Semaphorin 3A suppresses VEGF-mediated angiogenesis yet acts as a vascular permeability factor

Semaphorins in tumor microenvironment: Biological mechanisms and therapeutic progress

Hallmark features of the tumor microenvironment include immune cells, stromal cells, blood vessels, and extracellular matrix (ECM), providing a conducive environment for the growth and survival of tumors. Recent advances in the understanding of cancer biology have highlighted the functional role of semaphorins (SEMAs). SEMAs are a large and diverse family of widely expressed secreted and membrane-binding proteins, which were initially implicated in axon guidance and neural development. However, it is now clear that they are widely expressed beyond the nervous system and participate in regulating immune responses and cancer progression. In fact, accumulating evidence disclosed that different SEMAs can either stimulate or restrict tumor progression, some of which act as important regulators of tumor angiogenesis. Conversely, limited information is known about the functional relevance of SEMA signals in TME. In this setting, we systematically elaborate the role SEMAs and their major receptors played in characterized components of TME. Furthermore, we provide a convergent view of current SEMAs pharmacological progress in clinical treatment and also put forward their potential application value and clinical prospects in the future.

Semaphorins and the bone marrow microenvironment: New candidates that influence the hematopoietic system

The bone marrow is a haven for hematopoietic and non-hematopoietic cells, creating complex micro-anatomical regions called niches. These distinct niches all participate in an intricate orchestra of cellular interactions that regulates the hematopoietic stem cell and its progenies. In this review, we provide a detailed description of the three most well-known bone marrow niches and their participation in hematopoiesis. We use pre-clinical data, including different in vitro and in vivo studies to discuss how a group of proteins called Semaphorins could potentially modulate both hematopoietic and non-hematopoietic cells, establishing links between the niches, semaphorins, and hematopoietic regulation. Thus, here we provide a deep dive into the inner functioning of the bone marrow and discuss the overarching implications that semaphorins might have on blood formation.

Semaphorins: Missing Signals in Age-dependent Alteration of Neuromuscular Junctions and Skeletal Muscle Regeneration

Skeletal muscle is characterized by a remarkable capacity to rearrange after physiological changes and efficiently regenerate. However, during aging, extensive injury, or pathological conditions, the complete regenerative program is severely affected, with a progressive loss of muscle mass and function, a condition known as sarcopenia. The compromised tissue repair program is attributable to the gradual depletion of stem cells and to altered regulatory signals. Defective muscle regeneration can severely affect re-innervation by motor axons, and neuromuscular junctions (NMJs) development, ultimately leading to skeletal muscle atrophy. Defects in NMJ formation and maintenance occur physiologically during aging and are responsible for the pathogenesis of several neuromuscular disorders. However, it is still largely unknown how neuromuscular connections are restored on regenerating fibers. It has been suggested that attractive and repelling signals used for axon guidance could be implicated in this process; in particular, guidance molecules called semaphorins play a key role. Semaphorins are a wide family of extracellular regulatory signals with a multifaceted role in cell-cell communication. Originally discovered as axon guidance factors, they have been implicated in cancer progression, embryonal organogenesis, skeletal muscle innervation, and other physiological and developmental functions in different tissues. In particular, in skeletal muscle, specific semaphorin molecules are involved in the restoration and remodeling of the nerve-muscle connections, thus emphasizing their plausible role to ensure the success of muscle regeneration. This review article aims to discuss the impact of aging on skeletal muscle regeneration and NMJs remodeling and will highlight the most recent insights about the role of semaphorins in this context.

Regenerative Therapy for Corneal Scarring Disorders

The cornea is a transparent and vitally multifaceted component of the eye, playing a pivotal role in vision and ocular health. It has primary refractive and protective functions. Typical corneal dysfunctions include opacities and deformities that result from injuries, infections, or other medical conditions. These can significantly impair vision. The conventional challenges in managing corneal ailments include the limited regenerative capacity (except corneal epithelium), immune response after donor tissue transplantation, a risk of long-term graft rejection, and the global shortage of transplantable donor materials. This review delves into the intricate composition of the cornea, the landscape of corneal regeneration, and the multifaceted repercussions of scar-related pathologies. It will elucidate the etiology and types of dysfunctions, assess current treatments and their limitations, and explore the potential of regenerative therapy that has emerged in both in vivo and clinical trials. This review will shed light on existing gaps in corneal disorder management and discuss the feasibility and challenges of advancing regenerative therapies for corneal stromal scarring.

A cellular and spatial atlas of TP53 -associated tissue remodeling in lung adenocarcinoma

TP53 is the most frequently mutated gene across many cancers and is associated with shorter survival in lung adenocarcinoma (LUAD). To define how TP53 mutations affect the LUAD tumor microenvironment (TME), we constructed a multi-omic cellular and spatial tumor atlas of 23 treatment-naïve human lung tumors. We found that TP53 -mutant ( TP53 mut ) malignant cells lose alveolar identity and upregulate highly proliferative and entropic gene expression programs consistently across resectable LUAD patient tumors, genetically engineered mouse models, and cell lines harboring a wide spectrum of TP53 mutations. We further identified a multicellular tumor niche composed of SPP1 + macrophages and collagen-expressing fibroblasts that coincides with hypoxic, pro-metastatic expression programs in TP53 mut tumors. Spatially correlated angiostatic and immune checkpoint interactions, including CD274 - PDCD1 and PVR - TIGIT , are also enriched in TP53 mut LUAD tumors, which may influence response to checkpoint blockade therapy. Our methodology can be further applied to investigate mutation-specific TME changes in other cancers.

Involvement of neuronal factors in tumor angiogenesis and the shaping of the cancer microenvironment

Emerging evidence suggests that nerves within the tumor microenvironment play a crucial role in regulating angiogenesis. Neurotransmitters and neuropeptides released by nerves can interact with nearby blood vessels and tumor cells, influencing their behavior and modulating the angiogenic response. Moreover, nerve-derived signals may activate signaling pathways that enhance the production of pro-angiogenic factors within the tumor microenvironment, further supporting blood vessel growth around tumors. The intricate network of communication between neural constituents and the vascular system accentuates the potential of therapeutically targeting neural-mediated pathways as an innovative strategy to modulate tumor angiogenesis and, consequently, neoplastic proliferation. Hereby, we review studies that evaluate the precise molecular interplay and the potential clinical ramifications of manipulating neural elements for the purpose of anti-angiogenic therapeutics within the scope of cancer treatment.

Human Placenta Derived Mesenchymal Stem Cells Transplantation Reducing Cellular Apoptosis in Hypoxic-Ischemic Neonatal Rats by Down-Regulating Semaphorin 3A/Neuropilin-1

Neonatal hypoxic-ischemic encephalopathy (HIE) is an abnormal neurological condition caused by hypoxic-ischemic damage during the perinatal period. Human placenta derived mesenchymal stem cells (hPMSCs) have been shown to have protective and reparative effects in various neurological diseases; however, the research on HIE is insufficient. This study aimed to establish a rat model of HIE and transplant hPMSCs through the lateral ventricle after hypoxic-ishcemic (HI) brain damage to observe its protective effects and mechanisms, with a focus on brain apoptosis compared among groups. Differentially expressed apoptosis-related proteins were screened using a rat cytokine array and subsequent verification. Neuropilin-1 (NRP-1) and Semaphorin 3A (Sema 3A) were selected for further investigation. Western blotting was used to quantify the expression of Sema 3A and the proteins related to PI3K/Akt/mTOR signaling pathway. Exogenous Sema 3A was added to evaluate the effects of Sema 3A/NRP-1 on hPMSCs following HI injury. hPMSCs transplantation ameliorated HI-induced pathological changes, reduced apoptosis, and improved long-term neurological prognosis. Furthermore, Sema 3A/NRP-1 was a key regulator in reducing HI-induced apoptosis after hPMSCs transplantation. hPMSCs inhibited the expression of Sema 3A/NRP-1 and activated the PI3K/Akt/mTOR signaling pathway. Additionally, exogenous Sema 3A abolished the protective effects of hPMSCs against HI. In conclusion, hPMSCs transplantation reduced apoptosis and improved long-term neurological prognosis after HI by downregulating Sema 3A/NRP-1 expression and activating the PI3K/Akt/mTOR signaling pathway.

