RESUMEN
BACKGROUND: Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder that affects cognitive and motor abilities by primarily targeting the striatum and cerebral cortex. HD is caused by a mutation elongating the CAG repeats within the Huntingtin gene, resulting in HTT protein misfolding. Although the genetic cause of HD has been established, the specific susceptibility of neurons within various brain structures has remained elusive. Microglia, which are the brain's resident macrophages, have emerged as important players in neurodegeneration. Nevertheless, few studies have examined their implication in HD. METHODS: To provide novel insights, we investigated the maturation and dysfunction of striatal microglia using the R6/2 mouse model of HD. This transgenic model, which presents with 120+/-5 CAG repeats, displays progressive motor deficits beginning at 6 weeks of age, with full incapacitation by 13 weeks. We studied microglial morphology, phagocytic capacity, and synaptic contacts in the striatum of R6/2 versus wild-type (WT) littermates at 3, 10, and 13 weeks of age, using a combination of light and transmission electron microscopy. We also reconstructed dendrites and determined synaptic density within the striatum of R6/2 and WT littermates, at nanoscale resolution using focused ion beam scanning electron microscopy. RESULTS: At 3 weeks of age, prior to any known motor deficits, microglia in R6/2 animals displayed a more mature morphological phenotype than WT animals. Microglia from R6/2 mice across all ages also demonstrated increased phagocytosis, as revealed by light microscopy and transmission electron microscopy. Furthermore, microglial processes from 10-week-old R6/2 mice made fewer contacts with synaptic structures than microglial processes in 3-week-old R6/2 mice and age-matched WT littermates. Synaptic density was not affected by genotype at 3 weeks of age but increased with maturation in WT mice. The location of synapses was lastly modified in R6/2 mice compared with WT controls, from targeting dendritic spines to dendritic trunks at both 3 and 10 weeks of age. CONCLUSIONS: These findings suggest that microglia may play an intimate role in synaptic alteration and loss during HD pathogenesis.
Asunto(s)
Microglía/metabolismo , Neuronas/metabolismo , Sinapsis/metabolismo , Animales , Forma de la Célula/fisiología , Modelos Animales de Enfermedad , Femenino , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Enfermedad de Huntington/genética , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Masculino , Ratones , Ratones Transgénicos , Microglía/patología , Neuronas/patología , Sinapsis/patologíaRESUMEN
BACKGROUND: Alzheimer's disease (AD) is the most common neurodegenerative disease, characterized by the deposition of extracellular fibrillar amyloid ß (fΑß) and the intracellular accumulation of neurofibrillary tangles. As AD progresses, Aß drives a robust and prolonged inflammatory response via its recognition by microglia, the brain's immune cells. Microglial reactivity to fAß plaques may impair their normal surveillance duties, facilitating synaptic loss and neuronal death, as well as cognitive decline in AD. METHODS: In the current study, we performed correlative light, transmission, and scanning electron microscopy to provide insights into microglial structural and functional heterogeneity. We analyzed microglial cell bodies and processes in areas containing fAß plaques and neuronal dystrophy, dystrophy only, or appearing healthy, among the hippocampus CA1 of 14-month-old APPSwe-PS1Δe9 mice versus wild-type littermates. RESULTS: Our quantitative analysis revealed that microglial cell bodies in the AD model mice were larger and displayed ultrastructural signs of cellular stress, especially nearby plaques. Microglial cell bodies and processes were overall less phagocytic in AD model mice. However, they contained increased fibrillar materials and non-empty inclusions proximal to plaques. Microglial cell bodies and processes in AD model mice also displayed reduced association with extracellular space pockets that contained debris. In addition, microglial processes in healthy subregions of AD model mice encircled synaptic elements more often compared with plaque-associated processes. These observations in mice were qualitatively replicated in post-mortem hippocampal samples from two patients with AD (Braak stage 5). CONCLUSION: Together, our findings identify at the ultrastructural level distinct microglial transformations common to mouse and human in association with amyloid pathology.
