Regional comparison of the neurogenic effects of CNTF-derived peptides and cerebrolysin in AβPP transgenic mice

Treatment with Cerebrolysin Prolongs Lifespan in a Mouse Model of Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare familial neurological disorder caused by mutations in the NOTCH3 gene and characterized by migraine attacks, depressive episodes, lacunar strokes, dementia, and premature death. Since there is no therapy for CADASIL the authors investigate whether the multi-modal neuropeptide drug Cerebrolysin may improve outcome in a murine CADASIL model. Twelve-month-old NOTCH3R169C mutant mice (n=176) are treated for nine weeks with Cerebrolysin or Vehicle and histopathological and functional outcomes are evaluated within the subsequent ten months. Cerebrolysin treatment improves spatial memory and overall health, reduces epigenetic aging, and prolongs lifespan, however, CADASIL-specific white matter vacuolization is not affected. On the molecular level Cerebrolysin treatment increases expression of Calcitonin Gene-Related Peptide (CGRP) and Silent Information Regulator Two (Sir2)-like protein 6 (SIRT6), decreases expression of Insulin-like Growth Factor 1 (IGF-1), and normalizes the expression of neurovascular laminin. In summary, Cerebrolysin fosters longevity and healthy aging without specifically affecting CADASIL pathology. Hence, Cerebrolysin may serve a therapeutic option for CADASIL and other disorders characterized by accelerated aging.

Neuroprotection and Non-Invasive Brain Stimulation: Facts or Fiction?

Non-Invasive Brain Stimulation (NIBS) techniques, such as transcranial Direct Current Stimulation (tDCS) and repetitive Magnetic Transcranial Stimulation (rTMS), are well-known non-pharmacological approaches to improve both motor and non-motor symptoms in patients with neurodegenerative disorders. Their use is of particular interest especially for the treatment of cognitive impairment in Alzheimer's Disease (AD), as well as axial disturbances in Parkinson's (PD), where conventional pharmacological therapies show very mild and short-lasting effects. However, their ability to interfere with disease progression over time is not well understood; recent evidence suggests that NIBS may have a neuroprotective effect, thus slowing disease progression and modulating the aggregation state of pathological proteins. In this narrative review, we gather current knowledge about neuroprotection and NIBS in neurodegenerative diseases (i.e., PD and AD), just mentioning the few results related to stroke. As further matter of debate, we discuss similarities and differences with Deep Brain Stimulation (DBS)-induced neuroprotective effects, and highlight possible future directions for ongoing clinical studies.

Alzheimer's Disease: Challenges and a Therapeutic Opportunity to Treat It with a Neurotrophic Compound

Alzheimer’s disease (AD) is a progressive neurodegenerative disease with an insidious onset and multifactorial nature. A deficit in neurogenesis and synaptic plasticity are considered the early pathological features associated with neurofibrillary tau and amyloid β pathologies and neuroinflammation. The imbalance of neurotrophic factors with an increase in FGF-2 level and a decrease in brain derived neurotrophic factor (BDNF) and neurotrophin 4 (NT-4) in the hippocampus, frontal cortex and parietal cortex and disruption of the brain micro-environment are other characteristics of AD. Neurotrophic factors are crucial in neuronal differentiation, maturation, and survival. Several attempts to use neurotrophic factors to treat AD were made, but these trials were halted due to their blood-brain barrier (BBB) impermeability, short-half-life, and severe side effects. In the present review we mainly focus on the major etiopathology features of AD and the use of a small neurotrophic and neurogenic peptide mimetic compound; P021 that was discovered in our laboratory and was found to overcome the difficulties faced in the administration of the whole neurotrophic factor proteins. We describe pre-clinical studies on P021 and its potential as a therapeutic drug for AD and related neurodegenerative disorders. Our study is limited because it focuses only on P021 and the relevant literature; a more thorough investigation is required to review studies on various therapeutic approaches and potential drugs that are emerging in the AD field.

