Inhibition of Plexin C1 Protects Against Hepatic Ischemia-Reperfusion Injury*:

PLXNC1 interference alleviates the inflammatory injury, apoptosis and extracellular matrix degradation of IL-1β-exposed chondrocytes via suppressing GRP78 expression

BACKGROUND

Osteoarthritis (OA) is a frequently encountered debilitating joint disorder. Whether plexin C1 (PLXNC1) is implicated in OA is far from being investigated despite its well-documented pro-inflammatory property in human diseases. The goal of this study is to expound the specific role of PLXNC1 in OA and elaborate the probable action mechanism.

METHODS

Firstly, PLXNC1 expression in the cartilage tissues of patients with OA was examined with GEO database. In interleukin-1beta (IL-1β)-induced OA cell model, RT-qPCR and western blotting tested the expression of PLXNC1, glucose-regulating protein 78 (GRP78) and extracellular matrix (ECM) degradation-related factors. Cell viability and inflammation were respectively judged by CCK-8 assay and RT-qPCR. TUNEL and western blotting estimated cell apoptosis. The potential binding between PLXNC1 and GRP78 was corroborated by Co-IP assay. Western blotting also tested the expression of endoplasmic reticulum stress (ERS)-associated proteins.

RESULTS

As it turned out, PLXNC1 expression was elevated in the cartilage tissues of patients with OA and IL-1β-treated chondrocytes. When PLXNC1 was depleted, the viability injury, inflammation, apoptosis and ECM degradation of chondrocytes exposed to IL-1β were obstructed. Besides, GRP78 bond to PLXNC1 in IL-1β-treated chondrocytes. The ascending GRP78 expression in the chondrocytes exposed to IL-1β was depleted after PLXNC1 was silenced. Meanwhile, the impacts of PLXNC1 deficiency on the viability, inflammatory response, apoptosis, ECM degradation as well as ERS in IL-1β-exposed chondrocytes were abolished by GRP78 up-regulation.

CONCLUSION

In summary, PLXNC1 silencing might interact with and down-regulate GRP78 to mitigate the apoptosis, inflammation, and ECM degradation of IL-1β-insulted chondrocytes in OA.

Surgical Science and the Evolution of Critical Care Medicine

Surgical science has driven innovation and inquiry across adult and pediatric disciplines that provide critical care regardless of location. Surgically originated but broadly applicable knowledge has been globally shared within the pages Critical Care Medicine over the last 50 years.

Targeting the Semaphorin3E-plexinD1 complex in allergic asthma

Asthma is a heterogenous airway disease characterized by airway inflammation and remodeling. It affects more than 300 million people worldwide and poses a significant burden on society. Semaphorins, discovered initially as neural guidance molecules, are ubiquitously expressed in various organs and regulate multiple signaling pathways. Interestingly, Semaphorin3E is a critical molecule in lung pathophysiology through its role in both lung development and homeostasis. Semaphorin3E binds to plexinD1, mediating regulatory effects on cell migration, proliferation, and angiogenesis. Recent in vitro and in vivo studies have demonstrated that the Semaphorin3E-plexinD1 axis is implicated in asthma, impacting inflammatory and structural cells associated with airway inflammation, tissue remodeling, and airway hyperresponsiveness. This review details the Semaphorin3E-plexinD1 axis in various aspects of asthma and highlights future directions in research including its potential role as a therapeutic target in airway allergic diseases.

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

Vagus nerve stimulation (VNS) has a protective effect on distal organ injury after ischemia/reperfusion (I/R) injury. We aimed to investigate the protective efficacy of VNS on hepatic I/R injury-induced acute skeletal muscle injury and explore its underlying mechanisms. To test this hypothesis, male Sprague-Dawley rats were randomly divided into three groups: sham group (sham operation, n = 6); I/R group (hepatic I/R with sham VNS, n = 6); and VNS group (hepatic I/R with VNS, n = 6). A hepatic I/R injury model was prepared by inducing hepatic ischemia for 1 h (70%) followed by hepatic reperfusion for 6 h. VNS was performed during the entire hepatic I/R process. Tissue and blood samples were collected at the end of the experiment for biochemical assays, molecular biological preparations, and histological examination. Our results showed that throughout the hepatic I/R process, VNS significantly reduced inflammation, oxidative stress, and apoptosis, while significantly increasing the protein levels of silent information regulator 1 (SIRT1) and decreasing the levels of acetylated forkhead box O1 and Ac-p53, in the skeletal muscle. These data suggest that VNS can alleviate hepatic I/R injury-induced acute skeletal muscle injury by suppressing inflammation, oxidative stress, and apoptosis, potentially via the SIRT1 pathway.

