Background: Epidemiological studies indicate that a growing number of cirrhotic patients will develop hepatocellular carcinoma (HCC) in the next decade. Recent findings have demonstrated that Squamous cell carcinoma antigen 1 (SCCA1) and 2 (SCCA2) isoforms, now classified as serpinB3 and serpinB4, are over-expressed in HCC, but not in normal liver. As reported, high levels of circulating SCCA-IgM immunocomplexes in patients with cirrhosis are significantly associated with HCC development. Aim: To ascertain whether IgM-linked SCCA isoforms circulate in patients with chronic liver disease, compared to total SCCA-IgM levels. Methodology and Findings: 79 patients with chronic liver disease were studied, including 17 patients with chronic hepatitis, 36 patients with cirrhosis and 26 with HCC. 28 blood donors were used as control. Monoclonal antibodies against serpinB3 and serpinB4 were used as catcher antibodies to set up specific ELISA assays, while total SCCA-IgM immunocomplexes were detected by commercially available ELISA assay. Overall, the results revealed a better diagnostic sensitivity of total SCCA-IgM assay, compared to both serpinB3 and serpinB4 IgM-linked assays. SerpinB4-IgM median values obtained with SCC103 antibody were moderately higher in patients with cirrhosis than in those with HCC, median values: 0.168 (IQR 0.140–0.427) vs. 0.140 (IQR 0.140–0.278), (p = 0.177). A trend toward decreasing serpinB4-IgM/serpinB3-IgM median ratio was observed in patients with advanced liver disease, being 1.08 in patients with HCC, 1.10 in patients with cirrhosis and 1.40 in patients with chronic hepatitis (p = 0.079). Conclusions: IgM-linked SCCA isoforms in serum of patients with chronic liver diseases were quantified for the first time. Although the number of patients was limited, this preliminary study reveals that the relative balance of the two serpin isoforms is altered in HCC and it is characterized by a lower serpinB4-IgM/serpinB3-IgM ratio, determined by lower serpinB4 levels. Citation: Biasiolo A, Tono N, Ruvoletto M, Quarta S, Turato C, et al. (2012) IgM-Linked SerpinB3 and SerpinB4 in Sera of Patients with Chronic Liver Disease. PLoS ONE 7(7): e40658. doi:10.1371/journal.pone.0040658 Editor: Henrik Einwaechter, Klinikum rechts der Isar der TU München, Germany Received January 18, 2012; Accepted June 11, 2012; Published July 13, 2012 Copyright: 2012 Biasiolo et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work is supported in part by a grant from the National Ministry of Education, University and Research (FIRB Project Prot. RBLA03S4SP_005) and by a research grant from the Associazione Italiana per la Ricerca sul Cancro (AIRC). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding was received for this study. Competing Interests: The authors have read the journal’s policy and have the following conflicts of interest to declare: LB and GF are employees of Xeptagen S.p.A. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials. * E-mail: patrizia@unipd.it

The identification and surveillance of patients with liver dysfunctions and the discovering of new disease biomarkers are needed in the clinical practice. The aim of this study was to investigate on Survivin–immunoglobulin (Ig)M immune complex (IC) as a potential biomarker of chronic liver diseases.

