炎症小体及细胞焦亡在肠道稳态中的研究进展

炎症小体是一种细胞内多蛋白复合物，主要包括NLRP3、AIM2、NLRP6、NLRP12等亚型。识别相关刺激后，炎症小体进行组装并激活caspase-1，激活的caspase-1促进IL-1β和IL-18成熟和分泌。另外，活化的caspase-1也可裂解gasdermin D(GSDMD)，导致特殊形式的细胞死亡——细胞焦亡。肠道稳态在维持机体健康中起重要作用，而炎症小体及细胞焦亡通路在肠道稳态维持中发挥重要作用。本文主要阐述炎症小体及细胞焦亡在肠道稳态维持中的最新研究进展。     

细胞焦亡在脑缺血再灌注损伤中的研究进展

细胞焦亡(Proptosis)是近年来发现的一种程序性细胞死亡形式,主要依靠炎症小体激活部分Caspase家族蛋白(Caspase-1/4/5/11),切割其下游的Gasdermin-D(GSDMD)蛋白后,定位到细胞膜上形成孔洞,最终导致细胞膜破裂,并释放出细胞内容物及炎性因子等.目前研究表明,细胞焦亡参与了脑缺血再灌注的损伤过程.本文着重探讨细胞焦亡在脑缺血再灌注损伤中的机制及相关药物治疗进展,以期为缺血性脑卒中的防治提供一定理论依据.     

NLRP3炎性小体激活调控机制研究新进展

NLRP3炎性小体是一种胞内多蛋白复合体,主要由NOD样受体家族成员NLRP3、接头蛋白ASC以及前体半胱天冬酶1(pro-caspase-1)组成,该炎性小体可以通过激活caspase-1促进促炎因子白细胞介素-1 beta(IL-1β)和IL-18的分泌以及细胞焦亡(pyroptosis)的形成.NLRP3炎性小体的激活在很多自身免疫性及自身炎症性疾病中扮演着重要的角色,因此,深入探究NLRP3炎性小体激活的调控机制可为NLRP3炎性小体相关疾病的治疗提供更多新的思路.     

NOD1,NOD2和NLRP3炎症小体与牙髓炎

模式识别受体(pattern recognition receptors,PRRs)识别病原相关分子模式(pathogen associated molecule patterns,PAMP)激活固有免疫系统,是抵抗病原微生物入侵的第一道防线.核苷酸结合寡聚化结构域蛋白(nucleotide-binding oligomerization domains,NODs)和NOD样受体蛋白3(NODlike protein 3,NLRP3)属胞质内PRRs家族.NOD1和NOD2激活NF-κB,MAPK,JNK,p38和ERK信号通路,促进TNF-α,IL-1β,IL-6,IL-8和IL-12等多种炎性因子的转录表达.NLRP3炎症小体激活caspase-1,并促进IL-18和IL-1β表达.牙髓位于低顺应性根管系统中,牙髓环境环境与机体其他组织不同.目前的研究表明NOD1,NOD2和NLRP3炎症小体与牙髓固有免疫及牙髓炎的发生、发展有关.     

GSDMD是细胞焦亡的关键蛋白

细胞焦亡是一种新的细胞死亡模式,该模式不仅能通过依赖于模式识别受体来识别内源性危险信号、病原微生物及其产物刺激炎性小体的作用来激活caspase-1/4/5/11作用于GSDMD;而且使得GSDMD的氨基末端转移至细胞膜上形成的孔隙能允许水分子等物质进入细胞内而引起肿胀及裂解而导致细胞死亡。然而,在细胞焦亡的过程中,关于GSDMD在该过程中的作用以及在相关疾病、肿瘤中的作用仍是个谜。因此,这篇综述的目的是强调了GSDMD引起的焦亡在相关疾病及肿瘤中的作用。     

