Nerve growth factor improves visual loss in childhood optic gliomas: a randomized, double-blind, phase II clinical trial

An Overview of Optic Pathway Glioma With Neurofibromatosis Type 1: Pathogenesis, Risk Factors, and Therapeutic Strategies

Optic pathway gliomas (OPGs) are most predominant pilocytic astrocytomas, which are typically diagnosed within the first decade of life. The majority of affected children with OPGs also present with neurofibromatosis type 1 (NF1), the most common tumor predisposition syndrome. OPGs in individuals with NF1 primarily affect the optic pathway and lead to visual disturbance. However, it is challenging to assess risk in asymptomatic patients without valid biomarkers. On the other hand, for symptomatic patients, there is still no effective treatment to prevent or recover vision loss. Therefore, this review summarizes current knowledge regarding the pathogenesis of NF1-associated OPGs (NF1-OPGs) from preclinical studies to seek potential prognostic markers and therapeutic targets. First, the loss of the NF1 gene activates 3 distinct Ras effector pathways, including the PI3K/AKT/mTOR pathway, the MEK/ERK pathway, and the cAMP pathway, which mediate glioma tumorigenesis. Meanwhile, non-neoplastic cells from the tumor microenvironment (microglia, T cells, neurons, etc.) also contribute to gliomagenesis via various soluble factors. Subsequently, we investigated potential genetic risk factors, molecularly targeted therapies, and neuroprotective strategies for tumor prevention and vision recovery. Last, potential directions and promising preclinical models of NF1-OPGs are presented for further research. On the whole, NF1-OPGs develop as a result of the interaction between glioma cells and the tumor microenvironment. Developing effective treatments require a better understanding of tumor molecular characteristics, as well as multistage interventions targeting both neoplastic cells and non-neoplastic cells.

Visual Deficits and Diagnostic and Therapeutic Strategies for Neurofibromatosis Type 1: Bridging Science and Patient-Centered Care

Neurofibromatosis type 1 (NF1) is an inherited autosomal dominant disorder primarily affecting children and adolescents characterized by multisystemic clinical manifestations. Mutations in neurofibromin, the protein encoded by the Nf1 tumor suppressor gene, result in dysregulation of the RAS/MAPK pathway leading to uncontrolled cell growth and migration. Neurofibromin is highly expressed in several cell lineages including melanocytes, glial cells, neurons, and Schwann cells. Individuals with NF1 possess a genetic predisposition to central nervous system neoplasms, particularly gliomas affecting the visual pathway, known as optic pathway gliomas (OPGs). While OPGs are typically asymptomatic and benign, they can induce visual impairment in some patients. This review provides insight into the spectrum and visual outcomes of NF1, current diagnostic techniques and therapeutic interventions, and explores the influence of NF1-OPGS on visual abnormalities. We focus on recent advancements in preclinical animal models to elucidate the underlying mechanisms of NF1 pathology and therapies targeting NF1-OPGs. Overall, our review highlights the involvement of retinal ganglion cell dysfunction and degeneration in NF1 disease, and the need for further research to transform scientific laboratory discoveries to improved patient outcomes.

Recombinant protein delivery enables modulation of the phototransduction cascade in mouse retina

Inherited retinal dystrophies are often associated with mutations in the genes involved in the phototransduction cascade in photoreceptors, a paradigmatic signaling pathway mediated by G protein-coupled receptors. Photoreceptor viability is strictly dependent on the levels of the second messengers cGMP and Ca2+. Here we explored the possibility of modulating the phototransduction cascade in mouse rods using direct or liposome-mediated administration of a recombinant protein crucial for regulating the interplay of the second messengers in photoreceptor outer segments. The effects of administration of the free and liposome-encapsulated human guanylate cyclase-activating protein 1 (GCAP1) were compared in biological systems of increasing complexity (in cyto, ex vivo, and in vivo). The analysis of protein biodistribution and the direct measurement of functional alteration in rod photoresponses show that the exogenous GCAP1 protein is fully incorporated into the mouse retina and photoreceptor outer segments. Furthermore, only in the presence of a point mutation associated with cone-rod dystrophy in humans p.(E111V), protein delivery induces a disease-like electrophysiological phenotype, consistent with constitutive activation of the retinal guanylate cyclase. Our study demonstrates that both direct and liposome-mediated protein delivery are powerful complementary tools for targeting signaling cascades in neuronal cells, which could be particularly important for the treatment of autosomal dominant genetic diseases.

A Vicious NGF-p75NTR Positive Feedback Loop Exacerbates the Toxic Effects of Oxidative Damage in the Human Retinal Epithelial Cell Line ARPE-19

In spite of its variety of biological activities, the clinical exploitation of human NGF (hNGF) is currently limited to ocular pathologies. It is therefore interesting to test the effects of hNGF in preclinical models that may predict their efficacy and safety in the clinical setting of ocular disorders and compare the effects of hNGF with those of its analogs. We used a human retinal pigment cell line, ARPE-19 cells, to investigate the effects of hNGF and its analogs, mouse NGF (mNGF) and painless NGF (pNGF), on cell viability under basal conditions and after exposure to oxidative stimuli, i.e., hydrogen peroxide (H2O2) and ultraviolet (UV)-A rays. The effects of hNGF and pNGF were also tested on the gene expression and protein synthesis of the two NGF receptor subtypes, p75 neurotrophic receptors (p75NTR) and tyrosine kinase A (TrkA) receptors. We drew the following conclusions: (i) the exposure of ARPE-19 cells to H2O2 or UV-A causes a dose-dependent decrease in the number of viable cells; (ii) under baseline conditions, hNGF, but not pNGF, causes a concentration-dependent decrease in cell viability in the range of doses 1-100 ng/mL; (iii) hNGF, but not pNGF, significantly potentiates the toxic effects of H2O2 or of UV-A on ARPE-19 cells in the range of doses 1-100 ng/mL, while mNGF at the same doses presents an intermediate behavior; (iv) 100 ng/mL of hNGF triggers an increase in p75NTR expression in H2O2-treated ARPE-19 cells, while pNGF at the same dose does not; (v) pNGF, but not hNGF (both given at 100 ng/mL), increases the total cell fluorescence intensity for TrkA receptors in H2O2-treated ARPE-19 cells. The present findings suggest a vicious positive feedback loop through which NGF-mediated upregulation of p75NTR contributes to worsening the toxic effects of oxidative damage in the human retinal epithelial cell line ARPE-19. Looking at the possible clinical relevance of these findings, one can postulate that pNGF might show a better benefit/risk ratio than hNGF in the treatment of ocular disorders.

