Poster Session I - A30 INVESTIGATING THE IMPACT OF PARKINSON’S DISEASE-ASSOCIATED GENE <i>PINK1</i> ON INTESTINAL HOMEOSTASIS AND RESPONSE TO INFECTION

Abstract Background Intestinal epithelial cells (IECs) provide an essential physical barrier between luminal contents and host tissue. Dysregulation of IECs leads to barrier dysfunction, contributing to pathologies in both intestinal and extra-intestinal diseases. While Parkinson’s Disease (PD) is primarily a neurodegenerative disorder, increasing evidence links PD progression and gastrointestinal dysfunction. Our group developed a model to investigate the role of the gut in PD, demonstrating that mice with genetic ablation of the PD-associated gene Pink1 exhibited motor phenotypes only when previously infected with gram-negative intestinal bacteria – Citrobacter rodentium. As Pink1 is expressed in IECs and the colonic lamina propria, we hypothesize that PD-associated gene mutations directly affect the epithelium and impact early PD pathophysiology. Aims 1. Characterize transcriptional profiles of Pink1 wild-type (WT) and knockout (KO) IECs at baseline and following in vivo C. rodentium infection. 2. Investigate Pink1-dependent epithelial responses using isolated in vitro and ex vivo systems. Methods Single-cell RNA sequencing (scRNAseq) was performed on colonic IECs isolated from Pink1 WT and KO mice, at steady state and following in vivo C. rodentium infection. Mice were sacrificed at day 7 and day 14 post-infection to capture transcriptional changes across IEC lineages. To further explore pathways identified by scRNAseq, ex vivo colonoids derived from Pink1 WT and KO crypts, as well as Pink1 KO CMT-93 epithelial cell line with WT control, will be used in complementary validation assays. We will also complete colonic epithelium-T cell co-culture experiments to evaluate MHC class I-restricted antigen presentation. Results At baseline, our data revealed upregulation of interferon (IFN)-signaling genes (ISGs) in Pink1 KO colonocytes compared to WT. During infection, Pink1 KO absorptive progenitors showed significant alterations in ISGs and actin-cytoskeleton-related GO term pathways compared to WT. Additionally, Pink1 KO stem cells, transit-amplifying cells, absorptive progenitors, and colonocytes demonstrated increase in antigen presentation and processing-related pathways. Further in vivo and in vitro work will be completed to validate these findings. Conclusions Using in vivo and in vitro models encompassing PD-genetic susceptibility and environmental stimuli, we identified dysregulation in Pink1 KO epithelium, suggesting altered inflammatory responses at baseline and infection. By investigating PD-associated genes in IECs, we will contribute to better understanding the role of the intestine in PD initiation, progression, and pathogenesis. Funding Agencies CIHR, NoneTRIANGLE