Prevalence of antibodies to hepatitis C and herpes simplex virus type 1 is not increased in children with liver kidney microsomal type 1 autoimmune hepatitis

Seronegative autoimmune hepatitis in children : A real diagnostic challenge

BACKGROUND AND AIM

Classical autoimmune hepatitis (AIH) is characterized by the presence of conventional autoantibodies (anti-smooth muscle, antinuclear and anti-liver-kidney-microsomal antibodies). The absence of such autoantibodies in some patients does not preclude AIH diagnosis or the need for its treatment. This group of patients was termed seronegative AIH. Whether non-conventional autoantibodies can identify this group of patients is still elusive. We aimed to study the prevalence of seronegativity of conventional autoantibodies and the occurrence of non-conventional autoantibodies in children with AIH.

METHODS

In this study, 55 children with AIH were investigated for non-conventional autoantibodies (anti-neutrophil cytoplasmic antibodies, antibodies to soluble liver antigen, anti-tissue transglutaminase and antiplatelet antibodies). All the patients received immunosuppressive therapy and were assessed for treatment response.

RESULTS

Of the patients 44 had classical AIH (type 1, 70.09%, type 2, 9.09%) and 20% were seronegative. The four studied non-conventional autoantibodies occurred in four patients, one for each. All non-conventional autoantibodies were exclusively associated with type 1 AIH. The clinical profile, ultrasonographic findings, liver biochemistry and histopathological findings were comparable in the classical and seronegative AIH. The majority of patients with classical (72.7%) and seronegative (54.5%) AIH were treatment responders.

CONCLUSION

Seronegative AIH represents a substantial percentage of pediatric patients diagnosed with AIH. They were even negative for non-conventional autoantibodies. Furthermore, apart from autoantibodies, seronegative AIH is almost indistinguishable from the classical AIH and the majority of patients were treatment responders. This favorable response to immunosuppression deserves sustainable efforts for considering such a diagnosis and start therapy to halt disease progression is worthwhile.

Increased seroprevalence of HAV and parvovirus B19 in children and of HEV in adults at diagnosis of autoimmune hepatitis

Preceding viral infections have mostly been described in autoimmune hepatitis (AIH) in single cases. We aimed to identify viral infections that potentially trigger AIH, as suggested for hepatitis E virus (HEV) infections. Therefore, antibodies against hepatitis A (HAV), B, C and E viruses; hepatotropic herpesviruses; and parvovirus B19 (PVB19) were analyzed retrospectively in 219 AIH patients at diagnosis, 356 patients with other liver diseases and 89 children from our center. Untreated adult AIH (aAIH) patients showed higher anti-HEV seroprevalences at diagnosis than patients with other liver diseases. Untreated aAIH patients had no increased incidence of previous hepatitis A, B or C. Antibodies against hepatotropic herpesviruses in untreated AIH were in the range published for the normal population. Untreated pediatric AIH (pAIH) patients had evidence of more previous HAV and PVB19 infections than local age-matched controls. The genetic AIH risk factor HLA DRB1*03:01 was more frequent in younger patients, and DRB1*04:01 was more frequent in middle-aged patients without an obvious link to virus seropositivities. Pediatric and adult AIH seem to be distinct in terms of genetic risk factors and preceding viral infections. While associations cannot prove causal relations, the results suggest that hepatotropic virus infections could be involved in AIH pathogenesis.

Is there a role for viruses in triggering autoimmune hepatitis?

A role for viruses in autoimmune hepatitis (AH) has been repeatedly proposed but convincing evidence links only two viruses, hepatitis A and Epstein-Barr virus, to the type 1 form of the disease, and only in those rare cases where a genetic predisposition exists and the viral infection occurs at the right time, i.e. when other unknown factors are cooperating. In spite of an impressive amount of information conclusively showing molecular mimicry between cytochrome P450IID6 (the target autoantigen of autoantibodies characteristic of AH type 2) sequences and viral (hepatitis C virus, herpes simplex virus 1, cytomegalovirus, human T lymphotropic viruses 1 and 2) or bacterial (Salmonella typhimurium) antigens, no infectious agent is clearly able to induce this second form of the disease. In conclusion, the molecular mimicry theory has so far found little clinical evidence in its support and many more clinical observations are needed in order to unreveal possible links between viruses and AH.

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Hepatitis GB virus-C/hepatitis G virus infection in liver disease

Hepatitis GB virus-C (HGBV-C)/hepatitis G virus (HGV) infection was investigated in 106 children with liver disease (54 boys and 52 girls, mean age 7.3 years); 12 with chronic hepatitis C virus infection, 29 with positive hepatitis B surface antigen, nine with idiopathic fulminant hepatic failure, seven with graft dysfunction after liver transplantation associated with autoimmune features, 20 with cryptogenic liver disease, and 29 with autoimmune liver disease. HGV RNA detected by reverse transcription polymerase chain reaction was found to be positive in 4/106 patients (3.8%). Risk factors were identified in three patients, including blood transfusion and/or medical treatment in Eastern Europe. The prevalence was higher than that of blood donors but lower than that of 2 adult patients with liver disease. HGV is not associated with any specific disease group and does not seem to be a major aetiological agent of liver disease in childhood in the UK.