Bariatric surgery in patients with non-alcoholic fatty liver disease - from pathophysiology to clinical effects

Abstract

Non-alcoholic fatty liver disease (NAFLD) is increasingly recognized as a significant liver disease, and it covers the disease spectrum from simple steatosis with a risk of development of non-alcoholic steatohepatitis (NASH) to fibrosis, subsequent cirrhosis, end-stage liver failure, and liver cancer with a potential need for liver transplantation. NAFLD and NASH are closely related to obesity, metabolic syndrome, and type 2 diabetes (T2D). The role of gut hormones, especially glucagon-like peptide 1 (GLP-1), is important in NAFLD. Bariatric surgery has the potential for inducing great weight loss and may improve the symptoms of metabolic syndrome and T2D. Recent data demonstrated significant effects of bariatric surgery on GLP-1 and other gut hormones and important lipid metabolic and inflammatory abnormalities in the pathophysiology of NAFLD. Therefore, bariatric surgery may reverse the pathological liver changes in NAFLD and NASH patients. In the present review, we describe NAFLD and NASH pathophysiology and the primary effects of bariatric surgery on metabolic pathways. We performed a systematic review of the beneficial and harmful effects and focused on changes in liver disease severity in NAFLD and NASH patients. The specific focus was liver histopathology as assessed by the invasive liver biopsy. Additionally, we reviewed several non-invasive methods used for the assessment of liver disease severity following bariatric surgery.

Non-alcoholic fatty liver disease – 2019

“…Weight reduction is associated with significant improvement in liver histology in patients with NAFLD by several postulated mechanisms (Figure 7) (48). Bariatric surgery is more efficacious in achieving weight loss of 10 to 30% in morbidly obese patients when compared to diet, lifestyle modifications and anti-obesity medications (49).…”

“…NAFLD is considered as an important comorbidity when deciding on bariatric surgery in morbidly obese individuals (6,10,11). The presence of cirrhosis is a relative contraindication for bariatric surgery, as it might lead to increased mortality (48,53,54).…”

Roux-en-Y Gastric Bypass in Obese Diabetic Rats Promotes Autophagy to Improve Lipid Metabolism through mTOR/p70S6K Signaling Pathway

“…RYGB is a procedure in which doctors reduce the size of the stomach to a pouch about the size of an egg and attach it to the intestine. It is the most common surgical weight-loss procedure in the U.S. Roux-en-Y gastric bypass (RYGB) can effectively treat lipid metabolism disorders in obese T2DM patients, reduce hepatic lipid toxicity, improve liver insulin resistance, and delay or even reverse NAFLD [8,9]. However, the mechanism that RYGB reduces the accumulation of liver fat is not yet clear.…”

Nonalcoholic fatty liver disease is associated with decreased hepatocyte mitochondrial respiration, but not mitochondrial number

“…Steatotic hepatocytes accumulate TGs in single large, or multiple medium-sized, cytoplasmic lipid droplets [3] and whilst simple steatosis is largely benign, its presence increases the risk of developing non-alcoholic steatohepatitis (NASH), which may progress to cirrhosis and hepatocellular carcinoma [4]. It is unclear why only a subset of patients develop NASH and, other than bariatric surgery for morbidly obese patients, there are currently no specific therapeutics available to treat or reverse this pathology [5].…”