Biology subjects

Olsen, M. L.

Publications and source records attributed to Olsen, M. L..

8 recordsLinked to original sources

bioRxiv2025

Brain injury contributes to dopaminergic neurodegeneration, Lewy body pathology, and Parkinsonism preclinically with outcomes altered by T cell modulation

Traumatic brain injury (TBI) increases the risk of Parkinsons disease (PD) development later in life, but much remains unknown regarding the mechanisms driving this relationship. A single, mild brain injury triggers resident and peripheral neuroinflammatory pathways that are similarly activated in PD patients, which could possibly increase susceptibility to neurodegeneration. In this study, we used preclinical mouse models of mild TBI (mTBI) and PD to evaluate how injury-induced immune signaling may exacerbate PD-associated pathologies. Dopaminergic (DA) neurons showed upregulation of genes associated with neuroinflammation, adaptive immunity, and PD following mTBI. mTBI caused degeneration of DA neurons in the substantia nigra (SN) and increased the spread of Lewy body (LB) pathology to other brain regions, such as the ipsilateral cortex, in a preclinical model of PD. Reducing adaptive immune infiltration into the central nervous system (CNS) with a transgenic model lacking mature lymphocytes, or directly by in vivo depletion of T cells or B cells individually, improved neurodegenerative outcomes of DA neurons following brain injury. Our results indicate the possibility of a sustained, chronic peripheral immune cell infiltration which negatively affects both DA neurons and alpha synuclein (-syn) fibril propagation, providing insight on therapeutic windows to reduce DA neuron vulnerability.

neuroscience↗

bioRxiv2025

Design-driven optimization of low-cost reagent formulations for reproducible and high-yielding cell-free gene expression

Access to recombinant proteins is vital in basic science and biotechnology research. Cell-free gene expression systems provide one approach to address this need, but widespread utilization remains limited by the cost, complexity, and inconsistency of current platforms. To address these limitations, we carry out a multi-dimensional definitive screening design to reduce the number of reagent components and remove costly secondary energy substrates. From more than 1,200 reagent formulations, we discover a simple and reproducible system based on 12 components. The optimized reagent formulation can produce 2.4 {+/-} 0.3 g/L of protein product at the 15-L scale ([~]$55/gprotein) and 3.7 {+/-} 0.2 g/L ([~]$36/gprotein) at the 4-mL scale with oxygen supplementation. This provides an 84 to 99% reduction in cost over previous cell-free reagent formulations. We further show that the optimized reagent formulation can produce nucleoside triphosphates from nucleotides and ribose and that it is robust to failure across batches of cell lysates, users/locations, and in the synthesis of different proteins. Specifically, we demonstrate the production of fifteen therapeutically relevant products, including full-length aglycosylated monoclonal antibodies. We anticipate that our optimized reagent formulation will further democratize the use of cell-free systems for protein manufacturing and synthetic biology applications.

synthetic biology↗

bioRxiv2025

Vascular amyloidβ load in the meningeal arterial network correlates with loss of cerebral blood flow and pial collateral vessel enlargement in the J20 murine model of Alzheimer's disease

BackgroundGlobal reductions in cerebral blood flow (CBF) are among the earliest and most consistent abnormalities observed in Alzheimers disease (AD), preceding both cortical plaque formation and cognitive decline. While the pial arterial network--a critical supplier of intracortical perfusion--has been overlooked in this context, it may play a pivotal role in early vascular pathology. Here, we report extensive cerebral amyloid angiopathy (CAA) within the pial artery and arteriole network in the J20 (PDGF-APPSw, Ind) mouse model of AD. MethodsUsing premortem delivery of Methoxy-XO4 to label A{beta}, and arterial vascular labeling, we assessed A{beta} burden on the pial artery/arteriole network and cerebral blood flow in aged male and female WT and J20 AD mice. ResultsWe show that 12-month-old J20 mice exhibit significant A{beta} deposition across major leptomeningeal arteries (ACA, MCA) and pial collaterals, with [~]40% vessel coverage in males and [~]20% in females--substantially exceeding A{beta} levels in cortical or hippocampal vessels. This vascular A{beta} burden was accompanied by compensatory enlargement and increased tortuosity of pial collateral vessels. Yet, despite this apparent remodeling, CBF was reduced by [~]15% in J20 mice, and this decline was significantly associated with leptomeningeal CAA burden. ConclusionsThis is the first study to comprehensively characterize meningeal arterial A{beta} accumulation in a preclinical model of vascular AD, mirroring recent observations in early-stage human disease. Our findings implicate meningeal CAA as a potential driver of early CBF disruption and suggest that pial collateral remodeling may reflect a compensatory response to vascular insufficiency. Moreover, we identify robust sex differences in CAA burden, paralleling sex-specific patterns of parenchymal A{beta} pathology in humans. These results highlight the leptomeningeal vasculature as a novel and understudied locus for early AD pathology and a potential therapeutic target to preserve cerebrovascular integrity.

neuroscience↗

bioRxiv2024

Astrocyte TrkB.T1 deficiency disrupts glutamatergic synaptogenesis and astrocyte-synapse interactions.

