The role of humoral innate immunity in hepatitis C virus infection

Association between Immunologic Markers and Cirrhosis in Individuals from a Prospective Chronic Hepatitis C Cohort

Background: Chronic hepatitis C virus (HCV) infection can affect immune response and inflammatory pathways, leading to severe liver diseases such as cirrhosis and hepatocellular carcinoma (HCC). Methods: In a prospective cohort of chronically HCV-infected individuals, we sampled 68 individuals who developed cirrhosis, 91 controls who did not develop cirrhosis, and 94 individuals who developed HCC. Unconditional odds ratios (ORs) from polytomous logistic regression models and canonical discriminant analyses (CDAs) were used to compare categorical (C) baseline plasma levels for 102 markers in individuals who developed cirrhosis vs. controls and those who developed HCC vs. cirrhosis. Leave-one-out cross validation was used to produce receiver operating characteristic curves to assess predictive ability of markers. Lastly, biological pathways were assessed in association with cirrhotic development compared to controls. Results: After multivariable adjustment, DEFA-1 (OR: C2v.C1 = 7.73; p < 0.0001), ITGAM (OR: C2v.C1 = 4.03; p = 0.0002), SCF (OR: C4v.C1 = 0.19; p-trend = 0.0001), and CCL11 (OR: C4v.C1 = 0.31; p-trend= 0.002) were all associated with development of cirrhosis compared to controls; these markers, together with clinical/demographics variables, improved prediction of cirrhosis from 55.7% (in clinical/demographic-only model) to 74.9% accuracy. A twelve-marker model based on CDA results further increased prediction of cirrhosis to 88.0%. While six biological pathways were found to be associated with cirrhosis, cell adhesion was the only pathway associated with cirrhosis after Bonferroni correction. In contrast to cirrhosis, DEFA-1 and ITGAM levels were inversely associated with HCC risk. Conclusions: Pending validation, these findings highlight the important role of immunological markers in predicting HCV-related cirrhosis even 11 years post-enrollment.

The Multiple Faces of Nitric Oxide in Chronic Granulomatous Disease: A Comprehensive Update

Nitric oxide (NO), a signaling molecule, regulates multiple biological functions, including a variety of physiological and pathological processes. In this regard, NO participates in cutaneous inflammations, modulation of mitochondrial functions, vascular diseases, COVID-19, neurologic diseases, and obesity. It also mediates changes in the skeletal muscle function. Chronic granulomatous disease (CGD) is a primary immunodeficiency disorder characterized by the malfunction of phagocytes caused by mutations in some of the genes encoding subunits of the superoxide-generating phagocyte NADPH (NOX). The literature consulted shows that there is a relationship between the production of NO and the NADPH oxidase system, which regulates the persistence of NO in the medium. Nevertheless, the underlying mechanisms of the effects of NO on CGD remain unknown. In this paper, we briefly review the regulatory role of NO in CGD and its potential underlying mechanisms.

Profiling the HCV immune response in patients with chronic liver diseases and hepatocellular carcinoma by peptide microarray analysis

BACKGROUND

Chronic infection with hepatitis C virus (HCV) is among the major causes of hepatic fibrosis, cirrhosis, as well as hepatocellular carcinoma (HCC), and it is associated with a significant risk of developing lymphoproliferative disorders. The rate of clinical disease progression is variable depending on multiple host and viral factors, including immune response.

METHODS

To perform a comprehensive epitope mapping of anti-HCV antibodies in patients suffering from HCV-related liver or lymphoproliferative diseases, we analyzed clinical samples on a peptide microarray platform made of 5952 overlapping 15-mer synthetic peptides derived from the whole HCV proteome. We evaluated the antibody profile of 71 HCV-positive patients diagnosed with HCC, mixed cryoglobulinemia (MC), and HCV chronic infection. Antibody reactivity against virus peptides was detected in all HCV-positive patients. Importantly, the signal amplitude varied significantly within and between diverse patient groups.

RESULTS

Antibody reactivity against C peptides were found generally low in HCV chronically infected asymptomatic subjects and increasingly high in HCC and MC patients. Moreover, we found a statistically significant higher IgG response in HCC and MC patients against specific domains of HCV C, E2, NS3, NS4A, NS4B, NS5A, and p7 compared to HCV-positive subjects.

CONCLUSION

In conclusion, our data suggest that immune response against specific HCV protein domains may represent useful biomarkers of disease progression among HCV-positive patients and suggest that peptide microarrays are good tools for the screening of immunotherapy targets in preclinical HCV research.

Direct acting antiviral therapy rescues neutrophil dysfunction and reduces hemolysis in hepatitis C infection

Chronic hepatitis C virus infection is characterized by multiple extra-hepatic manifestations. Innate immune dysfunction and hemolysis are symptoms which might be associated with each other. We investigated the impact of direct acting antivirals on neutrophil function and its connection to hemolysis. In this prospective study, 85 patients with or without cirrhosis and 21 healthy controls were included. Patients' blood samples were taken at baseline, at the end of therapy and at follow-up 12 weeks after end of therapy. Neutrophil phagocytosis, oxidative burst, and hemolysis parameters were studied. Multivariate analysis was performed to decipher the relationship between hemolysis and neutrophil function. Ex vivo cross-incubation experiments with neutrophils and serum fractions were done. Impaired neutrophil phagocytosis and mild hemolysis were observed in patients with and without cirrhosis. A proteome approach revealed different expression of hemolysis-related serum proteins in patients and controls. Direct acting antiviral therapy restored neutrophil function irrespective of severity of liver disease, achievement of sustained virologic response or type of drug and reduced hemolysis. Treatment with ribavirin delayed the improvement of neutrophil function. Statistical analysis revealed associations of haptoglobin with neutrophil phagocytic capacity. Neutrophil dysfunction could be transferred to healthy cells by incubation with patients' serum fractions (>30 kDa) ex vivo. Neutrophil dysfunction and hemolysis represent extrahepatic manifestations of chronic hepatitis C virus infection and simultaneously improve during direct acting antiviral therapy independently of therapy-related liver function recovery. Therefore, large-scale treatment would not only drive viral eradication but also improve patients' immune system and may reduce susceptibility to infections.

