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This study aimed to investigate the histopathological changes associated with SARS-CoV-2 infection in placentas. A case series of anatomopathological analysis was conducted on the placentas of pregnant women with SARS-CoV-2 who delivered between March and December 2020 at Santo Amaro Hospital (HSA) in Salvador, Brazil. Out of the 29 placentas examined, the median weight was 423.0 (IQR: 385.0-521.0) g. Among them, 58.3% (n = 14) had inadequate weight relative to the newborn's weight. The histopathological findings revealed that 86.2% (n = 25) of the placentas had poorly defined lobes, and the fetal and maternal surface color was normal in 89.7% (n = 26) and 93.1% (n = 27), respectively. Additionally, 51.7% (n = 15) of the umbilical cords displayed hypercoiling. The most frequent microscopic finding was infarction, present in 35.3% (n = 6) of the cases, followed by 11.8% (n = 2) for each of chorioamnionitis, chronic villitis, focal perivillositis, and laminar necrosis. Analysis of the umbilical cords identified 23.5% (n = 4) cases of intervillous thrombosis, while amnion analysis showed 13.8% (n = 4) cases of squamous metaplasia. Extraplacental membrane examination revealed fibrin deposition in 93.1% (n = 27) of the cases, necrosis in 62.0% (n = 18), calcifications in 51.7% (n = 15), cysts in 37.9% (n = 11), neutrophilic exudate in 17.2% (n = 5), thrombosis in 13.7% (n = 4), and delayed placental maturation in 6.9% (n = 2). All analyzed placentas exhibited histopathological changes, primarily vascular and inflammatory, which indicate SARS-CoV-2 infection in term pregnancies. These alterations could be associated with impaired placental function, fetal growth restriction, preeclampsia, and prematurity. However, further prospective studies are required to validate the type, prevalence, and prognosis of each of these changes.
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X-linked myopathy with excessive autophagy (XMEA) is a genetic disease associated with weakness of the proximal muscles. It is caused by mutations in the VMA21 gene, coding for a chaperone that functions in the vacuolar ATPase (v-ATPase) assembly. Mutations associated with lower content of assembled v-ATPases lead to an increase in lysosomal pH, culminating in partial blockage of macroautophagy, with accumulation of vacuoles of undigested content. Here, we studied a 5-year-old boy affected by XMEA, caused by a small indel in the VMA21 gene. Detection of sarcoplasmic Lc3 (also known as MAP1LC3B)-positive vacuoles in his muscle biopsy confirmed an autophagy defect. To understand how autophagy is regulated in XMEA myogenesis, we used patient-derived muscle cells to evaluate autophagy during in vitro muscle differentiation. An increase in lysosomal pH was observed in the patient's cells, compatible with predicted functional defect of his mutation. Additionally, there was an increase in autophagic flux in XMEA myotubes. Interestingly, we observed that differentiation of XMEA myoblasts was altered, with increased myotube formation observed through a higher fusion index, which was not dependent on lysosomal acidification. Moreover, no variation in the expression of myogenic factors nor the presence of regenerating fibers in the patient's muscle were observed. Myoblast fusion is a tightly regulated process; therefore, the uncontrolled fusion of XMEA myoblasts might generate cells that are not as functional as normal muscle cells. Our data provide new evidence on the reason for predominant muscle involvement in the context of the XMEA phenotype.This article has an associated First Person interview with the first author of the paper.
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Diferenciación Celular , Enfermedades Genéticas Ligadas al Cromosoma X/patología , Músculo Esquelético/patología , Enfermedades Musculares/patología , Autofagia , Secuencia de Bases , Biopsia , Brasil , Proliferación Celular , Preescolar , Femenino , Regulación de la Expresión Génica , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Humanos , Recién Nacido , Lisosomas/metabolismo , Masculino , Fusión de Membrana , Desarrollo de Músculos/genética , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patología , Enfermedades Musculares/genética , Mioblastos/metabolismo , Mioblastos/patología , Linaje , ARN Mensajero/genética , ARN Mensajero/metabolismo , ATPasas de Translocación de Protón Vacuolares/genética , ATPasas de Translocación de Protón Vacuolares/metabolismo , Vacuolas/patología , Vacuolas/ultraestructuraRESUMEN
Satellite cells (SCs) are the main muscle stem cells responsible for its regenerative capacity. In muscular dystrophies, however, a failure of the regenerative process results in muscle degeneration and weakness. To analyze the effect of different degrees of muscle degeneration in SCs behavior, we studied adult muscle of the dystrophic strains: DMDmdx, Largemyd, DMDmdx/Largemyd, with variable histopathological alterations. Similar results were observed in the dystrophic models, which maintained normal levels of PAX7 expression, retained the Pax7-positive SCs pool, and their proliferation capacity. Moreover, elevated expression of MYOG, an important myogenic factor, was also observed. The ability to form new fibers was verified by the presence of dMyHC positive regenerating fibers. However, those fibers had incomplete maturation characteristics, such as small and homogenous fiber caliber, which could contribute to their dysfunction. We concluded that dystrophic muscles, independently of their degeneration degree, retain their SCs pool with proliferating and regenerative capacities. Nonetheless, the maturation of these new fibers is incomplete and do not prevent muscle degeneration. Taken together, these results suggest that the improvement of late muscle regeneration should better contribute to therapeutic approaches.
