Anti-β2GPⅠ antibody promotes uptake of oxLDL by macrophages to accelerate the progression of atherosclerosis

ObjectiveTo investigate the role of anti-β2-glycoprotein Ⅰ(β2GPⅠ)antibody in the relationship between macrophage uptake and atherosclerosis in apoE knockout (apoE^-/-) mice.

MethodsThe male apoE^-/- mice were randomly divided into the anti-β2GPⅠ antibody group and model group, with 8 mice in each group, and fed with high-fat diet for 8 weeks.The mice in the anti-β2GPⅠ antibody group were intraperitoneally injected with anti-β2GPⅠantibody, and the mice in the model group were intraperitoneally injected with the same dose of homologous control IgG antibody diluted with 0.9% sodium chloride solution.After 8 weeks, the mice were dissected, and the aortic root tissues were isolated for Movat staining and immunohistochemical staining to observe the histopathological characteristics of atherosclerotic plaques in the aortic root; Western blotting was used to detect the expression of marker proteins of endoplasmic reticulum stress and macrophage in aortic plaques; the peritoneal macrophages were cultured in vitro, the anti-β2GPⅠ antibody group and model group were stimulated with oxidized low-density lipoprotein (oxLDL) plus anti-β2GPⅠ antibody and oxLDL for 24 hours, respectively, to observe the uptake of oxLDL by macrophages.

ResultsMovat staining showed that the aortic plaque increased, the plaque area was larger, and the contents of collagen fibers and smooth muscle fibers were decreased in the anti-β2GPⅠ antibody group compared with the model group (P < 0.05 to P < 0.01).Immunohistochemical staining indicated that the area of macrophages in the aortic root plaque in the anti-β2GPⅠ antibody group was larger than that in the model group (P < 0.05).The results of Western blotting displayed that the expression levels of marker proteins of endoplasmic reticulum stress pathway such as IRE1-α, p-IRE1-α, ATF6, GRP-94 and macrophage CD36 protein were higher than those in the model group (P < 0.05 to P < 0.01).The results of fluorescence staining showed that the green fluorescence intensity in the anti-β2GPⅠ antibody group was significantly stronger than that in model group (P < 0.01).The results of oil red O staining of foam cells showed that foam cells existed in the anti-β2GPⅠ antibody group and the number of foam cells was significantly higher than that in the model group (P < 0.01).

ConclusionsThe anti-β2GPⅠ antibody promotes the uptake of oxLDL by macrophages in apoE^-/- mice, accelerates the formation of foam cells, and increases the expression of CD36 in macrophages through endoplasmic reticulum stress to accelerate the uptake of oxLDL, thus promoting the progression of atherosclerosis.