NLRP3炎症体与痛风的研究进展

痛风是由于机体血尿酸过饱和形成针状尿酸盐(Monosodium urate,MSU)沉积在关节腔导致的炎症。IL-1β是急性痛风性关节炎进程中重要的细胞因子,与炎症的产生以及炎症的级联放大反应有关,IL-1β的产生与细胞中炎症小体NLRP3复合体密切相关。研究者认为NLRP3炎症体是痛风性关节炎反应进程中的关键环节,痛风也被称为NLRP3炎症体相关疾病。本文综述了NLRP3炎症体与痛风的关系、相关机制,以及靶向NLRP3炎症体的小分子抑制剂,为今后寻找结构新颖、高效低毒的抗痛风新药的研究提供参考。     

NLRP3炎症小体介导的炎症相关疾病研究进展

炎症小体在炎症相关疾病的发生发展中发挥重要作用,其中NLRP3炎症小体能够被多种病原相关分子模式(pathogen-associated molecular patterns,PAMPs)和损伤相关分子模式(damage-associated molecular patterns,DAMPs)激活,进而活化caspase-1,释放成熟形式的IL-1β和IL-18,引起机体的炎症反应,并参与多种疾病的发生发展,包括2型糖尿病、痛风、动脉粥样硬化、神经退行性疾病、肿瘤、炎症性肠病等。因此,研究NLRP3炎症小体的作用机制不仅有助于加深对炎症性疾病发生发展的认识,也为寻找此类疾病的潜在治疗靶点提供了新的思路。就NLRP3炎症小体在炎症相关疾病中的研究进展作一综述。     

中药有效成分调控NLRP3 炎症小体活化的研究进展

炎症小体是细胞内组装形成的大分子蛋白复合体,可将白介素-1β(IL-1β) 和IL-18 加工成熟,并诱导细胞焦亡性死亡,在协调对抗病原体感染和生理紊乱的过程中发挥重要作用。Nod 样受体蛋白3(Nod-like receptor protein 3, NLRP3) 炎症小体是迄今为止结构和功能研究得最为明确的炎症小体,其活化后参与免疫性疾病、心血管疾病、神经系统疾病等多种疾病发生及发展过程。研究显示,许多中药有效成分可以调节相关疾病靶细胞中NLRP3 炎症小体的活化。从中药有效成分调节相关疾病靶细胞（如神经细胞、肝肾细胞、内皮细胞、肿瘤细胞等）中NLRP3 炎症小体活化的机制出发,综述近4 年国内外对中药有效成分调节NLRP3 炎症小体活化的研究进展,以期阐释相关中药有效成分的作用特点,并为相关疾病的防治提供一定参考。     

自噬与NLRP3炎症小体的相互作用

自噬是一种普遍存在的细胞内稳态机制,通过将细胞质成分运送到溶酶体进行降解,以抵抗病原体感染并促进氨基酸循环。NLRP3炎症小体是一种多蛋白复合物,在多种内源和外源性刺激下被激活,介导促炎细胞因子的分泌,参与炎症的发生。自噬功能失调可导致NLRP3炎症小体的过度激活,引起各种炎症性疾病以及癌症的发生。自噬作为NLRP3炎症小体的一种重要调节方式,可以通过去除NLRP3炎症小体的激活信号、包裹和降解其成分来调控炎症小体。此外,自噬在调控IL-1β的分泌中也起着重要作用。同样,NLRP3炎症小体也调控自噬过程,以平衡宿主防御所需的适当炎症反应以及预防过度、有害炎症的发生。因此,阐明这两个生物学过程之间的相互作用,能够加深对相关疾病发病机制的认识,为疾病治疗及药物研发提供新的思路和理论基础。     

炎症小体调控机制的研究进展

炎症小体(Inflammasome)是一种由机体胞浆内模式识别受体(PRRs)参与组成的多蛋白复合体,主要参与天然免疫反应中caspase-1激活,并介导IL-1β、IL-18的前体产生成熟细胞因子以及诱导细胞凋亡。NLRP3、NLRC4、NLRP1、AIM2是目前研究较多的炎症小体,对其结构、组成成分、作用机制等方面已有较为深入的研究,而主要只对炎症小体的活化及负性调控机制的研究进展进行了综述。     

