Molecular signatures of hepatitis C virus (HCV)-induced type II mixed cryoglobulinemia (MCII)

A multicentric and nationwide predictive study role of T cell sub-population in the prevalence and prognosis of cryoglobulinemia among genotype 4 chronic hepatitis C patients

The infection caused by the hepatitis C virus (HCV) is a significant global health concern. The prevailing genotype of HCV in Egypt is 4a, commonly referred to as GT-4a. A significant proportion exceeding 50% of patients infected with HCV experience extrahepatic manifestations (EHMs), encompassing a diverse range of clinical presentations. These manifestations, including essential mixed cryoglobulinemia (MC), can serve as initial and solitary indicators of the disease. The complete understanding of the pathogenesis of EHM remains unclear, with autoimmune phenomena being recognized as the primary causative factor. In this study, we examined the predictive significance of T-cell subpopulations in relation to the occurrence and prognosis of cryoglobulinemia in HCV patients. A total of 450 CHC genotype four treatment naïve patients were enrolled in this analytic cross-sectional study after thorough clinical, laboratory, and radiological examinations. All patients underwent laboratory investigations, including testing for cryoglobulin antibodies and measurements of CD4 and CD8 levels; two groups were described according to their test results: Group 1 consists of patients who have tested positive for cryoglobulin antibodies and Group 2 consists of patients who have tested negative for cryoglobulin antibodies. The exclusion criteria encompassed individuals with HIV infection or chronic HBV infection. Additionally, pelvi-abdominal ultrasonography was performed. Our study included 450 treatment naïve CHC patients (59% male, mean age 50.8 years). The patients were categorized according to their cryoglobulin antibodys test results into two groups: group A, CHC patients with cryoglobulin antibodies (Abs) negative (364 patients), and group B, CHC patients with cryoglobulin Ab positive (86 patients). Group B demonstrated a higher average age, elevated international normalized ratio, more prolonged duration of HCV infection, lower albumin, higher alanine aminotransferase, higher aspartate aminotransferase, higher bilirubin, lower CD8, lower CD4, and lower CD4:CD8 ratio. In contrast, 27 out of 86 (31.40%) patients in group B had symptoms; 85.8% had purpura and arthralgia, 74.3% had paresthesias, 86.7% had weakness, and 12.2% had non-Hodgkin's lymphoma. The levels of CD4 and CD8 were found to be decreased in chronic HCV patients with MC. T-cell subpopulation serves as a reliable indicator for assessing the prevalence and prognosis of MC in individuals with genotype 4 chronic hepatitis C. However, additional research is needed to further understand the development and spread of various emerging infectious diseases. Nevertheless, it is noteworthy that a critical threshold may exist beyond which EHM reaches a point of no return.

Selective decrease in complement C2 hemolytic activity is a sensitive marker for cryoglobulinemia and active disease in hepatitis C patients

BACKGROUND

Some HCV patients present low/non-detected C2 hemolytic activity (C2h) without apparent consumption of other Complement components (selective low/non-detected C2h).

AIM

Characterization of the immunologic/clinical basis of this phenomenon.

METHODS

C2h, HCV-viral load, cryoglobulinemia and Complement components were determined in 726 HCV patients, with sequential C2h determination in 189 patients.

RESULTS

C2h was non-detected in 15.9%, low in 16.9% and normal in 67.2% subjects and showed temporal oscillation in 30.7% of patients. Samples with selective non-detected C2h presented lower C3/C4 than those with normal C2h, but still within the normal C3/C4 range. Selective non-detected C2h was associated with higher aspartate aminotransferase (AST) (p<0.001), alanine transferase (ALT) (p = 0.03) and APRI (Aspartate aminotransferase-to-Platelet Ratio Index) (p<0.001), lower serum albumin (p = 0.01) and platelet count (p = 0.012), more individuals at pre-treatment stage, with detectable HCV-RNA p<0.001), cryoglobulinemia (p<0.001) and with HCV genotype 3 (p = 0.003). Elevated ALT, HCV genotype 3, active disease and viral load were independent predictors of low/non-detected C2h. In vitro exposure of normal serum to exogenous HCV cryoglobulins caused dose-dependent decrease in C2h.

CONCLUSIONS

Selective C2h decrease is a sensitive marker of Complement activation in HCV patients and is associated with cryoglobulinemia, active disease, elevated ALT, higher viral load, and HCV genotype 3.

Hepatitis C virus-associated non-Hodgkin lymphomas: the endless history

Hepatitis C virus (HCV) is a global population problem due to its high prevalence worldwide. In the prognosis of patients with HCV not only hepatic but increasingly frequent of extrahepatic HCV manifestations, such as mixed cryoglobulinemia (MC) and non-Hodgkin's lymphoma (NHL), are important. The role of the HCV virus in the pathogenesis of lymphoproliferative diseases is confirmed by a large number of epidemiological studies, as well as by the effectiveness of antiviral therapy in patients with non-Hodgkin's lymphoma (NHL). The purpose of the review was to provide an overview of epidemiological and biological data explaining the role of HCV in the development of NHL. The review also discusses HCV-associated NHL treatment by the traditional antiviral therapy (interferon and ribavirin) and by the new direct antiviral agents.

