Extracorporeal Shock Wave and Melatonin Alleviate Joint Capsule Fibrosis after Knee Trauma in Rats by Regulating Autophagy.

BACKGROUND: Joint contracture is a common clinical problem affecting joint function. Capsule fibrosis plays a pivotal role in the progression of Joint contracture. Previous studies have reported that autophagy plays a regulatory role in visceral fibrosis. OBJECTIVE: This study aimed to investigate whether extracorporeal shock wave therapy (ESWT) and melatonin alleviate joint capsule fibrosis in rats with extended knee joint contracture by regulating autophagy. METHODS: A rat knee joint extension contracture model was made. Then, the rats were treated with ESWT, melatonin, ESWT + melatonin, or ESWT + melatonin + mTOR agonist for 4 weeks. The range of motion (ROM) of the knee joints was measured. Joint capsules were collected and observed for pathological changes by H&E and Masson staining. LC3B protein expression was evaluated by immunofluorescence staining. TGF-ß1, MMP-1, Col-Ⅰ, Col-Ⅲ, LC3, ATG7, Beclin1, p-AMPK, p-mTOR and p-ULK1 protein expressions were measured by Western blot assay. RESULTS: The intervention groups had significantly improved ROM of knee joint (P < 0.05), significantly improved pathological changes on HE and Masson staining, significantly decreased protein expressions of TGF-ß1, MMP-1, Col-Ⅰ, Col-Ⅲ and pmTOR (P < 0.05), and significantly increased protein expressions of LC3B, LC3II/LC3I ratio, ATG7, Beclin1, p-AMPK, and p-ULK1 (P < 0.05). Among these groups, the effects demonstrated by the ESWT + melatonin group were the best. With the mTOR agonist supplement, the therapeutic effects of extracorporeal shock waves and melatonin were significantly reduced. CONCLUSION: ESWT plus melatonin alleviated knee joint capsule fibrosis in rats by regulating autophagy.

Preliminary study of extracorporeal shock wave alleviating joint capsule fibrosis caused by internal bleeding of knee joint in rats.

PURPOSE: Joint contracture is a common disease in clinical practice, joint bleeding is an important factor affecting the progression of joint contracture. This study aimed to explore the effect of extracorporeal shock wave on alleviating joint capsule fibrosis caused by intra-articular hemorrhage in rats. METHODS: Forty two SD rats were randomly divided into seven groups. Perform simple fixation and fixation after blood injection separately. Measure the range of motion of each group's knee joints and calculate the corresponding degree of contraction. Use HE staining and Masson staining to detect the number of anterior joint capsule cells and collagen deposition. Detection of changes in Wnt1, ß-catenin protein expression in joint capsule using Western blotting. RESULTS: Compared to group C, the degree of knee joint contracture in M1 and M2 groups of rats increased, and collagen deposition, cell number and Wnt1, ß-catenin protein expression also increased accordingly. Compared to M1 and M2 groups, the degree of knee contraction in E1 and E2 groups were reduced, while collagen deposition, cell number and Wnt1, ß-catenin protein expression were decreased, and the degree of joint contracture in NR1 and NR2 groups showed no significant improvement. Compared to NR1 and NR2 groups, the degree of knee contraction in E1 and E2 groups were reduced, while collagen deposition, cell number and Wnt1, ß-catenin protein expression were decreased. CONCLUSIONS: Both rat models of knee joint contracture were successful, and joint bleeding can exacerbate joint contracture. Extracorporeal shock waves alleviate joint capsule fibrosis caused by intra-articular bleeding in rats.

Pt(IV) complexes loaded hollow copper sulfide nanoparticles for tumor chemo/photothermal/photodynamic therapy.

Hollow CuS nanoparticles can achieve photothermal and photodynamic therapy (PDT) in tumor treatment. However, excessive GSH in the tumor cells will consume the reactive oxygen species produced by PDT and reduce the PDT effect. Cisplatin is a broad-spectrum antineoplastic drug that can be used in a variety of tumor treatments. However, cisplatin is cytotoxic to normal cells while it kills tumor cells. Therefore, we construct Pt(IV) complexes loaded hollow CuS nanoparticles to attenuate the toxicity of cisplatin and enhance the PDT effect of the hollow CuS nanoparticles. The nanoparticles were proved to be able to accumulate around the tumor site through the enhanced permeability and retention (EPR) effect to achieve a synergistic chemo/photothermal/photodynamic therapy.