Background and Aims: Using in vitro cell culture and in vivo xenograft mouse models, we have previously shown that the heparan sulfate-degrading endosulfatase SULF1 functions as a tumor suppressor in established hepatocellular carcinoma cell lines by abrogating receptor tyrosine kinase signaling. In contrast, whole genome gene expression analysis of resected human HCCs showed increased expression of SULF1 in 70% of primary HCCs; and SULF1 expression in primary HCCs has been associated with activation of the oncogenic Wnt/β-catenin pathway. Here we report for the first time the results of DEN-induced hepatocarcinogenesis in a hepatocyte-specific transgenic Sulf1 mouse model in which the Sulf1 gene is driven by the transthyretin promoter. The effect of Sulf1 transgenesis on Wnt/ β-catenin activation was assessed. Methods: Liver carcinogenesis was induced in wild-type or hepatocyte-specific Sulf1 transgenic mice by intraperitoneal injection of 15 mg/kg of the liver carcinogen diethylnitrosamine (DEN) at 14 days after birth. Mice were sacrificed at 8 months of age and the harvested livers were examined for weight, tumor size and number. Cell proliferation was assessed using the BrdU proliferation index and Wnt/ β-catenin activation was measured by assessment of β-catenin staining and cytoplasmic-nuclear translocation of β-catenin. Results: Consistent with the observation of increased SULF1 in primary human HCCs, Sulf1 transgenic mice showed increased liver tumorigenesis as demonstrated by tumor number, tumor volume, liver weight/body weight ratio, and BrdU proliferation index. To investigate the mechanism for this, we performed immunohistochemistry for β-catenin. Wnt-β-catenin signaling was increased in Sulf1 transgenic mice compared to wild-type mice, as assessed by both increased β-catenin immunostaining and increased cytoplasmic-nuclear translocation of β-catenin. Conclusions: In contrast to the tumor suppressor effects of SULF1 in established human cell lines, which are mediated by inhibition of the co-receptor function of heparan sulfate in receptor tyrosine kinase signaling, primary HCCs in an in vivo model of DEN-induced HCC in Sulf1 transgenic mice show increased liver tumorigenesis associated with activation ofWnt-β-catenin signaling. This suggests that the effect of Sulf1 in carcinogenesis is context-dependent, but appears to be mediated through oncogenic Wntβ-catenin signaling in the majority of HCCs.

BACKGROUND:Epidemiological studies indicate that a growing number of cirrhotic patients will develop hepatocellular carcinoma (HCC) in the next decade. Recent findings have demonstrated that Squamous cell carcinoma antigen 1 (SCCA1) and 2 (SCCA2) isoforms, now classified as serpinB3 and serpinB4, are over-expressed in HCC, but not in normal liver. As reported, high levels of circulating SCCA-IgM immunocomplexes in patients with cirrhosis are significantly associated with HCC development.AIM:To ascertain whether IgM-linked SCCA isoforms circulate in patients with chronic liver disease, compared to total SCCA-IgM levels.METHODOLOGY AND FINDINGS:79 patients with chronic liver disease were studied, including 17 patients with chronic hepatitis, 36 patients with cirrhosis and 26 with HCC. 28 blood donors were used as control. Monoclonal antibodies against serpinB3 and serpinB4 were used as catcher antibodies to set up specific ELISA assays, while total SCCA-IgM immunocomplexes were detected by commercially available ELISA assay. Overall, the results revealed a better diagnostic sensitivity of total SCCA-IgM assay, compared to both serpinB3 and serpinB4 IgM-linked assays. SerpinB4-IgM median values obtained with SCC103 antibody were moderately higher in patients with cirrhosis than in those with HCC, median values: 0.168 (IQR 0.140-0.427) vs. 0.140 (IQR 0.140-0.278), (p = 0.177). A trend toward decreasing serpinB4-IgM/serpinB3-IgM median ratio was observed in patients with advanced liver disease, being 1.08 in patients with HCC, 1.10 in patients with cirrhosis and 1.40 in patients with chronic hepatitis (p = 0.079).CONCLUSIONS:IgM-linked SCCA isoforms in serum of patients with chronic liver diseases were quantified for the first time. Although the number of patients was limited, this preliminary study reveals that the relative balance of the two serpin isoforms is altered in HCC and it is characterized by a lower serpinB4-IgM/serpinB3-IgM ratio, determined by lower serpinB4 levels.

