VEGF ligands and receptors: implications in neurodevelopment and neurodegeneration

Targeting the tumour vasculature: from vessel destruction to promotion

As angiogenesis was recognized as a core hallmark of cancer growth and survival, several strategies have been implemented to target the tumour vasculature. Yet to date, attempts have rarely been so diverse, ranging from vessel growth inhibition and destruction to vessel normalization, reprogramming and vessel growth promotion. Some of these strategies, combined with standard of care, have translated into improved cancer therapies, but their successes are constrained to certain cancer types. This Review provides an overview of these vascular targeting approaches and puts them into context based on our subsequent improved understanding of the tumour vasculature as an integral part of the tumour microenvironment with which it is functionally interlinked. This new knowledge has already led to dual targeting of the vascular and immune cell compartments and sets the scene for future investigations of possible alternative approaches that consider the vascular link with other tumour microenvironment components for improved cancer therapy.

Molecular characterization of vascular endothelial growth factor b from spotted sea bass (Lateolabrax maculatus) and its potential roles in decreasing lipid deposition

Vascular endothelial growth factor B (VEGFB), a member of the VEGF family, exhibits limited angiogenic activity in mammals but plays an unexpected role in targeting lipids to peripheral tissues. However, its role in lipid metabolism in fish is unknown. In this study, the vegfb gene was cloned and characterized from spotted sea bass (Lateolabrax maculatus). It encodes 254 amino acids and possesses the typical characteristics of the Vegfb family, demonstrating high homology with those from other vertebrate species. The vegfb gene exhibits the highest expression levels in the liver, followed by the gills, intestine, and adipose tissues in spotted sea bass. In vivo, high-lipid diets decreased vegfb expression and increased lipid deposition in liver of fish. In vitro, palmitic acid + oleic acid treatment or vegfb knockdown significantly increased TG and TC contents, promoting lipid droplet deposition in hepatocytes. Vegfb overexpression has the opposite effects, inhibiting lipid deposition and downregulating fatty acid transport and adipogenesis genes. In contrast, the vegfb knockdown significantly upregulated the expression levels of c/ebpα, plin2, and dgat1 (P < 0.05). These results demonstrate that Vegfb may play an important role in reducing lipid deposition by regulating fatty acid transport and adipogenesis in the hepatocytes of spotted sea bass.

VEGF and Neuronal Survival

Vascular endothelial growth factor (VEGF) is well known for its angiogenic activity, but recent evidence has revealed a neuroprotective action of this factor on injured or diseased neurons. In the present review, we summarize the most relevant findings that have contributed to establish a link between VEGF deficiency and neuronal degeneration. At issue, 1) mutant mice with reduced levels of VEGF show adult-onset muscle weakness and motoneuron degeneration resembling amyotrophic lateral sclerosis (ALS), 2) administration of VEGF to different animal models of motoneuron degeneration improves motor performance and ameliorates motoneuronal degeneration, and 3) there is an association between low plasmatic levels of VEGF and human ALS. Altogether, the results presented in this review highlight VEGF as an essential motoneuron neurotrophic factor endowed with promising therapeutic potential for the treatment of motoneuron disorders.

Changes in Neurodegeneration and Visual Prognosis in Branch Retinal Vein Occlusion after Resolution of Macular Edema

This study aimed to examine the thicknesses of the ganglion cell layer (GCL) and peripapillary retinal nerve fiber layer (RNFL) in eyes with resolved macular edema (ME) in branch retinal vein occlusion (BRVO) and determine their relationship with visual acuity (VA). This retrospective observational case-control study included 57 eyes of BRVO patients with resolved ME after treatment. The macular GCL thickness, peripapillary RNFL thickness, and central macular thickness (CMT) measured on swept-source optical coherence tomography scans with the contralateral eyes used as controls were evaluated. The mean CMT was 270.48 ± 32.7 μm; the mean RNFL thickness was 105.46 ± 25.94 μm in BRVO eyes. Although the average RNFL thickness was decreased in BRVO eyes compared to unaffected eyes, there was no significant difference between the groups. However, the temporal and nasal RNFL thicknesses were significantly different between the groups. The mean affected quadrant had a significantly thinner GCL compared to the corresponding opposite unaffected quadrant (p = 0.02). Final VA was significantly correlated with nasal and middle GCL thicknesses in the affected area (r = -0.512, p = 0.003 and r = -0.537, p = 0.001, respectively); no correlation was found between the average RNFL thickness and mean CMT. The peripapillary RNFL and GCL thicknesses of the affected area were reduced in BRVO eyes compared to unaffected eyes. VA significantly correlated with nasal and middle GCL thicknesses in the affected area. Inner retinal damage occurring in patients with ME secondary to BRVO may be related to the visual prognosis.

Burn Injury-related Growth Factor Expressions and Their Potential Roles in Burn-related Neuropathies

In the context of burn injury, growth factors (GFs) play a significant role in mediating the complex local and systematic processes that occur. Among the many systemic complications that arise following a burn injury, peripheral neuropathy remains one of the most common. Despite the broad understanding of the effects GFs have on multiple tissues, their potential implications in both wound healing and neuropathy remain largely unexplored. Therefore, this review aims to investigate the expression patterns of GFs prominent during the burn wound healing process and explore the potential contributions these GFs have on the development of burn-related peripheral neuropathy.

Reduced Brain Cortex Angiogenesis in the Offspring of the Preeclampsia-Like Syndrome

BACKGROUND

Children from pregnancies affected by preeclampsia have an increased risk of cognitive and behavioral alterations via unknown pathophysiology. We tested the hypothesis that preeclampsia generated reduced brain cortex angiogenesis in the offspring.

METHODS

The preeclampsia-like syndrome (PELS) mouse model was generated by administering the nitric oxide inhibitor NG-nitroarginine methyl ester hydrochloride. Confirmatory experiments were done using 2 additional PELS models. While in vitro analysis used mice and human brain endothelial cells exposed to serum of postnatal day 5 pups or umbilical plasma from preeclamptic pregnancies, respectively.

RESULTS

We report significant reduction in the area occupied by blood vessels in the motor and somatosensory brain cortex of offspring (postnatal day 5) from PELS compared with uncomplicated control offspring. These data were confirmed using 2 additional PELS models. Furthermore, circulating levels of critical proangiogenic factors, VEGF (vascular endothelial growth factor), and PlGF (placental growth factor) were lower in postnatal day 5 PELS. Also we found lower VEGF receptor 2 (KDR [kinase insert domain-containing receptor]) levels in mice and human endothelial cells exposed to the serum of postnatal day 5 PELS or fetal plasma of preeclamptic pregnancies, respectively. These changes were associated with lower in vitro angiogenic capacity, diminished cell migration, larger F-actin filaments, lower number of filopodia, and lower protein levels of F-actin polymerization regulators in brain endothelial cells exposed to serum or fetal plasma of offspring from preeclampsia.

CONCLUSIONS

Offspring from preeclampsia exhibited diminished brain cortex angiogenesis, associated with lower circulating VEGF/PlGF/KDR protein levels, impaired brain endothelial migration, and dysfunctional assembly of F-actin filaments. These alterations may predispose to structural and functional alterations in long-term brain development.

VEGF-A ameliorates ischemia hippocampal neural injury via regulating autophagy and Akt/CREB signaling in a rat model of chronic cerebral hypoperfusion

OBJECTIVE

Chronic cerebral hypoperfusion (CCH) can cause a series of pathophysiological processes, including neuronal autophagy and apoptosis. VEGF-A has been reported to affect angiogenesis and neurogenesis in many CNS diseases. However, its effects on neuronal autophagy and apoptosis, as well as the underlying mechanisms in CCH remain unclear.

METHODS

To address these issues, the CCH model was established by permanent bilateral common carotid artery occlusion (2VO). Rats were sacrificed at different stages of CCH. Hippocampal morphological and ultrastructural changes were detected using HE staining and electron microscopy. The immunoreactivities of microtubule-associated protein 1 light chain 3 (LC3) and phospho-cAMP response element binding protein (p-CREB) were examined by immunofluorescence staining. The neuronal apoptosis was detected via TUNEL staining. The levels of LC3-II, Beclin-1, Akt, p-Akt, CREB, p-CREB, Caspase-3, and Bad were accessed by Western blotting. Furthermore, mouse hippocampal HT22 neurons received the oxygen and glucose deprivation (OGD) treatment, VEGF-A treatment, and GSK690693 (an Akt inhibitor) treatment, respectively.