Nerve Growth Factor, Antimicrobial Peptides and Chemotherapy: Glioblastoma Combination Therapy to Improve Their Efficacy

Glioblastoma (GBM) is an aggressive and lethal malignancy of the central nervous system with a median survival rate of 15 months. We investigated the combined anticancer effects of nerve growth factor (NGF), cathelicidin (LL-37), and protegrin-1 (PG-1) with chemotherapy (temozolomide, doxorubicin, carboplatin, cisplatin, and etoposide) in the glioblastoma U251 cell line to overcome the limitations of conventional chemotherapy and to guarantee specific treatments to succeed. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used to study cell viability and to determine the cytotoxic effects of NGF, LL-37, and PG-1 and their combination with chemotherapy in U251 cells. Synergism or antagonism was determined using the combination index (CI) method. Caspase-3 activity was evaluated spectrophotometrically using a caspase-3 activity assay kit. Apoptosis was analyzed with flow cytometry using propidium iodide (PI) and YO-PRO-1. NGF and the peptides showed a strong cytotoxic effect on U251 glioma cells in the MTT test (IC50 0.0214, 3.1, and 26.1 μM, respectively) compared to chemotherapy. The combination of PG-1 + etoposide had a synergistic effect on apoptosis of U251 glioma cells. It should be noted that the cells were in the early and late stages of apoptosis, respectively, compared with the control cells. The caspase-3 activation analysis revealed that the caspase-3 level was not significantly (p > 0.05) increased in U251 cells following PG-1 with etoposide treatment compared with that in the untreated cells, suggesting that the combination of PG-1 and etoposide may induce caspase-independent apoptosis in U251 cells. NGF, LL-37, and PG-1 represent promising drug candidates as the treatment regimen for GBM. Furthermore, the synergistic efficacy of the combined protocol using PG-1 and etoposide may overcome some of the typical limitations of the conventional therapeutic protocols, thus representing a promising approach for GBM therapy.

Neurofibromatosis Type 1-Associated Optic Pathway Gliomas: Current Challenges and Future Prospects

Optic pathway glioma (OPG) occurs in as many as one-fifth of individuals with the neurofibromatosis type 1 (NF1) cancer predisposition syndrome. Generally considered low-grade and slow growing, many children with NF1-OPGs remain asymptomatic. However, due to their location within the optic pathway, ~20-30% of those harboring NF1-OPGs will experience symptoms, including progressive vision loss, proptosis, diplopia, and precocious puberty. While treatment with conventional chemotherapy is largely effective at attenuating tumor growth, it is not clear whether there is much long-term recovery of visual function. Additionally, because these tumors predominantly affect young children, there are unique challenges to NF1-OPG diagnosis, monitoring, and longitudinal management. Over the past two decades, the employment of authenticated genetically engineered Nf1-OPG mouse models have provided key insights into the function of the NF1 protein, neurofibromin, as well as the molecular and cellular pathways that contribute to optic gliomagenesis. Findings from these studies have resulted in the identification of new molecular targets whose inhibition blocks murine Nf1-OPG growth in preclinical studies. Some of these promising compounds have now entered into early clinical trials. Future research focused on defining the determinants that underlie optic glioma initiation, expansion, and tumor-induced optic nerve injury will pave the way to personalized risk assessment strategies, improved tumor monitoring, and optimized treatment plans for children with NF1-OPG.

Optic Pathway Gliomas: The Trends of Basic Research to Reduce the Impact of the Disease on Visual Function

Pediatric optic pathway gliomas (OPG) are low-grade brain tumors characterized by slow progression and invalidating visual loss. Common therapeutic strategies include surgery, radiotherapy, chemotherapy, and combinations of these modalities, but despite the different treatment strategies, no actual treatment exists to prevent or revert visual impairment. Nowadays, several reports of the literature show promising results regarding NGF eye drop instillation and improvement of visual outcome. Such results seem to be related with the NGF-linked prevention in caspase activation, which reduces retinal ganglion cell loss.Reducing retinal ganglion cell loss results clinically in visual field improvement as well as visual electric potential and optical coherence tomography gain. Nonetheless, visual acuity fails to show significant changes.Visual impairment represents nowadays one of the major issues in dealing with OPGs. Secondary to the interesting results offered by NGF eye drop administration, further studies are warranted to better comprehend potential treatment strategies.

Pediatric low-grade glioma and neurofibromatosis type 1: A single-institution experience

Background

Neurofibromatosis type 1 (NF1)-related gliomas appear to have a clinical behavior different from that of sporadic cases. The purpose of the study was to investigate the role of different factors in influencing the tumor response rate of children receiving chemotherapy for their symptomatic glioma.

Methods

Between 1995 and 2015, 60 patients with low-grade glioma (42 sporadic cases and 18 cases with NF1) were treated. Patients with brainstem gliomas were excluded. Thirty-nine patients underwent exclusive or postsurgical chemotherapy (vincristine/carboplatin-based regimen).

Results

Disease reduction was achieved in 12 of the 28 patients (42.8%) with sporadic low-grade glioma and in 9 of the 11 patients (81.8%) with NF1, with a significant difference between the 2 groups (P < 0.05). The response to chemotherapy in both the patient groups was not significantly influenced by sex, age, tumor site, and histopathology, although disease reduction occurred more frequently in children aged under 3 years.

Conclusions

Our study showed that pediatric patients with low-grade glioma and NF1 are more likely to respond to chemotherapy than those with non-NF1.

