HBV and HCV chronic infection: autoimmune manifestations and lymphoproliferation. Autoimmun Rev. 2008;8:107-111. [PMID: 18700171 DOI: 10.1016/j.autrev.2008.07.012]

Potential role of HBV DNA-induced CD8high T cell apoptosis in patients with systemic lupus erythematosus and rheumatoid arthritis

Objective

To investigate the potential role of hepatitis B virus (HBV) DNA-induced CD8^high T cell apoptosis in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).

Methods

The activity and HBV seropositivity rates of patients with SLE and RA were determined. The proportions of T cell subgroups were detected by fluorescence-activated cell sorting. The apoptosis of T cell subgroups was detected after peripheral blood mononuclear cells were stimulated with HBV DNA.

Results

The HBV infection rate was higher in patients with RA than in patients with SLE. Current or previous HBV infection was more common among patients with inactive SLE than among those with active SLE. Conversely, previous or current HBV infection was more common among patients with active RA than among those with inactive RA. CD4⁻CD8^high T cell counts were higher among patients with active SLE than in those with inactive SLE. However, CD4⁻CD8^high T cell counts were lower in patients with active RA patients than in those with inactive RA. HBV DNA increased the apoptosis of CD4⁻CD8^high T cells.

Conclusion

HBV DNA-induced CD8^high T cell apoptosis appears to play different roles in SLE and RA.

The association between hepatitis B, hepatitis C and systemic sclerosis: a cross-sectional study

PURPOSE OF REVIEW

To investigate the association between systemic sclerosis (SSc) to chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) carriage. We utilized the database of Clalit Health Services, the largest healthcare organization in Israel and performed a cross-sectional study.

RECENT FINDINGS

The study included 2431 SSc patients and 12 710 age-and-sex matched controls, HBV was found in 38 SSc patients (1.56%) and 64 controls (0.5%). HCV was found in 30 SSc patients (1.23%) and 83 controls (0.65%). In multivariable logistic regression model, HBV was found to be associated with smoking, dialysis treatment and SSc [odds ratio (OR) 2.97, 95% confidence interval (CI) 1.92-4.53]. HCV was found to be associated with dialysis treatment and SSc (OR 1.73, 95% CI 1.1-2.66). A trend was found between both HBV and HCV toward low socioeconomic status. SSc patients with HBV had demonstrated higher rates of end-stage renal disease requiring dialysis treatment.

SUMMARY

In our study, HBV and HCV were found to be associated with SSc. Common immune mechanisms or therapeutic modalities may serve as mediators of this association.

Development and in vivo evaluation of baicalin-loaded W/O nanoemulsion for lymphatic absorption

Background: Lymphatic formations that effectively eradicate the virus in the lymphatic system will be therapeutically advantagous in hepatitis B virus (HBV) infection. Lipid-based formulation is often used to deliver drug via the lymphatic system. Baicalin nanoemulsion may be a promising drug delivery system for improved treatment of HBV infection. Objective: This study aimed to prepare, characterize, and evaluate a lipid-based nanoemulsion containing baicalin for lymphatic system absorption. Method: The presence of a nanoemulsion region was studied by pseudoternary phase diagrams. The physicochemical properties of a baicalin-loaded nanoemulsion were investigated. The oral bioavailability of the baicalin-loaded nanoemulsion was compared to that of a baicalin suspension. A chylomicron flow blocking model was used to examine the extent of lymphatic uptake. The lymph node distribution of baicalin was measured to investigate the lymphatic transport ability of the nanoemulsion compared to the suspension. Results: Compared to the baicalin suspension, the AUC_0-t and C_max values of the baicalin nanoemulsion were increased by 10.5-fold and 3.12-fold, respectively. Compared with the saline-treated rats that were orally administered the baicalin nanoemulsion, the AUC_0-t and C_max values of the nanoemulsion for the rats pretreated with cycloheximide were reduced from 23.076 ± 1.244 mg/L h to 9.236 ± 0.940 mg/L h and from 3.010 ± 0.119 mg/L to 1.567 ± 0.220 mg/L, respectively. In comparing baicalin in W/O nanoemulsion with suspension, the C_max value was found to be 11.5-fold higher in the lymph nodes of the rats treated with the nanoemulsion. Conclusion: The results indicated that a baicalin-loaded W/O nanoemulsion may be a promising drug delivery system for the treatment of chronic hepatitis B.