DDR2/STAT3 Positive Feedback Loop Mediates the Immunosuppressive Microenvironment by Upregulating PD-L1 and Recruiting MDSCs in Oxaliplatin-Resistant HCC.

BACKGROUND AND AIMS: Transcriptome sequencing revealed high expression of DDR2 in oxaliplatin-resistant hepatocellular carcinoma (HCC). This study aimed to explore the role of DDR2 in oxaliplatin resistance and immune evasion in HCC. METHODS: Oxaliplatin-resistant HCC cell lines were established. The interaction between DDR2 and STAT3 was investigated, along with the mechanisms involved in DDR2/STAT3-mediated PD-L1 upregulation and polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) accumulation both in vitro and in vivo. RESULTS: DDR2 was found to induce the phosphorylation of STAT3, leading to its nuclear translocation. Conversely, the activation of STAT3 enhanced DDR2 expression. A positive feedback loop involving DDR2/STAT3 was identified in oxaliplatin-resistant HCC, which was associated with PD-L1 upregulation and PMN-MDSCs accumulation. Knockdown of DDR2 and STAT3 sensitized oxaliplatin-resistant HCC cells to oxaliplatin and resulted in decreased PMN-MDSCs and increased CD8+ T cells in the tumor microenvironment. Enzyme-linked immunosorbent array and MDSC transwell migration assays indicated that oxaliplatin-resistant HCC cells recruited PMN-MDSCs through CCL20. Dual luciferase reporter assays demonstrated that STAT3 can directly enhance the transcription of PD-L1 and CCL20. Furthermore, treatment with a PD-L1 antibody in combination with CCL20 blockade had significant antitumor effects on oxaliplatin-resistant HCC. CONCLUSIONS: Our findings revealed a positive feedback mechanism involving DDR2 and STAT3 that mediates the immunosuppressive microenvironment and promotes oxaliplatin resistance and immune evasion via PD-L1 upregulation and PMN-MDSC recruitment. Targeting the DDR2/STAT3 pathway may be a promising therapeutic strategy to overcome immune escape and chemoresistance in HCC.

Role of hypoxia-mediated pyroptosis in the development of extending knee joint contracture in rats.

Joint contracture is one of the common diseases clinically, and joint capsule fibrosis is considered to be one of the most important pathological changes of joint contracture. However, the underlying mechanism of joint capsule fibrosis is still controversial. The present study aims to establish an animal model of knee extending joint contracture in rats, and to investigate the role of hypoxia-mediated pyroptosis in the progression of joint contracture using this animal model. 36 male SD rats were selected, 6 of which were not immobilized and were used as control group, while 30 rats were divided into I-1 group (immobilized for 1 week following 7 weeks of free movement), I-2 group (immobilized for 2 weeks following 6 weeks of free movement), I-4 group (immobilized for 4 weeks following 4 weeks of free movement), I-6 group (immobilized for 6 weeks following 2 weeks of free movement) and I-8 group (immobilized for 8 weeks) according to different immobilizing time. The progression of joint contracture was assessed by the measurement of knee joint range of motion, collagen deposition in joint capsule was examined with Masson staining, protein expression levels of HIF-1α, NLRP3, Caspase-1, GSDMD-N, TGF-ß1, α-SMA and p-Smad3 in joint capsule were assessed using western blotting, and the morphological changes of fibroblasts were observed by transmission electron microscopy. The degree of total and arthrogenic contracture progressed from the first week and lasted until the first eight weeks after immobilization. The degree of total and arthrogenic contracture progressed rapidly in the first four weeks after immobilization and then progressed slowly. Masson staining indicated that collagen deposition in joint capsule gradually increased in the first 8 weeks following immobilization. Western blotting analysis showed that the protein levels of HIF-1α continued to increase during the first 8 weeks of immobilization, and the protein levels of pyroptosis-related proteins NLRP3, Caspase-1, GSDMD-N continued to increase in the first 4 weeks after immobilization and then decreased. The protein levels of fibrosis-related proteins TGF-ß1, p-Smad3 and α-SMA continued to increase in the first 8 weeks after immobilization. Transmission electron microscopy showed that 4 weeks of immobilization induced cell membrane rupture and cell contents overflow, which further indicated the activation of pyroptosis. Knee extending joint contracture animal model can be established by external immobilization orthosis in rats, and the activation of hypoxia-mediated pyroptosis may play a stimulating role in the process of joint capsule fibrosis and joint contracture.

