Alternatively spliced vascular endothelial growth factor receptor-2 is an essential endogenous inhibitor of lymphatic vessel growth

An Atypical Cause of a Child Limp: A Gorham-Stout Disease with a Vanishing Hip

Gorham-Stout disease (GSD) is a rare bone disease characterized by an abnormal proliferation of endothelial-lined vessels and destruction of the affected bone. As it affects commonly children and young adults, it is associated with significant morbidity and mortality. To date, there is no established treatment strategy for GSD. We report through this observation a rare case of GSD in a child located in the hip and the iliac crest.

New targets of nascent lymphatic vessels in ocular diseases

Recent advancements in the field of endothelial markers of lymphatic vessels and lymphangiogenic factors have shed light on the association between several ocular diseases and ocular nascent lymphatic vessels. The immune privilege of corneal tissue typically limits the formation of lymphatic vessels in a healthy eye. However, vessels in the eyes can potentially undergo lymphangiogenesis and be conditionally activated. It is evident that nascent lymphatic vessels in the eyes contribute to various ocular pathologies. Conversely, lymphatic vessels are present in the corneal limbus, ciliary body, lacrimal glands, optic nerve sheaths, and extraocular muscles, while a lymphatic vasculature-like system exists in the choroid, that can potentially cause several ocular pathologies. Moreover, numerous studies indicate that many ocular diseases can influence or activate nascent lymphatic vessels, ultimately affecting patient prognosis. By understanding the mechanisms underlying the onset, development, and regression of ocular nascent lymphatic vessels, as well as exploring related research on ocular diseases, this article aims to offer novel perspectives for the treatment of such conditions.

UV light-mediated corneal crosslinking as (lymph)angioregressive pretreatment to promote graft survival after subsequent high-risk corneal transplantation (CrossCornealVision): protocol for a multicenter, randomized controlled trial

BACKGROUND

Good vision highly depends on the transparency of the cornea, which is the "windscreen" of the eye. In fact, corneal blindness due to transparency loss is the second most common cause of blindness worldwide, and corneal transplantation is the main cure. Importantly, the cornea is normally avascular but can secondarily be invaded by pathological (blood and lymphatic) vessels due to severe inflammation, and the survival prognosis of a corneal graft mainly depends on the preoperative vascular condition of the recipient's cornea. Whereas transplants placed into avascular recipient beds enjoy long-term survival rates of > 90%, survival rates significantly decrease in pathologically pre-vascularized, so-called high-risk recipients, which account for around 10% of all performed transplants in Germany and > 75% in lower and middle-income countries worldwide.

METHODS

This parallel-grouped, open-randomized, multicenter, prospective controlled exploratory investigator-initiated trial (IIT) intends to improve graft survival by preconditioning pathologically vascularized recipient corneas by (lymph)angioregressive treatment before high-risk corneal transplantation. For this purpose, corneal crosslinking (CXL) will be used, which has been shown to potently regress corneal blood and lymphatic vessels. Prior to transplantation, patients will be randomized into 2 groups: (1) CXL (intervention) or (2) no pretreatment (control). CXL will be repeated once if insufficient reduction of corneal neovascularization should be observed. All patients (both groups) will then undergo corneal transplantation. In the intervention group, remaining blood vessels will be additionally regressed using fine needle diathermy (on the day of transplantation). Afterwards, the incidence of graft rejection episodes will be evaluated for 24 months (primary endpoint). Overall graft survival, as well as regression of corneal vessels and/or recurrence, among other factors, will be analyzed (secondary endpoints).

DISCUSSION

Based on preclinical and early pilot clinical evidence, we want to test the novel concept of temporary (lymph)angioregressive pretreatment of high-risk eyes by CXL to promote subsequent corneal graft survival. So far, there is no evidence-based approach to reliably improve graft survival in the high-risk corneal transplantation setting available in clinical routine. If successful, this approach will be the first to promote graft survival in high-risk transplants. It will significantly improve vision and quality of life in patients suffering from corneal blindness.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05870566. Registered on 22 May 2023.

The VEGFs/VEGFRs system in Alzheimer's and Parkinson's diseases: Pathophysiological roles and therapeutic implications

The vascular endothelial growth factors (VEGFs) and their cognate receptors (VEGFRs), besides their well-known involvement in physiological angiogenesis/lymphangiogenesis and in diseases associated to pathological vessel formation, play multifaceted functions in the central nervous system (CNS). In addition to shaping brain development, by controlling cerebral vasculogenesis and regulating neurogenesis as well as astrocyte differentiation, the VEGFs/VEGFRs axis exerts essential functions in the adult brain both in physiological and pathological contexts. In this article, after describing the physiological VEGFs/VEGFRs functions in the CNS, we focus on the VEGFs/VEGFRs involvement in neurodegenerative diseases by reviewing the current literature on the rather complex VEGFs/VEGFRs contribution to the pathogenic mechanisms of Alzheimer's (AD) and Parkinson's (PD) diseases. Thereafter, based on the outcome of VEGFs/VEGFRs targeting in animal models of AD and PD, we discuss the factual relevance of pharmacological VEGFs/VEGFRs modulation as a novel and potential disease-modifying approach for these neurodegenerative pathologies. Specific VEGFRs targeting, aimed at selective VEGFR-1 inhibition, while preserving VEGFR-2 signal transduction, appears as a promising strategy to hit the molecular mechanisms underlying AD pathology. Moreover, therapeutic VEGFs-based approaches can be proposed for PD treatment, with the aim of fine-tuning their brain levels to amplify neurotrophic/neuroprotective effects while limiting an excessive impact on vascular permeability.

Neuron-specific deletion of VEGF or its receptor Flk-1 occludes the antidepressant-like effects of desipramine and fluoxetine in mice

Vascular endothelial growth factor (VEGF) signaling is known to be involved in the antidepressant-like effects of conventional antidepressants, such as desipramine (DMI), a tricyclic antidepressant, and fluoxetine (FLX), a selective serotonin reuptake inhibitor; however, the precise role of neuronal VEGF signaling in mediating these effects remains unclear. Using mice with excitatory neuron-specific deletion of VEGF and its receptor, fetal liver kinase 1 (Flk-1) in the forebrain, we examined the effects of forebrain excitatory neuron-specific deletion of VEGF or Flk-1 on the antidepressant-like effects of repeated DMI and chronic FLX administration in the forced swim test (FST). Repeated intraperitoneal (i.p.) injections of DMI (10, 10, and 20 mg/kg at 24, 4, and 1 h before the FST, respectively) significantly decreased immobility in control mice; however, this effect was completely blocked in mice with neuron-specific VEGF or Flk-1 deletion. Although chronic treatment with FLX (18 mg/kg/day, i.p.) did not impact immobility in control mice 1 day after the 22nd injection, immobility was significantly reduced 1 day after the preswim and the 23rd FLX injection. However, in mice with neuron-specific Flk-1 deletion, chronic FLX treatment significantly increased immobility in the preswim and failed to produce antidepressant-like effects. Collectively, these findings indicate that neuronal VEGF-Flk-1 signaling contributes to the antidepressant-like actions of conventional antidepressants.

Up-to-date molecular medicine strategies for management of ocular surface neovascularization

Ocular surface neovascularization and its resulting pathological changes significantly alter corneal refraction and obstruct the light path to the retina, and hence is a major cause of vision loss. Various factors such as infection, irritation, trauma, dry eye, and ocular surface surgery trigger neovascularization via angiogenesis and lymphangiogenesis dependent on VEGF-related and alternative mechanisms. Recent advances in antiangiogenic drugs, nanotechnology, gene therapy, surgical equipment and techniques, animal models, and drug delivery strategies have provided a range of novel therapeutic options for the treatment of ocular surface neovascularization. In this review article, we comprehensively discuss the etiology and mechanisms of corneal neovascularization and other types of ocular surface neovascularization, as well as emerging animal models and drug delivery strategies that facilitate its management.

