Autoimmunity and hepatitis C

Hepatic Involvement in Aicardi-Goutières Syndrome

Aicardi-Goutières syndrome (AGS) is a monogenic type-I interferonopathy that results in neurologic injury. The systemic impact of sustained interferon activation is less well characterized. Liver inflammation is known to be associated with the neonatal form of AGS, but the incidence of AGS-related hepatitis across lifespan is unknown.We compared natural history data including liver enzyme levels with markers of inflammation, (liver-specific autoantibodies and interferon signaling gene expression[ISG] scores). Liver enzymes were classified as normal or elevated by the fold increase over the upper limit of normal (ULN). The highest increases were designated as hepatitis, defined as aspartate-aminotransferase or alanine-aminotransferase threefold ULN, or gamma-glutamyl transferase 2.5-fold ULN. A larger cohort was used to further characterize the longitudinal incidence of liver abnormalities and the association with age and genotype.Across the AGS cohort (n = 102), elevated liver enzymes were identified in 76 individuals (74.5%) with abnormalities at a level consistent with hepatitis in 29 individuals (28.4%). SAMHD1 mutations were less likely to be associated with hepatitis (log-rank test; p = 0.011). Hepatitis was associated with early-onset disease and microcephaly (log-rank test; microcephaly p = 0.0401, age onset p = 0.0355). While most subjects (n = 20/33) were found to have liver-specific autoantibodies, there was no association between the presence of autoantibodies or ISG scores with hepatitis-level enzyme elevations.In conclusion, all genotypes of AGS are associated with transient elevations of liver enzymes and the presence of liver-associated autoantibodies. This adds to our growing understanding of the systemic pathology AGS.

Assessment of the Prevalence of Non-Organ-Specific Autoantibodies in Egyptian Patients with HCV

The relation between non-organ specific autoantibodies (NOSA) and hepatitis C virus (HCV) infection has been investigated within different communities resulting in different prevalence rates and patterns. The purpose of this study was to investigate the prevalence of some NOSA such as RF-IgG, ANA, ASMA, and LKM-1 in Egyptian patients with HCV group as compared with Egyptian healthy controls group. A total of 186 HCV positive serum samples in addition to 81 samples from healthy control were screened for the presence of some common autoantibodies (RF-IgG, ANA, ASMA, and LKM-1) using ELISA technique for ANA, ASMA, and LK-1 while RF-IgG was assayed by latex agglutination technique. The presence of these autoantibodies was tested in relation to some demographic variables and viral titers. Associations were assessed using logistic regression analysis adjusted for potential confounders. Among patients, 100 (53.7%) of 186 and 6 (7.4%) of 81 healthy control group were positive for at least one autoantibody. Furthermore, 2 patients (1%) were positive for three autoantibodies, whereas 22 patients (11.7%) were positive for 2 autoantibodies. The most prevalent autoantibody in anti-HCV-positive group was RF-IgG (87, 46.7%) followed by ASMA (26, 14%). The frequency of autoantibodies was bit higher in women as compared to men. Taken together, this study reports a non-significant difference in prevalence of NOSA between patients with HCV infection and healthy individuals except for ASMA. Likewise, no significant difference was found in prevalence of such autoantibodies when correlated with some demographic variables.

Thioacetamide-induced liver damage and thrombocytopenia is associated with induction of antiplatelet autoantibody in mice

Thrombocytopenia is usually associated with liver injury, elevated plasma aspartate aminotransferase and alanine aminotransferase levels, and high antiplatelet immunoglobulin (Ig) titers, although the mechanism behind these effects remains elusive. Deciphering the mechanism behind acute liver disease–associated thrombocytopenia may help solve difficulties in routine patient care, such as liver biopsy, antiviral therapy, and surgery. To determine whether liver damage is sufficient per se to elicit thrombocytopenia, thioacetamide (TAA)-induced hepatitis rodent models were employed. The analysis results indicated that TAA treatment transiently induced an elevation of antiplatelet antibody titer in both rats and mice. B-cell-deficient (BCD) mice, which have loss of antibody expression, exhibited markedly less thrombocytopenia and liver damage than wild-type controls. Because TAA still induces liver damage in BCD mice, this suggests that antiplatelet Ig is one of the pathogenic factors, which play exacerbating role in the acute phase of TAA-induced hepatitis. TNF-α was differentially regulated in wild-type versus BCD mice during TAA treatment, and anti-TNF treatment drastically ameliorated antiplatelet Ig induction, thrombocytopenia, and liver injury, suggesting that the TNF pathway plays a critical role in the disease progression.

Association of diabetes mellitus with hepatitis B and hepatitis C virus infection: evidence from an epidemiological study

Objective

To study the association between glucose metabolism disorders and hepatotropic virus infection.

Methods

A cross-sectional analysis was performed using data from the REACTION study (Risk Evaluation of Cancers in Chinese Diabetic Individuals: A Longitudinal Study). Outcomes of the analysis were test results of kidney function, liver function, lipid metabolism, and the prevalence of hepatitis B virus (HBV) infection and potential hepatitis C virus (HCV) infection (positive hepatitis C virus antibody) among individuals with and without diabetes mellitus (DM) or pre-diabetes mellitus (pre-DM).

