Hepatitis B virus: something old, something new.
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Adolescent↗
Biomedical subjects
Diego Vergani
Publications and source records attributed to Diego Vergani.
Liver transplantation in children.
Liver transplantation (LT) is now a standard treatment for children with end-stage liver disease with excellent 1- and 5-year survival. This has been achieved through improvement of surgical techniques and anti-rejection treatment and management. The donor pool for children has been extended by the use of cut-down, split, living-related and, recently, non-heart-beating donor and isolated hepatocyte transplantation. Though the majority of transplanted children enjoy an excellent quality of life, there remain a high number of possible complications, including short-term primary non-function, vascular and biliary problems, bowel perforation, severe rejection, infection, hypertension and long-term renal impairment, chronic rejection, de novo autoimmunity, lymphoproliferative disease and cancer, most of which are related to anti-rejection drug toxicity. Hence, the focus of research for paediatric LT should be induction of tolerance, avoiding long-term immunosuppression and its toxicity.
Child↗
Functional study of CD4+CD25+ regulatory T cells in health and autoimmune hepatitis.
Regulatory CD4(+)CD25(+) T cells (Tregs) are defective numerically and functionally in autoimmune hepatitis (AIH). We have investigated and compared the mechanism of action of Tregs in healthy subjects and in AIH patients using Transwell experiments, where Tregs are cultured either in direct contact with or separated from their targets by a semipermeable membrane. We also studied Treg FOXP3 expression and effect on apoptosis. Direct contact is necessary for Tregs to suppress proliferation and IFN-gamma production by CD4(+)CD25(-) and CD8(+) T cells in patients and controls. Moreover, in both, direct contact of Tregs with their targets leads to increased secretion of regulatory cytokines IL-4, IL-10, and TGF-beta, suggesting a mechanism of linked immunosuppression. Tregs/CD4(+)CD25(-) T cell cocultures lead to similar changes in IFN-gamma and IL-10 secretion in patients and controls, whereas increased TGF-beta secretion is significantly lower in patients. In contrast, in patients, Tregs/CD8(+) T cell cocultures lead to a higher increase of IL-4 secretion. In AIH, Treg FOXP3 expression is lower than in normal subjects. Both in patients and controls, FOXP3 expression is present also in CD4(+)CD25(-) T cells, although at a low level and not associated to suppressive function. Both in patients and controls, addition of Tregs does not influence target cell apoptosis, but in AIH, spontaneous apoptosis of CD4(+)CD25(-) T cells is reduced. In conclusion, Tregs act through a direct contact with their targets by modifying the cytokine profile and not inducing apoptosis. Deficient CD4(+)CD25(-) T cell spontaneous apoptosis may contribute to the development of autoimmunity.
Adolescent↗
Reduced monocyte HLA-DR expression: a novel biomarker of disease severity and outcome in acetaminophen-induced acute liver failure.
Acute liver failure (ALF) shares striking similarities with septic shock where a decrease in HLA-DR expression on monocytes is associated with disease severity and predicts outcome. We investigated monocyte HLA-DR expression in ALF in relation to inflammatory mediator levels and clinical outcome. Monocyte HLA-DR expression was determined in 50 patients with acetaminophen-induced ALF (AALF) and 20 non-acetaminophen-induced ALF (NAALF). AALF patients were divided into dead/transplanted (AALF-NS, n = 26) and spontaneous survivors (AALF-S, n = 24). Fifty patients with chronic liver disease (CLD) and 50 healthy volunteers served as controls. Monocyte HLA-DR expression was determined by double-color flow-cytometry with monoclonal antibodies detecting HLA-DR and monocyte specific CD14. Serum levels of interleukin (IL) -4, -6, -10, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma were concomitantly measured by ELISA. Compared to healthy volunteers (75%) and CLD (67%) monocyte HLA-DR percentage expression was lower in AALF (15%, P < .001) and NAALF (22 %, P < .001). Compared to AALF-S, AALF-NS had lower monocyte HLA-DR % (11% vs. 36%, P < .001) and higher levels of IL-4, IL-6, IL-10 and TNF-alpha (P < .001). HLA-DR percentage negatively correlated with INR, blood lactate, pH and levels of encephalopathy (r = -0.8 to -0.5, P < .01), IL-10 (r = -0.8, P < .0001), TNF-alpha (r = -0.4, P = .02). HLA-DR percentage level <or=15% has a 96% sensitivity and 100% specificity and 98% accuracy in predicting poor prognosis. In conclusion, the strong relationship of monocyte HLA-DR expression with indices of disease severity, mediators of inflammation and outcome indicates a key role for this molecule as a biomarker of disease severity and prognosis.
