本文選題：慢性炎癥　切入點：脂質代謝紊亂　出處：《重慶醫(yī)科大學》2008年博士論文

【摘要】：目的低度慢性系統(tǒng)性炎癥反應是代謝綜合征（MS）的核心點和幾項組成成份（如血糖、血脂及尿酸等）的連接點，炎癥因子參與脂質代謝障礙的全過程。固醇調節(jié)元件結合蛋白（SREBPs）是核轉錄因子，SREBP裂解激活蛋白（SCAP）是內質網上的膜蛋白，SCAP對SREBPs的活性起著重要的調節(jié)作用；細胞是通過一個依賴于胞內膽固醇水平的反饋調節(jié)系統(tǒng)來控制膽固醇內穩(wěn)態(tài)平衡，即主要通過SCAP-SREBPs-LDLR之間的相互作用實現對細胞內脂質穩(wěn)態(tài)平衡的調節(jié)。體外實驗證實炎癥因子可通過干擾膽固醇介導的低密度脂蛋白受體反饋調節(jié)來促進外周細胞，如血管平滑肌細胞（VSMCs）的膽固醇攝入，從而導致膽固醇在外周細胞的異常聚集而形成泡沫細胞。乙酰CoA羧化酶（ACC）與脂肪酸合成酶（FAS）是甘油三酯（TG）合成的關鍵酶，肝臟TG的代謝是通過SCAP-SREBPs-ACC/FAS途徑實現的，肝臟脂質代謝障礙主要是TG在肝細胞內異常聚集而形成以大泡性為主的肝細胞脂肪變性，可伴有炎癥細胞浸潤和/或纖維組織增生，炎癥因子是否干擾ACC與FAS的表達而導致TG代謝障礙的機制目前仍不清楚。本實驗在過去體外細胞實驗的基礎上，建立慢性炎癥動物模型，探討炎癥狀態(tài)下血脂代謝紊亂情況；炎癥因子是否通過干擾SCAP-SREBPs介導的LDLR反饋調節(jié)促進脂質攝取，從而導致主動脈與肝臟脂質聚集。 材料和方法利用8周齡C57BL/6J小鼠皮下注射酪蛋白（Casein）制作小鼠慢性炎癥模型，分別給予普通飲食、高脂飲食飼養(yǎng)20周左右，提取血液、肝臟及主動脈進行下列實驗；用酶學方法檢測各組小鼠IL-6及血脂（包括TC、LDL-C、HDL-C及TG）水平；HE染色、ORO染色及Masson三色染色觀察肝臟與主動脈形態(tài)學改變；根據NAFLD、NASH分級與分期標準對各組小鼠肝臟進行分級和分期；利用Real-time PCR技術定量檢測肝臟LDLR、SCAP、SREBP2、SREBP1、ACC及FAS mRNA水平以及主動脈LDLR、SCAP、SREBP2mRNA水平； Western blotting檢測肝臟LDLR、SCAP、SREBP1蛋白及主動脈LDLR、SCAP、SREBP2蛋白表達水平。 結果1. C57BL/6J小鼠皮下注射Casein后，普通飲食和高脂飲食小鼠血清IL-6均顯著升高。 2.在普通飲食組中除單純普通飲食小鼠血清TC輕微下降外，LDL、HDL、及TG均明顯下降；高脂飲食各項血脂指標（TC、LDL、HDL及TG）均明顯下降。這些數據說明慢性炎癥狀態(tài)可導致血脂紊亂。 3.與普通飲食組相比，，單純高脂飲食顯著抑制主動脈和肝臟LDLR、SCAP和SREBP2mRNA與蛋白的表達，但在慢性炎癥狀態(tài)下，LDLR、SCAP和SREBP2mRNA與蛋白的顯著提高，這提示慢性炎癥狀態(tài)可干擾細胞膽固醇代謝。 4.單純高脂飲食組小鼠SREBP1、ACC及FAS基因表達升高，在慢性炎癥狀態(tài)下，SREBP1、ACC及FAS表達進一步提高，肝細胞攝取大量的TG，從而導致肝細胞脂肪變性、氣球樣變、肝細胞壞死及纖維組織增生，即形成NAFLD或者NASH。 5．單純高脂飲食組小鼠主動脈根部內膜明顯增厚，大量泡沫細胞形成及動脈粥樣硬化斑塊形成；在慢性炎癥狀態(tài)下，主動脈根部動脈粥樣硬化斑塊明顯增厚，斑塊面積更大，這說明炎癥可加重主動脈損害。 1結論1．IL-6是炎癥反應的敏感標記物，IL-6的高低與炎癥反應程度密切相關,血清IL-6顯著升高提示慢性炎癥模型成功建立。 2．體內慢性炎癥狀態(tài)通過干擾SCAP-SREBP2-LDLR反饋調節(jié)系統(tǒng)，促進脂質攝取，從而導致主動脈與肝臟脂質聚集。這些數據表明慢性炎癥狀態(tài)可明顯降低血脂水平；慢性炎癥狀態(tài)下沒有一個安全的血漿膽固醇濃度，血漿膽固醇水平并不與細胞內膽固醇水平呈正相關。 3．炎癥狀態(tài)促進SREBP1、ACC及FAS的表達而使肝細胞內大量TG聚集，導致肝細胞脂肪變性，壞死及纖維化，故炎癥狀態(tài)可加重肝臟損害。
[Abstract]:The purpose of low-grade chronic systemic inflammation is a metabolic syndrome (MS) of the core and several components (such as blood glucose, blood lipid and uric acid) of the connection point, the whole process of inflammatory factors involved in lipid metabolism. The sterol regulatory element binding protein (SREBPs) is a nuclear transcription factor, SREBP cleavage activating protein (SCAP) is a membrane protein of the endoplasmic reticulum, SCAP activity of SREBPs plays an important role in regulating the cell; through a cholesterol level dependent on intracellular feedback to control cholesterol homeostasis balance system, mainly through the interaction between SCAP-SREBPs-LDLR to achieve the regulation of intracellular lipid homeostasis in vitro. Low density lipoprotein receptor in inflammatory cytokines by disrupting cholesterol mediated feedback regulation to promote peripheral cells, such as vascular smooth muscle cells (VSMCs) of the intake of cholesterol, resulting in cholesterol In the abnormal aggregation of peripheral cells and the formation of foam cells. Acetyl CoA carboxylase (ACC) and fatty acid synthase (FAS) is a key enzyme in the synthesis of triglycerides (TG), the liver metabolism of TG is achieved through SCAP-SREBPs-ACC/FAS pathway, liver lipid metabolism disorder is the main accumulation of TG in the liver cells and abnormal form bullous mainly fatty degeneration of liver cells, can be accompanied by inflammatory cell infiltration and / or hyperplasia of fibrous tissue, the expression of inflammatory cytokines ACC and FAS whether the interference caused by the mechanism of TG metabolism is not clear. In this experiment the past in vitro cell experiments, the establishment of animal model of chronic inflammation, investigate the disorder of blood lipid the metabolism of inflammation; inflammatory cytokines by SCAP-SREBPs mediated interference LDLR feedback regulation to promote lipid uptake, leading to aortic and hepatic lipid accumulation.
