Diagnostic value of serum protein profiling by SELDI-TOF ProteinChip compared with a biochemical marker, FibroTest, for the diagnosis of advanced fibrosis in patients with chronic hepatitis C

Mapping Novel Biomarkers of Liver Injury by Tissue Proteomic Analysis

Liver damage is a dynamic process, and evaluation of liver injury degree is the key step in disease diagnosis. However, few common markers among different types of liver injury have been reported. Herein, we generated three liver injury mouse models, including Con A-induced, CCl₄-injected, and subjected bile duct ligation mouse models, to simulate different types of liver damage in humans and then performed a label-free mass spectrometry to identify differentially expressed proteins in liver tissues. Interestingly, two proteins, G3BP and ABCC6, were conserved regulated in different liver injury models and are proposed to be biomarkers in liver injury, with G3BP upregulated and ABCC6 downregulated. Overall, our study identified two novel biomarkers of liver injury, and they might be used as potential drug targets of liver damage research studies.

Impact of contacting study authors to obtain additional data for systematic reviews: diagnostic accuracy studies for hepatic fibrosis

BACKGROUND

Seventeen of 172 included studies in a recent systematic review of blood tests for hepatic fibrosis or cirrhosis reported diagnostic accuracy results discordant from 2 × 2 tables, and 60 studies reported inadequate data to construct 2 × 2 tables. This study explores the yield of contacting authors of diagnostic accuracy studies and impact on the systematic review findings.

METHODS

Sixty-six corresponding authors were sent letters requesting additional information or clarification of data from 77 studies. Data received from the authors were synthesized with data included in the previous review, and diagnostic accuracy sensitivities, specificities, and positive and likelihood ratios were recalculated.

RESULTS

Of the 66 authors, 68% were successfully contacted and 42% provided additional data for 29 out of 77 studies (38%). All authors who provided data at all did so by the third emailed request (ten authors provided data after one request). Authors of more recent studies were more likely to be located and provide data compared to authors of older studies. The effects of requests for additional data on the conclusions regarding the utility of blood tests to identify patients with clinically significant fibrosis or cirrhosis were generally small for ten out of 12 tests. Additional data resulted in reclassification (using median likelihood ratio estimates) from less useful to moderately useful or vice versa for the remaining two blood tests and enabled the calculation of an estimate for a third blood test for which previously the data had been insufficient to do so. We did not identify a clear pattern for the directional impact of additional data on estimates of diagnostic accuracy.

CONCLUSIONS

We successfully contacted and received results from 42% of authors who provided data for 38% of included studies. Contacting authors of studies evaluating the diagnostic accuracy of serum biomarkers for hepatic fibrosis and cirrhosis in hepatitis C patients impacted conclusions regarding diagnostic utility for two blood tests and enabled the calculation of an estimate for a third blood test. Despite relatively extensive efforts, we were unable to obtain data to resolve discrepancies or complete 2 × 2 tables for 62% of studies.

Biomarkers of liver fibrosis

Liver fibrosis is the final common pathway for almost all causes of chronic liver injury. Liver fibrosis is now known to be a dynamic process having significant potential for resolution. Therefore, fibrosis prediction is an essential part of the assessment and management of patients with chronic liver disease. As such, there is strong demand for reliable liver biomarkers that provide insight into disease etiology, diagnosis, therapy, and prognosis in lieu of more invasive approaches such as liver biopsy. Current diagnostic strategies range from use of serum biomarkers to more advanced imaging techniques including transient elastography and magnetic resonance imaging. In addition to these modalities, there are other approaches including the use of novel, but yet to be validated, biomarkers. In this chapter, we discuss the biomarkers of liver fibrosis including the use of invasive and noninvasive biomarkers and disease-specific biomarkers in various chronic liver diseases.

Predicting Discontinuation of Pegylated Interferon as a Result of Lack of Efficacy in United States Veterans With Chronic Hepatitis C on Dual Therapy

BACKGROUND

Many patients with chronic hepatitis C virus (HCV) being treated with pegylated interferon (peg-IFN) plus ribavirin (RBV) do not respond to therapy and do not clear the virus. Standard of care during the era of dual therapy was to discontinue the patient's therapy based on insufficient decreases in viral load after 12 and/or 24 weeks on therapy.

