Neuronal Remodeling Research Articles

CNSC-05. ELECTROPHYSIOLOGICAL PATTERNS OF GLIOMA-INDUCED NEURONAL NETWORK REMODELING ARE CONSERVED ACROSS TUMOR SUBTYPE

Abstract Recent evidence indicates that diffuse gliomas engage with neurons at the single-unit and circuit level through differing mechanisms. Certain malignant gliomas form glioma-neuron excitatory glutamatergic synapses and modulate neuron-neuron synapses through activity-dependent paracrine signaling, while others establish glioma-glioma connections via tumor microtubes. It is therefore possible that diffuse gliomas remodel neuronal circuits in a defined and predictable manner and demonstrate distinct electrophysiological profiles with prognostic and therapeutic significance. Here we apply machine learning principles in 140 patients across glioma subtypes to uncover unique electrophysiological features non-invasively via magnetoencephalography (discovery dataset) followed by feature validation using subdural electrocorticography (validation dataset). Following spatial-temporal registration, we fit an elastic net logistic regression classifier to distinguish between power spectra arising from glioma-remodeled cortex and within-subject control conditions. Model significance was determined non-parametrically by re-training each model 1,000 times with randomly permuted class labels and testing the true phi coefficient against the null distribution. In the discovery dataset, we were able to classify glioma infiltration based on tumor intrinsic neuronal activity (p < 0.05) in 127 patients (90.7%). We identified 30 electrophysiological features which revealed increased power in the delta range (1-4 Hz) and decreased power in the beta range (12-20 Hz) as a unique signature of glioma remodeling (p < 0.05) which was preserved in the validation dataset as well as across WHO 2021 diffuse glioma subtypes. In order to identify gene expression programs and signaling mechanisms that may contribute to glioma-induced remodeling but are potentially not identified in the current clinical classification scheme, we assessed targeted, next generation sequencing and DNA mutations as covariates, which again demonstrated the significance of the delta-beta spectral features. These data support converging mechanisms of glioma-induced neuronal network remodeling across tumor subtypes, setting the stage for novel therapies such as neuromodulation.

The microbiota promotes social behavior by modulating microglial remodeling of forebrain neurons.

Host-associated microbiotas guide the trajectory of developmental programs, and altered microbiota composition is linked to neurodevelopmental conditions such as autism spectrum disorder. Recent work suggests that microbiotas modulate behavioral phenotypes associated with these disorders. We discovered that the zebrafish microbiota is required for normal social behavior and reveal a molecular pathway linking the microbiota, microglial remodeling of neural circuits, and social behavior in this experimentally tractable model vertebrate. Examining neuronal correlates of behavior, we found that the microbiota restrains neurite complexity and targeting of forebrain neurons required for normal social behavior and is necessary for localization of forebrain microglia, brain-resident phagocytes that remodel neuronal arbors. The microbiota also influences microglial molecular functions, including promoting expression of the complement signaling pathway and the synaptic remodeling factor c1q. Several distinct bacterial taxa are individually sufficient for normal microglial and neuronal phenotypes, suggesting that host neuroimmune development is sensitive to a feature common among many bacteria. Our results demonstrate that the microbiota influences zebrafish social behavior by stimulating microglial remodeling of forebrain circuits during early neurodevelopment and suggest pathways for new interventions in multiple neurodevelopmental disorders.

Endovascular Stem Cell Therapy Promotes Neuronal Remodeling to Enhance Post Stroke Recovery by Alleviating Endoplasmic Reticulum Stress Modulated by BDNF Signaling.