RESULTS

LC3-II protein started to increase at 3 days of CCH, peaked at 4 weeks of CCH, then decreased. CCH increased the levels of LC3-II, Caspase-3, and Bad, and decreased the levels of p-Akt, CREB, and p-CREB, which were reversed by VEGF-A treatment. VEGF-A also improved CCH-induced neuronal ultrastructural injuries and apoptosis in the hippocampus in vitro. In HT22, the anti-apoptosis and pro-phosphorylation of VEGF-A were reversed by GSK690693.

CONCLUSION

Present results provide a novel neuroprotective effect of VEGF-A in CCH that is related to the inhibition of neuronal autophagy and activation of the Akt/CREB signaling, suggesting a potential therapeutic strategy for ischemic brain damage.

How Neuromembrane Lipids Modulate Membrane Proteins: Insights from G-Protein-Coupled Receptors (GPCRs) and Receptor Tyrosine Kinases (RTKs)

Lipids play a diverse and critical role in cellular processes in all tissues. The unique lipid composition of nerve membranes is particularly interesting because it contains, among other things, polyunsaturated lipids, such as docosahexaenoic acid, which the body only gets through the diet. The crucial role of lipids in neurological processes, especially in receptor-mediated cell signaling, is emphasized by the fact that in many neuropathological diseases there are significant deviations in the lipid composition of nerve membranes compared to healthy individuals. The lipid composition of neuromembranes can significantly affect the function of receptors by regulating the physical properties of the membrane or by affecting specific interactions between receptors and lipids. In addition, it is worth noting that the ligand-binding pocket of many receptors is located inside the cell membrane, due to which lipids can even modulate the binding of ligands to their receptors. These mechanisms highlight the importance of lipids in the regulation of membrane receptor activation and function. In this article, we focus on two major protein families: G-protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) and discuss how lipids affect their function in neuronal membranes, elucidating the basic mechanisms underlying neuronal function and dysfunction.

Dexmedetomidine attenuates sleep deprivation-induced inhibition of hippocampal neurogenesis via VEGF-VEGFR2 signaling and inhibits neuroinflammation

Long periods of sleep deprivation (SD) have serious effects on health. While the α2 adrenoceptor agonist dexmedetomidine (DEX) can improve sleep quality for patients who have insomnia, the effect of DEX on cognition and mechanisms after SD remains elusive. C57BL/6 mice were subjected to 20 h SD daily for seven days. DEX (100 μg/kg) was administered intravenously twice daily (at 1:00 p.m. and 3:00 p.m.) during seven days of SD. We found that systemic administration of DEX attenuated cognitive deficits by performing the Y maze and novel object recognition tests and increased DCX+, SOX2+, Ki67+, and BrdU+NeuN+/NeuN+ cell numbers in the dentate gyrus (DG) region of SD mice by using immunofluorescence, western blotting, and BrdU staining. DEX did not reverse the decrease in DCX+, SOX2+, or Ki67+ cell numbers in SD mice after administration of the α2A-adrenoceptor antagonist BRL-44408. Furthermore, the vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 (VEGFR2) expression was upregulated in SD+DEX mice compared with SD mice. Luminex analysis showed that the neurogenic effects of DEX were possibly related to the inhibition of neuroinflammation, including IL-1α, IL-2, CCL5, and CXCL1. Our results suggested that DEX alleviated the impaired learning and memory of SD mice potentially by inducing hippocampal neurogenesis via the VEGF-VEGFR2 signaling pathway and by suppressing neuroinflammation, and α2A adrenoceptors are required for the neurogenic effects of DEX after SD. This novel mechanism may add to our knowledge of DEX in the clinical treatment of impaired memory caused by SD.

A Meta-Analysis of Neurodevelopmental Outcomes following Intravitreal Bevacizumab for the Treatment of Retinopathy of Prematurity

BACKGROUND

Retinopathy of prematurity (ROP) is the most common cause of preventable blindness in preterm infants. First-line treatments include intravitreal bevacizumab (IVB) or laser photocoagulation (LPC).

OBJECTIVES

The aim of the study was to evaluate neurodevelopmental safety of IVB compared to LPC for ROP.

METHODS

MEDLINE, Embase, and Cochrane library were searched up to September 2022. Studies were included with at least 12-month follow-up of primary outcomes such as severe neurodevelopmental impairment (sNDI), cerebral palsy (CP), and hearing impairment (HI). Secondary outcomes were moderate-to-severe neurodevelopmental impairment (msNDI), Bayley Scores of Infant Development (BSID-III), and visual impairment.

RESULTS

1,231 patients from 11 comparative studies were included. Quality of evidence was rated low for all outcomes. IVB was associated with a higher risk for sNDI (risk ratio [RR] = 1.25, 95% confidence interval [CI]: [1.01, 1.53], p = 0.04); and CP (RR = 1.40, CI: [1.08, 1.81], p = 0.01) compared to LPC. There was no significant difference between IVB and LPC for msNDI (RR = 1.15, CI: [0.98, 1.35], p = 0.08) and HI (RR = 1.43, CI: [0.86, 2.39], p = 0.17). BSID-III percentile scores were similar between IVB and LPC, with weighted mean differences of 1.51 [CI = -1.25, 4.27], 2.43 [CI = -1.36, 6.22], and 1.97 [CI = -1.06, 5.01] for cognitive, language, and motor domains, respectively (p > 0.05).

CONCLUSION

To our knowledge, this is the largest meta-analysis on neurodevelopmental outcomes and the first to rigorously examine IVB monotherapy in ROP treatment. Compared to LPC, there was a marginally increased risk for sNDI and CP with IVB but little or no difference in the risk of msNDI and HI. Further randomized studies are needed to strengthen these findings.

The Labyrinthine Landscape of APP Processing: State of the Art and Possible Novel Soluble APP-Related Molecular Players in Traumatic Brain Injury and Neurodegeneration

Amyloid Precursor Protein (APP) and its cleavage processes have been widely investigated in the past, in particular in the context of Alzheimer’s Disease (AD). Evidence of an increased expression of APP and its amyloidogenic-related cleavage enzymes, β-secretase 1 (BACE1) and γ-secretase, at the hit axon terminals following Traumatic Brain Injury (TBI), firstly suggested a correlation between TBI and AD. Indeed, mild and severe TBI have been recognised as influential risk factors for different neurodegenerative diseases, including AD. In the present work, we describe the state of the art of APP proteolytic processing, underlining the different roles of its cleavage fragments in both physiological and pathological contexts. Considering the neuroprotective role of the soluble APP alpha (sAPPα) fragment, we hypothesised that sAPPα could modulate the expression of genes of interest for AD and TBI. Hence, we present preliminary experiments addressing sAPPα-mediated regulation of BACE1, Isthmin 2 (ISM2), Tetraspanin-3 (TSPAN3) and the Vascular Endothelial Growth Factor (VEGFA), each discussed from a biological and pharmacological point of view in AD and TBI. We finally propose a neuroprotective interaction network, in which the Receptor for Activated C Kinase 1 (RACK1) and the signalling cascade of PKCβII/nELAV/VEGF play hub roles, suggesting that vasculogenic-targeting therapies could be a feasible approach for vascular-related brain injuries typical of AD and TBI.

Circulating levels of vascular endothelial growth factor in patients with Alzheimer's disease: A case-control study

BACKGROUND

Vascular endothelial growth factor (VEGF) and platelets seem to reflect the Alzheimer's disease (AD) associated either with vascular impairment or disease. This study aimed to compare the circulating levels of VEGF and platelets between AD patients and healthy older adults.

METHODS

Seventy-two older adults, divided in 40 older adults (Clinical Dementia Rating Scale - CDR = 0); and 32 Alzheimer's disease patients (clinically diagnosed - CRD = 1) participated in the present study. The groups were paired by sex, age, comorbidities and educational level. The primary outcomes included circulating plasma VEGF and platelet levels obtained by blood collection.

RESULTS

The VEGF levels were significantly different between the groups (p = 0.03), with having a large effect size ( η² =18.15), in which the AD patients presented lower levels compared to healthy older adults. For platelets, the comparison showed a tendency to difference (p = 0.06), with a large effect size (η² =12.95) between the groups.

CONCLUSION

The VEGF levels and the platelet numbers were reduced in AD patients, suggesting that angiogenic factors could be modified due to AD.