OBJECTIVES

We identified patient characteristics that were significant predictors of discontinuation as a result of lack of efficacy (LOE) in a national database of US veterans with genotypes 1 and 4.

METHODS

We identified US veterans who received care at Veterans Affairs medical centers in 2004-2009 and who had lab-confirmed HCV diagnoses and initiated therapy with peg-IFN plus RBV. Patients who discontinued therapy early were classified as either LOE or non-LOE discontinuers based on pharmacy refill patterns and laboratory response data. Predictors of LOE discontinuation were identified using univariate and multivariable Cox proportional hazards modeling.

RESULTS

Of 321 238 HCV patients with an ICD-9 diagnosis code, 31 215 (9.7%) initiated dual therapy with peg-IFN plus RBV, and 10 333 (3.2%) met all inclusion criteria and were included in the analysis. Overall, 13.6% of the cohort was classified as LOE. Significant predictors of LOE discontinuation included treatment for drug abuse (hazard ratio [HR] = 2.18), age >65 years (HR = 1.75), antiretroviral therapy for HIV (HR = 1.48), black race (HR = 1.47), platelet count >100/mm³ (HR = 1.46), and drug therapy for insomnia (HR = 1.40).

CONCLUSIONS

We identified risk factors for discontinuation caused by LOE. Future work should focus on determining whether these characteristics are also predictive of triple-therapy LOE discontinuations.

Noninvasive Biomarkers of Liver Fibrosis: An Overview

Chronic liver diseases of differing etiologies are among the leading causes of mortality and morbidity worldwide. Establishing accurate staging of liver disease is very important for enabling both therapeutic decisions and prognostic evaluations. A liver biopsy is considered the gold standard for assessing the stage of hepatic fibrosis, but it has many limitations. During the last decade, several noninvasive markers for assessing the stage of hepatic fibrosis have been developed. Some have been well validated and are comparable to liver biopsy. This paper will focus on the various noninvasive biochemical markers used to stage liver fibrosis.

Liver biopsy in modern clinical practice: a pediatric point-of-view

Liver biopsy remains the foundation of evaluation and management of liver disease in children, although the role of the liver biopsy is changing with development of alternative methods of diagnosis and advancement of hepatic imaging techniques. The indications for liver biopsy are evolving as current knowledge of etiologies, noninvasive biomarker alternatives, and treatment options in pediatric liver disease are expanding. The procedure can often be complicated in children by technical difficulties, cost, and smaller specimen size. Communication and partnership of clinicians with pathologists experienced in pediatric liver diseases are essential. DNA sequencing, novel imaging modalities, noninvasive biomarkers of fibrosis and apoptosis, proteomics, and genome-wide association studies offer potential alternative methods for evaluation of liver disease in children. This review presents specific indications, considerations, methods, complications, contraindications, and alternatives for pediatric liver biopsy.

From proteomic multimarker profiling to interesting proteins: thymosin-β(4) and kininogen-1 as new potential biomarkers for inflammatory hepatic lesions

Despite tremendous efforts in disclosing the pathophysiological and epidemiological factors associated with liver fibrogenesis, non-invasive diagnostic measures to estimate the clinical outcome and progression of liver fibrogenesis are presently limited. Therefore, there is a mandatory need for methodologies allowing the reasonable and reliable assessment of the severity and/or progression of hepatic fibrogenesis. We here performed proteomic serum profiling by matrix-assisted laser desorption ionization time-of-flight mass spectrometry in 179 samples of patients chronically infected with hepatitis C virus and 195 control sera. Multidimensional analysis of spectra allowed the definition of algorithms capable to distinguish class-specific protein expression profiles in serum samples. Overall about 100 peaks could be detected per single spectrum. Different algorithms including protein peaks in the range of 2000 and 10,000 Da were generated after pre-fractionation on a weak cation exchange surface. A specificity of 93% with a sensitivity of 86% as mean of the test set results was found, respectively. The nature of three of these protein peaks that belonged to kininogen-1 and thymosin-β₄ was further analysed by tandem mass spectrometry (MS)/MS. We further found that kininogen-1 mRNA was significantly down-regulated in cirrhotic livers. We have identified kininogen-1 and thymosin-β₄ as potential new biomarkers for human chronic hepatitis C and conclude that serum profiling is a reliable technique to identify hepatitis-associated expression patterns. Based on the high throughput capability, the identified differential protein panel may serve as a diagnostic marker and warrants further validation in larger cohorts.