RELATIONSHIP BETWEEN UVEITIS, DIFFERENT TYPES OF VIRAL HEPATITIS, AND LIVER CIRRHOSIS: A 12-Year Nationwide Population-Based Cohort Study

PURPOSE

This study investigates whether patients with viral hepatitis and cirrhosis are at risk of uveitis in the years following hepatitis.

METHODS

We used data from Taiwan National Health Insurance system. The cases were patients newly diagnosed with viral hepatitis from 2000 to 2011. The end point of interest was a diagnosis of uveitis. A chi-square test was used for the difference of demographic characteristics between viral hepatitis and comparison. The risk of uveitis in hepatitis was stratified using Cox proportional hazard regression.

RESULTS

We selected 17,389 patients with viral hepatitis and 34,778 matched comparison. The risk of uveitis in hepatitis cohort was 1.30-fold (95% confidence interval = 1.01-1.69). Patients with hepatitis B virus and hepatitis C virus coinfection had the highest risk (hazard ratio = 2.88; 95% confidence interval = 1.07-7.78), and followed by only hepatitis C virus infection (hazard ratio = 1.75; 95% confidence interval = 1.10-2.79). Patients with cirrhosis had a higher risk in the multivariable model but did not attach statistic difference.

CONCLUSION

Patients with hepatitis B virus and hepatitis C virus coinfection had the highest risk of uveitis. In patients with hepatitis C virus and/or hepatitis B virus infection, the symptoms of uveitis should be alerted. Although these epidemiologic studies yielded informative results, the underlying mechanisms and the host's genetic factors remain to be investigated.

Presence of Rheumatoid Factor during Chronic HCV Infection Is Associated with Expansion of Mature Activated Memory B-Cells that Are Hypo-Responsive to B-Cell Receptor Stimulation and Persist during the Early Stage of IFN Free Therapy

Approximately half of those with chronic hepatitis C virus (HCV) infection have circulating rheumatoid factor (RF), and a portion of these individuals develop cryoglobulinemic vasculitis. B cell phenotype/function in relation to RF in serum has been unclear. We examined B cell subset distribution, activation state (CD86), cell cycle state (Ki67), and ex-vivo response to BCR, TLR9 and TLR7/8 stimulation, in chronic HCV-infected donors with or without RF, and uninfected donors. Mature-activated B-cells of HCV-infected donors had lower CD86 expression compared to uninfected donors, and in the presence of RF they also showed reduced CD86 expression in response to BCR and TLR9 stimulation. Additionally, mature activated memory B cells of HCV RF+ donors less commonly expressed Ki67+ than HCV RF- donors, and did not proliferate as well in response to BCR stimulation. Proportions of mature-activated B cells were enhanced, while naïve B-cells were lower in the peripheral blood of HCV-RF+ compared to RF- and uninfected donors. None of these parameters normalize by week 8 of IFN free direct acting antiviral (DAA) therapy in HCV RF+ donors, while in RF- donors, mature activated B cell proportions did normalize. These data indicate that while chronic HCV infection alone results in a lower state of activation in mature activated memory B cells, the presence of RF in serum is associated with a more pronounced state of unresponsiveness and an overrepresentation of these B cells in the blood. This phenotype persists at least during the early time window after removal of HCV from the host.

