Parkinson’s disease (PD) is a progressive neurodegenerative disease with devastating clinical manifestations. In PD, neuronal death is associated with intracellular aggregates of the neuronal protein α-synuclein known as Lewy bodies. Although the cause of sporadic PD is not well understood, abundant clinical and pathological evidence show that misfolded α-synuclein is found in enteric nerves before it appears in the brain. This suggests a model in which PD pathology originates in the gut and spreads to the central nervous system via cell-to-cell prion-like propagation, such that transfer of misfolded α-synuclein initiates misfolding of native α-synuclein in recipient cells. We recently discovered that enteroendocrine cells (EECs), which are part of the gut epithelium and directly face the gut lumen, also possess many neuron-like properties and connect to enteric nerves. In this report, we demonstrate that α-synuclein is expressed in the EEC line, STC-1, and native EECs of mouse and human intestine. Furthermore, α-synuclein–containing EECs directly connect to α-synuclein–containing nerves, forming a neural circuit between the gut and the nervous system in which toxins or other environmental influences in the gut lumen could affect α-synuclein folding in the EECs, thereby beginning a process by which misfolded α-synuclein could propagate from the gut epithelium to the brain.
Rashmi Chandra, Annie Hiniker, Yien-Ming Kuo, Robert L. Nussbaum, Rodger A. Liddle
Degenerative cervical myelopathy (DCM) is the most common progressive nontraumatic spinal cord injury. The most common recommended treatment is surgical decompression, although the optimal timing of intervention is an area of ongoing debate. The primary objective of this study was to assess whether a delay in decompression could influence the extent of ischemia-reperfusion injury and alter the trajectory of outcome in DCM. Using a DCM mouse model, we show that decompression acutely led to a 1.5- to 2-fold increase in levels of inflammatory cytokines within the spinal cord. Delayed decompression was associated with exacerbated reperfusion injury, astrogliosis, and poorer neurological recovery. Additionally, delayed decompression was associated with prolonged elevation of inflammatory cytokines and an exacerbated peripheral monocytic inflammatory response (P < 0.01 and 0.001). In contrast, early decompression led to resolution of reperfusion-mediated inflammation, neurological improvement, and reduced hyperalgesia. Similar findings were observed in subjects from the CSM AOSpine North America and International studies, where delayed decompressive surgery resulted in poorer neurological improvement compared with patients with an earlier intervention. Our data demonstrate that delayed surgical decompression for DCM exacerbates reperfusion injury and is associated with ongoing enhanced levels of cytokine expression, microglia activation, and astrogliosis, and paralleled with poorer neurological recovery.
Pia M. Vidal, Spyridon K. Karadimas, Antigona Ulndreaj, Alex M. Laliberte, Lindsay Tetreault, Stefania Forner, Jian Wang, Warren D. Foltz, Michael G. Fehlings
Microglia play a critical role in the development and homeostasis of the CNS. While mobilization of microglia is critical for a number of pathologies, understanding of the mechanisms of their migration in vivo is limited and often based on similarities to macrophages. Kindlin3 deficiency as well as Kindlin3 mutations of integrin-binding sites abolish both integrin inside-out and outside-in signaling in microglia, thereby resulting in severe deficiencies in cell adhesion, polarization, and migration in vitro, which are similar to the defects observed in macrophages. In contrast, while Kindlin3 mutations impaired macrophage mobilization in vivo, they had no effect either on the population of microglia in the CNS during development or on mobilization of microglia and subsequent microgliosis in a model of multiple sclerosis. At the same time, acute microglial response to laser-induced injury was impaired by the lack of Kindlin3-integrin interactions. Based on 2-photon imaging of microglia in the brain, Kindlin3 is required for elongation of microglial processes toward the injury site and formation of phagosomes in response to brain injury. Thus, while Kindlin3 deficiency in human subjects is not expected to diminish the presence of microglia within CNS, it might delay the recovery process after injury, thereby exacerbating its complications.