Specific Circular RNA Signature of Endothelial Cells: Potential Implications in Vascular Pathophysiology

Circular RNAs (circRNAs) are a recently characterized family of gene transcripts forming a covalently closed loop of single-stranded RNA. The extent of their potential for fine-tuning gene expression is still being discovered. Several studies have implicated certain circular RNAs in pathophysiological processes within vascular endothelial cells and cancer cells independently. However, to date, no comparative study of circular RNA expression in different types of endothelial cells has been performed and analysed through the lens of their central role in vascular physiology and pathology. In this work, we analysed publicly available and original RNA sequencing datasets from arterial, veinous, and lymphatic endothelial cells to identify common and distinct circRNA expression profiles. We identified 4713 distinct circRNAs in the compared endothelial cell types, 95% of which originated from exons. Interestingly, the results show that the expression profile of circular RNAs is much more specific to each cell type than linear RNAs, and therefore appears to be more suitable for distinguishing between them. As a result, we have discovered a specific circRNA signature for each given endothelial cell type. Furthermore, we identified a specific endothelial cell circRNA signature that is composed four circRNAs: circCARD6, circPLXNA2, circCASC15 and circEPHB4. These circular RNAs are produced by genes that are related to endothelial cell migration pathways and cancer progression. More detailed studies of their functions could lead to a better understanding of the mechanisms involved in physiological and pathological (lymph)angiogenesis and might open new ways to tackle tumour spread through the vascular system.

Axon guidance gene-targeted siRNA delivery system improves neural stem cell transplantation therapy after spinal cord injury

BACKGROUND

Neural stem cells (NSCs) derived from the embryonic spinal cord are excellent candidates for the cellular regeneration of lost neural cells after spinal cord injury (SCI). Semaphorin 3 A (Sema3A) is well known as being implicated in the major axon guidance of the growth cone as a repulsive function during the development of the central nervous system, yet its function in NSC transplantation therapy for SCI has not been investigated. Here, we report for the first time that embryonic spinal cord-derived NSCs significantly express Sema3A in the SCI environment, potentially facilitating inhibition of cell proliferation after transplantation.

METHODS

siRNA-Sema3A was conjugated with poly-l-lysin-coated gold nanoparticles (AuNPs) through a charge interaction process. NSCs were isolated from embryonic spinal cords of rats. Then, the cells were embedded into a dual-degradable hydrogel with the siRNA- Sema3A loaded-AuNPs and transplanted after complete SCI in rats.

RESULTS

The knockdown of Sema3A by delivering siRNA nanoparticles via dual-degradable hydrogels led to a significant increase in cell survival and neuronal differentiation of the transplanted NSCs after SCI. Of note, the knockdown of Sema3A increased the synaptic connectivity of transplanted NSC in the injured spinal cord. Moreover, extracellular matrix molecule and functional recovery were significantly improved in Sema3A-inhibited rats compared to those in rats with only NSCs transplanted.

CONCLUSIONS

These findings demonstrate the important role of Sema3A in NSC transplantation therapy, which may be considered as a future cell transplantation therapy for SCI cases.

Neuropilin-1 interacts with VE-cadherin and TGFBR2 to stabilize adherens junctions and prevent activation of endothelium under flow

Linear and disturbed flow differentially regulate gene expression, with disturbed flow priming endothelial cells (ECs) for a proinflammatory, atheroprone expression profile and phenotype. Here, we investigated the role of the transmembrane protein neuropilin-1 (NRP1) in ECs exposed to flow using cultured ECs, mice with an endothelium-specific knockout of NRP1, and a mouse model of atherosclerosis. We demonstrated that NRP1 was a constituent of adherens junctions that interacted with VE-cadherin and promoted its association with p120 catenin, stabilizing adherens junctions and inducing cytoskeletal remodeling in alignment with the direction of flow. We also showed that NRP1 interacted with transforming growth factor-β (TGF-β) receptor II (TGFBR2) and reduced the plasma membrane localization of TGFBR2 and TGF-β signaling. NRP1 knockdown increased the abundance of proinflammatory cytokines and adhesion molecules, resulting in increased leukocyte rolling and atherosclerotic plaque size. These findings describe a role for NRP1 in promoting endothelial function and reveal a mechanism by which NRP1 reduction in ECs may contribute to vascular disease by modulating adherens junction signaling and promoting TGF-β signaling and inflammation.

The role of sensory and sympathetic nerves in craniofacial bone regeneration

Multiple factors regulate the regeneration of craniofacial bone defects. The nervous system is recognized as one of the critical regulators of bone mass, thereby suggesting a role for neuronal pathways in bone regeneration. However, in the context of craniofacial bone regeneration, little is known about the interplay between the nervous system and craniofacial bone. Sensory and sympathetic nerves interact with the bone through their neuropeptides, neurotransmitters, proteins, peptides, and amino acid derivates. The neuron-derived factors, such as semaphorin 3A (SEMA3A), substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), and vasoactive intestinal peptide (VIP), possess a remarkable role in craniofacial regeneration. This review summarizes the roles of these factors and recently published factors such as secretoneurin (SN) and spexin (SPX) in the osteoblast and osteoclast differentiation, bone metabolism, growth, remodeling and discusses the novel application of nerve-based craniofacial bone regeneration. Moreover, the review will facilitate understanding the mechanism of action and provide potential treatment direction for the craniofacial bone defect.

Regulation of Semaphorin3A in the process of cutaneous wound healing

Semaphorin 3A (Sema3A) has been recognized as a crucial regulator of morphogenesis and homeostasis over a wide range of organ systems. However, its function in cutaneous wound healing is poorly understood. In our study, we demonstrated that Sema3A adenovirus plasmids transfection limited keratinocyte proliferation and decreased migrative capacity as assessed by in vitro wound healing assay. Sema3A transduction inhibited TGF-β1-mediated keratinocyte migration and EMT process. Besides, we applied mice with K14-Cre-mediated deletion of Sema3A and found that Sema3A depletion postponed wound closure with decreased re-epithelialization and matrix growth. Contrary to the results obtained with full-length Sema3A plasmids transfection, increased keratinocyte migration with recombinant Sema3A proteins resulted in quicker closure of the wounding area after a scratch. Further, exogenously applied recombinant Sema3A worked with EGF to maintain the activation of EGFR by interacting with NRP1 and thereby regulated the internalization of the EGFR-NRP1 complex. Taken together, these results indicated a paradoxical role of autonomous and non-autonomous Sema3A expression during wound healing. Combined administration of recombinant EGF and Sema3A proteins could accelerate the process of wound repair, thus providing promising treatment prospects in the future.

