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

N-butylphthalide (NBP) ameliorated ischemia/reperfusion-induced skeletal muscle injury in male mice via activating Sirt1/Nrf2 signaling pathway

N-butylphthalide (NBP) has been reported to have potential protective effects in ischemic stroke via its antioxidative properties. The present study was aimed to investigate the protective effects of NBP on ischemia/reperfusion (I/R)-induced skeletal muscle injury. Mouse model of I/R-induced skeletal muscle injury and hypoxia/reoxygenation (H/R)-induced C2C12 myotube injury model were constructed to test the protective effects of NBP both in vivo and in vitro. Our results showed that I/R resulted in skeletal muscle injury, as evidenced by elevated levels of LDH, CK, ROS, 3-NT, MDA, and 4-HNE as well as decreased activities of SOD, GSH-Px, and decreased expression of Myog and MyoD in gastrocnemius muscle, which was ameliorated by NBP treatment. Mechanistically, NBP treatment increased the expression of Sirt1 and Nrf2 in the injured skeletal muscle. Notably, the protective effects of NBP on I/R-induced skeletal muscle injury was diminished by the treatment of Sirt1 inhibitor. Further studies in H/R-induced C2C12 myotubes injury model also showed that NBP activated the Sirt1/Nrf2 pathway. NBP treatment upregulated the expression of myog and MyoD in H/R-stimulated C2C12 myotubes, which was eliminated by silencing of Sirt1. Taken together, our results suggest that NBP may alleviated I/R-induced skeletal muscle injury by activating Sirt1/Nrf2 signaling pathway.

Bibliometric analysis of skeletal muscle ischemia/reperfusion (I/R) research from 1986 to 2022

Introduction

Tissue damage due to ischemia and reperfusion is a critical medical problem worldwide. Studies in this field have made remarkable advances in understanding the pathogenesis of ischemia/reperfusion (I/R) injury and its treatment with new and known drugs. However, no bibliometric analysis exists in this area of research.

Methods

Research articles and reviews related to skeletal muscle I/R from 1986 to 2022 were retrieved from the Web of Science Core Collection. Bibliometric analysis was performed using Microsoft Excel 2019, VOSviewer (version 1.6.19), Bibliometrix (R-Tool for R-Studio), and CiteSpace (version 6.1.R5).

Results

A total of 3682 research articles and reviews from 2846 institutions in 83 countries were considered in this study. Most studies were conducted in the USA. Hobson RW (UMDNJ-New Jersey Medical School) had the highest publication, and Korthuis RJ (Louisiana State University) had the highest co-citations. Our analysis showed that, though the Journal of Surgical Research was most favored, the Journal of Biological Chemistry had the highest number of co-citations. The pathophysiology, interventions, and molecular mechanisms of skeletal muscle I/R injury emerged as the primary research areas, with "apoptosis," "signaling pathway," and "oxidative stress" as the main keywords of research hotspots.

Conclusions

This study provides a thorough overview of research trends and focal points in skeletal muscle I/R injury by applying bibliometric and visualization techniques. The insights gained from our findings offer a profound understanding of the evolving landscape of skeletal muscle I/R injury research, thereby functioning as a valuable reference and roadmap for future investigations.

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.

Lipid metabolism in B cell biology

In recent years, the field of immunometabolism has solidified its position as a prominent area of investigation within the realm of immunological research. An expanding body of scientific literature has unveiled the intricate interplay between energy homeostasis, signalling molecules, and metabolites in relation to fundamental aspects of our immune cells. It is now widely accepted that disruptions in metabolic equilibrium can give rise to a myriad of pathological conditions, ranging from autoimmune disorders to cancer. Emerging evidence, although sometimes fragmented and anecdotal, has highlighted the indispensable role of lipids in modulating the behaviour of immune cells, including B cells. In light of these findings, this review aims to provide a comprehensive overview of the current state of knowledge regarding lipid metabolism in the context of B cell biology.