Results

Of the 10,080 patients who participated in the study, 7665 eligible subjects were included in the analysis. There was no significant difference in the prevalence of HBV infection between DM and normal subjects, pre-DM and normal subjects, and DM or pre-DM and normal subjects (p-values of 0.9180, 0.8154, and 0.6448, respectively). There was also no significant difference in the prevalence of potential HCV infection between DM and normal subjects, pre-DM and normal subjects, and DM or pre-DM and normal subjects (p-values of 0.1190, 0.0591, and 0.5591, respectively). Lipid metabolism showed a significant difference between DM or pre-DM subjects and normal subjects (p-values were less than 0.0221 in all cases). Multiple logistic regression analysis revealed hypertension as the leading significant variable associated with DM, pre-DM, and both. Other significant factors included gender, body mass index, age, and alanine aminotransferase.

Conclusion

No significant association was detected between DM or pre-DM and HBV or potential HCV infection. Significant association was detected between lipid metabolism disorders and DM, but this association was absent in pre-DM patients when adjusting for other factors.

Molecular Mechanisms Involved in HCC Recurrence after Direct-Acting Antiviral Therapy

Chronic hepatitis C is associated with a high risk of developing hepatocellular carcinoma (HCC) because of a direct effect of the Hepatitis C Virus (HCV) proteins and an indirect oncogenic effect of chronic inflammation and impaired immune response. The treatment of chronic hepatitis C markedly reduces all-cause mortality; in fact, interferon-based treatment has shown a reduction of HCC incidence of more than 70%. The recent introduction of the highly effective direct-acting antivirals (DAAs) has completely changed the scenario of chronic hepatitis C (CHC) with rates of HCV cure over 90%. However, an unexpectedly high incidence of HCC recurrence was observed in patients after DAA treatment (27% versus 0.4–2% in patients who received interferon treatment). The mechanism that underlies the high rate of tumor relapse is currently unknown and is one of the main issues in hepatology. We reviewed the possible mechanisms involved in HCC recurrence after DAA treatment.

Pathogens and autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe form of hepatitis resulting in the autoimmune-mediated destruction of the liver parenchyma. Whereas many of the immunopathogenic events have been elucidated and some of the drivers of the disease have been identified, little is known about the aetiology of the disease. There are certain risk factors, such as particular human leucocyte antigen (HLA) haplotypes, that enhance the susceptibility for AIH or influence the severity of the disease. However, as for many other autoimmune diseases, the mere presence of such risk factors does not warrant the occurrence of the disease. Not all individuals carrying risk factors develop AIH, and not all patients with AIH are carriers of high-risk alleles. Thus, additional environmental factors need to be considered as triggers for AIH. Environmental factors include diet, sunlight exposure, stress, medication and hygiene, as well as pathogen infections and vaccinations. This review discusses if pathogens should be considered as triggers for the initiation and/or propagation of AIH.

Animal models of autoimmune hepatitis

Many animal models for autoimmune hepatitis (AIH) have been described in the past. Most models had to deal with the relative immunosuppressive environment of the liver. Therefore, some models used a combination of several triggering factors often on a susceptible background to generate an aggressive immune response that targets the liver. In addition, in order to be able to track the immune response the models used specific model autoantigens as targets that are either not present or have not been identified as a natural autoantigen in AIH patients. Thereby the feasibility of such models is somewhat questionable. Although many historic approaches included challenges of experimental animals with liver homogenates it was only in the last decade that natural occurring liver autoantigens have been used in animal models. This article reflects on the requirements for breaking liver tolerance and on how an ideal experimental model for AIH would look like. In addition, it discusses historic as well as recent animal models in the context of feasibility of induction, similarity of the clinical outcome to human AIH, and gain of knowledge for possible future therapies.

The Complement System and C1q in Chronic Hepatitis C Virus Infection and Mixed Cryoglobulinemia

The complement system bridges innate and adaptive immunity against microbial infections, with viral infection being a major trigger. Activation of the classical, alternative, and lectin pathways have been reported in chronic hepatitis C virus (HCV) infection and/or cryoglobulinemia. HCV infection leads to dysregulation of complement-mediated immune responses. Clinical and experimental evidence support involvement of complement in intra- and extrahepatic manifestations of HCV infection, such as liver fibrosis and type II cryoglobulinemia. In this review, we summarize studies that have investigated the interplay between HCV and the complement system to establish chronic infection and autoimmunity, as well as the association between HCV pathogenesis and abnormal complement profiles. Several unanswered questions are highlighted which suggest additional informative lines of investigation.

Autoantibodies in Autoimmune Hepatitis: Can Epitopes Tell Us about the Etiology of the Disease?

Autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are serious autoimmune liver diseases that are characterized by a progressive destruction of the liver parenchyma and/or the hepatic bile ducts and the development of chronic fibrosis. Left untreated autoimmune liver diseases are often life-threatening, and patients require a liver transplantation to survive. Thus, an early and reliable diagnosis is paramount for the initiation of a proper therapy with immunosuppressive and/or anticholelithic drugs. Besides the analysis of liver biopsies and serum markers indicating liver damage, the screening for specific autoantibodies is an indispensable tool for the diagnosis of autoimmune liver diseases. Such liver autoantigen-specific antibodies might be involved in the disease pathogenesis, and their epitope specificity may give some insight into the etiology of the disease. Here, we will mainly focus on the generation and specificity of autoantibodies in AIH patients. In addition, we will review data from animal models that aim toward a better understanding of the origins and pathogenicity of such autoantibodies.