Mapping Post-Translational Modifications in Brain Regions in Alzheimer's Disease Using Proteomics Data Mining

Alzheimer's disease (AD) is a leading cause of dementia and a neurodegenerative disease. Proteomics and post-translational modification (PTM) analyses offer new opportunities for a comprehensive understanding of pathophysiology of brain in AD. We report here multiple PTMs in patients with AD, harnessing publicly available proteomics data from nine brain regions and at three different Braak stages of disease progression. Specifically, we identified 7190 peptides with PTMs, corresponding to 2545 proteins from brain regions with intermediate tangles, and 6864 peptides with PTMs corresponding to 2465 proteins from brain regions with severe tangles. A total of 103 proteins with PTMs were expressed uniquely to intermediate tangles and severe tangles compared to no tangles. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis suggested the association of these proteins in AD progression through platelet activation. These modified proteins were also found to be enriched for the tricarboxylic acid (TCA) cycle, respiratory electron cycle, and detoxification of reactive oxygen species. The multi-PTM data reported here contribute to our understanding of the neurobiology of AD and highlight the prospects of omics systems science research in neurodegenerative diseases. The present study provides a region-wise classification for the proteins with PTMs along with their differential expression patterns, providing insights into the localization of these proteins upon modification. The catalog of multi-PTMs identified in the context of AD from different brain regions provides a unique platform for generating newer hypotheses in understanding the putative role of specific PTMs in AD pathogenesis.

Peptides Derived from Growth Factors to Treat Alzheimer's Disease

Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by progressive neuron losses in memory-related brain structures. The classical features of AD are a dysregulation of the cholinergic system, the accumulation of amyloid plaques, and neurofibrillary tangles. Unfortunately, current treatments are unable to cure or even delay the progression of the disease. Therefore, new therapeutic strategies have emerged, such as the exogenous administration of neurotrophic factors (e.g., NGF and BDNF) that are deficient or dysregulated in AD. However, their low capacity to cross the blood-brain barrier and their exorbitant cost currently limit their use. To overcome these limitations, short peptides mimicking the binding receptor sites of these growth factors have been developed. Such peptides can target selective signaling pathways involved in neuron survival, differentiation, and/or maintenance. This review focuses on growth factors and their derived peptides as potential treatment for AD. It describes (1) the physiological functions of growth factors in the brain, their neuronal signaling pathways, and alteration in AD; (2) the strategies to develop peptides derived from growth factor and their capacity to mimic the role of native proteins; and (3) new advancements and potential in using these molecules as therapeutic treatments for AD, as well as their limitations.

Prospective, double blinded, comparative assessment of the pharmacological activity of Cerebrolysin and distinct peptide preparations for the treatment of embolic stroke

BACKGROUND

Our previous work in acute ischemic stroke and TBI models focused on efficacy and pharmacological parameters of Cerebrolysin®. In this prospective, randomized, blinded, placebo-controlled study we compared efficacy of neuropeptide preparations with putative neurotrophic potential to the reference product Cerebrolysin® by assessing functional outcome and lesion volumes after embolic stroke in a rodent model.

METHODS

Male Wistar rats were subjected to embolic right middle cerebral artery occlusion and were treated with: 1) Cognistar® (Cerebroprotein Hydrolysate) 2.5 ml/kg, 2) Cerebrolysat® 2.5 ml/kg, 3) Cortexin® 1.7 mg/kg, 4) Cerebrolysin® 2.5 ml/kg, or 5) 1 ml of saline according to a pre-generated randomization plan. Dosages were defined according to the packet leaflet of the corresponding preparation and were adapted to the animal model as previously described. All enrolled rats received intraperitoneal injections once daily for 10 consecutive days, starting 4 h after occlusion. Functional outcome was assessed once weekly over four weeks by using a battery of behavioral tests. Infarct volume was measured four weeks after occlusion. Generalized Estimation Equations (GEE) was performed to study the treatment effect on overall functional recovery at day 28 (primary outcome), compared to saline controls.

RESULTS

Similar functional outcome was observed for saline control, Cognistar®, Cerebrolysat® and Cortexin®; in contrast, a significantly improved neurological outcome was observed with Cerebrolysin® treatment in comparison to saline as well as to the comparator drug treatment (p < .002). However, there was no significant difference in lesion volumes between rats treated with either Cortexin® (33.5 ± 1.9%), Cerebrolysat® (28.5 ± 2.4%), Cognistar® (34.7 ± 2.0%), or Cerebrolysin® (26.5 ± 2.3%) compared to saline-treated rats (30.8 ± 2.1%).

