肺炎支原体经ROS激活NLRP3炎性体诱导RAW264.7细胞分泌IL-1β

 目的: 观察肺炎支原体(Mycoplasma pneunoniae,Mp)促进NLRP3炎性体的活化及下游促炎性细胞因子白细胞介素-1β(IL-1β)的表达是否与活性氧簇(ROS)有关。方法: 预先用5 mmol/L ROS清除剂N-乙酰半胱氨酸(NAC)预处理RAW264.7细胞30 min,用10 MOI Mp分别感染RAW264.7细胞4、8、16和24 h。流式细胞术检测细胞内ROS水平;real-time PCR法检测细胞NLRP3、ASC和caspase-1 mRNA的表达;Western blot 法检测NLRP3、ASC和caspase-1 p20的蛋白水平;ELISA法检测细胞上清液IL-1β的分泌水平。结果: 与正常组比较,感染后4、8、16和24 h模型组ROS生成显著增加(P< 0.01);感染后8、16和24 h模型组NLRP3、ASC和caspase-1 mRNA的表达显著增加 (P<0.01),感染后16和24 h NLRP3、ASC和caspase-1 p20的蛋白水平上调(P<0.01),感染后24 h 细胞上清液IL-1β含量显著增加(P< 0.01);与模型组比较,NAC组在上述相应时点ROS生成降低,NLRP3、ASC和caspase-1 mRNA的表达下调,蛋白水平下降,细胞上清液IL-1β的含量减少。结论: Mp可能通过刺激RAW264.7细胞生成ROS而激活NLRP3炎性体。     

阿托伐他汀通过下调NLRP1炎性体表达抑制IL-1β和IL-18的释放

 目的:探讨核苷酸结合寡聚化结构域样受体蛋白1(NLRP1)炎性体在阿托伐他汀抑制THP-1巨噬细胞白细胞介素-1β(IL-1β)和白细胞介素-18(IL-18)分泌中的作用。方法:用10 μg/L脂多糖诱导THP-1巨噬细胞分泌IL-1β和IL-18,以不同浓度阿托伐他汀(1、10和20 μmol/L)孵育细胞24 h,或以10 μmol/L阿托伐他汀处理细胞不同时间(12、24和48 h),或转染NLRP1 siRNA以沉默细胞内NLRP1的表达。采用RT-PCR检测细胞内NLRP1炎性体mRNA的表达,Western blot检测细胞内NLRP1炎性体蛋白的表达,ELISA检测细胞上清液中IL-1β和IL-18的含量。结果:阿托伐他汀可抑制THP-1巨噬细胞NLRP1炎性体mRNA和蛋白的表达,且这种效应呈浓度和时间依赖性。转染NLRP1 siRNA后,THP-1巨噬细胞NLRP1的蛋白表达明显下降,且阿托伐他汀对IL-1β和IL-18分泌的抑制作用明显增强。结论:阿托伐他汀通过抑制NLRP1炎性体表达减少巨噬细胞IL-1β和IL-18的释放,发挥抗炎作用,进而延缓动脉粥样硬化进展。     

SO_2衍生物通过NLRP3炎症小体促进气道上皮细胞炎症发生

目的:观察二氧化硫(SO_2)衍生物亚硫酸钠和亚硫酸氢钠对支气管上皮细胞NLRP3炎症小体活化的影响。方法:使用不同浓度的SO_2衍生物作用于支气管上皮细胞16HBE,通过流式细胞术检测细胞内活性氧簇(ROS)的生成,Western blot检测细胞内NLRP3和caspase-1 p20蛋白水平,ELISA检测细胞上清中白细胞介素1β(IL-1β)的分泌水平,结合细胞毒性实验(MTT)确定2 mmol/L为SO_2衍生物的实验浓度。采用RNA干扰技术沉默16HEB细胞NLRP3基因及ROS清除剂N-乙酰半胱氨酸(NAC)预处理16HBE细胞,通过流式细胞术检测细胞内ROS, Western blot和ELISA分别检测NLRP3和caspase-1 p20蛋白表达及IL-1β分泌水平。结果:与对照组比较, 2 mmol/L和4 mmol/L SO_2衍生物组细胞内ROS水平、 NLRP3和caspase-1 p20蛋白表达及细胞上清液中IL-1β水平明显升高(P0.05)。与2 mmol/L SO_2衍生物组比较,NLRP3 siRNA组细胞内的NLRP3和caspase-1 p20蛋白水平明显降低(P0.05),且细胞上清液中IL-1β的浓度明显下降(P0.05),ROS无明显变化;NAC组NLRP3和caspase-1 p20蛋白水平及IL-1β浓度均明显下降(P0.05)。结论:SO_2衍生物激活支气管上皮细胞NLRP3炎症小体,促进IL-1β生成。     

