Knee Joint Tissues Research Articles

Protein folding dependence on selenoprotein M contributes to steady cartilage extracellular matrix repressing ferroptosis via PERK/ATF4/CHAC1 axis

ObjectiveInitiation of endoplasmic reticulum (ER) stress is pivotal to the advancement of osteoarthritis (OA). We aimed to explore the function of ER-resident selenoprotein M (SELM) in cartilage-forming chondrocytes, investigating how SELM participates in cartilage extracellular matrix (ECM) metabolism and ER stress modulation. MethodsArticular cartilage samples with knee OA undergoing total knee arthroplasty were categorized into OA-smooth and OA-damaged groups, with primary chondrocytes extracted from smooth areas. Destabilization of the medial meniscus was induced in male C57BL6/J mice, with sham operations on the left knee as controls. After 8 weeks, knee joint tissues were collected for analysis. Histology and immunohistochemistry examined cartilage damage. Molecular biology techniques investigated how SELM affects ECM metabolism and ER stress regulation. RNA sequencing revealed the pathway changes after SELM intervention. AlphaFold demonstrated how SELM interacts with other molecules. Cultured cartilage explants helped determine the effects of SELM supplementation. ResultsSELM expression was reduced in the damaged cartilage. Increasing SELM levels positively impacted ECM equilibrium. Decreasing SELM expression activated genes linked to degenerative ailments and impaired the cellular response to misfolded proteins, initiating the PERK/P-EIF2A/ATF4 pathway and exacerbating GSH/GSSG imbalance via the ATF4/CHAC1 axis. SELM likely participated in protein folding and modification by leveraging its thioredoxin domains. In vitro SELM supplementation mitigated IL-1β effects on damaged cartilage explants and suppressed beneficial chondrocyte phenotypes. ConclusionsOur results confirm the involvement of SELM in ER stress-induced cartilage damage as well as protein folding, pointing to new directions in molecular therapy for degenerative diseases.

PP2Ac Regulates Autophagy via Mediating mTORC1 and ULK1 During Osteoclastogenesis in the Subchondral Bone of Osteoarthritis.

The molecular mechanism underlying abnormal osteoclastogenesis triggering subchondral bone remodeling in osteoarthritis (OA) is still unclear. Here, single-cell and bulk transcriptomics sequencing analyses are performed on GEO datasets to identify key molecules and validate them using knee joint tissues from OA patients and rat OA models. It is found that the catalytic subunit of protein phosphatase 2A (PP2Ac) is highly expressed during osteoclastogenesis in the early stage of OA and is correlated with autophagy. Knockdown or inhibition of PP2Ac weakened autophagy during osteoclastogenesis. Furthermore, the ULK1 expression of the downstream genes is significantly increased when PP2Ac is knocked down. PP2Ac-mediated autophagy is dependent on ULK1 phosphorylation activity during osteoclastogenesis, which is associated with enhanced dephosphorylation of ULK1 Ser637 residue regulating at the post-translational level. Additionally, mTORC1 inhibition facilitated the expression level of PP2Ac during osteoclastogenesis. In animal OA models, decreasing the expression of PP2Ac ameliorated early OA progression. The findings suggest that PP2Ac is also a promising therapeutic target in early OA.

Artesunate attenuates osteoarthritis in mice by promoting MTA1 transcription through a USP7/FoxO1 axis

Artesunate (ART) is a derivative of artemisinin and has anti-inflammatory, anti-tumor, and anti-angiogenic properties. Although ART has been implicated in osteoarthritis (OA), the mechanism needs to be further dissected. Here, we explored the effects of ART on the development of OA and the underlying mechanism using destabilization of the medial meniscus (DMM) surgical instability model. Mice with OA were developed using DMM and treated with ART. The pathological morphology of knee joint tissues was examined, and the degeneration of joint cartilage was assessed. Mouse knee chondrocytes were isolated and induced with IL-1β, followed by ART treatment. ART alleviates OA in mice by elevating ubiquitin carboxyl-terminal hydrolase 7 (USP7) expression, and USP7 inhibitor (P22077) treatment mitigated the protective effects of ART on chondrocytes. We also showed that USP7 mediated the deubiquitination of forkhead box protein O1 (FoxO1), while FoxO1 alleviated chondrocyte injury. In addition, FoxO1 promoted metastasis-associated protein MTA1 (MTA1) transcription, and downregulation of MTA1 exacerbated chondrocyte injury. Our study identifies that USP7/FoxO1/MTA1 is a key signaling cascade in the treatment of ART on OA.

Diosmetin ameliorates osteoarthritic inflammation in vivo and ECM macromolecules degradation in interleukin-1β-stimulated murine chondrocytes through the Nrf2/NF-κB pathway.