Asunto(s)
Enfermedad de Alzheimer/patología , Microglía/patología , Microglía/ultraestructura , Anciano , Anciano de 80 o más Años , Péptidos beta-Amiloides , Animales , Hipocampo/patología , Hipocampo/ultraestructura , Humanos , RatonesRESUMEN
The past decade has witnessed a revolution in our understanding of microglia. These immune cells were shown to actively remodel neuronal circuits, leading to propose new pathogenic mechanisms. To study microglial implication in the loss of synapses, the best pathological correlate of cognitive decline across chronic stress, aging, and diseases, we recently conducted ultrastructural analyses. Our work uncovered the existence of a new microglial phenotype that is rarely present under steady state conditions, in hippocampus, cerebral cortex, amygdala, and hypothalamus, but becomes abundant during chronic stress, aging, fractalkine signaling deficiency (CX3 CR1 knockout mice), and Alzheimer's disease pathology (APP-PS1 mice). Even though these cells display ultrastructural features of microglia, they are strikingly distinct from the other phenotypes described so far at the ultrastructural level. They exhibit several signs of oxidative stress, including a condensed, electron-dense cytoplasm and nucleoplasm making them as "dark" as mitochondria, accompanied by a pronounced remodeling of their nuclear chromatin. Dark microglia appear to be much more active than the normal microglia, reaching for synaptic clefts, while extensively encircling axon terminals and dendritic spines with their highly ramified and thin processes. They stain for the myeloid cell markers IBA1 and GFP (in CX3 CR1-GFP mice), and strongly express CD11b and microglia-specific 4D4 in their processes encircling synaptic elements, and TREM2 when they associate with amyloid plaques. Overall, these findings suggest that dark microglia, a new phenotype that we identified based on their unique properties, could play a significant role in the pathological remodeling of neuronal circuits, especially at synapses.
Asunto(s)
Envejecimiento/patología , Enfermedad de Alzheimer/patología , Corteza Cerebral/patología , Microglía/patología , Estrés Psicológico/patología , Aldehído Deshidrogenasa/genética , Aldehído Deshidrogenasa/metabolismo , Enfermedad de Alzheimer/genética , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Antígenos CD/metabolismo , Receptor 1 de Quimiocinas CX3C , Modelos Animales de Enfermedad , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Proteínas del Tejido Nervioso/metabolismo , Oxidorreductasas actuantes sobre Donantes de Grupo CH-NH , Fenotipo , Presenilina-1/genética , Presenilina-1/metabolismo , Receptores de Quimiocina/genética , Receptores de Quimiocina/metabolismo , Estrés Psicológico/genéticaRESUMEN
It has been hypothesized that selective serotonin reuptake inhibitors (SSRIs), the most common treatment for major depression, affect mood through changes in immune function. However, the effects of SSRIs on inflammatory response are contradictory since these act either as anti- or pro-inflammatory drugs. Previous experimental and clinical studies showed that the quality of the living environment moderates the outcome of antidepressant treatment. Therefore, we hypothesized that the interplay between SSRIs and the environment may, at least partially, explain the apparent incongruence regarding the effects of SSRI treatment on the inflammatory response. In order to investigate such interplay, we exposed C57BL/6 mice to chronic stress to induce a depression-like phenotype and, subsequently, to fluoxetine treatment or vehicle (21days) while being exposed to either an enriched or a stressful condition. At the end of treatment, we measured the expression levels of several anti- and pro-inflammatory cytokines and inflammatory mediators in the whole hippocampus and in isolated microglia. We also determined microglial density, distribution, and morphology to investigate their surveillance state. Results show that the effects of fluoxetine treatment on inflammation and microglial function, as compared to vehicle, were dependent on the quality of the living environment. In particular, fluoxetine administered in the enriched condition increased the expression of pro-inflammatory markers compared to vehicle, while treatment in a stressful condition produced anti-inflammatory effects. These findings provide new insights regarding the effects of SSRIs on inflammation, which may be crucial to devise pharmacological strategies aimed at enhancing antidepressant efficacy by means of controlling environmental conditions.
