Serum sphingolipids predict de novo hepatocellular carcinoma in hepatitis C cirrhotic patients with sustained virologic response

Risk factors and clinical outcomes in patients with HCV eradication by direct-acting antivirals: a systematic review and meta-analysis

BACKGROUND

In hepatitis C patients with sustained virologic response (SVR) achieved after direct-acting antivirals (DAAs), the incidence of adverse clinical outcomes can be reduced but not completely eliminated. This meta-analysis aims at estimating the incidence of clinical outcomes in hepatitis C patients after achieving SVR with DAAs.

METHODS

Literature search was carried out in PubMed, Cochrane Library database, Web of Science, and Embase. The primary endpoint was the incidence of hepatocellular carcinoma (HCC) occurrence, HCC recurrence, decompensated cirrhosis, and liver-related mortality, following DAA-induced elimination of hepatitis C virus (HCV). Subgroup analyses were performed according to age, gender, comorbidities, region, fibrosis stage, presence of decompensation, duration of follow-up, start point of follow-up, and HCC treatment modality. Furthermore, meta-regression was performed to explore sources of high heterogeneity.

RESULTS

Finally, 132 articles were included in our study. The pooled HCC occurrence rate was 1.50/100 person-years (95% CI, 1.35-1.65), HCC recurrence rate was 17.00/100 person-years (95% CI, 13.83-20.42), decompensation rate was 0.30/100 person-years (95% CI, 0.16-0.48), and liver-related mortality was 0.32/100 person-years (95% CI, 0.14-0.56). Meta-regression showed that duration of follow-up and fibrosis grade were important contributors to HCC occurrence. Age, start point of follow-up, and duration of follow-up were important contributors to HCC recurrence rate.

CONCLUSION

Patients with DAA-induced HCV elimination remain at risk for adverse outcomes, particularly those with cirrhosis and HCC history. The exposure to adverse outcomes tended to decrease over time, and the frequency and intensity of follow-up might be reduced in the future, which will require new scoring models to identify these individuals.

Novel biomarker in hepatocellular carcinoma: Stearoyl-CoA desaturase 1

BACKGROUND

In recent years, more and more studies have shown that reprogramming lipid metabolism plays an important role in the occurrence and development of hepatocellular carcinoma (HCC). However, there is a lack of systematic exploration of fatty acid (FA) profiles in HCC.

AIMS

This study aims to systematically investigate the FA profile in HCC and assess the diagnostic potential of stearoyl-CoA desaturase 1 (SCD1) as a biomarker for HCC.

METHODS

The FA profile in HCC tissues was detected by gas chromatography mass spectrometry. Abnormal FA metabolism was analyzed by qRT-PCR, Western blot. Immunohistochemical and bioinformatics analysis were used to analyze SCD1 expression and function. Receiver operating characteristic curves were used to analyze the diagnostic efficacy of SCD1, and the relationship between SCD1 and immune infiltration in HCC was analyzed by the biological information method.

RESULTS

FAs were found to accumulate in the HCC samples, and abnormal FA metabolism in HCC related to the upregulation of the expression and activity of SCD1. The combination of SCD1 and alpha-fetoprotein produced a greater area under the receiver operating characteristic curve (0.925, P < 0.001) than SCD1 or alpha-fetoprotein alone. It also showed better sensitivity (77.5 %). Besides, high SCD1 expression was found to be related to immune infiltration in HCC.

CONCLUSION

SCD1 can serve as a reliable biomarker for HCC diagnosis.

Acid Sphingomyelinase Activation and ROS Generation Potentiate Antiproliferative Effects of Mitomycin in HCC