Osteoarthritis (OA) is a prevailing degenerative disease in elderly population and can lead to severe joint dysfunction. Studies have revealed various pharmacological activities of diosmetin, including the anti-OA efficacy. The present study further investigated its effect on interleukin (IL)-1β-induced OA in chondrocytes. Primary chondrocytes were isolated from young mice, stimulated with IL-1β (10 ng/mL), and pretreated with diosmetin (10 and 20 μM) to conduct the in vitro assays. CCK-8 assay assessed the cytotoxicity of diosmetin whereas the levels of inflammatory factors (PGE2, nitrite, TNF-α, and IL-6) in homogenized cells were evaluated by ELISA. The levels of inflammatory cytokines, content of extracellular matrix (ECM), and signaling-related proteins (Nrf2, HO-1, and NF-κB p65) were assessed by western blotting. Expression of collagen II, p65, and Nrf2 in the chondrocytes was confirmed by immunofluorescence staining. The chondrocytes treated with IL-1β and diosmetin were transfected with Nrf2 knockdown plasmid (si-Nrf2) to investigate the role of Nrf2. In vivo OA mouse model was induced by surgically destabilizing the medial meniscus (DMM). Safranin O staining was conducted to assess the OA severity in the knee-joint tissue. Diosmetin suppressed the expression of iNOS, COX-2, PGE2, nitrite, TNF-α, IL-6, MMP-13, and ADAMTS-5 induced by IL-1β in chondrocytes. The expression of p-p65, p-IκBα, and nuclear p65 was decreased whereas that of Nrf2 and HO-1 increased by diosmetin treatment in IL-1β-treated chondrocytes. Nrf2 knockdown by siRNA reversed the inhibitory effect of diosmetin on IL-1β-induced degradation of ECM proteins and inflammatory factors in cultured chondrocytes. In the DMM-induced model of OA, diosmetin alleviated cartilage degeneration and decreased the Osteoarthritis Research Society International score. Diosmetin ameliorates expression of inflammation biomarkers and ECM macromolecules degradation in cultured murine chondrocytes via inactivation of NF-κB signaling by activating Nrf2/HO-1 signaling pathway.

Downregulation of interleukin 11 regulates the transforming growth factor-β/ERK1/2 signaling pathway to inhibit articular capsule fibrosis and alleviate post-traumatic articular capsule contracture

BackgroundPost-traumatic capsular contracture is a common complication of joint injury and surgery. Post-traumatic capsular contracture is associated with fibrosis characterized by excessive differentiation and proliferation of myofibroblasts and abnormal secretion and accumulation of extracellular matrix. Previous studies have suggested that IL11 plays a role in myocardial fibrosis. We thus hypothesized that IL11 may play a fibrotic role during capsular contracture, in order to discover new targets for preventing joint capsule contracture MethodsWe constructed a post-traumatic contracture model by excessively extending the knee joint and fixing the joint in the flexion position, and a post-traumatic joint capsule contracture model was constructed in the wild-type, IL11-/-, IL11R -/-, α-SMA-cre-IL11fl/fl, α-SMA-cre-IL11Rfl/fl mouse strain, with wild-type mice without any treatment of the knee joint as the control group. Fibrotic markers and the expression of IL11 and IL11R in knee joint tissue were detected in each group of mice. The NIH3T3 cell line was used for in vitro analyses. The expression of fibrosis markers, IL11, TGFβ and ERK1/2 were detected by western blot, ELISA and RT-qPCR. ResultsInhibition of IL11 inhibited ERK1/2 phosphorylation, reduced the secretion of collagen in the joint capsule, and inhibited the excessive differentiation and proliferation of myofibroblasts in the post-traumatic joint capsule contracture, thus alleviating the joint capsule contracture and obtaining better joint mobility. ConclusionDownregulation of IL11 in traumatic joint capsule contracture inhibits ERK1/2 phosphorylation, thus significantly relieving joint capsule contracture. Our findings indicate the TGFβ/IL11/ERK1/2 axis is an important pathway for the differentiation of fibroblasts into myofibroblasts. Anti-IL11 treatment is an effective means to prevent traumatic joint capsule contracture.

Effect of heat-reinforcing needling on hypoxia-inducible factor 1α and glycolysis activity in rabbits with cold syndrome of rheumatoid arthritis.

