Sema3E/PlexinD1 signaling inhibits postischemic angiogenesis by regulating endothelial DLL4 and filopodia formation in a rat model of ischemic stroke.

Angiogenesis is a crucial defense response to hypoxia that regulates the process of raising the promise of long-term neurologic recovery during the management of stroke. A high expression of antiangiogenic factors leads to the loss of neovascularization capacity in pathologic conditions. We have previously documented an impairment of the cerebral vessel perfusion and neovascularization in the cortex neighboring the stroke-induced lesion, which was accompanied by an activation of semaphorin 3E (Sema3E)/PlexinD1 after ischemic stroke. In this study, we employed micro-optical sectioning tomography to fully investigate the details of the vascular pattern, including the capillaries. We found that after transient middle cerebral artery occlusion, inhibiting PlexinD1 signaling led to an organized recovery of the vascular network in the ischemic area. We then further explored the possible mechanisms. In vivo, Sema3E substantially decreased dynamic delta-like 4 (DLL4) expression. In cultured brain microvascular endothelial cells, Sema3E down-regulated DLL4 expression via inhibiting Ras-related C3 botulinum toxin substrate 1-induced JNK phosphorylation. At the microcosmic level, Sema3E/PlexinD1 signaling promoted F-actin disassembly and focal adhesion reduction by activating the small guanosine triphosphatase Ras homolog family member J by releasing RhoGEF Tuba from direct binding to PlexinD1, thus mediating endothelial cell motility and filopodia retraction. Our study reveals that Sema3E/PlexinD1 signaling, which suppressed endothelial DLL4 expression, cell motility, and filopodia formation, is expected to be a novel druggable target for angiogenesis during poststroke progression.-Zhou, Y.-F., Chen, A.-Q., Wu, J.-H., Mao, L., Xia, Y.-P., Jin, H.-J., He, Q.-W., Miao, Q. R., Yue, Z.-Y., Liu, X.-L., Huang, M., Li, Y.-N., Hu, B. Sema3E/PlexinD1 signaling inhibits postischemic angiogenesis by regulating endothelial DLL4 and filopodia formation in a rat model of ischemic stroke.

Sema4D/PlexinB1 inhibition ameliorates blood-brain barrier damage and improves outcome after stroke in rats.

The inflammatory process in stroke is the major contributor to blood-brain barrier (BBB) breakdown. Previous studies indicated that semaphorin 4D (Sema4D), an axon guidance molecule, initiated inflammatory microglial activation and disrupted endothelial function in the CNS. However, whether Sema4D disrupts BBB integrity after stroke remains unclear. To study the effect of Sema4D on BBB disruption in stroke, rats were subjected to transient middle cerebral artery occlusion and targeted injection of lentivirus-mediated clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene disruption of PlexinB1. We found that Sema4D synchronously increased with BBB permeability and accumulated in the perivascular area after stroke. Suppressing Sema4D/PlexinB1 signaling in the periinfarct cortex significantly decreased BBB permeability as detected by MRI and fibrin deposition, and thereby improved stroke outcome. In vitro, we confirmed that Sema4D disrupted BBB integrity and endothelial tight junctions. Moreover, we found that Sema4D induced pericytes to acquire a CD11b-positive phenotype and express proinflammatory cytokines. In addition, Sema4D inhibited AUF1-induced proinflammatory mRNA decay effect. Taken together, our data provides evidence that Sema4D disrupts BBB integrity and promotes an inflammatory response by binding to PlexinB1 in pericytes after transient middle cerebral artery occlusion. Our study indicates that Sema4D may be a novel therapeutic target for treatment in the acute phase of stroke.-Zhou, Y.-F., Li, Y.-N., Jin, H.-J., Wu, J.-H., He, Q.-W., Wang, X.-X., Lei, H., Hu, B. Sema4D/PlexinB1 inhibition ameliorates blood-brain barrier damage and improves outcome after stroke in rats.

Endogenous Retroviruses Unveiled: A Comprehensive Review of Inflammatory Signaling/Senescence-Related Pathways and Therapeutic Strategies.

Endogenous retroviruses (ERVs), a subset of genomic transposable elements (TEs) in a broader sense, have remained latent within mammalian genomes for tens of millions of years. These genetic elements are typically in a silenced state due to stringent regulatory mechanisms. However, under specific conditions, they can become activated, triggering inflammatory responses through diverse mechanisms. This activation has been shown to play a potential role in various neurological disorders, tumors, and cellular senescence. Consequently, the regulation of ERV expression through various methods holds promise for clinical applications in disease treatment. ERVs also engage in interactions with a variety of exogenous viruses, thereby influencing the outcomes of viral infectious diseases. This article comprehensively reviews the pathogenic cascade of ERVs, encompassing activation, inflammation, associated diseases, senescence, and interplay with viruses. Additionally, it outlines therapeutic strategies targeting ERVs with the aim of offering novel research directions for understanding the relationship between ERVs and diseases, along with corresponding treatment modalities.