P2X7受体与炎症相关性疾病

P2X7是一种在多种免疫细胞中广泛表达的以ATP为配体的阳离子通道受体,它的激活能引起和加重炎症反应。当细胞处于损伤、缺氧或炎症状态时, P2X7受体可被释放到胞外的大量ATP激活,进而通过活化NLRP3炎症小体、调节基因转录等方式,影响炎症介质(IL-1β、IL-18等)的释放从而参与多种炎症性疾病,如糖尿病肾病、系统性红斑狼疮(systemic lupus erythematosus,SLE)等。近年来,细胞外ATP-P2X7受体信号通路已成为炎症性疾病研究较多的通路之一。大量研究表明, P2X7受体是治疗炎症性疾病的潜在靶点。该文将对P2X7受体及其参与的炎症相关性疾病的关系作一综述。     

NLRP3炎性体与代谢性疾病的研究进展

代谢性疾病是由体内氨基酸、葡萄糖和脂质代谢紊乱引起的一类疾病,慢性炎症反应是其重要特征之一.Nod样受体蛋白3(Nod-like receptor protein 3,NLRP3)炎性体是位于细胞内的一种蛋白质复合体,主要功能为活化半胱氨酸天冬氨酸蛋白酶1(caspase-1)以间接调控白介素1β(IL-1β)、IL-18和IL-33等的成熟和分泌.NLRP3炎性体是炎性体相关研究的热点,多种内源性或外源性危险信号通过激活这一蛋白质复合体上调炎性因子的表达水平,从而促进多种代谢性疾病的发生发展.本文对NLRP3炎性体的结构、功能、调节以及在代谢性疾病中的作用做一综述,以期为代谢性疾病的防治提供新靶点.     

NLRP3炎症小体活化、调控机制及相关疾病机制

炎症作为机体的一种自我保护机制有助于清除感染或者有害物质,但是炎症反应失调也会导致疾病发生.NLRP3炎症小体是由胞内模式识别受体NOD样受体家族成员NLRP3形成的一个胞内蛋白复合物,能够诱导IL-1β和IL-18等促炎因子的成熟和分泌,从而促进炎症反应的发生.NLRP3炎症小体可以被多种病原微生物和危险信号活化,并且参与多种人类重大疾病的发生过程,因而NLRP3炎症小体近年来受到了极大的关注.本文就NLRP3炎症小体的活化和调控机制、NLRP3炎症小体在疾病中的作用及靶向NLRP3炎症小体进行相关疾病干预的研究进展进行简要综述.     

NLRP3炎症小体的负向调控机制

NLRP3炎症小体是由NOD样受体(NOD-like receptor, NLR) NLRP3、接头蛋白ASC和胱冬肽酶-1(Caspase-1)所形成的多聚蛋白复合体,能够感受来自病原微生物的病原相关分子模式(pathogen-associated molecular patterns, PAMPs)和胞内自身危险信号-危险相关分子模式(danger-associated molecular patterns, DAMPs),促进细胞因子IL-1β和IL-18的成熟和分泌、引起细胞焦亡,从而在多种生理、病理过程中发挥重要作用. NLRP3炎症小体是目前研究最深入的炎症小体,其表达水平和活化强度与多种疾病的发生、发展密切相关,如感染性疾病、痛风、Ⅱ型糖尿病、动脉粥样硬化、阿尔兹海默症及癌症等.因此,阐明NLRP3炎症小体活化的调控机制,对于揭示这些疾病发生、发展的机理,寻找免疫调节治疗的新途径具有重要意义.本文详细介绍了NLRP3炎症小体的负向调控机制.     

NLRP6炎症小体与肠道微生态研究进展

NLRP6炎症小体作为炎症反应的核心识别环节,由PRRs、ASC、Caspase三部分组成,可激活下游IL-1β、IL-18等炎症分子。肠道微生态主要由肠道内结构复杂的微生物、种类繁多的代谢物和肠道黏膜屏障组成,参与机体多种重要生命功能,与多种疾病发生发展密切相关。NLRP6炎症小体广泛分布于肠道组织中,可识别肠道内多种危险信号,进而与众多下游信号通路关联,调控肠道内微生物组成和肠道黏膜屏障,从而调控疾病进展。此外,肠道微生物菌群或其代谢产物可直接激活NLRP6炎症小体,也可通过肠-肝循环刺激肝脏内NLRP6炎症小体,对维持肠道微生态平衡及宿主-微生物相互作用至关重要。基于NLRP6炎症小体与肠道微生态之间的相互调控机制,靶向NLRP6炎症小体调节肠道微生态失衡,成为与肠道微生态失衡相关疾病治疗的新思路。文章就NLRP6炎症小体的组成、分布与激活,NLRP6炎症小体与肠道微生物、代谢产物、肠道黏膜屏障相互调控机制进行综述,为临床治疗肠道微生态失衡相关疾病提供更多研究思路。     

Vascular endothelial cells senescence is associated with NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation via reactive oxygen species (ROS)/thioredoxin-interacting protein (TXNIP) pathway

