tetracycline and Non-alcoholic-Fatty-Liver-Disease

Nonalcoholic fatty liver disease (NAFLD) is a continuous diseases spectrum associated with obesity, type 2 diabetes, insulin resistance, and hyperlipidemia. Simple hepatic steatosis may progress to nonalcoholic steatohepatitis (NASH), even fibrosis and cirrhosis, and finally hepatocellular carcinoma. In recent years, NAFLD has become a public health concern with increasing prevalence. However, the mechanisms underlying the pathogenesis remain incompletely understood, and few effective therapeutic approaches are available. Summary and Key Messages: A myriad of different rodent models has been developed to elucidate pathophysiology of NAFLD/NASH and guide therapeutic strategy. To date, no single rodent model can display the whole disease spectrum and metabolic features associated with human NASH, but can imitate particular characteristics. In this paper, we review the most commonly used dietary, genetic, and chemical rodent models for NAFLD referring to their advantages and disadvantages. Also, we illustrate the status of latest treatment strategy using various NAFLD rodent models. We hope to provide critical guidance for researchers to select appropriate animal models.

Topics: Animals; Antioxidants; Carbon Tetrachloride; Cholesterol, Dietary; Combined Modality Therapy; Diet, Carbohydrate Loading; Diet, High-Fat; Disease Models, Animal; Fecal Microbiota Transplantation; Gastrointestinal Microbiome; Humans; Insulin; Lipid Metabolism; Liver; Liver Cirrhosis; Mice; Mice, Knockout; Mice, Obese; Non-alcoholic Fatty Liver Disease; Probiotics; Rats; Rats, Transgenic; Streptozocin; Tetracycline

Endoplasmic reticulum (ER) stress is known to be involved in the development of several metabolic disorders, including non-alcoholic fatty liver disease (NAFLD). Tetracycline can cause hepatic steatosis, and ER stress may be involved in tetracycline-induced fatty liver. Our previous study showed that bicyclol has been proven to protect against tetracycline-induced fatty liver in mice, and ER stress may also be involved in bicyclol's hepatoprotective effect. Therefore, this study was performed to investigate the underlying mechanisms associated with ER stress and apoptosis, by which bicyclol attenuated tetracycline-induced fatty liver in mice. Bicyclol (300 mg/kg) was given to mice by gavage 3 times. Tetracycline (200 mg/kg, intraperitoneally) was injected at 1 h after the last dose of bicyclol. At 6 h and 24 h after single dose of tetracycline injection, serum ALT, AST, TG, CHO and hepatic histopathological examinations were performed to evaluate liver injuries. Hepatic steatosis was assessed by the accumulation of hepatic TG and CHO. Moreover, hepatic apoptosis and ER stress related markers were determined by TUNEL, real-time PCR, and western blot. As a result, bicyclol significantly protected against tetracycline-induced fatty liver as evidenced by the decrease of elevated serum transaminases and hepatic triglyceride, and the attenuation of histopathological changes in mice. In addition, bicyclol remarkably alleviated hepatic apoptosis and the gene expression of caspase-3, and increased the gene expression of XIAP. The gene expressions of ER stress-related markers, including CHOP, GRP78, IRE-1α, and ATF6, which were downregulated by bicyclol pretreatment in tetracycline-injected mice. These results suggested that bicyclol protected tetracycline-induced fatty liver partly due to its ability of anti-apoptosis associated with ER stress.

