Recent studies suggest a contribution of intrahepatic mineralocorticoid receptor (MR) activation to the development of cirrhosis. As MR blockade abrogates the development of cirrhosis and hypoxia, common during the development of cirrhosis, can activate MR in hepatocytes. But, the impact of non-physiological hepatic MR activation is unknown. In this study, we investigate the impact of hypoxia-induced hepatocyte MR activation as a relevant factor in cirrhosis.

RNA sequencing followed by gene ontology term enrichment analysis was performed on liver samples from rats treated for 12 weeks with or without CCl4 and for the last four weeks with or without eplerenone (MR antagonist). We investigated if these changes can be mimicked by hypoxia in a human hepatocyte cell line (HepG2 cells) and in primary rat hepatocytes (pRH). In order to evaluate the functional cellular importance, hepatocyte lipid accumulation, glucose consumption, lactate production and mitochondrial function were analyzed.

In cirrhotic liver tissue genes annotated to the GOterm "Monocarboxylic acid metabolic process" (PPARα, PDK4, AMACR, ABCC2, Lipin1) are downregulated. This effect is reversed by the MR antagonist eplerenone in vivo. The alterations are partially mimicked by hypoxia in rat and human hepatocytes in tissue culture. Furthermore, the reduction of mRNA and protein expression of PPARα, PDK4, AMACR, ABCC2 and Lipin1 during hypoxia is prevented by eplerenone in rat and human hepatocytes. Aldosterone, the endogenous MR agonist, did not affect the expression of those proteins in hepatocytes. As those proteins are key regulators of hepatocyte energy homeostasis, we analyzed if hypoxia affected glucose consumption, lactate production and lipid accumulation in HepG2 cells in a MR-mediated manner. All three parameters were affected by hypoxia and were partially normalized by eplerenone.

Our findings suggest that non-physiological MR activation plays a role in the dysregulation of glucose and lipid metabolism in hepatocytes. This leads to an increase in apoptosis, probably resulting in a proinflammatory micromilieu of the hepatic tissue. The enhanced deposition of extracellular matrix contributes to the development of cirrhosis. Therefore, MR antagonists may have therapeutic potential in the treatment of early stages of liver disease due to their direct action in the liver.

The liver is a highly vascularized organ where fluid properties, including vascular pressure, vessel integrity and fluid viscosity, play a critical role in gross mechanical properties. To study the effects of portal pressure, liver confinement, fluid viscosity, and tissue crosslinking on liver stiffness, water diffusion, and vessel size, we applied multiparametric magnetic resonance imaging (mpMRI), including multifrequency magnetic resonance elastography (MRE) and apparent diffusion coefficient (ADC) measurements, to ex vivo livers from healthy male rats (13.6±1.6 weeks) at room temperature. Four scenarios including altered liver confinement, tissue crosslinking, and vascular fluid viscosity were investigated with mpMRI at different portal pressure levels (0-17.5 cmH2O). Our experiments demonstrated that, with increasing portal pressure, rat livers showed higher water content, water diffusivity, and increased vessel sizes quantified by the vessel tissue volume fraction (VTVF). These effects were most pronounced in native, unconfined livers (VTVF: 300±120%, p<0.05, ADC: 88±29%, p<0.01), while still significant under confinement (confined: VTVF: 53±32%, p<0.01, ADC: 28±19%, p<0.05; confined-fixed: VTVF: 52±20%, p<0.001, ADC: 11±2%, p<0.01; confined-viscous: VTVF: 210±110%, p<0.01, ADC: 26±9%, p<0.001). Softening with elevated portal pressure (-12±5, p<0.05) occurred regardless of confinement and fixation. However, the liver stiffened when exposed to a more viscous inflow fluid (11±4%, p<0.001). Taken together, our results elucidate the complex relationship between macroscopic-biophysical parameters of liver tissue measured by mpMRI and vascular-fluid properties. Influenced by portal pressure, vascular permeability, and matrix crosslinking, liver stiffness is sensitive to intrinsic poroelastic properties, which, alongside vascular architecture and water diffusivity, may aid in the differential diagnosis of liver disease. STATEMENT OF SIGNIFICANCE: Using highly controllable ex vivo rat liver phantoms, hepatic biophysical properties such as tissue-vascular structure, stiffness, and water diffusivity were investigated using multiparametric MRI including multifrequency magnetic resonance elastography (MRE) and diffusion-weighted imaging (DWI). Through elaborate tuning of the experimental conditions such as the static portal pressure, flow viscosity, amount and distribution of fluid content in the liver, we identified the contributions of the fluid component to the overall imaging-based biophysical properties of the liver. Our finding demonstrated the sensitivity of liver stiffness to the hepatic poroelastic properties, which may aid in the differential diagnosis of liver diseases.

