Abstract Body: Introduction: Clonal Hematopoiesis of Indeterminate Potential (CHIP) is characterized by the expansion of a blood-cell clone due to somatic mutation in hematopoietic stem cells, in the absence of other hematologic abnormalities. Initially, CHIP was identified as a risk factor for hematologic cancer, but recently, many studies have implicated it as a risk factor for cardiovascular disease. CHIP is also considered a risk factor for subarachnoid hemorrhage. However, the causality between CHIP and aneurysm rupture, as well as the mechanism by which CHIP promotes aneurysm rupture, remains unclear. Our study aimed to assess whether CHIP promotes the development of intracranial aneurysm rupture and investigate its mechanisms in mice. We induced intracranial aneurysms on chimeric mice with partial bone marrow transplantation of TET2-knockout hematopoietic stem cells, widely used to recapitulate human CHIP to test our hypothesis.
Methods: We used competitive bone marrow transplantation as a model of CHIP. We used the C57BL/6 congenic mice that express the CD45.1 allele as a recipient and TET2-knockout mice that carry CD45.2 alleles as a donor. C57BL/6 CD45.1+/CD45.2- congenic mice were transplanted with suspensions of bone marrow cells containing 10% CD45.1-/CD45.2+ TET2-/- cells and 90% CD45.1+/CD45.2- TET2+/+ cells as a TET2-derived CHIP model. We induced intracranial aneurysms by a combination of elastase injection and DOCA-salt hypertension at 8 weeks later. We evaluated the formation and rupture rates of intracranial aneurysms and the survival curve. The qPCR was used to reveal molecular change in the intracranial artery. From the result of qPCR, we utilized IL-6 monoclonal antibody and NLRP3 inhibitor as a treatment for CHIP-related intracranial aneurysm rupture.
Results: First, CHIP mice show clonal expansion of TET2-knockout cells in flow cytometry (Fig.1). Our studies demonstrated increased aneurysmal rupture rates in CHIP mice of both sexes (Fig.2). Second, Inflammatory cytokines including IL-6, IL-1β, and NLRP3 were elevated in qPCR (Fig.3). Lastly, both IL-6 monoclonal antibody and NLRP3 inflammasome inhibitor significantly decreased aneurysm rupture rate in CHIP mice.
Conclusions: Our study showed that CHIP promotes the development of intracranial aneurysm rupture. Its mechanism is through the upregulation of inflammatory cytokines. Our findings suggest that IL-6 and NLRP3 are promising therapeutic targets for CHIP-related intracranial aneurysm rupture.