR-1271/p38 MAPK pathway to inhibit the development of KOA.

Melatonin enhances the ability of M2 macrophages to secrete IL10 by inhibiting Erk5 signaling pathway

BackgroundMelatonin plays a role in repairing damaged cartilage and regulating immune cells. The anti-inflammatory effect of Melatonin involves multiple pathways and molecular activation, which directly or indirectly inhibits inflammatory reaction. M2 macrophages have the ability to anti-inflammatory response and repair damaged tissues, secrete IL10 and IL-4, and participate in tissue repair and remodeling. Erk5 is a recently discovered member of the MAPK family and one of the least studied members. It plays an important role in cell differentiation, proliferation, secretion and other functions. This experiment aims to study how Melatonin affects M2 Macrophage polarization and secretion through ERK5 signaling pathway. MethodsThe RAW 264.7 macrophages were used for cell culture. The cells were cultured according to the pre-experimental results. The effects of Melatonin on M2 macrophages were comprehensively evaluated by CCK8 activity detection, RT-PCR, ELISA, cellular immunofluorescence, and WB.SD mice were selected to evaluate the effect of Melatonin on cartilage damage in rats with knee Osteoarthritis through HE staining, immunohistochemistry and immunofluorescence. ResultsMelatonin cultivates RAW 264.7 macrophages. Without affecting the polarization ratio of M2 Macrophage polarization, Melatonin may reduce Erk5 gene expression, reduce Erk5 and p-Erk5 protein synthesis, and cooperate with BIX 02189 to enhance the secretion function of existing M2 macrophages and increase the secretion of cytokines IL10. Immunohistochemistry of rat knee Osteoarthritis model confirmed that the expression of IL10 was up-regulated and the synthesis of type II collagen was enhanced, but immunofluorescence found that the polarization of M2 Macrophage polarization in subchondral bone was not obvious. ConclusionMelatonin enhances the ability of M2 macrophages to secrete IL10 by inhibiting Erk5 signaling pathway, but has no effect on M2 Macrophage polarization.

Platelet-rich plasma alleviates knee arthritis in rats by inhibiting p65.

Knee osteoarthritis (KOA) is a chronic joint disease characterized by the degeneration of articular cartilage. In this study, we explored the potential therapeutic effects of platelet-rich plasma (PRP) and identified molecular targets for treating KOA. A rat model of KOA was established via the Hulth method and primary knee joint chondrocytes were isolated to evaluate the effects of PRP and shRNA targeting p65 (sh-p65). ELISA was used to detect inflammatory factors, including IL-6, IL-1β, and TNF-α. HE staining, Safranin O/Fast Green staining and Masson staining were performed to evaluate the morphology of articular cartilage, followed by detection of p65, COL2A1, ACAN, MMP13, and ADAMTS5 expression. The proliferation and apoptosis of primary knee chondrocytes were detected by the CCK-8 assay and TUNEL staining, respectively. Treatment with either PRP or sh-p65 decreased IL-6, IL-1β, and TNF-α levels in the peripheral blood of KOA rats and chondrocyte culture supernatants, increased COL2A1 and ACAN levels, and decreased MMP13 and ADAMTS5 expression. Furthermore, administration of PRP or sh-p65 exerted protective effects on articular cartilage, enhanced the vitality of knee joint chondrocytes, and inhibited apoptosis. Collectively, PRP inhibited inflammation, promoted chondrocyte proliferation and cartilage matrix secretion, and induced cartilage regeneration by suppressing p65 expression; these effects allow PRP to alleviate KOA progression. P65-based targeted therapy administered in combination with PRP might be a promising strategy for treating KOA.

Honey improves radiographic features of monosodium iodoacetate-induced stifle (knee) joint osteoarthritis in a rat model

