Biology subjects

Carey, A.

Publications and source records attributed to Carey, A..

11 recordsLinked to original sources

bioRxiv2026

Carbonic anhydrase inhibition rescues heart function in the Tg2576 Alzheimer's mouse model by ameliorating cardiac amyloid-β pathology and neurotrophic signaling impairment.

FDA-approved carbonic anhydrase inhibitors (CAIs) have shown robust efficacy in reducing amyloid- beta pathology, neurodegeneration, and cerebrovascular dysfunction in Alzheimer disease (AD) and cerebral amyloid angiopathy (CAA) models, highlighting carbonic anhydrases (CAs) as a promising, previously untapped therapeutic target for AD and the vascular contribution to dementia. We have recently shown that amyloid- beta aggregates disrupt neuro-signaling and deplete neurotrophic factors (particularly BDNF) in the heart of AD mouse models and human subjects. In this study, we present the first in-depth examination of CAI therapy (acetazolamide, ATZ) in Tg2576 mice, a well-established model of AD and CAA. We confirm that progressive cardiac fibrosis and amyloid- beta deposition in 13-month-old mice severely impair the cardiac neuro-signaling system, marked by a drastic decrease in BDNF and reductions in adrenergic fibers and regenerating nerve endings (TH and GAP-43 markers), leading to significant declines in ejection fraction and fractional shortening compared to age-matched WT littermates. Critically, this study demonstrates that long-term ATZ treatment in Tg2576 mice significantly reduces cardiac amyloid- beta burden, prevents adverse neuro-signaling remodeling, and restores heart physiological function, as assessed via speckle tracking strain echocardiography. These in vivo findings were corroborated in human cardiomyocytes, in which CA inhibition reduced human amyloid- beta40 oligomer-dependent disruption of CREB signaling, thus preserving BDNF expression. Together, these results reveal a previously unrecognized cardio-neuroprotective role for CAIs in preventing amyloid- beta-induced cardiovascular remodeling and neuro-signaling disruption in the Tg2576-AD model. Given the established benefits of CAIs on cerebrovascular function and cognition, our findings further support advancing repurposing efforts into clinical trials. CAIs such as ATZ could offer a dual-action therapy approach, addressing both the central nervous system and cardiac pathologies associated with AD and, potentially, the systemic effects of amyloidosis.

cell biology↗

bioRxiv2024

GDF3 promotes adipose tissue macrophage-mediated inflammation via altered chromatin accessibility during aging

Age-related susceptibility to sepsis and endotoxemia is poorly defined, although hyperactivation of the immune system and the expansion of the visceral adipose as an immunological reservoir are underlying features. Macrophages from older organisms exhibit substantial changes, including chronic NLRP3 inflammasome activation, genomic remodeling and a dysfunctional, amplified inflammatory response upon new exposure to pathogen. However, the mechanisms by which old macrophages maintain their inflammatory phenotype during endotoxemia remains elusive. We previously identified Gdf3, a TGF{beta} superfamily cytokine, as a top-regulated gene by age and the NLRP3 inflammasome in adipose tissue macrophages (ATMs). Here, we demonstrate that endotoxemia increases inflammatory (CD11c+) ATMs in a Gdf3- dependent manner in old mice. Lifelong systemic or myeloid-specific deletion of Gdf3 leads to reduced endotoxemia- induced inflammation, with decreased CD11c+ ATMs and inflammatory cytokines, and protection from hypothermia. Moreover, acute blockade of Gdf3 using JQ1, a BRD4 inhibitor, phenocopies old mice with lifelong Gdf3-deficiency. We show that GDF3 promotes the inflammatory phenotype in ATMs by phosphorylating SMAD2/3. Mechanistically, the differential chromatin landscape of ATMs from old mice with or without myeloid-driven Gdf3 indicates that GDF3- SMAD2/3 signaling axis shifts the chromatin accessibility of ATMs towards an inflammatory state during aging. Furthermore, pharmaceutical inhibition of SMAD3 with a specific inhibitor of SMAD3 (SIS3) mimics Gdf3 deletion. SIS3 reduces endotoxemia-mediated inflammation with fewer CD11c+ ATMs and less severe hypothermia in old, but not young mice, as well as reduced mortality. In human adipose tissue, age positively correlates with GDF3 level, while inflammation correlates with pSMAD2/3 level. Overall, these results highlight the importance of GDF3-SMAD2/3 axis in driving inflammation in older organisms and identify this signaling axis as a promising therapeutic target for mitigating endotoxemia-related inflammation in the aged.

