1、 1.引言2.NLRP3炎性小體3.NLRP3與IBD 4.總結1.引言IBDPAMPs/DAMPs與PRRs(TLRs/NLRs)NF-B通路炎性小體(*NLRs/ASC/Caspase/AIM2) NLRP3 炎性小體的活化可致無活性的caspase-1 前體轉化為活性caspase-1，后者可裂解白細胞介素（IL-1）、IL-18、IL-33 前體以形成活性形式并分泌。NLRP3 已證實與人類多種自身免疫病相關，如家族性寒冷自身炎癥綜合征（familial cold utoinflammatory syndrome,FCAS）、穆-韋綜合征（Muckle-Wells syndrome，M

2、WS）和新生兒期多系統炎癥綜合征（neonatal onset ultisystem inflammatory disease, NOMID）， 上述疾病統稱為隱熱蛋白-相關周期綜合征（cryopyrin associated periodic syndrome, CAPS）。 NLRs N-terminal 效應區 含有一個熱蛋白結構域(PYD), caspase招募結構域(CARD), 或一個桿狀病毒凋亡抑制重復結構域(BIR),NLRs亞類的分類依據（NLRA/NLRB/NLRC/NLRP/NLRX）。 Central 核苷酸結合寡聚化結構域(NACHT），是各種NLRs的共同特征。 C

3、-terminus 亮氨酸重復區(LRR) 2.NLRP3 InflamasomedistributionStructureMechanisms of its activationSignal1:PrimingSignal2:ActivationInhibitionfunction 分布NLRP3 在中性粒細胞、單核細胞、淋巴細胞、樹突細胞、成骨細胞、上皮細胞（口咽部、食管、外宮頸、尿道）、皮膚角質形成細胞等均有表達。Figure 1. Schematic of NLRP1, NLRP3, NLRC4, and AIM2 inflammasomes. Human NLRP1 can inter

4、act with ASC and caspase-1 via an N-terminal PYD and also bind caspase-5 to the complex via the C-terminal CARD. Muramyl dipeptide (MDP), Bacillus anthracis lethal toxin, and Toxoplasma gondii can induce the activation of the NLRP1 inflammasome. Mouse Nlrp1b does not possess a functional N-terminal

5、PYD, hence caspase-1 may interact with its C-terminal CARD. NLRP3 interacts with ASC through an N-terminal PYD domain, which then recruits caspase-1.Mitochondrial DNA (mtDNA) and cardiolipin have been postulated to bind to NLRP3 and induce its activation., nucleotide-binding and oligomerization doma

6、in.structure激活劑NLRP3炎癥小體是目前研究最為深人的一種炎癥小體, 可被多種病原體及其成分或產物激活,如金黃色葡萄球菌、李斯特菌、白色念珠菌、釀酒酵母菌、仙臺病毒、細菌RNA 、尼利亞菌素等;內源性損傷信號或環境致病因子, 如胞外ATP 、尿酸鈉晶體、二氧化硅、紫外線等亦可激活NLRP3炎癥小體。Figure2. Signals mediating NLRP3 inflammasome priming.Upon engagement, patternrecognition receptors (PRR), such as TLR4 and NOD2, or cytokine r

7、eceptors, such as TNFR and IL-1R, activate NF-B, leading to the transcription and translation of NLRP3 and pro-IL-1. Dissociation of HSP90 and SGT1 from NLRP3 is required for NLRP3 inflammasome activation. Additionally, NLRP3 undergoes deubiquitylation by the JAMM domaincontaining Zn2+ metalloprotea

8、se deubiquitinating enzyme BRCC3,which is crucial for subsequent NLRP3 inflammasome activation. Upon activation of the NLRP3 inflammasome, active caspase-1 can process pro-IL-1 and pro-IL-18 into their mature secreted forms.Signal1:primingFigure 3. Inhibition of NLRP3 inflammasome activation. Type I

9、 IFNs acting through IFNAR inhibit the transcription of pro-IL-1 through the upregulation of the anti-inflammatory cytokine IL-10. Type I IFNs and IFN- inhibit NLRP3 through the production of nitric oxide (NO) via the inducible nitric oxide synthase (iNOS), resulting in nitrosylation of NLRP3. Inter