To observe the effect of heat-reinforcing needling (HRN) on synovial inflammation, hypoxia-inducible factor-1α (HIF-1α) and glycolytic activity in serum and synovial tissue in rabbits with cold syndrome of rheumatoid arthritis (RA), so as to explore its mechanisms underlying improvement of RA. A total of 32 rabbits were randomly divided into normal, model, inhibitor and HRN groups, with 8 rabbits in each group. The RA with cold syndrome model was induced by injecting ovalbumin dry powder and Freund's complete adjuvant combined with cold freezing. Rabbits in the inhibitor group were intraperitoneally injected with 2-methoxyestradiol (2.5 mg/kg), rabbits in the HRN group were received HRN at bilateral "Zusanli" (ST36) for 30 min. The treatments were conducted once daily for 14 consecutive days. After the interventions, the knee circumference and pain threshold were measured. The contents of nicotinamide adenine dinucleotide phosphoric (NADPH), Hexokinase II (HK2) and 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3) in serum of rabbits were detected by ELISA. The pathological morphology of synovial tissue of the knee joints were observed by HE staining. The positive expressions of tumor necrosis factor (TNF-α), interleukin (IL)-1β, IL-6 and IL-17 in synovial tissue of knee joint were detected by immunohistochemistry. The content of lactic acid in synovial tissue of rabbit knee joint was detected by spectrophotometry. The expression levels of HIF-1α, pyruvate kinase 2 (PKM2) and lactate dehydrogenase (LDHA) in synovial tissue of knee joint were detected by Western blot. After intervention, compared with the normal group, the knee circumference was significantly enlarged (P<0.05), the pain threshold was significantly decreased (P<0.05)；the synovial tissue of knee joints showed significant cell proliferation and inflammatory infiltration, the pathological score was significantly increased (P<0.05)；positive expressions of TNF-α, IL-1β, IL-6 and IL-17, the content of lactic acid in synovial tissue, the contents of NADPH, HK2 and PFKFB3 in serum, and the protein expression levels of HIF-1α, PKM2 and LDHA in synovial tissue were increased (all P<0.05) in the model group. Compared with model group, the circumference of knee joint was significantly decreased (P<0.05), the pain threshold was significantly increased (P<0.05)；in synovial tissue, the pathological score was decreased (P<0.05)；the positive expressions of TNF-α, IL-1β, IL-6 and IL-17 in synovial tissue were decreased (P<0.05), the lactic acid content in synovial tissue was decreased (P<0.05)；the contents of NADPH, HK2 and PFKFB3 in serum and the protein expression levels of HIF-1α, PKM2 and LDHA in synovial tissue were decreased (P<0.05) in inhibitor group and HRN group. Compared with the inhibitor group, the synovial pathological score was significantly increased (P<0.05), positive expressions of TNF-α, IL-1β, IL-6 and IL-17, the content of lactic acid in synovial tissue, the contents of NADPH, HK2 and PFKFB3 in serum, and the protein expression levels of HIF-1α, PKM2 and LDHA in synovial tissue were increased (all P<0.05) in HRN group. HRN can increase the pain threshold, reduce the knee circumference and inhibit the inflammatory response in rabbits with cold syndrome of RA. The possible mechanism is related to the down-regulation of HIF-1α and glycolysis activity.

Guasha improves knee osteoarthritis by inhibiting chondrocyte apoptosis and regulating expression of autophagy-related genes and proteins in rats.

To observe the effect of Guasha on inflammation factors, apoptosis and autophagy in the cartilage tissue of knee joint in rats with knee osteoarthritis (KOA), so as to explore its mechanisms underlying improvement of KOA. A total of 51 male SD rats were randomized into three groups：blank control, KOA model and Guasha (n= 17 in each group) . The rats in the blank control group received intra-articular injection of 0.9% NaCl solution in the right knee joint. The KOA model was established by intraarticular injection of glutamate sodium iodoacetic acid in the right knee joint. For rats of the Guasha group, Guasha (at a frequency of 1 time/s, and an applied pressure of 0.3-0.5 kgf) was applied to "Yanglingquan" (GB34) and "Xuehai"(SP10) areas of the right leg, once every other day, for 7 consecutive sessions. The circumference of the right knee was measured, The histopathological changes of right knee cartilage were observed after H.E. staining. The contents of inflammatory factors interleukin (IL)-1β and tumor necrosis factor (TNF)-α in the right knee articular cartilage tissue were assayed using ELISA. The expression levels of autophagy-related key molecule Beclin-1 (homologous series of yeast Atg6), light chain protease complication 3 type II/I (LC3II/LC3 I), ubiquitin binding factor 62 (P62) and cysteine aspartate protease-3 (Caspase-3) mRNAs and proteins of the right knee articular cartilage tissue were measured using real-time fluorescent quantitative PCR and Western blot, separately. The apoptosis of chondrocytes was assayed using TUNEL staining, and the immunoactivity of LC3 determined using immunofluorescence staining. After modeling, the right knee circumfe-rence of the model and Guasha groups was significantly increased compared with the blank control group (P<0.01), and after the intervention, the knee circumference of the Guasha group was markedly decreased in comparison with that of the model group (P<0.05). Results of H.E. staining showed obvious degeneration and defects in the cartilage tissue, necrosis of a large number of chondrocytes, fibrous hyperplasia, accompanied by inflammatory cell infiltration, osteoclast increase, fibroplasia and bone trabecular destruction in the model group, which was relatively milder in the Guasha group. Compared with the blank control group, the expression of Beclin-1 and LC3 mRNAs and proteins, and LC immunofluorescence intensity in the right knee articular cartilage tissue were significantly down-regulated (P<0.01, P<0.001), whereas the expression of P62 and Caspase-3 mRNAs and proteins, the apoptosis rate, contents of IL-1β and TNF-α in the right knee articular cartilage tissue considerably increased (P<0.01, P<0.001) in the model group. In contrast to the model group, the Guasha group had an apparent increase in the expression levels of Beclin-1 and LC3 mRNAs and proteins and LC immunofluorescence intensity in the right knee articular cartilage tissue (P<0.05), and a pronounced decrease in the expression of P62 and Caspase-3 mRNAs and proteins, the apoptosis rate, and contents of IL-1β and TNF-α in the right knee articular cartilage tissue (P<0.05, P<0.01). Guasha stimulation of GB34 and SP10 can improve joint cartilage damage in KOA rats, which may be associated with its functions in inhibiting the excessive release of inflammatory factors and apoptosis, possibly by down-regulating the expression of P62 and Caspase-3 mRNAs and proteins and up-regulating the expression of Beclin-1 and LC3 mRNAs and proteins, and by promoting autophagy of chondrocytes.

