Use of transgenic mice to study the role of autophagy protein ATG16L1 in Crohn’s Disease

Betts, Meghan (2016) Use of transgenic mice to study the role of autophagy protein ATG16L1 in Crohn’s Disease. Doctoral thesis, University of East Anglia.

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Crohn’s disease (CD) is a chronic inflammatory bowel disorder that primarily affects
the ileum and colon. CD aetiology is complex, with the current most widely accepted
hypothesis being that disease onset is triggered by environmental factors that alter the
intestinal microbiota and abnormally stimulate the intestinal immune response in
genetically susceptible individuals. Genome-wide association studies (GWAS) have
identified a single nucleotide polymorphism (SNP) conferring T300A in the autophagy
gene ATG16L1 as a CD susceptibility locus1. ATG16L1 is an essential component of the
autophagy pathway, a conserved cellular degradation pathway also linked to bacterial
defence2. It is not known how disruptions in ATG16L1 or autophagy contribute to CD
pathogenesis, although evidence increasingly suggests their involvement in defective
defence against bacterial infections. We hypothesise that autophagy defects caused by
mutations in ATG16L1 prevent effective clearance of pathogens and/or pathobionts by
xenophagy, resulting in a persistent infection and overt inflammation.
To address this question we generated and characterised mice with an intestinal
epithelial cell (IEC)-targeted deletion of Atg16L1 (Atg16L1ΔIEC) and validated our
findings by histological analysis of intestinal tissue from CD patients expressing the CDrisk
variant of ATG16L1 (*300A). To determine whether a combination of Atg16L1
mutations and a bacterial infection leads to the development of CD-like pathogenesis,
Atg16L1ΔIEC mice were characterised following infection with Salmonella Typhimurium.
We confirm that Atg16L1 is required for autophagy and show that an IEC-targeted
deletion of this gene without an additional bacterial challenge does not initiate
intestinal inflammation. Following S. Typhimurium infection, Atg16L1ΔIEC mice
exhibited an enlargement of colonic goblet cells. In contrast, CD patients expressing
*300A displayed smaller colonic goblet cells. Infected Atg16L1ΔIEC mice also exhibited
colonic crypt atrophy and a reduced number of ileal villi; however there was no
evidence of increased inflammation either prior to- or post- infection with S.
Typhimurium. Trends of increased bacterial dissemination to peripheral organs were
also observed in Atg16L1ΔIEC mice, suggesting that Atg16L1 is essential for regulating
IEC xenophagy and is required to prevent systemic infection of mice with S.

Item Type: Thesis (Doctoral)
Additional Information: This thesis has been embargoed, but no date has been given for its expiry.
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Stacey Armes
Date Deposited: 07 Jun 2016 15:37
Last Modified: 07 Jun 2016 15:37

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