Dexamethasone Protects Against Tourniquet-Induced Acute Ischemia-Reperfusion Injury in Mouse Hindlimb

Detecting viscosity changes in the limb ischemia-reperfusion in mice with a near-infrared fluorescence probe

BACKGROUND

Limb ischemia-reperfusion is a common phenomenon in clinical surgery, which disrupts the balanced physiological response process and ultimately leads to changes in intracellular viscosity. Intracellular viscosity is an important microenvironmental parameter that affects the normal function of organisms, and its level is closely related to many diseases. In addition, oxidative stress in the lower limbs can impair body function, and changes in pressure can lead to changes in the viscosity of limb tissues. Therefore, it is necessary to develop effective tools to detect changes in intracellular viscosity and visualize the progression of hind limb ischemia-reperfusion injury.

RESULTS

In order to solve this problem, a near infrared viscometry sensitive fluorescence probe (PH-XQ) with long emission wavelength and stable luminescence performance was designed and synthesized by using oxanthracene derivatives and malononitrile. The fluorescence probe (PH-XQ) has excellent selectivity, high sensitivity, low toxicity, high biocompatibility and excellent detection performance. The fluorescence intensity of the PH-XQ probe at 667 nm is highly sensitive to the change of viscosity. With the increase of viscosity, the fluorescence intensity of probe PH-XQ was significantly enhanced, and the fluorescence enhancement ratio was about 14-fold. In addition, PH-XQ can detect not only changes in viscosity between normal cells and drug-induced inflammatory cells, but also changes in the viscosity of the hind limbs of normal mice and mice after ischemia reperfusion.

SIGNIFICANCE

In particular, we are the first to successfully detect changes in handlimb viscosity after ischemia-reperfusion in mice using a probe. This study clearly elucidates changes in viscosity during ischemia-reperfusion of mouse limbs, providing favorable support for the relationship between viscosity and related diseases, and further providing a potential tool for the diagnosis of viscosity-related diseases.

Carbon Dot Nanozyme Ameliorating Ischemia-Reperfusion-Induced Muscle Injury by Antioxidation and Downregulating iNOS/COX-2 Pathway

Skeletal muscle ischemia-reperfusion (IR) injury is a prevalent type of muscle injury caused by events, such as trauma, arterial embolism, and primary thrombosis. The development of an IR injury is associated with oxidative stress and an excessive inflammatory response. Nanozymes, which have exceptional free radical scavenging activities, have gained significant attention for treating oxidative stress. This study demonstrates that carbon dot (C-dot) nanozymes possess superoxide dismutase (SOD)-like activity and can act as free radical scavengers. The carbon dot nanozymes are presented to mitigate inflammation by downregulating the iNOS/COX-2 pathway and scavenging reactive oxygen-nitrogen species to reduce oxidative stress, thereby suppressing inflammation. In the IR injury of skeletal muscle mice, we demonstrate that C-dots can effectively reduce inflammatory cytokines and tissue edema in skeletal muscle following IR injury in the limb. These findings suggest that C-dots have potential as a therapeutic approach for IR injury of skeletal muscle with negligible systemic toxicity. This offers a promising strategy for clinical intervention.

Cancer-associated muscle weakness - From triggers to molecular mechanisms

Skeletal muscle weakness is a debilitating consequence of many malignancies. Muscle weakness has a negative impact on both patient wellbeing and outcome in a range of cancer types and can be the result of loss of muscle mass (i.e. muscle atrophy, cachexia) and occur independently of muscle atrophy or cachexia. There are multiple cancer specific triggers that can initiate the progression of muscle weakness, including the malignancy itself and the tumour environment, as well as chemotherapy, radiotherapy and malnutrition. This can induce weakness via different routes: 1) impaired intrinsic capacity (i.e., contractile dysfunction and intramuscular impairments in excitation-contraction coupling or crossbridge cycling), 2) neuromuscular disconnection and/or 3) muscle atrophy. The mechanisms that underlie these pathways are a complex interplay of inflammation, autophagy, disrupted protein synthesis/degradation, and mitochondrial dysfunction. The current lack of therapies to treat cancer-associated muscle weakness highlight the critical need for novel interventions (both pharmacological and non-pharmacological) and mechanistic insight. Moreover, most research in the field has placed emphasis on directly improving muscle mass to improve muscle strength. However, accumulating evidence suggests that loss of muscle function precedes atrophy. This review primarily focuses on cancer-associated muscle weakness, independent of cachexia, and provides a solid background on the underlying mechanisms, methodology, current interventions, gaps in knowledge, and limitations of research in the field. Moreover, we have performed a mini-systematic review of recent research into the mechanisms behind muscle weakness in specific cancer types, along with the main pathways implicated.

Daprodustat reduces skeletal muscle ischemia-reperfusion injury in mice

PURPOSE

The purpose of the present work was to assess the specific effects and underlying mechanisms of Daprodustat (GSK1278863) on skeletal muscle injury induced by ischemia reperfusion (I/R).

METHODS

C57BL/6 mice were randomized into the skeletal muscle I/R injury (I/R), Daprodustat (GSK1278863) pretreatment and I/R (I/R + GSK) and sham operation (Sham) groups. The skeletal muscle I/R injury model was established by placing an orthodontic rubber band at the left hip joint for 3 h and releasing it for 3 h. H&E staining, wet weight/dry weight ratio assessment, TUNEL assay, ELISA, qRT-PCR and immunoblot were utilized to assess the effects of Daprodustat.

RESULTS

Daprodustat pretreatment significantly ameliorated apoptosis in skeletal muscle cells, reduced oxidative damage and suppressed inflammatory cytokines. Mechanistically, Daprodustat positively affected NF-κB signaling activation.

CONCLUSION

These data demonstrated that Daprodustat may provide a potential clinical approach for preventing or treating skeletal muscle injury induced by I/R.