Single-cell RNA transcriptome landscape of murine liver following systemic administration of mesoporous silica nanoparticles

Due to the unique physicochemical properties, mesoporous silica nanoparticles (MONs) have been widely utilized in biomedical fields for drug delivery, gene therapy, disease diagnosis and imaging. With the extensive applications and large-scale production of MONs, the potential effects of MONs on human health are gaining increased attention. To better understand the cellular and molecular mechanisms underlying the effects of MONs on the mouse liver, we profiled the transcriptome of 63,783 single cells from mouse livers following weekly intravenous administration of MONs for 2 weeks. The results showed that the proportion of endothelial cells and CD4+ T cells was increased, whereas that of Kupffer cells was decreased, in a dose-dependent manner after MONs treatment in the mouse liver. We also observed that the proportion of inflammation-related Kupffer cell subtype and wound healing-related hepatocyte subtype were elevated, but the number of hepatocytes with detoxification characteristics was reduced after MONs treatment. The cell-cell communication network revealed that there was more crosstalk between cholangiocytes and Kupffer cells, liver capsular macrophages, hepatic stellate cells, and endothelial cells following MONs treatment. Furthermore, we identified key ligand-receptor pairs between crucial subtypes after MONs treatment that are known to promote liver fibrosis. Collectively, our study explored the effects of MONs on mouse liver at a single-cell level and provides comprehensive information on the potential hepatotoxicity of MONs.

The novel role of lymphatic vessels in the pathogenesis of ocular diseases

Historically, the eye has been considered as an organ free of lymphatic vessels. In recent years, however, it became evident, that lymphatic vessels or lymphatic-like vessels contribute to several ocular pathologies at various peri- and intraocular locations. The aim of this review is to outline the pathogenetic role of ocular lymphatics, the respective molecular mechanisms and to discuss current and future therapeutic options based thereon. We will give an overview on the vascular anatomy of the healthy ocular surface and the molecular mechanisms contributing to corneal (lymph)angiogenic privilege. In addition, we present (i) current insights into the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea triggered e.g. by inflammation or trauma, (ii) the role of lymphatic vessels in different ocular surface pathologies such as dry eye disease, corneal graft rejection, ocular graft versus host disease, allergy, and pterygium, (iii) the involvement of lymphatic vessels in ocular tumors and metastasis, and (iv) the novel role of the lymphatic-like structure of Schlemm's canal in glaucoma. Identification of the underlying molecular mechanisms and of novel modulators of lymphangiogenesis will contribute to the development of new therapeutic targets for the treatment of ocular diseases associated with pathological lymphangiogenesis in the future. The preclinical data presented here outline novel therapeutic concepts for promoting transplant survival, inhibiting metastasis of ocular tumors, reducing inflammation of the ocular surface, and treating glaucoma. Initial data from clinical trials suggest first success of novel treatment strategies to promote transplant survival based on pretransplant corneal lymphangioregression.

Targeted splicing therapy: new strategies for colorectal cancer

RNA splicing is the process of forming mature mRNA, which is an essential phase necessary for gene expression and controls many aspects of cell proliferation, survival, and differentiation. Abnormal gene-splicing events are closely related to the development of tumors, and the generation of oncogenic isoform in splicing can promote tumor progression. As a main process of tumor-specific splicing variants, alternative splicing (AS) can promote tumor progression by increasing the production of oncogenic splicing isoforms and/or reducing the production of normal splicing isoforms. This is the focus of current research on the regulation of aberrant tumor splicing. So far, AS has been found to be associated with various aspects of tumor biology, including cell proliferation and invasion, resistance to apoptosis, and sensitivity to different chemotherapeutic drugs. This article will review the abnormal splicing events in colorectal cancer (CRC), especially the tumor-associated splicing variants arising from AS, aiming to offer an insight into CRC-targeted splicing therapy.

Interaction Between Blood Vasculatures and Lymphatic Vasculatures During Inflammation

Physiological activity cannot be regulated without the blood and lymphatic vasculatures, which play complementary roles in maintaining the body's homeostasis and immune responses. Inflammation is the body's initial response to pathological injury and is responsible for protecting the body, removing damaged tissues, and restoring and maintaining homeostasis in the body. A growing number of researches have shown that blood and lymphatic vessels play an essential role in a variety of inflammatory diseases. In the inflammatory state, the permeability of blood vessels and lymphatic vessels is altered, and angiogenesis and lymphangiogenesis subsequently occur. The blood vascular and lymphatic vascular systems interact to determine the development or resolution of inflammation. In this review, we discuss the changes that occur in the blood vascular and lymphatic vascular systems of several organs during inflammation, describe the different scenarios of angiogenesis and lymphangiogenesis at different sites of inflammation, and demonstrate the prospect of targeting the blood vasculature and lymphatic vasculature systems to limit the development of inflammation and promote the resolution of inflammation in inflammatory diseases.

A Soluble Platelet-Derived Growth Factor Receptor-β Originates via Pre-mRNA Splicing in the Healthy Brain and Is Upregulated during Hypoxia and Aging

The platelet-derived growth factor-BB (PDGF-BB) pathway provides critical regulation of cerebrovascular pericytes, orchestrating their investment and retention within the brain microcirculation. Dysregulated PDGF Receptor-beta (PDGFRβ) signaling can lead to pericyte defects that compromise blood-brain barrier (BBB) integrity and cerebral perfusion, impairing neuronal activity and viability, which fuels cognitive and memory deficits. Receptor tyrosine kinases such as PDGF-BB and vascular endothelial growth factor-A (VEGF-A) are often modulated by soluble isoforms of cognate receptors that establish signaling activity within a physiological range. Soluble PDGFRβ (sPDGFRβ) isoforms have been reported to form by enzymatic cleavage from cerebrovascular mural cells, and pericytes in particular, largely under pathological conditions. However, pre-mRNA alternative splicing has not been widely explored as a possible mechanism for generating sPDGFRβ variants, and specifically during tissue homeostasis. Here, we found sPDGFRβ protein in the murine brain and other tissues under normal, physiological conditions. Utilizing brain samples for follow-on analysis, we identified mRNA sequences corresponding to sPDGFRβ isoforms, which facilitated construction of predicted protein structures and related amino acid sequences. Human cell lines yielded comparable sequences and protein model predictions. Retention of ligand binding capacity was confirmed for sPDGFRβ by co-immunoprecipitation. Visualizing fluorescently labeled sPDGFRβ transcripts revealed a spatial distribution corresponding to murine brain pericytes alongside cerebrovascular endothelium. Soluble PDGFRβ protein was detected throughout the brain parenchyma in distinct regions, such as along the lateral ventricles, with signals also found more broadly adjacent to cerebral microvessels consistent with pericyte labeling. To better understand how sPDGFRβ variants might be regulated, we found elevated transcript and protein levels in the murine brain with age, and acute hypoxia increased sPDGFRβ variant transcripts in a cell-based model of intact vessels. Our findings indicate that soluble isoforms of PDGFRβ likely arise from pre-mRNA alternative splicing, in addition to enzymatic cleavage mechanisms, and these variants exist under normal physiological conditions. Follow-on studies will be needed to establish potential roles for sPDGFRβ in regulating PDGF-BB signaling to maintain pericyte quiescence, BBB integrity, and cerebral perfusion-critical processes underlying neuronal health and function, and in turn, memory and cognition.

Circulating Biomarkers in Patients With Locally Advanced or Metastatic Renal Cell Carcinoma Treated With Everolimus in the Pre-nephrectomy Setting

Many drugs are available in renal cell carcinoma (RCC), yet clinicians are still looking for predictive biomarkers of disease recurrence or progression supporting more personalised treatments. An assessment of circulating biomarkers over time was carried out in this French, open-label, single-arm, multicentre trial conducted in 25 patients with either locally advanced (n = 14) or metastatic RCC (n = 11) who received everolimus (10 mg daily) for 6 weeks prior to nephrectomy (NEORAD, NCT01715935). Circulating biomarkers, including circulating tumour cells, haematopoietic and endothelial cells, plasma angiogenesis and inflammatory markers were quantified at baseline, upon everolimus and post-nephrectomy. We assessed tumour burden, objective response rate upon RECIST1.1, disease-free survival (DFS) and progression-free survival (PFS). The correlation between circulating biomarkers was evaluated with multiple factor analysis and biomarker association with DFS/PFS by Cox regression. No objective response rate was obtained before nephrectomy. Upon everolimus, neutrophils, platelets and sVEGFR2 significantly decreased. We did not find any association between circulating biomarkers and DFS/PFS, but patients with the highest tumour burden at baseline had significantly higher plasma levels of interleukin-6, an inflammatory circulating biomarker, and lower levels of sVEGFR2, related to angiogenesis. Further understanding of the link between these circulating biomarkers could help to optimise drug combinations in RCC.

