Increased prevalence of seropositivity for non-gastric Helicobacter species in patients with autoimmune liver disease

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Abstract
Various Helicobacter species have been isolated from the stomach, intestinal tract and liver of a variety of mammalian and some avian species, and Helicobacter DNA has been detected in human bile and liver samples. An immunoblot assay was established to analyse serum antibody responses to non-gastric Helicobacter species in patients with autoimmune liver diseases, in comparison with healthy individuals. Sera from 36 patients with primary sclerosing cholangitis (PSC), 21 with primary biliary cirrhosis, 19 with autoimmune chronic hepatitis and 80 blood donors were analysed by immunoblot, using cell-surface proteins from Helicobacter pullorum, Helicobacter bilis and Helicobacter hepaticus as antigens. Prior to testing, sera were cross-absorbed with a whole-cell lysate of Helicobacter pylori. Antibody reactivity to various proteins of these three Helicobacter species was measured by densitometric scanning and results were processed by computer software to estimate antigenic specificity. Results were also compared with antibody response to H. pylori. For H. pullorum, reactivity to at least two of the proteins with molecular masses of 48, 45, 37, 20 and 16 kDa, for H. hepaticus, reactivity to the 76, 30 and 21 kDa proteins and for H. bilis, reactivity to the 22 and 20 kDa proteins, seemed to have high specificity. Positive immunoblot results with sera from patients with PSC to antigens of H. pullorum, H. bilis and H. hepaticus were found in 38, 22 and 25 % of cases, respectively, and from patients with other autoimmune liver diseases, in 30, 22 and 22 % of cases, respectively. Prevalence of serum antibodies to non-gastric Helicobacter species was significantly higher in patients with autoimmune chronic liver diseases than in healthy blood donors (P < 0.001). Increased antibody levels to enterohepatic Helicobacter species raise questions concerning an infectious role of these emerging bacterial pathogens in human autoimmune liver diseases.