Genomics and proteomics in liver fibrosis and cirrhosis

Genomics and proteomics have become increasingly important in biomedical science in the past decade, as they provide an opportunity for hypothesis-free experiments that can yield major insights not previously foreseen when scientific and clinical questions are based only on hypothesis-driven approaches. Use of these tools, therefore, opens new avenues for uncovering physiological and pathological pathways. Liver fibrosis is a complex disease provoked by a range of chronic injuries to the liver, among which are viral hepatitis, (non-) alcoholic steatohepatitis and autoimmune disorders. Some chronic liver patients will never develop fibrosis or cirrhosis, whereas others rapidly progress towards cirrhosis in a few years. This variety can be caused by disease-related factors (for example, viral genotype) or host-factors (genetic/epigenetic). It is vital to establish accurate tools to identify those patients at highest risk for disease severity or progression in order to determine who are in need of immediate therapies. Moreover, there is an urgent imperative to identify non-invasive markers that can accurately distinguish mild and intermediate stages of fibrosis. Ideally, biomarkers can be used to predict disease progression and treatment response, but these studies will take many years due to the requirement for lengthy follow-up periods to assess outcomes. Current genomic and proteomic research provides many candidate biomarkers, but independent validation of these biomarkers is lacking, and reproducibility is still a key concern. Thus, great opportunities and challenges lie ahead in the field of genomics and proteomics, which, if successful, could transform the diagnosis and treatment of chronic fibrosing liver diseases.

Towards noninvasive detection of oesophageal varices

Current guidelines recommend that all cirrhotic patients should undergo screening endoscopy at diagnosis to identify patients with varices at high risk of bleeding who will benefit from primary prophylaxis. This approach places a heavy burden upon endoscopy units and the repeated testing over time may have a detrimental effect on patient compliance. Noninvasive identification of patients at highest risk for oesophageal varices would limit investigation to those most likely to benefit. Upper GI endoscopy is deemed to be the gold standard against which all other tests are compared, but is not without its limitations. Multiple studies have been performed assessing clinical signs and variables relating to liver function, variables relating to liver fibrosis, and also to portal hypertension and hypersplenism. Whilst some tests are clearly preferable to patients, none appear to be as accurate as upper GI endoscopy in the diagnosis of oesophageal varices. The search for noninvasive tests continues.

Biomarkers of liver fibrosis

Fibrosis prediction is an essential part of the assessment and management of patients with chronic liver disease. Blood-based biomarkers offer a number of advantages over the traditional standard of fibrosis assessment of liver biopsy, including safety, cost-savings and wide spread accessibility. Current biomarker algorithms include indirect surrogate measures of fibrosis, including aminotransaminases and platelet count, or direct measures of fibrinogenesis or fibrinolysis such as hyaluronic acid and tissue inhibitor of metalloproteinase-1. A number of algorithms have now been validated across a range of chronic liver disease including chronic viral hepatitis, alcoholic and non-alcoholic fatty liver disease. Furthermore, several models have been demonstrated to be dynamic to changes in fibrosis over time and are predictive of liver-related survival and overall survival to a greater degree than liver biopsy. Current limitations of biomarker models include a significant indeterminate range, and a predictive ability that is limited to only a few stages of fibrosis. Utilization of these biomarker models requires knowledge of patient co-morbidities which may produce false positive or negative results in a small proportion of individuals. Furthermore, knowledge of the underlying prevalence of fibrosis in the patient population is required for interpretation of the positive or negative predictive values of a test result. Novel proteins identified by proteomic technology and genetic polymorphisms from genome association studies offer the possibility for further refinement and individualization of biomarker fibrosis models in the future.