柯里拉京抑制LPS和ATP激活的NLRP3炎症小体和巨噬细胞焦亡

目的 探讨柯里拉京对细菌脂多糖(LPS)联合腺嘌呤核苷三磷酸(ATP)诱导的巨噬细胞内NLRP3炎症小体活化和细胞焦亡的调控作用和机制。方法 采用CCK8试剂检测不同浓度柯里拉京对J774A.1细胞活力的影响;碘化丙啶(PI)染色和乳酸脱氢酶(LDH)释放检测柯里拉京对LPS+ATP诱导的细胞死亡的影响。Western blot法检测细胞上清液中炎症小体活化标志物caspase-1 p20(M_r20 000)和成熟IL-1β(M_r17 000)的表达水平,以及检测细胞内NLRP3、ASC、caspase-1、IL-1β前体(pro-IL-1β)和焦亡执行蛋白GSDMD的表达。ELISA检测细胞培养上清液中IL-1β的水平。活性氧(ROS)荧光探针H2DCFDA染色观察柯里拉京对ROS产生的影响。结果 柯里拉京浓度小于40μmol·L^-1时对细胞活性影响较小。柯里拉京减少LPS+ATP刺激的细胞内PI阳性细胞的比例和LDH的释放。柯里拉京抑制LPS+ATP刺激的巨噬细胞内GSDMD蛋白N末端(GSDMD-NT)的表达,以及...     

脂多糖通过NLRP3诱导并促进慢性鼻窦炎人鼻黏膜上皮细胞焦亡北大核心CSCD

目的革兰氏阴性菌能够诱发并加重慢性鼻窦炎(CRS)炎症反应,但病理机制有待进一步证实,而细胞焦亡被证实与细菌性炎症反应密切相关,因此本研究重点探讨来源于革兰氏阴性菌的关键成分脂多糖(LPS)是否能够通过诱导并加剧CRS患者鼻黏膜上皮细胞焦亡来促进CRS的炎症进展。方法利用临床上对照组和CRS组患者的鼻黏膜组织,采用IHC检测焦亡相关蛋白的表达。提取并培养正常原代人鼻黏膜上皮细胞(N-HNEpCs)和CRS原代人鼻黏膜上皮细胞(CRS-HNEpCs)。随后将2种细胞分为4组(对照组、LPS 1 mg/L组、LPS 5 mg/L组和LPS 25 mg/L组);CCK-8检测细胞存活率,EthD-I荧光染色结合GSDMD检测细胞焦亡,免疫荧光技术、Western blot、RT-qPCR检测炎性介质IL-18、IL-1β和NLRP3炎症小体(NLRP3、ASC、cleaved Caspase-1)的表达。结果IHC显示CRS患者鼻黏膜组织中NLRP3、cleaved Caspase-1、IL-18和IL-1β蛋白表达相较对照组显著增加(P<0.01)。体外实验结果表明,不同浓度的LPS刺激均可降低N-HNEpCs和CRS-HNEpCs的存活率(P<0.05),并可增加EthD-I荧光染色阳性细胞数和焦亡关键蛋白GSDMD的表达(P<0.05),且呈现出剂量依赖关系;免疫荧光技术、Western blot和RT-qPCR结果均显示5 mg/L LPS刺激后,N-HNEpCs和CRS-HNEpCs内炎性介质IL-18、IL-1β和NLRP3炎症小体的表达显著上调(P<0.05)。结论LPS可通过激活NLRP3炎症小体从而触发正常原代人鼻黏膜上皮细胞焦亡,并可进一步促进CRS原代人鼻黏膜上皮细胞焦亡进展,提示革兰氏阴性菌可能通过诱发鼻黏膜上皮细胞焦亡从而引起并加剧CRS病变。     

