Neuroscience
Abstract
Understanding the reorganization of neural circuits spared after spinal cord injury in the motor cortex and spinal cord would provide insight for developing therapeutics. Using optogenetic mapping we demonstrate a transhemispheric recruitment of neural circuits in the contralateral cortical M1/M2 area to improve the impaired forelimb function after a cervical 5 right-sided hemisection in mice, a model mimicking the human Brown-Séquard syndrome. This cortical reorganization can be elicited by a selective cortical optogenetic neuromodulation paradigm. Areas of whisker, jaw, and neck, together with the rostral forelimb area, on the motor cortex ipsilateral to the lesion are engaged to control the ipsilesional forelimb in both stimulation and non-stimulation groups at 8 weeks post-injury. However, significant functional benefits are only seen in the stimulation group. Using anterograde tracer, we further reveal a robust sprouting of the intact corticospinal tract in the spinal cord of those animals receiving optogenetic stimulation. The intraspinal cortical spinal axonal sprouting corelates with the forelimb functional recovery. Thus, specific neuromodulation of the cortical neural circuits induces massive neural reorganization both in the motor cortex and spinal cord, constructing an alternative motor pathway in restoring impaired forelimb function.
Authors
Wei Wu, Tyler Nguyen, Josue D. Ordaz, Yi Ping Zhang, Nai-Kui Liu, Xinhua Hu, Yuxiang Liu, Xingjie Ping, Qi Han, Xiangbing Wu, Wenrui Qu, Sujuan Gao, Christopher B. Shields, Xiaoming Jin, Xiao-Ming Xu
Abstract
Biological aging is the strongest factor associated with the clinical phenotype of multiple sclerosis (MS). Relapsing remitting MS (RRMS) typically presents in the third or fourth decade, while the mean age of presentation of progressive MS (pMS) is 45 years old. Here we show that experimental autoimmune encephalomyelitis (EAE), induced by the adoptive transfer of encephalitogenic CD4+ Th17 cells, is more severe, and less like to remit, in middle-aged compared with young adult mice. Donor T cells and neutrophils are more abundant, while B cells are relatively sparse, in central nervous system (CNS) infiltrates of the older mice. Experiments with reciprocal bone marrow chimeras demonstrate that radio-resistant, non-hematopoietic cells play a dominant role in shaping age-dependent features of the neuroinflammatory response, as well as the clinical course, during EAE. Reminiscent of pMS, EAE in middle-aged adoptive transfer recipients is characterized by widespread microglial activation. Microglia from older mice express a distinctive transcriptomic profile, suggestive of enhanced chemokine synthesis and antigen presentation. Collectively, our findings suggest that drugs that suppress microglial activation, and acquisition or expression of aging-associated properties, may be beneficial in the treatment of progressive forms of inflammatory demyelinating disease.
Authors
Jeffrey R. Atkinson, Andrew D. Jerome, Andrew R. Sas, Ashley Munie, Cankun Wang, Anjun Ma, William D. Arnold, Benjamin M. Segal
Abstract
Rhodopsin (RHO)-associated retinitis pigmentosa (RP) is a progressive retinal disease that currently has no cure. RHO protein misfolding leads to disturbed proteostasis and the death of rod photoreceptors, resulting in decreased vision. We previously identified non-retinoid chaperones of RHO, including YC-001 and F5257-0462, by small-molecule high-throughput screening. Here, we profile the chaperone activities of these molecules towards the cell-surface level of 27 RP-causing human RHO mutants in NIH3T3 cells. Further, using retinal explant culture, we show that YC-001 improves retinal proteostasis by supporting RHO homeostasis in RhoP23H/+ mouse retinae, which results in thicker outer nuclear layers (ONL) indicating delayed photoreceptor degeneration. Interestingly, YC-001 ameliorated retinal immune responses and reduced the number of microglia/macrophages in the RhoP23H/+ retinal explants. Similarly, F5257-0462 also protects photoreceptors in RhoP23H/+ retinal explants. In vivo, intravitreal injection of YC-001 or F5257-0462 microparticles in PBS shows that F5257-0462 has a higher efficacy in preserving photoreceptor function and delaying photoreceptor death in RhoP23H/+ mice. Collectively, we provide proof of principle that non-retinoid chaperones are promising drug candidates in treating RHO-associated RP.
