Plasma chemokine levels correlate with the outcome of antiviral therapy in patients with hepatitis C

The role of chemokines in the recruitment of lymphocytes to the liver

Chemokines direct leukocyte trafficking and positioning within tissues, thus playing critical roles in regulating immune responses and inflammation. The chemokine system is complex, involving interactions between multiple chemokines and their receptors that operate in combinatorial cascades with adhesion molecules. The involvement of multiple chemokines and chemokine receptors in these processes brings flexibility and specificity to recruitment. The hepatic vascular bed is a unique low-flow environment through which leukocytes are recruited to the liver during homeostatic immune surveillance and in response to infection or injury. The rate of leukocyte recruitment and the nature of cells recruited through the sinusoids in response to inflammatory signals will shape the severity of disease. At one end of the spectrum, fulminant liver failure results from a rapid recruitment of leukocytes that leads to hepatocyte destruction and liver failure; at the other end, diseases such as chronic hepatitis C infection may progress over many years from hepatitis to fibrosis and cirrhosis. Chronic hepatitis is characterized by a T lymphocyte-rich infiltrate and the nature and outcome of hepatitis will depend on the T cell subsets recruited, their activation and function within the liver. Different subsets of effector T cells have been described based on their secretion of cytokines and specific functions. These include Th1 and Th2 cells, and more recently Th17 and Th9 cells, which are associated with different types of immune response and which express distinct patterns of chemokine receptors that promote their recruitment under particular conditions. The effector function of these cells is balanced by the recruitment of regulatory T cells that are able to suppress antigen-specific effectors to allow resolution of immune responses and restoration of immune homeostasis. Understanding the signals that are responsible for recruiting different lymphocyte subsets to the liver will elucidate disease pathogenesis and open up new therapeutic approaches to modulate recruitment in favor of resolution rather than injury.

Management of nonresponsive hepatitis C

More than 50% of hepatitis C virus (HCV)-infected patients do not respond to the classical pegylated interferon (PEG-IFN)/ribavirin combination therapy. However, failing to respond to one course of treatment is not synonymous of therapy failure and retreatment is often beneficial. Alternative retreatment strategies include repeating the classical standard of care with an optimized drug regimen and adherence, including ribavirin serum concentration adjustment, correcting, if at all possible, comorbidities, and the addition of new specific anti-HCV molecules to the backbone of pegylated interferon/ribavirin. Options of retreatment should include consensus and natural interferons. For patients with advanced disease exposed to a high risk of lethal complications, customized maintenance therapy could be an effective option since it may slow down complications in some patients. Since low-dose interferon monotherapy is not sufficient, such a maintenance therapy remains to be verified via clinical trials. New possibilities of noninvasive assessment of fibrosis and the use of genetic tests to predict fibrosis progression and responsiveness to interferon are major emerging opportunities that run parallel to the revolution of the pharmacologic armentarium.

Therapeutic silencing of microRNA-122 in primates with chronic hepatitis C virus infection

The liver-expressed microRNA-122 (miR-122) is essential for hepatitis C virus (HCV) RNA accumulation in cultured liver cells, but its potential as a target for antiviral intervention has not been assessed. We found that treatment of chronically infected chimpanzees with a locked nucleic acid (LNA)-modified oligonucleotide (SPC3649) complementary to miR-122 leads to long-lasting suppression of HCV viremia, with no evidence of viral resistance or side effects in the treated animals. Furthermore, transcriptome and histological analyses of liver biopsies demonstrated derepression of target mRNAs with miR-122 seed sites, down-regulation of interferon-regulated genes, and improvement of HCV-induced liver pathology. The prolonged virological response to SPC3649 treatment without HCV rebound holds promise of a new antiviral therapy with a high barrier to resistance.

Serum concentrations of interleukin 1beta, CXCL10, and interferon-gamma in mixed cryoglobulinemia associated with hepatitis C infection

OBJECTIVE

Mixed cryoglobulinemia (MC) is a systemic vasculitis of small and medium-size vessels, often associated with the hepatitis C virus. Research has shown an emerging role for chemokines and type 1 cytokines in the pathophysiology of this vasculitis. Interleukin 1 (IL-1) plays a role in initiating the cascade of immunoinflammatory responses, and levels of the interferon-gamma (IFN-gamma) inducible chemokine CXCL10 have been shown to be significantly associated with the presence of active vasculitis in patients with MC. We evaluated serum levels of IL-1beta, IFN-gamma, and CXCL10 in a series of patients with hepatitis C-related MC (MC+HCV), and correlated these measurements with clinical disease features.

METHODS

Serum IL-1beta, IFN-gamma, and CXCL10 were assayed in 54 patients with MC+HCV, in 54 sex- and age-matched patients with type C chronic hepatitis without cryoglobulinemia (HCV+), and in 54 controls.

RESULTS

MC+HCV patients showed significantly higher mean IL-1beta and CXCL10 serum levels than controls (p < 0.01) or HCV+ patients (p < 0.01). CXCL10 was significantly increased in 14 cryoglobulinemic patients with active vasculitis (necrotizing vasculitis or vasculitic skin ulcers) compared to those without (p < 0.001); IL-1beta was increased in cryoglobulinemic patients with active vasculitis (p = 0.06). No differences were observed for serum IFN-gamma levels.

CONCLUSION

Serum levels of IL-1beta and CXCL10 were high in patients with MC+HCV. Increased CXCL10 and IL-1beta levels were associated with the presence of active vasculitis in MC+HCV patients.

CXCL10 and CCL2 chemokine serum levels in patients with hepatitis C associated with autoimmune thyroiditis

To evaluate CXCL10 and CCL2 in patients with hepatitis C virus chronic infection in presence/absence of autoimmune thyroiditis (AT). CXCL10 was significantly higher in: (1) patients with AT than controls without AT (control 1) (P < 0.001; ANOVA); (2) patients with hepatitis C infection than control 1 and patients with AT (P < 0.001); (3) patients with hepatitis C virus chronic infection and AT (HCV+AT) than control 1 and patients with AT (P < 0.001) and hepatitis C (P = 0.004). By defining a high CXCL10 level as a value >218 pg/mL, 2% of control 1, 14% of patients with AT, 68% of patients with hepatitis C infection, 81% of HCV+AT had high CXCL10 (P < 0.0001; chi-square). CCL2 was similar in control 1 and patients with AT. CCL2 was significantly higher in: (1) patients with hepatitis C infection than control 1 (P = 0.04; ANOVA); (2) HCV+AT than patients with AT (P = 0.03) and control 1 (P = 0.02); no difference was observed between HCV with or without AT. Our study demonstrates: (1) higher circulating CXCL10 and CCL2 in patients with hepatitis C virus chronic infection than in controls; (2) higher CXCL10 in HCV+AT than in patients with hepatitis C infection, suggesting a stronger Th1 immune response in these patients.

