A Clinical Workflow for Cost-Saving High-Rate Diagnosis of Genetic Kidney Diseases

SIGNIFICANCE STATEMENT

To optimize the diagnosis of genetic kidney disorders in a cost-effective manner, we developed a workflow based on referral criteria for in-person evaluation at a tertiary center, whole-exome sequencing, reverse phenotyping, and multidisciplinary board analysis. This workflow reached a diagnostic rate of 67%, with 48% confirming and 19% modifying the suspected clinical diagnosis. We obtained a genetic diagnosis in 64% of children and 70% of adults. A modeled cost analysis demonstrated that early genetic testing saves 20% of costs per patient. Real cost analysis on a representative sample of 66 patients demonstrated an actual cost reduction of 41%. This workflow demonstrates feasibility, performance, and economic effect for the diagnosis of genetic kidney diseases in a real-world setting.

BACKGROUND

Whole-exome sequencing (WES) increases the diagnostic rate of genetic kidney disorders, but accessibility, interpretation of results, and costs limit use in daily practice.

METHODS

Univariable analysis of a historical cohort of 392 patients who underwent WES for kidney diseases showed that resistance to treatments, familial history of kidney disease, extrarenal involvement, congenital abnormalities of the kidney and urinary tract and CKD stage ≥G2, two or more cysts per kidney on ultrasound, persistent hyperechoic kidneys or nephrocalcinosis on ultrasound, and persistent metabolic abnormalities were most predictive for genetic diagnosis. We prospectively applied these criteria to select patients in a network of nephrology centers, followed by centralized genetic diagnosis by WES, reverse phenotyping, and multidisciplinary board discussion.

RESULTS

We applied this multistep workflow to 476 patients with eight clinical categories (podocytopathies, collagenopathies, CKD of unknown origin, tubulopathies, ciliopathies, congenital anomalies of the kidney and urinary tract, syndromic CKD, metabolic kidney disorders), obtaining genetic diagnosis for 319 of 476 patients (67.0%) (95% in 21 patients with disease onset during the fetal period or at birth, 64% in 298 pediatric patients, and 70% in 156 adult patients). The suspected clinical diagnosis was confirmed in 48% of the 476 patients and modified in 19%. A modeled cost analysis showed that application of this workflow saved 20% of costs per patient when performed at the beginning of the diagnostic process. Real cost analysis of 66 patients randomly selected from all categories showed actual cost reduction of 41%.

CONCLUSIONS

A diagnostic workflow for genetic kidney diseases that includes WES is cost-saving, especially if implemented early, and is feasible in a real-world setting.

Chiari 1 malformation and exome sequencing in 51 trios: the emerging role of rare missense variants in chromatin-remodeling genes

Type 1 Chiari malformation (C1M) is characterized by cerebellar tonsillar herniation of 3–5 mm or more, the frequency of which is presumably much higher than one in 1000 births, as previously believed. Its etiology remains undefined, although a genetic basis is strongly supported by C1M presence in numerous genetic syndromes associated with different genes. Whole-exome sequencing (WES) in 51 between isolated and syndromic pediatric cases and their relatives was performed after confirmation of the defect by brain magnetic resonance image (MRI). Moreover, in all the cases showing an inherited candidate variant, brain MRI was performed in both parents and not only in the carrier one to investigate whether the defect segregated with the variant. More than half of the variants were Missense and belonged to the same chromatin-remodeling genes whose protein truncation variants are associated with severe neurodevelopmental syndromes. In the remaining cases, variants have been detected in genes with a role in cranial bone sutures, microcephaly, neural tube defects, and RASopathy. This study shows that the frequency of C1M is widely underestimated, in fact many of the variants, in particular those in the chromatin-remodeling genes, were inherited from a parent with C1M, either asymptomatic or with mild symptoms. In addition, C1M is a Mendelian trait, in most cases inherited as dominant. Finally, we demonstrate that modifications of the genes that regulate chromatin architecture can cause localized anatomical alterations, with symptoms of varying degrees.

Interferon-free therapy in hepatitis C virus mixed cryoglobulinaemia: a prospective, controlled, clinical and quality of life analysis

BACKGROUND

Cryoglobulinaemic vasculitis (CV) is a lymphoproliferative disorder related to hepatitis C virus (HCV) infection; anti-viral therapy is the first therapeutic option. CV can be incapacitating, compromising the patients' quality of life (QoL). In a controlled study, interferon-based therapy was associated with a lower virological response in vasculitic patients than in patients without vasculitis. Limited, uncontrolled data on direct-acting anti-virals are available.

AIM

To evaluate safety, clinical efficacy, virological response and the impact of interferon-free treatment on QoL in HCV patients with and without mixed cryoglobulinaemia (MC).

METHODS

We prospectively studied HCV patients with cryoglobulinaemia (with vasculitis-CV- and without vasculitis-MC-) and without cryoglobulinaemia (controls), treated with direct-acting anti-virals. Hepato-virological parameters, CV clinical response and impact on QoL were assessed.

RESULTS

One hundred and eighty-two HCV patients were recruited (85 with CV, 54 with MC and 43 controls). A sustained virological response at 12 weeks (SVR12) was achieved in 166 (91.2%) patients (77/85 CV, 48/54 MC, 41/43 controls). In CV SVR patients, cryocrit levels progressively decreased and clinical response progressively improved, reaching 96.7%, 24 weeks after treatment. QoL, baseline physical and mental component summaries were lower in the CV group compared to the other groups (P < 0.05). Scores improved in all groups, and significantly in CV patients after SVR.

CONCLUSIONS

No significant differences in SVR rates were recorded between cryoglobulinaemic patients and controls and a high clinical and immunological efficacy was confirmed in CV, supporting the role of interferon-free therapy as the first therapeutic option. Interestingly, CV patients had worse baseline QoL than other HCV-positive groups and interferon-free therapy was effective in significantly increasing QoL, suggesting the important role of direct-acting anti-viral-based therapy in improving CV's individual and social burden.

Real-world management of juvenile autoimmune liver disease

Background and aims

Juvenile autoimmune liver disease (JAILD) includes paediatric forms of autoimmune hepatitis (AIH) and autoimmune sclerosing cholangitis (ASC). Since evidence is scarce, there are currently no evidence-based management guidelines for juvenile AIH. This survey was carried out amongst the paediatric members of the International AIH Group (IAIHG) to describe their practices in the management of JAILD.

Methods

An online survey questionnaire was distributed to members of the IAIHG with active practice (https://www.surveymonkey.de/r/Juvenile_AILD). The questionnaire consisted of four clinical scenarios on different presentations of AIH.

Results

Fifty-eight surveys were sent to the IAIHG members, out of which 43 (74%, 22 countries, four continents) were returned. None reported budesonide as a first-line induction agent for the acute presentation of AIH. Sixteen (37%) routinely perform liver biopsy at three years of biochemical remission. Thirty-five respondents (81%) perform magnetic resonance cholangiography (MRC) at presentation. Ciclosporin is the most widely used second-line agent (number of patients treated = ∼360, 21 centres). Mycophenolate mofetil (n = ∼225, 31 centres), tacrolimus (n = ∼130, 21 centres) and sirolimus (n = ∼5, 3 centres) are less often reported. Rescue therapy with infliximab and rituximab has been tried in eight centres (n = ∼19) and nine centres (n = ∼16), respectively.

Conclusions

Prednisolone remains the preferred first-line induction agent in JAILD. MRC at presentation is performed by the large majority of participants. Participants reported a wide variation in performing liver biopsy for therapy evaluation during follow-up. Within the paediatric members of the IAIHG there is considerable experience with second-line therapeutic agents.

