Lamin A/C Expression in Hematopoietic Cells Declines During Human Aging and Constrains Atherosclerosis in Mice.

BACKGROUND: Aging is the primary risk factor for atherosclerosis, a degenerative process regulated by immune cells and the leading cause of death worldwide. Previous studies on premature aging syndromes have linked atherosclerosis to defects in A-type lamins, key nuclear envelope components. However, whether these defects influence atherosclerosis during normal aging remains unexplored. Here, we examined how aging affects lamin A/C expression in circulating leukocytes and investigated the impact of manipulating their expression in hematopoietic cells on their function and atherosclerosis progression. METHODS: Flow cytometry assessed lamin A/C expression in human circulating leukocytes. Bone marrow from donor mice was transplanted into lethally irradiated, Ldlr(-/-)-deficient mice to study leukocyte extravasation into the vessel wall via intravital microscopy in the cremaster muscle, and high-fat-diet-induced atherosclerosis via Oil Red O staining of the aorta and carotid arteries. Single-cell RNA sequencing of the aorta was conducted to identify transcriptional changes associated with hematopoietic cell lamin A/C gain-of-function or loss-of-function. RESULTS: Human aging is associated with lower levels of lamin A/C expression in blood-borne leukocytes. To evaluate the functional relationship between hematopoietic lamin A/C expression and atherosclerosis development, we used Lmna-null mice and Lmna(tg) mice, the latter being the first in vivo model of lamin A gain-of-function. Transplanting lamin A/C-deficient bone marrow into Ldlr(-/-) mice increased leukocyte extravasation into the vessel wall and accelerated atherosclerosis. Conversely, transplantation of bone marrow overexpressing lamin A into Ldlr(-/-) receptor mice reduced leukocyte extravasation and atherosclerosis. Single-cell RNA sequencing of atherosclerotic mouse aorta revealed that alterations to hematopoietic cell lamin A/C expression primarily modify the transcriptome of immune cell populations and endothelial cells, affecting their functionality. CONCLUSIONS: We suggest that the age-related decline in lamin A/C expression in blood-borne immune cells contributes to increased leukocyte extravasation and atherosclerosis, highlighting lamin A/C as a novel regulator of age-related atherosclerosis.