Expansion of functionally skewed CD56-negative NK cells in chronic hepatitis C virus infection: correlation with outcome of pegylated IFN-alpha and ribavirin treatment

NK cells are important innate immune effector cells, normally characterized as CD56(+)CD3(-) lymphocytes. In this study, we report that CD56(-)CD16(+) NK cells expand in many patients with chronic hepatitis C virus infection. These CD56(-) NK cells were functionally impaired with respect to cytokine production upon target cell recognition, in comparison to CD56(dim) and CD56(bright) NK cell subsets. In particular, CD56(-) NK cells were strikingly defective in their polyfunctional response as measured by the coexpression of MIP-1beta, IFN-gamma, TNF-alpha, and CD107a degranulation. The ability of these cells to mediate three or four of these functions was poor; expression of MIP-1beta alone dominated their response. CD56(-) NK cells retained expression of receptors such as the natural cytotoxicity receptors and NKG2D, whereas the expression of CD57 and perforin was lower when compared with CD56(dim) NK cells. Interestingly, pretreatment levels of CD56(-) NK cells correlated with the outcome of pegylated IFN-alpha and ribavirin treatment. In patients with CD56(-) NK cells in the range of healthy subjects, 80% reached a sustained virological response to treatment, whereas only 25% of patients with levels clearly above those in healthy subjects experienced a sustained virological response. Thus, chronic hepatitis C virus infection is associated with an expansion of CD56(-) NK cells functionally skewed toward MIP-1beta production only. Furthermore, high levels of these cells reveal a disturbance in innate cellular immunity that is associated with an impaired ability to respond to antiviral treatment with IFN-alpha and ribavirin.

The role of chemokines in the recruitment of lymphocytes to the liver

Chemokines direct leukocyte trafficking and positioning within tissues. They thus play critical roles in regulating immune responses and inflammation. The chemokine system is complex involving interactions between multiple chemokines and their receptors that operate in combinatorial cascades with adhesion molecules. The involvement of multiple chemokines and chemokine receptors in these processes brings flexibility and specificity to recruitment. The hepatic vascular bed is a unique low flow environment through which leukocyte are recruited to the liver during homeostatic immune surveillance and in response to infection or injury. The rate of leukocyte recruitment and the nature of cells recruited through the sinusoids in response to inflammatory signals will shape the severity of disease. At one end of the spectrum fulminant liver failure results from a rapid recruitment of leukocytes that leads to hepatocyte destruction and liver failure at the other diseases such as chronic hepatitis C infection may progress over many years from hepatitis to fibrosis and cirrhosis. Chronic hepatitis is charactezised by a T lymphocyte rich infiltrate and the nature and outcome of hepatitis will depend on the T cell subsets recruited, their activation and function within the liver. Different subsets of effector T cells have been described based on their secretion of cytokines and specific functions. These include Th1 and Th2 cells and more recently Th17 and Th9 cells which are associated with different types of immune response and which express distinct patterns of chemokine receptors that promote their recruitment under particular conditions. The effector function of these cells is balanced by the recruitment of regulatory T cells that are able to suppress antigen-specific effectors to allow resolution of immune responses and restoration of immune homeostasis. Understanding the signals that are responsible for recruiting different lymphocyte subsets to the liver will elucidate disease pathogenesis and open up new therapeutic approaches to modulate recruitment in favour of resolution rather than injury.

Gene expression and hepatitis C virus infection

Hepatitis C virus (HCV) is a major cause of chronic liver disease, with about 170 million people infected worldwide. Up to 70% of patients will have persistent infection after inoculation, making this disease a significant cause of morbidity and mortality. The severity of disease varies widely, from asymptomatic chronic infection to cirrhosis and hepatocellular carcinoma. Since the discovery of HCV, the treatment of hepatitis C has considerably improved. Recently, combination of pegylated interferons with ribavirin gives a response rate of about 55%. Treatment is indicated in patients with moderate or severe fibrosis. The tolerability of combination treatment is relatively poor, with a frequent flu-like syndrome and an impaired quality of life. In addition to viral and environmental behavioural factors, host genetic diversity is believed to contribute to the spectrum of clinical outcomes in HCV infection. The sequencing of the human genome, together with the development of high-throughput technologies that measure the function of the genome, have afforded unique opportunities to develop profiles that can distinguish, identify and classify discrete subsets of disease, predict the disease outcome or predict the response to treatment. This paper reviews the published literature on gene expression associated with HCV infection (HCV infection, fibrosis progression), and also according to response to treatment.

Role of chemokines and their receptors in viral persistence and liver damage during chronic hepatitis C virus infection

Chemokines produced in the liver during hepatitis C virus (HCV) infection induce migration of activated T cells from the periphery to infected parenchyma. The milieu of chemokines secreted by infected hepatocytes is predominantly associated with the T-helper cell/Tc1 T cell (Th1/Tc1) response. These chemokines consist of CCL3 (macrophage inflammatory protein-1 alpha; MIP-1 alpha), CCL4 (MIP-1 beta), CCL5 (regulated on activation normal T cell expressed and secreted; RANTES), CXCL10 (interferon-gamma-inducible protein-10; IP-10), CXCL11 (interferon-inducible T-cell alpha chemoattractant; I-TAC), and CXCL9 (monokine induced by interferon gamma; Mig) and they recruit T cells expressing either CCR5 or CXCR3 chemokine receptors. Intrahepatic and peripheral blood levels of these chemokines are increased during chronic hepatitis C. The interaction between chemokines and their receptors is essential in recruiting HCV-specific T cells to control the infection. When the adaptive immune response fails in this task, non-specific T cells without the capacity to control the infection are also recruited to the liver, and these are ultimately responsible for the persistent hepatic damage. The modulation of chemokine receptor expression and chemokine secretion could be a viral escape mechanism to avoid specific T cell migration to the liver during the early phase of infection, and to maintain liver viability during the chronic phase, by impairing non-specific T cell migration. Some chemokines and their receptors correlate with liver damage, and CXCL10 (IP-10) and CXCR3 levels have shown a clinical utility as predictors of treatment response outcome. The regulation of chemokines and their receptors could be a future potential therapeutic target to decrease liver inflammation and to increase specific T cell migration to the infected liver.

