IU Indianapolis ScholarWorks :: Browsing by Author "Bissel, Stephanie J."

Browsing by Author "Bissel, Stephanie J."

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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 Medicine
Background: 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.
Age-Related Pathology Associated with H1N1 A/California/07/2009 Influenza Virus Infection
(Elsevier, 2019-12) Bissel, Stephanie J.; Carter, Chalise E.; Wang, Guoji; Johnson, Scott K.; Lashua, Lauren P.; Kelvin, Alyson A.; Wiley, Clayton A.; Ghedin, Elodie; Ross, Ted M.; Medical and Molecular Genetics, School of Medicine
Influenza virus infection causes a spectrum of diseases, ranging from mild upper respiratory tract infection to severe lower respiratory tract infection, that can lead to diffuse alveolar damage, interstitial and airspace inflammation, or acute respiratory failure. Mechanisms instructing disease severity are not completely understood, but host, viral, and bacterial factors influence disease outcome. With age being one host factor associated with a higher risk of severe influenza, we investigated regional pulmonary distribution and severity of pneumonia after 2009 H1N1 influenza virus infection in newly weaned, adult, and aged ferrets to better understand age-dependent susceptibility and pathology. Aged ferrets exhibited greater weight loss and higher rates of mortality than adult ferrets, whereas most newly weaned ferrets did not lose weight but had a lack of weight gain. Newly weaned ferrets exhibited minimal pneumonia, whereas adult and aged ferrets had a spectrum of pneumonia severity. Influenza virus-induced pneumonia peaked earliest in adult ferrets, whereas aged ferrets had delayed presentation. Bronchial severity differed among groups, but bronchial pathology was comparable among all cohorts. Alveolar infection was strikingly different among groups. Newly weaned ferrets had little alveolar cell infection. Adult and aged ferrets had alveolar infection, but aged ferrets were unable to clear infection. These different age-related pneumonia and infection patterns suggest therapeutic strategies to treat influenza should be tailored contingent on age.
Genetic Variants of Phospholipase C-γ2 Alter the Phenotype and Function of Microglia and Confer Differential Risk for Alzheimer’s Disease
(Elsevier, 2023) Tsai, Andy P.; Dong, Chuanpeng; Lin, Peter Bor-Chian; Oblak, Adrian L.; Di Prisco, Gonzalo Viana; Wang, Nian; Hajicek, Nicole; Carr, Adam J.; Lendy, Emma K.; Hahn, Oliver; Atkins, Micaiah; Foltz, Aulden G.; Patel, Jheel; Xu, Guixiang; Moutinho, Miguel; Sondek, John; Zhang, Qisheng; Mesecar, Andrew D.; Liu, Yunlong; Atwood, Brady K.; Wyss-Coray, Tony; Nho, Kwangsik; Bissel, Stephanie J.; Lamb, Bruce T.; Landreth, Gary E.; Medical and Molecular Genetics, School of Medicine
Genetic association studies have demonstrated the critical involvement of the microglial immune response in Alzheimer's disease (AD) pathogenesis. Phospholipase C-gamma-2 (PLCG2) is selectively expressed by microglia and functions in many immune receptor signaling pathways. In AD, PLCG2 is induced uniquely in plaque-associated microglia. A genetic variant of PLCG2, PLCG2P522R, is a mild hypermorph that attenuates AD risk. Here, we identified a loss-of-function PLCG2 variant, PLCG2M28L, that confers an increased AD risk. PLCG2P522R attenuated disease in an amyloidogenic murine AD model, whereas PLCG2M28L exacerbated the plaque burden associated with altered phagocytosis and Aβ clearance. The variants bidirectionally modulated disease pathology by inducing distinct transcriptional programs that identified microglial subpopulations associated with protective or detrimental phenotypes. These findings identify PLCG2M28L as a potential AD risk variant and demonstrate that PLCG2 variants can differentially orchestrate microglial responses in AD pathogenesis that can be therapeutically targeted.
