Dipeptidyl peptidase 9 sets a threshold for CARD8 inflammasome formation by sequestering its active C-terminal fragment

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慢溃宁方对DSS诱导溃疡性结肠炎小鼠NLRP3/Caspase-1/GSDMD细胞焦亡通路和肠道菌群的影响

目的 探讨慢溃宁方对葡聚糖硫酸钠（DSS）诱导的溃疡性结肠炎（UC）小鼠肠道菌群的调控作用,和对NOD样受体（NLR）P3/胱天蛋白酶（Caspase）-1/Gasdermin D（GSDMD）细胞焦亡通路所介导炎症的影响。方法 SPF级C57BL/6小鼠60只,随机分为空白组、模型组、慢溃宁方组（20 g·kg^-1）、美沙拉秦组（0.266 g·kg^-1）,各组15只。小鼠通过自由饮用3%DSS溶液,7 d构建UC模型。造模开始12 h后,治疗组每天灌胃给药,其余组灌胃等体积生理盐水。记录小鼠每日体质量等情况,并评估计算疾病活动指数（DAI）。第8天麻醉后,脱臼颈椎处死小鼠,收集结肠和粪便,记量结肠长度;观察结肠组织苏木素-伊红（HE）染色后的病理学改变;结肠中肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）、白细胞介素-18（IL-18）水平用酶联免疫吸附测定法（ELISA）检测;基于16S rRNA测序技术检测各组小鼠粪便中肠道菌群的差异;NLRP3/Caspase-1/GSDMD蛋白结肠组织中含量用蛋白免疫印迹法（Western blot）检测。结果 相较于空白组,模型组小鼠的DAI升高（P<0.01）,结肠长度显著缩短（P<0.01）,结肠黏膜损伤严重,TNFα、IL-1β、IL-18水平均明显升高（P<0.01）,且结肠组织中NLRP3/Caspase-1/GSDMD蛋白含量显著升高（P<0.01）,肠道菌群结构改变,门水平上的放线菌门、拟杆菌门与变形菌门丰度减少,厚壁菌门丰度增加;属水平上的乳酸杆菌、普雷沃氏菌和鼠杆菌属丰度减少,拟杆菌属、芽孢杆菌、毛螺旋菌属NK4A136丰度增加。慢溃宁方组、美沙拉秦组相较于模型组,第3天后DAI显著降低（P<0.01）,结肠长度均显著增加（P<0.01）,结肠的炎症浸润及黏膜结构损伤减轻,且结肠TNF-α、IL-1β、IL-18水平均显著下降（P<0.01）,NLRP3/Caspase-1/GSDMD蛋白在结肠组织中的含量明显降低（P<0.05,P<0.01）,门水平上的变形菌门和拟杆菌门丰度增加,厚壁菌门丰度减少。结论 慢溃宁方可通过抑制细胞经典焦亡通路,缓解UC小鼠结肠炎症反应,减轻结肠损伤,并对肠道菌群紊乱有改善作用。     

The role of IL-1β during human immunodeficiency virus type 1 infection

Interleukin (IL)-1β is a key innate cytokine that is essential for immune activation and promoting the inflammatory process. However, abnormal elevation in IL-1β levels has been associated with unwanted clinical outcomes. IL-1β is the most extensively studied cytokine among the IL-1 family of cytokines and its role in pathology is well established. During the course of human immunodeficiency virus type 1 (HIV-1) infection, the level of this proinflammatory cytokine is increased in different anatomical compartments, particularly in lymphatic tissues, and this elevation is associated with disease progression. The aim of this review is to address the pathological roles play by IL-1β in the light of enhancing HIV-1 replication, driving immune cell depletion, and chronic immune activation. The role of IL-1β in HIV-1 transmission (sexually or vertically ‘from mother-to-child’) will also be discussed. Additionally, the impact of the available antiretroviral therapy regimens on the levels of IL-1β in HIV-1 treated patients is also discussed. Finally, we will provide a glance on how IL-1β could be targeted as a therapeutic strategy.     