Real-world study of hepatic artery infusion chemotherapy combined with anti-PD-1 immunotherapy for hepatocellular carcinoma patients with portal vein tumor thrombus.

Background: Patients with hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT) present a poor prognosis. Current systemic therapies offer limited benefits. Hepatic artery infusion chemotherapy (HAIC) is a local regional treatment for advanced HCC, particularly in selected patients such as patients with PVTT or high intrahepatic tumor burden. Objectives: The purpose of this study is to retrospectively evaluate the efficacy and safety of HAIC combined with anti-PD-1 immunotherapy for HCC patients with PVTT, and explore factors related to survival prognosis, providing clues for treatment decisions for HCC patients. Design: This is a single-center retrospective study conducted over 2 years on consecutive PVTT patients receiving HAIC combined anti-PD-1 antibodies. Methods: The primary endpoint was overall survival (OS). Univariate and multivariate analyses were performed to identify prognostic factors affecting OS. Treatment-associated adverse events were evaluated as well. Results: A total of 119 patients were analyzed. The median OS and PFS were 14.9 months and 6.9 months. A total of 31.1% of grade 3-4 adverse events were reported, with elevated transaminase and total bilirubin being the most common. The independent variables correlated with survival include treatment-related alpha-fetoprotein (AFP) response, the presence of extrahepatic organ metastasis, absolute value of platelet (PLT), neutrophil-to-lymphocyte ratio, and combined usage of tyrosine kinase inhibitors (TKIs). Conclusion: In HCC patients with PVTT, combination therapy with HAIC and anti-PD-1 antibodies might be a promising therapy. The efficacy and safety of this combination protocol on patients with HCC complicated by PVTT warrants further investigation prospectively, especially in combination with TKIs.

Maternal prednisone exposure during pregnancy elevates susceptibility to osteoporosis in female offspring: The role of mitophagy/FNDC5 alteration in skeletal muscle.

Maternal exposure to glucocorticoids has been associated with adverse outcomes in offspring. However, the consequences and mechanisms of gestational exposure to prednisone on susceptibility to osteoporosis in the offspring remain unclear. Here, we found that gestational prednisone exposure enhanced susceptibility to osteoporosis in adult mouse offspring. In a further exploration of myogenic mechanisms, results showed that gestational prednisone exposure down-regulated FNDC5/irisin protein expression and activation of OPTN-dependent mitophagy in skeletal muscle of adult offspring. Additional experiments elucidated that activated mitophagy significantly inhibited the expression of FNDC5/irisin in skeletal muscle cells. Likewise, we observed delayed fetal bone development, downregulated FNDC5/irisin expression, and activated mitophagy in fetal skeletal muscle upon gestational prednisone exposure. In addition, an elevated total m6A level was observed in fetal skeletal muscle after gestational prednisone exposure. Finally, gestational supplementation with S-adenosylhomocysteine (SAH), an inhibitor of m6A activity, attenuated mitophagy and restored FNDC5/irisin expression in fetal skeletal muscle, which in turn reversed fetal bone development. Overall, these data indicate that gestational prednisone exposure increases m6A modification, activates mitophagy, and decreases FNDC5/irisin expression in skeletal muscle, thus elevating osteoporosis susceptibility in adult offspring. Our results provide a new perspective on the earlier prevention and treatment of fetal-derived osteoporosis.

Development and Preliminary Validation of a Novel Convolutional Neural Network Model for Predicting Treatment Response in Patients with Unresectable Hepatocellular Carcinoma Receiving Hepatic Arterial Infusion Chemotherapy.

