Browsing by Author "Lamb, Bruce T."
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Item A human induced pluripotent stem cell model of Alzheimer’s Disease‐associated fractalkine receptor polymorphism to assess AD‐related microglial dysfunction(Wiley, 2025-01-03) Tutrow, Kaylee; Harkin, Jade; Hernandez, Melody; Huang, Kang-Chieh S.; Bissel, Stephanie J.; Puntambekar, Shweta S.; Lamb, Bruce T.; Meyer, Jason S.; Medical and Molecular Genetics, School of MedicineBackground: Dysfunctional microglial activity has recently been identified as a potential mechanism leading to accumulation of amyloid beta and pTau and subsequent neurodegeneration in Alzheimer’s Disease. The CX3CR1/fractalkine axis serves as a mechanism for bi‐directional communication between microglia and neurons, respectively, to promote a resting, anti‐inflammatory state in microglia. Previous studies have demonstrated that deficiency in CX3CR1 signaling leads microglia to a more pro‐inflammatory phenotype, phagocytic deficits, and increased susceptibility of neurons to cell death. Additionally, the CX3CR1‐V249I polymorphism was recently identified as a potential risk allele for Alzheimer’s Disease with worsened Braak staging in post‐mortem Alzheimer’s patients. However, the role of fractalkine dysfunction in human cells and the mechanisms by which microglia with the CX3CR1‐V249I SNP contribute to neurodegeneration remain unclear. Method: To address this shortcoming, we utilized human induced pluripotent stem cells and CRISPR/Cas9 gene editing technology to elucidate the effects of the CX3CR1‐V249I polymorphism on human microglia‐like cells (hMGLs) compared to an isogenic control cell line. Isogenic control cells alongside both heterozygous and homozygous CX3CR1 V249I cell lines were differentiated in parallel to yield enriched populations of hMGLs. Resulting hMGLs were then assessed for uptake of amyloid beta 1‐42 using flow cytometry, cell death in response to cytokine starvation, changes in proliferation, and finally alterations to migratory behavior using a microfluidic chamber. Result: We demonstrate the effective differentiation of hMGLS from both isogenic control and CX3CR1‐V249I backgrounds, which express characteristic microglial markers and are functionally phagocytic. Microglia bearing the homozygous CX3CR1‐V249I allele, but not heterozygous cells, demonstrated decreased uptake of amyloid beta in vitro compared to isogenic controls. Additionally, homozygous V249I microglia demonstrated increased stress‐induced cell death, as well as altered proliferation and decreased migratory capability. Conclusion: These findings suggest that the CX3CR1‐V249I polymorphism may cause a dysfunctional microglia phenotype that may contribute to neuronal dysfunction and death. Ongoing work will expand upon the transcriptome and secretome profile of CX3CR1‐V249I microglia and elucidate how this gene variant contributes to Alzheimer’s Disease‐related neurodegeneration.Item Active PSF shaping and adaptive optics enable volumetric localization microscopy through brain sections(Springer Nature, 2018-08) Mlodzianoski, Michael J.; Cheng-Hathaway, Paul J.; Bemiller, Shane M.; McCray, Tyler J.; Liu, Sheng; Miller, David A.; Lamb, Bruce T.; Landreth, Gary E.; Huang, Fang; Anatomy and Cell Biology, IU School of MedicineApplication of single-molecule switching nanoscopy (SMSN) beyond the coverslip surface poses substantial challenges due to sample-induced aberrations that distort and blur single-molecule emission patterns. We combined active shaping of point spread functions and efficient adaptive optics to enable robust 3D-SMSN imaging within tissues. This development allowed us to image through 30-μm-thick brain sections to visualize and reconstruct the morphology and the nanoscale details of amyloid-β filaments in a mouse model of Alzheimer's disease.Item Advancements in APOE and dementia research: Highlights from the 2023 AAIC Advancements: APOE conference(Wiley, 