Oxidative albumin damage in chronic liver failure: relation to albumin binding capacity, liver dysfunction and survival

Oxidative Alteration of Trp-214 and Lys-199 in Human Serum Albumin Increases Binding Affinity with Phenylbutazone: A Combined Experimental and Computational Investigation

Human serum albumin (HSA) is a target for reactive oxygen species (ROS), and alterations of its physiological functions caused by oxidation is a current issue. In this work, the amino-acid residues Trp-214 and Lys-199, which are located at site I of HSA, were experimentally and computationally oxidized, and the effect on the binding constant with phenylbutazone was measured. HSA was submitted to two mild oxidizing reagents, taurine monochloramine (Tau-NHCl) and taurine dibromamine (Tau-NBr₂). The oxidation of Trp-214 provoked spectroscopic alterations in the protein which were consistent with the formation of N'-formylkynurenine. It was found that the oxidation of HSA by Tau-NBr₂, but not by Tau-NHCl, provoked a significant increase in the association constant with phenylbutazone. The alterations of Trp-214 and Lys-199 were modeled and simulated by changing these residues using the putative oxidation products. Based on the Amber score function, the interaction energy was measured, and it showed that, while native HSA presented an interaction energy of -21.3 kJ/mol, HSA with Trp-214 altered to N'-formylkynurenine resulted in an energy of -28.4 kJ/mol, and HSA with Lys-199 altered to its carbonylated form resulted in an energy of -33.9 kJ/mol. In summary, these experimental and theoretical findings show that oxidative alterations of amino-acid residues at site I of HSA affect its binding efficacy.

Survival prediction among patients with non-cancer-related end-stage liver disease

BACKGROUND

Predicting the survival of non-cancer related end-stage-liver-disease patients in general practice has been difficult for physicians because of the extremely variable trajectories due to multiple complex clinical factors, hence it remains a challenging issue to date. This study aimed to develop and validate a specific prognostic scoring system to early recognize the prognosis and improve the quality of end-of life care for non-cancer end-stage-liver-disease population.

MATERIALS AND METHODS

A multicentre, retrospective cohort study was conducted during January 2010 ~ December 2012 and continued follow-up until December 2014. A cox proportional hazard regression analysis was used to derive and validate an optimized model. The main outcome measures were the 28-day, 3-month, 6-month, and 12-month mortality prediction. The performance of the novel model was evaluated, including discrimination and calibration.

RESULTS

A total of 4,080 consecutive subjects were enrolled. The AUROCs for the 3-month survival discrimination in the MELD, MELD-Na and novel model were 0.787, 0.705 and 0.804 (P<0.001); the 6-month survival discrimination were 0.781, 0.702 and 0.797 (P<0.001); the overall survival discrimination were 0.771, 0.694 and 0.785 (P = 0.002) respectively, whereas the novel model showed a significantly higher discrimination power than did the MELD and MELD-Na for the 3-month, 6-month and overall survival prediction. In addition, calibration of external validation cohort showed no statistical difference in all 5 groups compared with the observed groups.

CONCLUSION

This is a clinically relevant, validated scoring system that can be used sequentially to stratify the prognosis in non-cancer cirrhotic populations, which may help the patients along with medical team in decision making to improve the quality of end-of-life care.

New Insights About Albumin and Liver Disease

Decompensated liver cirrhosis has a dismal prognosis, with an overall survival of 2-4 years, which is worse than for many oncological diseases. Albumin is an important tool in the management of patients with cirrhosis, since it decreases for less than half the risk for post-paracentesis cardiocirculatory dysfunction and mortality associated with spontaneous bacterial infection, as well as, it triplicates the response to terlipressin in patients with hepatorenal syndrome. Recently, research on albumin has been a hot topic, with important new insights such as the characterization of the pleiotropic effects of albumin (which surpass its oncotic properties) and the concept of effective albumin concentration. In fact, patients with liver cirrhosis present posttranslational modifications on albumin that compromises its function. Those modified albumin forms were proved to have prognostic value and its knowledge may change the paradigm of albumin treatment. In this review, we critically summarize the latest evidence on the potential benefits of albumin in patients with end-stage liver disease.

Terminalia Sericea aqueous leaf extract protects growing wistar rats against fructose-induced fatty liver disease

Background Terminalia sericea (T. sericea) is traditionally used to treat stomach ailments, infections, hypertension and diabetes mellitus. Previous in vitro studies have reported that T. sericea has lipolytic properties. This study interrogated the effects of T. sericea on linear growth, development of fatty liver disease, viscera morphometry and health of growing rats fed a 12% fructose solution (FS). Methods Thirty 21-day old male Wistar rat pups were randomly allocated to five treatments: group I - plain gelatine cubes (PGC) + plain tap water (PW), group II - 12% FS + PGC, group III - gelatine cubes containing fenofibrate (Feno) at a dose of 100 mg/kg body + FS, group IV - gelatine cubes containing the low dose (100 mg/kg body mass per day) of the T. sericea extract (TsL) + FS, group V - gelatine cubes containing the high dose (400 mg/kg body mass per day) of the T. sericea extract (TsH) + FS. Following 12 weeks of feeding, the rats were fasted overnight, euthanized and plasma and viscera harvested for analysis. Results Consumption of fructose resulted in significantly increased (p<0.05) liver lipid content and caused macrovesicular steatosis. The T. sericea extracts at 400 mg/kg per day suppressed the fructose-induced liver lipid accumulation and macrovesicular steatosis similarly to 100 mg/kg per day of Feno. Conclusions These findings suggest that the aqueous T. sericea leaf extract at 400 mg/kg per day could potentially protect against fructose-induced lipid accumulation as well as macrovesicular steatosis.

Albumin Apheresis for Artificial Liver Support: In Vitro Testing of a Novel Filter

Currently there is no direct therapy for liver failure. We have previously described selective plasma exchange therapy using a hemofilter permeable to substances that have a molecular mass of up to 100 kDa. The proof-of-concept studies and a Phase I study in patients with decompensated cirrhosis demonstrated that hemofiltration using an albumin-leaking membrane is safe and effective in removing target molecules, alleviating severe encephalopathy and improving blood chemistry. In this study a novel large-pore filter for similar clinical application is described. The performance of the filter was studied in vitro; it was found to effectively remove a wide spectrum of pathogenic factors implicated in the pathophysiology of hepatic failure, including protein bound toxins and defective forms of circulating albumin. Data on mass transport characteristics and functionality using various modes of filtration and dialysis provide rationale for clinical evaluation of the filter for artificial liver support using albumin apheresis.

