Differentiation and fate of monocytes in atherosclerosis

动脉粥样硬化是一种弹性动脉和肌肉动脉的慢性炎症性疾病。在动脉粥样硬化的早期，聚集的氧化的脂蛋白颗粒附着在受影响动脉内皮下基质中的蛋白质上。穿过上覆内皮的单核细胞(Me)与这些基质结合的脂蛋白颗粒接触，吞噬它们，最终摄取大量的脂肪，发育成脂质充血的巨噬细胞(MF)来源的泡沫细胞。泡沫细胞在病变中聚集，分泌促炎细胞因子，刺激进一步的Me流入。当我进入炎症部位时，许多分化成树突状细胞(DC)，这些DC拾取抗原并在几天内离开组织，将抗原呈递给引流淋巴结中的T细胞。其余的分化为MF，可以在组织中保留数月或数年。我们假设单核细胞与动脉壁细胞外基质中聚集的脂蛋白以及环境中的炎性细胞因子相互作用影响单核细胞的分化和命运。项目2将确定与基质结合脂蛋白的相互作用是否会抑制单核细胞的迁移。与这些研究人员合作，我们将确定致动脉粥样硬化环境是否扭曲了Me向流动性较低的Mf的分化和/或抑制Me、Mf和DC的运动，使它们在致动脉粥样硬化环境中停留更长时间，促进它们摄取聚集的氧化脂蛋白并发育成泡沫细胞。利用与人内皮细胞体外共培养模型预测Me、MF和DC在体内的行为和运输，我们已经找到了MF积累脂肪并呈现泡沫细胞表型的条件。我们将确定这是否是因为Me与基质中聚集的脂蛋白的相互作用扭曲了它们向静止性MF的分化，或者这是否降低了DC的流动性，使它们无法离开(目标1)。我们将确定这是否被我与IL-1b和TNFa的相互作用所模仿，后者通过分泌型鞘磷脂酶(AIM 2)刺激脂蛋白在基质中的聚集。我们将确定在动脉粥样硬化病变中发现的IL-6是否通过扭曲Me向MF的分化而损害DC的分化来促进泡沫细胞的发展(目标3)。我们将确定促进胆固醇反向运输或阻断细胞因子或其受体的作用的药物是否逆转了这些现象。

Atherosclerosis is a chronic inflammatory disease of elastic and muscular arteries. Early in the pathogenesis of atherosclerosis, aggregated, oxidized lipoprotein particles become attached to proteins in the subendothelial matrix of the affected arteries. Monocytes (Me) that traverse the overlying endothelium come into contact with these matrixbound lipoprotein particles, engulf them, and eventually take up large amounts of lipid, developing into lipid-engorged macrophage (Mf)-derived foam cells. Foam cells accumulate in the lesion, secreting pro-inflammatory cytokines that stimulate further Me influx. When Me enter a site of inflammation, many differentiate into dendritic cells (DC) that pick up antigen and leave the tissue within days to present the antigen to T cells in draining lymph nodes. The remainder differentiate into Mf, which can remain in the tissues for months or years. We hypothesize that interaction of monocytes with aggregated lipoproteins in the extracellular matrix of the arterial wall and with inflammatory cytokines in the environment affect the differentiation and fate of monocytes. Project 2 will determine whether interaction with matrix bound lipoproteins inhibits monocyte migration. Working with these investigators, we will determine whether the atherogenic environment skews the differentiation of Me into less mobile Mf and/or inhibits movement of Me, Mf, and DC so that they remain in the atherogenic environment longer, promoting their uptake of aggregated, oxidized lipoproteins and development into foam cells. Using an in vitro co-culture model with human endothelial cells that has been predictive of Me, Mf, and DC behavior and trafficking in vivo, we have found conditions under which Mf accumulate lipid and take on the phenotype of foam cells. We will determine whether this occurs because interaction of Me with aggregated lipoproteins in the matrix skew their differentiation into sedentary Mf or whether this decreases mobility of DC so they cannot leave (Aim 1). We will determine whether this is mimicked by Me interactions with IL-lb and TNFa, which stimulate the aggregation of lipoproteins in the matrix via secreted sphingomyelinase (Aim 2). We will determine whether IL-6, which has been found in atherosclerotic lesions, promotes the development of foam cells by skewing the differentiation of Me into Mf at the expense of DC (Aim 3). We will determine if agents that promote reverse cholesterol transport or block the actions of the cytokines or their receptors reverse these phenomena.