Serum Levels of VEGF-A and Its Receptors in Patients in Different Phases of Hemorrhagic and Ischemic Strokes

Vascular endothelial growth factors (VEGFs) are important regulators of angiogenesis, neuroprotection, and neurogenesis. Studies have indicated the association of VEGF dysregulation with the development of neurodegenerative and cerebrovascular diseases. We studied the changes in serum levels of VEGF-A, VEGFR-1, and VEGFR-2 in patients at various phases of ischemic and hemorrhagic strokes. Quantitative assessment of VEGF-A, VEGFR-1, and VEGFR-2 in serum of patients with hemorrhagic or ischemic stroke was performed by enzyme immunoassay in the hyper-acute (1−24 h from the onset), acute (up to 1−7 days), and early subacute (7 days to 3 months) phases of stroke, and then compared with the control group and each other. Results of our retrospective study demonstrated different levels of VEGF-A and its receptors at various phases of ischemic and hemorrhagic strokes. In ischemic stroke, increased VEGFR-2 level was found in the hyper-acute (p = 0.045) and acute phases (p = 0.024), while elevated VEGF-A and reduced VEGFR-1 levels were revealed in the early subacute phase (p = 0.048 and p = 0.012, respectively). In hemorrhagic stroke, no significant changes in levels of VEGF-A and its receptors were identified in the hyper-acute phase. In the acute and early subacute phases there was an increase in levels of VEGF-A (p < 0.001 and p = 0.006, respectively) and VEGFR-2 (p < 0.001 and p = 0.012, respectively). Serum levels of VEGF-A and its receptors in patients with hemorrhagic and ischemic stroke indicate different pathogenic pathways depending on the phase of the disease.

A robust quantitative approach for laser speckle contrast imaging perfusion analysis revealed anomalies in the brain blood flow in offspring mice of preeclampsia

Microcirculation analysis of the brain cortex is challenging because surface perfusion varies rapidly in small space-time regions and is bone protected. The laser speckle contrast imaging (LSCI) technique allows analyzing in vivo brain vascular perfusion generating a large amount of data that requires sophisticated data analytics, making researchers invest much effort in processing. Our research question was whether the reduced placental perfusion model (RUPP) of preeclampsia (PE) was associated with impaired blood perfusion in the offspring's brains. We aimed to develop a robust numerical approach that mainly consisted of applying a signal-processing tool for calculating optimal segmentation and piece-wise fits of the offspring's brain perfusion signals obtained from the LSCI technique. We combined this tool with the usual statistical analysis, implementing both in Matlab software. We performed brain perfusion measurements from offspring (five days postnatal, P5) of control pregnant dams (sham, n = 13) and of RUPP dams (RUPP, n = 7) using the Pericam® PSI-HR system at a basal condition and after thermal stimuli (warm and cold). We found that pups of RUPP mice exhibited significant differences in perfusion and vascular response to thermal stimuli compared to the sham mice. These differences were associated with high data variability in the Sham group, while in the RUPP group, perfusion looks "stiffer." Data also suggest sex-dimorphism in the vascular response since female pups in the Sham group but not male pups showed statistically significant differences in response to the warm stimulus. Again, this sex-related difference was absent in pups of RUPP mice. In conclusion, we present a robust quantitative approach for LSCI measurements that revealed anomalies in the brain blood flow in offspring of the RUPP model of PE.

VEGF receptor heterodimers and homodimers are differentially expressed in neuronal and endothelial cell types

PURPOSE

We have previously reported that VEGF-B is more potent than VEGF-A in mediating corneal nerve growth in vitro and in vivo, and this stimulation of nerve growth appears to be different from stimulation of angiogenesis by these same ligands, at least in part due to differences in VEGF receptor activation. VEGF signaling may be modulated by a number of factors including receptor number or the formation of receptor hetero- vs. homodimers. In endothelial cells, VEGF receptor heterodimer (VEGR1/R2) activation after ligand binding and subsequent phosphorylation alters the activation of downstream signaling cascades. However, our understanding of these processes in neuronal cell types remains unclear. The purpose of this study was to identify the presence and distribution of VEGF Receptor-Ligand interactions in neuronal cells as compared to endothelial cells.

METHODS

PC12 (rat neuronal cell line), MAEC (mouse aortic endothelial cell line), MVEC (mouse venous endothelial cell line) and HUVEC (human umbilical venous endothelial cell line; control group) were used. Cells were acutely stimulated either with VEGF-A (50 ng/μL) or VEGF-B (50 ng/μL) or "vehicle" (PBS; control group). We also isolated mouse trigeminal ganglion cells from thy1-YFP neurofluorescent mice. After treatment, cells were used as follows: (i) One group was fixed in 4% paraformaldehyde and processed for VEGFR1 and VEGFR2 immunostaining and visualized using confocal fluorescence microscopy and Total Internal Reflection (TIRF) microscopy; (ii) the second group was harvested in cell lysis buffer (containing anti-protease / anti-phosphatase cocktail), lysed and processed for immunoprecipitation (IP; Thermo Fisher IP kit) and immunoblotting (IB; LI-COR® Systems). Immunoprecipitated proteins were probed either with anti-VEGFR1 or anti-VEGFR2 IgG antibodies to evaluate VEGFR1-R2-heterodimerization; (iii) a third group of cells was also processed for Duolink Proximity Ligation Assay (PLA; Sigma) to assess the presence and distribution of VEGF-receptor homo- and heterodimers in neuronal and endothelial cells.

RESULTS

TIRF and fluorescence confocal microscopy revealed the presence of VEGFR1 co-localized with VEGFR2 in endothelial and PC12 neuronal cells. Cell lysates immunoprecipitated with anti-VEGFR1 further validated the existence of VEGFR1-R2 heterodimers in PC12 neuronal cells. Neuronal cells showed higher levels of VEGFR1-R2 heterodimers as compared to endothelial cells whereas endothelial cells showed higher VEGFR2-R2 homodimers compared to neuronal cells as demonstrated by Duolink PLA. Levels of VEGFR1-R1 homodimers were very low in neuronal and endothelial cells.

CONCLUSIONS

Differences in VEGF Receptor homo- and heterodimer distribution may explain the differential role of VEGF ligands in neuronal versus endothelial cell types. This may in turn influence VEGF activity and regulation of neuronal cell homeostasis.

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.

Brain single-nucleus transcriptomics highlights that polystyrene nanoplastics potentially induce Parkinson's disease-like neurodegeneration by causing energy metabolism disorders in mice

With the prevalence of nanoplastics in daily life, human exposure is inevitable. However, whether and how nanoplastics cause neurotoxicity in humans remains obscure. Herein, we conducted a 28-day repeated dose oral toxicity study in C57BL/6 J mice exposed to 0.25-250 mg/kg body weight (BW) polystyrene nanoplastics (PS-NPs, 50 nm). We revealed that PS-NP-caused Parkinson's disease (PD)-like neurodegeneration in mice by multiple approaches. Furthermore, a single-nucleus RNA sequencing of 62,843 brain nuclei unearthed PS-NP-induced cell-specific responses in the mouse brains. These disturbed responses among various brain cells were primarily linked with energy metabolism disorder and mitochondrial dysfunction in all brain cells, and especially in excitatory neurons, accompanied by inflammatory turbulence in astrocytes and microglia, dysfunction of proteostasis and synaptic-function regulation in astrocytes, oligodendrocytes, and endotheliocytes. These responses may synergize in PS-NP-motivated PD-like neurodegeneration pathogenesis. Moreover, we verified these single-nucleus transcriptomics findings on different brain regions and found that PS-NPs potentially caused PD-like neurodegeneration primarily by causing energy metabolism disorder in the substantia nigra pars compacta (SNc) and striatum. This manifested as decreases in adenosine triphosphate (ATP) content and expression levels of ATP-associated genes and proteins. Given nanoplastics' inevitable and growing exposure risks to humans, the neurological health risks of nanoplastic exposure warrant serious consideration.

Comparison of each retinal layer thicknesses between eyes with CRVO and normal contralateral eyes

Purpose

To evaluate the difference in each retinal layer thickness in central retinal vein occlusion (CRVO) with resolved macular edema after intravitreal antivascular endothelial growth factor injection and normal contralateral eyes..