MDA5 Is Critical to Host Defense during Infection with Murine Coronavirus

Infection with the murine coronavirus mouse hepatitis virus (MHV) activates the pattern recognition receptors melanoma differentiation-associated gene 5 (MDA5) and Toll-like receptor 7 (TLR7) to induce transcription of type I interferon. Type I interferon is crucial for control of viral replication and spread in the natural host, but the specific contributions of MDA5 signaling to this pathway as well as to pathogenesis and subsequent immune responses are largely unknown. In this study, we use MHV infection of the liver as a model to demonstrate that MDA5 signaling is critically important for controlling MHV-induced pathology and regulation of the immune response. Mice deficient in MDA5 expression (MDA5(-/-) mice) experienced more severe disease following MHV infection, with reduced survival, increased spread of virus to additional sites of infection, and more extensive liver damage than did wild-type mice. Although type I interferon transcription decreased in MDA5(-/-) mice, the interferon-stimulated gene response remained intact. Cytokine production by innate and adaptive immune cells was largely intact in MDA5(-/-) mice, but perforin induction by natural killer cells and levels of interferon gamma, interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) in serum were elevated. These data suggest that MDA5 signaling reduces the severity of MHV-induced disease, at least in part by reducing the intensity of the proinflammatory cytokine response.

IMPORTANCE

Multicellular organisms employ a wide range of sensors to detect viruses and other pathogens. One such sensor, MDA5, detects viral RNA and triggers induction of type I interferons, chemical messengers that induce inflammation and help regulate the immune responses. In this study, we sought to determine the role of MDA5 during infection with mouse hepatitis virus, a murine coronavirus used to model viral hepatitis as well as other human diseases. We found that mice lacking the MDA5 sensor were more susceptible to infection than were mice with MDA5 and experienced decreased survival. Viral replication in the liver was similar in mice with and without MDA5, but liver damage was increased in MDA5(-/-) mice, suggesting that the immune response is causing the damage. Production of several proinflammatory cytokines was elevated in MDA5(-/-) mice, suggesting that MDA5 may be responsible for keeping pathological inflammatory responses in check.

Autoantibodies in Chinese patients with chronic hepatitis B: Prevalence and clinical associations

AIM: To investigate the prevalence of autoantibodies and their associations with clinical features in Chinese patients with chronic hepatitis B (CHB).

METHODS: A total of 325 Chinese patients with CHB were enrolled in this retrospective, hospital-based study. Patients with chronic hepatitis C (CHC), autoimmune hepatitis (AIH), or primary biliary cirrhosis (PBC) were included, with healthy donors acting as controls. A panel of autoantibodies that serologically define AIH and PBC was tested by indirect immunofluorescence assay and line immunoassay. The AIH-related autoantibody profile included homogeneous anti-nuclear antibodies (ANA-H), smooth-muscle antibodies, anti-liver kidney microsome type 1, anti-liver cytosolic antigen type 1, and anti-soluble liver antigen/liver pancreas; the PBC-related antibodies were characterized by ANA-nuclear dots/membranous rim-like, anti-mitochondrial antibodies-M2 (AMA-M2), anti-BPO (recombinant antigen targeted by AMA-M2), anti-Sp100, anti-promyelocytic leukemia protein (anti-PML), and anti-gp210. The dichotomization of clustering was used to unequivocally designate the AIH or PBC profiles for each case. Anti-Ro52 antibodies were also tested.

RESULTS: The prevalence of any autoantibody in CHB amounted to 58.2%, which was similar to the 66.2% prevalence in CHC, significantly higher than the 6.7% in the healthy controls (P < 0.001), and lower than the 100% found in AIH and PBC (P = 0.004 and P < 0.001, respectively). There were more anti-PML and anti-gp210 antibodies among the CHB patients than the CHC patients (11.1% vs 0%, P = 0.003; 12.6% vs 0%, P < 0.001, respectively). The prevalence and titer of AMA, anti-BPO, anti-PML, and anti-gp210 were higher in PBC than in those with CHB. Among the CHB patients, the prevalence of ANA, especially ANA-H, was significantly lower in patients with compensated and decompensated cirrhosis compared with patients without cirrhosis. Thirty-eight cases of hepatocellular carcinoma (HCC) in CHB showed a significant difference compared with non-HCC patients in the prevalence of anti-PML (0% vs 12.5%, P = 0.013). Dichotomization of the autoantibodies revealed that the PBC profile was more prevalent in patients with CHB than in those with CHC, and that it was strongly correlated with both compensated and decompensated cirrhosis. In contrast, the prevalence of the AIH profile was significantly higher in non-cirrhosis patients with CHB than in those with compensated cirrhosis (18.5% vs 8.2%, P = 0.039). Moreover, the AIH profile was also closely associated with hepatitis B e-antigen positivity.