NLRP3炎性小体在动脉粥样硬化发生发展中的作用

NLRP3炎性小体是一种包含胞内受体(主要是NOD样受体)、半胱天冬氨酸前体和凋亡相关斑点样蛋白的蛋白质复合体.该复合体最初只是被描述为一种影响感染和炎症过程的复合体,它的活化引起半胱天冬氨酶-1的激活并剪切加工底物白细胞介素-1β(interleukin-1β,IL-1β)和白细胞介素-18(interleukin-18,IL-18),从而引起炎症反应;此外,炎性小体的激活过程对有氧糖酵解(瓦伯格效应,Warburg effect)有着重要的影响,这同样可以促进炎症的发生.随后的证据表明炎性小体的活化还影响很多代谢紊乱包括动脉粥样硬化(atherosclerosis, AS)、2型糖尿病、痛风和肥胖等.本综述将探讨AS与炎症、NLRP3炎性小体活化的关联性,以及瓦伯格效应如何关联炎症反应及炎性小体的激活.     

细胞焦亡效应蛋白的作用机制及相关疾病的研究进展

细胞焦亡是一种促炎的程序性细胞死亡方式,并同时具有凋亡和坏死的特点。Toll样受体(Toll like receptors,TLRs)可以感受及识别不同的刺激,并传递信号至依赖半胱氨酸天冬氨酸酶-1(caspase-1)的经典焦亡途径或依赖半胱氨酸天冬氨酸酶-11(caspase-11)的非经典焦亡途径。炎性体在激活信号下的装配是诱导焦亡途径的核心环节,其中NLRP3炎性体是目前研究最多的,是其典型代表。激活的炎性体可以活化炎性caspases,后者进一步促进白细胞介素-1β/18(IL-1β/18)的成熟和释放。焦亡的执行蛋白GSDMD可以在细胞膜上形成膜孔,最终导致细胞渗透溶胀和裂解,同时将炎症因子释放到细胞外,进一步加重炎症反应。     

NLRP3 炎症小体在神经血管疾病中的作用

炎症小体是多蛋白复合物,可以招募并诱导半胱氨酸天冬氨酸酶-1前体(pro-caspase-1)成为有活性的半胱氨酸天冬氨酸酶-1(caspase-1),从而促进IL-1β和IL-18成熟与释放。许多研究表明NLRP3炎症小体与缺血性脑卒中、阿兹海默症(AD)、外伤性脑损伤(TBI)、脑瘤等神经血管疾病的发生发展密切相关。本文综述了NLRP3炎症小体激活途径,并着重介绍了NLRP3炎症小体介导的在上述几种神经血管疾病中的作用,为相关研究提供了基础资料。     

Caspase-11 is expressed in the colonic mucosa and protects against dextran sodium sulfate-induced colitis

Ulcerative colitis and Crohn's disease are major inflammatory syndromes that affect millions of patients. Caspase-11 confers protection against Gram-negative enteropathogens, but its role during colitis is unknown. Here, we show that caspase-11 was constitutively expressed in the colon, and that caspase-11-deficient (caspase-11^−/−) mice were hypersusceptible to dextran sodium sulfate (DSS)-induced colitis. Notably, pro-inflammatory Prevotella species were strongly reduced in the gut microbiota of caspase-11^−/− mice. Co-housing with wild-type mice leveled Prevotella contents, but failed to protect caspase-11^−/− mice from increased susceptibility to DSS-induced colitis. We therefore addressed the role of caspase-11 in immune signaling. DSS-induced tissue damage, release of the pyroptosis/necroptosis marker HMGB1, and inflammatory cell infiltration in the gut were markedly increased in caspase-11^−/− mice. Moreover, caspase-11^−/− mice showed normal or increased production of mature interleukin (IL)-1β and IL-18, whereas IL-1β and IL-18 secretion was blunted in animals lacking both caspases 1 and 11. In conclusion, we showed that caspase-11 shapes the gut microbiota composition, and that caspase-11^−/− mice are highly susceptible to DSS-induced colitis. Moreover, DSS-induced inflammasome activation relied on caspase-1, but not caspase-11. These results suggest a role for other caspase-11 effector mechanisms such as pyroptosis in protection against intestinal inflammation.     