SMARCA4 inactivating mutations cause concomitant Coffin-Siris syndrome, microphthalmia and small-cell carcinoma of the ovary hypercalcaemic type

SMARCA4 chromatin remodelling factor is mutated in 11% of Coffin–Siris syndrome (CSS) patients and in almost all small‐cell carcinoma of the ovary hypercalcaemic type (SCCOHT) tumours. Missense mutations with gain‐of‐function or dominant‐negative effects are associated with CSS, whereas inactivating mutations, leading to loss of SMARCA4 expression, have been exclusively found in SCCOHT. We applied whole‐exome sequencing to study a 15‐year‐old patient with mild CSS who concomitantly developed SCCOHT at age 13 years. Interestingly, our patient also showed congenital microphthalmia, which has never previously been reported in CSS patients. We detected a de novo germline heterozygous nonsense mutation in exon 19 of SMARCA4 (c.2935C > T;p.Arg979*), and a somatic frameshift mutation in exon 6 (c.1236_1236delC;p.Gln413Argfs*88), causing complete loss of SMARCA4 immunostaining in the tumour. The immunohistochemical findings are supported by the observation that the c.2935C > T mutant transcript was detected by reverse transcription polymerase chain reaction at a much lower level than the wild‐type allele in whole blood and the lymphoblastoid cell line of the proband, confirming nonsense‐mediated mRNA decay. Accordingly, immunoblotting demonstrated that there was approximately half the amount of SMARCA4 protein in the proband's cells as in controls. This study suggests that SMARCA4 constitutional mutations associated with CSS are not necessarily non‐truncating, and that haploinsufficiency may explain milder CSS phenotypes, as previously reported for haploinsufficient ARID1B. In addition, our case supports the dual role of chromatin remodellers in developmental disorders and cancer, as well as the involvement of SMARCA4 in microphthalmia, confirming previous findings in mouse models and the DECIPHER database. Finally, we speculate that mild CSS might be under‐recognized in a proportion of SCCOHT patients harbouring SMARCA4 mutations. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Immunosuppressive drugs affect interferon (IFN)-γ and programmed cell death 1 (PD-1) kinetics in patients with newly diagnosed autoimmune hepatitis

Autoimmune hepatitis (AIH) is characterized by overwhelming effector immune responses associated with defective regulatory T cells (T_regs ). Several lines of evidence indicate CD4 as the main effectors involved in autoimmune liver damage. Herein we investigate the in-vitro effects of prednisolone, 6-mercaptopurine, cyclosporin, tacrolimus, mycophenolic acid (MPA) and rapamycin, immunosuppressive drugs (ISDs) used in AIH treatment, on the expression of proinflammatory cytokines, co-inhibitory molecules and ability to proliferate of CD4⁺ CD25^- cells, isolated from the peripheral blood of treatment-naive patients with AIH. We note that in healthy subjects (HS) following polyclonal stimulation and in the absence of ISDs, the expression of interferon (IFN)-γ, interleukin (IL)-17 and tumour necrosis factor (TNF)-α by CD4 effectors peaks at 48 h and decreases at 96 h to reach baseline levels. In contrast, in AIH the expression of all these proinflammatory cytokines continue rising between 48 and 96 h. Levels of programmed cell death-1 (PD-1), T cell immunoglobulin and mucin domain-containing molecule-3 (TIM-3) and cytotoxic T lymphocyte antigen-4 (CTLA-4) increase over 96-h culture both in HS and AIH, although with faster kinetics in the latter. Exposure to ISDs contains IFN-γ and PD-1 expression in AIH, where control over CD4⁺ CD25^- cell proliferation is also noted upon exposure to MPA. Treatment with tacrolimus and cyclosporin render CD4⁺ CD25^- cells more susceptible to T_reg control. Collectively, our data indicate that in treatment-naive patients with AIH, all ISDs restrain T helper type 1 (Th1) cells and modulate PD-1 expression. Furthermore, they suggest that tacrolimus and cyclosporin may ameliorate effector cell responsiveness to T_regs .

Alcohol Dehydrogenase: An Autoantibody Target in Patients with Alcoholic Liver Disease

The link between alcohol consumption and liver disease is not direct and several factors including autoimmunity to hepatocyte components have been implicated. We have previously identified alcohol dehydrogenase (ADH) as an autoantigen in autoimmune liver disease and in a proportion of patients with alcoholic liver disease. The aim of the present study is to investigate the association between the presence of anti-ADH antibodies, alcohol consumption and severity of liver damage in alcoholic patients. The presence of antibodies to human ADH β2 and horse ADH was investigated in 108 patients with documented history of alcohol consumption and alcohol related liver disease, 86 being active alcohol abusers and 22 on sustained alcohol withdrawal, 39 with non-alcohol related disease and 22 normal subjects.

Antibodies to either ADH form were more frequently detected in active alcohol abusers (55/86, 64%) than in patients on sustained alcohol withdrawal longer than 6 months (1/8, 13%, p<0.005), HBV infection (2/8, 25%, P=0.03), non-alcohol related disease (9/29, 23%, p<0.0001) and in normal controls (3/22, 14%, p<0.0001); were more frequent in patients with cirrhosis than in those with steatosis (26/34, 76% vs 34/64, 53%, P=0.02); and were associated with elevated levels of ALT (anti-ADH β2, p<0.05), immunoglobulin A (p<0.05) and γ-glutamyl transpeptidase (P=0.01). Anti-ADH antibody positive serum samples were able to inhibit the enzymatic activity of ADH. These findings suggest that anti-ADH antibodies may be triggered by alcohol consumption and act as a disease activity marker in alcoholic liver disease.

Human identification by lice: A Next Generation Sequencing challenge

Rapid and progressive advances in molecular biology techniques and the advent of Next Generation Sequencing (NGS) have opened new possibilities for analyses also in the identification of entomological matrixes. Insects and other arthropods are widespread in nature and those found at a crime scene can provide a useful contribution to forensic investigations. Entomological evidence is used by experts to define the postmortem interval (PMI), which is essentially based on morphological recognition of the insect and an estimation of its insect life cycle stage. However, molecular genotyping methods can also provide an important support for forensic entomological investigations when the identification of species or human genetic material is required. This case study concerns a collection of insects found in the house of a woman who died from unknown causes. Initially the insects were identified morphologically as belonging to the Pediculidae family, and then, human DNA was extracted and analyzed from their gastrointestinal tract. The application of the latest generation forensic DNA assays, such as the Quantifiler(®) Trio DNA Quantification Kit and the HID-Ion AmpliSeq™ Identity Panel (Applied Biosystems(®)), individuated the presence of human DNA in the samples and determined the genetic profile.

Autoimmune hepatitis: From mechanisms to therapy

Autoimmune hepatitis (AIH) is a progressive inflammatory hepatopathy and an important cause of end-stage liver disease. Its aetiology remains unknown, though both genetic and environmental factors are involved in its development. The major mechanism of autoimmune liver damage involves immune reactions against host liver antigens. Numerical and functional defects of regulatory T-cells play a permissive role enabling autoimmune liver injury to occur and persist. The most typical features of AIH are female preponderance, hypergammaglobulinaemia, seropositivity for circulating autoantibodies and a picture of interface hepatitis on histology. Two types of AIH are distinguished according to serological profile: AIH type 1 patients are positive for anti-nuclear and/or anti-smooth muscle antibodies, whereas AIH type 2 patients are defined by the positivity for anti-liver kidney microsomal type 1 antibody and/or for anti-liver cytosol type 1 antibody. Clinical manifestations are variable, and AIH onset is often ill-defined, frequently mimicking acute hepatitis; its course may be fluctuating. AIH responds to immunosuppressive treatment in the majority of cases. Steroids with or without azathioprine should be instituted promptly upon diagnosis. Remission is achieved in some 80% of patients. For the remaining 20% of patients, alternative immunosuppressive agents such as mycophenolate mofetil and calcineurin inhibitors are an option. Liver transplantation should be considered for those patients who progress to cirrhosis and develop complications of end-stage liver disease, as well as for those presenting with acute liver failure; outcomes are excellent, although the disease may recur in the allograft.

