Changes in the ratio of branched-chain to aromatic amino acids affect the secretion of albumin in cultured rat hepatocytes

Effect of perioperative branched chain amino acids supplementation in liver cancer patients undergoing surgical intervention: A systematic review

BACKGROUND

Branched chain amino acid (BCAA) supplementation has been associated with favourable outcomes in liver malignancies requiring definitive resection or liver transplantation. Currently, there are no updated systematic reviews evaluating the efficacy of perioperative BCAA supplementation in patients undergoing surgery for liver cancer.

AIM

To evaluate the efficacy of perioperative BCAA supplementation in patients undergoing surgery for liver cancer.

METHODS

A systematic review of randomized control trials and observational studies was conducted on PubMed, Embase, Cochrane Library, Scopus, and Web of Science to evaluate the effect of perioperative BCAA supplementation compared to standard in-hospital diet, in liver cancer patients undergoing surgery. Clinical outcomes were extracted, and a meta-analysis was performed on relevant outcomes.

RESULTS

16 studies including 1389 patients were included. Perioperative BCAA administration was associated with reduced postoperative infection [risk ratio (RR) = 0.58 95% confidence intervals (CI): 0.39 to 0.84, P = 0.005] and ascites [RR = 0.57 (95%CI: 0.38 to 0.85), P = 0.005]. There was also a reduction in length of hospital stay (LOS) [weighted mean difference (WMD) = -3.03 d (95%CI: -5.49 to -0.57), P = 0.02] and increase in body weight [WMD = 1.98 kg (95%CI: 0.35 to 3.61, P = 0.02]. No significant differences were found in mortality, cancer recurrence and overall survival. No significant safety concerns were identified.

CONCLUSION

Perioperative BCAA administration is efficacious in reducing postoperative infection, ascites, LOS, and increases body weight in liver cancer patients undergoing surgical resection.

Branched-chain amino acids supplementation improves liver frailty index in frail compensated cirrhotic patients: a randomized controlled trial

BACKGROUND

Physical frailty is related with morbidity and mortality in patients with cirrhosis. Currently, there is no approved treatment of frailty in these patients. Here, we evaluated the efficacy of 16 weeks branched-chain amino acids (BCAA) supplementation on frailty in frail compensated cirrhotic patients.

METHODS

After a 4-week run-in period consisted of dietary and exercise counseling, compensated cirrhotic patients with frailty, defined by liver frailty index (LFI)≥4.5, were randomly assigned (1:1) to BCAA or control group. The BCAA group received twice daily BCAAs supplementation (210 kcal, protein 13.5 g, BCAA 2.03 g) for 16 weeks. The primary outcome was frailty reversion. The secondary outcomes were changes in biochemistries, body composition evaluated by bioelectrical impedance analysis, and quality of life (QoL).

RESULTS

54 patients were prospectively enrolled (age 65.5 ± 9.9 years, 51.9% female, Child-Pugh A/B 68.5%/31.5%, MELD 10.3 ± 3.1). Baseline characteristics were similar between both groups. At week 16, BCAA group had a significant improvement in LFI (-0.36 ± 0.3 vs. -0.15 ± 0.28, P = 0.01), BMI (+ 0.51 ± 1.19 vs. -0.49 ± 1.89 kg/m², P = 0.03), and serum albumin (+ 0.26 ± 0.27 vs. +0.06 ± 0.3 g/dl, P = 0.01). The proportion of frailty reversion at week 16 was significantly higher in BCAA group (36% vs. 0%, P < 0.001). Compared with baseline, BCAA group had a significant increase in skeletal muscle index (7.5 ± 1.6 to 7.8 ± 1.5 kg/m², P = 0.03). Regarding the QoL, only the BCAA group had a significant improvement in all 4 domains of physical component score of the SF-36 questionnaire.

CONCLUSIONS

A 16-week BCAA supplementation improved frailty in frail compensated cirrhotic patients. In addition, this intervention resulted in an improvement of muscle mass and physical domain of QoL in these patients.

TRIAL REGISTRATION

This study was registered with Thai Clinical Trial Registry (TCTR20210928001; https://www.thaiclinicaltrials.org/# ).

Hepatocellular Metabolic Abnormalities Induced by Long-Term Exposure to Novel Brominated Flame Retardant, Hexabromobenzene

Novel brominated flame retardants (NBFRs) are widely used to avoid environmental accumulation concerns and because of the regulations imposed on classical BFRs. However, recent studies have not revealed the negative effects of NBFR accumulation and exposure on humans. We conducted a metabolomics study on hexabromobenzene (HBB), one of the NBFRs, to investigate its effect on hepatocytes. Gas chromatography-mass spectrometry-based metabolite profiling was performed to observe metabolic perturbations by treating human livertissue-derived HepG2 cell lines with HBB for maximum 21 days. Metabolic pathway enrichment using 17 metabolite biomarkers determined via univariate and multivariate statistical analysis verified that long-term accumulation of HBB resulted in distinct diminution of eight amino acids and five other metabolites. Molecular docking of the biomarker-related enzymes revealed the potential molecular mechanism of hepatocellular response to HBB exposure, which disrupts the energy metabolism of hepatic cells. Collectively, this study may provide insights into the hidden toxicity of bioaccumulating HBB and unveil the risks associated with non-regulated NBFRs.

Therapeutic mechanisms and beneficial effects of non-antidiabetic drugs in chronic liver diseases

The global burden of chronic liver disease (CLD) is substantial. Due to the limited indication of and accessibility to antiviral therapy in viral hepatitis and lack of effective pharmacological treatment in nonalcoholic fatty liver disease, the beneficial effects of antidiabetics and non-antidiabetics in clinical practice have been continuously investigated in patients with CLD. In this narrative review, we focused on non-antidiabetic drugs, including ursodeoxycholic acid, silymarin, dimethyl4,4'-dimethoxy-5,6,5',6'-dimethylenedixoybiphenyl-2,2'-dicarboxylate, L-ornithine L-aspartate, branched chain amino acids, statin, probiotics, vitamin E, and aspirin, and summarized their beneficial effects in CLD. Based on the antioxidant, anti-inflammatory properties, and regulatory functions in glucose or lipid metabolism, several non-antidiabetic drugs have shown beneficial effects in improving liver histology, aminotransferase level, and metabolic parameters and reducing risks of hepatocellular carcinoma and mortality, without significant safety concerns, in patients with CLD. Although the effect as the centerpiece management in patients with CLD is not robust, the use of these non-antidiabetic drugs might be potentially beneficial as an adjuvant or combined treatment strategy.

