Role of AIOLOS in T Cell Mediated Pathogenesis of Inflammatory Bowel Disease

Project Summary: Inflammatory bowel disease (IBD) affects 3.1 million people in the United States, yet the precise mechanisms underlying its pathogenesis remain incompletely understood. Genome-wide association studies have identified multiple genes linked to IBD, including IKZF3, which encodes the transcriptional repressor AIOLOS, a protein exclusively expressed in lymphocytes. While these findings suggest a role for AIOLOS in immune regulation, the exact mechanisms by which it contributes to immune dysregulation in IBD are not fully elucidated. In our preliminary studies using murine models, we demonstrated that AIOLOS plays a crucial role in restraining the activation of CD4⁺ and CD8⁺ T cells. Specifically, AIOLOS-deficient mice exhibited heightened T cell activation and exacerbated disease in a mouse model of immune-mediated colitis. Mechanistically, we found that AIOLOS regulates T cell responsiveness to interleukins IL-2 and IL-12, which signal through the STAT5 and STAT4 pathways, respectively. These findings highlight the importance of AIOLOS in maintaining immune homeostasis and preventing excessive inflammation in the gut. Building upon these findings in mouse models, we aim to investigate whether similar mechanisms operate in humans and contribute to IBD pathogenesis by analyzing biorepository samples from healthy individuals and patients with IBD collected and stored at our institute, University of Colorado. We hypothesize that altered expression or function of AIOLOS in human T cells leads to excessive activation of CD4⁺ and CD8⁺ T cells in some IBD patients, resulting in chronic intestinal inflammation. In Aim 1, we will investigate the functional role of AIOLOS in human T cell activation by utilizing CRISPR-Cas9 genome-editing technology to delete AIOLOS in human T cells. After AIOLOS deletion, we will assess how its absence impacts T cell functions, including cytokine production and proliferation in response to cytokine stimulation. We will also analyze the transcriptomic changes resulting from AIOLOS deletion using RNA-seq. In Aim 2, we will compare AIOLOS expression patterns between healthy individuals and patients with IBD. We will isolate peripheral blood mononuclear cells (PBMCs) from both groups, stimulate T cells with various cytokines (IL-2, IL-6, IL-12, IFNα), and analyze AIOLOS expression using flow cytometry. Additionally, we will compare AIOLOS expression in T cells isolated from the inflamed intestinal tissues of IBD patients to those from healthy control intestines to determine whether its expression is altered in the local immune environment. By integrating our murine findings with human studies, we aim to create a comprehensive understanding of AIOLOS's role across species, strengthening the translational potential of our research. This approach allows us to build on established mechanisms from murine models while assessing their relevance to human health and disease. Overall, this study will enhance our understanding of AIOLOS’s role in human T cell biology and its potential contribution to immune dysregulation in IBD.