Authors
Abhishek Vats, Yibo Xi, Bing Feng, Owen D. Clinger, Anthony J. St. Leger, Xujie Liu, Archisha Ghosh, Chase D. Dermond, Kira L. Lathrop, Gregory P. Tochtrop, Serge Picaud, Yuanyuan Chen
Abstract
Inflammasomes are a class of innate immune signaling platforms that activate in response to an array of cellular damage and pathogens. Inflammasomes promote inflammation under many circumstances to enhance immunity against pathogens and inflammatory responses through their effector cytokines, IL-1β and IL-18. Multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE), are autoimmune conditions influenced by inflammasomes. Despite work investigating inflammasomes during EAE, little remains known concerning the role of inflammasomes in the central nervous system (CNS) during the disease. Here, we used multiple genetically modified mouse models to monitor activated inflammasomes in situ based on oligomerization of apoptosis-associated speck-like protein containing a CARD (ASC) in the spinal cord. Using inflammasome reporter mice, we found heightened inflammasome activation in astrocytes after the disease peak. In contrast, microglia and CNS-infiltrated myeloid cells had few activated inflammasomes in the CNS during EAE. Astrocyte inflammasome activation during EAE was dependent on absent in melanoma 2 (AIM2), but low IL-1β release and no significant signs of cell death were found. Thus, the AIM2 inflammasome activation in astrocytes may have a distinct role from traditional inflammasome-mediated inflammation.
Authors
William E. Barclay, Nupur Aggarwal, M. Elizabeth Deerhake, Makoto Inoue, Toshiaki Nonaka, Kengo Nozaki, Nathan A. Luzum, Edward A. Miao, Mari L. Shinohara
Abstract
Pain emanating from the female reproductive tract is notoriously difficult to be treated and the prevalence of transient pelvic pain has been placed as high as 70-80% in women surveyed. Although sex hormones, especially estrogen, are thought to underlie enhanced pain perception in females, the underlying molecular and cellular mechanisms are not completely understood. Here we show that the pain-initiating TRPA1 channel is required for pain-related behaviors in a mouse model of estrogen-induced uterine pain in ovariectomized female mice. Surprisingly, 2- and 4-hydroxylated estrogen metabolites (HEMs) in the estrogen hydroxylation pathway, but not estrone, estradiol and 16-HEMs, directly increase nociceptor hyperactivity through TRPA1 and TRPV1 channels, and picomolar concentrations of 2- and 4-hydroxylation estrone (OHE1) can sensitize TRPA1 channel function. Moreover, both TRPA1 and TRPV1 are expressed in uterine-innervating primary nociceptors and their expressions are increased in the estrogen-induced uterine pain model. Importantly, pretreatment of 2- or 4-OHE1 recapitulates estrogen-induced uterine pain-like behaviors and intraplantar injections of 2- and 4-OHE1 directly produce a TRPA1-dependent mechanical hypersensitivity. Our findings demonstrate that TRPA1 is critically involved in estrogen-induced uterine pain-like behaviors, which may provide a potential drug target for treating female reproductive tract pain.
