Browsing by Author "Moutinho, Miguel"
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Item CX3CR1 deficiency aggravates amyloid driven neuronal pathology and cognitive decline in Alzheimer's disease(BMC, 2022-06-28) Puntambekar, Shweta S.; Moutinho, Miguel; Lin, Peter Bor‑Chian; Jadhav, Vaishnavi; Tumbleson‑Brink, Danika; Balaji, Ananya; Benito, Martin Alvarado; Xu, Guixiang; Oblak, Adrian; Lasagna‑Reeves, Cristian A.; Landreth, Gary E.; Lamb, Bruce T.; Medical and Molecular Genetics, School of MedicineBackground: Despite its identification as a key checkpoint regulator of microglial activation in Alzheimer's disease, the overarching role of CX3CR1 signaling in modulating mechanisms of Aβ driven neurodegeneration, including accumulation of hyperphosphorylated tau is not well understood. Methodology: Accumulation of soluble and insoluble Aβ species, microglial activation, synaptic dysregulation, and neurodegeneration is investigated in 4- and 6-month old 5xFAD;Cx3cr1+/+ and 5xFAD;Cx3cr1-/- mice using immunohistochemistry, western blotting, transcriptomic and quantitative real time PCR analyses of purified microglia. Flow cytometry based, in-vivo Aβ uptake assays are used for characterization of the effects of CX3CR1-signaling on microglial phagocytosis and lysosomal acidification as indicators of clearance of methoxy-X-04+ fibrillar Aβ. Lastly, we use Y-maze testing to analyze the effects of Cx3cr1 deficiency on working memory. Results: Disease progression in 5xFAD;Cx3cr1-/- mice is characterized by increased deposition of filamentous plaques that display defective microglial plaque engagement. Microglial Aβ phagocytosis and lysosomal acidification in 5xFAD;Cx3cr1-/- mice is impaired in-vivo. Interestingly, Cx3cr1 deficiency results in heighted accumulation of neurotoxic, oligomeric Aβ, along with severe neuritic dystrophy, preferential loss of post-synaptic densities, exacerbated tau pathology, neuronal loss and cognitive impairment. Transcriptomic analyses using cortical RNA, coupled with qRT-PCR using purified microglia from 6 month-old mice indicate dysregulated TGFβ-signaling and heightened ROS metabolism in 5xFAD;Cx3cr1-/- mice. Lastly, microglia in 6 month-old 5xFAD;Cx3cr1-/- mice express a 'degenerative' phenotype characterized by increased levels of Ccl2, Ccl5, Il-1β, Pten and Cybb along with reduced Tnf, Il-6 and Tgfβ1 mRNA. Conclusions: Cx3cr1 deficiency impairs microglial uptake and degradation of fibrillar Aβ, thereby triggering increased accumulation of neurotoxic Aβ species. Furthermore, loss of Cx3cr1 results in microglial dysfunction typified by dampened TGFβ-signaling, increased oxidative stress responses and dysregulated pro-inflammatory activation. Our results indicate that Aβ-driven microglial dysfunction in Cx3cr1-/- mice aggravates tau hyperphosphorylation, neurodegeneration, synaptic dysregulation and impairs working memory.Item 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 MedicineGenetic 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.Item INPP5D deficiency attenuates amyloid pathology in a mouse model of Alzheimer’s disease(Wiley, 2023) Lin, Peter Bor-Chian; Tsai, Andy Po-Yi; Soni, Disha; Lee-Gosselin, Audrey; Moutinho, Miguel; Puntambekar, Shweta S.; Landreth, Gary E.; Lamb, Bruce T.; Oblak, Adrian L.; Anatomy, Cell Biology and Physiology, School of MedicineIntroduction: Inositol polyphosphate-5-phosphatase (INPP5D) is a microglia-enriched lipid phosphatase in the central nervous system. A non-coding variant (rs35349669) in INPP5D increases the risk for Alzheimer's disease (AD), and elevated INPP5D expression is associated with increased plaque deposition. INPP5D negatively regulates signaling via several microglial cell surface receptors, including triggering receptor expressed on myeloid cells 2 (TREM2); however, the impact of INPP5D inhibition on AD pathology remains unclear. Methods: We used the 5xFAD mouse model of amyloidosis to assess how Inpp5d haplodeficiency regulates amyloid pathogenesis. Results: Inpp5d haplodeficiency perturbs the microglial intracellular signaling pathways regulating the immune response, including phagocytosis and clearing of amyloid beta (Aβ). It is important to note that Inpp5d haploinsufficiency leads to the preservation of cognitive function. Spatial transcriptomic analysis revealed that pathways altered by Inpp5d haploinsufficiency are related to synaptic regulation and immune cell activation. Conclusion: These data demonstrate that Inpp5d haplodeficiency enhances microglial functions by increasing plaque clearance and preserves cognitive abilities in 5xFAD mice. Inhibition of INPP5D is a potential therapeutic strategy for AD.Item INPP5D expression is associated with risk for Alzheimer’s disease and induced by plaque-associated microglia(Elsevier, 2021-06) Tsai, Andy P.; Bor-Chian, Lin Peter; Dong, Chuanpeng; Moutinho, Miguel; Casali, Brad T.; Liu, Yunlong; Lamb, Bruce T.; Landreth, Gary E.; Oblak, Adrian L.; Nho, Kwangsik; Medical