The Effect of Cerium Oxide (CeO2) on Ischemia-Reperfusion Injury in Skeletal Muscle in Mice with Streptozocin-Induced Diabetes

Objective: Lower extremity ischemia-reperfusion injury (IRI) may occur with trauma-related vascular injury and various vascular diseases, during the use of a tourniquet, in temporary clamping of the aorta in aortic surgery, or following acute or bilateral acute femoral artery occlusion. Mitochondrial dysfunction and increased basal oxidative stress in diabetes may cause an increase in the effects of increased reactive oxygen species (ROS) and mitochondrial dysfunction due to IRI. It is of great importance to examine therapeutic approaches that can minimize the effects of IRI, especially for patient groups under chronic oxidative stress such as DM. Cerium oxide (CeO2) nanoparticles mimic antioxidant enzymes and act as a catalyst that scavenges ROS. In this study, it was aimed to investigate whether CeO2 has protective effects on skeletal muscles in lower extremity IRI in mice with streptozocin-induced diabetes. Methods: A total of 38 Swiss albino mice were divided into six groups as follows: control group (group C, n = 6), diabetes group (group D, n = 8), diabetes-CeO2 (group DCO, n = 8), diabetes-ischemia/reperfusion (group DIR, n = 8), and diabetes-ischemia/reperfusion-CeO2 (group DIRCO, n = 8). The DCO and DIRCO groups were given doses of CeO2 of 0.5 mg/kg intraperitoneally 30 min before the IR procedure. A 120 min ischemia-120 min reperfusion period with 100% O2 was performed. At the end of the reperfusion period, muscle tissues were removed for histopathological and biochemical examinations. Results: Total antioxidant status (TAS) levels were found to be significantly lower in group DIR compared with group D (p = 0.047 and p = 0.022, respectively). In group DIRCO, total oxidant status (TOS) levels were found to be significantly higher than in group DIR (p < 0.001). The oxidative stress index (OSI) was found to be significantly lower in group DIR compared with group DCO (p < 0.001). Paraoxanase (PON) enzyme activity was found to be significantly increased in group DIR compared with group DCO (p < 0.001). The disorganization and degeneration score for muscle cells, inflammatory cell infiltration score, and total injury score in group DIRCO were found to be significantly lower than in group DIR (p = 0.002, p = 0.034, and p = 0.001, respectively). Conclusions: Our results confirm that CeO2, with its antioxidative properties, reduces skeletal muscle damage in lower extremity IRI in diabetic mice.

Treatment for benign skin lesion in zygomatic-infraorbital region by the expanded multi-lobe cervicofacial advancement rotation flap in pediatric patients

PURPOSE

Benign skin lesions in zygomatic-infraorbital regions severely influence pediatric patients' appearance as well as mental health. Treatments are difficult for the high requirements of patients' guardians in both function and aesthetics. The present study aims to introduce a surgical method, Expanded Multi-Lobe Cervicofacial Flap, which combines the advantages of the classical cervicofacial advancement rotation flap and the tissue expansion technique.

METHODS

A total of 21 pediatric patients were enrolled. The treatment process included 2 stages: implantation of the skin tissue expander and flap transfer. The excessive skin created by tissue expansion extended the coverage area of the multi-lobe flap.

RESULTS

In this retrospective study, follow-up periods were all more than 12 months (20.8 ± 6.7). In the last follow-ups, the flaps were all in good condition, and No facial organ displacement was observed. The patients' guardians were satisfied with the outcomes.

CONCLUSIONS

Using the expanded multi-lobe cervicofacial flap for the zygomatic-infraorbital benign skin lesion repair is effective, and this method is especially applicable to the pediatric population.

Explore novel molecular mechanisms of FNDC5 in ischemia-reperfusion (I/R) injury by analyzing transcriptome changes in mouse model of skeletal muscle I/R injury with FNDC5 knockout

BACKGROUND

Irisin, a myokine derived from proteolytic cleavage of the fibronectin type III domain-containing protein 5 (FNDC5) protein, is crucial in protecting tissues and organs from ischemia-reperfusion (I/R) injury. However, the underlying mechanism of its action remains elusive. In this study, we investigated the expression patterns of genes associated with FNDC5 knockout to gain insights into its molecular functions.

METHODS

We employed a mouse model of skeletal muscle I/R injury with FNDC5 knockout to examine the transcriptional profiles using RNA sequencing. Differentially expressed genes (DEGs) were identified and subjected to further analyses, including gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, protein-protein interaction (PPI) network analysis, and miRNA-transcription factor network analysis. The bioinformatics findings were validated using qRT-PCR and Western blotting.

RESULTS

Comparative analysis of skeletal muscle transcriptomes between wild-type (WT; C57BL/6), WT-I/R, FNDC5 knockout (KO), and KO-I/R mice highlighted the significance of FNDC5 in both physiological conditions and I/R injury. Through PPI network analysis, we identified seven key genes (Col6a2, Acta2, Col4a5, Fap, Enpep, Mmp11, and Fosl1), which facilitated the construction of a TF-hub genes-miRNA regulatory network. Additionally, our results suggested that the PI3K-Akt pathway is predominantly involved in FNDC5 deletion-mediated I/R injury in skeletal muscle. Animal studies revealed reduced FNDC5 expression in skeletal muscle following I/R injury, and the gastrocnemius muscle with FNDC5 knockout exhibited larger infarct size and more severe tissue damage after I/R. Moreover, Western blot analysis confirmed the upregulation of Col6a2, Enpep, and Mmp11 protein levels following I/R, particularly in the KO-I/R group. Furthermore, FNDC5 deletion inhibited the PI3K-Akt signaling pathway.

CONCLUSION

This study demonstrates that FNDC5 deletion exacerbates skeletal muscle I/R injury, potentially involving the upregulation of Col6a2, Enpep, and Mmp11. Additionally, the findings suggest the involvement of the PI3K-Akt pathway in FNDC5 deletion-mediated skeletal muscle I/R injury, providing novel insights into the molecular mechanisms underlying FNDC5's role in this pathological process.