Methods

Patients with ischemic and nonischemic CRVO whose macular edema resolved after intravitreal antivascular endothelial growth factor injections and did not recur for at least 6 months, and a normal contralateral eye were enrolled. Each retinal layer thickness between CRVO and normal contralateral eyes was compared according to Early Treatment Diabetic Retinopathy Study subfields using spectral domain optical coherence tomography.

Results

The thicknesses of outer nuclear layer, photoreceptor layer, and retinal pigment epithelium in central ring, ganglion cell layer, inner plexiform layer, outer nuclear layer, and photoreceptor layer in the inner ring, and ganglion cell layer in the outer ring of CRVO eyes were significantly thinner than those of normal contralateral eyes (all p < 0.05). Whereas, inner nuclear layer and outer plexiform layer thicknesses in central ring of CRVO eyes were 23.86 ± 8.8 and 25.76 ± 7.6 μm, respectively, which was significantly thicker than those of normal contralateral eyes (19.52 ± 7.7 and 22.76 ± 6.5 μm; p = 0.019 and p = 0.043, respectively). Additionally, the mean best-corrected visual acuity of CRVO eyes were significantly correlated with photoreceptor layer thickness in central ring (p = 0.005).

Conclusions

In CRVO eyes with resolved macular edema, the outer retinal layers were thinner as well as inner retinal layers, whereas inner plexiform layer and outer nuclear layer were thicker than normal fellow eyes. Additionally, photoreceptor layer thickness in foveal area had a significant impact on visual acuity in CRVO.

Maternal vitamin D deficiency reduces docosahexaenoic acid, placental growth factor and peroxisome proliferator activated receptor gamma levels in the pup brain in a rat model of preeclampsia

BACKGROUND

Preeclampsia is a pregnancy disorder characterized with abnormal placental angiogenesis. Vitamin D and long chain polyunsaturated fatty acids (LCPUFA) play a crucial role in pregnancy and are required for normal placental and fetal growth and development. This study reports the effect of maternal vitamin D on LCPUFA levels in the mother and offspring brain fatty acid levels and angiogenic markers in a rat model of preeclampsia.

METHODS

Female rats were divided into four groups from pre-pregnancy to pregnancy, viz Control; Preeclampsia (PE); Vitamin D deficient with PE (VDD-PE) and Vitamin D supplemented with PE (VDS-PE). Preeclampsia was induced by administering l-nitroarginine methyl ester (L-NAME) at the dose of 50 mg/kg body weight/day from day 14 to day 19 of gestation. Dams were sacrificed at d20 of gestation to collect dam blood, placenta and pup brain. LCPUFA levels from dam plasma, erythrocytes and placenta and its transcription factor peroxisome proliferator activated receptor gamma (PPAR-g) from placenta were estimated. Pup brain LCPUFA levels, angiogenic factors vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) and transcription factor hypoxia inducible factor (Hif-1α) and PPAR-g were also estimated.

RESULTS

Maternal vitamin D status influences fatty acid levels. Placental PPAR-g levels were lower in the VDD-PE group as compared to the VDS-PE groups (p < 0.01). In the offspring brain, both PE and VDD-PE group showed lower levels of DHA (p < 0.05 for both) while saturated fatty acids (SFA) levels in the VDD-PE group were higher as compared to the control group (p < 0.05). VDD-PE group also showed lower levels of PlGF and PPAR-g (p < 0.01 and p < 0.05, respectively) in the pup brain while vitamin D supplementation demonstrated levels similar to control.

CONCLUSION

This study for the first time demonstrates that maternal vitamin D status influences LCPUFA metabolism and angiogenesis in the offspring brain.

The relationship between vascular endothelial growth factor (VEGF) and amnestic mild cognitive impairment among older adults living with HIV

Older people with HIV (PWH) experience increased risk of age-related neurodegenerative disorders and cognitive decline, such as amnestic mild cognitive impairment (aMCI). The objective of this study was to examine the relationship between aMCI and plasma VEGF biomarkers among older PWH. Data were collected at a university-based research center from 2011 to 2013. Participants were 67 antiretroviral therapy-treated, virally suppressed PWH. Participants completed comprehensive neurobehavioral and neuromedical evaluations. aMCI status was determined using adapted Jak/Bondi criteria, classifying participants as aMCI + if their performance was > 1 SD below the normative mean on at least two of four memory assessments. VEGF family plasma biomarkers (i.e., VEGF, VEGF-C, VEGF-D, and PIGF) were measured by immunoassay. Logistic regression models were conducted to determine whether VEGF biomarkers were associated with aMCI status. Participants were mostly non-Hispanic white (79%) men (85%) with a mean age of 57.7 years. Eighteen (26.9%) participants met criteria for aMCI. Among potential covariates, only antidepressant drug use differed by aMCI status, and was included as a covariate. VEGF-D was significantly lower in the aMCI + group compared to the aMCI - group. No other VEGF levels (VEGF, VEGF-C, PIGF) differed by aMCI classification (ps > .05). In a sample of antiretroviral therapy-treated, virally suppressed PWH, lower levels of VEGF-D were associated with aMCI status. Longitudinal analyses in a larger and more diverse sample are needed to support VEGF-D as a putative biological marker of aMCI in HIV.

Serum VEGF and Ang-2 Levels in Infants Before and After Laser Treatment for Retinopathy of Prematurity

To investigate VEGF and Ang-2 level changes in the systemic circulation after laser photocoagulation in premature infants with ROP. Methods: Eleven infants (4 girls and 7 boys) had serum levels determined for VEGF and Ang-2, collected 1 day prior to and 7 days after ROP laser therapy. Serum levels of VEGF and Ang-2 were quantified by enzyme-linked immunosorbent assay (ELISA). Results: Serum VEGF levels were significantly lower at 7 days after laser therapy compared to that at 1 day prior to laser therapy (p = 0.045). Serum Ang-2 levels increased significantly at 7 days after laser therapy compared with that at 1 day prior to laser therapy (p = 0.046). Conclusions: Serum VEGF levels in patients with ROP were suppressed and Ang-2 levels elevated significantly after laser therapy. The results suggest that changes in VEGF and Ang-2 serum levels may reflect regression and treatment of ROP.

Expression Pattern of T-Type Ca2+ Channels in Cerebellar Purkinje Cells after VEGF Treatment

T-type Ca2+ channels, generating low threshold calcium influx in neurons, play a crucial role in the function of neuronal networks and their plasticity. To further investigate their role in the complex field of research in plasticity of neurons on a molecular level, this study aimed to analyse the impact of the vascular endothelial growth factor (VEGF) on these channels. VEGF, known as a player in vasculogenesis, also shows potent influence in the central nervous system, where it elicits neuronal growth. To investigate the influence of VEGF on the three T-type Ca2+ channel isoforms, Cav3.1 (encoded by Cacna1g), Cav3.2 (encoded by Cacna1h), and Cav3.3 (encoded by Cacna1i), lasermicrodissection of in vivo-grown Purkinje cells (PCs) was performed, gene expression was analysed via qPCR and compared to in vitro-grown PCs. We investigated the VEGF receptor composition of in vivo- and in vitro-grown PCs and underlined the importance of VEGF receptor 2 for PCs. Furthermore, we performed immunostaining of T-type Ca2+ channels with in vivo- and in vitro-grown PCs and showed the distribution of T-type Ca2+ channel expression during PC development. Overall, our findings provide the first evidence that the mRNA expression of Cav3.1, Cav3.2, and Cav3.3 increases due to VEGF stimulation, which indicates an impact of VEGF on neuronal plasticity.

