Plasminogen decreases Aβ42 and Tau deposition, and shows multi-beneficial effects on Alzheimer's disease in mice and humans

Differential Effects of Aβ Peptides on the Plasmin-Dependent Degradation of ApoE3 and ApoE4

The ApoE4 allele of apolipoprotein E (ApoE4) is the strongest hereditary predisposition to Alzheimer's disease, even though ApoE4 only differs from the more common ApoE3 by a single amino acid substitution. Previous studies have shown that ApoE4 is more susceptible to proteolytic degradation than ApoE3. This is an important finding because of ApoE's role in cholesterol homeostasis and lipid transport in the brain. The molecular determinants of the increased susceptibility of ApoE4 to proteolysis are unknown. Here, we apply a combination of spectrometric and spectroscopic methods to show that amyloid-β (Aβ) peptides, including Aβ(1-40) and Aβ(pyroE3-42), differentially modulate the plasmin-dependent degradation of ApoE3 and ApoE4. In particular, our data reveal that while the Aβ peptides do not affect the proteolysis of ApoE3, the peptides enhance the degradation of ApoE4 significantly. Overall, this work motivates therapeutic development that targets the Aβ-induced dysregulation of ApoE4 homeostasis in individuals carrying the ApoE4 allele.

Shared interactions of six neurotropic viruses with 38 human proteins: a computational and literature-based exploration of viral interactions and hijacking of human proteins in neuropsychiatric disorders

INTRODUCTION

Viral infections may disrupt the structural and functional integrity of the nervous system, leading to acute conditions such as encephalitis, and neuropsychiatric conditions as mood disorders, schizophrenia, and neurodegenerative diseases. Investigating viral interactions of human proteins may reveal mechanisms underlying these effects and offer insights for therapeutic interventions. This study explores molecular interactions of virus and human proteins that may be related to neuropsychiatric disorders.

METHODS

Herpes Simplex Virus-1 (HSV-1), Cytomegalovirus (CMV), Epstein-Barr Virus (EBV), Influenza A virus (IAV) (H1N1, H5N1), and Human Immunodeficiency Virus (HIV1&2) were selected as key viruses. Protein structures for each virus were accessed from the Protein Data Bank and analyzed using the HMI-Pred web server to detect interface mimicry between viral and human proteins. The PANTHER classification system was used to categorize viral-human protein interactions based on function and cellular localization.

RESULTS

Energetically favorable viral-human protein interactions were identified for HSV-1 (467), CMV (514), EBV (495), H1N1 (3331), H5N1 (3533), and HIV 1&2 (62425). Besides immune and apoptosis-related pathways, key neurodegenerative pathways, including those associated with Parkinson's and Huntington's diseases, were frequently interacted. A total of 38 human proteins, including calmodulin 2, Ras-related botulinum toxin substrate 1 (Rac1), PDGF-β, and vimentin, were found to interact with all six viruses.

CONCLUSION

The study indicates a substantial number of energetically favorable interactions between human proteins and selected viral proteins, underscoring the complexity and breadth of viral strategies to hijack host cellular mechanisms. Further in vivo and in vitro validation is required to understand the implications of these interactions.

Serum Levels of Plasminogen Activator Inhibitor-1 in Patients with Parkinson's Disease

OBJECTIVES

The aim of the study was to investigate serum plasminogen activator inhibitor-1 (PAI-1) levels of patients with Parkinson's disease (PD) and their relationship with clinical findings and treatment of disease.

METHODS

The study included 125 PD patients and 48 healthy controls. Patients have been taking effective dopaminergic treatment regularly. The clinical severity of parkinsonism was assessed using the Hoehn and Yahr (HY) staging scale and the Unified PD Rating Scale (UPDRS). PAI-1 level analysis was performed by enzyme-linked immunosorbent assay.

