RESUMO
The pathophysiology of traumatic brain injury (TBI) has not yet been fully elucidated. Crystallin alpha-B (CRYAB) is a molecular chaperone that apparently tries to stabilize the rapid thickening of the intermediate filaments of glial fibrillary acidic protein (GFAP) during the process of reactive astrogliosis in response to TBI. Previous analyses of the gene expression profile in human brain contusion tissue showed us an exacerbated CRYAB overexpression. Here, we used 3, 3'-diaminobenzidine (DAB) immunohistochemistry and immunofluorescence to verify CRYAB overexpression and to describe its expression and distribution in samples of contused cortical tissue derived from emergency decompressive surgery after severe TBI. The histological expression of CRYAB was mainly seen in subcortical white matter astrocytes of injured tissue. Most of the cells that overexpressed GFAP in the analyzed tissue also overexpressed CRYAB, a finding corroborated by the co-localization of the two markers. The only difference was the presence of a few pyramidal neurons that expressed CRYAB in layer V of the cerebral cortex. The selective vulnerability of layer V of the cerebral cortex during TBI could explain the expression of CRYAB in neurons of this cortical layer. Our results indicate a parallel behavior in the cellular expression of CRYAB and GFAP during the subacute response to TBI. These results lead us to postulate CRYAB as a possible marker of reactive astrogliosis in contused cortical tissue.
RESUMO
The von Economo neurons (VEN) are characterized by a large soma, spindle-like soma, with little dendritic arborization at both, the basal and apical poles. In humans, VENs have been described in the entorhinal cortex, the hippocampal formation, the anterior cingulate cortex, the rostral portion of the insula and the dorsomedial Brodmann's area 9 (BA9). These cortical regions have been associated with cognitive functions such as social interactions, intuition and emotional processing. Previous studies that searched for the presence of these cells in the lateral frontal poles yielded negative results. The presence of VENs in other cortical areas on the medial surface of the human prefrontal cortex which share both a common functional network and similar laminar organization, led us to examine its presence in the medial portion of the frontal pole. In the present study, we used tissue samples from five postmortem subjects taken from the polar portion of BA10, on the medial surface of both hemispheres. We found VENs in the human medial BA10, although they are very scarce and dispersed. We also observed crests and walls of the gyrus to quantitatively assess: (A) interhemispheric asymmetries, (B) the VENs/pyramidal ratio, (C) the area of the soma of VENs and (D) the difference in soma area between VENs and pyramidal and fusiform cells. We found that VENs are at least seven times more abundant on the right hemisphere and at least 2.5 times more abundant in the crest than in the walls of the gyrus. The soma size of VENs in the medial frontopolar cortex is larger than that of pyramidal and fusiform cells of layer VI, and their size is larger in the walls than in the crests. Our finding might be a contribution to the understanding of the role of these neurons in the functional networks in which all the areas in which they have been found are linked. However, the particularities of VENs in the frontal pole, as their size and quantity, may also lead us to interpret the findings in the light of other positions such as van Essen's theory of tension-based brain morphogenesis.
RESUMO
Introducción: El trauma craneoencefalico (TCE)es un fenómeno heterogéneo desde el punto de vista molecular, celular y en la respuesta clínica. Se considera que esta diversidad se debe a la intensidad de la injuria primaria, eventos secundarios asociados (hipoxia, isquemia, edema, inflamación), al estado metabólico del paciente, su base genética, edad, género, etc. Para determinar la integridad anatomo-funcional de las células nerviosas es importante verificar el estado de la cito, dendroarquitectura y preservación laminar como un requisito para garantizar conectividad. Objetivo: Valorar la respuesta de las neuronas al trauma con dos marcadores neuronales selectivos sensibles a la lesión NeuN y MAP2. Materiales y métodos: Se utilizaron muestras (4 de lóbulo temporal y 2 de lóbulo frontal) de 6 pacientes que habían sufrido TCE. Las muestras se fijaron en PLP, cortadas en vibrßtomo a 50 µm, incubadas con los anticuerpos NeuN y MAP2 y procesadas con el sistema avidina-biotina. Como control se utilizó tejido humano post-mortem. Resultados: La inmunorreactividad (IR) para NeuN fue anormal en todas las muestras, con sectores que mostraron IR ligeramente alterada, otros con perdida parcial de las capas supragranulares, sobre todo la lßmina III y otros con pérdida drastica de todas las laminas. La IR para MAP2 se alteró en todas las muestras con diferentes grados de compromiso. Los procesos dendríticos fueron difíciles de seguir, especialmente los procedentes de la lßmina V, los cuales se observaron tortuosos, fragmentados y con orientación aberrante. Conclusiones: Con el propósito de conocer el estado de las neuronas después de un evento lesivo se recomienda el uso de los marcadores NeuN y MAP2 complementarios a los métodos clasicos. El presente trabajo muestra la diversidad de respuestas histopatológicas en sectores adyacentes de una misma muestra con ambos marcadores, como un indicador de los diferentes estados de neurodegeneración.
Introduction: Traumatic brain injury (TBI) is a heterogeneous phenomenon from a molecular, cellular and pathological perspective. Clinical outcome is also extremely variable. It is considered that such a diversity response to TBI is related to the primary injury intensity, associated secondary events (hypoxia, ischemia, oedema and inflammation), metabolic patient state, genetic background, age, gender, etc. After injury the histopathological outcome is variable in time and space. In order to determine the anatomofunctional integrity of nerve cells in the cerebral cortex, it is important to verify the state of the cito and dendroarchitecture and the laminar preservation as a requisite to guarantee connectivity. Objective: The aim of the present work was to evaluate the response of human cortical neurons using two selective neuronal markers, NeuN and MAP2, which recognize citoarchitecture and dendritic arrangement, respectively. Materials and methods: In the present study we utilized six tissue samples (4 temporal and 2 frontal cortices) from TBI patients. Tissues from four post-mortem human brains were used as controls. Tissue samples were fixed in PLP, cut at 50 um in a vibratome, incubated with NeuN and MAP2 and processes with the avidin/biotin complex. Results: NeuN-IR was abnormal in all samples analyzed with some sectors showing slight NeuN-IR, others with NeuN-IR partial loss in supragranular layers, especially layer IIII, and other with a drastic reduction in staining in all cortical layers. MAP2-IR was altered across sections with sectors showing different degrees of changes in the normal pattern of MAP2-IR. Dendritic processes were difficult to follow because of its discontinuity. Layer V apical dendritic processes appear tortuous and its IR was fragmented in some cases they take aberrant orientations.