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

Molecular mimicry between virus and host and its implications for dengue disease pathogenesis

Numerous infectious agents may trigger autoimmunity or even result in autoimmune diseases. Several mechanisms have been proposed for pathogen-triggered autoimmunity including molecular mimicry, cryptic antigens, epitope spreading, bystander activation and polyclonal activation. In the case of dengue virus infection which causes serious public health problems, the mechanisms regarding the pathogenesis of dengue hemorrhagic syndrome are not fully resolved. Our previous studies suggest a mechanism of molecular mimicry in which antibodies directed against dengue virus non-structural protein 1 (NS1) cross-react with human platelets and endothelial cells and cause their damage and dysfunction, which may be related to the clinical features of dengue disease. Several cell surface proteins recognized by patient serum samples and anti-NS1 antibodies have been identified. Based on proteomic studies and sequence analysis, the C-terminal region of dengue virus NS1 shows sequence homology with target proteins. In addition, different regions of dengue virus proteins including core, prM, E and NS1 proteins show sequence homology with different coagulatory molecules. As an example, the amino acid sequence 101-106 of E protein (WGNGCG) shows sequence homology with factors XI, X, IX, VII, II (thrombin), plasminogen and tissue plasminogen activator. Furthermore, single chain variable region against NS1 can interfere with fibrin formation, which leads to prolonged thrombin time. We hypothesize that molecular mimicry between dengue virus proteins and coagulatory molecules may induce cross-reactive autoantibodies that can interfere with coagulation activation. A molecular mimicry pathogenesis for dengue disease which involves cross-reactivity of dengue virus with human endothelial cells, platelets and coagulatory molecules is proposed.

Interleukin-1β, C-x-C motif ligand 10, and interferon-gamma serum levels in mixed cryoglobulinemia with or without autoimmune thyroiditis

The aim of this study was to evaluate serum levels of interleukin-1β (IL-1β), chemokine (C-X-C motif) ligand 10 (CXCL10), and interferon-gamma (IFN-γ) in a series of patients with "mixed cryoglobulinemia and hepatitis C virus chronic infection" (MC + HCV) in the presence or absence of autoimmune thyroiditis (AT) and to relate them to the clinical phenotype of these patients. Serum IL-1β, IFN-γ, and CXCL10 were assayed in 30 patients with MC + HCV without AT, in 30 patients with MC + HCV and AT, and in 30 sex- and age-matched controls. Cryoglobulinemic patients showed significantly higher mean IL-1β and CXCL10 levels than controls (P < 0.01). Moreover, CXCL10 was significantly increased in patients with AT patients with respect to those without AT (P < 0.01). Serum IFN-γ levels were not significantly higher in MC + HCV patients than in controls. In conclusion, our study demonstrates significantly high serum levels of IL-1β in patients with MC + HCV with and without AT compared with healthy controls. Further, significantly high serum levels of CXCL10 in patients with MC + HCV compared with healthy controls were confirmed, overall in the presence of AT. Moreover, a pathophysiological association between high circulating levels of IL-1β and CXCL10 has been suggested. A possible therapeutic role of the anti-IL-1 receptor antagonist (Anakirna) in MC remains to be evaluated.

Extrahepatic manifestations associated with chronic hepatitis C infections in Poland

PURPOSE

To assess the prevalence and predictive factors of extrahepatic manifestation (EM) in patients with chronic hepatitis C (CHC) infection in Poland.

MATERIAL AND METHODS

340 consecutive patients (mean age: 42 years) with untreated CHC were studied between 2000 and 2006. The HCV infection was defined by positive serology and serum HCV RNA. The inflammation grade and fibrosis stage were assessed according to Ishak. Demographic, laboratory and liver biopsy data were collected. The patients with liver cirrhosis, concomitant HBV or HIV infection, autoimmune liver diseases and alcohol abusers were excluded from the analysis.

RESULTS

210 patients with CHC (61.7%) presented at least 1 extrahepatic manifestation, including mixed cryoglobulinemia (37.1%), thrombocytopenia (27.6%), thyroid autoimmunity (16.2%), dermatological disorders (4.1%) and type 2 diabetes (4.1%). Other EM such as the sicca syndrome, nephropathy, polyneuropathy and B-cell lymphoma were observed in single cases. In multivariate analysis lower platelet count was found as a predictive factor of EM in patients with CHC.

CONCLUSIONS

The majority of patients with CHC, living in Poland, have EM, of which cryoglobulinemia, thrombocytopenia, thyroid autoimmunity, dermatological disorders and type 2 diabetes are most common. Through the multivariate analysis the lower platelet predicts extrahepatic manifestations associated with chronic hepatitis C.