A new era for optic pathway glioma: A developmental brain tumor with life-long health consequences

Optic pathway and hypothalamic glioma (OPHG) are low-grade brain tumors that arise from any part of the visual pathways frequently involving the hypothalamus. The tumors grow slowly and present with features driven by their precise anatomical site, their age at presentation and the stage of growth and development of the host neural and orbital bony tissues. Up to 50% of optic pathway glioma arise in association with Neurofibromatosis type 1 (NF1), which affects 1 in 3,000 births and is a cancer predisposition syndrome. As low-grade tumors, they almost never transform to malignant glioma yet they can threaten life when they present under two years of age. The main risks are to threaten vision loss by progressive tumor damage to optic pathways; furthermore, invasion of the hypothalamus can lead to diencephalic syndrome in infancy and hypopituitarism later in life. Progressive cognitive and behavioural dysfunction can occur, as part of NF1 syndromic features and in sporadic cases where large bulky tumors compress adjacent structures and disrupt neuro-hypothalamic pathways. Persistently progressive tumors require repeated treatments to attempt to control vision loss, other focal brain injury or endocrine dysfunction. In contrast tumors presenting later in childhood can be seen to spontaneously arrest in growth and subsequently progress after periods of stability. These patterns are influenced by NF status as well as stages of growth and development of host tissues. The past two decades has seen an expansion in our understanding and knowledge of the clinical and scientific features of these tumors, their modes of presentation, the need for careful visual and endocrine assessment. This influences the decision-making surrounding clinical management with surgery, radiotherapy, chemotherapy and most recently, the potential benefit of molecularly targeted drug therapy. This article, based upon the authors' clinical and research experience and the published literature will highlight advances in approach to diagnosis, the established role of vision loss as justification of treatments and the emerging evidence of endocrine and neurological consequences that need to be incorporated into judgements for case selection for therapy or observation. Consideration is given to the current state of biological evidence justifying current trials of new therapies, the genetic studies of the NF1 gene and the potential for new approaches to OPHG detection and treatment. The outstanding health system priorities from the perspective of children, their parents and health system commissioners or insurers are discussed.

Intravitreal Fluocinolone Acetonide for Diabetic Macular Edema: Long-Term Effect and Structure/Function Correlation

The long-term effect of intravitreal Fluocinolone acetonide (FAc) on retinal morphology and function in diabetic macular edema (DME) was investigated. Seventeen eyes of twelve consecutive DME patients, treated by intravitreal FAc, were retrospectively evaluated. Retinal morphology was assessed with central macular thickness (CMT). Retinal function was assessed by best-corrected visual acuity (BCVA) and cone b-wave and photopic negative response (PhNR). The main outcome was a mean change in CMT at month 24. The secondary outcomes were changes in cone b-wave and PhNR at month 24. The incidence of adverse events was also recorded. Mean CMT decreased from 406.52 µm (±138.74) at baseline to 310 µm (±130.39) at 24 months (p = 0.008). No significant changes in the other parameters were found. At baseline, BCVA and PhNR amplitude were negatively correlated (r = −0.55) with CMT. At the end of follow-up, the change in CMT was negatively correlated with baseline CMT (r = −0.53, p = 0.03) and positively correlated with baseline PhNR amplitude (r = 0.58, p < 0.01). A significant, long-term reduction in CMT was observed in DME patients after FAc implant. The anti-edema effect tended to be stronger in patients with the poorest baseline retinal morphology (CMT) and function (PhNR). Structure/function correlations might help to characterize the patients who may benefit from this treatment.

Management of Optic Pathway Glioma: A Systematic Review and Meta-Analysis

Background: OPG accounts for 3−5% of childhood central nervous system (CNS) tumors and about 2% of pediatric glial lesions. Methods: Article selection was performed by searching PubMed, Web of Science, and Cochrane databases. Results: The pooled mortality rate was 0.12 (95%CI 0.09−0.14). Due to the unrepresentative data, improved and not changed outcomes were classified as favorable outcomes and worsened as unfavorable. Meta-analyses were performed to determine the rate of clinical and radiological favorable outcomes. In terms of visual assessment, the pooled rate of a favorable outcome in chemotherapy, radiotherapy, and surgery was 0.74, 0.81, and 0.65, respectively, and the overall pooled rate of the favorable outcome was 0.75 (95%CI 0.70−0.80). In terms of radiological assessment, the rate of a favorable outcome following chemotherapy, radiotherapy, and surgery was 0.71, 0.74, and 0.67, respectively, and the overall pooled rate of the favorable outcome is 0.71 (95%CI 0.65−0.77). The subgroup analysis revealed no significant difference in the rate of clinical and radiological favorable outcomes between the different treatment modalities (p > 0.05). Conclusion: Our analyses showed that each therapeutic modality represents viable treatment options to achieve remission for these patients.

The effects of CHF6467, a new mutated form of NGF, on cell models of human glioblastoma. A comparison with wild-type NGF

CHF6467 is a mutated form of human recombinant nerve growth factor (NGF). The mutation selectively disrupts the binding of NGF to its p75NTR receptor while maintaining the affinity toward TrkA receptor. Because of such different profile of receptor interaction, CHF6467 maintains unaltered the neurotrophic and neuroprotective properties of wild-type NGF but shows reduced algogenic activity.In this study, we investigated the effects of CHF6467 on mortality, proliferation, cell-damage and migration in three human glioblastoma cell lines (U87MG, T98G, LN18), and in the rat astrocytoma C6 cells. Both CHF6467 and wild-type NGF, given in the range 1-50 ng/ml, did not modify cell proliferation, metabolism and migration, as well as the number of live/dead cells.The present in vitro data are predictive of a lack of tumorigenic activity by both wild-type NGF and CHF6467 on these cell types in vivo, and warrant for CHF6467 further clinical development.

Old Stars and New Players in the Brain Tumor Microenvironment

In recent years, the direct interaction between cancer cells and tumor microenvironment (TME) has emerged as a crucial regulator of tumor growth and a promising therapeutic target. The TME, including the surrounding peritumoral regions, is dynamically modified during tumor progression and in response to therapies. However, the mechanisms regulating the crosstalk between malignant and non-malignant cells are still poorly understood, especially in the case of glioma, an aggressive form of brain tumor. The presence of unique brain-resident cell types, namely neurons and glial cells, and an exceptionally immunosuppressive microenvironment pose additional important challenges to the development of effective treatments targeting the TME. In this review, we provide an overview on the direct and indirect interplay between glioma and neuronal and glial cells, introducing new players and mechanisms that still deserve further investigation. We will focus on the effects of neural activity and glial response in controlling glioma cell behavior and discuss the potential of exploiting these cellular interactions to develop new therapeutic approaches with the aim to preserve proper brain functionality.