Infiltration of inflammatory macrophages and neutrophils and widespread pyroptosis in lung drive influenza lethality in nonhuman primates
(Public Library of Science, 2022-03-10) Corry, Jacqueline; Kettenburg, Gwenddolen; Upadhyay, Amit A.; Wallace, Megan; Marti, Michelle M.; Wonderlich, Elizabeth R.; Bissel, Stephanie J.; Goss, Kyndal; Sturgeon, Timothy J.; Watkins, Simon C.; Reed, Douglas S.; Bosinger, Steven E.; Barratt-Boyes, Simon M.; Medical and Molecular Genetics, School of Medicine
Severe influenza kills tens of thousands of individuals each year, yet the mechanisms driving lethality in humans are poorly understood. Here we used a unique translational model of lethal H5N1 influenza in cynomolgus macaques that utilizes inhalation of small-particle virus aerosols to define mechanisms driving lethal disease. RNA sequencing of lung tissue revealed an intense interferon response within two days of infection that resulted in widespread expression of interferon-stimulated genes, including inflammatory cytokines and chemokines. Macaques with lethal disease had rapid and profound loss of alveolar macrophages (AMs) and infiltration of activated CCR2+ CX3CR1+ interstitial macrophages (IMs) and neutrophils into lungs. Parallel changes of AMs and neutrophils in bronchoalveolar lavage (BAL) correlated with virus load when compared to macaques with mild influenza. Both AMs and IMs in lethal influenza were M1-type inflammatory macrophages which expressed neutrophil chemotactic factors, while neutrophils expressed genes associated with activation and generation of neutrophil extracellular traps (NETs). NETs were prominent in lung and were found in alveolar spaces as well as lung parenchyma. Genes associated with pyroptosis but not apoptosis were increased in lung, and activated inflammatory caspases, IL-1β and cleaved gasdermin D (GSDMD) were present in bronchoalveolar lavage fluid and lung homogenates. Cleaved GSDMD was expressed by lung macrophages and alveolar epithelial cells which were present in large numbers in alveolar spaces, consistent with loss of epithelial integrity. Cleaved GSDMD colocalized with viral NP-expressing cells in alveoli, reflecting pyroptosis of infected cells. These novel findings reveal that a potent interferon and inflammatory cascade in lung associated with infiltration of inflammatory macrophages and neutrophils, elaboration of NETs and cell death by pyroptosis mediates lethal H5N1 influenza in nonhuman primates, and by extension humans. These innate pathways represent promising therapeutic targets to prevent severe influenza and potentially other primary viral pneumonias in humans.
Network analysis identifies strain-dependent response to tau and tau seeding-associated genes
(Rockefeller University Press, 2023) Acri, Dominic J.; You, Yanwen; Tate, Mason D.; Karahan, Hande; Martinez, Pablo; McCord, Brianne; Sharify, A. Daniel; John, Sutha; Kim, Byungwook; Dabin, Luke C.; Philtjens, Stéphanie; Wijeratne, H. R. Sagara; McCray, Tyler J.; Smith, Daniel C.; Bissel, Stephanie J.; Lamb, Bruce T.; Lasagna-Reeves, Cristian A.; Kim, Jungsu; Anatomy, Cell Biology and Physiology, School of Medicine
Previous research demonstrated that genetic heterogeneity is a critical factor in modeling amyloid accumulation and other Alzheimer's disease phenotypes. However, it is unknown what mechanisms underlie these effects of genetic background on modeling tau aggregate-driven pathogenicity. In this study, we induced tau aggregation in wild-derived mice by expressing MAPT. To investigate the effect of genetic background on the action of tau aggregates, we performed RNA sequencing with brains of C57BL/6J, CAST/EiJ, PWK/PhJ, and WSB/EiJ mice (n = 64) and determined core transcriptional signature conserved in all genetic backgrounds and signature unique to wild-derived backgrounds. By measuring tau seeding activity using the cortex, we identified 19 key genes associated with tau seeding and amyloid response. Interestingly, microglial pathways were strongly associated with tau seeding activity in CAST/EiJ and PWK/PhJ backgrounds. Collectively, our study demonstrates that mouse genetic context affects tau-mediated alteration of transcriptome and tau seeding. The gene modules associated with tau seeding provide an important resource to better model tauopathy.
