Plasticity of cell proliferation in the retina of Austrolebias charrua fish under light and darkness conditions

Austrolebias annual fishes exhibit cell proliferation and neurogenesis throughout life. They withstand extreme environmental changes as their habitat dries out, pressuring nervous system to adapt. Their visual system is challenged to adjust as the water becomes turbid. Therefore, this study focused on how change in photic envi- ronment can lead to an increased cell proliferation in the retina. We administered 5-chloro-2′- deoxyuridine (CldU) and 5-iodo-2′-deoxyuridine (IdU) at different temporal windows to detect cell proliferation in natural light and permanent darkness. Stem/progenitor cells were recognized as IdU+/CldU+ nuclei co-labeled with Sox2, Pax6 or BLBP found in the ciliary marginal zone (CMZ). The expression pattern of BLBP + glial cells and ultrastructural analysis indicates that CMZ has different cell progenitors. In darkness, the number of dividing cells significantly increased, compared to light conditions. Surprisingly, CMZ IdU+/CldU + cell number was similar under light and darkness, suggesting a stable pool of stem/progenitor cells possibly responsible for retinal growth. Therefore, darkness stimulated cell progenitors outside the CMZ, where Müller glia play a crucial role to generate rod precursors and other cell types that might integrate rod-dependent circuits to allow darkness adaptation. Thus, the Austrolebias fish retina shows great plasticity, with cell proliferation rates significantly higher than that of brain visual areas

Phenotypic transition of microglia into astrocyte-like cells associated with disease onset in a model of inherited ALS

Microglia and reactive astrocytes accumulate in the spinal cord of rats expressing the Amyotrophic lateral sclerosis (ALS)-linked SOD1ᴳ⁹³ᴬ mutation. We previously reported that the rapid progression of paralysis in ALS rats is associated with the appearance of prolifer- ative astrocyte-like cells that surround motor neurons. These cells, designated as Aberrant Astrocytes (AbA cells) because of their atypical astrocytic phenotype, exhibit high toxicity to motor neurons. However, the cellular origin of AbA cells remains unknown. Because AbA cells are labeled with the proliferation marker Ki67, we analyzed the phenotypic makers of proliferating glial cells that surround motor neurons by immunohistochemistry. The number of Ki67⁺AbA cells sharply increased in symptomatic rats, displaying large cell bodies with processes embracing motor neurons. Most were co-labeled with astrocytic marker GFAP concurrently with the microglial markers Iba1 and CD163. Cultures of spinal cord prepared from symptomatic SOD1ᴳ⁹³ᴬ rats yielded large numbers of microglia expressing Iba1, CD11b, and CD68. Cells sorted for CD11b expression by flow cytometry transformed into AbA cells within two weeks. During these two weeks, the expression of microglial markers largely disappeared, while GFAP and S100β expression increased. The phenotypic transition to AbA cells was stimulated by forskolin. These findings provide evidence for a subpopulation of proliferating microglial cells in SOD1ᴳ⁹³ᴬ rats that undergo a phenotypic transition into AbA cells after onset of paralysis that may promote the fulminant disease progression. These cells could be a therapeutic target for slowing paralysis progression in ALS

Gelatinasas como marcadores de consumo crônico de álcool: Um estúdio piloto em Urugua