Hepatitis C virus and autoimmunity

Hepatitis C virus infection is associated with several extrahepatic manifestations. About 60% of patients infected with HCV develop at least one extrahepatic manifestation. The majority of these diseases seem to be triggered through autoimmune mechanisms, such as autoantibody production, autoreactive T cells and complex autoimmune mechanisms leading to systemic autoimmune disorders. In this review we categorize these diseases into three groups according to the main pathogenetic process involved, in particular B-cell-mediated, T-cell-mediated and complex autoimmune systemic diseases.

Hypothyroidism in Noninterferon Treated-HCV Infected Individuals Is Associated with Abnormalities in the Regulation of Th17 Cells

HCV-Ag-specific TH17 cells secrete IL17, a cytokine involved in autoimmune diseases and regulated by IL10 and TGF-b. 5–12% of patients with chronic HCV infection have hypothyroidism. We evaluated the role of these cytokines in this patients by determining serum concentration of TsH, T3, free T4, IL2, IL10, IL12, IL17, TGF-b, anti-TG, TPO, CCP, GBM, and cardiolipin antibodies in 87 chronically noninterferon treated HCV-infected patients. 20 patients (group A) had elevated TsH values (>5 μUI/ml) whereas the remaining 67 (group B) had normal values. The percentage of anti-TPO, TG, GBM, and cardiolipin antibodies in group A patients (33%, 41%, 5% and 5%, resp.) as well as IL17, IL2 and TGF-b concentrations (25 ± 23 pg/ml, 643 ± 572 pg/ml, and 618 ± 221 pg/ml, resp.) were significantly higher than group B. Abnormal Th17 regulation mediated by IL-2 and low TGF-b concentrations is associated with hypothyroidism in chronically-infected HCV patients.

High circulating levels of N-terminal pro-brain natriuretic peptide and interleukin 6 in patients with mixed cryoglobulinemia

Many patients with mixed cryoglobulinemia and chronic HCV infection experience symptoms, such as dyspnea, which sometimes do not seem to indicate the involvement of the liver but rather the symptoms of heart failure. To our knowledge, there has been no other study evaluating the serum levels of N-terminal pro-brain natriuretic peptide (NTproBNP) and Interleukin 6 (IL-6) in such patients. Serum NTproBNP and IL-6 were assayed in 54 patients with mixed cryoglobulinemia and chronic HCV infection, and in 54 sex- and age-matched controls. Cryoglobulinemic-patients showed significantly higher mean NTproBNP and IL-6 levels than the controls (P = 0.005). By defining a high NTproBNP level as a value higher than 125 pg/ml (the single cut-off point for patients under 75 years of age), 30% of patients with mixed cryoglobulinemia and chronic HCV infection and 7% of controls had high NTproBNP (chi-square; P < 0.003). With a cut-off point of 300 pg/ml (used to rule out heart failure in patients under 75 years of age), 5/49 patients with mixed cryoglobulinemia and chronic HCV infection and 0/54 controls had high NTproBNP (chi-square; P < 0.04). With a cut-off point of 900 pg/ml (used for including heart failure in patients aged between 50 and 75, such as the patients in this study) 3/51 of patients with mixed cryoglobulinemia and chronic HCV infection and 0/54 controls had high NTproBNP (chi-square; P = 0.07). The study revealed high levels of circulating NTproBNP and IL-6 in patients with mixed cryoglobulinemia and chronic HCV infection. The increase in NTproBNP could indicate the presence of a subclinical cardiac dysfunction.

Serum levels of proinflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor alpha in mixed cryoglobulinemia

OBJECTIVE

No single previous study has evaluated serum levels of the proinflammatory cytokines interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor alpha (TNFalpha) in patients with hepatitis C virus-associated mixed cryoglobulinemia (HCV-MC). This study was undertaken to evaluate serum levels of these cytokines in patients with HCV-MC.

METHODS

Serum IL-1beta, IL-6, and TNFalpha were assayed in 43 patients with HCV-MC, in 43 sex- and age-matched patients with chronic HCV without cryoglobulinemia, and in 43 sex- and age-matched controls.

RESULTS

HCV-MC patients showed significantly higher mean IL-1beta, IL-6, and TNFalpha levels than did the controls (P<0.01) or the HCV patients (P<or=0.04). Serum levels of IL-6 and TNFalpha were significantly higher in HCV patients than in controls (P<0.05).

CONCLUSION

Our findings demonstrate elevated serum levels of IL-1beta, IL-6, and TNFalpha in patients with HCV-MC. If the importance of IL-1beta and IL-6 in the pathogenesis of MC is confirmed, these results will open the way for the evaluation of new therapies for MC.