and Molecular Genetics, School of MedicineAlzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, robust microgliosis, neuroinflammation, and neuronal loss. Genome-wide association studies recently highlighted a prominent role for microglia in late-onset AD (LOAD). Specifically, inositol polyphosphate-5-phosphatase (INPP5D), also known as SHIP1, is selectively expressed in brain microglia and has been reported to be associated with LOAD. Although INPP5D is likely a crucial player in AD pathophysiology, its role in disease onset and progression remains unclear. We performed differential gene expression analysis to investigate INPP5D expression in AD and its association with plaque density and microglial markers using transcriptomic (RNA-Seq) data from the Accelerating Medicines Partnership for Alzheimer's Disease (AMP-AD) cohort. We also performed quantitative real-time PCR, immunoblotting, and immunofluorescence assays to assess INPP5D expression in the 5xFAD amyloid mouse model. Differential gene expression analysis found that INPP5D expression was upregulated in LOAD and positively correlated with amyloid plaque density. In addition, in 5xFAD mice, Inpp5d expression increased as the disease progressed, and selectively in plaque-associated microglia. Increased Inpp5d expression levels in 5xFAD mice were abolished entirely by depleting microglia with the colony-stimulating factor receptor-1 antagonist PLX5622. Our findings show that INPP5D expression increases as AD progresses, predominantly in plaque-associated microglia. Importantly, we provide the first evidence that increased INPP5D expression might be a risk factor in AD, highlighting INPP5D as a potential therapeutic target. Moreover, we have shown that the 5xFAD mouse model is appropriate for studying INPP5D in AD.Item Inpp5d haplodeficiency alleviates tau pathology in the PS19 mouse model of Tauopathy(Wiley, 2024) Soni, Disha M.; Bor-Chian Lin, Peter; Lee-Gosselin, Audrey; Lloyd, Christopher D.; Mason, Emily; Ingraham, Cynthia M.; Perkins, Abigail; Moutinho, Miguel; Lamb, Bruce T.; Chu, Shaoyou; Oblak, Adrian L.; Neurology, School of MedicineIntroduction: A noncoding variant (rs35349669) within INPP5D, a lipid and protein phosphatase restricted to microglia in the brain, is linked to increased susceptibility to Alzheimer's disease (AD). While Inpp5d is well-studied in amyloid pathology, its role in tau pathology remains unclear. Methods: PS19 Tauopathy mice were crossed with Inpp5d-haplodeficient (Inpp5d+/-) mice to examine the impact of Inpp5d in tau pathology. Results: Increased INPP5D expression correlated positively with phospho-Tau AT8 in PS19 mice. Inpp5d haplodeficiency mitigated hyperphosphorylated tau levels (AT8, AT180, AT100, and PHF1) and motor deficits in PS19 mice. Transcriptomic analysis revealed an up-regulation of genes associated with immune response and cell migration. Discussion: Our findings define an association between INPP5D expression and tau pathology in PS19 mice. Alleviation in hyperphosphorylated tau, motor deficits, and transcriptomics changes in haplodeficient-Inpp5d PS19 mice indicate that modulation in INPP5D expression may provide therapeutic potential for mitigating tau pathology and improving motor deficits. Highlights: The impact of Inpp5d in the context of tau pathology was studied in the PS19 mouse model. INPP5D expression is associated with tau pathology. Reduced Inpp5d expression in PS19 mice improved motor functions and decreased total and phospho-Tau levels. Inpp5d haplodeficiency in PS19 mice modulates gene expression patterns linked to immune response and cell migration. These data suggest that inhibition of Inpp5d may be a therapeutic approach in tauopathies.Item Nuclear Receptors as Therapeutic Targets for Neurodegenerative Diseases: Lost in Translation(Annual Reviews, 2019-01-06) Moutinho, Miguel; Codocedo, Juan F.; Puntambekar, Shweta S.; Landreth, Gary E.; Anatomy & Cell Biology, IU School of MedicineNeurodegenerative diseases are characterized by a progressive loss of neurons that leads to a broad range of disabilities, including severe cognitive decline and motor impairment, for which there are no effective therapies. Several lines of evidence support a putative therapeutic role of nuclear receptors (NRs) in these types of disorders. NRs are ligand-activated transcription factors that regulate the expression of a wide range of genes linked to metabolism and inflammation. Although the activation of NRs in animal models of neurodegenerative disease exhibits promising results, the translation of this strategy to clinical practice has been unsuccessful. In this review we discuss the role of NRs in neurodegenerative diseases in light of preclinical and clinical studies, as well as new findings derived from the analysis of transcriptomic databases from humans and animal models. We discuss the failure in the translation of NR-based therapeutic approaches and consider alternative and