Semaphorin 3A: A potential target for prevention and treatment of nickel allergy

Metal allergy is one of the typical immune disorders encountered during the application of dental/medical materials and has a highly complex pathogenic mechanism. Semaphorin 3A (Sema3A), a member of the semaphorin family, is reported to be involved in various immune disorders. However, its role in metal allergy has not been clarified yet. Herein, we show that Sema3A expression was upregulated in nickel (Ni) allergy-induced mouse ear tissue and in NiCl₂-stimulated mouse keratinocytes. Moreover, Sema3A regulated tumor necrosis factor-alpha production and mitogen-activated protein kinase activation in keratinocytes. The specific deletion of Sema3A in keratinocytes did not affect immune cell infiltration but reduced edema and ear swelling; it also impeded Th1 responses to cause a slight alleviation in Ni allergy in mice. Our results demonstrate that Sema3A promotes the development of metal allergy and should be explored as a potential target for the prevention and treatment of metal allergy.

Semaphorin 3A is upregulated in keratinocytes upon nickel exposure, subsequently promoting Th1 cytokine responses and driving nickel allergic reactions.

[Prospects of Drug Therapy of Vestibular Schwannoma]

Vestibular schwannoma (VS) is one of the most common types of benign tumors of the central nervous system. At present, the prevailing treatment methods of VS include surgery, stereotactic radiotherapy, and follow-up observation, etc. However, there is still no drug therapy available for treating VS. Although the surgical technique is relatively mature, the complications cannot be completely avoided. Furthermore, both the growth rate of different cases and patients' sensitivity to radiotherapy vary greatly. With the constant progress made in molecular biology research, most of the studies on the growth mechanism of VS focus on the upstream and downstream of neurofibromin 2 ( NF2) gene and merlin protein, and a number of corresponding targets, including receptor protein tyrosine kinase (RTK), vascular endothelial growth factor receptor (VEGFR), mammalian target of rapamycin complex 1 (mTORC1) and platelet derived growth factor receptor (PDGFR). It has been reported in some studies that quite a few drugs could inhibit the proliferation of VS cells. Most of the studies are still in the stage of in vitro cell experiment and/or animal experiment. A small number of studies have entered phase Ⅰ and phase Ⅱ clinical trials, but have not led to any clinical treatment yet. This paper provides a comprehensive understanding of the current status and the prospects of drug therapies of VS, which is conducive to the development of subsequent research.

Sema3A accelerates bone formation during distraction osteogenesis in mice

Distraction osteogenesis (DO) is a bone regeneration technique used to treat maxillofacial disorders, fracture nonunion, and large bone defects. It is well known for its amazing regenerative potential, but an extended consolidation period limits its clinical use. The interaction between the nervous system and bone regeneration has attracted great attention in recent years. Sema3A is a key axonal chemorepellent which has been proved to have bone-protective effects. In this article, we try to improve DO by local administration of Sema3A and explore the possible mechanisms. Forty wildtype, male, adult mice were divided into two groups after tibia osteotomy surgery. Sema3A or Saline was daily injected transcutaneous into the center of the distraction zone during the consolidation period. Micro-CT images were taken at 4, 6,8 and 10 weeks post-surgery; vascular density and biomechanical testing were performed at 10 weeks post-surgery. We also set up in vitro vessel growth assay to evaluate the effect of Sema3A on angiogenesis. Compared with the Saline group, Sema3A treatment significantly accelerated bone regeneration, improved angiogenesis and callus' biomechanical strength. At 10 weeks post-surgery, compared with the Saline group, the BV/TV, BMD, TMD increased by about 23%, 22%, 18% respectively, vascular density increased by about 49% in the Sema3A group. Histological images and western-blot showed decreased expression of VEGF-A and increased expression of Ang-1 at 4 weeks post-surgery in the Sema3A group. In vitro, Sema3A suppressed VEGF-induced angiogenesis but had little effect on Ang-induced angiogenesis. Conclusion: Sema3A could accelerate bone regeneration and improve angiogenesis during DO.

Human organ rejuvenation by VEGF-A: Lessons from the skin

Transplanting aged human skin onto young SCID/beige mice morphologically rejuvenates the xenotransplants. This is accompanied by angiogenesis, epidermal repigmentation, and substantial improvements in key aging-associated biomarkers, including ß-galactosidase, p16^ink4a, SIRT1, PGC1α, collagen 17A, and MMP1. Angiogenesis- and hypoxia-related pathways, namely, vascular endothelial growth factor A (VEGF-A) and HIF1A, are most up-regulated in rejuvenated human skin. This rejuvenation cascade, which can be prevented by VEGF-A-neutralizing antibodies, appears to be initiated by murine VEGF-A, which then up-regulates VEGF-A expression/secretion within aged human skin. While intradermally injected VEGF-loaded nanoparticles suffice to induce a molecular rejuvenation signature in aged human skin on old mice, VEGF-A treatment improves key aging parameters also in isolated, organ-cultured aged human skin, i.e., in the absence of functional skin vasculature, neural, or murine host inputs. This identifies VEGF-A as the first pharmacologically pliable master pathway for human organ rejuvenation in vivo and demonstrates the potential of our humanized mouse model for clinically relevant aging research.

STAT6 Upregulates NRP1 Expression in Endothelial Cells and Promotes Angiogenesis

The role of signal transducer and activator of transcription 6 (STAT6) in tumor growth has been widely recognized. However, its effects on the regulation of angiogenesis remain unclear. In this study, we found that STAT6 promoted angiogenesis, possibly by increasing the expression of neuropilin-1 (NRP1) in endothelial cells (ECs). Both STAT6 inhibitor (AS1517499) and STAT6 siRNA reduced EC proliferation, migration, and tube-formation, accompanied by downregulation of NRP1, an angiogenesis regulator. Furthermore, IL-13 induced activation of STAT6 and then increased NRP1 expression in ECs. IL-13-induced EC migration and tube formation were inhibited by NRP1 siRNA. Luciferase assay and chromatin immunoprecipitation assay demonstrated that STAT6 could directly bind to human NRP1 promoter and increase the promoter activity. In tumor xenograft models, inhibition of STAT6 reduced xenograft growth, tumor angiogenesis, and NRP1 expression in vivo. Overall, these results clarified the novel mechanism by which STAT6 regulates angiogenesis, and suggested that STAT6 may be a potential target for anti-angiogenesis therapy.

Specific bio-functional CBD-PR1P peptide binding VEGF to collagen hydrogels promotes the recovery of cerebral ischemia in rats

Ischemic stroke was a leading cause of death and long-term disability. It was an effective way to improve cerebral ischemia injury by promoting angiogenesis and neuroprotection. Vascular endothelial growth factor (VEGF) was a potent pro-angiogenic factor, and had neuroprotective effect. A short peptide (PR1P) derived from the extracellular VEGF-binding glycoprotein-Prominin-1 was reported to specifically bind to VEGF. In order to realize sustained release of VEGF, a bio-functional peptide-CBD-PR1P was constructed, which target VEGF to collagen hydrogels to limit the diffusion of VEGF. When the collagen hydrogels loading with CBD-PR1P and VEGF were injected into the cerebral ischemic cortex, increased angiogenesis, decreased apoptosis and enhanced neurons survival were observed in the ischemic area, that promoted the motor functional recovery of cerebral ischemic injury. Thus, this targeting delivery system of VEGF provided a promising therapeutic strategy for cerebral ischemia.

