Enhanced production of leukotriene B4 by peripheral blood mononuclear cells in patients with fulminant hepatitis

The Mechanism of Hepatic Encephalopathy Induced by Thioacetamide Based on Metabolomics and Proteomics: A Preliminary Study

Hepatic encephalopathy (HE) is a central nervous system dysfunction syndrome caused by acute and chronic liver failure or various portal systemic shunt disorders. HE arises from metabolic disorder and excludes other known types of encephalopathy. HE is a major cause of death in people with liver disease. Early diagnosis and timely treatment are key to improving HE prognosis. Herein, we established a model of HE and performed metabolomics to identify 50 significantly differential metabolites between the HE group and control group. The main metabolic pathways associated with these differential metabolites were the purine metabolism, pyrimidine metabolism, aminoacyl tRNA biosynthesis, and glucose metabolism. Through proteomics analysis, we identified 226 significantly differential proteins (52 up-regulated and 174 down-regulated). The main (Kyoto Encyclopedia of Genes and Genomes) enrichment pathways were the Staphylococcus aureus infection, vitamin digestion and absorption, and complement and coagulation cascades. Through the conjoint analysis of proteomics and metabolomics, the differentially present proteins and metabolites were found to be involved in vitamin digestion and absorption, and ferroptosis pathways. In HE, malondialdehyde was significantly elevated, but glutathione was significantly diminished, and the redox balance was destroyed, thus leading to changes in proteins' levels associated with the ferroptosis pathway. In conclusion, this study preliminarily explored the molecular and metabolic mechanisms underlying HE.

Validity of serum leukotriene B4 as a marker of decompensated liver cirrhosis in chronic HCV patients: leukotriene B4 in decompensated liver cirrhosis

Background

Liver cirrhosis is divided into two stages: compensated stage and another advanced stage which includes both decompensated cirrhosis and acute-on-chronic liver failure. The immune system is of major importance in cirrhosis pathophysiology. Sustained bacterial translocation from the intestine to systemic circulation causes a chronic systemic inflammatory syndrome. Inflammatory markers are emerging in the scope of cirrhosis and its complications due to their deleterious effects on disease progression and prognosis. The aim of the study was to assess the value of leukotriene B4 (LTB4) as a marker of decompensated cirrhosis and to evaluate its relation to disease progression and complications.

Results

The current study was conducted on 80 candidates in the Alexandria Main University Hospital, Tropical Medicine Department; they were categorized into three groups: group I (n = 30) compensated cirrhotic patients, group II (n = 30) decompensated cirrhotic patients, and group III (n = 20) apparently healthy individuals. Serum LTB4 was measured by ELISA. LTB4 showed statistically significant higher values in the decompensated group than the compensated group (p = 0.007) and the control group (p = 0.002). However, there was no statistically significant difference between the compensated group and the controls (p = 0.510). LTB4 correlated positively with the Child-Pugh score (p = 0.003). Moreover, it correlated positively with the MELD-Na score (p = 0.012). There was a significant correlation between the degree of ascites and serum LTB4 (p < 0.001). However, there was no significant correlation between hepatic encephalopathy and LTB4 (P > 0.204).

Conclusion

Serum LTB4 could be used as a sensitive biomarker of decompensation in cirrhotic patients.

Role of leukotrienes on hepatic ischemia/reperfusion injury in rats

BACKGROUND

Leukotrienes (LT), composed of cysteinyl LT (cLT; LTC(4), LTD(4), and LTE(4)) and LTB(4), are potent lipid mediators enhancing the vascular permeability and recruitment of neutrophils, which are common features of hepatic ischemia/reperfusion (I/R) injury. The aim of this study was to investigate whether LT can mediate the liver and lung injuries following hepatic I/R.

MATERIALS AND METHODS

Sprague-Dawley rats were subjected to 90 min of partial hepatic ischemia followed by 3, 12, and 24 h of reperfusion. In the hepatic and pulmonary tissues, LT content and the mRNA expression of LT-synthesis enzymes, 5-lypoxygenase (5-LO), LTC(4) synthase (LTC(4)-S), and LTA(4) hydrolase (LTA(4)-H) were measured. Tissue injuries were assessed by plasma ALT, histological examination, and wet-to-dry tissue weight ratios.

RESULTS

The cLT content in the hepatic tissue after 12 and 24 h reperfusion was increased 4- to 5-fold compared to controls and this was accompanied by the enhancement of hepatic edema and plasma ALT elevation. There were no significant changes in the mRNA expression of LT-synthesis enzymes in both tissues. LTB(4) levels were not increased despite a significant neutrophil infiltration in both tissues.

CONCLUSIONS

These data suggest that cLT are generated in the liver during the reperfusion period and may contribute to the development of hepatic edema and exert cytotoxicity. Factors other than LTB(4) may contribute to neutrophil infiltration.

A novel hepatointestinal leukotriene B4 receptor. Cloning and functional characterization

Leukotriene B(4) (LTB(4)) is a product of eicosanoid metabolism and acts as an extremely potent chemotactic mediator for inflammation. LTB(4) exerts positive effects on the immigration and activation of leukocytes. These effects suggest an involvement of LTB(4) in several diseases: inflammatory bowel disease, psoriasis, arthritis, and asthma. LTB(4) elicits actions through interaction with one or more cell surface receptors that lead to chemotaxis and inflammation. One leukotriene B(4) receptor has been recently identified (LTB(4)-R1). In this report we describe cloning of a cDNA encoding a novel 358-amino acid receptor (LTB(4)-R2) that possesses seven membrane-spanning domains and is homologous (42%) and genetically linked to LTB(4)-R1. Expression of LTB(4)-R2 is broad but highest in liver, intestine, spleen, and kidney. In radioligand binding assays, membranes prepared from COS-7 cells transfected with LTB(4)-R2 cDNA displayed high affinity (K(d) = 0.17 nm) for [(3)H]LTB(4). Radioligand competition assays revealed high affinities of the receptor for LTB(4) and LTB(5), and 20-hydroxy-LTB(4), and intermediate affinities for 15(S)-HETE and 12-oxo-ETE. Three LTB(4) receptor antagonists, 14,15-dehydro-LTB(4), LTB(4)-3-aminopropylamide, and U-75302, had high affinity for LTB(4)-R1 but not for LTB(4)-R2. No apparent affinity binding for the receptors was detected for the CysLT1-selective antagonists montelukast and zafirlukast. LTB(4) functionally mobilized intracellular calcium and inhibited forskolin-stimulated cAMP production in 293 cells. The discovery of this new receptor should aid in further understanding the roles of LTB(4) in pathologies in these tissues and may provide a tool in identification of specific antagonists/agonists for potential therapeutic treatments.