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Deposition of C3, the terminal complement complex and vitronectin in primary biliary cirrhosis and primary sclerosing
P Garred1, H Lyon, P Christoffersen
1Department of Pathology, Hvidovre Hospital, Denmark.
Insights
Complement deposits were found in liver tissues of patients with primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). However, these deposits were not located around bile ducts, questioning their role in bile duct destruction.
Area of Science:
- Hepatology
- Immunology
- Pathology
Background:
- Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are characterized by bile duct destruction and portal inflammation.
- Elevated levels of complement activation products suggest a potential role for complement-dependent cytotoxicity in these diseases.
Purpose of the Study:
- To investigate the presence and location of complement deposits in liver biopsy specimens from patients with PBC and PSC.
- To determine if complement activation products are associated with bile duct destruction in these conditions.
Main Methods:
- Immunohistochemistry was used to detect complement deposits (C3d, terminal complement complex [TCC], vitronectin) in liver biopsy specimens.
- Specimens from 21 PBC patients, 6 PSC patients, and 6 controls were analyzed.
Main Results:
- C3d, TCC, and vitronectin deposits were found exclusively in portal tracts.
- C3d and TCC were present in hepatic arteries and connective tissue stroma, but not around bile ducts.
- Vitronectin deposits showed variable co-localization and inverse staining patterns with TCC, suggesting complex interactions.
Conclusions:
- The absence of complement deposits around bile ducts challenges the hypothesis that complement-dependent cytotoxic mechanisms directly cause bile duct destruction in PBC and PSC.
- Further research is needed to elucidate the precise role of complement in the pathogenesis of these cholestatic liver diseases.
Abstract:
Characteristics of primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are bile duct destruction and portal inflammation. Increased levels of circulating complement activation products are also present. This raises the possibility of involvement of complement-dependent cytotoxic mechanisms in the pathogenesis. Therefore, we investigated liver biopsy specimens from 21 patients with PBC, six patients with PSC and six controls for complement deposits by immunohistochemistry using polyclonal and monoclonal antibodies against C3d, the terminal complement complex (TCC) and vitronectin (S-protein). We found C3d, TCC and vitronectin deposits only in the portal tracts. C3d and TCC were present in the walls of the hepatic arteries and in the connective tissue stroma but never around the bile ducts. We found vitronectin deposits throughout the connective tissue, often independent of the TCC deposits. When vitronectin and TCC were co-localized, the staining patterns were inverse; that is, intense staining for TCC accompanied weak staining for vitronectin and vice versa. Occasionally complete dissociation between TCC and vitronectin staining was observed. Deposits of TCC and vitronectin showed a focal distribution leaving many portal tracts free of TCC. Our results question whether complement-dependent cytotoxic mechanisms take part in the bile duct destruction in PBC and PSC.