Perisynaptic astrocyte processes (PAPs) contact pre- and post-synaptic elements to provide structural and functional support to synapses. Accumulating research demonstrates that the cradling of synapses by PAPs is critical for synapse formation, stabilization, and plasticity. The specific signaling pathways that govern these astrocyte-synapse interactions, however, remain to be elucidated. Herein, we demonstrate a role for the astrocyte TrkB.T1 receptor, a truncated isoform of the canonical receptor for brain derived neurotrophic factor (BDNF), in modulating astrocyte-synapse interactions and excitatory synapse development. Neuron-astrocyte co-culture studies revealed that loss of astrocyte TrkB.T1 disrupts the formation of PAPs. To elucidate the role of TrkB.T1 in synapse development, we conditionally deleted TrkB.T1 in astrocytes in mice. Synaptosome preparations were employed to probe for TrkB.T1 localization at the PAP, and confocal three-dimensional microscopy revealed a significant reduction in synapse density and astrocyte-synapse interactions across development in the absence of astrocytic TrkB.T1. These findings suggest that BDNF/TrkB.T1 signaling in astrocytes is critical for normal excitatory synapse formation in the cortex and that astrocyte TrkB.T1 serves a requisite role in astrocyte synapse interactions. Overall, this work provides new insights into the molecular mechanisms of astrocyte-mediated synaptogenesis and may have implications for understanding neurodevelopmental disorders and developing potential therapeutic targets.

neuroscience↗

bioRxiv2024

Decoding the Epigenetic Landscape: Insights into 5mC and 5hmC Patterns in Mouse Cortical Cell Types

The DNA modifications, 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC), represent powerful epigenetic regulators of temporal and spatial gene expression. Yet, how the cooperation of these genome-wide, epigenetic marks determine unique transcriptional signatures across different brain cell populations is unclear. Here we applied Nanopore sequencing of native DNA to obtain a complete, genome-wide, single-base resolution atlas of 5mC and 5hmC modifications in neurons, astrocytes and microglia in the mouse cortex (99% genome coverage, 40 million CpG sites). In tandem with RNA sequencing, analysis of 5mC and 5hmC patterns across cell types reveals astrocytes drive uniquely high brain 5hmC levels and support two decades of research regarding methylation patterns, gene expression and alternative splicing, benchmarking this resource. As such, we provide the most comprehensive DNA methylation data in mouse brain as an interactive, online tool (NAM-Me, https://olsenlab.shinyapps.io/NAMME/) to serve as a resource dataset for those interested in the methylome landscape.

neuroscience↗

bioRxiv2023

Infection-induced epilepsy is caused by increased expression of chondroitin sulfate proteoglycans in hippocampus and amygdala

Alterations in the extracellular matrix (ECM) are common in epilepsy, yet whether they are cause or consequence of disease is unknow. Using Theilers virus infection model of acquired epilepsy we find de novo expression of chondroitin sulfate proteoglycans (CSPGs), a major ECM component, in dentate gyrus (DG) and amygdala exclusively in mice with seizures. Preventing synthesis of CSPGs specifically in DG and amygdala by deletion of major CSPG aggrecan reduced seizure burden. Patch-clamp recordings from dentate granule cells (DGCs) revealed enhanced intrinsic and synaptic excitability in seizing mice that was normalized by aggrecan deletion. In situ experiments suggest that DGCs hyperexcitability results from negatively charged CSPGs increasing stationary cations (K+, Ca2+) on the membrane thereby depolarizing neurons, increasing their intrinsic and synaptic excitability. We show similar changes in CSPGs in pilocarpine-induced epilepsy suggesting enhanced CSPGs in the DG and amygdala may be a common ictogenic factor and novel therapeutic potential.

neuroscience↗

bioRxiv2023

A novel adjuvant formulation induces robust Th1/Th17 memory and mucosal recall responses in Non-Human Primates

After clean drinking water, vaccination is the most impactful global health intervention. However, development of new vaccines against difficult-to-target diseases is hampered by the lack of diverse adjuvants for human use. Of particular interest, none of the currently available adjuvants induce Th17 cells. Here, we develop and test an improved liposomal adjuvant, termed CAF(R)10b, that incorporates a TLR-9 agonist. In a head-to-head study in non-human primates (NHPs), immunization with antigen adjuvanted with CAF(R)10b induced significantly increased antibody and cellular immune responses compared to previous CAF(R) adjuvants, already in clinical trials. This was not seen in the mouse model, demonstrating that adjuvant effects can be highly species specific. Importantly, intramuscular immunization of NHPs with CAF(R)10b induced robust Th17 responses that were observed in circulation half a year after vaccination. Furthermore, subsequent instillation of unadjuvanted antigen into the skin and lungs of these memory animals led to significant recall responses including transient local lung inflammation observed by Positron Emission Tomography-Computed Tomography (PET-CT), elevated antibody titers, and expanded systemic and local Th1 and Th17 responses, including >20% antigen-specific T cells in the bronchoalveolar lavage. Overall, CAF(R)10b demonstrated an adjuvant able to drive true memory antibody, Th1 and Th17 vaccine-responses across rodent and primate species, supporting its translational potential.

immunology↗

bioRxiv2019

BDNF/TrkB.T1 signaling is a novel mechanism for astrocyte morphological maturation

Brain derived neurotrophic factor (BDNF) is a critical growth factor involved in the maturation of neurons, including neuronal morphology and synapse refinement. Herein, we demonstrate astrocytes express high levels of BDNFs receptor, TrkB (in the top 20 of protein-coding transcripts), with nearly exclusive expression of the truncated isoform, TrkB.T1 which peaks in expression during astrocyte morphological maturation. Using a novel culture paradigm, we show that astrocyte morphological complexity is increased in the presence of BDNF and is dependent upon BDNF/TrkB.T1 signaling. Deletion of TrkB.T1 in vivo revealed morphologically immature astrocytes with significantly reduced volume and branching, as well as dysregulated expression of perisynaptic genes associated with mature astrocyte functions, including synaptogenic genes. Indicating a role for functional astrocyte maturation via BDNF/TrkB.T1 signaling, TrkB.T1 KO astrocytes do not support normal excitatory synaptogenesis. These data suggest a significant role for BDNF/TrkB.T1 signaling in astrocyte morphological maturation, a critical process for CNS development.

neuroscience↗