Neuroscience
Abstract
Autosomal Dominant Optic Atrophy (ADOA), the most prevalent hereditary optic neuropathy, leads to retinal ganglion cell (RGC) degeneration and vision loss. ADOA is primarily caused by mutations in the OPA1 gene, which encodes a conserved GTPase important for mitochondrial inner membrane dynamics. To date, the disease mechanism remains unclear, and no therapies are available. We generated a mouse model carrying the pathogenic Opa1R290Q/+ allele that recapitulated key features of human ADOA, including mitochondrial defects, age-related RGC loss, optic nerve degeneration, and reduced RGC functions. We identified SARM1, a neurodegeneration switch, as a key driver of RGC degeneration in these mice. Sarm1 knockout nearly completely suppressed all the degeneration phenotypes without reversing mitochondrial fragmentation. Additionally, we showed that a portion of SARM1 localized within the mitochondrial intermembrane space (IMS). These findings indicated that SARM1 was activated downstream of mitochondrial dysfunction in ADOA, highlighting it as a promising therapeutic target.
Authors
Chen Ding, Papa S. Ndiaye, Sydney R. Campbell, Michelle Y. Fry, Jincheng Gong, Sophia R. Wienbar, Whitney Gibbs, Philippe Morquette, Luke H. Chao, Michael Tri H. Do, Thomas Schwarz
Abstract
Phenylketonuria (PKU), an inborn error of phenylalanine (Phe) metabolism, is a common cause of intellectual disability. However, the mechanisms by which elevated phenylalanine (Phe) levels cause cognitive impairment remain unclear. Here, we show that submillimolar Phe perturbs synaptic plasticity through the hyperactivation of GluN2B-containing NMDARs. PahEnu2 PKU model mice exhibited submillimolar and supramillimolar concentrations of Phe in the cerebrospinal fluid (CSF) and serum, respectively. L-Phe produced concentration-dependent bidirectional effects on NMDA-induced currents, without affecting synaptic NMDARs in hippocampal CA1 neurons. L-Phe-induced hyperactivation of extrasynaptic GluN2B resulted in activity-dependent downregulation of AMPARs during burst or sustained synaptic activity. Administration of L-Phe in mice decreased neural activity and impaired memory, which were blocked by pretreatment with GluN2B inhibitors. Furthermore, pharmacological and virus-mediated suppression of GluN2B reversed the impaired learning in PahEnu2 mice. Collectively, these results suggest that the concentration of Phe in the CSF of patients with PKU perturbs extrasynaptic NMDARs and synaptic plasticity, and that suppression of GluN2B may have the potential to improve cognitive function in patients with PKU.
Authors
Woo Seok Song, Young Sook Kim, Young-Soo Bae, Sang Ho Yoon, Jae Min Lim, Myoung-Hwan Kim
Abstract
Diffuse midline gliomas (DMGs) are lethal brain tumors characterized by p53-inactivating mutations and oncohistone H3.3K27M mutations that rewire the cellular response to genotoxic stress. We used RCAS/tv-a retroviruses and Cre recombinase to inactivate p53 and induce native H3.3K27M mutations in a lineage- and spatially-directed manner. We generated primary mouse tumors that recapitulate human DMG. Disrupting ataxia-telangiectasia mutated kinase (ATM) enhanced the efficacy of radiation therapy in murine and patient-derived DMG models which increased survival. Microscopy-based in situ sequencing was used to spatially resolve transcriptional profiles in >750,000 single cells with or without ATM disruption and radiation therapy, revealing altered immune-neoplastic and endothelial cell interactions after treatment. An allelic series of primary murine DMG models with different p53 mutations confirmed that transactivation-independent p53 activity is a key mediator of radiosensitivity after ATM disruption. Our findings contribute primary DMG mouse models with deep profiling and reveal the mechanisms of treatment response to an actionable therapeutic strategy.