Topics: Alanine Transaminase; Animals; Apoptosis; Aspartate Aminotransferases; Biphenyl Compounds; Cholesterol; Disease Models, Animal; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Gene Expression; Heat-Shock Proteins; Liver; Male; Mice; Mice, Inbred ICR; Non-alcoholic Fatty Liver Disease; Tetracycline; Transcription Factor CHOP; Triglycerides

The small heterodimer partner (SHP) (NR0B2) is an atypical nuclear receptor that lacks a DNA-binding domain. It interacts with and inhibits many transcription factors, affecting key metabolic processes, including bile acid, cholesterol, fatty acid, and drug metabolism. Our aim was to determine the influence of steatotic drugs and nonalcoholic fatty liver disease (NAFLD) on SHP expression and investigate the potential mechanisms. SHP was found to be repressed by steatotic drugs (valproate, doxycycline, tetracycline, and cyclosporin A) in cultured hepatic cells and the livers of different animal models of NAFLD: iatrogenic (tetracycline-treated rats), genetic (glycine N-methyltransferase-deficient mice), and nutritional (mice fed a methionine- and choline-deficient diet). Among the different transcription factors investigated, CCAAT-enhancer-binding protein α (C/EBPα) showed the strongest dominant-repressive effect on SHP expression in HepG2 and human hepatocytes. Reporter assays revealed that the inhibitory effect of C/EBPα and steatotic drugs colocalize between -340 and -509 base pair of the SHP promoter, and mutation of a predicted C/EBPα response element at -473 base pair abolished SHP repression by both C/EBPα and drugs. Moreover, inhibition of major stress signaling pathways demonstrated that the mitogen-activated protein kinase kinase 1/2 pathway activates, while the phosphatidylinositol 3 kinase pathway represses SHP in a C/EBP-dependent manner. We conclude that SHP is downregulated by several steatotic drugs and in advanced NAFLD. These conditions can activate signals that target C/EBPα and consequently repress SHP, thus favoring the progression and severity of NAFLD.

Topics: Animals; CCAAT-Enhancer-Binding Protein-alpha; Cells, Cultured; Cyclosporine; Doxycycline; Fatty Liver; Humans; Male; Mice; Mitogen-Activated Protein Kinase 1; Non-alcoholic Fatty Liver Disease; Promoter Regions, Genetic; Receptors, Cytoplasmic and Nuclear; Signal Transduction; Tetracycline; Thiazepines; Transcription, Genetic; Valproic Acid

Tetracycline induces microvesicular steatosis, which has a poor long-term prognosis and a higher risk of steatohepatitis development compared with macrovesicular steatosis. Recent gene expression studies indicated that tetracycline treatment affects the expression of many genes associated with fatty acid transport and esterification. In this study, we investigated the role of fatty acid transport and esterification in tetracycline-induced steatosis. Intracellular lipid accumulation and the protein expression of fatty acid translocase (FAT or CD36) and diacylglycerol acyltransferase (DGAT) 2 were increased in both mouse liver and HepG2 cells treated with tetracycline at 50 mg/kg (intraperitoneal injection, i.p.) and 100 μM, respectively. Tetracycline increased the cellular uptake of boron-dipyrromethene-labeled C16 fatty acid, which was abolished by CD36 RNA interference. Oleate-induced cellular lipid accumulation was further enhanced by co-incubation with tetracycline. Tetracycline downregulated extracellular signal-regulated kinase (ERK) phosphorylation, which negatively regulated DGAT2 expression. U0126, a specific ERK inhibitor, also increased DGAT2 expression and cellular lipid accumulation. DGAT1 and 2 knock-down with specific small interfering (si)-RNA completely abrogated the steatogenic effect of tetracycline in HepG2 cells. Taken together, our data showed that tetracycline induces lipid accumulation by facilitating fatty acid transport and triglyceride esterification by upregulating CD36 and DGAT2, respectively.

Topics: Animals; Biological Transport; CD36 Antigens; Diacylglycerol O-Acyltransferase; Disease Models, Animal; Esterification; Extracellular Signal-Regulated MAP Kinases; Fatty Acids; Hep G2 Cells; Hepatocytes; Humans; Liver; Male; Mice, Inbred ICR; Non-alcoholic Fatty Liver Disease; Protein Kinase Inhibitors; RNA Interference; Tetracycline; Transfection; Up-Regulation