Clinical proteomics for liver disease: a promising approach for discovery of novel biomarkers

Hepatocellular carcinoma (HCC) is the fifth most common cancer and advanced hepatic fibrosis is a major risk factor for HCC. Hepatic fibrosis including liver cirrhosis and HCC are mainly induced by persistent hepatitis B or C virus infection, with approximately 500 million people infected with hepatitis B or C virus worldwide. Furthermore, the number of patients with non-alcoholic fatty liver disease (NAFLD) has recently increased and NAFLD can progress to cirrhosis and HCC. These chronic liver diseases are major causes of morbidity and mortality, and the identification of non-invasive biomarkers is important for early diagnosis. Recent advancements in quantitative and large-scale proteomic methods could be used to optimize the clinical application of biomarkers. Early diagnosis of HCC and assessment of the stage of hepatic fibrosis or NAFLD can also contribute to more effective therapeutic interventions and an improve prognosis. Furthermore, advancements of proteomic techniques contribute not only to the discovery of clinically useful biomarkers, but also in clarifying the molecular mechanisms of disease pathogenesis by using body fluids, such as serum, and tissue samples and cultured cells. In this review, we report recent advances in quantitative proteomics and several findings focused on liver diseases, including HCC, NAFLD, hepatic fibrosis and hepatitis B or C virus infections.

Can nonalcoholic steatohepatitis be diagnosed without liver biopsy?

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease. The main cause of NAFLD is insulin resistance; therefore, it is necessary to assess liver injury in patients with overweight and insulin resistance-related complications. The two main forms of primary NAFLD, steatosis and steatohepatitis (NASH), most likely represent distinct conditions. At present, the diagnosis of NASH presents drawbacks, including the lack of consensus regarding diagnostic criteria, sampling variability, cost and the invasiveness of the procedure. Based on a critical assessment of the literature, this article aims to determine whether the diagnosis of NASH is clinically useful, and whether it is feasible with noninvasive strategies instead of liver biopsy. A noninvasive diagnosis of NASH would facilitate screening and monitoring of populations at risk, as well as the conduct of therapeutic trials.

Noninvasive tools to assess liver disease

PURPOSE OF REVIEW

Improved understanding of the pathophysiology of fibrosis and recent technological advances have resulted in the development of several serum biomarkers and imaging tools as noninvasive alternatives to biopsy. This review highlights some of the recent advances and potential application of these tools in clinical practice.

RECENT FINDINGS

Several newer approaches have been used to improve the semiquantitative histological assessment of fibrosis in relation to biomarker development. These include statistical considerations, smooth muscle actin morphometry, and emerging microscopy techniques to quantify fibrillar collagen. Serum marker panels, initially developed for determining disease stage in chronic hepatitis C infection, have now been adapted for use in nonalcoholic fatty liver disease. Genetic markers of disease progression have been validated, and newer proteomic technologies are increasingly being applied towards biomarker discovery. A sequential approach or the combination of serum markers and transient elastography is able to significantly reduce the need for biopsy for the diagnosis of cirrhosis. Serum markers also appear to provide useful prognostic information in end-stage liver disease. Newer imaging methods and breath tests require further validation, but appear promising adjunctive techniques for prediction of advanced stage fibrosis and providing functional assessment.

SUMMARY

Current noninvasive tools have potential diagnostic and prognostic utility for end-stage liver disease. Adapting these methods into clinical practice remains a challenge.

Proteomic approaches in the search for biomarkers of liver fibrosis

Chronic liver diseases (CLDs) can cause progressive hepatic fibrosis culminating in cirrhosis. Fibrosis staging requires liver biopsy, which is invasive, expensive and frequently poorly tolerated by patients. Serum-based panels of fibrosis biomarkers have been developed as alternatives to biopsy. Recent advances in high-throughput proteomic methods have the potential to optimise combinations of biomarkers for the diagnosis of liver fibrosis. Here, we review the key recent developments in the field of proteomics and their application to this important clinical question. We critically discuss the challenges and priorities for future research that are of critical importance to clinical hepatology.