A Soluble Platelet-Derived Growth Factor Receptor-β Originates via Pre-mRNA Splicing in the Healthy Brain and is Differentially Regulated during Hypoxia and Aging

The platelet-derived growth factor-BB (PDGF-BB) pathway provides critical regulation of cerebrovascular pericytes, orchestrating their investment and retention within the brain microcirculation. Dysregulated PDGF Receptor-beta (PDGFRβ) signaling can lead to pericyte defects that compromise blood-brain barrier (BBB) integrity and cerebral perfusion, impairing neuronal activity and viability, which fuels cognitive and memory deficits. Receptor tyrosine kinases (RTKs) like PDGF-BB and vascular endothelial growth factor-A (VEGF-A) are often modulated by soluble isoforms of cognate receptors that establish signaling activity within a physiological range. Soluble PDGFRβ (sPDGFRβ) isoforms have been reported to form by enzymatic cleavage from cerebrovascular mural cells, and pericytes in particular, largely under pathological conditions. However, pre-mRNA alternative splicing has not been widely explored as a possible mechanism for generating sPDGFRβ variants, and specifically during tissue homeostasis. Here, we found sPDGFRβ protein in the murine brain and other tissues under normal, physiological conditions. Utilizing brain samples for follow-on analysis, we identified mRNA sequences corresponding to sPDGFRβ isoforms, which facilitated construction of predicted protein structures and related amino acid sequences. Human cell lines yielded comparable sequences and protein model predictions. Retention of ligand binding capacity was confirmed for sPDGFRβ by co-immunoprecipitation. Visualizing fluorescently labeled sPDGFRβ transcripts revealed a spatial distribution corresponding to murine brain pericytes alongside cerebrovascular endothelium. Soluble PDGFRβ protein was detected throughout the brain parenchyma in distinct regions such as along the lateral ventricles, with signals also found more broadly adjacent to cerebral microvessels consistent with pericyte labeling. To better understand how sPDGFRβ variants might be regulated, we found elevated transcript and protein levels in the murine brain with age, and acute hypoxia increased sPDGFRβ variant transcripts in a cell-based model of intact vessels. Our findings indicate that soluble isoforms of PDGFRβ likely arise from pre-mRNA alternative splicing, in addition to enzymatic cleavage mechanisms, and these variants exist under normal physiological conditions. Follow-on studies will be needed to establish potential roles for sPDGFRβ in regulating PDGF-BB signaling to maintain pericyte quiescence, BBB integrity, and cerebral perfusion - critical processes underlying neuronal health and function, and in turn memory and cognition.

Lymphangiogenesis Guidance Mechanisms and Therapeutic Implications in Pathological States of the Cornea

Corneal lymphangiogenesis is one component of the neovascularization observed in several inflammatory pathologies of the cornea including dry eye disease and corneal graft rejection. Following injury, corneal (lymph)angiogenic privilege is impaired, allowing ingrowth of blood and lymphatic vessels into the previously avascular cornea. While the mechanisms underlying pathological corneal hemangiogenesis have been well described, knowledge of the lymphangiogenesis guidance mechanisms in the cornea is relatively scarce. Various signaling pathways are involved in lymphangiogenesis guidance in general, each influencing one or multiple stages of lymphatic vessel development. Most endogenous factors that guide corneal lymphatic vessel growth or regression act via the vascular endothelial growth factor C signaling pathway, a central regulator of lymphangiogenesis. Several exogenous factors have recently been repurposed and shown to regulate corneal lymphangiogenesis, uncovering unique signaling pathways not previously known to influence lymphatic vessel guidance. A strong understanding of the relevant lymphangiogenesis guidance mechanisms can facilitate the development of targeted anti-lymphangiogenic therapeutics for corneal pathologies. In this review, we examine the current knowledge of lymphatic guidance cues, their regulation of inflammatory states in the cornea, and recently discovered anti-lymphangiogenic therapeutic modalities.

Hypoxia-induced carbonic anhydrase mediated dorsal horn neuron activation and induction of neuropathic pain

ABSTRACT

Neuropathic pain, such as that seen in diabetes mellitus, results in part from central sensitisation in the dorsal horn. However, the mechanisms responsible for such sensitisation remain unclear. There is evidence that disturbances in the integrity of the spinal vascular network can be causative factors in the development of neuropathic pain. Here we show that reduced blood flow and vascularity of the dorsal horn leads to the onset of neuropathic pain. Using rodent models (type 1 diabetes and an inducible endothelial-specific vascular endothelial growth factor receptor 2 knockout mouse) that result in degeneration of the endothelium in the dorsal horn, we show that spinal cord vasculopathy results in nociceptive behavioural hypersensitivity. This also results in increased hypoxia in dorsal horn neurons, depicted by increased expression of hypoxia markers such as hypoxia inducible factor 1α, glucose transporter 3, and carbonic anhydrase 7. Furthermore, inducing hypoxia through intrathecal delivery of dimethyloxalylglycine leads to the activation of dorsal horn neurons as well as mechanical and thermal hypersensitivity. This shows that hypoxic signalling induced by reduced vascularity results in increased hypersensitivity and pain. Inhibition of carbonic anhydrase activity, through intraperitoneal injection of acetazolamide, inhibited hypoxia-induced pain behaviours. This investigation demonstrates that induction of a hypoxic microenvironment in the dorsal horn, as occurs in diabetes, is an integral process by which neurons are activated to initiate neuropathic pain states. This leads to the conjecture that reversing hypoxia by improving spinal cord microvascular blood flow could reverse or prevent neuropathic pain.

Integration of TE Induces Cancer Specific Alternative Splicing Events

Alternative splicing of messenger RNA (mRNA) precursors contributes to genetic diversity by generating structurally and functionally distinct transcripts. In a disease state, alternative splicing promotes incidence and development of several cancer types through regulation of cancer-related biological processes. Transposable elements (TEs), having the genetic ability to jump to other regions of the genome, can bring about alternative splicing events in cancer. TEs can integrate into the genome, mostly in the intronic regions, and induce cancer-specific alternative splicing by adjusting various mechanisms, such as exonization, providing splicing donor/acceptor sites, alternative regulatory sequences or stop codons, and driving exon disruption or epigenetic regulation. Moreover, TEs can produce microRNAs (miRNAs) that control the proportion of transcripts by repressing translation or stimulating the degradation of transcripts at the post-transcriptional level. Notably, TE insertion creates a cancer-friendly environment by controlling the overall process of gene expression before and after transcription in cancer cells. This review emphasizes the correlative interaction between alternative splicing by TE integration and cancer-associated biological processes, suggesting a macroscopic mechanism controlling alternative splicing by TE insertion in cancer.

The lymphatic vascular system: much more than just a sewer

Almost 400 years after the (re)discovery of the lymphatic vascular system (LVS) by Gaspare Aselli (Asellius G. De lactibus, sive lacteis venis, quarto vasorum mesaraicorum genere, novo invento Gasparis Asellii Cremo. Dissertatio. (MDCXXIIX), Milan; 1628.), structure, function, development and evolution of this so-called 'second' vascular system are still enigmatic. Interest in the LVS was low because it was (and is) hardly visible, and its diseases are not as life-threatening as those of the blood vascular system. It is not uncommon for patients with lymphedema to be told that yes, they can live with it. Usually, the functions of the LVS are discussed in terms of fluid homeostasis, uptake of chylomicrons from the gut, and immune cell circulation. However, the broad molecular equipment of lymphatic endothelial cells suggests that they possess many more functions, which are also reflected in the pathophysiology of the system. With some specific exceptions, lymphatics develop in all organs. Although basic structure and function are the same regardless their position in the body wall or the internal organs, there are important site-specific characteristics. We discuss common structure and function of lymphatics; and point to important functions for hyaluronan turn-over, salt balance, coagulation, extracellular matrix production, adipose tissue development and potential appetite regulation, and the influence of hypoxia on the regulation of these functions. Differences with respect to the embryonic origin and molecular equipment between somatic and splanchnic lymphatics are discussed with a side-view on the phylogeny of the LVS. The functions of the lymphatic vasculature are much broader than generally thought, and lymphatic research will have many interesting and surprising aspects to offer in the future.