The impact of increased BDNF expression in brain by endovascular delivered mesenchymal stem cells (MSCs) post stroke towards modulating endoplasmic reticulum (ER) stress mediated neuronal remodeling has not been directly studied. Therefore, the present study investigates ER stress mediated neuronal remodeling following IA MSCs infusion in rodent model of ischemic stroke. Ovariectomized Sprague Dawley rats were subjected to MCAO followed by 1 × 105 IA MSCs administration at 6h. Infarct and functional outcomes at different time points post-stroke were evaluated. Further, various genes and protein expression studies were performed to determine the underlying mechanisms of the effect of IA MSCs towards ER stress mediated neuronal remodeling. Post-strokeIA MSCs administration significantly increased BDNF expression anddecreased ER stress markersexpression at day 1 post-stroke. A gradual rise in the expression of growth associate protein-43 (GAP 43) and spinophilin were observed at 7, 14- and 28-days post-stroke indicating an increase in neuronal remodeling towards functional restoration. The results suggest that IA MSCs post-stroke can modulate neuronal remodeling by BDNF-mediated reduction in ER stress that contribute towards functional recovery.

Acute myocardial infarction induces remodeling of the murine superior cervical ganglia and the carotid body.

A role for cardiac sympathetic hyperinnervation in arrhythmogenesis after myocardial infarction (MI) has increasingly been recognized. In humans and mice, the heart receives cervical as well as thoracic sympathetic contributions. In mice, superior cervical ganglia (SCG) have been shown to contribute significantly to myocardial sympathetic innervation of the left ventricular anterior wall. Of interest, the SCG is situated adjacent to the carotid body (CB), a small organ involved in oxygen and metabolic sensing. We investigated the remodeling of murine SCG and CB over time after MI. Murine SCG were isolated from control mice, as well as 24 h, 3 days, 7 days and 6 weeks after MI. SCG and CBs were stained for the autonomic nervous system markers β3-tubulin, tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT), as well as for the neurotrophic factors brain derived neurotropic factor (BDNF), nerve growth factor (NGF) and their tyrosine receptor kinase (pan TRK). Results show that after MI a significant increase in neuron size occurs, especially in the region bordering the CB. Co-expression of TH and ChAT is observed in SCG neuronal cells, but not in the CB. After MI, a significant decrease in ChAT intensity occurs, which negatively correlated with the increased cell size. In addition, an increase of BDNF and NGF at protein and mRNA levels was observed in both the CB and SCG. This upregulation of neurotropic factors coincides with the upregulation of their receptor within the SCG. These findings were concomitant with an increase in GAP43 expression in the SCG, which is known to contribute to axonal outgrowth and elongation. In conclusion, neuronal remodeling toward an increased adrenergic phenotype occurs in the SCG, which is possibly mediated by the CB and might contribute to pathological hyperinnervation after MI.

Dendritic Branching of Retinal Ganglion Cells as a Biomarker of Glaucomatous Optic Neuropathy and Alzheimer’s Disease and a Target of Neuroprotective Therapy

Irreversible damage to the structure of axons and death of the retinal ganglion cell (RGC) soma in primary open-angle glaucoma (POAG) and Alzheimer’s disease (AD) develop against the background of the already existing clinical manifestation, which is preceded by a slow period of progressive loss of synapses and dendrites of the RGCs. Recent studies have shown that the integrity of the RGC’s dendritic branching can serve as both a target of neuroprotective therapy and a sensitive marker of retinal degeneration in AD and glaucoma. To develop methods of complex neuroprotective therapy, it is necessary to substantiate the targets and tactics of affecting the dendritic tree of the RGCs, the remodeling of which, according to modern concepts, can be closely and antagonistically related to the regeneration of the axon after its damage in trauma and neurodegenerative diseases. RGCs are highly capable of functional modification. Currently, it has been proven that the use of neuroprotective drugs and neurotrophins is promising for maintaining the adaptive plasticity of RGCs and restoring their synaptic contacts at the level of the retina and brain. Understanding the features of the adaptive plasticity of RGCs in AD and glaucoma will make it possible to use technologies to activate the internal potential of neuronal remodeling, including the modification of dendritic branching of RGCs and regeneration of their axons, in the preclinical stages of these diseases. Increasing knowledge about the sequence and mechanisms of early events in the retina’s inner plexiform layer will contribute to the development of targeted neuroprotective therapy and new technologies to detect early POAG, AD, and, possibly, other systemic and local neurodegenerative conditions.