El consumo crónico de alcohol en Uruguay es un problemacreciente, sin embargo, las determinaciones de biomarcadoresconsensuados no se realizan sistemáticamente ni se investiganotros marcadores potenciales. Para validar la hipótesis de quelas metaloproteinasas de matriz con actividad gelatinasa sonbiomarcadores de consumo crónico de alcohol, se evaluaronmuestras de sangre de 100 alcohólicos que comenzaron aatenderse en la Unidad de Trastornos Relacionados con el Alcoholy de 50 donantes sanos no alcohólicos. Las muestras de alcohólicospresentaron actividad de gelatinasas que triplicaron la de loscontroles y aumentos pequeños pero significativos en los niveles degama-glutamil transferasa, aspartato-aminotransferasa y volumencorpuscular medio. Los valores de transferrina deficiente encarbohidratos fueron menores en alcohólicos que en controles. Estosresultados permiten proponer a las gelatinasas como los indicadoresmás sensibles del consumo sostenido de alcohol en la poblaciónanalizada ya que las enzimas hepáticas y el volumen corpuscularmedio muestran una tendencia acorde con la literatura pero noalcanzaron valores asociados a la patología. Dado que la transferrinadeficiente en carbohidratos es considerada el biomarcador indirectomás sensible y específico de consumo crónico de alcohol, los valoresmenores obtenidos en alcohólicos respecto de controles sugierenproblemas metodológicos que podrían subsanarse aplicando otrastécnicas de medida o la presencia de interferencias que deben seridentificadas. Finalmente, estos hallazgos justifican una extensiónde este trabajo piloto, así como estudios adicionales centrados enla participación de las metaloproteinasas de matriz con actividadgelatinasa en las cascadas de daño asociadas al consumo crónicode alcohol.Chronic alcohol consumption in Uruguay is a growing problem, however, determinations of consensual biomarker are not performed systematically neither potential markers are explored. To validate the hypothesis that matrix metalloproteinases with gelatinase activity are biomarkers of chronic alcohol consumption, blood samples of 100 alcoholics that began medical treatment at the Unidad de Trastornos Relacionados con el Alcohol and 50 healthy non-alcoholic donors were evaluated. Alcoholic samples showed gelatinase activity that tripled that of controls and small but significant increases in levels of gamma-glutamyl transferase, aspartate-aminotransferase and mean cellular volume. Carbohydrate deficient transferrin values were lower in alcoholics than in controls. These results allow proposing gelatinases as the most sensitive indicators of sustained alcohol consumption in the population analyzed since hepatic enzymes and mean cellular volume showed a tendency consistent with the literature but did not reach values associated with the pathology. Since carbohydrate-deficient transferrin is considered the most sensitive and specific indirect biomarker of chronic alcohol consumption, lower values in alcoholics related to controls suggest methodological problems that could be solved by applying other measurement techniques or the presence of yet unknown interferences. Finally, these findings justify an extension of this pilot work, as well as additional studies focused on the participation of matrix metalloproteinases with gelatinase activity in the cascades of damage associated with chronic alcohol consumption.O consumo crônico de álcool no Uruguai é um problema crescente, no entanto, as determinações consensuais de biomarcadores não são realizadas sistematicamente ou os potenciais marcadores são explorados. Para validar a hipótese de que as metaloproteinases de matriz com atividade gelatinase são biomarcadores do consumo crônico de álcool, foram avaliadas amostras de sangue cd 100 alcoólatras que começaram a ser tratadas na Unidad de Trastornos Relacionados con el Alcohol e 50 doadores não-alcoólatras saudáveis. As amostras alcoólicas apresentaram atividade de gelatinase que triplicou a dos controles e pequenos más significativos aumentos nos níveis de gama-glutamil transferase, aspartato-aminotransferase e volume médio celular. Os valores de transferrina deficientes em carboidratos foram menores nos alcoolistas que nos controles. Esses resultados permitem que as gelatinases sejam propostas como os indicadores mais sensíveis do consumo sustentado de álcool na população analisada, uma vez que as enzimas hepáticas e o volume celular médio apresentam uma tendência consistente com a literatura, mas não alcançaram valores associados à patologia. Como a transferrina deficiente em carboidratos é considerada o biomarcador indireto mais sensível e específico do consumo crônico de álcool, os valores mais baixos em alcoólatras do que em controles sugerem problemas metodológicos que poderiam ser sanados pela aplicação de outras técnicas de mensuração a presença de interferências que deben identificadas. Finalmente, esses achados justificam uma extensão deste trabalho piloto, bem como estudos adicionais voltados para a participação de metaloproteinases de matriz com atividade de gelatinase nas cascatas de danos associados ao consumo crônico de álcool.Fil: Marco, Marta. Universidad de la República. Facultad de Química; UruguayFil: Boragno, Daniela. Universidad de la República. Facultad de Química; UruguayFil: Rodriguez, Paola. Universidad de la República. Facultad de Química; UruguayFil: Mestre Cordero, Victoria Evangelina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Ciencias Biológicas. Cátedra de Fisiología Humana; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Pereira, Natalia Romina. Universidad de la República. Facultad de Química; UruguayFil: Berasain, Patricia. Universidad de la Republica. Facultad de Medicina. Hospital de Clínicas "dr. Manuel Quintela".; UruguayFil: Cadenas, Florencia. Universidad de la Republica. Facultad de Medicina. Hospital de Clínicas "dr. Manuel Quintela".; UruguayFil: Rodriguez, Cecilia. Universidad de la Republica. Facultad de Medicina. Hospital de Clínicas "dr. Manuel Quintela".; UruguayFil: Moreira, Alejandra. Universidad de la Republica. Facultad de Medicina. Hospital de Clínicas "dr. Manuel Quintela".; UruguayFil: Simoff, Ximena. Universidad de la Republica. Facultad de Medicina. Hospital de Clínicas "dr. Manuel Quintela".; UruguayFil: Bianchi, Virginia. Universidad de la Republica. Facultad de Medicina. Hospital de Clínicas "dr. Manuel Quintela".; UruguayFil: Barindelli, Anna. Universidad de la Republica. Facultad de Medicina. Hospital de Clínicas "dr. Manuel Quintela".; UruguayFil: Fielitz, Pablo. Universidad de la Republica. Facultad de Medicina. Hospital de Clínicas "dr. Manuel Quintela".; UruguayFil: Olivera Bravo, Silvia. Universidad de la República. Facultad de Química; Urugua