Targeting Albumin Binding Function as a Therapy Goal in Liver Failure: Development of a Novel Adsorbent for Albumin Dialysis

Liver failure results in impaired hepatic detoxification combined with diminished albumin synthesis and is associated with secondary organ failure. The accumulation of liver toxins has shown to saturate albumin binding sites. This was previously demonstrated by an in vitro test for albumin binding capacity (ABiC) that has shown to inversely correlate with the established MELD (Model for End-Stage Liver Disease) score. In this study, we introduced a new adsorbent material for albumin dialysis treatments that improves albumin binding capacity. The new charcoal adsorbent was developed by an evolutionary test schedule. Batch testing of charcoals was performed as steady-state experiments. The charcoal reflecting the highest increase in albumin binding capacity was then introduced to kinetic models: Perfusion tests were designed to evaluate adsorption capacity and kinetics for liver failure marker toxins. A dynamic recirculation model for liver failure was used for upscaling and comparison against conventional MARS adsorbents as the gold standard in an albumin dialysis setting. Batch tests revealed that powdered activated Hepalbin charcoal displayed the highest ABiC score. Hepalbin charcoal also demonstrated higher adsorptive capacity and kinetics for liver failure marker toxins as determined by perfusion tests. These findings translated to tests of upscaled adsorbents in a dynamic model for liver failure: upscaled Hepalbin adsorbent removes bile acids, direct bilirubin and indirect bilirubin significantly better than MARS adsorbents and significantly increases ABiC. The novel adsorbent Hepalbin offers a significant improvement over both MARS adsorbents concerning liver failure marker toxin removal and ABiC improvement.

Potential Drug Interactions Mediated by Renal Organic Anion Transporter OATP4C1

Organic anion-transporting polypeptide 4C1 (OATP4C1) is an organic anion transporter expressed in the basolateral membrane of the renal proximal tubules. It plays a major role in the urinary excretion of both exogenous drugs and endogenous compounds. Our previous studies have indicated the importance of OATP4C1 in pathologic and physiologic conditions; however, the majority of its pharmacologic characteristics remained unclear. Therefore, to provide essential information for clinical drug therapy decisions and drug development, we clarified drug interactions mediated by OATP4C1. To elucidate potential drug interactions via OATP4C1, we screened 53 representative drugs commonly used in clinical settings. Next, we evaluated the IC50 values of drugs that inhibited OATP4C1 by more than 50%. To apply our results to clinical settings, we calculated the drug-drug interaction (DDI) indices. The screening analysis using an OATP4C1-expressing cell system demonstrated that 22 out of 53 therapeutic drugs inhibited OATP4C1-mediated triiodothyronine transport. In particular, OATP4C1-mediated transport was strongly inhibited by 10 drugs. The IC50 values of 10 drugs-nicardipine, spironolactone, fluvastatin, crizotinib, levofloxacin, clarithromycin, ritonavir, saquinavir, quinidine, and verapamil-obtained in this study were 51, 53, 41, 24, 420, 200, 8.5, 4.3, 100, and 110 µM, respectively. The IC50 values of these drugs were higher than the plasma concentrations obtained in clinical practice. However, ritonavir showed the highest DDI index (1.9) for OATP4C1, suggesting that it may strongly influence this transporter and thus cause drug interactions seen in clinical settings. Our finding gives new insight into the role of OATP4C1 in clinical DDIs.

Evaluation of an ADVanced Organ Support (ADVOS) system in a two-hit porcine model of liver failure plus endotoxemia

Background

Novel extracorporeal procedures are constantly being developed and evaluated for use in patients with sepsis. Preclinical evaluation of such procedures usually requires testing in large animal models. In the present work, the safety and efficacy of a recently developed ADVanced Organ Support (ADVOS) system in a newly developed large animal two-hit model of liver failure combined with endotoxemia were tested.

Methods

After establishing the model in more than 50 animals, a randomized study was performed. An inflammatory cholestatic liver injury was initially provoked in pigs. Three days after surgery, endotoxin was gradually administered during 7½ h. Animals were randomized to receive standard medical treatment either with (ADVOS group, n = 5) or without ADVOS (control group, n = 5). The ADVOS treatment was started 2½ h after endotoxemia and continued for 7 h. Survival, cardiovascular, respiratory, renal, liver, coagulation, and cerebral parameters were analyzed.

Results

Three days after surgery, cholestatic injury resulted in hyperbilirubinemia [5.0 mg/dl (IQR 4.3–5.9 mg/dl)], hyperammonemia [292 μg/dl (IQR 291–296 μg/dl)], leukocytosis [20.2 10³/μl (IQR 17.7–21.8 10³/μl)], and hyperfibrinogenemia [713 mg/dl (IQR 654–803 mg/dl)]. After endotoxemia, the ADVOS procedure stabilized cardiovascular, respiratory, and renal parameters and eliminated surrogate markers as bilirubin [2.3 (IQR 2.3–3.0) vs. 5.5 (IQR 4.6–5.6) mg/dl, p = 0.001] and creatinine [1.4 (IQR 1.1–1.7) vs. 2.3 (IQR 2.1–3.1) mg/dl, p = 0.01]. Mortality: All animals in the ADVOS group survived, while all animals in the control group expired during the 10-h observation period (p = 0.002). No adverse events related to the procedure were observed.

Conclusions

The ADVOS procedure showed a promising safety and efficacy profile and improved survival in a sepsis-like animal model with dysfunction of multiple organs. An amelioration of major organ functions (heart and lung) combined with removal of markers for kidney and liver function was observed.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-017-0144-3) contains supplementary material, which is available to authorized users.

