Background: Primary biliary cirrhosis (PBC) is an autoimmune liver disease targeting the intrahepatic small bile ducts showing chronic non-suppurative destructive cholangitis (CNSDC). Recent studies suggest that naturally-occurring CD4+CD25high regulatory T cells (Tregs) expressing Forkhead box P3 (Foxp3) play an active role in immunological self-tolerance.
Aims: To investigate whether Foxp3+Tregs are involved in the pathogenesis of PBC.
Methods: Foxp3+Tregs was detected immunohistochemically in livers from patients with PBC (n = 27), chronic viral hepatitis (CVH) (n = 15), and normal subjects (n = 10). The distribution of Tregs in portal tracts was semi-quantitatively evaluated in each groups. Levels of Foxp3, IL-10, TGFβ, IFNγ and TNFα mRNA was evaluated in PBC (n = 15) and control livers (n = 21) using semi-quantitative reverse transcriptase-PCR.
Results: In PBC and CVH livers, the amounts of infiltrating Foxp3+Tregs in portal tracts were in parallel with the degree of portal inflammation irrespective of disease. The infiltration of Foxp3+Tregs into portal tracts with CNSDC in PBC was foremost in comparison with inflamed portal tracts in CVH or those without CNSDC in PBC (p<0.05). Focally, Tregs infiltrated into the biliary epithelial layer at the site of CNSDC. The level of Foxp3, IL-10 and TGFβ mRNA expression was high in PBC compared with normal livers (p<0.05). IFNγ and TNFα mRNA was high in early PBC and CVH livers.
Conclusion: Results of this evaluation of Foxp3+Tregs do not suggest that the reduced regulatory function accounts for the development of CNSDC in PBC.
- primary biliary cirrhosis
- regulatory T cells
- CNSDC, chronic non-suppurative destructive cholangitis
- CVH, chronic viral hepatitis
- Foxp3, Forkhead box P3
- IL, interleukin
- IFN, interferon
- PBC, primary biliary cirrhosis
- RT, reverse transcriptase
- TGF, transforming growth factor
- Th, T helper
- TNF, tumour necrosis factor
- Tregs, regulatory T cells
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Competing interests: None declared.