CONCLUSION: ANA-H could be an indicator of early-stage CHB. Dichotomizing the autoantibody profiles revealed that the PBC profile is strongly associated with cirrhosis in CHB.

The association of exposure to hepatitis B and C viruses with lung function and respiratory disease: a population based study from the NHANES III database

BACKGROUND

Globally, 500 million people are chronically infected with Hepatitis B virus (HBV) and Hepatitis C virus (HCV). While these viruses are notorious for their detrimental effect on the liver they are also known to affect multiple organs in the body including the lungs.

AIM

To investigate if exposure to HBV and HCV is associated with lung function and respiratory diseases.

METHODS

Data from the Third National Health and Nutrition Examination Survey (NHANES III) was analysed using multiple linear regressions to investigate the association between exposure to HBV and HCV with the various measures of lung function, while multiple logistic regressions were used to evaluate the association with the respiratory diseases asthma and chronic obstructive pulmonary disease (COPD).

RESULTS

Exposure to HCV was significantly associated with an increase in Forced Expiratory Volume in 1 s, FEV1 (Coef: 97.94 ml, 95% CI: 38.87 to 157.01) and Full Vital Capacity, FVC (Coef: 90 ml, 95% CI: 14.50 to 166.24). Individuals who had been exposed to both HBV and HCV also had a significantly higher FEV1 (Coef: 145.82, CI: 60.68 to 230.94) and FVC (Coef: 195.09, CI: 78.91 to 311.26). There was also a significant association between exposure to HBV and asthma (OR: 1.28, 95% CI: 1.05 to 1.58). These associations were no longer significant after additionally adjusting for cocaine and marijuana use as well as poverty income ratio.

CONCLUSION

Our research implies that hepatotropic viruses may affect the respiratory system, but more work at a population level is needed to further explore these associations.

Primary biliary cirrhosis in HBV and HCV patients: Clinical characteristics and outcome

AIM: To present the characteristics, management and outcome of patients with hepatitis B virus (HBV) or hepatitis C virus (HCV) infections concurrent with primary biliary cirrhosis (PBC).

METHODS: Since January 2001 to September 2009, we retrospectively evaluated the medical records of all HBV (n = 1493) and HCV patients (n = 526) who are followed in our center for the presence of concurrent PBC. Seventeen patients identified with concurrent viral hepatitis and PBC (8 HCV and PBC; follow-up: 61 ± 37 mo and 9 HBV and PBC; follow-up: 57 ± 38 mo). PBC diagnosis was established if the patients met at least two of the following criteria: positivity for antimitochondrial antibody, elevated cholestatic enzymes and histological lesions of PBC.

RESULTS: HCV or HBV diagnosis preceded that of PBC in most patients by many years. PBC diagnosis was based on the presence of antimitochondrial antibody and elevated cholestatic enzymes in all 17 patients, while one third (5/17; 29.4%) experienced severe pruritus many years before diagnosis. Patients with PBC and HBV were significantly younger at diagnosis of PBC compared to patients with PBC and HCV (56.1 ± 11.2 vs 68.5 ± 10.3, respectively, P < 0.05). At initial clinical and histological assessment the majority of patients were cirrhotics (10/17; 58.8%) with the group of PBC and HCV carrying the highest frequency (87.5% vs 33.3% in PBC and HBV; P < 0.05). The patients with HBV and concomitant PBC seem to have better outcome compared to those with HCV and PBC since none of the 6 non-cirrhotics with HBV and PBC developed cirrhosis during follow-up.

CONCLUSION: PBC diagnosis in HBV or HCV patients is very difficult and usually delayed. Therefore, in any case, cholestasis should alert physicians to further search for PBC.

The vasculitic neuropathies: an update

PURPOSE OF REVIEW

Vasculitic neuropathy is a heterogeneous disorder that usually occurs in systemic diseases, but less commonly appears as nonsystemic vasculitic neuropathy (NSVN). This review is intended to highlight recent developments in the field of vasculitic neuropathies.

