Previous studies have identified that non-canonical nucleic acid structures known as G-quadruplexes (G4s) modulate protein aggregation and could play major roles in neurodegenerative diseases. Here we examine the presence and protein oligomerization activity of G4s that are enriched in human hippocampal aggregates. We found these G4s to be powerful, sequence-specific modulators of aggregation. Different G4s facilitated aggregate propagation in cells, caused tau to form distinct protein oligomer populations, and seeded tau fibrils with different fibril structure and length. This study highlights the importance of nucleic acid composition within aggregates, where small changes in nucleotide sequence and topology can vastly alter protein interactions, oligomerization, and fibrillization.

BACKGROUND:Individuals with Down Syndrome (DS) frequently develop early onset Alzheimer's disease (AD) with pathological hallmarks closely resembling AD due to several triplicated genes on chromosome 21. Polyamines are small, organic molecules that play a pivotal role for growth and differentiation, and a dysregulation of polyamine pathways is implicated in AD pathology. However, their role in DS-associated AD is unclear. METHODS:We analyzed polyamines and their metabolite levels in mouse hippocampal cells and human DS-AD and AD hippocampal tissue and assessed the effects of the ODC inhibitor difluoromethylornithine (DFMO) on Aβ42 aggregation and protein expression in DS fibroblasts. RESULTS:Amyloid-β42 increased polyamine levels via ornithine decarboxylase (ODC) activation in a dose-dependent manner. DFMO reduced Aβ42 aggregation, decreased amyloid precursor protein (APP) levels, and normalized proteins linked to AD pathology in DS fibroblasts. Polyamine levels were elevated in DS-AD hippocampal tissue, with colocalization of ODC and Aβ42 aggregates. CONCLUSION:These findings suggest that polyamine biosynthesis may exacerbate Aβ42 toxicity and APP expression, contributing to AD progression in DS. The ability of DFMO to reduce Aβ42 aggregation and restore protein homeostasis presents the polyamine pathway as a therapeutic target for DS-AD management.

Introduction: Intracerebral hemorrhage (ICH) has high morbidity and mortality without available targets for intervention. Polyamines are metabolites implicated in neurological diseases such as traumatic brain injury, Alzheimer’s Disease, and ischemic stroke. No studies have evaluated polyamines as they relate to ICH occurrence or outcomes. In this pilot study, we sought preliminary data on whether polyamines could be potential novel targets to improve outcomes after ICH. Methods: We analyzed plasma samples from 7 ICH cases and 10 control participants from the Genetics and Environmental Risk Factors for Stroke (GERFHS) IV study for polyamine measurements using Capillary Electrophoresis with Laser Induced Fluorescence Detection with the modality of Micellar Electrokinetic Chromatography. Plasma samples were deproteinized and derivatized with Fluorescein Isothiocyanate. Samples were spiked with standard solutions and compared with standard curves developed per each polyamine. We report median age and sex of the cohort. Peak spermine, spermidine and putrescine levels were compared using a student’s t-test. Results: In this pilot study of participants enrolled into GERFHS IV (median age 67 vs 61, cases vs controls respectively, 50% female) all three unacetylated polyamine levels were higher in cases. Although sample size is modest, there was a trend towards increased spermidine levels with higher mRS at 90 days (r 2 = 0.3342) (Figure 1). Conclusions: For the first time, we have shown that polyamines are elevated after ICH, and that higher polyamine levels may be associated with worse outcomes. This preliminary data supports further evaluation of polyamines as potential targets to improve outcomes after ICH in a larger cohort.

Calorie restriction (CR) extends lifespan and healthspan in diverse species. Comparing ad libitum-- and CRfed mice is challenging due to their significantly different feeding patterns, with CR-fed mice consuming their daily meal in 2 h and then subjecting themselves to a prolonged daily fast. Here, we examine how ad libitum- and CR-fed mice respond to tests performed at various times and fasting durations and find that the effects of CR-insulin sensitivity, circulating metabolite levels, and mechanistic target of rapamycin 1 (mTORC1) activity-result from the specific temporal conditions chosen, with CR-induced improvements in insulin sensitivity observed only after a prolonged fast, and the observed differences in mTORC1 activity between ad libitum- and CR-fed mice dependent upon both fasting duration and the specific tissue examined. Our results demonstrate that much of our understanding of the effects of CR are related to when, relative to feeding, we choose to examine the mice.