Role of Semaphorins in Ischemic Stroke

Ischemic stroke is one of the major causes of neurological morbidity and mortality in the world. Although the management of ischemic stroke has been improved significantly, it still imposes a huge burden on the health and property. The integrity of the neurovascular unit (NVU) is closely related with the prognosis of ischemic stroke. Growing evidence has shown that semaphorins, a family of axon guidance cues, play a pivotal role in multiple pathophysiological processes in NVU after ischemia, such as regulating the immune system, angiogenesis, and neuroprotection. Modulating the NVU function via semaphorin signaling has a potential to develop a novel therapeutic strategy for ischemic stroke. We, therefore, review recent progresses on the role of semphorin family members in neurons, glial cells and vasculature after ischemic stroke.

Neuropilin 1 regulates bone marrow vascular regeneration and hematopoietic reconstitution

Ionizing radiation and chemotherapy deplete hematopoietic stem cells and damage the vascular niche wherein hematopoietic stem cells reside. Hematopoietic stem cell regeneration requires signaling from an intact bone marrow (BM) vascular niche, but the mechanisms that control BM vascular niche regeneration are poorly understood. We report that BM vascular endothelial cells secrete semaphorin 3 A (SEMA3A) in response to myeloablation and SEMA3A induces p53 - mediated apoptosis in BM endothelial cells via signaling through its receptor, Neuropilin 1 (NRP1), and activation of cyclin dependent kinase 5. Endothelial cell - specific deletion of Nrp1 or Sema3a or administration of anti-NRP1 antibody suppresses BM endothelial cell apoptosis, accelerates BM vascular regeneration and concordantly drives hematopoietic reconstitution in irradiated mice. In response to NRP1 inhibition, BM endothelial cells increase expression and secretion of the Wnt signal amplifying protein, R spondin 2. Systemic administration of anti - R spondin 2 blocks HSC regeneration and hematopoietic reconstitution which otherwise occurrs in response to NRP1 inhibition. SEMA3A - NRP1 signaling promotes BM vascular regression following myelosuppression and therapeutic blockade of SEMA3A - NRP1 signaling in BM endothelial cells accelerates vascular and hematopoietic regeneration in vivo.

bFGF-mediated phosphorylation of δ-catenin increases its protein stability and the ability to induce the nuclear redistribution of β-catenin

Recently, we have shown that δ-catenin strengthened the epidermal growth factor receptor (EGFR)/Erk1/2 signaling pathway through the association between EGFR and δ-catenin. Now, we further analyzed the correlation between basic fibroblast growth factor (bFGF)/fibroblast growth factor receptor 1 (FGFR1) and δ-catenin in prostate cancer and investigated the molecular mechanism underlying the role of bFGF/FGFR1 modulation in CWR22Rv-1 (Rv-1) cells. Here, we demonstrated that bFGF phosphorylated the tyrosine residues of δ-catenin in Rv-1 cells and further proved that the bFGF mediated FGFR1/δ-catenin tyrosine phosphorylation was time dependent. Furthermore, we demonstrated that bFGF stabilized the expression of δ-catenin through weakening its association with GSK3β and enhancing its stability to induce β-catenin into the nuclear by strengthening the processing of E-cadherin. In a word, these results indicated that bFGF/FGFR1 signaling pathway could enhance the tumor progression of prostate cancer via δ-catenin.

New Angiogenic Regulators Produced by TAMs: Perspective for Targeting Tumor Angiogenesis

Simple Summary

Since the targeting of a single pro-angiogenic factor fails to improve oncological disease outcome, significant efforts have been made to identify new pro-angiogenic factors that could compensate for the deficiency of current therapy or act independently as single drugs. Our review aims to present the state-of-the art for well-known and recently described factors produced by macrophages that induce and regulate angiogenesis. A number of positive and negative regulators of angiogenesis in the tumor microenvironment are produced by tumor-associated macrophages (TAMs). Accumulating evidence has indicated that, apart from the well-known angiogenic factors, there are plenty of novel angiogenesis-regulating proteins that belong to different classes. We summarize the data regarding the direct or indirect mechanisms of the interaction of these factors with endothelial cells during angiogenesis. We highlight the recent findings that explain the limitations in the efficiency of current anti-angiogenic therapy approaches.

Abstract

Angiogenesis is crucial to the supply of a growing tumor with nutrition and oxygen. Inhibition of angiogenesis is one of the main treatment strategies for colorectal, lung, breast, renal, and other solid cancers. However, currently applied drugs that target VEGF or receptor tyrosine kinases have limited efficiency, which raises a question concerning the mechanism of patient resistance to the already developed drugs. Tumor-associated macrophages (TAMs) were identified in the animal tumor models as a key inducer of the angiogenic switch. TAMs represent a potent source not only for VEGF, but also for a number of other pro-angiogenic factors. Our review provides information about the activity of secreted regulators of angiogenesis produced by TAMs. They include members of SEMA and S100A families, chitinase-like proteins, osteopontin, and SPARC. The COX-2, Tie2, and other factors that control the pro-angiogenic activity of TAMs are also discussed. We highlight how these recent findings explain the limitations in the efficiency of current anti-angiogenic therapy. Additionally, we describe genetic and posttranscriptional mechanisms that control the expression of factors regulating angiogenesis. Finally, we present prospects for the complex targeting of the pro-angiogenic activity of TAMs.

Myeloid-resident neuropilin-1 promotes choroidal neovascularization while mitigating inflammation

Age-related macular degeneration (AMD) in its various forms is a leading cause of blindness in industrialized countries. Here, we provide evidence that ligands for neuropilin-1 (NRP1), such as Semaphorin 3A and VEGF-A, are elevated in the vitreous of patients with AMD at times of active choroidal neovascularization (CNV). We further demonstrate that NRP1-expressing myeloid cells promote and maintain CNV. Expression of NRP1 on cells of myeloid lineage is critical for mitigating production of inflammatory factors such as IL6 and IL1β. Therapeutically trapping ligands of NRP1 with an NRP1-derived trap reduces CNV. Collectively, our findings identify a role for NRP1-expressing myeloid cells in promoting pathological angiogenesis during CNV and introduce a therapeutic approach to counter neovascular AMD.

Cerebrovascular development: mechanisms and experimental approaches

The cerebral vasculature plays a central role in human health and disease and possesses several unique anatomic, functional and molecular characteristics. Despite their importance, the mechanisms that determine cerebrovascular development are less well studied than other vascular territories. This is in part due to limitations of existing models and techniques for visualisation and manipulation of the cerebral vasculature. In this review we summarise the experimental approaches used to study the cerebral vessels and the mechanisms that contribute to their development.

Neuropilin 1 Regulation of Vascular Permeability Signaling

The vascular endothelium acts as a selective barrier to regulate macromolecule exchange between the blood and tissues. However, the integrity of the endothelium barrier is compromised in an array of pathological settings, including ischemic disease and cancer, which are the leading causes of death worldwide. The resulting vascular hyperpermeability to plasma molecules as well as leukocytes then leads to tissue damaging edema formation and inflammation. The vascular endothelial growth factor A (VEGFA) is a potent permeability factor, and therefore a desirable target for impeding vascular hyperpermeability. However, VEGFA also promotes angiogenesis, the growth of new blood vessels, which is required for reperfusion of ischemic tissues. Moreover, edema increases interstitial pressure in poorly perfused tumors, thereby affecting the delivery of therapeutics, which could be counteracted by stimulating the growth of new functional blood vessels. Thus, targets must be identified to accurately modulate the barrier function of blood vessels without affecting angiogenesis, as well as to develop more effective pro- or anti-angiogenic therapies. Recent studies have shown that the VEGFA co-receptor neuropilin 1 (NRP1) could be playing a fundamental role in steering VEGFA-induced responses of vascular endothelial cells towards angiogenesis or vascular permeability. Moreover, NRP1 is involved in mediating permeability signals induced by ligands other than VEGFA. This review therefore focuses on current knowledge on the role of NRP1 in the regulation of vascular permeability signaling in the endothelium to provide an up-to-date landscape of the current knowledge in this field.

