Posttranscriptional changes of serum albumin: clinical and prognostic significance in hospitalized patients with cirrhosis.

UNLABELLED: Beside the regulation of fluid distribution, human serum albumin (HSA) carries other activities, such as binding, transport, and detoxification of many molecules. In patients with cirrhosis, HSA exhibits posttranscriptional alterations that likely affect its functions. This study aimed at identifying the structural HSA alterations occurring in cirrhosis and determining their relationship with specific clinical complications and patient survival. One hundred sixty-eight patients with cirrhosis, 35 with stable conditions and 133 hospitalized for acute clinical complications, and 94 healthy controls were enrolled. Posttranscriptional HSA molecular changes were identified and quantified by using a high-performance liquid chromatography/electrospray ionization mass spectrometry technique. Clinical and biochemical parameters were also recorded and hospitalized patients were followed for up to 1 year. Seven HSA isoforms carrying one or more posttranscriptional changes were identified. Altered HSA isoforms were significantly more represented in patients than in healthy controls. Conversely, the native, unchanged HSA isoform was significantly reduced in cirrhosis. Native HSA and most altered isoforms correlated with both Child-Pugh and Model for End-Stage Liver Disease scores. In hospitalized patients, oxidized and N-terminal truncated isoforms were independently associated with ascites, renal impairment, and bacterial infection. Finally, the native HSA and cysteinylated/N-terminal truncated isoforms were predictors of 1-year survival, with greater prognostic accuracy than total serum albumin concentration. CONCLUSIONS: Extensive posttranscriptional changes of HSA, involving several molecular sites and increasing in parallel with disease severity, occur in patients with cirrhosis. Altered isoforms are independently associated with specific clinical complications, whereas the residual, native HSA isoform independently predicts patient survival. These findings support the concept of the "effective albumin concentration," which implies that the global HSA function is related not only to its serum concentration, but also to the preservation of its structural integrity.

Ischaemia-modified albumin: a marker of bacterial infection in hospitalized patients with cirrhosis.

BACKGROUND & AIMS: Patients with cirrhosis present structural changes of human serum albumin (HSA) affecting non-oncotic functions. Ischaemia-modified albumin (IMA), which reflects the capacity to bind cobalt, has been associated to patient mortality during acute-on-chronic liver failure. This study aimed to assess whether circulating IMA is elevated in advanced cirrhosis and its relationship with severity of cirrhosis and specific complications. METHODS: A total of 127 cirrhotic patients hospitalized for an acute complication of the disease and 44 healthy controls were enrolled. Plasma IMA and IMA to albumin ratio (IMAr) were measured with a cobalt-binding assay. HSA isoforms carrying post-transcriptional molecular changes were assessed with HPLC-ESI-MS. The effect of endotoxemia on IMA was evaluated in rats with CCl4 -cirrhosis. RESULTS: IMA/IMAr is significantly higher in cirrhotic patients than in controls, but no correlations were found with prognostic scores. IMA did not correlate with the altered HSA isoforms. Ascites, renal impairment and hepatic encephalopathy did not influence IMA/IMAr levels. In contrast, IMA/IMAr is significantly higher in infected than non-infected patients. ROC curves showed that IMA/IMAr had similar discriminating performances for bacterial infection as C-reactive protein (CRP). Moreover, CRP and IMA were independently associated with bacterial infection. Consistently, endotoxin injection significantly increased IMA in cirrhotic, but not in healthy rats. CONCLUSIONS: IMA is elevated in patients with advanced cirrhosis. The IMA level does not correlate with disease severity scores, but it is specifically associated to bacterial infection, showing a discriminating performance similar to CRP. Further investigations to assess IMA as a novel diagnostic test for bacterial infection are advocated.

The endocannabinoid system in advanced liver cirrhosis: pathophysiological implication and future perspectives.

Endogenous cannabinoids (EC) are ubiquitous lipid signalling molecules providing different central and peripheral effects that are mediated mostly by the specific receptors CB1 and CB2. The EC system is highly upregulated during chronic liver disease and consistent experimental and clinical findings indicate that it plays a role in the pathogenesis of liver fibrosis and fatty liver disease associated with obesity, alcohol abuse and hepatitis C. Furthermore, a considerable number of studies have shown that EC and their receptors contribute to the pathogenesis of the cardio-circulatory disturbances occurring in advanced cirrhosis, such as portal hypertension, hyperdynamic circulatory syndrome and cirrhotic cardiomyopathy. More recently, the EC system has been implicated in the development of ascites, hepatic encephalopathy and the inflammatory response related to bacterial infection. Rimonabant, a selective CB1 antagonist, was the first drug acting on the EC system approved for the treatment of obesity. Unfortunately, it has been withdrawn from the market because of its neuropsychiatric side effects. Compounds able to target selectively the peripheral CB1 receptors are under evaluation. In addition, molecules stimulating CB2 receptor or modulating the activity of enzymes implicated in EC metabolism are promising areas of pharmacological research. Liver cirrhosis and the related complications represent an important target for the clinical application of these compounds.

Reversal of liver fibrosis by the antagonism of endocannabinoid CB1 receptor in a rat model of CCl(4)-induced advanced cirrhosis.