Adding Branched-Chain Amino Acids to an Enhanced Standard-of-Care Treatment Improves Muscle Mass of Cirrhotic Patients With Sarcopenia: A Placebo-Controlled Trial

INTRODUCTION

The effect of branched-chain amino acid (BCAA) supplementation on muscle mass in patients with cirrhosis and sarcopenia is unknown.

METHODS

This is a pilot, prospective, randomized, and double-blind study of a cohort of 32 patients with cirrhosis and sarcopenia diagnosed by computed tomography scan who underwent a nutritional and physical activity intervention for 12 weeks. They were divided into 2 groups (placebo: 17 patients; BCAA: 15 patients). The study protocol was registered at ClinicalTrials.gov (NCT04073693).

RESULTS

Baseline characteristics were similar in both groups. After treatment, only the BCAA group presented a significant improvement in muscle mass (43.7 vs 46 cm2/m2; P = 0.023). Seventeen patients (63%) presented improvement in muscle mass overall, which was more frequent in the BCAA group (83.3 vs 46.7%; P = 0.056). Regarding frailty, there was a significant improvement in the Liver Frailty Index in the global cohort (n = 32) after the 12 weeks (4.2 vs 3.9; P < 0.001). This difference was significant in both groups: in the placebo group (4.2 vs 3.8; P < 0.001) and in the BCAA group (4.2 vs 3.9; P < 0.001). After treatment, the BCAA group had a higher increase in zinc levels than the placebo group (Δzinc: 12.3 vs 5.5; P = 0.026). In addition, there was a trend for greater improvement of albumin levels in the BCAA group (Δalbumin: 0.19 vs 0.04; P = 0.091).

DISCUSSION

BCAA supplementation improves muscle mass in cirrhotic patients with sarcopenia.

Are Supplemental Branched-Chain Amino Acids Beneficial During the Oncological Peri-Operative Period: A Systematic Review and Meta-Analysis

BACKGROUND

Branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) are essential amino acids involved in immune responses, and may have roles in protein malnutrition and sarcopenia. Furthermore, certain liver diseases have been associated with a decreased Fischer's ratio (BCAAs to aromatic amino acids; phenylalanine, tyrosine, and tryptophan). We aimed to evaluate the safety and efficacy of BCAAs use in patients with cancer undergoing surgery.

METHODS

MEDLINE, Embase, and CENTRAL were searched (inception to July 24, 2020) for randomized controlled trials (RCTs) and comparative observational studies in English evaluating BCAAs (alone or in combinations) during the oncological peri-operative period. Study selection, data extraction, and quality appraisal were done in duplicate. RCT risk-of-bias was appraised using Cochrane Risk-of-Bias tool, and observational studies' quality assessment was conducted with Newcastle-Ottawa Scale. Meta-analyses were conducted when appropriate.

RESULTS

20 articles were included comprising 13 RCTs and 6 observational cohort studies in 7 reports and 2019 total participants overall. Among 13 RCTs, 77% involved liver cancer. Methodological study quality scored substantial risk-of-bias across most RCTs. Meta-analysis of RCTs found a 38% decreased risk of post-operative infections in BCAAs group compared to controls (RR = 0.62; 95% CI = 0.44 to 0.87; P = .006; number of RCTs, k = 6; total sample size, N = 389; I² = 0%). BCAAs were also found to be beneficial for ascites (RR = 0.55; 95% CI = 0.35 to 0.86; P = .008; k = 4; N = 296; I² = 0%), body weight (MD = 3.24 kg; 95% CI = 0.44 to 6.04; P = .02; k = 3; N = 196; I² = 24%), and hospitalization length (MD = -2.07 days; 95% CI = -3.97 to -0.17; P = .03; k = 5; N = 362; I² = 59%). No differences were found between BCAAs and controls for mortality, recurrence, other post-operative complications (liver failure, edema, pleural effusion), blood loss, quality of life, ammonia level, and prothrombin time. No serious adverse events were related to BCAAs; however, serious adverse events were reported due to intravenous catheters. No safety concerns from observational studies were identified.

CONCLUSIONS

Branched-chain amino acids during the oncological surgical period demonstrated promise in reducing important post-operative morbidity from infections and ascites compared to controls. Blinded, placebo-controlled confirmatory trials of higher methodological quality are warranted, especially using oral, short-term BCAAs-enriched supplements within the context of recent ERAS programs.

PROSPERO REGISTRATION

CRD42018086168.

Untargeted metabolomic profiling of serum from dogs with chronic hepatic disease

Background

Chronic hepatopathies present a diagnostic challenge, with different diseases being associated with similar clinical and laboratory findings. Characterization of dogs with chronic hepatopathies can be difficult and require costly diagnostic procedures such as acquisition of a liver biopsy specimen. Noninvasive and inexpensive biomarkers that reliably characterize chronic hepatopathies such as chronic hepatitis or a congenital portosystemic vascular anomaly may decrease the need for costly or invasive diagnostic testing and guide novel therapeutic interventions.

Objective

To investigate differences in the serum metabolome among healthy dogs, dogs with congenital portosystemic shunts, and dogs with chronic hepatitis.

Animals

Stored serum samples from 12 healthy dogs, 10 dogs with congenital portosystemic shunts, and 6 dogs with chronic hepatitis were analyzed.

Methods

The serum metabolome was analyzed with an untargeted metabolomics approach using gas chromatography–quadrupole time of flight mass spectrometry.

Results

Principal component analysis and heat dendrogram plots of the metabolomics data showed clustering among individuals in each group. Random forest analysis showed differences in the abundance of various metabolites including increased aromatic amino acids and xylitol in dogs with congenital portosystemic shunts. Based on the univariate statistics, 50 metabolites were significantly different among groups.

Conclusions and Clinical Importance

The serum metabolome varies among healthy dogs, dogs with congenital portosystemic shunts, and dogs with chronic hepatitis. Statistical analysis identified several metabolites that differentiated healthy dogs from dogs with vascular or parenchymal liver disease. Further targeted assessment of these metabolites is needed to confirm their diagnostic reliability.