2024) Kloske, Courtney M.; Belloy, Michael E.; Blue, Elizabeth E.; Bowman, Gregory R.; Carrillo, Maria C.; Chen, Xiaoying; Chiba-Falek, Ornit; Davis, Albert A.; Di Paolo, Gilbert; Garretti, Francesca; Gate, David; Golden, Lesley R.; Heinecke, Jay W.; Herz, Joachim; Huang, Yadong; Iadecola, Costantino; Johnson, Lance A.; Kanekiyo, Takahisa; Karch, Celeste M.; Khvorova, Anastasia; Koppes-den Hertog, Sascha J.; Lamb, Bruce T.; Lawler, Paige E.; Le Guen, Yann; Litvinchuk, Alexandra; Liu, Chia-Chen; Mahinrad, Simin; Marcora, Edoardo; Marino, Claudia; Michaelson, Danny M.; Miller, Justin J.; Morganti, Josh M.; Narayan, Priyanka S.; Naslavsky, Michel S.; Oosthoek, Marlies; Ramachandran, Kapil V.; Ramakrishnan, Abhirami; Raulin, Ana-Caroline; Robert, Aiko; Saleh, Rasha N. M.; Sexton, Claire; Shah, Nilomi; Shue, Francis; Sible, Isabel J.; Soranno, Andrea; Strickland, Michael R.; Tcw, Julia; Thierry, Manon; Tsai, Li-Huei; Tuckey, Ryan A.; Ulrich, Jason D.; van der Kant, Rik; Wang, Na; Wellington, Cheryl L.; Weninger, Stacie C.; Yassine, Hussein N.; Zhao, Na; Bu, Guojun; Goate, Alison M.; Holtzman, David M.; Neurology, School of MedicineIntroduction: The apolipoprotein E gene (APOE) is an established central player in the pathogenesis of Alzheimer's disease (AD), with distinct apoE isoforms exerting diverse effects. apoE influences not only amyloid-beta and tau pathologies but also lipid and energy metabolism, neuroinflammation, cerebral vascular health, and sex-dependent disease manifestations. Furthermore, ancestral background may significantly impact the link between APOE and AD, underscoring the need for more inclusive research. Methods: In 2023, the Alzheimer's Association convened multidisciplinary researchers at the "AAIC Advancements: APOE" conference to discuss various topics, including apoE isoforms and their roles in AD pathogenesis, progress in apoE-targeted therapeutic strategies, updates on disease models and interventions that modulate apoE expression and function. Results: This manuscript presents highlights from the conference and provides an overview of opportunities for further research in the field. Discussion: Understanding apoE's multifaceted roles in AD pathogenesis will help develop targeted interventions for AD and advance the field of AD precision medicine. Highlights: APOE is a central player in the pathogenesis of Alzheimer's disease. APOE exerts a numerous effects throughout the brain on amyloid-beta, tau, and other pathways. The AAIC Advancements: APOE conference encouraged discussions and collaborations on understanding the role of APOE.Item Aging x Environment x genetic risk for late onset Alzheimer’s disease results in alterations in cognitive function in mice independent of amyloid and tau pathology(Wiley, 2025-01-03) Williams, Sean-Paul Gerard; Santos, Diogo Francisco Silva; Haynes, Kathryn A.; Heaton, Nicholas; Hart, Jason T.; Kotredes, Kevin P.; Pandey, Ravi S.; Persohn, Scott C.; Eldridge, Kierra; Ingraham, Cynthia M.; Lloyd, Christopher D.; Wang, Nian; Sasner, Michael; Carter, Gregory W.; Territo, Paul R.; Lamb, Bruce T.; Howell, Gareth R.; Oblak, Adrian L.; Sukoff Rizzo, Stacey J.; Neurology, School of MedicineBackground: Alzheimer’s disease (AD) research has been historically dominated with studies in mouse models expressing familial AD mutations; however, the majority of AD patients have the sporadic, late‐onset form of AD (LOAD). To address this gap, the IU/JAX/PITT MODEL‐AD Consortium has focused on development of mouse models that recapitulate LOAD by combining genetic risk variants with environmental risk factors and aging to enable more precise models to evaluate potential therapeutics. The present studies were undertaken to characterize cognitive and neurophysiological phenotypes in LOAD mice. Method: Two genetic risk factors, APOE4 and Trem2*R47H, were incorporated into C57BL/6J mice with humanized amyloid‐beta to produce the LOAD2 model (JAX# 030670). Male and female