Serum proteomic MRM identify peptide ions of transferrin as new fibrosis markers in chronic hepatitis B

Identification and characterization of substrates crosslinked by transglutaminases in liver and kidney fibrosis

The transglutaminase (TGase) family consists of eight isozymes that catalyze Ca²⁺-dependent crosslink formation between glutamine and lysine residues of proteins. In the pathogenesis of various chronic diseases, among the TGase isozymes, TG2 in particular is upregulated and contributes to a critical role in fibrosis development and progression via the stabilization of extracellular matrix proteins and activation of TGF-β. Although TG2 has been considered a key enzyme in fibrosis, the causative role of TG2 and involvement of other isozymes remain unclear. We have recently developed a comprehensive analysis method targeting the isozyme-specific substrates of TGase in liver and kidney fibrosis. In this review article, we introduce a previously developed method for determining the activity and tissue distribution of TGase and for the detecting and identification of TGase substrates in an isozyme-specific manner. Using our comprehensive analysis method, we newly characterized the overlapping profile data regarding potential substrates of TG1 and TG2 that have been identified in liver and kidney fibrosis to date. Our results obtained by comparing the specificity and similarity of potential TGase substrates between different tissue fibrosis models provide a deeper understanding regarding the specific and common pathways in disease pathogenesis and progression.

Synthesis of stable isotopically labeled peptides with filter-assisted enzymatic labeling for the diagnosis of hepatitis B virus infection utilizing mass spectrometry-based proteomics strategy

A facile method for the preparation of stable isotopically labeled peptides was developed by means of filter-assisted tryptic ¹⁶O/¹⁸O water labeling, which could be directly applied to the determination of hepatitis B virus infection from human serum with tandem mass spectrometry. Tryptic peptides of hepatitis B surface antigen or hepatitis B e antigen from different subtypes of hepatitis B virus were synthesized with traditional solid-phase peptide synthesis as potential biomarkers. Trypsin catalyzed oxygen-18 exchange at their amidated c-terminus of arginine or lysine residue. The protease catalyzed oxygen-18 to oxygen-16 back exchange reaction was eliminated due to the complete removal of trypsin by the centrifugal filter containing a thin membrane associated with molecular weight cut-off of 10 KDa. The synthetic isotopic peptides were spiked into trichloroacetic acid/acetone precipitated human serum as internal standards and were selectively detected with multiplexed parallel reaction monitoring on a hybrid quadrupole-orbitrap mass spectrometer. The limit of detection for all synthetic peptides were in the range of 0.09 fmol-1.13 fmol. The results indicated that the peptide YLWEWASVR derived from hepatitis B surface antigen was quantified approximately 200 fmol per μl serum and may serve as a diagnostic biomarker for the detection of hepatitis B virus infected disease.

iTRAQ-Based Proteomics Identification of Serum Biomarkers of Two Chronic Hepatitis B Subtypes Diagnosed by Traditional Chinese Medicine

Background. Chronic infection with hepatitis B virus (HBV) is a leading cause of cirrhosis and hepatocellular carcinoma. By traditional Chinese medicine (TCM) pattern classification, damp heat stasis in the middle-jiao (DHSM) and liver Qi stagnation and spleen deficiency (LSSD) are two most common subtypes of CHB. Results. In this study, we employed iTRAQ proteomics technology to identify potential serum protein biomarkers in 30 LSSD-CHB and 30 DHSM-CHB patients. Of the total 842 detected proteins, 273 and 345 were differentially expressed in LSSD-CHB and DHSM-CHB patients compared to healthy controls, respectively. LSSD-CHB and DHSM-CHB shared 142 upregulated and 84 downregulated proteins, of which several proteins have been reported to be candidate biomarkers, including immunoglobulin (Ig) related proteins, complement components, apolipoproteins, heat shock proteins, insulin-like growth factor binding protein, and alpha-2-macroglobulin. In addition, we identified that proteins might be potential biomarkers to distinguish LSSD-CHB from DHSM-CHB, such as A0A0A0MS51_HUMAN (gelsolin), PON3_HUMAN, Q96K68_HUMAN, and TRPM8_HUMAN that were differentially expressed exclusively in LSSD-CHB patients and A0A087WT59_HUMAN (transthyretin), ITIH1_HUMAN, TSP1_HUMAN, CO5_HUMAN, and ALBU_HUMAN that were differentially expressed specifically in DHSM-CHB patients. Conclusion. This is the first time to report serum proteins in CHB subtype patients. Our findings provide potential biomarkers can be used for LSSD-CHB and DHSM-CHB.