Vascular Permeability: Regulation Pathways and Role in Kidney Diseases

BACKGROUND

Vascular permeability (VP) is a fundamental aspect of vascular biology. A growing number of studies have revealed that many signalling pathways govern VP in both physiological and pathophysiological conditions. Furthermore, emerging evidence identifies VP alteration as a pivotal pathogenic factor in acute kidney injury, chronic kidney disease, diabetic kidney disease, and other proteinuric diseases. Therefore, perceiving the connections between these pathways and the aetiology of kidney disease is an important task as such knowledge may trigger the development of novel therapeutic or preventive medical approaches. In this regard, the discussion summarizing VP-regulating pathways and associating them with kidney diseases is highly warranted.

SUMMARY

Major pathways of VP regulation comprise angiogenic factors including vascular endothelial growth factor/VEGFR, angiopoietin/Tie, and class 3 semaphorin/neuropilin and inflammatory factors including histamine, platelet-activating factor, and leukocyte extravasation. These pathways mainly act on vascular endothelial cadherin to modulate adherens junctions of endothelial cells (ECs), thereby augmenting VP via the paracellular pathway. Elevated VP in diverse kidney diseases involves EC apoptosis, imbalanced regulatory factors, and many other pathophysiological events, which in turn exacerbates renal structural and functional disorders. Measures improving VP effectively ameliorate the diseased kidney in terms of tissue injury, endothelial dysfunction, kidney function, and long-term prognosis. Key Messages: (1) Angiogenic factors, inflammatory factors, and adhesion molecules represent major pathways that regulate VP. (2) Vascular hyperpermeability links various pathophysiological processes and plays detrimental roles in multiple kidney diseases.

Class-3 semaphorins: Potent multifunctional modulators for angiogenesis-associated diseases

Semaphorins, the neuronal guidance cues, were shown to have broad influences on pathophysiological processes such as bone remodeling, immune responses, and angiogenesis. In particular, Class-3 Semaphorins (SEMA3) is considered a vital regulator involved in angiogenesis. Scientific evidence has pointed to the role of angiogenesis in many diseases, and numerous efforts have been made to explore the possibilities of curing those diseases by targeting angiogenesis. Nevertheless, the efficacies are limited owing to the complex mechanisms of angiogenesis. Hence, investigating the mechanisms of SEMA3 in angiogenesis may contribute to novel therapeutics for diseases. Previous reviews mainly focused on the various functions of semaphorins in one particular disease, and the specific angiogenesis mechanism of SEMA3 in diverse diseases has not been well elucidated. Additionally, the role of SEMA3 in angiogenesis remains elusive, as contradicting results have been found in different disease types. Some evidence from recent studies implies that, while most SEMA3 molecules inhibit pathological angiogenesis in different diseases, occasionally SEMA3 may also promote angiogenesis. This review summarizes the specific role of SEMA3 in a variety of angiogenesis-associated diseases, and documents SEMA3 may be a promising therapeutic target for treating angiogenesis-associated diseases.

Semaphorins and Plexins in central nervous system patterning: the key to it all?

Semaphorins and Plexins constitute one of the largest family of guidance molecules and receptors involved in setting critical biological steps for central nervous system development. The role of these molecules in axonal development has been extensively characterized but Semaphorins and Plexins are also involved in a variety of other developmental processes, spanning from cell polarization to migration, laminar segregation and neuronal maturation. In this review, we aim to gather discoveries carried in the field of neurodevelopment over the last decade, during which Semaphorin/Plexin complexes have emerged as key regulators of neurogenesis, neural cell migration and adult gliogenesis. As well, we report mechanisms that brought a better understanding of axonal midline crossing.

A Review of Drug Therapy in Vestibular Schwannoma

Vestibular schwannomas (VSs, also known as acoustic neuromas) are benign intracranial tumors commonly managed with observation, surgery, and radiotherapy. There is currently no approved pharmacotherapy for VS patients, which is why we conducted a detailed search of relevant literature from PubMed and Web of Science to explore recent advances and experiences in drug therapy. VSs feature a long course of disease that requires treatment to have minimal long-term side effects. Conventional chemotherapeutic agents are characterized by neurotoxicity or ototoxicity, poor effect on slow-growing tumors, and may induce new mutations in patients who have lost tumor suppressor function, and therefore are unsuitable for treating VSs. Along with the well-investigated molecular pathophysiology of VS and the increasingly accessible technology such as drug repositioning platform, many molecular targeted inhibitors have been identified and shown certain therapeutic effects in preclinical experiments or clinical trials.

Sphingosine-1-Phosphate Receptor 1 Activity Promotes Tumor Growth by Amplifying VEGF-VEGFR2 Angiogenic Signaling

The vascular endothelial growth factor-A (VEGF-A)-VEGFR2 pathway drives tumor vascularization by activating proangiogenic signaling in endothelial cells (ECs). Here, we show that EC-sphingosine-1-phosphate receptor 1 (S1PR1) amplifies VEGFR2-mediated angiogenic signaling to enhance tumor growth. We show that cancer cells induce S1PR1 activity in ECs, and thereby, conditional deletion of S1PR1 in ECs (EC-S1pr1^−/− mice) impairs tumor vascularization and growth. Mechanistically, we show that S1PR1 engages the heterotrimeric G-protein Gi, which amplifies VEGF-VEGFR2 signaling due to an increase in the activity of the tyrosine kinase c-Abl1. c-Abl1, by phosphorylating VEGFR2 at tyrosine-951, prolongs VEGFR2 retention on the plasmalemma to sustain Rac1 activity and EC migration. Thus, S1PR1 or VEGFR2 antagonists, alone or in combination, reverse the tumor growth in control mice to the level seen in EC-S1pr1^−/− mice. Our findings suggest that blocking S1PR1 activity in ECs has the potential to suppress tumor growth by preventing amplification of VEGF-VEGFR2 signaling.

Vijay Avin et al. demonstrate an essential role of endothelial cell (EC)-S1PR1 signaling in amplifying VEGFR2-mediated tumor growth. S1PR1 by Gi and c-Abl1 phosphorylates VEGFR2 at Y951, which retains VEGFR2 at EC plasmalemma, thus enabling EC migration, tumor angiogenesis, and growth.

Influences of Semaphorin 3A Expression on Clinicopathological Features, Human Papillomavirus Status, and Prognosis in Oropharyngeal Carcinoma

Human papillomavirus (HPV) infection is now identified as a major etiologic factor for oropharyngeal cancer (OPC), and HPV positivity is well established better prognostic marker in OPC. Now, predictable markers for the prognosis of the patients who are stratified by HPV has been investigated in. Semaphorin 3A (SEMA3A) is a well-known axon guidance molecule in the nervous system. It is also known as a tumor suppressor in various cancers. In the present study, we examined the relationships between SEMA3A and clinicopathologic features, especially HPV status, and neoangiogenesis, and its prognostic significance for OPC patients. Thirty-two OPC patients and 17 normal patients were analyzed for SEMA3A expression by immunohistochemical analysis. We also analyzed 22 OPC specimens for CD34 expression as a marker of neoangiogenesis. SEMA3A was significantly downregulated in OPC compared with chronic tonsillitis tissues (p = 0.005). SEMA3A expression was negatively correlated with CD34 expression (r = −0.466, p = 0.033). Moreover, the higher SEMA3A expression cohort showed better survival than the lower SEMA3A expression cohort regardless of HPV status (p = 0.035). These results suggest that SEMA3A expression is a prognostic marker for survival regardless of HPV status and is associated with anti-angiogenesis in OPC.