Endocrine manifestations of hepatitis C virus infection

Chronic infection with hepatitis C virus (HCV) can result in both hepatic and extrahepatic disease and endocrine dysfunction represents an important class of HCV-related extrahepatic disease. The most frequently occurring--and clinically important--of these endocrine disorders are thyroid disease and type 2 diabetes mellitus. In this Review, we evaluate the evidence in support of a link between HCV infection and endocrine-system dysfunction, and discuss potential pathophysiological mechanisms. A meta-analysis of the literature has revealed significant associations between chronic HCV infection, thyroid autoimmunity and hypothyroidism. Furthermore, a high prevalence of thyroid cancer has been reported in HCV-positive patients. Several clinicoepidemiological studies have demonstrated that chronic HCV infection could lead to the development of type 2 diabetes mellitus, possibly as a result of HCV-induced metabolic disturbances. Some researchers have postulated that a type 1 T-helper -cell mediated immune response underpins the association of chronic HCV infection with endocrine disease. Indeed, the available data suggest that a common immunological, type 1 T-helper cell pattern of cytokine expression and activation (via interferon-gamma) could provide the pathophysiological basis for this association. Nonetheless, additional studies will be necessary to elucidate fully all the mechanisms involved in HCV-related endocrine dysfunction.

Chemokines in the immunopathogenesis of hepatitis C infection

Chronic infection with the hepatitis C virus, a noncytopathic hepatotropic RNA virus, affects over 170 million people worldwide. In the majority of cases, neither the early innate immune response nor the later adaptive immune response succeeds in clearing the virus, and the infection becomes chronic. Furthermore, in many patients, the ineffective inflammatory response drives fibrogenesis and the development of cirrhosis. It is critical to understand this immune pathology if preventative and curative therapies are to be developed. Chemokines are a superfamily of small proteins that promote leukocyte migration and orchestrate the immune response to viruses, including hepatitis C virus. Chemokines are crucial for viral elimination, but inappropriate persistence of expression in chronic hepatitis C infection can drive tissue damage and inflammation. Here we review the role of chemokines and their receptors in hepatitis C virus infection.

CXCL10 and CCL2 serum levels in patients with mixed cryoglobulinaemia and hepatitis C

BACKGROUND

No study evaluates serum levels of CXCL10 and CCL2 chemokines in patients with hepatitis C associated mixed cryoglobulinaemia.

AIMS

To measure circulating CXCL10 and CCL2 in cryoglobulinaemic patients.

PATIENTS AND METHODS

Serum CXCL10 and CCL2 were assayed in 70 consecutive cryoglobulinaemic patients, and in 2 control groups (1:1, gender- and age-matched) of healthy (controls), or of chronic hepatitis C subjects without cryoglobulinaemia.

RESULTS

Cryoglobulinaemic patients showed higher CXCL10 serum levels than controls (p<0.0001), or hepatitis C patients (p=0.001) (389 +/- 141, 91 +/- 51, 311 +/- 142 pg/ml, respectively). By defining a "high CXCL10" as a value at least 2 S.D. above the mean value of the control group (>193 pg/ml), 79% of cryoglobulinaemic patients, 5% of the controls and 69% of hepatitis C patients had high CXCL10 (p<0.0001). CXCL10 levels were (p<0.01) increased in cryoglobulinaemic patients with active vasculitis, with respect to those without (445+/-108, 339 +/- 161 pg/ml, respectively). Cryoglobulinaemic patients showed significantly higher CCL2 serum level than controls (p<0.01), but not than hepatitis C patients (541 +/- 493, 387 +/- 173 and 451 +/- 281 pg/ml, respectively).

CONCLUSION

Our study first demonstrates high serum levels of CXCL10 and CCL2 chemokines in cryoglobulinaemic patients. Circulating CXCL10 is higher overall in cryoglobulinaemic patients with active vasculitis, suggesting a prevalence of the Th1 immune response in this phase.

Molecular and contextual markers of hepatitis C virus and drug abuse

The spread of hepatitis C virus (HCV) infection involves a complex interplay of social risks, and molecular factors of both virus and host. Injection drug abuse is the most powerful risk factor for HCV infection, followed by sexual transmission and additional non-injection drug abuse factors such as co-infection with other viruses and barriers to treatment. It is clearly important to understand the wider context in which the factors related to HCV infection occur. This understanding is required for a comprehensive approach leading to the successful prevention, diagnosis, and treatment of HCV. An additional consideration is that current treatments and advanced molecular methods are generally unavailable to socially disadvantaged patients. Thus, the recognition of behavioral/social, viral, and host factors as components of an integrated approach to HCV is important to help this vulnerable group. Equally important, this approach is key to the development of personalized patient treatment - a significant goal in global healthcare. In this review, we discuss recent findings concerning the impact of drug abuse, epidemiology, social behavior, virology, immunopathology, and genetics on HCV infection and the course of disease.

Predictors of sustained virological response to a 48-week course of pegylated interferon alfa-2a and ribavirin in patients infected with hepatitis C virus genotype 4

BACKGROUND AND OBJECTIVES

Knowledge of the predictors of sustained viral response (SVR) to pegylated interferon (PEG-INF) alfa-2a and ribavirin (RBV) therapy in patients with hepatitis C genotype-4 (HCV-4) is crucial for selecting patients who would benefit most from therapy. We assessed the predictors of SVR to this combination therapy in Saudi patients with chronic HCV-4 infection.

PATIENTS AND METHODS

This retrospective study included 148 patients with HCV-4 infection who underwent clinical, biochemical and virological assessments before treatment and at 12, 24, 48 and 72 weeks post-treatment.

RESULTS

Of the 148 patients, 90 (60.8%) were males. Mean (SD) for age was 48.5 (12.7) years and BMI was 27.9 (7.5) kg/m(2). Seventy-nine of 148 (60.1%) patients were treatment naïve and 110 (74.3%) underwent pre-treatment liver biopsy. Eighteen (12.2%) patients did not complete therapy because of side effects or they were lost to follow up. Early virological response was achieved in 84 of 91 (92.3%) patients. In the 130 (87.8%) patients who completed therapy, 34 (26.2%) were non-responders and 96 (63.8%) achieved end-of-treatment virological response (ETVR). SVR and virological relapse (24 weeks after ETVR) occurred in 66/130 (50.7%) and 30/130 (31.2%) patients, respectively. Compared to relapsers, sustained responders were significantly younger (P=.005), non-diabetic (P=.005), had higher serum albumin (P=.028), lower alpha-fetoprotein level (P=.026), lower aspartate aminotransferase (AST) (P=.04) levels, and were treatment-naïve (P=.008). In a multivariate regression analysis, the independent predictors of SVR were younger age (P=.016), lower serum AST (P=.012), and being treatment naïve (P=.021).