COLOCALIZATION AND REMODELING OF HEART- AND LUNG-PROJECTING STELLATE GANGLION NEURONS IN BLEOMYCIN-INDUCED PULMONARY FIBROSIS

COLOCALIZATION AND REMODELING OF HEART- AND LUNG-PROJECTING STELLATE GANGLION NEURONS IN BLEOMYCIN-INDUCED PULMONARY FIBROSIS

Obese male Zucker rats exhibit dendritic remodeling in neurons of the hippocampal trisynaptic circuit as well as spatial memory deficits.

Obesity is characterized by excessive fat accumulation. The Zucker rat displays genetic obesity due to a mutation in the leptin receptor gene; this model is of great interest because of its similarity to human obesity. Brain regions may be affected by obesity, but detailed information is lacking. In the present study, we analyzed the morphology of neurons in the hippocampal trisynaptic circuit as well as the spatial memory of obese Zucker rats. We performed two experiments. Each experiment contained two experimental groups: the control group (male Long Evans rats) and the study group (obese male Zucker rats). We monitored the body weights of all rats over 4 weeks. In the first experiment, we analyzed the morphology of hippocampal neurons. Under anesthesia, we measured the abdominal and hip circumferences and collected at least 1ml of blood to assess serum glucose (GLU), triglyceride (TGC), and cholesterol (COL) concentrations. We perfused the brains of these rats with 0.9% saline solution, incubated the brains in Golgi-Cox solution, and subsequently evaluated the morphology of pyramidal neurons in the hippocampus (the CA1-CA3 regions) and the entorhinal cortex as well as the morphology of granule neurons in the dentate gyrus. In the second experiment, we assessed the spatial memory of animals with the Morris water maze. The Zucker rats had an obese phenotype, as indicated by their elevated body weight and increased abdominal and hip circumferences as well as elevated GLU, COL, and TGC concentrations. Analysis of neurons from the specified regions in obese male Zucker rats indicated reduced dendritic arborization and reduced dendritic spine density. In terms of spatial learning and memory, the obese Zucker rats exhibited intact spatial learning (i.e., of platform location) but deficits in spatial memory. These data provide evidence that obesity alters the morphology and function of hippocampal neurons.

Pathophysiological and Neuroplastic Changes in Postamputation and Neuropathic Pain: Review of the Literature.

Background:Despite advancements in surgical and rehabilitation strategies, extremity amputations are frequently associated with disability, phantom limb sensations, and chronic pain. Investigation into potential treatment modalities has focused on the pathophysiological changes in both the peripheral and central nervous systems to better understand the underlying mechanism in the development of chronic pain in persons with amputations.Methods:Presented in this article is a discussion outlining the physiological changes that occur in the peripheral and central nervous systems following amputation. In this review, the authors examine the molecular and neuroplastic changes occurring in the nervous system, as well as the state-of-the-art treatment to help reduce the development of postamputation pain.Results:This review summarizes the current literature regarding neurological changes following amputation. Development of both central sensitization and neuronal remodeling in the spinal cord and cerebral cortex allows for the development of neuropathic and phantom limb pain postamputation. Recently developed treatments targeting these pathophysiological changes have enabled a reduction in the severity of pain; however, complete resolution remains elusive.Conclusions:Changes in the peripheral and central nervous systems following amputation should not be viewed as separate pathologies, but rather two interdependent mechanisms that underlie the development of pathological pain. A better understanding of the physiological changes following amputation will allow for improvements in therapeutic treatments to minimize pathological pain caused by amputation.