The prevalence of autoantibody and its relationship with genotypes of hepatitis C virus in patients with chronic hepatitis C virus infection

The prevalence of autoantibody in the patients with chronic hepatitis C infection, and the relationship between the autoantibodies and HCV genotypes were investigated in this study. One hundred and eight anti-HCV positive and 86 anti-HCV negative patients were included in the study. Anti-HCV were studied by enzyme immunassay (EIA). HCV RNA was determined by real time polymerase chain reaction (PCR) and HCV genotypes were determined by a reverse-line blot hybridization. Anti-nuclear antibodies (ANA), anti-smooth muscle antibodies (ASMA), Anti-mitochondrial antibodies (AMA), liver kidney microsomal antibodies (LKM) were detected by indirect immunofluorescence assay. Among patients, 13 (12.03%) of 108 were positive for at least one autoantibody. The positivity was not observed in control group. The most prevalent autoantibody in anti-HCV positive group was ANA. ANA was positive in six HCV patients with genotype 1. In HCV patients with genotype 1, the frequencies of ANA, ASMA, AMA and LKM1 were six, two, three and one, respectively. In HCV patients with genotype 2, ANA was positive one patient and ASMA, AMA and LKM1 were not detected in HCV patients with genotype 2. In conclusion, the autoantibodies in patients with chronic hepatitis C in the study were low as compared to those reported in previous studies.

Useful properties of undifferentiated mesenchymal stromal cells and adipose tissue as the source in liver-regenerative therapy studied in an animal model of severe acute fulminant hepatitis

BACKGROUND AIMS

End-stage liver diseases frequently require liver transplantation. Cell therapy could be an alternative. This study aimed to analyze whether undifferentiated mesenchymal stromal cells (U-MSCs) or MSC-derived hepatocyte-like cells (DHLCs) from adipose tissue (AT), umbilical cord blood (UCB) and bone marrow (BM) would better restore damaged liver.

METHODS

AT was obtained from lipo-aspiration, UCB from an Umbilical Cord Blood Bank and BM from a BM Transplantation Unit. AT (collagenase digestion), UCB and BM (Ficoll gradient) were cultured (Dulbecco's modified Eagle's medium, low glucose, FBS) for 3 days. Detached adherent cells, at passage 4, were characterized as MSCs. Genetic stability was investigated by means of telomerase enzyme activity and karyotype. Hepatocyte differentiation protocol was performed with the use of Dulbecco's modified Eagle's medium, hepatocyte growth factor, basic fibroblast growth factor and nicotinamide (7 days); maturation medium (oncostatin, dexamethasone, insulin, transferrin and selenium) was added at 36 days. Hepatogenesis analyses were performed by use of morphology and albumin, AF, tyrosine-aminotransferase and glutamine synthetase gene expression and quantitative reverse transcription-polymerase chain reaction on days 9, 18, 25 and 36. Functionality was assessed through glycogen storage detection, indocyanine green absorption and transplantation procedure. U-MSCs and DHLCs were injected 48 h after induced fulminant hepatitis (intraperitoneal injection of carbon tetrachloride) in SCID/BALB-c mice. Histopathologic analyses were performed on days 7 and 15. Human origin included albumin and CK19 human markers.

RESULTS

All MSCs differentiated into functional hepatocyte-like cells, stored glycogen and absorbed indocyanine green. AT-MSC DHLC gene expression was more consistent with a normal hepatogenic-differentiation profile. UCB-MSCs expanded weakly, impairing their use for the transplantation procedure. AT and BM U-MSCs and DHLCs regenerated liver injury equally. Regenerated hepatocytes exhibited human origin.

CONCLUSIONS

AT might be the source and U-MSCS the stem cells useful for liver-regenerative therapy.

Pathogen infection as a possible cause for autoimmune hepatitis

Autoimmune disorders afflicting the liver comprise the bona fide autoimmune diseases, primary biliary cirrhosis, primary sclerosing cholangitis, and autoimmune hepatitis as well as drug-induced autoimmune-like diseases, such as halothane hepatitis. Whereas drug-induced forms of acute or chronic hepatitis often have a clear triggering factor, the etiology of classical autoimmune liver diseases is only poorly understood. Besides a genetic component present in disease susceptible individuals, environmental triggering factors are likely to play a role in the initiation and/or propagation of the disease. In this article, we will review on current evidence obtained from epidemiological associations, case studies, and findings in animal models for pathogens, to be involved in the etiology of autoimmune liver disease with a special focus on autoimmune hepatitis.

Autoimmunity and the gut

Autoimmune diseases have increased dramatically worldwide since World War II. This is coincidental with the increased production and use of chemicals both in industrial countries and agriculture, as well as the ease of travel from region to region and continent to continent, making the transfer of a pathogen or pathogens from one part of the world to another much easier than ever before. In this review, triggers of autoimmunity are examined, principally environmental. The number of possible environmental triggers is vast and includes chemicals, bacteria, viruses, and molds. Examples of these triggers are given and include the mechanism of action and method by which they bring about autoimmunity.