10、action of mature or memory T cells with macrophages via CD40CD40L results in inhibition of the NLRP3 inflammasome. Elevation of cellular cAMP levels also results in the inhibition of NLRP3. The microRNA miR-223 regulates the amount of NLRP3 mRNA and, consequently, NLRP3 expression.inhibitionSignal2:

11、activationFigure 4. Regulation of NLRP3 inflammasome activation in response to ion fluxes and mitochondrial dysfunction. K+ efflux is required for NLRP3 inflammasome activation and is achieved either directly by bacterial pore-forming toxins, such as nigericin,or indirectly via receptors such as the

12、 purinergic receptor for ATP, P2X7R. During the regulatory volume decrease response to cell swelling, Ca2+ fluxes can be regulated by the transient receptor potential receptors TRPM7 and TRPV2. Ca2+ influx can also be mediated via the ROS-sensitive TRPM2.可能的激活機制ATP-依賴的鉀離子外流線粒體功能障礙ROS溶酶體破裂核糖體功能障礙3.NL

13、RP3炎性小體與IBD(1)CD遺傳易感性 2001 年，McGovern等發現了CD 的第一個易感基因NOD2/CARD15，因NLRP3和NOD2 蛋白同屬NLR 家族成員，由此提示NLRP3 亦可能與CD 相關。 對瑞典人的研究發現NLRP3炎癥小體組分N LRP3、CARDS8基因多態性與NOD2 等位基因為野生型的男性的CD 易感性相關;對加拿大歐洲后裔的研究發現位于NLRP3 基因下游調控區的一組SN Ps 與C D易感性相關,但該相關性未能在英聯邦人群中被復制 ,表明此種相關性受地域和遺傳背景的影響。(2)IBD小鼠的相關研究 今年有研究發現NLRP3炎癥小體組分缺陷(NLRP3

14、 -/-或ASC-/-或Caspase-1-/-)小鼠對葡聚糖硫酸鈉( DSS)或三硝基苯磺酸（TNBS）誘導的結腸炎更為易感。給予重組IL-18可使caspase-1缺陷小鼠的重量減輕明顯緩解,表明NLRP3炎癥小體通過IL-18 對實驗性結腸炎發揮保護作用, 發揮作用的主要是腸上皮細胞中的NLR P3 炎癥小體。 然而亦有研究發現NLRP3 -/ -小鼠對DS 誘導的結腸炎耐受, 其機制可能與結腸促炎細胞因子IL-1、IL-18 、腫瘤壞死因子-(TNF- )等產生減少有關。 實驗結果的不一致性可能是由實驗小鼠的遺傳背景，腸道菌群組成以及實驗干預方案不同所引起。(3)材料與方法 Wild-

15、type mice and mice deficient in NLRP3, ASC, caspase 1, interleukin-1(IL-1), IL-1 receptor type I (IL-1RI), IL-18R, myeloid differentiation factor 88 (MyD88), or 5-LOX were used. neutrophil influx,LTB4 activity, cytokine (IL-1, CXCL1) production (by enzyme-linked immunosorbent assay), synovial microv

16、asculature cell adhesion (by intravital microscopy). Cleaved caspase 1 and production of reactive oxygen species (ROS) were analyzed in macrophages by Western blotting and fluorometric assay,respectively.4.總結雖然對NLRP3炎性小體的研究非常廣泛，但不夠深入。炎性小體組裝的激活信號通路還不清楚，如細胞鉀離子外流如何激活炎性體，線粒體如何發揮作用。目前，NLRP3炎性體與腸道炎癥的研究很少，

17、炎性體信號通路參與包括IBD在內的一些炎癥性疾病，可作為治療IBD的藥物靶點，對其研究有助于發現新型的治療藥物。參考文獻1.Allen IC,TeKippe M,Woodford RM,et al.The NLRP3 inflamasome funtions as a negative regulator of tumorigenesis during colitis-assocaited cancer J . J Exp Med,2010,207(5):1045-10562.Zaki MH,Boyd KL,Vogel P,et al.The NLRP3 inflamasome protects against loss of epithelial integrity and mortality during experimen