Branched-chain amino acids in liver diseases

Branched chain amino acids (BCAAs) are involved in various bioprocess such as protein metabolism, gene expression, insulin resistance and proliferation of hepatocytes. BCAAs have also been reported to suppress the growth of hepatocellular carcinoma (HCC) cells in vitro and to be required for immune cells to perform the function. In advanced cirrhotic patients, it has been clarified that serum concentrations of BCAA are decreased, whereas those of aromatic amino acids (AAAs) are increased. These alterations are thought to be the causes of hepatic encephalopathy (HE), sarcopenia and hepatocarcinogenesis and may be associated with the poor prognosis of patients with these conditions. Administration of BCAA-rich medicines has shown positive results in patients with cirrhosis.

Effect of branched-chain amino acid supplementation on insulin resistance and quality of life in chronic hepatitis C patients

The incidence rate of insulin resistance (IR) in patients with chronic hepatitis C (CHC) is high. Recently, branched-chain amino acids (BCAA) have been shown to attenuate IR in CHC patients; however, their effect on patient quality of life remains unclear. Therefore, the aim of the current prospective study was to determine the effects of BCAA supplement on IR and health-related quality of life (HR-QoL) in patients with CHC. In the study, 20 non-diabetic patients with CHC, who were non-responders to peginterferon-α and ribavirin, were recruited. Patients took a BCAA supplement once a day (30 g, after a minimum 10-h overnight fast) for 3 months. Serum levels of glucose, insulin, albumin, triglycerides and cholesterol were measured at 0 and 3 months. Additionally, IR was measured using the Homeostasis Model Assessment-IR, HR-QoL was assessed using the 36-item Short Form Health Survey and viral load was measured by reverse transcription polymerase chain reaction using Taqman probes. The Wilcoxon signed-rank test was used to determine statistical significance. The results indicated that 70% of the subjects were positive for IR, which decreased to 50% by the end of the study; furthermore, 85% of the subjects demonstrated some level of improvement. Overall, the BCAA treatment significantly decreased IR (P=0.006) and augmented serum albumin concentration (P=0.008) compared with basal values. Additionally, by the end of the treatment, viral load and triglycerides levels had decreased, though these results were not significant (P=0.084 and P=0.080, respectively). BCAA treatment also improved HR-QoL regarding role limitations due to physical health problems (P=0.017), role limitations due to emotional problems (P=0.026) and social function (P=0.008). In conclusion, BCAA supplementation reduced IR and improved HR-QoL in patients with CHC. These findings support the application of IR therapy as a possible therapeutic strategy for hepatitis C infection.

p62 Promotes Amino Acid Sensitivity of mTOR Pathway and Hepatic Differentiation in Adult Liver Stem/Progenitor Cells

Autophagy is a homeostatic process regulating turnover of impaired proteins and organelles, and p62 (sequestosome-1, SQSTM1) functions as the autophagic receptor in this process. p62 also functions as a hub for intracellular signaling such as that in the mammalian target of rapamycin (mTOR) pathway. Liver stem/progenitor cells have the potential to differentiate to form hepatocytes or cholangiocytes. In this study, we examined effects of autophagy, p62, and associated signaling on hepatic differentiation. Adult stem/progenitor cells were isolated from the liver of mice with chemically induced liver injury. Effects of autophagy, p62, and related signaling pathways on hepatic differentiation were investigated by silencing the genes for autophagy protein 5 (ATG5) and/or SQSTM1/p62 using small interfering RNAs. Hepatic differentiation was assessed based on increased albumin and hepatocyte nuclear factor 4α, as hepatocyte markers, and decreased cytokeratin 19 and SOX9, as stem/progenitor cell markers. These markers were measured using quantitative RT-PCR, immunofluorescence, and Western blotting. ATG5 silencing decreased active LC3 and increased p62, indicating inhibition of autophagy. Inhibition of autophagy promoted hepatic differentiation in the stem/progenitor cells. Conversely, SQSTM1/p62 silencing impaired hepatic differentiation. A suggested mechanism for p62-dependent hepatic differentiation in our study was activation of the mTOR pathway by amino acids. Amino acid activation of mTOR signaling was enhanced by ATG5 silencing and suppressed by SQSTM1/p62 silencing. Our findings indicated that promoting amino acid sensitivity of the mTOR pathway is dependent on p62 accumulated by inhibition of autophagy and that this process plays an important role in the hepatic differentiation of stem/progenitor cells. J. Cell. Physiol. 232: 2112-2124, 2017. © 2016 Wiley Periodicals, Inc.

A Randomized Clinical Trial of Preoperative Administration of Branched-Chain Amino Acids to Prevent Postoperative Ascites in Patients with Liver Resection for Hepatocellular Carcinoma

BACKGROUND

Massive postoperative ascites remains a major threat that can lead to liver failure and other fatal complications, especially in patients with poor liver function. Branched-chain amino acid (BCAA) administration increases biosynthesis and secretion of albumin by hepatocytes and increases oncotic pressure by elevating blood albumin concentration, thereby decreasing peripheral edema, ascites, and pleural effusion.

METHOD

We randomly allocated consecutive patients undergoing major liver resection for hepatocellular carcinoma to either a group where oral BCAA administration was initiated 3 weeks before liver resection, or a non-BCAA group. The primary study endpoint was development of postoperative ascites.

RESULTS

Overall, 39 patients were allocated to the BCAA group, while 38 were assigned to the non-BCAA group. No significant difference in the rate of refractory ascites, considered alone, was evident between the BCAA (5.1 %) and non-BCAA groups (13.2 %; p = 0.263). However, the occurrence of refractory ascites and/or pleural effusion was significantly less frequent in the BCAA group (5.1 %) than in the non-BCAA group (21.1 %; p = 0.047). Furthermore, the postoperative serum concentration of reduced-state albumin was greater immediately after liver resection in the BCAA group than in the non-BCAA group.

CONCLUSION

Preoperative administration of BCAA did not significantly improve prevention of refractory ascites, but significant effectiveness in preventing ascites, pleural effusion, or both, as well as improving metabolism of albumin, was demonstrated [University Hospital Medical Information Network (UMIN) reference number 000004244].