Authors
Zili Xie, Jing Feng, Tao Cai, Ronald McCarthy, Mark D. Eschbach II, Yuhui Wang, Yonghui Zhao, Zhihua Yi, Kaikai Zang, Yi Yuan, Xueming Hu, Fengxian Li, Qin Liu, Aditi Das, Sarah K. England, Hongzhen Hu
Abstract
Multiple sclerosis (MS) is an autoimmune inflammatory disease of the CNS that is characterized by demyelination and axonal degeneration. Although several established treatments reduce relapse burden, effective treatments to halt chronic progression are scarce. Single-cell transcriptomic studies in MS and its animal models have described astrocytes and their spatial and functional heterogeneity as important cellular determinants of chronic disease. We combined CNS single-cell transcriptome data and small-molecule screens in primary mouse and human astrocytes to identify glial interactions, which could be targeted by repurposing FDA-approved small-molecule modulators for the treatment of acute and late-stage CNS inflammation. Using hierarchical in vitro and in vivo validation studies, we demonstrate that among selected pathways, blockade of ErbB by the tyrosine kinase inhibitor afatinib efficiently mitigates proinflammatory astrocyte polarization and promotes tissue-regenerative functions. We found that i.n. delivery of afatinib during acute and late-stage CNS inflammation ameliorates disease severity by reducing monocyte infiltration and axonal degeneration while increasing oligodendrocyte proliferation. We used unbiased screening approaches of astrocyte interactions to identify ErbB signaling and its modulation by afatinib as a potential therapeutic strategy for acute and chronic stages of autoimmune CNS inflammation.
Authors
Mathias Linnerbauer, Lena Lößlein, Oliver Vandrey, Thanos Tsaktanis, Alexander Beer, Ulrike J. Naumann, Franziska Panier, Tobias Beyer, Lucy Nirschl, Joji B. Kuramatsu, Jürgen Winkler, Francisco J. Quintana, Veit Rothhammer
Abstract
BACKGROUND. Potent synthetic opioids, such as fentanyl, are increasingly abused, resulting in unprecedented numbers of fatalities from respiratory depression. Treatment with the high-affinity mu-opioid receptor partial agonist buprenorphine may prevent fatalities by reducing binding of potent opioids to the opioid receptor, limiting respiratory depression. METHODS. To characterize buprenorphine-fentanyl interaction at the level of the mu-opioid receptor in two populations (opioid-naïve individuals and chronic users of high-dose opioids), the effects of escalating intravenous fentanyl doses with range 0.075-0.35 mg/70kg (opioid-naïve) and 0.25-0.70 mg/70 kg (chronic opioid users) on iso-hypercapnic ventilation at 2-3 background doses of buprenorphine (target plasma concentrations range: 0.2-5 ng/mL) were quantified using receptor association/dissociation models combined with biophase distribution models. RESULTS. Buprenorphine produced mild respiratory depression, while high doses of fentanyl caused pronounced respiratory depression and apnea in both populations. When combined with fentanyl, buprenorphine produced a receptor binding-dependent reduction of fentanyl-induced respiratory depression in both populations. In chronic opioid users, at buprenorphine plasma concentrations ≥2 ng/mL, a protective effect against high-dose fentanyl was observed. CONCLUSION. Overall, the results indicate that when buprenorphine mu-opioid receptor occupancy is sufficiently high, fentanyl is unable to activate the mu-opioid receptor and consequently will not cause further respiratory depression in addition to the mild respiratory effects of buprenorphine. TRIAL REGISTRATION. Trialregister.nl, number NL7028 (https://www.trialregister.nl/trial/7028) FUNDING. Indivior Inc., North Chesterfield, VA.
Authors
Erik Olofsen, Marijke Hyke Algera, Laurence Moss, Robert L. Dobbins, Geert J. Groeneveld, Monique van Velzen, Marieke Niesters, Albert Dahan, Celine M. Laffont
Abstract
Spinocerebellar ataxia type1 (SCA1) is an adult-onset neurodegenerative disorder. As disease progresses motor neurons are affected, and their dysfunction contributes towards the inability to maintain proper respiratory function, a major driving force for premature death in SCA1. To investigate the isolated role of motor neurons in SCA1 we created a novel conditional SCA1 (cSCA1) mouse model. This model suppresses expression of the pathogenic SCA1 allele with a floxed stop cassette. cSCA1 mice crossed to a ubiquitous Cre line recapitulate all the major features of the original SCA1 mouse model, except they took twice as long to develop. We found that the cSCA1 mice produce less than half of the pathogenic protein compared to the unmodified SCA1 mice at 3 weeks of age. In contrast, restricted expression of the pathogenic SCA1 allele in motor neurons only leads to a decreased distance traveled of mice in the open field assay and did not affect body weight or survival. We conclude that a fifty percent or greater reduction of the mutant protein has a dramatic effect on disease onset and progression, and that expression of polyglutamine expanded ATXN1 at this level specifically in motor neurons is not sufficient to cause premature lethality.