The goal of this study was to evaluate the performance of a convolutional neural network (CNN) with preoperative MRI and clinical factors in predicting the treatment response of unresectable hepatocellular carcinoma (HCC) patients receiving hepatic arterial infusion chemotherapy (HAIC). A total of 191 patients with unresectable HCC who underwent HAIC in our hospital between May 2019 and March 2022 were retrospectively recruited. We selected InceptionV4 from three representative CNN models, AlexNet, ResNet, and InceptionV4, according to the cross-entropy loss (CEL). We subsequently developed InceptionV4 to fuse the information from qualified pretreatment MRI data and patient clinical factors. Radiomic information was evaluated based on several constant sequences, including enhanced T1-weighted sequences (with arterial, portal, and delayed phases), T2 FSE sequences, and dual-echo sequences. The performance of InceptionV4 was cross-validated in the training cohort (n = 127) and internally validated in an independent cohort (n = 64), with comparisons against single important clinical factors and radiologists in terms of receiver operating characteristic (ROC) curves. Class activation mapping was used to visualize the InceptionV4 model. The InceptionV4 model achieved an AUC of 0.871 (95% confidence interval [CI] 0.761-0.981) in the cross-validation cohort and an AUC of 0.826 (95% CI 0.682-0.970) in the internal validation cohort; these two models performed better than did the other methods (AUC ranges 0.783-0.873 and 0.708-0.806 for cross- and internal validations, respectively; P < 0.01). The present InceptionV4 model, which integrates radiomic information and clinical factors, helps predict the treatment response of unresectable HCC patients receiving HAIC treatment.

Preliminary investigation on the effect of extracorporeal shock wave combined with traction on joint contracture based on PTEN-PI3K/AKT pathway.

To investigate the intervention effect of extracorporeal shock wave combined with manual traction on fixation-induced knee contracture and its influence on PTEN-PI3K/AKT signaling pathway. Thirty-six SD male rats were randomly divided into six groups. The left knee joints were not fixed in the control group (C group). Rats in other groups underwent brace fixation in the extended position of the left knee. After 4 weeks of bracing, it is randomly divided into five groups: Model group (M group), natural recovery group (NR group), extracorporeal shock wave treatment group (ET group), manual traction group (MT group), and extracorporeal shock wave combined with manual traction group (CT group). Joint range of motion (ROM) of left knee was carried out to assess joint function. Hematoxylin and eosin (HE) staining and Masson staining were respectively used to assess the cell number and collagen deposition expression. Immunohistochemical staining and Western blot were used to assess protein levels of phosphatase and tensin homolog (PTEN), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (AKT). The combined therapy was more effective than extracorporeal shock wave therapy or manual traction alone against the joint ROM, cell number and the collagen deposition, low-expression of PTEN, and overexpression of PI3K/AKT in the anterior joint capsule of rats with knee extension contracture. Extracorporeal shock wave combined with manual traction can promote the histopathological changes of anterior joint capsule fibrosis, upregulate the protein expression of PTEN and downregulate the protein expression of PI3K/AKT in the fibrotic joint capsule in a rat joint contracture model.

LINC02362/hsa-miR-18a-5p/FDX1 axis suppresses proliferation and drives cuproptosis and oxaliplatin sensitivity of hepatocellular carcinoma.

