RESUMO
Although SARS-CoV-2 induces mucin hypersecretion in the respiratory tract, hyposalivation/xerostomia has been reported by COVID-19 patients. We evaluate the submandibular gland (SMGs) pathogenesis in SARS-CoV-2-infected K18-hACE2 mice, focusing on the impact of infection on the mucin production and structural integrity of acini, ductal system, myoepithelial cells (MECs) and telocytes. The spike protein, the nucleocapsid protein, hACE2, actin, EGF, TNF-α and IL-1ß were detected by immunofluorescence, and the Egfr and Muc5b expression was evaluated. In the infected animals, significant acinar hypertrophy was observed in contrast to ductal atrophy. Nucleocapsid proteins and/or viral particles were detected in the SMG cells, mainly in the nuclear membrane-derived vesicles, confirming the nuclear role in the viral formation. The acinar cells showed intense TNF-α and IL-1ß immunoexpression, and the EGF-EGFR signaling increased, together with Muc5b upregulation. This finding explains mucin hypersecretion and acinar hypertrophy, which compress the ducts. Dying MECs and actin reduction were also observed, indicating failure of contraction and acinar support, favoring acinar hypertrophy. Viral assembly was found in the dying telocytes, pointing to these intercommunicating cells as viral transmitters in SMGs. Therefore, EGF-EGFR-induced mucin hypersecretion was triggered by SARS-CoV-2 in acinar cells, likely mediated by cytokines. The damage to telocytes and MECs may have favored the acinar hypertrophy, leading to ductal obstruction, explaining xerostomia in COVID-19 patients. Thus, acinar cells, telocytes and MECs may be viral targets, which favor replication and cell-to-cell viral transmission in the SMG, corroborating the high viral load in saliva of infected individuals.
Assuntos
COVID-19 , Receptores ErbB , SARS-CoV-2 , Glândula Submandibular , Xerostomia , COVID-19/patologia , COVID-19/virologia , COVID-19/metabolismo , Animais , Glândula Submandibular/virologia , Glândula Submandibular/patologia , Glândula Submandibular/metabolismo , SARS-CoV-2/fisiologia , Camundongos , Xerostomia/etiologia , Xerostomia/patologia , Xerostomia/virologia , Xerostomia/metabolismo , Receptores ErbB/metabolismo , Humanos , Enzima de Conversão de Angiotensina 2/metabolismo , Mucina-5B/metabolismo , Células Acinares/patologia , Células Acinares/metabolismo , Células Acinares/virologia , Interleucina-1beta/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Modelos Animais de DoençasRESUMO
Coronavirus Disease-19 (COVID-19) pandemic is caused by SARS-CoV-2 that has infected more than 600 million people and killed more than 6 million people worldwide. This infection affects mainly certain groups of people that have high susceptibility to present severe COVID-19 due to comorbidities. Moreover, the long-COVID-19 comprises a series of symptoms that may remain in some patients for months after infection that further compromises their health. Thus, since this pandemic is profoundly affecting health, economy, and social life of societies, a deeper understanding of viral replication cycle could help to envisage novel therapeutic alternatives that limit or stop COVID-19. Several findings have unexpectedly discovered that mitochondria play a critical role in SARS-CoV-2 cell infection. Indeed, it has been suggested that this organelle could be the origin of its replication niches, the double membrane vesicles (DMV). In this regard, mitochondria derived vesicles (MDV), involved in mitochondria quality control, discovered almost 15 years ago, comprise a subpopulation characterized by a double membrane. MDV shedding is induced by mitochondrial stress, and it has a fast assembly dynamic, reason that perhaps has precluded their identification in electron microscopy or tomography studies. These and other features of MDV together with recent SARS-CoV-2 protein interactome and other findings link SARS-CoV-2 to mitochondria and support that these vesicles are the precursors of SARS-CoV-2 induced DMV. In this work, the morphological, biochemical, molecular, and cellular evidence that supports this hypothesis is reviewed and integrated into the current model of SARS-CoV-2 cell infection. In this scheme, some relevant questions are raised as pending topics for research that would help in the near future to test this hypothesis. The intention of this work is to provide a novel framework that could open new possibilities to tackle SARS-CoV-2 pandemic through mitochondria and DMV targeted therapies.