Hypoxia-induced downregulation of Sema3a and CXCL12/CXCR4 regulate the formation of the coronary artery stem at the proper site

BACKGROUND

During the formation of the coronary artery stem, endothelial strands from the endothelial progenitor pool surrounding the conotruncus penetrate into the aortic wall. Vascular endothelial growth factors (VEGFs) as well as CXCL12/CXCR4 signaling are thought to play a role in the formation of the coronary stem. However, the mechanisms regulating how endothelial strands exclusively invade into the aorta remain unknown.

METHODS AND RESULTS

Immunohistochemistry showed that before the formation of endothelial strands, Sema3a was highly expressed in endothelial progenitors surrounding the great arteries. At the onset of/during invasion of endothelial strands into the aorta, Sema3a was downregulated and CXCR4 was upregulated in the endothelial strands. In situ hybridization showed that Cxcl12 was highly expressed in the aortic wall compared with in the pulmonary artery. Using avian embryonic hearts, we established two types of endothelial penetration assay, in which coronary endothelial strands preferentially invaded into the aorta in culture. Sema3a blocking peptide induced an excess number of endothelial strands penetrating into the pulmonary artery, whereas recombinant Sema3a inhibited the formation of endothelial strands. In cultured coronary endothelial progenitors, recombinant VEGF protein induced CXCR4-positive endothelial strands, which were capable of being attracted by CXCL12-impregnated beads. Monoazo rhodamine detected that hypoxia was predominant in aortic/subaortic region in ovo and hypoxic condition downregulated the expression of Sema3a in culture.

CONCLUSION

Results suggested that hypoxia in the aortic region downregulates the expression of Sema3a, thereby enhancing VEGF activity to induce the formation of CXCR4-positive endothelial strands, which are subsequently attracted into the Cxcl12-positive aortic wall to connect the aortic lumen.

The role of semaphorins in small vessels of the eye and brain

Small vessel diseases, such as ischemic retinopathy and cerebral small vessel disease (CSVD), are increasingly recognized in patients with diabetes, dementia and cerebrovascular disease. The mechanisms of small vessel diseases are poorly understood, but the latest studies suggest a role for semaphorins. Initially identified as axon guidance cues, semaphorins are mainly studied in neuronal morphogenesis, neural circuit assembly, and synapse assembly and refinement. In recent years, semaphorins have been found to play important roles in regulating vascular growth and development and in many pathophysiological processes, including atherosclerosis, angiogenesis after stroke and retinopathy. Growing evidence indicates that semaphorins affect the occurrence, perfusion and regression of both the macrovasculature and microvasculature by regulating the proliferation, apoptosis, migration, barrier function and inflammatory response of endothelial cells, vascular smooth muscle cells (VSMCs) and pericytes. In this review, we concentrate on the regulatory effects of semaphorins on the cell components of the vessel wall and their potential roles in microvascular diseases, especially in the retina and cerebral small vessel. Finally, we discuss potential molecular approaches in targeting semaphorins as therapies for microvascular disorders in the eye and brain.

Semaphorins in Angiogenesis and Autoimmune Diseases: Therapeutic Targets?

The axonal guidance molecules, semaphorins, have been described to function both physiologically and pathologically outside of the nervous system. In this review, we focus on the vertebrate semaphorins found in classes 3 through 7 and their roles in vascular development and autoimmune diseases. Recent studies indicate that while some of these vertebrate semaphorins promote angiogenesis, others have an angiostatic function. Since some semaphorins are also expressed by different immune cells and are known to modulate immune responses, they have been implicated in autoimmune disorders such as multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis. We conclude this review by addressing strategies targeting semaphorins as potential therapeutic agents for angiogenesis and autoimmune diseases.

Endothelial Semaphorin 3F Maintains Endothelial Barrier Function and Inhibits Monocyte Migration

In normal physiology, endothelial cells (ECs) form a vital barrier between the blood and underlying tissue controlling leukocyte diapedesis and vascular inflammation. Emerging data suggest that neuronal guidance cues, typically expressed during development, have roles outside the nervous system in vascular biology and immune responses. In particular, Class III semaphorins have been reported to affect EC migration and angiogenesis. While ECs express high levels of semaphorin 3F (SEMA3F), little is known about its function in mature ECs. Here we show that SEMA3F expression is reduced by inflammatory stimuli and increased by laminar flow. Endothelial cells exposed to laminar flow secrete SEMA3F, which subsequently binds to heparan sulfates on the surface of ECs. However, under pro-inflammatory conditions, reduced levels of SEMA3F make ECs more prone to monocyte diapedesis and display impaired barrier function as measured with an electric cell-substrate impedance sensing system and a microfluidic system. In addition, we demonstrate that SEMA3F can directly inhibit the migration of activated monocytes. Taken together, our data suggest an important homeostatic function for EC-expressed SEMA3F, serving as a mediator of endothelial quiescence.

Neuropilin: Handyman and Power Broker in the Tumor Microenvironment

Neuropilin-1 and neuropilin-2 form a small family of transmembrane receptors, which, due to the lack of a cytosolic protein kinase domain, act primarily as co-receptors for various ligands. Performing at the molecular level both the executive and organizing functions of a handyman as well as of a power broker, they are instrumental in controlling the signaling of various receptor tyrosine kinases, integrins, and other molecules involved in the regulation of physiological and pathological angiogenic processes. In this setting, the various neuropilin ligands and interaction partners on various cells of the tumor microenvironment, such as cancer cells, endothelial cells, cancer-associated fibroblasts, and immune cells, are surveyed. The suitability of various neuropilin-targeting substances and the intervention in neuropilin-mediated interactions is considered as a possible building block of tumor therapy.

Anti-Nogo-A antibodies prevent vascular leakage and act as pro-angiogenic factors following stroke

Angiogenesis is a key restorative process following stroke but has also been linked to increased vascular permeability and blood brain barrier (BBB) disruption. Previous pre-clinical approaches primarily focused on the administration of vascular endothelial growth factor (VEGF) to promote vascular repair after stroke. Although shown to improve angiogenesis and functional recovery from stroke, VEGF increased the risk of blood brain barrier disruption and bleedings to such an extent that its clinical use is contraindicated. As an alternative strategy, antibodies against the neurite growth inhibitory factor Nogo-A have recently been shown to enhance vascular regeneration in the ischemic central nervous system (CNS); however, their effect on vascular permeability is unknown. Here, we demonstrate that antibody-mediated Nogo-A neutralization following stroke has strong pro-angiogenic effects but does not increase vascular permeability as opposed to VEGF. Moreover, VEGF-induced vascular permeability was partially prevented when VEGF was co-administered with anti-Nogo-A antibodies. This study may provide a novel therapeutic strategy for vascular repair and maturation in the ischemic brain.