HBsAg plasma level kinetics: a new role for an old marker as a therapy response predictor in vertically infected children on combination therapy

We aimed to investigate the ability of HBsAg plasma level kinetics to predict therapy response by studying 23 children with infancy-acquired chronic hepatitis B (CHB) during combination sequential therapy with lead-in lamivudine (LAM) and add-on interferon-α (IFN-α) [5 responders (R = anti-HBs seroconversion) and 18 nonresponders (NR)] and to assess their relationship with pretreatment intrahepatic HBV-DNA and cccDNA and HBsAg and HBcAg liver expression. Plasma HBsAg levels were measured in samples before (treatment week 0 = TW0), during (TW9, TW28, TW52) and after (follow-up week = FUW24) therapy by Abbott ARCHITECT(®) assay [log10 IU/mL]. Baseline liver HBV-DNA and cccDNA were quantified by real-time TaqMan PCR [log10 copies/ng genomic DNA]. HBsAg and HBcAg liver expression was evaluated by immunostaining of formalin-fixed, paraffin-embedded specimens [number of positive cells/1000 hepatocytes]. All results are presented as medians. Plasma: at baseline, on-treatment and during follow-up, HBsAg levels were lower in R than NR (TW0: 4.36 vs 4.75;TW28: 2.44 vs 4.35;TW52: 0 vs 4.08 and FUW24: 0.17 vs 4.35, all P < 0.05). Liver: baseline HBV-DNA (3.82 vs 4.71, P = 0.16) and cccDNA (1.98 vs 2.26, P = 0.18) tended to be lower in R than NR, HBsAg expression was lower in R than NR (0.5 vs 4.7, P = 0.03), and HBcAg expression was similar between R and NR. There were positive correlations between plasma HBsAg levels and liver HBV-DNA (r = 0.44, P = 0.04), cccDNA (r = 0.41, P = 0.04) and HBsAg liver expression (r = 0.38, P = 0.05). Lower baseline HBsAg plasma levels, lower HBsAg expression in liver and on-treatment decline of plasma HBsAg levels heralds HBsAg clearance and response to treatment in tolerant children with CHB.

Admission levels and early changes in serum interleukin-10 are predictive of poor outcome in acute liver failure and decompensated cirrhosis

BACKGROUND & AIM

Immunoparesis contributes to prognosis in acute liver failure (ALF) and decompensated cirrhosis, a phenomenon thought to be mediated by the anti-inflammatory cytokine interleukin (IL)-10. We investigated the prognostic value of admission IL-10 levels and their evolution during the early phase of treatment in intensive care, in comparison to the pro-inflammatory cytokines IL-6 and tumour necrosis factor (TNF)-alpha.

METHODS

We measured these cytokines within 48 h of admission in 51 ALF and 39 decompensated cirrhosis patients admitted to intensive care, and obtained follow-up measurement a median of 2 days later in 35 patients.

RESULTS

Levels of all cytokines were higher in those with a poor outcome. IL-10 performed as well as TNF-alpha and IL-6 in the whole cohort (area under receiver operator curve 0.73 vs 0.66 and 0.72). However IL-10 outperfomed pro-inflammatory cytokines in the subgroups with ALF (0.80 vs 0.63 and 0.70) and acetaminophen-induced ALF (0.92 vs 0.67 and 0.81). Levels of all cytokines rose significantly in non-surviving patients (n=15); IL-10 by a factor of 2, TNF-alpha by 2.6 and IL-6 by 1.13. No significant changes were seen in the surviving patients. In ALF, IL-10 was an independent predictor of outcome in multivariate analysis.

CONCLUSION

The magnitude of the compensatory anti-inflammatory response at admission, and its development during the early phase of treatment, predicts outcome as well as the pro-inflammatory response in acute hepatic syndromes and supports a vital role for this immunological phenomenon in the outcome of these patients.

HCV and autoimmunity

Hepatitis C virus (HCV) infection is characterized by a number of autoreactive manifestations, such as autoantibody production, cryoglobulinemia and thyroid disorders. We will analyse critically the mechanisms invoked, and partially documented, to explain such manifestations arising in genetically predisposed individuals exposed to HCV. In particular we will examine the available evidence implicating the virus in lowering the B cell activation threshold, in directly infecting lymphocytes and in inducing self-reactivity through a mechanism of molecular mimicry. We will then move to the HCV related clinical immunopathological manifestations, with a specific attention to the effects of antiviral treatment.

HCV infection: pathogenesis, clinical manifestations and therapy

Chronic hepatitis C virus (HCV) infection is a worldwide public health problem with a global prevalence of 2-3%. It is believed that about 170 million people are currently infected (about 3% of the world's population), and a further 3-4 million are infected each year. HCV is the main reason for liver transplantation in the developed world, and the main cause of liver-related morbidity and mortality in a number of countries, including Italy. It is not only a frequent cause of chronic liver diseases such as hepatitis, cirrhosis and hepatocellular carcinoma, but is also involved in the pathogenesis of various autoimmune and rheumatic disorders (arthritis, vasculitis, sicca syndrome, porphyria cutanea tarda, lichen planus, nephropathies, thyroid diseases, and lung fibrosis), as well as in the development of B-cell lymphoproliferative diseases. Furthermore, patients suffering from C hepatitis tend to produce rheumatoid factor, cryoglobulins and a large series of autoantibodies (ANA, anti-SSA/SSB, SAM, ATG, aCL). The use of glucocorticoids or immuno-suppressant agents in HCV infected individuals, which are needed to treat autoimmune and rheumatic disorders, leads to a risk of worsening the clinical outcome of HCV. Under these conditions, the viral infection often needs to be treated with antiviral agents, mainly pegylated interferon combined with ribavirin. However, cyclosporine A seems to be safe and effective in patients with autoimmune disease (AD) and concomitant chronic HCV infection as is documented by the reduction in viremia and transaminases, particularly in patients with high baseline levels. Finally, HCV is the main trigger of mixed cryoglobulinemia. An attempt at viral eradication is therefore indicated in most patients, and is particularly effective in the case of mild or moderate manifestations. In severe cases, rituximab is an apparently safe and effective alternative to conventional immunosuppression and, specifically, it controls B-cell proliferation.

Prevalence and clinical significance of isotype specific antinuclear antibodies in primary biliary cirrhosis

BACKGROUND

Antinuclear antibodies (ANA) giving a rim-like/membranous (RL/M) or a multiple nuclear dot (MND) pattern are highly specific for primary biliary cirrhosis (PBC). Aim and

SUBJECTS

To assess the prevalence of PBC specific ANAs, their Ig isotype, and their clinical significance in 90 PBC patients from Greece and Spain. Twenty eight patients with chronic hepatitis C, 23 patients with systemic lupus erythematosus, and 17 healthy subjects were studied as controls.

METHODS

PBC specific ANA reactivity was tested by indirect immunofluorescence using HEp2 cells as substrate and individual Ig class (IgG, IgA, IgM) and IgG subclass (IgG1, IgG2, IgG3, IgG4) specific antisera as revealing reagents.

