Decoding the role of RIPK1 in human immunity and intestinal inflammation - Molecular insights from children with monogenic RIPK1 deficiency

• Applicant: Dr. Daniel Kotlarz
• Subject Area: Pediatric and Adolescent Medicine
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 447562338

Children with rare very early onset inflammatory bowel diseases (VEO-IBD; onset < 6 years of age) often show severe and life-threatening courses refractory to conventional treatment. Paradigmatic studies by our laboratory have shown that IBD can be caused by monogenic defects in interleukin-10 receptor (IL10R) genes.To decipher novel molecular signatures of VEO-IBD I have systematically analyzed one of the largest international cohorts of more than 750 VEO-IBD patients by state-of-the-art next-generation sequencing. Our genetic screen has unraveled biallelic loss-of-function mutations in RIPK1 as novel genetic entity of VEO-IBD. RIPK1 is a key regulator of cell death processes and has been considered as attractive therapeutic target for common inflammatory and autoimmune diseases. The characterization of RIPK1-deficient patients has evidenced the essential role of RIPK1 in controlling immunity and intestinal homeostasis. However, the underlying disease mechanisms remain poorly understood and our preliminary studies did not yet provide decisive implications for the clinical management of patients.Here, I propose to comprehensively study immune and intestinal epithelial barrier dysfunctions of human RIPK1 deficiency using an advanced reverse genetic approach. To elucidate underlying multifactorial pathomechanisms of human RIPK1 deficiency, my group will employ CRISPR/Cas9-engineered induced pluripotent stem cells with patient-specific mutations to generate macrophages, 3D mini-guts and humanized mice with predictive characteristics for preclinical applications. Using these cutting-edge disease models, we will explore (i) perturbed modules of inflammasome activity, polarization, bioenergetic profiles, and bacterial handling in macrophages, (ii) inflammasome signaling, cell death programs, and host-pathogen interactions in intestinal epithelial cells, and (iii) inflammatory phenotypes in humanized mouse models. Taken together, I postulate that my proposed project will shed light on RIPK1-dependent mechanisms controlling immune homeostasis and inflammation. This knowledge will catalyze the development of novel diagnostic tools and personalized therapies for children with intractable RIPK1 deficiency. Since molecular targeting of RIPK1 is of prime interest for common inflammatory conditions, my studies will also (i) provide critical insights into potential effects and toxicities of therapies targeting RIPK1, and (ii) facilitate the discovery of novel biomarkers and therapeutic targets of common immune-related diseases.

• DFG Programme: Research Grants