novel research avenues in the development of effective therapies for neurodegenerative diseases.Item 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 MedicineBackground 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.Item The niacin receptor HCAR2 modulates microglial response and limits disease progression in a mouse model of Alzheimer's disease(American Association for the Advancement of Science, 2022) Moutinho, Miguel; Puntambekar, Shweta S.; Tsai, Andy P.; Coronel, Israel; Lin, Peter B.; Casali, Brad T.; Martinez, Pablo; Oblak, Adrian L.; Lasagna-Reeves, Cristian A.; Lamb, Bruce T.; Landreth, Gary E.; Anatomy, Cell Biology and Physiology, School of MedicineIncreased dietary intake of niacin has been correlated with reduced risk of Alzheimer's disease (AD). Niacin serves as a high-affinity ligand for the receptor HCAR2 (GPR109A). In the brain, HCAR2 is expressed selectively by microglia and is robustly induced by amyloid pathology in AD. The genetic inactivation of Hcar2 in 5xFAD mice, a model of AD, results in impairment of the microglial response to amyloid deposition, including deficits in gene expression, proliferation, envelopment of amyloid plaques, and uptake of amyloid-β (Aβ), ultimately leading to exacerbation of amyloid burden, neuronal loss, and cognitive deficits. In contrast, activation of HCAR2 with an FDA-approved formulation of niacin (Niaspan) in 5xFAD mice leads to reduced plaque burden and neuronal dystrophy, attenuation of neuronal loss, and rescue of working memory deficits. These data provide direct evidence that HCAR2 is required for an efficient and neuroprotective response of microglia to amyloid pathology. Administration of Niaspan potentiates the HCAR2-mediated microglial protective response and consequently attenuates amyloid-induced pathology, suggesting that its use may be a promising therapeutic approach to AD that specifically targets the neuroimmune response.Item Therapeutic potential of nuclear receptor agonists in Alzheimer's disease(American Society for Biochemistry and Molecular Biology, 2017-10) Moutinho, Miguel; Landreth, Gary E.; Anatomy and Cell Biology, IU School of MedicineAlzheimer's disease (AD) is characterized by an extensive accumulation of amyloid-β (Aβ) peptide, which triggers a set of deleterious processes, including synaptic dysfunction, inflammation, and neuronal injury, leading to neuronal loss and cognitive impairment. A large body of evidence supports that nuclear receptor (NR) activation could be a promising therapeutic approach for AD. NRs are ligand-activated transcription factors that regulate gene expression and have cell type-specific effects. In this review, we discuss the mechanisms that underlie the beneficial effects of NRs in AD. Moreover, we summarize studies reported in the last 10-15 years and their major outcomes arising from the pharmacological targeting of NRs in AD animal models. The dissection of the pathways regulated by NRs in the context of AD is of importance in identifying novel and effective therapeutic strategies.Item The Trem2 R47H variant confers loss-of-function-like phenotypes in Alzheimer's disease(BMC, 2018-06-01) Cheng-Hathaway, Paul J.; Reed-Geaghan, Erin G.; Jay, Taylor R.; Casali, Brad T.; Bemiller, Shane M.; Puntambekar, Shweta S.; von Saucken, Victoria E.; Williams, Roxanne Y.; Karlo, J. Colleen; Moutinho, Miguel; Xu, Guixiang; Ransohoff, Richard M.; Lamb, Bruce T.; Landreth, Gary E.; Anatomy and Cell Biology, School of MedicineBACKGROUND: The R47H variant of Triggering Receptor Expressed on Myeloid cells 2 (TREM2) confers greatly increased risk for Alzheimer's disease (AD), reflective of a central role for myeloid cells in neurodegeneration. Understanding how this variant confers AD risk promises to provide important insights into how myeloid cells contribute to AD pathogenesis and progression. METHODS: In order to investigate this mechanism, CRISPR/Cas9 was used to generate a mouse model of AD harboring one copy of the single nucleotide polymorphism (SNP) encoding the R47H variant in murine Trem2. TREM2 expression, myeloid cell responses to amyloid deposition, plaque burden, and neuritic dystrophy were assessed at 4 months of age. RESULTS: AD mice heterozygous for the Trem2 R47H allele exhibited reduced total Trem2 mRNA expression, reduced TREM2 expression around plaques, and reduced association of myeloid cells with plaques. These results were comparable to AD mice lacking one copy of Trem2. AD mice heterozygous for the Trem2 R47H allele also showed reduced myeloid cell responses to amyloid deposition, including a reduction in proliferation and a reduction in CD45 expression around plaques. Expression of the Trem2 R47H variant also reduced dense core plaque number but increased plaque-associated neuritic dystrophy. CONCLUSIONS: These data suggest that the AD-associated TREM2 R47H variant increases risk for AD by conferring a loss of TREM2 function and enhancing neuritic dystrophy around plaques.