NLRP7: From inflammasome regulation to human disease

Nucleotide‐binding oligomerization domain (NOD) and leucine‐rich repeat (LRR)‐containing receptors or NOD‐like receptors (NLRs) are cytosolic pattern recognition receptors, which sense conserved microbial patterns and host‐derived danger signals to elicit innate immune responses. The activation of several prototypic NLRs, including NLR and pyrin domain (PYD) containing (NLRP) 1, NLRP3 and NLR and caspase recruitment domain (CARD) containing (NLRC) 4, results in the assembly of inflammasomes, which are large, cytoplasmic multiprotein signalling platforms responsible for the maturation and release of the pro‐inflammatory cytokines IL‐1β and IL‐18, and for the induction of a specialized form of inflammatory cell death called pyroptosis. However, the function of other members of the NLR family, including NLRP7, are less well understood. NLRP7 has been linked to innate immune signalling, but its precise role is still controversial as it has been shown to positively and negatively affect inflammasome responses. Inflammasomes are essential for homeostasis and host defence, but inappropriate inflammasome responses due to hereditary mutations and somatic mosaicism in inflammasome components and defective regulation have been linked to a broad spectrum of human diseases. A compelling connection between NLRP7 mutations and reproductive diseases, and in particular molar pregnancy, has been established. However, the molecular mechanisms by which NLRP7 mutations contribute to reproductive diseases are largely unknown. In this review, we focus on NLRP7 and discuss the current evidence of its role in inflammasome regulation and its implication in human reproductive diseases.     

TRPV4 Regulates Soman-Induced Status Epilepticus and Secondary Brain Injury via NMDA Receptor and NLRP3 Inflammasome

Nerve agents are used in civil wars and terrorist attacks, posing a threat to public safety. Acute exposure to nerve agents such as soman (GD) causes serious brain damage, leading to death due to intense seizures induced by acetylcholinesterase inhibition and neuronal injury resulting from increased excitatory amino-acid levels and neuroinflammation. However, data on the anticonvulsant and neuroprotective efficacies of currently-used countermeasures are limited. Here, we evaluated the potential effects of transient receptor vanilloid 4 (TRPV4) in the treatment of soman-induced status epilepticus (SE) and secondary brain injury. We demonstrated that TRPV4 expression was markedly up-regulated in rat hippocampus after soman-induced seizures. Administration of the TRPV4 antagonist GSK2193874 prior to soman exposure significantly decreased the mortality rate in rats and reduced SE intensity. TRPV4-knockout mice also showed lower incidence of seizures and higher survival rates than wild-type mice following soman exposure. Further in vivo and in vitro experiments demonstrated that blocking TRPV4 prevented NMDA receptor-mediated glutamate excitotoxicity. The protein levels of the NLRP3 inflammasome complex and its downstream cytokines IL-1β and IL-18 increased in soman-exposed rat hippocampus. However, TRPV4 inhibition or deletion markedly reversed the activation of the NLRP3 inflammasome pathway. In conclusion, our study suggests that the blockade of TRPV4 protects against soman exposure and reduces brain injury following SE by decreasing NMDA receptor-mediated excitotoxicity and NLRP3-mediated neuroinflammation. To our knowledge, this is the first study regarding the “dual-switch” function of TRPV4 in the treatment of soman intoxication.Electronic supplementary materialThe online version of this article (10.1007/s12264-021-00662-3) contains supplementary material, which is available to authorized users.     

胃饥饿素对高糖下人视网膜血管内皮细胞的保护作用及机制

目的：探讨胃饥饿素(ghrelin)对高糖下的人视网膜血管内皮细胞的保护作用及机制。

方法：以人视网膜血管内皮细胞为研究对象,建立高糖损伤模型。胃饥饿素处理细胞后,采用CCK-8试剂盒检测不同浓度胃饥饿素对高糖下细胞增殖的影响,以筛选最佳浓度。将细胞分为正常对照组(NC)、胃饥饿素组(ghrelin)、高糖组(HG)和胃饥饿素+高糖组(ghrelin+HG)。采用CCK-8试剂盒检测细胞增殖,Annexin-APC/7-AAD试剂盒检测细胞凋亡,蛋白质印迹法检测细胞NLRP3、Caspase-1、IL-1β及IL-18的表达。