Structural and functional integrity of human serum albumin: Analytical approaches and clinical relevance in patients with liver cirrhosis

Human serum albumin (HSA) is the most abundant circulating plasma protein. Besides a significant contribution to the osmotic pressure, it is also involved in the fine regulation of many other physiological processes, including the balance of the redox state, the inflammatory and/or immunological responses, and the pharmacokinetic and pharmacodynamics of many drugs. Growing evidence suggests that HSA undergoes structural and functional damage in diseases characterized by an enhanced systemic inflammatory response and oxidative stress, as it occurs in chronic liver disease. Based on their clinical relevance, this review provides a summary of the most common post-translational modifications affecting HSA structural integrity and functions and their clinical relevance in the field of liver disease. The review also provides a critical description of the analytical approaches employed for the investigation of conformational alterations and the identification/quantitation of specific post-translational modifications affecting HSA. Finally, the analytical methods available for the assessment of two of the most clinically relevant non-oncotic properties of HSA, namely the binding capacity and the antioxidant activity, are critically reviewed. Among the available techniques particular attention is given to those proposed for the in vitro and in vivo investigation of structurally modified albumin.

Redox status of serum apolipoprotein E and its impact on HDL cholesterol levels

BACKGROUND

Apolipoprotein E (apoE) is closely involved in the pathogenesis of apoE-related diseases, such as Alzheimer's disease and cardiovascular disease. The redox modulation of cysteine-thiols in a protein is involved in various pathophysiological regulations; however, that of apoE has not been studied in detail. Herein, we devised an analytical method to determine the redox status of serum apoE and assessed its relation to serum cholesterol levels and apoE phenotype.

METHODS

The present method was based on a band shift assay, using a photocleavable maleimide-conjugated polyethylene glycol.

RESULTS

The basic characteristics of the present method were found to be satisfactory to determine the redox status of serum apoE quantitatively. Serum apoE was separated into its reduced-form (r-), non-reduced-form (nr-), apoE-AII complex, and homodimer using this method. R-apoE could be detected as a 40-kDa band, whereas nr-apoE remained as monomeric apoE. R-apoE displayed a preference for VLDL; however, the levels showed the correlation with HDL-cholesterol levels (p<0.005). Redox status of serum apoE was significantly different among apoE phenotypes. The quantitative ratios of nr-apoE to total apoE in serum from subjects with apoE4/E3 were higher than in serum from subjects with apoE3/E3 (p<0.0001) and apoE3/E2 (p<0.001).

CONCLUSION

The redox status of serum apoE might be related to the synthesis of HDL. The information concerning the redox status of serum apoE provided by the present method may be a potent indicator to evaluate various apoE-related diseases.

Clinical Implications Associated With the Posttranslational Modification-Induced Functional Impairment of Albumin in Oxidative Stress-Related Diseases

Recent research findings indicate that the posttranslational modification of human serum albumin (HSA) such as oxidation, glycation, truncation, dimerization, and carbamylation is related to certain types of diseases. We report herein on a simple and rapid analytical method, using an electrospray ionization time-of-flight mass spectrometry technique, that allows posttranslational modifications of HSA to be quantitatively and qualitatively evaluated with a high degree of sensitivity. In patients with chronic liver disease, chronic renal disease, and diabetes mellitus, an increase in the level of oxidized cysteine-34 (Cys-34) of HSA accompanied by a decrease in the level of reduced Cys-34 was observed. The redox status of Cys-34 was correlated with ligand binding and the antioxidative functions of HSA. Available evidence indicates that monitoring the redox state of Cys-34 not only could be a useful marker for evaluating the progression of disease and its complications but also would permit therapeutic efficacy to be predicted. The redox state of Cys-34 was also used as an index of the quality of HSA preparations. These data suggest that monitoring the posttranslational modifications of HSA can be important, because the function of HSA is related not only to its serum concentration but also to the preservation of its structural integrity under disease conditions.

Hyperoxidized albumin modulates neutrophils to induce oxidative stress and inflammation in severe alcoholic hepatitis

Albumin is a potent scavenger of reactive oxygen species (ROS). However, modifications in albumin structure may reduce its antioxidant properties and modulate its immune-regulatory functions. We examined alterations in circulating albumin in severe alcoholic hepatitis (SAH) patients and their contribution to neutrophil activation, intracellular stress, and alteration in associated molecular pathways. Albumin modifications and plasma oxidative stress were assessed in SAH patients (n = 90), alcoholic cirrhosis patients (n = 60), and healthy controls (n = 30) using liquid chromatography/mass spectrometry and spectrophotometry. Activation and intracellular ROS were measured in healthy neutrophils after treatment with purified albumin from the study groups. Gene expression of SAH neutrophils was analyzed and compared to gene expression from healthy neutrophils after stimulation with purified albumin from SAH patient plasma. SAH-albumin showed the highest albumin oxidative state (P < 0.05) and prominent alteration as human nonmercaptalbumin 2 (P < 0.05). Plasma oxidative stress (advanced oxidative protein product) was higher in SAH versus alcoholic cirrhosis patients and healthy controls (P < 0.05). Neutrophil gelatinase-associated lipocalin, myeloperoxidase, and intracellular ROS levels were highest in SAH-albumin-treated neutrophils (P < 0.05). Genes associated with neutrophil activation, ROS production, intracellular antioxidation, and leukocyte migration plus genes for proinflammatory cytokines and various toll-like receptors were overexpressed in SAH neutrophils compared to healthy neutrophils (P < 0.05). Expression of the above-mentioned genes in SAH-albumin-stimulated healthy neutrophils was comparable with SAH patient neutrophils, except for genes associated with apoptosis, endoplasmic reticulum stress, and autophagy (P < 0.05).

CONCLUSIONS

In patients with SAH, there is a significant increase in albumin oxidation, and albumin acts as a pro-oxidant; this promotes oxidative stress and inflammation in SAH patients through activation of neutrophils. (Hepatology 2017;65:631-646).

A simple, rapid and validated high-performance liquid chromatography method suitable for clinical measurements of human mercaptalbumin and non-mercaptalbumin

Background Human mercaptalbumin and human non-mercaptalbumin have been reported as markers for various pathological conditions, such as kidney and liver diseases. These markers play important roles in redox regulations throughout the body. Despite the recognition of these markers in various pathophysiologic conditions, the measurements of human mercaptalbumin and non-mercaptalbumin have not been popular because of the technical complexity and long measurement time of conventional methods. Methods Based on previous reports, we explored the optimal analytical conditions for a high-performance liquid chromatography method using an anion-exchange column packed with a hydrophilic polyvinyl alcohol gel. The method was then validated using performance tests as well as measurements of various patients' serum samples. Results We successfully established a reliable high-performance liquid chromatography method with an analytical time of only 12 min per test. The repeatability (within-day variability) and reproducibility (day-to-day variability) were 0.30% and 0.27% (CV), respectively. A very good correlation was obtained with the results of the conventional method. Conclusions A practical method for the clinical measurement of human mercaptalbumin and non-mercaptalbumin was established. This high-performance liquid chromatography method is expected to be a powerful tool enabling the expansion of clinical usefulness and ensuring the elucidation of the roles of albumin in redox reactions throughout the human body.