Hepatitis C virus alternative reading frame protein (ARFP): Production, features, and pathogenesis

Earlier observation suggests that hepatitis C virus (HCV) is a single-stranded RNA virus which encodes at least 10 viral proteins. F protein is a novel protein which has been discovered recently. These studies suggest three mechanisms for the production of this protein concerning ribosomal frameshift at codon 10, initial translation at codons 26 and 85 or 87. In this study, the association between protein F and chronicity of hepatocellular carcinoma (HCC) has been reviewed. Evidence suggests that humoral immune system can recognize this protein and produce antibodies against it. By detecting antibodies in infected people, investigators found that F protein might have a role in HCV infection causing chronic cirrhosis and HCC as higher prevalence was found in patients with mentioned complications. The increment of CD4+, CD25+, and FoxP3+ T cells, along with CD8+ T cells with low expression of granzyme B, also leads to weaker responses of the immune system which helps the infection to become chronic. Moreover, it contributes to the survival of the virus in the body through affecting the production of interferon. F protein also might play roles in the disease development, resulting in HCC. The existence of F protein affects cellular pathways through upregulating p53, c-myc, cyclin D1, and phosphorylating Rb. This review will summarize these effects on immune system and related mechanisms in cellular pathways.

Expression of human ficolin-2 in hepatocytes confers resistance to infection by diverse hepatotropic viruses

The liver-expressed pattern recognition receptors mannose-binding lectin (MBL), ficolin-2 and ficolin-3 contribute to the innate immune response by activating complement. Binding of soluble ficolin-2 to viral pathogens can directly neutralize virus entry. We observed that the human hepatoma cell line HuH7.5, which is routinely used for the study of hepatotropic viruses, is deficient in expression of MBL, ficolin-2 and ficolin-3. We generated a cell line that expressed and secreted ficolin-2. This cell line (HuH7.5 [FCN2]) was more resistant to infection with hepatitis C virus (HCV), ebolavirus and vesicular stomatitis virus, but surprisingly was more susceptible to infection with rabies virus. Cell-to-cell spread of HCV was also inhibited in ficolin-2 expressing cells. This illustrates that ficolin-2 expression in hepatocytes contributes to innate resistance to virus infection, but some viruses might utilize ficolin-2 to facilitate entry.

Association of C-type lectin 18 levels with extrahepatic manifestations in chronic HCV infection

Mixed cryobulinemia (MC) is the most common chronic hepatitis C virus (HCV)-associated extrahepatic manifestation. C-type lectin 18 (CLEC18) is a novel secretory lectin that is abundantly expressed in hepatocytes and peripheral blood cells (PBCs). We investigated the associations between CLEC18 expression during HCV infection and the presence of extrahepatic manifestations. A total of 41 rheumatic patients with HCV infection (including 28 patients with MC syndrome), 45 rheumatic patients without infection, and 14 healthy subjects were enrolled. The CLEC18 levels in PBCs and serum were determined by using flow cytometry and enzyme-linked immunosorbent assay, respectively. Significantly higher CLEC18 levels were observed in patients with HCV infection (P < 0.001) and were positively correlated with HCV viral loads (γ = 0.56, P < 0.05). Among patients with HCV infection, significantly increased CLEC18 levels were observed in patients with MC syndrome, particularly in those with type II MC (P < 0.05). CLEC18 levels were associated with cryoglobulin and C4 levels (P < 0.05). CLEC18 was significantly associated with HCV infection, particularly in those with HCV-associated MC. CLEC18 levels were also positively correlated with MC disease activity, suggesting its involvement in MC pathogenesis. CLEC18 may be a novel indicator of HCV infection and a potential therapeutic target in rheumatic patients.

Immunization with a synthetic consensus hepatitis C virus E2 glycoprotein ectodomain elicits virus-neutralizing antibodies

Global eradication of hepatitis C virus (HCV) infection will require an efficacious vaccine capable of eliciting protective immunity against genetically diverse HCV strains. Natural spontaneous resolution of HCV infection is associated with production of broadly-neutralizing antibodies targeting the HCV glycoproteins E1 and E2. As such, production of cross-neutralizing antibodies is an important endpoint for experimental vaccine trials. Varying success generating cross-neutralizing antibodies has been achieved with immunogens derived from naturally-occurring HCV strains. In this study the challenge of minimising the genetic diversity between the vaccine strain and circulating HCV isolates was addressed. Two novel synthetic E2 glycoprotein immunogens (NotC1 and NotC2) were derived from consensus nucleotide sequences deduced from samples of circulating genotype 1 HCV strains. These two synthetic sequences differed in their relative positions in the overall genotype 1a/1b phylogeny. Expression of these constructs in Drosophila melanogaster S2 cells resulted in high yields of correctly-folded, monomeric E2 protein, which were recognised by broadly neutralizing monoclonal antibodies. Immunization of guinea pigs with either of these consensus immunogens, or a comparable protein representing a circulating genotype 1a strain resulted in high titres of cross-reactive anti-E2 antibodies. All immunogens generated antibodies capable of neutralizing the H77 strain, but NotC1 elicited antibodies that more potently neutralized virus entry. These vaccine-induced antibodies neutralized some viruses representing genotype 1, but not strains representing genotype 2 or genotype 3. Thus, while this approach to vaccine design resulted in correctly folded, immunogenic protein, cross-neutralizing epitopes were not preferentially targeted by the host immune response generated by this immunogen. Greater immunofocussing of vaccines to common epitopes is necessary to successfully elicit broadly neutralizing antibodies.

