Non-Alcoholic Fatty Liver Disease

Area of Science:

• Hepatology
• Metabolic Diseases
• Cellular Biology

Background:

• Non-alcoholic fatty liver disease (NAFLD) is a prevalent liver condition associated with the global obesity epidemic.
• Hepatic steatosis in NAFLD is primarily linked to dietary fat intake, leading to triglyceride accumulation in hepatocytes.
• Insulin resistance plays a crucial role, impairing insulin receptor substrate-2 (IRS-2)-associated phosphatidylinositol 3-kinase (PI3K) activity and increasing lipotoxic metabolites.

Purpose of the Study:

• To elucidate the mechanisms underlying the development and progression of NAFLD and non-alcoholic steatohepatitis (NASH).
• To explain the "double-hit" hypothesis concerning lipotoxicity and its role in NAFLD pathogenesis.
• To detail the molecular pathways involved in NASH progression, including oxidative stress, autophagy, and inflammation.

Main Methods:

• Analysis of hepatic triglyceride accumulation due to increased free fatty acid inflow and de novo lipogenesis.
• Investigation of the role of insulin resistance and IRS-2/PI3K pathway deficiency in NAFLD.
• Examination of the "double-hit" hypothesis involving diacylglycerol accumulation and oxidative stress.

Main Results:

• Insulin resistance is identified as a primary driver for NAFLD and NASH development and progression.
• The "first hit" involves increased hepatic diacylglycerol and reduced mitochondrial respiratory chain complex activity.
• The "second hit" is characterized by oxidative stress, reduced glutathione, JNK/c-Jun signaling activation, and lipoapoptosis.

Conclusions:

• NAFLD pathogenesis is complex, involving metabolic dysregulation and cellular stress pathways.
• Insulin resistance and lipotoxicity are central to NAFLD and NASH progression.
• Oxidative stress, impaired cellular signaling, and hepatocyte apoptosis are critical in advancing NASH.