Hypoxia-inducible factor-dependent induction of myeloid-derived netrin-1 attenuates natural killer cell infiltration during endotoxin-induced lung injury

Sepsis and sepsis‐associated lung inflammation significantly contribute to the morbidity and mortality of critical illness. Here, we examined the hypothesis that neuronal guidance proteins could orchestrate inflammatory events during endotoxin‐induced lung injury. Through a targeted array, we identified netrin‐1 as the top upregulated neuronal guidance protein in macrophages treated with lipopolysaccharide (LPS). Furthermore, we found that netrin‐1 is highly enriched in infiltrating myeloid cells, particularly in macrophages during LPS‐induced lung injury. Transcriptional studies implicate hypoxia‐inducible factor HIF‐1α in the transcriptional induction of netrin‐1 during LPS treatment. Subsequently, the deletion of netrin‐1 in the myeloid compartment (Ntn1^loxp/loxp LysM Cre) resulted in exaggerated mortality and lung inflammation. Surprisingly, further studies revealed enhanced natural killer cells (NK cells) infiltration in Ntn1^loxp/loxp LysM Cre mice, and neutralization of NK cell chemoattractant chemokine (C‐C motif) ligand 2 (CCL2) reversed the exaggerated lung inflammation. Together, these studies provide functional insight into myeloid cell‐derived netrin‐1 in controlling lung inflammation through the modulation of CCL2‐dependent infiltration of NK cells.

Semaphorin 3F Promotes Transendothelial Migration of Leukocytes in the Inflammatory Response After Survived Cardiac Arrest

Leukocyte transmigration through the blood vessel wall is a fundamental step of the inflammatory response and requires expression of adhesion molecule PECAM-1. Accumulating evidence implicates that semaphorin (Sema) 3F and its receptor neuropilin (NRP) 2 are central regulators in vascular biology. Herein, we assess the role of Sema3F in leukocyte migration in vitro and in vivo. To determine the impact of Sema3F on leukocyte recruitment in vivo, we used the thioglycollate-induced peritonitis model. After the induction of peritonitis, C57BL/6 mice were intraperitoneally (i.p.) injected daily with recombinant Sema3F or solvent for 3 days. Compared with solvent-treated controls, leukocyte count was increased in the peritoneal lavage of Sema3F-treated mice indicating that Sema3F promotes leukocyte extravasation into the peritoneal cavity. In line with this observation, stimulation of human endothelial cells with Sema3F enhanced the passage of peripheral blood mononuclear cells (PBMCs) through the endothelial monolayer in the transwell migration assays. Conversely, silencing of endothelial Sema3F by siRNA transfection dampened diapedesis of PBMCs through the endothelium in vitro. xMechanistically, Sema3F induced upregulation of adhesion molecule PECAM-1 in endothelial cells and in murine heart tissue shown by immunofluorescence and western blotting. The inhibition of PECAM-1 by blocking antibody HEC7 blunted Sema3F-induced leukocyte migration in transwell assays. SiRNA-based NRP2 knockdown reduced PECAM-1 expression and migration of PBMCs in Sema3F-treated endothelial cells, indicating that PECAM-1 expression and leukocyte migration in response to Sema3F depend on endothelial NRP2. To assess the regulation of Sema3F in human inflammatory disease, we collected serum samples of patients from day 0 to day 7 after survived out-of-hospital cardiac arrest (OHCA, n = 41). First, we demonstrated enhanced migration of PBMCs through endothelial cells exposed to the serum of patients after OHCA in comparison to the serum of patients with stable coronary artery disease or healthy volunteers. Remarkably, serum samples of OHCA patients contained significantly higher Sema3F protein levels compared with CAD patients (CAD, n = 37) and healthy volunteers (n = 11), suggesting a role of Sema3F in the pathophysiology of the inflammatory response after OHCA. Subgroup analysis revealed that elevated serum Sema3F levels after ROSC are associated with decreased survival, myocardial dysfunction, and prolonged vasopressor therapy, clinical findings that determine the outcome of post-resuscitation period after OHCA. The present study provides novel evidence that endothelial Sema3F controls leukocyte recruitment through a NRP2/PECAM-1-dependent mechanism. Sema3F serum concentrations are elevated following successful resuscitation suggesting that Sema3F might be involved in the inflammatory response after survived OHCA. Targeting the Sema3F/NRP2/PECAM-1 pathway could provide a novel approach to abolish overwhelming inflammation after resuscitation.