Heterogeneity and coexistence of oncogenic mechanisms involved in HCV-associated B-cell lymphomas

The association of HCV-infection with B-lymphomas is supported by the regression of most indolent/low-grade lymphomas following anti-viral therapy. Studies on direct and indirect oncogenic mechanisms have elucidated the pathogenesis of HCV-associated B-lymphoma subtypes. These include B-lymphocyte proliferation and sustained clonal expansion by HCV-envelope protein stimulation of B-cell receptors, and prolonged HCV-infected B-cell growth by overexpression of an anti-apoptotic BCL-2 oncogene caused by the increased frequency of t(14;18) chromosomal translocations in follicular lymphomas. HCV has been implicated in lymphomagenesis by a "hit-and-run" mechanism, inducing enhanced mutation rate in immunoglobulins and anti-oncogenes favoring immune escape, due to permanent genetic damage by double-strand DNA-breaks. More direct oncogenic mechanisms have been identified in cytokines and chemokines in relation to NS3 and Core expression, particularly in diffuse large B-cell lymphoma. By reviewing genetic alterations and disrupted signaling pathways, we intend to highlight how mutually non-contrasting mechanisms cooperate with environmental factors toward progression of HCV-lymphoma.

Towards a universal influenza vaccine: different approaches for one goal

Influenza virus infection is an ongoing health and economic burden causing epidemics with pandemic potential, affecting 5–30% of the global population annually, and is responsible for millions of hospitalizations and thousands of deaths each year. Annual influenza vaccination is the primary prophylactic countermeasure aimed at limiting influenza burden. However, the effectiveness of current influenza vaccines are limited because they only confer protective immunity when there is antigenic similarity between the selected vaccine strains and circulating influenza isolates. The major targets of the antibody response against influenza virus are the surface glycoprotein antigens hemagglutinin (HA) and neuraminidase (NA). Hypervariability of the amino acid sequences encoding HA and NA is largely responsible for epidemic and pandemic influenza outbreaks, and are the consequence of antigenic drift or shift, respectively. For this reason, if an antigenic mismatch exists between the current vaccine and circulating influenza isolates, vaccinated people may not be afforded complete protection. There is currently an unmet need to develop an effective “broadly-reactive” or “universal” influenza vaccine capable of conferring protection against both seasonal and newly emerging pre-pandemic strains. A number of novel influenza vaccine approaches are currently under evaluation. One approach is the elicitation of an immune response against the “Achille’s heel” of the virus, i.e. conserved viral proteins or protein regions shared amongst seasonal and pre-pandemic strains. Alternatively, other approaches aim toward eliciting a broader immune response capable of conferring protection against the diversity of currently circulating seasonal influenza strains.

In this review, the most promising under-development universal vaccine approaches are discussed with an emphasis on those targeting the HA glycoprotein. In particular, their strengths and potential short-comings are discussed. Ultimately, the upcoming clinical evaluation of these universal vaccine approaches will be fundamental to determine their effectiveness against preventing influenza virus infection and/or reducing transmission and disease severity.

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.

Virus-induced preferential antibody gene-usage and its importance in humoral autoimmunity

It is known that even the adaptive components of the immune system are based on genetic traits common to all individuals, and that diversity is shaped by the lifelong contacts with different non-self antigens, including those found on infectious pathogens. Besides the individual differences, some of these common traits may be more prone to react against a given antigen, and this may be exploited by the infectious pathogens. Indeed, viral infections can deregulate immune response by subverting antibody (Ab) gene usage, leading to the overexpression of specific Ab subfamilies. This overexpression often results in a protective antiviral response but, in some cases, also correlates with a higher likelihood of developing humoral autoimmune disorders. These aspects of virus-induced autoimmunity have never been thoroughly reviewed, and this is the main purpose of this review. An accurate examination of virus specific Ab subfamilies elicited during infections may help further characterize the complex interplay between viruses and the humoral immune response, and be useful in the design of future monoclonal antibody (mAb)-based anti-infective prophylactic and therapeutic strategies.

Cloning of the first human anti-JCPyV/VP1 neutralizing monoclonal antibody: epitope definition and implications in risk stratification of patients under natalizumab therapy

JC virus (JCPyV) has gained novel clinical importance as cause of progressive multifocal leukoencephalopathy (PML), a rare demyelinating disease recently associated to immunomodulatory drugs, such as natalizumab used in multiple sclerosis (MS) cases. Little is known about the mechanisms leading to PML, and this makes the need of PML risk stratification among natalizumab-treated patients very compelling. Clinical and laboratory-based risk-stratification markers have been proposed, one of these is represented by the JCPyV-seropositive status, which includes about 54% of MS patients. We recently proposed to investigate the possible protective role of neutralizing humoral immune response in preventing JCPyV reactivation. In this proof-of-concept study, by cloning the first human monoclonal antibody (GRE1) directed against a neutralizing epitope on JCPyV/VP1, we optimized a robust anti-JCPyV neutralization assay. This allowed us to evaluate the neutralizing activity in JCPyV-positive sera from MS patients, demonstrating the lack of correlation between the level of anti-JCPyV antibody and anti-JCPyV neutralizing activity. Relevant consequences may derive from future clinical studies induced by these findings; indeed the study of the serum anti-JCPyV neutralizing activity could allow not only a better risk stratification of the patients during natalizumab treatment, but also a better understanding of the pathophysiological mechanisms leading to PML, highlighting the contribution of peripheral versus central nervous system JCPyV reactivation. Noteworthy, the availability of GRE1 could allow the design of novel immunoprophylactic strategies during the immunomodulatory treatment.

