Giamarellos-Bourboulis E J, Mouktaroudi M, Bodar E, van der Ven J, Kullberg B-J, Netea M G, van der Meer J W M
Department of Internal Medicine, University Medical Centre St Radboud, Nijmegen, The Netherlands.
Ann Rheum Dis. 2009 Feb;68(2):273-8. doi: 10.1136/ard.2007.082222. Epub 2008 Apr 4.
Recent studies suggest that crystals of monosodium urate (MSU), deposited in joints of patients with acute gouty arthritis, activate the NACHT domain, leucine-rich repeat and pyrin domain-containing protein (NALP)3 inflammasome. In the present study we have investigated whether production of proinflammatory cytokines by crystals was exacerbated during costimulation with Toll-like receptor (TLR) ligands.
Mononuclear cells of 22 healthy donors were stimulated by various concentrations of MSU crystals in the absence or presence of lipopolysaccharide (LPS), Pam3Cys and flagellin. Production of tumour necrosis factor alpha (TNFalpha), interleukin (IL)1 beta and IL6, as well as the intracellular concentrations of proIL1 beta were measured by ELISA. mRNA transcripts of TNFalpha and IL1 beta were assessed by real-time PCR. Stimulation experiments were also performed with peripheral blood mononuclear cells (PBMCs) of one patient carrying a NALP3 mutation.
MSU induced a moderate release of IL1 beta and IL6, but not of TNFalpha. Urate crystals amplified IL1 beta production stimulated by the TLR4 ligand LPS, while no synergy was apparent for IL6 production. In addition, no synergy between urate crystals and Pam3Cys (TLR2 ligand) or flagellin (TLR5 ligand) was apparent. The synergy between urate crystals and LPS was directed at the level of the NALP3 inflammasome, as it was present only when active IL1 beta was measured, but not at the level of IL1 mRNA or proIL1 beta. The synergy between LPS and MSU crystals ceased to exist in the presence of a caspase 1 inhibitor.
MSU crystals act in synergy with LPS for the induction of enhanced release of IL1 beta. Increased cleavage of proIL1 beta by urate-activated caspase 1 is proposed as the underlying mechanism.
近期研究表明，沉积于急性痛风性关节炎患者关节中的尿酸单钠（MSU）晶体可激活含NACHT结构域、富含亮氨酸重复序列和pyrin结构域的蛋白（NALP）3炎性小体。在本研究中，我们调查了在与Toll样受体（TLR）配体共刺激期间，晶体诱导的促炎细胞因子产生是否会加剧。
在不存在或存在脂多糖（LPS）、Pam3Cys和鞭毛蛋白的情况下，用不同浓度的MSU晶体刺激22名健康供体的单核细胞。通过酶联免疫吸附测定法（ELISA）测量肿瘤坏死因子α（TNFα）、白细胞介素（IL）-1β和IL-6的产生，以及前IL-1β的细胞内浓度。通过实时聚合酶链反应（PCR）评估TNFα和IL-1β的信使核糖核酸（mRNA）转录本。还对一名携带NALP3突变的患者的外周血单核细胞（PBMC）进行了刺激实验。
MSU诱导IL-1β和IL-6适度释放，但不诱导TNFα释放。尿酸盐晶体增强了由TLR4配体LPS刺激的IL-1β产生，而对于IL-6产生未观察到协同作用。此外，尿酸盐晶体与Pam3Cys（TLR2配体）或鞭毛蛋白（TLR5配体）之间未观察到协同作用。尿酸盐晶体与LPS之间的协同作用针对NALP3炎性小体水平，因为仅在测量活性IL-1β时存在，而在IL-1 mRNA或前IL-1β水平不存在。在存在半胱天冬酶1抑制剂的情况下，LPS与MSU晶体之间的协同作用消失。
MSU晶体与LPS协同作用以诱导增强的IL-1β释放。尿酸盐激活的半胱天冬酶1增加前IL-1β的切割被认为是潜在机制。