Oral branched-chain amino acid granules improve structure and function of human serum albumin in cirrhotic patients

BACKGROUND AND AIMS

The aim of this study was to evaluate structural and functional alterations of human serum albumin (HSA), with a special focus on the oxidized and reduced forms, in patients with chronic liver disease. We also investigated whether oral branched-chain amino acid (BCAA) supplementation could induce structural changes and improve the functions of HSA.

METHODS

The proportion of reduced and oxidized HSA was determined in 16 healthy controls and in 20 chronic hepatitis and 100 cirrhotic patients with stable conditions. To evaluate the functional properties of HSA, this study focused on the antioxidant and binding functions. The radical scavenging activity and binding ability of purified HSA were measured in 68 participants. After BCAA administration for 6 months, 29 patients were evaluated for HSA structural changes, with 19 out of the 29 patients also analyzed for HSA functional changes.

RESULTS

There was a significant decrease in the amounts of reduced HSA in conjunction with liver disease progression. Receiver operating characteristic curve analysis demonstrated that the levels of reduced HSA had high accuracy in determining disease progression. Functional alterations were strongly correlated to the levels of reduced HSA. BCAA supplementation led to substantial increases in the amount of reduced HSA. The altered HSA was able to scavenge significantly more radicals and restore the binding ability.

CONCLUSION

This study describes structural alterations and functional disturbances of HSA in patients with chronic liver disease, and indicates that the levels of reduced HSA might reflect disease progression and the functional properties of HSA. Moreover, oral BCAA supplementation increases the amount of reduced HSA, thereby leading to the restoration of HSA function in cirrhotic patients.

Albumin Binding Function: The Potential Earliest Indicator for Liver Function Damage

Background. Currently there is no indicator that can evaluate actual liver lesion for early stages of viral hepatitis, nonalcoholic fatty liver disease (NAFLD), and cirrhosis. Aim of this study was to investigate if albumin binding function could better reflect liver function in these liver diseases. Methods. An observational study was performed on 193 patients with early NAFLD, viral hepatitis, and cirrhosis. Cirrhosis patients were separated according to Child-Pugh score into A, B, and C subgroup. Albumin metal ion binding capacity (Ischemia-modified albumin transformed, IMAT) and fatty acid binding capacity (total binding sites, TBS) were detected. Results. Both IMAT and TBS were significantly decreased in patients with NAFLD and early hepatitis. In hepatitis group, they declined prior to changes of liver enzymes. IMAT was significantly higher in cirrhosis Child-Pugh class A group than hepatitis patients and decreased in Child-Pugh class B and class C patients. Both IMAT/albumin and TBS/albumin decreased significantly in hepatitis and NAFLD group patients. Conclusions. This is the first study to discover changes of albumin metal ion and fatty acid binding capacities prior to conventional biomarkers for liver damage in early stage of liver diseases. They may become potential earliest sensitive indicators for liver function evaluation.

Comparison of Posttranslational Modification and the Functional Impairment of Human Serum Albumin in Commercial Preparations

On account of its long circulating half-life, human serum albumin (HSA) is susceptible to posttranslational modifications that can alter its functions. Here, we comprehensively compared the degree of posttranslational modifications with the functional impairment of HSA derived from 5 different commercially available albumin preparations and clarified their relationships. We used electrospray ionization-time of flight mass spectrometry to evaluate the degree of posttranslational modification of the entire HSA molecule that was associated with disease development and found that the fraction of Cys34-cysteinylated HSA (Cys-Cys34-HSA), a major form of oxidative modification, varied substantially among the albumin preparations. Meanwhile, no remarkable difference was found in the degree of glycated or N-terminal truncated HSA among the preparations tested. The nonosmotic pressure maintenance functions of HSA, such as its antioxidative and ligand-binding activities significantly differed among the preparations. Interestingly, the alternations of these functions showed a significantly negative correlation only with the Cys-Cys34-HSA fraction. These findings suggest that the Cys-Cys34-HSA fraction, as estimated by electrospray ionization-time of flight mass spectrometry can be used as a predictive marker for the functional impairment of albumin preparations and that it would be preferable to use albumin preparations with higher contents of functionally effective albumin that correspond to a lower degree of cysteinylation of Cys34 in clinical practice.

Neuroinflammation in liver disease: sessional talks from ISHEN

At the recent ISHEN ('International Symposium of Hepatic Encephalopathy & Nitrogen Metabolism') conference in London, a whole session was dedicated to our increasing awareness of the importance of inflammation in the brain - termed 'neuroinflammation', in the development of Hepatic Encephalopathy (HE) - the neurological manifestations of advanced liver disease. In this review our ISHEN speakers further discuss the content of their sessional presentations and more broadly we discuss our understanding of the role of neuroinflammation in HE pathogenesis.

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.

N-acetyl-L-methionine is a superior protectant of human serum albumin against post-translational oxidation as compared to N-acetyl-L-tryptophan

Sodium octanoate and N-acetyl-L-tryptophan (N-AcTrp) are widely used as stabilizers during pasteurization and storage of albumin products. However, as compared with N-AcTrp, N-acetyl-L-methionine (N-AcMet) is superior in protecting albumin exposed to light during storage. Here, we examine, whether N-AcMet also is better than N-AcTrp to protect albumin against oxidation. Recombinant human serum albumin (rHSA) without and with N-AcMet or N-AcTrp was oxidized by using chloramine-T (CT) as a model compound for mimicking oxidative stress. Oxidation of rHSA was examined by determining carbonyl groups and advanced oxidation protein products. Structural changes were studied by native-PAGE, circular dichroism, intrinsic fluorescence and differential scanning calorimetry. The anti-oxidant capacity of CT-treated rHSA was quantified by its ability to scavenge peroxynitrite and the hydroxyl radical. The pharmacokinetics of indocyanine green-labeled albumin preparations was studied in male mice. We found that the number of chemical modifications and the structural changes of rHSA were significantly smaller in the presence of N-AcMet than in the presence of N-AcTrp. The anti-oxidant properties of CT-exposed rHSA were best protected by adding N-AcMet. Finally, N-AcMet is superior in preserving the normal pharmacokinetics of rHSA. Thus, N-AcMet is superior to N-AcTrp in protecting albumin preparations against oxidation. In addition, N-AcMet is probable also useful for protecting other proteins. Therefore, N-AcMet should be useful as a new and effective stabilizer and antioxidant for albumin isolated from blood, rHSA, albumin-fusion proteins and for preparations of rHSA-therapeutic complexes.

