Biology subjects

Arkelius, K.

Publications and source records attributed to Arkelius, K..

5 recordsLinked to original sources

bioRxiv2025

PCSK9 and High-Fat Diet Synergistically Induce Neurovascular Dysfunction and Neuroinflammation

Cerebral small vessel disease (CSVD) is strongly linked to metabolic risk factors and represents a major cause of vascular cognitive impairment and dementia. The interactions of genetic and environmental risk factors driving cerebrovascular pathology in metabolic syndrome are poorly understood. Here, we characterize neuroinflammatory and neurodegenerative phenotypes in a mouse model of metabolic syndrome with atherosclerosis induced by hepatic proprotein convertase subtilisin/kexin type 9 (PCSK9) overexpression combined with high-fat diet (HFD). PCSK9+HFD mice exhibit hallmark features of CSVD including vascular rarefaction, impaired neurovascular coupling, blood-brain barrier disruption, white matter injury, neuronal loss, and cognitive deficits. Notably, we identify lipid-droplet accumulating microglia (LDAM) as a distinct cellular phenotype that emerges in response to metabolic stress and correlates with cerebrovascular dysfunction. Three-dimensional light sheet microscopy reveals widespread vascular network disruption. Immunophenotyping demonstrates that microglia in PCSK9+HFD group exhibit enhanced phagocytic activation and ramification complexity yet accumulate perivascular amyloid-{beta}, suggesting impaired clearance capacity. Importantly, we observed vascular amyloid-{beta} deposition in wild-type mice without genetic Alzheimers disease mutations, suggesting that metabolic stress contributes to cerebrovascular amyloid pathology. PCSK9+HFD mice displayed recognition memory deficits and increased anxiety-like behavior. Our findings establish that severe hypercholesterolemia accelerates CSVD pathogenesis, and identify LDAM as a distinct pathological feature linking systemic metabolic syndrome to cerebrovascular dysfunction and cognitive impairment.

neuroscience↗

bioRxiv2025

Cerebrovascular Claudin-5 Isoform Expression Correlates with Worsened Stroke Outcomes Following Thromboembolic Stroke

Background and PurposeClaudin-5 plays a crucial role in the maintenance of the blood-brain barrier (BBB) integrity through its role in endothelial tight junction formation. Alternative splicing of claudin-5 within the microvascular endothelium may modulate BBB structural and functional dynamics, potentially influencing neuronal damage and recovery following ischemic stroke. We hypothesized that ischemic stroke induces temporal changes in claudin-5 protein isoform expression that correlates with worsened neurological outcomes. MethodsMale Wistar rats underwent thromboembolic stroke. Claudin-5 isoform expression was assessed at 3, 6, and 24h post-stroke onset, with additional groups receiving recombinant tissue plasminogen activator (rt-PA) at 4 hours post-stroke. Brain edema, infarct volume, hemorrhage, and cerebral blood flow was evaluated using 9.4T MRI. Ipsilateral and contralateral cerebrovascular claudin-5 expression was quantified via western blotting while neurological function was assessed by 28-point neuroscore. In addition, RNA sequencing analysis was performed to identify novel splice variants. ResultsA time-dependent increase in claudin-5 isoform 1 (35kDa) expression levels in the ipsilateral cerebrovasculature at 6 h was observed. Isoform 2 (25kDa) and fragment (10kDa) isoforms of claudin-5 remain unchanged. Treatment with rt-PA maintained the elevated levels of isoform 1 claudin-5 protein expression within the ipsilateral hemisphere. Increased claudin-5 isoform 1 expression within the ipsilateral hemisphere correlated with increased brain edema, hemorrhage, and worsened neurological function at 24h post-stroke onset. RNA sequencing revealed novel CLDN5 splice isoforms in post-stroke rat brain tissue which resemble structural similarity to known human CLDN5 isoforms. ConclusionThese findings demonstrate that ischemic stroke induces temporal, hemisphere-specific alterations in claudin-5 isoform expression that correlate with BBB dysfunction and poor neurological outcomes. The potential indication of novel alternative splice variants suggests that post-transcriptional regulation of claudin-5 represents a previously unrecognized mechanism contributing to endothelial tight junction dysfunction and stroke pathophysiology. These results highlight claudin-5 isoform expression as a potential therapeutic target for preserving BBB integrity following cerebral ischemia.

neuroscience↗

bioRxiv2025

Transcriptional and neuroprotective effects of hexokinase-2 inhibitors administered afterstroke