Endothelial dysfunction caused by endothelial cells senescence and chronic inflammation is tightly linked to the development of cardiovascular diseases. NLRP3 (NOD-like receptor family pyrin domain-containing3) inflammasome plays a central role in inflammatory response that is associated with diverse inflammatory diseases. This study explores the effects and possible mechanisms of NLRP3 inflammasome in endothelial cells senescence. Results show an increment of pro-inflammatory cytokine interleukin (IL) −1β secretion and caspase-1 activation during the senescence of endothelial cells induced by bleomycin. Moreover, secreted IL-1β promoted endothelial cells senescence through up-regulation of p53/p21 protein expression. NLRP3 inflammasome was found to mediate IL-1β secretion through the production of ROS (reactive oxygen species) during the senescence of endothelial cells. Furthermore, the association of TXNIP (thioredoxin-interacting protein) with NLRP3 induced by ROS promoted NLRP3 inflammasome activation in senescent endothelial cells. In addition, the expressions of NLRP3 inflammasome related genes, ASC (apoptosis associated speck-like protein containing a CARD), TXNIP, cleaved caspase-1 and IL-1β, were also increased in vitro and in vivo studies. These findings indicate that endothelial senescence could be mediated through ROS and NLRP3 inflammasome signaling pathways, suggesting a potential target for the prevention of endothelial senescence-related cardiovascular diseases.     

Tripartite-motif protein 30 negatively regulates NLRP3 inflammasome activation by modulating reactive oxygen species production

The NLR family, pyrin domain-containing 3 (NLRP3) inflammasome is critical for caspase-1 activation and the proteolytic processing of pro-IL-1β. However, the mechanism that regulates NLRP3 inflammasome activation remains unclear. In this paper, we demonstrate that tripartite-motif protein 30 (TRIM30) negatively regulates NLRP3 inflammasome activation. After stimulation with ATP, an agonist of the NLRP3 inflammasome, knockdown of TRIM30 enhanced caspase-1 activation and increased production of IL-1β in both J774 cells and bone marrow-derived macrophages. Similarly with ATP, knockdown of TRIM30 increased caspase-1 activation and IL-1β production triggered by other NLRP3 inflammasome agonists, including nigericin, monosodium urate, and silica. Production of reactive oxygen species was increased in TRIM30 knockdown cells, and its increase was required for enhanced NLRP3 inflammasome activation, because antioxidant treatment blocked excess IL-1β production. Conversely, overexpression of TRIM30 attenuated reactive oxygen species production and NLRP3 inflammasome activation. Finally, in a crystal-induced NLRP3 inflammasome-dependent peritonitis model, monosodium urate-induced neutrophil flux and IL-1β production was reduced significantly in TRIM30 transgenic mice as compared with that in their nontransgenic littermates. Taken together, our results indicate that TRIM30 is a negative regulator of NLRP3 inflammasome activation and provide insights into the role of TRIM30 in maintaining inflammatory responses.     

自噬与NLRP3炎症小体激活间的相互作用

自噬作为真核生物细胞遭遇各种应激压力时发生的一种基本应答方式,参与细胞的多种生命活动,使细胞在各种应激条件下维持一种动态平衡状态。NOD样受体家族核苷酸结合寡聚化结构域样受体3（NOD-like receptor family,pyrin domain containing 3,NLRP3）炎症小体,是生物体内防御病原微生物的固有免疫防御系统的重要组成部分。NLRP3炎症小体通过激活胱天蛋白酶-1（caspase-1）,从而促进白细胞介素-1β（interleukin-1,IL-1β）和白细胞介素-18（interleukin-18,IL-18）等促炎细胞因子的成熟和分泌,继而介导炎症的发生。众多研究表明,自噬能够负向或正向调控NLRP3炎症小体的激活。同时,NLRP3炎症小体也会逆向影响自噬的作用。本文对自噬包括选择性自噬与NLRP3炎症小体激活的相互作用,以及通过激活自噬抑制NLRP3炎症小体,从而在炎症相关疾病治疗中的应用进行综述。     

Zinc depletion regulates the processing and secretion of IL-1β

Sterile inflammation contributes to many common and serious human diseases. The pro-inflammatory cytokine interleukin-1β (IL-1β) drives sterile inflammatory responses and is thus a very attractive therapeutic target. Activation of IL-1β in sterile diseases commonly requires an intracellular multi-protein complex called the NLRP3 (NACHT, LRR, and PYD domains-containing protein 3) inflammasome. A number of disease-associated danger molecules are known to activate the NLRP3 inflammasome. We show here that depletion of zinc from macrophages, a paradigm for zinc deficiency, also activates the NLRP3 inflammasome and induces IL-1β secretion. Our data suggest that zinc depletion damages the integrity of lysosomes and that this event is important for NLRP3 activation. These data provide new mechanistic insight to how zinc deficiency contributes to inflammation and further unravel the mechanisms of NLRP3 inflammasome activation.     