[Hepatorenal syndrome in decompensated cirrhosis : A special form of acute renal failure]

Renal failure is a serious complication in patients with advanced cirrhosis. It occurs in about 20 % of patients hospitalized with cirrhosis. In about 70 % it is caused by prerenal failure, and in 30 % it is due to intrarenal causes. In about 70 % of patients with rperenal failure, renal function can be restored with fluid replacement, but the remaining 30 % are unresponsive to volume expansion. Minor increase in serum creatinine have been shown to be clinically relevant and can adversely affect survival. Therefore early efforts should be made to avoid precipitation of renal failure.Hepatorenal syndrome (HRS) is a  fully reversible impairment of renal function in patients with cirrhosis unresponsive to volume expansion characterized by an acute progressive decrease in kidney function (serumcreatinin > 1,5 mg/dl) - type 1 HRS, whereas type 2 HRS features a decrease in kidney function over a long time, mostly in patients with refractory ascites. Therapy with vasoconstrictors like terlipressin to reverse splanchnic vasodilation, together with albumin is effective in 30-50 % of patients with HRS 1 and improves survival. The only effective longterm therapy is livertransplantation. An improvement of kidney fuction before transplantation is associated with a better outcome and posttransplant kidney function.

A study on the effect of the internal exposure to (210)Po on the excretion of urinary proteins in rats

This study was designed to assess the feasibility of a noninvasive urine specimen for the detection of proteins as indicators of internal exposure to ionizing radiation. Three groups of rats (five in each group) were intravenously injected with 1601 ± 376, 10,846 ± 591 and 48,467 ± 2812 Bq of (210)Po in citrate form. A sham-exposed control group of five rats was intravenously injected with sterile physiological saline. Daily urine samples were collected over 4 days following injection. Purification and pre-concentration of urinary proteins were carried out by ultrafiltration using a 3000 Da molecular weight cutoff membrane filter. The concentration of common urinary proteins, namely albumin, alpha-1-acid glycoprotein, immunoglobulins IgA and IgG, was measured by an enzyme-linked immunosorbent assay. Urinary excretion of albumin decreased dose-dependently (p < 0.05) 96 h post-injection relative to the control group. In contrast, no statistically significant effects were observed for other proteins tested. The dose-dependent decrease in urinary excretion of albumin observed in this study underscores the need for further research, which may lead to the discovery of new biomarkers that would reflect the changes in the primary target organs for deposition of (210)Po.

Human albumin solution for patients with cirrhosis and acute on chronic liver failure: Beyond simple volume expansion

To provide an overview of the properties of human serum albumin (HSA), and to review the evidence for the use of human albumin solution (HAS) in critical illness, sepsis and cirrhosis. A MEDLINE search was performed using the terms “human albumin”, “critical illness”, “sepsis” and “cirrhosis”. The references of retrieved articles were reviewed manually. Studies published between 1980 and 2014 were selected based on quality criteria. Data extraction was performed by all authors. HSA is the main plasma protein contributing greatly to its oncotic pressure. HSA demonstrates important binding properties for endogenous and exogenous toxins, drugs and drug metabolites that account for its anti-oxidant and anti-inflammatory properties. In disease states, hypoalbuminaemia is secondary to decreased HSA production, increased loss or transcapillary leakage into the interstitial space. HSA function can be also altered in disease with reduced albumin binding capacity and increased production of modified isoforms. HAS has been used as volume expander in critical illness, but received criticism due to cost and concerns regarding safety. More recent studies confirmed the safety of HAS, but failed to show any survival benefit compared to the cheaper crystalloid fluids, therefore limiting its use. On the contrary, in cirrhosis there is robust data to support the efficacy of HAS for the prevention of circulatory dysfunction post-large volume paracentesis and in the context of spontaneous bacterial peritonitis, and for the treatment of hepato-renal syndrome and hypervolaemic hyponatraemia. It is likely that not only the oncotic properties of HAS are beneficial in cirrhosis, but also its functional properties, as HAS replaces the dysfunctional HSA. The role of HAS as the resuscitation fluid of choice in critically ill patients with cirrhosis, beyond the established indications for HAS use, should be addressed in future studies.

Extracorporeal support for patients with acute and acute on chronic liver failure

The number of patients developing liver failure; acute on chronic liver failure and acute liver failure continues to increase, along with the demand for donor livers for transplantation. As such there is a clinical need to develop effective extracorporeal devices to support patients with acute liver failure or acute-on-chronic liver failure to allow time for hepatocyte regeneration, and so avoiding the need for liver transplantation, or to bridge the patient to liver transplantation, and also potentially to provide symptomatic relief for patients with cirrhosis not suitable for transplantation. Currently devices can be divided into those designed to remove toxins, including plasma exchange, high permeability dialyzers and adsorption columns or membranes, coupled with replacement of plasma proteins; albumin dialysis systems; and bioartificial devices which may provide some of the biological functions of the liver. In the future we expect combinations of these devices in clinical practice, due to the developments in bioartificial scaffolds.