HO-1高表达对脂肪干细胞在低氧无血清条件下的保护作用及机制

 目的:探讨诱导内源性血红素氧合酶-1（HO-1）表达对脂肪干细胞（ADSCs）在低氧无血清条件下的保护作用及其可能的分子机制。方法: 分离培养SD大鼠脂肪干细胞进行低氧无血清处理,DAPI染色检测细胞凋亡率;Western blotting 法分析HO-1、NLRP3 、凋亡相关斑点样蛋白 (ASC)和cleaved caspase-1的蛋白表达;ELISA 法测定培养上清液中白细胞介素-1β (IL-1β) 的水平;采用 DCFH-DA 荧光探针检测细胞内活性氧 (ROS) 的水平。结果: 钴原卟啉诱导ADSCs HO-1蛋白呈剂量依赖性表达,以20 μmol/L最为显著;诱导内源性HO-1的表达明显抑制ADSCs在低氧无血清条件下的细胞凋亡率和NLRP3、ASC、cleaved caspase-1的蛋白表达,并减少细胞内ROS和上清液IL-1β的水平;而这种保护效应可被同时给予的HO-1抑制剂锌原卟啉所逆转。结论: 诱导内源性HO-1的表达可能通过抑制NLRP3炎症小体的激活以及减少IL-1β的分泌,对低氧无血清条件下ADSCs发挥保护作用。     

X线辐照激活NLRP3炎性体引起损伤肺组织细胞焦亡(pyroptosis)北大核心CSCD

目的建立放射性肺损伤模型,研究胱天蛋白酶1(caspase-1)依赖的程序性细胞死亡即细胞焦亡(pyroptosis)在放射性肺炎发病机制中的作用。方法 BALB/c小鼠胸腔15 Gy X线辐照5 d,处死小鼠。HE染色观察肺组织形态变化,原位末端转移酶标记技术(TUNEL)检测辐照后肺组织细胞凋亡情况,Western blot法检测肺组织γ组蛋白2AX(γ-H2AX)、抗原KI-67(ki67)、含pyrin结构域NOD样受体家族3(NLRP3)、caspase-1和含CARD结构域凋亡相关斑点样蛋白(ASC/TMS-1)的表达情况,实时荧光定量PCR检测肺组织白细胞介素6(IL-6)、IL-8、肿瘤坏死因子α(TNF-α)、单核细胞趋化蛋白1(MCP-1)、含pyrin结构域NOD样受体家族3(NLRP3)、caspase-1、白细胞介素1β(IL-1β)、IL-18的m RNA水平,采用免疫组织化学染色检测肺组织NLRP3、caspase-1和TMS1的表达情况,使用caspase-1活性检测试剂盒检测caspase-1活性;ELISA检测血清IL-1β和IL-18水平。结果辐照后小鼠肺泡壁毛细血管扩张充血,炎性细胞浸润,肺泡壁增厚;肺组织细胞TUNEL染色阳性指数升高,γ-H2AX和ki67的表达增强,提示细胞DNA遭到破坏且细胞增殖活性降低;肺组织细胞中IL-6、IL-8、TNF-α和MCP-1 m RNA水平增加;血清IL-1β和IL-18水平增加,肺组织NLRP3、caspase-1、ASC/TMS-1表达水平增加,caspase-1活性增强。结论辐照后,激活小鼠肺组织NLRP3炎性体诱导肺组织的细胞发生pyroptosis。     

