Avaliação das etapas de ativação dos inflamassomas em astrócitos em resposta ao Zika vírus
Arquivos
Data
2023-12-12
Autores
Lucena, Victoria Weise Leite de 
Orientadores
Bortoluci, Karina Ramalho
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Os inflamassomas são complexos citosólicos multiproteicos ativados em resposta a infecções ou danos celulares. A ativação dessas plataformas leva ao recrutamento e autoclivagem da protease efetora caspase-1 e consequente liberação de IL-1β e IL-18, além da indução de uma forma específica de morte celular, a piroptose. Esses complexos são encontrados em diversas células imunes como os macrófagos, neutrófilos e células dendríticas, mas sua presença já foi caracterizada em outras células, como em células epiteliais e no Sistema Nervoso Central (SNC). No SNC, os inflamassomas participam do controle de infecções, mas também estão relacionados a patologias como Doenças neurodegenerativas e Transtornos neuropsiquiátricos. A maior parte dos estudos de inflamassomas no SNC é limitada às micróglias, visto que estas células compõem o principal eixo imune desse compartimento. Os astrócitos se encontram em grande quantidade no SNC, possuindo funções essenciais para o funcionamento dos circuitos neurais e metabolismo do SNC. Por mais que a expressão de inflamassomas e de seus componentes já tenha sido documentada em astrócitos, não se sabe com clareza as etapas e mecanismos que levam a sua ativação, especialmente no contexto infeccioso. Por isso, o presente trabalho buscou avaliar a participação dos inflamassomas de astrócitos primários murinos durante a infecção por Zika vírus (ZIKV), através da análise de expressão, montagem e funcionalidade dos inflamassomas. Para isso, as células foram divididas em grupos tratados ou não tratados com LPS e infectadas com ZIKV em multiplicidade de infecção (MOI) 1 por 2 horas, 24 horas, 48 horas ou 72 horas. Através de imagens de imunofluorescência, não foi observada a formação de punctas de ASC em nenhum dos tempos de infecção analisados. Astrócitos infectados por ZIKV não apresentaram secreção de IL-1β. Através da dosagem de lactato, foi observado um aumento de sua concentração no decorrer do tempo, mas não foram encontradas diferenças no metabolismo glicolítico entre astrócitos infectados e não infectados. Não houve diferenças significativas entre os grupos tratados e não tratados com LPS em nenhum dos testes realizados. Os dados obtidos sugerem que o ZIKV não é capaz de induzir a ativação dos inflamassomas em astrócitos, indicando um mecanismo não dependente da resposta clássica dos inflamassomas no controle dessa infecção.
Inflammasomes are cytosolic multiprotein complexes expressed in response to the perception of a threat by the innate immune system. Their functioning leads to the activation, production, and release of several essential molecules for the immune response, such as caspase-1, IL-1β, and IL-18. Besides, they also act as important inducers of a specific form of cell death, pyroptosis. These complexes are found in a variety of cells, such as macrophages, neutrophils, and dendritic cells, but their presence has been characterized in cells outside the immune system, such as in epithelial and neural cells. In the Central Nervous System (CNS), inflammasomes are expressed mainly in the microglia, but have also been observed in astrocytes and even in neurons. Most studies of inflammasomes in the CSN are limited to microglia, since those cells are the main immune axis of this system and have better characterized inflammasome activation pathways. The NLRP3 inflammasome, a major inflammasome expressed in those cells, is known to be related to several diseases affecting the CNS, such as Alzheimer’s, Parkinson’s, and traumatic brain injury. Astrocytes are found in large numbers in the CNS and have functions that are essential for the performance of neural circuits. Although the expression of inflammasomes and their components has been documented in these cells, the steps and mechanisms that lead to their activation, especially in response to infections, are not yet clearly known. For this reason, this study sought to evaluate the participation of inflammasomes in murine primary astrocytes during Zika virus (ZIKV) infection, by analyzing the expression, assembly, and functionality of inflammasomes. To do this, the cells were divided into groups treated or not treated with LPS and infected with ZIKV at multiplicity of infection (MOI) 1 for 2 hours, 24 hours, 48 hours, or 72 hours. Immunofluorescence images showed no ASC specks formation at any of the infection times analyzed. ZIKV-infected astrocytes did not secrete IL-1β. By measuring lactate, an increase in its concentration was observed over time, but no differences were found in glycolytic metabolism between infected and uninfected astrocytes. There were no significant differences between the groups treated and not treated with LPS in any of the tests conducted. Results suggest that ZIKV is not capable of inducing inflammasome activation in astrocytes, indicating a mechanism that is not dependent on the classic inflammasome response to control this infection.
Inflammasomes are cytosolic multiprotein complexes expressed in response to the perception of a threat by the innate immune system. Their functioning leads to the activation, production, and release of several essential molecules for the immune response, such as caspase-1, IL-1β, and IL-18. Besides, they also act as important inducers of a specific form of cell death, pyroptosis. These complexes are found in a variety of cells, such as macrophages, neutrophils, and dendritic cells, but their presence has been characterized in cells outside the immune system, such as in epithelial and neural cells. In the Central Nervous System (CNS), inflammasomes are expressed mainly in the microglia, but have also been observed in astrocytes and even in neurons. Most studies of inflammasomes in the CSN are limited to microglia, since those cells are the main immune axis of this system and have better characterized inflammasome activation pathways. The NLRP3 inflammasome, a major inflammasome expressed in those cells, is known to be related to several diseases affecting the CNS, such as Alzheimer’s, Parkinson’s, and traumatic brain injury. Astrocytes are found in large numbers in the CNS and have functions that are essential for the performance of neural circuits. Although the expression of inflammasomes and their components has been documented in these cells, the steps and mechanisms that lead to their activation, especially in response to infections, are not yet clearly known. For this reason, this study sought to evaluate the participation of inflammasomes in murine primary astrocytes during Zika virus (ZIKV) infection, by analyzing the expression, assembly, and functionality of inflammasomes. To do this, the cells were divided into groups treated or not treated with LPS and infected with ZIKV at multiplicity of infection (MOI) 1 for 2 hours, 24 hours, 48 hours, or 72 hours. Immunofluorescence images showed no ASC specks formation at any of the infection times analyzed. ZIKV-infected astrocytes did not secrete IL-1β. By measuring lactate, an increase in its concentration was observed over time, but no differences were found in glycolytic metabolism between infected and uninfected astrocytes. There were no significant differences between the groups treated and not treated with LPS in any of the tests conducted. Results suggest that ZIKV is not capable of inducing inflammasome activation in astrocytes, indicating a mechanism that is not dependent on the classic inflammasome response to control this infection.