PLCG2 is associated with the inflammatory response and is induced by amyloid plaques in Alzheimer's disease
(Springer, 2022-02-18) Tsai, Andy P.; Dong, Chuanpeng; Lin, Peter Bor-Chian; Messenger, Evan J.; Casali, Brad T.; Moutinho, Miguel; Liu, Yunlong; Oblak, Adrian L.; Lamb, Bruce T.; Landreth, Gary E.; Bissel, Stephanie J.; Nho, Kwangsik; Medical and Molecular Genetics, School of Medicine
Background Alzheimer’s disease (AD) is characterized by robust microgliosis and phenotypic changes that accompany disease pathogenesis. Accumulating evidence from genetic studies suggests the importance of phospholipase C γ 2 (PLCG2) in late-onset AD (LOAD) pathophysiology. However, the role of PLCG2 in AD is still poorly understood. Methods Using bulk RNA-Seq (N=1249) data from the Accelerating Medicines Partnership-Alzheimer’s Disease Consortium (AMP-AD), we investigated whether PLCG2 expression increased in the brains of LOAD patients. We also evaluated the relationship between PLCG2 expression levels, amyloid plaque density, and expression levels of microglia specific markers (AIF1 and TMEM119). Finally, we investigated the longitudinal changes of PLCG2 expression in the 5xFAD mouse model of AD. To further understand the role of PLCG2 in different signaling pathways, differential gene expression and co-expression network analyses were performed using bulk RNA-Seq and microglial single-cell RNA-Seq data. To substantiate the human analyses, we performed differential gene expression analysis on wild-type (WT) and inactivated Plcg2 mice and used immunostaining to determine if the differentially expressed genes/pathways were altered by microglial cell coverage or morphology. Results We observed significant upregulation of PLCG2 expression in three brain regions of LOAD patients and significant positive correlation of PLCG2 expression with amyloid plaque density. These findings in the human brain were validated in the 5xFAD amyloid mouse model, which showed disease progression-dependent increases in Plcg2 expression associated with amyloid pathology. Of note, increased Plcg2 expression levels in 5xFAD mice were abolished by reducing microglia. Furthermore, using bulk RNA-Seq data, we performed differential expression analysis by comparing cognitively normal older adults (CN) with 75th percentile (high) and 25th percentile (low) PLCG2 gene expression levels to identify pathways related to inflammation and the inflammatory response. The findings in the human brain were validated by differential expression analyses between WT and plcg2 inactivated mice. PLCG2 co-expression network analysis of microglial single-cell RNA-Seq data identified pathways related to the inflammatory response including regulation of I-kappaB/NF-kappa B signaling and response to lipopolysaccharide. Conclusions Our results provide further evidence that PLCG2 plays an important role in AD pathophysiology and may be a potential target for microglia-targeted AD therapies.
The APOE Pathway as a Modulator of Amyloid Pathology in Alzheimer's Disease Models
(2025-03) Tate, Mason Douglas; Baucum, AJ; Kim, Jungsu; Bissel, Stephanie J.; Lasagna Reeves, Cristian A.; Oblak, Adrian L.