CONCLUSION

Among all tested neuropeptide preparations, Cerebrolysin® was the only agent that was associated with a significant improvement of neurological outcome after stroke.

Purification and characterization of a long-acting ciliary neurotrophic factor via genetically fused with an albumin-binding domain

Ciliary neurotrophic factor (CNTF) is a promising candidate for the treatment of neurodegenerative or metabolic diseases, but suffers rapid clearance in body. Herein we constructed a new long-acting recombinant human CNTF (rhCNTF) by genetic fusion with an albumin-binding domain (ABD) through a flexible peptide linker, hoping to endow the new molecule prolonged serum circulation time by binding with endogenous human serum albumin (HSA) and then utilizing the naturally long-half-life property of HSA. This fused protein rhCNTF-ABD was expressed in Escherichia coli mainly in the soluble form and purified through a two-step chromatography, with purity of 95% and a high yield of 90-100 mg/L culture. The in vitro binding ability of rhCNTF-ABD with HSA was firstly verified by incubation of the two components together followed by HP-SEC analysis. ABD-fused rhCNTF showed similar secondary and tertiary structure as the parent protein. It retained approximately 94.1% of the native bioactivity as demonstrated via CCK-8 cell viability assay analysis. In vivo studies in SD rats were performed and the terminal half-life of 483.89 min for rhCNTF-ABD was determined, which is about 14 folds longer than that of rhCNTF (34.28 min) and comparable with 20 k-40 kDa PEGylated rhCNTFs. The new constructed rhCNTF-ABD represents a potential therapeutic modality, and the proposed strategy may also have useful applications for other long-lasting biopharmaceutics' design.

Neurotrophic factor small-molecule mimetics mediated neuroregeneration and synaptic repair: emerging therapeutic modality for Alzheimer's disease

Alzheimer's disease (AD) is an incurable and debilitating chronic progressive neurodegenerative disorder which is the leading cause of dementia worldwide. AD is a heterogeneous and multifactorial disorder, histopathologically characterized by the presence of amyloid β (Aβ) plaques and neurofibrillary tangles composed of Aβ peptides and abnormally hyperphosphorylated tau protein, respectively. Independent of the various etiopathogenic mechanisms, neurodegeneration is a final common outcome of AD neuropathology. Synaptic loss is a better correlate of cognitive impairment in AD than Aβ or tau pathologies. Thus a highly promising therapeutic strategy for AD is to shift the balance from neurodegeneration to neuroregeneration and synaptic repair. Neurotrophic factors, by virtue of their neurogenic and neurotrophic activities, have potential for the treatment of AD. However, the clinical therapeutic usage of recombinant neurotrophic factors is limited because of the insurmountable hurdles of unfavorable pharmacokinetic properties, poor blood-brain barrier (BBB) permeability, and severe adverse effects. Neurotrophic factor small-molecule mimetics, in this context, represent a potential strategy to overcome these short comings, and have shown promise in preclinical studies. Neurotrophic factor small-molecule mimetics have been the focus of intense research in recent years for AD drug development. Here, we review the relevant literature regarding the therapeutic beneficial effect of neurotrophic factors in AD, and then discuss the recent status of research regarding the neurotrophic factor small-molecule mimetics as therapeutic candidates for AD. Lastly, we summarize the preclinical studies with a ciliary neurotrophic factor (CNTF) small-molecule peptide mimetic, Peptide 021 (P021). P021 is a neurogenic and neurotrophic compound which enhances dentate gyrus neurogenesis and memory processes via inhibiting leukemia inhibitory factor (LIF) signaling pathway and increasing brain-derived neurotrophic factor (BDNF) expression. It robustly inhibits tau abnormal hyperphosphorylation via increased BDNF mediated decrease in glycogen synthase kinase-3β (GSK-3β, major tau kinase) activity. P021 is a small molecular weight, BBB permeable compound with suitable pharmacokinetics for oral administration, and without adverse effects associated with native CNTF or BDNF molecule. P021 has shown beneficial therapeutic effect in several preclinical studies and has emerged as a highly promising compound for AD drug development.