Osteoarthritis (OA) is the most common form of joint disease with over half of all people older than 65 years demonstrating radiographic changes of osteoarthritis in the knees. Honey is known to contain bioactive compounds that exert chondroprotective effects by counteracting the homeostatic dysregulation of the joint. However, its effect on the radiographic features of osteoarthritis has not been proven. This study was carried out to evaluate the effect of honey on radiographic features of monosodium iodoacetate (MIA)- induced knee osteoarthritis in female Wistar rats. Thirty female Wistar rats were randomly divided into five groups of six animals each. Animals in group one were healthy (control) rats, while animals in groups two to five were subjected to experimental osteoarthritis of the right knee joint induced by a single intra-articular injection of 1mg of MIA. The animals in groups two, three, four, and five were treated with normal saline (1ml/kg b. w.), arthocare (glucosamine/chondroitin sulfate 6.67/8.33mg/kg b. w.), low dose honey (250mg/kg b. w.) and high dose honey (1,000mg/kg b. w.) respectively. All treatments were administered orally once daily using an oral cannula for twenty-one days. All animals were subjected to radiographic assessment of the right knee joint before and after induction of OA, and after treatment. High and low-dose honey reversed the loss of joint space; sclerosis of the tibial plateau, medial, and lateral femoral condyles, when compared to the arthocare-treated and untreated groups. In conclusion, honey improved radiographic features of knee osteoarthritis in a rat model induced by monosodium iodoacetate.

Effect of electroacupuncture on the expression of Iba-1 in spinal dorsal horn and hippocampus of chronic pain rats with knee osteoarthritis

To observe the effect of electroacupuncture(EA) on pain-ralated behaviors, morphology of hippocampus, concentrations of inflammatory cytokines and expression of ionized calcium binding adapter molecule 1(Iba-1) in dorsal horn of the spinal cord and the hippocampus, and brain-derived neurotrophic factor (BDNF) in hippocampus of rats with knee osteoarthritis (KOA), so as to explore the mechanism of EA in improving chronic pain of KOA. Forty SD rats were randomly divided into blank group, saline group, model group and EA group, with 10 rats in each group. Monosodium iodoacetate(MIA, 80 mg/mL, 50 μL) was injected into the left knee joint cavity of rats in the model group and EA group to establish the chronic pain model of KOA, while the same volume of normal saline was injected into the left knee joint cavity of rats in the saline group. Rats in the EA group received EA stimulation(2 Hz/100 Hz, 1-2 mA) at left "Yanglingquan"(GB34) and "Neixiyan"(EX-LE4) for 15 min, 14 d after MIA injection. The treatment was given once daily, 5 d as 1 session and 2 sessions of treatment were required. Methanical withdrawl threshold(MWT) and weight-bearing capacity tests on left hind limbs were carried out 1 d before, 7 d，14 d, 20 d and 26 d after MIA injection. At the 27th day, rats were sacrificed and HE staining was used to observe the morphology of hippocampal CA1 area. Concentrations of interleukin(IL)-1β and tumor necrosis factor(TNF)-α in the left L3-L5 spinal dorsal horn and hippocampal CA1 area were detected by ELISA, the expressions of Iba-1 in the spinal dorsal horn and hippo-campal CA1 area were detected by immunofluorescence, and the expression of BDNF in left hippocampal CA1 area was detected by Western blot. The HE staining results of the hippocampal CA1 area showed reduced number of neurons, unclear cell contour and boundary between nucleus and cytoplasm, and nuclear pyknosis in the model group, which was relatively milder in the EA group. Compared with the blank group, MWT and weight-bearing capacity of rats' left hind limbs, and expression of BDNF protein in hippocampal CA1 area were significantly decreased (P<0.01), while the contents of IL-1β and TNF-α, the expression of Iba-1 in spinal dorsal horn and hippocampal CA1 area were significantly increased (P<0.01) in the model group. In comparison with the model group, MWT and weight-bearing capacity of rats' left hind limbs, and protein expression of BDNF in hippocampal CA1 area were significantly increased (P<0.01), while the contents of IL-1β and TNF-α, and the expression of Iba-1 protein in spinal dorsal horn and hippocampal CA1 area were significantly decreased after EA intervention(P<0.01). EA at GB34 and EX-LE4 can alleviate the pain-related behaviors of KOA rats. The mechanism might be related to the inhibition of inflammatory reaction mediated by microglia in spinal dorsal horn and hippocampus, and the up-regulation of BDNF expression in hippocampus.