Geo-epidemiology and autoimmunity

Autoimmune disease (AD) affects approximately 3% of the population. This is an enormous number, but ironically the study of autoimmunity has not taken on the significance of many other diseases because so many of the ADs are relatively uncommon. Indeed, despite enormous advances in the diagnosis and the treatment of AD, there is still a paucity of data on the etiological events that lead to the clinical pathology. For most other human diseases, the etiology is addressed and often solved by the use of epidemiology. Epidemiology consists of the study of prevalence of a disease, coupled with analysis of genetic factors and detection of environmental agents. In the context of autoimmune conditions, preclinical epidemiology has recently been favored, as a consequence of the discovery that autoantibody precedes overt disease. The idea of a North-South gradient in the prevalence of ADs, with a reciprocal gradient in that of infectious injuries has proven to be debatable. More importantly, environmentally-induced changes have been shown to modify certain diseases giving rise to the key concept of epigenetics. However, it is clear that major voids exist. Some of these voids were hoped to be solved by the use of genome-wide associations. This, however, has proven very problematic, as the genetic basis of AD is considerably more complicated than once believed. We now base our hopes on next generational sequencing as a brut force undertaking to partially decipher the genetic code that predisposes individuals to AD. This volume is a compilation of papers in Autoimmunity Reviews and the Journal of Autoimmunity and presented as part of the 7th International Congress on Autoimmunity in Ljubljana, Slovenia. It is clearly impossible to present data on the geoepidemiology of all of the AD. Instead, we attempted to generate interest amongst immunologists to generate papers that are thought provoking but also contemporary reviews.

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.

Infectious serologies and autoantibodies in inflammatory bowel disease: insinuations at a true pathogenic role

The aim of this study was to reevaluate the role of infection in inflammatory bowel disease (IBD). Sera from 119 patients with IBD [80 with Crohn's disease (CD); 39 with ulcerative colitis] and 98 healthy controls were assessed using the Bio-Rad BioPlex 2200 for the presence of Toxoplasma gondii, cytomegalovirus, Epstein-Barr virus, Treponema pallidum, and Saccharomyces cerevisiae. Hepatitis B virus, hepatitis C virus (HCV), and anti-Helicobacter pylori antibodies were assessed by ELISA. In addition, sera were tested for a panel of antibodies associated with thrombophilia as well as various autoantibodies. Titers of antibodies toward HCV and T. gondii, and S. cerevisiae were higher in IBD patients than in controls, while the H. pylori autoantibodies were less prevalent among the patient population. Several thrombophilia-associated antibodies were more common in CD patients, and a single patient had a thromboembolic event. Our results show an excess of anti-HCV and anti-T. gondii antibodies among patients with IBD compared to healthy controls. Whereas the former may be the result of immunosuppression from the inflammatory disease itself or from the medications used to treat it, the latter association suggests that T. gondii is involved in the etiopathogenesis of IBD, and especially CD, in humans, as has been shown in the murine model. However, our findings also reiterate the positive association between CD and anti-S. cerevisiae antibodies as well as the negative association with H. pylori infections. These, in turn, lend indirect support to the "hygiene hypothesis" in IBD as well as the newly proposed role of commensal bacteria in the initiation of the disease process.

Incidence and nature of infectious disease in patients treated with anti-TNF agents

Tumor necrosis factor alpha (TNF-alpha) inhibitors offer a targeted therapeutic strategy that contrasts with the nonspecific immunosuppressive agents traditionally used to treat most inflammatory diseases. These biologic agents have had a significant impact in ameliorating the signs and symptoms of inflammatory rheumatoid disease and improving patient function. From the onset of clinical trials, a central concern of cytokine blockade has been a potential increase in susceptibility to infections. Not surprisingly, a variety of infections have been reported in association with the use of TNF-alpha inhibitor agents. In particular, there is evidence suggesting an increased rate of granulomatous infections in patients treated with monoclonal TNF-alpha inhibitors. This review provides the incidence and nature of infections in patients treated with TNF-alpha inhibitor agents and reminds the clinician of the required vigilance in monitoring patients.

Navigating the passage between Charybdis and Scylla: recognizing the achievements of Noel Rose

This special edition of the Journal of Autoimmunity is dedicated to celebrate the enormous contributions of Dr. Noel Rose, a physician-scientist, someone that can be readily anointed as a gifted scientist who laid down the foundation and fundamental concepts of human autoimmunity. Dr. Rose performed a series of landmark studies that extend back more than 50 years and whose work is the cornerstone of the commonly used term "from the bench to the bedside." The studies included not only characterization of a normal immune response but, more importantly, defining the nature of not only the antigen, but also the aberrant response that results in organ, tissue specific reactions and immunopathology. These pioneering studies contributed to the biochemical nature of antigens, dissection of the immune repertoire, the recognition of the importance of genetics and environment, and the distinctions between a normal and an autoimmune response. Hence, this volume has been coined "Navigating the Passage Between Charybdis and Scylla: Recognizing the Achievements of Noel Rose."