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Distrofias Musculares/patología , Distrofias Musculares/fisiopatología , Regeneración , Células Satélite del Músculo Esquelético/patología , Animales , Modelos Animales de Enfermedad , Regulación de la Expresión Génica , Antígeno Ki-67/metabolismo , Ratones Endogámicos C57BL , Ratones Endogámicos mdx , Desarrollo de Músculos/genética , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patología , Factor de Transcripción PAX7/metabolismo , Células Satélite del Músculo Esquelético/metabolismoRESUMEN
Dysferlin is a sarcolemmal muscle protein associated with the processes of membrane repair, trafficking, and fusion of intracellular vesicles and muscle regeneration. Mutations in the DYSF gene cause clinically distinct forms of muscular dystrophies. The dysferlin-deficient SJL/J mouse model presents a reduction of 85% of the protein but shows mild weakness and discrete histopathological alterations. To study the effect of dysferlin deficiency in the muscle regenerative process, we used a model of electrical injury by electroporation to induce muscle degeneration/regeneration in the SJL/J mouse. The relative expression of the genes Pax7, MyoD, Myf5, and Myog was accompanied by the histopathological evaluation during muscle recovery at different time points after injury. We also investigated the effects of dysferlin deficiency in the expression of genes encoding FAM65B and HDAC6 proteins, recently described as forming a tricomplex with dysferlin at the beginning of myoblast differentiation. We observed an altered time course through the process of degeneration and regeneration in dysferlin-deficient mice, with remarkable regenerative capacity characterized by a faster and effective response in the first days after injury, as compared to the WT mice. Also, dysferlin deficiency seems to significantly alter the gene expression of Fam65b and Hdac6 during regeneration, since higher levels of expression of both genes were observed in dysferlin-deficient mice. These results need further attention to define their relevance in the disease mechanism.
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Moléculas de Adhesión Celular/metabolismo , Disferlina/deficiencia , Histona Desacetilasa 6/metabolismo , Músculo Esquelético/fisiología , Regeneración/efectos de los fármacos , Animales , Moléculas de Adhesión Celular/farmacología , Disferlina/farmacología , Disferlina/fisiología , Regulación de la Expresión Génica/efectos de los fármacos , Histona Desacetilasa 6/farmacología , Ratones , Músculo Esquelético/lesiones , Factores de TiempoRESUMEN
Adult skeletal muscle is a postmitotic tissue with an enormous capacity to regenerate upon injury. This is accomplished by resident stem cells, named satellite cells, which were identified more than 50 years ago. Since their discovery, many researchers have been concentrating efforts to answer questions about their origin and role in muscle development, the way they contribute to muscle regeneration, and their potential to cell-based therapies. Satellite cells are maintained in a quiescent state and upon requirement are activated, proliferating, and fusing with other cells to form or repair myofibers. In addition, they are able to self-renew and replenish the stem pool. Every phase of satellite cell activity is highly regulated and orchestrated by many molecules and signaling pathways; the elucidation of players and mechanisms involved in satellite cell biology is of extreme importance, being the first step to expose the crucial points that could be modulated to extract the optimal response from these cells in therapeutic strategies. Here, we review the basic aspects about satellite cells biology and briefly discuss recent findings about therapeutic attempts, trying to raise questions about how basic biology could provide a solid scaffold to more successful use of these cells in clinics.