Evaluating the Anti-Osteoarthritis Potential of Standardized Boswellia serrata Gum Resin Extract in Alleviating Knee Joint Pathology and Inflammation in Osteoarthritis-Induced Models.

Osteoarthritis is a widespread chronic degenerative disease marked by the deterioration of articular cartilage, modifications in subchondral bone, and a spectrum of symptoms, including pain, stiffness, and disability. Ultimately, this condition impairs the patient's quality of life. This study aimed to evaluate the therapeutic efficacy of standardized Boswellia serrata gum resin extract (BSRE) in a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis. A total of 60 rats were allocated into six groups: normal control group (NC), osteoarthritis control (injected with MIA, OC), O + B50 (injected with MIA and treated with 50 mg/kg body weight (BW) BSRE), O + B75 (injected with MIA and treated with 75 mg/kg BW BSRE), O + B100 (injected with MIA and treated with 100 mg/kg BW BSRE), and O + M (injected with MIA and treated with 150 mg/kg BW methyl sulfonyl methane). Several parameters, including knee joint swelling, histopathological changes, and the expression of collagen type II alpha 1 (COL2A1) and aggrecan, were comprehensively assessed. Concurrently, the serum levels and mRNA expression of inflammatory mediators, cytokines, and matrix metalloproteinases (MMPs) were analyzed in both the serum and knee joint synovium. The results demonstrated that BSRE significantly mitigated knee joint swelling, cartilage destruction, and tissue deformation. Notably, BSRE administration markedly upregulated the expression of COL2A1 and aggrecan while concurrently reducing levels of nitric oxide, prostaglandin E2, leukotriene B4, interleukin (IL)-6, and tumor necrosis factor (TNF)-α. Furthermore, a substantial decrease was observed in the mRNA expression of inducible nitric oxide synthase, cyclooxygenase-2, 5-lipoxygenase, IL-6, TNF-α and MMP-3 and -13, thereby indicating promising therapeutic implications for osteoarthritis. In conclusion, BSRE exhibited anti-inflammatory properties and inhibited cartilage matrix degradation in a rat model of MIA-induced osteoarthritis, with the O + B100 group showing significant reductions in swelling and notable improvements in joint cartilage damage. These findings illuminate the preventive and therapeutic potential of BSRE for osteoarthritis treatment, emphasizing the criticality of exhaustive evaluation of novel compounds.

Doxorubicin concentrations in bone tumour-relevant tissues after bolus and continuous infusion: a randomized porcine microdialysis study

PurposeDoxorubicin is a widely used chemotherapeutic drug that can be administered intravenously as both a bolus infusion and a continuous infusion. The latter is believed to lower the risk of cardiotoxicity, which is a critical long-term complication of doxorubicin treatment. The local tissue concentrations of doxorubicin will be reflected in both treatment efficacy and toxicity, but very limited information is available. The aim of this study was to measure the concentration of doxorubicin after continuous and bolus infusion in tissue compartments around a typical location of a bone tumour.MethodsSixteen pigs (female, Danish Landrace, mean weight 77 kg) were randomized into two groups of eight. Both groups received an intravenous infusion of 150 mg doxorubicin; Group 1 received a bolus infusion (10–15 min) and Group 2 received a continuous infusion (6 h). Before infusion, microdialysis catheters were placed intravenously and in four bone tumour-relevant tissue compartments (cancellous bone, subcutaneous tissue, synovial fluid of the knee joint and muscle tissue). Sampling was done (n = 15) over 24 h, and venous blood samples were collected as a reference.ResultsArea under the concentration–time curve (AUC0–24 h) for plasma (total concentration) was significantly different between the two groups, while peak drug concentration (Cmax) was significantly higher in two compartments (plasma and synovial fluid of the knee joint) in Group 1 compared to Group 2. Overall, the unbound tissue concentrations were extremely low with values below 0.20 µg/mL.ConclusionThe pharmacokinetic profile for doxorubicin in the investigated tissues is very similar when comparing bolus and 6 h continuous infusion.

