Project 3: Mouse Models to Enable Assessments of Clonal Hematopoiesis, Hematologic Indicator Changes, and Pro-inflammatory Phenotypes Following Radiation Exposure

Summary

Clonal hematopoiesis, associated with radiation exposure and increased risks of inflammatory diseases, has not been evaluated in animal model studies. To evaluate the extent to which clonal hematopoiesis following radiation exposure leads to the accumulation of pro-inflammatory monocytes in the periphery, this project will establish one or more mouse models that can test the hypothesis that clonal hematopoiesis in irradiated mice is involved in pro-inflammatory phenotypes that promote atherosclerosis formation. Elemental experimental procedures in this project include 1) identification of clonal hematopoiesis with somatic mutations by performing whole-exome sequencing using bone marrow (BM) cells, longitudinal analyses of hematologic indicators, and an in vitro analysis of macrophage function in irradiated and control mice; and 2) clonality assessments of monocytes accumulating in atherosclerotic plaques formed in LDLR-KO mice irradiated but not receiving BM transplantation, and/or those lethally irradiated and receiving BM transplantation from mice exhibiting clonal hematopoiesis. The prevalence of clonal hematopoiesis and related hematologic indicators will be compared in (C57BL/6 x C3H/HeJ) F1 (B6C3F1) mice following 3-Gy or 0-Gy irradiation. We will also assess the feasibility of using spontaneous mutations (SPMs) acquired in early embryogenesis as genetic markers for clonality assessments in LDLR-KO and B6C3F1 mice. In macrophages accumulating in atherosclerotic plaques developed in LDLR-KO mice, we expect to see expansion of those bearing particular SPMs. Mouse models developed in this project will provide mechanistic implications into the relationship between radiation-associated clonal hematopoiesis and pro-inflammatory phenotypes potentially underlying increased risks of inflammatory diseases such as cardiovascular disease among atomic bomb survivors. In addition, hematopoietic stem cell dynamics that may be measurable in the mouse models will inform the development of mathematical and computational models for clonal hematopoiesis and mediator-mediator interactions in atherosclerosis development following radiation exposure.