甜橙黄酮体外抑制氧化应激减轻肾小球微血管内皮细胞焦亡的机制研究

目的 糖尿病肾脏疾病(diabetic kidney disease,DKD)的发病率逐年升高,氧化应激诱发的肾小球微血管内皮损伤与其发生发展具有重大关联,但其潜在机制尚不完全清楚,且治疗策略有限。甜橙黄酮是一种广泛用于治疗心血管疾病的多甲氧基化黄酮类化合物,有研究显示其抗氧化的作用较为显著。然而,甜橙黄酮是否抑制肾小球微血管内皮细胞的氧化应激来延缓DKD的进展尚不清楚。因此,本研究旨在从一个全新的角度探讨DKD发生发展的机制,并证实甜橙黄酮的作用和机理,为DKD的治疗提供新思路。方法 采用Px-12孵育人肾小球微血管内皮细胞(human renal glomerular microvascular endothelial cells, HRGEC)在体外建立细胞氧化损伤模型。根据光镜观察细胞形态、细胞活性检测试剂盒-8明确细胞活性、并使用(reactive oxygen species ,SROS)/O_^2?荧光探针测定各组HRGEC细胞氧化应激水平的差异。通过透射电镜观察各组细胞膜形态的变化以及western blot检测膜穿孔蛋白(gasdermin D,GSDMD)蛋白表达的变化来明确细胞焦亡的情况。最后通过增加氧化应激抑制剂和细胞外调节蛋白激酶(extracellular regulated protein kinases, ERK1/2)抑制剂,采用western blot探讨间隙连接、丝裂原活化蛋白激酶(mitogen-activated protein kinases, MAPK)信号通路在HRGEC细胞焦亡中的调控关系以及甜橙黄酮的作用机理。结果 Px-12可诱导HRGEC细胞细胞膜完整性破坏,并可使 GSDMD蛋白剪切暴露其NT端,出现细胞焦亡的发生；Px-12可明显上调ROS/O_^2-的表达,激活氧化应激水平；甜橙黄酮可明显的抑制Px-12诱导的ROS/O_^2-增加,同时能够减少Px-12诱导的GSDMD-NT的形成和ERK的磷酸化；Px-12可诱导间隙连接蛋白43(Connexin 43,Cx43)的表达明显的增加,ERK信号通路抑制剂PD98059则可以明显的抑制Cx43的表达,而甜橙黄酮与其作用相似。结论 甜橙黄酮可减轻Px-12诱导的HRGEC细胞焦亡,可能与调控ERK-MAPK/Cx43信号通路相关。     

寿胎丸对脂多糖诱导的人绒毛外滋养细胞氧化应激及焦亡的调节作用

目的 探讨寿胎丸在脂多糖（LPS）诱导的人绒毛外滋养细胞（HTR-8/SVneo）损伤中的作用及其对细胞损伤中氧化应激和焦亡的调控，为寿胎丸安胎的作用机制研究提供新的方向。方法 采用LPS（100 μg?L^-1）诱导HTR-8/SVneo细胞损伤建立细胞模型，设置空白组、模型组、寿胎丸组（10%寿胎丸含药血清）、抗氧化剂组（1 mmol·L^-1 NAC）、NOD样受体热蛋白结构域3（NLRP3）抑制剂组（50 μmol·L^-1MCC950）。分别采用细胞增殖与活性检测（CCK-8）试剂盒检测细胞活性情况；Hochest 33342/PI双荧光染色和流式细胞术观察细胞死亡情况；酶联免疫吸附测定法（ELISA）检测细胞上清液中白细胞介素-18（IL-18）、白细胞介素-1β（IL-1β）、丙二醛（MDA）、超氧化物歧化酶（SOD）释放情况；DCFH-DA探针检测细胞内活性氧（ROS）含量；蛋白免疫印迹法（Western blot）检测NLRP3、胱天蛋白酶（Caspase）-1、消化道皮肤素D（GSDMD）、IL-1β蛋白的表达；实时荧光定量聚合酶链式反应（Real-time PCR）检测NLRP3、Caspase-1 mRNA的表达。结果 与空白组比较，模型组细胞活力显著降低（P<0.01），细胞上清液中炎症因子IL-1β、IL-18含量显著增加（P<0.01），氧化应激因子ROS、MDA含量升高，SOD活性显著降低（P<0.01），NLRP3、Caspase-1、GSDMD、IL-1β蛋白和NLRP3、Caspase-1 mRNA表达显著上调（P<0.01）；与模型组比较，寿胎丸组、NAC组及MCC950组细胞活力显著升高（P<0.01），寿胎丸组和NAC组MDA、ROS活性降低，SOD活性显著升高（P<0.01），寿胎丸组和MCC950组细胞上清液中IL-1β、IL-18含量减少（P<0.01），细胞内NLRP3、Caspase-1、GSDMD、IL-1β蛋白和NLRP3、Caspase-1、IL-1β mRNA表达均明显降低（P<0.05，P<0.01）。结论 寿胎丸可通过抑制氧化应激和细胞焦亡减轻LPS诱导的HTR-8/SVneo细胞损伤，这可能是寿胎丸防治复发性流产，发挥安胎作用的机制之一。     