The endocannabinoid system is involved in the pathogenesis of liver fibrosis. Although many substances have been proved to reduce fibrosis in experimental models of chronic liver injury, most of them appear to be effective only if given as a prophylactic or early treatment. This study aimed to explore the effect of pharmacological antagonism of the endocannabinoid cannabinoid type 1 (CB1) receptor started after the stage of full-blown cirrhosis had been reached. Wistar-Han rats with carbon tetrachloride (CCl(4))-induced cirrhosis were randomized to receive the CB1 receptor antagonist Rimonabant (10 mg/kg/day) or the vehicle for 2 weeks. Age-matched healthy rats served as controls. Liver fibrosis was assessed using Sirius red staining, hydroxyproline concentration and α-smooth muscle actin expression. Hepatic gene expression of mediators of fibrogenesis and inflammation were evaluated by real-time PCR. We also assessed the hepatic expression of CB1 and CB2 receptors and that of the enzymes implicated in the endocannabinoid metabolism. Fibrosis was significantly reduced in rats treated with Rimonabant compared with rats receiving the vehicle. CB1 receptor antagonism limited the gene upregulation of fibrogenic and inflammatory mediators occurring in untreated cirrhotic rats. CB1 and CB2 receptor expression was increased in cirrhotic animals. Interestingly, pharmacological CB1 receptor antagonism was associated with a further induction of the CB2 receptor expression. Regression of fibrosis can be achieved by pharmacological blockade of the CB1 receptor even when started in an advanced stage of the disease. This effect is associated with the suppression of pro-fibrogenic and inflammatory mediators and may have been indirectly favoured by the induction of CB2 receptor expression.

An innovative hyperbaric hypothermic machine perfusion protects the liver from experimental preservation injury.

PURPOSE: Hypothermic machine perfusion systems seem more effective than the current static storage to prevent cold ischemic liver injury. Thus, we test an innovative hyperbaric hypothermic machine perfusion (HHMP), which combines hyperbaric oxygenation of the preservation solution and continuous perfusion of the graft. METHODS: Rat livers were preserved with Celsior solution according to 4 different modalities: normobaric static preservation; hyperbaric static preservation at 2 atmosphere absolute (ATA); normobaric dynamic preservation, with continuous perfusion; hyperbaric dynamic preservation, with continuous perfusion at 2 ATA. After 24 h cold preservation, we assessed different parameters. RESULTS: Compared to baseline, livers preserved with the current static storage showed severe ultrastructural damage, glycogen depletion and an increased oxidative stress. Normobaric perfused livers showed improved hepatocyte ultrastructure and ameliorated glycogen stores, but they still suffered a significant oxidative damage. The addition of hyperbaric oxygen produces an extra benefit by improving oxidative injury and by inducing endothelial NO synthase (eNOS) gene expression. CONCLUSIONS: Preservation by means of the present innovative HHMP reduced the liver injury occurring after the current static cold storage by lowering glycogen depletion and oxidative damage. Interestingly, only the use of hyperbaric oxygen was associated to a blunted oxidative stress and an increased eNOS gene expression.

The epigenetically regulated miR-494 associates with stem-cell phenotype and induces sorafenib resistance in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) represents the second cause of cancer-related mortality worldwide and is associated with poor prognosis, especially in patients not amenable for curative treatments. The multi-kinase inhibitor sorafenib represents the first-line treatment option for advanced HCC; nevertheless, its effectiveness is limited due to tumor heterogeneity as well as innate or acquired drug resistance, raising the need for new therapeutic strategies. MicroRNAs (miRNAs) involvement in treatment response as well as their safety and efficacy in preclinical models and clinical trials have been widely documented in the oncologic field, including HCC. Here, we identified miR-494 upregulation in a subgroup of human and rat HCCs with stem cell-like characteristics, as well as multiple epigenetic mechanisms involved in its aberrant expression in HCC cell lines and patients. Moreover, we identified p27, puma and pten among miR-494 targets, contributing to speed up cell cycle progression, enhance survival potential in stressful conditions and increase invasive and clonogenic capabilities. MiR-494 overexpression increased sorafenib resistance via mTOR pathway activation in HCC cell lines and, in line, high miR-494 levels associated with decreased sorafenib response in two HCC animal models. A sorafenib-combined anti-miR-494-based strategy revealed an enhanced anti-tumor potential with respect to sorafenib-only treatment in our HCC rat model. In conclusion, our findings suggested miR-494 as a possible therapeutic target as well as a candidate biomarker for patient stratification in advanced HCC.

Albumin Homodimers in Patients with Cirrhosis: Clinical and Prognostic Relevance of a Novel Identified Structural Alteration of the Molecule.

Decompensated cirrhosis is associated to extensive post-transcriptional changes of human albumin (HA). This study aims to characterize the occurrence of HA homodimerization in a large cohort of patients with decompensated cirrhosis and to evaluate its association with clinical features and prognosis. HA monomeric and dimeric isoforms were identified in peripheral blood by using a HPLC-ESI-MS technique in 123 cirrhotic patients hospitalized for acute decompensation and 50 age- and sex-comparable healthy controls. Clinical and biochemical parameters were recorded and patients followed up to one year. Among the monomeric isoforms identified, the N- and C-terminal truncated and the native HA underwent homodimerization. All three homodimers were significantly more abundant in patients with cirrhosis, acute-on-chronic liver failure and correlate with the prognostic scores. The homodimeric N-terminal truncated isoform was independently associated to disease complications and was able to stratify 1-year survival. As a result of all these changes, the monomeric native HA was significantly decreased in patients with cirrhosis, being also associated with a poorer prognosis. In conclusion homodimerization is a novel described structural alteration of the HA molecule in decompensated cirrhosis and contributes to the progressive reduction of the monomeric native HA, the only isoform provided of structural and functional integrity.