A clinically-relevant mouse model that displays hemorrhage exacerbates tourniquet-induced acute kidney injury

Hemorrhage is a leading cause of death in trauma. Tourniquets are effective at controlling extremity hemorrhage and have saved lives. However, tourniquets can cause ischemia reperfusion injury of limbs, leading to systemic inflammation and other adverse effects, which results in secondary damage to the kidney, lung, and liver. A clinically relevant animal model is critical to understanding the pathophysiology of this process and developing therapeutic interventions. Despite the importance of animal models, tourniquet-induced lower limb ischemia/reperfusion (TILLIR) models to date lack a hemorrhage component. We sought to develop a new TILLIR model that included hemorrhage and analyze the subsequent impact on kidney, lung and liver injuries. Four groups of mice were examined: group 1) control, group 2) hemorrhage, group 3) tourniquet application, and group 4) hemorrhage and tourniquet application. The hemorrhagic injury consisted of the removal of 15% of blood volume through the submandibular vein. The tourniquet injury consisted of orthodontic rubber bands applied to the inguinal area bilaterally for 80 min. Mice were then placed in metabolic cages individually for 22 h to collect urine. Hemorrhage alone did not significantly affect transcutaneous glomerular filtration rate (tGFR), blood urea nitrogen (BUN) or urinary kidney injury molecule-1 (KIM-1) levels. Without hemorrhage, TILLIR decreased tGFR by 46%, increased BUN by 162%, and increased KIM-1 by 27% (p < 0.05 for all). With hemorrhage, TILLIR decreased the tGFR by 72%, increased BUN by 395%, and increased urinary KIM-1 by 37% (p < 0.05 for all). These differences were statistically significant (p < 0.05). While hemorrhage had no significant effect on TILLIR-induced renal tubular degeneration and necrosis, it significantly increased TILLIR-induced lung total injury scores and congestion, and fatty liver. In conclusion, hemorrhage exacerbates TILLIR-induced acute kidney injury and structural damage in the lung and liver.

Severe muscle damage after a short period of ischemia and reperfusion in an animal model

BACKGROUND

Skeletal muscle ischemia-reperfusion injuries result in a loss of contractile function, leading to limb disability or amputation. Ischemia causes hypoxia and cellular energy failure, which is aggravated by reperfusion due to the inflammatory response and oxidative stress. The consequences of the injury vary according to the duration of the period of ischemia and reperfusion. Therefore, the present work aims to evaluate ischemia-reperfusion injuries induced in the skeletal muscles of Wistar rats submitted to 3 different application periods based on morphological and biochemical parameters.

METHODS

For this, a tourniquet was applied to the root of the animals' hind limbs, occluding arterial and venous blood flow, and it was followed by reperfusion-the removal of the tourniquet. The groups were: control (without tourniquet); I30'/R60' (30 minutes of ischemia and 1 hour of reperfusion); I120'/R120' (2 hours and 2 hours); and I180'/R180' (3 hours and 3 hours).

RESULTS

All ischemia-reperfusion groups showed characteristics of muscle injury. Microscopic analyses of the extensor digitorum longus, soleus, tibialis anterior, and gastrocnemius muscles showed a significant increase in the number of injured muscle fibers in the ischemia-reperfusion groups compared to the control group. There were also significant differences between the ischemia-reperfusion groups in all muscles, showing a progressive increase in the degree of injury. The quantification of the number of injured muscle fibers between the muscles revealed that at I30'/R60', the soleus muscles had a higher number of injuries in relation to the other muscles, with statistical significance. In the I120'/R120' group, the gastrocnemius muscles presented a significantly greater number of injured fibers. There were no significant differences in the I180'/R180' group. The serum levels of creatine kinase in the I180'/R180' group were significantly higher than in the control and I30'/R60' groups.

CONCLUSIONS

Therefore, it was evident that the 3 ischemia-reperfusion models used were capable of causing cell damage, with these findings being more pronounced in the I180'/R180' group.

Systemic glucose-insulin-potassium reduces skeletal muscle injury, kidney injury, and pain in a murine ischaemia-reperfusion model

Glucose-insulin-potassium (GIK) is protective following cardiac myocyte ischaemia-reperfusion (IR) injury, however the role of GIK in protecting skeletal muscle from IR injury has not been evaluated. Given the similar mechanisms by which cardiac and skeletal muscle sustain an IR injury, we hypothesized that GIK would similarly protect skeletal muscle viability. A total of 20 C57BL/6 male mice (10 control, 10 GIK) sustained a hindlimb IR injury using a 2.5-hour rubber band tourniquet. Immediately prior to tourniquet placement, a subcutaneous osmotic pump was placed which infused control mice with saline (0.9% sodium chloride) and treated mice with GIK (40% glucose, 50 U/l insulin, 80 mEq/L KCl, pH 4.5) at a rate of 16 µl/hr for 26.5 hours. At 24 hours following tourniquet removal, bilateral (tourniqueted and non-tourniqueted) gastrocnemius muscles were triphenyltetrazolium chloride (TTC)-stained to quantify percentage muscle viability. Bilateral peroneal muscles were used for gene expression analysis, serum creatinine and creatine kinase activity were measured, and a validated murine ethogram was used to quantify pain before euthanasia. GIK treatment resulted in a significant protection of skeletal muscle with increased viability (GIK 22.07% (SD 15.48%)) compared to saline control (control 3.14% (SD 3.29%)) (p = 0.005). Additionally, GIK led to a statistically significant reduction in gene expression markers of cell death (CASP3, p < 0.001) and inflammation (NOS2, p < 0.001; IGF1, p = 0.007; IL-1β, p = 0.002; TNFα, p = 0.012), and a significant reduction in serum creatine kinase (p = 0.004) and creatinine (p < 0.001). GIK led to a significant reduction in IR-related pain (p = 0.030). Systemic GIK infusion during and after limb ischaemia protects murine skeletal muscle from cell death, kidneys from reperfusion metabolites, and reduces pain by reducing post-ischaemic inflammation.

