内分泌
词汇介绍
拓展阅读
解析
Lipopolysaccharide 英 /ˌlʌɪpəʊpɒlɪˈsakərʌɪd/ 美 /ˌlʌɪpəʊpɒlɪˈsakərʌɪd/
释 义 n. [有化] 脂多糖
例 句 It recognizes lipopolysaccharide, a component of the outer membrane of Gram-negative bacteria. 它识别广泛存在革兰氏阴性菌细胞外膜上的脂多糖。
概述
概述
脂多糖（LPS），也称为脂聚糖和内毒素，是大的分子组成的脂质和多糖的O-抗原，它们存在于革兰氏阴性细菌的外膜中。保持在细菌细胞内，并且仅在破坏细菌细胞壁后才释放。随后的研究表明，从革兰氏阴性菌中释放LPS 不一定需要破坏细菌细胞壁，相反，LPS作为膜囊泡运输的正常生理活性的一部分以下列形式分泌：细菌外膜囊泡（OMV），也可能包含其他毒力因子和蛋白质。
组成
O抗原：LPS中包含的重复聚糖聚合物称为细菌的O抗原，O多糖或O侧链。O抗原连接至核心寡糖，并包含LPS分子的最外层结构域。O链的组成因菌株而异。
核心：核心结构域总是包含直接连接到一个寡糖成分脂质A和通常含有糖如庚糖和3-脱氧-D-甘露-辛-2-糖酸（也称为KDO）。许多细菌的LPS核心还包含非碳水化合物成分，例如磷酸盐，氨基酸和乙醇胺取代基。
脂质A ：脂质A是，在正常情况下，一个磷酸葡萄糖胺糖饰以多种脂肪酸。这些疏水性脂肪酸链将LPS锚定在细菌膜中，其余LPS从细胞表面突出。脂质A结构域是革兰氏阴性细菌大部分毒性的原因。当细菌细胞被免疫系统溶解时，含有脂质A的膜碎片会释放到循环系统中，从而引起发烧，腹泻以及可能致命的内毒素性休克（也称为败血性休克）。脂质A部分是LPS的非常保守的组分。然而，脂质A结构在细菌物种之间变化，并且脂质A结构定义了总体宿主免疫活化。
免疫反应
LPS可以作为原型内毒素，因为它可以在许多细胞类型中结合CD14/ TLR4 / MD2 受体复合物，特别是在单核细胞，树突状细胞，巨噬细胞和B细胞中，这可以促进促炎性细胞因子，一氧化氮和类二十烷酸的分泌。作为细胞应激反应的一部分，过氧化物是LPS在表达TLR（toll样受体）的各种细胞类型中诱导的主要活性氧之一。LPS也是一种外源热原（发烧物质）。对于革兰氏阴性细菌至关重要，这些分子成为新的抗菌剂的候选靶标。
LPS功能在激活许多转录因子中的作用已经进行了多年的实验研究。LPS还产生许多类型的与败血性休克有关的介体。与其他动物（例如小鼠）相比，人类对LPS更加敏感。1µg/kg的剂量会引起人类休克，但是小鼠最多可以耐受一千倍。这可能与两个物种之间循环天然抗体水平的差异有关。Said等研究发现LPS 通过上调单核细胞上的PD-1水平引起IL-10依赖性的CD4 T细胞扩增和功能抑制其通过PD-1结合后会导致IL-10产生的单核细胞通过PD-L1。
内毒素在很大程度上导致了致病性革兰氏阴性细菌（如脑膜炎奈瑟氏球菌）感染的相关性临床表现，脑膜炎奈瑟氏球菌是引起脑膜炎球菌病的病原体，包括脑膜炎球菌血症，沃特豪斯-弗里德里希森综合征和脑膜炎。
复制标题人肾周脂肪间充质基质/干细胞隔离、鉴定、分化和免疫调节能力
发表时间：2019-10-29
影响指数：5.7
作者： Patrick C Baer
期刊：Cells
Recent data have suggested that adipose tissue located in different anatomical locations of the body appear to have distinct cellular compositions and diverse functions. In humans, fat depot-specific differences are clinically relevant owing to the observation that increased abdominal white fat is associated with insulin resistance, while subcutaneous white adipose tissue exerts a protective effect against metabolic syndrome. Para- and perirenal adipose tissue is a fat pad located in the retroperitoneal space. Perirenal fat is separated from pararenal fat by the renal fascia, and surrounds each kidney. It is a collection of adipose tissue located superficial to the renal cortex and is part of the visceral fat, which can be divided into perirenal, gonadal, epicardial, retroperitoneal, omental and mesenteric fat depots. They are composed mainly of white adipose cells that store energy and produce soluble inflammatory cytokines. Perirenal fat shares the same developmental origin as typical visceral fat. However, each white adipose tissue depot can be described as a separate mini-organ, and perirenal fat and typical visceral fat are different in histology, physiology and functions. The vascularization of perirenal adipose tissue grows from branches of the abdominal aorta, which also supplies blood to the kidney cortex. Therefore, effects on renal cells through soluble factor released by cells from the perirenal adipose tissue are possible. Renal adipose tissue has been linked recently to effects on kidney function and blood hypertension and a neuronal link from perirenal adipose tissue to multiple central nervous system’s regions has been shown in animal data. Perirenal tissue is rarely analyzed for viral infections, however MSC from selected organs other than perirenal tissue show susceptibility and permissiveness for human cytomegalovirus (HCMV) infection. The object of this study was to describe the isolation and culture of human perirenal adiposederived stromal/stem cells (prASCs) in detail and to characterize cultured cells and their differentiation potential into adipocytes, chondrocytes, osteoblasts and epithelial cells. The present study further investigated the immunomodulatory potential of prASCs after stimulation with lipopolysaccharide (LPS), lipoteichoic acid (LTA), a mixture of cytokines (cytomix), or infection with HCMV. Whereas, few studies used human prASCs in vitro, there is currently no other study which fully described the isolation, characterization, differentiation and immunomodulatory potential of human prASCs as well as their susceptibility to HCMV.
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