Mechanisms of autoimmune hepatitis

Autoimmune hepatitis type 2 following anti-papillomavirus vaccination in a 11-year-old girl

In the last years numerous reports describing a possible association between administration of vaccines and development of autoimmune phenomena and overt autoimmune disease were published. Possible mechanisms of induction of autoimmune phenomena by vaccines and their excipients are probably similar to those implicated in induction by infectious agents. Here we report the case of an 11-year-old girl who developed autoimmune hepatitis type II after four weeks from vaccination against human papillomavirus. The possible relationships between the use of adjuvated vaccine against papillomavirus and autoimmune hepatitis are discussed. Although we do not provide evidence for a causal link, we suggest that the occurrence of the autoimmune hepatitis may be related to the stimulation of immune system by adjuvated-vaccine, that could have triggered the disease in a genetically predisposed individual. Therefore a monitoring of liver function test following administration of vaccine against papillomavirus may be useful in adolescent girl with signs of hepatopathy, as jaundice, dark urine or hepatomegaly, to early identify and to promptly treat autoimmune liver disorders.

Autoimmune hepatitis: an analysis of 46 cases

AIM: To analyze the clinical, biochemical and immunological features, treatment, and outcome of autoimmune hepatitis (AIH) in elderly patients.

METHODS: Forty-six patients with AIH diagnosed from January 2005 to June 2009 according to the diagnostic criteria revised by international autoimmune hepatitis group (IAIHG) were included in this study. These patients were divided into two groups: those ≥60 years (n = 21) and those <60 years (n = 25). The general information, clinical, biochemical and immunological features, initial diagnostic accuracy, and outcome in these patients were retrospectively analyzed.

RESULTS: Elderly and younger AIH patients shared similar clinical manifestations, mainly including fatigue, body mass loss, jaundice, and hepatosplenomegaly. Compared with younger patients, elderly ones had higher incidence of cirrhosis (57.1% vs 12.0%, P < 0.01) and morbidity of associated autoimmune diseases (52.3% vs 17.4%, P < 0.01), but lower initial diagnostic accuracy (28.5% vs 56.0%, P < 0.05). The detection rates of ANA, SMA, AMA-M2 and SSA/SSB in elderly patients were 61.9%, 14.3%, 23.8% and 23.8%, respectively, while those of ANA, SMA, LKM1, SLA, AMA-M2, SSA/SSB, Sm and pANCA in younger patients were 65.2%, 26.0%, 4.3%, 4.3%, 4.3%, 4.3%, 4.3% and 4.3%, respectively. Both groups of patients showed increased serum γ-GT, ALT, AST, IgG and bilirubin at initial diagnosis. The increase in the levels of serum γ-GT, bilirubin, IgG and IgM was more significant in elderly patients than in younger ones (all P < 0.05 or 0.01). At 24 wk of follow-up, biochemical blood tests showed that the majority of patients had excellent immune response, and better improvement in immune response was achieved in younger patients than in elderly ones (P < 0.05 or 0.01).

CONCLUSION: Long course of disease and late diagnosis are associated with severe liver damage and slow recovery in elderly AIH patients. Misdiagnosis or missed diagnosis is the main reason for delayed treatment of AIH.

Postinfectious immunodeficiency and autoimmunity: pathogenic and clinical values and implications

Autoimmunity is still a mystery of clinical immunology and medicine as a whole. The etiology and pathogenesis of autoimmune disorders remain unclear and, thus, are assessed as a balance between hereditary predisposition, triggering factors and the appearance of autoantibodies and/or self-reactive T cells. Among the immunological armamentarium, molecular mimicry, based on self-reactive T- and B-cell activation by cross-reactive epitopes of infectious agents, is of special value. Hypotheses regarding the possible involvement of molecular mimicry in the development of postinfectious autoimmunity are currently very intriguing. They provide new approaches for identifying etiological agents that are associated with postinfectious autoimmunity, paired microbial- and tissue-linked epitopes targeted for autoimmune reaction determination, postinfectious autoimmunity pathogenesis recognition and specific prevention, and therapy for autoimmune disorder development.

Indirect immunohistochemical evaluation of graft fibrosis and interface hepatitis after pediatric liver transplantation

Fibrosis or IH following pediatric liver transplantation is recognized as major causes of graft loss, but the etiology remains unclear. To determine this issue, we used an indirect immunohistochemistry technique with post-transplant serum samples from recipients and normal human liver tissues from living liver donors, and the association between occult antibody reaction to the liver and the occurrence of fibrosis or IH was evaluated. Forty-three recipients were evaluated, and both hepatocytes and biliary epithelial cells were evaluated for staining intensity. Fibrosis and IH occurred in 13 and six patients, respectively. According to staining results for the hepatocytes and biliary epithelial cells, 18 and 11 patients, respectively, were classified into the positive group. According to log-rank analysis, positive reaction for hepatocytes was associated with increased rates of fibrosis and IH (p = 0.002 and 0.048, respectively), while positive reaction for biliary epithelial cells was associated with an increased rate of fibrosis (p = 0.014). Multivariate analysis revealed that positive reaction for hepatocytes and biliary epithelial cells was independently associated with fibrosis occurrence (p = 0.020 and 0.047, respectively). In conclusion, immune-mediated reactions by occult antibodies may underlie the pathogeneses of fibrosis and IH.

