ROLE OF CYTOKINES AND GROWTH FACTORS ON THE PATHOGENESIS OF XANTHOMA

得到了两种氧化修饰的低密度脂蛋白。一种是从兔黄瘤组织中提取的低密度脂蛋白组分，另一种是与兔黄瘤组织孵育的人血清低密度脂蛋白。这些低密度脂蛋白已被发现是氧化修饰的。人血单核细胞和U-937细胞系在体外向巨噬细胞分化。用两种低密度脂蛋白孵育巨噬细胞后，用EASLA法检测培养上清液中IL-1、干扰素-γ、肿瘤坏死因子-α和GM-CSF的水平。两种氧化修饰的低密度脂蛋白均抑制巨噬细胞IL-1的合成，刺激干扰素-γ的合成，但对巨噬细胞的肿瘤坏死因子-α的合成无影响。这些结果表明，氧化低密度脂蛋白处理的巨噬细胞不被刺激合成促进黄瘤的细胞因子(IL-1和TNF-α)，而被刺激合成保护黄瘤的细胞因子(干扰素-γ)。用抗ICAM-1、抗VCAM-1和抗ELAM-1抗体对人脐静脉内皮细胞(HUVEC)进行免疫组织化学染色，流式细胞仪检测细胞ICAM-1、VCAM-1和ELAM-1的表达。人脐静脉内皮细胞经低密度脂蛋白刺激后，VCAM-1和ELAM-1均呈剂量依赖性表达，而ICAM-1则未见表达。这些结果提示，氧化型低密度脂蛋白直接诱导内皮细胞表达VCAM-1或ELAM-1，从而介导单核细胞与内皮细胞的黏附。在表达黏附分子的细胞中未发现NFkB的激活。

Two kinds of oxidatively modified LDLs were obtained. One was the LDL fraction extracted from himogenized rabbit xanthoma tissues and the other was human serum LDL which had been incubated with rabbit xanthoma tissues. These LDLs have been revealed to be oxidatively modified. Human blood monocytes and U-937 cell line were differentiated to macrophages in vitro. After an incubation of these macrophages with the two kinds of LDLs, IL-1, IFN-gamma, TNF-alpha and GM-CSF levels in the medium were assayd by the EASLA method. Both two types of oxidatively modified LDLs suppressed the IL-1 synthesis, stimulated the IFN-gamma synthesis and geve no effects on the TNF-alpha synthesis by these macrophages. These findings suggest that oxidized-LDL treated macrophages are not stimulated to synthesize the xanthoma promoting cytokines (IL-1 and TNF-alpha) and are stimulated to synthesize the xanthoma protecting cytokines (IFN-gamma). On the other hand, the synthesis of xanthoma promoting GM-CSF by macrophages are stimulated by these LDLs.Human umbilical vein endothelial cells (HUVEC) were immunohistochemically stained using anti-ICAM-1, anti-VCAM-1 and anti-ELAM-1 antibodies after an incubation with the xanthoma tissue-modified LDL.Expression of ICAM-1, VCAM-1 and ELAM-1 on the HUVEC was investigated by flow cytometry. Both VCAM-1 and ELAM-1 were dose-dependently expressed on the HUVEC by a stimuation with the LDL.On the other hand, ICAM-1 expression was never observed. These results suggest that oxidized LDL directly elicit the endothelial cell expression of VCAM-1 or ELAM-1 which mediate the adhesion of blood monocytes to endothelial cells. NFkB activation in the adhesion molecule expressing cells was not revealed.