Effect of B-Cell Receptor Recognition on Atherosclerosis in Transgenic Mice
Abstract
Introduction: Atherosclerosis is an inflammatory disease of the large and medium arteries characterized by accumulation of oxidized low-density lipoproteins (oxLDL) within the aorta. Antibodies against oxLDL show that B cell response is involved in atherogenesis; however, B cell receptor (BCR) recognition of oxLDL has not been directly demonstrated, and specific self-antigens are not well characterized. B cell anergy is a state of B cell unresponsiveness caused by weak recognition of self-antigens. While anergy break is critical in autoimmune diseases, evidence suggests that anergic autoreactive B-cells may support chronic inflammation by mechanisms outside classical autoimmunity. While no oxLDL-specific BCR-restricted mouse model yet exists, models of increased anergy (the ARS/A1 mouse model, with weakly self-reactive BCR and therefore high anergic populations) and BCR restriction (the MD4 mouse model, with BCR sensitive only to hen-egg lysozyme) can be used to explore the effect of B cell anergy and BCR restriction on atherosclerosis.
Methods: Male MD4, ARS/A1, and C57BL/6 WT mice were treated with an adenovirus vector containing PCSK9 to induce hyperlipidemia and fed a high-fat diet (HFD) for 15-28 weeks before sacrifice. Genotyping was performed via flow cytometry. Plasma cholesterol was determined via colorimetric assay. Aortas were removed and stained with Oil Red O en face, and plaque formation was quantified through color analysis in ImageJ. Hearts were fixed, and sections at the aortic sinus were stained with Movat pentachrome stain. Total lesion, fibrous cap, and necrotic core areas were assessed and analyzed using ImageJ.
Results: No significant differences were found in aortic atherosclerosis lesions (n=4-12) or aortic sinus fibrous cap or necrotic core between ARS, MD4 and WT mice (n=4-9/group).
Conclusion: Our preliminary data suggest that altering BCR recognition by all B cells does not significantly affect the degree and phenotype of plaque burden. Further experiments focused on BCR recognition in specific B cells subsets might elucidate role of BCR in atherogenesis.