Identification of hub genes in the subacute spinal cord injury in rats

BackgroundSpinal cord injury (SCI) is a common trauma in clinical practices. Subacute SCI is mainly characterized by neuronal apoptosis, axonal demyelination, Wallerian degeneration, axonal remodeling, and glial scar formation. It has been discovered in recent years that inflammatory responses are particularly important in subacute SCI. However, the mechanisms mediating inflammation are not completely clear.MethodsThe gene expression profiles of GSE20907, GSE45006, and GSE45550 were downloaded from the GEO database. The models of the three gene expression profiles were all for SCI to the thoracic segment of the rat. The differentially expressed genes (DEGs) and weighted correlation network analysis (WGCNA) were performed using R software, and functional enrichment analysis and protein–protein interaction (PPI) network were performed using Metascape. Module analysis was performed using Cytoscape. Finally, the relative mRNA expression level of central genes was verified by RT-PCR.ResultsA total of 206 candidate genes were identified, including 164 up-regulated genes and 42 down-regulated genes. The PPI network was evaluated, and the candidate genes enrichment results were mainly related to the production of tumor necrosis factors and innate immune regulatory response. Twelve core genes were identified, including 10 up-regulated genes and 2 down-regulated genes. Finally, seven hub genes with statistical significance in both the RT-PCR results and expression matrix were identified, namely Itgb1, Ptprc, Cd63, Lgals3, Vav1, Shc1, and Casp4. They are all related to the activation process of microglia.ConclusionIn this study, we identified the hub genes and signaling pathways involved in subacute SCI using bioinformatics methods, which may provide a molecular basis for the future treatment of SCI.

Genetic Mouse Models to Study Pancreatic Cancer-Induced Pain and Reduction in Well-Being.

In addition to the poor prognosis, excruciating abdominal pain is a major challenge in pancreatic cancer. Neurotropism appears to be the underlying mechanism leading to neuronal invasion. However, there is a lack of animal models suitable for translationally bridging in vitro findings with clinical trials. We characterized KPC (KrasG12D/+; Trp53R172H/+; P48-Cre) and KPPC (KrasG12D/+; Trp53R172H/R172H; P48-Cre) mice with genetically determined pancreatic ductal adenocarcinoma (PDAC) and compared them with an orthotopic pancreatic cancer mouse model, healthy littermates and human tissue. We analyzed behavioral correlates of cancer-associated pain and well-being, and studied neuronal remodeling and cytokine expression. Histologically, we found similarities between KPC and KPPC tissue with human samples. Compared to healthy littermates, we detect nerve fiber hypertrophy, which was not restricted to a certain fiber type. Interestingly, while KPPC mice showed significantly reduced well-being, KPC mice emerged to be better suited for studying long-lasting cancer pain that emerges over a slow course of tumor progression. To address the neuroinflammatory correlate of loss of well-being, we studied cytokine levels in KPPC mice and observed a significant upregulation of CXCL16, TNFRSF5, CCL24, CXCL1, CCL22, CLL20 and CX2CL1. In summary, we demonstrate that the KPC mouse model is best suited to studying cancer pain, whereas the KPPC model can be employed to study cancer-associated reduction in well-being.

Correlation of matrix metalloproteinase 3 and matrix metalloproteinase 9 levels with non-motor symptoms in patients with Parkinson's disease.

ObjectiveMatrix metalloproteinases (MMPs) are essential for tissue formation, neuronal network remodeling, and blood–brain barrier integrity. MMPs have been widely studied in acute brain diseases. However, the relationship with Parkinson’s disease (PD) remains unclear. The purpose of this study was to evaluate the serum MMP3 and MMP9 levels of PD patients and analyze their correlation with non-motor symptoms.MethodsIn this cross-sectional study, we recruited 73 patients with idiopathic PD and 64 healthy volunteers. Serum MMP3 and MMP9 levels were measured by enzyme-linked immunosorbent assay (ELISA). Patients with PD were assessed for non-motor symptoms using the Non-motor Symptoms Scale (NMSS) and Parkinson’s disease sleep scale (PDSS) and Mini Mental State Examination (MMSE).ResultsSerum MMP3 levels were significantly decreased in PD patients, predominantly those with early-stage PD, compared with controls [12.56 (9.30, 17.44) vs. 15.37 (11.33, 24.41) ng/ml; P = 0.004], and the serum MMP9 levels of PD patients were significantly higher than those of healthy controls [522 (419, 729) vs. 329 (229, 473) ng/ml; P < 0.001]. MMP3 levels were positively correlated with the NMSS total score (r = 0.271, P = 0.020) and the single-item scores for item six, assessing the gastrointestinal tract (r = 0.333, P = 0.004), and there was an inverse correlation between serum MMP3 levels and PDSS score (r = –0.246, P = 0.036); meanwhile, MMP9 levels were positively correlated with the NMSS total score (r = 0.234, P = 0.047), and higher serum MMP9 levels were detected in the cognitive dysfunction subgroup than in the cognitively intact subgroup [658 (504, 877) vs. 502 (397, 608) ng/ml, P = 0.008].ConclusionThe serum MMP3 level of PD patients (especially early-stage patients) was significantly lower than that of the healthy control group, and the MMP9 level was significantly higher than that of the healthy control group. MMP3 and MMP9 levels correlate with sleep disturbance and cognitive function in PD patients, respectively.