RECENT FINDINGS

A Peripheral Nerve Society guideline provides data-driven consensus recommendation on classification of vasculitic neuropathies and diagnosis/treatment of NSVN. NSVN is sometimes accompanied by subclinical inflammation of adjacent skin. Amyotrophic lateral sclerosis with sensory involvement can mimic NSVN. Systemic vasculitides with neuropathy include polyarteritis nodosa, microscopic polyangiitis (MPA), rheumatoid vasculitis, Churg-Strauss syndrome (CSS), and hepatitis C-related mixed cryoglobulinemic vasculitis (MCV). At autopsy, MPA affects limb nerves diffusely, with maximal damage in proximal/middle segments. CSS can be accompanied by antineutrophil cytoplasmic antibodies (ANCAs), but most patients with neuropathy lack ANCAs. Cryoglobulinemic neuropathies are usually caused by vasculitis, irrespective of phenotype. Two randomized trials revealed rituximab to be noninferior to cyclophosphamide for inducing remission in ANCA-associated vasculitis. Many reports also document efficacy of rituximab in MCV.

SUMMARY

Consensus guidelines on NSVN should be evaluated prospectively. MPA-associated vasculitic neuropathy results from vasculitic lesions distributed diffusely throughout peripheral extremity nerves. Rituximab is effective for ANCA-associated and cryoglobulinemic vasculitis with neuropathy.

The immunopathogenetic role of autoantibodies in canine autoimmune hepatitis: lessons to learn from human autoimmune hepatitis

Autoimmune hepatitis (AIH) is not a disease entity restricted to man, but it can be found in other animals including canines. An increasing number of studies have focused on the immunopathogenesis of human autoimmune hepatitis (hAIH), but little is known of what triggers canine autoimmune hepatitis (cAIH). Several drugs, toxins, microbial and viral agents are able to induce autoantibodies and indeed immune-mediated chronic canine hepatitis with immunological and serological features similar of those seen in the human disease. We discuss the features of cAIH paying attention to the autoantibody profile of the disease in comparison to that seen in hAIH. We also discuss the immunomodulatory role of specific molecular signaling pathways such as those mediated by tumor growth factor and p38 mitogen-activated kinase in the induction of AIH, and the potential of these molecules to act as targets of specialized immunotherapeutic interventions. Review of the literature indicates that we have more to learn for the delineation of autoantibody profile and the antigen-specific immunoregulatory mechanisms involved in the pathogenesis of cAIH from the human disease, rather than the other way around.

Autoimmune manifestations in viral hepatitis

Infections by the viruses responsible for hepatitis B, C and D are accompanied by a number of immunopathological manifestations. A link between infection and autoimmunity is particularly well documented for the hepatitis C virus. Immunopathological manifestations range from production of autoantibodies to overt autoimmune disease, including thyroiditis and autoimmune hepatitis, and to immune-complex-mediated disorders, including cryoglobulinaemia, glomerulonephritis and vasculitis. Several of these manifestations improve with successful antiviral treatment, directly incriminating the virus in their pathogenesis. Mechanisms considered responsible for hepatitis virus-related immunopathology, including molecular mimicry, impairment of regulatory T cells and activation of B lymphocytes, will be examined in this review.

Hepatitis B virus-associated antigen deposition in renal tissue from patients with systemic lupus erythematosus

OBJECTIVE

To determine the significance of hepatitis B virus (HBV)-associated antigen deposition in renal tissue from patients with systemic lupus erythematosus (SLE).

METHODS

The medical records of 166 inpatients with lupus nephritis and 384 controls without SLE were analyzed retrospectively. Patients with SLE were classified as positive or negative depending on whether HBV-associated antigen deposition was detected in renal biopsies.