Effects of VX765 on osteoarthritis and chondrocyte inflammation in rats

To investigate the effects and underlying mechanisms of VX765 on osteoarthritis (OA) and chondrocytes inflammation in rats. Chondrocytes were isolated from the knee joints of 4-week-old Sprague Dawley (SD) rats. The third-generation cells were subjected to cell counting kit 8 (CCK-8) analysis to assess the impact of various concentrations (0, 1, 5, 10, 20, 50, 100 μmol/L) of VX765 on rat chondrocyte activity. An in vitro lipopolysaccharide (LPS) induced cell inflammation model was employed, dividing cells into control group, LPS group, VX765 concentration 1 group and VX765 concentration 2 group without obvious cytotoxicity. Western blot, real-time fluorescence quantitative PCR, and ELISA were conducted to measure the expression levels of inflammatory factors-transforming growth factor β 1 (TGF-β 1), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α). Additionally, Western blot and immunofluorescence staining were employed to assess the expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1). Thirty-two SD rats were randomly assigned to sham surgery group (group A), OA group (group B), OA+VX765 (50 mg/kg) group (group C), and OA+VX765 (100 mg/kg) group (group D), with 8 rats in each group. Group A underwent a sham operation with a medial incision, while groups B to D underwent additional transverse incisions to the medial collateral ligament and anterior cruciate ligament, with removal of the medial meniscus. One week post-surgery, groups C and D were orally administered 50 mg/kg and 100 mg/kg VX765, respectively, while groups A and B received an equivalent volume of saline. Histopathological examination using HE and safranin-fast green staining was performed, and Mankin scoring was utilized for evaluation. Immunohistochemical staining technique was employed to analyze the expressions of matrix metalloproteinase 13 (MMP-13) and collagen type Ⅱ. The CCK-8 assay indicated a significant decrease in cell viability at VX765 concentrations exceeding 10 μmol/L ( P<0.05), so 4 μmol/L and 8 μmol/L VX765 without obvious cytotoxicity were selected for subsequent experiments. Following LPS induction, the expressions of TGF-β 1, IL-6, and TNF-α in cells significantly increased when compared with the control group ( P<0.05). However, intervention with 4 μmol/L and 8 μmol/L VX765 led to a significant decrease in expression compared to the LPS group ( P<0.05). Western blot and immunofluorescence staining demonstrated a significant upregulation of Nrf2 pathway-related molecules Nrf2 and HO-1 protein expressions by VX765 ( P<0.05), indicating Nrf2 pathway activation. Histopathological examination of rat knee joint tissues and immunohistochemical staining revealed that, compared to group B, treatment with VX765 in groups C and D improved joint structural damage in rat OA, alleviated inflammatory reactions, downregulated MMP-13 expression, and increased collagen type Ⅱ expression. VX765 can improve rat OA and reduce chondrocyte inflammation, possibly through the activation of the Nrf2 pathway.

RAGE signalling contributes to oxidative stress and inflammation in knee osteoarthritis patients with metabolic syndrome.

Metabolic factors play significant role in the natural history of knee osteoarthritis (KO). There is a limited understanding of molecular and cellular events that give rise to the disease in patients. This study explored the possible cellular mechanisms by which metabolic syndrome leads to KO. This cross-sectional study enrolled 80 subjects with KO who fulfilled the ACR diagnostic criteria and were undergoing total knee replacement surgery. The patients were divided into two groups: KO patients without metabolic syndrome and KO patients with metabolic syndrome. We hypothesised that metabolic syndrome may accelerate pathogenesis of OA by enhanced RAGE axis in articular cartilage and Infrapatellar fat pad of the knee joint. We have found enhanced protein expression of receptor for advanced glycation end products (RAGE) and its ligands AGEs and HMGB-1 in knee joint tissue of KO patients with metabolic syndrome as compared to KO patients without metabolic syndrome. Further downstream, the gene expression of oxidative stress regulators such as NADPH and inflammation, NFĸB were upregulated in KO patients with MetS as compared to KO patients alone. Higher levels of advanced oxidation products and inflammatory marker IL-17 were exhibited in synovial fluid of KO patients with metabolic syndrome. The enhanced levels of these oxidative stress and inflammatory markers were reflected in the serum of KO patients with metabolic syndrome as well. We conclude that enhanced function of RAGE axis could be one of the mechanisms by which metabolic syndrome leads to KO.

Preclinical Study of Dual-Wavelength Light-Emitting Diode Therapy in an Osteoarthritis Rat Model.

To evaluate the efficacy of light-emitting diode (LED) and their dual-wavelengths as a treatment strategy for osteoarthritis. We induced osteoarthritis in male Sprague-Dawley rats by intra-articular injection of sodium iodoacetate into the right rear knee joint. The animals with lesions were divided into an untreated group and an LED-treated group (n=7 each). In the LED-treated group, the lesioned knee was irradiated with lasers (850 and 940 nm) and dose (3.15 J/cm2) for 20 minutes per session, twice a week for 4 weeks. Knee joint tissues were stained and scanned using an in vivo micro-computed tomography (CT) scanner. Serum interleukin (IL)-6 and IL-18 levels were determined using enzyme-linked immuno-sorbent assay. Several functional tests (lines crossed, rotational movement, rearing, and latency to remain rotating rod) were performed 24 hours before LED treatment and at 7, 14, 21, and 28 days after treatment. LED-treated rats showed improved locomotor function and suppressed matrix-degrading cytokines. Micro-CT images indicated that LED therapy had a preserving effect on cartilage and cortical bone. LED treatment using wavelengths of 850 and 940 nm resulted in significant functional, anatomical, and histologic improvements without adverse events in a rat model. Further research is required to determine the optimal wavelength, duration, and combination method, which will maximize treatment effectiveness.

