2026 Theses Doctoral

Anti-Inflammatory and Lipid-Lowering Strategies in Jak2V617F Clonal Hematopoiesis–Driven Atherosclerosis

Hardaway, Brian D.

Clonal Hematopoiesis arises from leukemogenic mutations that confer a selective advantage to hematopoietic cells, leading to clonal expansion, and is an independent risk factor for cardiovascular disease. Among clonal hematopoiesis drivers, Jak2V617F increases JAK-STAT signaling, can give rise to myeloproliferative neoplasms, and confers the strongest risk of myocardial infarction compared with other clonal hematopoiesis mutations.

In mouse models of clonal hematopoiesis and myeloproliferative neoplasms, Jak2V617F exacerbates atherosclerosis by increasing DNA damage, promoting AIM2 inflammasome activation, and impairing efferocytosis despite decreasing plasma cholesterol, suggesting that low-density lipoprotein lowering alone may be insufficient to reverse the associated increase in cardiovascular risk. Interleukin-1 inhibition, Jak2V617F inactivation, and TREM2 agonism each mitigate the effects of Jak2V617F by increasing fibrous cap thickness through enhanced collagen and proteoglycan deposition. In contrast, the JAK1/2 inhibitor ruxolitinib markedly worsens necrotic core formation in Jak2V617F lesions, suggesting that selective targeting of Jak2V617F may be required to reduce cardiovascular risk in patients.

In this study, we investigated mechanisms of decreased lesion stability with ruxolitinib treatment in Jak2V617F atherosclerotic lesions, assessed whether enhancing DNA damage repair can improve Jak2V617F lesions, and determined whether Jak2V617F impairs lesion regression with low-density lipoprotein lowering. Here, we show that ruxolitinib increases pyroptosis and necroptosis while decreasing apoptosis in Jak2V617F lesions, consistent with a shift from modes of cell death that promote efferocytosis toward pro-inflammatory modes that exacerbate necrotic core formation.

We further show that overexpression of the OGG1 DNA damage-repair enzyme modestly decreases lesion area and necrotic core area even when hematopoietic expression of Jak2V617F is low, suggesting that direct enhancement of DNA damage repair can improve lesions. Finally, we demonstrate that aggressive low-density lipoprotein lowering normalizes atherosclerosis regression in Jak2V617F mice, halting necrotic core formation, decreasing macrophage burden, and increasing collagen similar to controls. Low-density lipoprotein lowering reverses the proliferative, inflammatory phenotype of Jak2V617F by suppressing AIM2 inflammasome activation, abolishing Jak2V617F cell-intrinsic DNA damage and proliferation, increasing MerTK-positive, TREM2-high macrophages and restoring impaired efferocytosis. Aggressive low-density lipoprotein lowering markedly increases c-Myc in TREM2-high macrophages, suggesting that low-density lipoprotein lowering promotes survival or selective proliferation of these macrophages despite an overall decrease in macrophage proliferation.

Together, these findings identify necrotic cell death as a potential mechanism by which ruxolitinib destabilizes Jak2V617F lesions, show that augmenting DNA damage repair can modestly improve lesion stability, and demonstrate that the major, targetable driver of Jak2V617F-associated cardiovascular risk is elevated low-density lipoprotein cholesterol, which can be fully normalized by sufficiently intensive low-density lipoprotein lowering.