B-cell receptors expressed by lymphomas of hepatitis C virus (HCV)-infected patients rarely react with the viral proteins. Blood. 2014;123:1512-1515. [PMID: 24449209 DOI: 10.1182/blood-2013-10-532895]

Chronic hepatitis C virus (HCV) infection has been implicated in the induction and maintenance of B-cell lymphomas. The strongest evidence for this derives from clinical observations of tumor regressions upon antiviral treatments. Here we used multiple methods to test the hypothesis that the expansion of HCV-specific B cells gives rise to lymphomas. We obtained lymphoma tissues from HCV-infected lymphoma patients, including some that later regressed upon antiviral treatments. We expressed the lymphoma B-cell receptors as soluble immunoglobulin Gs and membrane IgMs, and analyzed their reactivity with HCV proteins and with HCV virions. We confirmed previous reports that HCV-associated lymphomas use a restricted immunoglobulin variable region gene repertoire. However, we found no evidence for their binding to the HCV antigens. We conclude that most lymphomas of HCV-infected patients do not arise from B cells aimed at eliminating the virus.

Structural and antigenic definition of hepatitis C virus E2 glycoprotein epitopes targeted by monoclonal antibodies. Clin Dev Immunol. 2013;2013:450963. [PMID: 23935648 PMCID: PMC3722892 DOI: 10.1155/2013/450963]

Hepatitis C virus (HCV) is the major cause of chronic liver disease as well as the major indication for liver transplantation worldwide. Current standard of care is not completely effective, not administrable in grafted patients, and burdened by several side effects. This incomplete effectiveness is mainly due to the high propensity of the virus to continually mutate under the selective pressure exerted by the host immune response as well as currently administered antiviral drugs. The E2 envelope surface glycoprotein of HCV (HCV/E2) is the main target of the host humoral immune response and for this reason one of the major variable viral proteins. However, broadly cross-neutralizing monoclonal antibodies (mAbs) directed against HCV/E2 represent a promising tool for the study of virus-host interplay as well as for the development of effective prophylactic and therapeutic approaches. In the last few years many anti-HCV/E2 mAbs have been evaluated in preclinical and clinical trials as possible candidate antivirals, particularly for administration in pre- and post-transplant settings. In this review we summarize the antigenic and structural characteristics of HCV/E2 determined through the use of anti-HCV/E2 mAbs, which, given the absence of a crystal structure of this glycoprotein, represent currently the best tool available.

Hepatitis C virus (HCV)-related cryoglobulinemia: cryoglobulin type and anti-HCV profile. Clin Vaccine Immunol. 2013;20:698-703. [PMID: 23467778 DOI: 10.1128/cvi.00720-12]

Cryoglobulin characteristics in chronic hepatitis C (CHC) might be of importance for knowing more about the pathogenesis and treatment of the disease. We aimed to investigate the relationship between cryoglobulin types and their specificity against hepatitis C virus (HCV) antigenic epitopes in CHC patients. We analyzed samples from 43 patients with HCV-associated cryoglobulinemia, of whom 4 had concomitant lymphoma. Cryoglobulins were measured, purified, typed by immunofixation electrophoresis, and tested for IgG and IgM anti-HCV antibodies by immunoblot analysis and an enzyme-linked immunosorbent assay (ELISA). Clinical and other laboratory data were recorded. The median cryocrit level of the tested samples was 6%. Type I cryoglobulins were detected in 9.3% (4/43) of the cryoprecipitates, and type II cryoglobulins were detected in 48.8% (21/43) of the cryoprecipitates. IgM monoclonal protein, mainly IgM(κ), was found in 92% (23/25) of type I and II cryoprecipitates. Type III cryoglobulins were identified in 41.9% (18/43) of the patients and were associated with high blood serum IgG levels. In 81.3% (13/16) of type II and 92.3% (12/13) of type III cryoglobulins, there was IgG reactivity against the viral core region. Ninety-two percent and 32% of IgG anti-HCV core-positive cryoprecipitates had additional specificities against the NS3 and NS4 regions, respectively. Also, IgM anti-HCV antibodies were detected in 31% of the cryoprecipitates. In conclusion, all types of cryoglobulins were found in patients with HCV-associated cryoglobulinemia, with type II being the most frequently identified. Type III cryoglobulins were common and were associated with high serum IgG levels. HCV-related cryoglobulins demonstrated IgM, and particularly IgG, anti-HCV specificities, mainly against the core and NS3 epitopes.