Magnetic targeting of lornoxicam/SPION bilosomes loaded in a thermosensitive in situ hydrogel system for the management of osteoarthritis: Optimization, in vitro, ex vivo, and in vivo studies in rat model via modulation of RANKL/OPG

Osteoarthritis is a bone and joint condition characterized pathologically by articular cartilage degenerative damage and can develop into a devastating and permanently disabling disorder. This investigation aimed to formulate the anti-inflammatory drug lornoxicam (LOR) into bile salt–enriched vesicles loaded in an in situ forming hydrogel as a potential local treatment of osteoarthritis. This was achieved by formulating LOR-loaded bilosomes that are also loaded with superparamagnetic iron oxide nanoparticles (SPIONs) for intra-muscular (IM) administration to improve joint targeting and localization by applying an external magnet to the joint. A 31.22 full factorial design was employed to develop the bilosomal dispersions and the optimized formula including SPION (LSB) was loaded into a thermosensitive hydrogel. Moreover, in vivo evaluation revealed that the IM administration of LSB combined with the application of an external magnet to the joint reversed carrageen-induced suppression in motor activity and osteoprotegerin by significantly reducing the elevations in mitogen-activated protein kinases, extracellular signal-regulated kinase, and receptor activator of nuclear factor kappa beta/osteoprotegerin expressions. In addition, the histopathological evaluation of knee joint tissues showed a remarkable improvement in the injured joint tissues. The results proved that the developed LSB could be a promising IM drug delivery system for osteoarthritis management.Graphical

Classification of distinct osteoarthritis subtypes with different knee joint tissues by gene expression profiles.

Knee osteoarthritis (OA) involves a variety of tissues in the joint. Gene expression profiles in different tissues are of great importance in order to understand OA. First, we obtained gene expression profiles of cartilage, synovium, subchondral bone, and meniscus from the Gene Expression Omnibus (GEO). Several datasets were standardized by merging and removing batch effects. Then, we used unsupervised clustering to divide OA into three subtypes. The gene ontology and pathway enrichment of three subtypes were analyzed. CIBERSORT was used to evaluate the infiltration of immune cells in different subtypes. Finally, OA-related genes were obtained from the Molecular Signatures Database for validation, and diagnostic markers were screened according to clinical characteristics. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to verify the effectiveness of markers. C1 subtype is mainly concentrated in the development of skeletal muscle organs, C2 lies in metabolic process and immune response, and C3 in pyroptosis and cell death process. Therefore, we divided OA into three subtypes: bone remodelling subtype (C1), immune metabolism subtype (C2), and cartilage degradation subtype (C3). The number of macrophage M0 and activated mast cells of C2 subtype was significantly higher than those of the other two subtypes. COL2A1 has significant differences in different subtypes. The expression of COL2A1 is related to age, and trafficking protein particle complex subunit 2 is related to the sex of OA patients. This study linked different tissues with gene expression profiles, revealing different molecular subtypes of patients with knee OA. The relationship between clinical characteristics and OA-related genes was also studied, which provides a new concept for the diagnosis and treatment of OA.

Antiarthritic activity of Physalis peruviana fruit extract via inhibition of inflammatory mediators: Integrated in vitro, in vivo and in silico study

Ethnopharmacological relevanceP. peruviana fruit, native to Andean region, is cultivated worldwide for its adaptability to various soil natures and climatic conditions. It is increasingly consumed for its high nutritional profile and history of ethnomedical uses including treatment of arthritis. Little pharmacological evidences support this folk use except for previous in vitro study that reported significant inhibition of protein denaturation. Aim of the studyThe study aims at providing new in vivo evidence on antiarthritic activity of P. peruviana fruits in vivo that justifies its traditional use through mechanism-based experiment. Material and methodsInhibition of inflammatory mediators is considered one of the key treatments to alleviate painful symptoms of rheumatoid arthritis (RA). Anti-inflammatory activity was assessed against COX-1 and COX-2 activity in vitro.Serum TNFα, IL-1β and IL-6 were traced using in vivo model of adjuvant-induced arthritis. Gross/inflammatory changes in rat paw, relative mass indices of spleen and liver were further investigated together with joint tissue histoarchitecture. Seven metabolites from different phytochemical classes, that were previously reported in P. peruviana fruit, were evaluated in silico against TNF-α target protein (PDB ID: 2AZ5) to assess their inhibitory effect. This was followed by assessment of their drug-likeness based on Lipinski's rule according to their physicochemical and pharmacokinetic properties. ResultsHigh dose of extract (E−1000 mg) improved adjuvant-induced cachexia and attenuated immune-inflammatory responses in paw and serum parameters, with equipotent effect to MTX, in addition to minimal side effect profile on spleen and liver. Histopathological study of knee joint tissues confirmed dose-dependent improvement in arthritic groups treated with P. peruviana fruit extracts. The insilico study recommended steroidal lactones withaperuvin E/C and hydroxywithanolide E as promising lead compounds for inhibiting TNF enzyme as evidenced by docking scores of 6.301, 5.488 and 5.763 kcal/mol, respectively, fitting as well the Lipinski's rule of drug likeness. ConclusionThe study provided novel approach that rationalize folk use of P. peruviana fruit in treatment of arthritis.

