Bleeding is increased in amyloid precursor protein knockout mouse

Alterations in the Processing of Platelet APP (Amyloid Beta Precursor Protein) in Alzheimer Disease: The Possible Nexus

Alzheimer's disease (AD) is the most common neurodegenerative disease associated with the development of dementia. The hallmarks of AD neuropathology are accumulations of amyloid peptide (Aβ) and neurofibrillary tangles (NFTs). Aβ is derived from the processing of APP (amyloid beta precursor protein) by BACE1 (beta-secretase 1) and γ-secretase through an amyloidogenic pathway. However, processing of APP by ADAM10/α-secretase (ADAM metallopeptidase domain 10) enzymes through a non-amyloidogenic pathway produces soluble APP alpha (sAPPα), which has a neuroprotective effect. It has been shown that activated platelets are implicated in the pathogenesis of AD, which also increases platelet activation. Under physiological conditions, platelets regulate synaptic plasticity and increase neuronal differentiation by regulation of the inflammatory response. However, overactivated platelets contribute to the pathogenesis of AD. Activated platelets represent the main source of circulating APP and Aβ that may be involved in AD neuropathology. Therefore, there is a close relationship between AD neuropathology and activated platelets. This review discusses the potential role of platelets in the pathogenesis of AD, and how targeting of activated platelets may reduce AD neuropathology.

Gene expression profiling in Venous thromboembolism: Insights from publicly available datasets

BACKGROUND

Venous thromboembolism (VTE) is the third most common cardiovascular disease and is a major cause of mobility and mortality worldwide. VTE is a complex multifactorial disease and genetic mechanisms underlying its pathogenesis is yet to be completely elucidated. The aim of the present study was to identify hub genes and pathways involved in development and progression of blood clot during VTE using gene expression data from public repositories.

METHODOLOGY

Differential gene expression (DEG) data from two datasets, GSE48000 and GSE19151 were analysed using GEO2R tool. Gene expression data of VTE patients were compared to that of healthy controls using various bioinformatics tools.

RESULTS

When the differentially expressed genes of the two datasets were compared, it was found that 19 genes were up-regulated while 134 genes were down-regulated. Gene ontology (GO) and pathway analysis revealed that pathways such as complement and coagulation cascade and B-cell receptor signalling along with DNA methylation, DNA alkylation and inflammatory genes were significantly up-regulated in VTE patients. On the other hand, differentially down-regulated genes included mitochondrial translation elongation, termination and biosysthesis along with heme biosynthesis, erythrocyte differentiation and homeostasis. The top 5 up-regulated hub genes obtained by protein-protein interaction (PPI) network analysis included MYC, FOS, SGK1, CR2 and CXCR4, whereas the top 5 down-regulated hub genes included MRPL13, MRPL3, MRPL11, RPS29 and RPL9. The up-regulated hub genes are functionally involved in maintain vascular integrity and complementation cascade while the down-regulated hub genes were mostly mitochondrial ribosomal proteins.

CONCLUSION

Present study highlights significantly enriched pathways and genes associated with VTE development and prognosis. The data hereby obtained could be used for designing newer diagnostic and therapeutic tools for VTE management.

Nanofiber Peptides for Bacterial Trapping: A Novel Approach to Antibiotic Alternatives in Wound Infections

The pervasive employment of antibiotics has engendered the advent of drug-resistant bacteria, imperiling the well-being and health of both humans and animals. Infections precipitated by such multi-resistant bacteria, especially those induced by methicillin-resistant Staphylococcus aureus (MRSA), pervade hospital settings, constituting a grave menace to patient vitality. Antimicrobial peptides (AMPs) have garnered considerable attention as a potent countermeasure against multidrug resistant bacteria. In preceding research endeavors, an insect-derived antimicrobial peptide is identified that, while possessing antimicrobial attributes, manifested suboptimal efficacy against drug-resistant Gram-positive bacteria. To ameliorate this issue, this work enhances the antimicrobial capabilities of the initial β-hairpin AMPs by substituting the structural sequence of the original AMPs with variant lengths of hydrophobic amino acid-hydrophilic amino acid repeat units. Throughout this endeavor, this work has identified a number of peptides that possess highly effective antibacterial characteristics against a wide range of bacteria. Additionally, some of these peptides have the ability to self-assemble into nanofibers, which then build networks in a distinctive manner to capture bacteria. Consequently, they represent prospective antibiotic alternatives for addressing wound infections engendered by drug-resistant bacteria.

