Satoh M, Matsumura T, Nakamoto M, Yamazaki M
Faculty of Pharmaceutical Sciences, Teikyo University, Kanagawa, Japan.
J Immunol. 1995 Jul 15;155(2):877-85.
Recent studies have revealed that animals have evolved a wide range of protective systems against the deleterious effects of LPS, but the molecular mechanisms in the barrier functions of liver against enterobacterial LPS, particularly in mammals, are poorly understood. In this study, we extracted a soluble fraction from the liver of normal mice (normal liver extract, NLE) and examined its effect on biologic activities of LPS. Preincubation of NLE and LPS suppressed serum-dependent TNF induction (TNF-triggering activity) of LPS; the effect was dose-dependent and overcome by increasing LPS concentration, but treatment of macrophages with NLE showed no effect. Separation by ultrafiltration and protease sensitivity demonstrated that the factor(s) in NLE was a protein(s). We tentatively called this liver LPS-inactivating factor (LLIF). LPS inactivation by LLIF was temperature-dependent and required the coexistence of divalent cations. LLIF also suppressed a synthetic lipid A analogue, ONO-4007. Pretreatment of LPS with serum rendered LPS refractory to the action of LLIF. However, LLIF was unable to inhibit limulus amebocyte lysate activation by LPS. Direct interaction of LLIF and lipid A was evident by the method of [1-14C]ONO-4007 binding to solid-phase LLIF, but treatment of [1-14C]ONO-4007 with LLIF generated no degradative products. These results suggest that LLIF probably interacts with the lipid A portion of LPS and interferes with the association of LPS and LBP (LPS-binding protein) in serum, and that LLIF may be one of the protective molecules in liver against the gastrointestine-derived LPS.
最近的研究表明，动物已经进化出多种针对脂多糖（LPS）有害影响的保护系统，但肝脏针对肠道细菌LPS的屏障功能的分子机制，尤其是在哺乳动物中，仍知之甚少。在本研究中，我们从正常小鼠肝脏中提取了一种可溶性组分（正常肝脏提取物，NLE），并检测了其对LPS生物学活性的影响。NLE与LPS预孵育可抑制LPS的血清依赖性肿瘤坏死因子诱导（TNF触发活性）；该效应呈剂量依赖性，且可通过增加LPS浓度来克服，但用NLE处理巨噬细胞则无效果。通过超滤分离和蛋白酶敏感性分析表明，NLE中的因子是一种蛋白质。我们暂将此称为肝脏LPS失活因子（LLIF）。LLIF介导的LPS失活具有温度依赖性，且需要二价阳离子共存。LLIF还可抑制一种合成脂多糖类似物ONO-4007。用血清对LPS进行预处理可使LPS对LLIF的作用产生抗性。然而，LLIF无法抑制LPS对鲎试剂的激活。通过[1-14C]ONO-4007与固相LLIF结合的方法可明显看出LLIF与脂多糖A之间的直接相互作用，但用LLIF处理[1-14C]ONO-4007未产生降解产物。这些结果表明，LLIF可能与LPS的脂多糖A部分相互作用，并干扰LPS与血清中LBP（LPS结合蛋白）的结合，且LLIF可能是肝脏中抵御源自胃肠道的LPS的保护分子之一。