Cystathionine β-synthase as novel endogenous regulator of lymphangiogenesis via modulating VEGF receptor 2 and 3

Lymphangiogenesis is a key player in several diseases such as tumor metastasis, obesity, and graft rejection. Endogenous regulation of lymphangiogenesis is only partly understood. Here we use the normally avascular cornea as a model to identify endogenous regulators of lymphangiogenesis. Quantitative trait locus analysis of a large low-lymphangiogenic BALB/cN x high-lymphangiogenic C57BL/6 N intercross and prioritization by whole-transcriptome sequencing identify a novel gene responsible for differences in lymphatic vessel architecture on chromosome 17, the cystathionine β-synthase (Cbs). Inhibition of CBS in lymphatic endothelial cells results in reduce proliferation, migration, altered tube-formation, and decrease expression of vascular endothelial growth factor (VEGF) receptor 2 (VEGF-R2) and VEGF-R3, but not their ligands VEGF-C and VEGF-D. Also in vivo inflammation-induced lymphangiogenesis is significantly reduce in C57BL/6 N mice after pharmacological inhibition of CBS. The results confirm CBS as a novel endogenous regulator of lymphangiogenesis acting via VEGF receptor 2 and 3-regulation and open new treatment avenues in diseases associated with pathologic lymphangiogenesis.

Antiangiogenic AAV2 gene therapy with a truncated form of soluble VEGFR-2 reduces the growth of choroidal neovascularization in mice after intravitreal injection

Pathological angiogenesis related to neovascularization in the eye is mediated through vascular endothelial growth factors (VEGFs) and their receptors. Ocular neovascular-related diseases are mainly treated with anti-VEGF agents. In this study we evaluated the efficacy and safety of novel gene therapy using adeno associated virus 2 vector expressing a truncated form of soluble VEGF receptor-2 fused to the Fc-part of human IgG1 (AAV2-sVEGFR-2-Fc) to inhibit ocular neovascularization in laser induced choroidal neovascularization (CNV) in mice. The biological activity of sVEGFR-2-Fc was determined in vitro. It was shown that sVEGFR-2-Fc secreted from ARPE-19 cells was able to bind to VEGF-A₁₆₅ and reduce VEGF-A₁₆₅ induced cell growth and survival. A single intravitreal injection (IVT) of AAV2-sVEGFR-2-Fc (1 μl, 4.7 × 10¹² vg/ml) one-month prior laser photocoagulation did not cause any changes in the retinal morphology and significantly suppressed fluorescein leakage at 7, 14, 21 and 28 days post-lasering compared to controls. Macrophage infiltration was observed after the injection of both AAV2-sVEGFR-2-Fc and PBS. Our findings indicate that AAV2 mediated gene delivery of the sVEGFR-2-Fc efficiently reduces formation of CNV and could be developed to a therapeutic tool for the treatment of retinal diseases associated with neovascularization.

VEGFR endocytosis: Implications for angiogenesis

The binding of vascular endothelial growth factor (VEGF) superfamily to VEGF receptor tyrosine kinases (VEGFRs) and co-receptors regulates vasculogenesis, angiogenesis and lymphangiogenesis. A recurring theme is that dysfunction in VEGF signaling promotes pathological angiogenesis, an important feature of cancer and pro-inflammatory disease states. Endocytosis of basal (resting) or activated VEGFRs facilitates signal attenuation and endothelial quiescence. However, increasing evidence suggest that activated VEGFRs can continue to signal from intracellular compartments such as endosomes. In this chapter, we focus on the evolving link between VEGFR endocytosis, signaling and turnover and the implications for angiogenesis. There is much interest in how such understanding of VEGFR dynamics can be harnessed therapeutically for a wide range of human disease states.

Alternative Splicing in Cancer and Immune Cells

Splicing is a phenomenon enabling the excision of introns from pre-mRNA to give rise to mature mRNA. All the 20,000 genes of the human genome are concerned by this mechanism. Nevertheless, it is estimated that the proteome is composed of more than 100,000 proteins. How to go from 20,000 genes to more than 100,000 proteins? Alternative splicing (AS) is in charge of this diversity of proteins. AS which is found in most of the cells of an organism, participates in normal cells and in particular in immune cells, in the regulation of cellular behavior. In cancer, AS is highly dysregulated and involved in almost all of the hallmarks that characterize tumor cells. In view of the close link that exists between tumors and the immune system, we present in this review the literature relating to alternative splicing and immunotherapy. We also provide a global but not exhaustive view of AS in the immune system and tumor cells linked to the events that can lead to AS dysregulation in tumors.

Roles of Epithelial and Mesenchymal TRP Channels in Mediating Inflammatory Fibrosis

The maintenance of normal vision is dependent on preserving corneal transparency. For this to occur, this tissue must remain avascular and its stromal architecture needs to be retained. Epithelial transparency is maintained provided the uppermost stratified layers of this tissue are composed of terminally differentiated non-keratinizing cells. In addition, it is essential that the underlying stromal connective tissue remains avascular and scar-free. Keratocytes are the source of fibroblasts that are interspersed within the collagenous framework and the extracellular matrix. In addition, there are sensory nerve fibers whose lineage is possibly either neural crest or mesenchymal. Corneal wound healing studies have been undertaken to delineate the underlying pathogenic responses that result in the development of opacification following chemical injury. An alkali burn is one type of injury that can result in severe and long- lasting losses in ocular transparency. During the subsequent wound healing process, numerous different proinflammatory cytokines and proteolytic enzymes undergo upregulation. Such increases in their expression levels induce maladaptive expression of sustained stromal inflammatory fibrosis, neovascularization, and losses in the smooth optical properties of the corneal outer surface. It is becoming apparent that different transient receptor potential channel (TRP) isoforms are important players in mediating these different events underlying the wound healing process since injury upregulates both their expression levels and functional involvement. In this review, we focus on the involvement of TRPV1, TRPA1 and TRPV4 in mediating some of the responses that underlie the control of anterior ocular tissue homeostasis under normal and pathological conditions. They are expressed on both different cell types throughout this tissue and also on corneal sensory nerve endings. Their roles have been extensively studied as sensors and transducers of environmental stimuli resulting from exposure to intrinsic modulators and extrinsic ligands. These triggers include alteration of the ambient temperature and mechanical stress, etc., that can induce pathophysiological responses underlying losses in tissue transparency activated by wound healing in mice losses in tissue transparency. In this article, experimental findings are reviewed about the role of injury-induced TRP channel activation in mediating inflammatory fibrotic responses during wound healing in mice.

Corneal lymphangiogenesis as a potential target in dry eye disease - a systematic review

Dry eye disease (DED) is a common ocular surface condition causing symptoms of significant discomfort, visual disturbance, and pain. With recent advancements, DED has become recognized as a chronic self-perpetuating inflammatory condition triggered by various internal and environmental factors. DED has been shown to arise from the activation of both the innate and adaptive immune systems, leading to corneal epithelium and lacrimal gland dysfunction. While the cornea is normally avascular and thus imbued with angiogenic and lymphangiogenic privilege, various DED models have revealed activated corneal antigen-presenting cells in regional lymph nodes, suggesting the formation of new corneal lymphatic vessels in DED. The recent availability of reliable lymphatic cell surface markers such as LYVE-1 has made it possible to study lymphangiogenesis. Accordingly, numerous studies have been published within the last decade discussing the role of lymphangiogenesis in DED pathology. We systematically review the literature to identify and evaluate studies presenting data on corneal lymphangiogenesis in DED. There is considerable evidence supporting corneal lymphangiogenesis as a central mediator of DED pathogenesis. These findings suggest that anti-lymphangiogenic therapeutic strategies may be a viable option for the treatment of DED, a conclusion supported by the limited number of reported clinical trials examining anti-lymphangiogenic modalities in DED.

The Role of Lymphangiogenesis in Coronary Atherosclerosis

Lymphatic circulation, a one-way channel system independent of blood circulation, collects interstitial fluid in a blind-end way. Existing widely in various organs and tissues, lymphatic vessels play important roles in maintaining tissue fluid homeostasis, regulating immune function, and promoting lipid transport. Recent studies have shown clear evidence that lymphangiogenesis has a strong mutual effect on coronary atherosclerosis (AS). In this study, we focus on this topic, especially in the aspects of relevant ligand/receptor, inflammation, and adipose metabolism. For the moment, however, the role of lymphangiogenesis and remodeling in coronary AS still remains controversial. The studies of our group and accumulating published evidence show that the pathological remodeling of lymphatic vessels in coronary AS may have a negative effect, but normal functional lymphangiogenesis is probably beneficial to the regression of coronary AS. Thus, the conclusion of this review is that lymphatic vessel function rather than its quantity determines its influence in AS, which needs more evidence to support.