immunology↗

bioRxiv2024

Ultra-efficient, unified discovery from microbial sequencing with SPLASH and precise statistical assembly

Bacteria comprise > 12% of Earths biomass and profoundly impact human and planetary health.1 Many key biological functions of microbes, and functions differentiating strains, are conferred or modified by genome plasticity including mobilization of genetic elements, phage integration, and CRISPR arrays. Characterizing each of these processes is time-consuming and requires custom bioinformatic workflows ill-suited to enable discovery of new sources of genetic diversity or to uncover which elements are active. Further, strain typing of bacterial species and approaches to discriminate sub-populations remain time-consuming and resource intensive. Here, we show that SPLASH, our published approach for reference-free discovery and analysis directly from raw reads, and an improved statistical assembly algorithm, compactors, unify diverse tasks in microbial sequence analysis: discovering new mobile elements and CRISPR arrays missing from any reference, and generating rapid, metadata-free strain typing of diverse bacteria. SPLASH and compactors together constitute a new general discovery tool for biological discovery in the microbial world.

bioinformatics↗

bioRxiv2023

Amyloid β induces cardiac dysfunction and neuro-signaling impairment in the heart of an Alzheimer's disease model

While a link between cardiovascular risk factors and increased Alzheimers disease (AD) risk has been reported, it remains unclear whether AD pathology has a direct effect on cardiac function and myocardial innervation. AD and amyloidosis are known to impair neuronal function and affect brain neurotrophic factors (NGF and BDNF) expression. Amyloid aggregates and neuro-signaling impairments may also expose AD patients to peripheral nervous system deficits, promoting cardiac disorders. Here, we characterize cardiac physiology, amyloid pathology, neurotrophic factors loss, and the impoverishment of cardiac neuronal fibers in Tg2576-AD mice hearts, human cardiomyocytes in culture, and human AD post-mortem left ventricular (LV) heart tissue. We reveal that Tg2576 animals exhibit increased myocardial fibrosis, amyloid {beta} (A{beta}) deposition, and brain/heart-axis neurotrophic deficiencies, resulting in myocardial denervation and cardiac dysfunction. A{beta} oligomers reduce BDNF expression in both human immortalized and iPSC-derived cardiomyocytes, by disrupting TrkB/CREB signaling. Analysis of human LV AD post-mortem tissue confirmed cell and animal results. Our findings elucidate a previously unknown mechanism of A{beta}-induced cardiac neurotrophic signaling dysregulation, underscoring the relevance of heart degeneration in AD. Translational PerspectiveThis research identified cardiac amyloid pathology, neurotrophic factor depletion, and reduced myocardial nerve function in a transgenic model of cerebral amyloidosis (Tg2576) and in human AD heart tissue. These findings carry significant diagnostic and therapeutic implications, emphasizing the role of neuro-signaling disruption in cardiac physiology impairment linked to AD. Our study advocates for considering cardiac complications in AD management and paves the way for future precision medicine approaches to enhance systemic clinical strategies for treating AD, proposing the cardiac neurotrophic signaling pathway as a potential therapeutic target.

molecular biology↗

bioRxiv2023

Age-related increases in fibroblasts-secreted IGFBP2 increase melanoma cell invasion and lipid synthesis.

Aged melanoma patients (>65 years old) have more aggressive disease relative to young patients (<55 years old) for reasons that are not completely understood. Analysis of the young and aged secretome from human dermal fibroblasts identified >5-fold levels of insulin-like growth factor binding protein 2 (IGFBP2) in the aged fibroblast secretome. IGFBP2 functionally triggers upregulation of the PI3K-dependent fatty acid biosynthesis program in melanoma cells through increases in FASN. Melanoma cells co-cultured with aged dermal fibroblasts have higher levels of lipids relative to young dermal fibroblasts, which can be lowered by silencing IGFBP2 expression in fibroblasts, prior to treating with conditioned media. Conversely, ectopically treating melanoma cells with recombinant IGFBP2 in the presence of conditioned media from young fibroblasts, promoted lipid synthesis and accumulation in the melanoma cells. Neutralizing IGFBP2 in vitro reduces migration and invasion in melanoma cells, and in vivo studies demonstrate that neutralizing IGFBP2 in syngeneic aged mice, ablates tumor growth as well as metastasis. Conversely, ectopic treatment of young mice with IGFBP2 in young mice increases tumor growth and metastasis. Our data reveal that aged dermal fibroblasts increase melanoma cell aggressiveness through increased secretion of IGFBP2, stressing the importance of considering age when designing studies and treatment. SignificanceThe aged microenvironment drives metastasis in melanoma cells. This study reports that IGFBP2 secretion by aged fibroblasts induces FASN in melanoma cells and drives metastasis. Neutralizing IGFBP2 decreases melanoma tumor growth and metastasis.

