动物造模,非酒精性脂肪性肝病,动物模型 z-bio 2021-10-07 883

　　Non-alcoholic fatty liver disease (NAFLD) is a liver syndrome that does not involve alcohol abuse, including simple fatty liver, steatohepatitis, fatty liver fibrosis, and cirrhosis. From simple fatty liver to non-alcoholic steatohepatitis (NASH) to liver fibrosis, it can even lead to end-stage liver diseases such as cirrhosis, hepatocellular carcinoma (HCC) or liver failure.

　　According to a study by Younossi et al., "NAFLD is one of the most important causes of liver disease in the world, and may be the main cause of end-stage liver disease in the next few decades. Adults and children"

　　The standard for diagnosis of golden NASH is liver biopsy, but this method is very invasive. Liver enzymes in patients with AFLD may be normal. Ultrasound can detect fatty liver, but not fibrosis or inflammation. Currently, there is no approved treatment for NAFLD, so not only are ASH treatments being developed, but new diagnostic methods are also being studied. Pharmaceutical and biotechnology companies are investing heavily in AFLD/NASH research.

　　Animal models play an important role in elucidating the pathophysiological mechanism of non-alcoholic fatty liver and developing new drugs. Preclinical research requires the use of different animal models based on the specific AFLD phenotype being studied. AFLD and NASH preclinical animal models can be divided into four categories: diet induction model, chemical induction model, gene editing model and compound model.

　　1. Diet induction model

　　It is a fatty liver model established by feeding animals a high-fat and high-sugar diet. The main cause is overnutrition. The fat, cholesterol and/or carbohydrates in the food cannot be taken in too much. Fat accumulates in the liver, leading to fatty liver and hepatitis. And fibrosis. This model is similar to human AFLD and is the most common animal model of AFLD. Different dietary guidance models have different characteristics. One of the challenges of the diet-induced model is that it takes time to build the model before starting the research.

　　2, chemical induction model

　　is used in combination with low-dose streptozotocin and high-fat diet to prepare mouse NAFLD, which can cause steatosis, inflammation, fibrosis, and even hepatocellular carcinoma. Carbon tetrachloride (CCl4) can cause liver damage. It can be used alone or in combination with a high-fat diet to induce fatty liver and cirrhosis. The main mechanism is that carbon tetrachloride causes oxidative stress in the liver, leading to the continuous production and accumulation of harmful lipids and protein peroxides, and severe necrosis leads to the destruction of liver cell structure and function. Although this method can establish a model in a short time, its etiology, pathological changes and histological morphology are very different from human fatty liver, and it is very toxic, which can cause animal death.

　　3. Gene editing model

　　The production and removal of fat in liver cells are regulated by a variety of genes. Mutations, deletions, overexpression or changes affect fat metabolism and cause fatty liver, or may artificially manipulate animal genes. You can convert AFLD animal models. on

　　The pathogenesis of NAFLD, the "second hit" theory is widely accepted. "Blowing" is fatty liver caused by insulin resistance, and the "second time" is oxidative stress, inflammatory factors, endotoxin and other factors.

　　Ob/ob mice have ob (repo) homozygous mutations, obesity and steatosis; db/db mice or Zucker rats are thin due to mutations in the db or fa gene (leptin receptor encoding gene), leptin receptor lose the capacity of. It causes leptin resistance and exhibits a genotype similar to ob/ob mice. However, these models cannot spontaneously change from hepatic steatohepatitis to steatohepatitis, and must be combined with diet and chemicals to induce the "second hit" to change to the ASH phenotype.

　　PTEN is a lipid phosphatase, involved in fatty acid β-oxidation and triglyceride synthesis in liver cells, and is a negative regulator of signal pathways such as apoptosis, cell proliferation and differentiation, and tumorigenesis. SatoW et al. found that liver-specific PTEN knockout mice can cause liver damage similar to human ASH. These mice can develop steatohepatitis, liver fibrosis, and liver adenomas 10 weeks after birth. Finally, 66 mice had HCC. PPAR-α is a transcription factor that participates in the transcriptional regulation of mitochondria and peroxisome β-oxidation genes in the liver, and can regulate the production of ATP. MTP is a key enzyme for β-oxidation of mitochondrial fatty acids. AOX is the rate-limiting enzyme for β-oxidation of long-chain fatty acids in peroxisomes, which can produce hydrogen peroxide. Modifications of these genes can affect the β-oxidation of fatty acids to create an AFLD model.

　　Methionine adenosyltransferase 1A (MAT-1A) is a liver-specific methionine metabolism rate-determining enzyme that can catalyze the production of S-adenosylmethionine, S-adenosylmethionine Acid is the main methyl donor for the liver. MAT-1A knockout mice reduced antioxidants (such as glutathione) and down-regulated the expression of genes involved in liver lipid oxidation.

　　Apoe knockout mice are often used to study atherosclerosis. When fed a high-fat, high-cholesterol diet, they can cause ASH phenotypes such as lipemia, inflammation, and fibrosis.

　　Gene editing and chemical induction can speed up the model, but the model may have nothing to do with the disease induction mechanism.

　　4. Composite model

　　None of the above three models can fully simulate the etiology of human NAFLD, and its phenotype is different from that of human NAFLD. Many scholars combine gene editing models with diet and drug induction to create composite models. This makes the phenotype and etiology of the composite model closer to human AFLD, reflecting the progression of the disease from simple fatty liver to ASH and ASH. Progress to the process of liver fibrosis.

　　The most commonly used composite model:

　　ob/ob mice + methionine choline deficiency (MCD), db/db mice + methionine choline deficiency (MCD) diet, Zucker rat + methionine choline deficiency (MCD)) fat diet. These models can form typical AFLD histological changes.

　　db/db mouse + MCD diet model is more serious than ob/ob mouse + MCD diet model, accompanied by inflammation and fibrosis around the cell, the modeling cycle is significantly shortened, leading to the use of db/db mouse + MCD diet model.

　　The

　　 composite model can best simulate human NAFLD with significant pathological changes, but the modeling process is slightly more complicated.

　　Fatty liver animal models have different phenotypes and formation mechanisms according to different methods. Therefore, the best animal model is selected according to the research purpose, and the complications of the NAFLD model are considered to prevent the animal model from being affected. Used for. Choose an experimental model similar to human NAFLD. The method is simple, the success rate is high, the animal mortality is low, the modeling time is short, and the reproducibility is good.