Cuproptosis is a novel cell death mechanism caused by copper overload, with FDX1 serving as the key regulator. LncRNAs are known to play a significant role in the aberrant regulation of gene expression in hepatocellular carcinoma (HCC). In this study, we investigated the biological role of the LINC02362/hsa-miR-18a-5p/FDX1 axis in HCC. We first explored the expression pattern, prognostic value, biological functions, drug sensitivity, and immune effect of FDX1. Using bioinformatics techniques, we then predicted several potential target lncRNAs and miRNAs. We identified a lncRNA-miRNA-FDX1 axis based on the ceRNA mechanism. In vitro experiments were conducted to validate the relationship between the lncRNA-miRNA-FDX1 axis and its biological effects in HCC. Finally, we investigated the relationship between the LINC02362/hsa-miR-18a-5p/FDX1 axis and oxaliplatin-induced cuproptosis in HCC. Our findings indicated that FDX1 expression was downregulated in HCC tissues; however, elevated FDX1 expression correlates with improved prognosis and heightened sensitivity to oxaliplatin. We confirmed that LINC02362 binds to and directly regulates the expression of miR-18a-5p, with FDX1 a target of miR-18a-5p. Experimental results suggested that upregulating LINC02362/hsa-miR-18a-5p/FDX1 axis suppressed the proliferation of HCC cells. Furthermore, LINC02362 knockdown led to a reduction in copper concentration and resistance to elesclomol-Cu. We also discovered that augmenting the LINC02362/hsa-miR-18a-5p/FDX1 axis could bolster the sensitivity of HCC to oxaliplatin through cuproptosis. This work presents the LINC02362/hsa-miR-18a-5p/FDX1 axis as a novel pathway that triggers cuproptosis and enhances the sensitivity of HCC to oxaliplatin, presenting a promising therapeutic avenue to combat oxaliplatin resistance in HCC.

The effect of extracorporeal shock wave on joint capsule fibrosis based on A2AR-Nrf2/HO-1 pathway in a rat extending knee immobilization model.

Joint capsule fibrosis, a common complication of joint immobilization, is mainly characterized by abnormal collagen deposition. The present study aimed to investigate the effect of extracorporeal shock wave therapy (ESWT) on reduced collagen deposition in the joint capsule during immobilization-induced joint capsule fibrosis. Additionally, the potential involvement of the adenosine A2A receptor (A2AR)-Neurotrophic factor e2-related factor 2 (Nrf2)/Haem oxygenase-1 (HO-1) pathway was explored. Thirty 3-month-old male Sprague-Dawley rats were randomly assigned to five groups: control (C), immobilization model (IM), natural recovery (NR), ESWT intervention (EI), and ESWT combined with A2AR antagonist SCH 58261 intervention (CI). After the left knee joints of rats in the IM, NR, EI and CI groups were immobilized using a full-extension fixation brace for 4 weeks, the EI and CI groups received ESWT twice a week for 4 weeks. The CI group was also treated with ESWT following intraperitoneal injection of SCH 58261 (0.01 mg/kg) for 4 weeks. The range of motion of the left knee joint was measured, and the protein levels of collagens I and III, A2AR, phosphorylated-protein kinase A/protein kinase A (p-PKA/PKA), p-Nrf2/Nrf2, and HO-1 were analysed by Western blotting. The IM and NR groups showed significantly greater arthrogenic contracture than the C group (P < 0.05). Compared to the NR group, the EI and CI groups exhibited significant improvement in arthrogenic contracture (P < 0.05). Conversely, the EI group showed lower contracture than the CI group (P < 0.05). Similar results were observed for collagen deposition and the protein levels of collagens I and III. The intervention groups (EI and CI groups) showed higher levels of p-Nrf2/Nrf2 and HO-1 than the NR group (P < 0.05). Moreover, the EI group exhibited higher levels of p-PKA/PKA, p-Nrf2/Nrf2, and HO-1 than the CI group (P < 0.05). However, no significant difference was found in the A2AR levels among the five groups (P > 0.05). ESWT may activate A2AR, leading to the phosphorylation of PKA. Subsequently, Nrf2 may be activated, resulting in the upregulation of HO-1, which then reduces collagen deposition and alleviates immobilization-induced joint capsule fibrosis.

NLRP3/IL-1ß induced myeloid-derived suppressor cells recruitment and PD-L1 upregulation promotes oxaliplatin resistance of hepatocellular carcinoma.

