Macrophage apoAI protects against dyslipidemia-induced dermatitis and atherosclerosis without affecting HDL

Area of Science:

• Cardiovascular Biology
• Immunodermatology

Background:

• Tissue cholesterol accumulation, macrophage infiltration, and inflammation characterize atherosclerosis and dermatitis.
• High-density lipoprotein (HDL) and apolipoprotein AI (apoAI) facilitate cholesterol efflux from macrophages, mitigating tissue inflammation.
• Current research questions the efficacy of HDL manipulation in cardiovascular disease.

Purpose of the Study:

• To investigate the impact of ectopic macrophage apoAI expression on atherosclerosis and dermatitis in a mouse model.
• To determine if targeting macrophages with apoAI can ameliorate inflammatory conditions independent of systemic HDL levels.

Main Methods:

• Hematopoietic progenitor cells were engineered to express human apoAI and transplanted into LDL receptor(-/-)/apoAI(-/-) mice.
• Mice were subjected to a high-fat diet for 16 weeks to induce hypercholesterolemia and dermatitis.
• Aortic and skin tissues, along with lymph nodes, were analyzed for cholesterol levels, lesion size, immune cell infiltration, and specific T-cell populations.

Main Results:

• Macrophage apoAI expression significantly reduced aortic lesion size and necrotic core area, along with CD4(+) T-cell levels, without affecting serum HDL or macrophage counts.
• Skin cholesterol levels decreased by 39.8%, skin morphology was restored, and skin CD4(+) T-cell infiltration was reduced.
• ApoAI expression in macrophages specifically lowered CD4(+) T-cell counts in skin-draining lymph nodes, sparing other immune cell types.

Conclusions:

• Targeted expression of apoAI in macrophages offers protection against atherosclerosis and dermatitis.
• This strategy effectively reduces tissue cholesterol accumulation and modulates CD4(+) T-cell responses.
• Macrophage-specific apoAI expression presents a potential therapeutic avenue for inflammatory diseases, independent of systemic HDL modulation.