The role of alternative splicing in human cancer progression

In eukaryotes, alternative splicing refers to a process via which a single precursor RNA (pre-RNA) is transcribed into different mature RNAs. Thus, alternative splicing enables the translation of a limited number of coding genes into a large number of proteins with different functions. Although, alternative splicing is common in normal cells, it also plays an important role in cancer development. Alteration in splicing mechanisms and even the participation of non-coding RNAs may cause changes in the splicing patterns of cancer-related genes. This article reviews the latest research on alternative splicing in cancer, with a view to presenting new strategies and guiding future studies related to pathological mechanisms associated with cancer.

Corneal Allografts: Factors for and against Acceptance

Cornea is one of the most commonly transplanted tissues worldwide. However, it is usually omitted in the field of transplantology. Transplantation of the cornea is performed to treat many ocular diseases. It restores eyesight significantly improving the quality of life. Advancements in banking of explanted corneas and progressive surgical techniques increased availability and outcomes of transplantation. Despite the vast growth in the field of transplantation laboratory testing, standards for corneal transplantation still do not include HLA typing or alloantibody detection. This standard practice is based on immune privilege dogma that accounts for high success rates of corneal transplantation. However, the increasing need for retransplantation in high-risk patients with markedly higher risk of rejection causes ophthalmology transplantation centers to reevaluate their standard algorithms. In this review we discuss immune privilege mechanisms influencing the allograft acceptance and factors disrupting the natural immunosuppressive environment of the eye. Current developments in testing and immunosuppressive treatments (including cell therapies), when applied in corneal transplantation, may give very good results, decrease the possibility of rejection, and reduce the need for retransplantation, which is fairly frequent nowadays.

Cell-specific gene association network construction from single-cell RNA sequence

The recent development of a high throughput single-cell RNA sequence devises the opportunity to study entire transcriptomes in the smallest detail. It also leads to the characterization of molecules and subtypes of a cell. Cancer epigenetics induced not only from individual molecules but also from the dysfunction of the system and the coupling effect of genes. While rapid advances are being made in the development of tools for single-cell RNA-seq data analysis, few slants are noticed in the potential advantages of single-cell network construction.Here, we used network perturbation theory with significant analysis to develop a cell-specific network that provides an insight into gene-gene association based on molecular expressions in a single-cell resolution. Besides, using this method, we can characterize each cell by inspecting how genes are connected and can identify the hub genes using network degree theory. Pathway & Gene enrichment analysis of the identified cell-specific high network degree genes supported the effectiveness of this method. This method could be beneficial for personalized drug design and even therapeutics.

Soluble vascular endothelial growth factor receptor 2 and prognosis in patients with chronic heart failure

Aims

Endothelial cell vascular endothelial growth factor receptor 2 (VEGFR‐2) plays a pivotal role in angiogenesis, which induces physiological cardiomyocyte hypertrophy via paracrine signalling between endothelial cells and cardiomyocytes. We investigated whether a decrease in circulating soluble VEGFR‐2 (sVEGFR‐2) levels is associated with poor prognosis in patients with chronic heart failure (HF).

Methods and results

We performed a multicentre prospective cohort study of 1024 consecutive patients with HF, who were admitted to hospitals due to acute decompensated HF and were stabilized after initial management. Serum levels of sVEGFR‐2 were measured at discharge. Patients were followed up over 2 years. The outcomes were cardiovascular death, all‐cause death, major adverse cardiovascular events (MACE) defined as a composite of cardiovascular death and HF hospitalization, and HF hospitalization. The mean age of the patients was 75.5 (standard deviation, 12.6) years, and 57% were male. Patients with lower sVEGFR‐2 levels were older and more likely to be female, and had greater proportions of atrial fibrillation and anaemia, and lower proportions of diabetes, dyslipidaemia, and HF with reduced ejection fraction (<40%). During the follow‐up, 113 cardiovascular deaths, 211 all‐cause deaths, 350 MACE, and 309 HF hospitalizations occurred. After adjustment for potential clinical confounders and established biomarkers [N‐terminal B‐type natriuretic peptide (NT‐proBNP), high‐sensitivity cardiac troponin I, and high‐sensitivity C‐reactive protein], a low sVEGFR‐2 level below the 25th percentile was significantly associated with cardiovascular death [hazard ratio (HR), 1.79; 95% confidence interval (CI), 1.16–2.74] and all‐cause death (HR, 1.43; 95% CI, 1.04–1.94), but not with MACE (HR, 1.11; 95% CI, 0.86–1.43) or HF hospitalization (HR, 1.03; 95% CI, 0.78–1.35). The stratified analyses revealed that a low sVEGFR‐2 level below the 25th percentile was significantly associated with cardiovascular death (HR, 1.76; 95% CI, 1.07–2.85) and all‐cause death (HR, 1.49; 95% CI, 1.03–2.15) in the high‐NT‐proBNP group (above the median), but not in the low‐NT‐proBNP group. Notably, the patients with high‐NT‐proBNP and low‐sVEGFR‐2 (below the 25th percentile) had a 2.96‐fold higher risk (95% CI, 1.56–5.85) for cardiovascular death and a 2.40‐fold higher risk (95% CI, 1.52–3.83) for all‐cause death compared with those with low‐NT‐proBNP and high‐sVEGFR‐2.

Conclusions

A low sVEGFR‐2 value was independently associated with cardiovascular death and all‐cause death in patients with chronic HF. These associations were pronounced in those with high NT‐proBNP levels.

Corneal lymphangiogenesis in dry eye disease is regulated by substance P/neurokinin-1 receptor system through controlling expression of vascular endothelial growth factor receptor 3

PURPOSE

To evaluate the role of substance P (SP)/neurokinin-1 receptor (NK1R) system in the regulation of pathologic corneal lymphangiogenesis in dry eye disease (DED).

METHODS

Immunocytochemistry, angiogenesis assay, and Western blot analysis of human dermal lymphatic endothelial cells (HDLECs) were conducted to assess the involvement of SP/NK1R system in lymphangiogenesis. DED was induced in wild-type C57BL/6 J mice using controlled-environment chamber without scopolamine. Immunohistochemistry, corneal fluorescein staining, and phenol red thread test were used to evaluate the effect of SP signaling blockade in the corneal lymphangiogenesis. The expression of lymphangiogenic factors in the corneal and conjunctival tissues of DED mouse model was quantified by real-time polymerase chain reaction.

RESULTS

NK1R expression and pro-lymphangiogenic property of SP/NK1R system in HDLECs were confirmed by Western blot analysis and angiogenesis assay. Blockade of SP signaling with L733,060, an antagonist of NK1R, or NK1R-targeted siRNA significantly inhibited lymphangiogenesis and expression of vascular endothelial growth factor (VEGF) receptor 3 stimulated by SP in HDLECs. NK1R antagonist also suppressed pathological corneal lymphangiogenesis and ameliorated the clinical signs of dry eye in vivo. Furthermore, NK1R antagonist effectively suppressed the lymphangiogenic factors, including VEGF-C, VEGF-D, and VEGF receptor 3 in the corneal and conjunctival tissues of DED.

CONCLUSIONS

SP/NK1R system promotes lymphangiogenesis in vitro and NK1R antagonism suppresses pathologic corneal lymphangiogenesis in DED in vivo.

Lymphatic Trafficking in the Eye: Modulation of Lymphatic Trafficking to Promote Corneal Transplant Survival

(Lymph)angiogenesis into the cornea prior to and after corneal transplantation is a critical risk factor for allograft rejection. Lymphatic vessels even more than blood vessels seem important in mediating immune responses, as they facilitate allograft sensitization in the draining lymph nodes. Thus, the concept of modulating lymphatic trafficking to promote corneal graft survival seems promising. A variety of approaches has been developed to inhibit progressive lymphangiogenesis in experimental settings. Recently, additionally to pharmacological approaches, clinically available techniques such as UVA-based corneal collagen crosslinking and fine needle diathermy were reported to be effective in regressing lymphatic vessels and to experimentally promote graft survival. Clinical pilot studies also suggest the efficacy of blocking antigen presenting cell trafficking to regional lymph nodes by regressing corneal lymphatic vessels to enhance allograft survival in high-risk eyes. In this article, we will give an overview of current strategies to modulate lymphatic trafficking with a special focus on recently reported strategies, which may be easy to translate into clinical practice. This novel concept of temporary, pretransplant regression of lymphatic vessels at the site of transplantation to promote subsequent corneal transplant survival ("lymphangioregressive preconditioning") may also be applicable to other transplantation sites later.