Inflammation balance in skeletal muscle damage and repair

Responding to tissue injury, skeletal muscles undergo the tissue destruction and reconstruction accompanied with inflammation. The immune system recognizes the molecules released from or exposed on the damaged tissue. In the local minor tissue damage, tissue-resident macrophages sequester pro-inflammatory debris to prevent initiation of inflammation. In most cases of the skeletal muscle injury, however, a cascade of inflammation will be initiated through activation of local macrophages and mast cells and recruitment of immune cells from blood circulation to the injured site by recongnization of damage-associated molecular patterns (DAMPs) and activated complement system. During the inflammation, macrophages and neutrophils scavenge the tissue debris to release inflammatory cytokines and the latter stimulates myoblast fusion and vascularization to promote injured muscle repair. On the other hand, an abundance of released inflammatory cytokines and chemokines causes the profound hyper-inflammation and mobilization of immune cells to trigger a vicious cycle and lead to the cytokine storm. The cytokine storm results in the elevation of cytolytic and cytotoxic molecules and reactive oxygen species (ROS) in the damaged muscle to aggravates the tissue injury, including the healthy bystander tissue. Severe inflammation in the skeletal muscle can lead to rhabdomyolysis and cause sepsis-like systemic inflammation response syndrome (SIRS) and remote organ damage. Therefore, understanding more details on the involvement of inflammatory factors and immune cells in the skeletal muscle damage and repair can provide the new precise therapeutic strategies, including attenuation of the muscle damage and promotion of the muscle repair.

Sarcopenia phenotype and impaired muscle function in male mice with fast-twitch muscle-specific knockout of the androgen receptor

Sarcopenia is distinct from normal muscle atrophy in that it is closely related to a shift in the muscle fiber type. Deficiency of the anabolic action of androgen on skeletal muscles is associated with sarcopenia; however, the function of the androgen receptor (AR) pathway in sarcopenia remains poorly understood. We generated a mouse model (fast-twitch muscle-specific AR knockout [fmARKO] mice) in which the AR was selectively deleted in the fast-twitch muscle fibers. In young male mice, the deletion caused no change in muscle mass, but it reduced muscle strength and fatigue resistance and induced a shift in the soleus muscles from fast-twitch fibers to slow-twitch fibers (14% increase, P = 0.02). After middle age, with the control mice, the male fmARKO mice showed much less muscle function, accompanied by lower hindlimb muscle mass; this phenotype was similar to the progression of sarcopenia. The bone mineral density of the femur was significantly reduced in the fmARKO mice, indicating possible osteosarcopenia. Microarray and gene ontology analyses revealed that in male fmARKO mice, there was downregulation of polyamine biosynthesis-related geneswhich was confirmed by liquid chromatography-tandem mass spectrometry assay and the primary cultured myofibers. None of the AR deletion-related phenotypes were observed in female fmARKO mice. Our findings showed that the AR pathway had essential muscle type- and sex-specific roles in the differentiation toward fast-twitch fibers and in the maintenance of muscle composition and function. The AR in fast-twitch muscles was the dominant regulator of muscle fiber-type composition and muscle function, including the muscle-bone relationship.

Effect of dexmedetomidine on tourniquet-induced skeletal muscle injury

OBJECTIVE

The aim of this study was to investigate whether dexmedetomidine could reduce tourniquet-induced skeletal muscle injury.

METHODS

C57BL6 male mice were randomly assigned to sham, ischemia/reperfusion, and dexmedetomidine groups. Mice in the ischemia/reperfusion and dexmedetomidine groups received normal saline solution and dexmedetomidine intraperitoneally, respectively. The sham group underwent the same procedure as the ischemia/reperfusion group, with the exception of tourniquet application. Subsequently, the ultrastructure of the gastrocnemius muscle was observed, and its contractile force was examined. In addition, Toll-like receptor 4 and nuclear factor-κB expression within muscles was detected by Western blot.

RESULTS

Dexmedetomidine alleviated myocyte damage and increased the contractility of skeletal muscles. Moreover, dexmedetomidine significantly inhibited the expression of Toll-like receptor 4/nuclear factor-κB in the gastrocnemius muscle.

CONCLUSION

Taken together, these results demonstrate that dexmedetomidine administration attenuated tourniquet-induced structural and functional impairment of the skeletal muscle, partly through inactivation of the Toll-like receptor 4/nuclear factor-κB pathway.

Clinical efficacy and feasibility of laser correction technology with an ordinary laser pen and surgical instrument box in open-wedge high tibial osteotomy

Background

The clinical outcomes of open-wedge high tibial osteotomy (OWHTO) for medial knee osteoarthritis primarily depend on the corrective precision. The present study aimed to determine the efficacy and feasibility of laser correction technology with an ordinary laser pen and surgical instrument box.

Methods

This prospective and randomized trial included 71 patients randomly divided into laser (n = 36) and traditional groups (n = 35). In the laser group, the hip centre, knee (Fujisawa point), and ankle centre were located preoperatively using the surgical instrument box lid. The leg was aligned with an ordinary laser pen. In the traditional group, the lower limb alignment was corrected by a metal cable. Radiation exposure, operative time, and rate of outliers (lower limb force line does not pass through 62–66% of the lateral tibial plateau) were evaluated. The visual analogue scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were recorded. After 24 months, the femoral tibial angle (FTA), medial proximal tibial angle (MPTA), and posterior slope angle (PSA), were recorded. The Kaplan-Meier method was used to evaluate the survival time of affected knees, and postoperative complications were recorded.

Results

The radiation exposure, operative time and rate of outliers were lower in the laser correction group (P < 0.05). Six months postoperatively, the VAS and WOMAC scores were significantly improved in both groups (P < 0.001). At 24 months, the FTA, MPTA, and PSA were corrected in both groups (P < 0.001). There were no differences in the postoperative knee survival time from OWHTO to knee arthroplasty between the groups or postoperative complications (P = 0.53; P = 0.61).

Conclusions

Laser correction technology can effectively reduce radiation exposure, the operative time, and the rate of outliers (trial identification number (retrospectively registered): ChiCTR2200060480; date of register: 03/06/2022).

Dl-3-n-Butylphthalide (NBP) Mitigates Muscular Injury Induced by Limb Ischemia/Reperfusion in Mice through the HMGB1/TLR4/NF-κB Pathway

Objective

Limb ischemia/reperfusion (I/R) injury is a clinical syndrome associated with severe damages to skeletal muscles and other fatal outcomes. Oxidative stress and inflammatory response play vital roles in the development of limb I/R injury. Existing evidence further indicates that Dl-3-n-butylphthalide (NBP) has anti-inflammatory and antioxidative properties. However, whether NBP can protect skeletal muscles from limb I/R injury and the mechanism in mediating the action of NBP treatment still remain to be investigated, which are the focuses of the current study.