Nerve Growth Factor-Based Therapy in Alzheimer's Disease and Age-Related Macular Degeneration

Alzheimer’s disease (AD) is an age-associated neurodegenerative disease which is the most common cause of dementia among the elderly. Imbalance in nerve growth factor (NGF) signaling, metabolism, and/or defect in NGF transport to the basal forebrain cholinergic neurons occurs in patients affected with AD. According to the cholinergic hypothesis, an early and progressive synaptic and neuronal loss in a vulnerable population of basal forebrain involved in memory and learning processes leads to degeneration of cortical and hippocampal projections followed by cognitive impairment with accumulation of misfolded/aggregated Aβ and tau protein. The neuroprotective and regenerative effects of NGF on cholinergic neurons have been largely demonstrated, both in animal models of AD and in living patients. However, the development of this neurotrophin as a disease-modifying therapy in humans is challenged by both delivery limitations (inability to cross the blood–brain barrier (BBB), poor pharmacokinetic profile) and unwanted side effects (pain and weight loss). Age-related macular degeneration (AMD) is a retinal disease which represents the major cause of blindness in developed countries and shares several clinical and pathological features with AD, including alterations in NGF transduction pathways. Interestingly, nerve fiber layer thinning, degeneration of retinal ganglion cells and changes of vascular parameters, aggregation of Aβ and tau protein, and apoptosis also occur in the retina of both AD and AMD. A protective effect of ocular administration of NGF on both photoreceptor and retinal ganglion cell degeneration has been recently described. Besides, the current knowledge about the detection of essential trace metals associated with AD and AMD and their changes depending on the severity of diseases, either systemic or locally detected, further pave the way for a promising diagnostic approach. This review is aimed at describing the employment of NGF as a common therapeutic approach to AMD and AD and the diagnostic power of detection of essential trace metals associated with both diseases. The multiple approaches employed to allow a sustained release/targeting of NGF to the brain and its neurosensorial ocular extensions will be also discussed, highlighting innovative technologies and future translational prospects.

Retinal Morpho-Functional Changes Following 0.19 mg Fluocinolone Acetonide Intravitreal Implant for Chronic Diabetic Macular Edema

Purpose

To evaluate morpho-functional outcomes of the intravitreal fluocinolone acetonide (FAc) implant.

Methods

Retrospective, observational, single-center study. Primary endpoint was the mean change in central macular thickness (CMT) from baseline to month 1–3. Secondary endpoints included mean CMT change from baseline to month 4–8 and 9–14 and mean best corrected visual acuity (BCVA), photopic negative response (PhNR) and b-wave of flash full-field electroretinogram (ERG) changes from baseline to month 1–3, 4–8, and 9–14.

Results

Fourteen patients (18 eyes) were included. Mean (standard deviation) CMT decreased from 473 (196) µm at baseline to 371 (163) µm at month 1–3 (mean difference − 102.3 ± 98.35 µm, 95% CI ± 46.4 µm; p < 0.0001) and this decrease tended to endure up to month 9–14. BCVA did not change significantly. There was an improvement in mean PhNR amplitude from 2.76 (1.65) µV at baseline to 3.73 (2.32) µV at month 1–3 (mean difference 0.91 (1.14) µV, 95% CI ± 0.54 µV, p = 0.003); b-wave amplitude improved from 8.83 (4.52) µV at baseline versus 10.05 (5.04) µV at month 1–3 (mean difference 1.22 (2.23) µV, 95% CI ± 1.08 µV, p = 0.0384). These ERG positive changes tended to endure up to month 9–14, although they did not reach statistical significance after month 3.

Conclusions

Intravitreal FAc implant significantly improved anatomic as well as functional outcomes related to middle and inner retinal layers, known to be altered in diabetic retinopathy. Our findings support the hypothesis that intravitreal FAc implant may exert a protective effect in diabetic retinas with diabetic macular edema.

hTERT Transduction Extends the Lifespan of Primary Pediatric Low-Grade Glioma Cells While Preserving the Biological Response to NGF

The neurotrophin nerve growth factor (NGF) modulates the growth of human gliomas and is able to induce cell differentiation through the engagement of tropomyosin receptor kinase A (TrkA) receptor, although the role played in controlling glioma survival has proved controversial. Unfortunately, the slow growth rate of low-grade gliomas (LGG) has made it difficult to investigate NGF effects on these tumors in preclinical models. In fact, patient-derived low-grade human astrocytoma cells duplicate only a limited number of times in culture before undergoing senescence. Nevertheless, replicative senescence can be counteracted by overexpression of hTERT, the catalytic subunit of telomerase, which potentially increases the proliferative potential of human cells without inducing cancer-associated changes. We have extended, by hTERT transduction, the proliferative in vitro potential of a human LGG cell line derived from a pediatric pilocytic astrocytoma (PA) surgical sample. Remarkably, the hTERT-transduced LGG cells showed a behavior similar to that of the parental line in terms of biological responses to NGF treatment, including molecular events associated with induction of NGF-related differentiation. Therefore, transduction of LGG cells with hTERT can provide a valid approach to increase the in vitro life-span of patient-derived astrocytoma primary cultures, characterized by a finite proliferative potential.

Nerve Growth Factor as an Ocular Therapy: Applications, Challenges, and Future Directions

Nerve growth factor (NGF), the prototypical neurotrophin first discovered in the 1950s, has recently garnered increased interest as a therapeutic agent promoting neuronal health and regeneration. After gaining orphan drug status within the last decade, NGF-related research and drug development has accelerated. The purpose of this article is to review the preclinical and clinical evidence of NGF in various applications, including central and peripheral nervous system, skin, and ophthalmic disorders. We focus on the ophthalmic applications including not only the FDA-approved indication of neurotrophic keratitis but also retinal disease and glaucoma. NGF represents a promising therapy whose therapeutic profile is evolving. The challenges related to this therapy are reviewed, along with possible solutions and future directions.