Authors
Avani Mangoli, Vennesa Valentine, Spencer Maingi, Sophie R. Wu, Harrison Q. Liu, Michael Aksu, Vaibhav Jain, Bronwen E. Foreman, Joshua A. Regal, Loren B. Weidenhammer, Connor E. Stewart, Maria E. Guerra Garcia, Emily Hocke, Karen Abramson, Tal Falick Michaeli, Nerissa T. Williams, Lixia Luo, Megan Romero, Katherine Deland, Samantha Gadd, Eita Uchida, Laura Attardi, Kouki Abe, Rintaro Hashizume, David M. Ashley, Oren J. Becher, David G. Kirsch, Simon G. Gregory, Zachary J. Reitman
Abstract
The efficacy of T cell-activating therapies against glioma is limited by an immunosuppressive tumor microenvironment and tumor-induced T cell sequestration. We investigated whether peripherally infused non-antigen specific autologous lymphocytes (ALT) could accumulate in intracranial tumors. We observed that non-specific autologous CD8+ ALT cells can indeed accumulate in this context, despite endogenous T cell sequestration in bone marrow. Rates of intratumoral accumulation were markedly increased when expanding lymphocytes with IL-7 compared to IL-2. Pre-treatment with IL-7 ALT also enhanced the efficacy of multiple tumor-specific and non-tumor-specific T cell-dependent immunotherapies against orthotopic murine and human xenograft gliomas. Mechanistically, we detected increased VLA-4 on mouse and human CD8+ T cells following IL-7 expansion, with increased transcription of genes associated with migratory integrin expression (CD9). We also observed that IL-7 increases S1PR1 transcription in human CD8+ T cells, which we have shown to be protective against tumor-induced T cell sequestration. These observations demonstrate that expansion with IL-7 enhances the capacity of ALT to accumulate within intracranial tumors, and that pre-treatment with IL-7 ALT can boost the efficacy of subsequent T cell-activating therapies against glioma. Our findings will inform the development of future clinical trials where ALT pre-treatment can be combined with T cell-activating therapies.
Authors
Kirit Singh, Kelly M. Hotchkiss, Sarah L. Cook, Pamy Noldner, Ying Zhou, Eliese M. Moelker, Chelsea O. Railton, Emily E. Blandford, Bhairavy J. Puviindran, Shannon E. Wallace, Pamela K. Norberg, Gary E. Archer, Beth H. Shaz, Katayoun Ayasoufi, John H. Sampson, Mustafa Khasraw, Peter E. Fecci
Abstract
BACKGROUND. Microglia-mediated brain immune changes play a role in the pathogenesis of Parkinson’s disease (PD) but imaging microglia in living people with PD has relied on positron emission tomography (PET) ligands that lack specificity in labeling immune cells in the nervous system. We aimed to develop imaging of colony stimulating factor 1 receptor (CSF1R) as a microglial-sensitive marker of innate immunity. METHODS. Immunohistochemistry using a CSF1R antibody evaluated colocalization with Iba-1 in PD (n = 4) and control (n = 4) human brain samples. Autoradiography using a CSF1R tritiated ligand in PD (n = 5) and controls (n = 4) human brain samples was performed to obtain Bmax. PET imaging using a CSF1R radioligand was performed in 10 controls and 12 people with PD and VT was compared between groups and correlated with disease severity. RESULTS. Immunohistochemistry of CSF1R in human brain shows colocalization with Iba-1 and is significantly increased in PD compared to controls. Autoradiography revealed significantly increased CSF1R ligand binding in the inferior parietal cortex of PD patients. [11C]CPPC PET showed higher binding in people with moderate PD compared to controls and correlated with more severe motor disability and poorer verbal fluency. CONCLUSION. This study underscores the significance of CSF1R imaging as a promising biomarker for brain immune function in Parkinson's disease, which may be associated with cognitive and motor disease severity FUNDING. PET imaging: the Michael J. Fox Foundation and the RMS Family Foundation. Radiotracer development: NIH (R01AG066464 and P41 EB024495). Postmortem brain tissues: NIH P30 AG066507 and BIOCARD study NIH U19 AG033655.