Clinical value of hepatitis C virus core antigen levels in monitoring acute hepatitis C spontaneous clearance or treatment-induced clearance

BACKGROUND AND AIM

To observe the clinical value of hepatitis C virus (HCV) core antigen (HCcAg) levels in monitoring acute HCV infection in patients with spontaneous clearance (SC) or clearance induced by antiviral therapy.

METHODS

Patients with iatrogenic HCV infection (n = 104) were enrolled at the Shengjing Hospital, China Medical University, between 5 February 2013 and 3 April 2013. All cases were diagnosed with acute HCV infection, enrolled within 90 days of infection, and followed for 12 to 16 weeks. Blood was collected every month. HCV RNA and HCcAg levels were detected. From week 16, patients without SC were treated with pegylated-interferon and the HCV RNA and HCcAg levels were observed monthly. Follow-up was 7.5 (5.0 to 10.4) months. The Spearman correlation analysis was performed to determine the correlation between HCV RNA and HCcAg. Logistic regression analysis was used to determine the association of baseline HCV RNA and HCcAg levels with SC.

RESULTS

Ten patients (9.62%) showed SC, with a negative conversion time of 57 (14 to 143) days. During follow-up, HCV RNA and HCcAg expression levels were positively correlated for each patient (except on the sixth month), but the levels of HCV RNA and HCcAg were not associated with HCV infection SC.

CONCLUSIONS

HCcAg levels could be of value for monitoring the course early HCV infection, but could not predict SC of HCV infection.

Hepatitis C virus: Morphogenesis, infection and therapy

Hepatitis C virus (HCV) is a major cause of liver diseases including liver cirrhosis and hepatocellular carcinoma. Approximately 3% of the world population is infected with HCV. Thus, HCV infection is considered a public healthy challenge. It is worth mentioning, that the HCV prevalence is dependent on the countries with infection rates around 20% in high endemic countries. The review summarizes recent data on HCV molecular biology, the physiopathology of infection (immune-mediated liver damage, liver fibrosis and lipid metabolism), virus diagnostic and treatment. In addition, currently available in vitro, ex vivo and animal models to study the virus life cycle, virus pathogenesis and therapy are described. Understanding of both host and viral factors may in the future lead to creation of new approaches in generation of an efficient therapeutic vaccine.

Apolipoprotein(a) inhibits hepatitis C virus entry through interaction with infectious particles

The development of different cell culture models has greatly contributed to increased understanding of the hepatitis C virus (HCV) life cycle. However, it is still challenging to grow HCV clinical isolates in cell culture. If overcome, this would open new perspectives to study HCV biology, including drug-resistant variants emerging with new antiviral therapies. In this study we hypothesized that this hurdle could be due to the presence of inhibitory factors in patient serum. Combining polyethylene glycol precipitation, iodixanol gradient, and size-exclusion chromatography, we obtained from HCV-seronegative sera a purified fraction enriched in inhibitory factors. Mass spectrometric analysis identified apolipoprotein(a) (apo[a]) as a potential inhibitor of HCV entry. Apo(a) consists of 10 kringle IV domains (KIVs), one kringle V domain, and an inactive protease domain. The 10 KIVs are present in a single copy with the exception of KIV type 2 (KIV₂ ), which is encoded in a variable number of tandemly repeated copies, giving rise to numerous apo(a) size isoforms. In addition, apo(a) covalently links to the apolipoprotein B component of a low-density lipoprotein through a disulfide bridge to form lipoprotein(a). Using a recombinant virus derived from the JFH1 strain, we confirmed that plasma-derived and recombinant lipoprotein(a) as well as purified recombinant apo(a) variants were able to specifically inhibit HCV by interacting with infectious particles. Our results also suggest that small isoforms are less inhibitory than the large ones. Finally, we observed that the lipoprotein moiety of HCV lipoviroparticles was essential for inhibition, whereas functional lysine-binding sites in KIV₇ , KIV₈ , and KIV₁₀ were not required.

CONCLUSIONS

Our results identify apo(a) as an additional component of the lipid metabolism modulating HCV infection. (Hepatology 2017;65:1851-1864).

MBL2 Genetic Variants in HCV Infection Susceptibility, Spontaneous Viral Clearance and Pegylated Interferon Plus Ribavirin Treatment Response

Hepatitis C is disease that damages the liver, and it is caused by the hepatitis C virus (HCV). The pathology became chronic in about 80% of the cases due to virus persistence in the host organism. The standard of care consists of pegylated interferon plus ribavirin; however, the treatment response is very variable and different host/viral factors may concur in the disease outcome. The mannose-binding protein C (MBL) is a component of the innate immune system, able to recognize HCV and consecutively activating the immune response. MBL is encoded by MBL2 gene, and polymorphisms, two in the promoter region (H/L and X/Y) and three in exon 1 (at codon 52, 54 and 57), have been described as functionally influencing protein expression. In this work, 203 Italian HCV patients and 61 healthy controls were enrolled and genotyped for the five MBL2 polymorphisms mentioned above to investigate their role in HCV infection susceptibility, spontaneous viral clearance and treatment response. MBL2 polymorphisms were not associated with HCV infection susceptibility and with spontaneous viral clearance, while MBL2 O allele, O/O genotype, HYO haplotype and DP combined genotype (all correlated with low or deficient MBL expression) were associated with sustained virological response. Moreover, a meta-analysis to assess the role of MBL2 polymorphisms in HCV infection susceptibility was also performed: YA haplotype could be associated with protection towards HCV infection.