Evaluation of the effect of enriched hydrogen saline solution on distant organ (lung) damage in skeletal muscle ischemia reperfusion in rats

INTRODUCTION

Ischemia-reperfusion (IR) injury is a major concern that frequently occurs during vascular surgeries. Hydrogen-rich saline (HRS) solution exhibits antioxidant and anti-inflammatory properties. This study aimed to examine the effects of HRS applied before ischemia in the lungs of rats using a lower extremity IR model.

MATERIAL AND METHODS

After approval was obtained from the ethics committee, 18 male Wistar albino rats weighing 250-280 g were randomly divided into three groups: control (C), IR and IR-HRS. In the IR and IR-HRS groups, an atraumatic microvascular clamp was used to clamp the infrarenal abdominal aorta, and skeletal muscle ischemia was induced. After 120 min, the clamp was removed, and reperfusion was achieved for 120 min. In the IR-HRS group, HRS was administered intraperitoneally 30 min before the procedure. Lung tissue samples were examined under a light microscope and stained with hematoxylin-eosin (H&E). Malondialdehyde (MDA) levels, total sulfhydryl (SH) levels, and histopathological parameters were evaluated in the tissue samples.

RESULTS

MDA and total SH levels were significantly higher in the IR group than in the control group (p < 0.0001 and p = 0.001, respectively). MDA and total SH levels were significantly lower in the IR-HRS group than in the IR group (p < 0.0001 and p = 0.013, respectively). A histopathological examination revealed that neutrophil infiltration/aggregation, alveolar wall thickness, and total lung injury score were significantly higher in the IR group than in the control group (p < 0.0001, p = 0.001, and p < 0.0001, respectively). Similarly, alveolar wall thickness and total lung injury scores were significantly higher in the IR-HRS group than in the control group (p = 0.009 and p = 0.004, respectively). A statistically significant decrease was observed in neutrophil infiltration/aggregation and total lung injury scores in the IR-HRS group compared to those in the IR group (p = 0.023 and p = 0.022, respectively).

CONCLUSION

HRS at a dose of 20 mg/kg, administered intraperitoneally 30 min before ischemia in rats, reduced lipid peroxidation and oxidative stress, while also reducing IR damage in lung histopathology. We believe that HRS administered to rats prior to IR exerts a lung-protective effect.

Restoration of epigenetic impairment in the skeletal muscle and chronic inflammation resolution as a therapeutic approach in sarcopenia

Sarcopenia is an age-associated loss of skeletal muscle mass, strength, and function, accompanied by severe adverse health outcomes, such as falls and fractures, functional decline, high health costs, and mortality. Hence, its prevention and treatment have become increasingly urgent. However, despite the wide prevalence and extensive research on sarcopenia, no FDA-approved disease-modifying drugs exist. This is probably due to a poor understanding of the mechanisms underlying its pathophysiology. Recent evidence demonstrate that sarcopenia development is characterized by two key elements: (i) epigenetic dysregulation of multiple molecular pathways associated with sarcopenia pathogenesis, such as protein remodeling, insulin resistance, mitochondria impairments, and (ii) the creation of a systemic, chronic, low-grade inflammation (SCLGI). In this review, we focus on the epigenetic regulators that have been implicated in skeletal muscle deterioration, their individual roles, and possible crosstalk. We also discuss epidrugs, which are the pharmaceuticals with the potential to restore the epigenetic mechanisms deregulated in sarcopenia. In addition, we discuss the mechanisms underlying failed SCLGI resolution in sarcopenia and the potential application of pro-resolving molecules, comprising specialized pro-resolving mediators (SPMs) and their stable mimetics and receptor agonists. These compounds, as well as epidrugs, reveal beneficial effects in preclinical studies related to sarcopenia. Based on these encouraging observations, we propose the combination of epidrugs with SCLI-resolving agents as a new therapeutic approach for sarcopenia that can effectively attenuate of its manifestations.

