Apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC) is a component of inflammasome, which plays crucial roles in the inflammatory response. In mammals, ASC regulates caspase-1 activation, thereby inducing pyroptosis and producing activated inflammatory cytokines. In addition, ASC also interacts with receptor-interacting protein kinase 2 (RIPK2) and induces nuclear factor-κB (NF-κB) activation. However, the role of ASC remains poorly understood in fish. In this study, we focused on elucidating the role of ASC in fish that were infected with Aeromonas hydrophila using Japanese medaka (Oryzias latipes) as fish model, and ASC-knockout (KO) medaka was established using CRISPR-Cas9 system. ASC-KO and wild type (WT) medakas were infected with A. hydrophila, and mortality was observed. ASC-KO medaka demonstrated higher mortality than WT. Moreover, the expression of immune-related genes in the kidney and intestine of the ASC-KO and WT medakas challenged with A. hydrophila were analyzed. Following A. hydrophila infection, the kidney of ASC-KO medaka exhibited significantly lower expression of NF-κB regulated genes (e.g., IL-1β, IL-6, IL-8 and TNF-α) and RIPK2 gene than in WT kidney. Moreover, to investigate the immune response against A. hydrophila via ASC in the medaka, bacterial burden, superoxide anion production, and lactate dehydrogenase release in the kidney cells of ASC-KO medaka were measured. After infection, these responses in ASC-KO medaka were significantly decreased compared to those in WT. These results suggest that the medaka ASC plays a critical role against A. hydrophila infection by inducing inflammatory responses and cell death for bacterial clearance.

凋亡相关斑点样蛋白，含有半胱天冬酶募集结构域（ASC），是炎性小体的一个组成部分，在炎症反应中起关键作用。在哺乳动物中，ASC调节caspase-1活化，从而诱导焦磷酸化并产生活化的炎性细胞因子。此外，ASC还与受体相互作用蛋白激酶2（RIPK2）相互作用并诱导核因子-κB（NF-κB）激活。但是，ASC在鱼类中的作用仍然知之甚少。在这项研究中，我们专注于阐明ASC在以日本（Oryzias latipes）为鱼类模型感染了嗜水气单胞菌的鱼中的作用，并使用CRISPR-Cas9系统建立了ASC敲除（KO）medaka。ASC-KO和野生型（med）感染了嗜水链球菌，并观察到死亡率。ASC-KO medaka的死亡率高于WT。此外，A攻击了ASC-KO和WT medakas肾脏和肠中免疫相关基因的表达。对亲水性进行了分析。继一。嗜水气感染，ASC-KO鳉的肾脏显示出NF-κB调节的基因显著更低的表达（例如，IL-1β，IL-6 ，IL-8和TNF-α）和RIPK2基因比在WT肾。此外，研究针对A的免疫应答。通过亲水测定了高aka中的ASC，细菌负担，超氧阴离子的产生以及ASC-KO medaka肾脏细胞中乳酸脱氢酶的释放。感染后，与野生型相比，ASC-KO medaka中的这些响应显着降低。这些结果表明，medaka ASC对A起关键作用。通过诱导炎症反应和细胞死亡清除细菌而导致亲水性感染。