Oxaliplatin is commonly used as the first-line chemotherapeutic agent for advanced hepatocellular carcinoma (HCC). Unfortunately, the acquired resistance, limits the effectiveness of oxaliplatin and the underlying mechanisms remain unknown. Therefore, we explored the role of NOD-like receptor protein 3 (NLRP3)/IL-1ß in mediating oxaliplatin resistance in HCC. We observed that NLRP3/IL-1ß expression was much higher in oxaliplatin-resistant HCC cells. To further understand its impact on drug resistance, we knocked down NLRP3 and observed that it sensitized HCC cells to the growth-inhibitory effects of oxaliplatin and induced cell apoptosis. NLRP3/IL-1ß overexpressing tumor cells also attracted polymorphonuclear myeloid-derived suppressor cells. Using mouse models, we demonstrated that NLRP3/IL-1ß inhibition by short hairpin RNA or MCC950 effectively overcame oxaliplatin resistance. Furthermore, NLRP3/IL-1ß inhibition resulted in reduced expression of PD-L1. We also found that PD-L1 antibody combined with NLRP3/IL-1ß blockade displayed significant antitumor effect in HCC. Overall, our study provides compelling evidence supporting the essential role of NLRP3/IL-1ß in conferring resistance to oxaliplatin and reshaping the immunosuppressive microenvironment in HCC. Targeting NLRP3/IL-1ß presents a potential therapeutic target for overcoming oxaliplatin resistance and reshaping microenvironment of HCC.

Gas7 attenuates hepatocellular carcinoma progression and chemoresistance through the PI3K/Akt signaling pathway.

Growth arrest-specific gene 7 (Gas7) was involved in various cellular functions, although its specific roles and molecular mechanisms in hepatocellular carcinoma (HCC) remained unclear. So the current study was to investigate the role of Gas7 in HCC. Our findings revealed that Gas7 was downregulated in various HCC cell lines and low Gas7 expression was associated with decreased overall survival in patients with HCC. Additionally, our functional assays showed that Gas7 inhibited cell proliferation and migration, induced cell cycle arrest, apoptosis, and autophagy, and enhanced oxaliplatin sensitivity by inhibiting the PI3K/Akt signaling pathway. We also observed that transcription factorSp1 was responsible for inhibiting Gas7. These findings provide insights into the role and elucidated a potential mechanism of Gas7 in HCC progression and metastasis. It was also observed that the Sp1/Gas7/PI3K/Akt axis was critical for malignant phenotype and oxaliplatin sensitivity in HCC. Therefore, Gas7 can be considered as a prognostic predictor and therapeutic target for HCC.

LIPUS Alleviates Knee Joint Capsule Fibrosis in Rabbits by Regulating SOD/ROS Dynamics and Inhibiting the TGF-ß1/Smad Signaling Pathway.

OBJECTIVE: The aim of the work described here was to investigate the efficacy and potential mechanisms of low-intensity pulsed ultrasound (LIPUS) for the treatment of arthrogenic contracture induced by immobilization in rabbits. METHODS: The left knee joint of rabbits was immobilized for 6 wk to establish the model of extending knee joint contracture. The rabbits were divided into a control group (C), a group immobilized for 6 wk (IM-6w), a group remobilized for 1 wk (RM-1w), a group subjected to LIPUS intervention for 1 wk (LIPUS-1w), a group remobilized for 2 wk (RM-2w) and a group subjected to LIPUS intervention for 2 wk (LIPUS-2w). The degrees of arthrogenic contracture and joint capsule fibrosis were assessed, as were the levels of reactive oxygen species (ROS) and the activation status of the TGF-ß1/Smad signaling pathway in the joint capsule. RESULTS: After immobilization for 6 wk, the degrees of arthrogenic contracture and joint capsule fibrosis increased. The ROS level increased, as evidenced by an increase in malondialdehyde content and a decrease in superoxide dismutase content. In addition, the TGF-ß1/Smad signaling pathway was significantly activated. The degrees of knee joint contracture increased in the first week after remobilization and decreased in the second week. Furthermore, joint capsule fibrosis continued to develop during the 2 wk of remobilization, and the ROS level increased, while the TGF-ß1/Smad signaling pathway was significantly activated. LIPUS effectively reduced the level of ROS in the joint capsule, which further inhibited activation of the TGF-ß1/Smad signaling pathway, thereby improving joint capsule fibrosis and reducing arthrogenic contracture. CONCLUSION: The high ROS levels and overactivation of the TGF-ß1/Smad signaling pathway may be reasons why immobilization induces knee joint capsule fibrosis. LIPUS can alleviate the degree of knee joint capsule fibrosis induced by immobilization by inhibiting the production of ROS and the activation of the TGF-ß1/Smad signaling pathway.