The HCV serum proteome: a search for fibrosis protein markers

Liver fibrosis/cirrhosis is a serious health issue in hepatitis C virus (HCV-) infected patients and is currently diagnosed by the invasive liver biopsy. The aim of this study was to find useful fibrosis markers in HCV-patients' sera of different fibrosis degrees (METAVIR F0-F4) based on proteomics. Serum proteome profiles were created by two-dimensional gel electrophoresis. Profiles were analysed between different degrees of fibrosis (F0-F4) and between early (F0F1) and late (F2F3F4) fibrosis by univariate analyses (P <or= 0.05). Differentially expressed proteins were subsequently identified by mass spectrometry. Mac-2-binding protein, alpha-2-macroglobulin and hemopexin were increased in F4 opposite F0/F1. A-1-antitrypsin, leucine-rich alpha-2-glycoprotein and fetuin-A were decreased in F4 opposite F0/F1. Late fibrosis was characterized by an increase in Mac-2-binding protein, alpha-2-macroglobulin and alpha-1B-glycoprotein expression and a decrease in haptoglobin expression. Mac-2-binding protein expression was confirmed by dot blot assay and enzyme-linked immunosorbent assay in a secondary population. In conclusion, serum proteome analysis enabled the detection/identification of existing and new candidate markers in line with fibrosis progression in HCV-patients.

Assessment of fibrosis in chronic liver diseases

The assessment of liver fibrosis provides useful information not only for diagnosis but also for therapeutic decisions. Although liver biopsy is the current gold standard for fibrosis assessment, it has some risks and limitations, including intra-observer and inter-observer variation, sampling error and variability. In recent years, many studies and great interest have been dedicated to the development of non-invasive tests to substitute a liver biopsy for fibrosis assessment and follow up. Advances in serological and radiological tests such as serum marker panels, transient elastography and their combinations can assess fibrosis accurately and reduce the need for a liver biopsy. But at present, all have failed to completely replace a liver biopsy because of their respective limitations and an imperfect gold standard used in current researches. The searching for an ideal surrogate is still in progress.

Biomarkers of liver fibrosis

Liver biopsy, due to its limitations and risks, is an imperfect gold standard for assessing the severity of the most frequent chronic liver diseases. This chapter summarized the advantages and the limits of the available biomarkers of liver fibrosis. Among a total of 2237 references, a total of 14 validated biomarkers have been identified between 1991 and 2007. Nine were not patented and five were patented. FibroTest (FT) was the most studied test with 33 different populations including 6549 patients and 925 controls. The mean diagnostic value for the diagnosis of advanced fibrosis assessed using standardized area under the receiver operating characteristics (ROC) curves was 0.84 [95% confidence interval (CI), 0.83-0.86], without significant difference between the causes of liver disease, hepatitis C, hepatitis B, alcoholic or nonalcoholic fatty liver disease. High-risk profiles of false negative/positive of FT are present in 3% of populations, mainly Gilbert syndrome, hemolysis, and acute inflammation. FT has higher accuracy than aspartate aminotransferase/platelets ratio index (APRI), the most used nonpatented test. No significant difference has been observed between the five patented tests. A quality score has been assessed in order to compare the quality of fibrosis biomarkers. Neither biomarkers nor biopsy are sufficient alone to take definitive decision in a given patient and all the clinical and biological data must be taken into account. Due to the evidence-based data, health authorities in some countries have already approved validated biomarkers as first-line procedure for the staging of liver fibrosis. This overview of evidence-based data suggests that biomarkers could be used as an alternative to liver biopsy for the assessment of fibrosis stage in the four more common chronic liver diseases: C virus (HCV), hepatitis B virus (HBV), hepatitis nonalcoholic fatty liver disease (NAFLD), and alcoholic liver disease (ALD). Neither biomarkers nor biopsy are sufficient alone to take definitive decision in a given patient and all the clinical and biological data must be taken into account.

Noninvasive assessment of liver fibrosis: serum markers, imaging, and other modalities

Liver fibrosis is a common pathway of injury after chronic insult to the liver. The evolution of liver fibrosis to cirrhosis has many clinical implications, including bleeding, infection, hepatocellular carcinoma, and death. The reference standard for diagnosing liver fibrosis is currently histologic assessment of tissue obtained through liver biopsy. Although this provides valuable information, it has limitations, including its invasiveness, sampling error, observer variability, and the use of categorical scoring systems. This article outlines the various noninvasive markers, including blood tests, imaging, and novel technologies. It examines the principles behind their development, their diagnostic accuracy, and their evolution.