Efficacy and safety of oral branched-chain amino acid supplementation in patients undergoing interventions for hepatocellular carcinoma: a meta-analysis

Most hepatocellular carcinoma (HCC) patients have complications, including cirrhosis and malnutrition. The efficacy of dietary supplementation with oral branched-chain amino acids (BCAAs) in HCC patients undergoing interventions has not been confirmed. Relevant publications on the efficacy and safety of oral BCAA supplementation for HCC patients undergoing anti-HCC interventions through September, 2014 were searched for identification in the PubMed, Embase, Web of Science, and the Cochrane Library databases. The pooled risk ratio (RR) and standardized mean difference (SMD) were used to assess the supplementation effects. A total of 11 eligible studies (974 patients in total) were evaluated and included in our analysis. Oral BCAA supplementation helped to maintain liver reserve with higher serum albumin (SMD = 0.234, 95 % CI: 0.033–0.435, P = 0.022), and lower rates of ascites (RR = 0.545, 95 % CI: 0.316–0.938, P = 0.029) and edema (RR = 0.494, 95 % CI: 0.257–0.952, P = 0.035) than in the control group. BCAA supplementation seemed to be effective in improving mortality, especially in Child-Pugh class B patients, but the efficacy was not confirmed. Apparent effects were not found in improving HCC recurrence, total bilirubin, ALT, or AST. BCAA supplementation was relatively safe without serious adverse events. BCAA supplementation may be clinically applied in improving liver functional reserve for HCC patients and further improving the quality of life.

Oral supplementation with branched-chain amino acid granules prevents hepatocarcinogenesis in patients with hepatitis C-related cirrhosis: A propensity score analysis

AIM

It has been reported that branched-chain amino acids (BCAA) supplementation can improve nutritional status and reduce liver-related complications in patients with decompensated cirrhosis. BCAA supplementation reportedly reduces the incidence of hepatocellular carcinoma (HCC) in obese cirrhotic patients infected with hepatitis C virus (HCV). We investigated the effects of oral supplementation with BCAA granules on hepatocarcinogenesis in patients with HCV-related cirrhosis using propensity score matching.

METHODS

A total of 60 patients with HCV-related cirrhosis and without history of HCC who were selected by one-to-one matching of propensity scores: 30 patients receiving 12 g/day of BCAA granules for 3 months or more (BCAA group) and 30 being observed without BCAA supplementation (control group). The impact of BCAA supplementation was analyzed on the incidence of HCC.

RESULTS

The 3- and 5-year rates of HCC development were 13.7% and 13.7% in the BCAA group and 35.1% and 44.5% in the control group, respectively. The BCAA group had a significantly lower rate of HCC than the control group (P = 0.032). Multivariate analysis for factors that were associated with hepatocarcinogenesis indicated that BCAA supplementation was independently associated with a reduced incidence of HCC (hazard ratio 0.131; 95% confidence interval, 0.032-0.530; P = 0.004) along with sex and serum α-fetoprotein. Obesity (body mass index, ≥25 kg/m(2) ) was not significantly associated with an increased incidence of HCC.

CONCLUSION

Oral supplementation with BCAA granules is associated with a reduced incidence of HCC in patients with HCV-related cirrhosis regardless of the presence of obesity based on the propensity score analysis.

Branched-chain amino acids in liver diseases

Branched chain amino acids (BCAAs) have been shown to affect gene expression, protein metabolism, apoptosis and regeneration of hepatocytes, and insulin resistance. They have also been shown to inhibit the proliferation of liver cancer cells in vitro, and are essential for lymphocyte proliferation and dendritic cell maturation. In patients with advanced chronic liver disease, BCAA concentrations are low, whereas the concentrations of aromatic amino acids such as phenylalanine and tyrosine are high, conditions that may be closely associated with hepatic encephalopathy and the prognosis of these patients. Based on these basic observations, patients with advanced chronic liver disease have been treated clinically with BCAA-rich medicines, with positive effects.

Branched-chain amino acids enhance premature senescence through mammalian target of rapamycin complex I-mediated upregulation of p21 protein

Branched-chain amino acids (BCAAs) have been applied as an oral supplementation to patients with liver cirrhosis. BCAAs not only improve nutritional status of patients but also decrease the incidence of liver cancer. Mammalian target of rapamycin (mTOR) links cellular metabolism with growth and proliferation in response to nutrients, energy, and growth factors. BCAAs, especially leucine, have been shown to regulate protein synthesis through mTOR activities. On the other hand, cellular senescence is suggested to function as tumor suppressor mechanisms, and induced by a variety of stimuli including DNA damage-inducing drugs. However, it is not clear how BCAA supplementation prevents the incidence of liver cancer in patients with cirrhosis. Here we showed that human cancer cells, HepG2 and U2OS, cultured in medium containing BCAAs with Fischer's ratio about 3, which was shown to have highest activities to synthesize and secrete of albumin, had higher activities to induce premature senescence and elevate mTORC1 activities. Furthermore, BCAAs themselves enhanced the execution of premature senescence induced by DNA damage-inducing drugs, which was effectively prevented by rapamycin. These results strongly suggested the contribution of the mTORC1 pathway to the regulation of premature senescence. Interestingly, the protein levels of p21, a p53 target and well-known gene essential for the execution of cellular senescence, were upregulated in the presence of BCAAs. These results suggested that BCAAs possibly contribute to tumor suppression by enhancing cellular senescence mediated through the mTOR signalling pathway.

DNA microarray analysis identified molecular pathways mediating the effects of supplementation of branched-chain amino acids on CCl4-induced cirrhosis in rats

SCOPE

This study addresses the effects of branched-chain amino acids (BCAA) on global gene expression in liver and skeletal muscle and the molecular mechanisms underlying the improvement in liver cirrhosis using DNA microarray analysis combined with RNase protection assay.

METHODS AND RESULTS

Male Wistar rats administered carbon tetrachloride (CCl(4) ) repeatedly for 19 weeks as a decompensated cirrhosis model were thereafter given BCAA-enriched diet (AL) or normal diet (LC) for 5 weeks. The control-diet rats without CCl(4) administration were used as a normal control group. Gene expression in AL was reversed by twofold greater than in LC in the microarray were selected to elucidate the improvements in nutritional and metabolic disorders. Downregulation of fatty acid translocase (FAT)/Cd36, glutamine synthetase, and pyruvate dehydrogenase kinase isoenzyme 4 is believed to promote lower uptake of fatty acids, lower ammonia incorporation, and higher uptake of glucose, and thus to provide an energy source without using BCAA. Ultimately, the catabolism of BCAA and skeletal muscle protein would be slowed, maintaining BCAA concentrations in blood.