The role of autoantibodies in autoimmune hepatitis type 2

Antibodies play an important role in autoimmune liver diseases, such as autoimmune hepatitis (AIH). On the one hand, they are essential diagnostic markers to identify not only the presentation of AIH, but also the AIH subtype characterized by the presence of particular antibodies to target autoantigens in the liver. On the other hand, such autoantibodies might be directly involved in the etiology and/or pathogenesis of AIH. This review will reflect on the evidence of how specific autoantibodies influence AIH and will further provide insight into the necessities for generating therapeutic antibodies to treat AIH in the future.

Molecular mimicry rather than identity breaks T-cell tolerance in the CYP2D6 mouse model for human autoimmune hepatitis

In our novel mouse model for autoimmune hepatitis (AIH), wildtype FVB mice infected with an Adenovirus (Ad) expressing the major AIH autoantigen human cytochrome P450 2D6 (hCYP2D6) show persistent histological and immunological features associated with AIH, including the generation of anti-hCYP2D6 antibodies with an epitope specificity identical to LKM-1 autoantibodies in AIH-patients. Since FVB mice do not express hCYP2D6, the immune response was directed against mouse CYP (mCYP) homologues. Additional expression of hCYP2D6 in transgenic mice resulted in amelioration of the liver disease. In the present study we used the CYP2D6 model to assess why tolerance breakdown and induction of autoimmune liver disease is more efficient if the triggering antigen is similar but not identical to the target autoantigen. We found that in contrast to the specificity and magnitude of anti-hCYP2D6 antibody responses, T-cell responses differ profoundly between wildtype and transgenic mice. Detailed T-cell epitope mapping studies show a robust, antigen-specific T-cell reactivity in FVB mice largely directed against one CD4 and three CD8 epitopes, activating a total of approximately 1% CD4 and 10% CD8 T-cells, respectively, while infected hCYP2D6 mice generated almost no hCYP2D6-specific T-cells. The frequency of hCYP2D6-specific T-cells was approximately 3-fold higher in the liver compared with the spleen. Amino acid sequence comparison revealed that the immunodominant epitopes were located in hCYP2D6-segments of intermediate homology between hCYP2D6 and its mCYP homologues. Our data indicate that self/non-self molecular mimicry, rather than molecular identity, is a prerequisite for breaking T-cell tolerance in the liver.

Smooth muscle antibodies and cryoglobulinemia are associated with advanced liver fibrosis in Brazilian hepatitis C virus carriers

Cryoglobulinemia and non-organ-specific-autoantibody are biomarkers of autoimmunity of the chronic infection caused by hepatitis C virus (HCV). In this work, we report the association between the presence of smooth muscle antibodies (SMA) and cryoglobulinemia and chronic liver disease in HCV carriers. Sixty-five untreated HCV patients, 38 women and 27 men were included in this study. Cryoglobulinemia was tested by cryoprecipitation, SMA by indirect fluorescent antibody test, and liver fibrosis and hepatocellular inflammation activity was investigated by histology of liver biopsy using the METAVIR score. The prevalence of SMA in the patients was 33.8% and cryoglobulinemia was demonstrated in 36.9% patients. Cryoglobulinemia and SMA seropositivity was associated with advanced fibrosis (p < 0.05). The presence of SMA and cryoglobulinemia was not associated with hepatocellular inflammation activity, age, carrier gender or HCV genotype. We concluded that liver biopsy should be recommended for HCV carriers that are seropositive for SMA or cryoglobulinemia.

Epitope spreading of the anti-CYP2D6 antibody response in patients with autoimmune hepatitis and in the CYP2D6 mouse model

Autoimmune hepatitis (AIH) is a serious chronic inflammatory disease of the liver with yet unknown etiology and largely uncertain immunopathology. The hallmark of type 2 AIH is the generation of liver kidney microsomal-1 (LKM-1) autoantibodies, which predominantly react to cytochrome P450 2D6 (CYP2D6). The identification of disease initiating factors has been hampered in the past, since antibody epitope mapping was mostly performed using serum samples collected late during disease resulting in the identification of immunodominant epitopes not necessarily representing those involved in disease initiation. In order to identify possible environmental triggers for AIH, we analyzed for the first time the spreading of the anti-CYP2D6 antibody response over a prolonged period of time in AIH patients and in the CYP2D6 mouse model, in which mice infected with Adenovirus-human CYP2D6 (Ad-h2D6) develop antibodies with a similar specificity than AIH patients. Epitope spreading was analyzed in six AIH-2-patients and in the CYP2D6 mouse model using SPOTs membranes containing peptides covering the entire CYP2D6 protein. Despite of a considerable variation, both mice and AIH patients largely focus their humoral immune response on an immunodominant epitope early after infection (mice) or diagnosis (patients). The CYP2D6 mouse model revealed that epitope spreading is initiated at the immunodominant epitope and later expands to neighboring and remote regions. Sequence homologies to human pathogens have been detected for all identified epitopes. Our study demonstrates that epitope spreading does indeed occur during the pathogenesis of AIH and supports the concept of molecular mimicry as a possible initiating mechanism for AIH.

Urticaria and thyroid autoimmunity

BACKGROUND

Chronic urticaria is a common clinical condition whose etiology, in about 75% of cases, is unknown and is therefore called chronic idiopathic urticaria (CIU). A link between CIU and autoimmune thyroid diseases was proposed several decades ago. Here we review this topic.

