Browsing by Author "Weekman, Erica M."
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Item Acute Communication Between Microglia and Nonparenchymal Immune Cells in the Anti-Aβ Antibody-Injected Cortex(Society for Neuroscience, 2025-01-29) Foley, Kate E.; Weekman, Erica M.; Krick, Katelynn E.; Johnson, Sherika N.; Sudduth, Tiffany L.; Wilcock, Donna M.; Neurology, School of MedicineAnti-Aβ immunotherapy use to treat Alzheimer's disease is on the rise. While anti-Aβ antibodies provide hope in targeting Aβ plaques in the brain, there still remains a lack of understanding regarding the cellular responses to these antibodies in the brain. In this study, we sought to identify the acute effects of anti-Aβ antibodies on immune responses. To determine cellular changes due to anti-Aβ antibody exposure, we intracranially injected 14 mo APP male and female mice with anti-Aβ IgG1 (6E10) or control IgG1 into the cortex. After 24 h or 3 d, we harvested the cortex and performed a glial cell-enriched preparation for single-cell sequencing. Cell types, proportions, and cell-to-cell signaling were evaluated between the two injection conditions and two acute timepoints. We identified 23 unique cell clusters including microglia, astrocytes, endothelial cells, neurons, oligos/OPCs, immune cells, and unknown. The anti-Aβ antibody-injected cortices revealed more ligand-receptor (L-R) communications between cell types, as well as stronger communications at only 24 h. At 3 d, while there were more L-R communications for the anti-Aβ antibody condition, the strength of these connections was stronger in the control IgG condition. We also found evidence of an initial and strong communication emphasis in microglia-to-nonparenchymal immune cells at 24 h, specifically in the TGFβ signaling pathway. We identify several pathways that are specific to anti-Aβ antibody exposure at acute timepoints. These data lay the groundwork for understanding the brain's unique response to anti-Aβ antibodies.Item Acute communication between microglia and other immune cells in the anti‐Aβ antibody injected cortex(Wiley, 2025-01-03) Foley, Kate E.; Krick, Katelynn E.; Weekman, Erica M.; Wilcock, Donna M.; Neurology, School of MedicineBackground: Anti‐Aβ immunotherapy use to treat Alzheimer’s disease is on the rise. While anti‐Aβ antibodies provide hope in targeting Aβ plaques in the brain, a major side effect of amyloid‐related imaging abnormalities (ARIA) persists with no known cause. As severe ARIA is typically seen within the first few infusions in human clinical trials, we sought to identify acute effects of anti‐Aβ antibody on brain. Method: To determine cellular changes due to anti‐Aβ antibody exposure, we intracranially injected 14mo APP male and female mice with anti‐Aβ IgG1 (6E10) or control IgG1 into the cortex. After 24hrs or 3days, we harvested the cortex and performed a glial cell enriched preparation for single cell sequencing. Cell types, proportions, and cell‐to‐cell signaling was evaluated between the two injection conditions and two acute timepoints. Result: We identified 23 unique cell clusters including microglia, astrocytes, endothelial cells, neurons, oligos/OPCs, immune cells, and unknown. The anti‐Aβ antibody injected cortices revealed more ligand‐receptor communications between cell types, as well as stronger communications at 24hrs. At 3days, while there were more L‐R communications for the anti‐Aβ antibody condition, the strength of these connections was stronger in the control IgG condition. Specific pathways such as CD48 and PD‐L1 were enriched in the anti‐Aβ antibody condition, but not the control IgG condition in microglia‐to‐microglia communication. We also found evidence of an initial and strong communication emphasis in microglia‐to‐peripheral immune cells at 24hrs, specifically in the TGFβ signaling pathway. Additionally, we found that peripheral immune cells that were exposed to anti‐Aβ antibody failed to signal via the TNF pathway, which was strongly enriched in the control IgG condition at both timepoints. Conclusion: We identify several pathways that differ between anti‐Aβ antibody and control IgG injections at acute timepoints. These data lay the groundwork for understanding the brain’s unique response to anti‐Aβ antibody and its predisposition to ARIA.Item Alzheimer's disease and inflammatory biomarkers positively correlate in plasma in the UK‐ADRC cohort(Wiley, 2024) Foley, Kate E.; Winder, Zachary; Sudduth, Tiffany L.; Martin, Barbara J.; Nelson, Peter T.; Jicha, Gregory A.; Harp, Jordan P.; Weekman, Erica M.; Wilcock, Donna M.; Neurology, School of MedicineIntroduction: Protein-based plasma assays provide hope for improving accessibility and specificity of molecular diagnostics to diagnose dementia. Methods: Plasma was obtained from participants (N = 837) in our community-based University of Kentucky Alzheimer's Disease Research Center cohort. We evaluated six Alzheimer's disease (AD)- and neurodegeneration-related (Aβ40, Aβ42, Aβ42/40, p-tau181, total tau, and NfLight) and five inflammatory biomarkers (TNF𝛼, IL6, IL8, IL10, and GFAP) using the SIMOA-based protein assay platform. Statistics were performed to assess correlations. Results: Our large cohort reflects previous plasma biomarker findings. Relationships between biomarkers to understand AD-inflammatory biomarker correlations showed significant associations between AD and inflammatory biomarkers suggesting peripheral inflammatory interactions with increasing AD pathology. Biomarker associations parsed out by clinical diagnosis (normal, MCI, and dementia) reveal changes in strength of the correlations across the cognitive continuum. Discussion: Unique AD-inflammatory biomarker correlations in a community-based cohort reveal a new avenue for utilizing plasma-based biomarkers in the assessment of AD and related dementias. Highlights: Large community cohorts studying sex, age, and APOE genotype effects on biomarkers are few. It is unknown how biomarker-biomarker associations vary through aging and dementia. Six AD (Aβ40, Aβ42, Aβ42/40, p-tau181, total tau, and NfLight) and five inflammatory biomarkers (TNFα, IL6, IL8, IL10, and GFAP) were used to examine associations between biomarkers. Plasma biomarkers suggesting increasing cerebral AD pathology corresponded to increases in peripheral inflammatory markers, both pro-inflammatory and anti-inflammatory. Strength of correlations, between pairs of classic AD and inflammatory plasma biomarker, changes throughout cognitive progression to dementia.Item 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 MedicineBackground: 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.Item Cerebrovascular pathology and neurovascular coupling impairment in aged‐mouse model of Alzheimer’s disease(Wiley, 2025-01-09) Promkan, Moltira; Phikulthong, Kamonchat; Kimseng, Rungruedee; Pauss, Kate; Lee, Tiffany; Weekman, Erica M.; Nelson, Peter T.; Wilcock, Donna M.; Sompol, Pradoldej; Neurology, School of MedicineBackground: Vascular pathology profoundly comorbid with AD pathology could worsen disease progression and reduce treatment efficacy. Knowledge of small vessels and cerebrovascular function in AD mouse models is limited. Investigating vascular related aspects for preclinical AD studies is essential for biomarker development and treatment trials. Therefore, we aim to characterize cerebrovascular amyloid angiopathy (CAA), vascular degeneration, and cerebrovascular function in an aged Tg2576 mouse model of AD. Method: WT and Tg2576 (∼ 2 years of age) were housed in a reversed light cycle room. Cranial window surgery and cranial window installation were performed. After 3 weeks of recovery, the animals were acclimated to an intravital multiphoton imaging platform. To visualize beta‐amyloid in the brain, Methoxy‐X04 (10mg/kg) was injected the day before the imaging. Cerebrovasculature was visualized by intravascular retro‐orbital injection of rhodamine‐dextran (5% V/W in saline). This procedure was done while the animals were under anesthesia and securely head‐fixed prior to the imaging. Z‐stack imaging was performed, and vascular structure was analyzed by using FIJI or ImageJ. Neurovascular coupling was performed to investigate vascular function in awake mice. While imaging penetrating arteriole, air‐puff stimulation of contralateral whiskers was conducted and increased vascular diameter is used as an indicator of hyperemic neurovascular function. Result: Investigation of cerebrovascular pathology including CAA, vascular straightness, and vascular blebbing are ongoing. During whisker stimulation, vascular diameter was relatively reduced in Tg2576 compared to WT control mice. Conclusion: Aged Tg2576 exhibits comorbidity of amyloid plaques, cerebral amyloid angiopathy, small vessel pathology and cerebrovascular dysfunction similar to human brain. This aged Tg2576 could be used as a preclinical translational mixed vascular/AD model.Item 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 MedicineBackground: 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.Item 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 MedicineOver 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.Item 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 MedicineBackground: 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.Item Mechanisms of ARIA: is it time to focus on the unique immune environment of the neurovascular unit?(BMC, 2023-10-20) Foley, Kate E.; Weekman, Erica M.; Wilcock, Donna M.; Neurology, School of MedicineItem Understanding the cellular responses to anti‐Abeta antibodies to gain insights into mechanisms of ARIA(Wiley, 2025-01-03) Foley, Kate E.; Weekman, Erica M.; Wilcock, Donna M.; Neurology, School of MedicineAnti‐amyloid immunotherapy holds great promise for our patients and their families as the first disease‐modifying therapy for the treatment of Alzheimer’s disease (AD) to be approved. Positive clinical trials for lecanamab and donanemab showed significant and rapid lowering of brain amyloid burden and a significant slowing of cognitive decline. Amyloid‐related imaging abnormalities (ARIA) in the form of vasogenic edema (ARIA‐E) and micro ‐ and macro‐ hemorrhages (ARIA‐H) remain the major obstacle to broad use of these agents. Significant cerebrovascular pathology precludes treatment due to enhanced risk of ARIA. In addition, it is known that ApoE4 carriers are at a significantly increased risk of ARIA incidence, with 25‐40% of homozygotes developing ARIA. Understanding the mechanisms underlying ARIA is of critical importance to increase safety and broaden the use of anti‐amyloid immunotherapy. Using mouse models of amyloid deposition, we have performed systemic and intracranial anti‐beta‐amyloid antibody administration to study the potential mechanisms of both amyloid clearance and cerebrovascular disruptions that lead to ARIA. We have found that microglial activation is present along the vessels that are laden with cerebral amyloid angiopathy (CAA). Furthermore, coincident with microhemorrhage occurrence is increased expression and activity of matrix metalloproteinases (MMPs) MMP9 and MMP3. MMPs are known to degrade basement membranes and tight junction proteins that could lead to disruption of the blood‐brain barrier and, ultimately, edema and hemorrhage. in fact, it has long been understood that MMP9 plays a critical role in the hemorrhagic transformation of ischemic stroke. We have performed single‐cell transcriptomic analysis to examine the glial responses following a single anti‐amyloid immunotherapy and we find significant microglial population shifts and also enhanced signaling from microglia to perivascular macrophages, potentially implicating these cells as a key player in the development of ARIA. Ultimately, discovering the mechanisms of ARIA will result in the development of safer, next‐generation antibody therapy that has reduced ARIA risk, and also could lead to the identification of adjunct treatments that can be co‐administered with the anti‐amyloid immunotherapy to prevent the occurrence of ARIA in those at risk.