Acetaminophen↗
Combined lamivudine/interferon-alpha treatment in "immunotolerant" children perinatally infected with hepatitis B: a pilot study.
OBJECTIVE: To investigate whether combining the antiviral effect of lamivudine with the immune-boosting action of interferon-alpha (IFN-alpha) is effective in treating hepatitis B virus (HBV) "immunotolerant" children. STUDY DESIGN: Twenty-three children (8 boys; mean age, 10 years) infected during the first year of life (17 Asian, 21 with normal aminotransferase levels, 15 with HBV-DNA >1000 pg/mL by hybridization and all with mild histologic changes) were treated with lamivudine (3 mg/kg) for 8 weeks alone and then lamivudine (3 mg/kg) and IFN-alpha (5 MU/m(2), 3 times weekly) in combination for 10 months. RESULTS: Seventy-eight percent became HBV-DNA negative at the end of treatment, 5 (22%) seroconverted to anti-HBe, 4 (17%) of whom achieved complete viral control, becoming persistently HBsAg negative and anti-HBs positive. None had YMDD mutations. The viral status of the patients has not changed after a median follow-up of 40 months (range, 36 to 48). CONCLUSIONS: This pilot study suggests that lamivudine pretreatment followed by a combination of lamivudine and IFN-alpha can induce complete viral control in HBV immunotolerant children, hitherto considered poor responders.
Adolescent↗
Polyclonal T-cell responses to cytochrome P450IID6 are associated with disease activity in autoimmune hepatitis type 2.
BACKGROUND & AIMS: Autoimmune hepatitis type 2 (AIH-2), a severe juvenile liver disorder of unknown etiology and pathogenesis, is characterized by liver-kidney microsomal antibody type 1 targeting cytochrome P450IID6 (CYP2D6) and is associated to HLA DRB1*07. Although CYP2D6 B-cell reactivity has been extensively characterized, little is known about CYP2D6-specific T-cell responses. The aim of the present study was to characterize anti-CYP2D6 cellular immune responses and their possible pathogenic role in patients with AIH-2. METHODS: We investigated T-cell reactivity against 61 overlapping peptides spanning the full CYP2D6 protein using ex vivo cultures obtained at diagnosis, remission, and relapse. Moreover, CYP2D6-specific T-cell reactivity was investigated in the context of HLA restriction, peptide-binding affinity to HLA DRB1*07, cytokine profile, disease specificity, and clinical course. RESULTS: Proliferative responses to CYP2D6 cluster to 7 antigenic regions in DRB1*07 and to 4 regions in non-DRB1*07 patients. Whereas distinct peptides induce production of interferon gamma, interleukin-4, or interleukin-10, peptides inducing interferon-gamma and proliferation overlap. There is also an overlap between sequences inducing T- and B-cell responses. The breadth (number of epitopes) and intensity (quantity of cytokine produced) of the T-cell response are directly correlated to disease activity (biochemical and histologic markers). CONCLUSIONS: These data imply that the T-cell response to CYP2D6 in AIH-2 is polyclonal, involves multiple effector types targeting different epitopes, and is associated with hepatocyte damage, knowledge that should form the basis for a more refined therapeutic approach.
Adolescent↗
Does cross-reactivity between mycobacterium avium paratuberculosis and human intestinal antigens characterize Crohn's disease?