LOAD2 and WT mice were exposed to ad libitum 45% high‐fat diet from 2‐months of age (LOAD2+HFD or WT+HFD, respectively) throughout their lifespan and compared to LOAD2 and WT mice on control diet (+CD). Cognitive training began at 14‐months of age using a touchscreen testing battery, similar to previously described methods (Oomen et al 2013). At the conclusion of touchscreen testing, subjects were implanted with wireless telemetry devices (DSI) for evaluation of electroencephalography (EEG) signatures. Result: All subjects met the touch‐reward association criteria. During task acquisition LOAD2+CD mice demonstrated impaired acquisition relative to WT+CD, while both LOAD2+HFD and WT+HFD failed to learn the task as indicated by accuracy less than chance (<50%); which was confirmed in a separate cohort. LOAD2+HFD mice demonstrated increased spikewave events as measured by EEG, relative to LOAD2+CD. At 18‐months of age +CD mice that met acquisition criteria were evaluated in a location discrimination task with LOAD2+CD mice demonstrating modest impairments in pattern separation relative to age‐matched WT+CD. Conclusion: These data are the first reports of cognitive deficits and neurophysiological alterations in mice with environmental x genetic risk for LOAD, independent of amyloid and tau pathology. Importantly, the present findings demonstrate the sensitivity of the translational touchscreen testing battery for detecting mild cognitive impairment in LOAD mice with corresponding neurophysiologic alterations, and extend previous characterization data for the LOAD2 model and its utility for the study of the biology of LOAD.Item Cellular players that shape evolving pathology and neurodegeneration following traumatic brain injury(Elsevier, 2018) Puntambekar, Shweta S.; Saber, Maha; Lamb, Bruce T.; Kokiko-Cochran, Olga N.; Medical and Molecular Genetics, School of MedicineTraumatic brain injury (TBI) is one of the leading causes of death and disability worldwide, and has emerged as a critical risk factor for multiple neurodegenerative diseases, particularly Alzheimer’s disease (AD). How the inflammatory cascade resulting from mechanical stress, axonal shearing and the loss of neurons and glia following initial impact in TBI, contributes to the development of AD-like disease is unclear. Neuroinflammation, characterized by blood-brain barrier (BBB) dysfunction and activation of brain-resident microglia and astrocytes, resulting in secretion of inflammatory mediators and subsequent recruitment of peripheral immune cells has been the focus of extensive research in attempts to identify drug-targets towards improving functional outcomes post TBI. While knowledge of intricate cellular interactions that shape lesion pathophysiology is incomplete, a major limitation in the field is the lack of understanding of how distinct cell types differentially alter TBI pathology. The aim of this review is to highlight functional differences between populations of bone marrow derived, infiltrating monocytes/macrophages and brain-resident microglia based on differential expression of the chemokine receptors CCR2 and CX3CR1. This review will focus on how unique subsets of mononuclear phagocytes shape TBI pathophysiology, neurotoxicity and BBB function, in a disease-stage dependent manner. Additionally, this review summarizes the role of multiple microglia and macrophage receptors, namely CCR2, CX3CR1 and Triggering Receptor Expressed on Myeloid Cells-2 (TREM2) in pathological neuroinflammation and neurodegeneration vs. recovery following TBI. TREM2 has been implicated in mediating AD-related pathology, and variants in TREM2 are particularly important due to their correlation with exacerbated neurodegeneration. Finally, this review highlights behavioral outcomes associated with microglial vs. macrophage variances, the need for novel treatment strategies that target unique subpopulations of peripheral macrophages, and the importance of