Polymerized albumin binding to serum in various liver diseases: its significance and relation to hepatitis B virus infection

Sparse logistic regression revealed the associations between HBV PreS quasispecies and hepatocellular carcinoma

BACKGROUND

Chronic infection with hepatitis B virus (HBV) has been proved highly associated with the development of hepatocellular carcinoma (HCC).

AIMS

The purpose of the study is to investigate the association between HBV preS region quasispecies and HCC development, as well as to develop HCC diagnosis model using HBV preS region quasispecies.

METHODS

A total of 104 chronic hepatitis B (CHB) patients and 117 HBV-related HCC patients were enrolled. HBV preS region was sequenced using next generation sequencing (NGS) and the nucleotide entropy was calculated for quasispecies evaluation. Sparse logistic regression (SLR) was used to predict HCC development and prediction performances were evaluated using receiver operating characteristic curves.

RESULTS

Entropy of HBV preS1, preS2 regions and several nucleotide points showed significant divergence between CHB and HCC patients. Using SLR, the classification of HCC/CHB groups achieved a mean area under the receiver operating characteristic curve (AUC) of 0.883 in the training data and 0.795 in the test data. The prediction model was also validated by a completely independent dataset from Hong Kong. The 10 selected nucleotide positions showed significantly different entropy between CHB and HCC patients. The HBV quasispecies also classified three clinical parameters, including HBeAg, HBVDNA, and Alkaline phosphatase (ALP) with the AUC value greater than 0.6 in the test data.

CONCLUSIONS

Using NGS and SLR, the association between HBV preS region nucleotide entropy and HCC development was validated in our study and this could promote the understanding of HCC progression mechanism.

Vitamin D attenuates human gingival fibroblast inflammatory cytokine production following advanced glycation end product interaction with receptors for AGE

BACKGROUND AND OBJECTIVES

Vitamin D [1,25(OH)₂ D₃ or 1,25D3] is critical in musculoskeletal health, inflammation, immune response, and glucose metabolism. Patients with vitamin D deficiency may be at higher risk of diabetes and periodontitis. Diabetic patients exhibit exacerbated inflammation and more periodontal destruction. Advanced glycation end products (AGEs), formed during diabetic hyperglycemia, activate inflammatory pathways in periodontitis. Human gingival fibroblasts (HGFs) express receptors for AGEs (RAGEs) and can contribute to inflammation.

OBJECTIVES

Determine whether glycated human serum albumin (G-HSA) augments HGF IL-6 and IL-8 production, and whether treatment with 1,25D3 attenuates cytokine production following stimulation with G-HSA + IL-1β and/or IL-17.

MATERIAL AND METHODS

HGFs were incubated ±G-HSA or normal human serum albumin (HSA), ±IL-1β and/or IL-17, ±1,25D3. Cytokines were measured by ELISA. Neutralizing anti-RAGE was used to assess AGE-RAGE interaction. Endotoxin was measured using the ToxinSensor™ System. Data were expressed as mean ± standard deviation and analyzed using a one-way analysis of variance (ANOVA) and Scheffe's F procedure for post hoc comparisons.

RESULTS

G-HSA or IL-1β, but not HSA, significantly stimulated IL-6 and IL-8 production. G-HSA or HSA when combined with IL-1β or IL-1β + IL-17 synergistically stimulated IL-6 and IL-8. Neutralizing anti-RAGE inhibited IL-6 and IL-8 produced by cells stimulated with IL-1β + G-HSA but not (+HSA). Synergism caused by HSA did not appear to be mediated by endotoxin since its levels in G-HSA and HSA were not sufficient to stimulate fibroblasts. Vitamin D inhibited IL-6 and IL-8 production stimulated by G-HSA or HSA + IL-1β or IL-1β + IL-17.

CONCLUSIONS

Results suggest that the "perioprotective" effects of vitamin D are related to its ability to regulate inflammatory cytokine production by HGFs following AGE-RAGE interaction.

Significance of natural polymerized albumin and its receptor in hepatitis B infection of hepatocytes

Lack of information regarding the presence of native albumin polymer in serum and its structural similarity to the one produced by glutaraldehyde treatment casts doubt on the postulate that hepatitis B virus attachment to hepatocytes is mediated through polymerized albumin. We used a sandwich enzyme-linked immunosorbent assay with murine monoclonal antibodies raised against glutaraldehyde-polymerized albumin to detect native albumin polymer in human serum and its cross-reactivity with other albumin polymers. Presence of polymerized albumin receptor on the HepG2 cell was studied by radioreceptor assay. Purified hepatitis B virus and synthetic peptide analogous to part of pre-S2 sequence (120-145) were used to study polymerized albumin-dependent attachment of the virus to HepG2 cells. Antibodies raised against pre-S2 peptide were used to inhibit the pre-S2 and hepatitis B virus attachment to HepG2 cells. Glutaraldehyde-treated polymerized albumin was found to be immunologically cross-reactive with native albumin polymer. Its levels were found to be significantly raised in sera of patients with liver diseases. Polymerized albumin has specific saturable receptor on HepG2 cells with two classes of binding sites of different equilibrium dissociation constant (Kd1 = (16 +/- 9.6)pmol/L and Kd2 = (1,019 +/- 172)pmol/L. Albumin monomer was unable to compete for the polymerized albumin receptor sites on HepG2 cells. Anti-pre-S2 antibodies inhibit hepatitis B virus and pre-S2 binding to hepatocyte by 40% and 70%, respectively. Added extraneous polymerized albumin and the antibody against it did not interfere with virus attachment to HepG2 cells.