SUMMARY

Several studies have been performed to determine if and to what degree there is an association between CIU and autoimmune thyroid diseases, particularly autoimmune thyroiditis. Many of these studies were not well controlled, however. Approximately one-fourth of CIU patients have serological evidence of thyroid autoimmunity, suggesting that these two disorders are associated. The mechanisms for the apparent association between CIU and serological evidence of thyroid autoimmunity are not clear. There are no data regarding the correlations between CIU and histological features of autoimmune thyroiditis or hypothyroidism. Despite this, there are anecdotal reports regarding L-thyroxine administration in patients with CIU.

CONCLUSIONS

Screening for thyroid autoimmunity is probably useful in patients with CIU. More solid evidence, based on still lacking well-conducted controlled studies, is desirable to determine if there is a therapeutic role for L-thyroxine treatment in ameliorating the skin manifestations of urticaria.

Conformational anti-cytochrome P4502E1 (CYP2E1) auto-antibodies contribute to necro-inflammatory injury in chronic hepatitis C

Circulating auto-antibodies against cytochrome P4502E1 (CYP2E1) have been observed in a significant fraction of patients with chronic hepatitis C (CHC). This study investigated the clinical significance of these auto-antibodies in relation to their antigen specificity. The presence of anti-CYP2E1 IgG was investigated in 137 consecutive patients with biopsy-proven CHC. Anti-CYP2E1 IgG above control threshold levels was detected in 52 (38%) subjects. By combined immunoprecipitation and western blotting, we observed that among anti-CYP2E1 IgG-positive sera, 23 (44%) were unreactive towards denaturated CYP2E1, indicating a prevalent recognition of conformational CYP2E1 antigens. Conformational anti-CYP2E1 auto-antibodies were unrelated to circulating gamma-globulins, alcohol intake or infection by specific HCV genotypes. The presence of anti-CYP2E1 auto-antibodies was associated with an 11-fold (OR 10.9 95%CI 1.4-86.6 P = 0.008) increased prevalence of necro-inflammatory grading ≥ 4 (Ishack's criteria) and 4-fold (OR 4.0; 95%CI 1.3-11-7: P = 0.014) increased prevalence of fibrosis staging ≥ 2, respectively. Multivariate analysis confirmed conformational anti-CYP2E1 IgG (P = 0.005) and age (P = 0.033) as independent predictors of necro-inflammatory grading ≥ 4. The development of anti-CYP2E1 auto-antibodies targeting conformational CYP2E1 epitopes is associated with more severe liver damage in CHC.

Breaking self-tolerance toward cytochrome P4502E1 (CYP2E1) in chronic hepatitis C: possible role for molecular mimicry

BACKGROUND & AIMS

Circulating auto-antibodies targeting conformational antigens on cytochrome P4502E1 (CYP2E1) are detectable in patients with chronic hepatitis C (CHC) and are associated with more severe necro-inflammation. This study investigated the antigen specificity and the possible origin of these auto-antibodies.

METHODS

CYP2E1 site-directed mutagenesis and molecular simulation were used to characterize the epitope specificity of CHC-associated anti-CYP2E1 auto-antibodies.

RESULTS

Immunoprecipitation experiments using differently mutated human CYP2E1s revealed that conformational anti-CYP2E1 antibodies targeted two epitopes located on the molecule surface in an area between Lys(324)-Glu(346) at J-K'' helices overlapping. Such epitopes were not recognized by the sera targeting linear CYP2E1 antigens. The CYP2E1(324-346) peptide showed good homology with two sequences (NS5b(438-449) and NS5b(456-465)) within the NS5b protein of hepatitis C virus (HCV). Consistently, conformational anti-CYP2E1 IgG bind to GST-conjugated NS5b(438-449) and NS5b(456-465) more efficiently than those recognizing CYP2E1 linear antigens. Competition experiments confirmed the cross-reactivity of conformational anti-CYP2E1 IgG with both NS5b(438-449) and NS5b(456-465). Moreover, mice immunized with GST-conjugated NS5b(438-449) or NS5b(456-465) peptides developed antibodies recognizing human CYP2E1.

CONCLUSIONS

In CHC patients cross-reactivity between CYP2E1 and specific sequences in HCV-NS5b protein can promote the development of auto-antibodies targeting conformational epitopes on the CYP2E1 surface that might contribute to hepatic injury.

The infectious etiology of vasculitis

Infectious agents have been implicated in the etiopathogenesis of various vasculitides via numerous and overlapping mechanisms including direct microbial invasion of endothelial cells, immune complex mediated vessel wall damage and stimulation of autoreactive B and/or T cells through molecular mimicry and superantigens. While the causative role of hepatitis B virus in polyarteritis nodosa and hepatitis C virus in mixed cryoglobulinemia is clearly established, evidence for the association of other infectious agents with vasculitis, including human immunodeficiency virus, parvovirus B19, cytomegalovirus, varicella zoster virus, Staphylococcus aureus, rickettsiaceae, Treponema pallidum and Borrelia burgdorferi, among numerous others, is accumulating. The spectrum of association of infectious agents; bacteria, viruses and parasites, with systemic vasculitides, will be reviewed herewith.