基于NF-κB/NLRP3/Caspase-1通路介导的巨噬细胞焦亡探究葛根芩连汤对动脉粥样硬化易损斑块的干预机制

目的 探究葛根芩连汤（GQL）通过调控核转录因子（NF）-κB/NOD样受体蛋白3（NLRP3）/胱天蛋白酶（Caspase）-1通路介导的巨噬细胞焦亡对动脉粥样硬化（AS）易损斑块的作用。方法 12只正常C57BL/6CNC小鼠作为空白组，60只同品系的载脂蛋白E基因敲除（ApoE^-/-）小鼠随机分为5组，即模型组、葛根芩连汤低、中、高剂量组（GQL-D、Z、G组）、立普妥组，以高脂饲料喂养造模。空白组、模型组予等体积无菌蒸馏水灌胃；GQL-D、Z、G、立普妥组分别予对应浓度的药物灌胃8周。苏木素-伊红（HE）染色观测主动脉区域斑块情况，酶联免疫吸附测定法（ELISA）检测血清白细胞介素-1β（IL-1β）、白细胞介素-18（IL-18）水平，ELISA检测巨噬细胞甘露糖受体（MMR/CD206）/凋亡相关斑点样蛋白（ASC）、CD206/NLRP3蛋白表达水平，蛋白免疫印迹法（Western blot）检测各组小鼠gasdermin D蛋白C端（C-terminal GSDMD）、gasdermin D蛋白N端（N-terminal GSDMD）、NLRP3、含胱天蛋白酶-1前体（pro-Caspase-1）和NF-κB p65蛋白表达水平。结果 与空白组比较，模型小鼠AS病变程度严重，血清IL-1β、IL-18、组织ASC、NLRP3、C-terminal GSDMD、N-terminal GSDMD、pro-Caspase-1和NF-κB p65表达水平明显升高（P<0.05），CD206水平明显下降（P<0.05）；与模型组比较，给药各组小鼠主动脉壁AS病变程度有所减轻，血清IL-1β、IL-18、组织ASC、NLRP3、C-terminal GSDMD、N-terminal GSDMD、pro-Caspase-1和NF-κB p65表达水平有不同程度下降，CD206水平不同程度上升，部分组结果差异有统计学意义（P<0.05）。结论 GQL对AS易损斑块的干预作用可能是通过调控NF-κB/NLRP3/Caspase-1通路，减轻其介导的巨噬细胞焦亡来实现的。     

GsdmD p30 elicited by caspase-11 during pyroptosis forms pores in membranes

Gasdermin-D (GsdmD) is a critical mediator of innate immune defense because its cleavage by the inflammatory caspases 1, 4, 5, and 11 yields an N-terminal p30 fragment that induces pyroptosis, a death program important for the elimination of intracellular bacteria. Precisely how GsdmD p30 triggers pyroptosis has not been established. Here we show that human GsdmD p30 forms functional pores within membranes. When liberated from the corresponding C-terminal GsdmD p20 fragment in the presence of liposomes, GsdmD p30 localized to the lipid bilayer, whereas p20 remained in the aqueous environment. Within liposomes, p30 existed as higher-order oligomers and formed ring-like structures that were visualized by negative stain electron microscopy. These structures appeared within minutes of GsdmD cleavage and released Ca²⁺ from preloaded liposomes. Consistent with GsdmD p30 favoring association with membranes, p30 was only detected in the membrane-containing fraction of immortalized macrophages after caspase-11 activation by lipopolysaccharide. We found that the mouse I105N/human I104N mutation, which has been shown to prevent macrophage pyroptosis, attenuated both cell killing by p30 in a 293T transient overexpression system and membrane permeabilization in vitro, suggesting that the mutants are actually hypomorphs, but must be above certain concentration to exhibit activity. Collectively, our data suggest that GsdmD p30 kills cells by forming pores that compromise the integrity of the cell membrane.Pyroptosis is an inflammatory form of programmed cell death that occurs in response to microbial products in the cytoplasm or to cellular perturbations caused by diverse stimuli, including crystalline substances, toxins, and extracellular ATP (1, 2). Pyroptosis plays a critical role in the clearance of intracellular bacteria (3), but may also contribute to autoinflammatory and autoimmune disease pathology. Mechanistically, pyroptosis occurs when cytosolic nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs), including NLRP1, NLRP3, and NLRC4, or the pyrin domain-containing protein AIM2, nucleate a canonical inflammasome complex that activates the protease caspase-1 (2). Alternatively, intracellular lipopolysaccharide (LPS) from Gram-negative bacteria can trigger noncanonical activation of mouse caspase-11 and human caspases 4 and 5 (4–7). Caspases 1, 4, 5, and 11 can each cleave Gasdermin-D (GsdmD) to mediate pyroptotic cell death (8, 9). It is the N-terminal p30 fragment of GsdmD that is cytotoxic to cells, but precisely how it kills cells is unknown.Here we show that the human GsdmD p30 fragment liberated by active caspase-11 forms ring-like structures within membranes that function as pores. Therefore, we propose p30 kills cells by directly compromising the integrity of cellular membranes. We also show that the GsdmD I105N mutant that was unable to mediate macrophage pyroptosis (9) is hypomorphic at cell killing in a transient overexpression system and at liposome permeabilization in vitro—conditions where p30 concentration favors oligomerization.     