Effect of moxibustion and scraping on bioactive substances changes of acupoints in knee osteoarthritis rats

To compare the effects of moxibustion and scraping of "Yanglingquan" (GB34) and "Xuehai" (SP10) area on changes of bioactive substances in the region of acupoints in rats with knee osteoarthritis (KOA). SD rats were randomly divided into blank, model, moxibustion, scraping, and moxibustion + scraping (combination) groups, with 8 rats in each group. The KOA model was established by injecting 50 μL 0.9% sodium chloride solution into the right knee cavity. Fourteen days after modeling, GB34 and SP10 on the right limb were stimulated by moxibustion (10 min) or scraping (till regional flush) once every other day for 7 times. The mechanical paw withdrawal threshold (PWT) and thermal withdrawal latency (TWL) were tested by Von Frey and hot stabbing instrument, separately. The pathological changes of the right knee joint were observed by HE staining. The serotonin (5-HT) contents of skin tissues in the region of acupoint GB34 and SP10 were detected by ELISA. The expression levels of substance P (SP) and calcitonin gene-related peptide (CGRP) in GB34 and SP10 region skin tissues were detected by Western blot. Compared with the blank group, the PWT and TWL of the rats in the model group were significantly decreased (P<0.001), while the contents of 5-HT and the expression levels of SP and CGRP in GB34 and SP10 region skin tissues were significantly increased (P<0.001, P<0.01). Following intervention and in comparison the with the model group, the TWL and PWT of rats in the three treatment groups were significantly increased (P<0.01), the content of 5-HT and the expression levels of SP and CGRP in GB34 and SP10 region skin tissues were significantly decreased (P<0.01, P<0.001, P<0.05). Except for the expression levels of CGRP, the above indexes of the combination group were significantly superior to those of the moxibustion and scraping groups (P<0.05, P<0.01). Findings of HE staining showed severe damaged cartilage, few chondrocytes on the surface, with subchondral neovascularization in the model group, which was relatively milder in the moxibustion, scraping, and combination groups. Moxibustion and scraping can relieve knee joint pain in KOA rats, which may be associated with its function in down-regulating the expression levels of SP and CGRP, and the content of 5-HT. The therapeutic effect of moxibustion plus scraping is better than that of moxibustion and scraping alone.

Mechanism of electroacupuncture penetration needling for relieving synovial inflammation of knee osteoarthritis through TLR4/MyD88/NF-κB signal pathway

To observe the effects of electroacupuncture (EA) penetration needling on Toll-like receptors 4/myeloid differentiation factor 88/nuclear factor-kappa B (TLR4/MyD88/NF-κB) signaling pathway in rat synovium and the serum-related inflammatory factors, so as to explore the mechanism of EA penetration needling on synovial inflammation in rats with knee osteoarthritis (KOA). SD male rats were randomly divided into sham-operation group, model group, EA+penetration needling group, and conventional EA group, with 16 rats in each group. The rats model was prepared by anterior cruciate ligment transection and these rats were forced to exercise for 8 weeks after operation. After successful modeling, in the EA+penetration needling group, the needles were inserted at "Dubi" (ST35) "Neixiyan" (EX-LE4), and at "Xuehai"(SP10) "Liangqiu"(ST34) on the right hind limb, towards each other, 5-8 mm in depth, respectively. In the conventional EA group, the needles were inserted at ST35 and EX-LE4 on the right hind limb, obliquely, at 30° angle to the skin, 3-5 mm in depth; and were inserted at SP10 and ST34 on the right hind limb perpendicularly, 3-5 mm in depth. In these two groups, electric stimulation was operated with dense-disperse wave, 2 Hz/10 Hz in frequency and 0.5-1.5 mA in intensity, retained for 20 min in each treatment. The treatment was given once daily, 10 days as 1 course of treatment, and 2 courses were required at the interval of 2 days. After the intervention, the knee joint effusion was observed by musculoskeletal ultrasound; the contents of IL-1β, IL-6 and TNF-α in serum were determined by ELISA; the morphological changes in the synovium were observed after H.E. staining; the positive expression of NF-κB p65 in the synovial membrane was detected by immunohistochemical method; the expression levels of TLR4, MyD88, TRAF-6 and NF-κB p65 proteins in the synovial membrane were determined by Western blot. Compared with the sham-operation group, in the model group, the knee joint effusion was obviously increased, the synovial lining cells were distributed irregularly, the cells were disarranged, the pannus was formed largely, and a great number of the inflammatory cells were infiltrated; the contents of serum IL-1β, IL-6 and TNF-α, the positive expression of NF-κB p65, the protein expression levels of TLR4, MyD88, TRAF-6 and NF-κB p65 in the synovial tissue were increased (P<0.05). Compared with the model group, the knee joint effusion was reduced, the synovial lining cells were proliferated, a small number of the inflammatory cells were infiltrated, and the pannus was formed lightly; the contents of serum IL-1β, IL-6 and TNF-α, the positive expression of NF-κB p65, the protein expression levels of TLR4, MyD88, TRAF-6 and NF-κB p65 in the synovial tissue were lower (P<0.05) in the EA+penetration needling group and the conventional EA group. In the conventional EA group, the knee joint effusion was increased, the synovial lining cells were proliferated, the inflammatory cells were infiltrated largely, and the pannus was formed increasingly; the contents of serum IL-1β, IL-6 and TNF-α, and the protein expression levels of TLR4, MyD88 and NF-κB p65 in the synovial tissue were increased when compared with the EA+penetration needling group (P<0.05). The EA+penetration needling can significantly relieve the synovial inflammatory reaction and the knee joint effusion in KOA rats. The mechanism is probably related to down-regulating the downstream inflammatory cascade through inhibiting the transduction of TLR4/MyD88/NF-κB signaling pathway.

