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The immune response to mitochondrial autoantigens
Hiromi Ishibashi1, Shinji Shimoda, M Eric Gershwin
1Clinical Research Center, National Hospital Organization Nagasaki Medical Center, Nagasaki, Japan. hiishibashi-gi@umin.ac.jp
Seminars in Liver Disease
|September 7, 2005
Summary
Primary biliary cirrhosis (PBC) involves immune responses targeting mitochondria, specifically pyruvate dehydrogenase complex E2 (PDC-E2). This autoimmune attack, driven by T cells and antibodies, leads to biliary epithelial cell destruction.
Area of Science:
- Immunology
- Hepatology
- Autoimmunity
Background:
- Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by immune responses against self-antigens.
- Antimitochondrial antibodies (AMAs) are a hallmark of PBC, targeting the E2 subunit of pyruvate dehydrogenase complex (PDC-E2) located on the inner mitochondrial membrane.
Purpose of the Study:
- To elucidate the immunological mechanisms underlying the destruction of intrahepatic biliary epithelial cells (BECs) in PBC.
- To investigate the role of T cells and autoantibodies in PBC pathogenesis.
Main Methods:
- Analysis of humoral and cellular immune responses in PBC patients.
- Identification of autoantigens targeted by AMAs.
- Investigation of T cell responses against intrahepatic BECs.
Main Results:
- AMAs, primarily targeting PDC-E2, are present in 90-95% of PBC sera.
- Both CD4+ helper T cells and CD8+ cytotoxic T lymphocytes (CTLs) specific for 2-oxo-acid dehydrogenase complexes (2-OADCs) are implicated in BEC destruction.
- Environmental factors may trigger self-tolerance breakdown, leading to BEC damage and autoimmune responses.
Conclusions:
- The immune-mediated destruction of BECs in PBC involves a coordinated attack by T cells and autoantibodies against mitochondrial antigens.
- Initial BEC damage, possibly triggered by environmental factors, can initiate and perpetuate the autoimmune cascade in PBC.