development of therapeutics to modulate inflammatory functions of brain-resident microglia at specific stages of TBI.Item Characterization of the A1527G variant of ABCA7 in an animal model for late‐onset Alzheimer’s disease(Wiley, 2025-01-03) Bernabe, Cristian S.; Kotredes, Kevin P.; Pandey, Ravi S.; Carter, Gregory W.; Sasner, Michael; Oblak, Adrian L.; Howell, Gareth R.; Lamb, Bruce T.; Territo, Paul R.; MODEL-AD consortium; Medicine, School of MedicineBackground: Genome‐wide association studies (GWAS) identified the ATP binding cassette subfamily A member 7 (ABCA7) gene as increasing risk for Alzheimer’s disease (AD). ABC proteins transport various molecules across extra and intra‐cellular membranes. ABCA7 is part of the ABC1 subfamily and is expressed in brain cells including neurons, astrocytes, microglia, endothelial cells and pericytes. However, the mechanisms by which variations in ABCA7 increase risk for AD are not known. Method: The IU/JAX/PITT MODEL‐AD Center identified the A1527G variant in ABCA7 (ABCA7*A1527G) as a putative LOAD risk factor. CRISPR/CAS9 was first used to introduce Abca7*A1527G variant to B6.APOE4.Trem2*R47H (LOAD1) mice to assess the transcriptional profiling on brain hemispheres from different ages. The Abca7*A1527G was then incorporated into B6.APOE4.Trem2*R47H.hAb (LOAD2) mice to further evaluate its contribution to LOAD. Female and male LOAD2.Abca7*A1527G and LOAD2 mice were characterized at 4, 12, and 24 months using the following phenotyping pipeline: behavior, PET/CT, multi‐omics, fluid biomarkers, electrophysiology, cognition, and neuropathology. Result: Brain transcriptional profiling showed that Abca7*A1527G induced changes in gene expression that are similar to some of those observed in human AD (e.g., granulocyte/neutrophil migration, and insulin receptor signaling). LOAD2.Abca7*A1527G showed no aging cognitive deficit but did show significant sex‐ and region‐dependent increases in brain glycolysis paralleled by reduced tissue perfusion yielding progressive age‐related uncoupled phenotypes between 4‐12 and 4‐24 months. While multi‐resolution consensus clustering of regional covariance matrices revealed an increase in cluster number and organization in LOAD2.Abca7*A1527G over LOAD2 for both sexes at 4 months, the cluster number and complexity were reduced by 24 months. Importantly, LOAD2.Abca7*A1527G, but not LOAD2, displayed a similar age‐dependent reduction in cluster number for both sexes. Consistent with the uncoupled phenotype, IL6, IL10, and TNFα were elevated in plasma with genotype, but were not age dependent. Conversely, brain levels of IL4, IL12, TNFα, and CXCL1 were decreased, whereas IL2 and IL10 were elevated in LOAD2.Abca7*A1527G relative to LOAD2. Lastly, assessment of plasma levels of Ab40‐Ab42 revealed an age‐dependent increase in both genotypes. Conclusion: Data collected to date support a model whereby variations in ABCA7 exert risk for AD through interactions between cerebrovasculature, microglia, and peripheral immune cells.Item Characterizing Molecular and Synaptic Signatures in mouse models of Late-Onset Alzheimer’s Disease Independent of Amyloid and Tau Pathology(bioRxiv, 2023-12-20) Kotredes, Kevin P.; Pandey, Ravi S.; Persohn, Scott; Elderidge, Kierra; Burton, Charles P.; Miner, Ethan W.; Haynes, Kathryn A.; Santos, Diogo Francisco S.; Williams, Sean-Paul; Heaton, Nicholas; Ingraham, Cynthia M.; Lloyd, Christopher; Garceau, Dylan; O’Rourke, Rita; Herrick, Sarah; Rangel-Barajas, Claudia; Maharjan, Surendra; Wang, Nian; Sasner, Michael; Lamb, Bruce T.; Territo, Paul R.; Sukoff Rizzo, Stacey J.; Carter, Gregory W.; Howell, Gareth R.; Oblak, Adrian L.; Medical and Molecular Genetics, School of MedicineIntroduction: MODEL-AD is creating and distributing novel mouse models with humanized, clinically relevant genetic risk factors to more accurately mimic LOAD than commonly used transgenic models. Methods: We created the LOAD2 model by combining