CONCLUSION

Approximately half of HCV-4 patients who complete the course of combination therapy achieve an SVR, especially if they are young, treatment naA ve and have lower AST levels.

Role of chemokines and their receptors in viral persistence and liver damage during chronic hepatitis C virus infection

Chemokines produced in the liver during hepatitis C virus (HCV) infection induce migration of activated T cells from the periphery to infected parenchyma. The milieu of chemokines secreted by infected hepatocytes is predominantly associated with the T-helper/T-cytotoxic type-1 cell (Th1/Tc1) response. These chemokines consist of CCL3 (macrophage inflammatory protein-1α; MIP-1α), CCL4 (MIP-1β), CCL5 (regulated on activation normal T cell expressed and secreted; RANTES), CXCL10 (interferon-γ−inducible protein-10; IP-10), CXCL11 (interferon-inducible T-cell α chemoattractant; I-TAC), and CXCL9 (monokine induced by interferon γ; Mig) and they recruit T cells expressing either CCR5 or CXCR3 chemokine receptors. Intrahepatic and peripheral blood levels of these chemokines are increased during chronic hepatitis C. The interaction between chemokines and their receptors is essential in recruiting HCV-specific T cells to control the infection. When the adaptive immune response fails in this task, non-specific T cells without the capacity to control the infection are also recruited to the liver, and these are ultimately responsible for the persistent hepatic damage. The modulation of chemokine receptor expression and chemokine secretion could be a viral escape mechanism to avoid specific T cell migration to the liver during the early phase of infection, and to maintain liver viability during the chronic phase, by impairing non-specific T cell migration. Some chemokines and their receptors correlate with liver damage, and CXCL10 (IP-10) and CXCR3 levels have shown a clinical utility as predictors of treatment response outcome. The regulation of chemokines and their receptors could be a future potential therapeutic target to decrease liver inflammation and to increase specific T cell migration to the infected liver.

Plasmacytoid dendritic cells move down on the list of suspects: in search of the immune pathogenesis of chronic hepatitis C

Chronic hepatitis C is a major public health problem. Despite numerous clinical studies in humans and experimental observations made in chimpanzees, hepatitis C pathogenesis remains poorly understood. Here, we review the clinical features of acute and chronic disease, and discuss the role of the immune system in the pathogenesis of disease. Many are aware of the dual role of T cells: responsibility for clearance of the virus during acute phase; and liver injury during chronic phase. Nonetheless, there is an emerging belief that failure to prime HCV-specific T cells is responsible for the failure to spontaneously clear the virus, and possibly, for the lack of response to pegylated-IFNalpha(2a)/ribavirin therapy. We have focused on the latest suspects, plasmacytoid dendritic cells (pDCs), considered to be the professional type I IFNs producing cells. We review the somewhat contradictory data regarding the functional capacity of pDCs in chronic HCV patients and argue that, while lower in relative concentration as compared to healthy individuals, they are not defective in their ability to initiate an innate inflammatory response. Thus, instead of being the culprit, pDCs may in fact represent a novel therapeutic target in order to improve upon existing therapies for treating HCV patients.

Cellular and molecular interactions in coinfection with hepatitis C virus and human immunodeficiency virus

Coinfection with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) is associated with increased HCV replication and a more rapid progression to severe liver disease, including the development of cirrhosis and hepatocellular carcinoma. In this review, we discuss the current understanding of the pathogenesis of HCV/HIV coinfection and the cellular and molecular mechanisms associated with the accelerated course of liver disease. The strength and breadth of HCV-specific T-cell responses are reduced in HCV/HIV-coinfected patients compared with those infected with HCV alone, suggesting that the immunosuppression induced by HIV compromises immune responses to HCV. HCV is not directly cytopathic, but many of the pathological changes observed in the liver of infected patients are a direct result of the intrahepatic antiviral immune responses. Apoptosis also has a role in HCV-mediated liver damage through the induction of apoptotic pathways involving the host immune response and HCV viral proteins. This review summarises the evidence correlating the role of cell-mediated immune responses and apoptosis with liver disease progression in HCV/HIV-coinfected patients.

High values of CXCL10 serum levels in mixed cryoglobulinemia associated with hepatitis C infection

OBJECTIVES

No study has evaluated circulating CXCL10 in patients with mixed cryoglobulinemia (MC) and hepatitis C virus (HCV) chronic infection. The aim of this study is to measure inteferon-inducible protein 10 (CXCL10/IP-10), interferon-gamma (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) (Th1 cytokines) in a series of cryoglobulinemic patients and to correlate this parameter to the clinical phenotype.

METHODS

Serum CXCL10, IFN-gamma, and TNF-alpha were assayed in 102 patients with hepatitis C-associated cryoglobulinemia (MC + HCV), in 102 sex- and age-matched patients with type C chronic hepatitis without cryoglobulinemia (HCV+), and in 102 sex- and age-matched controls.

RESULTS

Cryoglobulinemic patients showed significantly higher mean CXCL10 serum levels than controls (P < 0.0001) or HCV+ patients (P < 0.0001) (397 +/- 132 pg/mL, 92 +/- 53 pg/mL, 280 +/- 149 pg/mL, respectively). Moreover, CXCL10 was significantly increased in 30 cryoglobulinemic patients with active vasculitis compared to those without it (460 +/- 104 pg/mL vs 369 +/- 139 pg/mL, respectively; P < 0.001). Both groups of MC + HCV patients with or without active vasculitis had serum CXCL10 significantly higher than HCV+ patients (P < 0.001, P= 0.02, respectively). IFN-gamma levels were not significantly different in MC + HCV than in HCV+ patients or controls. Serum TNF-alpha levels were significantly higher in MC + HCV than in HCV+ patients or controls (median [interquartile range]: 12.0 [9.8], 5.7 [5.4], 1.3 [2.1] pg/mL, respectively; P < 0.0001).

CONCLUSIONS

The study demonstrates high CXCL10 and TNF-alpha serum levels in patients with hepatitis C-associated cryoglobulinemia. Moreover, in MC + HCV patients, increased CXCL10 levels were significantly associated with the presence of active vasculitis.