Altered neurodevelopmental DNA methylation status after fetal growth restriction with brain-sparing

It is under debate how preferential perfusion of the brain (brain-sparing) in fetal growth restriction (FGR) relates to long-term neurodevelopmental outcome. Epigenetic modification of neurotrophic genes by altered fetal oxygenation may be involved. To explore this theory, we performed a follow-up study of 21 FGR children, in whom we prospectively measured the prenatal cerebroplacental ratio (CPR) with Doppler sonography. At 4 years of age, we tested their neurodevelopmental outcome using the Wechsler Preschool and Primary Scale of Intelligence, the Child Behavior Checklist, and the Behavior Rating Inventory of Executive Function. In addition, we collected their buccal DNA to determine the methylation status at predefined genetic regions within the genes hypoxia-inducible factor-1 alpha (HIF1A), vascular endothelial growth factor A (VEGFA), erythropoietin (EPO), EPO-receptor (EPOR), brain-derived neurotrophic factor (BDNF), and neurotrophic tyrosine kinase, receptor, type 2 (NTRK2) by pyrosequencing. We found that FGR children with fetal brain-sparing (CPR <1, n = 8) demonstrated a trend (0.05 < p < 0.1) toward hypermethylation of HIF1A and VEGFA at their hypoxia-response element (HRE) compared with FGR children without fetal brain-sparing. Moreover, in cases with fetal brain-sparing, we observed statistically significant hypermethylation at a binding site for cyclic adenosine monophophate response element binding protein (CREB) of BDNF promoter exon 4 and hypomethylation at an HRE located within the NTRK2 promoter (both p <0.05). Hypermethylation of VEGFA was associated with a poorer Performance Intelligence Quotient, while hypermethylation of BDNF was associated with better inhibitory self-control (both p <0.05). These results led us to formulate the hypothesis that early oxygen-dependent epigenetic alterations due to hemodynamic alterations in FGR may be associated with altered neurodevelopmental outcome in later life. We recommend further studies to test this hypothesis.

Involvement of vascular endothelial growth factor in schizophrenia

Vascular endothelial growth factor (VEGF), which acts as an angiogenic and neurotrophic factor, is involved the regulation of cerebral blood volume and flow in Schizophrenia (SCZ). Several evidence indicates that modification of brain blood circulation due to alterations in the VEGF system affects cognitive performance and brain function in patients with SCZ. The aim of this study is: 1) To analyze the literature data concerning the role of VEGF in modulating the angiogenic response in SCZ. These data are controversial because some studies found elevated VEGF serum levels of VEGF in patients with SCZ, whereas others demonstrated no significant differences between SCZ patients and controls. 2)To analyze the role of VEGF as a predictive factor on the effects of antipsychotics agents used in the treatment of SCZ. In this context, high VEGF levels, associated to better responses to antipsychotics, might be predictive of the use of first generation antipsycotic drugs, whereas low VEGF levels, expression of resistance to therapy, might be predictive for the use of second generation antipsycotic drugs.

Non-productive angiogenesis disassembles Aß plaque-associated blood vessels

The human Alzheimer's disease (AD) brain accumulates angiogenic markers but paradoxically, the cerebral microvasculature is reduced around Aß plaques. Here we demonstrate that angiogenesis is started near Aß plaques in both AD mouse models and human AD samples. However, endothelial cells express the molecular signature of non-productive angiogenesis (NPA) and accumulate, around Aß plaques, a tip cell marker and IB4 reactive vascular anomalies with reduced NOTCH activity. Notably, NPA induction by endothelial loss of presenilin, whose mutations cause familial AD and which activity has been shown to decrease with age, produced a similar vascular phenotype in the absence of Aß pathology. We also show that Aß plaque-associated NPA locally disassembles blood vessels, leaving behind vascular scars, and that microglial phagocytosis contributes to the local loss of endothelial cells. These results define the role of NPA and microglia in local blood vessel disassembly and highlight the vascular component of presenilin loss of function in AD.

Does blood flow limit acute hypoxia performance in larval zebrafish (Danio rerio)?

Oxygen uptake (ṀO₂) in larval zebrafish prior to maturation of the gill relies on cutaneous O₂ transfer. Under normoxic conditions, rates of cutaneous O₂ transfer are unaffected by haemoglobin availability but are diminished in fish lacking a functional circulatory system, suggesting that internal convection is critically involved in setting the resting ṀO₂ in zebrafish larvae, even when relying on cutaneous O₂ transfer. The reliance of ṀO₂ on blood circulation led to the first objective of the current study, to determine whether loss of internal convection would reduce acute hypoxia performance (as determined by measuring critical PO₂; P_crit) in larval zebrafish under conditions of moderate hypoxia (PO₂ = 55 mmHg) at 28.5 and 34 °C. Internal convection was eliminated by preventing development of blood vessels using morpholino knockdown of vascular endothelial growth factor (VEGF); these fish are termed VEGF morphants. Breathing frequency (f_V) and heart rate (f_H) also were measured (at 28.5 °C) to determine whether any detriment in performance might be linked to cardiorespiratory dysfunction. Although ṀO₂ was reduced in the VEGF morphants, there was no significant effect on P_crit at 28.5 °C. Raising temperature to 34 °C resulted in the VEGF morphants exhibiting a higher P_crit than the shams, suggesting an impairment of hypoxia tolerance in the morphants at the higher temperature. The usual robust increase in f_V during hypoxia was absent or attenuated in VEGF morphants at 4 and 5 days post fertilization (dpf), respectively. Resting f_H was reduced in the VEGF morphants and unlike the sham fish, the morphants did not exhibit hypoxic tachycardia at 4 or 5 dpf. The number of cutaneous neuroepithelial cells (presumptive O₂ chemoreceptors) was significantly higher in the VEGF morphants and thus the cardiorespiratory impairment in the morphants during hypoxia was unlikely related to inadequate peripheral O₂ sensing.

Brain stimulation effects on serum BDNF, VEGF, and TNFα in treatment-resistant psychiatric disorders

Resistance to pharmacological treatment poses a notable challenge for psychiatry. Such cases are usually treated with brain stimulation techniques, including repetitive transcranial magnetic stimulation (rTMS) and electroconvulsive therapy (ECT). Empirical evidence links treatment resistance to insufficient brain plasticity and chronic inflammation. Therefore, this study encompasses analysis of neurotrophic and inflammatory factors in psychiatric patients undergoing rTMS and ECT in order to refine the selection of patients and predict clinical outcomes. This study enrolled 25 drug-resistant depressive patients undergoing rTMS and 31 drug-resistant schizophrenia patients undergoing ECT. Clinical efficacy of brain stimulation therapies was gauged using MADRS and HAM-D scales in the depression group and PANSS scale in the schizophrenia group. Blood-derived BDNF, VEGF, and TNFα were analysed during the treatment course. For reference, 19 healthy control subjects were also enrolled. After statistical analysis, no significant differences were detected in BDNF, VEGF, and TNFα concentrations among healthy, depressive, and schizophrenic subject groups before the treatment. However, depressive patient treatment with rTMS has increased BDNF concentration, while schizophrenic patient treatment with ECT has lowered the concentration of TNFα. Our findings suggest that a lower initial TNFα concentration could be a marker for treatment success in depressed patients undergoing rTMS, whereas in schizophrenic patient group treated with ECT, a higher concentration of VEGF correlates to milder symptoms post-treatment, especially in the negative scale.

Disabling VEGF-Response of Purkinje Cells by Downregulation of KDR via miRNA-204-5p

The vascular endothelial growth factor (VEGF) is well known for its wide-ranging functions, not only in the vascular system, but also in the central (CNS) and peripheral nervous system (PNS). To study the role of VEGF in neuronal protection, growth and maturation processes have recently attracted much interest. These effects are mainly mediated by VEGF receptor 2 (VEGFR-2). Current studies have shown the age-dependent expression of VEGFR-2 in Purkinje cells (PC), promoting dendritogenesis in neonatal, but not in mature stages. We hypothesize that microRNAs (miRNA/miR) might be involved in the regulation of VEGFR-2 expression during the development of PC. In preliminary studies, we performed a miRNA profiling and identified miR204-5p as a potential regulator of VEGFR-2 expression. In the recent study, organotypic slice cultures of rat cerebella (postnatal day (p) 1 and 9) were cultivated and VEGFR-2 expression in PC was verified via immunohistochemistry. Additionally, PC at age p9 and p30 were isolated from cryosections by laser microdissection (LMD) to analyse VEGFR-2 expression by quantitative RT-PCR. To investigate the influence of miR204-5p on VEGFR-2 levels in PC, synthetic constructs including short hairpin (sh)-miR204-5p cassettes (miRNA-mimics), were microinjected into PC. The effects were analysed by confocal laser scanning microscopy (CLSM) and morphometric analysis. For the first time, we could show that miR204-5p has a negative effect on VEGF sensitivity in juvenile PC, resulting in a significant decrease of dendritic growth compared to untreated juvenile PC. In mature PC, the overexpression of miR204-5p leads to a shrinkage of dendrites despite VEGF treatment. The results of this study illustrate, for the first time, which miR204-5p expression has the potential to play a key role in cerebellar development by inhibiting VEGFR-2 expression in PC.