Autoimmune hepatitis type 2 arising in PFAPA syndrome: coincidences or possible correlations?

PFAPA syndrome is a chronic disease classified in the group of autoinflammatory syndromes characterized by periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis in young children. The etiology of this disorder is still unknown, but a primary dysfunction of the innate immune system seems to be involved. According to Marshall criteria, it is not possible to diagnose PFAPA in the presence of autoimmune diseases. We present here the case report of an 8-month girl with PFAPA who developed autoimmune hepatitis type 2 at the age of 18 months. We suppose that the dysregulation in innate immunity that is typical of patients with PFAPA could trigger autoimmune disorders such as autoimmune hepatitis in susceptible subjects. The possible relationships between immune-system dysfunction peculiar to this syndrome and autoimmune hepatitis are discussed.

Recurrence of primary biliary cirrhosis and development of autoimmune hepatitis after liver transplant: A blind histologic study

AIM

This long-term study aimed to evaluate recurrence and evolution of primary biliary cirrhosis (PBC) after orthotopic liver transplantation (OLT).

METHODS

We reviewed "blindly" allograft biopsy specimens of women who underwent transplantation for PBC (n = 84), and women who received a transplant for chronic hepatitis C virus infection (CHCV ) (n = 108). All needle liver biopsy specimens obtained more than 6 months post-OLT were examined, including 83 specimens from 44 PBC patients and 152 specimens from 58 CHCV patients.

RESULTS

Granulomatous destructive cholangitis was found in five biopsies from four PBC patients (P = 0.0048). Non-necrotizing epithelioid cell granulomas were present in four biopsies from four PBC patients, and in two biopsies from one CHCV patient. Piecemeal necrosis (P = 0.0002), lobular necroinflammatory activity (P < 0.0001), steatosis (P < 0.0001) and fibrosis (P < 0.0001) were more prevalent in CHCV patients than PBC patients. Four PBC patients developed histologic evidence of autoimmune hepatitis (AIH), at a mean time of 3.66 years post-OLT. One of these patients had histologic features of AIH/PBC overlap syndrome. All four patients developed bridging fibrosis (n = 2) or cirrhosis (n = 2). No other PBC patient had evidence of cirrhosis after OLT.

CONCLUSIONS

Histologic findings indicative of recurrent PBC were present in 15.9% of the PBC patients undergoing biopsy in this series. However, this group of patients did not suffer significant bile duct loss or fibrosis, as compared to the control group, suggesting that recurrent PBC is a mild or slowly progressive disease. Histologic evidence of AIH was observed in allograft biopsies of some PBC patients.

End-organ damage in a mouse model of fulminant liver inflammation requires CD4+ T cell production of IFN-gamma but is independent of Fas

Fulminant inflammation in the liver is often accompanied by the accumulation of IFN-gamma-producing T cells. The BALB/c-Tgfb1(-/-) mouse exhibits extensive, spontaneously developing necroinflammation in the liver, accompanied by the accumulation of IFN-gamma-producing CD4(+) and CD8(+) T cells. Liver damage depends on the presence of an intact Ifng gene. We determined the relevant cellular source(s) of IFN-gamma. In Tgfb1(-/-) liver, CD4(+) T cells were more numerous than CD8(+) T cells and NK cells, and produced more IFN-gamma. Depletion of CD4(+) T cells eliminated both the elevation in plasma IFN-gamma and aspartate aminotransferase, whereas depletion of CD8(+) T cells did not. Rag1(-/-)Tgfb1(-/-) mice exhibited neither IFN-gamma elevation nor tissue damage, indicating that NK cells are not sufficient. IFN-gamma was required for strong overexpression of class II genes but not for CD4(+) T cell activation, oligoclonal expansion, or accumulation in the liver. The T cell inhibitory molecule PD-L1 was strongly expressed in Tgfb1(-/-) livers, ruling out a lack of PD-L1 expression as an explanation for aberrant liver T cell activation. Finally, whereas Tgfb1(-/-) CD4(+) T cells overexpressed Fas ligand, hepatocellular damage was observed in Fas(lpr/lpr)Tgfb1(-/-) mice, indicating that liver pathology is Fas independent. We conclude that liver damage in this model of fulminant autoimmune hepatitis is driven by CD4(+) T cell production of IFN-gamma, is independent of both CD8(+) T cells and the Fas ligand/Fas pathway, and is not explained by a lack of PD-L1 expression.