Endothelin causes vasoconstriction via the endothelin-A receptor (ET-A) in the intrahepatic circulation in cirrhosis and its increase leads to portal hypertension. The aim of the study was to investigate the acute effect of a selective ET-A antagonist in patients with portal hypertension and cirrhosis.

Proof-of-concept study with two different substudies: (a) local intrahepatic administration of the ET-A antagonist BQ 123 and (b) systemic oral administration of the ET-A antagonist Ambrisentan. Portal pressure was determined by hepatic venous pressure gradient (HVPG, both substudies) and hepatic arterial blood flow (HABF) by intra-arterial Doppler measurements (substudy 1) before and under the ET-A antagonist. Systemic haemodynamic parameters were measured in substudy 2.

Twelve patients (Child-Pugh [CP] B/C n = 7/5) were included in substudy 1 and 14 patients (CP A/B/C n = 4/6/4) in substudy 2. The relative decrease in HVPG was -12.5% (IQR: -40% to 0%; P = .05) in substudy 1 and -5.0% (IQR: -11.5% to 0%; P = .01) in substudy 2. Substudy 1 revealed higher decrease in HVPG in CP B patients. HABF increased significantly and patients without portal pressure decrease showed a higher increase of HABF. Substudy 2 showed a slight decrease in the mean arterial pressure without changes of other systemic haemodynamic parameters.

Administration of a selective ET-A antagonist decreases the portal pressure in cirrhotic patients. This decrease was higher in CP B patients and the non-responders showed a higher increase in hepatic arterial flow. Selective ET-A antagonists might be a future treatment option in patients with portal hypertension.

The mineralocorticoid receptor (MR) contributes to fibrosis in various tissues, and MR antagonists, like eplerenone, are used to prevent fibrosis. The role of MR antagonists in hepatic fibrosis and cirrhosis is unknown. Here, we investigated the role of MRs and eplerenone in cirrhosis development.

Liver fibrosis (5 weeks) and cirrhosis, without (8 weeks) and with ascites (12 weeks), were induced by CCl₄ in rats and comprehensively analysed. The effect of eplerenone on the development of cirrhosis with ascites was assessed. MR expression, cellular and subcellular distribution and impact of hypoxia were investigated in vivo and ex vivo. Primary rat hepatocytes and cell lines were used to investigate MR trafficking and transcriptional activity mechanistically.

In cirrhosis with ascites, MR mRNA and protein expressions were reduced in hepatocytes of hypoxic areas. While in normoxic areas MRs were mainly cytosolic, the remaining MRs in hypoxic areas were mainly localized in the nuclei, indicating activation followed by translocation and degradation. Accordingly, eplerenone treatment prevented nuclear MR translocation and the worsening of cirrhosis. Exposing hepatocytes ex vivo to hypoxia induced nuclear MR translocation and enhanced transcriptional MR activity at response elements of the NF-κB pathway.

We showed for the first time that hypoxia leads to a pathogenetic ligand-independent activation of hepatic MRs during cirrhosis resulting in their nuclear translocation and transcriptional activation of the NF-κB pathway. Treatment with eplerenone prevented the worsening of cirrhosis by blocking this ligand-independent activation of the MR.