RESULTS

Fourteen of 90 (15.6%) PBC patients had PBC specific ANA reactivity when an anti-IgG (total) antiserum was used as the revealing reagent while 58 (64.4%) were positive when specific antisera to each of the four IgG isotypes were used. The prevailing isotype was IgG3 for MND and IgG1 for RL/M. PBC patients with specific ANA, in particular of the IgG3 isotype, had significantly more severe biochemical and histological disease compared with those who were seronegative. None of the controls was positive.

CONCLUSIONS

Disease specific ANA are present in the majority of patients with PBC when investigated at the level of immunoglobulin isotype. PBC specific ANA, in particular of the IgG3 isotype, are associated with a more severe disease course, possibly reflecting the peculiar ability of this isotype to engage mediators of damage.

Multiple viral/self immunological cross-reactivity in liver kidney microsomal antibody positive hepatitis C virus infected patients is associated with the possession of HLA B51

Liver Kidney Microsomal autoantibody type 1(LKM1) directed to cytochrome P4502D6 (CYP2D6) characterises autoimmune hepatitis type-2 (AIH-2), but is also found in a proportion of chronic hepatitis C virus (HCV) infected patients, CYP2D6252-271 being a major B- cell autoepitope. Molecular mimicry and immunological cross-reactivity between CYP2D6252-271, HCV polyprotein and the infected cell protein 4 (ICP4) of herpes simplex virus type 1 (HSV-1) have been suggested as triggers for the induction of LKM1, but reactivity and cross-reactivity to the relevant sequences have not been investigated experimentally. CYP2D6252-271 and its viral homologues were constructed and tested by ELISA in the sera of 46 chronically infected HCV patients, 23 of whom were LKM1 positive. Reactivity to the E1 HCV and ICP4 HSV1 mimics was frequently found in HCV infected patients irrespectively of their LKM1 status; viral/self cross-reactivity (as indicated by inhibition studies), however, was present in the only 2 of the 23 LKM1 seropositive HCV patients, who possessed the HLA allotype B51. Our results indicate that in HCV infected patients virus/self cross-reactivity is dependent on a specific immunogenetic background, a finding awaiting confirmation by studies in larger series of patients.

Extensive homology between the major immunodominant mitochondrial antigen in primary biliary cirrhosis and Helicobacter pylori does not lead to immunological cross-reactivity

BACKGROUND

Primary biliary cirrhosis (PBC) is an immune-mediated chronic cholestatic disease characterized by the presence of antibodies directed predominantly against the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2). What provokes tolerance breakdown in PBC remains to be established, though there is evidence to indicate that microbes may induce anti-mitochondrial antibodies (AMA) through a mechanism of molecular mimicry.

METHODS

Having found that urease beta (UREB)(22-36) antigen of Helicobacter pylori (HELPY) shares extensive (87%) similarity with PDC-E2(212-226), the major mitochondrial autoepitope, it was hypothesized that this would also lead to cross-reactivity. The UREB/PDC-E2 mimics were thus constructed and tested by ELISA in 112 PBC patients and 114 controls.

RESULTS

Reactivity to PDC-E2(212-226) was found in 104 patients but to UREB(22-36) in only 2. In these two patients, the double reactivity was not cross-reactive. The lack of surface antibody accessibility to UREB(22-36), as demonstrated through three-dimensional model prediction analysis, may explain this unexpected finding. There was some speculation on whether HELPY UREB(22-36) might act as a cross-reactive CD4 T-cell epitope. All seven PBC patients, tested in a standard proliferation assay against PDC-E2(212-226), gave a positive response. All seven were unresponsive to HELPY UREB(22-36). The pattern of reactivity to HELPY antigens by immunoblot was similar between anti-PDC-E2-positive and negative PBC cases, as well as between PBC patients and controls.

CONCLUSION

Contrary to common belief, extensive sequence homology (molecular mimicry) between self and microbe does not necessarily result in cross-reactivity. It is therefore likely that, when present, cross-reactivity between self and microbes is of biological importance.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is characterised histologically by interface hepatitis, and serologically by the presence of non-organ and liver specific autoantibodies and increased levels of immunoglobulin G. Its onset is often ill-defined, frequently mimicing acute hepatitis. AIH usually responds to immunosuppressive treatment, which should be instituted as soon as diagnosis is made. Two types of AIH are recognized according to seropositivity for smooth muscle and/or antinuclear antibody (SMA/ANA, type 1 AIH) or liver kidney microsomal type 1 antibody (LKM1, type 2 AIH). There is a female predominance in both. LKM1 positive patients tend to present more acutely, at a younger age and commonly have immunoglobulin A deficiency, while duration of symptoms before diagnosis, clinical signs, family history of autoimmunity, presence of associated autoimmune disorders, response to treatment and long-term prognosis are similar in the 2 groups. Susceptibility to AIH type 1 is conferred by possession of HLA DR3 and DR4, while to AIH type 2 by possession of HLA DR7. Liver damage is likely to derive from an immune reaction to liver cell antigens, possibly triggered by a mechanism of molecular mimicry, where immune responses to external pathogens, e.g. viruses, become directed towards structurally similar self-components. In AIH this process would be perpetuated by impairment in immune regulation.

Association between the primary biliary cirrhosis specific anti-sp100 antibodies and recurrent urinary tract infection

BACKGROUND AND AIMS

Recurrent urinary tract infections (rUTI) have been suggested to be involved in the induction of anti-mitochondrial antibodies (AMA), the serological hallmark of primary biliary cirrhosis (PBC), in view of the presence of AMA in rUTI women without liver disease and conversely of a high prevalence of rUTI in women with PBC. This prompted us to investigate whether PBC-specific anti-nuclear antibodies (ANA) to sp100, gp210 and lamin B receptor (LBR) antigens may also be related to rUTI.

METHODS AND SUBJECTS

PBC-specific ANA reactivities were investigated in 20 women with rUTI but without liver disease, some of whom were AMA-seropositive; 40 women with PBC, with or without rUTI; and 104 pathological and 23 healthy controls.

RESULTS

Among the women with rUTI but without liver disease, 8 (80%) of 10 AMA-positive women reacted with sp100 compared with none of the 10 AMA-negative women. Among the PBC patients, 14 (74%) of 19 with rUTI and 1 (4.8%) of the 21 without rUTI reacted with sp100. None of the rUTI women without liver disease reacted with gp210 or LBR. None of 127 pathological and healthy controls had PBC-specific ANA reactivity.

CONCLUSIONS

Anti-sp100 reactivity strongly correlates with AMA seropositivity in rUTI women, with or without evidence of primary biliary cirrhosis. These findings provide additional support to the notion that E. coli infection is involved in the induction of PBC-specific autoimmunity. Additional factors must be involved in the progression to overt autoimmune disease.

Type 1 diabetes mellitus in patients with chronic hepatitis C before and after interferon therapy

Type 1 diabetes mellitus is the result of an autoimmune process characterized by pancreatic beta cell destruction. It has been reported that chronic hepatitis C infection is associated with type 2 diabetes mellitus, but not with type 1. Although the prevalence of markers of pancreatic autoimmunity in hepatitis C virus-positive patients is not significantly different to that reported in the general population, it increases during alpha-interferon therapy from 3 to 7%, probably due to the immunostimulatory effects of this cytokine. To date, 31 case reports of type 1 diabetes mellitus related to interferon treatment have been published. Type 1 diabetes mellitus occurs more frequently in patients treated for chronic hepatitis C than for other conditions and is irreversible in most cases. In 50% of these patients, markers of pancreatic autoimmunity predated treatment, the majority of cases having a genetic predisposition. Thus, in predisposed individuals, alpha-interferon can either induce or accelerate a diabetogenic process already underway. We suggest that islet cell autoantibodies and glutamic acid decarboxylase autoantibodies should be investigated before and during interferon treatment in order to identify subjects at high risk of developing type 1 diabetes mellitus.

