Papel do inflamassoma NLRP3 em modelo de infecção sistêmica por Sporothrix schenckii
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Data
2016-12-09
Autores
Gonçalves, Amanda Costa [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A esporotricose é uma infecção fúngica causada pelas espécies do complexo Sporothrix, incluindo Sporothrix schenckii sensu stricto. Os receptores de reconhecimento padrão (PRRs), pertencentes às células da resposta imune inata, reconhecem os padrões moleculares associados a patógenos (PAMPs). Uma classe de PRRs que tem sido associada ao reconhecimento de fungos é a dos receptores Nod-like (NLR). Após o reconhecimento de PAMPs, os receptores NLR family pyrin domain–containing 3 (NLRP3), em conjunto com a molécula adaptadora Apoptosis-associated speck–like protein containing a caspase recruitment domain (ASC) e com a caspase-1, formam o inflamassoma NLRP3. Quando ativado, este complexo protéico promove a maturação das citocinas pró-inflamatórias IL-1β e IL-18, que influenciam no desenvolvimento das respostas imune Th17 e Th1, respectivamente. O inflamassoma NLRP3 também é responsável pela piroptose, uma morte celular inflamatória regulada por caspase-1. Neste contexto, o objetivo deste estudo foi avaliar o papel do inflamassoma NLRP3 em modelo de infecção sistêmica por S. schenckii, utilizando um camundongo selvagem (WT) e três diferentes camundongos knockout (KO): NLRP3-/-, ASC-/- e Casp-1-/-. Todos os animais KO foram mais suscetíveis que os WT na infecção por S. schenckii. A ativação do inflamassoma NLRP3 foi essencial para a liberação ex vivo de NO, IL-1β, IL-17, IL-18, mas não para IFN-γ. Além disso, S. schenckii desencadeou maior expressão de caspase-1 ativa e maior porcentagem de células em piroptose nos animais WT. Em adição, o inflamassoma NLRP3 também foi crucial para a formação de respostas imunes adaptativas, visto que as frequências de células Th17 e Th1/Th17 estavam reduzidas nos animais KO infectados. Por outro lado, a ausência de ativação deste complexo proteico resultou em aumento da frequência de células T citotóxicas nesta infecção. Em conclusão, nossos resultados mostraram que o inflamassoma NLRP3 correlaciona o desencadeamento das respostas imunes inata e adaptativa no reconhecimento de S. schenckii, contribuindo com a resposta protetora do hospedeiro durante a infecção por este fungo.
Sporotrichosis is a mycosis caused by fungi from the Sporothrix schenckii species complex, whose prototypical member is Sporothrix schenckii sensu stricto. Pattern recognition receptors (PRRs) recognize and respond to pathogen-associated molecular patterns (PAMPs) and shape the following adaptive immune response. A family of PRRs most frequently associated to fungal recognition is the nucleotide-binding oligomerization domain–like receptor (NLR). After recognition of a PAMP, NLR family pyrin domain–containing 3 (NLRP3) binds to apoptosis-associated speck–like protein containing a caspase recruitment domain (ASC) and caspase-1 to form the NLRP3 inflammasome. When activated, this complex promotes maturation of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 that influence the development of the Th17 and Th1 immune responses, respectively. In addition, the NLRP3 inflammassome is responsible for pyroptosis, a highly inflammatory cell death regulated by caspase-1. In this work, we aimed to evaluate the role of the NLRP3 inflammasome to the outcome of the S. schenckii infection using a wild-type mice (WT) and three different knockout mice (KO): NLRP3-/-, ASC-/-, and Casp-1-/-. All the KO mice were more susceptible to the infection than the WT during the S. schenckii infection. Furthermore, the NLRP3 inflammasome seems to be critical to the ex vivo release of NO, IL-1β, IL-18, and IL-17, but not IFN-γ. The S. schenckii infection led to increased activation of caspase-1 and cell death by pyroptosis in WT mice. Also, a role for the inflammasome in shaping the adaptive immune response was suggested by lower frequencies of type 17 helper T (Th17) and Th1/Th17 cells in S. schenckii-infected KO mice. On the other hand, absence of any of the inflammasome components resulted in increased frequency of cytotoxic T cells in this infection. As a whole, our results indicate the NLRP3 inflammasome links the innate recognition of S. schenckii to the adaptive immune response, thus contributing to protective response in the infection by this fungus.
Sporotrichosis is a mycosis caused by fungi from the Sporothrix schenckii species complex, whose prototypical member is Sporothrix schenckii sensu stricto. Pattern recognition receptors (PRRs) recognize and respond to pathogen-associated molecular patterns (PAMPs) and shape the following adaptive immune response. A family of PRRs most frequently associated to fungal recognition is the nucleotide-binding oligomerization domain–like receptor (NLR). After recognition of a PAMP, NLR family pyrin domain–containing 3 (NLRP3) binds to apoptosis-associated speck–like protein containing a caspase recruitment domain (ASC) and caspase-1 to form the NLRP3 inflammasome. When activated, this complex promotes maturation of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 that influence the development of the Th17 and Th1 immune responses, respectively. In addition, the NLRP3 inflammassome is responsible for pyroptosis, a highly inflammatory cell death regulated by caspase-1. In this work, we aimed to evaluate the role of the NLRP3 inflammasome to the outcome of the S. schenckii infection using a wild-type mice (WT) and three different knockout mice (KO): NLRP3-/-, ASC-/-, and Casp-1-/-. All the KO mice were more susceptible to the infection than the WT during the S. schenckii infection. Furthermore, the NLRP3 inflammasome seems to be critical to the ex vivo release of NO, IL-1β, IL-18, and IL-17, but not IFN-γ. The S. schenckii infection led to increased activation of caspase-1 and cell death by pyroptosis in WT mice. Also, a role for the inflammasome in shaping the adaptive immune response was suggested by lower frequencies of type 17 helper T (Th17) and Th1/Th17 cells in S. schenckii-infected KO mice. On the other hand, absence of any of the inflammasome components resulted in increased frequency of cytotoxic T cells in this infection. As a whole, our results indicate the NLRP3 inflammasome links the innate recognition of S. schenckii to the adaptive immune response, thus contributing to protective response in the infection by this fungus.
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Palavras-chave
Inflamassoma NLRP3, Citocinas, Piroptose, Sporothrix schenckii, NLRP3 inflammasome, Cytokines, Pyroptosis, Sporothrix schenckii