结果：与NC组(100.00%±0.00%)相比,HG组细胞增殖率(69.87%±0.68%,P<0.05)明显下降。与HG组相比,ghrelin+HG组细胞增殖率(92.31%±3.62%,P<0.05)明显升高。与NC组(4.94%±0.15%)相比,HG组细胞凋亡率(28.33%±1.37%,P<0.05)明显升高。与HG组相比,ghrelin+HG组细胞凋亡率(14.24%±0.32%,P<0.05)明显降低。与NC组相比,HG组细胞表达NLRP3、Caspase-1、IL-1β及IL-18蛋白均明显升高(均P<0.05)。与HG组相比,ghrelin+HG组细胞表达NLRP3、Caspase-1、IL-1β及IL-18蛋白均明显下降(均P<0.05)。

结论：胃饥饿素能对高糖损伤的视网膜血管内皮细胞起到保护作用,可能是通过抑制NLRP3炎症小体信号通路发挥其功能。     

NLRP3基因敲除小鼠的繁殖与基因型鉴定

目的 繁殖及鉴定NLRP3基因敲除（NLRP3^-/-）小鼠。方法 将引进的NLRP3基因敲除杂合子小鼠,单独进行饲养及配种繁殖,繁殖后其子代出现3种基因型：野生型、杂合子型及纯合子型,提取每只小鼠的基因组DNA,用PCR和T7E1酶切方法进行鉴定,将获得的纯合子小鼠与异性杂合子交配,以获得更多的基因敲除纯合子小鼠。结果 NLRP3杂合子小鼠的饲养及繁殖均获得成功,获得了NLRP3基因敲除纯合子和杂合子小鼠。结论 正确的饲养、繁殖及鉴定方法是从NLRP3基因敲除杂合子小鼠中获得纯合子小鼠的有效途径。     

鼠神经生长因子联合丹参川芎嗪注射液对缺氧缺血性脑病新生儿氧化应激及炎症因子水平的影响

目的探讨鼠神经生长因子联合丹参川芎嗪注射液对缺氧缺血性脑病新生儿氧化应激及炎症因子水平的影响。方法将98例缺氧缺血性脑病新生儿按随机数字表法分为两组,每组49例。两组新生儿均给予常规对症治疗,在此基础上,对照组给予鼠神经生长因子治疗,观察组给予鼠神经生长因子联合丹参川芎嗪注射液治疗。观察2周。比较两组临床疗效及不良反应发生率,统计治疗前后两组新生儿意识障碍、原始反射和肌张力恢复时间。治疗前后,应用酶联免疫吸附法检测血清白细胞介素-1β、白细胞介素-6、白细胞介素-18水平,应用高通量逆转录实时荧光定量测定Nod样受体蛋白3、凋亡相关斑点样蛋白、半胱氨酸天冬氨酸特异蛋白酶mRNA水平。结果观察组临床疗效显著优于对照组(P<0.05)。观察组新生儿意识障碍、原始反射和肌张力恢复时间显著短于对照组(P<0.01),白细胞介素-1β、白细胞介素-6、白细胞介素-18水平以及Nod样受体蛋白3、凋亡相关斑点样蛋白、半胱氨酸天冬氨酸特异蛋白酶mRNA水平显著低于对照组(P<0.01)。两组不良反应发生率比较差异无统计学意义(P>0.05)。结论鼠神经生长因子联合丹参川芎嗪注射液治疗新生儿缺氧缺血性脑病临床疗效明显,能更好地调节患儿白细胞介素-1β、白细胞介素-6、白细胞介素-18以及Nod样受体蛋白3、凋亡相关斑点样蛋白、半胱氨酸天冬氨酸特异蛋白酶mRNA水平。     

RRx-001 ameliorates inflammatory diseases by acting as a potent covalent NLRP3 inhibitor

The NLRP3 inflammasome plays a crucial role in innate immune-mediated inflammation and contributes to the pathogenesis of multiple autoinflammatory, metabolic and neurodegenerative diseases, but medications targeting the NLRP3 inflammasome are not available for clinical use. RRx-001 is a well-tolerated anticancer agent currently being investigated in phase III clinical trials, but its effects on inflammatory diseases are not known. Here, we show that RRx-001 is a highly selective and potent NLRP3 inhibitor that has strong beneficial effects on NLRP3-driven inflammatory diseases. RRx-001 inhibits the activation of the canonical, noncanonical, and alternative NLRP3 inflammasomes but not the AIM2, NLRC4 or Pyrin inflammasomes. Mechanistically, RRx-001 covalently binds to cysteine 409 of NLRP3 via its bromoacetyl group and therefore blocks the NLRP3-NEK7 interaction, which is critical for the assembly and activation of the NLRP3 inflammasome. More importantly, RRx-001 treatment attenuates the symptoms of lipopolysaccharide (LPS)-induced systemic inflammation, dextran sulfate sodium (DSS)-induced colitis and experimental autoimmune encephalomyelitis (EAE) in mice. Thus, our study identifies RRx-001 as a new potential therapeutic agent for NLRP3-driven diseases.     