[Non-invasive evaluation of liver fibrosis in hepatitis C]

In 2007, the << Haute Autorité de Santé >> recommended FibroScan, FibroTest or liver biopsy for the initial diagnosis of fibrosis in patients with hepatitis C without co morbidities. These methods have to be interpreted according to the clinical situation, keeping in mind negative and positive false results. For FibroTest, hemolysis, Gilbert syndrome or acute inflammation can modify the result. Pre-analytical and analytical conditions of FibroTest have to be respected according to manufactory recommendations. For FibroScan, the numbers of measurements, the rate of successful measurements, and the interquartile range have to be correct. In case of suspicious results, FibroTest or FibroScan have to be done again. The liver biopsy, FibroTest, and FibroScan are less relevant for the distinction of two adjacent stages of fibrosis. However, their performances are excellent for the diagnosis of severe fibrosis or cirrhosis compared to moderate fibrosis.

Use of ProteinChip technology for identifying biomarkers of parasitic diseases: the example of porcine cysticercosis (Taenia solium)

Taenia solium cysticercosis is a significant public health problem in endemic countries. The current serodiagnostic techniques are not able to differentiate between infections with viable cysts and infections with degenerated cysts. The objectives of this study were to identify specific novel biomarkers of these different disease stages in the serum of experimentally infected pigs using ProteinChip technology (Bio-Rad) and to validate these biomarkers by analyzing serum samples from naturally infected pigs. In the experimental sample set 30 discriminating biomarkers (p<0.05) were found, 13 specific for the viable phenotype, 9 specific for the degenerated phenotype and 8 specific for the infected phenotype (either viable or degenerated cysts). Only 3 of these biomarkers were also significant in the field samples; however, the peak profiles were not consistent among the two sample sets. Five biomarkers discovered in the sera from experimentally infected pigs were identified as clusterin, lecithin-cholesterol acyltransferase, vitronectin, haptoglobin and apolipoprotein A-I.

Review article: current management of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome.

AIM

To assess the epidemiological impact and the current management of patients with NAFLD.

METHODS

Published peer-reviewed literature and abstracts concerning NAFLD and non-alcoholic steatohepatitis (NASH) were reviewed. Articles specifically related to epidemiology, diagnosis and current treatment strategies for NAFLD and NASH are summarized.

RESULTS

NAFLD is strongly associated with the epidemic of obesity and type-2 diabetes mellitus, and is estimated to affect about 20-30% of the population in the US. From the spectrum of NAFLD, only patients with biopsy-proven NASH (estimated prevalence in the US population is about 3-5%) have been convincingly shown to progress to cirrhosis, liver failure and hepatocellular carcinoma. The clinical manifestation of NAFLD is usually absent or subtle, with abnormal aminotransferases or incidental radiographic findings of fatty liver. The pathogenesis of NAFLD is attributed to a multi-hit process involving insulin resistance, oxidative stress, apoptotic pathways, and adipocytokines. In 2008, there is no established treatment for NAFLD. Weight loss and treatment for each component of metabolic syndrome. Nevertheless, a large number of agents are being considered in clinical trials of patients with NASH.

CONCLUSIONS

Awareness of the tremendous impact of NAFLD as an important cause of chronic liver disease is increasing along with a great deal of information about its pathogenesis. Future, well-designed clinical trials that target specific pathways involved in the pathogenesis of NASH are urgently needed.

FibroMAX: towards a new universal biomarker of liver disease?

Among the noninvasive alternatives to liver biopsy, several studies have demonstrated the predictive value and a better benefit-to-risk ratio than biopsy of five combinations of simple serum biochemical markers (the super combination being FibroMAX (BioPredictive, Paris, France) in patients at risk of chronic liver diseases: FibroTest (BioPredictive) for the quantitative assessment of fibrosis; SteatoTest (BioPredictive) for the quantitative assessment of steatosis; ActiTest (BioPredictive) for the quantitative assessment of necroinflammatory activity in chronic viral hepatitis C and B; NashTest (BioPredictive) for the categorical diagnosis of nonalcoholic steatohepatitis; and AshTest for the quantitative assessment of alcoholic steatohepatitis (also known in the USA as HCV-FibroSURE, HBV-FibroSURE, ASH-FibroSURE and NASH-FibroSURE; LabCorp, NC, USA). The possible causes of false-negative and false-positive results are also better identified. These tests, which are now available in 50 countries, can facilitate the screening and management of the most frequent liver diseases.