Sphingolipids play a major role in the regulation of hepatocellular apoptosis and proliferation. We have previously identified sphingolipid metabolites as biomarkers of chronic liver disease and hepatocellular carcinoma. Human hepatocellular carcinoma cell lines were transfected with a plasmid vector encoding for acid sphingomyelinase. Overexpressing cells were subsequently treated with mitomycin and cell proliferation, acid sphingomyelinase activity, sphingolipid concentrations, and generation of reactive oxygen species were assessed. The stimulation of acid sphingomyelinase-overexpressing cell lines with mitomycin showed a significant activation of the enzyme (p < 0.001) followed by an accumulation of various ceramide species (p < 0.001) and reactive oxygen radicals (p < 0.001) as compared to control transfected cells. Consequently, a significant reduction in cell proliferation was observed in acid sphingomyelinase-overexpressing cells (p < 0.05) which could be diminished by the simultaneous application of antioxidant agents. Moreover, the application of mitomycin induced significant alterations in mRNA expression levels of ceramidases and sphingosine kinases (p < 0.05). Our data suggest that the overexpression of the acid sphingomyelinase in human hepatoma cell lines enhances the in vitro antiproliferative potential of mitomycin via accumulation of ceramide and reactive oxygen species. The selective activation of acid sphingomyelinase might offer a novel therapeutic approach in the treatment of hepatocellular carcinoma.

Surveillance and management of hepatocellular carcinoma after treatment of hepatitis C with direct-acting antiviral drugs

Hepatitis C virus (HCV) belongs to the Flaviviridae family, and is a single-stranded RNA virus with positive polarity. It is the primary cause of hepatocellular carcinoma (HCC) worldwide. The treatment of HCV has entered a new era with the advent of direct-acting antiviral drugs (DAAs) and is associated with cure rates of more than 95 %, making HCV the only curable viral disease. The successful treatment of chronic hepatitis C has greatly reduced, but not eliminated, the risk of HCC. Certain individuals, especially those with cirrhosis already present, remain vulnerable to HCC after achieving a sustained virological response (SVR). This article systematically reviews the recent studies on the risk and mechanisms of HCC development after HCV viral cure, the screening and predictive value of biological markers, and patient surveillance. Factors such as older age, diabetes, hepatic fat accumulation, alcohol use, and lack of fibrosis reversal are linked to increased HCC risk after HCV cure. The mechanism of HCC development after DAAs treatment remains unclear, but the possible mechanisms include immune cell dysfunction during HCV infection, cytokine network imbalance, epigenetic alterations, and host factors. Several biological markers and risk prediction models have been used to monitor the risk of HCC in CHC patients who have achieved SVR, but most still require validation and standardization. The implementation of risk-stratified surveillance programs is becoming urgent from a cost-effective point of view, but the availability of validated biomarkers to predict HCC in cured patients remains an unmet clinical need. Additionally, managing CHC patients who achieve SVR is becoming a growing challenge as an increasing number of HCV patients are cured.

Unmet needs in the post-direct-acting antivirals era: The risk and molecular mechanisms of hepatocellular carcinoma after hepatitis C virus eradication

Hepatitis C virus (HCV) infection is one of the major etiologies of hepatocellular carcinoma (HCC) with approximately 30% of HCC being due to HCV infection worldwide. HCV eradication by antivirals greatly reduces the risk of HCC; nevertheless, HCC remains to occur in chronic hepatitis C (CHC) patients who have achieved a sustained virological response (SVR). The proportion of post-SVR HCC among newly diagnosed HCC patients is increasing in the direct-acting antiviral (DAA) era and might be due to preexisting inflammatory and fibrotic liver backgrounds, immune dysregulation between host and virus interactions, as well as host epigenetic scars, genetic predispositions and alternations. By means of applying surrogate markers and adopting risk stratification, HCC surveillance should be consistently performed in high-risk populations. In this review, we discuss the possible molecular mechanism, risk factors, and HCC surveillance strategy for HCC development after HCV eradication in CHC patients.

Metabolomics as a tool to predict the risk of decompensation or liver-related death in patients with compensated cirrhosis

BACKGROUND AND AIMS

Patients with compensated cirrhosis with clinically significant portal hypertension (CSPH: HVPG > 10 mm Hg) have a high risk of decompensation. HVPG is, however, an invasive procedure not available in all centers. The present study aims to assess whether metabolomics can improve the capacity of clinical models in predicting clinical outcomes in these compensated patients.