Topical delivery of nerve growth factor for treatment of ocular and brain disorders

Neurotrophins are a family of proteins that support neuronal proliferation, survival, and differentiation in the central and peripheral nervous systems, and are regulators of neuronal plasticity. Nerve growth factor is one of the best-described neurotrophins and has advanced to clinical trials for treatment of ocular and brain diseases due to its trophic and regenerative properties. Prior trials over the past few decades have produced conflicting results, which have principally been ascribed to adverse effects of systemic nerve growth factor administration, together with poor penetrance of the blood-brain barrier that impairs drug delivery. Contrastingly, recent studies have revealed that topical ocular and intranasal nerve growth factor administration are safe and effective, suggesting that topical nerve growth factor delivery is a potential alternative to both systemic and invasive intracerebral delivery. The therapeutic effects of local nerve growth factor delivery have been extensively investigated for different ophthalmic diseases, including neurotrophic keratitis, glaucoma, retinitis pigmentosa, and dry eye disease. Further, promising pharmacologic effects were reported in an optic glioma model, which indicated that topically administered nerve growth factor diffused far beyond where it was topically applied. These findings support the therapeutic potential of delivering topical nerve growth factor preparations intranasally for acquired and degenerative brain disorders. Preliminary clinical findings in both traumatic and non-traumatic acquired brain injuries are encouraging, especially in pediatric patients, and clinical trials are ongoing. The present review will focus on the therapeutic effects of both ocular and intranasal nerve growth factor delivery for diseases of the brain and eye.

Management of Children with Optic Gliomas and Neurofibromatosis Type 1

Optic pathway gliomas (OPG) are a common cancer in children with neurofibromatosis type 1. OPGs can cause clinical symptoms such as reduction of visual acuity, alterations of the visual field, pallor of the optical papilla, strabismus, endocrinological alterations up to diencephalic syndrome.The current guidelines provide for wait and see as the main approach if the tumor is not causing visual deterioration and adopting treatment only in the event of significant impairment of the visual function. Therefore, it is essential to early detect the visual deterioration changes as well as the identification of children eligible for treatment.

Combined Intravitreal Dexamethasone Implant and Cataract Surgery in Patients with Diabetic Retinopathy: Effect on Retinal Morphology and Function

Introduction

Cataract surgery can be associated with vision-threatening complications in patients with diabetes. This study aimed to assess the functional and anatomic outcomes of the intravitreal dexamethasone (DEX) implant, administered at the time as cataract surgery, in patients with diabetic retinopathy and diabetic macular edema (DME).

Methods

This was a retrospective, observational, and single-center study. The primary endpoint was the mean change in central macular thickness (CMT) from baseline to month 1. Secondary endpoints included mean change in best corrected visual acuity (BCVA) from baseline to month 1 and 3, mean change in CMT from baseline to month 3, the photopic negative response (PhNR) and the b wave of flash full-field electroretinogram from baseline to month 1, and the incidence of adverse events.

Results

Twenty-four eyes of 21 patients were included in the study. The mean (range) age of patients was 69 (63–87) years and 13 (61.9%) were men. Mean (standard deviation) CMT significantly decreased from 447 (134) µm at baseline to 341 (134) µm at month 1 (mean difference − 106 ± 134 µm, 95% CI − 183.9 to − 28.1 µm; p = 0.0087). BCVA significantly improved from 46 (20) ETDRS letters at baseline to 59 (22) ETDRS letters at month 1 (mean difference 13 ± 21 letters, 95% CI 0.8–25.2 letters; p = 0.0375). Regarding electrophysiology, there was a statistically significant reduction in mean PhNR from 5.24 (1.67) µV at baseline to 3.73 (1.19) µV at month 1 (mean difference − 1.51 ± 0.42 µV, 95% CI − 2.4 to − 0.7 µV, p = 0.0008); whereas b wave amplitude did not change (12.69 ± 6.89 µV at baseline versus 12.29 ± 6.30 µV at month 1; p = 0.8347). Four (16.7%) eyes developed ocular hypertension over the course of follow-up, which was successfully controlled with topical hypotensive medication.

Conclusion

Perioperative DEX implant significantly improved both anatomic and functional outcomes in patients with DME who underwent cataract surgery.

Treatment and Long-Term Sequelae in Childhood Brain Tumors

In children treated for brain tumors, important deficits in cognitive development have been described. The reduction of Intelligence Quotient (IQ) is correlated with multiple conditions such as tumor location, obstructive hydrocephalus, surgical intervention, and above all, the use of radiotherapy, especially in young children. Demyelinization represents the most striking microscopic alteration following radiation: cerebral white matter’s loss and failure to white matter development could partly account for changes in IQ score.

Recently, combined chemo-radiotherapeutic approaches and the improvement of radiotherapy techniques have enabled the reduction of neurocognitive symptoms and improved the standard of life of childhood brain tumor survivors.

Intranasal nerve growth factor administration improves neurological outcome after GBS meningitis

Nerve growth factor (NGF) is a neurotrophin that promotes neural recovery and plasticity after experimental brain injury, supporting neuronal growth, differentiation, and survival of brain cells. Only a few studies reported NGF administration in pediatric patients with impaired brain functions after traumatic injuries, ischemic or infectious diseases, such as meningitis. We described the beneficial therapeutic effects of human-recombinant nerve growth factor (hr-NGF) treatment in an infant with persistent unresponsive wakefulness syndrome (UWS), due to late-onset group B Streptococcus meningitis. The infant received five monthly cycles of intranasal hr-NGF (0.1 mg/kg, 3 times daily for 7 consecutive days) through a mucosal atomizer device (MAD). NGF administration improved functional [positron emission tomography/computed tomography (PET/CT), single-photon emission/computed tomography (SPECT/CT), and magnetic resonance imaging (MRI)] assessments, electrophysiological [Electroencephalogram (EEG)] studies, as well as main cognitive processes and clinical and neurological functions. After hr-NGF treatment, significant improvements in facial mimicry, attention, motor reactions, oral motility, and feeding capacity were observed. She also recovered some hypothalamic functions and her cough reflex was restored. No side effects were reported during and after the treatment. For the first time ever, hr-NGF has been successfully utilized in an infant with UWS and severe neurologic outcome due to a bacterial meningitis. Although further studies are needed for better understanding the neuroprotective role of this neurotrophin, intranasal hr-NGF administration appears to be a promising and save rescuing strategy treatment in infants with severe neurological impairment after brain damage.

