Alleviation of high cholesterol-induced hepatic steatosis by lactobacillus acidophilus ATCC 43121

다국어 초록 (Multilingual Abstract)

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that ranges in severity from simple steatosis to cirrhosis. Now NAFLD is considered to be associated with hepatic metabolic disorders, resulting in overaccumulation of fatty acids/triglycerides and cholesterol. Especially, cholesterol has an important role of development of NAFLD. In some studies of nutritional animal models, the accumulation of cholesterol rather than fatty acids/triglycerides plays a critical role in this progression.
It has been reported that probiotics has the ability to lower plasma cholesterol levels when animals are fed with it. Many people, heretofore, focused on how to decrease cholesterol levels in serum and overlook the role of cholesterol for hepatosteatosis.
The purpose of the present study was to evaluate the alleviation of hepatic steatosis induced by high cholesterol diet with probiotics. Lactobacillus acidophilus ATCC 43121, which has high ability of cholesterol assimilation, was used to improve the liver steatosis. This strain has excellent acid tolerant character and showed high adhesion activity to HT-29 cells compared to GG strain. This indicated that 43121 strains has potential to positive effect in human intestine when intake it. And we checked whether our strain can modulate the cholesterol metabolism using HepG2 cells, cultured human liver cell, but it has no effect to HepG2 cells. However, because our strain has high ability of cholesterol assimilation, potential effect of L. acidophilus ATCC 43121 on plasma cholesterol level and liver steatosis was evaluated in C57BL/6N mice. Six week old male mice were fed a commercial diet (cholesterol-free diet, negative control, NC), cholesterol-enriched diet 28 days. We investigated the effects of L. acidophilus ATCC 43121 on cholesterol levels in serum and liver steatosis. And also we checked hepatic mRNA expression related lipid metabolism and TG contents in liver. The results showed that our strain could decrease levels of LDL cholesterol levels (p<0.05) and total triglyceride (TG) in liver (p<0.05), but the levels of total cholesterol and HDL-C in plasma was unchanged (p<0.05). In addition, the result of histologic analysis showed that high cholesterol group supplemented with probiotic had improved liver compared with high cholesterol groups. This study suggested that probiotics improve hepatic steatosis by reducing LDL-c and TG contents in liver.
In conclusion, these results suggest that Lactobacillus acidophilus ATCC 43121 have the potential to be explored as a probiotic in the management of non-alcoholic fatty liver disease.

목차 (Table of Contents)

• CONTENTS
• ABSTRACT
• CONTENTS
• LIST OF TABLES
• LIST OF FIGURES
• CHAPTER 1.
• LITERATURE REVIEW
• 1.1. Lactic acid bacteria (LAB)
• 1.1.1. Classification and Physiology
• 1.1.2. Lactic acid bacteria as probiotics
• 1.2. Cholesterol
• 1.2.1. Cholesterol metabolism
• 1.2.2. Hypocholesterolemic effect of LAB
• 1.3. Non-alcoholic fatty liver disease (NAFLD)
• 1.3.1. Overview
• 1.3.2. Role of cholesterol in NAFLD
• 1.4. References
• CHAPTER 2.
• Effects on cholesterol metabolism by lactobacillus acidophilus ATCC 43121 in cultured human liver cells
• 2.1. Introduction
• 2.2. Material and methods
• 2.2.1. Bacterial strains and culture conditions
• 2.2.2. Acid tolerance
• 2.2.3. Bile tolerance
• 2.2.4. Cholesterol reduction assay
• 2.2.5. Adhesion assay
• 2.2.6. Cell culture and treatment
• 2.2.7. Cell viability (MTT assay)
• 2.2.8. Reverse transcription polymerase chain reaction (RT-RCR)
• 2.2.9. Statistical Analysis
• 2.3. RESULTS AND DISCUSSION
• 2.3.1. Acid Tolerance and Bile Tolerance
• 2.3.2. Cholesterol reduction
• 2.3.3. Attachment ability to cultured human intestine cells
• 2.3.4. Cytotoxicity (MTT assay)
• 2.3.5. mRNA expression related to cholesterol metabolism
• 2.4. References
• CHAPTER 3.
• Effect of lactobacillus acidophilus ATCC 43121 on cholesterol diet-induced hepatic steatosis in C57BL/6N
• 3.1. Introduction
• 3.2. Material and methods
• 3.2.1. Animals
• 3.2.2. Preparation of Lactobacillus acidophilus ATCC 43121
• 3.2.3. Experimental design
• 3.2.4. Biochemical analysis
• 3.2.5. Histological evaluation
• 3.2.6. RNA isolation and RT-PCR from liver tissue
• 3.2.7. Hepatic lipid measurements
• 3.2.8. Statistical analysis
• 3.3. RESULTS AND DISCUSSION
• 3.3.1. Body weight & Food intake
• 3.3.2. Serum biochemical parameters
• 3.3.3. Effect of Lactobacillus acidophilus ATCC 43121 on NAFLD
• 3.3.4. Quantification of triglyceride in liver
• 3.3.5. mRNA expression levels related to lipid metabolism
• 3.4. Reference
• ABSTRACT IN KOREAN