Parkinson's disease (PD) is a progressive neurodegenerative disorder for which there is no successful prevention or intervention. The pathological hallmark for PD involves the self-assembly of functional Alpha-Synuclein (αS) into non-functional amyloid structures. One of the potential therapeutic interventions against PD is the effective inhibition of αS aggregation. However, the bottleneck towards achieving this goal is the identification of αS domains/sequences that are essential for aggregation. Using a protein mimetic approach, we have identified αS sequences-based targets that are essential for aggregation and will have significant therapeutic implications. An extensive array of in vitro, ex vivo, and in vivo assays is utilized to validate αS sequences and their structural characteristics that are essential for aggregation and propagation of PD phenotypes. The study aids in developing significant mechanistic and therapeutic insights into various facets of αS aggregation, which will pave the way for effective treatments for PD.

Schizophrenia is a neurodevelopmental psychiatric disorder, encompassing genetic and environmental risk factors. For several decades, investigators have been implementing the use of lesions of the neonatal rodent hippocampus to model schizophrenia, resulting in a broad spectrum of adult schizophrenia-related behavioral changes. Despite the extensive use of these proposed animal models of schizophrenia, the mechanisms by which these lesions result in schizophrenia-like behavioral alterations remain unclear. Here we provide in vivo evidence that transient pharmacological inactivation of the hippocampus via tetrodotoxin microinjections or a genetic reduction in brain derived neurotrophic factor (BDNF) protein levels (BDNF+/- rats) lead to global DNA hypomethylation, disrupted maturation of the neuronal nucleus and aberrant acoustic startle response in the adult rat. The similarity between the effects of the two treatments strongly indicate that BDNF signaling is involved in effects obtained after the TTX microinjections. These findings may shed light on the cellular mechanisms underlying the phenotypical features of neonatal transient inhibition of the hippocampus as a preclinical model of schizophrenia and suggest that BDNF signaling represents a target pathway for development of novel treatment therapies.

Individuals with Down syndrome (DS) exhibit Alzheimer's disease (AD) pathology at a young age, including amyloid plaques and neurofibrillary tangles (NFTs). Tau pathology can spread via extracellular vesicles, such as exosomes. The cargo of neuron-derived small extracellular vesicles (NDEVs) from individuals with DS contains p-Tau at an early age. The goal of the study was to investigate whether NDEVs isolated from the blood of individuals with DS can spread Tau pathology in the brain of wildtype mice. We purified NDEVs from the plasma of patients with DS-AD and controls and injected small quantities using stereotaxic surgery into the dorsal hippocampus of adult wildtype mice. Seeding competent Tau conformers were amplified in vitro from DS-AD NDEVs but not NDEVs from controls. One month or 4 months post-injection, we examined Tau pathology in mouse brains. We found abundant p-Tau immunostaining in the hippocampus of the mice injected with DS-AD NDEVs compared to injections of age-matched control NDEVs. Double labeling with neuronal and glial markers showed that p-Tau staining was largely found in neurons and, to a lesser extent, in glial cells and that p-Tau immunostaining was spreading along the corpus callosum and the medio-lateral axis of the hippocampus. These studies demonstrate that NDEVs from DS-AD patients exhibit Tau seeding capacity and give rise to tangle-like intracellular inclusions.