RESULTS

Patients with PD had significantly lower serum PAI-1 levels than healthy controls (p < 0.001). Correlations with clinical findings showed only a marginally positive correlation between serum PAI-1 and HY score (r = 0.170, p = 0.05). In contrast, no significant correlation was demonstrated with the UPDRS score or other clinical parameters.

CONCLUSION

This is the first comprehensive analysis of serum PAI-1 levels in patients with PD. The distribution of PAI-1 in PD appears to be complex. The study results implicate that the paradoxical effects of tissue plasminogen activator on the brain parenchyma can be important in the pathophysiology of PD. Future studies are needed to elucidate the role of fibrinolytic system components in PD.

Plasminogen degrades α-synuclein, Tau and TDP-43 and decreases dopaminergic neurodegeneration in mouse models of Parkinson's disease

Parkinson's disease (PD) is the second most frequently diagnosed neurodegenerative disease, and it is characterized by the intracellular and extracellular accumulation of α-synuclein (α-syn) and Tau, which are major components of cytosolic protein inclusions called Lewy bodies, in the brain. Currently, there is a lack of effective methods that preventing PD progression. It has been suggested that the plasminogen activation system, which is a major extracellular proteolysis system, is involved in PD pathogenesis. We investigated the functional roles of plasminogen in vitro in an okadaic acid-induced Tau hyperphosphorylation NSC34 cell model, ex vivo using brains from normal controls and methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice, and in vivo in a widely used MPTP-induced PD mouse model and an α-syn overexpression mouse model. The in vitro, ex vivo and in vivo results showed that the administered plasminogen crossed the blood‒brain barrier (BBB), entered cells, and migrated to the nucleus, increased plasmin activity intracellularly, bound to α-syn through lysine binding sites, significantly promoted α-syn, Tau and TDP-43 clearance intracellularly and even intranuclearly in the brain, decreased dopaminergic neurodegeneration and increased the tyrosine hydroxylase levels in the substantia nigra and striatum, and improved motor function in PD mouse models. These findings indicate that plasminogen plays a wide range of pivotal protective roles in PD and therefore may be a promising drug candidate for PD treatment.

Alzheimer's disease: The role of proteins in formation, mechanisms, and new therapeutic approaches

Alzheimer's disease (AD) is a progressive neurological disorder that affects the central nervous system (CNS), leading to memory and cognitive decline. In AD, the brain experiences three main structural changes: a significant decrease in the quantity of neurons, the development of neurofibrillary tangles (NFT) composed of hyperphosphorylated tau protein, and the formation of amyloid beta (Aβ) or senile plaques, which are protein deposits found outside cells and surrounded by dystrophic neurites. Genetic studies have identified four genes associated with autosomal dominant or familial early-onset AD (FAD): amyloid precursor protein (APP), presenilin 1 (PS1), presenilin 2 (PS2), and apolipoprotein E (ApoE). The formation of plaques primarily involves the accumulation of Aβ, which can be influenced by mutations in APP, PS1, PS2, or ApoE genes. Mutations in the APP and presenilin (PS) proteins can cause an increased amyloid β peptides production, especially the further form of amyloidogenic known as Aβ42. Apart from genetic factors, environmental factors such as cytokines and neurotoxins may also have a significant impact on the development and progression of AD by influencing the formation of amyloid plaques and intracellular tangles. Exploring the causes and implications of protein aggregation in the brain could lead to innovative therapeutic approaches. Some promising therapy strategies that have reached the clinical stage include using acetylcholinesterase inhibitors, estrogen, nonsteroidal anti-inflammatory drugs (NSAIDs), antioxidants, and antiapoptotic agents. The most hopeful therapeutic strategies involve inhibiting activity of secretase and preventing the β-amyloid oligomers and fibrils formation, which are associated with the β-amyloid fibrils accumulation in AD. Additionally, immunotherapy development holds promise as a progressive therapeutic approach for treatment of AD. Recently, the two primary categories of brain stimulation techniques that have been studied for the treatment of AD are invasive brain stimulation (IBS) and non-invasive brain stimulation (NIBS). In this article, the amyloid proteins that play a significant role in the AD formation, the mechanism of disease formation as well as new drugs utilized to treat of AD will be reviewed.

