23 research outputs found
Nuevas estrategias docentes en Histología. Más aprendizaje y menos enseñanza: Uso de microscopios virtuales e Historrelatos.
Current teaching at the University needs novel methodologies to increase students’ motivation. Here, we present two approaches to engage the student body to Human Histology subject at the University of Malaga. Virtual teaching was propelled by the COVID-19 crisis and confinement. The software for the study of histological/histopathological samples has become a valuable tool. Moreover, digital competences are in high demand within the biomedical field but students usually do not receive sufficient training. For these reasons, we have implemented the use of virtual microscopy (VM, Olympus), sharing 66 digitalized slides accessible under a username/password. VM provides real-time dynamic microscopy and offers an innovative experience at exceptionally high resolution. VM allows students to explore the samples online from anywhere, favoring autonomy and self-learning. Moreover, VM enables capturing specific tissue areas using these pictures to ask specific questions. On the other hand, transversal competences such as reading and writing skills, along with synthesis capability can be underdeveloped in our students. We initiated the activity of writing stories about histology contents (Histostories). Professional graphic designers from a webpage of scientific divulgation (masscience.com) illustrated the first story about erythrocytes. We conducted a survey among medical students to analyze the impact of this narration on their learning. Most of them welcome the initiative, considering it as an appropriate and enjoyable instrument for summarizing and revising the concepts. Immunity was among the topics more demanded between the students. Finally, we encouraged our students to write their own Histostories mentored by our teaching staff. These stories are shared through the virtual campus and on masscience website. So far, two medical students are collaborating with us in this experimental project that we expect it will bring more benefits to both readers and participants.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Distinct Microglial Responses in Two Transgenic Murine Models of TAU Pathology
Microglial cells are crucial players in the pathological process of neurodegenerative
diseases, such as Alzheimer’s disease (AD). Microglial response in AD has been
principally studied in relation to amyloid-beta pathology but, comparatively, little is known
about inflammatory processes associated to tau pathology. In the hippocampus of
AD patients, where tau pathology is more prominent than amyloid-beta pathology,
a microglial degenerative process has been reported. In this work, we have directly
compared the microglial response in two different transgenic tau mouse models:
ThyTau22 and P301S. Surprisingly, these two models showed important differences
in the microglial profile and tau pathology. Where ThyTau22 hippocampus manifested
mild microglial activation, P301S mice exhibited a strong microglial response in parallel
with high phospho-tau accumulation. This differential phospho-tau expression could
account for the different microglial response in these two tau strains. However, soluble
(S1) fractions from ThyTau22 hippocampus presented relatively high content of soluble
phospho-tau (AT8-positive) and were highly toxic for microglial cells in vitro, whereas
the correspondent S1 fractions from P301S mice displayed low soluble phosphotau
levels and were not toxic for microglial cells. Therefore, not only the expression
levels but the aggregation of phospho-tau should differ between both models. In fact,
most of tau forms in the P301S mice were aggregated and, in consequence, forming
insoluble tau species.We conclude that different factors as tau mutations, accumulation,
phosphorylation, and/or aggregation could account for the distinct microglial responses
observed in these two tau models. For this reason, deciphering the molecular nature of
toxic tau species for microglial cells might be a promising therapeutic approach in order
to restore the deficient immunological protection observed in AD hippocampus.CIBERNEDJunta de Andalucía. Consejería de Economía, Innovación, Ciencia y Empleo CTS-2035Fundación Tatiana Pérez de Guzmán el BuenoMinisterio de Ciencia, Innovación y UniversidadesInstituto de Salud Carlos III. Fondo de Investigación Sanitaria. PI15/00957 PI15/00796Fondo Europeo de Desarrollo Regional PI15/00957 PI15/0079
New teaching strategies in Histology. More learning and less teaching
Las transformaciones de la educación Médica conciernen a la Histología, ocasionando reducciones en la carga docente y asignación de créditos, redefinición de competencias y objetivos de aprendizaje, así como una creciente orientación médica de sus contenidos y una disminución de las clases magistrales.
Por ello se hace necesario el empleo de nuevos métodos que se aproximen más al aprendizaje que a la enseñanza, pero que no supongan ni un aumento de la carga docente del alumnado ni un incremento de los ya hipertrofiados planes de estudios.
En la Facultad de Medicina de Málaga hemos implementado nuevas metodologías docentes: orientación médica , clase inversa, ABP, microscopia virtual, HistolCasts), HistolWord, Instagram, Historrelatos), y evaluación continua .