Association between ABO and Duffy blood types and circulating chemokines and cytokines

Blood group antigens are inherited traits that may play a role in immune and inflammatory processes. We investigated associations between blood groups and circulating inflammation-related molecules in 3537 non-Hispanic white participants selected from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Whole-genome scans were used to infer blood types for 12 common antigen systems based on well-characterized single-nucleotide polymorphisms. Serum levels of 96 biomarkers were measured on multiplex fluorescent bead-based panels. We estimated marker associations with blood type using weighted linear or logistic regression models adjusted for age, sex, smoking status, and principal components of population substructure. Bonferroni correction was used to control for multiple comparisons, with two-sided p values < 0.05 considered statistically significant. Among the 1152 associations tested, 10 were statistically significant. Duffy blood type was associated with levels of CXCL6/GCP2, CXCL5/ENA78, CCL11/EOTAXIN, CXCL1/GRO, CCL2/MCP1, CCL13/MCP4, and CCL17/TARC, whereas ABO blood type was associated with levels of sVEGFR2, sVEGFR3, and sGP130. Post hoc pairwise t-tests showed that individuals with type Fy(a+b−) had the lowest mean levels of all Duffy-associated markers, while individuals with type A blood had the lowest mean levels of all ABO-associated markers. Additional work is warranted to explore potential clinical implications of these differences.

Imaging of vascular abnormalities in ocular surface disease

The vascular system of the ocular surface plays a central role in infectious, autoimmune, inflammatory, traumatic and neoplastic diseases. The development, application, and monitoring of treatments for vascular abnormalities depends on the in vivo analysis of the ocular surface vasculature. Until recently, ocular surface vascular imaging was confined to biomicroscopic and color photographic assessment, both limited by poor reproducibility and the inability to image lymphatic vasculature in vivo. The evolvement and clinical implementation of innovative imaging modalities including confocal microscopy, intravenous, and optical coherence tomography-based angiography now allows standardized quantitative and functional vascular assessment with potential applicability to automated analysis algorithms and diagnostics.

Phage-Displayed Peptides for Targeting Tyrosine Kinase Membrane Receptors in Cancer Therapy

Receptor tyrosine kinases (RTKs) regulate critical physiological processes, such as cell growth, survival, motility, and metabolism. Abnormal activation of RTKs and relative downstream signaling is implicated in cancer pathogenesis. Phage display allows the rapid selection of peptide ligands of membrane receptors. These peptides can target in vitro and in vivo tumor cells and represent a novel therapeutic approach for cancer therapy. Further, they are more convenient compared to antibodies, being less expensive and non-immunogenic. In this review, we describe the state-of-the-art of phage display for development of peptide ligands of tyrosine kinase membrane receptors and discuss their potential applications for tumor-targeted therapy.

Macrophage-Mediated Tissue Vascularization: Similarities and Differences Between Cornea and Skin

Macrophages are critical mediators of tissue vascularization both in health and disease. In multiple tissues, macrophages have been identified as important regulators of both blood and lymphatic vessel growth, specifically following tissue injury and in pathological inflammatory responses. In development, macrophages have also been implicated in limiting vascular growth. Hence, macrophages provide an important therapeutic target to modulate tissue vascularization in the clinic. However, the molecular mechanisms how macrophages mediate tissue vascularization are still not entirely resolved. Furthermore, mechanisms might also vary among different tissues. Here we review the role of macrophages in tissue vascularization with a focus on their role in blood and lymphatic vessel formation in the barrier tissues cornea and skin. Comparing mechanisms of macrophage-mediated hem- and lymphangiogenesis in the angiogenically privileged cornea and the physiologically vascularized skin provides an opportunity to highlight similarities but also tissue-specific differences, and to understand how macrophage-mediated hem- and lymphangiogenesis can be exploited for the treatment of disease, including corneal wound healing after injury, graft rejection after corneal transplantation or pathological vascularization of the skin.

PEDF inhibits lymphatic metastasis of nasopharyngeal carcinoma as a new lymphangiogenesis inhibitor

Nasopharyngeal carcinoma (NPC) is one of the most malignant tumors in southern China and Asia, and lymph node metastasis is an important cause for treatment failure. Lymphangiogenesis is a crucial step in lymphatic metastasis of NPC, while little is known about lymphangiogenesis in NPC. Similar to angiogenesis, lymphangitic neovascularization is a process of balance between pro-lymphangiogenesis and anti-lymphangiogenesis factors, but there are few studies on endogenous lymphangiogenesis inhibitors. Pigment epithelium-derived factor (PEDF) is a well-known effective endogenous angiogenesis inhibitor. However, the relationship between PEDF and lymphangiogenesis remains unknown. Our present study reveals that PEDF is lowly expressed in human NPC tissues with poor prognosis and is negatively correlated with lymphatic vessel density (LVD). Consistently, PEDF inhibits lymphangiogenesis and lymphatic metastasis of NPC in vivo experiments. Mechanistically, PEDF inhibits the proliferation, migration, and tube formation of lymphatic endothelial cells and promotes cell apoptosis. On the other hand, PEDF reduces the expression and secretion of vascular endothelial growth factor C (VEGF-C) of NPC cells through the nuclear factor-κB (NF-κB) signaling pathway. Our findings indicate that PEDF plays a vital role in lymphatic metastasis by targeting both lymphatic endothelial cells and NPC cells, and PEDF may represent a novel therapeutic target for NPC.

The Role of VEGF Receptors as Molecular Target in Nuclear Medicine for Cancer Diagnosis and Combination Therapy

Simple Summary

The rapid development of diagnostic and therapeutic methods of the cancer treatment causes that these diseases are becoming better known and the fight against them is more and more effective. Substantial contribution in this development has nuclear medicine that enables very early cancer diagnosis and early start of the so-called targeted therapy. This therapeutic concept compared to the currently used chemotherapy, causes much fewer undesirable side effects, due to targeting a specific lesion in the body. This review article discusses the possible applications of radionuclide-labelled tracers (peptides, antibodies or synthetic organic molecules) that can visualise cancer cells through pathological blood vessel system in close tumour microenvironment. Hence, at a very early step of oncological disease, targeted therapy can involve in tumour formation and growth.

Abstract

One approach to anticancer treatment is targeted anti-angiogenic therapy (AAT) based on prevention of blood vessel formation around the developing cancer cells. It is known that vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptors (VEGFRs) play a pivotal role in angiogenesis process; hence, application of angiogenesis inhibitors can be an effective approach in anticancer combination therapeutic strategies. Currently, several types of molecules have been utilised in targeted VEGF/VEGFR anticancer therapy, including human VEGF ligands themselves and their derivatives, anti-VEGF or anti-VEGFR monoclonal antibodies, VEGF binding peptides and small molecular inhibitors of VEGFR tyrosine kinases. These molecules labelled with diagnostic or therapeutic radionuclides can become, respectively, diagnostic or therapeutic receptor radiopharmaceuticals. In targeted anti-angiogenic therapy, diagnostic radioagents play a unique role, allowing the determination of the emerging tumour, to monitor the course of treatment, to predict the treatment outcomes and, first of all, to refer patients for AAT. This review provides an overview of design, synthesis and study of radiolabelled VEGF/VEGFR targeting and imaging agents to date. Additionally, we will briefly discuss their physicochemical properties and possible application in combination targeted radionuclide tumour therapy.