Ciliary neurotrophic factor (CNTF): New facets of an old molecule for treating neurodegenerative and metabolic syndrome pathologies

Ciliary neurotrophic factor (CNTF) is the most extensively studied member of the cytokine family that signal through intracellular chains of the gp130/LIFRβ receptor. The severe phenotype in patients suffering from mutations inactivating LIFRβ indicates that members of this cytokine family play key, non-redundant roles during development. Accordingly, three decades of research has revealed potent and promising trophic and regulatory activities of CNTF in neurons, oligodendrocytes, muscle cells, bone cells, adipocytes and retinal cells. These findings led to clinical trials to test the therapeutic potential of CNTF and CNTF derivatives for treating neurodegenerative and metabolic diseases. Promising results have encouraged continuation of studies for treating retinal degenerative diseases. Results of some clinical trials showed that side-effects may limit the systemically administrated doses of CNTF. Therefore, therapies being currently tested rely on local delivery of CNTF using encapsulated cytokine-secreting implants. Since the side effects of CNTF might be linked to its ability to activate the alternative IL6Rα-LIFRβ-gp130 receptor, CNTFR-specific mutants of CNTF have been developed that bind to the CNTFRα-LIFRβ-gp130 receptor. These developments may prove to be a breakthrough for therapeutic applications of systemically administered CNTF in pathologies such as multiple sclerosis or Alzheimer's disease. The "designer cytokine approach" offers future opportunities to further enhance specificity by conjugating mutant CNTF with modified soluble CNTFRα to target therapeutically relevant cells that express gp130-LIFRβ and a specific cell surface marker.

Neuroprotective effects of sulforaphane on cholinergic neurons in mice with Alzheimer's disease-like lesions

Alzheimer’s disease (AD) is a common neurodegenerative disease in elderly individuals, and effective therapies are unavailable. This study was designed to investigate the neuroprotective effects of sulforaphane (an activator of NF-E2-related factor 2) on mice with AD-like lesions induced by combined administration of aluminum and d-galactose. Step-down-type passive avoidance tests showed sulforaphane ameliorated cognitive impairment in AD-like mice. Immunohistochemistry results indicated sulforaphane attenuated cholinergic neuron loss in the medial septal and hippocampal CA1 regions in AD-like mice. However, spectrophotometry revealed no significant difference in acetylcholine level or the activity of choline acetyltransferase or acetylcholinesterase in the cerebral cortex among groups of control and AD-like mice with and without sulforaphane treatment. Sulforaphane significantly increased the numbers of 5-bromo-2'-deoxyuridine-positive neurons in the subventricular and subgranular zones in AD-like mice which were significantly augmented compared with controls. Atomic absorption spectrometry revealed significantly lower aluminum levels in the brains of sulforaphane-treated AD-like mice than in those that did not receive sulforaphane treatment. In conclusion, sulforaphane ameliorates neurobehavioral deficits by reducing cholinergic neuron loss in the brains of AD-like mice, and the mechanism may be associated with neurogenesis and aluminum load reduction. These findings suggest that phytochemical sulforaphane has potential application in AD therapeutics.

Age-dependent neuroplasticity mechanisms in Alzheimer Tg2576 mice following modulation of brain amyloid-β levels

The objective of this study was to investigate the effects of modulating brain amyloid-β (Aβ) levels at different stages of amyloid pathology on synaptic function, inflammatory cell changes and hippocampal neurogenesis, i.e. processes perturbed in Alzheimer's disease (AD). Young (4- to 6-month-old) and older (15- to 18-month-old) APP(SWE) transgenic (Tg2576) mice were treated with the AD candidate drug (+)-phenserine for 16 consecutive days. We found significant reductions in insoluble Aβ1-42 levels in the cortices of both young and older transgenic mice, while significant reductions in soluble Aβ1-42 levels and insoluble Aβ1-40 levels were only found in animals aged 15-18 months. Autoradiography binding with the amyloid ligand Pittsburgh Compound B ((3)H-PIB) revealed a trend for reduced fibrillar Aβ deposition in the brains of older phenserine-treated Tg2576 mice. Phenserine treatment increased cortical synaptophysin levels in younger mice, while decreased interleukin-1β and increased monocyte chemoattractant protein-1 and tumor necrosis factor-alpha levels were detected in the cortices of older mice. The reduction in Aβ1-42 levels was associated with an increased number of bromodeoxyuridine-positive proliferating cells in the hippocampi of both young and older Tg2576 mice. To determine whether the increased cell proliferation was accompanied by increased neuronal production, the endogenous early neuronal marker doublecortin (DCX) was examined in the dentate gyrus (DG) using immunohistochemical detection. Although no changes in the total number of DCX(+)-expressing neurons were detected in the DG in Tg2576 mice at either age following (+)-phenserine treatment, dendritic arborization was increased in differentiating neurons in young Tg2576 mice. Collectively, these findings indicate that reducing Aβ1-42 levels in Tg2576 mice at an early pathological stage affects synaptic function by modulating the maturation and plasticity of newborn neurons in the brain. In contrast, lowering Aβ levels in Tg2576 mice when Aβ plaque pathology is prominent mainly alters the levels of proinflammatory cytokines and chemokines.