Sobre estas actividades los estudiantes han mostrado un alto grado de participación y satisfacción, estimulando su interés y motivación por la Histología y mejorando el rendimiento académico. Adicionalmente, muchas de estas estrategias se pueden extrapolar a otras áreas de la educación médica, tanto para estudiantes como para residentes y formación continuada.
Algunas de estas metodologías ya han sido ya presentadas y otras lo serán por algunos de mis compañeros. Me voy a referir a continuación al HistolWord.
Se trata de una actividad de gamificación basada en el juego del pasapalabra, empleando términos histológicos. Se formaron 32 equipos de 5 estudiantes que compitieron en un sistema de eliminatorias desde dieciseisavos de final, confeccionándose 70 roscos de palabras. Todo se desarrollaba en un aula con casi 200 estudiantes, donde se leían las preguntas y se proyectaba el rosco, de manera que no solo participaban los dos equipos que se enfrentaban en ese momento, sino todos los presentes. Los estudiantes indicaron la utilidad de HistolWord como motivación para el estudio, complemento de las clases, revisión y aplicaciones médicas, existiendo una correlación positiva con las calificaciones.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec
Phagocytic clearance of presynaptic dystrophies by reactive astrocytes in Alzheimer's disease
Reactive astrogliosis, a complex process characterized by cell hypertrophy and upregulation ofcomponents of intermediate filaments, is a common feature in brains of Alzheimer’s patients. Reac-tive astrocytes are found in close association with neuritic plaques; however, the precise role ofthese glial cells in disease pathogenesis is unknown. In this study, using immunohistochemical tech-niques and light and electron microscopy, we report that plaque-associated reactive astrocytesenwrap, engulf and may digest presynaptic dystrophies in the hippocampus of amyloid precursorprotein/presenilin-1 (APP/PS1) mice. Microglia, the brain phagocytic population, was apparentlynot engaged in this clearance. Phagocytic reactive astrocytes were present in 35% and 67% ofamyloid plaques at 6 and 12 months of age, respectively. The proportion of engulfed dystrophicneurites was low, around 7% of total dystrophies around plaques at both ages. This fact, alongwith the accumulation of dystrophic neurites during disease course, suggests that the efficiency ofthe astrocyte phagocytic process might be limited or impaired. Reactive astrocytes surroundingand engulfing dystrophic neurites were also detected in the hippocampus of Alzheimer’spatientsby confocal and ultrastructural analysis. We posit that the phagocytic activity of reactive astrocytesmight contribute to clear dysfunctional synapses or synaptic debris, thereby restoring impairedneural circuits and reducing the inflammatory impact of damaged neuronal parts and/or limitingthe amyloid pathology. Therefore, potentiation of the phagocytic properties of reactive astrocytesmay represent a potential therapy in Alzheimer s disease.Fondo de Investigación Sanitaria (FIS). Instituto de Salud Carlos III (ISCiii) de España y fondos FEDER de la Unión Europea. PI15/00796 y PI15/00957Fundación La Marató-TV3 de Cataluña, España. 20141432, 20141431, 20141433, y 20141430Centro de investigación en red de enfermedades neurodegenerativas (CIBERNED) de España. PI2015-2/02Junta de Andalucía. Proyecto de Excelencia CTS-203
Plaque-Associated Oligomeric Amyloid-Beta Drives Early Synaptotoxicity in APP/PS1 Mice Hippocampus: Ultrastructural Pathology Analysis
Alzheimer’s disease (AD) is a devastating neurodegenerative disorder characterized by initial memory impairments that progress to dementia. In this sense, synaptic dysfunction and loss have been established as the pathological features that best correlate with the typical early cognitive decline in this disease. At the histopathological level, post mortem AD brains typically exhibit intraneuronal neurofibrillary tangles (NFTs) along with the accumulation of amyloid-beta (Abeta) peptides in the form of extracellular deposits. Specifically, the oligomeric soluble forms of Abeta are considered the most synaptotoxic species. In addition, neuritic plaques are Abeta deposits surrounded by activated microglia and astroglia cells together with abnormal swellings of neuronal processes named dystrophic neurites. These periplaque aberrant neurites are mostly presynaptic elements and represent the first pathological indicator of synaptic dysfunction. In terms of losing synaptic proteins, the hippocampus is one of the brain regions most affected in AD patients. In this work, we report an early decline in spatial memory, along with hippocampal synaptic changes, in an amyloidogenic APP/PS1 transgenic model. Quantitative electron microscopy revealed a spatial synaptotoxic pattern around neuritic plaques with significant loss of periplaque synaptic terminals, showing rising synapse loss close to the border, especially in larger plaques. Moreover, dystrophic presynapses were filled with autophagic vesicles in detriment of the presynaptic vesicular density, probably interfering with synaptic function at very early synaptopathological disease stages. Electron immunogold labeling showed that the periphery of amyloid plaques, and the associated dystrophic neurites, was enriched in Abeta oligomers supporting an extracellular location of the synaptotoxins. Finally, the incubation of primary neurons with soluble fractions derived from 6-month-old APP/PS1 hippocampus induced significant loss of synaptic proteins, but not neuronal death. Indeed, this preclinical transgenic model could serve to investigate therapies targeted at initial stages of synaptic dysfunction relevant to the prodromal and early AD.Instituto de Salud Carlos III (ISCiii) FEDER funds PI18/01557 and PI18/01556Junta de Andalucia UMA18-FEDERJA-211, P18-RT-2233 and US-126273Spanish Minister of Science and Innovation PID2019-108911RA-100, PID2019-107090RA-I00 and RYC-2017-21879Malaga University B1-2019_07 and B1-2019_0
