Fractalkine and CX3CR1 are involved in the recruitment of intraepithelial lymphocytes of intrahepatic bile ducts.
Fractalkine is a chemokine with both chemoattractant and cell-adhesive functions, and in the intestine it is involved with its receptor CX3CR1 in the chemoattraction and recruitment of intraepithelial lymphocytes. We examined the pathophysiological roles of fractalkine and CX3CR1 in normal and diseased bile ducts. Expression of fractalkine and CX3CR1 were examined in liver tissues from patients with primary biliary cirrhosis (17 cases) and controls (9 cases of primary sclerosing cholangitis, 10 cases of extrahepatic biliary obstruction, 20 cases of chronic viral hepatitis C, and 18 cases of histologically normal livers). Expression of fractalkine in biliary epithelial cells (BECs) in response to cytokine treatments was examined using a human cholangiocarcinoma cell line (HuCC-T1) and human intrahepatic BEC line. The chemotaxis of CX3CR1-expressing monocytes (THP-1) toward fractalkine was assayed using chemotaxis chambers. Fractalkine messenger RNA/protein were expressed on BECs of normal and diseased bile ducts, and their expression was upregulated in injured bile ducts of primary biliary cirrhosis. CX3CR1 was expressed on infiltrating mononuclear cells in portal tracts and on CD3(+), CD4(+), and CD8(+) intraepithelial lymphocytes of injured bile ducts in primary biliary cirrhosis. Fractalkine messenger RNA expression was upregulated in two cultured BECs on treatment with lipopolysaccharide and Th1-cytokines (interleukin 1beta, interferon gamma, and tumor necrosis factor alpha). THP-1 cells showed chemotaxis toward fractalkine secreted by cultured cells. In conclusion, Th1-cytokine predominance and lipopolysaccharide in the microenvironment of injured bile ducts resulting from primary biliary cirrhosis induce the upregulation of fractalkine expression in BECs, followed by the chemoattraction of CX3CR1-expressing mononuclear cells, including CD4(+) and CD8(+) T cells, and their adhesion to BECs and the accumulation of biliary intraepithelial lymphocytes.
Isse
Kumiko
K
Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan.
Harada
Kenichi
K
Zen
Yoh
Y
Kamihira
Takashi
T
Shimoda
Shinji
S
Harada
Mine
M
Nakanuma
Yasuni
Y
D000368:Aged; D001653:Bile Ducts, Intrahepatic / Q000276:immunology*; D015153:Blotting, Western; D000073883:CX3C Chemokine Receptor 1; D002465:Cell Movement; D002478:Cells, Cultured; D054428:Chemokine CX3CL1; D020523:Chemokines, CX3C / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D002633:Chemotaxis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000494:pharmacology; D008214:Lymphocytes / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D008875:Middle Aged; D019707:Receptors, Chemokine / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000073883:CX3C Chemokine Receptor 1; C515538:CX3CL1 protein, human; C095235:CX3CR1 protein, human; D054428:Chemokine CX3CL1; D020523:Chemokines, CX3C; D007375:Interleukin-1; D008565:Membrane Proteins; D019707:Receptors, Chemokine; D014409:Tumor Necrosis Factor-alpha