Search bioRxiv⌕ Search

Biology subjects

Nilsson, P. R.

Publications and source records attributed to Nilsson, P. R..

9 recordsLinked to original sources

Soluble epoxide hydrolase upregulation in Alzheimer's disease promotes blood-brain barrier dysfunction

Recent advances in anti-amyloid therapies for Alzheimers disease have been promising, but they have also highlighted critical challenges, including increased vascular complications, such as amyloid-related imaging abnormalities. Emerging evidence suggests that the soluble epoxide hydrolase may be a promising therapeutic target due to the involvement of sEH-derived diols in inflammation, oxidative stress, and vascular destabilization. APPPS1 mice were crossed with an inducible soluble epoxide hydrolase knock-out mouse line. The knock-out was induced before onset of amyloid deposition, and then the mice were analyzed using histological, molecular, and RNA sequencing techniques. Here, we identify astrocytic soluble epoxide hydrolase as a key mediator of vascular instability in Alzheimers disease. Targeted astrocyte-specific deletion of soluble epoxide hydrolase in APPPS1 mice dramatically mitigated vascular changes, reducing the vascular amyloid burden by 67.95% and preserving VE-cadherin architecture. Importantly, vasomotion was markedly impaired in the Alzheimers disease model and was preserved in soluble epoxide hydrolase-deficient animals. Transcriptomic profiling of vasculature in APPPS1xsEH{Delta}AC mice revealed upregulated expression of genes critical for neurovascular protection. These findings identify soluble epoxide hydrolase as a central regulator of neurovascular dysfunction and underscore its therapeutic potential in increasing vascular stability in Alzheimers disease.

neuroscience↗

Enhanced ex vivo 3D whole-brain mapping and automated analysis of Parkinson's disease pathologies in mice

The spatiotemporal relationships among -synuclein inclusion formation, dopaminergic degeneration, and white matter microstructural changes remain poorly defined. To address this, we unilaterally injected preformed fibrils (PFFs) or monomeric -synuclein into the substantia nigra pars compacta (SNc) of wild-type mice. At 12 and 20 weeks post-injection (wpi), we performed ex vivo magnetic resonance imaging (MRI) at 9.4T to assess microstructural, volumetric and paramagnetic changes, along with light-sheet microscopy (LSM) to map -synuclein aggregates, and dopaminergic neuron at single-cell resolution across the whole brain. We developed a Python-based, automated registration pipeline that achieves <40 {micro}m alignment error between ex vivo MRI and LSM and computes clearing-induced distortion, enabling scalable deformation analysis and multimodal multiscale data integration. Unilateral SNc injection of -syn PFFs induced dense phospho--syn pathology in the ipsilateral SNc at 12 wpi, which decreased by 20 wpi in parallel with the loss of tyrosine hydroxylase-positive dopaminergic neuron. Pathogenic -synuclein spreads along with dopaminergic denervation in the nigrostriatal pathway to the ipsilateral striatum and contralateral SNc. Our ex vivo MRI-LSM platform provides a scalable, open-source framework for understanding circuit-level and whole-brain propagation of pathology in an -synucleinopathy model and beyond. HighlightsO_LIOpen-source, automated pipeline aligns ex vivo 9.4T MRI with light-sheet microscopy (LSM) at <40 {micro}m error, quantifies clearing-induced tissue distortion, and enables multiscale, whole-brain multimodal analysis. C_LIO_LIWhole-brain, single-cell-resolution mapping of -synuclein pathology and dopaminergic neuron loss in an -synucleinopathy mouse model using an optimized iDISCO+ protocol that achieves uniform antibody penetration even in dense regions like the striatum. C_LIO_LIUnilateral SNc injection of -syn PFFs drives spread of p--syn pathology along the nigrostriatal pathway to the ipsilateral striatum, BST, CEA, and contralateral SNc, along with dopaminergic degeneration. C_LIO_LIIpsilateral SNc shows high pS129 pathology at 12 weeks post-injection but significant reduction by 20 wpi, concurrent with loss of tyrosine hydroxylase-positive neurons. C_LIO_LIMultiparametric MRI reveals microstructural and iron-related alterations in striatum, SNc, and VTA, with cross-modal correlations linking pS129 burden, TH loss, and magnetic susceptibility changes. C_LI

neuroscience↗

The tumor suppressor protein PTEN undergoes amyloid-like aggregation in tumor cells.