Methods

The model of limb I/R injury was established and H&E staining was adopted to assess the pathological changes in skeletal muscles following limb I/R injury. Additionally, the W/D ratio of muscle tissue was also measured. ELISA and biochemical tests were carried out to measure the levels of inflammatory cytokines and oxidative stress in mouse models of limb I/R injury. Moreover, the levels of the HMGB1/TLR4/NF-κB pathway-related proteins were also determined using immunohistochemistry and immunoblotting.

Results

It was established that NBP treatment alleviated I/R-induced pathological changes in muscular tissue of mice, accompanied by lower W/D ratio of skeletal muscular tissue. Meanwhile, the limb I/R-induced inflammation and oxidative stress in skeletal muscles of mice were also inhibited by NBP. Mechanistic study indicated that the alleviatory effect of NBP was ascribed to inactivation of the HMGB1/TLR4/NF-κB pathway.

Conclusions

Our findings highlighted the potential of NBP as a novel strategy for limb I/R-driven muscle tissue damages by suppressing inflammatory response and oxidative stress via the HMGB1/TLR4/NF-κB pathway.

Jujuboside A Exhibits an Antiepileptogenic Effect in the Rat Model via Protection against Traumatic Epilepsy-Induced Oxidative Stress and Inflammatory Responses

Traumatic brain injuries (TBI) are the greatest source of death in trauma, and post-traumatic epilepsy (PTE) is one of the common complications of TBI. Oxidative stress and inflammatory responses play an important role in the process of PTE. Many studies have shown that Jujuboside A has powerful antioxidant and anti-inflammatory properties. However, it is not known whether Jujuboside A has an anti-epileptic effect. The influences of Jujuboside A in the experimental FeCl3-induced model of PTE were tested by estimating the grade of seizures and performing behavioral tests. Following that, we detected oxidative stress indicators and inflammatory factors. Additionally, western blotting was used to test the protein levels of signaling molecules in MAPK pathways. In this study, Jujuboside A was found to have improved the recognition deficiency and epilepsy syndromes in the experimental rat model. Moreover, oxidative stress and inflammatory responses induced by FeCl3 injection were relieved by Jujuboside A. In addition, Jujuboside A was found to be capable of reducing the increased expression of p-P38 and p-ERK1/2 caused by iron ions. Collectively, our results demonstrated that Jujuboside A exhibits an antiepileptogenic effect by alleviating oxidative stress and inflammatory responses via the p38 and ERK1/2 pathways.

Resolution of Inflammation after Skeletal Muscle Ischemia-Reperfusion Injury: A Focus on the Lipid Mediators Lipoxins, Resolvins, Protectins and Maresins

Skeletal muscle ischemia reperfusion is very frequent in humans and results not only in muscle destruction but also in multi-organ failure and death via systemic effects related to inflammation and oxidative stress. In addition to overabundance of pro-inflammatory stimuli, excessive and uncontrolled inflammation can also result from defects in resolution signaling. Importantly, the resolution of inflammation is an active process also based on specific lipid mediators including lipoxins, resolvins and maresins that orchestrate the potential return to tissue homeostasis. Thus, lipid mediators have received growing attention since they dampen deleterious effects related to ischemia–reperfusion. For instance, the treatment of skeletal muscles with resolvins prior to ischemia decreases polymorphonuclear leukocyte (PMN) infiltration. Additionally, remote alterations in lungs or kidneys are reduced when enhancing lipid mediators’ functions. Accordingly, lipoxins prevented oxidative-stress-mediated tissue injuries, macrophage polarization was modified and in mice lacking DRV2 receptors, ischemia/reperfusion resulted in excessive leukocyte accumulation. In this review, we first aimed to describe the inflammatory response during ischemia and reperfusion in skeletal muscle and then discuss recent discoveries in resolution pathways. We focused on the role of specialized pro-resolving mediators (SPMs) derived from polyunsaturated fatty acids (PUFAs) and their potential therapeutic applications.

Impact of Dexamethasone Preconditioning on Prevention of Development of Cognitive Impairment following Acute Inflammation

To assess the preventive role of dexamethasone (Dex) in the development of neuroinflammation and concomitant neurocognitive disorders following acute inflammation. C57BL6 mice were fallen into the sham group, ischemia-reperfusion (I/R) group, and I/R + Dex group randomly. In the end, behavioral alterations were assessed with the Morris water maze (MWM) test, passive avoidance test (PAT), and open field test (OFT). The serum levels of IL-1β and TNF-α were detected by ELISA. Immunofluorescence was adopted to observe the NF-kB expression in the hippocampus. In addition, TLR4, NF-kB, CD68, and CD206 were examined by Western blot. The cognitive ability of mice can be impaired by tourniquet-induced acute inflammation, and these changes were prevented by Dex. Compared to the I/R group, Dex pretreatment could decrease levels of IL-1β and TNF-α proteins in serum. Besides, Dex preconditioning significantly decreased the utterance of NF-kB immunoreactive cells and TLR4, NF-kB, and CD68 overexpression in the hippocampus. Dex partly through inhibiting microglia transformation to the M1 polarization state and inactivating the TLR4/NF-kB pathway attenuates the cognitive disorders in mice.

Sulforaphane Ameliorates Limb Ischemia/Reperfusion-Induced Muscular Injury in Mice by Inhibiting Pyroptosis and Autophagy via the Nrf2-ARE Pathway

Background

Limb ischemia/reperfusion (I/R) injury, as a life-threatening syndrome, is commonly caused by skeletal muscle damage resulting from oxidative stress. Additionally, inflammation-induced pyroptosis and dysregulated autophagy are vital factors contributing to the aggravation of I/R injury. Of note, sulforaphane (SFN) is a natural antioxidant, but whether it worked in limb I/R injury and the possible mechanism behind its protection for skeletal muscle has not been clearly established.