Mannose-binding lectin in chronic hepatitis C in children

OBJECTIVE

To investigate effect of mannose-binding lectin (MBL) genetic polymorphisms and phenotype in chronic hepatitis C and its impact on response to antiviral therapy in children.

METHODS

Fifty four children with chronic hepatitis C, aged 2.5-18 years were enrolled. Forty-five children were treated with interferon-α (IFN-α) alone (n = 2) or IFN-α and ribavirin (n = 43). Twenty-one children who responded to antiviral therapy were defined as sustained responders to therapy (IFN-SR). Before therapy, MBL genotypes and serum MBL levels (by ELISA) were determined. MBL genotype distribution and levels were correlated to disease characteristics and response to therapy.

RESULTS

Children with chronic hepatitis C who did not respond to antiviral therapy (IFN-NR) presented more frequently MBL2 polymorphisms, although this did not reach significance (p = 0.08). MBL levels were significantly lower in children classified as IFN-NR when compared to children defined as IFN-SR (1.623 ng/ml vs. 3.699 ng/ml), (p = 0.04). Serum activity levels of ALT and AST were higher in children with A/O MBL genotype when compared to group with A/A genotype (p < 0.05).

CONCLUSIONS

Our findings suggest negative effect of MBL deficiency (defined by genotype and phenotype) on progression of chronic hepatitis C in children and response to antiviral therapy.

Chimeric antigen receptor (CAR)-engineered T cells redirected against hepatitis C virus (HCV) E2 glycoprotein

OBJECTIVE

The recent availability of novel antiviral drugs has raised new hope for a more effective treatment of hepatitis C virus (HCV) infection and its severe sequelae. However, in the case of non-responding or relapsing patients, alternative strategies are needed. To this end we have used chimeric antigen receptors (CARs), a very promising approach recently used in several clinical trials to redirect primary human T cells against different tumours. In particular, we designed the first CARs against HCV targeting the HCV/E2 glycoprotein (HCV/E2).

DESIGN

Anti-HCV/E2 CARs were composed of single-chain variable fragments (scFvs) obtained from a broadly cross-reactive and cross-neutralising human monoclonal antibody (mAb), e137, fused to the intracellular signalling motif of the costimulatory CD28 molecule and the CD3ζ domain. Activity of CAR-grafted T cells was evaluated in vitro against HCV/E2-transfected cells as well as hepatocytes infected with cell culture-derived HCV (HCVcc).

RESULTS

In this proof-of-concept study, retrovirus-transduced human T cells expressing anti-HCV/E2 CARs were endowed with specific antigen recognition accompanied by degranulation and secretion of proinflammatory and antiviral cytokines, such as interferon γ, interleukin 2 and tumour necrosis factor α. Moreover, CAR-grafted T cells were capable of lysing target cells of both hepatic and non-hepatic origin expressing on their surface the HCV/E2 glycoproteins of the most clinically relevant genotypes, including 1a, 1b, 2a, 3a, 4 and 5. Finally, and more importantly, they were capable of lysing HCVcc-infected hepatocytes.

CONCLUSIONS

Clearance of HCV-infected cells is a major therapeutic goal in chronic HCV infection, and adoptive transfer of anti-HCV/E2 CARs-grafted T cells represents a promising new therapeutic tool.

Innate Immunity and BK Virus: Prospective Strategies

Recent information demonstrated that BK virus reactivation is a dominant complication after kidney transplantation, which occurs because of immunosuppression. BK virus reactivation is the main reason of transplanted kidney losing. Immune response against BK virus is the major inhibitor of the virus reactivation. Therefore, improving our knowledge regarding the main parameters that fight against BK viruses can shed light on to direct new treatment strategies to suppress BK infection. Innate immunity consists of numerous cell systems and also soluble molecules, which not only suppress virus replication, but also activate adaptive immunity to eradicate the infection. Additionally, it appears that immune responses against reactivated BK virus are the main reasons for induction of BK virus-associated nephropathy (BKAN). Thus, improving our knowledge regarding the parameters and detailed mechanisms of innate immunity and also the status of innate immunity of the patients with BK virus reactivation and its complications can introduce new prospective strategies to either prevent or as therapy of the complication. Therefore, this review was aimed to collate the most recent data regarding the roles played by innate immunity against BK virus and also the status of innate immunity in the patients with reactivation BK virus and BKAN.