BACKGROUND & AIMS: Most Crohn's disease (CD) patients show seroreactivity against Mycobacterium avium paratuberculosis (MAP), suggesting a pathogenic role for this organism. Our aim was to seek amino acid similarities between MAP and intestinal proteins that, through molecular mimicry, could serve as targets for cross-reactive immunity in CD. METHODS: Fifty-three peptides comprising 23 sets of MAP/human intestinal peptidyl mimics chosen for maximal homology were constructed and tested for immunologic cross-reactivity by enzyme-linked immunosorbent assay in 50 patients with CD, 50 with ulcerative colitis, and 38 healthy controls. RESULTS: Antibody reactivity was present in only 7 of 23 peptide sets. MAP/self-reactivity in at least 1 of the 7 reactive sets was present in 21 (42%) CD patients but was virtually absent in the controls. Significant double-reactivity was found against MAP glycosyl transferase d (gsd)(230-244)/human gastrointestinal glutathione peroxidase (GPg)(111-125) homologues in 15 of 50 (30%) CD patients; MAP alkylohydroperoxidase C (ahpC)(20-34)/human tumor overexpressed protein (TOG)(637-651) double-reactivity was present in 10 (20%) CD patients, but in none of the controls. Inhibition studies confirmed that simultaneous reactivity to mimics was caused by cross-reactivity. Three-dimensional modeling predicts GPg(111-125) will be exposed in a solvent-accessible surface region of the protein compatible with antibody recognition. Antibody affinity was greater for the MAP mimics than for the self-sequences, suggesting that reactivity to the mycobacterial sequences precedes that against self-sequences. CONCLUSIONS: We describe MAP/self-mimics as targets of cross-reactive antibody responses characterizing patients with CD. Our findings indicate gastrointestinal glutathione peroxidase as a novel autoantigen in CD.
Adolescent↗
Origin of cross-reactive autoimmunity in primary biliary cirrhosis.
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Autoantibodies↗
Non-organ-specific autoantibodies in hepatitis C virus infection: do they matter?
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Adult↗
Treatment challenges and investigational opportunities in autoimmune hepatitis.
New drugs and advances in molecular biology afford opportunities to upgrade the treatment of autoimmune hepatitis. The aims of this study were to define treatment problems, identify possible solutions, and stimulate investigations to improve patient care. A clinical subcommittee of the International Autoimmune Hepatitis Group reviewed current management difficulties and proposed corrective actions. The assessment of new front-line and salvage therapies for adults and children were given top priority. Cyclosporine and mycophenolate mofetil were endorsed as drugs worthy of rigorous study in severe disease, and budesonide was endorsed for study as front-line therapy in mild disease. Diagnostic criteria and treatment regimens for children required codification, and pharmacokinetic studies were encouraged to develop optimal dosing schedules based on therapeutic ranges. Collaborative efforts were proposed to help understand racial, geographical, and genetic factors affecting outcome and to establish definitions and therapies for variant syndromes and graft dysfunction after transplantation. The development of experimental animal models was deemed essential for the study of site-specific molecular interventions, and gene therapy was endorsed as a means of bolstering reparative processes. In conclusion, evolving pharmacological and technical advances promise to improve the treatment of autoimmune hepatitis, and investigations of these advances are timely, feasible, and necessary.
Gastroenterology↗
Primary biliary cirrhosis is characterized by IgG3 antibodies cross-reactive with the major mitochondrial autoepitope and its Lactobacillus mimic.
The serological hallmark of primary biliary cirrhosis (PBC) is the presence of pyruvate dehydrogenase complex E2 subunit (PDC-E2) antimitochondrial antibodies (AMAs). Anti-PDC-E2 antibodies cross-react specifically with mycobacterial hsp65, and we have demonstrated that the motif SxGDL[ILV]AE shared by PDC-E2(212-226) and hsp's is a cross-reactive target. Having found that this same motif is present only in beta-galactosidase of Lactobacillus delbrueckii (BGAL LACDE), we hypothesized that this homology would also lead to cross-reactivity. The mimics were tested via ELISA for reactivity and competitive cross-reactivity using sera from 100 AMA-positive and 23 AMA-negative PBC patients and 190 controls. An Escherichia coli (ECOLI) PDC-E2 mimic that has been pathogenetically linked to PBC but lacks this motif has been also tested. Anti-BGAL(266-280) LACDE antibodies were restricted to AMA-positive patients (54 of 95, 57%) and belonged to immunoglobulin (Ig) G3. Of the 190 controls, 22 (12%; P < .001) had anti-BGAL(266-280) antibodies, mainly of the IgG4 subclass. ECOLI PDC-E2 reactivity was virtually absent. BGAL(266-280)/PDC-E2(212-226) reactivity of the IgG3 isotype was found in 52 (52%) AMA-positive PBC patients but in only 1 of the controls (P < .001). LACDE BGAL(266-280)/PDC-E2(212-226) reactivity was due to cross-reactivity as confirmed via competition ELISA. Antibody affinity for BGAL(266-280) was greater than for PDC-E2 mimics. Preincubation of a multireactive serum with BGAL(266-280) reduced the inhibition of enzymatic activity by 40%, while marginal effect (12%) or no effect (2%) was observed in human or ECOLI PDC-E2 mimics. In conclusion, IgG3 antibodies to BGAL LACDE cross-react with the major mitochondrial autoepitope and are characteristic of PBC.
