Brain-Derived Neurotrophic Factor in Children and Adolescents with Cirrhosis Due to Biliary Atresia

New Insight Into Mechanisms of Hepatic Encephalopathy: An Integrative Analysis Approach to Identify Molecular Markers and Therapeutic Targets

Hepatic encephalopathy (HE) is a set of complex neurological complications that arise from advanced liver disease. The precise molecular and cellular mechanism of HE is not fully understood. Differentially expressed genes (DEGs) from microarray technologies are powerful approaches to obtain new insight into the pathophysiology of HE. We analyzed microarray data sets of cirrhotic patients with HE from Gene Expression Omnibus to identify DEGs in postmortem cerebral tissues. Consequently, we uploaded significant DEGs into the STRING to specify protein-protein interactions. Cytoscape was used to reconstruct the genetic network and identify hub genes. Target genes were uploaded to different databases to perform comprehensive enrichment analysis and repurpose new therapeutic options for HE. A total of 457 DEGs were identified in 2 data sets totally from 12 cirrhotic patients with HE compared with 12 healthy subjects. We found that 274 genes were upregulated and 183 genes were downregulated. Network analyses on significant DEGs indicated 12 hub genes associated with HE. Enrichment analysis identified fatty acid beta-oxidation, cerebral organic acidurias, and regulation of actin cytoskeleton as main involved pathways associated with upregulated genes; serotonin receptor 2 and ELK-SRF/GATA4 signaling, GPCRs, class A rhodopsin-like, and p38 MAPK signaling pathway were related to downregulated genes. Finally, we predicted 39 probable effective drugs/agents for HE. This study not only confirms main important involved mechanisms of HE but also reveals some yet unknown activated molecular and cellular pathways in human HE. In addition, new targets were identified that could be of value in the future study of HE.

Neurotrophic factors stimulate the activation of hepatic stellate cells in liver fibrosis

BACKGROUND AND AIMS

Patients with liver fibrosis who have pain in the liver region may have changed nerve factors. The expression of neurokines and hepatic nerves in liver fibrosis, however, was little understood. In order to better understand how liver fibrosis develops, we plan to look into the hepatic nerve and neurokine changes and how they relate to hepatic stellate cells (HSCs).

METHODS

The expression of neurokines in liver samples from 55 chronic hepatitis B patients and the carbon tetrachloride (CCl₄) animal model were studied. The co-staining of Nissl and α-SMA allowed us to investigate the neurons and their interaction with α-SMA in fibrotic livers, as well as the expression of the glial cell marker glial fibrillary acidic protein (GFAP) and its relationship with α-SMA, a marker of HSCs. SH-SY5Y cells were treated with a fibrotic serum to imitate the hepatic microenvironment on neuronal cells. We also used brain-derived neurotrophic factor (BDNF) to stimulate mouse primary HSCs and LX2.

RESULTS

The levels of mRNA for neurokines such as BDNF, GFAP, and growth-associated protein (GAP43) are significantly increased in both human and animal liver fibrosis. As liver fibrosis advances, we found that Nissl bodies and α-SMA may co-localize, suggesting a connection between hepatic nerves and HSCs. Human fibrotic serum may increase neurkines, notably BDNF, in SH-SY5Y cells. We also found that BDNF increased pro-inflammatory cytokines and fibrogenic markers in hHSCs.

CONCLUSIONS

Patients with hepatic fibrosis had significantly higher levels of BDNF, GFAP, GAP43, and nerve fibers. HSC and nerve fibers interact, and nerves also create neurogenic substances that promote liver fibrosis and HSC activation.

Hepatic Encephalopathy: From Metabolic to Neurodegenerative

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome of both acute and chronic liver disease. As a metabolic disorder, HE is considered to be reversible and therefore is expected to resolve following the replacement of the diseased liver with a healthy liver. However, persisting neurological complications are observed in up to 47% of transplanted patients. Several retrospective studies have shown that patients with a history of HE, particularly overt-HE, had persistent neurological complications even after liver transplantation (LT). These enduring neurological conditions significantly affect patient's quality of life and continue to add to the economic burden of chronic liver disease on health care systems. This review discusses the journey of the brain through the progression of liver disease, entering the invasive surgical procedure of LT and the conditions associated with the post-transplant period. In particular, it will discuss the vulnerability of the HE brain to peri-operative factors and post-LT conditions which may explain non-resolved neurological impairment following LT. In addition, the review will provide evidence; (i) supporting overt-HE impacts on neurological complications post-LT; (ii) that overt-HE leads to permanent neuronal injury and (iii) the pathophysiological role of ammonia toxicity on astrocyte and neuronal injury/damage. Together, these findings will provide new insights on the underlying mechanisms leading to neurological complications post-LT.

