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Background: Epidemiological data suggests statins could reduce the risk of dementia, and more specifically, Alzheimer's disease (AD). Pre-clinical data suggests statins reduce the risk of dementia through their pleiotropic effects rather than their cholesterol lowering effects. While AD is a leading cause of dementia, it is frequently found co-morbidly with cerebral small vessel disease and other vascular contributions to cognitive impairment and dementia (VCID), which are another leading cause of dementia. In this study, we determined if atorvastatin ameliorated hyperhomocysteinemia (HHcy)-induced VCID. Methods: Wild-type (C57Bl6/J) mice were placed on a diet to induce HHcy or a control diet each with or without atorvastatin for 14 weeks. Mice underwent novel object recognition testing before tissue collection. Plasma total cholesterol and total homocysteine as well as related metabolites were measured. Using qPCR and NanoString technology, we profiled glial cell-associated gene expression changes. Finally, microglial morphology, astrocyte end feet, and microhemorrhages were analyzed using histological methods. Results: Atorvastatin treatment of HHcy in mice led to no changes in total cholesterol but decreases in total homocysteine in plasma. While HHcy decreased expression of many glial genes, atorvastatin rescued these gene changes, which mostly occurred in oligodendrocytes and microglia. Microglia in HHcy mice with atorvastatin were trending towards fewer processes compared to control with atorvastatin, but there were no atorvastatin effects on astrocyte end feet. While atorvastatin treatment was trending towards increasing the area of microhemorrhages in HHcy mice in the frontal cortex, it only slightly (non-significantly) reduced the number of microhemorrhages. Finally, atorvastatin treatment in HHcy mice led to improved cognition on the novel object recognition task. Conclusions: These data suggest that atorvastatin rescued cognitive changes induced by HHcy most likely through lowering plasma total homocysteine and rescuing gene expression changes rather than impacts on vascular integrity or microglial changes. [ABSTRACT FROM AUTHOR]

Abstract: Superoxide dismutase (SOD) is major cytosolic antioxidant enzyme responsible for dismutation of superoxide anion (). Alterations in SOD expression and activity are associated with various neurological disorders. In the present study, we utilized neuronal HT-22 cells to investigate heat-stressed induced cytotoxicity. Heat stress at 43°C for 30min caused a decrease in SOD-1 mRNA levels, cytoplasmic SOD protein and enzyme activity and a corresponding decline in cell number during a 48h recovery at 37°C. During the recovery phase, there was an increase in reactive oxygen species generation and an increase in NADPH oxidase activity with a corresponding increase in DNA fragmentation and release of cytochrome c from the mitochondria. The increase in ROS accumulation and cell death was abolished by pretreatment with the SOD mimetics EUK-134 and Mn(III)TBAP and the NADPH oxidase inhibitor apocynin. These data suggest that hyperthermia increases ROS generation by increasing NADPH activity and decreasing SOD activity leading to cytotoxicity in HT-22 cells. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the capacity of the asialoglycoprotein receptor on the hepatocyte-derived cell line HepG2 to exhibit an anomeric preference with respect to the D-galacto moiety on cationic liposome membrane-anchored cholesteryl-α-D-galactopyranoside (Choαgal) and cholesteryl-β-Dgalactopyranoside (Cholβgal) in cationic liposome/pGL3 plasmid DNA complexes constructed for non-viral, hepatocyte-directed gene transfer. In addition, cholesteryl-α-D-glucopyranoside (Choαglu) and cholesteryl-β-D-glucopyranoside (Cholβglu) were separately formulated into cationic liposomes at the same mole ratio (11%) to examine the C-4 epimeric selectivity of the asialoglycoprotein lectin for the glucopyranosides displayed in derived lipoplexes. Lipoplex formation was examined by gel retardation, ethidium displacement assays, and transmission electron microscopy. Plasmid DNA was shown to be fully liposome associated and maximally compacted at a liposome:DNA ratio of 6:1 (weight ratio), corresponding to a +/- charge ratio of 1.3 with complexes falling in the 80–200 nm size range, whereas at a 5:1 w/wratio [1.1 (+/-) charge ratio] lipoplexes were somewhat smaller (50–100 nm) but promoted higher transgene activity in HepG2 cells than 6:1 (w/w) lipoplexes, in the following order: Cholβgal > Cholαgal > Cholβglu = Cholαglu. Transgene activity levels in HeLa cells which lack the asialoglycoprotein receptor were approximately 10% of those achieved in HepG2 cells. Moreover, transgene activity in HepG2 cells was reduced by approximately 90% in the presence of excess asialofetuin, a ligand for the asialoglycoprotein lectin. [ABSTRACT FROM AUTHOR]