CONCLUSION

We established, for the first time, the regulatory gene pathways of processes involved in hepatic fibrosis and energy metabolism (hypoalbuminemia, hyperammonemia, and carbohydrate catabolism, and their relationships) under BCAA supplementation.

Branched-chain amino acids as pharmacological nutrients in chronic liver disease

Branched-chain amino acids (BCAAs) are a group of essential amino acids comprising valine, leucine, and isoleucine. A low ratio of plasma BCAAs to aromatic amino acids is a physiological hallmark of liver cirrhosis, and BCAA supplementation was originally devised with the intention of normalizing amino acid profiles and nutritional status. However, recent studies on BCAAs have revealed that, in addition to their role as protein constituents, they may have a role as pharmacological nutrients for patients with chronic liver disease. Large-scale, multicenter, randomized, double-blinded, controlled trials on BCAA supplementation have been performed in Italy and Japan, and results demonstrate that BCAA supplementation improves not only nutritional status, but also prognosis and quality of life in patients with liver cirrhosis. Moreover, accumulating experimental evidence suggests that the favorable effects of BCAA supplementation on prognosis may be supported by unforeseen pharmacological actions of BCAAs. This review summarizes the possible effects of BCAAs on albumin synthesis and insulin resistance from clinical and basic viewpoints. We also review the newly discovered clinical impact of BCAAs on hepatocellular carcinoma and the prognosis and quality of life of patients with liver cirrhosis.

A randomized pilot trial of oral branched-chain amino acids in early cirrhosis: validation using prognostic markers for pre-liver transplant status

Because of the chronic shortage of liver donors, hepatologists are required to prolong the liver transplant waiting period by preserving the hepatic reserve of scheduled recipients. This study examined the effectiveness of oral branched-chain amino acids (BCAAs), using outcome markers indicating pretransplant hepatic reserve. Fifty-six consecutive eligible patients with Child class A cirrhosis without major complications were randomly assigned to receive oral BCAA granules (12.45 g/day) for least 1 year or no BCAAs. Differences between groups in the Model for End-Stage Liver Disease (MELD) score, Child-Turcotte-Pugh (CTP) score, asialoscintigraphic clearance index (CI), and complications were examined. Of 50 remaining patients, 27 received BCAAs, and 23 received no BCAAs (mean duration, 3.2 years). The mean annual changes in the MELD score, CTP score, and asialoscintigraphic CI were smaller in the BCAA group than in the control group (-0.06 +/- 0.23 versus 0.10 +/- 0.40, P = 0.024, 0.06 +/- 0.30 versus 0.30 +/- 0.48, P = 0.037, and 0.00 +/- 0.02 versus 0.02 +/- 0.04, P = 0.040, respectively). The mean annual changes in the serum total bilirubin and the serum albumin in the BCAA group were better preserved than those in the control group (-0.07 +/- 0.20 versus 0.12 +/- 0.18 mg/dL, P < 0.001, and 0.07 +/- 0.13 versus -0.02 +/- 0.19 g/dL, P = 0.005, respectively); other laboratory variables were not significant. The incidence of overall major cirrhotic complications was lower in the BCAA group than in the control group [14.8% (4 of 27 patients) versus 30.4% (7 of 23 patients) at 3 years, P = 0.043]; only ascites was significant individually. In conclusion, early interventional oral BCAAs might prolong the liver transplant waiting period by preserving hepatic reserve in cirrhosis.

A snack enriched with oral branched-chain amino acids prevents a fall in albumin in patients with liver cirrhosis undergoing chemoembolization for hepatocellular carcinoma

Nutritional support may play an important role in management of liver cirrhosis (LC) associated with unresectable hepatocellular carcinoma (HCC). Total protein and albumin deteriorate in patients with LC undergoing trans-arterial chemoembolization (TACE). Therefore, in this study, we examined the hypothesis that short-term administration of branched-chain amino acids (BCAA) will prevent a fall in total protein and albumin in the perioperative period. The subjects were 56 patients who underwent TACE for HCC between 2004 and 2005 at Nagasaki University Hospital. The patients were randomly placed in the BCAA group (n = 28) or a control group (n = 28). The patients in the BCAA group consumed a snack containing 50 g of BCAA once a day at 10:00 pm starting 1 day before TACE and continuing until 2 weeks after TACE. A comparison of baseline and end point data showed greater decreases in the concentrations of total protein, albumin, cholinesterase, and total cholesterol and in the red blood cell count in the control group compared to the BCAA group. Ammonia levels decreased in the BCAA group and increased in the control group. Our findings indicate that a BCAA supplement taken orally as a late evening snack prevents suppression of liver function by TACE in patients with LC complicated with HCC during the 2-week period after TACE.

Oral branched-chain amino acid supplementation improves the oxidized/reduced albumin ratio in patients with liver cirrhosis

AIM

Branched-chain amino acid (BCAA) supplementation improves hypoalbuminemia in decompensated cirrhotics. Recently, it was clarified that the ratio of oxidized albumin within total albumin rises with progression of liver cirrhosis. We conducted a feasibility study to investigate whether BCAA supplementation might improve this ratio.

METHODS

Seven cirrhotic patients (age: 70 +/-> 6 years; M/F = 4/3; etiology: hepatitis C in six and non-B/non-C hepatitis virus in one; Child-Pugh classification: A in six and B in one) were enrolled consecutively in this study in October 2004 to March 2005. Patients were given 4 g BCAA after each meal for 8 weeks. Serum total, oxidized and reduced albumin, plasma amino acids, glutathione, zinc, selenium, and lipid peroxide concentrations were measured every 2 weeks.

RESULTS

Low total albumin, high oxidized albumin, and low reduced albumin levels were observed at entry. After 8 weeksBCAA supplementation, the ratio of oxidized albumin within total albumin decreased significantly and that of reduced albumin increased significantly (P < 0.05, respectively). Total albumin tended to rise and lipid peroxide concentrations tended to fall, but not significantly.