Fulminant autoimmune hepatitis in a girl with 22q13 deletion syndrome: a previously unreported association

We report a 7-year-old girl with 22q13 deletion syndrome, 46,XX,Ish del(22)(q13.3)(ARSA-; D22S1726), who developed a fulminant autoimmune hepatitis requiring orthotopic liver transplantation. Recently, it has been suggested that the Shank3 gene product, whose deficiency is responsible for the features observed in this syndrome, could play a role in immunological response. Despite an increased incidence of respiratory infections, autoimmune diseases have thus far not been reported in patients with this syndrome. This is the first case of fulminant autoimmune hepatitis associated with the 22q13 deletion syndrome. The possible relationships between immune system dysfunctions peculiar of this syndrome and autoimmune hepatitis are discussed.

Serum autoantibodies: a road map for the clinical hepatologist

The widespread use of serum autoantibodies in the practice of clinical hepatology has led to novel challenges in the interpretation of results obtained with routine techniques, such as indirect immunofluorescence (IIF) or with recombinant antigens. In fact, the laboratory methods are often overlooked factors in the interpretation of data by the bedside clinician despite being critical in the interpretation of data. Importantly, the sensitivity and specificity of these serum hallmarks are not defined in all cases. Taken altogether, these observations point towards the need for a systematic discussion of autoimmune serology in the clinical setting of everyday practice. The target of this review article is therefore, to illustrate the current knowledge and available experimental evidence to guide the diagnostic and prognostic decision making in autoimmune and viral chronic liver diseases.

Mapping the human proteome for non-redundant peptide islands

We describe immune-proteome structures using libraries of protein fragments that define a structural immunological alphabet. We propose and validate such an alphabet as i) composed of letters of five consecutive amino acids, pentapeptide units being sufficient minimal antigenic determinants in a protein, and ii) characterized by low-similarity to human proteins, so representing structures unknown to the host and potentially able to evoke an immune response. In this context, we have thoroughly sifted through the entire human proteome searching for non-redundant protein motifs. Here, for the first time, a complete sequence redundancy dissection of the human proteome has been conducted. The non-redundant peptide islands in the human proteome have been quantified and catalogued according to the amino acid length. The library of uniquely occurring n-peptide sequences that was obtained is characterized by a logarithmic decrease of the number of non-redundant peptides as a function of the peptide length. This library represents a highly specific catalogue of molecular protein signatures, the possible use of which in cancer/autoimmunity research is discussed, with a major focus on non-redundant dodecamer sequences.

Rejection and steroid dependence: unique risk factors in the development of pediatric posttransplant de novo autoimmune hepatitis

Posttransplant de novo autoimmune hepatitis (d-AIH) is increasingly described as a long-term complication after pediatric liver transplantation (LT). d-AIH is characterized by graft dysfunction, the development of autoimmune antibodies and histologic evidence of hepatitis in liver transplant recipients without previous history of autoimmune liver disease. This study is a matched case-control, univariate analysis aimed at identifying risk factors for the development of d-AIH and evaluating response to treatment. From 1984 to 2003, 619 children received 788 LTs at a single center. Forty-one patients developed d-AIH and were matched with controls for year of LT, age at time of LT and diagnosis. The following variables were insignificant in the development of d-AIH: age, gender, race, initial diagnosis, ischemia time, graft type, Epstein-Barr virus and cytomegalovirus status, HLA typing and primary immunosuppression. Compared to controls, d-AIH patients were less likely to be on monotherapy immunosuppression or weaned off prednisone at the time of diagnosis. The d-AIH group relative to the controls had statistically significant greater numbers of rejection episodes. d-AIH was treated with prednisone and/or MMF in 39 of 41 patients and lead to significant improvements in liver function tests. Thirty-nine patients are alive at a mean of 4.0 years follow-up after diagnosis. Three have required retransplantation.

Autoimmune hepatitis in children: diagnosis, pathology and treatment

Autoimmune hepatitis (AIH) is characterized by progressive inflammation of the liver and destruction of liver parenchyma. Rare in absolute terms, it is nevertheless an important cause of noninfectious chronic liver disease in children. In many ways, the diagnosis and treatment of children with AIH has changed little over the last 10 years. However, in recent years, steady progress in defining the genetic, immunologic and potential environmental triggers that underlie this disease, in addition to increasing experience with a wider array of therapeutic agents, promises to expand our understanding and ability to treat AIH effectively. This review will summarize the current clinical and pathophysiological understanding of AIH in children, along with therapeutic options.

Acute liver failure in children

Acute liver failure (ALF) is a rare but devastating illness. Specific therapy to promote liver recovery is often not available, and the underlying cause of the liver failure is often unknown. This article examines current knowledge of the epidemiology, pathobiology, and treatment of ALF in children and identifies potential gaps in this knowledge for future study.

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