The Study Of Myeloid Cell-Specific Serine Palmitoyltransferase Subunit2Insufficiency On Murine Atherosclerosis Development

Objectives:Serine palmitoyltransferase (SPT) is the first and rate-limiting enzyme of the de novo biosynthetic pathway of sphingomyelin (SM). Both SPT and SM have been implicated in the pathogenesis of atherosclerosis, a disease in which macrophages are known to be a critical driving force in its development. Macrophages are derived from myeloid cells, the role of SPT in macrophages and myeloid cells mediated atherogenesis is unknown. To address this issue, we investigated the effects of myeloid cell specific Sptlc2+/-on atherosclerosis development. We performed this study at State University of New York Downstate Medical Center.Methods:(1) We crossed Sptlc2-Flox mice with LysM-Cre transgenic mice and prepared heterozygous Sptlc2-Flox/LysM-Cre transgenic mice. We monitored the process of cell replacement by PCR, using genomic DNA from mouse PBMCs as templates.(2) We transplanted Sptlc2-Flox or Sptlc2-Flox/LysM-Cre mouse bone marrow into Ldlr-/-mice. Before bone marrow transplantation, total Ldlr-/-mice were lethally irradiated with10Gy. After bone marrow transplantation, We checked the genotype, blood cell counts and plasma lipid levels.(3) After bone marrow transplantation, the mice were fed with western-type diet for12weeks. Then, Aortae were dissected, aortic arches were photographed, and aortic lesion en face assay was performed.Results:(1) Blood cell counts showed no differences between Sptlc2-Flox/LysM-Creâ†'Ldlr-/-and Sptlc2-Floxâ†'Ldlr-/-mice.(2) After12weeks on a Western-type diet, all mice had lesions in the aortic arches. However, those of Sptlc2-Flox/LysM-Creâ†'Ldlr-/-mice were smaller than those of Sptlc2-Floxâ†'Ldlr-/-mice.(3) The proximal aortae of Sptlc2-Flox/LysM-Creâ†'Ldlr-/-animals also exhibited decreased lesion areas (35%decrease, P<0.05).(4) In addition, significantly reduced lesion areas were revealed by Oil-Red O staining in the whole aortae of Sptlc2-Flox/LysM-Creâ†'Ldlr-/-compared with control mice (30%reduction, P<0.05).Conclusions: (1) Myeloid cell specific Sptlc2+/-can reduce Murine atherosclerotic lesions.(2) Myeloid cell SPT could be a novel therapeutic target for atherosclerosis.