CONCLUSION

BCAA supplementation improved the oxidized/reduced state of serum albumin. This intervention is effective to maintain the quality of serum albumin in cirrhotic patients.

Localization of polypyrimidine-tract-binding protein is involved in the regulation of albumin synthesis by branched-chain amino acids in HepG2 cells

Long-term supplementation of branched-chain amino acids (BCAA) improves hypoalbuminemia in patients with cirrhosis. Our previous findings have suggested that the binding of polypyrimidine-tract-binding protein (PTB) to rat albumin mRNA attenuates its translation. The aim of the present study was to investigate the role of PTB in the regulation of albumin synthesis by BCAA in human hepatoma cells. HepG2 cells were cultured in a medium containing no amino acids (AA-free medium), a medium containing only 1 amino acid (a BCAA: valine, leucine or isoleucine) or a medium containing all 20 amino acids (AA-complete medium). HepG2 cells cultured in AA-complete medium secreted much more albumin than cells cultured in AA-free medium, with no difference in albumin mRNA levels. In cells cultured in AA-free medium, nuclear export of PTB was observed, and the level of the albumin mRNA-PTB complex was greater than in cells cultured in AA-complete medium. Addition of amino acids stimulated nuclear import of PTB. However, addition of amino acids with rapamycin inhibited the nuclear import of PTB. The addition of leucine, but not of valine or isoleucine, to AA-free medium increased albumin secretion and stimulated the nuclear import of PTB. These data indicate that the mammalian target of rapamycin is involved in the regulation of PTB localization and that leucine promotes albumin synthesis by inhibiting the formation of the albumin mRNA-PTB complex.

BCAA-enriched snack improves nutritional state of cirrhosis

OBJECTIVE

A late evening snack improves the catabolic state in patients with advanced liver cirrhosis. We tested whether long-term (3 mo) late evening snacking that included a branched-chain amino acid (BCAA)-enriched nutrient mixture produces a better nutritional state and better quality of life than ordinary food in patients with hepatitis C virus-positive liver cirrhosis.

METHODS

In a multicenter, randomized study, 48 patients with liver cirrhosis received late-evening supplementation with the BCAA-enriched nutrient mixture or ordinary food, such as a rice ball or bread, for 3 mo. During the study period, each patient was instructed on energy and protein intake. Blood biochemical data, nitrogen balance, respiratory quotient, and health-related quality of life (Short Form 36 questionnaire) were evaluated at baseline and at the end of the study.

RESULTS

Total and late-evening energy intakes were similar in the two groups at 3 mo. Serum albumin level, nitrogen balance, and respiratory quotient were significantly improved by the BCAA mixture but not by ordinary food. The parameters of the Short Form 36 did not statistically significantly improve over 3 mo in either group.

CONCLUSION

Long-term oral supplementation with a BCAA mixture is better than ordinary food in a late evening snack at improving the serum albumin level and the energy metabolism in patients with cirrhosis.

Branched-chain amino acid catabolism in exercise and liver disease

Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, the enzyme catalyst for the second step of the BCAA catabolic pathway, plays a central role in the regulation of BCAA catabolism. The activity of the complex is regulated by a covalent modification cycle in which phosphorylation by BCKDH kinase inactivates and dephosphorylation by BCKDH phosphatase activates the complex. Many studies suggest that control of the activity of the kinase is a primary determinant of the activity of the complex. The kinase exists at all times in the mitochondrial matrix space in two forms, with a large amount being free and a smaller amount bound rather tightly to the BCKDH complex. Only the bound form of the kinase appears to be catalytically active and, therefore, responsible for phosphorylation and inactivation of the complex. alpha-Ketoisocaproate, the transamination product of leucine and the most important known physiological inhibitor of BCKDH kinase, promotes release of the kinase from the complex. alpha-Chloroisocaproate, the analogue of leucine and the most potent known inhibitor of the kinase, is more effective than alpha-ketoisocaproate in promoting release of BCKDH kinase from the complex. Exercise and chronic liver disease (liver cirrhosis) likewise decrease the amount of the kinase bound to the complex in rat liver. The resulting activation of the BCKDH complex appears responsible for the increase in BCAA catabolism caused by exercise and liver cirrhosis. Our findings support the use of BCAA supplements for patients with liver cirrhosis.

Usefulness of granular BCAA after hepatectomy for liver cancer complicated with liver cirrhosis

OBJECTIVE

Nutritional disturbances such as ascites and hypoalbuminemia frequently arise after hepatectomy for liver cancer with liver cirrhosis. We examined the possibility of maintaining a favorable state of nutrition by outpatient administration of branched-chain amino acid (BCAA) granules.

METHODS

Forty-three patients who had gross liver cirrhosis complicated by liver cancer and underwent surgery up to May 2002 were given BCAA granules (n = 21, BCAA group) or no granules (n = 22, control group).

RESULTS

1) Background details such as age, sex, surgical technique, blood loss, and duration of surgery showed no significant differences. 2) Among objective findings, improvement of ascites and edema tended to occur sooner in the BCAA group, but without a significant difference. 3) Although serum albumin recovered its preoperative value 9 mo after surgery in the control group, only 6 mo was required for recovery in the BCAA group. Total protein showed similar changes, but neither group showed any difference in changes of aspartate aminotransferase, alanine transferase, or platelets. 4) One year postoperatively, the change from the preoperative indocyanine green retention rate at 15 min after intravenous administration tended to be worse in the control group, but not significantly so. 5) In the BCAA group, hyaluronic acid and type IV collagen 7S improved significantly sooner than in the control group.

CONCLUSIONS

BCAA supplementation after hepatectomy promotes rapid improvement in protein metabolism and inhibits progression to liver cirrhosis. Administration of BCAA after hepatectomy is considered beneficial to a patient's nutritional state.

Effects of oral branched-chain amino acid granules on event-free survival in patients with liver cirrhosis

BACKGROUND & AIMS

Nutritional intervention with branched-chain amino acid (BCAA) is reported to increase serum albumin concentration in patients with decompensated cirrhosis. However, a definite conclusion on whether it can improve patients' survival has not yet been reached. The present study aimed to test possibilities of improving survival of patients with decompensated cirrhosis by using a BCAA preparation that is suitable for long-term oral administration.