Neuroprotective effects of violacein in a model of inherited amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive death of motor neurons and muscle atrophy, with defective neuron-glia interplay and emergence of aberrant glial phenotypes having a role in disease pathology. Here, we have studied if the pigment violacein with several reported protective/antiproliferative properties may control highly neurotoxic astrocytes (AbAs) obtained from spinal cord cultures of symptomatic hSOD1G93A rats, and if it could be neuroprotective in this ALS experimental model. At concentrations lower than those reported as protective, violacein selectively killed aberrant astrocytes. Treatment of hSOD1G93A rats with doses equivalent to the concentrations that killed AbAs caused a marginally significant delay in survival, partially preserved the body weight and soleus muscle mass and improved the integrity of the neuromuscular junction. Reduced motor neuron death and glial reactivity was also found and likely related to decreased inflammation and matrix metalloproteinase-2 and -9. Thus, in spite that new experimental designs aimed at extending the lifespan of hSOD1G93A rats are needed, improvements observed upon violacein treatment suggest a significant therapeutic potential that deserves further studies.IIBCE (MEC), PEDECIBA y ANII

Neonatal Astrocyte Damage Is Sufficient to Trigger Progressive Striatal Degeneration in a Rat Model of Glutaric Acidemia-I

BACKGROUND: We have investigated whether an acute metabolic damage to astrocytes during the neonatal period may critically disrupt subsequent brain development, leading to neurodevelopmental disorders. Astrocytes are vulnerable to glutaric acid (GA), a dicarboxylic acid that accumulates in millimolar concentrations in Glutaric Acidemia I (GA-I), an inherited neurometabolic childhood disease characterized by degeneration of striatal neurons. While GA induces astrocyte mitochondrial dysfunction, oxidative stress and subsequent increased proliferation, it is presently unknown whether such astrocytic dysfunction is sufficient to trigger striatal neuronal loss. METHODOLOGY/PRINCIPAL FINDINGS: A single intracerebroventricular dose of GA was administered to rat pups at postnatal day 0 (P0) to induce an acute, transient rise of GA levels in the central nervous system (CNS). GA administration potently elicited proliferation of astrocytes expressing S100β followed by GFAP astrocytosis and nitrotyrosine staining lasting until P45. Remarkably, GA did not induce acute neuronal loss assessed by FluoroJade C and NeuN cell count. Instead, neuronal death appeared several days after GA treatment and progressively increased until P45, suggesting a delayed onset of striatal degeneration. The axonal bundles perforating the striatum were disorganized following GA administration. In cell cultures, GA did not affect survival of either striatal astrocytes or neurons, even at high concentrations. However, astrocytes activated by a short exposure to GA caused neuronal death through the production of soluble factors. Iron porphyrin antioxidants prevented GA-induced astrocyte proliferation and striatal degeneration in vivo, as well as astrocyte-mediated neuronal loss in vitro. CONCLUSIONS/SIGNIFICANCE: Taken together, these results indicate that a transient metabolic insult with GA induces long lasting phenotypic changes in astrocytes that cause them to promote striatal neuronal death. Pharmacological protection of astrocytes with antioxidants during encephalopatic crisis may prevent astrocyte dysfunction and the ineluctable progression of disease in children with GA-I

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

A Focus on Astrocyte Contribution to Parkinson’s Disease Etiology

Parkinson’s disease (PD) is an incurable neurodegenerative disease of high prevalence, characterized by the prominent death of dopaminergic neurons in the substantia nigra pars compacta, which produces dopamine deficiency, leading to classic motor symptoms. Although PD has traditionally been considered as a neuronal cell autonomous pathology, in which the damage of vulnerable neurons is responsible for the disease, growing evidence strongly suggests that astrocytes might have an active role in the neurodegeneration observed. In the present review, we discuss several studies evidencing astrocyte implications in PD, highlighting the consequences of both the loss of normal homeostatic functions and the gain in toxic functions for the wellbeing of dopaminergic neurons. The revised information provides significant evidence that allows astrocytes to be positioned as crucial players in PD etiology, a factor that needs to be taken into account when considering therapeutic targets for the treatment of the disease

Astrocyte Dysfunction in Developmental Neurometabolic Diseases.

International audienceAstrocytes play crucial roles in maintaining brain homeostasis and in orchestrating neural development, all through tightly coordinated steps that cooperate to maintain the balance needed for normal development. Here, we review the alterations in astrocyte functions that contribute to a variety of developmental neurometabolic disorders and provide additional data on the predominant role of astrocyte dysfunction in the neurometabolic neurodegenerative disease glutaric acidemia type I. Finally, we describe some of the therapeutical approaches directed to neurometabolic diseases and discuss if astrocytes can be possible therapeutic targets for treating these disorders