Clinical efficacy of Yiqi Yangxue formula on knee osteoarthritis and unraveling therapeutic mechanism through plasma metabolites in rats.

Objective: To observe the clinical efficacy and safety of Yiqi Yangxue formula (YQYXF) on knee osteoarthritis (KOA), and to explore the underlying therapeutic mechanism of YQYXF through endogenous differential metabolites and their related metabolic pathways. Methods: A total of 61 KOA patients were recruited and divided into the treatment group (YQYXF, 30 cases) and the control group (celecoxib, Cxb, 31 cases). Effects of these two drugs on joint pain, swelling, erythrocyte sedimentation rate (ESR) and c-reactive protein (CRP) were observed, and their safety and adverse reactions were investigated. In animal experiments, 63 SD rats were randomly divided into normal control (NC) group, sham operation (sham) group, model (KOA) group, Cxb group, as well as low-dose (YL), medium-dose (YM), and high-dose groups of YQYXF (YH). The KOA rat model was established using a modified Hulth method. Ultra-high-performance liquid chromatography/Q Exactive HF-X Hybrid Quadrupole-Orbitrap Mass (UHPLC-QE-MS)-based metabolomics technology was used to analyze the changes of metabolites in plasma samples of rats. Comprehensive (VIP) >1 and t-test p < 0.05 conditions were used to screen the disease biomarkers of KOA, and the underlying mechanisms of YQYXF were explored through metabolic pathway enrichment analysis. The related markers of YQYXF were further verified by ELISA (enzyme-linked immunosorbent assay). Results: YQYXF can improve joint pain, swelling, range of motion, joint function, Michel Lequesen index of severity for osteoarthritis (ISOA) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, ESR, and CRP. No apparent adverse reactions were reported. In addition, YQYXF can improve cartilage damage in KOA rats, reverse the abnormal changes of 16 different metabolites, and exert an anti-KOA effect mainly through five metabolic pathways. The levels of reactive oxygen species (ROS) and glutathione (GSH) were significantly decreased after the treatment of YQYXF. Conclusion: YQYXF can significantly improve the clinical symptoms of KOA patients without obvious adverse reactions. It mainly improved KOA through modulating lipid metabolism-related biomarkers, reducing lipid peroxidation and oxidative stress.

Cuminaldehyde Effects in a MIA-Induced Experimental Model Osteoarthritis in Rat Knees.

Osteoarthritis (OA) is a chronic degenerative disease that has a significant global impact. It is associated with aging and characterized by widespread joint destruction. Cuminaldehyde is a biologically active component of essential oils that has shown promise in the treatment of nociceptive and inflammatory diseases. This study investigated the effects of cuminaldehyde on an experimental model of osteoarthritis induced in rat knees. Cuminaldehyde was found to be as effective as indomethacin in reducing pain in all evaluated tests, including forced walking, functional disability of weight distribution on the legs, and spontaneous pain in animals with osteoarthritis. The knees of animals treated with cuminaldehyde had significantly higher radiographic and histopathological scores than those of animals that did not receive the treatment. Cuminaldehyde also modulated the production of pro-inflammatory cytokines. In vitro assays showed that cuminaldehyde preferentially inhibits COX-2 enzyme activity. In silico studies demonstrated that cuminaldehyde has satisfactory energy affinity parameters with opioid receptors and COX-2. These findings suggest that cuminaldehyde's anti-inflammatory activity is multifactorial, acting through multiple pathways. Its nociceptive activity occurs via central and peripheral mechanisms. Cuminaldehyde modulates the immune response of the inflammatory process and may be considered a leading compound for the development of new anti-inflammatory and analgesic drugs.

