Biology subjects

Rutledge, C.

Publications and source records attributed to Rutledge, C..

6 recordsLinked to original sources

bioRxiv2025

Sensory neurostimulation promotes stress resilience with frequency-specificity

Chronic stress is a major risk factor for neuropsychiatric disorders, acting via increased neuroinflammation and disrupted synaptic plasticity. While non-invasive visual or audiovisual neurostimulation (AV flicker) at 40Hz has been shown to modulate brain immune signaling and improve cognitive performance in mouse models of Alzheimers disease, its effects in the context of stress remain unknown. Here we show that AV flicker protects against stress-induced behavioral, microglial, astrocytic, and synaptic changes in a sex- and frequency-specific manner. Male and female mice underwent 28 days of chronic unpredictable stress with concomitant daily AV flicker exposure at 10Hz, 20Hz, or 40Hz. Stress-induced behaviors were most effectively mitigated by 10Hz AV flicker in males and 40Hz AV flicker in females. In the medial prefrontal cortex, AV flicker normalized the balance of mature and immature dendritic spines and counteracted stress-induced molecular changes in neurons, microglia, and astrocytes, including in key neuropsychiatric risk genes. These findings show that frequency optimized AV flicker induces resilience to chronic stress.

neuroscience↗

bioRxiv2024

Mesenchymal Cell-Derived Extracellular Vesicles Ameliorate Age-Related Deficits in Working Memory as well as Brain MRI and CSF in vivo Biomarkers of Neurodegeneration in Rhesus Monkeys.

Normal aging in humans and non-human primates is associated with a decline in cognitive functions. Subject-wise differences in cognitive decline can be attributed to different degrees of damage to cortical white matter (WM) which is largely affected by neuroinflammation during aging. Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) have recently been identified as a potential immunomodulatory therapeutic for brain damage and Alzheimers disease (AD) and related dementias by suppressing neuroinflammation. Here, we evaluated the efficacy of MSC-EVs for slowing or ameliorating cognitive decline during aging in rhesus monkeys, a well-studied model of normal aging that is free of extensive AD pathology. We report that late middle-aged monkeys treated with MSC-EVs every two weeks for 18 months showed improved performance on a task of spatial working memory relative to vehicle control monkeys. In addition, we used diffusion magnetic resonance imaging (MRI) and resting state functional MRI to evaluate structural white matter and functional network changes in vivo. Imaging data revealed that MSC-EV treatment preserved prefrontal and temporal WM structural integrity and large-scale functional network connectivity that are correlated with early, increased CSF levels of amyloid beta protein. Amyloid beta levels at 12 months are also correlated with improved cognitive performance at the end of the 18 months of treatment. These findings suggest that MSC-EVs can mitigate age-related cognitive decline by potentially enhancing the CSF clearance of neurodegenerative proteins, which correlates with greater WM integrity and functional brain connectivity.

neuroscience↗

bioRxiv2024

Temporal dynamics of inflammatory and transcriptome changes in the myocardium in a murine model of cardiac arrest

BackgroundIt is increasingly recognized that inflammatory changes play a significant role in myocardial injury following cardiac arrest. However, the pathophysiological mechanisms responsible for functional changes in the myocardium following the event remain incompletely understood. Here, we characterize the transcriptomic and immunological changes in a mouse model of cardiac arrest to explore the roles of epinephrine and ischemia/reperfusion on myocardial inflammation. Methods and ResultsMale and female mice (C57BL/6J) were divided into three groups: (1) Naive (anesthesia only), (2) Sham (anesthesia + saline injection + epinephrine), and (3) Arrest (8-minute cardiac arrest followed by resuscitation (anesthesia + potassium chloride + epinephrine). We monitored the animals over 0.5, 1, 3, and 7 days with serial echocardiography. Hearts were harvested for transcriptomic analysis and inflammatory changes as assessed by flow cytometry and immunohistochemistry. Plasma samples were collected for cytokine signaling analysis by multiplex ELISA. Our data indicate that the cardiac arrest group have increased infiltrating neutrophils in the myocardium and elevated plasma levels of pro-inflammatory cytokines, peaking at 0.5 days after the initial insult and subsequently resolving. In contrast, Sham mice displayed less pronounced inflammatory changes, which peaked at 1 day after the procedure. Notably, these inflammatory alterations coincided with cardiac stunning, as demonstrated by echocardiography. ConclusionsIn our murine model of cardiac arrest, epinephrine exposure and ischemia/reperfusion induce significant inflammatory changes in the myocardium with increased infiltrating neutrophils and elevated circulating cytokines which subsequently resolve in a time-dependent manner. These changes correlate with improving cardiac function by echocardiography.

immunology↗

bioRxiv2022

Liraglutide protects against diastolic dysfunction and improves ventricular protein translation