Julia Meller, Zhihong Chen, Tejasvi Dudiki, Rebecca M. Cull, Rakhilya Murtazina, Saswat K. Bal, Elzbieta Pluskota, Samantha Stefl, Edward F. Plow, Bruce D. Trapp, Tatiana V. Byzova
Many extremely preterm infants (born before 28 gestational weeks [GWs]) develop cognitive impairment in later life, although the underlying pathogenesis is not yet completely understood. Our examinations of the developing human neocortex confirmed that neuronal migration continues beyond 23 GWs, the gestational week at which extremely preterm infants have live births. We observed larger numbers of ectopic neurons in the white matter of the neocortex in human extremely preterm infants with brain injury and hypothesized that altered neuronal migration may be associated with cognitive impairment in later life. To confirm whether preterm brain injury affects neuronal migration, we produced brain damage in mouse embryos by occluding the maternal uterine arteries. The mice showed delayed neuronal migration, ectopic neurons in the white matter, altered neuronal alignment, and abnormal corticocortical axonal wiring. Similar to human extremely preterm infants with brain injury, the surviving mice exhibited cognitive deficits. Activation of the affected medial prefrontal cortices of the surviving mice improved working memory deficits, indicating that decreased neuronal activity caused the cognitive deficits. These findings suggest that altered neuronal migration altered by brain injury might contribute to the subsequent development of cognitive impairment in extremely preterm infants.
Ken-ichiro Kubo, Kimiko Deguchi, Taku Nagai, Yukiko Ito, Keitaro Yoshida, Toshihiro Endo, Seico Benner, Wei Shan, Ayako Kitazawa, Michihiko Aramaki, Kazuhiro Ishii, Minkyung Shin, Yuki Matsunaga, Kanehiro Hayashi, Masaki Kakeyama, Chiharu Tohyama, Kenji F. Tanaka, Kohichi Tanaka, Sachio Takashima, Masahiro Nakayama, Masayuki Itoh, Yukio Hirata, Barbara Antalffy, Dawna D. Armstrong, Kiyofumi Yamada, Ken Inoue, Kazunori Nakajima
Motor dysfunction is a prominent and disabling feature of Huntington’s disease (HD), but the molecular mechanisms that dictate its onset and progression are unknown. The N-methyl-D-aspartate receptor 2A (NR2A) subunit regulates motor skill development and synaptic plasticity in medium spiny neurons (MSNs) of the striatum, cells that are most severely impacted by HD. Here, we document reduced NR2A receptor subunits on the dendritic membranes and at the synapses of MSNs in zQ175 mice that model HD. We identify that SorCS2, a vacuolar protein sorting 10 protein–domain (VPS10P-domain) receptor, interacts with VPS35, a core component of retromer, thereby regulating surface trafficking of NR2A in MSNs. In the zQ175 striatum, SorCS2 is markedly decreased in an age- and allele-dependent manner. Notably, SorCS2 selectively interacts with mutant huntingtin (mtHTT), but not WT huntingtin (wtHTT), and is mislocalized to perinuclear clusters in striatal neurons of human HD patients and zQ175 mice. Genetic deficiency of SorCS2 accelerates the onset and exacerbates the motor coordination deficit of zQ175 mice. Together, our results identify SorCS2 as an interacting protein of mtHTT and demonstrate that impaired SorCS2-mediated NR2A subunit trafficking to dendritic surface of MSNs is, to our knowledge, a novel mechanism contributing to motor coordination deficits of HD.
Qian Ma, Jianmin Yang, Teresa A. Milner, Jean-Paul G. Vonsattel, Mary Ellen Palko, Lino Tessarollo, Barbara L. Hempstead
Nonalcoholic fatty liver disease (NAFLD), characterized by an excess accumulation of hepatic triglycerides, is a growing health epidemic. While ER stress in the liver has been implicated in the development of NAFLD, the role of brain ER stress — which is emerging as a key contributor to a number of chronic diseases including obesity — in NAFLD remains unclear. These studies reveal that chemical induction of ER stress in the brain caused hepatomegaly and hepatic steatosis in mice. Conversely, pharmacological reductions in brain ER stress in diet-induced obese mice rescued NAFLD independent of body weight, food intake, and adiposity. Evaluation of brain regions involved revealed robust activation of ER stress biomarkers and ER ultrastructural abnormalities in the circumventricular subfornical organ (SFO), a nucleus situated outside of the blood-brain-barrier, in response to high-fat diet. Targeted reductions in SFO-ER stress in obese mice via SFO-specific supplementation of the ER chaperone 78-kDa glucose–regulated protein ameliorated hepatomegaly and hepatic steatosis without altering body weight, food intake, adiposity, or obesity-induced hypertension. Overall, these findings indicate a novel role for brain ER stress, notably within the SFO, in the pathogenesis of NAFLD.