Serum cytokine profile in hepatitis C virus carriers presenting cryoglobulinaemia and non-organ-specific autoantibodies

This work investigated the serum cytokine profile (IL-2, IL-4, IL-5, IL-10, IFN-gamma and BAFF) of hepatitis C virus (HCV) carriers with autoimmunity. Forty-seven HCV carriers and 28 healthy controls were evaluated. Cytokine levels were measured by ELISA. Patients and controls presented similar levels of IL-2, IL-4, IL-5, IL-10, IFN-gamma and BAFF (p>0.05). Cryoglobulinaemic HCV carriers had increased IL-2 (p=0.013), IL-5 (p=0.018) and BAFF (p=0.050). IFN-gamma level was decreased in HCV carriers with rheumatoid factor in comparison with those that were RF-seronegative (p=0.035). Patients with beta2GPI IgA antibodies when were compared with those without this autoantibody, had more serum IL-2 (p=0.009), IL-5 (p=0.018) and BAFF (p=0.039). Interleukin-2 was increased in HCV carriers with positive ANA when they were compared with ANA-seronegative carriers (p=0.044). Interleukins IL-4 and IL-10 were not associated with autoimmunity (P>0.05). In HCV carriers, IL-2 was correlated with IL-5 (p<0.0001) and IFN-gamma (p=0.015), and IL-5 with IFN-gamma (p=0.015). We concluded that the serum profile of cytokines in HCV carriers presenting autoimmune markers may be mainly represented by increased IL-2, IL-5 and BAFF.

Management of autoimmune and cholestatic liver disorders

The management of autoimmune and cholestatic liver disorders is a challenging area of hepatology. Autoimmune and cholestatic liver diseases represent a comparatively small proportion of hepatobiliary disorders, yet their appropriate management is of critical importance for patient survival. In this article, management strategies are discussed, including the indications and expectations of pharmacologic therapy, endoscopic approaches, and the role of liver transplantation.

Antinuclear antibody positivity in patients with chronic hepatitis C: clinically relevant or an epiphenomenon?

BACKGROUND

Serum autoantibodies such as antinuclear antibody (ANA) are frequently detected in patients with chronic hepatitis C virus (HCV) infection, but its relevance is a matter of discussion.

AIM

To assess the association of ANA positivity with clinical and histological features, and with the outcome of antiviral therapy in patients with HCV infection.

METHODS

Baseline samples from patients with hepatitis C treated with interferon and ribavirin were tested for ANA positivity by indirect immunofluorescence.

RESULTS

The mean age was 48.3+/-11.1 years and 56% were men. Among 234 included patients, 22 patients (9.4%) were positive for ANA. These patients showed significantly higher median alanine aminotransferase level (3.52 vs. 2.39 x upper limit of normal, P=0.009) when compared with ANA-negative patients. Fibrosis stage and necroinflammatory grading were not influenced by ANA positivity. Sustained virological response (SVR) rates were similar between ANA-positive and ANA-negative patients (27 vs. 29%, P=0.882). Alanine aminotransferase flares (> or = 1.5-fold the baseline) during treatment were observed in 28 patients (12%), irrespective of the presence of ANA and without any clinical significance.

CONCLUSION

Among HCV patients, ANA positivity seems to represent an immunological epiphenomenon. It neither influences clinical, biochemical, and histological features of chronic hepatitis C nor predicts response to antiviral treatment.

Serum autoantibodies against cytochrome P450 2E1 (CYP2E1) predict severity of necroinflammation of recurrent hepatitis C

We previously reported that autoantibodies against cytochrome P4502E1 (CYP2E1) are frequent in patients with chronic hepatitis C. As autoimmune reactions are increasingly detected after orthotopic liver transplantation (OLT), this study investigates prevalence and significance of anti-CYP2E1 autoantibodies in 46 patients with post-OLT recurrent hepatitis C. IgG against recombinant human CYP2E1 above the control threshold was detected in 19 out 46 (41%) sera collected immediately before OLT and in 15 out 46 (33%) sera collected at the time of the 12 months follow-up liver biopsy. Although anti-CYP2E1 reactivity was not modified by OLT, the patients with persistently elevated anti-CYP2E1 IgG (n = 12; 26%) showed significantly higher prevalence of recurrent hepatitis with severe necroinflammation and fibrosis than those persistently negative or positive only either before or after OLT. Moreover, the probability of developing severe necroinflammation was significantly higher in persistently anti-CYP2E1-positive subjects. Multivariate regression and Cox analysis confirmed that the persistence of anti-CYP2E1 IgG, together with a history of acute cellular rejection and donor age >50 years, was an independent risk factor for developing recurrent hepatitis C with severe necroinflammation. We propose that autoimmune reactions involving CYP2E1 might contribute to hepatic damage in a subgroup of transplanted patients with recurrent hepatitis C.

