Clinton S K, Underwood R, Hayes L, Sherman M L, Kufe D W, Libby P
Laboratory of Clinical Pharmacology, Dana-Farber Cancer Institute, Boston, MA 02115.
Am J Pathol. 1992 Feb;140(2):301-16.
The infiltration of monocytes into the vascular wall and their transformation into lipid-laden foam cells characterizes early atherogenesis. Macrophages are also present in more advanced human atherosclerotic plaques and can produce many mediators that may contribute to lesion formation and progression. Macrophage colony-stimulating factor (MCSF) enhances the proliferation and differentiation of monocyte progenitors and is required for the survival and activation of mature monocytes and macrophages. The authors therefore examined the expression of the MCSF gene in cultured human vascular endothelial (EC) and smooth muscle cells (SMC) as well as in atheromatous lesions from rabbits and humans. Growth arrested EC and SMC contain a low level of MCSF mRNA. Bacterial lipopolysaccharide (LPS), recombinant human interleukin-1 alpha (IL-1 alpha) or tumor necrosis factor alpha (TNF alpha) induced MCSF mRNA accumulation in a concentration-dependent manner in both EC and SMC. These stimuli induced large increases in MCSF mRNA with peak induction between 4-8 hours after treatment. LPS, IL-1 alpha, and TNF alpha stimulated EC and SMC also showed increased fluorescent antibody staining for MCSF protein and released immunoreactive MCSF in a time-dependent manner. In contrast, phorbol 12-myristate 13-acetate (PMA) was a less potent inducer of MCSF gene expression and iron-oxidized low-density lipoproteins (ox-LDL) did not increase consistently MCSF mRNA or the synthesis and secretion of immunoreactive protein. Northern analysis of mRNA isolated from the atheromatous aorta of rabbits fed a 1% cholesterol diet for 10 weeks showed elevated MCSF mRNA compared with controls. Immunostaining of atheromatous arterial lesions of rabbits demonstrated MCSF protein in association with intimal SMC as well as macrophages. Furthermore, polymerase chain reaction (PCR) analysis of MCSF mRNA in human atheromata showed higher levels than found in nonatherosclerotic arteries and veins. Since the authors found no mRNA for the MCSF receptor, c-fms, in cultured EC or SMC macrophages are likely the primary target for MCSF within atheromatous vessels. The authors therefore investigated the effects of MCSF on monocyte functions related to foam cell development. Treatment of cultured human monocytes with recombinant human MCSF (10(3) U/ml, 72 hr) led to the accumulation of mRNA for the acetyl-LDL (scavenger) receptor and apolipoprotein E (apo E). These studies establish that vascular EC and SMC produce substantial MCSF in response to a variety of stimuli. The local production of MCSF during atherogenesis may contribute to macrophage survival and proliferation or activate specific macrophage functions such as expression of the scavenger receptor and secretion of apo E.
单核细胞浸润至血管壁并转化为富含脂质的泡沫细胞是早期动脉粥样硬化形成的特征。巨噬细胞也存在于更晚期的人类动脉粥样硬化斑块中，并且能产生许多可能有助于病变形成和进展的介质。巨噬细胞集落刺激因子（MCSF）可增强单核细胞祖细胞的增殖和分化，是成熟单核细胞和巨噬细胞存活及激活所必需的。因此，作者检测了MCSF基因在培养的人血管内皮细胞（EC）和平滑肌细胞（SMC）以及兔和人的动脉粥样硬化病变中的表达。生长停滞的EC和SMC含有低水平的MCSF mRNA。细菌脂多糖（LPS）、重组人白细胞介素-1α（IL-1α）或肿瘤坏死因子α（TNFα）以浓度依赖的方式诱导EC和SMC中MCSF mRNA的积累。这些刺激导致MCSF mRNA大幅增加，在处理后4 - 8小时诱导达到峰值。LPS、IL-1α和TNFα刺激的EC和SMC也显示出MCSF蛋白的荧光抗体染色增加，并以时间依赖的方式释放免疫反应性MCSF。相比之下，佛波酯12 - 肉豆蔻酸酯13 - 乙酸酯（PMA）是MCSF基因表达的较弱诱导剂，而铁氧化低密度脂蛋白（ox-LDL）并不能持续增加MCSF mRNA或免疫反应性蛋白的合成与分泌。对喂食1%胆固醇饮食10周的兔的动脉粥样硬化主动脉中分离的mRNA进行Northern分析显示，与对照组相比，MCSF mRNA升高。兔动脉粥样硬化病变的免疫染色显示MCSF蛋白与内膜SMC以及巨噬细胞相关。此外，对人动脉粥样硬化斑块中MCSF mRNA的聚合酶链反应（PCR）分析显示其水平高于非动脉粥样硬化的动脉和静脉。由于作者在培养的EC或SMC中未发现MCSF受体c-fms的mRNA，巨噬细胞可能是动脉粥样硬化血管内MCSF的主要靶细胞。因此，作者研究了MCSF对与泡沫细胞形成相关的单核细胞功能的影响。用重组人MCSF（10³ U/ml，72小时）处理培养的人单核细胞导致乙酰-LDL（清道夫）受体和载脂蛋白E（apo E）的mRNA积累。这些研究表明，血管EC和SMC在受到多种刺激时会产生大量MCSF。动脉粥样硬化形成过程中MCSF的局部产生可能有助于巨噬细胞的存活和增殖，或激活特定的巨噬细胞功能（如清道夫受体的表达和apo E的分泌）。