FAK-Mediated Signaling Controls Amyloid Beta Overload, Learning and Memory Deficits in a Mouse Model of Alzheimer's Disease.

The non-receptor focal adhesion kinase (FAK) is highly expressed in the central nervous system during development, where it regulates neurite outgrowth and axon guidance, but its role in the adult healthy and diseased brain, specifically in Alzheimer’s disease (AD), is largely unknown. Using the 3xTg-AD mouse model, which carries three mutations associated with familial Alzheimer’s disease (APP KM670/671NL Swedish, PSEN1 M146V, MAPT P301L) and develops age-related progressive neuropathology including amyloid plaques and Tau tangles, we describe here, for the first time, the in vivo role of FAK in AD pathology. Our data demonstrate that while site-specific knockdown in the hippocampi of 3xTg-AD mice has no effect on learning and memory, hippocampal overexpression of the protein leads to a significant decrease in learning and memory capabilities, which is accompanied by a significant increase in amyloid β (Aβ) load. Furthermore, neuronal morphology is altered following hippocampal overexpression of FAK in these mice. High-throughput proteomics analysis of total and phosphorylated proteins in the hippocampi of FAK overexpressing mice indicates that FAK controls AD-like phenotypes by inhibiting cytoskeletal remodeling in neurons which results in morphological changes, by increasing Tau hyperphosphorylation, and by blocking astrocyte differentiation. FAK activates cell cycle re-entry and consequent cell death while downregulating insulin signaling, thereby increasing insulin resistance and leading to oxidative stress. Our data provide an overview of the signaling networks by which FAK regulates AD pathology and identify FAK as a novel therapeutic target for treating AD.

Uwhangchungsimwon Inhibits Oxygen Glucose Deprivation/Re-Oxygenation-Induced Cell Death through Neuronal VEGF and IGF-1 Receptor Signaling and Synaptic Remodeling in Cortical Neurons.

Uwhangchungsimwon (UCW), a multi-component herbal product, has long been used to treat vascular diseases such as headache, dizziness, high blood pressure, and stroke. Though the prophylactic actions of UCW are well known, insufficient experimental evidence exists on its effectiveness against stroke. Here, we investigated the mechanism underlying the efficacy of UCW in oxygen glucose deprivation/re-oxygenation (OGD/R)-injury to the primary cortical neurons using an in vitro ischemia model. Neurons secrete vascular endothelial growth factor (VEGF), which acts as a neurotrophic factor in response to an ischemic injury. VEGF modulates neuroprotection and axonal outgrowth by activating the VEGF receptors and plays a critical role in vascular diseases. In this study, cortical neurons were pretreated with UCW (2, 10, and 50 µg/mL) for 48 h, incubated in oxygen-glucose-deprived conditions for 2 h, and further reoxygenated for 24 h. UCW effectively protected neurons from OGD/R-induced degeneration and cell death. Moreover, the role of UCW in sustaining protection against OGD/R injury is associated with activation of VEGF-VEGFR and insulin-like growth factor 1 receptor expression. Therefore, UCW is a potential herbal supplement for the prevention of hypoxic-ischemic neuronal injury as it may occur after stroke.