APPROACH AND RESULTS

This is a nested study from the PREDESCI cohort (an RCT of nonselective beta-blockers vs. placebo in 201 patients with compensated cirrhosis and CSPH), including 167 patients for whom a blood sample was collected. A targeted metabolomic serum analysis, using ultra-high-performance liquid chromatography-mass spectrometry, was performed. Metabolites underwent univariate time-to-event cox regression analysis. Top-ranked metabolites were selected using Log-Rank p -value to generate a stepwise cox model. Comparison between models was done using DeLong test. Eighty-two patients with CSPH were randomized to nonselective beta-blockers and 85 to placebo. Thirty-three patients developed the main endpoint (decompensation/liver-related death). The model, including HVPG, Child-Pugh, and treatment received ( HVPG/Clinical model ), had a C-index of 0.748 (CI95% 0.664-0.827). The addition of 2 metabolites, ceramide (d18:1/22:0) and methionine (HVPG/Clinical/Metabolite model), significantly improved the model's performance [C-index of 0.808 (CI95% 0.735-0.882); p =0.032]. The combination of these 2 metabolites together with Child-Pugh and the type of treatment received (Clinical/Metabolite model) had a C-index of 0.785 (CI95% 0.710-0.860), not significantly different from the HVPG-based models including or not metabolites.

CONCLUSIONS

In patients with compensated cirrhosis and CSPH, metabolomics improves the capacity of clinical models and achieves similar predictive capacity than models including HVPG.

Metabolic Reprogramming of HCC: A New Microenvironment for Immune Responses

Hepatocellular carcinoma is the most common primary liver cancer, ranking third among the leading causes of cancer-related mortality worldwide and whose incidence varies according to geographical area and ethnicity. Metabolic rewiring was recently introduced as an emerging hallmark able to affect tumor progression by modulating cancer cell behavior and immune responses. This review focuses on the recent studies examining HCC's metabolic traits, with particular reference to the alterations of glucose, fatty acid and amino acid metabolism, the three major metabolic changes that have gained attention in the field of HCC. After delivering a panoramic picture of the peculiar immune landscape of HCC, this review will also discuss how the metabolic reprogramming of liver cancer cells can affect, directly or indirectly, the microenvironment and the function of the different immune cell populations, eventually favoring the tumor escape from immunosurveillance.

The altered lipidome of hepatocellular carcinoma

Alterations in metabolic pathways are a hallmark of cancer. A deeper understanding of the contribution of different metabolites to carcinogenesis is thus vitally important to elucidate mechanisms of tumor initiation and progression to inform therapeutic strategies. Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide and its altered metabolic landscape is beginning to unfold with the advancement of technologies. In particular, characterization of the lipidome of human HCCs has accelerated, and together with biochemical analyses, are revealing recurrent patterns of alterations in glycerophospholipid, sphingolipid, cholesterol and bile acid metabolism. These widespread alterations encompass a myriad of lipid species with numerous roles affecting multiple hallmarks of cancer, including aberrant growth signaling, metastasis, evasion of cell death and immunosuppression. In this review, we summarize the current trends and findings of the altered lipidomic landscape of HCC and discuss their potential biological significance for hepatocarcinogenesis.

Serum Ceramide Species Are Associated with Liver Cirrhosis and Viral Genotype in Patients with Hepatitis C Infection

Hepatitis C virus (HCV) infection affects ceramide metabolism, and, here, we have evaluated associations of eight serum ceramide species with viral load, viral genotype, and disease markers in 178 patients with chronic HCV. In this cohort, ceramide d18:1;O2/16:0 was higher in the serum of the 20 diabetic patients compared to the patients without this complication. Moreover, ceramide d18:1;O2/24:0 was negatively correlated with age. Of note, all but ceramide d18:1;O2/16:0 and 26:0 were diminished in the serum of patients with liver cirrhosis and, with the exception of ceramide d18:1;O2/16:0, were negatively correlated with the model for end-stage liver disease (MELD) score. Most of the serum ceramides are carried in low-density lipoprotein (LDL), which rises following effective direct-acting antiviral (DAA) therapy. Ceramide d18:1;O2/24:0 recovered in parallel with LDL, whereas ceramide d18:1;O2/18:0 declined. Genotype-3-infected patients had the lowest ceramide levels, which were comparable to other genotypes after DAA treatment. Notably, ceramide d18:1;O2/23:0 and 24:0 were negatively correlated with the MELD score in patients with liver cirrhosis at the end of DAA therapy. Long-chain (LC) ceramides show adverse effects, whereas very-long-chain (VL) species have protective functions in the liver. The ratio of VL/LC ceramides was higher in non-cirrhosis patients than cirrhosis patients and further increased at the end of therapy in this subgroup. In summary, our study shows that serum ceramide levels are related to liver cirrhosis and viral genotype. Whether the more favorable serum ceramide profile in non-cirrhosis patients, before and after DAA therapy, is of pathophysiological importance needs further investigation.

