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Nonalcoholic Fatty Liver Disease

Basic Pathogenetic Mechanisms in the Progression From NAFLD to NASH

Pierantonelli, Irene, MD, PhD1; Svegliati-Baroni, Gianluca, MD1,2

doi: 10.1097/TP.0000000000002480
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Nonalcoholic fatty liver disease (NAFLD) represents a growing cause of chronic liver injury, especially in western countries, where it is becoming the most frequent indication for liver transplantation. Nonalcoholic fatty liver disease encompasses a spectrum of diseases that from simple steatosis (pure NAFLD) can progress to nonalcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma. The pathogenesis of NAFLD and the mechanisms behind its progression to NASH have been extensively studied. However, although the processes that determine fat accumulation are mostly clear, the mechanisms associated with the progression of the disease are not fully characterized. In predisposed patients, lipid accumulation can promote lipotoxicity and mitochondrial dysfunction, thus triggering hepatocyte death, inflammation and fibrosis. The specific role of different lipids has been identified and free fatty acids as well as free cholesterol have been identified as toxic species. To make the picture more complex, the pathogenesis of NAFLD involves pathological connections between several organs, including the adipose tissue and the gut, with the liver. The “inflamed” adipose tissue plays a key role in the release of toxic lipids, whereas alterations in the gut-liver axis have been associated with the progression from NAFLD to NASH mediated by dysbiosis, alteration of intestinal barrier, and finally bacterial translocation, which can trigger proinflammatory and profibrogenetic pathways, finally leading to cirrhosis development.

1 Department of Gastroenterology, Università Politecnica delle Marche, Ancona, Italy.

2 Obesity Center, Università Politecnica delle Marche, Ancona, Italy.

Received 25 June 2018. Revision received 14 September 2018.

Accepted 3 October 2018.

The authors declare no funding or conflicts of interest.

Authorship: Both authors contributed to the writing of the manuscript.

Correspondence: Gianluca Svegliati-Baroni, MD, Department of Gastroenterology, Università Politecnica delle Marche, Via Tronto 10, 60126 Ancona, Italy. (gsvegliati@gmail.com).

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