Effects of Cord Blood Serum (CBS) on viability of retinal Müller glial cells under in vitro injury

Oxidative stress and inflammation determine retinal ganglion cell degeneration, leading to retinal impairment and vision loss. Müller glial cells regulate retinal repair under injury, through gliosis. Meanwhile, reactive gliosis can turn in pathological effects, contributing to neurodegeneration. In the present study, we tested whether Cord Blood Serum (CBS), rich of growth factors, might improve the viability of Müller cells under in vitro damage. BDNF, NGF, TGF-α, GDNF and EGF levels were measured in CBS samples by Human Magnetic Luminex Assay. CBS effects were evaluated on rat (rMC-1) and human (MIO-M1) Müller cells, under H₂O₂ and IL-1β damage. Cells grown with FBS or CBS both at 5% were exposed to stress and analyzed in terms of cell viability, GFAP, IL-6 and TNF-α expression. CBS was also administrated after treatment with K252a, inhibitor of the neurotrophin receptor Trk. Cell viability of rMC-1 and MIO-M1 resulted significantly improved when pretreated with CBS and exposed to H₂O₂ and IL-1β, in comparison to the standard culture with FBS. Accordingly, the gliosis marker GFAP resulted down-regulated following CBS priming. In parallel, we observed a lower expression of the inflammatory mediators in rMC-1 (TNF-α) and MIO-M1 (IL-6, TNF- α), especially in presence of inflammatory damage. Trk inhibition through K252a administration impaired the effects of CBS under stress conditions on MIO-M1 and rMC-1 viability, not significantly different from FBS condition. CBS is enriched with neurotrophins and its administration to rMC-1 and MIO-M1 attenuates the cytotoxic effects of H₂O₂ and IL-1β. Moreover, the decrease of the main markers of gliosis and inflammation suggests a promising use of CBS for neuroprotection aims. This study is a preliminary basis that prompts future investigations to deeply explore and confirm the CBS potential.

Temozolomide and oral etoposide in children with recurrent malignant brain tumors

Despite advances in the treatment of brain tumors, the prognosis of children with recurrent malignant brain tumors remains poor. Etoposide (VP-16), an inhibitor of nuclear enzyme deoxyribonucleic acid (DNA)-topoisomerase II, has shown activity in brain tumors. Its efficacy appears schedule dependent but, to date, the most effective schedule of administration has not been well defined. Temozolomide (TMZ), like VP-16, penetrates the blood–brain barrier and has activity against malignant brain tumors. This novel alkylating agent is rapidly absorbed and is highly bioavailable after oral administration. The antitumor activity of TMZ has been shown to be schedule dependent. Based on the evidence of different mechanisms of cytotoxicity, TMZ and VP-16 have been utilized in combination in patients with malignant brain tumors. This review evaluates the results derived from the combination use of TMZ and oral VP-16. The reported data suggest potential activity of oral VP-16 and TMZ alone or in combination. Further clinical trials are needed to explore and confirm their promising activity in relapsed brain neoplasms.

Cord Blood Serum (CBS)-Based Eye Drops Modulate Light-Induced Neurodegeneration in Albino Rat Retinas

Age-related macular degeneration (AMD) is one of the leading causes of visual loss in western countries, it has no cure, and its incidence will grow in the future, for the overall population aging. Albino rats with retinal degeneration induced by exposure to high-intensity light (light-damage, LD) have been extensively used as a model of AMD to test neuroprotective agents. Among them, trophic factors (NGF and BDNF) have been shown to play a significant role in photoreceptors' survival. Interestingly, cord blood serum (CBS) is an extract full of chemokines and trophic factors; we, therefore, hypothesized that CBS could be an excellent candidate for neuroprotection. Here, we investigate whether CBS-based eye drops might mitigate the effects of light-induced retinal degeneration in albino rats. CBS treatment significantly preserved flash-electroretinogram (f-ERG) response after LD and reduced the "hot-spot" extension. Besides, CBS-treated animals better preserved the morphology of the outer nuclear layer, together with a reduction in microglia migration and activation. Interestingly, the treatment did not modulate reactive gliosis and activation of the self-protective mechanism (FGF2). In conclusion, our results suggest that CBS-based eye drops might be successfully used to mitigate retinal neurodegenerative processes such as AMD.

Optic Pathway Glioma in Type 1 Neurofibromatosis: Review of Its Pathogenesis, Diagnostic Assessment, and Treatment Recommendations

Type 1 neurofibromatosis (NF1) is a dominantly inherited condition predisposing to tumor development. Optic pathway glioma (OPG) is the most frequent central nervous system tumor in children with NF1, affecting approximately 15-20% of patients. The lack of well-established prognostic markers and the wide clinical variability with respect to tumor progression and visual outcome make the clinical management of these tumors challenging, with significant differences among distinct centers. We reviewed published articles on OPG diagnostic protocol, follow-up and treatment in NF1. Cohorts of NF1 children with OPG reported in the literature and patients prospectively collected in our center were analyzed with regard to clinical data, tumor anatomical site, diagnostic workflow, treatment and outcome. In addition, we discussed the recent findings on the pathophysiology of OPG development in NF1. This review provides a comprehensive overview about the clinical management of NF1-associated OPG, focusing on the most recent advances from preclinical studies with genetically engineered models and the ongoing clinical trials.

Knockdown of RAD18 inhibits glioblastoma development

This study aimed at investigating the role of RAD18 in the regulation of glioblastoma development as well as the underlying mechanisms. The human glioblastoma U251 and U87MG cells were transfected with siRNAs specifically targeting RAD18, and the effects of knockdown of RAD18 on the viability, apoptosis, migration, and invasion of U251 and U87MG cells were investigated. Transcriptome sequencing of the siRNA-RAD18-tranfected and siRNA-NC-transfected U251 cells was performed, followed by bioinformatic analyses for sequencing data. The results showed that knockdown of RAD18 significantly inhibited cell viability, promoted apoptosis, and suppressed migration and invasion of U251 and U87MG cells. Bioinformatic analyses of sequencing data identified 1,051 differentially expressed genes (DEGs) (369 up- and 682 downregulated genes) in the siRNA-RAD18-transfected U251 cells compared with siRNA-NC-transfected U251 cells. Eleven DEGs, including nerve growth factor (NGF), colony-stimulating factor 2 (CSF2), matrix metallopeptidase 1 (MMP1), platelet-derived growth factor receptor α (PDGFRA), and heme oxygenase 1 (HMOX1), were identified as the hub nodes in protein-protein interaction (PPI) network. Moreover, the aforementioned 11 hub genes were significantly enriched in PI3K-Akt signaling pathway and GO functions associated with the extracellular region. Notably, quantitative real-time polymerase chain reaction further confirmed that the expression levels of NGF, CSF2, HMOX1, and MMP1 were significantly downregulated, while that of PDGFRA was markedly upregulated in the siRNA-RAD18-transfected U251 cells than in the siRNA-NC cells. In conclusion, the knockdown of RAD18 may inhibit glioblastoma development by regulating the expression of the aforementioned key DEGs.