Cell Heterogeneity Uncovered by Single-Cell RNA Sequencing Offers Potential Therapeutic Targets for Ischemic Stroke.

Ischemic stroke is a detrimental neurological disease characterized by an irreversible infarct core surrounded by an ischemic penumbra, a salvageable region of brain tissue. Unique roles of distinct brain cell subpopulations within the neurovascular unit and peripheral immune cells during ischemic stroke remain elusive due to the heterogeneity of cells in the brain. Single-cell RNA sequencing (scRNA-seq) allows for an unbiased determination of cellular heterogeneity at high-resolution and identification of cell markers, thereby unveiling the principal brain clusters within the cell-type-specific gene expression patterns as well as cell-specific subclusters and their functions in different pathways underlying ischemic stroke. In this review, we have summarized the changes in differentiation trajectories of distinct cell types and highlighted the specific pathways and genes in brain cells that are impacted by stroke. This review is expected to inspire new research and provide directions for investigating the potential pathological mechanisms and novel treatment strategies for ischemic stroke at the level of a single cell.

Lipid accumulation and novel insight into vascular smooth muscle cells in atherosclerosis.

Atherosclerosis is a chronic and progressive process. It is the most important pathological basis of cardiovascular disease and stroke. Vascular smooth muscle cells (VSMCs) are an essential cell type in atherosclerosis. Previous studies have revealed that VSMCs undergo phenotypic transformation in atherosclerosis to participate in the retention of atherogenic lipoproteins as well as the formation of the fibrous cap and the underlying necrotic core in plaques. The emergence of lineage-tracing studies indicates that the function and number of VSMCs in plaques have been greatly underestimated. In addition, recent studies have revealed that VSMCs make up at least 50% of the foam cell population in human and mouse atherosclerotic lesions. Therefore, understanding the formation of lipid-loaded VSMCs and their regulatory mechanisms is critical to elucidate the pathogenesis of atherosclerosis and to explore potential therapeutic targets. Moreover, combination of many complementary technologies such as lineage tracing, single-cell RNA sequencing (scRNA-seq), flow cytometry, and mass cytometry (CyTOF) with immunostaining has been performed to further understand the complex VSMC function. Correct identification of detrimental and beneficial processes may reveal successful therapeutic treatments targeting VSMCs and their derivatives during atherosclerosis. The purpose of this review is to summarize the process of lipid-loaded VSMC formation in atherosclerosis and to describe novel insight into VSMCs gained by using multiple advanced methods.

Inhibition of Sema4D/PlexinB1 signaling alleviates vascular dysfunction in diabetic retinopathy.

Diabetic retinopathy (DR) is a common complication of diabetes and leads to blindness. Anti-VEGF is a primary treatment for DR. Its therapeutic effect is limited in non- or poor responders despite frequent injections. By performing a comprehensive analysis of the semaphorins family, we identified the increased expression of Sema4D during oxygen-induced retinopathy (OIR) and streptozotocin (STZ)-induced retinopathy. The levels of soluble Sema4D (sSema4D) were significantly increased in the aqueous fluid of DR patients and correlated negatively with the success of anti-VEGF therapy during clinical follow-up. We found that Sema4D/PlexinB1 induced endothelial cell dysfunction via mDIA1, which was mediated through Src-dependent VE-cadherin dysfunction. Furthermore, genetic disruption of Sema4D/PlexinB1 or intravitreal injection of anti-Sema4D antibody reduced pericyte loss and vascular leakage in STZ model as well as alleviated neovascularization in OIR model. Moreover, anti-Sema4D had a therapeutic advantage over anti-VEGF on pericyte dysfunction. Anti-Sema4D and anti-VEGF also conferred a synergistic therapeutic effect in two DR models. Thus, this study indicates an alternative therapeutic strategy with anti-Sema4D to complement or improve the current treatment of DR.

Semaphorin-3A protects against neointimal hyperplasia after vascular injury.

