Analysis of mechanism of activation of kupffer cells in the liver

本研究的目的是确定GdCl3如何影响KC功能，并进一步研究KC产生的细胞因子如TNF-α或IL-6与LPS给药后这些细胞因子水平之间的相关性。给予或不给予GdCl3的大鼠LPS或生理盐水溶液。在LPS给药后的每个时间点采集主动脉血清样本，测量TNF-α和IL-6。此外，收集肝组织进行病理评估和免疫组织化学。此外，分离的KCs被用于评估吞噬作用、超氧化物和炎症细胞因子的产生。LPS处理后所有动物均死亡，但GdCl3完全阻止了这种死亡。两组血清TNF-α水平均迅速升高，但差异无统计学意义。与GdCl3相比，载药大鼠IL-6水平逐渐升高，且显著高于GdCl3。大KCs比小KCs表现出更强的吞噬作用。LPS使分离的KCs产生的超氧化物和TNF-α增加。在小kc中没有观察到这些增加。此外，LPS或TNF-α刺激增加了IL-6的产生；然而，该数值在小KC中明显高于大KC。ed2阳性细胞主要在肝脏中观察到一些ED1阳性细胞。LPS后EDI阳性细胞增加，但ED2阳性细胞未增加。因此，在肝巨噬细胞中观察到功能异质性。大KC可能是常驻的肝巨噬细胞，小KC可能是浸润到肝脏的外周单核细胞/巨噬细胞。活化的大KCs衍生的TNF-α可活化小KCs。随后，这些小KCs向肺、肾等其他器官募集，产生大量IL-6，导致器官损伤和多器官衰竭。因此，肝脏可能是炎症免疫系统的中心器官。

The purpose of this study was to determine how GdCl3 affects Kupffer cell (KC) function and further to investigate a correlation between cytokine productions such as TNF-α or IL-6 by KC and those cytokine levels after LPS administration. Rats with or without GdCl3 were received LPS or saline vehicle. Serum samples were collected from the aorta at each time point after LPS administration for TNF-α and IL-6 measurements. Further, liver tissues were collected for pathological evaluation and immunohistochemistry. Moreover, isolated KCs were used for evaluation of phagocytosis, and production of superoxide and inflammatory cytokines. All animals died after LPS administration but GdCl3 prevented this mortality completely. TNF-α levels were increased rapidly by LPS in both groups without differences. In contrast, IL-6 levels were increased gradually and values were significantly greater in rats treated with vehicle than GdCl3. Large KCs showed greater phagocytosis than small KCs. Superoxide and TNF-α productions by isolated KCs were increased by LPS.These increases were not observed in the small KC.Further, LPS or TNF-α stimulation increased IL-6 production ; however values were significantly greater in the small KC than the large KC.ED2 positive cells were observed predominantly with some ED1 positive cells in the liver. Further EDI positive cells were increased after LPS but not ED2. Thus, functional heterogeneity was observed in the hepatic macrophage. The Large KC may be the resident hepatic macrophage and the small KC may be the peripheral monocyte/macrophage infiltrating into the liver. TNF-α derived from activated large KCs could activate small KCs. Subsequently, these small KCs are recruiting to other organs such as lung and kidney, and produce large amount of IL-6 leading to organ injuries and multiple organ failures. Thus, the liver could be the central organ in the inflammatory immune system.