Getting Into the Brain: The Intranasal Approach to Enhance the Delivery of Nerve Growth Factor and Its Painless Derivative in Alzheimer’s Disease and Down Syndrome

Multifaceted Roles of Nerve Growth Factor: A Comprehensive Review with a Special Insight into Pediatric Perspectives

Nerve growth factor (NGF) is a neurotrophic peptide largely revealed for its ability to regulate the growth and survival of peripheral sensory, sympathetic, and central cholinergic neurons. The pro-survival and regenerative properties of neurotrophic factors propose a therapeutic potential in a wide range of brain diseases, and NGF, in particular, has appeared as an encouraging potential treatment. In this review, a summary of clinical studies regarding NGF and its therapeutic effects published to date, with a specific interest in the pediatric context, will be attempted. NGF has been studied in neurological disorders such as hypoxic-ischemic encephalopathy, traumatic brain injury, neurobehavioral and neurodevelopmental diseases, congenital malformations, cerebral infections, and in oncological and ocular diseases. The potential of NGF to support neuronal survival, repair, and plasticity in these contexts is highlighted. Emerging therapeutic strategies for NGF delivery, including intranasal administration as well as advanced nanotechnology-based methods, are discussed. These techniques aim to enhance NGF bioavailability and target specificity, optimizing therapeutic outcomes while minimizing systemic side effects. By synthesizing current research, this review underscores the promise and challenges of NGF-based therapies in pediatric neurology, advocating for continued innovation in delivery methods to fully harness NGF's therapeutic potential.

Current non-invasive strategies for brain drug delivery: overcoming blood-brain barrier transport

BACKGROUND

The blood-brain barrier (BBB) is a complex and dynamic structure that serves as a gatekeeper, restricting the migrations of most compounds and molecules from blood into the central nervous system (CNS). The BBB plays a crucial role in maintaining CNS physiological function and brain homeostasis. It can protect the CNS from the entrance of toxic and infectious agents, however, it also restricts the drug permeation into brain to play a therapeutic role. The BBB has been the biggest limiting hurdle to medications entering the brain excluding from the brain about 100% of large-molecule and more than 98% of all small-molecule neurotherapeutics. As a result, it is of inability for drug molecule to reach requisite concentrations within the brain.

OBJECTIVE

With the aim of enhancing drug permeability and efficacy, a variety of strategies have been developed: invasive approaches, such as intraarterial delivery, intrathecal delivery, or administrating directly the drug intraventricularly and intracerebrally; non-invasive approaches that take advantage of innate BBB functions, using prodrugs, focused ultrasound, intranasal administration or nanotechnology.

CONCLUSIONS

Here we mainly review recent developments and challenges related to non-invasive BBB-crossing techniques, whose benefits include higher efficacy, easier application, less treatment burden, better patient acceptability, and adherence. Additionally, we also analyze the potential of non-invasive methods in the treatment of CNS disorders and render them as a most suitable platform for the management of neurological diseases.

The Role of Oxidative Stress in Trisomy 21 Phenotype

Extensive research has been conducted to gain a deeper understanding of the deregulated metabolic pathways in the development of trisomy 21 (T21) or Down syndrome. This research has shed light on the hypothesis that oxidative stress plays a significant role in the manifestation of the T21 phenotype. Although in vivo studies have shown promising results in mitigating the detrimental effects of oxidative stress, there is currently a lack of introduced antioxidant treatment options targeting cognitive impairments associated with T21. To address this gap, a comprehensive literature review was conducted to provide an updated overview of the involvement of oxidative stress in T21. The review aimed to summarize the insights into the pathogenesis of the Down syndrome phenotype and present the findings of recent innovative research that focuses on improving cognitive function in T21 through various antioxidant interventions. By examining the existing literature, this research seeks to provide a holistic understanding of the role oxidative stress plays in the development of T21 and to explore novel approaches that target multiple aspects of antioxidant intervention to improve cognitive function in individuals with Down syndrome. The guides -base systematic review process (Hutton et al. 2015).

Neurotrophin Analog ENT-A044 Activates the p75 Neurotrophin Receptor, Regulating Neuronal Survival in a Cell Context-Dependent Manner

Neuronal cell fate is predominantly controlled based on the effects of growth factors, such as neurotrophins, and the activation of a variety of signaling pathways acting through neurotrophin receptors, namely Trk and p75 (p75NTR). Despite their beneficial effects on brain function, their therapeutic use is compromised due to their polypeptidic nature and blood-brain-barrier impermeability. To overcome these limitations, our previous studies have proven that DHEA-derived synthetic analogs can act like neurotrophins, as they lack endocrine side effects. The present study focuses on the biological characterization of a newly synthesized analog, ENT-A044, and its role in inducing cell-specific functions of p75NTR. We show that ENT-A044 can induce cell death and phosphorylation of JNK protein by activating p75NTR. Additionally, ENT-A044 can induce the phosphorylation of TrkB receptor, indicating that our molecule can activate both neurotrophin receptors, enabling the protection of neuronal populations that express both receptors. Furthermore, the present study demonstrates, for the first time, the expression of p75NTR in human-induced Pluripotent Stem Cells-derived Neural Progenitor Cells (hiPSC-derived NPCs) and receptor-dependent cell death induced via ENT-A044 treatment. In conclusion, ENT-A044 is proposed as a lead molecule for the development of novel pharmacological agents, providing new therapeutic approaches and research tools, by controlling p75NTR actions.

The effects of painless nerve growth factor on human microglia polarization

Previous studies in the rat suggest that microglial cells represent a potential druggable target for nerve growth factor (NGF) in the brain. The painless human Nerve Growth Factor (hNGFp) is a recombinant mutated form of human nerve growth factor (hNGF) that shows identical neurotrophic and neuroprotective properties of wild-type NGF but displays at least 10-fold lower algogenic activity. From the pharmacological point of view, hNGFp is a biased tropomyosin receptor kinase A (TrkA) agonist and displays a significantly lower affinity for the p75 neurotrophin receptor (p75NTR). This study aimed to evaluate the expression of TrkA and p75NTR NGF receptors in two different human microglia cell lines, and to investigate the effects of hNGFp and wild-type NGF (NGF) on L-arginine metabolism, taken as a marker of microglia polarization. Both NGF receptors are expressed in human microglia cell lines and are effective in transducing signals triggered by NGF and hNGFp. The latter and, to a lesser extent, NGF inhibit cytokine-stimulated inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in these cells. Conversely NGF but not hNGFp stimulates arginase-mediated urea production.