TRPV1 channel mediates NLRP3 inflammasome-dependent neuroinflammation in microglia

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease in the central nervous system (CNS). The NLRP3 inflammasome is considered an important regulator of immunity and inflammation, both of which play a critical role in MS. However, the underlying mechanism of NLRP3 inflammasome activation is not fully understood. Here we identified that the TRPV1 (transient receptor potential vanilloid type 1) channel in microglia, as a Ca²⁺ influx-regulating channel, played an important role in NLRP3 inflammasome activation. Deletion or pharmacological blockade of TRPV1 inhibited NLRP3 inflammasome activation in microglia in vitro. Further research revealed that TRPV1 channel regulated ATP-induced NLRP3 inflammasome activation through mediating Ca²⁺ influx and phosphorylation of phosphatase PP2A in microglia. In addition, TRPV1 deletion could alleviate mice experimental autoimmune encephalomyelitis (EAE) and reduce neuroinflammation by inhibiting NLRP3 inflammasome activation. These data suggested that the TRPV1 channel in microglia can regulate NLRP3 inflammasome activation and consequently mediate neuroinflammation. Meanwhile, our study indicated that TRPV1–Ca²⁺–PP2A pathway may be a novel regulator of NLRP3 inflammasome activation, pointing to TRPV1 as a potential target for CNS inflammatory diseases.Subject terms: Neuroimmunology, Neuroimmunology     

Suppression of ribosomal function triggers innate immune signaling through activation of the NLRP3 inflammasome

Some inflammatory stimuli trigger activation of the NLRP3 inflammasome by inducing efflux of cellular potassium. Loss of cellular potassium is known to potently suppress protein synthesis, leading us to test whether the inhibition of protein synthesis itself serves as an activating signal for the NLRP3 inflammasome. Murine bone marrow-derived macrophages, either primed by LPS or unprimed, were exposed to a panel of inhibitors of ribosomal function: ricin, cycloheximide, puromycin, pactamycin, and anisomycin. Macrophages were also exposed to nigericin, ATP, monosodium urate (MSU), and poly I:C. Synthesis of pro-IL-? and release of IL-1? from cells in response to these agents was detected by immunoblotting and ELISA. Release of intracellular potassium was measured by mass spectrometry. Inhibition of translation by each of the tested translation inhibitors led to processing of IL-1?, which was released from cells. Processing and release of IL-1? was reduced or absent from cells deficient in NLRP3, ASC, or caspase-1, demonstrating the role of the NLRP3 inflammasome. Despite the inability of these inhibitors to trigger efflux of intracellular potassium, the addition of high extracellular potassium suppressed activation of the NLRP3 inflammasome. MSU and double-stranded RNA, which are known to activate the NLRP3 inflammasome, also substantially inhibited protein translation, supporting a close association between inhibition of translation and inflammasome activation. These data demonstrate that translational inhibition itself constitutes a heretofore-unrecognized mechanism underlying IL-1? dependent inflammatory signaling and that other physical, chemical, or pathogen-associated agents that impair translation may lead to IL-1?-dependent inflammation through activation of the NLRP3 inflammasome. For agents that inhibit translation through decreased cellular potassium, the application of high extracellular potassium restores protein translation and suppresses activation of the NLRP inflammasome. For agents that inhibit translation through mechanisms that do not involve loss of potassium, high extracellular potassium suppresses IL-1? processing through a mechanism that remains undefined.     

Activated human CD4+CD45RO+ memory T-cells indirectly inhibit NLRP3 inflammasome activation through downregulation of P2X7R signalling