BACKGROUND: Neointimal hyperplasia is a prominent pathological event during in-stent restenosis. Phenotype switching of vascular smooth muscle cells (VSMCs) from a differentiated/contractile to a dedifferentiated/synthetic phenotype, accompanied by migration and proliferation of VSMCs play an important role in neointimal hyperplasia. However, the molecular mechanisms underlying phenotype switching of VSMCs have yet to be fully understood. METHODS: The mouse carotid artery ligation model was established to evaluate Sema3A expression and its role during neointimal hyperplasia in vivo. Bioinformatics analysis, chromatin immunoprecipitation (ChIP) assays and promoter-luciferase reporter assays were used to examine regulatory mechanism of Sema3A expression. SiRNA transfection and lentivirus infection were performed to regulate Sema3A expression. EdU assays, Wound-healing scratch experiments and Transwell migration assays were used to assess VSMC proliferation and migration. FINDINGS: In this study, we found that semaphorin-3A (Sema3A) was significantly downregulated in VSMCs during neointimal hyperplasia after vascular injury in mice and in human atherosclerotic plaques. Meanwhile, Sema3A was transcriptionally downregulated by PDGF-BB via p53 in VSMCs. Furthermore, we found that overexpression of Sema3A inhibited VSMC proliferation and migration, as well as increasing differentiated gene expression. Mechanistically, Sema3A increased the NRP1-plexin-A1 complex and decreased the NRP1-PDGFRß complex, thus inhibiting phosphorylation of PDGFRß. Moreover, we found that overexpression of Sema3A suppressed neointimal hyperplasia after vascular injury in vivo. INTERPRETATION: These results suggest that local delivery of Sema3A may act as a novel therapeutic option to prevent in-stent restenosis.

Sema3E/PlexinD1 inhibition is a therapeutic strategy for improving cerebral perfusion and restoring functional loss after stroke in aged rats.

Brain tissue survival and functional recovery after ischemic stroke greatly depend on cerebral vessel perfusion and functional collateral circulation in the ischemic area. Semaphorin 3E (Sema3E), one of the class 3 secreted semaphorins, has been demonstrated to be a critical regulator in embryonic and postnatal vascular formation via binding to its receptor PlexinD1. However, whether Sema3E/PlexinD1 signaling is involved in poststroke neovascularization remains unknown. To determine the contribution of Sema3E/PlexinD1 signaling to poststroke recovery, aged rats (18 months) were subjected to a transient middle cerebral artery occlusion. We found that depletion of Sema3E/PlexinD1 signaling with lentivirus-mediated PlexinD1-specific-shRNA improves tissue survival and functional outcome. Sema3E/PlexinD1 inhibition not only increases cortical perfusion but also ameliorates blood-brain barrier damage, as determined by positron emission tomography and magnetic resonance imaging. Mechanistically, we demonstrated that Sema3E suppresses endothelial cell proliferation and angiogenic capacity. More importantly, Sema3E/PlexinD1 signaling inhibits recruitment of pericytes by decreasing production of platelet derived growth factor-BB in endothelial cells. Overall, our study revealed that inhibition of Sema3E/PlexinD1 signaling in the ischemic penumbra, which increases both endothelial angiogenic capacity and recruitment of pericytes, contributed to functional neovascularization and blood-brain barrier integrity in the aged rats. Our findings imply that Sema3E/PlexinD1 signaling is a novel therapeutic target for improving brain tissue survival and functional recovery after ischemic stroke.

Semaphorin-3E attenuates neointimal formation via suppressing VSMCs migration and proliferation.

AIMS: The migration and proliferation of vascular smooth muscle cells (VSMCs) are crucial events in the neointimal formation, a hallmark of atherosclerosis and restenosis. Semaphorin3E (Sema3E) has been found to be a critical regulator of cell migration and proliferation in many scenarios. However, its role on VSMCs migration and proliferation is unclear. This study aimed to investigate the effect of Sema3E on VSMCs migration, proliferation and neointimal formation, and explore possible mechanisms. METHODS AND RESULTS: We found that the expression of Sema3E was progressively decreased during neointimal formation in a carotid ligation model. H&E-staining showed lentivirus-mediated overexpression of Sema3E in carotid ligation area attenuated neointimal formation. Immunofluorescence staining showed that the receptor (PlexinD1) of Sema3E was expressed in vascular walls. In cultured mouse VSMCs, Sema3E inhibited VSMCs migration and proliferation via plexinD1 receptor. The inhibitory effect was mediated, at least in part, by inactivating Rap1-AKT signalling pathways in VSMCs. Moreover, we found that PDGFBB down-regulated the expression of Sema3E in VSMCs and Sema3E notably inhibited the expression of PDGFB in endothelial cells. In addition, the number of Sema3E-positive VSMCs was diminished in plaques of atherosclerotic patients. Results from a public GEO microarray database showed a negative correlation between Sema3E and PDGFB transcriptional levels in the human plaques examined. CONCLUSION: Our study demonstrates that Sema3E/plexinD1 inhibits proliferation and migration of VSMCs via inactivation of Rap1-AKT signalling pathways. The mutual inhibition between PDGF-BB and Sema3E after vascular injury plays a critical role in the process of neointimal formation.