Materials and methods using 8 week old C57BL/6J mice by subcutaneous injection of casein (Casein) production of chronic inflammation model in mice, which were fed with normal diet, high fat diet for 20 weeks or so, extraction of blood, liver and aorta of the experimental mice were detected by enzymatic method; IL-6 and blood lipid (including TC, LDL-C, HDL-C and TG) level; HE staining, to observe the changes of liver and aortic morphology ORO staining and Masson staining; according to NAFLD, on mice liver grading and staging NASH grading and staging criteria; using quantitative Real-time PCR detection of liver LDLR, SCAP, SREBP2, SREBP1, ACC and FAS mRNA level and SCAP level of SREBP2mRNA, aortic LDLR, Western; blotting detection of liver LDLR, SCAP, SREBP1, SCAP, LDLR protein and aortic, the expression of SREBP2 protein.
Results after subcutaneous injection of Casein in 1. C57BL/6J mice, the serum IL-6 of the normal diet and the high fat diet mice increased significantly.
2., in the general diet group, except for a slight decrease in serum TC level, LDL, HDL and TG decreased significantly. The blood lipid indexes (TC, LDL, HDL and TG) of high-fat diet decreased significantly. These data indicate that chronic inflammation can lead to dyslipidemia.
3., compared with the normal diet group, the high-fat diet significantly inhibited the expression of LDLR, SCAP and SREBP2mRNA and protein in aorta and liver, but in chronic inflammatory state, LDLR, SCAP and SREBP2mRNA increased significantly with protein. This indicates that chronic inflammation can interfere with cholesterol metabolism in cells.
4. simple high-fat diet group mice SREBP1, ACC and FAS gene expression increased, SREBP1 in chronic inflammatory conditions, ACC, and FAS expression to further improve the hepatic uptake amounts of TG, which leads to hepatic steatosis, ballooning degeneration, necrosis of liver cells and fibrous tissue hyperplasia, the formation of NAFLD or NASH.
5. simple high-fat diet group mice aortic intima was obviously thickened, a large number of foam cell formation and the formation of atherosclerotic plaque; in chronic inflammatory conditions, aortic atherosclerotic plaque thickening, larger plaque area, suggesting that inflammation can aggravate the main artery damage.
1 conclusion 1.IL-6 is a sensitive marker of inflammatory reaction. The level of IL-6 is closely related to the degree of inflammatory reaction. Serum IL-6 is significantly elevated, suggesting that the chronic inflammation model is successfully established.
2. in the state of chronic inflammation by interfering with SCAP-SREBP2-LDLR feedback regulation system, promote lipid uptake, resulting in accumulation of aorta and liver lipid. These data suggest that chronic inflammation can significantly reduce blood lipid level; chronic inflammation is not a safe plasma cholesterol concentration, plasma cholesterol levels and not intracellular cholesterol levels were positively correlated.
3., inflammatory state promotes the expression of SREBP1, ACC and FAS, and makes a large number of TG aggregation in liver cells, resulting in steatosis, necrosis and fibrosis of liver cells. Therefore, inflammation can aggravate liver damage.

【學位授予單位】：重慶醫(yī)科大學
【學位級別】：博士
【學位授予年份】：2008
【分類號】：R363

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相關期刊論文 前2條

1 范建高;第二講 非酒精性脂肪肝的臨床流行病學研究[J];中華消化雜志;2002年02期

2 ;Mechanisms of dysregulation of low-density lipoprotein receptor expression in HepG2 cells induced by inflammatory cytokines[J];Chinese Medical Journal;2007年24期

本文編號：1696979