Entamoeba histolytica-induced IL-1β secretion is dependent on caspase-4 and gasdermin D

During invasion, Entamoeba histolytica (Eh) encounter macrophages and activate them to elicit tissue damaging pro-inflammatory responses. When Eh binds macrophages via the Gal-lectin, surface EhCP-A5 RGD sequence ligates α₅β₁ integrin to activate caspase-1 in a complex known as the NLRP3 inflammasome. In this study, we investigated Eh requirements underlying macrophage caspase-4 and -1 activation and the role caspase-4 and gasdermin D (GSDMD) play in augmenting pro-inflammatory cytokine responses. Caspase-4 activation was similar to caspase-1 requiring live Eh attachment via the Gal-lectin and EhCP-A5. However, unlike caspase-1, caspase-4 activation was independent of ASC and NLRP3. Using CRISPR/Cas9 gene editing of caspase-4 and -1 and GSDMD, we determined that caspase-1 and bioactive IL-1β release was highly dependent on caspase-4 activation and cleavage of GSDMD in response to Eh. Formaldehyde cross-linking to stabilize protein–protein interactions in transfected COS-7 cells stimulated with Eh revealed that caspase-4 specifically interacted with caspase-1 in a protein complex that enhanced the cleavage of caspase-1 CARD domains to augment IL-1β release. Activated caspase-4 and -1 cleaved GSDMD liberating the N-terminal p30 pore-forming fragment that caused the secretion of IL-1β. These findings reveal a novel role for caspase-4 as a sensor molecule to amplify pro-inflammatory responses when macrophage encounters Eh.     

Caspase-11非经典炎症小体对问号钩端螺旋体诱导J774A.1细胞炎性细胞因子分泌水平的影响

目的:了解caspase-11非经典炎症小体对问号钩端螺旋体(钩体)诱导J774A.1细胞分泌炎性细胞因子的影响。方法:采用钩体56601株感染小鼠单核-巨噬细胞株(J774A.1)建立细胞模型,应用real-time RT-PCR检测J774A.1细胞caspase-11、IL-1β、IL-1α和IL-18 mRNA水平,采用ELISA定量检测J774A.1细胞上清液中caspase-11、IL-1β、IL-1α和IL-18水平。结果:Real-time RT-PCR检测结果显示,钩体感染J774A.1细胞1、2、4、8、12和24 h后,caspase-11 mRNA水平分别为未感染细胞的5.12、14.21、8.94、14.06、18.58和0.93倍,caspase-11阻断后分别下降至0.10、0.07、0.10、0.09、0.07和0.45倍( P<0.05);钩体感染后,IL-1β、IL-1α和IL-18 mRNA水平均显著上调,caspase-11阻断后IL-1β mRNA水平分别下降至0.05、0.03、0.02、0.05、0.06和0.02倍( P<0.05);IL-1α mRNA分别下降至0.14、0.07、0.15、0.10、0.03和0.06倍( P<0.05);IL-18 mRNA分别下降至0.08、0.10、0.16、0.18、0.10和0.07倍( P<0.05)。ELISA检测结果显示,钩体感染J774A.1细胞后细胞上清液中caspase-11、IL-1β、IL-1α和IL-18水平均显著上调,caspase-11阻断后caspase-11分别下降至43.07、41.64、51.96、86.56、105.36和129.95 pg/ml( P<0.05);IL-1β分别下降至15.01、14.19、68.02、31.20、173.13和104.98 pg/ml( P<0.05);IL-1α分别下降至12.14、15.40、38.01、21.97、24.48和27.09 pg/ml( P<0.05);IL-18分别下降至96.27、102.21、85.34、116.28、155.36和114.03 pg/ml( P<0.05)。 结论:Caspase-11非经典炎症小体参与介导问号钩体诱导小鼠单核-巨噬细胞IL-1β、IL-1α和IL-18的分泌。     