Julie A. Horwath, Chansol Hurr, Scott D. Butler, Mallikarjun Guruju, Martin D. Cassell, Allyn L. Mark, Robin L. Davisson, Colin N. Young
We lack a mechanistic explanation for the stereotyped pattern of white matter loss seen in Huntington’s disease (HD). While the earliest white matter changes are seen around the striatum, within the corpus callosum, and in the posterior white matter tracts, the order in which these changes occur and why these white matter connections are specifically vulnerable is unclear. Here, we use diffusion tractography in a longitudinal cohort of individuals yet to develop clinical symptoms of HD to identify a hierarchy of vulnerability, where the topological length of white matter connections between a brain area and its neighbors predicts the rate of atrophy over 24 months. This demonstrates a new principle underlying neurodegeneration in HD, whereby brain connections with the greatest topological length are the first to suffer damage that can account for the stereotyped pattern of white matter loss observed in premanifest HD.
Peter McColgan, Kiran K. Seunarine, Sarah Gregory, Adeel Razi, Marina Papoutsi, Jeffrey D. Long, James A. Mills, Eileanoir Johnson, Alexandra Durr, Raymund A.C. Roos, Blair R. Leavitt, Julie C. Stout, Rachael I. Scahill, Chris A. Clark, Geraint Rees, Sarah J. Tabrizi, the Track-On HD Investigators
Shadab A. Rahman, Melissa A. St. Hilaire, Anne-Marie Chang, Nayantara Santhi, Jeanne F. Duffy, Richard E. Kronauer, Charles A. Czeisler, Steven W. Lockley, Elizabeth B. Klerman
Martin Niethammer, Chris C. Tang, Peter A. LeWitt, Ali R. Rezai, Maureen A. Leehey, Steven G. Ojemann, Alice W. Flaherty, Emad N. Eskandar, Sandra K. Kostyk, Atom Sarkar, Mustafa S. Siddiqui, Stephen B. Tatter, Jason M. Schwalb, Kathleen L. Poston, Jaimie M. Henderson, Roger M. Kurlan, Irene H. Richard, Christine V. Sapan, David Eidelberg, Matthew J. During, Michael G. Kaplitt, Andrew Feigin
Intracerebral hemorrhage (ICH) causes high mortality and morbidity, but our knowledge of post-ICH neuronal death and related mechanisms is limited. In this study, we first demonstrated that ferroptosis, a newly identified form of cell death, occurs in the collagenase-induced ICH model in mice. We found that administration of ferrostatin-1, a specific inhibitor of ferroptosis, prevented neuronal death and reduced iron deposition induced by hemoglobin in organotypic hippocampal slice cultures (OHSCs). Mice treated with ferrostatin-1 after ICH exhibited marked brain protection and improved neurologic function. Additionally, we found that ferrostatin-1 reduced lipid reactive oxygen species production and attenuated the increased expression level of
Qian Li, Xiaoning Han, Xi Lan, Yufeng Gao, Jieru Wan, Frederick Durham, Tian Cheng, Jie Yang, Zhongyu Wang, Chao Jiang, Mingyao Ying, Raymond C. Koehler, Brent R. Stockwell, Jian Wang
Surgery can induce cognitive decline, a risk that increases with advancing age. In rodents, postoperative cognitive decline (POCD) is associated with the inflammatory activation of hippocampal microglia. To examine the role of microglia in POCD, we inhibited the colony-stimulating factor 1 receptor (CSF1R) in adult mice, effectively depleting CNS microglia. Surgical trauma (tibial fracture) reduced the ability of mice to remember a conditioned response learned preoperatively, a deficit more pronounced and persistent in mice with diet-induced obesity (DIO). Whereas microglial depletion by itself did not affect learning or memory, perioperative microglial depletion remarkably protected mice, including those with DIO, from POCD. This protection was associated with reduced hippocampal levels of inflammatory mediators, abrogation of hippocampal recruitment of CCR2+ leukocytes, and higher levels of circulating inflammation-resolving factors. Targeting microglia may thus be a viable strategy to mitigate the development of POCD, particularly in those with increased vulnerability.