HCV E2 protein binds directly to thyroid cells and induces IL-8 production: a new mechanism for HCV induced thyroid autoimmunity

HCV infection is well-known to be associated with autoimmune thyroiditis. However, the mechanisms by which HCV triggers thyroiditis are unknown. We hypothesized that HCV envelope proteins could induce thyroidal inflammation directly, thereby triggering thyroiditis by a bystander activation mechanism. To test this hypothesis we examined whether the HCV receptor CD81 was expressed and functional on thyroid cells. We found significant levels of CD81 mRNA by QPCR analysis, as well as CD81 protein by flow cytometric (FACS) analysis. Incubation of thyroid cells with HCV envelope glycoprotein E2 resulted in E2 binding to thyroid cells and activation of IL-8, an important pro-inflammatory cytokine. Intriguingly, thyroid cells incubated with E2 continued to proliferate normally and did not undergo apoptosis, as was reported in hepatocytes. We conclude that: (1) HCV envelope glycoprotein E2 can bind to CD81 receptors which are expressed on thyroid cells and induce a cascade of signaling pathway leading to IL-8 release; and (2) HCV may trigger thyroiditis in genetically susceptible individuals by bystander activation mechanisms.

Autoimmune hepatitis induced by the prolonged hepatitis A virus infection

Hepatitis A virus (HAV) is the most common cause of acute viral hepatitis in the world. Rarely, acute infection may persist for a long time. Autoimmune hepatitis (AIH) may provide anti-HAV IgM positivity detection for a prolonged time. On the other hand, HAV as an infectious agent may also trigger AIH. Here we presented a case which seemed like a simple acute viral hepatitis A infection at the beginning but turned out to be an AIH according to the International Autoimmune Hepatitis Group's system. A 21-year-old female was diagnosed as symptomatic acute HAV infection with anti-HAV IgM positivity and elevated aminotransferase levels. The other viral serological tests were negative. On the 6th, 12th and 18th months of the follow up, her anti-HAV IgM positivity still continued and transaminase levels were also 3 to 7 times high of the upper limit of normal. In addition, antinuclear antibody was positive. However, on the 19th month anti-HAV IgM could be detected as negative. Liver histology was prominent. The patient had a score of 16 according to the International Autoimmune Hepatitis Group's system. She was given prednisolone (10 mg/day) and azathioprine (100 mg/day). The aminotransferase levels were detected within normal ranges at the end of the first month of therapy. She was in remission during follow up for 6 years. In conclusion, prolonged HAV infection and AIH may not only trigger each other but also deteriorate the liver histology. AIH should be investigated in cases of long-lasting HAV infection in order to begin the treatment earlier. On the other hand, AIH patients should also be vaccinated for both HBV and HAV to avoid more severe diseases.

Detection of auto-antibodies against cytochrome P4502E1 (CYP2E1) in chronic hepatitis C

BACKGROUND/AIMS

Chronic hepatitis C (CHC) is often associated with auto-immune reactions. In the light of the role of alcohol in promoting CHC progression, we have investigated the possible presence of auto-reactivity against the ethanol-inducible cytochrome P4502E1 (CYP2E1) in CHC patients with and without alcohol consumption.

METHODS

The IgG reactivity against recombinant human CYP2E1 was evaluated by solid-phase immunoassays in 102 CHC patients with different alcohol consumption and 59 HCV-free controls.

RESULTS

Auto-antibodies against CYP2E1 were significantly (p<0.0001) increased in CHC patients as compared to controls. Anti-CYP2E1 IgG above the 97th percentile in the controls were evident in 41 (40%) CHC patients. Competition experiments revealed that CYP2E1 recognition was not due to the cross-reactivity with CYP2D6. The detection of anti-CYP2E1 IgG was unrelated to alcohol consumption and no difference in gender, age, aminotransferase levels and virus genotype was evident among the patients with or without anti-CYP2E1 auto-antibodies. However, anti-CYP2E1 auto-reactivity was significantly (p=0.025) associated with the severity of periportal/periseptal interface hepatitis. Moreover, confocal microscopy demonstrated that anti-CYP2E1 IgG associated with CHC recognized CYP2E1 exposed on the outer side of hepatocyte plasma membranes.

CONCLUSIONS

HCV infection favours the breaking of self-tolerance against CYP2E1 that might contribute to hepatocyte injury.

[Autoimmune hepatitis in a HIV-HCV co-infected patient: diagnostic ant therapeutic difficulties]

INTRODUCTION

Autoimmune hepatitis (AIH) is a chronic inflammatory hepatic disorder, characterized by hypergammaglobulinemia and autoantibodies. In some cases, AIH can be associated with another liver disease; such as the hepatitis C-AIH overlap syndrome, which diagnosis and treatment may be delicate.

EXEGESE

We report a type 1 AIH case in a HIV-HCV co-infected woman. AIH remission and HCV eradication were obtained with prednisone and interferon plus ribavirine. AIH relapse appeared with corticosteroid withdrawal and a new remission was obtained with immunosuppressive treatment associating prednisone and azathioprine, without opportunistic infection.

CONCLUSION

This case illustrates diagnostic and therapeutic difficulties of hepatitis C-AIH overlap syndromes in an HIV-infected patient. To our knowledge, it is the first AIH case report in a HIV-HCV co-infected patient.

Cigarette smoke-induced emphysema: A role for the B cell?

RATIONALE

Little is known about what drives the inflammatory reaction in the development of chronic obstructive lung disease. B cells have been found.

OBJECTIVE

To study the involvement of B cells in the development of emphysema.

METHODS

The presence of B-cell follicles and their interaction with other cells were investigated in lungs of patients with chronic obstructive pulmonary disease and of smoking mice. B cells were isolated from lymphoid follicles by laser microdissection and analyzed for the presence of immunoglobulin rearrangements and somatic mutations.