PurposeDiastolic dysfunction is an increasingly common cardiac pathology linked to heart failure with preserved ejection fraction. Previous studies have implicated glucagon-like peptide 1 (GLP-1) receptor agonists as potential therapies for improving diastolic dysfunction. In this study, we investigate the physiologic and metabolic changes in a mouse model of angiotensin II (AngII) mediated diastolic dysfunction with and without the GLP-1 receptor agonist liraglutide (Lira). MethodsMice were divided into sham, AngII, or AngII + Lira therapy for 4 weeks. Mice were monitored for cardiac function, weight change, and blood pressure at baseline and after 4 weeks of treatment. After 4 weeks of treatment, tissue was collected for histology, protein analysis, targeted metabolomics, and protein synthesis assays. ResultsAngII treatment causes diastolic dysfunction when compared to sham mice. Lira partially prevents this dysfunction. The improvement in function in Lira mice is associated with dramatic changes in amino acid accumulation in the heart. Lira mice also have improved markers of protein translation by Western blot and increased protein synthesis by puromycin assay, suggesting that increased protein turnover protects against fibrotic remodeling and diastolic dysfunction seen in the AngII cohort. Lira mice also lost lean muscle mass compared to the AngII cohort, raising concerns about peripheral muscle scavenging as a source of the increased amino acids in the heart. ConclusionsLira therapy protects against AngII-mediated diastolic dysfunction, at least in part by promoting amino acid uptake and protein turnover in the heart. Liraglutide therapy is associated with loss of mean muscle mass, and long-term studies are warranted to investigate sarcopenia and frailty with liraglutide therapy in the setting of diastolic disease.

physiology↗

bioRxiv2021

Metformin Confers Cardiac and Renal Protection in Sudden Cardiac Arrest via AMPK Activation

Cardiac arrest (CA) causes high mortality due to multi-system organ damage attributable to ischemia-reperfusion injury. Recent work in our group found that among diabetic patients who experienced cardiac arrest, those taking metformin had less evidence of cardiac and renal damage after cardiac arrest when compared to those not taking metformin. To investigate the potential for metformin to impact cardiac arrest outcomes, the current study investigates metformin interventions on cardiac and renal outcomes in a non-diabetic CA mouse model. We found that two weeks of metformin pretreatment protects against reduced ejection fraction and reduces kidney ischemia-reperfusion injury at 24 hours post-arrest. This cardiac and renal protection depends on AMPK signaling, as demonstrated by outcomes in mice pretreated with the AMPK activator AICAR or metformin plus the AMPK inhibitor compound C. At this 24-hour time point, gene expression analysis showed that metformin pretreatment caused changes supporting autophagy, antioxidant response, and protein translation. Further investigation found associated improvements in mitochondrial structure and markers of autophagy. We also found that markers of protein nitrosylation between sham and arrest were not significantly different and thus unlikely to be a driver of gene expression differences. Notably, Western analysis indicated that protein synthesis was preserved in arrest hearts of animals pretreated with metformin. The AMPK activation-mediated protection of protein synthesis was also demonstrated in a hypoxia/reoxygenation cell culture model. Despite the positive impacts of pretreatment in vivo and in vitro, metformin did not preserve ejection fraction when deployed at resuscitation. Taken together, we propose that metformins in vivo cardiac preservation occurs through AMPK activation, requires adaptation before arrest, and is associated with preserved protein translation. New and NoteworthyWe leveraged a mouse model of cardiac arrest to study whether metformin pretreatment could protect cardiac function after arrest. We find that AMPK activity is crucial to this protection and characterize several pathways associated with this response. Signaling nodes with strong association may be precise targets to promote cardiac function in ischemia/reperfusion injury or in cardiac stunning.

physiology↗

bioRxiv2020

Histone modifications form a cell-type-specific chromosomal bar code that modulates and maintains patterns of gene expression through the cell cycle

BackgroundChromatin configuration influences gene expression in eukaryotes at multiple levels, from individual nucleosomes to chromatin domains several Mb long. Post-translational modifications (PTM) of core histones seem to be involved in chromatin structural transitions, but how remains unclear. To explore this, we used ChIP-seq and two cell types, HeLa and lymphoblastoid (LCL) to define how changes in chromatin packaging through the cell cycle influence the distributions of three transcription-associated histone modifications, H3K9ac, H3K4me3 and H3K27me3. ResultsChromosome regions (bands) of 10-50Mb, detectable by immunofluorescence microscopy of metaphase (M) chromosomes, are also present in G1 and G2. We show that they comprise 1-5Mb sub-bands that differ between HeLa and LCL but remain consistent through the cell cycle. The same sub-bands are defined by H3K9ac and H3K4me3, while H3K27me3 spreads more widely. We found little change between cell cycle phases, whether compared by 5Kb rolling windows or when analysis was restricted to functional elements such as transcription start sites and topologically associating domains. Only a small number of genes showed cell-cycle related changes: at genes encoding proteins involved in mitosis, H3K9 became highly acetylated in G2M, possibly because of ongoing transcription. ConclusionsModified histone isoforms H3K9ac, H3K4me3 and H3K27me3 exhibit a characteristic genomic distribution at resolutions of 1Mb and below that differs between HeLa and lymphoblastoid cells but remains remarkably consistent through the cell cycle. We suggest that this cell-type-specific chromosomal bar-code is part of a homeostatic mechanism by which cells retain their characteristic gene expression patterns, and hence their identity, through multiple mitoses.

genomics↗