Browsing by Author "Alvarez, Alejandra"

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    Asymptomatic herpes simplex virus brain infection elicits cellular senescence phenotypes in the central nervous system of mice suffering multiple sclerosis-like disease
    (2024) Duarte, Luisa; Villalobos, Verónica; Farías, Mónica; Rangel, Maria; González, Enrique; Navarro, Areli; Carbone, Javier; Domínguez, Angélica; Alvarez, Alejandra; Riedel, Claudia; Bueno, Susan; Kalergis, Alexis; Cáceres, Mónica; González, Pablo
    Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease affecting the central nervous system (CNS) in animals that parallels several clinical and molecular traits of multiple sclerosis in humans. Herpes simplex virus type 1 (HSV-1) infection mainly causes cold sores and eye diseases, yet eventually, it can also reach the CNS, leading to acute encephalitis. Notably, a significant proportion of healthy individuals are likely to have asymptomatic HSV-1 brain infection with chronic brain inflammation due to persistent latent infection in neurons. Because cellular senescence is suggested as a potential factor contributing to the development of various neurodegenerative disorders, including multiple sclerosis, and viral infections may induce a premature senescence state in the CNS, potentially increasing susceptibility to such disorders, here we examine the presence of senescence-related markers in the brains and spinal cords of mice with asymptomatic HSV-1 brain infection, EAE, and both conditions. Across all scenarios, we find a significant increases of senescence biomarkers in the CNS with some differences depending on the analyzed group. Notably, some senescence biomarkers are exclusively observed in mice with the combined conditions. These results indicate that asymptomatic HSV-1 brain infection and EAE associate with a significant expression of senescence biomarkers in the CNS.
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    Bacteriemia en daño hepático crónico
    (2011) Munita, José; Araos, Rafael; Pérez, Jorge; Alvarez, Alejandra; Canals, Magdalena; Contreras, Jorge; Marcotti, Alejandra; Thompson, Luis; Noriega, Luis
    Bacteremic infections are more frequent in patients with cirrhosis, as their immune system is compromised. Series of cirrhotic patients with bacteremia has seldom been reported in Chile. We retrospectively collected, from 2005 to 2008, 59 episodes of bacteremia in cirrhotics representing 9% of the overall number of bacteremic episodes seen in our center in the period. Spontaneous bacteremia accounted for 29% followed by those of pulmonary origin (22%). Grampositive cocci and gramnegative bacilli were responsible in 52% and 48% respectively, however gramnegative rods predominated in nosocomial bacteremias. Overall, the most frequent organisms were Staphylococcus aureus (24%) and Escherichia coli (22%). Mortality in bacteremic patients was significantly higher compared with all cirrhotic patients hospitalized in the period (37.0 vs 9.4%; p < 0.001) and MELD score was significantly correlated with mortality. Conclusion: bacteremia is a severe complication of cirrhosis and MELD score could be a useful tool to stratify risk in these patients.
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    c-Abl Inhibition Activates TFEB and Promotes Cellular Clearance in a Lysosomal Disorder
    (Cell Press, 2020) Contreras, Pablo; Tapia, Pablo; González-Hodar, Lila; Peluso, Ivana; Soldati, Chiara; Napoiotano, Gennaro; Matarese, María; Las Heras, Macarena; Valls, Cristian; Martínez, Alexis; Balboa, Elisa; Castro, Juan; Nancy, Leal; Platt, Frances; Sobota, Andrzej; Winter, Dominic; Klein, Andrés; Medina, Diego; Ballabio, Andrea; Alvarez, Alejandra; Zanlungo, Silvana
    The transcription factor EB (TFEB) has emerged as a master regulator of lysosomal biogenesis, exocytosis, and autophagy, promoting the clearance of substrates stored in cells. c-Abl is a tyrosine kinase that participates in cellular signaling in physiological and pathophysiological conditions. In this study, we explored the connection between c-Abl and TFEB. Here, we show that under pharmacological and genetic c-Abl inhibition, TFEB translocates into the nucleus promoting the expression of its target genes independently of its well-known regulator, mammalian target of rapamycin complex 1. Active c-Abl induces TFEB phosphorylation on tyrosine and the inhibition of this kinase promotes lysosomal biogenesis, autophagy, and exocytosis. c-Abl inhibition in Niemann-Pick type C (NPC) models, a neurodegenerative disease characterized by cholesterol accumulation in lysosomes, promotes a cholesterol-lowering effect in a TFEB-dependent manner. Thus, c-Abl is a TFEB regulator that mediates its tyrosine phosphorylation, and the inhibition of c-Abl activates TFEB promoting cholesterol clearance in NPC models.

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