补中益气丸治疗腹泻型肠易激综合征的疗效及其对NLRP3炎症小体的影响

【】目的：观察补中益气丸治疗腹泻型肠易激综合征(IBS-D)的临床疗效及其对外周血中NOD样受体-3(NLRP3)炎性小体及其下游炎症因子白细胞介素-1β(IL-1β)、白细胞介素-18(IL-18)的影响。方法：入选IBS-D患者80例,随机分为2组,各40例。对照组给予马来酸曲美布汀片 0.1g tid。观察组给予补中益气丸 6 g tid。疗程均为4周。观察2组患者的临床疗效,同时检测患者外周血中NLRP3、IL-1β、IL-18的表达。结果：经治疗后,观察组的临床有效率(92.5%)明显优于对照组(72.5%),差异有统计学意义(P<0.05)。观察组外周血中NLRP3、IL-1β、IL-18的表达水平(72.58±10.24、33.75±8.49、81.75±10.43)较对照组明显减低(91.56±10.34、51.26±8.72、101.62±20.35),差异有统计学意义(P<0.05)。结论：补中益气丸治疗IBS-D具有良好的临床效果,其作用机制可能与下调NLRP3炎症小体及其下游炎症因子的表达有关。     

孙鲜策：NOD样受体蛋白亚家族在非酒精性脂肪性肝病发生和进展中的作用

NOD样受体蛋白亚家族（NOD-like receptor proteins,NLRPs）参与机体的固有免疫反应,可受上游信号调控而激活,导致炎症性细胞死亡,即细胞焦亡（pyroptosis）。近年来研究表明,NLRPs炎症小体激活引发的炎症应答与非酒精性脂肪性肝病（nonalcoholic fatty liver disease,NAFLD）的发生发展密切相关,本文对NLRPs炎症小体在NAFLD的发生和疾病进展中的作用进行综述。     

miR-122-5p调节创伤性脑外伤后小胶质细胞极化减弱炎症反应北大核心CSCD

目的探讨miR-122-5p对创伤性脑外伤后小胶质细胞凋亡、极化和炎症反应的影响。方法建立创伤性脑外伤(traumatic brain injury,TBI)小鼠模型和细胞模型。使用TBI小鼠脑匀浆刺激星型胶质细胞产生外泌体,microRNA微阵列分析外泌体中显著改变的microRNA。实时荧光定量PCR检测TBI小鼠模型和TBI细胞模型中miR-122-5p表达。使用TUNEL凋亡染色、免疫荧光共聚焦、蛋白质印迹研究miR-122-5p抑制剂在TBI神经炎症中对小胶质细胞凋亡、小胶质细胞M1/M2表型转化、NLRP3通路及NFκB磷酸化的作用。结果通过microRNA微阵列分析发现有83个下调miRNA(改变2倍以上,P<0.05),其中miR-122-5p显著下调(P<0.01),miR-122-5p在TBI小鼠及细胞模型中表达显著下降[(1.0±0.00)vs.(0.41±0.15),P<0.001];[(1.0±0.00)vs.(0.34±0.07),P<0.001]。TUNEL凋亡检测、免疫荧光染色结果表明抑制miR-122-5p表达,可以显著减轻LPS诱导的小胶质细胞凋亡[(8.03±1.30)vs.(3.17±0.34),P<0.001],促进小胶质细胞M1向M2表型转化,即M1表型极化减少[(56.96±13.70)vs.(34.70±3.47),P=0.002],M2表型极化增加[(30.46±3.67)vs.(40.74±2.49),P=0.005]。蛋白质印迹结果表明miR-122-5p抑制剂降低NLRP3炎症小体活化[(0.77±0.10)vs.(0.51±0.11),P=0.02],降低NFκB的磷酸化[(0.73±0.08)vs.(0.50±0.07),P=0.003]。结论miR-122-5p在TBI星形胶质细胞分泌的外泌体及小胶质细胞中表达下调,miR-122-5p抑制剂可以通过抑制TBI后NLRP3炎症小体通路的活化及NFκB的磷酸化,促进小胶质细胞M1向M2表型转化,减少小胶质细胞凋亡,从而减轻TBI后小胶质细胞炎症损伤。