白藜芦醇对脂多糖诱导的人肺上皮细胞焦亡的保护机制研究

目的:探究白藜芦醇对脂多糖(LPS)诱导的人肺上皮细胞(又称BEAS-2B)增殖、炎症因子释放和焦亡的影响。方法:用CCK-8法检测LPS和LPS与白藜芦醇联用对BEAS-2B细胞增殖的影响;采用ELISA法检测细胞上清炎症因子肿瘤坏死因子(TNF-α)、白介素-6(IL-6)、白介素-1β(IL-1β)和白介素-18(IL-18)表达以及qPCR和Western blot检测焦亡基因NLRP3、Gasdermin D、Caspase-1、ELAVL1的表达;分析其对细胞活力、BEAS-2B细胞中细胞因子的含量及其焦亡相关基因、相关蛋白表达的影响。结果:LPS可以抑制BEAS-2B细胞的增殖,同时可以促进炎症因子的表达,经qPCR和Western blot检测结果表明LPS可以促进NLRP3、Gasdermin D、Caspase-1、ELAVL1基因的表达;其经用白藜芦醇处理48 h后,可以有效逆转LPS所引起的细胞增殖受抑制和炎症因子高表达的现象;此外,NLRP3、Gasdermin D、Caspase-1、ELAVL1的表达也部分受抑制。结论:白藜芦醇通过减少炎症因子的释放和NLRP3、Gasdermin D、Caspase-1、ELAVL1表达对LPS诱导的BEAS-2B焦亡起到一定的保护作用。     

RETRACTED: Resibufogenin suppresses growth and metastasis through inducing caspase-1-dependent pyroptosis via ROS-mediated NF-κB suppression in non-small cell lung cancer

The purpose of this study is to explore the antitumor properties of resibufogenin (RB) in non-small cell lung cancer (NSCLC) and elucidate its underlying mechanism. A549 and H520 cells were treated with various concentrations of RB with or without NLRP3 inhibitor (MCC950), caspase-1 inhibitor (VX765), or N-acetyl-l -cysteine (an ROS scavenger). Cell counting kit-8 and colony formation assays were conducted to determine cell viability. Cell invasion was detected by using the transwell assay. The release of lactate dehydrogenase (LDH) was determined by the LDH detection assay. The protein expression levels of related genes were measured by western blotting and immunohistochemistry. The reactive oxygen species (ROS) level was detected by using a 2,7-dichlorodihydrofluorescein diacetate ROS Assay Kit. The in vivo effects of RB were evaluated in a xenograft mouse model. RB treatment reduced cell viability and invasion in a dose-dependent manner. Furthermore, RB also enhanced pyroptosis levels in A549 and H520 cells, as indicated by the increased release of LDH and pyroptosis-related proteins. Interestingly, we also found that the antiproliferative and antimetastatic effects of RB were alleviated by the blockade of pyroptosis using NLRP3 inhibitor MCC950. Further study demonstrated that RB induced pyroptosis in a caspase-1-dependent manner, as evidenced by the finding that VX765 effectively reversed the effects of RB on A549 and H520 cells. We also found that RB could trigger caspase-1-dependent pyroptosis through ROS-mediated NF-κB suppression. In summary, our findings provide a potential antitumor agent and a novel insight into the mechanism of RB treatment of NSCLC.