Biomarkers for the Detection and Management of Hepatocellular Carcinoma in Patients Treated with Direct-Acting Antivirals

Simple Summary

Chronic Hepatitis C virus (HCV) represents the main etiological factor for hepatocellular carcinoma (HCC) in developed countries. The introduction of direct-acting antivirals (DAAs) improved the eradication of the hepatitis C virus (HCV) but not the reduction in the incidence of HCV-associated HCC. Some patients still develop HCC, even after reaching a sustained virological response (SVR). This review is a summary of pre-clinical studies that investigated predictive biomarkers for HCC occurrence and recurrence in HCV-infected patients treated with DAAs. The presented biomarkers are found dysregulated in serum or tissue at specific time points (before, during, after DAA treatment or post SVR) and correlated with HCC-predisposing conditions. Thus, this review aims to improve the management of patients developing HCV-induced HCC.

Abstract

Hepatocellular carcinoma (HCC) is the sixth-most common type of cancer worldwide and chronic Hepatitis C virus (HCV) represents the main etiological factor in developed countries. HCV promotes hepatocarcinogenesis through persistent liver inflammation and dysregulation of cell signaling pathways. The introduction of direct-acting antivirals (DAAs) resulted in a significant improvement in the eradication of the virus, with an expected reduction of HCC incidence. However, the risk of HCC development can persist after DAA treatment. Recent studies have investigated the potential use of molecular biomarkers that predict HCC occurrence or recurrence helping the stratification of patients under surveillance. This review aimed to summarize all pre-clinical exploration of predictive biomarkers to identify DAA-treated patients at risk for HCC development. Dysregulated microRNAs, lncRNAs, histone modifications, cytokines, proteins, and sphingolipids represent various classes of HCC risk predictors identified in two different biological sources (tissue and serum). The non-invasive serum markers can provide a more accessible means to perform clinical monitoring and predict the risk of HCC. In addition, conditions like cirrhosis, predisposing to HCC, strongly correlate with most of the molecular predictors identified, supporting the value of these molecules as possible biomarkers of HCC in DAA-treated patients.

Untargeted Plasma Metabolomics Reveals Extensive Metabolic Alterations Among Treatment-Naive Human Immunodeficiency Virus/Hepatitis C Virus Co-Infected Patients with Liver Disease Progression

Both human immunodeficiency virus (HIV) and hepatitis C virus (HCV) may induce metabolic disorders and cause liver complications. Therefore, we aim to analyze the metabolite differences among treatment-naive HIV/HCV co-infected patients with versus without liver disease progression (LDP) and HIV mono-infected patients. A cross-sectional study was conducted in 65 HIV/HCV co-infected patients (22 with LDP and 43 without) and 65 HIV mono-infected patients in Dehong prefecture of Yunnan province, China. Plasma metabolomics were measured by gas chromatography-mass spectrometry (MS) and liquid chromatography-MS. Discrimination analysis, pathway enrichment analysis, generalized linear model with binomial distribution, and area under the receiver-operating characteristic curve (AUC) were conducted to identify bilateral differences in metabolites and pathways in different comparison groups. A total of 10,831 with 673 named and 10,158 unnamed metabolites were detected. Compared with HIV/HCV co-infected patients without LDP, phenylalanine, tyrosine, and tryptophan biosynthesis pathway with the increased level of tyrosine were significantly altered among HIV/HCV co-infected patients with LDP. Compared with HIV mono-infected patients, the decreased level of glutamine and increased levels of glutamic acid, arachidonic acid, and its derivatives were identified among HIV/HCV co-infected patients. Metabolite panels adjusted for baseline information had a higher accuracy than baseline model (without metabolite information) in distinguishing HIV/HCV co-infected patients with versus without LDP (AUC 0.951 vs. 0.849, p = .027) and HIV/HCV co-infected patients from HIV mono-infected patients (AUC 0.889 vs. 0.766, p < .001). A novel set of metabolites were found to discriminate HIV/HCV co-infected patients with versus without LDP, and from HIV mono-infected patients, which may have mechanistic and interventional implications.

