Cheluvappa Rajkumar, Luo Annie S, Grimm Michael C
Department of Medicine, St. George Clinical School, University of New South Wales, Sydney, Australia.
Inflamm Bowel Dis. 2014 May;20(5):847-55. doi: 10.1097/MIB.0000000000000034.
When done at a young age, appendicitis followed by appendectomy (AA) offers protection against ulcerative colitis development in later life. We developed the first ever murine AA model. Using this model, we showed earlier that previous AA ameliorated colitis. We aimed to determine whether autophagy genes contribute to the anti-colitis protection conferred by AA, and if so, to delineate the autophagy-linked genes involved in this.
Mice with 2 laparotomies each served as controls (sham-sham). Distal colons were harvested (4 AA-group colons, 4 sham-sham group colons), and RNA extracted from each. The RNA was taken through microarray analysis or reverse transcription-polymerase chain reaction validation. Gene set enrichment analysis software was used to analyze the microarray data.
Out of 28 key autophagy-related genes investigated (VPS15, VPS34, FIP200, ATG03, ATG04A, ATG04B, ATG05, ATG07, ATG10, ATG12, ATG13b, ATG14, ATG16L1, BECN1, GABARAPL1, IRGM1, IRGM2, LAMP2, LC3A, LC3B, RAB7A, UVRAG, NOD2, XBP1, LRRK2, ULK1, ULK2, PTPN2), 7 have genetic associations with inflammatory bowel diseases (ATG16L1, IRGM1, NOD2, XBP1, LRRK2, ULK1, PTPN2). There was slight upregulation of IRGM1, FIP200, and ATG04A (P < 0.05), but no variations with the other 25 genes. In contrast, gene set enrichment analysis revealed that AA downregulated 74 gene sets (associated with 28 autophagy genes) while upregulating only 5 (false discovery rate <5%; P < 0.001) gene sets. Additionally, 22 gene sets associated with the 7 autophagy + inflammatory bowel disease-associated genes were downregulated by AA, whereas only 3 were upregulated. The genes with maximum AA-induced gene set suppression were VPS15, LAMP2, LC3A, XBP1, and ULK1.
AA induces profound autophagy suppression in the distal colon. The AA-induced upregulation of individual genes (IRGM1, FIP200, ATG04A) could be a reflection of complex compensatory changes or the initial abnormality that led to the pronounced autophagy suppression. Autophagy suppression by AA may induce lesser antigen processing, leading to lesser cross-reactive immunity between microbes and self-antigens, and subsequent amelioration of colitis.
年轻时进行阑尾炎切除术后（AA）可预防日后发生溃疡性结肠炎。我们建立了首个小鼠AA模型。利用该模型，我们先前已表明既往AA可改善结肠炎。我们旨在确定自噬基因是否有助于AA赋予的抗结肠炎保护作用，若如此，则阐明其中涉及的自噬相关基因。
每组接受两次剖腹手术的小鼠作为对照（假手术-假手术组）。收集远端结肠（4个AA组结肠，4个假手术-假手术组结肠），并从每个样本中提取RNA。RNA进行微阵列分析或逆转录-聚合酶链反应验证。使用基因集富集分析软件分析微阵列数据。
在研究的28个关键自噬相关基因（VPS15、VPS34、FIP200、ATG03、ATG04A、ATG04B、ATG05、ATG07、ATG10、ATG12、ATG13b、ATG14、ATG16L1、BECN1、GABARAPL1、IRGM1、IRGM2、LAMP2、LC3A、LC3B、RAB7A、UVRAG、NOD2、XBP1、LRRK2、ULK1、ULK2、PTPN2）中，7个与炎症性肠病存在基因关联（ATG16L1、IRGM1、NOD2、XBP1、LRRK2、ULK1、PTPN2）。IRGM1、FIP200和ATG04A有轻微上调（P < 0.05），但其他25个基因无变化。相比之下，基因集富集分析显示AA下调了74个基因集（与28个自噬基因相关），而上调仅5个（错误发现率<5%；P < 0.001）基因集。此外，与7个自噬+炎症性肠病相关基因相关的22个基因集被AA下调，而仅3个上调。AA诱导基因集抑制程度最大的基因是VPS15、LAMP2、LC3A、XBP1和ULK1。
AA在远端结肠诱导深度自噬抑制。AA诱导的个别基因（IRGM1、FIP2（此处原文有误，应为FIP200）、ATG04A）上调可能反映了复杂的代偿性变化或导致明显自噬抑制的初始异常。AA诱导的自噬抑制可能导致较少的抗原加工，从而减少微生物与自身抗原之间的交叉反应性免疫，进而改善结肠炎。