Prospects for the pharmacological validation of the use of platelets as a “peripheral model” of neurons

Depressive disorders often occur in patients with cardiovascular pathologies and are a predictor of the development of thrombotic events, such as myocardial infarction, acute ischemic cerebrovascular accident, and pulmonary embolism. These are believed to be caused by the structural and biochemical relationship between platelets and brain neurons, which allows us to consider platelets as a marker of central nervous system (CNS) pathologies. This review aimed to assess the relationship between the hemostasis system and the development of depressive disorders using platelets as a “peripheral model” of neurons and evaluate the effectiveness of drugs for the treatment of depression. The study was conducted in accordance with the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analyses. A systematic literature search was conducted using PubMed, Cochrane, and CINAHL databases from 2018 to 2023, according to the following keywords: “hemostasis,” “acute cerebrovascular accident,” “depression,” “depressive disorders,” “platelets,” “cardiovascular diseases.” The data obtained indicate both a clinical link between depressive disorders and vascular events and the commonality of platelets and CNS cells because of the commonality of the following proteins: transporters and receptors of serotonin or 5-hydroxytryptamine, amyloid precursor protein, and brain neurotrophic factor, which were previously considered specific neural proteins. In addition, a relationship exists between hemostasis dynamics and drug therapy for depression. In this review, changes in hemostasis in terms of platelet activation in patients with depression and vascular disease were critically analyzed. The literature presents diverse mechanisms of platelet induction, which require further study. A rational study of the pathways of platelet activation in patients with depressive disorders will provide a comprehensive understanding of the molecular mechanisms underlying the relationship between hemostasis and depression in various vascular pathologies. Platelet activation in patients with depression and the dynamics of changes in hemostasis parameters during the treatment of depressive disorders allow us to consider hemostasis as a peripheral marker of the CNS and pharmacotherapy.

Clinical considerations in early-onset cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is an important cerebral small vessel disease associated with brain haemorrhage and cognitive change. The commonest form, sporadic amyloid-β CAA, usually affects people in mid- to later life. However, early-onset forms, though uncommon, are increasingly recognized and may result from genetic or iatrogenic causes that warrant specific and focused investigation and management. In this review, we firstly describe the causes of early-onset CAA, including monogenic causes of amyloid-β CAA (APP missense mutations and copy number variants; mutations of PSEN1 and PSEN2) and non-amyloid-β CAA (associated with ITM2B, CST3, GSN, PRNP and TTR mutations), and other unusual sporadic and acquired causes including the newly-recognized iatrogenic subtype. We then provide a structured approach for investigating early-onset CAA, and highlight important management considerations. Improving awareness of these unusual forms of CAA amongst healthcare professionals is essential for facilitating their prompt diagnosis, and an understanding of their underlying pathophysiology may have implications for more common, late-onset, forms of the disease.

Beyond Haemostasis and Thrombosis: Platelets in Depression and Its Co-Morbidities

Alongside their function in primary haemostasis and thrombo-inflammation, platelets are increasingly considered a bridge between mental, immunological and coagulation-related disorders. This review focuses on the link between platelets and the pathophysiology of major depressive disorder (MDD) and its most frequent comorbidities. Platelet- and neuron-shared proteins involved in MDD are functionally described. Platelet-related studies performed in the context of MDD, cardiovascular disease, and major neurodegenerative, neuropsychiatric and neurodevelopmental disorders are transversally presented from an epidemiological, genetic and functional point of view. To provide a complete scenario, we report the analysis of original data on the epidemiological link between platelets and depression symptoms suggesting moderating and interactive effects of sex on this association. Epidemiological and genetic studies discussed suggest that blood platelets might also be relevant biomarkers of MDD prediction and occurrence in the context of MDD comorbidities. Finally, this review has the ambition to formulate some directives and perspectives for future research on this topic.

Post-Translational Modifications of Platelet-Derived Amyloid Precursor Protein by Coagulation Factor XIII-A

The physiological function of amyloid β precursor protein (APP) in platelets has remained elusive. Upon platelet activation, APP localizes to the platelet surface and is proteolytically processed by proteases to release various metabolites, including amyloid β (Aβ) and soluble APP. Synthetic Aβ is a substrate of activated coagulation factor XIII (FXIII-A*), a transglutaminase that is active both inside and on the surface of platelets. Here we tested if platelet APP and its fragments are covalently modified by FXIII-A*. Platelet-derived FXIII-A* and fibrin(ogen) bound to APP, and their bound fractions increased 7- and 11-fold upon platelet activation, respectively. The processing of platelet APP was enhanced when FXIII-A* was inhibited. Soluble APPβ was covalently cross-linked by FXIII-A*. This mechanism regulating APP processing is significant, because controlling the processing of APP, such as by inhibiting specific secretases that cleave APP, is a therapeutic target for Alzheimer's disease.