Browsing by Author "Rogers, Colin B."

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    A high-throughput single-cell RNA expression profiling method identifies human pericyte markers
    (Wiley, 2023) Sziraki, Andras; Zhong, Yu; Neltner, Allison M.; Niedowicz, Dana; Rogers, Colin B.; Wilcock, Donna M.; Nehra, Geetika; Neltner, Janna H.; Smith, Rebecca R.; Hartz, Anika M.; Cao, Junyue; Nelson, Peter T.; Neurology, School of Medicine
    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.
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    Atorvastatin rescues hyperhomocysteinemia-induced cognitive deficits and neuroinflammatory gene changes
    (BMC, 2023-09-01) Weekman, Erica M.; Johnson, Sherika N.; Rogers, Colin B.; Sudduth, Tiffany L.; Xie, Kevin; Qiao, Qi; Fardo, David W.; Bottiglieri, Teodoro; Wilcock, Donna M.; Neurology, School of Medicine
    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.
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    Glial changes as result of cerebral amyloid angiopathy progression
    (Wiley, 2025-01-03) Krick, Katelynn E.; Johnson, Sherika N.; Rogers, Colin B.; Sudduth, Tiffany L.; Weekman, Erica M.; Wilcock, Donna M.; Anatomy, Cell Biology and Physiology, School of Medicine
    Background: Cerebral Amyloid Angiopathy (CAA) occurs at the intersection of Alzheimer’s disease and vascular contributions to cognitive impairment and dementia (VCID). In the human brain it occurs when amyloid beta (Aβ) aggregates in small/medium‐sized cerebral blood vessels, which contribute to hypoperfusion and cognitive decline by altering vascular function and integrity. The current study seeks to track the progression of CAA and associated neuroinflammation and glial cell changes in Tg2576 mice. Method: Tg2576 mice were aged to 8‐, 14‐, 20‐, and 27‐months and assessed for CAA pathology via histology. Gene expression was evaluated in hippocampal tissue by qPCR and posterior cortex by nanostring (ncounter Mouse Neuroinflammation and Mouse CVD Pathophysiology panels; in progress) to compare 8‐ and 20‐month APP and wildtype groups. Protein expression was evaluated via digital spatial profiling in the same APP mice, grouped by age or CAA presence compared to wildtype controls. CAA presence was defined as Aβ surrounding lectin‐positive vessels. Regions of interest were categorized as either positive or negative for CAA based on this criterion. Result: Congophillic plaque deposition along the vasculature increased in width, length, and area in a time dependent manner in both the frontal cortex and hippocampus. Astrocyte marker GFAP and proinflammatory receptor TNFR1 gene expression both increased at 20 months compared to 8 months in the APP group. Of the protein profile assessed (Mouse Neural Cell Profiling and Mouse Glial Cell Subtyping), the most consistent changes were found in astrocyte markers. Both Aldh1l1 and S100B were increased at 20 months compared to 8 months of age in both APP and WT mice. GFAP protein expression was found to increase with both age and CAA. Conclusion: This study showed increased vascular amyloid deposition and astrocyte gene and protein expression over time, further supporting a role for astrocytes in etiology and/or reaction to CAA.
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    Hyperhomocysteinemia-induced VCID results in visual deficits, reduced neuroinflammation and vascular alterations in the retina
    (Springer Nature, 2025-01-30) Weekman, Erica M.; Rogers, Colin B.; Sudduth, Tiffany L.; Wilcock, Donna M.; Neurology, School of Medicine
    Over recent years, the retina has been increasingly investigated as a potential biomarker for dementia. A number of studies have looked at the effect of Alzheimer's disease (AD) pathology on the retina and the associations of AD with visual deficits. However, while OCT-A has been explored as a biomarker of cerebral small vessel disease (cSVD), studies identifying the specific retinal changes and mechanisms associated with cSVD are lacking. Using our model of hyperhomocysteinemia-induced cSVD, we aimed to identify the effects of cSVD on visual sensitivity and cognition, retinal glial and vascular cells, and neuroinflammatory and cardiovascular gene expression changes. We placed C57Bl6/SJL mice on a HHcy-inducing diet, a model that has been well characterized to have vascular pathologies in the brain similar to pathologic cSVD. After 14 weeks on diet, mice underwent the Visual-Stimuli 4-arm Maze to identify visual deficits. Whole mount retinas were stained for vessels, microglia and astrocytes to identify glial and vascular changes. Finally, neuroinflammatory and cardiovascular gene expression was measured using NanoString's nCounter system. Ultimately, HHcy led to visual changes that specifically affected the reaction to blue and white light, slightly decreased vascular volume and significantly decreased interaction of microglia with the vasculature, as well as downregulation of inflammatory and vascular genes. These changes provide novel insights and reproduce some prior observations. These studies highlight retinal changes in association with cSVD and serve as a precaution when interpreting vision-dependent cognitive testing of cSVD models.
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    Induction of VCID via hyperhomocysteinemia leads to vision and retina changes in mice
    (Wiley, 2025-01-03) Weekman, Erica M.; Rogers, Colin B.; Sudduth, Tiffany L.; Wilcock, Donna M.; Neurology, School of Medicine
    Background: Diagnosis of Alzheimer’s disease (AD) via MRI is costly and can be limited by regional availability. With the recent advancements and discovery of amyloid in the retina, diagnosis of AD and the effect of AD pathology on the retina is becoming well characterized. However, the prevalence of vascular contributions to cognitive impairment and dementia (VCID) and its effects on the retina are less well known. With the retina being a highly vascularized tissue and the considerable overlap of AD with VCID, it is imperative to understand the effect of VCID on vision. Method: We placed 6‐month‐old mice on a diet deficient in B vitamins and enriched in methionine to induce hyperhomocysteinemia (HHcy). HHcy is a risk factor for VCID, stroke and AD, and has been well characterized in our lab. After 14 weeks on diet, mice underwent the Visual‐Stimuli 4‐arm Maze (ViS4M) to identify visual and cognitive abnormalities. After behavior, brains and eyes were harvested with the left eye fixed in 4% PFA for 24hrs and the right eye flash frozen for RNA extraction. The fixed retina was flat mounted and stained for vessels, GFAP, and IBA‐1 and the flash frozen retina was used for RNA isolation and NanoString analysis. Result: Over the seven days the mice were tested on the ViS4M, the mice on the HHcy diet showed impaired cognition and altered colored arm entries compared to control mice. HHcy mice made more 2 arm alternations than 3 or 4 arm alternations, suggesting diminished exploration. When we determined their arm transitions, we saw that the HHcy mice tended to avoid the blue arm, suggesting sensitivity to blue light. In the retina, we saw slightly less vessel volume in the HHcy diet mice along with reduced coverage of vessels by microglia and astrocytes combined. Conclusion: The high prevalence of VCID with AD along with the impact of AD pathology on the eye makes it critical to understand the effect of VCID on the retina. In our model of HHcy induced VCID, we determined that HHcy does impair both cognition and vision and affects vessels within the retina.