U843, INSERM, Paris, France; UMR-S843, Université Paris Diderot, Paris, France.
PLoS One. 2007 Jun 13;2(6):e523. doi: 10.1371/journal.pone.0000523.
CARD15/NOD2 mutations are associated with susceptibility to Crohn's Disease (CD) and Graft Versus Host Disease (GVHD). CD and GVHD are suspected to be related with the dysfunction of Peyer's patches (PP) and isolated lymphoid follicles (LFs). Using a new mouse model invalidated for Card15/Nod2 (KO), we thus analysed the impact of the gene in these lymphoid formations together with the development of experimental colitis.
METHODOLOGY/PRINCIPAL FINDINGS: At weeks 4, 12 and 52, the numbers of PPs and LFs were higher in KO mice while no difference was observed at birth. At weeks 4 and 12, the size and cellular composition of PPs were analysed by flow cytometry and immunohistochemistry. PPs of KO mice were larger with an increased proportion of M cells and CD4(+) T-cells. KO mice were also characterised by higher concentrations of TNFalpha, IFNgamma, IL12 and IL4 measured by ELISA. In contrast, little differences were found in the PP-free ileum and the spleen of KO mice. By using chamber experiments, we found that this PP phenotype is associated with an increased of both paracellular permeability and yeast/bacterial translocation. Finally, KO mice were more susceptible to the colitis induced by TNBS.
Card15/Nod2 deficiency induces an abnormal development and function of the PPs characterised by an exaggerated immune response and an increased permeability. These observations provide a comprehensive link between the molecular defect and the Human CARD15/NOD2 associated disorders: CD and GVHD.
CARD15/NOD2 突变与克罗恩病（CD）和移植物抗宿主病（GVHD）的易感性相关。CD 和 GVHD 被怀疑与派尔集合淋巴结（PP）和孤立淋巴滤泡（LF）的功能障碍有关。我们使用一种新的 Card15/Nod2（KO）基因无效的小鼠模型，分析了该基因对这些淋巴组织形成的影响，以及实验性结肠炎的发展。
方法/主要发现：在第 4、12 和 52 周时，KO 小鼠的 PP 和 LF 数量增加，而出生时没有差异。在第 4 和 12 周时，通过流式细胞术和免疫组织化学分析了 PP 的大小和细胞组成。KO 小鼠的 PP 较大，M 细胞和 CD4(+)T 细胞的比例增加。KO 小鼠还表现出更高的 TNFalpha、IFNgamma、IL12 和 IL4 浓度，通过 ELISA 测量。相比之下，KO 小鼠的无 PP 回肠和脾中差异较小。通过使用腔室实验，我们发现这种 PP 表型与细胞旁通透性和酵母/细菌易位的增加有关。最后，KO 小鼠对 TNBS 诱导的结肠炎更敏感。
Card15/Nod2 缺乏导致 PP 的异常发育和功能，表现为过度的免疫反应和增加的通透性。这些观察结果为分子缺陷与人类 CARD15/NOD2 相关疾病：CD 和 GVHD 之间提供了一个全面的联系。