Impact of sleep disorders and disease duration on neurotrophins levels in cocaine use disorder

IntroductionBrain-derived neurotrophic factor (BDNF) and its precursor proBDNF contribute to brain plasticity and neuronal remodeling. Recently, the ratio between proBDNF and BDNF (RpB) has been proposed as a possible marker in major psychiatric disorders. Convergent lines of evidence suggest neurotrophins alterations could be involved into the pathophysiology of Cocaine Use Disorder (CUD) and insomnia. The aims of the present study are to evaluate the correlations between neurotrophins levels, insomnia and clinical features among CUD patients. Materials and methodsSubjects with a moderate to severe CUD were recruited. ProBDNF, BDNF and consequently RpB values were analyzed using ELISA technique. Insomnia severity index (ISI) scale was used to assess the severity of insomnia. Sociodemographic characteristics and CUD habits (e.g., years of cocaine use) were also collected. ResultsTwenty-four subjects (mean age 39.3 ± 6.7 years) were recruited. Correlation analysis showed that lower values of RpB were associated with higher ISI score (r = −0.469; p = 0.021), longer history of cocaine use (r = −0.584, p = 0.022) and higher amount of cocaine used (r = −0.655, p = 0.004). DiscussionThese preliminary findings may offer a novel insight on neurobiological alterations sustaining cocaine use. Lower RpB, as observed both in high insomnia levels and in chronic cocaine use, could induce a neuroprotective state as a synaptic homeostatic response to chronic damage. These findings also highlight the important role of neurotrophins balance on neurobiological alterations induced by cocaine misuse and insomnia, suggesting that RpB could be considered as a marker of neurotrophic and metabolic state of neural tissue.

Torpor Does Not Influence Spatial Memory in Hibernating Golden-Mantled Ground Squirrels (Spermophilus [Callospermophilus] lateralis).

AbstractMammalian hibernation in ground squirrels is characterized by periods of torpor wherein body temperature approaches ambient temperature and metabolism is reduced to as low as 1/100th of active rates. It is unclear how hibernation affects long-term spatial memory, as tremendous remodeling of neurons is associated with torpor use. Given the suspected links between remodeling and memory formation and retention, we examined long-term spatial memory retention throughout a hibernation season. Animals were trained on a Barnes maze before entering torpor. Animals were tested for memory retention once a month throughout a hibernation season. Results indicate marked variation between individuals. Some squirrels retained memory across multiple torpor bouts, while other squirrels did not. No relationship was found between the number of torpor bouts, duration of bouts, or time spent torpid on long-term memory retention. However, that some squirrels successfully retain memory suggests that the profound remodeling of dendritic spines during torpor does not always lead to memory loss.

Perirenal adipose afferent nerves sustain pathological high blood pressure in rats

Hypertension is a pathological condition of persistent high blood pressure (BP) of which the underlying neural mechanisms remain obscure. Here, we show that the afferent nerves in perirenal adipose tissue (PRAT) contribute to maintain pathological high BP, without affecting physiological BP. Bilateral PRAT ablation or denervation leads to a long-term reduction of high BP in spontaneous hypertensive rats (SHR), but has no effect on normal BP in control rats. Further, gain- and loss-of-function and neuron transcriptomics studies show that augmented activities and remodeling of L1-L2 dorsal root ganglia neurons are responsible for hypertension in SHR. Moreover, we went on to show that calcitonin gene-related peptide (CGRP) is a key endogenous suppressor of hypertension that is sequestered by pro-hypertensive PRAT in SHRs. Taken together, we identify PRAT afferent nerves as a pro-hypertensive node that sustains high BP via suppressing CGRP, thereby providing a therapeutic target to tackle primary hypertension.