Silencing of STUB1 relieves osteoarthritis via inducing NRF2-mediated M2 macrophage polarization

ObjectivesShifting macrophages towards an anti-inflammatory state is key in treating osteoarthritis (OA) by reducing inflammation and tissue damage. However, the underlying mechanisms guiding this shift remain largely undefined. STUB1, an E3 ubiquitin ligase, known for its regulatory role in macrophage polarization. This study aims to explore the function and underlying action mechanisms of STUB1 in OA. MethodsAn in vivo OA model was established in rats. Hematoxylin-Eosin and safranin O-fast green staining were performed to reveal the hispathological injuries in knee-joint tissues. Immunohistochemistry and flow cytometry were performed to detect the distribution of M1 and M2 macrophages. The inflammatory response (TNF-α and IL-6 levels) was evaluated by ELISA. In vitro, the interaction between STUB1 and NFR2 was determined by CO-IP and pull-down assays. After treated with LPS (an in vitro model of OA), the viability and apoptosis of chondrocytes were measured by CCK-8 and flow cytometry, respectively. ResultsSilencing STUB1 alleviated OA in rats, as indicated by reduced subchondral bone thickness, knee synovitis score, histopathological damages, and inflammatory response. STUB1 silencing also decreased M1 macrophages and increased M2 macrophages in both in vivo and in vitro settings. NRF2 was identified as a target of STUB1, with STUB1 mediating its ubiquitination. Silencing NRF2 reversed the effects of STUB1 silencing on inducing M2 macrophage polarization. Furthermore, silencing STUB1 upregulated NRF2 expression in LPS-treated chondrocytes, promoting cell viability and inhibiting apoptosis. ConclusionSilencing STUB1 induces M2 macrophage polarization by inhibiting NRF2 ubiquitination, thereby contributing to the mitigation of OA.

Impact of hyaluronic acid injection on the knee joint friction

PurposeThe purpose of this in vitro study was to investigate whether or not hyaluronic acid supplementation improves knee joint friction during osteoarthritis progression under gait-like loading conditions.MethodsTwelve human cadaveric knee joints were equally divided into mild and moderate osteoarthritic groups. After initial conservative preparation, a passive pendulum setup was used to test the whole joints under gait-like conditions before and after hyaluronic acid supplementation. The friction-related damping properties given by the coefficient of friction µ and the damping coefficient c (in kg m2/s) were calculated from the decaying flexion–extension motion of the knee. Subsequently, tibial and femoral cartilage and meniscus samples were extracted from the joints and tested in an established dynamic pin-on-plate tribometer using synthetic synovial fluid followed by synthetic synovial fluid supplemented with hyaluronic acid as lubricant. Friction was quantified by calculating the coefficient of friction.ResultsIn the pendulum tests, the moderate OA group indicated significantly lower c0 values (p < 0.05) under stance phase conditions and significantly lower µ0 (p = 0.01) values under swing phase conditions. No degeneration-related statistical differences were found for µend or cend. Friction was not significantly different (p > 0.05) with regard to mild and moderate osteoarthritis in the pin-on-plate tests. Additionally, hyaluronic acid did not affect friction in both, the pendulum (p > 0.05) and pin-on-plate friction tests (p > 0.05).ConclusionThe results of this in vitro study suggested that the friction of cadaveric knee joint tissues does not increase with progressing degeneration. Moreover, hyaluronic acid viscosupplementation does not lead to an initial decrease in knee joint friction.

Rapid specialization and stiffening of the primitive matrix in developing articular cartilage and meniscus.