Alteration of methotrexate binding to human serum albumin induced by oxidative stress. Spectroscopic comparative study

Changes of oxidative modified albumin conformation by comparison of non-modified (HSA) and modified (oHSA) human serum albumin absorption spectra, Red Edge Excitation Shift (REES) effect and fluorescence synchronous spectra were investigated. Studies of absorption spectra indicated that changes in the value of absorbance associated with spectral changes in the region from 200 to 250nm involve structural alterations related to variations in peptide backbone conformation. Analysis of the REES effect allowed for the observation of changes caused by oxidation in the region of the hydrophobic pocket containing the tryptophanyl residue. Synchronous fluorescence spectroscopy confirmed changes of the position of the tryptophanyl and tyrosil residues fluorescent band. Effect of oxidative stress on binding of methotrexate (MTX) was investigated by spectrofluorescence, UV-VIS and (1)HNMR spectroscopy. MTX caused the fluorescence quenching of non-modified (HSA) and modified (oHSA) human serum albumin molecule. The values of binding constants, Hill's coefficients and a number of binding sites in the protein molecule in the high affinity binding site were calculated for the binary MTX-HSA and MTX-oHSA systems. For these systems, qualitative analysis in the low affinity binding sites was performed with the use of the (1)HNMR technique.

Role of albumin in diseases associated with severe systemic inflammation: Pathophysiologic and clinical evidence in sepsis and in decompensated cirrhosis

The metabolism of albumin in inflammatory states such as sepsis or major surgery is complex and still not well characterized. Nevertheless, in inflammatory states, albumin synthesis has been observed to increase. By contrast, in decompensated cirrhosis, a disease characterized by systemic inflammation, albumin synthesis by the liver may decrease to 30% to 50% of normal values. Furthermore, in these conditions, there are high capillary leakage and altered albumin kinetics. The discussion regarding the effect of exogenous albumin administration on intravascular volume in inflammatory states should therefore address albumin turnover. To add complexity to our understanding of the effects of albumin, there are many data indicating that the therapeutic action of albumin is mediated not only through the impact on plasma volume expansion but also through a modulatory effect on inflammation and oxidative stress. All these characteristics are relevant to diseases associated with systemic inflammation including sepsis and decompensated cirrhosis.

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.

Mechanisms of decompensation and organ failure in cirrhosis: From peripheral arterial vasodilation to systemic inflammation hypothesis

The peripheral arterial vasodilation hypothesis has been most influential in the field of cirrhosis and its complications. It has given rise to hundreds of pathophysiological studies in experimental and human cirrhosis and is the theoretical basis of life-saving treatments. It is undisputed that splanchnic arterial vasodilation contributes to portal hypertension and is the basis for manifestations such as ascites and hepatorenal syndrome, but the body of research generated by the hypothesis has revealed gaps in the original pathophysiological interpretation of these complications. The expansion of our knowledge on the mechanisms regulating vascular tone, inflammation and the host-microbiota interaction require a broader approach to advanced cirrhosis encompassing the whole spectrum of its manifestations. Indeed, multiorgan dysfunction and failure likely result from a complex interplay where the systemic spread of bacterial products represents the primary event. The consequent activation of the host innate immune response triggers endothelial molecular mechanisms responsible for arterial vasodilation, and also jeopardizes organ integrity with a storm of pro-inflammatory cytokines and reactive oxygen and nitrogen species. Thus, the picture of advanced cirrhosis could be seen as the result of an inflammatory syndrome in contradiction with a simple hemodynamic disturbance.

Pathogenesis of Hepatorenal Syndrome: Implications for Therapy

Patients with cirrhosis are prone to develop acute kidney injury (AKI) due to a number of causes, including bacterial infections with or without septic shock, hypovolemia, administration of nephrotoxic drugs, and intrinsic kidney diseases, among others. Most importantly, patients with advanced cirrhosis develop a distinctive cause of AKI, characterized by rapidly progressive glomerular filtration rate loss associated with marked disturbances in circulatory function in the absence of obvious pathologic abnormalities in the kidneys, known as hepatorenal syndrome (HRS). Decreased kidney function results from intense renal vasoconstriction secondary to the complex circulatory changes of cirrhosis with splanchnic vasodilatation and effective hypovolemia. Beyond activation of vasoactive systems, factors including impaired renal blood flow autoregulation and systemic inflammation may play a role in the development of HRS. Most patients improve with albumin and vasopressors; however, the prognosis of HRS remains very poor. Novel biomarkers may be helpful in distinguishing HRS from other causes of AKI in patients with cirrhosis.

Albumin in chronic liver disease: structure, functions and therapeutic implications

Human serum albumin is a critical plasma protein produced by the liver with a number of accepted clinical indications in chronic liver disease including management of circulatory and renal dysfunction in patients with ascites. Advanced cirrhosis is characterised by reduced albumin concentration as well as impaired albumin function as a result of specific structural changes and oxidative damage. Traditionally, the biologic and therapeutic role of albumin in liver disease was attributed to its oncotic effects but it is now understood that albumin has a wide range of other important physiologic functions such as immunomodulation, endothelial stabilisation, antioxidant effects and binding multiple drugs, toxins and other molecules. This review discusses the multifunctional properties of albumin and, in particular, the biologic and clinical implications of structural and functional changes of albumin that are associated with cirrhosis. Based on these insights, we explore the current and potential future therapeutic uses of albumin in liver disease.

Extracorporeal liver assist device to exchange albumin and remove endotoxin in acute liver failure: Results of a pivotal pre-clinical study

BACKGROUND & AIMS

In acute liver failure, severity of liver injury and clinical progression of disease are in part consequent upon activation of the innate immune system. Endotoxaemia contributes to innate immune system activation and the detoxifying function of albumin, critical to recovery from liver injury, is irreversibly destroyed in acute liver failure. University College London-Liver Dialysis Device is a novel artificial extracorporeal liver assist device, which is used with albumin infusion, to achieve removal and replacement of dysfunctional albumin and reduction in endotoxaemia. We aimed to test the effect of this device on survival in a pig model of acetaminophen-induced acute liver failure.

METHODS

Pigs were randomised to three groups: Acetaminophen plus University College London-Liver Dialysis Device (n=9); Acetaminophen plus Control Device (n=7); and Control plus Control Device (n=4). Device treatment was initiated two h after onset of irreversible acute liver failure.

RESULTS

The Liver Dialysis Device resulted in 67% reduced risk of death in acetaminophen-induced acute liver failure compared to Control Device (hazard ratio=0.33, p=0.0439). This was associated with 27% decrease in circulating irreversibly oxidised human non-mercaptalbumin-2 throughout treatment (p=0.046); 54% reduction in overall severity of endotoxaemia (p=0.024); delay in development of vasoplegia and acute lung injury; and delay in systemic activation of the TLR4 signalling pathway. Liver Dialysis Device-associated adverse clinical effects were not seen.