Asunto(s)
Encefalitis/metabolismo , Ambiente , Fluoxetina/administración & dosificación , Microglía/efectos de los fármacos , Inhibidores Selectivos de la Recaptación de Serotonina/administración & dosificación , Animales , Citocinas/metabolismo , Depresión , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Mediadores de Inflamación/metabolismo , Masculino , Ratones Endogámicos C57BL , Microglía/fisiología , Estrés PsicológicoRESUMEN
Cerebral vasospasm remains the most frequent and devastating complication after subarachnoid aneurysmal hemorrhage because of secondary cerebral ischemia and its sequelae. The underlying pathophysiology involves vasodilator peptide release (such as CGRP) and nitric oxide depletion at the level of the precapillary sphincters of the cerebral (internal carotid artery network) and dural (external carotid artery network) arteries, which are both innervated by craniofacial autonomic afferents and tightly connected to the trigeminal nerve and trigemino-cervical nucleus complex. We hypothesized that trigeminal nerve modulation could influence the cerebral flow of this vascular network through a sympatholytic effect and decrease the occurrence of vasospasm and its consequences. We conducted a prospective double-blind, randomized controlled pilot trial to compare the effect of 10 days of transcutaneous electrical trigeminal nerve stimulation vs. sham stimulation on cerebral infarction occurrence at 3 months. Sixty patients treated for aneurysmal SAH (World Federation of Neurosurgical Societies scale between 1 and 4) were included. We compared the radiological incidence of delayed cerebral ischemia (DCI) on magnetic resonance imaging (MRI) at 3 months in moderate and severe vasospasm patients receiving trigeminal nerve stimulation (TNS group) vs. sham stimulation (sham group). Our primary endpoint (the infarction rate at the 3-month follow-up) did not significantly differ between the two groups (p = 0.99). Vasospasm-related infarctions were present in seven patients (23%) in the TNS group and eight patients (27%) in the sham group. Ultimately, we were not able to show that TNS can decrease the rate of cerebral infarction secondary to vasospasm occurrence. As a result, it would be premature to promote trigeminal system neurostimulation in this context. This concept should be the subject of further research.
Asunto(s)
Isquemia Encefálica , Hemorragia Subaracnoidea , Vasoespasmo Intracraneal , Humanos , Hemorragia Subaracnoidea/complicaciones , Hemorragia Subaracnoidea/terapia , Vasoespasmo Intracraneal/etiología , Vasoespasmo Intracraneal/prevención & control , Estudios Prospectivos , Proyectos Piloto , Infarto Cerebral , Isquemia Encefálica/epidemiología , Nervio TrigéminoRESUMEN
The World Food Conference in 1974 emphasized the significance of establishing global nutrition surveillance to monitor and address nutritional challenges effectively. However, many countries, especially in the EMRO region, continue to encounter substantial difficulties in regularly generating disaggregated data on nutrition. The current study aimed to review the existing nutrition surveillance systems in the region and to identify their strengths and weaknesses, as well as the challenges they face in functioning optimally. METHODS: This study focused on the functional nutrition surveillance systems in eight Arab countries; namely Kuwait, Morocco, Oman, Palestine, Saudi Arabia, Sudan, Syria, and Yemen. The study's analysis involved utilizing primary data collected from both published and unpublished reports. Additionally, a structured checklist was employed to gather information from all countries involved in the study. Furthermore, interviews were conducted with the EMRO offices to gain deeper insights into the challenges, if any, that these nutrition surveillance systems face in functioning optimally. RESULTS: All countries use health facilities as a basic source of data for their nutrition surveillance, some countries triangulate their nutrition surveillance reports with data from other sources of information such as community or school surveys. Identified nutrition surveillance approaches are closely split between those who operate in stable settings and use routine health information systems (Morocco, Saudi Arabia, Oman, and Kuwait) and other countries that operate in fragile settings; for example, Yemen, Syria, Palestine, and Sudan struggle to provide early warning reports for rapid nutritional responses. CONCLUSIONS: Nutrition surveillance systems that utilize existing health information systems are the most sustained in the EMRO region. However, by integrating data from multiple sources, such as health facilities, surveys, and population censuses, countries can provide a holistic view of the nutritional situation, enhance their response to any emergency, and can leverage the infrastructure and resources already in place for health data collection and reporting. Collaboration between countries in the region through sharing experiences and success stories is important in order to reach a standardized system that can be implemented in different settings.
Asunto(s)
Árabes , Censos , Humanos , Lista de Verificación , Alimentos , Región MediterráneaRESUMEN
Recent advances in object detection facilitated by deep learning have led to numerous solutions in a myriad of fields ranging from medical diagnosis to autonomous driving. However, historical research is yet to reap the benefits of such advances. This is generally due to the low number of large, coherent, and annotated datasets of historical documents, as well as the overwhelming focus on Optical Character Recognition to support the analysis of historical documents. In this paper, we highlight the importance of visual elements, in particular illustrations in historical documents, and offer a public multi-class historical visual element dataset based on the Sphaera corpus. Additionally, we train an image extraction model based on YOLO architecture and publish it through a publicly available web-service to detect and extract multi-class images from historical documents in an effort to bridge the gap between traditional and computational approaches in historical studies.
