Intrahepatic distribution of nerve fibers and alterations due to fibrosis in diseased liver

The role of the nervous system in liver diseases

The nervous system significantly participates in maintaining homeostasis, and modulating repair and regeneration processes in the liver. Moreover, the nervous system also plays an important role in the processes associated with the development and progression of liver disease, and can either potentiate or inhibit these processes. The aim of this review is to describe the mechanisms and pathways through which the nervous system influences the development and progression of liver diseases, such as alcohol-associated liver disease, nonalcoholic fatty liver disease, cholestatic liver disease, hepatitis, cirrhosis, and hepatocellular carcinoma. Possible therapeutic implications based on modulation of signals transduction between the nervous system and the liver are also discussed.

The brain-liver cholinergic anti-inflammatory pathway and viral infections

Efferent cholinergic signaling is a critical and targetable source of immunoregulation. The vagus nerve (VN) is the primary source of cholinergic signaling in the body, and partially innervates hepatic functionality through the liver-brain axis. Virus-induced disruption of cholinergic signaling may promote pathogenesis in hepatotropic and neurotropic viruses. Therefore, restoring VN functionality could be a novel therapeutic strategy to alleviate pathogenic inflammation in hepatotropic and neurotropic viral infections alike. In this minireview, we discuss the physiological importance of cholinergic signaling in maintaining liver-brain axis homeostasis. Next, we explore mechanisms by which the VN is perturbed by viral infections, and how non-invasive restoration of cholinergic signaling pathways with bioelectronic medicine (BEM) might ameliorate hepatic inflammation and neuroinflammation in certain viral infections.

Non-alcoholic fatty liver disease (NAFLD) and mental illness: Mechanisms linking mood, metabolism and medicines

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the world and one of the leading indications for liver transplantation. It is one of the many manifestations of insulin resistance and metabolic syndrome as well as an independent risk factor for cardiovascular disease. There is growing evidence linking the incidence of NAFLD with psychiatric illnesses such as schizophrenia, bipolar disorder and depression mechanistically via genetic, metabolic, inflammatory and environmental factors including smoking and psychiatric medications. Indeed, patients prescribed antipsychotic medications, regardless of diagnosis, have higher incidence of NAFLD than population norms. The mechanistic pharmacology of antipsychotic-associated NAFLD is beginning to emerge. In this review, we aim to discuss the pathophysiology of NAFLD including its risk factors, insulin resistance and systemic inflammation as well as its intersection with psychiatric illnesses.

Metabolic associated fatty liver disease is a disease related to sympathetic nervous system activation

Strong evidence from animal and human studies shows that sympathetic nervous system (SNS) activation is a key factor in the development of metabolic associated fatty liver disease (MAFLD). Activation of the sympathetic nervous system plays an important role in the pathogenesis of obesity, metabolic syndrome, diabetes, hypertension, and MAFLD. When genetically susceptible subjects are exposed to a variety of epigenetic changes, their liver damage may develop into MAFLD. Thus, the pathogenesis of MAFLD is complex, involving the complex interaction of insulin resistance, abnormal hormone secretion, obesity, diet, genetic factors, immune activation, gut microbiota, and other factors. In these processes, the role of sympathetic nerves cannot be underestimated. Notably, SNS has been proposed as a therapeutic target for MAFLD by inhibiting sympathetic nerves. It is worthy of further discussion and research.

Reclassification of Hepatocellular Cancer With Neural-Related Genes

Neural infiltration is a critical component of the tumor microenvironment; however, owing to technological limitations, its role in hepatocellular cancer remains obscure. Herein, we obtained the RNA-sequencing data of liver hepatocellular carcinoma (LIHC) from The Cancer Genome Atlas database and performed a series of bioinformatic analyses, including prognosis analysis, pathway enrichment, and immune analysis, using the R software packages, Consensus Cluster Plus and Limma. LIHC could be divided into two subtypes according to the expression of neural-related genes (NRGs); moreover, there are statistic differences in the prognosis, stage, and immune regulation between the two subtypes. The prognostic model showed that high expression of NRGs correlated with a poor survival prognosis (P<0.05). Further, CHRNE, GFRA2, GFRA3, and GRIN2D was significantly correlated with LIHC clinical prognosis, clinical stage, immune infiltration, immune response, and vital signaling pathways. There was nerve-cancer crosstalk in LIHC. A reclassification of LIHC based on NRG expression may prove beneficial to clinical practice. CHRNE, GFRA2, GFRA3, and GRIN2D may serve as potential biomarker for liver cancer prognosis or immune response.

The Role of Catecholamines in Pathophysiological Liver Processes

Over the last few years, the number of research publications about the role of catecholamines (epinephrine, norepinephrine, and dopamine) in the development of liver diseases such as liver fibrosis, fatty liver diseases, or liver cancers is constantly increasing. However, the mechanisms involved in these effects are not well understood. In this review, we first recapitulate the way the liver is in contact with catecholamines and consider liver implications in their metabolism. A focus on the expression of the adrenergic and dopaminergic receptors by the liver cells is also discussed. Involvement of catecholamines in physiological (glucose metabolism, lipids metabolism, and liver regeneration) and pathophysiological (impact on drug-metabolizing enzymes expression, liver dysfunction during sepsis, fibrosis development, or liver fatty diseases and liver cancers) processes are then discussed. This review highlights the importance of understanding the mechanisms through which catecholamines influence liver functions in order to draw benefit from the adrenergic and dopaminergic antagonists currently marketed. Indeed, as these molecules are well-known drugs, their use as therapies or adjuvant treatments in several liver diseases could be facilitated.