Authors
Kelly A. Mills, Yong Du, Jennifer M. Coughlin, Catherine A. Foss, Andrew G. Horti, Katelyn R. Jenkins, Yana Skorobogatova, Ergi Spiro, Chelsie S. Motley, Robert F. Dannals, Wojciech G. Lesniak, Jae-Jin Song, Yu Ree Choi, Javier Redding-Ochoa, Juan C. Troncoso, Valina L. Dawson, Tae-In Kam, Martin G. Pomper, Ted M. Dawson
Abstract
Weight loss medications are emerging candidates for pharmacotherapy of sleep disordered breathing (SDB). A melanocortin receptor 4 (MC4R) agonist, setmelanotide (SET), is used to treat obesity caused by abnormal melanocortin and leptin signaling. We hypothesized that SET can treat SDB in diet induced obese mice. We performed a proof-of-concept randomized crossover trial of a single dose of SET vs vehicle and a two-week daily SET vs vehicle trial, examined co-localization of Mc4r mRNAs with markers of CO2 sensing neurons Phox2b and neuromedin-B in the brainstem, and expressed Cre-dependent designer receptors exclusively activated by designer drugs or caspase in obese Mc4r-Cre mice. SET increased minute ventilation across sleep/wake states, enhanced the hypercapnic ventilatory response (HCVR) and abolished apneas during sleep. Phox2b+ neurons in the nucleus of the solitary tract (NTS) and the parafacial region expressed Mc4r. Chemogenetic stimulation of the MC4R+ neurons in the parafacial region, but not in the NTS, augmented HCVR without any changes in metabolism. Caspase elimination of the parafacial MC4R+ neurons abolished effects of SET on HCVR. Parafacial MC4R+ neurons projected to the respiratory pre-motor neurons retrogradely labeled from C3-C4. In conclusion, MC4R agonists enhance the HCVR and treat SDB by acting on the parafacial MC4R+ neurons.
Authors
Mateus R. Amorim, Noah R. Williams, O Aung, Melanie Alexis Ruiz, Frederick Anokye-Danso, Junia Lara de Deus, Jiali Xiong, Olga Dergacheva, Shannon Bevans-Fonti, Sean M. Lee, Jeffrey S Berger, Mark N. Wu, Rexford S. Ahima, David Mendelowitz, Vsevolod Y. Polotsky
Abstract
Neuronal hyperexcitability precedes synapse loss in certain neurodegenerative diseases, yet the synaptic membrane interactions and downstream signaling events remain unclear. The disordered amino terminus of the prion protein (PrPC) has been implicated in aberrant signaling in prion and Alzheimer’s disease. To disrupt neuronal interactions and signaling linked to the amino terminus, here we CRISPR-engineered a knock-in mouse expressing mutant PrPC (G92N), generating an N-linked glycosylation site between two functional motifs. Mice developed seizures and necrosis of hippocampal pyramidal neurons, similar to prion-infected mice and consistent with excitotoxicity. Phosphoproteomics revealed phosphorylated glutamate receptors and calcium-sensitive kinases, including protein kinase C (PKC). Additionally, 92N-PrPC-expressing neurons show persistent calcium influx as well as dendritic beading, which was rescued by an NMDA receptor antagonist. Finally, survival of Prnp92N mice was prolonged by blocking active NMDA receptor channels. We propose dysregulated PrPC – NMDA receptor - induced signaling can trigger excitatory – inhibitory imbalance, spongiform degeneration, and neurotoxicity, and that calcium dysregulation is central to PrPC-linked neurodegeneration.
Authors
Joie Lin, Julia A. Callender, Joshua E. Mayfield, Daniel B. McClatchy, Daniel Ojeda-Juárez, Mahsa Pourhamzeh, Katrin Soldau, Timothy D. Kurt, Garrett A. Danque, Helen K. Khuu, Josephina E. Ronson, Donald P. Pizzo, Yixing Du, Maxwell A. Gruber, Alejandro M. Sevillano, Jin Wang, Christina D. Orrú, Joy Chen, Gail Funk, Patricia Aguilar-Calvo, Brent D. Aulston, Subhojit Roy, Jong M. Rho, Jack D. Bui, Alexandra C. Newton, Stuart A. Lipton, Byron Caughey, Gentry N. Patrick, Kim Doré, John R. Yates III, Christina J. Sigurdson
Abstract
Maladaptive fear generalization is one of the hallmarks of trauma-related disorders. The endocannabinoid 2-arachidonoylglycerol (2-AG) is crucial for modulating anxiety, fear, and stress adaptation but its role in balancing fear discrimination versus generalization is not known. To address this, we used a combination of plasma endocannabinoid measurement and neuroimaging from a childhood maltreatment-exposed and non-exposed mixed population combined with human and rodent fear conditioning models. Here we show that 2-AG levels are inversely associated with fear generalization at the behavioral level in both mice and humans. In mice, 2-AG depletion increases the proportion of neurons, and the similarity between neuronal representations, of threat-predictive and neutral stimuli within prelimbic prefrontal cortex neuronal ensembles. In humans, increased dorsolateral prefrontal cortical-amygdala resting state connectivity is inversely correlated with fear generalization. These data provide convergent cross-species evidence that 2-AG is a key regulator of fear generalization and further support the notion that 2-AG deficiency could represent a trauma-related disorder susceptibility endophenotype.