Risk of hepatocellular carcinoma after hepatitis C virus cure

Hepatitis C virus (HCV) is a significant cause of hepatocellular carcinoma (HCC). The direct-acting antivirals marked a new era of HCV therapy and are associated with greater than 95% cure rate. Successful treatment of chronic hepatitis C greatly reduces the risk of HCC. A proportion of patients, especially those with pre-existing cirrhosis, remain at risk for HCC despite sustained virologic response (SVR). Diabetes mellitus, hepatic steatosis, alcohol consumption and lack of fibrosis regression are associated with risks of HCC after HCV cure. Noninvasive modalities such as aspartate aminotransferase to platelet ratio index and fibrosis-4 index and transient elastography have been used to monitor hepatic fibrosis. More recently, various fibrosis scores have been combined with clinical parameters and other novel biomarkers to predict risks of HCC for patients who achieved SVR. These models still need to be validated and standardized prior to applying to routine clinical care.

Predictive Factors for Hepatocellular Carcinoma Development after Direct-Acting Antiviral Treatment of HCV

Chronic hepatitis C virus infection is still one of the major risk factors for the development of hepatocellular carcinoma (HCC), the most frequent type of primary liver cancer. Direct-acting antivirals have substantially improved the cure rate of the virus, but the risk of hepatitis C virus-related HCC remains high, mainly in patients with advanced liver fibrosis and cirrhosis. HCC is often asymptomatic and, therefore, remains undetected until the late tumor stage, which is associated with poor survival rates. Therefore, to improve the surveillance programs following HCV eradication, there is a need to summarize predictive factors or potential biomarkers, to specifically identify patients likely to develop HCC after direct-acting antiviral treatment. This review outlines the most recent data about different predictive factors for HCC development after direct-acting antiviral treatment of hepatitis C virus-infected patients, to improve the clinical management of patients with chronic hepatitis C virus.

Hepatocellular carcinoma risk after viral response in hepatitis C virus-advanced fibrosis: Who to screen and for how long?

Hepatitis C virus (HCV) chronic infection is associated with fibrosis progression, end-stage liver complications and HCC. Not surprisingly, HCV infection is a leading cause of liver-related morbidity and mortality worldwide. After sustained virological response (SVR), the risk of developing hepatocellular carcinoma is not completely eliminated in patients with established cirrhosis or with advanced fibrosis. Therefore, lifelong surveillance is currently recommended. This strategy is likely not universally cost-effective and harmless, considering that not all patients with advanced fibrosis have the same risk of developing HCC. Factors related to the severity of liver disease and its potential to improve after SVR, the molecular and epigenetic changes that occur during infection and other associated comorbidities might account for different risk levels and are likely essential for identifying patients who would benefit from screening programs after SVR. Efforts to develop predictive models and risk calculators, biomarkers and genetic panels and even deep learning models to estimate the individual risk of HCC have been made in the direct-acting antiviral agents era, when thousands of patients with advanced fibrosis and cirrhosis have reached SVR. These tools could help to identify patients with very low HCC risk in whom surveillance might not be justified. In this review, factors affecting the probability of HCC development after SVR, the benefits and risks of surveillance, suggested strategies to estimate individualized HCC risk and the current evidence to recommend lifelong surveillance are discussed.