熊果酸对肝纤维化大鼠NOX2/ROS/NLRP3炎性小体活化的影响

目的观察熊果酸(UA)对肝纤维化模型大鼠肝内胶原沉积的改善作用及其对NADPH氧化酶2(NOX2)/活性氧簇(ROS)/NLRP3炎性小体活化的影响。方法将大鼠随机分为对照组、CCl4模型组及UA治疗组。用CCl4诱导构建SD大鼠肝纤维化模型,一半用作UA治疗组。用试剂盒检测血清ALT含量;HE染色观察肝脏病理;天狼星红染色观察肝内胶原沉积;RT-q PCR法检测Nox2、Nlrp3、caspase1及IL-1βmRNA表达量;Western blot及免疫组化检测肝脏中NOX2、NLRP3、casepase-1 p45、caspase-1 p10及IL-1β蛋白表达;DCFH-DA荧光探针法检测肝脏组织内ROS水平。结果与对照组相比,CCl4模型组血清ALT水平升高(P0.05),Ishak's肝纤维化评分明显上升,胶原沉积明显增多(P0.05),Nox2、Nlrp3、Caspase1及IL-1βmRNA的表达水平明显上升(P0.05);NOX2、NLRP3、caspase-1 p10及IL-1β蛋白的表达均出现明显增加,肝组织内ROS含量增加(P0.05);与CCl4模型组相比,UA治疗组血清ALT含量下降(P0.05),肝脏Ishak's肝纤维化评分及胶原沉积减少(P0.05),Nox2、Nlrp3、caspase1及IL-1βmRNA的表达水平明显下降(P0.05),NOX2、NLRP3、caspase-1 p10及IL-1β蛋白表达明显下降,肝脏组织内ROS水平显著改善(P0.05)。结论 UA减轻肝脏炎性反应并减少肝内胶原沉积,其机制可能与其抑制肝纤维化大鼠肝内NOX2/ROS/NLRP3炎性小体活化及IL-1β的释放减少有关。     

幽门螺杆菌经ROS通路激活NLRP3炎症复合体诱导THP-1细胞分泌IL-1β和IL-18

目的:研究幽门螺杆菌(H.pylori)对NLRP3炎症复合体活化的影响及活性氧(ROS)在其中的作用。方法:将THP-1细胞与H.pylori SS1共孵育,于不同时间点收集细胞及上清,ELISA检测细胞上清中IL-1β和IL-18的含量;流式细胞术(FCM)检测胞内ROS的产生;实时荧光定量PCR(Real-time PCR)检测细胞中NLRP3、caspase-1 mRNA的表达;Western blot检测细胞中caspase-1活性亚单位p10的表达;检测ROS清除剂N-乙酰半胱氨酸(N-acetylcysteine,NAC)及NLRP3特异性小干扰RNA(small interfering RNA,siRNA)预处理细胞后相关信号分子的表达。结果:H.pylori SS1能以时间依赖性和剂量依赖性方式诱导THP-1细胞产生IL-1β、IL-18和胞内ROS;H.pylori SS1刺激能使THP-1细胞NLRP3和caspase-1 mRNA转录水平显著升高;NAC及NLRP3-siRNA预处理THP-1细胞能显著降低H.pylori SS1诱导的NLRP3炎症复合体相关成份的表达及细胞因子的分泌。结论:H.pylori SS1株通过ROS途径激活NLRP3炎症复合体诱导THP-1细胞分泌IL-1β和IL-18,这可能与机体的先天免疫防御及细菌的致病作用相关。     

炎性体与器官移植

炎性体是指存在于细胞质内能够激活半胱天冬酶-1(caspase-1)的大分子复合物,活化的caspase-1通过酶切白细胞介素-1β(IL-1β)和白细胞介素-18(IL-18)前体分子而生成具有生物学活性的IL-1β和IL-18.近来研究发现,炎性体分子NLRP1、NLRP2、NLRP5、CARD8、CASP5的基因...     

小檗碱通过mtROS-NLRP3通路抑制H_(2)O_(2)诱导的巨噬细胞焦亡北大核心CSCD

目的:探究小檗碱(BBR)对过氧化氢(H_(2)O_(2))诱导的巨噬细胞焦亡的影响及mtROS-NLRP3通路在其中的调控作用。方法:以巨噬细胞J774A.1为研究对象,设置正常对照组(control组)、模型组(H_(2)O_(2)作用24 h)、BBR干预组(H_(2)O_(2)+BBR作用24 h)和ROS清除剂NAC干预组(H_(2)O_(2)+NAC作用24 h)。流式细胞术检测各组细胞活性氧簇(ROS)的生成,免疫荧光检测ROS与线粒体的共定位情况,实时荧光定量PCR检测各组细胞NLRP3、IL-1β的基因转录水平,Western blot检测NLRP3蛋白表达量,流式细胞术检测caspase-1的活化及其介导的细胞焦亡率,乳酸脱氢酶(LDH)试剂盒检测各组细胞LDH的释放量,ELISA检测IL-1β分泌水平。结果:与模型组相比,BBR干预后显著减少了H_(2)O_(2)诱导的巨噬细胞线粒体ROS(mtROS)的生成,下调了NLRP3和IL-1β的基因表达水平,减少了NLRP3蛋白的表达,降低了caspase-1活化水平及其介导的细胞焦亡率,同时减少了细胞上清液中LDH和IL-1β的释放。结论:小檗碱可能通过下调mtROS水平进而抑制NLRP3炎症体介导的细胞焦亡以减轻炎症反应。     