Long-term visual acuity in patients with optic pathway glioma treated during childhood with up-front BB-SFOP chemotherapy-Analysis of a French pediatric historical cohort

Background

Visual outcome is one of the main issues in the treatment of optic pathway glioma in childhood. Although the prognostic factors of low vision have been discussed extensively, no reliable indicators for visual loss exist. Therefore, we aimed to define initial and evolving factors associated with long-term vision loss.

Methods

We conducted a multicenter historical cohort study of children treated in France with up-front BB-SFOP chemotherapy between 1990 and 2004. Visual acuity performed at the long-term follow-up visit or within 6 months prior was analyzed. Logistic regression analysis was used to estimate the effects of clinical and radiological factors on long-term visual outcome.

Findings

Of the 180 patients in the cohort, long-term visual acuity data were available for 132 (73.3%) patients (median follow-up: 14.2 years; range: 6.1–25.6). At the last follow-up, 61/132 patients (46.2%) had impaired vision, and 35 of these patients (57.3%) were partially sighted or blind. Multivariate analysis showed that factors associated with a worse prognosis for long-term visual acuity were an age at diagnosis of < 1 year (OR 3.5 [95% CI: 1.1–11.2], p = 0.04), tumor extent (OR 4.7 [95% CI: 1.2–19.9], p = 0.03), intracranial hypertension requiring one or more surgical procedures (OR 5.6 [95% CI: 1.8–18.4], p = 0.003), and the need for additional treatment after initial BB-SFOP chemotherapy (OR 3.5 [95% CI: 1.1–11.9], p = 0.04). NF1 status did not appear as a prognostic factor, but in non-NF1 patients, a decrease in tumor volume with contrast enhancement after BB-SFOP chemotherapy was directly associated with a better visual prognosis (OR 0.8 [95% CI: 0.8–0.9], p = 0.04).

Interpretation

Our study confirms that a large proportion of children with optic pathway glioma have poor long-term outcomes of visual acuity. These data suggest new prognostic factors for visual acuity, but these results need to be confirmed further by large- and international-scale studies.

Nerve Growth Factor Role on Retinal Ganglion Cell Survival and Axon Regrowth: Effects of Ocular Administration in Experimental Model of Optic Nerve Injury

Retinal ganglion cell (RGC) degeneration occurs within 2 weeks following optic nerve crush (ONC) as a consequence of reduced retro-transport of growth factors including nerve growth factor (NGF). The hypothesis that intravitreal (ivt) and eye drop (ed) administration of recombinant human NGF (rhNGF) might counteract ONC in adult rats is explored in this study. We found that both ivt- and ed-rhNGF reduced RGC loss and stimulated axonal regrowth. Chiefly, survival and regenerative effects of rhNGF were associated with a reduction of cells co-expressing Nogo-A/p75NTR at crush site borders, which contribute to glia scar formation following nerve injury, and induce further degeneration. We also found that ocular application of rhNGF reduced p75NTR and proNGF and enhanced phosphorylation of TrkA and its intracellular signals at retina level. Nogo-R and Rock2 expression was also normalized by ed-rhNGF treatment in both ONC and contralateral retina. Our findings that ocular applied NGF reaches and exerts biological actions on posterior segment of the eye give a further insight into the neurotrophin diffusion/transport through eye structures and/or their trafficking in optic nerve. In addition, the use of a highly purified NGF form in injury condition in which proNGF/p75NTR binding is favored indicates that increased availability of mature NGF restores the balance between TrkA and p75NGF, thus resulting in RGC survival and axonal growth. In conclusion, ocular applied NGF is confirmed as a good experimental paradigm to study mechanisms of neurodegeneration and regeneration, disclose biomarkers, and time windows for efficacy treatment following cell or nerve injury.

Insights into optic pathway glioma vision loss from mouse models of neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common cancer predisposition syndrome caused by mutations in the NF1 gene. The NF1-encoded protein (neurofibromin) is an inhibitor of the oncoprotein RAS and controls cell growth and survival. Individuals with NF1 are prone to developing low-grade tumors of the optic nerves, chiasm, tracts, and radiations, termed optic pathway gliomas (OPGs), which can cause vision loss. A paucity of surgical tumor specimens and of patient-derived xenografts for investigative studies has limited our understanding of human NF1-associated OPG (NF1-OPG). However, mice genetically engineered to harbor Nf1 gene mutations develop optic gliomas that share many features of their human counterparts. These genetically engineered mouse (GEM) strains have provided important insights into the cellular and molecular determinants that underlie mouse Nf1 optic glioma development, maintenance, and associated vision loss, with relevance by extension to human NF1-OPG disease. Herein, we review our current understanding of NF1-OPG pathobiology and describe the mechanisms responsible for tumor initiation, growth, and associated vision loss in Nf1 GEM models. We also discuss how Nf1 GEM and other preclinical models can be deployed to identify and evaluate molecularly targeted therapies for OPG, particularly as they pertain to future strategies aimed at preventing or improving tumor-associated vision loss in children with NF1.

MicroRNA-21 promotes glioma cell proliferation and inhibits senescence and apoptosis by targeting SPRY1 via the PTEN/PI3K/AKT signaling pathway

AIMS

Our study aims to investigate the effect of microRNA-21 (miR-21) on the proliferation, senescence, and apoptosis of glioma cells by targeting SPRY1 via the PTEN/PI3K/AKT signaling pathway.