Understanding early patterning events in the extracellular matrix (ECM) formation can provide a blueprint for regenerative strategies to better recapitulate the function of native tissues. Currently, there is little knowledge on the initial, incipient ECM of articular cartilage and meniscus, two load-bearing counterparts of the knee joint. This study elucidated distinctive traits of their developing ECMs by studying the composition and biomechanics of these two tissues in mice from mid-gestation (embryonic day 15.5) to neo-natal (post-natal day 7) stages. We show that articular cartilage initiates with the formation of a pericellular matrix (PCM)-like primitive matrix, followed by the separation into distinct PCM and territorial/interterritorial (T/IT)-ECM domains, and then, further expansion of the T/IT-ECM through maturity. In this process, the primitive matrix undergoes a rapid, exponential stiffening, with a daily modulus increase rate of 35.7% [31.9 39.6]% (mean [95% CI]). Meanwhile, the matrix becomes more heterogeneous in the spatial distribution of properties, with concurrent exponential increases in the standard deviation of micromodulus and the slope correlating local micromodulus with the distance from cell surface. In comparison to articular cartilage, the primitive matrix of meniscus also exhibits exponential stiffening and an increase in heterogeneity, albeit with a much slower daily stiffening rate of 19.8% [14.9 24.9]% and a delayed separation of PCM and T/IT-ECM. These contrasts underscore distinct development paths of hyaline versus fibrocartilage. Collectively, these findings provide new insights into how knee joint tissues form to better guide cell- and biomaterial-based repair of articular cartilage, meniscus and potentially other load-bearing cartilaginous tissues. STATEMENT OF SIGNIFICANCE: Successful regeneration of articular cartilage and meniscus is challenged by incomplete knowledge of early events that drive the initial formation of the tissues' extracellular matrix in vivo. This study shows that articular cartilage initiates with a pericellular matrix (PCM)-like primitive matrix during embryonic development. This primitive matrix then separates into distinct PCM and territorial/interterritorial domains, undergoes an exponential daily stiffening of ≈36% and an increase in micromechanical heterogeneity. At this early stage, the meniscus primitive matrix shows differential molecular traits and exhibits a slower daily stiffening of ≈20%, underscoring distinct matrix development between these two tissues. Our findings thus establish a new blueprint to guide the design of regenerative strategies to recapitulate the key developmental steps in vivo.

TissueGene-C induces long-term analgesic effects through regulation of pain mediators and neuronal sensitization in a rat monoiodoacetate-induced model of osteoarthritis pain

TissueGene-C (TG-C), a combination of human allogeneic chondrocytes and irradiated GP2-293 cells engineered to overexpress transforming growth factor-β1 (TGF-β1), has been developed as a novel cell-based gene therapy and a candidate for disease modifying osteoarthritis drug (DMOAD). We aim to investigate analgesic mechanism of TG-C in a pre-clinical animal model with monoiodoacetate (MIA)-induced pain. We used a rat MIA model of osteoarthritis (OA) pain. We examined that TG-C can regulate pain by inhibiting the upregulation of various pain mediators in both knee joint tissue and dorsal root ganglia (DRG) (n=112) and alleviating pain behavior (n=41) and neuronal hyperexcitability in DRG (n=60), afferent nerve fiber (n=24), and spinal cord (n=35). TG-C significantly alleviated pain-related behavior by restoring altered dynamic weight bearing and reduced mechanical threshold of the affected hindlimb. TG-C significantly suppressed the expression of nerve growth factor (NGF) and calcitonin gene-related peptide (CGRP) in inflamed joint tissue. TG-C significantly suppressed the upregulation of tropomyosin receptor kinase A (TrkA) and nerve injury/regeneration protein (GAP43) and activation of Iba1-positive microglial cells in DRG. TG-C significantly recovered neuronal hyperexcitability by restoring RMP and firing threshold and frequency of DRG neurons, attenuating firing rates of mechanosensitive C- or Aδ-nerve fiber innervating knee joint, and lowering increased miniature and evoked excitatory postsynaptic currents (mEPSCs and eEPSCs) in the spinal cord. Our results demonstrated that TG-C exerted potent analgesic effects in a rat MIA model of OA pain by inhibiting the upregulation of pain mediators and modulating neuronal sensitization.

Protective effect of vaginal resveratrol administration on joint tissues in ovariectomized rats: Targeting mTOR and сaspase 3

IntroductionEstrogens play a considerable role in maintaining bone and articular cartilage homeostasis. Menopause provokes joint disorders due to metabolic syndrome and altered signaling pathways. Phytoestrogen resveratrol was demonstrated to provide chondroprotective and osteoprotective effects. However, the mechanisms of such action of Resveratrol are still being explored. AimThe study aims to determine the effect of Resveratrol on the joints and its therapeutic mechanism in ovariectomized rats. Material and methodsThe study was carried out on Wistar female rats that were divided into three groups, including control animals; ovariectomized rats (OVX); and the OVX group treated with an intravaginal gel containing Resveratrol (0.5 % 0.1 mL, daily 28 days). Knee joint tissues (articular cartilage, subchondral plate, subchondral bone) were assessed by histomorphometry. The expression of mTOR, PTEN, Caspase 3 and BCL-2 in articular cartilage and subchondral bone were evaluated immunohistochemically. ResultsResveratrol treatment of OVX rats prevented weight gain by 17 % (P < 0.001), demonstrating the systemic effect on metabolic pathways. Although there were no statistically significant differences in the thickness of articular cartilage between groups, OVX rats possessed degenerative changes in chondrocytes, associated with the enhanced expression of mTOR (P < 0.001) and Casp-3 (P = 0.005). Resveratrol decreased mTOR (P = 0.007) and Casp-3 (P = 0.011) expression in chondrocytes, reducing degenerative changes. At the same time, resveratrol attenuated the deterioration of trabecular bone in OVX rats (P = 0.002). This effect was through the up-regulation of BCL-2 (P = 0.018) and down-regulation of Casp-3 expression (P < 0.001). ConclusionsIntravaginal administration of resveratrol provided systemic effects and ameliorated joint tissue structure and signaling in OVX rats through stimulation of BCL-2 and reduced Casp-3 expression.