Gelatin/polyethylene glycol-loaded magnesium hydroxide nanocomposite to attenuate acetylcholinesterase, neurotoxicity, and activation of GPR55 protein in rat models of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease marked by mitochondrial dysfunction, amyloid-β (Aβ) aggregation, and neuronal cell loss. G-protein-coupled receptor 55 (GPR55) has been used as a promising target for insulin receptors in diabetes therapy, but GPR55's role in AD is still unidentified. Gelatin (GE) and polyethylene glycol (PEG) polymeric hydrogels are commonly used in the drug delivery system. Therefore, the aim of the present study was the preparation of magnesium hydroxide nanocomposite using Clitoria ternatea (CT) flower extract, GE, and PEG (GE/PEG/Mg(OH)2NCs) by the green precipitation method. The synthesized GE/PEG/Mg(OH)2NCs were used to determine the effect of GPR55 activation of intracerebroventricular administration on streptozotocin (ICV-STC)-induced cholinergic dysfunction, oxidative stress, neuroinflammation, and cognitive deficits. The GE/PEG/Mg(OH)2NCs were administered following bilateral ICV-STC administration (3 mg/kg) in experimental rats. Neurobehavioral assessments were performed using a Morris water maze (MWM) and a passive avoidance test (PA). Cholinergic and antioxidant activity, oxidative stress, and mitochondrial complex activity were estimated in the cortex and hippocampus through biochemical analysis. Inflammatory markers (TNF-α, IL-6, and IL-1β) were determined using the ELISA method. Our study results demonstrated that the GE/PEG/Mg(OH)2NCs treatment significantly improved spatial and non-spatial memory functions in behavioral studies. Moreover, the treatment with GE/PEG/Mg(OH)2NCs group significantly attenuated cholinergic dysfunction, oxidative stress, and inflammatory markers, and also highly improved anti-oxidant activity (GSH, SOD, CAT, and GPx) in the cortex and hippocampus regions. The western blot results suggest the activation of the GPR55 protein expression through GE/PEG/Mg(OH)2NCs. The histopathological studies showed clear cytoplasm and healthy neurons, effectively promoting neuronal activity. Furthermore, the molecular docking results demonstrated the binding affinity and potential interactions of the compounds with the AChE enzyme. In conclusion, the GE/PEG/Mg(OH)2NCs treated groups showed reduced neurotoxicity and have the potential as a therapeutic agent to effectively target AD.

Synthesis, in silico and in vitro studies of hydrazide-hydrazone imine derivatives as potential cholinesterase inhibitors

A series of hydrazide-hydrazone imine derivative compounds (3a-k) were synthesized and their structures characterized using FTIR, 1 H, and 13 C (NMR) spectroscopic methods. In addition, molecular structures of compounds 3a, 3d, and 3g were elucidated by X-ray diffraction technique. In vitro inhibition activities of hydrazide-hydrazone imine derivatives against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were investigated. Compound 3i (IC50  = 2.01 μM) exhibited the best inhibitory activity against AChE, comparable to the control Galantamine (IC50  = 2.60 μM). Against BChE, compound 3h (IC50  = 2.83 μM) showed the best inhibitory property which is higher control Galantamine (IC50  = 3.70 μM). The Ki values of compound 3i (Ki = 0.63 μM) and compound 3h (Ki = 0.94 μM) that have the strongest inhibitory potential were determined against AChE and BChE, respectively. According to the docking result, the most stable conformation of AChE and compound 3i showed that it has a binding affinity of -10.82 kcal/moL. The binding affinity of the most stable conformation formed by BChE and compound 3h is -8.60 kcal/moL. Finally, in silico results and pharmacokinetic parameters of ADME showed that these compounds have good oral bioavailability properties.