High interleukin-6 and tumor necrosis factor-alpha serum levels in hepatitis C infection associated or not with mixed cryoglobulinemia

The objective of this study is to evaluate serum levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-a) in a series of patients with hepatitis C virus (HCV)-related mixed cryoglobulinemia (HCV-MC) and to correlate these parameters with the clinical features of the disease. Serum IL-6 and TNF-a were assayed in 61 patients with HCV-MC, in 61 sex- and age-matched patients with HCV chronic hepatitis without cryoglobulinemia (HCV+), and in 61 sex- and age-matched healthy controls. HCV-MC patients showed significantly higher mean IL-6 levels than controls (p=0.005) or HCV+ patients (p = 0.02). Moreover, IL-6 was increased in cryoglobulinemic patients with active vasculitis, even if the statistical significance was not reached (p=0.056). Serum TNF-a levels were significantly higher in HCV-MC than in HCV+ or in controls (p<0.01). The study demonstrates high IL-6 and TNF-a serum levels in HCV-MC patients; moreover, IL-6 levels tended to be higher in HCV-MC patients in presence of active vasculitis.

Infections and the antiphospholipid syndrome

Currently, the origin of autoimmune diseases is considered to be multifactorial. Genetic predisposition, immune system malfunction or even backfire, hormonal regulation, and environmental factors, i.e. infections, all play important roles in the pathogenesis of autoimmune diseases such as the antiphospholipid syndrome (APS). New drugs and strategies aimed at preventing infections could further improve the outcome of APS and other autoimmune diseases.

Thyroid dysfunction in patients with chronic hepatitis C: virus- or therapy-related?

BACKGROUND AND AIMS

Thyroid dysfunction (TD) represents an extrahepatic manifestation of chronic hepatitis C (CHC). Moreover, the currently approved treatment of CHC is often associated with TD. However, it remains debatable if TD is mainly virus- or treatment-related. The aim of this study was to assess the incidence and features of TD, and to identify its predictors in treated and untreated CHC patients.

METHODS

Ninety-four patients with CHC and normal thyroid function were evaluated long-term for TD: 33 were untreated (control group) and 61 were treated with pegylated interferon alpha (PEG-IFN-alpha) plus ribavirin (treatment group). Mean follow up was 80.1 and 39.4 months, respectively.

RESULTS

All patients in the control group remained euthyroid, while 13 treated patients (21.3%) developed TD (P < 0.001). Eleven of these were diagnosed with hypothyroidism and two with hyperthyroidism, which then converted to hypothyroidism. In the majority of cases (9/13, 69.2%) TD did not reverse after treatment discontinuation and required hormone replacement therapy. Pretreatment virological parameters did not predict TD, according to multiple logistic regression analysis. TD was not associated with total dose of PEG-IFN-alpha or ribavirin, viral kinetics or with virological outcome, but it was linked to development of other therapy-related autoimmune disorders (odds ratio, 8.29).

CONCLUSION

Antiviral therapy of CHC possibly induces de novo or exacerbates pre-existing silent TD. TD does not seem to correlate with any pretreatment virological parameter; it is probably not related to dose or treatment duration, nor linked to viral kinetics or virological outcome. The role of chronic hepatitis C per se in TD remains to be determined.

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.

Prevalence of hepatitis C serum antibody in autoimmune diseases

OBJECTIVE

To evaluate the prevalence of serum antibodies against hepatitis C virus and other infectious agents in a large cohort of well-characterized patients with autoimmune diseases (AID).

METHODS

We utilized 1322 sera from patients with 18 different AID and 236 sera from healthy controls from the same countries and with similar age and sex distribution. All sera were tested for the presence of serum anti-hepatitis C virus (HCV) antibodies as well as antibodies directed at other infectious agents and autoantibodies.

RESULTS

Anti-HCV antibody was detected in 115/1322 (8.7%) of patients with AID and 0.4% of matched healthy controls (P < 0.0001). The prevalence of anti-HCV antibody was significantly higher in 7/18 different AID (i.e. cryoglobulinemia, mixed cryoglobulinemia pemphigus vulgaris, vasculitis, secondary anti-phospholipid syndrome, Hashimoto's thyroiditis, and inflammatory bowel disease) compared to controls. Patients with AID and serum anti-HCV positivity had an increased prevalence of antibodies against hepatitis B virus, Toxoplasma gondii and Cytomegalovirus as opposed to a lower frequency of serum autoantibodies.

CONCLUSIONS

The enhanced prevalence of anti-HCV serum antibodies in AID may suggest a role for HCV in tolerance to breakdown, similarly to its established role in mixed cryoglobulinemia. This immune mediated effect does not rule out the role of other infectious agents.

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.