APOE4, Trem2*R47H, and humanized amyloid-beta. Mice aged up to 24 months were subjected to either a control diet or a high-fat/high-sugar diet (LOAD2+HFD) from two months of age. We assessed disease-relevant outcomes, including in vivo imaging, biomarkers, multi-omics, neuropathology, and behavior. Results: By 18 months, LOAD2+HFD mice exhibited cortical neuron loss, elevated insoluble brain Aβ42, increased plasma NfL, and altered gene/protein expression related to lipid metabolism and synaptic function. In vivo imaging showed age-dependent reductions in brain region volume and neurovascular uncoupling. LOAD2+HFD mice also displayed deficits in acquiring touchscreen-based cognitive tasks. Discussion: Collectively the comprehensive characterization of LOAD2+HFD mice reveal this model as important for preclinical studies that target features of LOAD independent of amyloid and tau.Item Comprehensive Evaluation of the 5XFAD Mouse Model for Preclinical Testing Applications: A MODEL-AD Study(Frontiers Media, 2021-07-23) Oblak, Adrian L.; Lin, Peter B.; Kotredes, Kevin P.; Pandey, Ravi S.; Garceau, Dylan; Williams, Harriet M.; Uyar, Asli; O’Rourke, Rita; O’Rourke, Sarah; Ingraham, Cynthia; Bednarczyk, Daria; Belanger, Melisa; Cope, Zackary A.; Little, Gabriela J.; Williams, Sean-Paul G.; Ash, Carl; Bleckert, Adam; Ragan, Tim; Logsdon, Benjamin A.; Mangravite, Lara M.; Sukoff Rizzo, Stacey J.; Territo, Paul R.; Carter, Gregory W.; Howell, Gareth R.; Sasner, Michael; Lamb, Bruce T.; Radiology and Imaging Sciences, School of MedicineThe ability to investigate therapeutic interventions in animal models of neurodegenerative diseases depends on extensive characterization of the model(s) being used. There are numerous models that have been generated to study Alzheimer’s disease (AD) and the underlying pathogenesis of the disease. While transgenic models have been instrumental in understanding AD mechanisms and risk factors, they are limited in the degree of characteristics displayed in comparison with AD in humans, and the full spectrum of AD effects has yet to be recapitulated in a single mouse model. The Model Organism Development and Evaluation for Late-Onset Alzheimer’s Disease (MODEL-AD) consortium was assembled by the National Institute on Aging (NIA) to develop more robust animal models of AD with increased relevance to human disease, standardize the characterization of AD mouse models, improve preclinical testing in animals, and establish clinically relevant AD biomarkers, among other aims toward enhancing the translational value of AD models in clinical drug design and treatment development. Here we have conducted a detailed characterization of the 5XFAD mouse, including transcriptomics, electroencephalogram, in vivo imaging, biochemical characterization, and behavioral assessments. The data from this study is publicly available through the AD Knowledge Portal.Item Contributions of heavy metal exposure to late‐onset Alzheimer’s disease(Wiley, 2025-01-03) Kotredes, Kevin P.; Minaeva, Olga; Pandey, Ravi S.; Moncaster, Juliet A.; Lamb, Bruce T.; Carter, Gregory W.; Goldstein, Lee E.; Howell, Gareth R.; Medical and Molecular Genetics, School of MedicineBackground: Late‐onset Alzheimer’s disease (LOAD) is the leading cause of dementia and a major contributor to increased mortality. Recent human datasets have revealed many LOAD genetic risk factors that are correlated with the degree of AD burden. Further, the complexity and heterogeneity of LOAD appears to be promoted by interactions between genetics and environmental factors such as diet, sedentary behavior, and exposure to toxicants, like lead (Pb), cadmium (Cd), and arsenic (As). While the neurotoxicants‐LOAD association is known, the molecular mechanisms modulated by these gene‐environmental interactions are unknown. Here we test the hypothesis that heavy metal exposure induces cerebrovascular deficits, neuroinflammation, and brain biometal dyshomeostasis which exacerbate