Methods

Effects of SFN on limb I/R-injured skeletal muscle were assessed by HE staining, followed by assessment of wet weight/dry weight (W/D) ratio of muscle tissues. Next, ELISA and biochemical tests were used to measure the inflammatory cytokine production and oxidative stress. Immunofluorescent analysis and Western blot were adopted to examine the level of pyroptosis- and autophagy-related proteins in vivo. Moreover, protein levels of Nrf2-ARE pathway-related factors were also examined using Western blot.

Results

SFN treatment could protect skeletal muscle against limb I/R injury, as evidenced by diminished inflammation, pyroptosis, autophagy, and oxidative stress in skeletal muscles of mice. Further mechanistic exploration confirmed that antioxidative protection of SFN was associated with the Nrf2-ARE pathway activation.

Conclusions

SFN activates the Nrf2-ARE pathway, and thereby inhibits pyroptosis and autophagy and provides a novel therapeutic strategy for the limb I/R-induced muscle tissue damage.

Hyperbaric oxygen therapy does not alleviate tourniquet-induced acute ischemia-reperfusion injury in mouse skeletal muscles

During tourniquet application, blood flow is restricted to a limb to stop excessive limb hemorrhage in a trauma setting and to create a bloodless operating field in the surgical setting. During tourniquet-related ischemia, aerobic respiration stops, and ATP is depleted, and during subsequent reperfusion, there is an increase in reactive oxygen species (ROS) production and other endogenous substances, which leads to acute ischemia-reperfusion (IR) injuries, including tissue necrosis and skeletal muscle contractile dysfunction. Hyperbaric oxygen (HBO) therapy can increase the arterial oxygen tension in the tissues of patients with general hypoxia/anoxia, including carbon monoxide poisoning, circulatory arrest, and cerebral and myocardial ischemia. Here, we studied the protective effects of HBO pretreatment with 100% oxygen at 2.5 ATA against tourniquet/IR injury in mice. After one hour of HBO therapy with 100% oxygen at 2.5 ATA was administered to C57/BL6 mice, a rubber band was placed at the hip joint of the unilateral hindlimb to induce 3 h of ischemia and then released for 48 h of reperfusion. We analyzed gastrocnemius muscle morphology and contractile function and measured the levels of ATP and ROS accumulation in the muscles. HBO pretreatment did not improve tourniquet/IR-injured gastrocnemius muscle morphology and muscle contraction. Tourniquet/IR mice with HBO pretreatment showed no increase in ATP levels in IR tissues, but they did have a decreased amount of ROS accumulation in the muscles, compared to IR mice with no HBO pretreatment. These data suggest that one hour of HBO pretreatment with 100% oxygen at 2.5 ATA increases the antioxidant response to lower ROS accumulation but does not increase ATP levels in IR muscles and improve tourniquet/IR-injured muscle morphology and contractile function.

Therapeutic effects of masitinib on abnormal mechanoreception in a mouse model of tourniquet-induced extremity ischemia-reperfusion

Tourniquets are widely used to stop extremity hemorrhage, but their use and subsequent release can result in nerve damage and degeneration, leading to neurological deficits. Increasing evidence has suggested a pivotal role of inflammation in nerve damage and abnormal mechanoreception. In this study, we investigated the therapeutic effects of masitinib (Mas), an anti-neuroinflammatory drug, on the mechanoreception of sensory neurons in a mouse model of tourniquet-induced hind paw ischemia-reperfusion (tourniquet/IR). C57BL/6 mice were subjected to 3 h of ischemia by placing a rubber band at the ankle joint and evaluated for subsequent reperfusion injury on day 1, 3, 7, 14, and 28 based on the experiments. Treatment with Mas (28 mg/kg/day, i.p.) began on the day of IR induction and lasted for 1, 3, 7, 14, or 28 days. Tourniquet/IR caused sensory nerve denervation in the skin of paw pads and abolished the hind paw mechanoreception to mechanical stimulation during the first 3 days of reperfusion. Sensory nerves gradually reinnervated in the skin of paw pads and allodynia began to appear on day 7. The maximum reaction occurred on day 14 and was maintained throughout the study period. Treatment with Mas mitigated nerve damage and improved hind paw mechanoreception to mechanical stimulation by decreasing the production of reactive oxygen species (ROS) during the early stages of tourniquet/IR. Mas also alleviated allodynia and decreased inflammatory cytokines (IL-1β and TNFα) in the skin of paw pads from days 7-28. Our data suggest that treatment with Mas significantly ameliorated paw numbness and allodynia in mouse hind paw tourniquet/IR.

A comparison of acute mouse hindlimb injuries between tourniquet- and femoral artery ligation-induced ischemia-reperfusion

The tourniquet or femoral artery ligation is widely used to stop extremity hemorrhage or create a bloodless operating field in the combat scenario and civilian setting. However, these procedures with subsequent reperfusion also induce ischemia-reperfusion (IR) injuries. To fully evaluate animal models of limb IR injuries, we compared tourniquet- and femoral artery ligation-induced IR injuries in the hindlimb of mice. In C57/BL6 mice, 3 h of unilateral hindlimb ischemia was induced by placement of a rubber band at the hip joint or a surgical ligation of the femoral artery. The tourniquet or femoral artery ligation was then released, allowing for 24 h of reperfusion. Compared to the femoral artery ligation/IR, the tourniquet/IR induced more severe skeletal muscle damage, including muscle necrosis and interruption of muscle fibers. There was no gastrocnemius muscle contraction in tourniquet/IR, while femoral artery ligation/IR markedly weakened gastrocnemius muscle contraction. Motor nerve terminals disappeared, and endplate potentials (EPPs) were undetectable in tourniquet/IR, whereas femoral artery ligation/IR only induced mild impairment of motor nerve terminals and decreased the amplitude of EPPs. Additionally, western blot data showed that proinflammatory cytokine levels (IL-1β and TNF-α) were higher in the tourniquet/IR than that in femoral artery ligation/IR. Moreover, tourniquet/IR caused significant tissue edema and dilation of lymphatic vessels in the hindlimb, compared to femoral artery ligation/IR. The above data demonstrated that tourniquet/IR-induced acute hindlimb injuries are more severe than those induced by femoral artery ligation/IR. This suggests that future investigators should determine which hindlimb IR model (tourniquet/IR or femoral artery ligation/IR) is optimal depending on the purpose of their study.

