Department Gastroenterology and Hepatology, Erasmus MC University Medical Centre Rotterdam, Rotterdam, The Netherlands.
Gut. 2014 Jul;63(7):1081-91. doi: 10.1136/gutjnl-2012-303527. Epub 2013 Aug 20.
Although genome wide association studies have partly uncovered the genetic basis of Crohn's disease (CD), it remains a challenge to link genetic polymorphisms to functional intestinal phenotypes. Paneth cells are specialised antimicrobial epithelial cells localised to the small-intestinal crypt-base. Here, we investigate whether genomic variations in ATG16L1 affect Paneth cell function.
Genomic variation of ATG16L1 (T300A, rs2241880) was determined in DNA from 78 patients with CD and 12 healthy controls. Paraffin-embedded ileal biopsies from patients with genotype AA (n=17), GA (n=38) and patients with the GG allele (n=23) were stained for GRP78, phospho-EIF2α, lysozyme, cleaved-caspase 3, phosphohistone H3, phospho-IκB, p65, phospho-p38MAPK and PHLDA1. Microbial composition of biopsies was assessed by PCR. Disease phenotype was scored.
In patients with quiescent disease but with an ATG16L1 risk allele, the endoplasmic reticulum (ER) stress markers GRP78 and pEIF2α were highly expressed in Paneth cells. Other CD risk gene variations did not correlate with Paneth cell ER stress. Functionally, patients with ER-stressed Paneth cells showed no changes in intestinal epithelial cells proliferation or apoptosis, Paneth cell or stem cell numbers, p65, phospho-IκB and phospho-p38 staining. However, a significantly increased presence of adherent-invasive Escherichia coli was observed in biopsies from patients with ER-stressed Paneth cells. Phenotypically, patients with GRP78 positive Paneth cells have relatively less colonic disease over ileal disease (-21%, p=0.04), more fistulas (+21%, p=0.05) and an increased need for intestinal surgery (+38%, p=0.002).
The ATG16L1 T300A polymorphism defines a specific subtype of patients with CD, characterised by Paneth cell ER stress even during quiescent disease. Paneth cell ER stress correlates with bacterial persistence, and is thus likely to modulate antimicrobial functionality of this cell type in patients with CD.
虽然全基因组关联研究部分揭示了克罗恩病（CD）的遗传基础，但将遗传多态性与功能性肠道表型联系起来仍然是一个挑战。潘氏细胞是定位于小肠隐窝基底的特殊抗菌上皮细胞。在这里，我们研究 ATG16L1 的基因组变异是否影响潘氏细胞功能。
在 78 例 CD 患者和 12 例健康对照的 DNA 中确定 ATG16L1（T300A，rs2241880）的基因组变异。对基因型为 AA（n=17）、GA（n=38）和 GG 等位基因患者（n=23）的石蜡包埋回肠活检进行 GRP78、磷酸化 EIF2α、溶菌酶、cleaved-caspase 3、磷酸组蛋白 H3、磷酸化 IκB、p65、磷酸化 p38MAPK 和 PHLDA1 染色。通过 PCR 评估活检中的微生物组成。对疾病表型进行评分。
在处于缓解期但具有 ATG16L1 风险等位基因的患者中，内质网（ER）应激标志物 GRP78 和 pEIF2α在潘氏细胞中高度表达。其他 CD 风险基因变异与潘氏细胞 ER 应激无关。功能上，ER 应激的潘氏细胞患者的肠上皮细胞增殖或凋亡、潘氏细胞或干细胞数量、p65、磷酸化 IκB 和磷酸化 p38 染色无变化。然而，在 ER 应激的潘氏细胞活检中观察到粘附侵袭性大肠杆菌的存在明显增加。表型上，GRP78 阳性潘氏细胞患者的结肠疾病相对较少，回肠疾病较多（-21%，p=0.04），瘘管较多（+21%，p=0.05），肠道手术需求增加（+38%，p=0.002）。
ATG16L1 T300A 多态性定义了 CD 的一种特定亚型，其特征是即使在缓解期也存在潘氏细胞 ER 应激。潘氏细胞 ER 应激与细菌持续存在相关，因此可能调节 CD 患者这种细胞类型的抗菌功能。