Neuronal guidance proteins in cardiovascular inflammation

Cardiovascular pathologies are often induced by inflammation. The associated changes in the inflammatory response influence vascular endothelial biology; they complicate the extent of ischaemia and reperfusion injury, direct the migration of immune competent cells and activate platelets. The initiation and progression of inflammation is regulated by the classical paradigm through the system of cytokines and chemokines. Therapeutic approaches have previously used this knowledge to control the extent of cardiovascular changes with varying degrees of success. Neuronal guidance proteins (NGPs) have emerged in recent years and have been shown to be significantly involved in the control of tissue inflammation and the mechanisms of immune cell activation. Therefore, proteins of this class might be used in the future as targets to control the extent of inflammation in the cardiovascular system. In this review, we describe the role of NGPs during cardiovascular inflammation and highlight potential therapeutic options that could be explored in the future.

Neuroprotective Effect of Vascular Endothelial Growth Factor on Motoneurons of the Oculomotor System

Vascular endothelial growth factor (VEGF) was initially characterized as a potent angiogenic factor based on its activity on the vascular system. However, it is now well established that VEGF also plays a crucial role as a neuroprotective factor in the nervous system. A deficit of VEGF has been related to motoneuronal degeneration, such as that occurring in amyotrophic lateral sclerosis (ALS). Strikingly, motoneurons of the oculomotor system show lesser vulnerability to neurodegeneration in ALS compared to other motoneurons. These motoneurons presented higher amounts of VEGF and its receptor Flk-1 than other brainstem pools. That higher VEGF level could be due to an enhanced retrograde input from their target muscles, but it can also be produced by the motoneurons themselves and act in an autocrine way. By contrast, VEGF’s paracrine supply from the vicinity cells, such as glial cells, seems to represent a minor source of VEGF for brainstem motoneurons. In addition, ocular motoneurons experiment an increase in VEGF and Flk-1 level in response to axotomy, not observed in facial or hypoglossal motoneurons. Therefore, in this review, we summarize the differences in VEGF availability that could contribute to the higher resistance of extraocular motoneurons to injury and neurodegenerative diseases.

The Role of Neurotrophic Factors in Pathophysiology of Major Depressive Disorder

According to the neurotrophic hypothesis of major depressive disorder (MDD), impairment in growth factor signaling might be associated with the pathology of this illness. Current evidence demonstrates that impaired neuroplasticity induced by alterations of neurotrophic growth factors and related signaling pathways may be underlying to the pathophysiology of MDD. Brain-derived neurotrophic factor (BDNF) is the most studied neurotrophic factor involved in the neurobiology of MDD. Nevertheless, developing evidence has implicated other neurotrophic factors, including neurotrophin-3 (NT-3), neurotrophin-4 (NT-4), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF), glial cell-derived neurotrophic factor (GDNF), and fibroblast growth factor (FGF) in the MDD pathophysiology. Here, we summarize the current literature on the involvement of neurotrophic factors and related signaling pathways in the pathophysiology of MDD.

Improved survival in amyotrophic lateral sclerosis patients following autologous bone marrow mononuclear cell therapy: a long term 10-year retrospective study

Background:

Promising results from previous studies using cell therapy have paved the way for an innovative treatment option for amyotrophic lateral sclerosis (ALS). There is considerable evidence of immune and inflammatory abnormalities in ALS. Bone marrow mononuclear cells (BMMNCs) possess immunomodulatory properties and could contribute to slowing of disease progression.

Objective:

Aim of our study was to evaluate the long-term effect of autologous BMMNCs combined with standard treatment on survival duration in a large population and to evaluate effect of type of onset and hormonal status on survival duration in the intervention group.

Methods:

This controlled, retrospective study spanned over 10 years, 5 months; included 216 patients with probable or definite ALS, 150 in intervention group receiving autologous BMMNCs and standard treatment, and 66 in control group receiving only standard treatment. The estimated survival duration of control group and intervention group was computed and compared using Kaplan Meier analysis. Survival duration of patients with different types of onset and hormonal status was compared within the intervention group.

Results:

None of the patients reported any major adverse events related to cell administration or the procedure. Kaplan Meier analysis estimated survival duration in the intervention group to be 91.7 months while 49.7 months in the control group (p = 0.008). Within the intervention group, estimated survival was significantly higher (p = 0.013) in patients with limb onset (102.3 months) vs. bulbar onset (49.9 months); premenopausal women (93.1 months) vs. postmenopausal women (57.6 months) (p = 0.002); and preandropausal men (153.7 months) vs. postandropausal males (56.5 months) (p = 0.006).

Conclusion:

Cell therapy using autologous BMMNCs along with standard treatment offers a promising and safe option for ALS with the potential of long term beneficial effect and increased survival. Limb onset patients, premenopausal women and men ≤ 40 years of age demonstrated better treatment efficacy.

The Emerging Role of SGK1 (Serum- and Glucocorticoid-Regulated Kinase 1) in Major Depressive Disorder: Hypothesis and Mechanisms

Major depressive disorder (MDD) is a heterogeneous psychiatric disease characterized by persistent low mood, diminished interests, and impaired cognitive and social functions. The multifactorial etiology of MDD is still largely unknown because of the complex genetic and environmental interactions involved. Therefore, no established mechanism can explain all the aspects of the disease. In this light, an extensive research about the pathophysiology of MDD has been carried out. Several pathogenic hypotheses, such as monoamines deficiency and neurobiological alterations in the stress-responsive system, including the hypothalamic-pituitary-adrenal (HPA) axis and the immune system, have been proposed for MDD. Over time, remarkable studies, mainly on preclinical rodent models, linked the serum- and glucocorticoid-regulated kinase 1 (SGK1) to the main features of MDD. SGK1 is a serine/threonine kinase belonging to the AGK Kinase family. SGK1 is ubiquitously expressed, which plays a pivotal role in the hormonal regulation of several ion channels, carriers, pumps, and transcription factors or regulators. SGK1 expression is modulated by cell stress and hormones, including gluco- and mineralocorticoids. Compelling evidence suggests that increased SGK1 expression or function is related to the pathogenic stress hypothesis of major depression. Therefore, the first part of the present review highlights the putative role of SGK1 as a critical mediator in the dysregulation of the HPA axis, observed under chronic stress conditions, and its controversial role in the neuroinflammation as well. The second part depicts the negative regulation exerted by SGK1 in the expression of both the brain-derived neurotrophic factor (BDNF) and the vascular endothelial growth factor (VEGF), resulting in an anti-neurogenic activity. Finally, the review focuses on the antidepressant-like effects of anti-oxidative nutraceuticals in several preclinical model of depression, resulting from the restoration of the physiological expression and/or activity of SGK1, which leads to an increase in neurogenesis. In summary, the purpose of this review is a systematic analysis of literature depicting SGK1 as molecular junction of the complex mechanisms underlying the MDD in an effort to suggest the kinase as a potential biomarker and strategic target in modern molecular antidepressant therapy.

VEGF is an autocrine/paracrine neuroprotective factor for injured retinal ganglion neurons

Vascular endothelial growth factor-A (VEGF) is the angiogenic factor promoting the pathological neovascularization in age-related macular degeneration (AMD) or diabetic macular edema (DME). Evidences have suggested a neurotrophic and neuroprotective role of VEGF, albeit in retina, cellular mechanisms underlying the VEGF neuroprotection remain elusive. Using purified adult retinal ganglion cells (RGCs) in culture, we demonstrated here that VEGF is released by RGCs themselves to promote their own survival, while VEGF neutralization by specific antibodies or traps drastically reduced the RGC survival. These results indicate an autocrine VEGF neuroprotection on RGCs. In parallel, VEGF produced by mixed retinal cells or by mesenchymal stem cells exerted a paracrine neuroprotection on RGCs. Such neuroprotective effect was obtained using the recombinant VEGF-B, suggesting the involvement of VEGF-R1 pathway in VEGF-elicited RGC survival. Finally, glaucomatous patients injected with VEGF traps (ranibizumab or aflibercept) due to either AMD or DME comorbidity, showed a significant reduction of RGC axon fiber layer thickness, consistent with the plausible reduction of the VEGF autocrine stimulation of RGCs. Our results provide evidence of the autocrine neuroprotective function of VEGF on RGCs is crucially involved to preserve injured RGCs such as in glaucomatous patients.

