Peptide antibiotic human beta-defensin-1 and -2 contribute to antimicrobial defense of the intrahepatic biliary tree.
Human beta-defensins (hBDs) are important antimicrobial peptides that contribute to innate immunity at mucosal surfaces. This study was undertaken to investigate the expression of hBD-1 and hBD-2 in intrahepatic biliary epithelial cells in specimens of human liver, and 4 cultured cell lines (2 consisting of biliary epithelial cells and 2 cholangiocarcinoma cells). In addition, hBD-1 and hBD-2 were assayed in specimens of bile. hBD-1 was nonspecifically expressed immunohistochemically in intrahepatic biliary epithelium and hepatocytes in all patients studied, but expression of hBD-2 was restricted to large intrahepatic bile ducts in 8 of 10 patients with extrahepatic biliary obstruction (EBO), 7 of 11 with hepatolithiasis, 1 of 6 with primary biliary cirrhosis (PBC), 1 of 5 with primary sclerosing cholangitis (PSC), 0 of 6 with chronic hepatitis C (CH-C), and 0 of 11 with normal hepatic histology. hBD-2 expression was evident in bile ducts exhibiting active inflammation. Serum C reactive protein levels correlated with biliary epithelial expression of hBD-2. Real-time PCR revealed that in all of 28 specimens of fresh liver, including specimens from patients with hepatolithiasis, PBC, PSC, CH-C and normal hepatic histology, hBD-1 messenger RNA was consistently expressed, whereas hBD-2 messenger RNA was selectively expressed in biliary epithelium of patients with hepatolithiasis. Immunobloting analysis revealed hBD-2 protein in bile in 1 of 3 patients with PSC, 1 of 3 with PBC, and each of 6 with hepatolithiasis; in contrast, hBD-1 was detectable in all bile samples examined. Four cultured biliary epithelial cell lines consistently expressed hBD-1; in contrast these cell lines did not express hBD-2 spontaneously but were induced to express hBD-2 by treatment with Eschericia coli, lipopolysaccharide, interleukin-1beta or tumor necrosis factor-alpha. In conclusion, these findings suggest that in the intrahepatic biliary tree, hBD-2 is expressed in response to local infection and/or active inflammation, whereas hBD-1 may constitute a preexisting component of the biliary antimicrobial defense system.
Harada
Kenichi
K
Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan.
Ohba
Kazuo
K
Ozaki
Satoru
S
Isse
Kumiko
K
Hirayama
Toshiya
T
Wada
Akihiro
A
Nakanuma
Yasuni
Y
D000328:Adult; D000368:Aged; D001646:Bile / Q000378:metabolism; D001649:Bile Duct Diseases / Q000378:metabolism / Q000503:physiopathology*; D001650:Bile Duct Neoplasms; D001653:Bile Ducts, Intrahepatic / Q000166:cytology / Q000378:metabolism*; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D006801:Humans; D017403:In Situ Hybridization; D008107:Liver Diseases / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D023083:beta-Defensins / Q000235:genetics* / Q000378:metabolism*
C406407:DEFB1 protein, human; C106641:DEFB4A protein, human; D012333:RNA, Messenger; D023083:beta-Defensins