An understanding of the immune mechanisms that lead to rejection versus tolerance of allogeneic pancreatic islet grafts is of paramount importance, as it facilitates the development of innovative methods to improve the transplant outcome. Here, we used our established intraocular islet transplant model to gain novel insight into changes in the local metabolome and proteome within the islet allograft's immediate microenvironment in association with immune-mediated rejection or tolerance. We performed integrated metabolomics and proteomics analyses in aqueous humor samples representative of the graft's microenvironment under each transplant outcome. The results showed that several free amino acids, small primary amines, and soluble proteins related to the Warburg effect were upregulated or downregulated in association with either outcome. In general, the observed shifts in the local metabolite and protein profiles in association with rejection were consistent with established pro-inflammatory metabolic pathways and those observed in association with tolerance were immune regulatory. Taken together, the current findings further support the potential of metabolic reprogramming of immune cells towards immune regulation through targeted pharmacological and dietary interventions against specific metabolic pathways that promote the Warburg effect to prevent the rejection of transplanted islets and promote their immune tolerance.

We have assessed the dependency of wind power resources in Western Europe on the atmospheric circulation as represented by a new set of 8 tailored weather regimes (WRs). For this purpose, we have derived wind capacity factors (CFs) from a meteorological reanalysis dataset and from high-resolution data simulated by the Weather Research and Forecasting (WRF) model. We first show that WRs capture effectively year-round onshore wind power production variability across Europe, especially over northwestern/central Europe and Iberia. Since the influence of the large-scale circulation on wind energy production is regionally dependent, we have then examined the high-resolution CF data interpolated to the location of more than 100 wind farms in two regions with different orography and climatological features, the United Kingdom and the Iberian Peninsula. The use of the monthly frequencies of occurrence of WRs as predictors in a multi-linear regression model allows explaining up to two thirds of the month-to-month CF variability for most seasons and sub-regions. These results outperform those previously reported based on Euro-Atlantic modes of atmospheric circulation, indicating that the use of WRs customized to the region of study is preferred to reproduce the evolution of wind energy resources. Finally, we have applied these WRs to understand the day-to-day evolution of specific episodes with anomalous regional wind power production. In particular, the wind energy deficit of summer 2018 in the United Kingdom and the surplus of March 2018 in Iberia stemmed from the combination of WRs associated with low and high CFs, respectively. These findings are relevant for the forecast of wind energy resources as the large-scale features of the atmospheric circulation captured by WRs can be modelled with considerably less uncertainty than wind speeds at wind farm sites.

Aging is the major risk factor for development of cognitive decline and neurodegenerative disease. The aging brain undergoes gradual neuroanatomical and neurochemical changes, including alterations in components of the endocannabinoid system. These changes impact brain functions controlling motoric, emotive, and cognitive activities. Some degree of age-related cognitive decline occurs independent of the presence of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. However, neurodegenerative diseases can also develop in younger individuals who exhibit what appears to be accelerated “aging” of selective populations of neurons. The discovery of the endogenous cannabinoid system is relatively recent and began with identification of receptors in brain that interacted and bound with the main psychoactive component of the phytocannabinoid delta-9-tetrahydrocannabinol (THC). At present, the various components of the endocannabinoid system (endogenous ligands, receptors, biosynthetic and degradative enzymes) have been characterized, and research in this field is rapidly growing. In this brief review, the changes in the endocannabinoid system that occur with aging and in several classical neurodegenerative diseases are discussed with a focus on the therapeutic potential of agents that interact with various components of the endocannabinoid system.