Alpha-chemokine CXCL10 and beta-chemokine CCL2 serum levels in patients with hepatitis C-associated cryoglobulinemia in the presence or absence of autoimmune thyroiditis

Chemokines have been identified to play an important role in endocrine autoimmune disease and hepatitis C chronic infection. To our knowledge, no study has evaluated serum levels of CXCL10 and CCL2 in patients with "mixed cryoglobulinemia and hepatitis C virus chronic infection" (MC) in the presence or absence of autoimmune thyroiditis (AT). Serum CXCL10 and CCL2 were assayed in 60 patients with MC, in 45 patients with "MC with AT" (MC + AT), and in controls (60 without [control 1] and 45 with AT [control 2]). CXCL10 was significantly higher (1) in control 2 than in control 1 (P < .001), (2) in MC than in control 1, and (3) in MC + AT than in controls 1 and 2 and in MC (P = .002). A high CXCL10 level (>mean + SD control 1; >167 pg/mL) was present in 7% control 1, 21% control 2, 49% MC, and 78% MC + AT (P < .0001). CCL2 was significantly higher in MC and in MC + AT than in control 1 or in control 2 (P < .01). A high CCL2 level (>mean + SD control 1; >730 pg/mL) was present in 2% control 1, 1% control 2, 18% MC, and 21% MC + AT (P < .0001). The study demonstrates high CXCL10 and CCL2 serum levels in patients with MC; CXCL10 in MC + AT is significantly higher than that in MC. Future studies in larger series will be needed to evaluate the potential usefulness of serum CXCL10 and CCL2 determination as a prognostic marker in the follow-up of MC patients, also in relation to the presence of AT.

Immunopathogenesis of HCV-related endocrine manifestations in chronic hepatitis and mixed cryoglobulinemia

Hepatitis C Virus (HCV) is known to be responsible for both hepatic and extrahepatic diseases (HCV-related extrahepatic diseases = HCV-EHDs). The most important systemic HCV-EHDs are mixed cryoglobulinemia and lymphoproliferative disorders, while the most frequent and clinically important endocrine HCV-EHDs are thyroid disorders and type 2 diabetes mellitus (T2D). From a meta-analysis of the literature a significant association between HCV infection and thyroid autoimmunity and hypothyroidism has been reported. A high prevalence of thyroid cancer has been reported, too. Furthermore, several clinical epidemiologic studies have reported that HCV infection is associated to T2D. Many studies have linked Th1 immune response with HCV infection, thyroid autoimmunity, or diabetes. These findings suggest that a possible common immunological Th1 pattern could be the pathophysiological base of the association of HCV-EHDs, with thyroid autoimmunity and T2D. In fact, HCV infection of thyrocytes or beta-cells may act by upregulating CXCL10 secretion in these cells that is responsible for Th1 lymphocyte recruitment. Th1 response leads to increased IFNgamma and TNFalpha production that in turn stimulates CXCL10 secretion by the target cells, thus perpetuating the immune cascade. This process may lead to the appearance of thyroid autoimmune disorders or T2D in genetically predisposed subjects.

Increased serum levels of the chemokine CXCL13 and up-regulation of its gene expression are distinctive features of HCV-related cryoglobulinemia and correlate with active cutaneous vasculitis

Chemokine CXCL13, also known as BCA-1 (B cell-attracting chemokine-1) or BLC (B-lymphocyte chemoattractant), is a major regulator of B-cell trafficking. Hepatitis C virus (HCV) infection may be associated with B-cell dysfunction and lymphoproliferative disorders, including mixed cryoglobulinemia (MC). This study evaluates circulating levels of CXCL13 protein and specific mRNA expression in chronically HCV-infected patients with and without MC. Compared with healthy controls and HCV-infected patients without MC, CXCL13 serum levels were significantly higher in MC patients. The highest CXCL13 levels strongly correlated with active cutaneous vasculitis. CXCL13 gene expression in portal tracts, isolated from liver biopsy tissues with laser capture microdissection, showed enhanced levels of specific mRNA in MC patients with active cutaneous vasculitis. Specific CXCL13 gene mRNA expression was also up-regulated in skin tissue of these patients. These findings paralleled specific deposits of CXCL13 protein both in the liver and in the skin. Our results indicate that up-regulation of CXCL13 gene expression is a distinctive feature of HCV-infected patients. Higher levels of this chemokine in the liver as well as in the skin of patients with active MC vasculitis suggest a possible interrelation between these biologic compartments.

Sustained virologic response to peginterferon alpha-2a and ribavirin in 335 patients with chronic hepatitis C: a tertiary care center experience

BACKGROUND/AIM

This retrospective study assessed the efficacy, safety, and the predictors of sustained viral response (SVR) to a 48-week-course of peginterferon alpha-2a (Pegasys) and ribavirin combination therapy in 335 consecutive Saudi patients with chronic hepatitis C virus (HCV) infection.

MATERIALS AND METHODS

Clinical, biochemical, and virological parameters were collected at time 0 (pretreatment) and at 12, 24, 48, and 72 weeks posttreatment. The mean +/- SD age was 49.1 +/- 13.0 years; 229 (68.4%) were males, mean +/- SD body mass index was 27.8 +/- 7.4, 85 (25.4%) were diabetic, 25 (7.5%) had renal impairment, 136 (40.6%) had previously received interferon +/- ribavirin therapy, and 247 (73.7%) underwent pretreatment liver biopsy. Patients with genotypes 1, 2 or 3, 4 and mixed genotype were 60 (22.15%), 30 (11.0%), 148 (54.4%), and 34 (12.5%), respectively.

RESULTS

Early viral response (>or=2-log10 HCV-RNA decline 12 weeks posttreatment) was achieved in 253 (75.3%). Patients who completed 48 weeks of treatment were 292 (87.1%); of these, 121 (75.6%) achieved ETVR, 161 (55.1%) continued to have SVR and 60 (20.5%) had a viral relapse following end-of-treatment response, that is 48.1 and 17.9% of all patients (n = 335), respectively. Nonresponders (NR) were 71 (24.3%) patients and 43 (12.8%) were unable to complete treatment (due to side effects or loss to follow up). Compared to the relapsers, patients with SVR were significantly younger (P = 0.000), nondiabetics (P = 0.015), had higher serum albumin (P = 0.007), had less pretreatment inflammatory grade (P = 0.011), infected with genotypes 2 or 3 (P = 0.014), and treatment-naïve patients (P = 0.001). However, in stepwise multivariate logistic regression analysis, only treatment naiveté and low pretreatment inflammatory score were the independent predictors of SVR (P = 0.005 and P = 0.018, respectively).