Electroacupuncture activated local sympathetic noradrenergic signaling to relieve synovitis and referred pain behaviors in knee osteoarthritis rats.

Recent research has focused on the local control of articular inflammation through neuronal stimulation to avoid the systemic side effects of conventional pharmacological therapies. Electroacupuncture (EA) has been proven to be useful for inflammation suppressing and pain reduction in knee osteoarthritis (KOA) patients, yet its mechanism remains unclear. In the present study, the KOA model was established using the intra-articular injection of sodium monoiodoacetate (MIA) (1 mg/50 μL) into the knee cavity. EA was delivered at the ipsilateral ST36-GB34 acupoints. Hind paw weight-bearing and withdrawl thresholds were measured. On day 9, the histology, dep enrichment proteins, cytokines contents, immune cell population of the synovial membrane of the affected limbs were measured using HE staining, Masson staining, DIA quantitative proteomic analysis, flow cytometry, immunofluorescence staining, ELISA, and Western Blot. The ultrastructure of the saphenous nerve of the affected limb was observed using transmission electron microscopy on the 14th day after modeling. The result demonstrated that EA intervention during the midterm phase of the articular inflammation alleviated inflammatory pain behaviors and cartilage damage, but not during the early phase. Mid-term EA suppressed the levels of proinflammatory cytokines TNF-α, IL-1β, and IL-6 in the synovium on day 9 after MIA by elevating the level of sympathetic neurotransmitters Norepinephrine (NE) in the synovium but not systemic NE or systemic adrenaline. Selective blocking of the sympathetic function (6-OHDA) and β2-adrenergic receptor (ICI 118,551) prevented the anti-inflammatory effects of EA. EA-induced increment of the NE in the synovium inhibited the CXCL1-CXCR2 dependent overexpression of IL-6 in the synovial macrophages in a β2-adrenergic receptor (AR)-mediated manner. These results revealed that EA activated sympathetic noradrenergic signaling to control local inflammation in KOA rats and contributed to the development of novel therapeutic neurostimulation strategies for inflammatory diseases.

Metabolomics-based Approach to Analyze the Therapeutic Targets and Metabolites of a Synovitis Ointment for Knee Osteoarthritis

Background: Knee osteoarthritis (KOA) is a clinically common degenerative joint disease that is not fatal but has a high prevalence. Synovitis ointment (HMYG) is a traditional Chinese medicine formula that has been clinically proven to treat KOA; however, its therapeutic targets remain unknown. Objective: This study aimed to identify metabolites and potential targets of synovitis ointment alleviation in rats with KOA using ultra-high-performance liquid-chromatography–mass spectrometry (UHPLC-MS) metabolomics. Methods: The meniscus on each side of the knee was removed to model KOA in rats. The synovitis ointment treatment was provided for 4 weeks. The lateral diameter of the knee was measured once a week, and after 4 weeks, serum was collected to observe changes in the knee through a metabolomic analysis. Results: Synovitis ointment reduced the lateral diameter of the knee joint, relieved knee swelling, and improved knee volume. In total, 28 differential metabolites, which were mainly involved in arginine and proline metabolism and apoptosis, were identified in the Con and HMYG groups. 15-Deoxy-d-12, 14-PGJ2 and fomepizole were found to be the key metabolites after the HMYG treatment of KOA. Compared with known drugs (diclofenac diethylamine emulsion and Jin Huang San), 2-(SGlutathionyl) acetyl glutathione, daidzein, pelargonic acid, and sulfamethoxazole increased in the HMYG, and the metabolic pathways included the oxytocin signaling pathway, platelet activation, olfactory transduction, phototransduction, and cGMP-PKG signaling pathway. The expression levels of cleaved-caspase-3, Bcl-2, PIK3a, TP53, TGFB1, and NFKB1 were reversed after HMYG treatment. Conclusion: It has been observed that synovitis ointment relieves KOA. UHPLC-MS can analyze the potential mechanism of action of the herbal compound of the synovitis ointment.