DataSheet_1_NLRP3 Inflammasome Contributes to Host Defense Against Talaromyces marneffei Infection.docx

Talaromyce marneffei is an important thermally dimorphic pathogen causing disseminated mycoses in immunocompromised individuals in southeast Asia. Previous studies have suggested that NLRP3 inflammasome plays a critical role in antifungal immunity. However, the mechanism underlying the role of NLRP3 inflammasome activation in host defense against T. marneffei remains unclear. We show that T. marneffei yeasts but not conidia induce potent IL-1β production. The IL-1β response to T. marneffei yeasts is differently regulated in different cell types; T. marneffei yeasts alone are able to induce IL-1β production in human PBMCs and monocytes, whereas LPS priming is essential for IL-1β response to yeasts. We also find that Dectin-1/Syk signaling pathway mediates pro-IL-1β production, and NLRP3-ASC-caspase-1 inflammasome is assembled to trigger the processing of pro-IL-1β into IL-1β. In vivo, mice deficient in NLRP3 or caspase-1 exhibit higher mortality rate and fungal load compared to wild-type mice after systemic T. marneffei infection, which correlates with the diminished recruitment of CD4 T cells into granulomas in knockout mice. Thus, our study first demonstrates that NLRP3 inflammasome contributes to host defense against T. marneffei infection.

Talaromyce marneffei作为一种热变型病原体，在东南亚地区免疫受损人群中引起播散性真菌感染，具有重要性。既往研究表明，NLRP3炎症小体在抗真菌免疫过程中发挥着关键作用。然而，NLRP3炎症小体在宿主防御T. marneffei过程中的作用机制尚不明确。本研究发现，T. marneffei酵母而非分生孢子能够诱导产生强大的IL-1β。对T. marneffei酵母的IL-1β反应在不同细胞类型中受到不同的调控；T. marneffei酵母单独即可诱导人PBMCs和单核细胞产生IL-1β，而LPS的预处理对于酵母引起的IL-1β反应则是必不可少的。此外，我们发现Dectin-1/Syk信号通路介导了前IL-1β的产生，NLRP3-ASC-caspase-1炎症小体组装以触发前IL-1β向IL-1β的加工。在体内实验中，与野生型小鼠相比，NLRP3或caspase-1基因敲除小鼠在系统性T. marneffei感染后表现出更高的死亡率及真菌负荷，这与敲除小鼠中巨噬细胞中CD4 T细胞的减少招募相关。因此，本研究首次证实了NLRP3炎症小体在宿主防御T. marneffei感染中的作用。