The inflammatory response induced by stroke can exacerbate injury to peri-infarct tissue. Microglia and other immune cells that mediate this response require increased glycolytic flux during pro-inflammatory activation. These cells, unlike neurons and most other cell types, utilize hexokinase-2 (HK2) rather than hexokinase-1 for glycolysis, such that HK2 inhibitors may selectively target them to suppress post-ischemic inflammation. Here we compared the effects of the non-selective hexokinase inhibitor 2-deoxyglucose to the HK2-selective inhibitors lonidamine and 3-bromopyruvate on secondary injury after stroke. A spatial transcriptomic assessment was performed in parallel to compare effects of the inhibitors on microglial gene expression and microglia - neuron interactions and to screen for off-target effects. Each of the inhibitors suppressed pro-inflammatory gene upregulation in peri-infarct microglia and attenuated the upregulation of cell stress functional pathways in the neighboring neurons, but had minimal effect on neuronal gene expression in uninjured cortex. The HK2-selective inhibitors were more effective than 2-deoxyglucose in suppressing morphological microglial changes, neuronal oxidative stress, and neurite loss. 3-bromopyruvate administered after stroke produced long-term improvements in functional outcome. Selective HK2 inhibitors may thus provide a clinically applicable means to suppress microglial activation and thereby improve outcomes after stroke without endangering neuronal energy metabolism.

neuroscience↗

bioRxiv2024

PATJ regulates cell stress responses and vascular remodeling post-stroke

PALS1-associated tight junction (PATJ) protein is linked to metabolic disease and stroke in human genetic studies. Despite the recognized role of PATJ in cell polarization, its specific functions in metabolic disease and ischemic stroke recovery remain largely unexplored. Using a mouse model of stroke, we found post-ischemic stroke duration-dependent increase of PATJ abundance in endothelial cells. PATJ knock-out (KO) HEK293 cells generated by CRISPR-Cas9 suggest roles for PATJ in cell proliferation, migration, mitochondrial stress response, and interactions with the Yes-associated protein (YAP)-1 signaling pathway. Notably, PATJ deletion altered YAP1 nuclear translocation. PATJ KO cells demonstrated extensive transcriptional reprograming based on RNA sequencing analysis. Crucially, we identified dysregulation in genes central to vascular development, stress response, and metabolism, including RUNX1, HEY1, NUPR1, and HK2. These insights offer a new understanding of PATJs complex regulatory functions within cellular and vascular physiology and help lay the groundwork for therapeutic strategies targeting endothelial PATJ-mediated pathways for stroke rehabilitation and neurovascular repair.

neuroscience↗

bioRxiv2023

LOX-1 and MMP-9 inhibition attenuates the detrimental effects of delayed rt-PA therapy and improves outcomes after acute ischemic stroke

BackgroundAcute ischemic stroke triggers endothelial activation that disrupts vascular integrity and increases hemorrhagic transformation leading to worsened stroke outcomes. Recombinant-tissue plasminogen activator (rt-PA) is an effective treatment; however, its use is limited due to a restricted time window and high risk for hemorrhagic transformation, which in part may involve activation of metalloproteinases (MMPs) mediated through lectin-like oxidized LDL receptor 1 (LOX-1). This studys overall aim was to evaluate the therapeutic potential of novel MMP-9 and LOX-1 inhibitors in combination with rt-PA to improve stroke outcomes. MethodsThromboembolic rat stroke model was utilized to investigate the impact of rt-PA delivered 4h post-stroke onset as well as selective LOX-1 (BI-0115) and/or MMP-9 (JNJ0966) inhibitors given prior to rt-PA administration. Infarct size, perfusion, and hemorrhagic transformation were evaluated by MRI. Neurological function was assessed using sensorimotor functioning testing. Using an in vitro, human brain microvascular endothelial cell (HBMEC) model, cells were exposed to hypoxia plus glucose deprivation (3h)/reperfusion (12h) (HGD/R) and treated with rt-PA {+/-} an MMP-9 and LOX-1 inhibition cocktail. MMP-9 activity was determined with zymography, and endothelial barrier marker gene expression and LOX-1 levels were evaluated via qRT-PCR and western blot respectively. ResultsRt-PA treatment increased edema, hemorrhage, and worsened neurological outcomes post stroke. LOX-1 inhibition significantly improved neurological function and reduced edema after delayed rt-PA treatment. Hemorrhagic transformation, edema, and increased MMP-9 activity were attenuated by the MMP-9 inhibitor. Stroke induced increases in cerebrovascular LOX-1 expression correlated with increased MMP-9 activity and elevated activity correlated with increased edema, infarct volume, and decreased neurological function. In cultured HBMECs, LOX-1/MMP-9 inhibition differentially attenuated rt-PA-mediated increases in endothelial derived MMP-9 levels and activity, inflammation, and activation following HGD/R. ConclusionHere, we conclude that MMP-9/LOX-1 inhibition attenuates negative aspects of delayed rt-PA therapy leading to improved neurological function.

neuroscience↗