Alzheimer’s disease (AD) is characterized by the accumulation of beta-amyloid (Aβ) peptides and amyloid plaque deposition. The apolipoprotein E (APOE) ε4 allele is the strongest genetic risk factor for sporadic AD, with apoE protein crucial for brain lipid transport. ATP-binding cassette subfamily A member 1 (ABCA1), another risk gene, loads lipids onto apoE, highlighting the importance of lipid homeostasis in AD. MicroRNA-33 regulates the expression of ABCA1 and apoE lipidation, although its effect on amyloid pathology is unknown. Additionally, apoE variants can modulate AD risk. The apoEε4R251G variant eliminates the increased risk associated with the APOEε4 allele. This variant is located within the lipid binding domain of apoE, however its roles in lipid homeostasis and amyloid pathology remain unexplored. This dissertation investigates the role of apoE in amyloid pathology. We first used microRNA-33 knockout mice within an amyloidosis mouse model to determine if increased ABCA1 and apoE lipidation affect amyloid pathology. We demonstrate that deleting microRNA-33 reduced Aβ levels and plaque deposition. Through our multi-omics approach, we identified that microRNA-33 regulates microglial function, and mechanistically confirmed in vitro that inhibition of microRNA-33 increased microglial migration and Aβ phagocytosis. We next explored if the astrocyte-specific deletion of microRNA-33 could similarly reduce amyloid pathology. While the loss of microRNA-33 in astrocytes increased ABCA1 levels, we did not observe an increase in apoE lipidation. Furthermore, the astrocyte-specific deletion of microRNA-33 did not reduce amyloid pathology to the extent seen in the whole-body knockouts, suggesting a critical role for microglial microRNA-33 or a synergistic effect across cell types. Finally, we investigated if the astrocytic expression of the novel R251G apoE variant modulated apoE lipid pathways and amyloid pathology in an amyloidosis mouse model. We show that apoEε4R251G exhibits increased lipid binding compared to apoEε4. Additionally, the R251G variant reduced levels of Aβ and plaque deposition. Furthermore, astrocytes expressing apoEε4R251G colocalized more around plaques compared to apoEε4 mice, suggesting that astrocytes might be influencing the changes observed in amyloid pathology. Collectively, our results highlight the role of apoE lipid homeostasis in AD and potential therapeutic targets that can modulate apoE function and mitigate amyloid pathology.
The Impact of INPP5D on Microglia Response to Tau Pathology in Alzheimer's Disease
(2025-02) Soni, Dishaben Miteshkumar; Truitt, William A.; Oblak, Adrian L.; Lasagna-Reeves, Cristian; Bissel, Stephanie J.; Chu, Shaoyou
Alzheimer’s Disease (AD), the most prevalent form of dementia, is neuropathologically defined by the extracellular buildup of amyloid-beta (Aβ) plaques, the formation of intracellular neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein, and progressive neuronal degeneration, ultimately leading to cognitive decline. Genetic studies have identified immune-related risk genes linked to AD, underscoring the regulatory role of microglia in AD pathogenesis. Among these genes, INPP5D, which is exclusively expressed by microglia in the brain, has been associated with an increased risk for AD. Elevated INPP5D expression in microglia correlates with amyloid-plaque burden in human AD brain tissue, and studies indicate that INPP5D deficiency modulates amyloid pathology, with effects differing by disease stage and model system. While INPP5D modulation has been shown to impact amyloid pathology, its influence on tau pathology remains largely unexplored. This dissertation seeks to illuminate the role of INPP5D in tau pathogenesis. Our initial studies demonstrated a positive correlation between INPP5D expression and tau-seeding activity in human AD brain samples. Likewise, we observed increased INPP5D expression associated with phospho-tau AT8 levels in PS19 mice, indicating a significant link between INPP5D and tau pathology. Building on these findings, we explored the effect of Inpp5d haplodeficiency on tau pathogenesis in PS19 mice, revealing that Inpp5d haplodeficiency recovered motor functions, mitigated tau pathology, lowered proinflammatory cytokine levels and altered microglial morphology without affecting the overall cellular composition. Transcriptomic analysis also showed the upregulation of genes involved in cell migration, immune response, angiogenesis, and wound healing. These results highlight a complex interplay between Inpp5d, tau pathology, and behavioral outcomes, supporting Inpp5d’s involvement in tau pathogenesis. To explore this further, we treated primary microglia isolated from Wildtype, Inpp5d+/-, and Inpp5d-/- mice with recombinant mutant tau-preformed fibrils and insolubletau extracted from PS19 mice brains. Our results revealed increased tau uptake in Inpp5d+/- and Inpp5d-/- microglia, suggesting that Inpp5d modulation enhances tau uptake, potentially influencing disease progression through altered microglial response. While further research is needed to clarify the mechanisms through which INPP5D influences tau pathogenesis, our findings highlight INPP5D as a promising therapeutic target for modulating tau pathology and improving microglial function in AD.
The Role of the Lung-Brain Axis in the Ozone-Impaired Amyloid Associated Astrocytic and Vascular Phenotype
(2024-06) Ahmed, Chandrama; Oblak, Adrian; Block, Michelle; Baucum, A. J.; Bissel, Stephanie J.; Nass, Richard M.