Harnessing anti-inflammatory pathways and macrophage nano delivery to treat inflammatory and fibrotic disorders

Targeting specific organs and cell types using nanotechnology and sophisticated delivery methods has been at the forefront of applicative biomedical sciences lately. Macrophages are an appealing target for immunomodulation by nanodelivery as they are heavily involved in various aspects of many diseases and are highly plastic in their nature. Their continuum of functional "polarization" states has been a research focus for many years yielding a profound understanding of various aspects of these cells. The ability of monocyte-derived macrophages to metamorphose from pro-inflammatory to reparative and consequently to pro-resolving effectors has raised significant interest in its therapeutic potential. Here, we briefly survey macrophages' ontogeny and various polarization phenotypes, highlighting their function in the inflammation-resolution shift. We review their inducing mediators, signaling pathways, and biological programs with emphasis on the nucleic acid sensing-IFN-I axis. We also portray the polarization spectrum of macrophages and the characteristics of their transition between different subtypes. Finally, we highlighted different current drug delivery methods for targeting macrophages with emphasis on nanotargeting that might lead to breakthroughs in the treatment of wound healing, bone regeneration, autoimmune, and fibrotic diseases.

Market Needs and Methodologies Associated with Patient Lipidomic Diagnoses and Analyses

This chapter conducts an in-depth exploration of the impact of musculoskeletal (MSK) disorders and injuries, with a specific emphasis on their consequences within the older population demographic. It underscores the escalating demand for innovative interventions in MSK tissue engineering. The chapter also highlights the fundamental role played by lipid signaling mediators (LSMs) in tissue regeneration, with relevance to bone and muscle recovery. Remarkably, Prostaglandin E2 (PGE2) emerges as a central orchestrator in these regenerative processes. Furthermore, the chapter investigates the complex interplay between bone and muscle tissues, explaining the important influence exerted by LSMs on their growth and differentiation. The targeted modulation of LSM pathways holds substantial promise as a beneficial way for addressing muscle disorders. In addition to these conceptual understandings, the chapter provides a comprehensive overview of methodologies employed in the identification of LSMs, with a specific focus on the Liquid Chromatography-Mass Spectrometry (LC-MS). Furthermore, it introduces a detailed LC MS/MS-based protocol tailored for the detection of PGE2, serving as an invaluable resource for researchers immersed in this dynamic field of study.

Extracellular vesicles derived from human ESC-MSCs target macrophage and promote anti-inflammation process, angiogenesis, and functional recovery in ACS-induced severe skeletal muscle injury

BACKGROUND

Acute compartment syndrome (ACS) is one of the most common complications of musculoskeletal injury, leading to the necrosis and demise of skeletal muscle cells. Our previous study showed that embryonic stem cells-derived mesenchymal stem cells (ESC-MSCs) are novel therapeutics in ACS treatment. As extracellular vesicles (EVs) are rapidly gaining attention as cell-free therapeutics that have advantages over parental stem cells, the therapeutic potential and mechanisms of EVs from ESC-MSCs on ACS need to be explored.

METHOD

In the present study, we examined the protective effects in the experimental ACS rat model and investigated the role of macrophages in mediating these effects. Next, we used transcriptome sequencing to explore the mechanisms by which ESC-MSC-EVs regulate macrophage polarization. Furthermore, miRNA sequencing was performed on ESC-MSC-EVs to identify miRNA candidates associated with macrophage polarization.

RESULTS

We found that intravenous administration of ESC-MSC-EVs, given at the time of fasciotomy, significantly promotes the anti-inflammation process, angiogenesis, and functional recovery of muscle in ACS. The beneficial effects were associated with ESC-MSC-EVs affecting macrophage polarization by delivering various miRNAs which regulate NF-κB, JAK/STAT, and PI3K/AKT pathways. Our data further illustrate that ESC-MSC-EVs mainly modulate macrophage polarization via the miR-21/PTEN, miR-320a/PTEN, miR-423/NLRP3, miR-100/mTOR, and miR-26a/TLR3 axes.

CONCLUSION

Together, our results demonstrated the beneficial effects of ESC-MSC-EVs in ACS, wherein the miRNAs present in ESC-MSC-EVs regulate the polarization of macrophages.