Effects of Dexmedetomidine and Oxycodone on Neurocognitive and Inflammatory Response After Tourniquet-Induced Ischemia-Reperfusion Injury

To evaluate the effects of dexmedetomidine (Dex) and oxycodone (Oxy) on neurocognitive and inflammatory response after tourniquet-induced ischemia-reperfusion (I/R) injury. C57/BL6 mice were used to construct the mouse model of tourniquet-induced I/R injury. Mice (n = 48) were randomly divided into sham, I/R, Dex or Oxy group. Morris water maze test was performed to assess the spatial learning and memory function. The expression of NF-κB, TLR4, NR2B, M1 (CD68 and TNF-α) and M2 (CD206 and IL-10) polarization markers in mice hippocampus were detected by western blot or immunofluorescent staining. Spontaneous excitatory post-synaptic currents (sEPSCs) were recorded by electrophysiology. Dex treatment alleviated I/R-induced declines in learning and memory (p < 0.05), while Oxy had no significant effect on it. Compared with I/R group, Dex and Oxy treatment down-regulated the expression of NF-κB, TLR4, TNF-α and CD68 (all p < 0.05), while no significantly different was found in CD206 and IL-10. In addition, Dex treatment down-regulated the expression of NR2B and reduced the frequency and amplitude of sEPSCs in I/R model mice (all p < 0.05), while Oxy had no significant effect on them. Tourniquet-induced I/R could impair the neurocognitive function of mice. Dex treatment could alleviate I/R-induced neurocognitive disorder by inhibiting abnormal synaptic transmission in hippocampal neurons. Both Dex and Oxy could alleviate the inflammatory response likely by inhibiting the polarization of microglia toward M1 phenotype via TLR4/NF-κB pathway. Future studies are needed to further examine the effects of Dex on neurocognitive disorder after tourniquet-induced I/R injury and investigate the exact mechanism.

Low-molecular-weight heparin calcium attenuates the tourniquet-induced ischemia-reperfusion injury in rats

Ischemia-reperfusion injury (IRI) is a common postoperative complication of the tourniquet used surgery; low-molecular-weight heparin calcium (LMWH) is frequently used postoperatively to prevent the formation of deep venous thrombosis. However, subcutaneous hemorrhage can usually be seen in patients who underwent lower limb surgery, especially in total knee arthroplasty, the influence of LMWH on IRI remains controversial. In this experiment, we designed an animal model to observe the influence of LMWH on the skeletal muscle injury induced by tourniquets. Sprague-Dawley (SD) rats underwent either 2 h of unilateral hindlimb ischemia or anesthesia alone, at different time points of reperfusion interval, animals received either 4mg/kg LMWH or normal saline subcutaneously twice a day. The levels of inflammatory markers in serum, the expression of apoptosis proteins, as well as histological examination of skeletal muscles, were detected at 48-h reperfusion. We found that the injury of skeletal muscle and the systemic inflammatory response was less severe in LMWH-treated animals, indicating that LMWH could attenuate the tourniquet-induced IRI. In conclusion, LMWH given postoperatively after limb surgery may be clinically beneficial.

Activation of Opioid Receptors Attenuates Ischemia/Reperfusion Injury in Skeletal Muscle Induced by Tourniquet Placement

Method

Mice were randomly assigned to the sham, I/R, Oxy, and I/R with Oxy groups. Oxy was injected intraperitoneally 30 min before tourniquet placement. Morphological changes of the gastrocnemius muscle in these mice were assessed by hematoxylin-eosin (HE) staining and electron microscopy. Expression levels of TLR4, NF-κB, SIRT1, and PGC-1α in the skeletal muscles were detected by western blot. Blood TNF-α levels, gastrocnemius muscle contractile force, and ATP concentration were examined.

Results

Compared with the I/R group, Oxy pretreatment attenuated skeletal muscle damage, decreased serum TNF-α levels, and inhibited the expression levels of TLR4/NF-κB in the gastrocnemius muscle. Furthermore, Oxy treatment significantly increased serum ATP levels and the contractility of the skeletal muscles. SIRT1 and PGC-1α levels were significantly reduced in gastrocnemius muscle after I/R. Oxy pretreatment recovered these protein expression levels.

Conclusion

Tourniquet-induced acute limb I/R results in morphological and functional impairment in skeletal muscle. Pretreatment with Oxy attenuates skeletal muscle from acute I/R injury through inhibition of TLR4/NF-κB-dependent inflammatory response and protects SIRT1/PGC-1α-dependent mitochondrial function.

Quantitative evaluation of dexamethasone treatment effects in renal ischemia-reperfusion injury using contrast enhanced ultrasonography in rats

BACKGROUND

Renal ischemia-reperfusion (I/R) injury often occurs in various clinical events, and its incidence and mortality have been increasing.

OBJECTIVE

To investigate the value of contrast enhanced ultrasonography (CEUS) in the monitoring of dexamethasone in the improvement of renal I/R injury in rats.

METHODS

Eighteen healthy male Sprague-Dawley rats were randomly divided into sham-operated, I/R, and I/R surgery plus dexamethasone treatment (Dexa) groups. In the I/R group 45-minute renal ischemia with 24 h reperfusion period was monitored. Time-intensity curve (TIC)-derived parameters, which included peak value, time to peak (TP), area under the curve (AUC), and mean transit time (MTT) were compared to the blood creatinine, urea, Caspase-1, and NLRP3 levels.

RESULTS

The I/R group showed an increased peak value, prolonged TP and MTT, and greater AUC (P < 0.05). The Dexa group showed shorter TP and MTT, and smaller AUC (P < 0.05). Results show that the associations between (i) TP, AUC, and MTT and (ii) creatinine, urea, Caspase-1, and NLRP3 levels were significant (P < 0.05).

CONCLUSION

Dexamethasone can alleviate renal I/R injury in rats, which may be related to the inhibition of NLRP3 and caspase-1. CEUS can quantitatively measure this change, in which the changes in TP, AUC and MMT values have considerable reference values.