Protective effects of phosphodiesterase 2 inhibitor against Aβ1-42 induced neuronal toxicity

Our previous study suggested that inhibition of Phosphodiesterase 2 ameliorates memory loss upon exposure to oxidative stress. While whether memory enhancing effects of PDE2 inhibition on Alzheimer's disease mouse model are involved in antioxidant defense and neuronal remodeling, are largely unexplored. The present study addressed whether and how PDE2 inhibitor Bay 60–7550 rescued Aβ oligomers (Aβo)-induced neuronal damage and memory impairment. The results suggested that exposure of primary cortical neurons to Aβo induced neuronal cells damage and increased PDE2 expression, which were paralleled to an increase in the oxidative parameter malondialdehyde (MDA) level and cellular apoptosis. However, this Aβo-induced oxidative damage was blocked by pre-treatment with protein kinase A or G (PKA or PKG) inhibitor, suggesting the involvement of cAMP/cGMP signaling. Moreover, microinjection of Aβo into the prefrontal cortex of mice increased the MDA level; while Bay 60–7550 reversed this effect and increased antioxidant and anti-apoptotic factors, i.e. increased trolox-equivalent-antioxidant capacity and Bcl-2/Bax ratio. Bay 60–7550 also rescued Aβo-induced synaptic atrophy and memory deficits, as evidenced by the increased synaptic proteins' levels and spine density in the prefrontal cortex, and improved cognitive behaviors by decreased working memory errors in the eight-arm maze and increased discrimination index in the novel object recognition test. These findings suggest that inhibition of PDE2 contributes to antioxidant defense and neuronal remodeling by regulation of cAMP/cGMP signaling, which provide a theoretical basis for the future use of PDE2 inhibitors as the anti-AD drugs.

Spatiotemporal Control of Neuronal Remodeling by Cell Adhesion Molecules: Insights From Drosophila.

Developmental neuronal remodeling is required for shaping the precise connectivity of the mature nervous system. Remodeling involves pruning of exuberant neural connections, often followed by regrowth of adult-specific ones, as a strategy to refine neural circuits. Errors in remodeling are associated with neurodevelopmental disorders such as schizophrenia and autism. Despite its fundamental nature, our understanding of the mechanisms governing neuronal remodeling is far from complete. Specifically, how precise spatiotemporal control of remodeling and rewiring is achieved is largely unknown. In recent years, cell adhesion molecules (CAMs), and other cell surface and secreted proteins of various families, have been implicated in processes of neurite pruning and wiring specificity during circuit reassembly. Here, we review some of the known as well as speculated roles of CAMs in these processes, highlighting recent advances in uncovering spatiotemporal aspects of regulation. Our focus is on the fruit fly Drosophila, which is emerging as a powerful model in the field, due to the extensive, well-characterized and stereotypic remodeling events occurring throughout its nervous system during metamorphosis, combined with the wide and constantly growing toolkit to identify CAM binding and resulting cellular interactions in vivo. We believe that its many advantages pose Drosophila as a leading candidate for future breakthroughs in the field of neuronal remodeling in general, and spatiotemporal control by CAMs specifically.

Nearest Neighbor Density Analysis of the Stellate Ganglia

IntroductionThe so‐called heart‐brain axis is the neurological and physiological connection between the autonomic systems of both organs. The stellate ganglia and superior cervical ganglia are the location of the sympathetic neuronal cells that innervate the vasculature of the heart and brain, respectively. The paravertebral chain connects the ganglia on either side of the neck. Myocardial infarction is thought to cause remodeling of the sympathetic neurons in the stellate ganglia. In a recent qualitative study, the stellate ganglia were shown to remodel with regard to cell body number, size, density, and clustering in the presence of various cardiac diseases. We developed a tool to automatically quantify the nearest neighbor density of neurons weighted by size in pathology specimens of the stellate ganglia. This is the first step to quantifying sympathetic nervous system changes in the heart‐brain axis of cardiovascular pathology.MethodsBiopsies of the stellate ganglia were collected bilaterally from an opportunity sample of 17 willed body donors (34 total specimens) with and without histories of self‐reported myocardial infarction (MI) and/or cerebrovascular accident (CVA). The ganglia were stained with luxol fast blue and cresyl violet which allowed for histological analysis of local neurons. Images of the ganglia at its middle coronal slice after staining were processed using multiple libraries in python, primarily PIL and OpenCV. The images first underwent multiple filters: a high contrast filter and a smoothing filter. After this filter, the image passed through a color threshold that obtained the location of each neuron; the locations of each neuron were used to make a binary image. The binary image was passed through various parameters such as neuron area, radius of the minimum enclosing circle, and a ratio of the area of the neuron and area of the minimum enclosing circle. A heatmap was generated from this last image through a convolution calculation that takes into account the location of the neuron, size, and proximity of surrounding neurons‐ all variables that are needed to calculate nearest neighbor density. Quantitative and qualitative measurements are generated from this: a graphical map of high and low density areas and number of neurons per given threshold of density.ResultsA pipeline was created that generates heatmaps of the nearest neighbor density based on the location and size of neurons on the stellate ganglia. Quantitative data is also measured based on how many neurons are located in varying levels of density structures.ConclusionsHeatmaps of the nearest neighbor density and size of the neurons potentially show signs of cardiac diseases‐ regions of high density or patterns of where highly dense regions are located are indicators. Developments within computation pathology is an easily accessible and pioneering way for new technological innovation.