Inflammasomes are multi-protein complexes that control the production of pro-inflammatory cytokines such as IL-1β. Inflammasomes play an important role in the control of immunity to tumors and infections, and also in autoimmune diseases, but the mechanisms controlling the activation of human inflammasomes are largely unknown. We found that human activated CD4+CD45RO+ memory T-cells specifically suppress P2X7R-mediated NLRP3 inflammasome activation, without affecting P2X7R-independent NLRP3 or NLRP1 inflammasome activation. The concomitant increase in pro-IL-1β production induced by activated memory T-cells concealed this effect. Priming with IFNβ decreased pro-IL-1β production in addition to NLRP3 inflammasome inhibition and thus unmasked the inhibitory effect on NLRP3 inflammasome activation. IFNβ suppresses NLRP3 inflammasome activation through an indirect mechanism involving decreased P2X7R signaling. The inhibition of pro-IL-1β production and suppression of NLRP3 inflammasome activation by IFNβ-primed human CD4+CD45RO+ memory T-cells is partly mediated by soluble FasL and is associated with down-regulated P2X7R mRNA expression and reduced response to ATP in monocytes. CD4+CD45RO+ memory T-cells from multiple sclerosis (MS) patients showed a reduced ability to suppress NLRP3 inflammasome activation, however their suppressive ability was recovered following in vivo treatment with IFNβ. Thus, our data demonstrate that human P2X7R-mediated NLRP3 inflammasome activation is regulated by activated CD4+CD45RO+ memory T cells, and provide new information on the mechanisms mediating the therapeutic effects of IFNβ in MS.     

TLR2/MyD88/NF-κB pathway, reactive oxygen species, potassium efflux activates NLRP3/ASC inflammasome during respiratory syncytial virus infection

Human respiratory syncytial virus (RSV) constitute highly pathogenic virus that cause severe respiratory diseases in newborn, children, elderly and immuno-compromised individuals. Airway inflammation is a critical regulator of disease outcome in RSV infected hosts. Although "controlled" inflammation is required for virus clearance, aberrant and exaggerated inflammation during RSV infection results in development of inflammatory diseases like pneumonia and bronchiolitis. Interleukin-1β (IL-1β) plays an important role in inflammation by orchestrating the pro-inflammatory response. IL-1β is synthesized as an immature pro-IL-1β form. It is cleaved by activated caspase-1 to yield mature IL-1β that is secreted extracellularly. Activation of caspase-1 is mediated by a multi-protein complex known as the inflammasome. Although RSV infection results in IL-1β release, the mechanism is unknown. Here in, we have characterized the mechanism of IL-1β secretion following RSV infection. Our study revealed that NLRP3/ASC inflammasome activation is crucial for IL-1β production during RSV infection. Further studies illustrated that prior to inflammasome formation; the "first signal" constitutes activation of toll-like receptor-2 (TLR2)/MyD88/NF-κB pathway. TLR2/MyD88/NF-κB signaling is required for pro-IL-1β and NLRP3 gene expression during RSV infection. Following expression of these genes, two "second signals" are essential for triggering inflammasome activation. Intracellular reactive oxygen species (ROS) and potassium (K(+)) efflux due to stimulation of ATP-sensitive ion channel promote inflammasome activation following RSV infection. Thus, our studies have underscored the requirement of TLR2/MyD88/NF-κB pathway (first signal) and ROS/potassium efflux (second signal) for NLRP3/ASC inflammasome formation, leading to caspase-1 activation and subsequent IL-1β release during RSV infection.     

Suppression of lncRNA NLRP3 inhibits NLRP3-triggered inflammatory responses in early acute lung injury

Acute lung injury (ALI) is a common lung pathology that is accompanied by alveolar macrophage (AM) activation and inflammatory response. This study investigated the role of the long non-coding RNA NONRATT004344 (hereafter named lncRNA NLRP3) in regulating the Nod-like receptor protein 3 (NLRP3)-triggered inflammatory response in early ALI and the underlying mechanism as well. We established LPS-induced ALI models to explore their interactive mechanisms in vitro and in vivo. Luciferase reporter assays were performed to determine that miR-138-5p could bind to lncRNA NLRP3 and NLRP3. We observed increased lncRNA NLRP3 expression, decreased miR-138-5p expression, NLRP3 inflammasome activation, and upregulated caspase-1, IL-1β, and IL-18 expression in the LPS-induced ALI model. Furthermore, lncRNA NLRP3 overexpression activated the NLRP3 inflammasome and promoted IL-1β and IL-18 secretion; the miR-138-5p mimic abolished these effects in vivo and in vitro. Consistently, miR-138-5p inhibition reversed the effects of lncRNA NLRP3 silencing on the expression of NLRP3-related molecules and inhibition of the NLRP3/caspase-1/IL-1β signalling pathway. Mechanistically, lncRNA NLRP3 sponging miR-138-5p facilitated NLRP3 activation through a competitive endogenous RNA (ceRNA) mechanism. In summary, our results suggested that lncRNA NLRP3 binding miR-138-5p promotes NLRP3-triggered inflammatory response via lncRNA NLRP3/miR-138-5p/NLRP3 ceRNA network (ceRNET) and provides insights into the treatment of early ALI.Subject terms: Bacterial infection, Inflammasome