Microglia in Alzheimer’s Disease: Activated, Dysfunctional or Degenerative
Microglial activation has been considered a crucial player in the pathological process of multiple human neurodegenerative diseases. In some of these pathologies, such as Amyotrophic Lateral Sclerosis or Multiple Sclerosis, the immune system and microglial cells (as part of the cerebral immunity) play a central role. In other degenerative processes, such as Alzheimer’s disease (AD), the role of microglia is far to be elucidated. In this “mini-review” article, we briefly highlight our recent data comparing the microglial response between amyloidogenic transgenic models, such as APP/PS1 and AD patients. Since the AD pathology could display regional heterogeneity, we focus our work at the hippocampal formation. In APP based models a prominent microglial response is triggered around amyloid-beta (Aβ) plaques. These strongly activated microglial cells could drive the AD pathology and, in consequence, could be implicated in the neurodegenerative process observed in models. On the contrary, the microglial response in human samples is, at least, partial or attenuated. This patent difference could simply reflect the lower and probably slower Aβ production observed in human hippocampal samples, in comparison with models, or could reflect the consequence of a chronic long-standing microglial activation. Beside this differential response, we also observed microglial degeneration in Braak V–VI individuals that, indeed, could compromise their normal role of surveying the brain environment and respond to the damage. This microglial degeneration, particularly relevant at the dentate gyrus, might be mediated by the accumulation of toxic soluble phospho-tau species. The consequences of this probably deficient immunological protection, observed in AD patients, are unknown.España, Instituto de Salud Carlos III PI15/00957, PI15/00796España Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucia Proyecto de Excelencia CTS-203
Distinct disease-sensitive GABAergic neurons in the perirhinal cortex of Alzheimer's mice and patients
Neuronal loss is the best neuropathological substrate that correlates with cortical atrophy and dementia in Alzheimer’s disease (AD). Defective GABAergic neuronal functions may lead to cortical network hyperactivity and aberrant neuronal oscilla-tions and in consequence, generate a detrimental alteration in memory processes. In this study, using immunohistochemical and stereological approaches, we report that the two major and non-overlapping groups of inhibitory interneurons (SOM-cells and PV-cells) displayed distinct vulnerability in the perirhinal cortex of APP/PS1 mice and AD patients. SOM-positive neurons were notably sensitive and exhibited a dramatic decrease in the perirhinal cortex of 6-month-old transgenic mice (57% and 61% in areas 36 and 35, respectively) and, most importantly, in AD patients (91% in Braak V–VI cases). In addition, this interneuron degenerative process seems to occur in parallel, and closely related, with the progression of the amyloid pathol-ogy. However, the population expressing PV was unaffected in APP/PS1 mice while in AD brains suffered a pronounced and significant loss (69%). As a key component of cortico-hippocampal networks, the perirhinal cortex plays an important role in memory processes, especially in familiarity-based memory recognition. Therefore, disrupted functional connectivity of this cortical region, as a result of the early SOM and PV neurodegeneration, might contribute to the altered brain rhythms and cognitive failures observed in the initial clinical phase of AD patients. Finally, these findings highlight the failure of amyloidogenic AD models to fully recapitulate the selective neuronal degeneration occurring in humans.Instituto de Salud Carlos III (ISCiii) de España y fondos FEDER de la Unión Europea. PI18/01557 y PI18/01556Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía. Proyecto de Excelencia CTS-2035Universidad de Málaga. PPIT.UMA.B1.2017/2
Litio como terapia neuroprotectora en el modelo appsl/ps1m146l de la enfermedad de Alzheimer
El litio se utiliza desde hace varias décadas en el tratamiento de trastornos bipolares y la depresión, y recientemente se debate su uso potencial en patologías neurodegenerativas como la enfermedad de Alzheimer (AD)
Defective lysosomal proteolysis and axonal transport are early pathogenic events that worsen with age leading to increased APP metabolism and synaptic Abeta in transgenic APP/PS1 hippocampus
Background: Axonal pathology might constitute one of the earliest manifestations of Alzheimer disease. Axonal dystrophies were observed in Alzheimer’s patients and transgenic models at early ages. These axonal dystrophies could reflect the disruption of axonal transport and the accumulation of multiple vesicles at local points. It has been also proposed that dystrophies might interfere with normal intracellular proteolysis. In this work, we have investigated the progression of the hippocampal pathology and the possible implication in Abeta production in young (6 months) and aged (18 months) PS1(M146L)/APP(751sl) transgenic mice.