Mimicry between the hepatitis C virus polyprotein and antigenic targets of nuclear and smooth muscle antibodies in chronic hepatitis C virus infection

Autoantibodies to smooth muscle (SMA) and nuclear components (ANA) arise in the natural course of chronic infection with hepatitis C virus. In view of the growing evidence for 'molecular mimicry' as a mechanism of autoimmunity we investigated whether cross-reactive immune reactions between host smooth muscle/nuclear components and HCV antigens may contribute to the formation of SMA and ANA in chronic HCV infection. Computer-assisted protein database search methods were used to identify three smooth muscle (smoothelin698-717, myosin1035-1054, vimentin69-88) and three nuclear (matrin722-741, histone H2A11-30, replication protein A133-152) host antigens with the highest local sequence similarity to the HCV polyprotein and 20-mer peptides corresponding to these regions were constructed. Sera from 51 children with chronic HCV infection [median age: 8 (2-16); 27 boys], 26 SMA positive and five ANA positive, were tested for reactivity to the synthesized HCV peptides and their human homologues by enzyme linked immunosorbent assay (ELISA). Sera from patients with HBV infection and chronic liver disease of different aetiologies were used as controls. 'Double reactivity' to HCV peptides and smooth muscle/nuclear homologues was associated strongly with HCV infection (P < 0.001 for both). Humoral cross-reactivity was established as the basis for double recognition by competition ELISA. Double-reactivity to smooth muscle and HCV peptide antigens correlated with SMA positivity by indirect immunofluouresence (P = 0.05). Of 15 patients double-reactive to myosin1035-1054 and its HCV homologue, 13 recognized whole myosin by immunoblot. These results suggest that ANA and SMA in chronic HCV infection may arise, at least in part, as a consequence of cross-reactive immune responses to HCV and host smooth muscle/nuclear antigens.

Autoimmune liver disease in children

Autoimmune liver disorders are characterised by an inflammatory liver histology, circulating non-organ specific autoantibodies and increased levels of immunoglobulin G (IgG) in the absence of a known aetiology. They respond to immunosuppressive treatment, which should be instituted as soon as diagnosis is made. Liver disorders with a likely autoimmune pathogenesis include autoimmune hepatitis (AIH) and autoimmune sclerosing cholangitis (ASC). Two types of AIH are recognised according to seropositivity for smooth muscle and/or antinuclear antibody (SMA/ANA, type 1) or liver kidney microsomal antibody (LKM1, type 2). There is a female predominance in both. LKM1-positive patients tend to present more acutely, at a younger age, and commonly have immunoglobulin A (IgA) deficiency, while duration of symptoms before diagnosis, clinical signs, family history of autoimmunity, presence of associated autoimmune disorders, response to treatment and long-term prognosis are similar in both groups. The most common type of paediatric sclerosing cholangitis is ASC. The clinical, biochemical, immunological and histological presentation of ASC is often indistinguishable from that of AIH. In both, there are high IgG, non-organ specific autoantibodies and interface hepatitis. Diagnosis is made by cholangiography. Children with ASC respond to immunosuppression satisfactorily and similarly to AIH in respect to remission and relapse rates, times to normalisation of biochemical parameters and decreased inflammatory activity on follow-up liver biopsies. However, the cholangiopathy can progress and there may be an evolution from AIH to ASC over the years, despite treatment. Whether the juvenile autoimmune form of sclerosing cholangitis and AIH are 2 distinct entities, or different aspects of the same condition, remains to be elucidated.

Detection of liver kidney microsomal type 1 antibody using molecularly based immunoassays

AIMS

To assess the diagnostic value of two commercial molecularly based immunoassays detecting liver kidney microsomal type 1 antibody (LKM1).

METHODS

The performance of Varelisa and LKM1 enzyme linked immunosorbent assay (ELISA) was compared with immunofluorescence, and two validated research techniques-an in house ELISA and a radioligand assay measuring antibodies to P4502D6. Thirty serum samples from three patients with autoimmune hepatitis type 2 covering immunofluorescence titres of 1/10 to 1/10 240 and 55 LKM1 negative controls were tested.

RESULTS

All 30 sera that were LKM1 positive by immunofluorescence were positive by the in house ELISA, the radioligand assay, and LKM1-ELISA, and 29 were also positive by Varelisa. None of the 55 sera negative for LKM1 by immunofluorescence was positive by the in house ELISA and radioligand assay, but one was positive by Varelisa and 14 were positive using the LKM1-ELISA. Agreement between immunofluorescence, the in house ELISA, the radioligand assay, and Varelisa was high (kappa > 0.8), and agreement between immunofluorescence and LKM1-ELISA was moderate (kappa = 0.63).

CONCLUSION

The assay kit marketed as Varelisa allows accurate detection of LKM1.

Immunodeficiency-related lymphoproliferative disorders: prospective data from the United Kingdom Children's Cancer Study Group Registry

Clinical data and biological samples were prospectively collected in 42 children with lymphoproliferative disease (LPD) secondary to organ/bone marrow transplant-related immunosuppression (30: 11 liver, 10 heart/lung, 8 kidney and 1 bone marrow), other drug-induced immunosuppression (2), congenital immunodeficiency (8) or human immunodeficiency virus (HIV)-related immune dysfunction (2). Ages ranged from 10 months to 17 years and there were 15 girls. Pathology was centrally reviewed and showed polymorphic features in 5 cases, monomorphic in 23, mixed pattern in 5 patients and 9 other types. Using the Revised European-American Classification of Lymphoid Neoplasms, 5 were B lymphoblastoid, 24 were high-grade B and 14 were other subtypes. Using the Pittsburgh classification, 9 were lymphadenopathic, 10 were systemic, 25 were lymphomatous and, with the Murphy grouping for non-Hodgkin's lymphoma (NHL), 10 were localized and 32 non-localized. Twenty-four out of 38 evaluable cases were Epstein-Barr virus positive. Thirty-five patients were evaluable for clonality; 24 were monoclonal and 11 were polyclonal. Reduced immunosuppression in solid organ transplant patients resulted in resolution of disease in 14/24, which was sustained in 11. Nineteen patients received chemotherapy, 14/18 evaluable responded, which was sustained in 8 cases. Seven out of 29 solid organ transplant and 10/13 other immune-deficient patients died. In the largest group of patients, solid organ transplants, no significant clinical or biological characteristics that predicted outcome were identified. In the transplant group close monitoring of response during reduction in immunosuppression is essential and the early use of B NHL chemotherapy may be effective.

Autoimmune hepatitis

Autoimmune liver disease encompasses several disorders (Table 1). Autoimmune hepatitis (AIH) affects mainly women and is characterized histologically by a portal tract mononuclear cell infiltrate disrupting the limiting plate and invading the parenchyma ("interface hepatitis") and serologically by the presence of autoantibodies and increased levels of immunoglobulin G (IgG), in the absence of a known cause. AIH responds to immunosuppressive treatment. It can present insidiously or as an acute hepatitis. The previously accepted requirement of 6-month duration of symptoms before diagnosis can be made has been abandoned and treatment should be instituted as soon as the disease is diagnosed. In this review, we concentrate on those reports that add to our knowledge in terms of pathogenesis, differential diagnosis, treatment, and clinical course. Special attention is given to overlap syndromes.