Comparison of diagnostic accuracy of aspartate aminotransferase to platelet ratio index and fibrosis-4 index for detecting liver fibrosis in adult patients with chronic hepatitis B virus infection: a systemic review and meta-analysis

The aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis index based on the four factors (Fibrosis 4 index; FIB-4) are the two most widely studied noninvasive tools for assessing liver fibrosis. Our aims were to systematically review the performance of APRI and FIB-4 in hepatitis B virus (HBV) infection in adult patients and compare their advantages and disadvantages. We examined the diagnostic accuracy of APRI and FIB-4 for significant fibrosis, advanced fibrosis, and cirrhosis based on their sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (AUROC). Heterogeneity was explored using metaregression. Our systemic review and meta-analysis included 16 articles of APRI only, 21 articles of APRI and FIB-4 and two articles of FIB-4 for detecting different levels of liver fibrosis. With an APRI threshold of 0.5, 1.0, and 1.5, the sensitivity and specificity values were 70.0% and 60.0%, 50.0% and 83.0%, and 36.9% and 92.5% for significant fibrosis, advanced fibrosis, and cirrhosis, respectively. With an FIB-4 threshold of 1.45 and 3.25, the sensitivity and specificity values were 65.4% and 73.6% and 16.2% and 95.2% for significant fibrosis. The summary AUROC values using APRI and FIB-4 for the diagnosis of significant fibrosis, advanced fibrosis, and cirrhosis were 0.7407 (95% confidence interval [CI]: 0.7033-0.7781) and 0.7844 (95% CI: 0.7450-0.8238; (Z = 1.59, P = 0.06), 0.7347 (95% CI: 0.6790-0.7904) and 0.8165 (95% CI: 0.7707-0.8623; Z = 2.01, P = 0.02), and 0.7268 (95% CI: 0.6578-0.7958) and 0.8448 (95% CI: 0.7742-0.9154; (Z = 2.34, P = 0.01), respectively.

CONCLUSIONS

Our meta-analysis suggests that APRI and FIB-4 can identify hepatitis B-related fibrosis with a moderate sensitivity and accuracy.

Serum transferrin as a liver fibrosis biomarker in patients with chronic hepatitis B

Background/Aims

Transferrin and alpha-1 antitrypsin are reportedly associated with liver fibrosis. We evaluated the usefulness of serum transferrin and alpha-1 antitrypsin as new liver fibrosis markers in patients with chronic hepatitis B.

Methods

The study included 293 patients with chronic hepatitis B who underwent a liver biopsy between October 2005 and June 2009, and who had no history of hepatocellular carcinoma. Serum markers and liver fibrosis stages were compared.

Results

Univariate analysis revealed that age (P<0.001), serum platelet count (P<0.001), and serum alkaline phosphatase level (P=0.003) differed significantly between the patients with and without liver cirrhosis. Serum transferrin levels were significantly lower in advanced fibrosis than in mild fibrosis in both univariate analysis (P=0.002) and multivariate analysis (P=0.009). In addition, the serum transferrin level was significantly lower in cirrhotic patients than in noncirrhotic patients (P=0.020). However, the serum level of alpha-1 antitrypsin was not significantly associated with liver cirrhosis in patients with chronic hepatitis B.

Conclusions

Serum transferrin could be promising serum marker for predicting advanced liver fibrosis in patients with chronic hepatitis B.

The diagnostic value of the FIB-4 index for staging hepatitis B-related fibrosis: a meta-analysis

Background

Liver fibrosis stage is an important factor in determining prognosis and need for treatment in patients infected with hepatitis B virus (HBV). Liver biopsies are typically used to assess liver fibrosis; however, noninvasive alternatives such as the FIB-4 index have also been developed.

Aims

To quantify the accuracy of the FIB-4 index in the diagnosis of HBV related fibrosis and cirrhosis.

Methods

A meta-analysis of studies comparing the diagnostic accuracy of the FIB-4 index vs. liver biopsy in HBV-infected patients was performed using studies retrieved from the following databases: PubMed, Ovid, EMBASE, the Cochrane Library, the Chinese National Knowledge Infrastructure and the Chinese Biology Medicine disc. A hierarchical summary receiver operating curves model and bivariate model were used to produce summary receiver operating characteristic curves and pooled estimates of sensitivity and specificity. The heterogeneity was explored with meta-regression analysis. Publication bias was detected using Egger’s test and the trim and fill method.

Results

12 studies (N = 1,908) and 10 studies (N = 2,105) were included in the meta-analysis for significant fibrosis and cirrhosis, respectively. For significant fibrosis, the area under the hierarchical summary receiver operating curve (AUHSROC) was 0.78 (95% CI = 0.74–0.81). The recommended cutoff value was between 1.45 and 1.62, and the AUHSROC, summary sensitivity and specificity were 0.78 (95% CI = 0.74–0.81), 0.65 (95% CI = 0.56–0.73) and 0.77 (95% CI = 0.7–0.83), respectively. For cirrhosis, the AUHSROC was 0.89 (95% CI = 0.85–0.91). The recommended cutoff value was between 2.9 and 3.6, and the AUHSROC, summary sensitivity and specificity were 0.96 (95% CI = 0.92–1.00), 0.42 (95% CI = 0.36–0.48) and 0.96 (95% CI = 0.95–0.97), respectively. No publication bias was detected.

Conclusions

The FIB-4 index is valuable for detecting significant fibrosis and cirrhosis in HBV-infected patients, but has suboptimal accuracy in excluding fibrosis and cirrhosis.