Functions of Sphingolipids in Pathogenesis During Host-Pathogen Interactions

Sphingolipids are a class of membrane lipids that serve as vital structural and signaling bioactive molecules in organisms ranging from yeast to animals. Recent studies have emphasized the importance of sphingolipids as signaling molecules in the development and pathogenicity of microbial pathogens including bacteria, fungi, and viruses. In particular, sphingolipids play key roles in regulating the delicate balance between microbes and hosts during microbial pathogenesis. Some pathogens, such as bacteria and viruses, harness host sphingolipids to promote development and infection, whereas sphingolipids from both the host and pathogen are involved in fungus-host interactions. Moreover, a regulatory role for sphingolipids has been described, but their effects on host physiology and metabolism remain to be elucidated. Here, we summarize the current state of knowledge about the roles of sphingolipids in pathogenesis and interactions with host factors, including how sphingolipids modify pathogen and host metabolism with a focus on pathogenesis regulators and relevant metabolic enzymes. In addition, we discuss emerging perspectives on targeting sphingolipids that function in host-microbe interactions as new therapeutic strategies for infectious diseases.

Residual risk of liver disease after hepatitis C virus eradication

Treatment of hepatitis C with direct-acting antivirals is safe and highly efficacious, resulting in viral clearance (sustained virological response [SVR]) in the vast majority of patients. Although SVR is mostly permanent and associated with a significant reduction of liver morbidity and mortality, some patients may still suffer from a major risk of progressive liver damage, potentially leading to severe complications - including liver decompensation, hepatocellular carcinoma and death. This concise review discusses some of the most important features of residual liver disease in patients with chronic hepatitis C who have achieved SVR after antiviral therapy.

Serum Sphingosine-1-Phosphate Is Decreased in Patients With Acute-on-Chronic Liver Failure and Predicts Early Mortality

Sphingosine‐1‐phosphate (S1P) regulates pathophysiological processes, including liver regeneration, vascular tone control, and immune response. In patients with liver cirrhosis, acute deterioration of liver function is associated with high mortality rates. The present study investigated whether serum S1P concentrations are associated with disease severity in patients with chronic liver disease from compensated cirrhosis (CC), acute decompensation (AD), or acute‐on‐chronic liver failure (ACLF). From August 2013 to October 2017, patients who were admitted to the University Hospital Frankfurt with CC, AD, or ACLF were enrolled in our cirrhosis cohort study. Tandem mass spectrometry was performed on serum samples of 127 patients to assess S1P concentration. Our study comprised 19 patients with CC, 55 with AD, and 51 with ACLF, aged 29 to 76 years. We observed a significant decrease of S1P according to advanced liver injury from CC and AD up to ACLF (P < 0.001). S1P levels further decreased with progression to ACLF grade 3 (P < 0.05), and S1P highly inversely correlated with the Model for End‐Stage Liver Disease score (r = −0.508; P < 0.001). In multivariate analysis, S1P remained an independent predictor of 7‐day mortality with high diagnostic accuracy (area under the curve, 0.874; P < 0.001). Conclusion: In patients with chronic liver disease, serum S1P levels dramatically decreased with advanced stages of liver disease and were predictive of early mortality. Because S1P is a potent regulator of endothelial integrity and immune response, low S1P levels may significantly influence progressive multiorgan failure. Our data justify further elucidation of the diagnostic and therapeutic role of S1P in ACLF.

Hyperbaric oxygen treatment mitigates liver damage in mice with noise exposure

Noise exposure relates to various pathological disorders including liver damage, preventive measures of which are being demanded. Hyperbaric oxygen treatment (HBOT), as a non-invasive procedure, exerts convincing therapeutic potency on multiple liver diseases. The efficacy of HBOT in mitigating noise induced liver damage (NILD) and associated mechanisms would be elucidated here. Mice were subject to broad band noise (20-20k Hz, 90-110 dB) for 5 days by 3 hours/day. HBOT with 2.5 atmosphere absolute (ata) was employed before noise exposure. Morphology of liver tissue was examined by hematoxylin-eosin (HE) staining. Oil Red O (ORO), transferase-mediated dUTP nick end labelling (TUNEL) test and western blot were utilized to detect lipid accumulation, apoptotic cells and protein expression, respectively. Ceramide (Cer) level was assayed by immunohistochemistry (IHC) analysis. With noise exposure, conspicuous structural derangement and lipid deposition occurred in liver tissue of mice, which was alleviated significantly by the application of HBOT. Meanwhile, HBOT reduced the proportion of apoptotic hepatocytes, restraining the superoxide production in noise exposed mice. In view of underlying mechanisms, noise enhanced the acid sphingomyelinase (ASM) protein expression and the Cer generation in liver tissue of mice which was reversed substantially by HBOT. Altogether, HBOT ameliorates the structural and functional derangement of liver by neutralizing the ASM/Cer pathway in noise exposed mice.