白蛋白导致肾小管上皮细胞NLRP3炎性体激活的机制分析

目的探讨白蛋白导致肾小管上皮细胞NLRP3炎性体激活的机制。方法采用免疫组化法检测30例不同蛋白尿水平的膜性肾病患者肾组织中组织蛋白酶B(Cathepsin B)的表达;用BSA刺激HK-2细胞,再用高浓度KCl、Cathepsin B抑制剂CA074 Me及活性氧(ROS)抑制剂二苯基氯化碘(diphenyliodonium chloride,DPI)作用于HK-2细胞,应用Western blot、实时荧光定量PCR法检测IL-1β和IL-18生成的变化。结果大量蛋白尿的膜性肾病患者肾小管上皮细胞中Cathepsin B的表达明显高于低蛋白尿的患者(P0.05);CA 074 Me组、DPI组的IL-1β和IL-18蛋白和mRNA生成明显减少(P0.05),而高浓度KCl组无明显变化(P0.05)。结论白蛋白引起的肾小管上皮细胞NLRP3炎性体激活,可能与Cathepsin B释放和ROS生成有关,而与钾离子外流无关。     

The inflammasome: an integrated view

An inflammasome is a multiprotein complex that serves as a platform for caspase-1 activation and caspase-1-dependent proteolytic maturation and secretion of interleukin-1β (IL-1β). Though a number of inflammasomes have been described, the NLRP3 inflammasome is the most extensively studied but also the most elusive. It is unique in that it responds to numerous physically and chemically diverse stimuli. The potent proinflammatory and pyrogenic activities of IL-1β necessitate that inflammasome activity is tightly controlled. To this end, a priming step is first required to induce the expression of both NLRP3 and proIL-1β. This event renders the cell competent for NLRP3 inflammasome activation and IL-1β secretion, and it is highly regulated by negative feedback loops. Despite the wide array of NLRP3 activators, the actual triggering of NLRP3 is controlled by integration a comparatively small number of signals that are common to nearly all activators. Minimally, these include potassium efflux, elevated levels of reactive oxygen species (ROS), and, for certain activators, lysosomal destabilization. Further investigation of how these and potentially other as yet uncharacterized signals are integrated by the NLRP3 inflammasome and the relevance of these biochemical events in vivo should provide new insight into the mechanisms of host defense and autoinflammatory conditions.     

Capsular Polysaccharide Is Involved in NLRP3 Inflammasome Activation by Klebsiella pneumoniae Serotype K1

Klebsiella pneumoniae (strain 43816, K2 serotype) induces interleukin-1β (IL-1β) secretion, but neither the bacterial factor triggering the activation of these inflammasome-dependent responses nor whether they are mediated by NLRP3 or NLRC4 is known. In this study, we identified a capsular polysaccharide (K1-CPS) in K. pneumoniae (NTUH-K2044, K1 serotype), isolated from a primary pyogenic liver abscess (PLA K. pneumoniae), as the Klebsiella factor that induces IL-1β secretion in an NLRP3-, ASC-, and caspase-1-dependent manner in macrophages. K1-CPS induced NLRP3 inflammasome activation through reactive oxygen species (ROS) generation, mitogen-activated protein kinase phosphorylation, and NF-κB activation. Inhibition of both the mitochondrial membrane permeability transition and mitochondrial ROS generation inhibited K1-CPS-mediated NLRP3 inflammasome activation. Furthermore, IL-1β secretion in macrophages infected with PLA K. pneumoniae was shown to depend on NLRP3 but also on NLRC4 and TLR4. In macrophages infected with a K1-CPS deficiency mutant, an lipopolysaccharide (LPS) deficiency mutant, or K1-CPS and LPS double mutants, IL-1β secretion levels were lower than those in cells infected with wild-type PLA K. pneumoniae. Our findings indicate that K1-CPS is one of the Klebsiella factors of PLA K. pneumoniae that induce IL-1β secretion through the NLRP3 inflammasome.     