Assuntos
COVID-19 , Mitocôndrias , SARS-CoV-2 , Humanos , Mitocôndrias/metabolismo , SARS-CoV-2/fisiologia , COVID-19/virologia , Replicação ViralRESUMO
Therapies that improve leptin sensitivity have potential as an alternative treatment approach against obesity and related comorbidities. We investigated the effects of Socs3 gene ablation in different mouse models to understand the role of SOCS3 in the regulation of leptin sensitivity, diet-induced obesity (DIO) and glucose homeostasis. Neuronal deletion of SOCS3 partially prevented DIO and improved glucose homeostasis. Inactivation of SOCS3 only in LepR-expressing cells protected against leptin resistance induced by HFD, but did not prevent DIO. However, inactivation of SOCS3 in LepR-expressing cells protected mice from diet-induced insulin resistance by increasing hypothalamic expression of Katp channel subunits and c-Fos expression in POMC neurons. In summary, the regulation of leptin signaling by SOCS3 orchestrates diet-induced changes on glycemic control. These findings help to understand the molecular mechanisms linking obesity and type 2 diabetes, and highlight the potential of SOCS3 inhibitors as a promising therapeutic approach for the treatment of diabetes.
RESUMO
Ghrelin is a stomach-derived peptide hormone that acts in the brain to regulate many important physiological functions. Ghrelin receptor, named the growth hormone secretagogue receptor (GHSR), is present in many brain areas with or without obvious direct access to ghrelin circulating in the bloodstream. Ghrelin is also present in the cerebrospinal fluid (CSF) but the brain targets of CSF ghrelin are unclear. Here, we studied which brain areas are accessible to ghrelin present in the CSF. For this purpose, we centrally injected mice with fluorescein-labeled ghrelin (F-ghrelin) peptide tracer and then systematically mapped the distribution of F-ghrelin signal through the brain. Our results indicated that centrally injected F-ghrelin labels neurons in most of the brain areas where GHSR is present. Also, we detected F-ghrelin uptake in the ependymal cells of both wild-type and GHSR-null mice. We conclude that CSF ghrelin is able to reach most of brain areas expressing GHSR. Also, we propose that the accessibility of CSF ghrelin to the brain parenchyma occurs through the ependymal cells in a GHSR-independent manner.
Assuntos
Encéfalo/fisiologia , Grelina/líquido cefalorraquidiano , Grelina/farmacologia , Receptores de Grelina/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Ingestão de Alimentos/efeitos dos fármacos , Fluoresceína/farmacocinética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , RNA Mensageiro/metabolismo , Receptores de Grelina/deficiência , Receptores de Grelina/genéticaRESUMO
ABSTRACT The objective of this work was to characterize the aspects related to the diameter of household aerosol droplets. The droplet spectra was determined in a particle size analyzer (Mastersizer S®, version 2.19). The experiment was carried out in a completely randomized design, arranged on a 6 x 2 factorial scheme, with six replications. Two samples were evaluated, of 6 different aerosols available on the market and codified as: BAT, REB, RCJ, RAT, SMI and M. The following parameters were analyzed: 1) the percentage of the sprayed volume containing drops with diameter equal to 15 µm or less; 2) the relative amplitude of the diameter of the droplets in the applied spurt; and the 3) the diameter of droplets for which 10% (Dv0.1), 50% (Dv0.5) and 90% (Dv0.9) of the sprayed volumes presented droplets with lesser diameters. The aerosols evaluated presented characteristics of droplets within the limits of effective tolerance according to the official resolution of the national regulating agency.
RESUMO O objetivo deste trabalho foi caracterizar os aspectos relacionados ao diâmetro de gotas de aerossóis domissanitários. O espectro de gotas foi determinado num analisador de partículas (Mastersizer S®, versão 2.19), utilizando o delineamento inteiramente casualizado em arranjo fatorial 6 x 2, com seis repetições. Avaliaram-se duas amostras, de seis diferentes marcas de aerossóis disponíveis no mercado e codificados como: BAT, REB, RCJ, RAT, SMI e M. Os seguintes parâmetros foram analisados: 1) a porcentagem do volume pulverizado contendo gotas com diâmetro igual ou inferior a 15 µm; 2) a amplitude relativa ao diâmetro de gotas do jato aplicado; e 3) os diâmetros de gotas para os quais 10% (Dv0,1), 50% (Dv0,5) e 90% (Dv0,9) dos volumes pulverizados apresentaram gotas de diâmetro inferiores. Os aerossóis avaliados apresentaram características de gotas que atenderam aos limites de tolerância vigente em resolução oficial da agência reguladora nacional.