Estudo sobre o papel dos processos infecciosos na hepatotoxicidade induzida por células iNKT
Data
2023-12-11
Autores
Labate, Juliana da Luz 
Orientadores
Keller, Alexandre de Castro
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O fígado está exposto, diariamente, a potenciais estímulos lesivos derivados de
microrganismo provenientes do intestino ou que alcançam a circulação pela
veia porta. Assim, o sistema imunológico precisa manter um equilíbrio entre
tolerância e ativação a fim de controlar o dano hepático. Nesse contexto, as
células T invariantes natural killer (iNKT) exercem um papel importante na
fisiopatologia do tecido hepático, podendo contribuir tanto para a homeostasia
quanto para o dano. Nesse sentido, já foi demonstrado que a expressão de
CD1d, molécula responsável pela apresentação de antígenos lipídicos às
iNKTs, é de extrema importância para o controle e ativação dessas células. Em
vista disso, nosso objetivo foi avaliar se estímulos que mimetizam infecções
bacterianas (LPS) e virais (Imiquimod) induzem modificações moleculares em
hepatócitos e, se estas, influenciam a relação entre as iNKT e as células
hepáticas. Para isso, hepatócitos murinos da linhagem AML12 foram
estimulados com LPS e Imiquimod por 16 horas. A análise da expressão de
CD1d, Fas e moléculas coestimuladoras (CD80 e CD86) por citometria de fluxo
demonstrou que o LPS é capaz de promover redução na expressão de CD1d e
de CD86, e o aumento de Fas na superfície das células AML12, enquanto o
Imiquimod aumenta a expressão de CD1d e reduz a de Fas. A quantificação da
enzima lactato desidrogenase (LDH) na cocultura entre AML12 e iNKT,
demonstrou a indução de citotoxicidade apenas após o estímulo com
Imiquimod. Ademais, nenhuma das mudanças induzidas pelo LPS ou pelo
Imiquimod em células AML12 foram capazes de alterar a apresentação de
antígenos cognatos para a iNKT. Portanto, nossos dados sugerem que o
aumento da expressão de CD1d e a redução de Fas, resultante do estímulo
com Imiquimod, interferem de maneira expressiva na relação entre as iNKTs e
os hepatócitos.
The liver is exposed, daily, to potential harmful stimuli derived from microorganisms originating from de gut or reaching circulation through the portal vein. Thus, the immune system needs to maintain a balance between tolerance and activation to control liver damage. In this context, invariant natural killer T (iNKT) cells play an important role in the physiopathology of liver tissue, potentially contributing to both homeostasis and damage. In this regard, it has already been demonstrated that the expression of CD1d, the molecule responsible for presenting lipid antigens to iNKTs, is extremely important for the control and activation of these cells. In view of this, our objective was to evaluate whether stimuli that mimic bacterial (LPS) and viral (Imiquimod) infections induce molecular changes in hepatocytes and whether these influences the relationship between iNKT and liver cells. For this, murine hepatocytes of the AML12 lineage were stimulated with LPS and Imiquimod for 16 horas. Analysis of the expression of CD1d, Fas and costimulatory molecules (CD80 and CD86) by flow cytometry demonstrated that LPS can promote a reduction in the expression of CD1d and CD86, and an increase in Fas on the surface of AML12 cells, while Imiquimod increases the expression of CD1d and reduces the expression of Fas. Quantification of the enzyme lactate dehydrogenase (LDH) in the coculture of AML12 and iNKT demonstrated the induction of cytotoxicity only after stimulation with Imiquimod. Furthermore, none of the changes induced by LPS or Imiquimod in AML12 cells were able to alter the presentation of cognate antigens to iNKT. Therefore, our data suggest that the increased expression of CD1d and the reduction of Fas, resulting from stimulation with Imiquimod, significantly change the relationship between iNKTs and hepatocytes.
The liver is exposed, daily, to potential harmful stimuli derived from microorganisms originating from de gut or reaching circulation through the portal vein. Thus, the immune system needs to maintain a balance between tolerance and activation to control liver damage. In this context, invariant natural killer T (iNKT) cells play an important role in the physiopathology of liver tissue, potentially contributing to both homeostasis and damage. In this regard, it has already been demonstrated that the expression of CD1d, the molecule responsible for presenting lipid antigens to iNKTs, is extremely important for the control and activation of these cells. In view of this, our objective was to evaluate whether stimuli that mimic bacterial (LPS) and viral (Imiquimod) infections induce molecular changes in hepatocytes and whether these influences the relationship between iNKT and liver cells. For this, murine hepatocytes of the AML12 lineage were stimulated with LPS and Imiquimod for 16 horas. Analysis of the expression of CD1d, Fas and costimulatory molecules (CD80 and CD86) by flow cytometry demonstrated that LPS can promote a reduction in the expression of CD1d and CD86, and an increase in Fas on the surface of AML12 cells, while Imiquimod increases the expression of CD1d and reduces the expression of Fas. Quantification of the enzyme lactate dehydrogenase (LDH) in the coculture of AML12 and iNKT demonstrated the induction of cytotoxicity only after stimulation with Imiquimod. Furthermore, none of the changes induced by LPS or Imiquimod in AML12 cells were able to alter the presentation of cognate antigens to iNKT. Therefore, our data suggest that the increased expression of CD1d and the reduction of Fas, resulting from stimulation with Imiquimod, significantly change the relationship between iNKTs and hepatocytes.