Autoantibodies to human cytosol: a marker of sporadic porphyria cutanea tarda

The enzymes potentially involved in the pathogenesis of sporadic porphyria cutanea tarda (PCT) reside in liver cytosoles and microsomes. PCT is frequently associated with hepatitis C virus (HCV) infection, which is in turn associated with autoimmune manifestations. To investigate whether autoimmune reactions, possibly triggered by HCV, are involved in the pathogenesis of PCT, we measured by immunoblot autoantibodies to human cytosolic and microsomal liver fractions in 82 patients with PCT (77% with HCV infection), 105 with other liver disorders and 40 healthy subjects. Anti-liver cytosolic antibodies were more frequent in PCT patients (38/82, 46%) than in pathological controls (P < 0.05-P < 0.001) or in healthy subjects (3/40, 8%, P < 0.001). Among PCT patients, anticytosolic antibodies were more frequent in HCV positive (36/63, 57%) than in HCV negative (2/19, 11%, P < 0.05) cases. Reactivity to a 40-kDa cytosolic polypeptide was present in 20 PCT patients (19 HCV positive), being more frequent than in all pathological controls (P < 0.01-P < 0.0001). Histological activity index (P = 0.04) and antibodies to HCV (P = 0.027) - but not HCV RNA - were associated independently with anticytosolic antibodies as assessed by multivariate analysis. In contrast, frequency of antiliver microsomal antibodies was similar in PCT patients (24/82, 29%) and pathological controls (8-26%), being higher in the autoimmune hepatitis control group (23/23, 100%, P < 0.0001). In conclusion, anticytosolic antibodies, particularly to a 40-kDa polypeptide, are frequent in PCT and associated with HCV infection and severity of liver damage.

Sclerosing cholangitis in the paediatric patient

Sclerosing cholangitis in childhood is a heterogeneous condition, which has different aetiologies. Sclerosing cholangitis may be inherited and diagnosed in the neonatal period (neonatal sclerosing cholangitis); it may present later with features of autoimmunity (autoimmune sclerosing cholangitis); or it may be associated with a variety of disorders, including Langerhans cell histiocytosis, immunodeficiency, psoriasis, cystic fibrosis, reticulum cell sarcoma and sickle cell anaemia. In contrast to the experience in adult patients, sclerosing cholangitis occurring as an individual disease (primary sclerosing cholangitis) is rare. The initiating events and possible pathogenic mechanisms differ in the various forms of sclerosing cholangitis and are still obscure. Treatment and prognosis depend on the type of sclerosing cholangitis present.

Molecular mimicry and autoimmune liver disease: virtuous intentions, malign consequences

The pathogenesis of autoimmune liver disease and autoimmunity associated with chronic viral hepatitis remains poorly understood. One of the major hurdles to a deeper understanding of these pathological processes is the absence of clearly defined inductive mechanisms, which, if identified and characterised, could guide clinical strategies for their prevention or allow therapeutic intervention. Molecular mimicry leading to crossreactive autoimmune responses has gained strong experimental support in the past decade. A fundamental premise of this hypothesis is the involvement of a mimicking environmental trigger. In view of the numerous viral and bacterial agents epidemiologically linked to autoimmune liver diseases, we and others have proposed molecular mimicry to be an important mechanism in these diseases. We also propose similar crossreactive mechanisms to operate in the generation of autoimmunity in viral hepatitis. This review focuses on molecular mimicry at the level of the B-cell, as few data on T-cell crossreactivity in liver disease are thus far available.

Pediatric autoimmune liver diseases: the molecular basis of humoral and cellular immunity

Pediatric autoimmune liver disease is mainly represented by two similar liver disorders: autoimmune hepatitis (AIH) and autoimmune sclerosing cholangitis (ASC), both characterized by hypergammalobulinemia, interface hepatitis and the presence of a wide range of circulating autoantibodies. Although similar features are seen in AIH and inflammatory bowel disease, histological biliary changes are more common in ASC. In addition to their role as diagnostic markers, autoantibodies, such as anti-extractable nuclear antigen (ENA) antibodies and liver kidney microsomal antibody type 1 (LKM1) may be involved directly in inducing aggressive liver diseases. Although the cellular immune response in pediatric autoimmune liver disease has been less intensively investigated than humoral immunity, the importance of antigen specific T cells has been explored. Both alphabeta and gammadelta T cells derived from either peripheral blood and liver biopsies have highly heterogeneous TCR gene usage and cytolytic activity has been demonstrated. There have been attempts to seek triggers of liver autoimmunity and several sequences shared in common between autoantigens and hepatotropic viruses, namely hepatitis B, C and cytomegalovirus have been identified. The presence of cross-reactivity between homologous sequences, especially between HCV and cytochromes, supports the possibility that molecular mimicry plays a role in the induction of autoantibodies and autoreactive cytotoxic T cells.

Autoimmune hepatitis/sclerosing cholangitis overlap syndrome in childhood: a 16-year prospective study

To investigate whether sclerosing cholangitis with an autoimmune serology characteristic of autoimmune hepatitis (AIH) and AIH are distinct entities, we studied 55 consecutive children with clinical and/or biochemical evidence of liver disease and circulating antinuclear (ANA), anti-smooth muscle (SMA), and/or liver-kidney-microsomal type 1 (LKM1) autoantibodies. They underwent liver biopsy, direct cholangiography, sigmoidoscopy, and rectal biopsy at presentation. Twenty-eight were diagnosed as AIH in the absence and 27 autoimmune sclerosing cholangitis (ASC) in the presence of radiological features of cholangiopathy. Twenty-six ASC and 20 AIH had ANA and/or SMA; 1 ASC and 8 AIH LKM1 autoantibody. Similarities between the 2 conditions included most clinical and biochemical parameters and a lower frequency of HLA DR4. Inflammatory bowel disease and histological biliary changes were more common in ASC; coagulopathy, hypoalbuminemia, lymphocytic periportal hepatitis, and HLA DR3 were more common in AIH. Histological biliary changes were observed in 65% of ASC and 31% of AIH patients. Eighty-nine percent responded to immunosuppression. Follow-up liver biopsies from 17 ASC and 18 AIH patients had similarly reduced inflammatory activity and no progression to cirrhosis. Sixteen follow-up cholangiograms from AIH patients and 9 from ASC patients were unchanged, while 8 ASC patients showed a progressive cholangiopathy. One child with AIH and ulcerative colitis developed sclerosing cholangitis 8 years after presentation. At 2 to 16 years (median, 7 years) from presentation, all patients are alive, including 4 ASC patients who underwent liver transplantation. In conclusion, ASC and AIH are similarly prevalent in childhood; cholangiography is often needed to distinguish between these 2 entities, which are likely to lie within the same disease process.

Heart rate variability and early recurrence of atrial fibrillation after electrical cardioversion

OBJECTIVES

The study evaluated the role of the autonomic nervous system in atrial fibrillation (AF) recurrence.

BACKGROUND

Early recurrence of AF after cardioversion (CV) is attributed to electrical remodeling. The possibility that an abnormal autonomic modulation might contribute to this phenomenon has not yet been adequately tested.

METHODS

We analyzed short-term heart rate variability (HRV) in 93 patients with persistent AF and on chronic amiodarone treatment, after restoration of sinus rhythm by electrical CV.

