Medizinische Klinik Innenstadt, University of Munich, Ziemssenstr. 1, D-80336 Munich, Germany.
Gut. 2010 Sep;59(9):1192-9. doi: 10.1136/gut.2009.197822. Epub 2010 May 4.
The proinflammatory cytokines interleukin 1beta (IL-1beta) and IL-18 are central players in the pathogenesis of inflammatory bowel disease (IBD). In response to a variety of microbial components and crystalline substances, both cytokines are processed via the caspase-1-activating multiprotein complex, the NLRP3 inflammasome. Here, the role of the NLRP3 inflammasome in experimental colitis induced by dextran sodium sulfate (DSS) was examined.
IL-1beta production in response to DSS was studied in macrophages of wild-type, caspase-1(-/-), NLRP3(-/-), ASC(-/-), cathepsin B(-/-) or cathepsin L(-/-) mice. Colitis was induced in C57BL/6 and NLRP3(-/-) mice by oral DSS administration. A clinical disease activity score was evaluated daily. Histological colitis severity and expression of cytokines were determined in colonic tissue.
Macrophages incubated with DSS in vitro secreted high levels of IL-1beta in a caspase-1-dependent manner. IL-1beta secretion was abrogated in macrophages lacking NLRP3, ASC or caspase-1, indicating that DSS activates caspase-1 via the NLRP3 inflammasome. Moreover, IL-1beta secretion was dependent on phagocytosis, lysosomal maturation, cathepsin B and L, and reactive oxygen species (ROS). After oral administration of DSS, NLRP3(-/-) mice developed a less severe colitis than wild-type mice and produced lower levels of proinflammatory cytokines in colonic tissue. Pharmacological inhibition of caspase-1 with pralnacasan achieved a level of mucosal protection comparable with NLRP3 deficiency.
The NLRP3 inflammasome was identified as a critical mechanism of intestinal inflammation in the DSS colitis model. The NLRP3 inflammasome may serve as a potential target for the development of novel therapeutics for patients with IBD.
促炎细胞因子白细胞介素 1β（IL-1β）和 IL-18 是炎症性肠病（IBD）发病机制中的关键因素。这两种细胞因子在应对各种微生物成分和结晶物质时，均通过半胱天冬酶-1 激活的多蛋白复合物——NLRP3 炎性体进行加工。本研究旨在研究 NLRP3 炎性体在葡聚糖硫酸钠（DSS）诱导的实验性结肠炎中的作用。
在野生型、半胱天冬酶-1（caspase-1）（-/-）、NLRP3（-/-）、ASC（-/-）、组织蛋白酶 B（cathepsin B）（-/-）或组织蛋白酶 L（cathepsin L）（-/-）小鼠的巨噬细胞中，研究 DSS 诱导的 IL-1β 产生情况。通过口服 DSS 处理 C57BL/6 和 NLRP3（-/-）小鼠，诱导结肠炎。每天评估临床疾病活动评分。在结肠组织中测定组织学结肠炎严重程度和细胞因子的表达。
在体外用 DSS 孵育的巨噬细胞以依赖半胱天冬酶-1 的方式分泌高水平的 IL-1β。缺乏 NLRP3、ASC 或 caspase-1 的巨噬细胞中，IL-1β 分泌被阻断，表明 DSS 通过 NLRP3 炎性体激活半胱天冬酶-1。此外，IL-1β 的分泌依赖于吞噬作用、溶酶体成熟、组织蛋白酶 B 和 L 以及活性氧（ROS）。在口服 DSS 后，与野生型小鼠相比，NLRP3（-/-）小鼠发展出较轻的结肠炎，并在结肠组织中产生较低水平的促炎细胞因子。用 pralnacasan 抑制半胱天冬酶-1 的药理学作用可达到与 NLRP3 缺乏相似的黏膜保护水平。
NLRP3 炎性体被鉴定为 DSS 结肠炎模型中肠道炎症的关键机制。NLRP3 炎性体可能成为开发新型治疗 IBD 患者药物的潜在靶点。