Aims: We sought to identify and optimise a universally available histological marker for pericytes in the human brain. Such a marker could be a useful tool for researchers. Further, identifying a gene expressed relatively specifically in human pericytes could provide new insights into the biological functions of this fascinating cell type. Methods: We analysed single‐cell RNA expression profiles derived from different human and mouse brain regions using a high‐throughput and low‐cost single‐cell transcriptome sequencing method called EasySci. Through this analysis, we were able to identify specific gene markers for pericytes, some of which had not been previously characterised. We then used commercially (and therefore universally) available antibodies to immunolabel the pericyte‐specific gene products in formalin‐fixed paraffin‐embedded (FFPE) human brains and also performed immunoblots to determine whether appropriately sized proteins were recognised. Results: In the EasySci data sets, highly pericyte‐enriched expression was notable for SLC6A12 and SLC19A1. Antibodies against these proteins recognised bands of approximately the correct size in immunoblots of human brain extracts. Following optimisation of the immunohistochemical technique, staining for both antibodies was strongly positive in small blood vessels and was far more effective than a PDGFRB antibody at staining pericyte‐like cells in FFPE human brain sections. In an exploratory sample of other human organs (kidney, lung, liver, muscle), immunohistochemistry did not show the same pericyte‐like pattern of staining. Conclusions: The SLC6A12 antibody was well suited for labelling pericytes in human FFPE brain sections, based on the combined results of single‐cell RNA‐seq analyses, immunoblots and immunohistochemical studies. [ABSTRACT FROM AUTHOR]

The p38 alpha mitogen-activated protein kinase (p38α) is linked to both innate and adaptive immune responses and is under investigation as a target for drug development in the context of Alzheimer's disease (AD) and other conditions with neuroinflammatory dysfunction. While preclinical data has shown that p38α inhibition can protect against AD-associated neuropathology, the underlying mechanisms are not fully elucidated. Inhibitors of p38α may provide benefit via modulation of microglial-associated neuroinflammatory responses that contribute to AD pathology. The present study tests this hypothesis by knocking out microglial p38α and assessing early-stage pathological changes. Conditional knockout of microglial p38α was accomplished in 5-month-old C57BL/6J wild-type and amyloidogenic AD model (APPswe/PS1dE9) mice using a tamoxifen-inducible Cre/loxP system under control of the Cx3cr1 promoter. Beginning at 7.5 months of age, animals underwent behavioral assessment on the open field, followed by a later radial arm water maze test and collection of cortical and hippocampal tissues at 11 months. Additional endpoint measures included quantification of proinflammatory cytokines, assessment of amyloid burden and plaque deposition, and characterization of microglia-plaque dynamics. Loss of microglial p38α did not alter behavioral outcomes, proinflammatory cytokine levels, or overall amyloid plaque burden. However, this manipulation did significantly increase hippocampal levels of soluble Aβ42 and reduce colocalization of Iba1 and 6E10 in a subset of microglia in close proximity to plaques. The data presented here suggest that rather than reducing inflammation per se, the net effect of microglial p38α inhibition in the context of early AD-type amyloid pathology is a subtle alteration of microglia-plaque interactions. Encouragingly from a therapeutic standpoint, these data suggest no detrimental effect of even substantial decreases in microglial p38α in this context. Additionally, these results support future investigations of microglial p38α signaling at different stages of disease, as well as its relationship to phagocytic processes in this particular cell-type. [ABSTRACT FROM AUTHOR]

Despite the indispensable role that astrocytes play in the neurovascular unit, few studies have investigated the functional impact of astrocyte signaling in cognitive decline and dementia related to vascular pathology. Diet-mediated induction of hyperhomocysteinemia (HHcy) recapitulates numerous features of vascular contributions to cognitive impairment and dementia (VCID). Here, we used astrocyte targeting approaches to evaluate astrocyte Ca21 dysregulation and the impact of aberrant astrocyte signaling on cerebrovascular dysfunction and synapse impairment in male and female HHcy diet mice. Two-photon imaging conducted in fully awake mice revealed activity-dependent Ca21 dysregulation in barrel cortex astrocytes under HHcy. Stimulation of contralateral whiskers elicited larger Ca21 transients in individual astrocytes of HHcy diet mice compared with control diet mice. However, evoked Ca21 signaling across astrocyte networks was impaired in HHcy mice. HHcy also was associated with increased activation of the Ca21/calcineurin-dependent transcription factor NFAT4, which has been linked previously to the reactive astrocyte phenotype and synapse dysfunction in amyloid and brain injury models. Targeting the NFAT inhibitor VIVIT to astrocytes, using adeno-associated virus vectors, led to reduced GFAP promoter activity in HHcy diet mice and improved functional hyperemia in arterioles and capillaries. VIVIT expression in astrocytes also preserved CA1 synaptic function and improved spontaneous alternation performance on the Y maze. Together, the results demonstrate that aberrant astrocyte signaling can impair the major functional properties of the neurovascular unit (i.e., cerebral vessel regulation and synaptic regulation) and may therefore represent a promising drug target for treating VCID and possibly Alzheimer's disease and other related dementias. [ABSTRACT FROM AUTHOR]