Adult↗
Effect of CD4+ CD25+ regulatory T-cells on CD8 T-cell function in patients with autoimmune hepatitis.
BACKGROUND AND AIMS: CD4 T lymphocytes constitutively expressing the IL-2-receptor alpha-chain (CD25) (T-regs) are central to self-tolerance maintenance, preventing the proliferation and effector function of autoreactive T-cells. In autoimmune hepatitis T-regs are defective in number but maintain the ability to suppress IFNgamma production by CD4+CD25- T-cells. We have studied the ability of CD4+CD25+ (T-regs) to regulate proliferation and cytokine production by CD8 T-cells in patients with autoimmune hepatitis at diagnosis and during remission. METHODS: Twenty-five patients were studied. T-regs were purified from PBMCs by CD4 negative selection followed by CD25 positive selection, using immunomagnetic beads. The ability of T-regs to suppress CD8 T-cell proliferation was assessed by 3H-thymidine incorporation; their ability to regulate cytokine production by intracellular cytokine staining. RESULTS: We found that T-regs are unable to regulate CD8 T-cell proliferation and cytokine production in patients studied at diagnosis, while they suppress CD8 T-cell proliferation and induce an elevation of IL-4 producing CD8 T-cells in patients during drug-induced remission. CONCLUSION: Inability of T-regs to regulate CD8 T-cell function at diagnosis may contribute to the initiation of autoimmune liver damage. The ability of T-regs to regulate CD8 proliferation and IL-4 production during drug-induced remission suggests a role for immunosuppressive treatment at reconstituting T-regs function.
CD4-CD8 Ratio↗
Paralysed monocytes in acute on chronic liver disease.
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Chronic Disease↗
Susceptibility to thyroid disorders in hepatitis C.
BACKGROUND & AIMS: Autoimmune thyroid disorders (AITDs) are reported, especially during interferon treatment, in chronic HCV infection, in which non-organ-specific autoantibodies (NOSAs) are common. We wondered whether seropositivity for NOSA is associated with susceptibility to AITDs. METHODS: We evaluated thyroid function and antithyroglobulin and antithyroperoxidase antibodies in 348 Italian patients with chronic hepatitis C (34% NOSA-positive), 196 patients (33% NOSA-positive) of whom received interferon treatment. RESULTS: At baseline, thyroid disorders were significantly more frequent in liver/kidney microsomal antibody type 1 (LKM1)-positive patients (29% vs 9%, P < .005). Similarly, on interferon therapy de novo autoimmune thyroid markers and/or symptomatic thyroid disorders appeared more often in LKM1-positive patients (50% vs 3%, P < .0001). Both female sex and LKM1 positivity were predictors of AITD, but only the latter remained significant after logistic regression analysis. Cross-reactivity to all 7 linear epitopes encoding homologous amino acid sequences shared by the HCV polyprotein, CYP2D6 (the LKM1 autoantigen), and thyroperoxidase was detected in 86% LKM1-positive HCV patients with clinical thyroid disorders, but in none of the LKM1-positive or negative HCV patients without thyroid disease, and none of an HCV-negative control group comprising subjects with LKM1-positive autoimmune hepatitis or AITD without liver disease ( P < .0001). CONCLUSIONS: Patients receiving interferon therapy for hepatitis C seropositive for LKM1 are susceptible to develop AITDs, in association with treatment. Molecular mimicry and epitope spreading are potential pathogenic mechanisms.
Adolescent↗
A study of molecular mimicry and immunological cross-reactivity between hepatitis B surface antigen and myelin mimics.