HCV-related central and peripheral nervous system demyelinating disorders

Chronic infection with hepatitis C virus (HCV) is associated with a large spectrum of extrahepatic manifestations (EHMs), mostly immunologic/rheumatologic in nature owing to B-cell proliferation and clonal expansion. Neurological complications are thought to be immune-mediated or secondary to invasion of neural tissues by HCV, as postulated in transverse myelitis and encephalopathic forms. Primarily axonal neuropathies, including sensorimotor polyneuropathy, large or small fiber sensory neuropathy, motor polyneuropathy, mononeuritis, mononeuritis multiplex, or overlapping syndrome, represent the most common neurological complications of chronic HCV infection. In addition, a number of peripheral demyelinating disorders are encountered, such as chronic inflammatory demyelinating polyneuropathy, the Lewis-Sumner syndrome, and cryoglobulin-associated polyneuropathy with demyelinating features. The spectrum of demyelinating forms also includes rare cases of iatrogenic central and peripheral nervous system disorders, occurring during treatment with pegylated interferon. Herein, we review HCV-related demyelinating conditions, and disclose the novel observation on the significantly increased frequency of chronic demyelinating neuropathy with anti-myelin-associated glycoprotein antibodies in a cohort of 59 consecutive patients recruited at our institution. We also report a second case of neuromyelitis optica with serum IgG autoantibody against the water channel aquaporin-4. The prompt recognition of these atypical and underestimated complications of HCV infection is of crucial importance in deciding which treatment option a patient should be offered.

Immune and non-immune responses to hepatitis C virus infection

The host innate and adaptive immune systems are involved in nearly every step of hepatitis C virus (HCV) infection. In patients, the outcome is determined by a series of complex host-virus interactions, whether it is a natural infection or results from clinical intervention. Strong and persistent CD8⁺ and CD4⁺ T-cell responses are critical in HCV clearance, as well as cytokine-induced factors that can directly inhibit virus replication. Newly available direct-acting antivirals (DAAs) are very effective in viral clearance in patients. DAA treatment may further result in the down-regulation of programmed death-1, leading to rapid restoration of HCV-specific CD8⁺ T cell functions. In this review, we focus on recent studies that address the host responses critical for viral clearance and disease resolution. Additional discussion is devoted to the prophylactic vaccine development as well as to current efforts aimed at understanding the host innate responses against HCV infection. Current theories on how the ubiquitin system and interferon-stimulated genes may affect HCV replication are also discussed.

Expression and Purification of HCV Core and Core-E1E2 Proteins in Different Bacterial Strains

BACKGROUND

Hepatitis C virus (HCV) is a main public health problem causing chronic liver infection and subsequently liver cirrhosis and lethal hepatocellular carcinoma (HCC). Vaccination based on HCV capsid proteins has attracted a special interest for prevention of viral infections. The core protein is a basic and evolutionary most conserved protein, which regulates the cellular processes related to viral replication and pathogenesis. The envelope E1 and E2 proteins involve in generation of the infectious particles, viral entry by binding to a host cell receptor, and modulation of the immune responses.

OBJECTIVES

In current study, the efficient generation of recombinant core and core-E1E2 proteins was developed in bacterial expression systems.

MATERIALS AND METHODS

The expression of HCV core and core-E1E2 proteins was performed using prokaryotic pET-28a and pQE-30 expression systems in BL21/ Rosetta, and M15 strains, respectively. The recombinant proteins were purified using affinity chromatography under native conditions and also reverse staining method. Finally, the levels of recombinant proteins were assessed by BCA kit and spectrophotometer.

RESULTS

The data showed a clear band of ~573 bp for HCV core and ~2238 bp for core-E1E2 genes in agarose gel. Moreover, a ~21 kDa band of core protein and a ~83 kDa band of core-E1E2 protein were revealed in SDS-PAGE. The affinity chromatography could not purify the core and core-E1E2 proteins completely, because of low affinity to Ni-NTA bead in comparison with reverse staining method.

CONCLUSIONS

This study is the first report for purification of HCV core and core-E1E2 proteins using the reverse staining procedure with no need of any chromatography columns. The BL21 strain was more potent than Rosetta strain for HCV core protein in pET 28a expression system. Furthermore, M15 strain was suitable for expression of coreE1E2 in pQE-30 bacterial system.

MBL-associated serine proteases (MASPs) and infectious diseases

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MASP-1 and MASP-2 are central players of the lectin pathway of complement.

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MASP1 and MASP2 gene polymorphisms regulate protein serum levels and activity.

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MASP deficiencies are associated with increased infection susceptibility.

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MASP polymorphisms and serum levels are associated with disease progression.

The lectin pathway of the complement system has a pivotal role in the defense against infectious organisms. After binding of mannan-binding lectin (MBL), ficolins or collectin 11 to carbohydrates or acetylated residues on pathogen surfaces, dimers of MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2) activate a proteolytic cascade, which culminates in the formation of the membrane attack complex and pathogen lysis. Alternative splicing of the pre-mRNA encoding MASP-1 results in two other products, MASP-3 and MAp44, which regulate activation of the cascade. A similar mechanism allows the gene encoding MASP-2 to produce the truncated MAp19 protein. Polymorphisms in MASP1 and MASP2 genes are associated with protein serum levels and functional activity. Since the first report of a MASP deficiency in 2003, deficiencies in lectin pathway proteins have been associated with recurrent infections and several polymorphisms were associated with the susceptibility or protection to infectious diseases. In this review, we summarize the findings on the role of MASP polymorphisms and serum levels in bacterial, viral and protozoan infectious diseases.

Human lectins and their roles in viral infections

Innate recognition of virus proteins is an important component of the immune response to viral pathogens. A component of this immune recognition is the family of lectins; pattern recognition receptors (PRRs) that recognise viral pathogen-associated molecular patterns (PAMPs) including viral glycoproteins. In this review we discuss the contribution of soluble and membrane-associated PRRs to immunity against virus pathogens, and the potential role of these molecules in facilitating virus replication. These processes are illustrated with examples of viruses including human immunodeficiency virus (HIV), hepatitis C virus (HCV) and Ebola virus (EBOV). We focus on the structure, function and genetics of the well-characterised C-type lectin mannose-binding lectin, the ficolins, and the membrane-bound CD209 proteins expressed on dendritic cells. The potential for lectin-based antiviral therapies is also discussed.