Investigation mechanisms between normal, developing and regenerating livers for regenerative liver drug design

Aim: A systematic multimolecule drug design procedure is proposed for promoting hepatogenesis and liver regeneration. Materials & methods: Genome-wide microarray data including three hepatic conditions are obtained from the GEO database (GSE15238). System modeling and big data mining methods are used to construct real genome-wide genetic-and-epigenetic networks (GWGENs). Then, we extracted the core GWGENs by applying principal network projection on real GWGENs of normal, developing and regenerating livers, respectively. After that, we investigated the significant signal pathways and epigenetic modifications in the core GWGENs to identify potential biomarkers as drug targets. Result & conclusion: A multimolecule drug consisting of sulmazole, clofibrate, colchicine, furazolidone, nadolol, eticlopride and felbinac is proposed to target on novel biomarkers for promoting hepatogenesis and liver regeneration.

Semaphorins and Their Roles in Airway Biology: Potential as Therapeutic Targets

Semaphorins are a large family of proteins originally identified as axon guidance cues that play a crucial role in neural development. They are also ubiquitously expressed beyond the nervous system and contribute to regulation of essential cell functions, such as cell migration, proliferation, and adhesion. Binding of semaphorins to their receptors, including plexins and neuropilins, triggers diverse signaling pathways, which are involved in the pathogenesis of various diseases, from cancer to autoimmune and allergic disorders. Despite emerging evidence suggestive of nonredundant roles of semaphorins in cellular and molecular mechanisms of the airway biology, their precise expression and function have not been fully addressed. Here, we first provide an overview about the semaphorin family, their receptors, signaling pathways, and their cellular functions. Then, we highlight the novel findings on the role of semaphorins in airway biology under developmental, homeostatic, and pathological conditions. In particular, we discuss the dual roles of semaphorins in respiratory disorders where they can up- or downregulate processes underlying the pathophysiology of the airway diseases. Next, our recent findings on the expression and function of semaphorin 3E in allergic asthma are further emphasized, and its potential mechanism of action in allergic airway inflammation and remodeling is discussed. Finally, we raise some unanswered questions aiming to develop future research directions.

Immunomodulatory Functions of Neuronal Guidance Proteins

Neuronal guidance proteins (NGPs) were originally identified for their role during the embryonic development of the nervous system. Recent years have seen the discovery of NGP functions during immune responses. In this context, NGPs were demonstrated to control leukocyte migration and the release of cytokines during conditions of acute inflammation, such as lung injury or sepsis. However, NGPs also display potent actions in the resolution of inflammation, chronic inflammatory conditions, the development of atherosclerosis, and during ischemia followed by reperfusion. Here, we provide an overview of the current state of knowledge about the role of NGPs in the immune system and describe their immunomodulatory function.

Pre-conditions for eliminating mitochondrial dysfunction and maintaining liver function after hepatic ischaemia reperfusion

The liver, the largest organ with multiple synthesis and secretion functions in mammals, consists of hepatocytes and Kupffer, stem, endothelial, stellate and other parenchymal cells. Because of early and extensive contact with the external environment, hepatic ischaemia reperfusion (IR) may result in mitochondrial dysfunction, autophagy and apoptosis of cells and tissues under various pathological conditions. Because the liver requires a high oxygen supply to maintain normal detoxification and synthesis functions, it is extremely susceptible to ischaemia and subsequent reperfusion with blood. Consequently, hepatic IR leads to acute or chronic liver failure and significantly increases the total rate of morbidity and mortality through multiple regulatory mechanisms. An increasing number of studies indicate that mitochondrial structure and function are impaired after hepatic IR, but that the health of liver tissues or liver grafts can be effectively rescued by attenuation of mitochondrial dysfunction. In this review, we mainly focus on the subsequent therapeutic interventions related to the conservation of mitochondrial function involved in mitigating hepatic IR injury and the potential mechanisms of protection. Because mitochondria are abundant in liver tissue, clarification of the regulatory mechanisms between mitochondrial dysfunction and hepatic IR should shed light on clinical therapies for alleviating hepatic IR‐induced injury.

Current drug design to target the Semaphorin/Neuropilin/Plexin complexes

The Semaphorin/Neuropilin/Plexin (SNP) complexes control a wide range of biological processes. Consistently, activity deregulation of these complexes is associated with many diseases. The increasing knowledge on SNP had in turn validated these molecular complexes as novel therapeutic targets. Targeting SNP activities by small molecules, antibodies and peptides or by soluble semaphorins have been proposed as new therapeutic approach. This review is focusing on the latest demonstration of this potential and discusses some of the key questions that need to be addressed before translating SNP targeting into clinically relevant approaches.