Lymphatic metastasis of bladder cancer: Molecular mechanisms, diagnosis and targeted therapy

Bladder cancer is the most common and lethal cancer of the urinary system. Lymphatic metastasis is the primary and main metastatic type of bladder cancer, leading to an extremely poor prognosis in patients. Therefore, a better understanding of molecular mechanisms may provide potential targets for the diagnosis and treatment of lymphatic metastasis in bladder cancer. Herein, we summarize the current knowledge of molecular mechanisms of the lymphatic metastasis in bladder cancer, including lymphangiogenesis and its regulators, noncoding RNAs, and microenvironment-associated molecules. Novel radiomics and genomics approaches have substantially improved the preoperative diagnostic accuracy of lymph node metastasis in patients with bladder cancer. Newly discovered targets may lead to promising therapeutic strategies for clinical intervention in lymphatic metastasis of bladder cancer. More basic and translational studies need to be conducted to further clarify the molecular mechanisms, and identify predictive markers and therapeutic targets of lymphatic metastasis for bladder cancer patients.

Role of Arginine Methylation in Alternative Polyadenylation of VEGFR-1 (Flt-1) pre-mRNA

Mature mRNA is generated by the 3ʹ end cleavage and polyadenylation of its precursor pre-mRNA. Eukaryotic genes frequently have multiple polyadenylation sites, resulting in mRNA isoforms with different 3ʹ-UTR lengths that often encode different C-terminal amino acid sequences. It is well-known that this form of post-transcriptional modification, termed alternative polyadenylation, can affect mRNA stability, localization, translation, and nuclear export. We focus on the alternative polyadenylation of pre-mRNA for vascular endothelial growth factor receptor-1 (VEGFR-1), the receptor for VEGF. VEGFR-1 is a transmembrane protein with a tyrosine kinase in the intracellular region. Secreted forms of VEGFR-1 (sVEGFR-1) are also produced from the same gene by alternative polyadenylation, and sVEGFR-1 has a function opposite to that of VEGFR-1 because it acts as a decoy receptor for VEGF. However, the mechanism that regulates the production of sVEGFR-1 by alternative polyadenylation remains poorly understood. In this review, we introduce and discuss the mechanism of alternative polyadenylation of VEGFR-1 mediated by protein arginine methylation.

Soluble Vegfr3 gene therapy suppresses multi-organ metastasis in a mouse mammary cancer model

Accumulating evidence on the association of VEGF-C with lymphangiogenesis and lymph node metastasis implicates lymphatic vessels as a potential target in anti-cancer therapy. To evaluate whether blocking VEGF-C and VEGFR-3 signaling can inhibit multi-organ metastases, a mouse metastatic mammary cancer model was subjected to gene therapy using a soluble VEGFR-3 expression vector (psVEGFR-3). We showed that psVEGFR-3 significantly diminished cell growth in vitro with or without added VEGF-C, and significantly reduced primary tumor growth and tumor metastases to wide-spectrum organs in vivo. Although apoptotic cell death and angiogenesis levels did not differ between the control and psVEGFR-3 groups, cell proliferation and lymphangiogenesis in the mammary tumors were significantly decreased in the psVEGFR-3 group. Furthermore, lymphatic vessel invasion was significantly inhibited in this group. Real-time RT-PCR analysis revealed significantly high expression of the Vegfr3 gene due to gene therapy, and the transcriptional levels of Pcna and Lyve1 tended to decrease in the psVEGFR-3 group. Immunofluorescence staining indicated that phospho-tyrosine expression was considerably lower in tumor cells of psVEGFR-3-treated mammary carcinomas than those of control tumors. Double immunofluorescence staining indicated that phospho-tyrosine⁺ /LYVE-1⁺ (a lymphatic vessel marker) tended to decrease in psVEGFR-3-treated mammary carcinomas compared with control mice, indicating a decline in the activity of the VEGF-C/VEGFR-3 axis. These findings showed that a blockade of VEGF-C/VEGFR-3 signaling caused by sVEGFR-3 sequestered VEGF-C and prevented the side-effects of anti-angiogenesis and suppressed overall metastases, suggesting their high clinical significance.

Gene-based Therapeutic Tools in the Treatment of Cornea Disease

BACKGROUND

As one of the main blinding ocular diseases, corneal blindness resulted from neovascularization that disrupts the angiogenic privilege of corneal avascularity. Following neovascularization, inflammatory cells are infiltrating into cornea to strengthen corneal injury. How to maintain corneal angiogenic privilege to treat corneal disease has been investigated for decades.

METHODOLOGY

Local administration of viral and non-viral-mediated anti-angiogenic factors reduces angiogenic protein expression in situ with limited or free of off-target effects upon gene delivery. Recently, Mesenchymal Stem Cells (MSCs) have been studied to treat corneal diseases. Once MSCs are manipulated to express certain genes of interest, they could achieve superior therapeutic efficacy after transplantation.

DISCUSSION

In the text, we first introduce the pathological development of corneal disease in the aspects of neovascularization and inflammation. We summarize how MSCs become an ideal candidate in cell therapy for treating injured cornea, focusing on cell biology, property and features. We provide an updated review of gene-based therapies in animals and preclinical studies in the aspects of controlling target gene expression, safety and efficacy. Gene transfer vectors are potent to induce candidate protein expression. Delivered by vectors, MSCs are equipped with certain characters by expressing a protein of interest, which facilitates better for MSC-mediated therapeutic intervention for the treatment of corneal disease.

CONCLUSION

As the core of this review, we discuss how MSCs could be engineered to be vector system to achieve enhanced therapeutic efficiency after injection.

Variable Responses to Corneal Grafts: Insights from Immunology and Systems Biology

Corneal grafts interact with their hosts via complex immunobiological processes that sometimes lead to graft failure. Prediction of graft failure is often a tedious task due to the genetic and nongenetic heterogeneity of patients. As in other areas of medicine, a reliable prediction method would impact therapeutic decision-making in corneal transplantation. Valuable insights into the clinically observed heterogeneity of host responses to corneal grafts have emerged from multidisciplinary approaches, including genomics analyses, mechanical studies, immunobiology, and theoretical modeling. Here, we review the emerging concepts, tools, and new biomarkers that may allow for the prediction of graft survival.

Effect of isotretinoin (13-cis-retinoic acid) on levels of soluble VEGF receptors (sVEGFR1, sVEGFR2, sVEGFR3) in patients with acne vulgaris

Background/aim: The effect of isotretinoin on soluble VEGFRs has not been previously investigated. This study evaluate the effects of isotretinoin (13-cis-retinoic acid) on soluble VEGFR1 (sVEGFR1), soluble VEGFR2 (sVEGFR2) and soluble VEGFR3 (sVEGFR3).Methods: The study included 38 patients (28 females, 10 males) receiving systemic isotretinoin treatment and 38 healthy individuals (28 females, 10 males) with similar age and gender characteristics. The blood samples of the patient group at third months and blood samples of the control group were compared in terms of sVEGFR1, sVEGFR2 and sVEGFR3 concentrations.Results: It was significant that sVEGFR1 was low and sVEGFR3 was high in patients receiving isotretinoin (p: .038, p: .021, respectively). There was no significant change in sVEGFR2 levels between the groups (p: .519).Conclusions: We think that the effect of isotretinoin on sVEGFR1, sVEGFR2 and sVEGFR3 may be secondary to its effects on the VEGF family. However, after clarifying the effect of isotretinoin on the VEGF family, we think that it can be used in some tumors and vascular diseases.

Role of Endogenous Regulators of Hem- And Lymphangiogenesis in Corneal Transplantation

Under normal conditions, the cornea, being the transparent “windscreen” of the eye, is free of both blood and lymphatic vessels. However, various diseases of the eye, like infections, can interfere with the balance between promoting and inhibiting factors, which leads to ingrowth of blood and lymphatic vessels. The newly formed lymphatic vessels increase the risk of graft rejection after subsequent corneal transplantation. Corneal transplantation is one of the most commonly performed transplantations worldwide, with more than 40,000 surgeries per year in Europe. To date, various anti-hem- and anti-lymphangiogenic treatment strategies have been developed specifically for the corneal vascular endothelial growth factor (VEGF) pathway. Currently, however, no treatment strategies are clinically available to specifically modulate lymphangiogenesis. In this review, we will give an overview about endogenous regulators of hem- and lymphangiogenesis and discuss potential new strategies for targeting pathological lymphangiogenesis. Furthermore, we will review recently identified modulators and demonstrate that the cornea is a suitable model for the identification of novel endogenous modulators of lymphangiogenesis. The identification of novel modulators of lymphangiogenesis and a better understanding of the signaling pathways involved will contribute to the development of new therapeutic targets for the treatment of pathological lymphangiogenesis. This, in turn, will improve graft rejection, not only for the cornea.