Authors
James P. Orengo, Larissa Nitschke, Meike E. van der Heijden, Nicholas A. Ciaburri, Harry T. Orr, Huda Y. Zoghbi
Abstract
Understanding the endogenous mechanisms regulating resolution of pain may identify novel targets for treatment of chronic pain. Resolution of chemotherapy-induced peripheral neuropathy (CIPN) after treatment completion depends on CD8+ T cells and on IL-10 produced by other cells. Using Rag2–/– mice lacking T and B cells and adoptive transfer of Il13–/– CD8+ T cells, we showed that CD8+ T cells producing IL-13 were required for resolution of CIPN. Intrathecal administration of anti–IL-13 delayed resolution of CIPN and reduced IL-10 production by dorsal root ganglion macrophages. Depleting local CD206+ macrophages also delayed resolution of CIPN. In vitro, TIM3+CD8+ T cells cultured with cisplatin, apoptotic cells, or phosphatidylserine liposomes produced IL-13, which induced IL-10 in macrophages. In vivo, resolution of CIPN was delayed by intrathecal administration of anti-TIM3. Resolution was also delayed in Rag2–/– mice reconstituted with Havcr2 (TIM3)–/– CD8+ T cells. Our data indicated that cell damage induced by cisplatin activated TIM3 on CD8+ T cells, leading to increased IL-13 production, which in turn induced macrophage IL-10 production and resolution of CIPN. Development of exogenous activators of the IL-13/IL-10 pain resolution pathway may provide a way to treat the underlying cause of chronic pain.
Authors
Susmita K. Singh, Karen Krukowski, Geoffroy O. Laumet, Drew Weis, Jenolyn F. Alexander, Cobi J. Heijnen, Annemieke Kavelaars
Abstract
BACKGROUND After the initial surge in COVID-19 cases, large numbers of patients were discharged from a hospital without assessment of recovery. Now, an increasing number of patients report postacute neurological sequelae, known as “long COVID” — even those without specific neurological manifestations in the acute phase.METHODS Dynamic brain changes are crucial for a better understanding and early prevention of “long COVID.” Here, we explored the cross-sectional and longitudinal consequences of COVID-19 on the brain in 34 discharged patients without neurological manifestations. Gray matter morphology, cerebral blood flow (CBF), and volumes of white matter tracts were investigated using advanced magnetic resonance imaging techniques to explore dynamic brain changes from 3 to 10 months after discharge.RESULTS Overall, the differences of cortical thickness were dynamic and finally returned to the baseline. For cortical CBF, hypoperfusion in severe cases observed at 3 months tended to recover at 10 months. Subcortical nuclei and white matter differences between groups and within subjects showed various trends, including recoverable and long-term unrecovered differences. After a 10-month recovery period, a reduced volume of nuclei in severe cases was still more extensive and profound than that in mild cases.CONCLUSION Our study provides objective neuroimaging evidence for the coexistence of recoverable and long-term unrecovered changes in 10-month effects of COVID-19 on the brain. The remaining potential abnormalities still deserve public attention, which is critically important for a better understanding of “long COVID” and early clinical guidance toward complete recovery.FUNDING National Natural Science Foundation of China.
Authors
Tian Tian, Jinfeng Wu, Tao Chen, Jia Li, Su Yan, Yiran Zhou, Xiaolong Peng, Yuanhao Li, Ning Zheng, Aoling Cai, Qin Ning, Hongbing Xiang, Fuqiang Xu, Yuanyuan Qin, Wenzhen Zhu, Jie Wang
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