Molecular mechanisms and functions of pyroptosis,inflammatory caspases and inflammasomes in infectious diseases

Cell death is a fundamental biological phenomenon that is essential for the survival and development of an organism. Emerging evidence also indicates that cell death contributes to immune defense against infectious diseases. Pyroptosis is a form of inflammatory programmed cell death pathway activated by human and mouse caspase-1, human caspase-4 and caspase-5, or mouse caspase-11. These inflammatory caspases are used by the host to control bacterial, viral, fungal, or protozoan pathogens. Pyroptosis requires cleavage and activation of the pore-forming effector protein gasdermin D by inflammatory caspases. Physical rupture of the cell causes release of the pro-inflammatory cytokines IL-1β and IL-18, alarmins and endogenous danger-associated molecular patterns, signifying the inflammatory potential of pyroptosis. Here, we describe the central role of inflammatory caspases and pyroptosis in mediating immunity to infection and clearance of pathogens.     

Salmonella-induced inflammasome activation in humans

Inflammasomes are macromolecular complexes that assemble upon recognition of pathogen- or danger-associated molecular patterns. Inflammasome assembly is nucleated by the oligomerisation of specific, activated pattern recognition receptors within the cytosol. Inflammasomes function as platforms for the activation of the caspase-1 protease, which in turn triggers the maturation and secretion of the pro-inflammatory cytokines IL-1β and IL-18, and initiates pyroptosis, a highly inflammatory form of lytic cell death. Recently, additional inflammatory caspases (murine caspase-11, and human caspase-4/5) were also reported to be activated upon a pyroptosis-inducing ‘non-canonical inflammasome’ by direct recognition of lipopolysaccharide (LPS), a pathogen-associated molecular pattern. Here we review and discuss recent advances in our understanding of inflammasome-mediated host defence against Salmonella particularly in human cells, and their implications for cellular survival and cytokine secretion.     

细胞焦亡：程序性死亡研究新热点

细胞焦亡(Pyroptosis)是一种以促炎性为特点的细胞程序性死亡方式,分为依赖半胱氨酸蛋白酶-1(Caspase-1)的经典细胞焦亡途径和依赖半胱氨酸蛋白酶-4/5/11(Caspase-4/5/11)的非经典细胞焦亡途径。研究表明细胞焦亡广泛参与到多种疾病的发生发展中。最近研究人员发现GSDMD和Pannexin-1可能是介导细胞焦亡的关键物质,但具体机制和相互关系仍有待进一步深入研究。     

Gasdermin D-independent release of interleukin-1β by living macrophages in response to mycoplasmal lipoproteins and lipopeptides

Interleukin-1β (IL-1β) plays pivotal roles in controlling bacterial infections and is produced after the processing of pro-IL-1β by caspase-1, which is activated by the inflammasome. In addition, caspase-1 cleaves the cytosolic protein, gasdermin-D (GSDMD), whose N-terminal fragment subsequently forms a pore in the plasma membrane, leading to the pyroptic cell-death-mediated release of IL-1β. Living cells can also release IL-1β via GSDMD pores or other unconventional secretory pathways. However, the precise mechanisms are poorly defined. Here, we show that lipoproteins from Mycoplasma salivarium (MsLP) and Mycoplasma pneumoniae (MpLP) and an M. salivarium-derived lipopeptide (FSL-1), which are activators of the nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome, induce IL-1β release from mouse bone-marrow-derived macrophages (BMMs) without inducing cell death. The levels of IL-1β release induced by MsLP, MpLP and FSL-1 were more than 100 times lower than those induced by the canonical NLRP3 activator nigericin. The IL-1β release-inducing activities of MsLP, MpLP and FSL-1 were not attenuated in BMMs from GSDMD-deficient mice. Furthermore, both active caspase-1 and cleaved GSDMD were detected in response to transfection of FSL-1 into the cytosol of BMMs, but the release of IL-1β was unaffected by GSDMD deficiency. Meanwhile, punicalagin, a membrane-stabilizing agent, drastically down-regulated the release of IL-1β in response to FSL-1. These results suggest that mycoplasmal lipoprotein/lipopeptide-induced IL-1β release by living macrophages is not mediated via GSDMD but rather through changes in membrane permeability.     

