Blocking H1R signal aggravates atherosclerosis by promoting inflammation and foam cell formation

Atherosclerosis (AS) is a chronic inflammatory arterial disease, in which abnormal lipid metabolism and foam cell formation play key roles. Histamine is a vital biogenic amine catalyzed by histidine decarboxylase (HDC) from L-histidine. Histamine H1 receptor (H1R) antagonist is a commonly encountered anti-allergic agent in the clinic. However, the role and mechanism of H1R in atherosclerosis have not been fully elucidated. Here, we explored the effect of H1R on atherosclerosis using Apolipoprotein E-knockout (ApoE−/−) mice with astemizole (AST, a long-acting H1R antagonist) treatment. The results showed that AST increased atherosclerotic plaque area and hepatic lipid accumulation in mice. The result of microarray study identified a significant change of endothelial lipase (LIPG) in CD11b+ myeloid cells derived from HDC-knockout (HDC−/−) mice compared to WT mice. Blocking H1R promoted the formation of foam cells from bone marrow-derived macrophages (BMDMs) of mice by up-regulating p38 mitogen-activated protein kinase (p38 MAPK) and LIPG signaling pathway. Taken together, these findings demonstrate that blocking H1R signal aggravates atherosclerosis by promoting abnormal lipid metabolism and macrophage-derived foam cell formation via p38 MAPK-LIPG signaling pathway.