Effects of Senescent Human Endothelial Cells on Neuronal Viability and Neurite Outgrowth Are Not IL‐8‐ or Serpin E1‐Dependent

It is estimated that more than 50% of adults over 80 will develop dementia, including Alzheimer’s disease (AD), and the primary risk factor for dementia is aging. Aging provides the substrate for disease through increased inflammation and cellular dysfunction, which in turn sets the stage for neurodegenerative disease. In a previous study we validated replicative senescence, a model of cell senescence that permits the study of cells as they progress to senescence, in human coronary artery endothelial cells (HCAEC). Here, we tested the hypothesis that senescent endothelial cells, which accumulate with aging and release senescence‐associated secretory phenotype (SASP) and extracellular vesicles, create a pro‐inflammatory environment that adversely affects the viability and morphology of neurons, which are endpoints implicated in AD. We categorized the phenotypes of HCAEC by passage number and identified them as EP‐ early passage (non‐senescent), ES‐ early senescence and LS‐ late senescence. HCAEC at these varying stages of senescence were co‐cultured with LUHMES cells, a human neuronal cell line. Co‐culturing HCAEC LS with LUHMES significantly decreased LUHMES viability, while co‐culturing HCAEC ES with LUHMES decreased the number of neurites extended by LUHMES in 24h and decreased the length of LUHMES’ neurites in 48h, when compared to LUHMES grown in the absence of HCAEC for the same period of time. HCAEC EP or LS co‐cultured with LUHMES did not affect the number or length of the LUHMES’ neurites, when compared to LUHMES grown in the absence of HCAEC. Using a cytokine array containing probes for 105 analytes, we detected 17 inflammatory mediators released by the co‐cultures of HCAEC (EP, ES and LS) with LUHMES. Of these 17 mediators, 14 were also found at supernatants of HCAEC (EP, ES and LS) grown in the absence of LUHMES, and none of the analytes were detected in supernatants from LUHMES grown in the absence of HCAEC. Statistical analysis of the intensity of the positive reaction for inflammatory mediators in the array was run for all the 17 positive analytes, and only IL‐8 and Serpin E1 release into the supernatants of the co‐cultures were significantly increased in co‐cultures of LUHMES and senescent HCAEC (ES or LS), when compared to the levels of the same mediators released by co‐cultures of LUHMES and EP HCAEC. However, exposing LUHMES to IL‐8 and Serpin E1, in the absence of HCAEC, did not affect LUHMES viability, the number or length of LUHMES’ neurites or LUHMES’ NF‐kB activation. The results from the LUHMES and HCAEC co‐cultures study supports a role for aging endothelial cells in the toxicity and morphological remodeling of the surrounding neurons, which may contribute to the development and progression of neurodegenerative diseases. However, our data exclude IL‐8 and Serpin E1 as direct independent mediators of senescent HCAEC on neuronal cytotoxicity and neurite remodeling.