Evidences of oseltamivir resistant influenza patients raised the need of novel neuraminidase inhibitors. In this study, five oseltamivir analogs PMC-31-PMC-36, synthesised according to the outcomes of a rational design analysis aimed to investigate the effects of substitution at the 5-amino and 4-amido groups of oseltamivir on its antiviral activity, were screened for their inhibition against neuraminidase N1 and N3. The enzymes used as models were from the avian influenza A H7N1 and H7N3 viruses. The neuraminidase inhibition assay was carried out by using recombinant species obtained from a baculovirus expression system and the fluorogenic substrate MUNANA. The assay was validated by using oseltamivir carboxylate as a reference inhibitor. Among the tested compounds, PMC-36 showed the highest inhibition on N1 with an IC(50) of 14.6±3.0nM (oseltamivir 25±4nM), while PMC-35 showed a significant inhibitory effect on N3 with an IC(50) of 0.1±0.03nM (oseltamivir 0.2±0.02nM). The analysis of the inhibitory properties of this panel of compounds allowed a preliminary assessment of a structure-activity relationship for the modification of the 4-amido and 5-amino groups of oseltamivir carboxylate. The substitution of the acetamido group in the oseltamivir structure with a 2-butenylamido moiety reduced the observed activity, while the introduction of a propenylamido group was well tolerated. Substitution of the free 5-amino group of oseltamivir carboxylate with an azide, decreased the activity against both N1 and N3. When these structural changes were both introduced, a dramatic reduction of activity was observed for both N1 and N3. The alkylation of the free 5-amino group in oseltamivir carboxylate introducing an isopropyl group seemed to increase the inhibitory effect for both N1 and N3 neuraminidases, displaying a more pronounced effect against N1.

POSTERSresults being statistically significant (P < 0.05).Higher sensitivity in lesion detection by hepatocyte-phase compared with arterial dominant phase was also clearly demonstrated in a diameter of HCC (lesions <10 mm: 72% vs. 46%; lesions 10-20 mm: 90% vs. 69%, lesions >20 mm: 96% vs. 87%, respectively).Conclusions: Hepatocyte-specific Gd-EOB-DTPA enhanced MRI has sufficient image quality to detect HCC lesions diagnosed by CT-HA and CT-AP.Hepatocyte-phase is especially useful for the detection for smaller lesions.

SERPINB3 has been found in chronic liver damage and hepatocellular carcinoma, but not in normal liver. By direct mRNA sequencing, a new SERPINB3 polymorphism (SCCA-PD) has been identified, presenting the substitution Gly351Ala in the reactive center loop of the protein. The prevalence of the SCCA-PD isoform has been found to be significantly higher in patients with cirrhosis than in patients with chronic liver disease and in normal subjects. The aim of this study was to investigate the biological and functional activity of SERPINB3 isoforms using in vitro models. HepG2 and Huh7 cells lines were transfected with plasmid vectors containing wild-type SERPINB3 or its polymorphic variant SCCA-PD and their expression at transcriptional and protein level was determined. To assess the functional activity, both recombinant proteins were produced and kinetic analysis was carried out using papain and cathepsin-L as target proteases. In addition, the inhibition of JNK kinase activity by SERPINB3 isoforms was assessed. The crystal structure of wild-type SERPINB3 at 2.7 Å resolution was used for preparation of refined 3D models of the two isoforms. The results showed that transcriptional activity and protein expression of the two isoforms were similar in both transfected cell lines. Both SERPINB3 preparations exerted a dose-dependent protease inhibitory activity, but the effect of SCCA-PD was higher than that of the wild-type isoform. This result was supported by 3D modelling, where increased hydrophobic profile of the SCCA-PD isoform, introduced by the G351A mutation, was detected. In addition, at high protein concentration, SCCA-PD revealed a 16% higher inhibitory effect on c-Jun phosphorylation by JNK1, compared with wild-type SERPINB3. In conclusion, the single amino acid substitution in the SERPINB3 reactive site loop improves the functional activity of SCCA-PD isoform. This different antiprotease activity might favor disease progression in patients carrying this polymorphism.

Many assays aimed to test the inhibitory effects of synthetic molecules, and naturally occurring products on the neuraminidase activity exploit the hydrolysis of 2′-O-(4-methylumbelliferyl)-N-acetylneuraminic acid (4-MUNANA). The amount of the released product, 4-methylumbelliferone (4-MU), is then measured fluorimetrically. The authors attempted an analysis of the inhibitory properties of 35 naturally occurring flavonoids on neuraminidase N3, where only 29 of them were sufficiently soluble in the assay medium. During the analysis, the authors noticed a strong quenching effect due to the test compounds on the fluorescence of 4-MU. The quenching constants for the flavonoids were determined according to the Stern-Volmer approach. The extent of fluorescence reduction due to quenching and the magnitude of the fluorescence reduction measured in the inhibition assays were comparable: for 11 of 29 compounds, the two values were found to be coincident within the experimental uncertainty. These data were statistically analyzed for correlation by calculating the pertinent Pearson correlation coefficient. Inhibition and quenching were found to be positively correlated (r = 0.71, p(uncorr) = 1.5 × 10−5), and the correlation was maintained for the whole set of tested compounds. Altogether, the collected data imply that all of the tested flavonoids could produce false-positive results in the neuraminidase inhibition assay using 4-MUNANA as a substrate.