Complement C5a acts as molecular adjuvant in fish by enhancing antibody response to soluble antigen

C5a, the most potent anaphylatoxin generated during complement activation, has important pro-inflammatory actions and has also been shown to enhance antigen-specific antibody response in mammals, thereby acting as a molecular adjuvant. In rainbow trout, C5a has been shown to have a chemoattractant ability and its receptor has also been found on potential APCs. In this study, we tested the possible role of trout C5a as a molecular adjuvant. We demonstrated the presence of native C5a in trout serum using the antibody generated by recombinant trout C5a, and then we generated recombinant infectious hematopoietic necrosis virus glycoprotein (G), and a G-C5a fusion protein to test the adjuvant activity of trout C5a. Recombinant G-C5a displayed a potent chemoattractant activity in contrast to G alone, indicating that the C5a portion of the fusion protein was functional. Thereafter, G-C5a, partially emulsified in a small quantity of IFA, was injected into one group of trout, while the other group of trout was inoculated with the same dose of recombinant G. At four to sixteen weeks post-injection, the serum IgM antibody levels of the fish injected with recombinant G-C5a were obviously higher than those injected with G protein alone. Thus, these results suggest, for the first time, that C5a acts as molecular adjuvant in teleost fish by enhancing antibody response to a soluble antigen.

Combinatorial library-based profiling of the antibody response against hepatitis C virus in humans

The antibody response plays a crucial role against hepatitis C virus (HCV) infection, and our understanding of this intricate progress in vivo is far from complete. We previously reported a novel and robust technique based on a large combinatorial viral antigen library displayed on the surface of the yeast Saccharomyces cerevisiae, allowing comprehensive profiling of polyclonal antibody responses in vivo in both qualitative and quantitative terms. Here, we report the generation and application of a combinatorial library of HCV strain JFH1 envelope glycoprotein to profile the antibody response in four HCV chronically infected individuals. By systematic analysis of the location and frequency of antigenic fragments along the JFH1 envelope glycoprotein, we showed that the major binding antibody response was targeted to E2 (80.9-99.8 %), whilst that against E1 was relatively small (0.3-19.0 %). A total of five major antigenic domains (D1-D5) were identified: one was within E1 and an additional four within E2, despite substantial variability among the different individuals. However, serum absorption with the yeast clones containing the antigenic domain D1 resulted in more reduction in neutralizing antibody activity against pseudotyped HCV than those in E2, suggesting that E1 contains additional neutralizing epitopes. Our results have provided additional insights into the HCV-specific antibody response in humans and should assist in a better understanding of protective antibody immunity and in guiding the development of effective vaccines and therapeutics against HCV infection.

Pushing to a cure by harnessing innate immunity against hepatitis C virus

Hepatitis C virus (HCV) causes 350,000 deaths and infects at least 3million people worldwide every year. Currently no vaccine has been developed. Direct-acting antiviral (DAA) drugs with high efficacy for suppressing HCV infection have recently been introduced into the clinic. While DAAs initially required combination therapy with type-1 interferon (IFN) administration for full efficacy and to avoid viral resistance to treatment, new DAA combinations show promise as an IFN-free regimen. However, IFN-free DAA therapy is in its infancy, still to be proven and today is cost-prohibitive for the patient. A major goal in HCV therapy to remove or replace IFN with DAAs or an alternative therapeutic to render virologic response with continued virus sensitivity to DAAs, thus facilitating a cure for infection. Recent advances in our understanding of innate immune responses to HCV have identified new therapeutic targets to combat HCV infection. We discuss how the targeting of innate immune response factors can be harnessed with DAAs to produce new generations of DAA-based HCV therapeutics. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication."

Serum complements C3 and C4 in chronic HCV infection and their correlation with response to pegylated interferon and ribavirin treatment

BACKGROUND AND STUDY AIMS

To search for an immunological parameter that may correlate with the response to interferon (IFN) treatment is very crucial. The objective of this study was to correlate the levels of C3 and C4 complement components with the response to IFN treatment in patients with chronic hepatitis C virus (HCV) infection.

PATIENTS AND METHODS

This study was conducted on 100 patients and control subjects classified into three groups. Group (I) consisted of 50 patients with chronic hepatitis C who were receiving IFN treatment and showed various responses; group (II) included 25 patients with chronic hepatitis C naive to IFN treatment; and group (III) included 25 healthy subjects matched for age and sex who served as controls. Measurement of the level of complement C3 and C4 was done by a quantitative turbidimetric test. Measurement of complement levels in group (I) was done at the end of treatment at the 48th week.

RESULTS

Serum levels of C3 and C4 were found to be significantly reduced in all patients with chronic HCV infection in both groups (I and II) compared to the healthy control group (III) (p<0.05). Moreover, chronic HCV patients treated with IFN and ribavirin had significantly lower levels of C3 and C4 compared with patients naive to IFN and ribavirin treatment. At the end of treatment, both C3 and C4 had significantly increased in responders to IFN when compared to non-responders (p=0.025 and 0.05, respectively). There was a significant negative correlation between C3 and C4 levels and the concentration of serum alanine aminotransferase (ALT) measured simultaneously.

CONCLUSION

Higher C3 and C4 serum concentrations were found to be positively correlated to the end-of-treatment response in patients with chronic HCV infection treated with IFN and ribavirin.