Xiaomei Feng, Martin Valdearcos, Yosuke Uchida, David Lutrin, Mervyn Maze, Suneil K. Koliwad
Molecular mechanisms underlying learning and memory remain imprecisely understood, and restorative interventions are lacking. We report that intranasal administration of siRNAs can be used to identify targets important in cognitive processes and to improve genetically impaired learning and memory. In mice modeling the intellectual deficiency of Fragile X syndrome, intranasally administered siRNA targeting glycogen synthase kinase-3β (GSK3β), histone deacetylase-1 (HDAC1), HDAC2, or HDAC3 diminished cognitive impairments. In WT mice, intranasally administered brain-derived neurotrophic factor (BDNF) siRNA or HDAC4 siRNA impaired learning and memory, which was partially due to reduced insulin-like growth factor-2 (IGF2) levels because the BDNF siRNA– or HDAC4 siRNA–induced cognitive impairments were ameliorated by intranasal IGF2 administration. In
Marta Pardo, Yuyan Cheng, Dmitry Velmeshev, Marco Magistri, Hagit Eldar-Finkelman, Ana Martinez, Mohammad A. Faghihi, Richard S. Jope, Eleonore Beurel
Neuroinflammation is a pathological hallmark of ALS in both transgenic rodent models and patients, and is characterized by proinflammatory T lymphocytes and activated macrophages/microglia. In ALS mouse models, decreased regulatory T lymphocytes (Tregs) exacerbate the neuroinflammatory process, leading to accelerated motoneuron death and shortened survival; passive transfer of Tregs suppresses the neuroinflammation and prolongs survival. Treg numbers and FOXP3 expression are also decreased in rapidly progressing ALS patients. A key question is whether the marked neuroinflammation in ALS can be attributed to the impaired suppressive function of ALS Tregs in addition to their decreased numbers. To address this question, T lymphocyte proliferation assays were performed. Compared with control Tregs, ALS Tregs were less effective in suppressing responder T lymphocyte proliferation. Although both slowly and rapidly progressing ALS patients had dysfunctional Tregs, the greater the clinically assessed disease burden or the more rapidly progressing the patient, the greater the Treg dysfunction. Epigenetically, the percentage methylation of the Treg-specific demethylated region was greater in ALS Tregs. After in vitro expansion, ALS Tregs regained suppressive abilities to the levels of control Tregs, suggesting that autologous passive transfer of expanded Tregs might offer a novel cellular therapy to slow disease progression.
David R. Beers, Weihua Zhao, Jinghong Wang, Xiujun Zhang, Shixiang Wen, Dan Neal, Jason R. Thonhoff, Abdullah S. Alsuliman, Elizabeth J. Shpall, Katy Rezvani, Stanley H. Appel
Spinal muscular atrophy (SMA) is a leading genetic cause of infantile death and is caused by the loss of survival motor neuron-1 (
Kevin A. Kaifer, Eric Villalón, Erkan Y. Osman, Jacqueline J. Glascock, Laura L. Arnold, D.D.W. Cornelison, Christian L. Lorson
Decreased noradrenergic excitation of hypoglossal motoneurons during sleep causing hypotonia of pharyngeal dilator muscles is a major contributor to the pathogenesis of obstructive sleep apnea (OSA), a widespread disease for which treatment options are limited. Previous OSA drug candidates targeting various excitatory/inhibitory receptors on hypoglossal motoneurons have proved unviable in reactivating these neurons, particularly during rapid-eye-movement (REM) sleep. To identify a viable drug target, we show that the repurposed α2-adrenergic antagonist yohimbine potently reversed the depressant effect of REM sleep on baseline hypoglossal motoneuron activity (a first-line motor defense against OSA) in rats. Remarkably, yohimbine also restored the obstructive apnea–induced long-term facilitation of hypoglossal motoneuron activity (hLTF), a much-neglected form of noradrenergic-dependent neuroplasticity that could provide a second-line motor defense against OSA but was also depressed during REM sleep. Corroborating immunohistologic, optogenetic, and pharmacologic evidence confirmed that yohimbine’s beneficial effects on baseline hypoglossal motoneuron activity and hLTF were mediated mainly through activation of pontine A7 and A5 noradrenergic neurons. Our results suggest a 2-tier (impaired first- and second-line motor defense) mechanism of noradrenergic-dependent pathogenesis of OSA and a promising pharmacotherapy for rescuing both these intrinsic defenses against OSA through disinhibition of A7 and A5 neurons by α2-adrenergic blockade.