Sema3a-Nrp1 Signaling Mediates Fast-Twitch Myofiber Specificity of Tw2+ Cells

We previously identified a unique population of interstitial muscle progenitors, marked by expression of the Twist2 transcription factor, which fuses specifically to type IIb/x fast-twitch myofibers. Tw2⁺ progenitors are distinct from satellite cells, a muscle progenitor that expresses Pax7 and contributes to all myofiber types. Through RNA sequencing and immunofluorescence, we identify the membrane receptor, Nrp1, as a marker of Tw2⁺ cells but not Pax7⁺ cells. We also found that Sema3a, a chemorepellent ligand for Nrp1, is expressed by type I and IIa myofibers but not IIb myofibers. Using stripe migration assays, chimeric cell-cell fusion assays, and a Sema3a transgenic mouse model, we identify Sema3a-Nrp1 signaling as a major mechanism for Tw2⁺ cell fiber-type specificity. Our findings reveal an extracellular signaling mechanism whereby a cell-surface receptor for a chemorepellent confers specificity of intercellular fusion of a specific muscle progenitor with its target tissue.

A rationally designed NRP1-independent superagonist SEMA3A mutant is an effective anticancer agent

Vascular normalizing strategies, aimed at ameliorating blood vessel perfusion and lessening tissue hypoxia, are treatments that may improve the outcome of cancer patients. Secreted class 3 semaphorins (SEMA3), which are thought to directly bind neuropilin (NRP) co-receptors that, in turn, associate with and elicit plexin (PLXN) receptor signaling, are effective normalizing agents of the cancer vasculature. Yet, SEMA3A was also reported to trigger adverse side effects via NRP1. We rationally designed and generated a safe, parenterally deliverable, and NRP1-independent SEMA3A point mutant isoform that, unlike its wild-type counterpart, binds PLXNA4 with nanomolar affinity and has much greater biochemical and biological activities in cultured endothelial cells. In vivo, when parenterally administered in mouse models of pancreatic cancer, the NRP1-independent SEMA3A point mutant successfully normalized the vasculature, inhibited tumor growth, curbed metastatic dissemination, and effectively improved the supply and anticancer activity of chemotherapy. Mutant SEMA3A also inhibited retinal neovascularization in a mouse model of age-related macular degeneration. In summary, mutant SEMA3A is a vascular normalizing agent that can be exploited to treat cancer and, potentially, other diseases characterized by pathological angiogenesis.

The Prognostic Value of Serum Semaphorin3A and VEGF Levels in Patients with Metastatic Colorectal Cancer

PURPOSE

Despite new treatment options in metastatic colorectal cancer (mCRC), new prognostic markers are still needed to determine optimal chemoregimen especially for anti-angiogenesis drugs. In this study, we evaluated the serum semaphorin and VEGF-A levels as prognostic factors in patients with mCRC.

METHODS

Patients with diagnosed mCRC who were treated with first-line bevacizumab plus chemotherapy were included in the study. Venous blood samples of 37 patients with metastatic colon cancer were taken, and serum semaphorin 3A and VEGF-A levels were studied in pre-treatment and the 1st and third months after the treatment was initiated.

RESULTS

Totally, 37 patients were enrolled in the study. The patients' mean age was 62 years. Twenty-eight (49%) of the patients were male, and 19 (51%) were female. Serum semaphorin3A (sema3A) levels of the patients were 5.4 ± 7.4 ng/ml before the treatment, 3.5 ± 3.3 ng/ml at the first month, and 3.5 ± 3.7 ng/ml at the third month. Serum VEGF-A levels were 27.7 ± 32.9 ng/l before the treatment, 23.1 ± 28.1 ng/l at the first month, and 28.9 ± 30.2 ng/l at the third month. There was no significant correlation between the survival and pre-treatment VEGF-A level (p = 0.064). Overall survival (OS) was statistically significantly higher in patients with pre-treatment semaphorin 3A levels below 5.4 ng/ml than higher than 5.4 ng/ml (10.5 months vs 4.5 months, respectively, HR 0.23, 95% CI 19.635-11,391, p = 0.012).

CONCLUSION

Pre-treatment semaphorin 3A level can be a prognostic marker for the mCRC patients who were treated with bevacizumab in patients with metastatic colorectal cancer.

Semaphorin-3A inhibits multiple myeloma progression in a mouse model

Previous studies revealed that progression of multiple myeloma (MM) is associated with downregulation of semaphorin-3A (sema3A) expression in bone marrow endothelial cells. We therefore determined if serum sema3A concentrations are correlated with MM progression and if sema3A can affect MM progression. We find that the concentration of sema3A in sera of MM patients is strongly reduced and that the decrease is correlated with disease progression. A similar depletion is found in patients having acute myeloid leukemia and acute lymphoblastic leukemia but not in cancer forms that do not involve the bone marrow such as in colon cancer. Expression of a modified sema3A [furin-resistant sema3A (FR-sema3A)] stabilized against cleavage by furin-like proprotein convertases in CAG MM cells did not affect their behavior in-vitro. CAG cells injected into the tail vein of severe combined immunodeficient (SCID) mice home to the bone marrow and proliferate, mimicking MM disease progression. Disease progression in mice injected with CAG cells expressing FR-sema3A was inhibited, resulting in prolonged survival and a lower incidence of bone lesions. Histological examination and fluorescence-activated cell sorting analysis revealed that FR-sema3A expression reduced the infiltration of the CAG cells into the bone marrow, reduced bone marrow necrosis and reduced angiogenesis induced by the MM cells in the bone marrow. Our results suggest that measurement of sema3A serum concentrations may be of use for the diagnosis and for the monitoring of malignancies of the bone marrow such as MM. Furthermore, our results suggest that FR-sema3A may perhaps find use as an inhibitor of MM disease progression.

Semaphorin 3A Contributes to Secondary Blood-Brain Barrier Damage After Traumatic Brain Injury

Semaphorin 3A (SEMA3A) is a member of the Semaphorins family, a class of membrane-associated protein that participates in the construction of nerve networks. SEMA3A has been reported to affect vascular permeability previously, but its influence in traumatic brain injury (TBI) is still unknown. To investigate the effects of SEMA3A, we used a mouse TBI model with a controlled cortical impact (CCI) device and a blood–brain barrier (BBB) injury model in vitro with oxygen-glucose deprivation (OGD). We tested post-TBI changes in SEMA3A, and its related receptors (Nrp-1 and plexin-A1) expression and distribution through western blotting and double-immunofluorescence staining, respectively. Neurological outcomes were evaluated by modified neurological severity scores (mNSSs) and beam-walking test. We examined BBB damage through Evans Blue dye extravasation, brain water content, and western blotting for VE-cadherin and p-VE-cadherin in vivo, and we examined the endothelial cell barrier through hopping probe ion conductance microscopy (HPICM), transwell leakage, and western blotting for VE-cadherin and p-VE-cadherin in vitro. Changes in miR-30b-5p were assessed by RT-PCR. Finally, the neuroprotective function of miR-30b-5p is measured by brain water content, mNSSs and beam-walking test. SEMA3A expression varied following TBI and peaked on the third day which expressed approximate fourfold increase compared with sham group, with the protein concentrated at the lesion boundary. SEMA3A contributed to neurological function deficits and secondary BBB damage in vivo. Our results demonstrated that SEMA3A level following OGD injury almost doubled than control group, and the negative effects of OGD injury can be improved by blocking SEMA3A expression. Furthermore, the expression of miR-30b-5p decreased approximate 40% at the third day and 60% at the seventh day post-CCI. OGD injury also exhibited an effect to approximately decrease 50% of miR-30b-5p expression. Additionally, the expression of SEMA3A post-TBI is regulated by miR-30b-5p, and miR-30b-5p could improve neurological outcomes post-TBI efficiently. Our results demonstrate that SEMA3A is a significant factor in secondary BBB damage after TBI and can be abolished by miR-30b-5p, which represents a potential therapeutic target.