TLR4/NLRP3炎症复合体介导对比剂诱导的肾小管上皮细胞炎症和损伤

目的:探讨Toll样受体4(TLR4)/Nod样受体蛋白3(NLRP3)炎症复合体是否介导了对比剂(CM)引起的肾小管上皮细胞炎症和损伤。方法:本研究运用碘普罗胺作用于大鼠肾小管上皮细胞NRK-52E建立损伤模型。应用CCK-8法测定细胞存活率;Western blot测定TLR4、NLRP3、凋亡相关斑点样蛋白(ASC)、caspase-1和cleaved caspase-3的蛋白水平;ELISA法检测炎症因子白细胞介素1β(IL-1β)和IL-18的水平;Hoechst 33258核染色法检测凋亡率;JC-1染色法测定线粒体膜电位。用小干扰RNA沉默NLRP3表达。结果:CM可降低NRK-52E细胞的存活率并上调cleaved caspase-3的蛋白水平(P0.05);此外,CM可上调细胞TLR4/NLRP3炎症复合体的表达并促进炎症因子IL-1β和IL-18的分泌(P0.05)。沉默NLRP3可以对抗CM诱导的炎症因子分泌;TLR4抑制剂TAK-242及沉默NLRP3能减轻CM引起的细胞凋亡和线粒体功能损伤。结论:TLR4/NLRP3炎症复合体参与了CM致急性肾损伤的发病机制,并介导了CM诱导的肾小管上皮细胞损伤和炎症。     

大鼠急性心肌梗死后NLRP3炎性体-IL-1β信号轴激活与End-MT的关系

目的:研究在急性心肌梗死(acute myocardial infarction,AMI)引发的心肌纤维化过程中,NLRP3炎性体-IL-1β信号轴的激活与内皮-间充质转化(endothelial-mesenchymal transition,End-MT)是否存在同一性。方法:30只成年雄性SD大鼠随机分为假手术组(n=15)与AMI组(n=15),术后28 d采用Masson染色检测心肌纤维化水平;Western blot检测NLRP3炎性体(NLRP3、ASC、pro-caspase-1和caspase-1)、内皮细胞标志物(CD31和VE-cadherin)及间充质细胞标志物(α-SMA和FSP1)的表达;酶联免疫吸附法检测NLRP3炎性体下游因子IL-1β的表达。结果:与假手术组相比,冠脉结扎组AMI大鼠心肌纤维化水平、End-MT进展程度、NLRP3炎性体活性及caspase-1和IL-1β的表达均显著增加(P0.05)。结论:NLRP3炎性体-IL-1β信号轴的激活与End-MT进程具有显著同一性,提示NLRP3炎性体-IL-1β作为激活End-MT的潜在靶点将为研究AMI后心肌纤维化及心力衰竭提供新的理论依据。     

Mycophenolic acid enhanced lipopolysaccharide-induced interleukin-18 release in THP-1 cells via activation of the NLRP3 inflammasome

Abstract

Background: Interleukin (IL)-18 is a pro-inflammatory cytokine that has important functions in host defense. The maturation and secretion of IL-18 has been shown to be regulated by the NOD-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome. Mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF), in association with lipopolysaccharide (LPS), is able to promote the secretion of IL-18, but the mechanism remains unknown. This study aims to explore the mechanism by which MPA synergizes with LPS to induced IL-18 release.

Methods: THP-1 cells were stimulated with LPS and MPA and treated with or without the inhibitors of caspase-1, Ac-YVAD-cmk or KCl; IL-18 in the supernatants was measured by ELISA. The intracellular protein levels of NF-κB p-p65, pro-IL-18, NLRP3, and cleaved caspase-1(p20) were measured by Western blot.

Results: We found that MPA alone failed to induce IL-18, whereas MPA enhanced LPS-mediated IL-18 release. MPA did not affect the intracellular protein levels of NF-κB p-p65 or pro-IL-18 but activated the NLRP3 inflammasome. Ac-YVAD-cmk or increasing extracellular K⁺ blocked the activation of caspase-1 and attenuated the release of IL-18.

Conclusions: Taken together, MPA synergized with LPS to induce the release of IL-18 via activating the NLRP3 inflammasome and increasing the degradation of pro-IL-18, rather than by enhancing the production of pro-IL-18.