Peptidergic drugs for the treatment of traumatic brain injury

Traumatic brain injury (TBI) is a devastating medical condition that has an enormous socioeconomic impact because it affects more than 10 million people annually worldwide and is associated with high rates of hospitalization, mortality and disability. Although TBI survival has improved continuously for decades, particularly in developing countries, implementation of an effective drug therapy for TBI represents an unmet clinical need. All confirmatory trials conducted to date with drugs targeting a single TBI pathological pathway failed to show clinical efficacy, probably because TBI pathophysiology involves multiple cellular and molecular mechanisms of secondary brain damage. According to current scientific evidence of the participation of peptide-mediated mechanisms in the processes of brain injury and repair after TBI, peptidergic drugs represent a multimodal therapy alternative to improve acute outcome and long-term recovery in TBI patients. Preliminary randomized-controlled clinical trials and open-label studies conducted to date with the peptidergic drug Cerebrolysin® (Ever Neuro Pharma GmbH, Unterach, Austria) and with the endogenous neuropeptides progesterone and erythropoietin, showed positive clinical results. Cerebrolysin-treated patients had a faster clinical recovery, a shorter hospitalization time and a better long-term outcome. Treatment with progesterone showed advantages over placebo regarding TBI mortality and clinical outcome, whereas erythropoietin only reduced mortality. Further validation of these promising findings in confirmatory randomized-controlled clinical trials is warranted. This article reviews the scientific basis and clinical evidence on the development of multimodal peptidergic drugs as a therapeutic option for the effective treatment of TBI patients.

Cerebrolysin modulates pronerve growth factor/nerve growth factor ratio and ameliorates the cholinergic deficit in a transgenic model of Alzheimer's disease

Alzheimer's disease (AD) is characterized by degeneration of neocortex, limbic system, and basal forebrain, accompanied by accumulation of amyloid-β and tangle formation. Cerebrolysin (CBL), a peptide mixture with neurotrophic-like effects, is reported to improve cognition and activities of daily living in patients with AD. Likewise, CBL reduces synaptic and behavioral deficits in transgenic (tg) mice overexpressing the human amyloid precursor protein (hAPP). The neuroprotective effects of CBL may involve multiple mechanisms, including signaling regulation, control of APP metabolism, and expression of neurotrophic factors. We investigate the effects of CBL in the hAPP tg model of AD on levels of neurotrophic factors, including pro-nerve growth factor (NGF), NGF, brain-derived neurotrophic factor (BDNF), neurotropin (NT)-3, NT4, and ciliary neurotrophic factor (CNTF). Immunoblot analysis demonstrated that levels of pro-NGF were increased in saline-treated hAPP tg mice. In contrast, CBL-treated hAPP tg mice showed levels of pro-NGF comparable to control and increased levels of mature NGF. Consistently with these results, immunohistochemical analysis demonstrated increased NGF immunoreactivity in the hippocampus of CBL-treated hAPP tg mice. Protein levels of other neurotrophic factors, including BDNF, NT3, NT4, and CNTF, were unchanged. mRNA levels of NGF and other neurotrophins were also unchanged. Analysis of neurotrophin receptors showed preservation of the levels of TrKA and p75(NTR) immunoreactivity per cell in the nucleus basalis. Cholinergic cells in the nucleus basalis were reduced in the saline-treated hAPP tg mice, and treatment with CBL reduced these cholinergic deficits. These results suggest that the neurotrophic effects of CBL might involve modulation of the pro-NGF/NGF balance and a concomitant protection of cholinergic neurons.