AD‐associated brain pathologies in next‐generation mouse models of LOAD. Examination of these gene‐environmental (“exposome”) interactions provides essential insight into the heterogeneity observed in human disease and may uncover potentially modifiable mechanisms that mediate AD pathogenesis. Method: Young and aged mice from novel polygenic strains expressing LOAD risk alleles (APOE4, Trem2, APP, Mthfr, Abca7) were exposed to heavy metal toxicants in drinking water. Toxicants and endogenous biometals were assayed by ICP‐mass spectrometry in the brain, blood, and urine. Transcriptional profiling of brains revealed specific changes in human‐aligned, LOAD‐related gene expression networks indicating mechanisms of disease progression. Neuropathology was evaluated with LOAD‐relevant phenotypes, including amyloid burden, glial activity, and neuron loss. Result: Neurotoxicants were detected in all tissue samples collected. Pb, Cd, and As accumulated in the brain and altered expression of LOAD‐relevant genes in a toxicant‐specific manner, including a decrease in Vgf and an increase in App. Reduced VGF expression has been observed and reported in all four independent AMP‐AD studies and nominated as a key therapeutic target in each and APP encodes amyloid precursor protein (APP) from which the Aβ peptides are generated. Conclusion: Pb, Cd, and As exposure is common, especially in disadvantaged populations (urban, rural), raising concern about LOAD risk disparities, socioeconomic/racial inequities, and environmental justice. These experiments provide critical feedback related to the impact of the “exposome” in the aging, disease progression, and gene expression of novel preclinical LOAD models. Collectively these data suggest a direct effect of neurotoxicant exposure related to LOAD progression.Item Control of the temporal development of Alzheimer's disease pathology by the MR1/MAIT cell axis(BMC, 2023-03-21) Wyatt‑Johnson, Season K.; Kersey, Holly N.; Codocedo, Juan F.; Newell, Kathy L.; Landreth, Gary E.; Lamb, Bruce T.; Oblak, Adrian L.; Brutkiewicz, Randy R.; Microbiology and Immunology, School of MedicineBackground: Neuroinflammation is an important feature of Alzheimer's disease (AD). Understanding which aspects of the immune system are important in AD may lead to new therapeutic approaches. We study the major histocompatibility complex class I-related immune molecule, MR1, which is recognized by an innate-like T cell population called mucosal-associated invariant T (MAIT) cells. Methods: Having found that MR1 gene expression is elevated in the brain tissue of AD patients by mining the Agora database, we sought to examine the role of the MR1/MAIT cell axis in AD pathology. Brain tissue from AD patients and the 5XFAD mouse model of AD were used to analyze MR1 expression through qPCR, immunofluorescence, and flow cytometry. Furthermore, mice deficient in MR1 and MAIT cells were crossed with the 5XFAD mice to produce a model to study how the loss of this innate immune axis alters AD progression. Moreover, 5XFAD mice were also used to study brain-resident MAIT cells over time. Results: In tissue samples from AD patients and 5XFAD mice, MR1 expression was substantially elevated in the microglia surrounding plaques vs. those that are further away (human AD: P < 0.05; 5XFAD: P < 0.001). In 5XFAD mice lacking the MR1/MAIT cell axis, the development of amyloid-beta plaque pathology occurred at a significantly slower rate than in those mice with MR1 and MAIT cells. Furthermore, in brain tissue from 5XFAD mice, there was a temporal increase in MAIT cell numbers (P < 0.01) and their activation state, the latter determined by detecting an upregulation of both CD69 (P < 0.05) and the interleukin-2 receptor alpha chain (P < 0.05) via flow cytometry. Conclusions: Together, these data reveal a previously unknown role for the MR1/MAIT cell innate immune axis in AD pathology and its potential utility as a novel therapeutic target.