cancer biology↗

bioRxiv2023

Perirhinal Cortex Learns A Predictive Map of The Task Environment

Goal-directed tasks involve acquiring an internal model, known as a predictive map, of relevant stimuli and associated outcomes to guide behavior. Here, we identified neural signatures of a predictive map of task behavior in perirhinal cortex (Prh). Mice learned to perform a tactile working memory task by classifying sequential whisker stimuli over multiple training stages. Chemogenetic inactivation demonstrated that Prh is involved in task learning. Chronic two-photon calcium imaging, population analysis, and computational modeling revealed that Prh encodes stimulus features as sensory prediction errors. Prh forms stable stimulus-outcome associations that expand in a retrospective manner and generalize as animals learn new contingencies. Stimulus-outcome associations are linked to prospective network activity encoding possible expected outcomes. This link is mediated by cholinergic signaling to guide task performance, demonstrated by acetylcholine imaging and perturbation. We propose that Prh combines error-driven and map-like properties to acquire a predictive map of learned task behavior.

neuroscience↗

bioRxiv2023

Neural correlates of face perception modeled with a convolutional recurrent neural network

Event-related potential (ERP) sensitivity to faces is predominantly characterized by an N170 peak that has greater amplitude and shorter latency when elicited by human faces than images of other objects. We developed a computational model of visual ERP generation to study this phenomenon which consisted of a convolutional neural network (CNN) connected to a recurrent neural network (RNN). We used open-access data to develop the model, generated synthetic images for simulating experiments, then collected additional data to validate predictions of these simulations. For modeling, visual stimuli presented during ERP experiments were represented as sequences of images (time x pixels). These were provided as inputs to the model. The CNN transformed these inputs into sequences of vectors that were passed to the RNN. The ERP waveforms evoked by visual stimuli were provided to the RNN as labels for supervised learning. The whole model was trained end-to-end using data from the open-access dataset to reproduce ERP waveforms evoked by visual events. Cross-validation model outputs strongly correlated with open-access (r = 0.98) and validation study data (r = 0.78). Open-access and validation study data correlated similarly (r = 0.81). Some aspects of model behavior were consistent with neural recordings while others were not, suggesting promising albeit limited capacity for modeling the neurophysiology of face-sensitive ERP generation.

neuroscience↗

bioRxiv2021

Monash DaCRA fPET-fMRI: A DAtaset for Comparison of Radiotracer Administration for high temporal resolution functional FDG-PET

Background Functional [18F]-fluorodeoxyglucose positron emission tomography (FDG-fPET) is a new approach for measuring glucose uptake in the human brain. The goal of FDG-fPET is to maintain a constant plasma supply of radioactive FDG in order to track, with high temporal resolution, the dynamic uptake of glucose during neuronal activity that occurs in response to a task or at rest. FDG-fPET has most often been applied in simultaneous BOLD-fMRI/FDG-fPET (blood oxygenation level dependent functional MRI fluorodeoxyglucose functional positron emission tomography) imaging. BOLD-fMRI/FDG-fPET provides the capability to image the two primary sources of energetic dynamics in the brain, the cerebrovascular haemodynamic response and cerebral glucose uptake. FindingsIn this Data Note, we describe an open access dataset, Monash DaCRA fPET-fMRI, which contrasts three radiotracer administration protocols for FDG-fPET: bolus, constant infusion, and hybrid bolus/infusion. Participants (n=5 in each group) were randomly assigned to each radiotracer administration protocol and underwent simultaneous BOLD-fMRI/FDG-fPET scanning while viewing a flickering checkerboard. The Bolus group received the full FDG dose in a standard bolus administration; the Infusion group received the full FDG dose as a slow infusion over the duration of the scan, and the Bolus-Infusion group received 50% of the FDG dose as bolus and 50% as constant infusion. We validate the dataset by contrasting plasma radioactivity, grey matter mean uptake, and task-related activity in the visual cortex. ConclusionsThe Monash DaCRA fPET-fMRI dataset provides significant re-use value for researchers interested in the comparison of signal dynamics in fPET, and its relationship with fMRI task-evoked activity.

neuroscience↗

bioRxiv2020

CUB and Sushi Multiple Domains 1 (CSMD1) opposes the complement cascade in neural tissues