CONCLUSIONS

The survival benefit and lack of adverse effects would support clinical trials of University College London-Liver Dialysis Device in acute liver failure patients.

Serum Albumin Can Identify Patients With Compensated Cirrhosis With a Good Prognosis

BACKGROUND

Many prognostic studies in cirrhosis were performed without distinguishing between compensated and decompensated patients and/or have evaluated the prognostic role of variables that are not routinely used. The aim was to evaluate predictors of survival in compensated and decompensated cirrhosis separately but in a concurrent cohort and focused on routine clinical variables.

METHODS

Secondary analysis of a prospective cohort with cirrhosis collected in a tertiary center between August 2000 and May 2002 and followed until death or April 2006. Univariate, stratified univariate analysis, and multivariate Cox regression analysis were performed. Receiving operating characteristics curves were used to identify the best cutoff of variables predictive of death.

RESULTS

A total of 242 patients were included (122 compensated, 120 decompensated). In a median follow-up of 30 months (range, 6 to 50 mo), 62 (26%) deaths occurred, 24 (20%) in the compensated and 38 (32%) in the decompensated group. In the whole cohort, decompensation was the strongest predictor of death. In the compensated group, age, albumin, and platelets and in the decompensated group model for end-stage liver disease, platelets, and albumin were identified as independent predictors of death. A serum albumin of 4 g/dL was the best cutoff to identify patients at risk for death in the compensated group with a hazard ratio of 13.3 [95% confidence interval, 1.8-98.8] in those with an albumin of <4.0 g/dL.

CONCLUSIONS

Albumin is a predictor of death in compensated and decompensated cirrhosis. In compensated cirrhosis a subset patients with particularly good prognosis can be identified. Different predictors were observed in both stages, confirming that compensated and decompensated cirrhosis are 2 separate disease stages.

Treatment to improve acute kidney injury in cirrhosis

OPINION STATEMENT

Acute kidney injury (AKI) is an ominous complication of decompensated cirrhosis, which can be fatal if not treated promptly. It is important that clinicians recognize that AKI has occurred and institute timely treatment. Recent establishment of diagnostic criteria and treatment guidelines are most useful, and these will be further refined as treatments are being modified to improve patient outcome. To manage such a patient, firstly, the cause of the AKI needs to be identified and any precipitating factors corrected. Bacterial infections are a common cause of AKI in cirrhosis, and it is recommended to offer empirical antibiotics in cases of suspicious bacterial infection until all the cultures are negative. Patients should be given albumin infusion in doses of 1 g/kg of body weight for at least 2 days. This can improve the filling of the central circulation, and also absorb many of the bacterial products or inflammatory cytokines that play a role in mediating the renal dysfunction. Often, albumin infusion alone may be sufficient to reverse the AKI. For patients who have acute or type 1 hepatorenal syndrome (HRS1), which is a special form of AKI, pharmacotherapy in the form of vasoconstrictor will be needed. The vasoconstrictor can be terlipressin, norepinephrine, or midodrine, depending on the local availability of drugs or facilities. Currently, approximately 40 % of patients will respond to a combination of vasoconstrictor and albumin. All patients with HRS1 should be assessed for liver transplant. If accepted for liver transplantation, those patients who do not respond to vasocontrictors and albumin need to be started on renal replacement therapy, which otherwise has no place in the treatment of HRS1. Once listed, liver transplantation should occur promptly, preferable under 2 weeks. Otherwise, the chances for renal recovery after liver transplant are significantly reduced, necessitating a renal transplant at the future date.

Albumin-induced circular dichroism in Congo red: Applications for studies of amyloid-like fibril aggregates and binding sites

Congo red (CR), one of the most commonly used dyes for the identification of amyloid fibril aggregates, is also a ligand of native bovine serum albumin (BSA). Induced circular dichroism (ICD) is a phenomenon observed when a chiral compound induces chirality in an achiral one. Here, we study the spectral properties and analytical applications of ICD in Congo red provoked by its interaction with BSA. The complex BSA:CR displays a strong ICD spectrum with a positive band at 412 nm and two negative bands at 356 and 490 nm. The use of site I and site II albumin ligands as warfarin and ibuprofen, respectively, provoked different alterations in the Congo red ICD spectrum. The BSA binding sites were modified by oxidation and the ICD signal was sensitive to this alteration. The thermal treatment of the BSA:CR complex (30-90 °C) was monitored by ICD at 490 nm and showed a sigmoidal pattern typical of phase transition in proteins. The altered ICD spectrum is consistent with the formation of amyloid-like fibril aggregates in BSA, which was confirmed by thioflavin T and Rayleigh scattering assays. In conclusion, the ICD provoked by the binding of Congo red to albumin may represent a new spectroscopic technique for studying alterations in the structure of albumin regarding its binding sites and the formation of amyloid aggregates.

Branched-chain amino acids reduce hepatic iron accumulation and oxidative stress in hepatitis C virus polyprotein-expressing mice

BACKGROUND & AIMS

Branched-chain amino acids (BCAA) reduce the incidence of hepatocellular carcinoma (HCC) in patients with cirrhosis. However, the mechanisms that underlie these effects remain unknown. Previously, we reported that oxidative stress in male transgenic mice that expressed hepatitis C virus polyprotein (HCVTgM) caused hepatic iron accumulation by reducing hepcidin transcription, thereby leading to HCC development. This study investigated whether long-term treatment with BCAA reduced hepatic iron accumulation and oxidative stress in iron-overloaded HCVTgM and in patients with HCV-related advanced fibrosis.

METHODS

Male HCVTgM were fed an excess-iron diet that comprised either casein or 3.0% BCAA, or a control diet, for 6 months.

RESULTS

For HCVTgM, BCAA supplementation increased the serum hepcidin-25 levels and antioxidant status [ratio of biological antioxidant potential (BAP) relative to derivatives of reactive oxygen metabolites (dROM)], decreased the hepatic iron contents, attenuated reactive oxygen species generation, and restored mitochondrial superoxide dismutase expression and mitochondrial complex I activity in the liver compared with mice fed the control diet. After 48 weeks of BCAA supplementation in patients with HCV-related advanced fibrosis, BAP/dROM and serum hepcidin-25 increased and serum ferritin decreased compared with the pretreatment levels.