AbstractBackgroundThe dysfunctional accumulation of amyloid beta (Aβ) plaques in neuronal cells is widely regarded as a hallmark sign of Alzheimer’s disease (AD). However, the mechanisms by which Aβ causes the rampant apoptosis that leads to the characteristic memory loss and dementia observed in AD patients are much less understood. In this study, we investigated the regulatory relationship between Aβ42, a particularly toxic member of the Aβ peptide family, and polyamines (PA), a ubiquitous class of molecules associated with cell growth, proliferation, and immune response. Increasing evidence has suggested that the PA pathway is changed in AD. For example, increased levels of enzymes in the PA synthesis pathway and altered PA metabolomics have been found in the AD brain. Here, we sought to investigate the relationship between PA synthesis and disease pathogenesis, specifically Aβ aggregation and in turn, neuronal death.MethodHT22 hippocampal cells were transiently transfected with bicistronic plasmids allowing for expression of DsRed alone or co‐expression with Aβ42. We then examined the effects of Aβ42 on expression of the rate limiting enzyme for PA synthesis, ornithine decarboxylase (ODC) and in turn, PA levels. Irreversible ODC inhibitor, L‐difluoromethylornithine (DFMO) was used to examine effects on Aβ42 aggregation and neuronal apoptosis. Hippocampal tissue from human sporadic AD and age matched controls were also assessed for PA concentration and ODC expression.ResultsWe found that Aβ42 increased PA levels in a dose‐dependent fashion through enhanced expression of ODC in HT22 hippocampal cells. Treatment with DFMO significantly reduced this increase in PA as well as aggregation of Aβ42 and Aβ42‐induced apoptosis. Lastly, levels of spermidine and spermine as well as ODC expression were significantly increased in sporadic AD human hippocampal tissue in comparison to age‐matched controls.ConclusionThese data suggest that increased intracellular concentrations of PA are not only a response to Aβ42, but they also promote Aβ42 toxicity by enhancing aggregation. Secondarily, DFMO may be a novel therapeutic to mitigate Aβ42 toxicity and reduce amyloid plaque load in patients with AD.

The application of artificial intelligence (AI) and machine learning (ML) in biomedical research promises to unlock new information from the vast amounts of data being generated through the delivery of healthcare and the expanding high-throughput research applications. Such information can aid medical diagnoses and reveal various unique patterns of biochemical and immune features that can serve as early disease biomarkers. In this report, we demonstrate the feasibility of using an AI/ML approach in a relatively small dataset to discriminate among three categories of samples obtained from mice that either rejected or tolerated their pancreatic islet allografts following transplant in the anterior chamber of the eye, and from naïve controls. We created a locked software based on a support vector machine (SVM) technique for pattern recognition in electropherograms (EPGs) generated by micellar electrokinetic chromatography and laser induced fluorescence detection (MEKC-LIFD). Predictions were made based only on the aligned EPGs obtained in microliter-size aqueous humor samples representative of the immediate local microenvironment of the islet allografts. The analysis identified discriminative peaks in the EPGs of the three sample categories. Our classifier software was tested with targeted and untargeted peaks. Working with the patterns of untargeted peaks (i.e., based on the whole pattern of EPGs), it was able to achieve a 21 out of 22 positive classification score with a corresponding 95.45% prediction accuracy among the three sample categories, and 100% accuracy between the rejecting and tolerant recipients. These findings demonstrate the feasibility of AI/ML approaches to classify small numbers of samples and they warrant further studies to identify the analytes/biochemicals corresponding to discriminative features as potential biomarkers of islet allograft immune rejection and tolerance.

The pontine nucleus locus coeruleus (LC) is the primary source of noradrenergic (NE) projections to the brain and is important for working memory, attention, and cognitive flexibility. Individuals with Down syndrome (DS) develop Alzheimer's disease (AD) with high penetrance and often exhibit working memory deficits coupled with degeneration of LC-NE neurons early in the progression of AD pathology. Designer receptors exclusively activated by designer drugs (DREADDs) are chemogenetic tools that allow targeted manipulation of discrete neuronal populations in the brain without the confounds of off-target effects. We utilized male Ts65Dn mice (a mouse model for DS), and male normosomic (NS) controls to examine the effects of inhibitory DREADDs delivered via an AAV vector under translational control of the synthetic PRSx8, dopamine β hydroxylase (DβH) promoter. This chemogenetic tool allowed LC inhibition upon administration of the inert DREADD ligand, clozapine-N-oxide (CNO). DREADD-mediated LC inhibition impaired performance in a novel object recognition task and reversal learning in a spatial task. DREADD-mediated LC inhibition gave rise to an elevation of α-adrenoreceptors both in NS and in Ts65Dn mice. Further, microglial markers showed that the inhibitory DREADD stimulation led to increased microglial activation in the hippocampus in Ts65Dn but not in NS mice. These findings strongly suggest that LC signaling is important for intact memory and learning in Ts65Dn mice and disruption of these neurons leads to increased inflammation and dysregulation of adrenergic receptors.