Bilobalide protects against ischemia/reperfusion-induced oxidative stress and inflammatory responses via the MAPK/NF-휅B pathways in rats

Background

Clinically, skeletal muscle ischemia/reperfusion injury is a life-threatening syndrome that is often caused by skeletal muscle damage and is characterized by oxidative stress and inflammatory responses. Bilobalide has been found to have antioxidative and anti-inflammatory effects. However, it is unclear whether bilobalide can protect skeletal muscle from ischemia/reperfusion injury.

Methods

The effects of bilobalide on ischemia/reperfusion-injured skeletal muscle were investigated by performing hematoxylin and eosin staining and assessing the wet weight/dry weight ratio of muscle tissue. Then, we measured lipid peroxidation, antioxidant activity and inflammatory cytokine levels. Moreover, Western blotting was conducted to examine the protein levels of MAPK/NF-휅B pathway members.

Results

Bilobalide treatment could protected hind limb skeletal muscle from ischemia/reperfusion injury by alleviating oxidative stress and inflammatory responses via the MAPK/NF-휅B pathways.

Conclusions

Bilobalide may be a promising drug for I/R-injured muscle tissue. However, the specific mechanisms for the protective effects still need further study.

Protective Effects of Dexmedetomidine and Oxycodone in Patients Undergoing Limb Ischemia-Reperfusion

Background

Tourniquet-related complications are a common clinical problem. In the present study, we compared the effects of dexmedetomidine vs. oxycodone in patients undergoing limb ischemia-reperfusion.

Material/Methods

Fifty-four patients undergoing unilateral lower-extremity surgery under combined spinal and epidural anesthesia were randomly assigned to a control (ischemia-reperfusion, I/R) group, a dexmedetomidine (Dex) group, and an oxycodone (Oxy) group. Tourniquet-induced hemodynamic parameters changes among groups were compared. The serum concentration of malondialdehyde (MDA), superoxide dismutase (SOD), tumor necrosis factor-a (TNF-α), interleukin-6 (IL-6), fatty acid binding protein 3 (FABP3), endothelin-1 (ET-1), and brain-derived neurotrophic factor (BDNF) were measured using ELISA before anesthesia and at 30 min and at 6 h after tourniquet release.

Results

In the control group, tourniquet use caused significant increases in systolic arterial pressure (SAP), mean arterial pressure (MAP), diastolic arterial pressure (DAP), and rate-pressure product. Compared with Oxy, Dex significantly decreased heart rate (HR). Both Dex and Oxy lowered SAP compared with the control group. No significant difference was observed in DAP between Dex and Oxy. The levels of MDA, TNF-α, IL-6, FABP3, and ET-1 were significantly higher, while the SOD and BDNF were significantly lower compared to baseline in the I/R group, but the variation range of those agents was significantly smaller in the Dex and Oxy groups, and the measured values were comparable between the 2 groups.

Conclusions

Compared with Dex, Oxy was not inferior in mitigating tourniquet-induced hyperdynamic response, ameliorating the inflammatory reaction, and protecting remote multiple organs in lower-extremity surgery patients.

Chronic intermittent hypobaric hypoxia attenuates skeletal muscle ischemia-reperfusion injury in mice

AIM

The aim of this study was to investigate the protective effect of chronic intermittent hypobaric hypoxia (CIHH) against skeletal muscle ischemia-reperfusion (IR) injury and to determine the underlying mechanism.

MAIN METHODS

C57BL/6 mice were randomly divided into 3 groups: skeletal muscle IR injury group (IR), CIHH pretreatment following IR group (IR + CIHH), and sham operation group (Sham). The skeletal muscle IR injury model was induced by the unilateral application of a tourniquet on a hind limb for 3 h and then releasing it for 24 h. CIHH pretreatment simulating a 5000-m altitude was applied 6 h per day for 28 days. The functional and morphological performance of IR-injured gastrocnemius muscle was evaluated using contraction force, H&E staining, and transmission electron microscopy. IR injury-induced CD68⁺ macrophage infiltration was assessed by immunofluorescence. TNFα levels in serum and muscle were measured by ELISA and western blotting, respectively. Apoptosis was examined by TUNEL staining and Cleaved Caspase-3 protein expression.

KEY FINDINGS

Acute IR injury resulted in reduced contraction tension, morphological destruction, macrophage infiltration, increased TNFα levels, and apoptosis in gastrocnemius muscle. CIHH pretreatment significantly ameliorated contraction function and morphological performance in IR-injured skeletal muscle. In addition, CIHH pretreatment resulted in marked decreases in CD68⁺ macrophage infiltration, TNFα levels, and apoptosis.

SIGNIFICANCE

These data demonstrated that CIHH has a protective effect against acute IR injury in skeletal muscle via inhibition of inflammation and apoptosis.

Vagus Nerve Stimulation Attenuates Acute Skeletal Muscle Injury Induced by Ischemia-Reperfusion in Rats

Vagus nerve stimulation (VNS) has been shown to attenuate ischemia-reperfusion (I/R) injury in multiple organs. The present study aimed at investigating whether VNS could exert protective effects against I/R injury in the skeletal muscle. Male Sprague-Dawley rats were randomly divided into 3 groups: the control, I/R, and I/R+VNS groups. The skeletal muscle I/R (SMI/R) model was induced by occlusion of the left femoral artery for 2.5 hours followed by reperfusion for 2 hours. The vagal nerve trunk was separated, and VNS was performed during the whole I/R process. The intensity of VNS was optimized in each rat to obtain a 10% reduction in the heart rate relative to the value before stimulation. After the experiment, the blood sample and left gastrocnemius muscle tissues were collected for histological examination, biochemical analysis, and molecular biological detection. During the I/R process, VNS significantly reduced cellular apoptosis, necrosis, and inflammatory cell infiltration compared to sham VNS. The VNS treatment also decreased the inflammatory response, alleviated oxidative stress, and improved vascular endothelial function (p < 0.05 for each). In contrast, the I/R group showed an opposite effect compared to the control group. The present study indicated that VNS could protect against SMI/R injury by suppressing excessive inflammation, alleviating oxidative stress, and preserving vascular endothelial function.