Authors
Luis E. Rosas-Vidal, Saptarnab Naskar, Leah M. Mayo, Irene Perini, Rameen Masroor, Megan Altemus, Liorimar Ramos-Medina, S. Danyal Zaidi, Hilda Engelbrektsson, Puja Jagasia, Markus Heilig, Sachin Patel
Abstract
Background: Despite growing preclinical evidence that glucagon-like peptide-1 receptor agonists (GLP-1RAs) could be repurposed to treat alcohol use disorder (AUD), clinical evidence is scarce. Additionally, the potential impact of dipeptidyl peptidase-4 inhibitors (DPP-4Is) on alcohol intake is largely unknown. Methods: We conducted a large cohort study using 2008-2023 electronic health records data from the U.S. Department of Veterans Affairs. Changes in Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) scores were compared between propensity-score-matched GLP-1RA recipients, DPP-4I recipients, and unexposed comparators. We further tested the effects of two DPP-4Is, linagliptin and omarigliptin, on binge-like alcohol drinking in mice and operant oral alcohol self-administration in alcohol-dependent rats, models previously used to show a significant effect of the GLP-1RA semaglutide in reducing alcohol intake. Results: GLP-1RA recipients reported a greater reduction in AUDIT-C scores than unexposed individuals [difference-in-difference: 0.09(0.03,0.14), p=0.0025] and DPP-4I recipients [difference-in-difference: 0.11(0.05,0.17), p=0.0002]. Reductions in drinking were more pronounced among individuals with baseline AUD [GLP-1RA vs. unexposed: 0.51(0.29,0.72), p<0.0001; GLP-1RA vs. DPP-4I: 0.65(0.43,0.88), p<0.0001] and baseline hazardous drinking [GLP-1RA vs. unexposed: 1.38(1.07,1.69), p<0.0001; GLP-1RA vs. DPP-4I: 1.00(0.68,1.33), p<0.0001]. There were no differences between DPP-4I recipients and unexposed individuals. The latter results were confirmed via a reverse translational approach. Specifically, neither linagliptin nor omarigliptin reduced alcohol drinking in mice or rats. The rodent experiments also confirmed target engagement as both DPP-4Is reduced blood glucose levels. Conclusion: Convergent findings across humans, mice, and rats indicate that GLP-1RAs but not DPP-4Is reduce alcohol consumption and may be efficacious in treating AUD.
Authors
Mehdi Farokhnia, John Tazare, Claire L. Pince, Nicolaus Bruns Vi, Joshua C. Gray, Vincent Lo Re III, David A. Fiellin, Henry R. Kranzler, George F. Koob, Amy C. Justice, Leandro F. Vendruscolo, Christopher T. Rentsch, Lorenzo Leggio
Abstract
Multiple sclerosis (MS) is a debilitating autoimmune disease of the CNS, which is characterized by demyelination and axonal injury and frequently preceded by a demyelinating event called clinically isolated syndrome (CIS). Despite the importance of B cells and autoantibodies in MS pathology, their target specificities remain largely unknown. For an agnostic and comprehensive evaluation of autoantibodies in MS, we developed and employed what we believe to be a novel autoantigen discovery technology, the Antigenome Platform. This Platform is a high-throughput assay comprising large-fragment (approximately 100 amino acids) cDNA libraries, phage display, serum antibody screening technology, and robust bioinformatics analysis pipelines. For autoantibody discovery, we assayed serum samples from CIS patients who received either placebo or treatment who were enrolled in the REFLEX clinical trial, which assessed the effects of IFN-β-1a (Rebif) clinical and MRI activity in patients with CIS. Serum autoantibodies from patients with CIS were significantly and reproducibly enriched for known and previously unreported protein targets; 166 targets were selected by over 10% of patients’ sera. Further, 10 autoantibody biomarkers associated with disease activity and 17 associated with patient response to IFN-β-1a therapy. These findings indicate widespread autoantibody production in MS and provide biomarkers for continued study and prediction of disease progression.
Authors
Europe B. DiCillo, Evgueni Kountikov, Minghua Zhu, Stefan Lanker, Danielle E. Harlow, Elizabeth R. Piette, Weiguo Zhang, Brooke Hayward, Joshua Heuler, Julie Korich, Jeffrey L. Bennett, David Pisetsky, Thomas Tedder
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)