Grant: Project Grant

Background: Autoimmune diseases (AD) are a significant cause of chronic morbidity and disability in men and women. Multi-organ autoimmunity is a feature of Tregopathies, rare congenital diseases caused by mutations in key immune genes like FOXP3, a master genetic factor driving the development of regulatory T (Treg) cells, gatekeepers in the prevention of AD. Over 60 mutations are associated with a broad clinical spectrum and variable degrees of Treg cell deficiency in Tregopathies. Establishing a definitive diagnosis and therapy is crucial for patients and represents major unmet clinical need. Hypothesis: Immune Dysregulation, Polyendocrinopathy, Enteropathy, X-linked (IPEX) is the hallmark Tregopathy caused by germline mutations in the FOXP3 gene. We hypothesize that individual mutations selectively impact key aspects of the FOXP3 function, ultimately disrupting Treg cell development, homeostasis, or function in IPEX. Objective and Research Aims: We have recently made the ground-breaking demonstration that hematopoietic stem cell (HSC) can develop into FOXP3+ Treg cells in artificial thymic organoids (ATOs). Our objective to understand how FOXP3 functions in human Treg cell development in IPEX both in vitro and in vivo. The proposal comprises 3 aims: (i) (Aim 1) to study the factors that influence FOXP3 activity in human Treg functional development in our ATO system; (ii) (Aim 2) to use IPEX patient-derived HSC and genome editing to reproduce patients' mutations in primary human HSC and study the impact of candidate FOXP3 mutations on Treg development in ATOs; and (iii) (Aim 3) to evaluate their potential to control immune responses in humanized mouse models. Significance: Our research will harness the power of a state-of-the-art ATO system to study how FOXP3 mutations cripple human Treg cell development, thus better defining diagnosis, improving our understanding of disease