CONCLUSION

Combination therapy, if tolerated and completed, is effective in treating chronic HCV patients, especially those with no previous interferon therapy and lower pretreatment inflammatory grade.

High values of CXCL10 serum levels in patients with hepatitis C associated mixed cryoglobulinemia in presence or absence of autoimmune thyroiditis

The aim of this study was to evaluate CXCL10 serum levels in patients with hepatitis C virus chronic infection (HCV) associated mixed cyoglobulinemia (MC), in the presence or absence of autoimmune thyroiditis (AT). CXCL10 was assayed in 50 MC patients without AT, in 40 MC patients with AT (MC+AT), in 2 gender- and age-matched control groups [50 healthy controls (without HCV or AT; control); 40 controls with AT (without HCV and MC; control+AT)]. CXCL10 was significantly higher: (1) in control+AT than in control (p<0.001); (2) in MC patients than in control (p<0.001); (3) in MC+AT patients than in control (p<0.001), control+AT (p<0.001), or in MC (p=0.002). CXCL10 was significantly increased in MC+AT patients with thyroid hypoechogenicity (388+/-147 vs 302+/-112; p=0.03), or hypothyroidism (391+/-142 vs 307+/-118; p=0.04), compared to those without. By defining a high CXCL10 level as a value at least 2 SD above the mean value of the control (>167 pg/ml), 8% of control, 22% of control+AT, 47% of MC and 80% of MC+AT had high CXCL10 (p<0.0001). In conclusion, our study is the first to demonstrate high serum levels of CXCL10 in MC and that CXCL10 in MC+AT patients are significantly higher compared to MC patients.

The role of CCR5/CXCR3 expressing CD8+ cells in liver damage and viral control during persistent hepatitis C virus infection

BACKGROUND/AIMS

CXCR3 and CCR5 play a major role in recruiting cytotoxic T cells (Tc) and secreting secondary type 1 cytokines (Tc1) in the liver. HCV could impair their expression as a survival mechanism. The role of these chemokine receptors on CD8+ cells in chronic hepatitis C is analysed.

METHODS

Serum, chemokines, peripheral blood and intrahepatic lymphocytes from chronic hepatitis C patients were studied. CXCR3/CCR5 expressing CD8+ cells were quantified by flow-cytometry. Serum chemokines concentration (CXCL10/CCL3) was measured by ELISA. Basal data were correlated with liver inflammation. Longitudinal data were obtained during treatment and correlated with virologic response.

RESULTS

CCR5/CXCR3 expressing CD8+ cells were enriched in the liver and correlated with inflammation. Chronic HCV patients presented the same frequency of CCR5(high)/CXCR3(high) expressing CD8+ cells in peripheral blood as in healthy controls but higher serum concentration of CXCL10/CCL3. Treatment with PEG-interferon alpha-2b plus ribavirin increased CCR5(high)/CXCR3(high) expressing CD8+ cells frequency in peripheral blood and decreased CXCL10/CCL3 serum concentration. Increase in CXCR3(high) expressing CD8+ cells after 24 weeks of treatment was correlated with SVR.

CONCLUSIONS

In chronic hepatitis C, anti-viral treatment induces an increase in CD8+ cells expressing chemokine receptors associated with Tc1 response and a reduction in their ligands. Achievement of viral control is associated with an increase in CXCR3(high) expressing CD8+ cells during treatment.

The role of chemokines as inflammatory mediators in chronic hepatitis C virus infection

Hepatitis C virus (HCV) is a leading cause of chronic liver disease that can progress to cirrhosis and/or hepatocellular carcinoma. Intrahepatic inflammation and liver cell injury are defining features of chronic HCV infection. Chemokines, chemotactic cytokines that attract leucocytes to inflammatory sites, may be important in the development of intrahepatic inflammation. As T-helper (Th)1 inflammatory cells, characterized by interferon (IFN)-gamma and interleukin (IL)-2 secretion, predominate in the liver during chronic HCV infection, chemokines that attract these cells might be particularly important in disease progression. In this review, we focus on the role of Th1 chemokines, which are all members of the CXC or CC subfamilies. Among the CXC chemokines, the non-ELR group comprised of IFN-gamma-inducible protein 10 (IP-10), monokine induced by IFN-gamma (Mig) and IFN-inducible T-cell-alpha chemoattractant (I-TAC), attract Th1 cells through the interaction with their receptor, CXCR3. Among the CC subfamily, Th1-associated chemokines include regulated upon activation, normal T-cell expressed and secreted (RANTES) and macrophage inflammatory proteins (MIP)1alpha and beta. These chemokines attract cells through an interaction with their receptor, CCR5. While peripheral blood and intrahepatic levels of all of these chemokines are elevated in chronic hepatitis C patients, only select chemokines have been found to be correlated with hepatic inflammation. Among the six chemokines, IP-10 has uniquely been shown to have prognostic utility as a marker of treatment outcome. In the future, chemokines might be used to monitor the natural course and progression of HCV-associated liver disease, to identify patients with a high likelihood of achieving a therapeutic response, and they may even have potential as therapeutic targets.

Lack of response to exogenous interferon-alpha in the liver of chimpanzees chronically infected with hepatitis C virus

The mechanism of the interferon-alpha (IFNalpha)-induced antiviral response is not completely understood. We recently examined the transcriptional response to IFNalpha in uninfected chimpanzees. The transcriptional response to IFNalpha in the liver and peripheral blood mononuclear cells (PBMCs) was rapidly induced but was also rapidly down-regulated, with most interferon-alpha-stimulated genes (ISGs) returning to the baseline within 24 hours. We have extended these observations to include chimpanzees chronically infected with hepatitis C virus (HCV). Remarkably, using total genome microarray analysis, we observed almost no induction of ISG transcripts in the livers of chronically infected animals following IFNalpha dosing, whereas the response in PBMCs was similar to that in uninfected animals. In agreement with this finding, no decrease in the viral load occurred with up to 12 weeks of pegylated IFNalpha therapy. The block in the response to exogenous IFNalpha appeared to be HCV-specific because the response in a hepatitis B virus-infected animal was similar to that of uninfected animals. The lack of a response to exogenous IFNalpha may be due to an already maximally induced ISG response because chronically HCV-infected chimpanzees already have a highly up-regulated hepatic ISG response. Alternatively, negative regulation may block the response to exogenous IFNalpha, yet it does not prevent the continued response to endogenous ISG stimuli. The IFNalpha response in chronically HCV-infected chimpanzees may be mechanistically similar to the null response in the human population.