RESULTS

Two weeks later, 25 patients presented with AF. Spectral analysis of HRV revealed that patients wi

Incubation phase of acute hepatitis B in man: dynamic of cellular immune mechanisms

After hepatitis B virus (HBV) infection, liver injury and viral control have been thought to result from lysis of infected hepatocytes by virus-specific cytotoxic T cells. Patients are usually studied only after developing significant liver injury, and so the viral and immune events during the incubation phase of disease have not been defined. During a single-source outbreak of HBV infection, we identified patients before the onset of symptomatic hepatitis. The dynamics of HBV replication, liver injury, and HBV-specific CD8+ and CD4+ cell responses were investigated from incubation to recovery. Although a rise in alanine transaminase (ALT) levels was present at the time of the initial fall in HBV-DNA levels, maximal reduction in virus level occurred before significant liver injury. Direct ex vivo quantification of HBV-specific CD4+ and CD8+ cells, by using human leukocyte antigen (HLA) class I tetramers and intracellular cytokine staining, showed that adaptive immune mechanisms are present during the incubation phase, at least 4 weeks before symptoms. The results suggest that the pattern of reduction in HBV replication is not directly proportional to tissue injury during acute hepatitis B in humans. Furthermore, because virus-specific immune responses and significant reductions in viral replication are seen during the incubation phase, it is likely that the immune events central to viral control occur before symptomatic disease.

[Detection and assessment of myocardial stunning with perfusion tomographic scintigraphy using gated SPECT]

BACKGROUND

Gated-SPECT using 99mTc-labeled flow tracers provides the simultaneous assessment of global and regional myocardial perfusion and function. The aim of this study was to identify patients with stress-induced postischemic stunning, among those with reversible stress perfusion defects, and patients with artifactual defects among those with fixed defects, in order to assess the value of the functional data provided by gated acquisition of perfusion imaging in the characterization of ischemia.

METHODS

We studied 221 consecutive patients who underwent conventional diagnostic dual day stress/rest gated-SPECT following injection of 925 MBq of 99mTc-tetrofosmin using a dual head SPECT camera, 115 of whom (52%) showed reversible perfusion defects, and 66 (30%) fixed defects. Perfusion was analyzed on ungated images using 20 segments scored on a 5-point scale (0 = normal, 4 = no uptake), while wall thickening was assessed visually on stress/rest end-systolic images using a 4-point score (0 = normal, 3 = absence of wall thickening). Left ventricular ejection fraction and volumes were calculated using an automatic algorithm (quantitative gated-SPECT). Fifty-two out of 221 (23.5%) patients underwent coronary angiography.

RESULTS

In 40/115 (35%) patients with reversible perfusion defects, post-stress left ventricular ejection fraction was > 5% lower than that at rest (Group A: stunned), whereas in the remaining 75 patients, post-stress left ventricular ejection fraction was either +/- 5% or greater than that at rest (Group B: non-stunned). Peak exercise angina and ischemic electrocardiographic response to exercise were present in 79 and 58% respectively of Group A patients and in 33 and 39% of Group B patients. The number of patients with multivessel disease was significantly higher in Group A compared to Group B (58 vs 41%, p < 0.05). The total stress and rest perfusion scores were significantly higher in Group A than in Group B (p < 0.01); even the total stress wall thickening score was significantly higher in Group A (p < 0.001). As for global parameters, post-stress end-systolic volume was significantly higher in the stunned group (p < 0.05). In 40 out of 66 (60.5%) patients without reversible ischemia fixed defects were judged to be ischemic (Group C), while in 26/66 (39.5%) they were attributed to attenuation artifacts (Group D). Eighty percent of Group C patients had a previous myocardial infarction against none of Group D. Stress/rest perfusion and wall thickening scores were significantly higher in Group C than in Group D.

CONCLUSIONS

Gated-SPECT myocardial perfusion evaluation allowed us to identify a subgroup of post-stress stunned coronary artery diseased patients. The post-stress left ventricular ejection fraction reduction in this population seems to be due to the increase in end-systolic volume. The stunned patients showed more severe perfusion defects and wall thickening abnormalities.

Virus, liver and autoimmunity

The immune system's ability to distinguish self from nonself is essential for both host defence against microbial antigens and protection of self-antigens from autoimmune destruction. Such discrimination is complicated by extensive structural homology shared between micro-organisms and self-antigens, a condition known as molecular mimicry. Molecular mimicry provides the foundation for an immune response directed against an exogenous agent such as a virus to cross-react with mimicked host self sequences, leading to autoimmunity, and in some cases, tissue injury and autoimmune disease. In this review we analyse studies investigating the role of molecular mimicry and cross-reactive immunity in liver-related autoimmunity.

The role of virus-specific CD8(+) cells in liver damage and viral control during persistent hepatitis B virus infection

Hepatitis B virus (HBV) is a noncytopathic virus, and the recognition of infected hepatocytes by HBV-specific CD8 cells has been assumed to be the central mechanism causing both liver damage and virus control. To understand the role of cytotoxic T cells in the pathogenesis of HBV infection, we used functional assays that require T cell expansion in vitro and human histocompatibility leukocyte antigen (HLA)-peptide tetramers that allow direct ex vivo quantification of circulating and liver-infiltrating HBV-specific CD8 cells. Two groups of patients with persistent HBV infection were studied: one without liver inflammation and HBV replication, the other with liver inflammation and a high level of HBV replication. Contrary to expectation, a high frequency of intrahepatic HBV-specific CD8 cells was found in the absence of hepatic immunopathology. In contrast, virus-specific T cells were more diluted among liver infiltrates in viremic patients, but their absolute number was similar because of the massive cellular infiltration. Furthermore, inhibition of HBV replication was associated with the presence of a circulating reservoir of CD8(+) cells able to expand after specific virus recognition that was not detectable in highly viremic patients with liver inflammation. These results show that in the presence of an effective HBV-specific CD8 response, inhibition of virus replication can be independent of liver damage. When the HBV-specific CD8 response is unable to control virus replication, it may contribute to liver pathology not only directly but by causing the recruitment of nonvirus-specific T cells.

Immunopathogenesis of hepatitis B virus recurrence after liver transplantation

BACKGROUND AND AIMS

Hepatitis B virus (HBV) recurrence after orthotopic liver transplantation is associated with inflammatory graft changes, despite immunosuppression and donor/recipient HLA mismatch. We investigated whether immune mechanisms are involved in the pathogenesis of hepatitis B after liver transplantation.

METHODS

The virus-specific T helper (Th) cell response, activation of Th1/Th2 subpopulations, donor/recipient HLA, and expression of tumor necrosis factor (TNF)-alpha/TNF receptors were determined in 28 patients who underwent transplantation for HBV-related cirrhosis (17 with HBV recurrence and 11 without recurrence) in comparison to 30 nontransplant patients with chronic hepatitis B.

RESULTS

Orthotopic liver transplantation recipients with HBV recurrence showed significant hepatitis B core antigen-specific T-cell proliferation, comparable to nontransplant patients, which was not present in transplant recipients without recurrence. In addition, hepatic and serum interleukin (IL)-2, interferon-gamma, and TNF-alpha were enhanced, without changes in IL-4 and IL-10. Phenotypically, hepatic infiltrates in allografts with HBV recurrence were comprised of CD4+ lymphocytes and macrophages with a correlation between interferon-gamma- and TNF-alpha-producing cells and the degree of necroinflammatory activity. There was a marked up-regulation of both TNF-alpha receptors, significantly greater than in nontransplant patients.

CONCLUSIONS

These findings suggest that despite immunosuppression, HLA class I-independent immune mechanisms have a significant pathogenic role in liver damage associated with HBV recurrence after liver transplantation.

Direct ex vivo analysis of hepatitis B virus-specific CD8(+) T cells associated with the control of infection

BACKGROUND & AIMS

Cytotoxic T cells have been suggested to be responsible for lysis of hepatitis B virus (HBV)-infected hepatocytes and control of virus infection. The frequency, kinetics, phenotype, and capacity for clonal expansion of circulating HBV-specific CD8 cells were analyzed directly in patients with acute HBV infection to clarify their pathogenetic role.