The highly reactive α-dicarbonyl compounds glyoxal and methylglyoxal are major precursors of posttranslational protein modifications in vivo. Model incubations of N²-t-Boc-lysine and either glyoxal or methylglyoxal were used to further elucidate the underlying mechanisms of the N⁶-carboxymethyl lysine and N⁶-carboxyethyl lysine reaction cascades. After independent synthesis of the authentic reference standards, we were able to detect N⁶-glyoxylyl lysine and N⁶-pyruvoyl lysine for the first time by HPLC-MS² analyses. These two novel amide advanced-glycation endproducts were exclusively formed under aerated conditions, suggesting that they were potent markers for oxidative stress. Analogous to the well-known Strecker degradation pathway, leading from amino acids to Strecker acids, the oxidation of an enaminol intermediate is suggested to be the key mechanistic step. A highly sensitive workup for the determination of AGEs in tissues was developed. In support of our hypothesis, the levels of N⁶-glyoxylyl lysine and N⁶-pyruvoyl lysine in rat livers indeed correlated with liver cirrhosis and aging.

In recent years, defined progress has been made in understanding the mechanisms of hemodynamic disturbances occurring in liver cirrhosis, which are based on portal hypertension. In addition to pathophysiological disorders related to endothelial dysfunction, it was revealed: There is the restructuring of the vasculature, which includes vascular remodeling and angiogenesis. In spite of the fact that these changes are the compensatory-adaptive response to the deteriorating conditions of blood circulation, taken together, they contribute to the development and progression of portal hypertension causing severe complications such as bleeding from esophageal varices. Disruption of systemic and organ hemodynamics and the formation of portosystemic collaterals in portal hypertension commence with neovascularization and splanchnic vasodilation due to the hypoxia of the small intestine mucosa. In this regard, the goal of comprehensive treatment may be to influence on the chemokines, proinflammatory cytokines, and angiogenic factors (vascular endothelial growth factor, placental growth factor, platelet-derived growth factor and others) that lead to the development of these disorders. This review is to describe the mechanisms of restructuring of the vascular bed in response to hemodynamic disturbances in portal hypertension. Development of pathogenetic methods, which allow correcting portal hypertension, will improve the efficiency of conservative therapy aimed at prevention and treatment of its inherent complications.

Portal vein obstructive lesions associated with hypertrophy of the hepatic artery territory are observed in Schistosoma mansoni schistosomiasis. Liver perfusion scintigraphy is a method used for evaluation of hepatic perfusion changes in liver diseases. It has been suggested that, like in cirrhosis, where compensatory increase in perfusion through the hepatic artery is documented, perfusion changes occur in hepatosplenic schistosomiasis (HSS).

This study aims to determine changes in liver hemodynamics using hepatic perfusion scintigraphy and correlate them with clinical and laboratory variables and ultrasound findings in HSS.

Nineteen patients with schistosomiasis underwent ultrasound evaluation of degree of liver fibrosis, splenic length, and splenic and portal vein diameter, digestive endoscopy, and quantification of platelets. Subsequently, perfusion scintigraphy with measurement of hepatic perfusion index (HPI) was performed.

It was observed that patients with hepatosplenic schistosomiasis had significantly higher HPI compared with normal individuals (p = 0.0029) and that this increase correlated with splenic length (p = 0.038) and diameter of esophageal varices (p = 0.0060). Angioscintigraphy showed high accuracy for predicting presence of large esophageal varices.

Angioscintigraphy could show that patients with HSS had increased HPI, featuring greater liver "arterialization," as previously described for cirrhotic patients. Correlations were also observed between HPI and longitudinal splenic length, caliber of esophageal varices, caliber of portal vein, and blood platelet count. Angioscintigraphy is a promising technique for evaluation of hepatosplenic schistosomiasis.