CONCLUSION

In chimpanzees infected with HCV, the highly elevated hepatic ISG expression may prevent the further induction of ISGs and antiviral efficacy following an IFNalpha treatment.

Interferon gamma-inducible protein 10: a predictive marker of successful treatment response in hepatitis C virus/HIV-coinfected patients

BACKGROUND

Elevated pretreatment interferon (IFN) gamma-inducible protein 10 (IP-10/CXCL10) levels are a marker of treatment nonresponse in hepatitis C virus (HCV)-monoinfected patients. We undertook this study to determine if IP-10 is a marker of treatment outcome in HCV/HIV-coinfected patients.

METHODS

Nineteen HCV/HIV-coinfected patients were treated with weight-based pegylated (PEG) IFNalpha-2b (1.5 microg/kg) once weekly plus weight-based ribavirin (1000 or 1200 mg) daily for up to 48 weeks. Plasma IP-10, monokine induced by IFNgamma/CXCL9 (Mig), and IFN-inducible T-cell alpha-chemoattractant/CXCL11 (I-TAC) levels were measured by enzyme-linked immunosorbent assay on samples obtained frequently during the first 3 PEG-IFN doses and throughout treatment.

RESULTS

Median pretreatment plasma IP-10 (interquartile range [IQR]) levels were significantly lower in virological responders (n=6) at 217 (IQR: 181-301) pg/mL compared with nonresponders (n=13) at 900 (IQR: 628-2048) pg/mL (P=0.002), whereas pretreatment Mig and I-TAC levels did not differ significantly. Plasma IP-10 levels of 400 pg/mL before treatment and on days 7 and 14 could be used to identify likely coinfected PEG-IFN/ribavirin nonresponders. PEG-IFN-induced elevations in IP-10 were greater in virological responders than in nonresponders (approximately 10-fold vs. approximately 4-fold) after the first PEG-IFN dose.

CONCLUSIONS

IP-10 may be a biomarker of HCV treatment outcome in difficult-to-treat HCV/HIV-coinfected patients.

Role of chemokines in endocrine autoimmune diseases

Chemokines are a group of peptides of low molecular weight that induce the chemotaxis of different leukocyte subtypes. The major function of chemokines is the recruitment of leukocytes to inflammation sites, but they also play a role in tumoral growth, angiogenesis, and organ sclerosis. In the last few years, experimental evidence accumulated supporting the concept that interferon-gamma (IFN-gamma) inducible chemokines (CXCL9, CXCL10, and CXCL11) and their receptor, CXCR3, play an important role in the initial stage of autoimmune disorders involving endocrine glands. The fact that, after IFN-gamma stimulation, endocrine epithelial cells secrete CXCL10, which in turn recruits type 1 T helper lymphocytes expressing CXCR3 and secreting IFN-gamma, thus perpetuating autoimmune inflammation, strongly supports the concept that chemokines play an important role in endocrine autoimmunity. This article reviews the recent literature including basic science, animal models, and clinical studies, regarding the role of these chemokines in autoimmune endocrine diseases. The potential clinical applications of assaying the serum levels of CXCL10 and the value of such measurements are reviewed. Clinical studies addressing the issue of a role for serum CXCL10 measurement in Graves' disease, Graves' ophthalmopathy, chronic autoimmune thyroiditis, type 1 diabetes mellitus, and Addison's disease have been considered. The principal aim was to propose that chemokines, and in particular CXCL10, should no longer be considered as belonging exclusively to basic science, but rather should be used for providing new insights in the clinical management of patients with endocrine autoimmune diseases.

Chemokines in hepatitis C virus infection: Pathogenesis, prognosis and therapeutics

Hepatitis C virus infection and its associated liver inflammatory disease is a major global health problem affecting over 170 million people worldwide. Following viral infection, multiple pro-inflammatory mediators contribute to recruitment of immune cells to the liver and to the generation of an anti-viral immune response. However, when this vigorous immune response fails to eliminate the virus, chronic infection is established. This in turn, results in an ongoing process of inflammation, regeneration and fibrosis that in many cases leads to the development of cirrhosis and of hepatocellular carcinoma. Multiple recent publications mark chemokines and their receptors as key players in leukocyte recirculation through the inflamed liver. Furthermore, chemokines may also be involved in liver regeneration, fibrosis, and in malignant transformation, which is induced by the persistence of inflammation. Accumulating data indicates that distinct chemokines and chemokine receptors may be associated with different stages of the chronic hepatitis C virus infection-associated liver disease. Multiple small molecules and peptide antagonizing chemokines and their receptors are in advanced phase 3 and phase 2 clinical trials. In the near future, such drugs are expected to enter clinical use raising the question whether they may be applicable for the treatment of chronic viral infection-associated liver disease. In this review, recent advances in understanding the role of chemokines and their receptors in the pathogenesis of chronic viral infection-associated liver disease are presented. Furthermore, the clinical implications of these novel findings, which mark chemokines as prognostic markers and therapeutic targets for immune-modulation during chronic liver viral infection, are documented.

CCL2-2518 A/G and CCR2 190 A/G do not influence the outcome of hepatitis C virus infection in the Spanish population

AIM: To assess whether CCL2 or interactions between this chemokine and its receptor (CCR2) are associated with outcomes of chronic hepatitis C and with responses to antiviral therapy.

METHODS: Two hundred and eighty-four patients with chronic hepatitis C and 193 non-infected matched controls were included in this study. Patients were categorized according to their Scheuer score of hepatic fibrosis as F0-F2 (n = 202) or F3-F4 (n = 82) and according to their response to anti-Hepatitis C virus (HCV) therapy as sustained response (SR, n = 101) or non-sustained response (NSR, n = 98). Genotyping of the -2518 (A/G) CCL2 was performed using PCR-RFLP, genotyping of the 190 (A/G) CCR2 using a PCR-ARMS system, and genotyping of the rs3138042 (G/A) CCR2 using Taqman probes.

RESULTS: Univariate analyses identified 4 parameters (infection duration time, viral genotype, gender and AST levels) that tended to influence fibrosis and 7 parameters (CCL2G, CCL2ACCR2A, viremia levels, fibrosis stage, viral genotype, infection duration time and AST levels) that significantly influenced or tended to influence response to treatment. Multivariate analysis identified gender and AST levels as parameters that independently influenced fibrosis stage and viral genotype and infection duration time were the two parameters that independently influenced response to treatment.

CONCLUSION: Our results indicate that the mutations studied in the gene pair CCL2/CCR2 do not play a major role in the outcome and response to treatment for HCV infection in the Spanish population.