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The mdx mouse is a good genetic and molecular murine model for Duchenne Muscular Dystrophy (DMD), a progressive and devastating muscle disease. However, this model is inappropriate for testing new therapies due to its mild phenotype. Here, we transferred the mdx mutation to the 129/Sv strain with the aim to create a more severe model for DMD. Unexpectedly, functional analysis of the first three generations of mdx129 showed a progressive amelioration of the phenotype, associated to less connective tissue replacement, and more regeneration than the original mdxC57BL. Transcriptome comparative analysis was performed to identify what is protecting this new model from the dystrophic characteristics. The mdxC57BL presents three times more differentially expressed genes (DEGs) than the mdx129 (371 and 137 DEGs respectively). However, both models present more overexpressed genes than underexpressed, indicating that the dystrophic and regenerative alterations are associated with the activation rather than repression of genes. As to functional categories, the DEGs of both mdx models showed a predominance of immune system genes. Excluding this category, the mdx129 model showed a decreased participation of the endo/exocytic pathway and homeostasis categories, and an increased participation of the extracellular matrix and enzymatic activity categories. Spp1 gene overexpression was the most significant DEG exclusively expressed in the mdx129 strain. This was confirmed through relative mRNA analysis and osteopontin protein quantification. The amount of the 66 kDa band of the protein, representing the post-translational product of the gene, was about 4,8 times higher on western blotting. Spp1 is a known DMD prognostic biomarker, and our data indicate that its upregulation can benefit phenotype. Modeling the expression of the DEGs involved in the mdx mutation with a benign course should be tested as a possible therapeutic target for the dystrophic process.
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Ratones de la Cepa 129 , Ratones Endogámicos mdx , Distrofia Muscular de Duchenne/genética , Mutación , Fenotipo , Animales , Modelos Animales de Enfermedad , Femenino , Perfilación de la Expresión Génica , Masculino , Ratones , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Músculo Esquelético/fisiopatología , Distrofia Muscular de Duchenne/patología , Distrofia Muscular de Duchenne/fisiopatología , Factores Protectores , TranscriptomaRESUMEN
Amyotrophic lateral sclerosis (ALS) is a progressive and lethal disease of motor neuron degeneration, leading to paralysis of voluntary muscles and death by respiratory failure within five years of onset. Frontotemporal dementia (FTD) is characterised by degeneration of frontal and temporal lobes, leading to changes in personality, behaviour, and language, culminating in death within 5-10 years. Both of these diseases form a clinical, pathological, and genetic continuum of diseases, and this link has become clearer recently with the discovery of a hexanucleotide repeat expansion in the C9orf72 gene that causes the FTD/ALS spectrum, that is, c9FTD/ALS. Two basic mechanisms have been proposed as being potentially responsible for c9FTD/ALS: loss-of-function of the protein encoded by this gene (associated with aberrant DNA methylation) and gain of function through the formation of RNA foci or protein aggregates. These diseases currently lack any cure or effective treatment. Antisense oligonucleotides (ASOs) are modified nucleic acids that are able to silence targeted mRNAs or perform splice modulation, and the fact that they have proved efficient in repeat expansion diseases including myotonic dystrophy type 1 makes them ideal candidates for c9FTD/ALS therapy. Here, we discuss potential mechanisms and challenges for developing oligonucleotide-based therapy for c9FTD/ALS.
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OBJECTIVE: Brain natriuretic peptide (BNP) has potent lipolytic action and, probably, a role in the biological mechanisms of obesity. Clinically, high levels are found in subjects with heart failure (HF). Low levels and inverse relation to BMI lead to questioning of its clinical utility in obese subjects, but heterogeneous results are found in severe obesity. METHODS: In order to describe BNP behavior and its metabolic and cardiovascular determinants in class III obesity, we performed BNP measurement as well as clinical and echocardiographic evaluation of 89 subjects from two public hospitals in Brazil. Multivariate logistic ordinal regression with BNP tertiles as the dependent variable was performed. RESULTS: Mean (± SD) age and BMI (± SD) was 44 ± 11.5 years and 53.2 ± 7.9 kg/m(2), respectively. 72 (81%) participants were women, and 18 (20%) had HF. Median BNP was 9.5 pg/ml(Q1 4.9; Q3 21.2 pg/ml). 30% of BNP values were below the detection limit of the method. In multivariate analysis, left atrial volume (LAV) was the only determinant of BNP levels (p 0.002) with odds-ratio of 1.1 (95% CI 1.03-1.16). CONCLUSION: BNP levels are low in severe obesity, even in subjects with HF. LAV, which marks diastolic dysfunction, determines BNP levels, but not BMI and metabolic abnormalities.