Air pollution has been associated with an increased risk of Alzheimer’s Disease (AD). Studies show ozone (O3), a major component of urban air pollution, can exacerbate amyloid pathology. However, O3 reacts in its entirety with lung epithelial lining after inhalation, hence does not translocate to brain. Studies have implicated the lung−brain axis in O3 induced central nervous system (CNS) pathology. However, the mechanistic underpinnings of its role in amyloid pathology is obscure. Here, we explored the impact of O3 on the astrocytic and vascular response to amyloid plaque in 5xFAD mice and its link to the O3 lung response. O3 exposure increased GFAP positive astrocyte density correlating with increased plaque burden in the cortex. Focusing on the plaque microenvironment, we found O3 qualitatively altered plaque associated astrocytes, evidenced by both proteomic and transcriptomic changes. Along with loss of protein expression, proteomic changes reflected increased cell-cell interaction in plaque microenvironment. Specifically, we found increased astrocyte-microglia contact selectively in periplaque space from O3 exposure. Transcriptional analysis of periplaque astrocytes revealed an accelerated shift towards disease associated astrocyte (DAA) phenotype. Elevated circulating HMGB1 was previously found from O3 exposure. In this study we demonstrate deleting HMGB1 selectively in peripheral myeloid cells and not in CNS microglia ameliorates the lung immune response to O3 as well as downregulates DAA marker in the CNS, providing a potential link between peripheral HMGB1 and O3 induced astrocytic dysregulation. On examining vascular response to O3 we found increased vascular amyloid accumulation associated with an altered vascular proteomic profile. Our analysis indicates O3 potentially disrupts vascular function such as amyloid clearance. Taken together, our study demonstrates that astrocyte and neurovasculature are contributors to O3 lung-brain axis with important implications towards amyloid pathology progression and identifies peripheral myeloid HMGB1 as its potential modulator. Further studies are required to fully understand the consequences of this impact and its role in amyloid pathology.
The Role of TREM2 and the Responses Mediated by Galectin-3 During Age-Related Myelin Degeneration
(2025-03) McCray, Tyler Jacob; Oblak, Adrian L.; Bissel, Stephanie J.; Lahiri, Debomoy K.; Lamb, Bruce T.; McKinzie, David L.
Aging is the greatest known risk factor for various neurodegenerative diseases. Myelin degeneration is an early pathological indicator of these diseases and normal part of aging; albeit, to a lesser extent. Despite this, little is known about how age-related degeneration could contribute to and impact development of neurodegenerative disease. Microglia participate in a variety of white matter events from demyelination to remyelination. The microglial innate immune receptor triggering receptor expressed on myeloid cells 2 (TREM2) has been implicated in regulating (de)myelination. We found in response to demyelination, TREM2 is required for large volumes of myelin debris and during extended periods of phagocytosis. In addition to lysosomal regulation, we showed TREM2 can modify the ER stress response prior to overt myelin debris preventing early microglial dysfunction. We found TREM2 is necessary for remyelination by recruiting reparative glia and mediating signaling that promotes OPC differentiation/maturation. One of the signaling factors involved, the β-galactosidase-binding protein galectin-3 (gal-3), was recently identified as a ligand for TREM2, however little is known about this interaction in the context of aging or neurodegenerative disease. Treating microglia with a pharmacological gal-3 inhibitor, we found overlapping functional deficits with Trem2-deficient microglia during myelin phagocytosis. These shared deficits included impaired myelin uptake, altered lysosomal function, ER stress, and lipid droplet accumulation that were rescued inTrem2-deficient microglia with the addition of recombinant gal-3. RNA-seq analyses revealed common genes and pathways affected that importantly included genes associated with the integrated stress response. Taken together, these data suggest Gal-3 mediates and throttles the TREM2-dependent stress response during age-related myelin degeneration. Further, it provides support for targeting TREM2 function early to augment reparative signaling preventing overt debris accumulation and/or promoting gal-3 to alleviate stress pathways that can lead to premature microglial dysfunction and onset of pathology.

Browsing by Author "Bissel, Stephanie J."

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