Low Levels of 25-Hydroxy Vitamin D are Independently Associated with the Risk of Bacterial Infection in Cirrhotic Patients

OBJECTIVES:

Low levels of vitamin D are associated with a higher mortality in cirrhotic patients, but the role of this deficiency is still unknown. The purpose of this study was to assess the levels of vitamin D in cirrhotic patients with and without bacterial infection.

METHODS:

25-hydroxy (25-OH) vitamin D was assessed by immunoassay in 88 patients hospitalized in our hepatology unit.

RESULTS:

The causes of cirrhosis were mainly alcohol (70%), hepatitis C (10%), or both (9%). Infections (n=38) mainly included bacteriemia (21%), urinary tract infections (24%), and spontaneous bacterial peritonitis (29%). A severe deficiency in vitamin D (<10 ng/ml) was observed in 56.8% of patients. Infections were more frequent in patients with a severe deficiency compared with the others (54 vs. 29%, P=0.02). A severe deficiency in vitamin D was a predictive factor of infection (odds ratio=5.44 (1.35–21.97), P=0.017) independently of the Child–Pugh score (odds ratio=2.09 (1.47–2.97) P=0.00004) and the C-reactive protein level (odds ratio=1.03 (1.002–1.052), P=0.03) in a logistic regression also including the alanine amino transferase (not significant). By a Cox regression analysis, only the presence of an infection was significantly associated with mortality (relative risk=3.24 (1.20–8.76), P=0.02) in a model also associating the Child–Pugh score (not significant) and the presence of a severe deficiency in vitamin D (not significant).

CONCLUSIONS:

Low levels of 25-OH vitamin D were independently associated with bacterial infections in cirrhotic patients. The impact of 25-OH vitamin D supplementation on the infection rate and death of cirrhotic patients should be assessed in randomized trials.

Maternal-fetal transmission of hepatitis C infection: what is so special about babies?

Children with hepatitis C virus infection often differ from adults regarding the rate of viral clearance, duration of infection, and the progression to cirrhosis. In the pediatric population, vertical transmission of hepatitis C virus infection from mother to infant is the most common route of infection. In the present review, we explore the factors that may influence the natural history of hepatitis C virus infection in children who acquire the infection through maternal-fetal transmission. There is particular focus on how viral diversity and the infant immune system may affect viral transmission. An enhanced understanding of maternal-fetal transmission of hepatitis C virus infection has the potential to affect effective drug and vaccine development for both children and adults.

Mannan binding lectin-associated serine protease 1 is induced by hepatitis C virus infection and activates human hepatic stellate cells

Mannan binding lectin (MBL)-associated serine protease type 1 (MASP-1) has a central role in the lectin pathway of complement activation and is required for the formation of C3 convertase. The activity of MASP-1 in the peripheral blood has been identified previously as a highly significant predictor of the severity of liver fibrosis in hepatitis C virus (HCV) infection, but not in liver disease of other aetiologies. In this study we tested the hypotheses that expression of MASP-1 may promote disease progression in HCV disease by direct activation of hepatic stellate cells (HSCs) and may additionally be up-regulated by HCV. In order to do so, we utilized a model for the maintenance of primary human HSC in the quiescent state by culture on basement membrane substrate prior to stimulation. In comparison to controls, recombinant MASP-1 stimulated quiescent human HSCs to differentiate to the activated state as assessed by both morphology and up-regulation of HSC activation markers α-smooth muscle actin and tissue inhibitor of metalloproteinase 1. Further, the expression of MASP-1 was up-regulated significantly by HCV infection in hepatocyte cell lines. These observations suggest a new role for MASP-1 and provide a possible mechanistic link between high levels of MASP-1 and the severity of disease in HCV infection. Taken together with previous clinical observations, our new findings suggest that the balance of MASP-1 activity may be proinflammatory and act to accelerate fibrosis progression in HCV liver disease.

Complement activation correlates with liver necrosis and fibrosis in chronic hepatitis C

Chronic hepatitis C viral infection modulates complement. The aim of this study was to determine whether complement analysis predicts liver inflammation and fibrosis in patients with chronic hepatitis C. 50 chronic hepatitis C patients who underwent a liver biopsy were compared to 50 healthy controls and 35 patients with various liver diseases. Total plasma complement activity (CH50) in plasma was diminished in hepatitis C patients suggesting complement activation. This decrease correlated with increased necrosis (r = -0.24, p < 0.05), and patients with levels below the normal range had a higher METAVIR activity score reflecting enhanced inflammation. SC5b-9, a marker of complement activation, correlated with inflammation (r = 0.40, p < 0.05), activity (r = 0.42, p < 0.05), and fibrosis scores (r = 0.49, p < 0.05). Finally, the prevalence of C1q auto-antibodies was higher in hepatitis C patients, and their presence was associated with increased inflammation and seemed to affect fibrosis. We conclude that complement-induced liver inflammation contributes to fibrosis in patients with chronic hepatitis C.

Seroprevalence of human enterovirus 71 and coxsackievirus A16 in Guangdong, China, in pre- and post-2010 HFMD epidemic period

BACKGROUND

Human Enterovirus 71 and Coxsackie A16 have caused many outbreaks in the last decade in mainland China, resulting in thousands of fatal cases. Seroepidemiology which provides important information to document population immunity is rare in China.