On the basis of the reported association between hepatitis B vaccination (HBvacc) and autoimmune demyelinating complications such as multiple sclerosis (MS), we have looked for aminoacid similarities between the small hepatitis B virus surface antigen (SHBsAg), and the MS-autoantigens myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG) that could serve as targets of immunological cross-reactivity. Twenty-mer peptides spanning 4 SHBsAg/MOG and 1 SHBsAg/MBP mimicking pairs, were constructed and tested by ELISA as targets of cross-reactive responses. A total of 147 samples from 58 adults were collected before HBvacc (58/58), and post-HBvacc (48/58 before the second and 41/58 before the third boost). Eighty-seven sera from anti-SHBsAg antibody negative patients with various diseases were tested as pathological controls. Reactivity to at least one of the SHBsAg peptides was found in 8 (14%) pre-HBvacc subjects; amongst the remaining 50, reactivity to at least one of the SHBsAg peptides appeared in 47 (94%) post-HBvacc. Reactivity to at least one of the MOG mimics was present in 4 (8%) pre-HBvacc and in 30 (60%) post-HBvacc (p < 0.001). Overall 30/50 (60%) vaccinees had SHBsAg/MOG double reactivity on at least one occasion compared to none before-vaccination and in 2 (2%) of the pathological controls (p < 0.001 for both). SHBsAg/MOG double reactivity was cross-reactive as confirmed by inhibition studies. At 6 months post-vaccination, 3 of the 4 anti-MOG reactive cases before vaccination and 7 of the 24 (29%) of the anti-MOG reactive cases at 3 months post-vaccination had lost their reactivity to MOG5-24. There was no reactivity to the SHBsAg/MBP mimics. None of the vaccinees reported symptoms of demyelinating disorders. In view of the observed SHBsAg/MOG cross-reactivity, the vaccine's possible role as an immunomodulator of viral/self cross-reactivity must be further investigated.
Adult↗
Antibodies to soluble liver antigen and alpha-enolase in patients with autoimmune hepatitis.
BACKGROUND: Antibodies to a cytosolic soluble liver antigen (SLA) are specifically detected in patients with autoimmune hepatitis (AIH). The target of anti-SLA has been identified as a ~50 kDa UGA serine tRNA-associated protein complex (tRNP(Ser)Sec), through the screening of cDNA libraries. A recent report questioned the identity of tRNP(Ser)Sec as the real SLA antigen. The latter study identified alpha-enolase as a major anti-SLA target, through proteomic analysis. METHODS: In an attempt to explain the observed discrepancy we have investigated reactivity of SLA positive sera against alpha-enolase and tRNP(Ser)Sec using rat and primate liver homogenate and the recombinant antigens. Thirty-three serum samples, 11 from SLA-positive patients and 22 from SLA negative controls were investigated. SLA antibodies were detected by an inhibition ELISA and confirmed by immunoblot using human liver homogenate. Autoantibody reactivity was further evaluated using preparations of primate and rat liver homogenates. Anti-alpha-enolase antibody reactivity has been tested by immunoblot using recombinant alpha-enolase. An affinity purified goat polyclonal anti-alpha-enolase IgG antibody was used as reference serum sample. Anti-tRNP(Ser)Sec antibody reactivity was detected by ELISA or dot blot using recombinant tRNP(Ser)Sec antigen. RESULTS AND DISCUSSION: The affinity purified IgG antibody directed to human alpha-enolase gave a band of approximately 48 kDa in both human and rat liver homogenates. A high titre anti-tRNP(Ser)Sec antibody serum gave a single band of ~50 kDa in both liver preparations. All but one anti-SLA antibody positive sera reacted with a ~50 kDa but none immunofixed a 48 kDa band. All anti-SLA antibody positive sera reacted strongly with the recombinant full length tRNP(Ser)Sec protein. None of the anti-SLA negative sera reacted with tRNP(Ser)Sec. Anti-SLA positive, and anti-SLA negative sera reacted equally against recombinant alpha-enolase by immunoblot. Pre-incubation of anti-SLA positive sera with tRNP(Ser)Sec completely abolished the 50 kDa band. The findings of the present study indicate that alpha-enolase and tRNP(Ser)Sec are both expressed in primate and rat liver and have a respective MW of 48 and 50 kDa. They also show that anti-tRNP(Ser)Sec - but not anti-alpha-enolase - correlates with anti-SLA antibody reactivity. CONCLUSION: Our findings indicate that tRNP(Ser)Sec is the most likely target of anti-SLA.
Journal Article↗
Non-organ-specific autoantibodies in children with chronic hepatitis C virus infection.
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Antibody Specificity↗
Unusual suspects in primary biliary cirrhosis.
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Alphaproteobacteria↗