Increased brain-derived neurotrophic factor in the serum of persons with nonalcoholic fatty liver disease

Brain-derived neurotrophic factor knock-out mice develop non-alcoholic steatohepatitis

While brain-derived neurotrophic factor (BDNF), which is a growth factor associated with cognitive improvement and the alleviation of depression symptoms, is known to regulate food intake and body weight, the role of BDNF in peripheral disease is not fully understood. Here, we show that reduced BDNF expression is associated with weight gain and the chronic liver disease non-alcoholic steatohepatitis (NASH). At 10 months of age, BDNF-heterozygous (BDNF+/- ) mice developed symptoms of NASH: centrilobular/perivenular steatosis, lobular inflammation with infiltration of neutrophils, ballooning hepatocytes, and fibrosis of the liver. Obesity and higher serum levels of glucose and insulin - major pathologic features in human NASH - were dramatic. Dying adipocytes were surrounded by macrophages in visceral fat, suggesting that chronic inflammation occurs in peripheral organs. RNA sequencing (RNA-seq) studies of the liver revealed that the most significantly enriched Gene Ontology term involved fatty acid metabolic processes and the modulation of neutrophil aggregation, pathologies that well characterise NASH. Gene expression analysis by RNA-seq also support the notion that BDNF+/- mice are under oxidative stress, as indicated by alterations in the expression of the cytochrome P450 family and a reduction in glutathione S-transferase p, an antioxidant enzyme. Histopathologic phenotypes of NASH were also observed in a knock-in mouse (BDNF+/pro ), in which the precursor BDNF is inefficiently converted into the mature form of BDNF. Lastly, as BDNF reduction causes overeating and subsequent obesity, a food restriction study was conducted in BDNF+/pro mice. Pair-fed BDNF+/pro mice developed hepatocellular damage and showed infiltration of inflammatory cells, including neutrophils in the liver, despite having body weights and blood parameters that were comparable to those of controls. This is the first report demonstrating that reduced BDNF expression plays a role in the pathogenic mechanism of NASH, which is a hepatic manifestation of metabolic syndrome. © 2023 The Pathological Society of Great Britain and Ireland.

Regulatory Networks, Management Approaches, and Emerging Treatments of Nonalcoholic Fatty Liver Disease

The pathogenesis of NAFLD is complex and diverse, involving multiple signaling pathways and cytokines from various organs. Hepatokines, stellakines, adipokines, and myokines secreted by hepatocytes, hepatic stellate cells, adipose tissue, and myocytes play an important role in the occurrence and development of nonalcoholic fatty liver disease (NAFLD). The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) contributes to the progression of NAFLD by mediating liver inflammation, immune response, hepatocyte death, and later compensatory proliferation. In this review, we first discuss the crosstalk and interaction between hepatokines, stellakines, adipokines, and myokines and NF-κB in NAFLD. The characterization of the crosstalk of NF-κB with these factors will provide a better understanding of the molecular mechanisms involved in the progression of NAFLD. In addition, we examine new expert management opinions for NAFLD and explore the therapeutic potential of silymarin in NAFLD/NASH.