Neuron-specific deletion of VEGF or its receptor Flk-1 impairs recognition memory

Vascular endothelial growth factor (VEGF, also known as VEGF-A) is a pleiotropic factor which is expressed by neurons, astrocytes and perivascular macrophages, as well as endothelial cells, in the brain. Recently, VEGF signaling has been implicated in learning and memory, and several clinical and preclinical studies demonstrate that VEGF inhibitors induce cognitive impairment. However, the role of endogenous neuronal VEGF signaling in recognition memory remains unclear. Recently, we have developed mice with forebrain excitatory neuron-specific deletion of VEGF or its receptor, fetal liver kinase 1 (Flk-1) by crossing Camk2a-Cre mice with Vegfa^flox/flox and Flk-1^flox/flox mice, respectively. Using these conditional knockout mice, the present study addressed the influence of forebrain excitatory neuron-specific deletion of VEGF or Flk-1 on recognition memory in the novel object recognition test. The results show that both short-term (2 h) and long-term (24 h) recognition memory are impaired by neuron-specific deletion of either Flk-1 or VEGF. These findings indicate the physiological importance of endogenous neuronal VEGF-Flk-1 signaling in recognition memory. In addition, the current results also suggest that the impairment of neuronal VEGF-Flk-1 signaling can be a cause of anti-VEGF chemotherapy-induced cognitive impairment.

Generation of a self-cleaved inducible Cre recombinase for efficient temporal genetic manipulation

Site-specific recombinase-mediated genetic technology, such as inducible Cre-loxP recombination (CreER), is widely used for in vivo genetic manipulation with temporal control. The Cre-loxP technology improves our understanding on the in vivo function of specific genes in organ development, tissue regeneration, and disease progression. However, inducible CreER often remains inefficient in gene deletion. In order to improve the efficiency of gene manipulation, we generated a self-cleaved inducible CreER (sCreER) that switches inducible CreER into a constitutively active Cre by itself. We generated endocardial driver Npr3-sCreER and fibroblast driver Col1a2-sCreER, and compared them with conventional Npr3-CreER and Col1a2-CreER, respectively. For easy-to-recombine alleles such as R26-tdTomato, there was no significant difference in recombination efficiency between sCreER and the conventional CreER. However, for alleles that were relatively inert for recombination such as R26-Confetti, R26-LZLT, R26-GFP, or VEGFR2^flox/flox alleles, sCreER showed a significantly higher efficiency in recombination compared with conventional CreER in endocardial cells or fibroblasts. Compared with conventional CreER, sCreER significantly enhances the efficiency of recombination to induce gene expression or gene deletion, allowing temporal yet effective in vivo genomic modification for studying gene function in specific cell lineages.

The Impact of Kinase Insert Domain (KDR) Gene Polymorphism rs2305948 on Clopidogrel Resistance in Iraqi Patients Undergoing Elective Percutaneous Coronary Intervention (PCI)

Introduction:

Clopidogrel, the first-choice antiplatelet agent for patient undergoing Percutaneous Coronary Intervention (PCI) along with Aspirin. Clopidogrel resistance is one of the major obstacles that cause MACE and failure of PCI. Kinase Insert Domain (KDR) gene responsible for VEGFR2 coding, the major receptor that translates VEGF ligand. The rs2305948 SNP in VEGFR2 gene has been documented to be involved atherogenesis and in CAD pathogenesis.

Aim:

To study the impact of KDR gene polymorphism rs2305948 on clopidogrel resistance in patients undergoing elective PCI.

Methods:

A case control study with 324 patients documented for elective PCI whom divided according to platelet aggregation level measured into (CR) with 111patients and (NCR) that consists of 213 patients. Serum lipids and VEGFR2 levels, BMI and platelet count were measured. Genotype for rs2305948 was done by PCR-RFLP.

Results:

Allele frequency and genotype results indicate a significant association with the pathogenesis of CR in all models in CR group compared to NCR group, a significant correlation for T allele with LDL, cholesterol and serum VEGFR2 in dominant and co-dominant models. RFLP-PCR results were documented by gene sequencing and results were compatible with HWE.

Conclusion:

rs2305948 SNP is associated with occurrences of CR and have an influence in the development of other metabolic changes.

Biomarkers of Prognosis and Efficacy of Anti-angiogenic Therapy in Metastatic Clear Cell Renal Cancer

In the last decades, the prognosis of metastatic renal cell carcinoma (mRCC) has remarkably improved following the advent of the "targeted therapy" era. The expanding knowledge on the prominent role played by angiogenesis in RCC pathogenesis has led to approval of multiple anti-angiogenic agents such as sunitinib, pazopanib, axitinib, cabozantinib, sorafenib, and bevacizumab. These agents can induce radiological responses and delay cancer progression for months or years before onset of resistance, with a clinically meaningful activity. The need for markers of prognosis and efficacy of anti-angiogenic agents has become more compelling as novel systemic immunotherapy agents have also been approved in RCC and can be administered as an alternative to angiogenesis inhibitors. Anti PD-1 monoclonal antibody nivolumab has been approved in the second-line setting after tyrosine kinase inhibitors failure, while combination of nivolumab plus anti CTLA-4 monoclonal antibody ipilimumab has been approved as first-line therapy of RCC patients at intermediate or poor prognosis. In this review article, biomarkers of prognosis and efficacy of antiangiogenic therapies are summarized with a focus on those that have the potential to affect treatment decision-making in RCC. Biomarkers predictive of toxicity of anti-angiogenic agents have also been discussed.

Does an imbalance in circulating vascular endothelial growth factors (VEGFs) cause atrial fibrillation in patients with valvular heart disease?

Background

The pathogenesis of atrial fibrillation (AF) remains unclear. Vascular endothelial growth factors (VEGFs) can stimulate fibrosis within the atrium and ventricle. We hypothesized that there is a relationship between the serum VEGFs/soluble vascular endothelial growth factor receptor (sVEGFRs) levels and AF in patients with valvular heart disease (VHD). This provides a new paradigm for studying AF.

Methods

The plasma levels of VEGF-A, VEGF-C, sVEGFR-1 and sVEGFR-2 were detected by enzyme-linked immunosorbent assay (ELISA). A total of 100 people, consisting of AF patients (long-standing, persistent AF; n=49), sinus rhythm (SR) patients (n=31) and healthy controls (n=20), were included in this study.

Results

The plasma levels of VEGF-A were significantly higher in AF patients compared to healthy control (P<0.05). The plasma levels of sVEGFR-1 were significantly higher in AF compared to SR (P<0.05). The plasma levels of sVEGFR-2 were significantly lower in AF patients compared to SR patients and healthy controls (both P<0.05). There was a significant and negative correlation between AF and the sVEGFR-2 levels in the groups (r=-0.432, P=0.000).

Conclusions

An imbalance in VEGFs and sVEGFRs may contribute to AF by breaking the balance of angiogenesis and lymphangiogenesis. Additionally, sVEGFR-2 may be an important biomarker of AF.

Communication Of Cancer Cells And Lymphatic Vessels In Cancer: Focus On Bladder Cancer

Bladder cancer is one of the most commonly diagnosed cancers worldwide and causes the highest lifetime treatment costs per patient. Bladder cancer is most likely to metastasize through lymphatic ducts, and once the lymph nodes are involved, the prognosis is poorly and finitely improved by current modalities. The underlying metastatic mechanism for bladder cancer is thus becoming a research focus to date. To identify relevant published data, an online search of the PubMed/Medline archives was performed to locate original articles and review articles regarding lymphangiogenesis and lymphatic metastasis in urinary bladder cancer (UBC), and was limited to articles in English published between 1998 and 2018. A further search of the clinical trials.gov search engine was conducted to identify both trials with results available and those with results not yet available. Herein, we summarized the unique mechanisms and biomarkers involved in the malignant progression of bladder cancer as well as their emerging roles in therapeutics, and that current data suggests that lymphangiogenesis and lymph node invasion are important prognostic factors for UBC. The growing knowledge about their roles in bladder cancers provides the basis for novel therapeutic strategies. In addition, more basic and clinical research needs to be conducted in order to identify further accurate predictive molecules and relevant mechanisms.