METHODOLOGY/PRINCIPAL FINDINGS

A cross sectional study of Enterovirus 71 (EV71) and Coxsackie A16 (CA16) seroprevalence was carried out in Guangdong, China, pre- and post- the 2010 hand, foot and mouth disease (HFMD) epidemic period. The levels of EV71 and CA16 specific antibodies were evaluated by a microneutralization test and the geometric mean titer (GMT) was calculated and compared. Our results indicated frequent infection by EV71 and CA16 in Guangdong before the 2010 epidemic. Only EV71 neutralizing antibody but not CA16 seroprevalence was significantly increased after the 2010 HFMD epidemic. Children less than 3 years old especially those aged 2 years showed the lowest positive rates for EV71 and CA16 NA before epidemic and the most significantly increased EV71 seroprevalence after epidemic. CA16 GMT values declined after the 2010 epidemic.

CONCLUSIONS

These results indicate EV71 was the major pathogen of HFMD in Guangdong during the 2010 epidemic. The infection occurs largely in children less than 3 years, who should have first priority to receive an EV71 vaccine.

Plasma proteome analysis reveals overlapping, yet distinct mechanisms of immune activation in chronic HCV and HIV infections

BACKGROUND

HIV infection contributes to accelerated rates of progression of liver fibrosis during hepatitis C virus (HCV) infection, and HCV liver disease contributes to mortality during HIV infection. Although mechanisms underlying these interactions are not well known, soluble and cellular markers of immune activation associate with disease progression during both infections.

METHODS

We identified proteins varying in expression across the plasma proteomes of subjects with untreated HIV infection, untreated HCV infection with low aspartate transaminase/platelet ratio index, untreated HCV infection with high aspartate transaminase/platelet ratio index, HIV-HCV coinfection, and controls. We examined correlations between dysregulated proteins and markers of immune activation to uncover biomarkers specific to disease states.

RESULTS

We observed the anticipated higher frequencies of HLA-DRCD38CD4 and CD8 T cells, higher serum soluble CD14 levels, and higher serum interleukin-6 levels for HCV- and HIV-infected groups compared with controls. Plasma proteome analysis identified 2297 peptides mapping to 227 proteins, and quantitative analysis of peptide intensity identified significant changes in 85 proteins across the 5 groups. Abundance for 7 of these proteins was validated by enzyme-linked immunosorbent assay. Forty-three of these proteins correlated with markers of immune activation, including at least 2 proteins that may directly drive T-cell activation. As a functional validation, we tested the enzymatic pathway product (lysophosphatidic acid, LPA) of one such protein, ecotonucleotide pyrophosphatase/phosphodiesterase-2, for ability to activate T cells in vitro. LPA activated T cells to express CD38 and HLA-DR.

CONCLUSIONS

These data indicate that elevated levels of ecotonucleotide pyrophosphatase/phosphodiesterase-2 and LPA during advanced HCV disease may play a role in exacerbating immune activation during HCV-HIV coinfection.

Seroepidemiology of human enterovirus71 and coxsackievirusA16 among children in Guangdong province, China

Background

Hand, foot and mouth disease (HFMD) is a common pediatric illness. Mainly induced by the Enterovirus 71 and Coxsackievirus A 16 infections, the frequently occurred HFMD outbreaks have become a serious public health problem in Southeast Asia. Currently,only a few studies have investigated the human immunity to HFMD in China. In this study, we conducted a cohort study in Guangdong province, China.

Methods

Stored serum samples from children less than 10 years old were analyzed. The levels of EV71 and CA16 specific antibodies before, during and shortly after the 2008 large outbreak of HFMD were evaluated by the microneutralization test. The geometric mean titer (GMT) was calculated and compared. Statistical significance was taken as P < 0.05.

Results

The seroprevalence data showed a continuous circulation of EV71 and CA16 in Guangdong province China in 2007–2009. The low positive rate in 2009 correlated well with the unprecedented outbreak of HFMD in 2010. Age related increase of seroprevalence was identified in 1–3 years old children for EV71 and in 1–5 years old children for CA16 in Guangdong province. High GMT of EV71 and CA16 antibody titers were also found for these age groups.

Conclusions

All of the above findings indicated common infections for these age groups. And they should clearly be at the top of the priority in periodical seroprevalence survey and future vaccination campaign.

Complementary serum proteomic analysis of autoimmune hepatitis in mice and patients

Background

Autoimmune hepatitis (AIH) is a chronic liver disease caused by inflammation of the liver. The etiology of AIH remains elusive, and there are no reliable serum biomarkers.

Methods

In order to identify candidate biomarkers, 2-DE analysis of serum proteins was performed using a mouse model of AIH induced by treatment with concanavalin A (ConA). To enrich samples for low abundance molecules a commercial albumin removal reagent was used. In an independent analysis, candidate biomarkers were identified in AIH patient’s serum by a targeted iTRAQ (isobaric tags for relative and absolute quantification) identification. Candidates were validated in independent cohorts of ConA treated mice and AIH patients by ELISA (enzyme-linked immuno sorbent assay).

Results

Nine proteins were differentially expressed in AIH mice treated with con-A. Two of these, the third component of complement (C3) and alpha-2-macroglobulin (A2M) were also up-regulated in AIH patient’s sera by a targeted iTRAQ identification. In separate validation studies, serum C3 and A2M levels were increased in mice with ConA treatment after 20-40 h and in 34 AIH patients in a subgroup analysis, females with AIH aged 20–50 years old displayed the largest increases in serum A2M level. Biological network analysis implements the complement cascade and protease inhibitors in the pathogenesis of AIH.

Conclusion

The serum proteins C3 and A2M are increased both in a mouse model and in patients with AIH by both 2-DE and iTRAQ methods. This integrated serum proteomics investigation should be applicable for translational researchers to study other medical conditions.