Role of lipids in pathophysiology, diagnosis and therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive and widespread cancer. Patients with liver cirrhosis of different aetiologies are at a risk to develop HCC. It is important to know that in approximately 20% of cases primary liver tumors arise in a non-cirrhotic liver. Lipid metabolism is variable in patients with chronic liver diseases, and lipid metabolites involved therein do play a role in the development of HCC. Of note, lipid composition of carcinogenic tissues differs from non-affected liver tissues. High cholesterol and low ceramide levels in the tumors protect the cells from oxidative stress and apoptosis, and do also promote cell proliferation. So far, detailed characterization of the mechanisms by which lipids enable the development of HCC has received little attention. Evaluation of the complex roles of lipids in HCC is needed to better understand the pathophysiology of HCC, the later being of paramount importance for the development of urgently needed therapeutic interventions. Disturbed hepatic lipid homeostasis has systemic consequences and lipid species may emerge as promising biomarkers for early diagnosis of HCC. The challenge is to distinguish lipids specifically related to HCC from changes simply related to the underlying liver disease. This review article discusses aberrant lipid metabolism in patients with HCC.

Sphingolipids in Non-Alcoholic Fatty Liver Disease and Hepatocellular Carcinoma: Ceramide Turnover

Non-alcoholic fatty liver disease (NAFLD) has emerged as one of the main causes of chronic liver disease worldwide. NAFLD comprises a group of conditions characterized by the accumulation of hepatic lipids that can eventually lead to non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma (HCC), the fifth most common cancer type with a poor survival rate. In this context, several works have pointed out perturbations in lipid metabolism and, particularly, changes in bioactive sphingolipids, as a hallmark of NAFLD and derived HCC. In the present work, we have reviewed existing literature about sphingolipids and the development of NAFLD and NAFLD-derived HCC. During metabolic syndrome, considered a risk factor for steatosis development, an increase in ceramide and sphigosine-1-phosphate (S1P) have been reported. Likewise, other reports have highlighted that increased sphingomyelin and ceramide content is observed during steatosis and NASH. Ceramide also plays a role in liver fibrosis and cirrhosis, acting synergistically with S1P. Finally, during HCC, metabolic fluxes are redirected to reduce cellular ceramide levels whilst increasing S1P to support tumor growth.

Risk profiling using metabolomic characteristics for susceptible individuals of drug-induced liver injury caused by Polygonum multiflorum

Idiosyncratic drug-induced liver injury (IDILI) is a rare but potentially severe adverse drug reaction. To date, identifying individuals at risk for IDILI remains challenging. This is a prospective study, where a nested case-control (1:5) design was adopted. For six patients who had abnormalities in liver function test after Polygonum multiflorum Thunb. (PM) ingestion (susceptible group), 30 patients with normal liver function were matched (tolerant group). Based on liquid chromatography-mass spectrometry, metabolomics analysis was done on serum samples prior to PM ingestion, to screen the differential metabolites and characterize metabolomic profiles of patient serum in the two groups. Multivariate analysis showed that there were remarkable separations between susceptible and tolerant groups. A total of 25 major differential metabolites were screened out, involving glycerophospholipid metabolism, sphingolipid metabolism, fatty acid metabolism, histidine metabolism and aromatic amino acid metabolism. Wherein, the area under the curve of the receiver operating characteristic curves of metabolites PE 22:6, crotonoyl-CoA, 2E-tetradecenoyl-CoA, phenyllactic acid, indole-5,6-quinone, phosphoribosyl-ATP were all greater than 0.9. The overall serum metabolic profile comprising of 25 metabolites could clearly distinguish susceptible and tolerant groups. This proof-of-concept study used metabolomics to characterize the metabolic profile of IDILI risk individuals before drug ingestion for the first time. The metabolome characteristics in patient serum before PM ingestion may predict the risk of liver injury after PM ingestion.