van Heel D A, Ghosh S, Hunt K A, Mathew C G, Forbes A, Jewell D P, Playford R J
Intestinal Inflammation and Repair Group, Department of Gastroenterology, Imperial College London, Hammersmith Campus, London W12 0NN, UK.
Gut. 2005 Nov;54(11):1553-7. doi: 10.1136/gut.2005.065888. Epub 2005 May 31.
Nucleotide binding oligomerisation domain 2 (NOD2; also known as CARD15) mutations are associated with Crohn's disease but how mutations cause disease is poorly understood. Innate immune responses are reportedly enhanced by combined NOD2 ligand (muramyl dipeptide, MDP) and Toll-like receptor 4 ligand (TLR4, lipopolysaccharide) stimulation. Intestinal TLR signalling has a dual role-maintaining intestinal homeostasis and protection from injury as well as initiating inflammatory responses. TLR9 is functional in the intestinal epithelium where it is most strongly expressed in Paneth cells.
To study possible interactions between CpG DNA (TLR9 ligand) and MDP using primary human cells of differing NOD2 genotypes.
NOD2 wild-type healthy controls (n = 7) and NOD2 homozygous Crohn's disease patients (n = 19), age and sex matched.
Peripheral blood mononuclear cells were stimulated with CpG DNA and MDP. Cytokines were measured by enzyme linked immunosorbent assay.
Tumour necrosis factor alpha (TNF-alpha) and interleukin 8 (IL-8) responses to CpG DNA were similar in NOD2 wild-type and homozygous mutant cells. Concomitant NOD2 stimulation had a marked synergistic effect on CpG DNA induced TNF-alpha responses at 10-100 ng/ml MDP. A mean 2.1-fold increase in CpG DNA induced TNF-alpha responses and a mean 3.7-fold increase in IL-8 responses were observed in NOD2 wild-type cells with 10 ng/ml MDP. This effect was abolished in NOD2 homozygous cells.
NOD2 stimulation normally enhances innate immune responses to CpG DNA. This marked synergistic effect is lost in Crohn's disease patients homozygous for NOD2 mutations, with implications for TLR mediated intestinal homeostasis and inflammation.
核苷酸结合寡聚化结构域2（NOD2；也称为CARD15）突变与克罗恩病相关，但突变如何导致疾病尚不清楚。据报道，NOD2配体（胞壁酰二肽，MDP）和Toll样受体4配体（TLR4，脂多糖）联合刺激可增强先天免疫反应。肠道TLR信号传导具有双重作用——维持肠道内环境稳定和免受损伤以及引发炎症反应。TLR9在肠道上皮细胞中起作用，在潘氏细胞中表达最强。
使用不同NOD2基因型的原代人细胞研究CpG DNA（TLR9配体）与MDP之间可能的相互作用。
NOD2野生型健康对照者（n = 7）和NOD2纯合克罗恩病患者（n = 19），年龄和性别匹配。
用CpG DNA和MDP刺激外周血单个核细胞。通过酶联免疫吸附测定法检测细胞因子。
NOD2野生型和纯合突变细胞对CpG DNA的肿瘤坏死因子α（TNF-α）和白细胞介素8（IL-8）反应相似。在10 - 100 ng/ml MDP时，同时进行的NOD2刺激对CpG DNA诱导的TNF-α反应有显著的协同作用。在含有10 ng/ml MDP的NOD2野生型细胞中，观察到CpG DNA诱导的TNF-α反应平均增加2.1倍，IL-8反应平均增加3.7倍。在NOD2纯合细胞中这种作用消失。
NOD2刺激通常会增强对CpG DNA的先天免疫反应。在NOD2突变纯合的克罗恩病患者中这种显著的协同作用丧失，这对TLR介导的肠道内环境稳定和炎症有影响。
