Cromheeke K M, Kockx M M, De Meyer G R, Bosmans J M, Bult H, Beelaerts W J, Vrints C J, Herman A G
Department of Cardiology, University Hospital, Antwerp, Belgium.
Cardiovasc Res. 1999 Aug 15;43(3):744-54. doi: 10.1016/s0008-6363(99)00148-0.
Advanced human atherosclerotic plaques are characterized by the abundant presence of the autofluorescent non-soluble lipid pigment ceroid, consisting of oxidized lipoproteins. The aim of the present study was to examine the topographical and cellular distribution of inducible nitric oxide synthase (iNOS or NOS II) within different stages of atherosclerosis and its colocalization with ceroid deposits and nitrotyrosine.
Different stages of atherosclerosis were studied by immunohistochemistry on whole-mount longitudinal sections of carotid endarterectomy specimens. In the adaptive intimal thickening the predominant cell type were smooth muscle cells. The fatty streaks contained both smooth muscle cells and macrophages with an extremely low NOS II immunoreactivity. The advanced atherosclerotic plaques however, showed a very dense infiltration by macrophages, of which a subpopulation expressed NOS II as a vesicular immunoreactivity in their cytoplasm. These were mainly present around the necrotic core, in association with ceroid accumulation and nitrotyrosine. Fluorescence quenching microscopy showed the presence of NOS II on autofluorescent ceroid vesicles in the macrophages. Large extracellular ceroid granules were not NOS II immunoreactive. NOS II mRNA was detected by RT-PCR and the protein by Western blot in the plaque tissue but not in mammary arteries used as controls.
Ceroid, nitrotyrosine and NOS II colocalized in late stages of atherosclerosis and were found around the necrotic core in the plaque. This could suggest that NOS II expression in macrophages is involved in oxidation and peroxidation of lipids, leading to ceroid formation.
晚期人类动脉粥样硬化斑块的特征是存在大量自发荧光的不溶性脂质色素脂褐素，其由氧化脂蛋白组成。本研究的目的是检测诱导型一氧化氮合酶（iNOS或NOS II）在动脉粥样硬化不同阶段的拓扑和细胞分布，及其与脂褐素沉积物和硝基酪氨酸的共定位。
通过对颈动脉内膜切除术标本的全层纵切片进行免疫组织化学研究动脉粥样硬化的不同阶段。在适应性内膜增厚中，主要细胞类型是平滑肌细胞。脂肪条纹中既有平滑肌细胞又有巨噬细胞，NOS II免疫反应性极低。然而，晚期动脉粥样硬化斑块显示巨噬细胞密集浸润，其中一部分亚群在其细胞质中以囊泡免疫反应性表达NOS II。这些主要存在于坏死核心周围，与脂褐素积累和硝基酪氨酸相关。荧光猝灭显微镜显示巨噬细胞中自发荧光脂褐素囊泡上存在NOS II。大的细胞外脂褐素颗粒无NOS II免疫反应性。通过RT-PCR在斑块组织中检测到NOS II mRNA，通过蛋白质印迹法检测到蛋白质，但在用作对照的乳腺动脉中未检测到。
脂褐素、硝基酪氨酸和NOS II在动脉粥样硬化晚期共定位，且在斑块的坏死核心周围被发现。这可能表明巨噬细胞中NOS II的表达参与脂质的氧化和过氧化，导致脂褐素形成。