Trans-Axonal Signaling in Neural Circuit Wiring

The development of neural circuits is a complex process that relies on the proper navigation of axons through their environment to their appropriate targets. While axon–environment and axon–target interactions have long been known as essential for circuit formation, communication between axons themselves has only more recently emerged as another crucial mechanism. Trans-axonal signaling governs many axonal behaviors, including fasciculation for proper guidance to targets, defasciculation for pathfinding at important choice points, repulsion along and within tracts for pre-target sorting and target selection, repulsion at the target for precise synaptic connectivity, and potentially selective degeneration for circuit refinement. This review outlines the recent advances in identifying the molecular mechanisms of trans-axonal signaling and discusses the role of axon–axon interactions during the different steps of neural circuit formation.

Effects of photobiomodulation on annulus fibrosus cells derived from degenerative disc disease patients exposed to microvascular endothelial cells conditioned medium

Intervertebral disc (IVD) degeneration with chronic low back pain is associated with neo-vascularisation into the deeper IVD regions. During this process, endothelial cells (ECs), which are primarily responsible for angiogenesis, interact with the adjacent annulus fibrosus (AF) cells, which are the first line of defence against the invasion of vascular structures into deeper IVD regions. However, the accumulation of inflammatory and catabolic enzymes that results from this interaction promotes matrix degradation and an inflammatory response. Thus, regulating the production of these mediators and catabolic enzymes could ameliorate IVD degeneration. Photobiomodulation (PBM) therapy is a non-invasive stimulation known to have biologically beneficial effects on wound healing, tissue repair, and inflammation. Here, we examined the effects of PBM, administered at various wavelengths (645, 525, and 465 nm) and doses (16, 32, and 64 J/cm²), on EC-stimulated human AF cells. Our results show that PBM selectively inhibited the EC-mediated production of inflammatory mediators, catabolic enzymes, and neurotrophins by human AF cells in a dose- and wavelength-dependent manner. These results suggest that PBM could be a superior and advanced treatment strategy for IVD degeneration.

Central VEGF-A pathway plays a key role in the development of trigeminal neuropathic pain in rats

The study reported here investigated the role of the central vascular endothelial growth factor-A (VEGF-A) pathway in the development of trigeminal neuropathic pain following nerve injury. A Sprague-Dawley rat model of trigeminal neuropathic pain was produced using malpositioned dental implants. The left mandibular second molar was extracted under anesthesia and replaced with a miniature dental implant to induce injury to the inferior alveolar nerve. The inferior alveolar nerve injury produced a significant upregulation of astrocytic VEGF-A expression in the medullary dorsal horn. The nerve injury-induced mechanical allodynia was inhibited by an intracisternal infusion of VEGF-A₁₆₄ antibody. Although both VEGF-A Receptor 1 (VEGF-A R1; colocalized with the blood–brain barrier) and VEGF-A Receptor 2 (VEGF-A R2; colocalized with astrocytes) participated in the development of trigeminal neuropathic pain following nerve injury, only the intracisternal infusion of a VEGF-A R1 antibody, and not that of a VEGF-A R2 antibody, inhibited the increased blood–brain barrier permeability produced by nerve injury. Finally, we confirmed the participation of the central VEGF-A pathway in the development of trigeminal neuropathic pain by reducing VEGF-A expression using VEGF-A₁₆₄ siRNA. This suppression of VEGF-A produced significant prolonged anti-allodynic effects. These results suggest that the central VEGF-A pathway plays a key role in the development of trigeminal neuropathic pain following nerve injury through two separate pathways: VEGF-A R1 and VEGF-A R2. Hence, a blockade of the central VEGF-A pathway provides a new therapeutic avenue for the treatment of trigeminal neuropathic pain.

APOE ε4-specific associations of VEGF gene family expression with cognitive aging and Alzheimer's disease

Literature suggests vascular endothelial growth factor A (VEGFA) is protective among those at highest risk for Alzheimer's disease (AD). Apolipoprotein E (APOE) ε4 allele carriers represent a highly susceptible population for cognitive decline, and VEGF may confer distinct protection among APOE-ε4 carriers. We evaluated interactions between cortical expression of 10 VEGF gene family members and APOE-ε4 genotype to clarify which VEGF genes modify the association between APOE-ε4 and cognitive decline. Data were obtained from the Religious Orders Study and Rush Memory and Aging Project (N = 531). Linear regression assessed interactions on global cognition. VEGF genes NRP1 and VEGFA interacted with APOE-ε4 on cognitive performance (p.fdr < 0.05). Higher NRP1 expression correlated with worse outcomes among ε4 carriers but better outcomes among ε4 noncarriers, suggesting NRP1 modifies the risk for poor cognitive scores based on APOE-ε4 status. NRP1 regulates angiogenesis, and literature suggests vessels in APOE-ε4 brains are more prone to leaking, perhaps placing young vessels at risk for ischemia. Results suggest that future therapeutics targeting brain angiogenesis should also consider ε4 allele status.

Upregulation of VEGF-A and correlation between VEGF-A and FLT-1 expressions in Iranian multiple sclerosis patients

Multiple sclerosis (MS) is among the most common diseases affecting brain and spinal cord. MS progression is characterized by breakdown of blood brain barrier which leads to increased vascular permeability and angiogenesis. Consequently, vascular endothelial growth factor A (VEGF) and its receptors are considered to be important components of MS progression. VEGFA and fms-related tyrosine kinase 1 (FLT1) play important roles in various aspects of MS. In this study, we investigated the relationship between these genes and MS. For this purpose, the expression levels of VEGFA and FLT1 were measured in the blood of 50 relapsing-remitting MS (RR-MS) patients and 50 healthy individuals using TaqMan quantitative real-time PCR. A significant upregulation of VEGFA expression was observed among MS patients compared with controls (p = 0.04). However, the difference in FLT1 gene expression between study groups was insignificant (p = 0.947). In addition, there was a significant positive correlation between VEGFA and FLT1 genes expressions (r = 0.769, p < 0.0001). In spite of the highly complex molecular mechanisms behind this, the findings imply participation of VEGFA in the pathogenesis of MS.

VEGFD Protects Retinal Ganglion Cells and, consequently, Capillaries against Excitotoxic Injury

In the central nervous system, neurons and the vasculature influence each other. While it is well described that a functional vascular system is trophic to neurons and that vascular damage contributes to neurodegeneration, the opposite scenario in which neural damage might impact the microvasculature is less defined. In this study, using an in vivo excitotoxic approach in adult mice as a tool to cause specific damage to retinal ganglion cells, we detected subsequent damage to endothelial cells in retinal capillaries. Furthermore, we detected decreased expression of vascular endothelial growth factor D (VEGFD) in retinal ganglion cells. In vivo VEGFD supplementation via neuronal-specific viral-mediated expression or acute intravitreal delivery of the mature protein preserved the structural and functional integrity of retinal ganglion cells against excitotoxicity and, additionally, spared endothelial cells from degeneration. Viral-mediated suppression of expression of the VEGFD-binding receptor VEGFR3 in retinal ganglion cells revealed that VEGFD exerts its protective capacity directly on retinal ganglion cells, while protection of endothelial cells is the result of upheld neuronal integrity. These findings suggest that VEGFD supplementation might be a novel, clinically applicable approach for neuronal and vascular protection.

VEGF/VEGFR2 signaling regulates hippocampal axon branching during development

Axon branching is crucial for proper formation of neuronal networks. Although originally identified as an angiogenic factor, VEGF also signals directly to neurons to regulate their development and function. Here we show that VEGF and its receptor VEGFR2 (also known as KDR or FLK1) are expressed in mouse hippocampal neurons during development, with VEGFR2 locally expressed in the CA3 region. Activation of VEGF/VEGFR2 signaling in isolated hippocampal neurons results in increased axon branching. Remarkably, inactivation of VEGFR2 also results in increased axon branching in vitro and in vivo. The increased CA3 axon branching is not productive as these axons are less mature and form less functional synapses with CA1 neurons. Mechanistically, while VEGF promotes the growth of formed branches without affecting filopodia formation, loss of VEGFR2 increases the number of filopodia and enhances the growth rate of new branches. Thus, a controlled VEGF/VEGFR2 signaling is required for proper CA3 hippocampal axon branching during mouse hippocampus development.