Pyroptosis in neutrophils: Multimodal integration of inflammasome and regulated cell death signaling pathways

Pyroptosis is a proinflammatory mode of lytic cell death mediated by accumulation of plasma membrane (PM) macropores composed of gasdermin-family (GSDM) proteins. It facilitates two major functions in innate immunity: (i) elimination of intracellular replicative niches for pathogenic bacteria; and (ii) non-classical secretion of IL-1 family cytokines that amplify host-beneficial inflammatory responses to microbial infection or tissue damage. Physiological roles for gasdermin D (GSDMD) in pyroptosis and IL-1β release during inflammasome signaling have been extensively characterized in macrophages. This involves cleavage of GSDMD by caspase-1 to generate GSDMD macropores that mediate IL-1β efflux and progression to pyroptotic lysis. Neutrophils, which rapidly accumulate in large numbers at sites of tissue infection or damage, become the predominant local source of IL-1β in coordination with their potent microbiocidal capacity. Similar to macrophages, neutrophils express GSDMD and utilize the same spectrum of diverse inflammasome platforms for caspase-1-mediated cleavage of GSDMD. Distinct from macrophages, neutrophils possess a remarkable capacity to resist progression to GSDMD-dependent pyroptotic lysis to preserve their viability for efficient microbial killing while maintaining GSDMD-dependent mechanisms for export of bioactive IL-1β. Rather, neutrophils employ cell-specific mechanisms to conditionally engage GSDMD-mediated pyroptosis in response to bacterial pathogens that use neutrophils as replicative niches. GSDMD and pyroptosis have also been mechanistically linked to induction of NETosis, a signature neutrophil pathway that expels decondensed nuclear DNA into extracellular compartments for immobilization and killing of microbial pathogens. This review summarizes a rapidly growing number of recent studies that have produced new insights, unexpected mechanistic nuances, and some controversies regarding the regulation of, and roles for, neutrophil inflammasomes, pyroptosis, and GSDMs in diverse innate immune responses.     

Molecular and functional characterization of gilthead seabream Sparus aurata caspase-1: the first identification of an inflammatory caspase in fish

Caspases are a family of cysteine proteases that fulfil critical roles in mammalian apoptosis and in the proteolytic activation of cytokines. In humans, the caspase family includes 13 members whose functions seem to correlate with their phylogenetic relationship. They are classified into two main groups, the cell death (apoptotic) and the inflammatory caspases. Caspase-1 is the best characterized inflammatory caspase and is responsible for the processing of interleukin-1beta (IL-1beta), IL-18 and IL-33. Despite the importance of caspase-1 in inflammation, no information is available on the presence and activity of this enzyme in fish. In this study, we cloned a caspase-1-like gene from the bony fish gilthead seabream (Sparus aurata L.) which shows a conserved N-terminal caspase-recruitment domain (CARD) and a C-terminal caspase catalytic domain. The seabream caspase-1 gene was expressed in 1 day post-hatching larvae and its mRNA levels increased throughout development. In adult fish, caspase-1 was found to be constitutively expressed in all immune tissues analyzed and, unexpectedly, infection of fish and stimulation of professional phagocytes in vitro decreased its mRNA levels. It was also demonstrated that the recombinant seabream caspase-1 ectopically expressed in HEK293 cells was able to cleave a caspase-1 specific substrate, this activity being enhanced upon activation of the rat P2X7 receptor with BzATP. Finally, seabream fibroblast cell line SAF-1 and primary leukocytes showed endogenous caspase-1 activity, which was almost completely inhibited by a caspase-1 specific inhibitor.