RESULTS

HBV-associated antigen deposition was mainly detected in renal tissue from patients with SLE (50.6%), primary renal glomerular disease (20.8%), and allergic purpura (21.7%). It was not detected in renal tissue from patients with diabetic nephropathy, hypertensive nephrosclerosis, thin basement membrane nephropathy, or Alport syndrome. Hepatitis B surface antigen and core antigen were deposited in the mesangial region and vascular loops. The positive group had a significantly higher frequency of IgG, IgA, and IgM deposition than the negative group (53.6% vs 30.5%; p < 0.01). There was no significant difference in the types of lupus nephritis observed between the 2 groups.

CONCLUSION

There was a high prevalence of HBV-associated antigen deposition in renal tissue of patients with SLE by indirect immunofluorescence, which may result mainly from the cross-reactivity with deposited immunoglobulins.

Autoimmunity in hepatitis C virus carriers: involvement of ferritin and prolactin

BACKGROUND

Ferritin and prolactin have been associated with active autoimmune diseases as systemic lupus erythematosus and autoantibody production, but have been little studied in viral infections that present autoimmunity.

OBJECTIVE

To investigate the association of these two autoimmune mediators with the presence of cryoglobulinaemia and non-organ-specific autoantibodies (RF, SMA, β2GPI IgA antibody and ANA) in Brazilian individuals chronically infected with hepatitis C virus (HCV).

METHODS

Ninety-nine patients were evaluated. Ferritin and prolactin levels were determined by chemiluminescent immunoassays.

RESULTS

Hyperprolactinemia was found in 10 (six men and four women) out of 99 (10.1%) hepatitis C patients. Thirty-eight out of 99 (38.4%) HCV carriers had hyperferritinemia (median level 385ng/mL). Neither hyperprolactinemia nor hyperferritinemia was associated with cryoglobulinaemia or non-organ-specific autoantibodies (p>.05). There was an association between hyperprolactinemia and the infection with HCV genotype 3 (p<.01). Ferritin and ALT levels were correlated (p<.05).

CONCLUSION

Our results suggest that neither prolactin nor ferritin is involved with the extra-hepatic manifestation of autoimmunity observed in HCV carriers.

Autoimmune hepatitis, HLA and extended haplotypes

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease. Characteristic liver-infiltrating immune cells in portal and periportal areas, hypergammaglobulinemia and typical autoantibodies indicate an ongoing autoimmune reaction against liver self antigens, which lead to irreversible cellular damage and ultimately to severe hepatic failure. A significant part of adult, but not pediatric AIH patients, exhibit concurrent autoimmune diseases, further strengthening the immunological etiology of the disease. Genetic susceptibility to autoimmune hepatitis is strongly associated with HLA-DRB1 alleles. In Caucasian European and North American patients, AIH-1 is associated with the presence of DRB1*0301, DRB3*0101 and DRB1*0401 alleles, while AIH-2 is associated with DRB1*0301 or DRB1*07. In Brazil, the primary susceptibility allele for AIH-1 is DRB1*1301, but a secondary association with DRB1*0301 has also been identified. We looked for additional susceptibility factors in the extended MHC region. We genotyped 107 AIH-1 children and up to 326 healthy subjects for TNFA G-308A, TNFA G-238A, LTA A+252G, LTA A+80C, NFKBIL1 T-63A, BAT1 C-348T, BAT1 G-22C, MICA, and HLA-B polymorphisms. The TNFA-308 A allele was significantly increased in AIH-1 when compared with healthy controls, confirming data from other studies. Linkage disequilibrium analysis was carried out. The ancestral haplotype comprising TNFA-308A, TNFA-238G, LTA+252G, LTA+80C, NFKBIL1-63A, BAT1-348C, BAT1-22C, HLA-B*08, MICA*08 was more common in DRB1*03 positive patients than in controls (40% vs. 14%), showing a seven-fold increased risk for the disease [OR=7.8 (95%CI 2.04-29.9.2, p=0.0021). In contrast, the remaining patients carrying DRB1*03 exhibited varied haplotypes. Finally, a variety of class III haplotypes was also present in HLA-DRB1*13 patients, without a predominant pattern. The most common of the 98 haplotypes present in patients were completely absent in controls. The extended haplotype analysis in this sample of AIH-1 patients highlights not only the genetic diversity present in the Brazilian population, but is also in accordance with the previously documented microdiversity within the MHC region. The present knowledge of AIH suggests that the same or a very similar disease can be induced by yet unknown, but different, triggers followed by presentation on different HLA-DR molecules of the epitopes derived from the corresponding autoantigens, characterizing a much more complex disease than previously thought.