Protein aggregation is an underappreciated mechanism that may contribute to the loss- and oncogenic-gain-of-function of mutant tumor suppressors such as p53 and axin. In the present study, we describe amyloid-like aggregation behaviour of the second most frequently mutated tumor suppressor in human cancer, PTEN. In silico analysis revealed a particularly high aggregation vulnerability for this protein, which was corroborated by in vitro aggregation assays. In cultured tumor cells, we found that under stress conditions, PTEN readily undergoes amyloid-like aggregation as a result of mutation. However, we also show that severe dysregulation of protein homeostasis may lead to aggregation of wild-type PTEN. These observations were supported by a small survey of patient-derived uterine tumor tissues, which found that more than 25% of tumors analyzed displayed wild-type PTEN aggregation. Finally, in an exploratory clinical study we found that PTEN aggregation status was correlated with a decline in clinical outcome. Our findings establish that the tumor suppressor PTEN is highly aggregation-prone and our work suggests that protein aggregation might be an underestimated but prevalent component of cancer cell biology.

cancer biology↗

Inhibiting the mitochondrial pyruvate carrier does not ameliorate synucleinopathy in the absence of inflammation or metabolic deficits

Epidemiological studies suggest a link between type-2 diabetes and Parkinsons disease (PD) risk. Treatment of type-2 diabetes with insulin sensitizing drugs lowers the risk of PD. We previously showed that the insulin sensitizing drug, MSDC-0160, ameliorates pathogenesis in some animal models of PD. MSDC-0160 reversibly binds the mitochondrial pyruvate carrier (MPC) protein complex, which has an anti-inflammatory effect and restores metabolic deficits. Since PD is characterized by the deposition of -synuclein (Syn), we hypothesized that inhibiting the MPC might directly inhibit Syn aggregation in vivo in mammals. To answer if modulation of MPC can reduce the development of Syn assemblies, and reduce neurodegeneration, we treated two chronic and progressive mouse models; a viral vector-based Syn overexpressing model and a pre-formed fibril (PFF) Syn seeding model with MSDC-0160. These two models present with distinct types of Syn pathology but lack inflammatory or autophagy deficits. Contrary to our hypothesis, we found that a modulation of MPC in these models did not reduce the accumulation Syn aggregates or mitigate neurotoxicity. Instead, MSDC-0160 changed the post-translational modification and aggregation features of the Syn. These results are consistent with the lack of a direct effect on MPC modulation on synuclein clearance in these models.

neuroscience↗

Detection of cerebral tauopathy in P301L mice using high-resolution large-field multifocal illumination fluorescence microscopy

Current intravital microscopy techniques visualize tauopathy with high-resolution, but have a small field-of-view and depth-of-focus. Herein, we report a transcranial detection of tauopathy over the entire cortex of P301L tauopathy mice using large-field multifocal illumination (LMI) fluorescence microscopy technique and luminescent conjugated oligothiophenes. In vitro assays revealed that fluorescent ligand h-FTAA is optimal for in vivo tau imaging, which was confirmed by observing elevated probe retention in the cortex of P301L mice compared to non-transgenic littermates. Immunohistochemical staining further verified the specificity of h-FTAA to detect tauopathy in P301L mice. The new imaging platform can be leveraged in pre-clinical mechanistic studies of tau spreading and clearance as well as longitudinal monitoring of tau targeting therapeutics.

neuroscience↗

Whole brain optoacoustic tomography reveals strain-specific regional beta-amyloid densities in Alzheimer`s disease amyloidosis models