Semaphorin 3A Is Effective in Reducing Both Inflammation and Angiogenesis in a Mouse Model of Bronchial Asthma

Semaphorin 3A (sema3A) belongs to the sub-family of the immune semaphorins that function as regulators of immune-mediated inflammation. Sema3A is a membrane associated molecule on T regulatory cells and on B regulatory cells. Being transiently ligated to the cell surface of these cells it is suggested to be a useful marker for evaluating their functional status. In earlier studies, we found that reduced sema3A concentration in the serum of asthma patients as well as reduced expression by Treg cells correlates with asthma disease severity. Stimulation of Treg cells with recombinant sema3A induced a significant increase in FoxP3 and IL-10 expression. To find out if sema3A can be of benefit to asthma patients, we evaluated the effect of sema3A injection in a mouse model of asthma. BALB\c-mice were sensitized using ovalbumin (OVA) + adjuvant for 15 days followed by OVA aerosol inhalation over five consecutive days. Four hours following air ways sensitization on each of the above days- 15 of these mice were injected intraperitoneally with 50 μg per mouse of recombinant human sema3A-FR and the remaining 15 mice were injected with a similarly purified vehicle. Five days later the mice were sacrificed, broncheo-alveolar lavage (BAL) was collected and formalin-fixed lung biopsies taken and analyzed. In sema3A treated mice, only 20% of the bronchioles and arterioles were infiltrated by inflammatory cells as compared to 90% in the control group (p = 0.0079). In addition, eosinophil infiltration was also significantly increased in the control group as compared with the sema3A treated mice. In sema3A treated mice we noticed only a small number of mononuclear and neutrophil cells in the BAL while in the control mice, the BAL was enriched with mononuclear and neutrophil cells. Finally, in the control mice, angiogenesis was significantly increased in comparison with sema3A treated mice as evidenced by the reduced concentration of microvessels in the lungs of sema3A treated mice. To conclude, we find that in this asthma model, sema3A functions as a potent suppressor of asthma related inflammation that has the potential to be further developed as a new therapeutic for the treatment of asthma.

iRGD synergizes with PD-1 knockout immunotherapy by enhancing lymphocyte infiltration in gastric cancer

Poor infiltration of activated lymphocytes into tumors represents a fundamental factor limiting the therapeutic effect of adoptive cell immunotherapy. A tumor-penetrating peptide, iRGD, has been widely used to deliver drugs into tumor tissues. In this study, we demonstrate for the first time that iRGD could also facilitate the infiltration of lymphocytes in both 3D tumor spheroids and several xenograft mouse models. In addition, combining iRGD modification with PD-1 knockout lymphocytes reveals a superior anti-tumor efficiency. Mechanistic studies demonstrate that the binding of iRGD to neuropilin-1 results in tyrosine phosphorylation of the endothelial barrier regulator VE-cadherin, which plays a role in the opening of endothelial cell contacts and the promotion of transendothelial lymphocyte migration. In summary, these results demonstrate that iRGD modification could promote tumor-specific lymphocyte infiltration, and thereby overcome the bottleneck associated with adoptive immune cell therapy in solid tumors.

The therapeutic efficacy of adoptive T cell transfer is limited by their ability to infiltrate solid tumours. Here, the authors show that loading the tumor penetrating cyclic peptide iRGD on the cell surface of T cells enhances their ability to penetrate the tumour, resulting in enhanced efficacy in a mouse model of gastric cancer.

Neuropilins in the Context of Tumor Vasculature

Neuropilin-1 and Neuropilin-2 form a small family of plasma membrane spanning receptors originally identified by the binding of semaphorin and vascular endothelial growth factor. Having no cytosolic protein kinase domain, they function predominantly as co-receptors of other receptors for various ligands. As such, they critically modulate the signaling of various receptor tyrosine kinases, integrins, and other molecules involved in the regulation of physiological and pathological angiogenic processes. This review highlights the diverse neuropilin ligands and interacting partners on endothelial cells, which are relevant in the context of the tumor vasculature and the tumor microenvironment. In addition to tumor cells, the latter contains cancer-associated fibroblasts, immune cells, and endothelial cells. Based on the prevalent neuropilin-mediated interactions, the suitability of various neuropilin-targeted substances for influencing tumor angiogenesis as a possible building block of a tumor therapy is discussed.

Class-3 Semaphorins and Their Receptors: Potent Multifunctional Modulators of Tumor Progression

Semaphorins are the products of a large gene family containing 28 genes of which 21 are found in vertebrates. Class-3 semaphorins constitute a subfamily of seven vertebrate semaphorins which differ from the other vertebrate semaphorins in that they are the only secreted semaphorins and are distinguished from other semaphorins by the presence of a basic domain at their C termini. Class-3 semaphorins were initially characterized as axon guidance factors, but have subsequently been found to regulate immune responses, angiogenesis, lymphangiogenesis, and a variety of additional physiological and developmental functions. Most class-3 semaphorins transduce their signals by binding to receptors belonging to the neuropilin family which subsequently associate with receptors of the plexin family to form functional class-3 semaphorin receptors. Recent evidence suggests that class-3 semaphorins also fulfill important regulatory roles in multiple forms of cancer. Several class-3 semaphorins function as endogenous inhibitors of tumor angiogenesis. Others were found to inhibit tumor metastasis by inhibition of tumor lymphangiogenesis, by direct effects on the behavior of tumor cells, or by modulation of immune responses. Notably, some semaphorins such as sema3C and sema3E have also been found to potentiate tumor progression using various mechanisms. This review focuses on the roles of the different class-3 semaphorins in tumor progression.

Neuropilin-1 maintains dimethylarginine dimethylaminohydrolase 1 expression in endothelial cells, and contributes to protection from angiotensin II-induced hypertension

Dimethylarginine dimethylaminohydrolases (DDAHs) are known to degrade asymmetric dimethylarginine, an endogenous inhibitor of NOS, and maintain vascular homeostasis; however, the regulatory pathways of DDAHs remain unclear. In this study, we aimed to define the role of transmembrane glycoprotein neuropilin-1 (NRP1) in the expression of DDAHs and investigate the potential roles of NRP1 in regulation of blood pressure. Short hairpin RNA-mediated knockdown of NRP1 reduced the level and mRNA stability of DDAH1 but not DDAH2 in HUVECs, whereas overexpression of NRP1 increased the mRNA stability of DDAH1. Meanwhile, mesenteric arteries and lung vascular endothelial cells of tamoxifen-inducible endothelial cell-specific NRP1 knockout mice exhibited decreased expression of DDAH1 and slightly increased expression of DDAH2. Mechanistically, the regulation of NRP1 on DDAH1 expression is mediated by a posttranscriptional mechanism involving miR-219-5p in HUVECs. Although the endothelial cell-specific NRP1 knockout mice did not exhibit any significant change in blood pressure at the basal level, they were more sensitive to low-dose angiotensin II infusion-induced increases in blood pressure. Our results show that NRP1 is required for full expression of DDAH1 in endothelial cells and that NRP1 contributes to protection from low-dose angiotensin II-induced increases in blood pressure.-Wang, Y., Wang, E., Zhang, Y., Madamsetty, V. S., Ji, B., Radisky, D. C., Grande, J. P., Misra, S., Mukhopadhyay, D. Neuropilin-1 maintains dimethylarginine dimethylaminohydrolase 1 expression in endothelial cells, and contributes to protection from angiotensin II-induced hypertension.