Ikeda U, Maeda Y, Funayama H, Hojo Y, Ikeda M, Minota S, Kano S, Shimada K
Department of Cardiology, Jichi Medical School, Tochigi, Japan.
Cardiovasc Res. 1998 Mar;37(3):820-5. doi: 10.1016/s0008-6363(97)00265-4.
The adhesive interaction of monocytes and vascular smooth muscle cells (VSMCs) has been suggested to be a regulatory signal in the cellular activation that is involved in the pathogenesis of atherosclerosis. We investigated the effects of monocyte-VSMC interaction on inducible nitric oxide (NO) synthase expression.
NO production by the cultured cells was determined by measuring the nitrite content of the culture media using the Griess reagent. The expression of inducible NO synthase protein was assayed by Western blotting.
Interleukin-1 beta (IL-1 beta) induced nitrite production by VSMCs in a time-dependent manner. The addition of the mouse monocyte cell line J774 to IL-1 beta-stimulated VSMCs further increased nitrite production in a monocyte number-dependent manner. Enhanced nitrite production by coculture was accompanied by increased inducible NO synthase protein accumulation. Addition of tumor necrosis factor-alpha (TNF-alpha) also enhanced IL-1 beta-induced nitrite production by VSMCs, but TNF-alpha showed no effect in the presence of monocytes. Coculture of monocytes and VSMCs in the presence of IL-1 beta secreted substantial amounts of TNF-alpha. The production of nitrite by coculture was markedly inhibited by an anti-TNF-alpha antibody.
The present study revealed that direct cell-to-cell interaction between monocytes and VSMCs enhances NO production, suggesting an important role for their interaction in the pathogenesis of atherosclerosis.
单核细胞与血管平滑肌细胞（VSMC）之间的黏附相互作用被认为是细胞活化过程中的一种调节信号，参与动脉粥样硬化的发病机制。我们研究了单核细胞与VSMC相互作用对诱导型一氧化氮（NO）合酶表达的影响。
通过使用格里斯试剂测量培养基中的亚硝酸盐含量来测定培养细胞产生的NO。通过蛋白质免疫印迹法检测诱导型NO合酶蛋白的表达。
白细胞介素-1β（IL-1β）以时间依赖性方式诱导VSMC产生亚硝酸盐。将小鼠单核细胞系J774添加到IL-1β刺激的VSMC中，以单核细胞数量依赖性方式进一步增加亚硝酸盐的产生。共培养增强的亚硝酸盐产生伴随着诱导型NO合酶蛋白积累的增加。添加肿瘤坏死因子-α（TNF-α）也增强了IL-1β诱导的VSMC亚硝酸盐产生，但在存在单核细胞的情况下，TNF-α没有作用。在IL-1β存在下，单核细胞与VSMC的共培养分泌大量TNF-α。共培养产生的亚硝酸盐被抗TNF-α抗体显著抑制。
本研究表明，单核细胞与VSMC之间直接的细胞间相互作用增强了NO的产生，提示它们的相互作用在动脉粥样硬化发病机制中起重要作用。