Deposition of beta-amyloid (A{beta}) deposits is one major histopathological hallmark of Alzheimers disease (AD). Here, we introduce volumetric multi-spectral optoacoustic tomography (vMSOT), which covers 10x10x10 mm3 field-of-view, capable of 3D whole mouse brain imaging. We show for the first time the optoacoustic properties of oxazine-derivative AOI987 probe, which binds to A{beta}, and the application of vMSOT for the quantification of brain-wide A{beta} deposition. Administration of AOI987 to two common transgenic mouse strains of AD amyloidosis led to a retention of the probe in A{beta}-laden brain regions. Co-registered of vMSOT data to a brain atlas revealed strain-specific pattern of AOI987 uptake. A comparison with ex vivo light-sheet microscopy in cleared mouse brains showed a good correspondence in A{beta} distribution. Lastly, we demonstrate the specificity of the AOI987 probe by immunohistochemistry. vMSOT with AOI987 facilitates preclinical brain region-specific studies of A{beta} spread and accumulation, and the monitoring of putative treatments targeting A{beta}.

neuroscience↗

Transcranial in vivo detection of Aβ at single plaque resolution with large-field multifocal illumination fluorescence microscopy

The abnormal deposition of beta-amyloid proteins in the brain is one of the major histopathological hallmarks of Alzheimers disease. Currently available intravital microscopy techniques for high-resolution plaque visualization commonly involve highly invasive procedures and are limited to a small field-of-view within the rodent brain. Here, we report the transcranial detection of amyloid-beta deposits at the whole brain scale with 20 m resolution in APP/PS1 and arcA{beta} mouse models of Alzheimers disease amyloidosis using a large-field multifocal (LMI) fluorescence microscopy technique. Highly sensitive and specific detection of amyloid-beta deposits at a single plaque level in APP/PS1 and arcA{beta} mice was facilitated using luminescent conjugated oligothiophene HS-169. Immunohistochemical staining with HS-169, anti-A{beta} antibody 6E10, and conformation antibodies OC (fibrillar) of brain tissue sections further showed that HS-169 resolved compact parenchymal and vessel-associated amyloid deposits. The novel imaging platform offers new prospects for in vivo studies into Alzheimers disease mechanisms in animal models as well as longitudinal monitoring of therapeutic responses at a single plaque level.

neuroscience↗

Microglia control small vessel calcification via TREM2

Microglia participate in CNS development and homeostasis and are often implicated in modulating disease processes in the CNS. However, less is known about the role of microglia in the biology of the neurovascular unit (NVU). In particular, data are scant on whether microglia are involved in CNS vascular pathology. In this study, we use a mouse model of primary familial brain calcification (PFBC) - Pdgfbret/ret to investigate the role of microglia in calcification of the NVU. We report that microglia enclosing vessel-calcifications, coined calcification-associated microglia (CAM), display a distinct activation signature. Pharmacological ablation of microglia with the CSF1R inhibitor - PLX5622 leads to aggravated vessel calcification. Additionally, depletion of microglia in wild-type and Pdgfbret/ret mice causes the development of bone protein (osteocalcin, osteopontin) containing axonal spheroids in the white matter. Mechanistically, we show that microglia require functional TREM2 for controlling vessel-associated calcification. In conclusion, our results demonstrate that microglial activity in the setting of pathological vascular calcification is beneficial. In addition, we identify a new, previously unrecognized function of microglia in halting the expansion of ectopic calcification.

neuroscience↗

Live detection of neural stem and glioblastoma cells by an oligothiophene derivative

Here we report a luminescent conjugated oligothiophene (LCO), named p-HTMI, for non-invasive and non-amplified real-time detection of live human patient-derived glioblastoma (GBM) cells and embryonic neural stem cells (NSCs). While p-HTMI stained only a small fraction of other cell types investigated, the mere addition of p-HTMI to the cell culture resulted in efficient detection of NSCs or GBM cells from rodents and humans within minutes. p-HTMI is functionalized with a methylated imidazole moiety resembling the side chain of histidine/histamine, and non-methylated analogues were not functional. p-HTMI were readily able to detect a subpopulation of human cells in vivo in mouse brain sections with tumors developed from orthotopically transplanted patient-derived GBM cells. Cell sorting experiments of human GBM cells demonstrated that p-HTMI labeled the same population as CD271, a proposed marker for stem cell-like cells and rapidly migrating cells in glioblastoma. Our results suggest that the LCO p-HTMI is a versatile tool for immediate and selective detection of subpopulations of neural stem and glioma cells.

bioengineering↗