Gang Song, Chi-Sang Poon
A role for oxidative stress in the brain has been suggested in the pathogenesis of diet-induced obesity (DIO), although the underlying neural regions and mechanisms remain incompletely defined. We tested the hypothesis that NADPH oxidase–dependent oxidative stress in the paraventricular nucleus (PVN), a hypothalamic energy homeostasis center, contributes to the development of DIO. Cre/LoxP technology was coupled with selective PVN adenoviral microinjection to ablate
Heinrich E. Lob, Jiunn Song, Chansol Hurr, Alvin Chung, Colin N. Young, Allyn L. Mark, Robin L. Davisson
The sympathetic nervous system (SNS) accelerates heart rate, increases cardiac contractility, and constricts resistance vessels. The activity of SNS efferent nerves is generated by a complex neural network containing neurons and glia. Gq G protein–coupled receptor (Gq-GPCR) signaling in glial fibrillary acidic protein–expressing (GFAP+) glia in the central nervous system supports neuronal function and regulates neuronal activity. It is unclear how Gq-GPCR signaling in GFAP+ glia affects the activity of sympathetic neurons or contributes to SNS-regulated cardiovascular functions. In this study, we investigated whether Gq-GPCR activation in GFAP+ glia modulates the regulatory effect of the SNS on the heart; transgenic mice expressing Gq-coupled DREADD (designer receptors exclusively activated by designer drugs) (hM3Dq) selectively in GFAP+ glia were used to address this question in vivo. We found that acute Gq-GPCR activation in peripheral GFAP+ glia significantly accelerated heart rate and increased left ventricle contraction. Pharmacological experiments suggest that the glial-induced cardiac changes were due to Gq-GPCR activation in satellite glial cells within the sympathetic ganglion; this activation led to increased norepinephrine (NE) release and beta-1 adrenergic receptor activation within the heart. Chronic glial Gq-GPCR activation led to hypotension in female
Alison Xiaoqiao Xie, Jakovin J. Lee, Ken D. McCarthy
The creation of a humanized chimeric mouse nervous system permits the study of human neural development and disease pathogenesis using human cells in vivo. Humanized glial chimeric mice with the brain and spinal cord being colonized by human glial cells have been successfully generated. However, generation of humanized chimeric mouse brains repopulated by human neurons to possess a high degree of chimerism have not been well studied. Here we created humanized neuronal chimeric mouse brains by neonatally engrafting the distinct and highly neurogenic human induced pluripotent stem cell (hiPSC)–derived rosette-type primitive neural progenitors. These neural progenitors predominantly differentiate to neurons, which disperse widely throughout the mouse brain with infiltration of the cerebral cortex and hippocampus at 6 and 13 months after transplantation. Building upon the hiPSC technology, we propose that this potentially unique humanized neuronal chimeric mouse model will provide profound opportunities to define the structure, function, and plasticity of neural networks containing human neurons derived from a broad variety of neurological disorders.
Chen Chen, Woo-Yang Kim, Peng Jiang
Counteracting the progressive neurological disability caused by neuronal and axonal loss is the major unmet clinical need in multiple sclerosis therapy. However, the mechanisms underlying irreversible neuroaxonal degeneration in multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE) are not well understood. A long-standing hypothesis holds that the distribution of voltage-gated sodium channels along demyelinated axons contributes to neurodegeneration by increasing neuroaxonal sodium influx and energy demand during CNS inflammation. Here, we tested this hypothesis in vivo by inserting a human gain-of-function mutation in the mouse NaV1.2-encoding gene
Benjamin Schattling, Walid Fazeli, Birgit Engeland, Yuanyuan Liu, Holger Lerche, Dirk Isbrandt, Manuel A. Friese
Levodopa-induced dyskinesia (LID) is the most common, disruptive complication of Parkinson’s disease (PD) pharmacotherapy, yet despite decades of research, the changes in regional brain function underlying LID remain largely unknown. We previously found that the cerebral vasomotor and metabolic responses to levodopa are dissociated in PD subjects. Nonetheless, it is unclear whether levodopa-mediated dissociation is exaggerated in LID or distinguishes LID from non-LID subjects. To explore this possibility, we used dual-tracer positron emission tomography to quantify regional cerebral blood flow and metabolic activity in 28 PD subjects (14 LID, 14 non-LID), scanned before and during intravenous levodopa infusion. Levodopa-mediated dissociation was most prominent in the posterior putamen (
Vincent A. Jourdain, Chris C. Tang, Florian Holtbernd, Christian Dresel, Yoon Young Choi, Yilong Ma, Vijay Dhawan, David Eidelberg
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