Growth Factors Assessed during Kasai Procedure in Liver and Serum Are Not Predictive for the Postoperative Liver Deterioration in Infants with Biliary Atresia

Background: Biliary atresia (BA) is a neonatal cholangiopathy characterized by progressive destruction of the biliary system resulting in liver cirrhosis. Residual bile drainage can temporarily be achieved through Kasai portoenterostomy (KPE) and some children show long-term survival with their native liver. However, most children eventually require liver transplantation (LTX). As several growth factors (GF) and chemokines have been shown to promote fibrogenesis in the liver, we assessed whether GF are predictive for the course of disease. Material and Methods: Liver and sera samples were collected from 49 infants with BA during KPE. Levels of 13 different GF were measured by multiplex immunoassay. Patient outcomes were stratified into favorable (bilirubin < 20 µmol/L at 2-year follow-up) and unfavorable (LTX). GF levels were compared between groups by a t-test, correlation coefficients were calculated, and principal component analyses performed. Results: Twenty-two patients showed a favorable and 27 an unfavorable disease course. No relation of GF and outcome could be established. In both groups, high levels of SDF-1alpha/CXCL12 (1473.0 ± 497.5 pg/mL), FGF2 (301.2 ± 207.8 pg/mL), and VEGF-a (209.0 ± 146.4 pg/mL) levels were measured within the liver, followed (in descending order) by PDGF-bb, LIF, GM-CSF, BDNF, VEGF-d, beta-NGF, IL-7, SCF, PIGF-1, and EGF. Serum marker levels showed much higher mean variation compared to hepatic values and no correlation to the protein microenvironment in the liver. Conclusions: Our study demonstrates high amounts of GF in livers from infants with BA at KPE, but no correlation to the outcome or serum values could be established. Our data suggest that local or systemic GF levels are unsuitable for prediction of the disease course. Collectively, we conclude that in BA the degree of proliferative activity caused by GF is a dismissible factor for the further course of disease.

Brain-derived neurotrophic factor as a potential diagnostic marker in minimal hepatic encephalopathy

Introduction

Minimal hepatic encephalopathy (MHE) is a common complication of liver cirrhosis not only leading to a decrease in the quality of life, but also predicting development of overt encephalopathy. The diagnosis of MHE usually relies on a combination of neuropsychological tests, while robust serum biomarkers are lacking. We aimed to assess serum concentrations of brain-derived neurotrophic factor (BDNF) in MHE patients.

Material and methods

Serum BDNF was assessed in 78 patients with liver cirrhosis (53 male, median age 55 years) and 40 healthy individuals. 43 subjects underwent extensive evaluation for MHE by psychometric hepatic encephalopathy score (PHES) and inhibitory control test (ICT) or critical flicker frequency (CFF).

Results

Serum BDNF was twofold lower in liver cirrhosis compared to healthy subjects [13.6 (7.8-22.6) vs. 33.0 (24.1-40.7) ng/ml, p < 0.001] and its decrease reflected a degree of liver insufficiency assessed by model for end-stage liver disease (MELD). BDNF showed a negative correlation with bilirubin (R = –0.35, p = 0.005) and international normalized ratio (INR) (R = –0.37, p = 0.003), and positive with platelets (PLT) (R = 0.36, p = 0.004), while no associations with age, sex, body mass index (BMI), waist-hip ratio (WHR), creatinine and ammonia were noted. Importantly, subjects with a diagnosis of MHE by at least two modalities showed the lowest levels of BDNF [10.9 (2.5-14.4) vs. 19.9 (9.3-29.4) ng/ml, p < 0.01]. Patients with self-reported sleep disturbances had significantly lower serum BDNF [13.0 (2.5-23.4) vs. 20.0 (8.4-31.3) ng/ml, p = 0.04].

Conclusions

The lowest serum BDNF concentration was noted in patients with MHE and sleep disturbances, which suggests a role in pathophysiology of hepatic encephalopathy but also as a potential biomarker.