A novel dendrimeric peptide ligand dubbed D-PAM-Φ was designed to achieve a high capacity for human IgG through the decoration of the D-PAM scaffold. The design criteria based on the introduction of small hydrophobic groups on the D-PAM structure were supported by the recently published solid-state structure of D-PAM complexed to the Fc fragment of a recombinant human IgG1 and by molecular dynamic simulations that provided information on the mode of binding of phenylacetyl-D-PAM (D-PAM-Φ). D-PAM-Φ was immobilised on an activated solid support and compared with the parent D-PAM affinity matrix. The newly obtained affinity sorbent was evaluated for its capacity to selectively capture polyclonal human IgG; the binding capacity was approximately 10 mg/ml, an almost 10-fold enhancement with respect to the D-PAM-functionalised matrices without the specificity of binding being reduced. The new ligand was also effective in the capturing of recombinant humanised IgG1 from a clarified cell culture supernatant. Under a typical laboratory-scale affinity chromatography assembly and preliminarily optimised binding conditions, the affinity purification of humanised IgG1 from culture supernatants rendered the desired product, with purity higher than 90%. The results suggest that the application of the computational approach on the structure of the D-PAM-Fc complex may be very valuable in the development of novel lead molecules for the downstream processing of human or humanised antibodies used in therapy.

Context: Development of inexpensive and safe enzymatic assays to screen for putative neuraminidase inhibitors. Objective: Validate the use of recombinant neuraminidase expressed in baculovirus located on the viral surface capsule to develop a neuraminidase inhibitor screening assay. Materials and methods: Recombinant baculovirus particles displaying neuraminidase N1 and N3 were used as enzyme sources. The assay set-up required the use of 2′-(4-methylumbelliferyl)-α-D-acetyl neuraminic acid as substrate and oseltamivir carboxylate as benchmark inhibitor. Results: The assay was set up in a standard 96-well plate. The within- and between-assay coefficients of variation were, on average, less than 10%. The 50% inhibitory concentration values of the inhibitor were in good agreement with those determined by independent kinetic experiments. Discussion and conclusions: The assay showed satisfactory within- and between-assay repeatability. The obtained results suggest that recombinant baculovirus expressing neuraminidase located on the virus membrane capsule can be used to set up affordable and reliable neuraminidase inhibitors screening assays.

Protein-protein conjugation is usually achieved by solution phase methods requiring concentrated protein solution and post-synthetic purification steps. In this report we describe a novel continuous-flow solid-phase approach enabling the assembly of protein complexes minimizing the amount of material needed and allowing the repeated use of the same solid phase. The method exploits an immunoaffinity matrix as solid support; the matrix reversibly binds the first of the complex components while the other components are sequentially introduced, thus allowing the complex to grow while immobilized. The tethering technique employed relies on the use of the very mild synthetic conditions and fast association rates allowed by the avidin-biotin system. At the end of the assembly, the immobilized complexes can be removed from the solid support and recovered by lowering the pH of the medium. Under the conditions used for the sequential complexation and recovery, the solid phase was not damaged or irreversibly modified and could be reused without loss of binding capacity. The method was specifically designed to prepare protein complexes to be used in immunometric methods of analysis, where the immunoreactivity of each component needs to be preserved. The approach was successfully exploited for the preparation of two different immunoaffinity reagents with immunoreactivity mimicking native squamous cell carcinoma antigen-immunoglobulin M (SCCA-IgM) and alphafetoprotein-immunoglobulin M (AFP-IgM) immune complexes, which were characterized by dedicated sandwich enzyme-linked immunosorbent assay (ELISA) and immunoblot. Besides the specific application described in the paper, the method is sufficiently general to be used for the preparation of a broad range of protein assemblies. Copyright (C) 2010 John Wiley & Sons, Ltd.