MAIN RESULTS

Lymphoid follicles consisting of B cells and follicular dendritic cells with adjacent T cells were demonstrated both in the parenchyma and in bronchial walls of patients with emphysema. A clonal process was observed in all follicles and the presence of ongoing somatic mutations was observed in 75% of the follicles, indicating oligoclonal, antigen-specific proliferation. Similar lymphoid follicles were detected in mice that had developed pulmonary inflammation and progressive alveolar airspace enlargement after smoking. The increase in the number of B-cell follicles was progressive with time and correlated with the increase in mean linear intercept. Specific bacterial or viral nucleic acids could not be detected.

CONCLUSIONS

B-cell follicles with an oligoclonal, antigen-specific reaction were found in men and mice with emphysema. In mice, the development was progressive with time and correlated with the increase in airspace enlargement. We hypothesize that these B cells contribute to the inflammatory process and/or the development and perpetuation of emphysema by producing antibodies against either tobacco smoke residues or extracellular matrix components.

Differentiation of human adipose stromal cells into hepatic lineage in vitro and in vivo

Embryonic stem cells (ES cells), bone marrow-derived mesenchymal stem cells, umbilical cord blood-derived mesenchymal stem cells, and hepatic stem cells in liver have been known as a useful source that can induce to differentiate into hepatocytes. In this study, we examined whether human adipose tissue-derived stromal cells (hADSC) can differentiate into hepatic lineage in vitro. hADSC, that were induced to differentiate into hepatocyte-like cells by the treatment of HGF and OSM, had morphology similar to hepatocytes. Addition of DMSO enhanced differentiation into hepatocytes. RT-PCR and immunocytochemical analysis showed that hADSC express albumin and alpha-fetoprotein during differentiation. Differentiated hADSC showed LDL uptake and production of urea. Additionally, transplanted hADSC to CCl4-injured SCID mouse model were able to be differentiated into hepatocytes and they expressed albumin in vivo. Mesenchymal stem cells isolated from human adipose tissue are immunocompatible and are easily isolated. Therefore, hADSC may become an alternative source to hepatocyte regeneration or liver cell transplantation.

Successful treatment with cyclosporine A of HCV-driven chronic liver disease mimicking autoimmune hepatitis in a patient with common variable immunodeficiency

Common variable immunodeficiency (CVID) is the commonest primary immunodeficiency disease characterized by defective antibody production and various degrees of T cell numbers abnormality or impaired proliferation to mitogens. Clinical features include recurrent bacterial sinopulmonary and gastrointestinal infections. Autoimmunity is very common in CVID, occurring in approximately 25% of the patients particularly with autoimmune thrombocytopenia, hemolytic anemia, inflammatory bowel disease, and rheumatoid arthritis. Persistent antigen stimulation, secondary to a defective eradication of pathogens followed by a compensatory exaggerated chronic inflammatory response, is the primary cause leading to autoimmunity. Here we describe a girl with CVID in whom a chronic liver disease mimicking autoimmune hepatitis developed after hepatitis C virus infection. The immunosuppressive treatment with cyclosporine A proved effective in reversing liver disease.

Is there any relationship between hepatitis C virus and vitiligo?

GOALS AND BACKGROUND

Hepatitis C virus (HCV) is a hepatotropic and lymphotropic virus. This agent can promote development of a panel of autoimmune diseases. The relationship between HCV infection and vitiligo, in which autoimmune mechanisms are believed to play a role is not yet elucidated. In this study we investigated HCV seropositivity in vitiligo patients and compared this with non-vitiligo population.

STUDY

A total of 102 consecutive patients with vitiligo were included in the study (47 male, 55 female, mean age: 36.8 +/- 16.9 years, range: 5-75). Control population was 670 age and sex matched healthy blood donors (406 male, 264 female, mean age: 32.8 +/- 11.3 years, range: 20-58). Third generation enzyme immunoassay was used for serum anti-HCV determination. When positive, qualitative confirmation was performed by HCV-RNA determination using RT-PCR.

RESULTS

Anti-HCV antibody was detected only in 1 patient and confirmed by RT-PCR test. This patient was a 6-year-old girl with a non-segmental form of vitiligo, which is more frequently associated with autoimmune disorders, hence the incidence of HCV seropositivity found as 0.98%. There was no statistically significant difference between this figure and 0.6% prevalence in healthy blood donors.

CONCLUSION

Seroprevalence of HCV in vitiligo patients is not different from that of a control group in Turkey, and HCV infection may not be involved in the pathogenesis of vitiligo despite case reports showing co-existence of these 2 diseases.

Stem cell therapy of the liver--fusion or fiction?

Various stem cell populations have been described in distinct models of liver regeneration. This review provides an overview of these different stem cell populations aimed at unifying diverse views of liver stem cell biology. Embryonic stem cells, hemopoietic stem cells, mesenchymal stem cells, liver-derived hepatic stem cells, bone marrow-derived hepatic stem cells, and mature hepatocytes (as cells with stemlike properties) are considered separately. In so doing, we seek to clarify the nomenclature of putative liver stem cell types. Experiments that address the question of cellular fusion versus transdifferentiation as explanations for observed liver regeneration are highlighted. This review concludes with a series of open questions that should be addressed in the context of clinical liver disease before attempts at human therapeutic interventions.