Clonal CD27+ CD19+ B cell expansion through inhibition of FC gammaIIR in HCV(+) cryoglobulinemic patients

Persistent HCV infection may be associated with extrahepatic manifestations such as type II mixed cryoglobulinemia (II-MC), a clonal B cell proliferative disorder. In persistent HCV infection without II-MC, an increase in serum immunoglobulins (Ig) is commonly observed. This increase is polyclonal and is determined primarily by increased levels of IgG which include both HCV-specific and nonspecific antibodies. Nonetheless, memory CD27(+) B cells do not accumulate. This paradoxical phenomenon depends on heightened sensitivity of memory B cells to BCR-independent noncognate T cell help, which speeds up their terminal differentiation into antibody-secreting cells and makes them more prone to apoptosis. In persistent HCV infection with II-MC, serum Ig elevation is also a general occurrence, and characteristically includes IgM antibodies with rheumatoid factor activity, which are essential for the development of circulating, cryoprecipitable immune complexes. Hypergammaglobulinemia is sustained by a peripheral expansion of IgM(+)k(+)IgD(low/neg)CD21(low)CD27(+) B cells. These cells exhibit marked V(H), J(H), and V(K) gene segment usage restriction, indicating that a limited number of antigens drive their proliferation through BCR interaction. Recently, two epitopes, one of the human IgG and the second of the HCV(NS3) protein, had been identified and demonstrated able to link the BCR exposed on II-MC subjects. Based on the above findings, we propose a model whereby BCR binding the IgM/IgG/HCV(NS3) immune complexes deprives Fc gammaIIR of its natural ligand. This takes the brake off RF(+)CD27(+) B cell proliferation and promotes their selective accumulation, which is otherwise prevented by increased apoptosis susceptibility in persistent HCV infection without II-MC.

Differential susceptibility of peripheral blood CD5+ and CD5- B cells to apoptosis in chronic hepatitis C patients

A body of evidence has suggested a close link between chronic hepatitis C virus (HCV) infection and B cell abnormalities, including mixed cryoglobulinemia, rheumatoid factor (RF) production, and lymphoproliferative disorders that may develop into non-Hodgkin's lymphoma. Recent studies have demonstrated the expansion of CD5(+) B cells in the peripheral blood of chronic hepatitis C patients (CHC). As CD5(+) B cells, which are capable of producing autoantibodies and RF, are apparently crucial for the development of HCV-associated pathogenesis, the fate of both the CD5(+) and CD5(-) B cell subsets upon chronic HCV infection is of interest. In this study, the degree to which chronic HCV infection induces apoptosis in each B cell subset was investigated. Our results demonstrated that peripheral CD5(-) B cells were more susceptible to apoptosis than CD5(+) B cells in CHC. Furthermore, plasma levels of IL-4, IL-10, and IL-12 were significantly elevated in CHC, thus suggesting that these interleukins protect CD5(+) B cells from apoptosis. The rationale for the differential susceptibility of distinct B cell subsets in CHC is also discussed with regard to extrahepatic manifestations associated with chronic HCV infection.

B cells and HCV: an infection model of autoimmunity

In addition to cause acute and chronic liver disease, hepatitis C virus (HCV) infection is frequently associated to autoimmune disorders, such as mixed cryoglobulinemia, primary glomerulonephritis, monoclonal gammopathy of undetermined significance and post-transplant proliferative disorders. Progression to malignant phenotype of B cells may be the consequence of additional genetic events or abnormal conditions resulting from modification of host cell genes involved in the control of oncogenes and oncoproteins. In this review, we will address the potential immune disregulatory mechanism(s) underlying HCV persistence. In addition, HCV/B-cell interaction that might explain defects in humoral immunity in individuals who develop chronic virus carriage and lymphoproliferative disorders will be emphasized.