METHODS

Three HLA-A2 peptide tetramers able to visualize HBV core, envelope, and polymerase epitope-specific cytotoxic T lymphocytes were synthesized and used for flow cytometric analysis of antigen-specific populations.

RESULTS

Tetramer-positive cells specific for the core 18-27 epitope were found at a higher frequency than those specific for polymerase 575-583 and envelope 335-343 epitopes in most patients with acute HBV. The number of HBV-specific CD8 cells was highest during the clinically acute stage of infection and decreased after recovery. These cells expressed an activated phenotype and had an impaired capacity to expand in vitro and to display cytolytic activity in response to peptide stimulation. Recovery of these functions was observed when the frequency of specific CD8 cells decreased, coincident with a progressive decrease in their expression of activation markers.

CONCLUSIONS

This study provides the first ex vivo evidence that the highest frequency of circulating HBV-specific CD8 cells coincides with the clinically acute phase of hepatitis B. These cells exhibit an activated phenotype with limited further proliferative capacity that is restored during recovery.

Prevalence of autoantibodies to autonomic nervous tissue structures in Type 1 diabetes mellitus

AIMS

The pathogenesis of diabetic autonomic neuropathy is multifactorial, but recent studies have suggested a link between the presence of autoantibodies to nervous tissue structures and severe, symptomatic autonomic neuropathy. The present study was designed to examine the true prevalence of these autoantibodies in a large clinic-based population of Type 1 diabetic patients compared to nondiabetic controls.

METHODS

The presence of complement fixing autoantibodies to vagus nerve (CF-VN), sympathetic ganglion (CF-SG) and adrenal medulla (CF-ADM) was assessed by immunofluorescence in a large cohort of patients (n = 394) of varying duration of Type 1 DM (median 28 years, range 6 months to 73 years) and 160 age and sex-matched nondiabetic control subjects.

RESULTS

All three autoantibodies were frequently detected in Type 1 DM (CF-VN, 22.1%; CF-SG, 30.7%; CF-ADM, 13.2%) but only rarely in healthy control subjects (4.4%, 4.4% and 3.1%, respectively; P < 0.0005 for all). There was no association between any of the autoantibodies and retinopathy (fundoscopy), peripheral somatic neuropathy (biothesiometry) or nephropathy (urinary albumin-creatinine ratio).

CONCLUSIONS

Our results on this large cohort establish the extensive presence of autonomic nervous tissue autoantibodies in Type 1 DM. Their role in reflecting, causing or predicting autonomic neuropathy remains to be determined.

The role of HBV DNA quantitative PCR in monitoring the response to interferon treatment in chronic hepatitis B virus infection

BACKGROUND/AIMS

To investigate whether the measurement of HBV DNA by quantitative polymerase chain reaction (PCR) is helpful in monitoring response to interferon treatment in chronic hepatitis B virus infection, we have determined sequentially serum levels of HBV DNA during and up to 18 months after treatment, in 10 patients with a sustained response (all anti-HBe positive, five also HBsAg negative and anti-HBs positive) and, as controls, in 12 non-responders.

METHODS

Serum HBV DNA was measured by standard hybrisation assay (Genostics, Abbott) and by quantitative PCR (Amplicor HBV Monitor test, Roche Diagnostic Systems).

RESULTS

A clear difference in HBV viral load between responders and non-responders was observed from the fourth week of treatment and was maintained throughout the study period. At the last follow up 16-26 (median 21) months after starting treatment, all the 10 responders were HBV DNA negative by hybridisation. By PCR, however, five (one anti-HBs and four anti-HBe positive) were still HBV DNA positive. In addition, one anti-HBs positive patient HBV DNA negative by PCR at last follow up, had fluctuating levels of HBV DNA by PCR during the observation period, only intermittently falling below the threshold of the assay.

CONCLUSIONS

The measurement of HBV DNA by quantitative PCR provides early prediction of response to interferon, allowing prompt modification of treatment. With this technique, HBV DNA is detected in a high proportion of sustained responders, suggesting that HBV may never be completely eliminated by interferon treatment, even after anti-HBs seroconversion.

Spontaneous T-cell proliferation in the non-obese diabetic mouse to a peptide from the unique class II MHC molecule, I-Ag7, which is also protective against the development of autoimmune diabetes

AIMS/HYPOTHESIS

Major histocompatibility complex class II molecules present antigenic peptides to T-cells and have an important role in T-cell thymic education. The mechanism by which major histocompatibility complex alleles confer a high genetic risk for autoimmune diabetes is not known. One hypothesis is that during positive thymic selection, the peripheral T-cell repertoire is modelled by major histocompatibility complex-restricted presentation of self major histocompatibility complex molecule-derived peptides, some of which mimic tissue autoantigens. The sequence similarity between a known T-cell epitope of glutamic acid decarboxylase-65, 509:VPPSLRTLED and the non-obese diabetic mouse class II major histocompatibility complex molecule I-Ag7 86:VPTSLRRLEQ is consistent with this.

METHODS

We measured spontaneous proliferation of peripheral T-cells from non-obese diabetic mice and other, non-diabetes-prone strains, to the I-Ag7 86-101 and glutamic acid decarboxylase-65(509-524) peptides, binding of these peptides to intact I-Ag7 and assessed the effect of tolerance induction on diabetes development, by injecting young non-obese diabetic mice with high doses of peptide.

RESULTS

T-cells from non-obese diabetic, but not other mice strains, spontaneously proliferate to the I-Ag7 86-101 and glutamic acid decarboxylase-65(509-524) peptides, but not control peptides. Both test peptides bind I-Ag7. Tolerance induction prolongs diabetes-free survival in non-obese diabetic mice when either the I-Ag7 86-101 or glutamic acid decarboxylase-65(509-524) peptide, but not control peptide, is used.

CONCLUSION/INTERPRETATION

A peptide from the unique class II major histocompatibility complex, diabetes-susceptibility molecule, I-Ag7, presented by I-Ag7 is a target of T-cell responses in diabetes-prone nonobese diabetic mice and tolerance induction against the peptide offers appreciable protection against the development of diabetes.

[A comparison between attenuation-corrected and -uncorrected transmission-emission SPECT images obtained with Tl-201 in CAD patients]

BACKGROUND

The aim of this study was to evaluate the impact of attenuation correction (AC) on the diagnostic accuracy of conventional stress/red thallium SPECT studies.

METHODS

We studied 60 consecutive patients (36 males) who underwent conventional diagnostic stress/red study with and without AC (NAC) using a dual-head SPECT camera (Vertex ADAC) with a 153Gd source. The mean age of these patients was 60 years (30-80) and 29 of the subjects had a history of MI. Reconstructed images were visually analyzed using 20 segments scored on a 5-point scale (0 = normal, 4 = no uptake). Diagnostic accuracy was evaluated in 24 consecutive patients who underwent coronary angiography. Polar plots from each of the four reconstructed data sets per patient were normalized on the maximum and quantified using a nine segment model.

RESULTS

The comparison between the segmental stress score obtained with and without AC showed agreement in 1057 out of 1200 (88%) segments analyzed, K statistic value = 0.67. The number of fixed defects was significantly lower after AC. The diagnostic accuracy, evaluated in 24 patients (480 segs), was not significantly different between AC and NAC analysis (80 vs 84% respectively).

CONCLUSIONS

AC seems to reduce the number of fixed defects due to attenuation artefacts without improving diagnostic accuracy, probably because of the low number of subjects submitted to angiography and of the interpreting bias due to the expertise of the operators. In fact, in the rather small group of patients evaluated, no improvement in diagnostic accuracy was observed, probably because several attenuation defects were not considered pathological due to operator expertise.