Exploring the transformation potential of haematopoietic stem cells under niche pressure, and its therapeutic targeting.

Acute myeloid leukaemia (AML) is a deadly disease characterised by aberrant myeloid lineage proliferation and differentiation. Our previous work has shown that IL-1 receptor antagonist (IL-1RN), contributes to myeloproliferation in health and in presence of known malignant mutations in mouse models, is a prognostic marker for poor survival in AML patients and provides a new rationale for IL-1ß blockade therapeutic potential. We will determine the mechanisms that cause low IL-1RN. Using big data sets, we will study if these mechanisms correlate to clonal haematopoiesis (pre-leukaemic condition that does not always result in leukaemia), and thereby predispose to haematological malignancy and age-related disease. Their functional impact and potential therapeutic value will be confirmed in vivo using xenografts. Myeloproliferative neoplasms (MPNs) are clonal haematopoietic diseases, characterised by increased production of mature cells and shortened lifespan. Their major complication is transformation to AML. Our previous work has shown that neuropathy in the bone marrow is essential for MPN development. We have now identified germinal loss of function variants in the gene NTRK1 (involved in proliferation and survival of neurons), present in family members with mutually exclusive MPN driver mutations. We will perform ex vivo functional and phenotypic studies in carriers. The pathogenic potential of the variants will be characterized in vivo using gene knock-out, in presence or absence of known MPN mutations. Human samples will be used in serial xenografts to evaluate the potential of the variants to predispose to acquisition of driver somatic mutations. Finally, we will explore the potential neural-immune interactions, i.e. NTRK1-IL1RN, in the origin of haematological malignancies. Our approach will provide new knowledge into the origin of haematological malignancies and has the potential to pave the path for disease prevention, early detection and efficient treatment.

AML is a heterogeneous and deadly disease characterised by aberrant myeloid lineage proliferation and differentiation. Our previous work has shown that low IL-1ß endogenous regulatory cytokine, IL-1 receptor antagonist (IL-1RN), from either the haematopoietic or the stromal compartment, contributes to biased myelopoiesis in the presence of pre-leukaemic lesions in mouse models, is a prognostic marker for reduced survival in AML patients, and provides a new rationale for IL-1ß blockade therapeutic potential. We will now determine the genetic/epigenetic mechanisms associated to low IL1RN within AML CD34+ progenitors and their MSC niche. Using the Lothian Birth Cohorts, we will determine if these mechanisms correlate to clonal haematopoiesis (CHIP) driven by them and/or additional mutations, and thereby predispose to haematological malignancy and age-related disease. Their functional impact will be confirmed. In parallel, MPNs are clonal haematopoietic diseases, characterised by increased production of mature cells, extramedullary haematopoiesis and shortened lifespan. Their major complication is transformation to secondary AML, which is particularly aggressive. Our previous work has shown that neuropathy of the HSC niche is essential for the development of MPN. We have identified germinal loss of function variants in the gene NTRK1, NGF receptor, which are present in family members with mutually exclusive driver mutations for MPN, JAK2 and CALR. We will now characterise the pathogenic potential of these variants in both the BM haematopoietic and stromal compartments in vivo using gene knock-out of Ntrk1, in presence or absence of additional driver mutations. Human haematopoietic progenitors will be used in serial xenografts to evaluate the potential of the germline variants to predispose to acquisition of somatic mutations at the single-cell level and the development of CHIP and/or MPN.