METHODS

Glioma tissues and brain tissues were collected for this study after surgical decompression for traumatic brain injury. RT-qPCR was employed to measure mRNA levels of miR-21, SPRY1, PTEN, PI3K, and AKT, and Western blotting was conducted to determine protein levels of SPRY1, PTEN, PI3K, AKT, p-AKT, Caspase-3, Caspase-9, P53, GSK3, and p-GSK3. Human glioma U87 cells were assigned into the blank, negative control (NC), miR-21 mimics, miR-21 inhibitors, siRNA-SPRY1, and miR-21 inhibitors + siRNA-SPRY1 groups, with human HEB cells serving as the normal group. Cell proliferation, cell cycle, and apoptosis were determined by MTT and flow cytometry, respectively.

RESULTS

Compared with control group, an increased expression of miR-21, PI3K, AKT, p-AKT, P53, and p-GSK3, and a decreased expression of SPRY1, PTEN, Caspase-3, and Caspase-9 were observed in the glioma group, and no significant differences were found in the expression of GSK3. SPRY1 was verified to be the target gene of miR-21. Compared with the blank and NC groups, levels of PI3K, AKT, p-AKT, P53, and p-GSK3 increased while levels of SPRY1, PTEN, Caspase-3, and Caspase-9 decreased in the miR-21 mimics and siRNA-SPRY1 groups; the miR-21 inhibitors group reversed the tendency; furthermore, the miR-21 inhibitors group showed decreased cell proliferation but promoted apoptosis, which were opposite to the results of the miR-21 mimics and siRNA-SPRY1 groups.

CONCLUSION

MicroRNA-21 might promote cell proliferation and inhibit cell senescence and apoptosis of human glioma cells by targeting SPRY1 via the PTEN/PI3K/AKT signaling pathway.

Nerve Growth Factor: Early Studies and Recent Clinical Trials

Since its discovery, nerve growth factor (NGF) has long occupied a critical role in developmental and adult neurobiology for its many important regulatory functions on the survival, growth and differentiation of nerve cells in the peripheral and central nervous system. NGF is the first discovered member of a family of neurotrophic factors, collectively indicated as neurotrophins, (which include brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin 4/5). NGF was discovered for its action on the survival and differentiation of selected populations of peripheral neurons. Since then, an enormous number of basic and human studies were undertaken to explore the role of purified NGF to prevent the death of NGF-receptive cells. These studies revealed that NGF possesses important therapeutic properties, after topical administration, on human cutaneous pressure ulcer, corneal ulcers, glaucoma, retinal maculopathy, Retinitis Pigmentosa and in pediatric optic gliomas and brain traumas. The aim of this review is to present our previous, recent and ongoing clinical studies on the therapeutic properties of NGF.

Ocular Nerve Growth Factor (NGF) and NGF Eye Drop Application as Paradigms to Investigate NGF Neuroprotective and Reparative Actions

The eye is a central nervous system structure that is uniquely accessible to local treatment. Through the ocular surface, it is possible to access the retina, optic nerve, and brain. Animal models of retina degeneration or optic nerve crush could thus serve as tools to investigate whether and how factors, which are anterogradely or retrogradely transported through the optic nerve, might contribute to activate neuroprotection and eventually regeneration. Among these factors, nerve growth factor (NGF) plays a crucial role during development of the visual system, as well as during the entire life span, and in pathological conditions. The ability of NGF to exert survival and trophic actions on the retina and brain cells when applied intraocularly and topically as eye drops is critically reviewed here, together with the effects of ocular neurotrophins on neuronal pathways influencing body rhythm, cognitions, and behavioral functions. The latest data from animal models and humans are presented, and the mechanism of action of ocularly administered NGF is discussed. NGF eye drops are proposed as an experimental strategy to investigate the role and cellular targets of neurotrophins in the mechanism(s) underlying neurodegeneration/regeneration and their involvement in the regulation of neurological and behavioral dysfunctions.

A Potential Nanofiber Membrane Device for Filling Surgical Residual Cavity to Prevent Glioma Recurrence and Improve Local Neural Tissue Reconstruction

This study aims to develop a novel device with nanofiber membrane capable of sustained release of temozolomide (TMZ) and neuron growth factor (NGF). An improved bio-availability of TMZ and NGF in surroundings proximal to the device was expected to be attained for a prolonged period of time. The device was developed by integrating TMZ-doped polycaprolactone (PCL) nanofiber (TP) membrane and NGF-coated PCL (NGFP) membrane using sodium alginate hydrogel. TP was prepared by direct electrospinning of TMZ/PCL. NGFP membrane was developed by layer-by-layer assembling technology. The incorporation of TMZ-doped nanofiber and NGFP nanofiber in the device was confirmed by scanning electron microscopy. The number of NGF layer in NGF-coated PCL membrane could be readily measured with energy spectrum analysis. The in vitro release study showed that TP-NGFP-TP membrane could efficiently liberate TMZ to inhibit the growth of C6 glioma cells, and sufficient NGF to induce the differentiation of PC12 neuron cells over four weeks. Such TP-NGFP-TP membrane device can be employed as a tampon to fill up surgical residual cavity and afford residual glioma removal, structural support, hemostasis, and local neural tissue reconstruction in the surgical treatment of glioma. The study opens a horizon to develop multifunctional biomaterial device for maximized glioma treatment efficacy.

Optic pathway gliomas in neurofibromatosis-1: controversies and recommendations

Optic pathway glioma (OPG), seen in 15% to 20% of individuals with neurofibromatosis type 1 (NF1), account for significant morbidity in young children with NF1. Overwhelmingly a tumor of children younger than 7 years, OPG may present in individuals with NF1 at any age. Although many OPG may remain indolent and never cause signs or symptoms, others lead to vision loss, proptosis, or precocious puberty. Because the natural history and treatment of NF1-associated OPG is different from that of sporadic OPG in individuals without NF1, a task force composed of basic scientists and clinical researchers was assembled in 1997 to propose a set of guidelines for the diagnosis and management of NF1-associated OPG. This new review highlights advances in our understanding of the pathophysiology and clinical behavior of these tumors made over the last 10 years. Controversies in both the diagnosis and management of these tumors are examined. Finally, specific evidence-based recommendations are proposed for clinicians caring for children with NF1.