RESUMEN
Epidemiological studies revealed that environmental factors comprising prenatal infection are strongly linked to risk for later development of neuropsychiatric disorders such as schizophrenia. Considering strong sex differences in schizophrenia and its increased prevalence in males, we designed a methodological approach to investigate possible sex differences in pathophysiological mechanisms. Prenatal immune challenge was modeled by systemic administration of the viral mimic polyinosinic-polycytidylic acid (Poly I:C) to C57BL/6 mice at embryonic day 9.5. The consequences on behavior, gene expression, and microglia-brain immune cells that are critical for normal development-were characterized in male vs. female offspring at adulthood. The cerebral cortex, hippocampus, and cerebellum, regions where structural and functional alterations were mainly described in schizophrenia patients, were selected for cellular and molecular analyses. Confocal and electron microscopy revealed most pronounced differences in microglial distribution, arborization, cellular stress, and synaptic interactions in the hippocampus of male vs. female offspring exposed to Poly I:C. Sex differences in microglia were also measured under both steady-state and Poly I:C conditions. These microglial alterations were accompanied by behavioral impairment, affecting for instance sensorimotor gating, in males. Consistent with these results, increased expression of genes related to inflammation was measured in cerebral cortex and hippocampus of males challenged with Poly I:C. Overall, these findings suggest that schizophrenia's higher incidence in males might be associated, among other mechanisms, with an increased microglial reactivity to prenatal immune challenges, hence determining disease outcomes into adulthood.
RESUMEN
A detailed protocol is provided here to identify amyloid Aß plaques in brain sections from Alzheimer's disease mouse models before pre-embedding immunostaining (specifically for ionized calcium-binding adapter molecule 1 (IBA1), a calcium binding protein expressed by microglia) and tissue processing for electron microscopy (EM). Methoxy-X04 is a fluorescent dye that crosses the blood-brain barrier and selectively binds to ß-pleated sheets found in dense core Aß plaques. Injection of the animals with methoxy-X04 prior to sacrifice and brain fixation allows pre-screening and selection of the plaque-containing brain sections for further processing with time-consuming manipulations. This is particularly helpful when studying early AD pathology within specific brain regions or layers that may contain very few plaques, present in only a small fraction of the sections. Post-mortem processing of tissue sections with Congo Red, Thioflavin S, and Thioflavin T (or even with methoxy-X04) can label ß-pleated sheets, but requires extensive clearing with ethanol to remove excess dye and these procedures are incompatible with ultrastructural preservation. It would also be inefficient to perform labeling for Aß (and other cellular markers such as IBA1) on all brain sections from the regions of interest, only to yield a small fraction containing Aß plaques at the right location. Importantly, Aß plaques are still visible after tissue processing for EM, allowing for a precise identification of the areas (generally down to a few square millimeters) to examine with the electron microscope.
Asunto(s)
Microglía , Placa Amiloide , Enfermedad de Alzheimer/diagnóstico , Péptidos beta-Amiloides , Animales , Barrera Hematoencefálica , Encéfalo , Ratones , Microscopía ElectrónicaRESUMEN
In mammals, adenosine 3', 5'-cyclic monophosphate (cAMP) is known to play highly important roles in sperm motility and acrosomal exocytosis. It is known to act through protein phosphorylation via PRKA and through the activation of guanine nucleotide exchange factors like EPAC. Sperm intracellular cAMP levels depend on the activity of adenylyl cyclases, mostly SACY, though transmembrane-containing adenylyl cyclases are also present, and on the activity of cyclic nucleotide phosphodiesterases (PDE) whose role is to degrade cAMP into 5'-AMP. The PDE superfamily is subdivided into 11 families (PDE1 to 11), which act on either cAMP or cGMP, or on both cAMP and cGMP although with different enzymatic properties. PDE10, which is more effective on cAMP than cGMP, has been known for almost 15 years and is mostly studied in the brain where it is associated with neurological disorders. Although a high level of PDE10A gene expression is observed in the testis, information on the identity of the isoforms or on the cell type that express the PDE10 protein is lacking. The objective of this study was to identify the PDE10A isoforms expressed in the testis and germ cells, and to determine the presence and localization of PDE10A in mature spermatozoa. As a sub-objective, since PDE10A transcript variants were reported strictly through analyses of bovine genomic sequence, we also wanted to determine the nucleotide and amino acid sequences by experimental evidence. Using RT-PCR, 5'- and 3'-RACE approaches we clearly show that PDE10A transcript variants X3 and X5 are expressed in bovine testis as well as in primary spermatocytes and spermatids. We also reveal using a combination of immunological techniques and proteomics analytical tools that the PDE10A isoform X4 is present in the area of the developing acrosome of spermatids and of the acrosome of mature spermatozoa.