Formation process of extension knee joint contracture following external immobilization in rats.

BACKGROUND: Current research lacks a model of knee extension contracture in rats. AIM: To elucidate the formation process of knee extension contracture. METHODS: We developed a rat model using an aluminum external fixator. Sixty male Sprague-Dawley rats with mature bones were divided into the control group (n = 6) and groups that had the left knee immobilized with an aluminum external fixator for 1, 2, and 3 d, and 1, 2, 3, 4, 6, and 8 wk (n = 6 in each group). The passive extension range of motion, histology, and expression of fibrosis-related proteins were compared between the control group and the immobilization groups. RESULTS: Myogenic contracture progressed very quickly during the initial 2 wk of immobilization. After 2 wk, the contracture gradually changed from myogenic to arthrogenic. The arthrogenic contracture progressed slowly during the 1st week, rapidly progressed until the 3rd week, and then showed a steady progression until the 4rd week. Histological analyses confirmed that the anterior joint capsule of the extended fixed knee became increasingly thicker over time. Correspondingly, the level of transforming growth factor beta 1 (TGF-ß1) and phosphorylated mothers against decapentaplegic homolog 2 (p-Smad2) in the anterior joint capsule also increased with the immobilization time. Over time, the cross-sectional area of muscle fibers gradually decreased, while the amount of intermuscular collagen and TGF-ß1, p-Smad2, and p-Smad3 was increased. Unexpectedly, the amount of intermuscular collagen and TGF-ß1, p-Smad2, and p-Smad3 was decreased during the late stage of immobilization (6-8 wk). The myogenic contracture was stabilized after 2 wk of immobilization, whereas the arthrogenic contracture was stabilized after 3 wk of immobilization and completely stable in 4 wk. CONCLUSION: This rat model may be a useful tool to study the etiology of joint contracture and establish therapeutic approaches.

The worsening of skeletal muscle atrophy induced by immobilization at the early stage of remobilization correlates with BNIP3-dependent mitophagy.

BACKGROUND: Recent studies have shown that immobilization enhances reactive oxygen species (ROS) production and mitophagy activity in atrophic skeletal muscle. However, there are relatively few studies examining the biological changes and underlying mechanisms of skeletal muscle during remobilization. In this study, we aimed to investigate the effects of remobilization on skeletal muscle and explore the role of BNIP3-dependent mitophagy in this process. METHODS: Thirty rats were randomly divided into six groups based on immobilization and remobilization time: control (C), immobilization for two weeks (I-2w), and remobilization for one day (R-1d), three days (R-3d), seven days (R-7d), and two weeks (R-2w). At the end of the experimental period, the rectus femoris muscles were removed and weighed, and the measurements were expressed as the ratio of muscle wet weight to body weight (MWW/BW). Sirius Red staining was performed to calculate the values of cross-sectional area (CSA) of rectus femoris. Oxidative fluorescent dihydroethidium was used to evaluate the production of ROS, and the levels of superoxide dismutase (SOD) were also detected. The morphological changes of mitochondria and the formation of mitophagosomes in rectus femoris were examined and evaluated by transmission electron microscope. Immunofluorescence was employed to detect the co-localization of BNIP3 and LC3B, while Western blot analysis was performed to quantify the levels of proteins associated with mitophagy and mitochondrial biogenesis. The total ATP content of the rectus femoris was determined to assess mitochondrial function. RESULTS: Within the first three days of remobilization, the rats demonstrated decreased MWW/BW, CSA, and ATP concentration, along with increased ROS production and HIF-1α protein levels in the rectus femoris. Results also indicated that remobilization triggered BNIP3-dependent mitophagy, supported by the accumulation of mitophagosomes, the degradation of mitochondrial proteins (including HSP60 and COX IV), the elevation of BNIP3-dependent mitophagy protein markers (including BNIP3, LC3B-II/LC3B-I, and Beclin-1), and the accumulation of puncta representing co-localization of BNIP3 with LC3B. Additionally, PGC-1α, which is involved in the regulation of mitochondrial biogenesis, was upregulated within the first seven days of remobilization to counteract this adverse effect. CONCLUSION: Our findings suggested that BNIP3-denpendent mitophagy was sustained activated at the early stages of remobilization, and it might contribute to the worsening of skeletal muscle atrophy.