Flying Under the Radar: The Immunobiology of Hepatitis C

The hepatitis C virus (HCV) is a remarkably successful pathogen, establishing persistent infection in more than two-thirds of those who contract it. Its success is related to its abilities to blunt innate antiviral pathways and to evade adaptive immune responses. These two themes may be related. We propose that HCV takes advantage of the impaired innate response to delay the organization of an effective adaptive immune attack. The tolerogenic liver environment may provide cover, prolonging this delay. HCV's error-prone replication strategy permits rapid evolution under immune pressure. Persistent high levels of viral antigens may contribute to immune exhaustion. Finally, the virus may benefit from the efficient enlistment of memory T and B cells in the pursuit of a moving target.

Serum levels of anti-NS4a and anti-NS5a predict treatment response of patients with chronic hepatitis C

In order to understand better the clinical significance and prognostic value of antibody responses to HCV proteins and in search for parameters that may allow the early identification of non-sustained responders to therapy, antibody levels were measured against NS3, NS4a and NS5a at baseline in the serum of 120 patients chronically infected with HCV of genotype 1 that were classified as sustained responders, relapsers, or non-responders to therapy. The capacity of these antibody tests to predict therapy-outcome was evaluated. While no differences were observed in the anti-NS3 responses in these different response groups, anti-NS4a and anti-NS5a antibodies were observed more frequently and at higher titres in sustained responders versus non-responders or non-sustained responders (=non-responders + relapsers). Based on this observation, a combination of test results consisting of 'the absence of NS4a (AA 1687-1718) antibody at baseline and the presence of HCV-RNA exceeding 10(5) IU/ml after 1 week of treatment' was identified which predicts non-sustained response to treatment with 100% certainty. Replacing the HCV-RNA decision limit by a HCV-core antigen level of >15 pg/ml resulted in the same predictive value. The proposed algorithm also holds for patients treated with peg-interferon and ribavirin. In conclusion, in patients with chronic HCV infection, the decision to continue or stop treatment can be made after 1 week of treatment with (peg)-interferon alpha and ribavirin.

IP-10 predicts viral response and therapeutic outcome in difficult-to-treat patients with HCV genotype 1 infection

Plasma from 173 patients with HCV genotype 1 infection was analyzed for IP-10 levels prior to treatment with pegylated interferon-alpha-2a and ribavirin. Significantly lower IP-10 levels were observed in patients achieving a rapid viral response (RVR) (P < .0001), even in those with body mass index (BMI) > or = 25 kg/m2 (P = .004) and with baseline viral load > or = 2 million IU/mL (P = .001). Similarly, significantly lower IP-10 levels were observed in patients obtaining a sustained viral response (SVR) (P = .0002), including those having higher BMI (P < .05), higher viral load (P = .0005), and both higher BMI and viral load (P < .03). In multivariate logistic regression analyses, a low IP-10 value was independently predictive of both RVR and SVR. A baseline cutoff IP-10 value of 600 pg/mL yielded a negative predictive value (NPV) of 79% (19/24) for all genotype 1-infected patients, which was comparable with that observed using a reduction in HCV-RNA by at least 2 logs after 12 weeks of therapy (NPV 86%; 19/22); by combining the two, 30 of 38 patients (NPV 79%) potentially could have been spared unnecessary therapy. In patients having both higher BMI and viral load, cut-off levels of 150 and 600 pg/mL yielded a positive predictive value (PPV) of 71% and NPV of 100%, respectively. In conclusion, pretreatment IP-10 levels predict RVR and SVR in patients infected with HCV genotype 1, even in those with higher BMI and viral load. A substantial proportion of the latter patients may achieve SVR in spite of unfavorable baseline characteristics if their pretreatment IP-10 level is low. Thus, pretreatment IP-10 analysis may prove helpful in decision-making regarding pharmaceutical intervention.

Fas ligand is responsible for CXCR3 chemokine induction in CD4+ T cell-dependent liver damage

Immune-mediated hepatic damage has been demonstrated in the pathogenesis of hepatitis C virus (HCV) and other hepatotrophic infections. Fas/Fas ligand (FasL) interaction plays a critical role in immune-mediated hepatic damage. To understand the molecular mechanism(s) of FasL-mediated liver inflammation, we examined the effect of CD4(+) T cells expressing high levels of FasL on the initiation of hepatic damage through analysis of chemokine and chemokine receptor expression in HCV core x TCR (DO11.10) double-transgenic mice. In vivo antigenic stimulation triggers a marked influx of core-expressing Ag-specific CD4(+) T cells into the liver of the immunized core(+) TCR mice but not their core(-) TCR littermates. Strikingly, the inflammatory process in the liver of core(+) TCR mice was accompanied by a dramatic increase in IFN-inducible protein 10 and monokine induced by IFN-gamma production. The intrahepatic lymphocytes were primarily CXCR3-positive and anti-CXCR3 Ab treatment abrogates migration of CXCR3(+) lymphocytes into the liver and hepatic damage. Importantly, the blockade of Fas/FasL interaction reduces the expression of IFN-inducible protein 10 and monokine induced by IFN-gamma and cellular infiltration into the liver. These findings suggest that activated CD4(+) T cells with elevated FasL expression are involved in promoting liver inflammation and hepatic damage through the induction of chemokines.

Activation of naïve B lymphocytes via CD81, a pathogenetic mechanism for hepatitis C virus-associated B lymphocyte disorders

Infection with hepatitis C virus (HCV), a leading cause of chronic liver diseases, can associate with B lymphocyte proliferative disorders, such as mixed cryoglobulinemia and non-Hodgkin lymphoma. The major envelope protein of HCV (HCV-E2) binds, with high affinity CD81, a tetraspanin expressed on several cell types. Here, we show that engagement of CD81 on human B cells by a combination of HCV-E2 and an anti-CD81 mAb triggers the JNK pathway and leads to the preferential proliferation of the naïve (CD27-) B cell subset. In parallel, we have found that B lymphocytes from the great majority of chronic hepatitis C patients are activated and that naïve cells display a higher level of activation markers than memory (CD27+) B lymphocytes. Moreover, eradication of HCV infection by IFN therapy is associated with normalization of the activation-markers expression. We propose that CD81-mediated activation of B cells in vitro recapitulates the effects of HCV binding to B cell CD81 in vivo and that polyclonal proliferation of naïve B lymphocytes is a key initiating factor for the development of the HCV-associated B lymphocyte disorders.