Isolation of microglia-derived extracellular vesicles: towards miRNA signatures and neuroprotection

The functional preservation of the central nervous system (CNS) is based on the neuronal plasticity and survival. In this context, the neuroinflammatory state plays a key role and involves the microglial cells, the CNS-resident macrophages. In order to better understand the microglial contribution to the neuroprotection, microglia-derived extracellular vesicles (EVs) were isolated and molecularly characterized to be then studied in neurite outgrowth assays. The EVs, mainly composed of exosomes and microparticles, are an important cell-to-cell communication process as they exhibit different types of mediators (proteins, lipids, nucleic acids) to recipient cells. The medicinal leech CNS was initially used as an interesting model of microglia/neuron crosstalk due to their easy collection for primary cultures. After the microglia-derived EV isolation following successive methods, we developed their large-scale and non-targeted proteomic analysis to (i) detect as many EV protein markers as possible, (ii) better understand the biologically active proteins in EVs and (iii) evaluate the resulting protein signatures in EV-activated neurons. The EV functional properties were also evaluated in neurite outgrowth assays on rat primary neurons and the RNAseq analysis of the microglia-derived EVs was performed to propose the most representative miRNAs in microglia-derived EVs. This strategy allowed validating the EV isolation, identify major biological pathways in EVs and corroborate the regenerative process in EV-activated neurons. In parallel, six different miRNAs were originally identified in microglia-derived EVs including 3 which were only known in plants until now. The analysis of the neuronal proteins under the microglial EV activation suggested possible miRNA-dependent regulation mechanisms. Taken together, this combination of methodologies showed the leech microglial EVs as neuroprotective cargos across species and contributed to propose original EV-associated miRNAs whose functions will have to be evaluated in the EV-dependent dialog between microglia and neurons.

Vascular Endothelial Growth Factor and Cutaneous Scarring

Significance: The proangiogenic mediator vascular endothelial growth factor (VEGF) plays an important role in cutaneous wound repair. Most of the work on VEGF and wound healing has focused on its role in mediating angiogenesis and how this affects wound closure rates. Less is known about how VEGF affects other phases of wound healing, including scar formation. Recent Advances: Over the last 10 years, mounting evidence suggests that VEGF plays an important role in regulating scar tissue production. Multiple studies have linked high VEGF levels with scar formation in normal, hypertrophic, and keloid scars. In addition, there is experimental evidence that VEGF inhibition can reduce scar tissue deposition. Critical Issues: While there is evidence that VEGF can promote scar formation in the skin, there are several unanswered questions that remain. First, the mechanisms by which VEGF promotes scar formation have not been completely characterized. While both indirect and direct mechanisms could be involved, clear evidence for a specific mechanism is lacking. In addition, despite the availability of anti-VEGF drugs, the potential value in targeting VEGF to attenuate scar formation clinically is not yet known. Future Directions: While there are a significant number of studies examining the effects of VEGF on angiogenesis and wound closure, much less attention has been paid to the contribution of VEGF to scar tissue production. Additional studies are required to learn more about how VEGF regulates scar formation and whether VEGF inhibition could be used clinically to manage scars.

Screening and novel therapies for retinopathy of prematurity - A review

With current screening for sight threatening retinopathy of prematurity (ROP) <10% of screened infants need treatment. Prediction models based on birth characteristics, postnatal weight gain and other factors have been developed to reduce examinations in low-risk infants. A model based on advanced statistics using data from >7000 infants registered in the Swedish ROP registry is being developed. Based on birth characteristics only, it appears to predict total risk of ROP-treatment as well as models including weight measurements. Treatment risk peaked at 12 weeks of age. Laser therapy is the method of choice for severe ROP. Anti-VEGF therapies are implemented worldwide despite insufficient knowledge of choice of drug, dosage and long term systemic effects. Prevention of ROP may be achieved through oxygen control and provision of the mother's breastmilk. Other interventions such as supplementation with long chain polyunsaturated fatty acids and preservation of fetal haemoglobin are investigated.

The two faces of titanium dioxide nanoparticles bio-camouflage in 3D bone spheroids

Titanium (Ti) and its alloys are widely used in dental implants and hip-prostheses due to their excellent biocompatibility. Growing evidence support that surface degradation due to corrosion and wear processes, contribute to implant failure, since the release of metallic ions and wear particles generate local tissue reactions (peri-implant inflammatory reactions). The generated ions and wear debris (particles at the micron and nanoscale) stay, in a first moment, at the interface implant-bone. However, depending on their size, they can enter blood circulation possibly contributing to systemic reactions and toxicities. Most of the nanotoxicological studies with titanium dioxide nanoparticles (TiO2 NPs) use conventional two-dimensional cell culture monolayers to explore macrophage and monocyte activation, where limited information regarding bone cells is available. Recently three-dimensional models have been gaining prominence since they present a greater anatomical and physiological relevance. Taking this into consideration, in this work we developed a human osteoblast-like spheroid model, which closely mimics bone cell-cell interactions, providing a more realistic scenario for nanotoxicological studies. The treatment of spheroids with different concentrations of TiO2 NPs during 72 h did not change their viability significantly. Though, higher concentrations of TiO2 NPs influenced osteoblast cell cycle without interfering in their ability to differentiate and mineralize. For higher concentration of TiO2 NPs, collagen deposition and pro-inflammatory cytokine, chemokine and growth factor secretion (involved in osteolysis and bone homeostasis) increased. These results raise the possible use of this model in nanotoxicological studies of osseointegrated devices and demonstrate a possible therapeutic potential of this TiO2 NPs to prevent or reverse bone resorption.

Blood-brain barrier dysfunction underlying Alzheimer's disease is induced by an SSAO/VAP-1-dependent cerebrovascular activation with enhanced Aβ deposition

Dysfunctions of the vascular system directly contribute to the onset and progression of Alzheimer's disease (AD). The blood-brain barrier (BBB) shows signs of malfunction at early stages of the disease. When Abeta peptide (Aβ) is deposited on brain vessels, it induces vascular degeneration by producing reactive oxygen species and promoting inflammation. These molecular processes are also related to an excessive SSAO/VAP-1 (semicarbazide-sensitive amine oxidase) enzymatic activity, observed in plasma and in cerebrovascular tissue of AD patients. We studied the contribution of vascular SSAO/VAP-1 to the BBB dysfunction in AD using in vitro BBB models. Our results show that SSAO/VAP-1 expression is associated to endothelial activation by altering the release of pro-inflammatory and pro-angiogenic angioneurins, most highly IL-6, IL-8 and VEGF. It is also related to a BBB structure alteration, with a decrease in tight-junction proteins such as zona occludens or claudin-5. Moreover, the BBB function reveals increased permeability and leukocyte adhesion in cells expressing SSAO/VAP-1, as well as an enhancement of the vascular Aβ deposition induced by mechanisms both dependent and independent of the enzymatic activity of SSAO/VAP-1. These results reveal an interesting role of vascular SSAO/VAP-1 in BBB dysfunction related to AD progression, opening a new window in the search of alternative therapeutic targets for fighting AD.

Angioneurins - Key regulators of blood-brain barrier integrity during hypoxic and ischemic brain injury

The loss of blood-brain barrier (BBB) integrity leading to vasogenic edema and brain swelling is a common feature of hypoxic/ischemic brain diseases such as stroke, but is also central to the etiology of other CNS disorders. In the past decades, numerous proteins, belonging to the family of angioneurins, have gained increasing attention as potential therapeutic targets for ischemic stroke, but also other CNS diseases attributed to BBB dysfunction. Angioneurins encompass mediators that affect both neuronal and vascular function. Recently, increasing evidence has been accumulated that certain angioneurins critically determine disease progression and outcome in stroke among others through multifaceted effects on the compromised BBB. Here, we will give a concise overview about the family of angioneurins. We further describe the most important cellular and molecular components that contribute to structural integrity and low permeability of the BBB under steady-state conditions. We then discuss BBB alterations in ischemic stroke, and highlight underlying cellular and molecular mechanisms. For the most prominent angioneurin family members including vascular endothelial growth factors, angiopoietins, platelet-derived growth factors and erythropoietin, we will summarize current scientific literature from experimental studies in animal models, and if available from clinical trials, on the following points: (i) spatiotemporal expression of these factors in the healthy and hypoxic/ischemic CNS, (ii) impact of loss- or gain-of-function during cerebral hypoxia/ischemia for BBB integrity and beyond, and (iii) potential underlying molecular mechanisms. Moreover, we will highlight novel therapeutic strategies based on the activation of endogenous angioneurins that might improve BBB dysfuntion during ischemic stroke.