CONCLUSIONS

BCAA supplementation reduced oxidative stress by restoring mitochondrial function and improved iron metabolism by increasing hepcidin-25 in both iron-overloaded HCVTgM and patients with HCV-related advanced fibrosis. These activities of BCAA may partially account for their inhibitory effects on HCC development in cirrhosis patients.

Treatment and management of ascites and hepatorenal syndrome: an update

Ascites and renal dysfunction are frequent complications experienced by patients with cirrhosis of the liver. Ascites is the pathologic accumulation of fluid in the peritoneal cavity, and is one of the cardinal signs of portal hypertension. The diagnostic evaluation of ascites involves assessment of its granulocyte count and protein concentration to exclude complications such as infection or malignoma and to allow risk stratification for the development of spontaneous peritonitis. Although sodium restriction and diuretics remain the cornerstone of the management of ascites, many patients require additional therapy when they become refractory to this treatment. In this situation, the treatment of choice is repeated large-volume paracentesis. Alteration in splanchnic hemodynamics is one of the most important changes underlying the development of ascites. Further splanchnic dilation leads to changes in systemic hemodynamics, activating vasopressor agents and leading to decreased renal perfusion. Small alterations in renal function influence the prognosis, which depends on the cause of renal failure. Prerenal failure is evident in about 70% of patients, whereas in about 30% of patients the cause is hepatorenal syndrome (HRS), which is associated with a worse prognosis. Therefore, effective therapy is of great clinical importance. Recent data indicate that use of the new definition of acute kidney injury facilitates the identification and treatment of patients with renal insufficiency more rapidly than use of the current criteria for HRS. In this review article, we evaluate approaches to the management of patients with ascites and HRS.

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

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.

Human serum albumin, systemic inflammation, and cirrhosis

Human serum albumin (HSA) is one of the most frequent treatments in patients with decompensated cirrhosis. Prevention of paracentesis-induced circulatory dysfunction, prevention of type-1 HRS associated with bacterial infections, and treatment of type-1 hepatorenal syndrome are the main indications. In these indications treatment with HSA is associated with improvement in survival. Albumin is a stable and very flexible molecule with a heart shape, 585 residues, and three domains of similar size, each one containing two sub-domains. Many of the physiological functions of HSA rely on its ability to bind an extremely wide range of endogenous and exogenous ligands, to increase their solubility in plasma, to transport them to specific tissues and organs, or to dispose of them when they are toxic. The chemical structure of albumin can be altered by some specific processes (oxidation, glycation) leading to rapid clearance and catabolism. An outstanding feature of HSA is its capacity to bind lipopolysaccharide and other bacterial products (lipoteichoic acid and peptidoglycan), reactive oxygen species, nitric oxide and other nitrogen reactive species, and prostaglandins. Binding to NO and prostaglandins are reversible, so they can be transferred to other molecules at different sites from their synthesis. Through these functions, HSA modulates the inflammatory reaction. Decompensated cirrhosis is a disease associated systemic inflammation, which plays an important role in the pathogenesis of organ or system dysfunction/failure. Although, the beneficial effects of HAS have been traditionally attributed to plasma volume expansion, they could also relate to its effects modulating systemic and organ inflammation.

Immune dysfunction in cirrhosis

Innate and adaptive immune dysfunction, also referred to as cirrhosis-associated immune dysfunction syndrome, is a major component of cirrhosis, and plays a pivotal role in the pathogenesis of both the acute and chronic worsening of liver function. During the evolution of the disease, acute decompensation events associated with organ failure(s), so-called acute-on chronic liver failure, and chronic decompensation with progression of liver fibrosis and also development of disease specific complications, comprise distinct clinical entities with different immunopathology mechanisms. Enhanced bacterial translocation associated with systemic endotoxemia and increased occurrence of systemic bacterial infections have substantial impacts on both clinical situations. Acute and chronic exposure to bacteria and/or their products, however, can result in variable clinical consequences. The immune status of patients is not constant during the illness; consequently, alterations of the balance between pro- and anti-inflammatory processes result in very different dynamic courses. In this review we give a detailed overview of acquired immune dysfunction and its consequences for cirrhosis. We demonstrate the substantial influence of inherited innate immune dysfunction on acute and chronic inflammatory processes in cirrhosis caused by the pre-existing acquired immune dysfunction with limited compensatory mechanisms. Moreover, we highlight the current facts and future perspectives of how the assessment of immune dysfunction can assist clinicians in everyday practical decision-making when establishing treatment and care strategies for the patients with end-stage liver disease. Early and efficient recognition of inappropriate performance of the immune system is essential for overcoming complications, delaying progression and reducing mortality.

Cys34-cysteinylated human serum albumin is a sensitive plasma marker in oxidative stress-related chronic diseases

The degree of oxidized cysteine (Cys) 34 in human serum albumin (HSA), as determined by high performance liquid chromatography (HPLC), is correlated with oxidative stress related pathological conditions. In order to further characterize the oxidation of Cys34-HSA at the molecular level and to develop a suitable analytical method for a rapid and sensitive clinical laboratory analysis, the use of electrospray ionization time-of-flight mass spectrometer (ESI-TOFMS) was evaluated. A marked increase in the cysteinylation of Cys34 occurs in chronic liver and kidney diseases and diabetes mellitus. A significant positive correlation was observed between the Cys-Cys34-HSA fraction of plasma samples obtained from 229 patients, as determined by ESI-TOFMS, and the degree of oxidized Cys34-HSA determined by HPLC. The Cys-Cys34-HSA fraction was significantly increased with the progression of liver cirrhosis, and was reduced by branched chain amino acids (BCAA) treatment. The changes in the Cys-Cys34-HSA fraction were significantly correlated with the alternations of the plasma levels of advanced oxidized protein products, an oxidative stress marker for proteins. The binding ability of endogenous substances (bilirubin and tryptophan) and drugs (warfarin and diazepam) to HSA purified from chronic liver disease patients were significantly suppressed but significantly improved by BCAA supplementation. Interestingly, the changes in this physiological function of HSA in chronic liver disease were correlated with the Cys-Cys34-HSA fraction. In conclusion, ESI-TOFMS is a suitable high throughput method for the rapid and sensitive quantification of Cys-Cys34-HSA in a large number of samples for evaluating oxidative stress related chronic disease progression or in response to a treatment.