METHODS

A multicenter, randomized, and nutrient intake-controlled trial on the comparative effects of BCAA orally administered at 12 g/day for 2 years versus diet therapy with defined daily food intake (1.0-1.4 g protein kg(-1) day(-1) including BCAA preparation and 25-35 kcal kg(-1) day(-1)) was conducted in 646 patients with decompensated cirrhosis. The primary end point was a composite of death by any cause, development of liver cancer, rupture of esophageal varices, or progress of hepatic failure (event-free survival). The secondary end points were serum albumin concentration and health-related quality of life (QOL) measured by Short Form-36 questionnaire.

RESULTS

The incidence of events comprising the primary end point significantly decreased in the BCAA group as compared with the diet group (hazard ratio, 0.67; 95% confidence interval, 0.49-0.93; P = .015; median observation period, 445 days). Serum albumin concentration increased significantly in the BCAA group as compared with the diet group (P = .018). The "general health perception" domain in Short Form-36 measures was also improved (P = .003). Patients' adherence to the prescription was favorable.

CONCLUSIONS

Oral supplementation with a BCAA preparation that can be administered for a long period improves event-free survival, serum albumin concentration, and QOL in patients with decompensated cirrhosis with an adequate daily food intake.

Posttranscriptional regulation of albumin gene expression by branched-chain amino acids in rats with acute liver injury

We previously demonstrated that the integration of albumin mRNA into functional polysomes was regulated by the supply of branched-chain amino acids (BCAA) in the liver of galactosamine-treated rats. To study the mechanism of this regulation, we investigated interaction between rat liver proteins and albumin transcripts. When albumin transcript was incubated with ribosome salt wash (RSW) extracts prepared from liver, a specific RNA-protein complex (p65) formed. Competition experiments showed that a pyrimidine-rich sequence in the coding region of albumin mRNA was required for the formation of p65. The level of p65 was increased in the RSW extracts prepared from liver of galactosamine-treated rats infused with a standard amino acid formula, compared with a BCAA-enriched amino acid formula. The protein in p65 appears to be polypyrimidine tract-binding protein (PTB), because the formation of p65 was reduced in the RSW extracts pre-incubated with anti-PTB antibody. In cell-free translation analysis, immunodepletion of PTB from rabbit reticulocyte lysate caused an increase in albumin translation. These results suggest that binding of PTB to albumin mRNA suppresses its translation. A supply of BCAA may interfere with this binding and improve the translation efficiency of albumin mRNA in injured liver.

Effects of liver failure on branched-chain alpha-keto acid dehydrogenase complex in rat liver and muscle: comparison between acute and chronic liver failure

BACKGROUND/AIMS

Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex catalyses the committed step in the branched-chain amino acid (BCAA) catabolic pathway. In many cases of liver failure, the serum BCAAs/aromatic amino acids ratio (Fisher's ratio) decreases, and BCAAs have been administered to patients with liver failure to correct this ratio. We conducted an animal study to examine whether the effects on hepatic BCKDH complex differ between acute liver failure (ALF) and chronic liver failure (CLF).

METHODS

ALF and CLF was induced in rats by a single high-dose injection and 21 weeks of repeated low-dose injections of carbon tetrachloride, respectively. Plasma BCAA and branched-chain alpha-keto acid (BCKA) levels, and activities and protein amounts of hepatic BCKDH complex and kinase were measured.

RESULTS

ALF was characterized by elevated plasma BCAA and BCKA levels and decreased hepatic BCKDH activity. CLF was characterized by decreased plasma BCAA and BCKA levels and increased hepatic BCKDH activity. This increase in BCKDH activity in CLF was associated with the decreased BCKDH kinase, which is responsible for the BCKDH inactivation.

CONCLUSIONS

The results obtained in the present study suggest that BCAA catabolism is suppressed in ALF and increased in CLF.

Branched-chain amino acids as a protein- and energy-source in liver cirrhosis

Protein-energy malnutrition (PEM) is a common manifestation in cirrhotic patients with reported incidences as high as 65-90%. PEM affects largely the patients' quality of life and survival. Thus, diagnosis of and intervention for PEM is important in the clinical management of liver cirrhosis. Supplementation with branched-chain amino acids (BCAA) is indicated to improve protein malnutrition. As an intervention for energy malnutrition, frequent meal or late evening snack has been recently recommended. Plasma amino acid analysis characterizes the patients with liver cirrhosis to have decreased BCAA. Such reduction of BCAA is explained by enhanced consumption of BCAA for ammonia detoxication and for energy generation. Supplementation with BCAA raises in vitro the synthesis and secretion of albumin by cultured rat hepatocytes without affecting albumin mRNA expression. BCAA recover the impaired turnover kinetics of albumin both in rat cirrhotic model and in cirrhotic patients. Longer-term supplementation with BCAA raises plasma albumin, benefits quality of life issues, and finally improves survival in liver cirrhosis. Recent interests focused on the timing of administration of BCAA, since daytime BCAA are usually consumed by energy generation for physical exercise of skeletal muscles. Nocturnal BCAA seem to be more favorable as a source of protein synthesis by giving higher nitrogen balance. This minireview focuses on the basic and clinical aspects of BCAA as a pharmaco-nutritional source to control PEM in liver cirrhosis.

Branched-chain amino acids promote albumin synthesis in rat primary hepatocytes through the mTOR signal transduction system

The administration of branched-chain amino acids (BCAAs) to cirrhosis patients increases serum albumin levels and improves the blood Fischer's ratio. Although it has been reported that albumin synthesis in rat primary hepatocytes is diminished under lower Fisher's ratio conditions compared to normal Fischer's ratio conditions, the mode of action at the molecular level for these effects is still uncertain. It has been reported recently that the triggering signal for protein synthesis is transmitted through mTOR (mammalian target of rapamycin). We have had an interest in the mTOR signal transduction system. In the present study, we analyzed the mode of action of BCAA-induced albumin synthesis using rat primary hepatocytes. The BCAA mixture dose-dependently promoted the production of albumin, with leucine being the major effector half of which was inhibited by the mTOR inhibitor rapamycin. We also showed that only leucine induces P70 S6 kinase activation and 4E-BP1 phosphorylation which are mTOR's downstream translational effectors. These activations were completely inhibited by rapamycin. Our results suggest that BCAAs, especially leucine, promote the production of albumin in rat primary hepatocytes through an mTOR signal transduction system.