Schizophrenia risk is associated with increased gene copy number and brain expression of complement component 4 (C4). Because the complement system facilitates synaptic pruning, the C4 association has renewed interest in a hypothesis that excessive pruning contributes to schizophrenia pathogenesis. However, little is known about complement regulation in neural tissues or whether such regulation could be relevant to psychiatric illness. Intriguingly, common variation within CSMD1, which encodes a putative complement inhibitor, has consistently associated with schizophrenia at genome-wide significance. We found that Csmd1 is predominantly expressed in the brain by neurons, and is enriched at synapses; that human stem cell-derived neurons lacking CSMD1 are more vulnerable to complement deposition; and that mice lacking Csmd1 have increased brain complement activity, fewer synapses, aberrant complement-dependent development of a neural circuit, and synaptic elements that are preferentially engulfed by cultured microglia. These data suggest that CSMD1 opposes the complement cascade in neural tissues. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=168 SRC="FIGDIR/small/291427v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@172c857org.highwire.dtl.DTLVardef@bee84corg.highwire.dtl.DTLVardef@184da10org.highwire.dtl.DTLVardef@10867c8_HPS_FORMAT_FIGEXP M_FIG Graphic Abstract.Our findings support a model in which CSMD1 opposes actions of the complement cascade in neural tissues (top left). We investigated two models in which Csmd1 was genetically ablated: human cortical neurons derived from embryonic stem cells, and a back-crossed C57bl6-Tac mouse line (top right). Csmd1 is normally expressed by neurons and present at synapses where it can protect them from complement (bottom left); in the absence of Csmd1 (bottom right), we find more deposition of complement (on cultured human cortical neurons and in the mouse visual system), reduced numbers of synapses (in the mouse visual system), and synaptic fractions that are more readily engulfed by microglia (ex vivo). Created with BioRender.com. C_FIG

neuroscience↗

bioRxiv2020

Local externalization of phosphatidylserine mediates developmental synaptic pruning by microglia

Neuronal circuits assembly requires the fine equilibrium between synapse formation and elimination. Microglia, through the elimination of supernumerary synapses, have an established role in this process. While the microglial receptor TREM2 and the soluble complement proteins C1q and C3 are recognized key players in this process, the neuronal molecular components that tag synapses to be eliminated are still undefined. Here we show that exposed phosphatidylserine (PS) represents a neuronal eat-me signal enabling microglial-mediated synapse pruning. In hippocampal neuron and microglia co-cultures, synapse elimination can be prevented by blocking accessibility of exposed PS using Annexin V or through microglial loss of TREM2. In vivo, exposed PS is detectable at both hippocampal and retinogeniculate synapses, where exposure coincides with the onset of synapse elimination and increased PS engulfment by microglia. Mice deficient in C1q, which fail to properly refine retinogeniculate connections, display elevated exposed PS and reduced PS engulfment by microglia. These data provide mechanistic insight into microglial-mediated synapse pruning and identify a novel role of developmentally regulated PS exposure that is common among developing brain structures.

neuroscience↗

bioRxiv2019

Constant Infusion Radiotracer Administration for High Temporal Resolution Positron Emission Tomography (PET) of the Human Brain: Application to -Fluorodexoyglucose PET (FDG-PET)

Functional Positron Emission Tomography (fPET) provides a method to track molecular dynamics in the human brain. With a radioactively labelled glucose-analogue, [18F]-flurodeoxyglucose (FDG-fPET), it is now possible to index the dynamics of glucose metabolism with temporal resolutions approaching those of functional magnetic resonance imaging (fMRI). This direct measure of glucose uptake has enormous potential for understanding normal and abnormal brain function, and probing the effects of metabolic and neurodegenerative diseases. Further, new advances in hybrid MR-PET hardware makes it possible to capture fluctuations in glucose and blood oxygenation simultaneously using fMRI and FDG-fPET.\n\nThe temporal resolution and signal-to-noise of the FDG-fPET images is critically dependent upon the administration of the radioactive tracer. In this work we present two alternative continuous infusion protocols and compare them to a traditional bolus approach. We detail a method for acquiring blood samples, time-locking PET, MRI and experimental stimulus, and administrating the non-traditional tracer delivery. By applying a visual stimulus, we demonstrate cortical maps of the glucose-response to external stimuli on an individual level with a temporal resolution of 16-seconds.\n\nSummaryRadiotracer infusion protocols for positron emission tomography (PET) provide improved temporal resolution over bolus administration. Here, we describe radiotracer administration for two protocols, constant infusion and bolus plus infusion protocol. We compare this to the standard bolus administration protocol. Using [18-F] fluorodeoxyglucose PET (FDG-PET) as an example, we show that temporal resolutions of approximately 16sec are achievable using these protocols.

neuroscience↗