Results: Our data demonstrated the existence of a progressive, age-dependent, formation of axonal dystrophies, mainly located in contact with congophilic Abeta deposition, which exhibited tau and neurofilament
hyperphosphorylation. This progressive pathology was paralleled with decreased expression of the motor proteins kinesin and dynein. Furthermore, we also observed an early decrease in the activity of cathepsins B and D, progressing to a deep inhibition of these lysosomal proteases at late ages. This lysosomal impairment could be responsible for the accumulation of LC3-II and ubiquitinated proteins within axonal dystrophies. We have also investigated the repercussion of these deficiencies on the APP metabolism. Our data demonstrated the existence of
an increase in the amyloidogenic pathway, which was reflected by the accumulation of hAPPfl, C99 fragment, intracellular Abeta in parallel with an increase in BACE and gamma-secretase activities. In vitro experiments, using APPswe transfected N2a cells, demonstrated that any imbalance on the proteolytic systems reproduced the in vivo alterations in APP metabolism. Finally, our data also demonstrated that Abeta peptides were preferentially accumulated in isolated synaptosomes.
Conclusion: A progressive age-dependent cytoskeletal pathology along with a reduction of lysosomal and, in minor extent, proteasomal activity could be directly implicated in the progressive accumulation of APP derived fragments (and Abeta peptides) in parallel with the increase of BACE-1 and gamma-secretase activities. This retard in the APP metabolism seemed to be directly implicated in the synaptic Abeta accumulation and, in consequence,
in the pathology progression between synaptically connected regions
Abnormal accumulation of autophagic vesicles correlates with axonal and synaptic pathology in young Alzheimer’s mice hippocampus
Dystrophic neurites associated with amyloid
plaques precede neuronal death and manifest early in
Alzheimer’s disease (AD). In this work we have characterized the plaque-associated neuritic pathology in the
hippocampus of young (4- to 6-month-old) PS1M146L/
APP751SL mice model, as the initial degenerative process
underlying functional disturbance prior to neuronal loss.
Neuritic plaques accounted for almost all fibrillar deposits
and an axonal origin of the dystrophies was demonstrated.
The early induction of autophagy pathology was evidenced
by increased protein levels of the autophagosome marker
LC3 that was localized in the axonal dystrophies, and by electron microscopic identification of numerous autophagic
vesicles filling and causing the axonal swellings. Early
neuritic cytoskeletal defects determined by the presence of
phosphorylated tau (AT8-positive) and actin–cofilin rods
along with decreased levels of kinesin-1 and dynein motor
proteins could be responsible for this extensive vesicle
accumulation within dystrophic neurites. Although microsomal Ab oligomers were identified, the presence of
A11-immunopositive Ab plaques also suggested a direct role
of plaque-associated Ab oligomers in defective axonal
transport and disease progression. Most importantly, presynaptic terminals morphologically disrupted by abnormal
autophagic vesicle buildup were identified ultrastructurally
and further supported by synaptosome isolation. Finally,
these early abnormalities in axonal and presynaptic structures might represent the morphological substrate of
hippocampal dysfunction preceding synaptic and neuronal
loss and could significantly contribute to AD pathology in the
preclinical stages.Fondo de Investigación Sanitaria (FIS). Instituto de Salud Carlos III, España. PS09/00099, PS09/00151, PS09/00848 y PS09/00376Junta de Andalucía. SAS P09/496 y CTS-479