The effect of extracorporeal shock wave on joint capsule fibrosis in rats with knee extension contracture: a preliminary study.

The purpose of this study was to observe the therapeutic effect of extracorporeal shock wave (ESW) on extensional joint contracture of knee joint in rats and its mechanism on articular capsule fibrosis. Thirty-two SD rats were randomly divided into blank control, immobilization, natural recovery, and ESW intervention groups. Except for the control group, the left knee joints of other rats were fixed with external fixation brace for 4 weeks when they were fully extended to form joint contracture. The effect of intervention was assessed by evaluating joint contracture, total cell count and collagen deposition in joint capsule, and protein expression levels of TGF-ß1, p-Smad2/3, Smad2/3, p-JNK, JNK, I and III collagen in joint capsule. ESW can effectively reduce arthrogenic contracture, improve the histopathological changes of anterior joint capsule, inhibit the high expression of target protein and the excessive activation of TGF-ß1/Smad2/3/JNK signal pathway. Inhibition of excessive activation of TGF-ß1/Smad2/3/JNK pathway may be one of the potential molecular mechanisms by which extracorporeal shock wave can play a role.

Effect of Electrical Stimulation on Disuse Muscular Atrophy Induced by Immobilization: Correlation With Upregulation of PERK Signal and Parkin-Mediated Mitophagy.

OBJECTIVES: The aims of the study are to investigate the effect of electrical stimulation on disuse muscular atrophy induced by immobilization (IM) and to explore the role of PERK signal and Parkin-dependent mitophagy in this process. DESIGN: In the first subexperiment, 24 rabbits were divided into four groups, which underwent different periods of IM. In the second subexperiment, 24 rabbits were divided into four groups on average in accordance with different kinds of interventions. To test the time-dependent changes of rectus femoris after IM, and to evaluate the effect of electrical stimulation, the wet weights, cross-sectional area and fat deposition of rectus femoris were assessed in this study, along with the protein levels of atrogin-1, p-PERK, Parkin, and COXIV. RESULTS: The wet weights and cross-sectional area decreased, and the fat deposition increased in rectus femoris after IM, along with the elevated protein levels of atrogin-1, p-PERK, Parkin, and decreased protein levels of COXIV. The above histomorphological and molecular changes can be partially ameliorated by electrical stimulation. CONCLUSIONS: Immobilization of unilateral lower limb could induce rectus femoris atrophy, which can be partially rectified by electrical stimulation. PERK signal and Parkin-mediated mitophagy may be the mechanisms by which electrical stimulation can play a significant role.

Possible mechanism of static progressive stretching combined with extracorporeal shock wave therapy in reducing knee joint contracture in rats based on MAPK/ERK pathway.

The study aimed to observe the therapeutic effect of static progressive stretching (SPS) combined with extracorporeal shock wave therapy (ESWT) on extension knee joint contracture in rats and the effect on the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway in the development of joint capsule fibrosis. Thirty-six Sprague Dawley rats were randomly divided into blank control group, immobilization model group, natural recovery group, ESWT intervention group, SPS intervention group, and SPS combined with ESWT intervention group. The left knee joints of the rats, except for the control group, were fixed with an external fixation brace for four weeks at full extension to form joint contractures. The therapeutic effect of each intervention was assessed by evaluating total and arthrogenic contracture, the number of total cells and collagen deposition in the anterior joint capsule, the protein levels of TGF-ß1, FGF-2, and ERK2 in the anterior joint capsule, the mean optical density of upstream RAS and downstream ERK2 positive expression in the MAPK/ERK pathway. SPS in combination with ESWT was more effective in relieving joint contracture, improving the histopathological changes in the anterior joint capsule, and suppressing the high expression of target proteins and the overactivated MAPK/ERK pathway. The overactivated MAPK/ERK pathway was involved in the formation of extension knee joint contracture in rats. SPS in combination with ESWT was effective in relieving joint contracture and fibrosis of joint capsule. Moreover, the inhibition of the overactivated MAPK/ERK pathway may be the potential molecular mechanism for its therapeutic effect.