Effect of the molar ratio of branched-chain to aromatic amino acids on growth and albumin mRNA expression of human liver cancer cell lines in a serum-free medium

Supplementation of branched-chain amino acids (BCAAs) is often used for the treatment of hepatic encephalopathy and low albuminemia in Japan. In this scenario, although many cases are complicated with hepatocellular carcinoma in chronic viral infection, the effect of BCAA levels on hepatocellular carcinoma cells remains unclear. We investigated the effect of the molar ratios of BCAAs to aromatic amino acids (AAAs) on the growth and albumin mRNA expression of cultured human liver cancer cell lines, HCC-M, HCC-T, PLC/PRF/5, and Hep G2. To exclude the effect of fetal serum in culture media on modification of the growth and albumin transcription of cell lines, we used a synthetic serum-free medium. We found that an increase in the molar ratio of BCAAs to AAAs reduced the growth of Hep G2 cells, and it increased albumin mRNA expression in this cell line at a molar ratio of 0.1-10. These results suggest that the molar ratio of BCAAs to AAAs affect the growth and mRNA expression of some liver cancer cells, and supplementation of BCAAs may at least be beneficial to patients with cirrhosis, even complicated with liver cancer.

Impairment of albumin and whole body postprandial protein synthesis in compensated liver cirrhosis

To investigate the anabolic effects of feeding in cirrhosis, we measured albumin fractional synthesis rate (FSR) and whole body protein synthesis in six nondiabetic patients with stable liver cirrhosis (three in the Child-Pugh classification Class A, three in Class B) and in seven normal control subjects, before and after administration of a 4-h mixed meal. Leucine tracer precursor-product relationships and whole body kinetics were employed at steady state. Basal levels of postabsorptive albumin concentration and FSR, whole body leucine rate of appearance, oxidation, and nonoxidative leucine disposal (NOLD, approximately equal to protein synthesis) were similar in the two groups. However, after the meal, in the patients neither albumin FSR (from 8.5 +/- 1.5 to 8.8 +/- 1.8 %/day) nor NOLD (from 1.69 +/- 0.22 to 1.55 +/- 0.26 micromol x kg(-1) x min(-1)) changed (P = nonsignificant vs. basal), whereas they increased in control subjects (albumin FSR: from 10.9 +/- 1.5 to 15.9 +/- 1.9 %/day, P < 0.002; NOLD: from 1.80 +/- 0.14 to 2.10 +/- 0.19 micromol x kg(-1) x min(-1), P = 0.032). Thus mixed meal ingestion did not stimulate either albumin FSR or whole body protein synthesis in compensated liver cirrhosis. The mechanism(s) maintaining normoalbuminemia at this disease stage need to be further investigated.

Branched-chain amino acids

The branched-chain amino acids (BCAA), isoleucine, leucine and valine, are unique in that they are principally metabolized extrahepatically in the skeletal muscle. This observation led to the investigation of these nutrients in a number of clinical scenarios. By far the most intensively studied applications for BCAA have been in patients with liver failure and/or patients in catabolic disease states. However, the resulting studies have not demonstrated a clear clinical benefit for BCAA nutritional supplements. In patients with liver failure, the BCAA did improve nitrogen retention and protein synthesis, but their effect on patient outcome was less clear. Similarly, in critically ill septic patients, BCAA did not improve either survival or morbidity. The BCAA are important nutrients, and it seems that any specific benefits associated with their use will be based upon a greater understanding of the underlying cellular biology. Potential areas of further research may include the combination of BCAA supplements with other anabolic factors (e.g. growth hormone) in managing patients with catabolic disease states.

Investigation of albumin-synthesizing ability in rat cirrhotic liver-derived hepatocytes using primary hepatocyte culture

BACKGROUND/AIMS

In cirrhosis, despite a decrease in the total number of hepatocytes, a normal serum albumin level is maintained during the compensatory stage of the disease in many cases. Therefore, to elucidate the mechanism in hepatocytes related to the regulation of the serum albumin level, the albumin-synthesizing ability of individual hepatocytes was investigated in cirrhotic rats.

METHODS

Cirrhotic rats were prepared by oral administration of furfural to male Wistar rats for 20 weeks. Albumin-synthesizing abilities of liver and of isolated hepatocyte culture were evaluated by measuring the albumin concentration in blood and culture supernatant. Expressions of albumin mRNA were compared using Northern blotting. Furthermore, transcriptional activity of the albumin gene was measured using the promoter domain of the gene.

RESULTS

The total number of hepatocytes in rat cirrhotic liver was significantly decreased compared to that in normal rat liver. However, there were no significant differences in levels of serum albumin or albumin mRNA expression between cirrhotic and normal liver. In primary hepatocyte culture, albumin mRNA expression, the amount of albumin secretion and the albumin promoter activity were clearly enhanced in cirrhotic hepatocytes compared to normal hepatocytes.

CONCLUSION

Although the total number of hepatocytes was decreased in the rat cirrhosis models used in this study, the serum albumin level was maintained and albumin-synthesizing ability was enhanced at the transcriptional level in the individual hepatocytes. These results suggest that the maintenance of serum albumin levels in compensated cirrhosis may be due to enhanced albumin synthesis by the hepatocytes.

Oral supplementation with branched-chain amino acids improves survival rate of rats with carbon tetrachloride-induced liver cirrhosis

We investigated whether supplementation with branched-chain amino acids (BCAA) improves survival of rats with carbon tetrachloride (CCl4) -induced cirrhosis. Liver cirrhosis was induced in 40 male Sprague-Dawley rats by administering CCl4 for 15 weeks. Twenty rats each were then assigned to the control and BCAA group and fed a casein diet or a BCAA-supplemented casein diet, respectively, for an additional 17 weeks with repeated injections of CCl4. No significant difference occurred in either mean energy or nitrogen intake or in body or liver weight between the two groups. BCAA-supplementation significantly preserved plasma albumin concentrations (P < 0.05) and inhibited significantly the occurrence of ascites and hyperammonemia (P < 0.05). The survival rate was significantly higher in the BCAA group (P=0.03), while no significant difference was found in liver histology between the groups. These results suggest that BCAA improved survival of rats with CCl4-induced cirrhosis by preventing hypoalbuminemia and hyperammonemia without directly reducing hepatic necrosis and fibrosis.