Increased expression of the 3.1 isoform of the KCNH2 potassium channel has been associated with cognitive dysfunction and with schizophrenia, yet little is known about the underlying pathophysiological mechanisms. Here, by using in vivo wireless local field potential recordings during working memory processing, in vitro brain slice whole-cell patching recordings and in vivo stereotaxic hippocampal injection of AAV-encoded expression, we identified specific and delayed disruption of hippocampal-mPFC synaptic transmission and functional connectivity associated with reductions of SERPING1, CFH , and CD74 in the KCNH2-3.1 overexpression transgenic mice. The differentially expressed genes in mice are enriched in neurons and microglia, and reduced expression of these genes dysregulates the complement cascade, which has been previously linked to synaptic plasticity. We find that knockdown of these genes in primary neuronal–microglial cocultures from KCNH2-3.1 mice impairs synapse formation, and replenishing reduced CFH gene expression rescues KCNH2-3.1-induced impaired synaptogenesis. Translating to humans, we find analogous dysfunctional interactions between hippocampus and prefrontal cortex in coupling of the fMRI blood oxygen level-dependent (BOLD) signal during working memory in healthy subjects carrying alleles associated with increased KCNH2-3.1 expression in brain. Our data uncover a previously unrecognized role of the truncated KCNH2-3.1 potassium channel in mediating complement activation, which may explain its association with altered hippocampal–prefrontal connectivity and synaptic function. These results provide a potential molecular link between increased KCNH2-3.1 expression, synapse alterations, and hippocampal–prefrontal circuit abnormalities implicated in schizophrenia.

A highly sensitive method was developed to measure putrescine by micellar electrokinetic chromatography with laser induced fluorescence detection with excellent linearity in the 1 nM to 3 μM range. The technique was tested on a drop of blood from Parkinson's disease patients obtained by finger prick. The results showed a statistically significant increase of putrescine in the erythrocytes compared to controls and a non-significant increase in plasma. This high level of putrescine does not constitute by itself proof that putrescine and polyamines are directly related to Parkinson's disease. However, the present results and several others addressed in the discussion suggest that these compounds might be causally involved in the pathophysiology of Parkinson's disease. In addition, the analytical method reported here may help to find new biomarkers for many diseases including Parkinson's disease.

Numerous genetic and functional studies implicate variants of Neuregulin-1 (NRG1) and its neuronal receptor ErbB4 in schizophrenia and many of its endophenotypes. Although the neurophysiological and behavioral phenotypes of NRG1 mutant mice have been investigated extensively, practically nothing is known about the function of NRG2, the closest NRG1 homolog. We found that NRG2 expression in the adult rodent brain does not overlap with NRG1 and is more extensive than originally reported, including expression in the striatum and medial prefrontal cortex (mPFC), and therefore generated NRG2 knockout mice (KO) to study its function. NRG2 KOs have higher extracellular dopamine levels in the dorsal striatum but lower levels in the mPFC; a pattern with similarities to dopamine dysbalance in schizophrenia. Like ErbB4 KO mice, NRG2 KOs performed abnormally in a battery of behavioral tasks relevant to psychiatric disorders. NRG2 KOs exhibit hyperactivity in a novelty-induced open field, deficits in prepulse inhibition, hypersensitivity to amphetamine, antisocial behaviors, reduced anxiety-like behavior in the elevated plus maze and deficits in the T-maze alteration reward test—a task dependent on hippocampal and mPFC function. Acute administration of clozapine rapidly increased extracellular dopamine levels in the mPFC and improved alternation T-maze performance. Similar to mice treated chronically with N -methyl- d -aspartate receptor (NMDAR) antagonists, we demonstrate that NMDAR synaptic currents in NRG2 KOs are augmented at hippocampal glutamatergic synapses and are more sensitive to ifenprodil, indicating an increased contribution of GluN2B-containing NMDARs. Our findings reveal a novel role for NRG2 in the modulation of behaviors with relevance to psychiatric disorders.