International Journal of Hepatology

International Journal of Hepatology / 2012 / Article
Special Issue

Cholangiopathy: Genetics, Mechanism, and Pathology

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Research Article | Open Access

Volume 2012 |Article ID 102839 |

Shinji Shimoda, Carlo Selmi, M. Eric Gershwin, "Fractalkine and Other Chemokines in Primary Biliary Cirrhosis", International Journal of Hepatology, vol. 2012, Article ID 102839, 5 pages, 2012.

Fractalkine and Other Chemokines in Primary Biliary Cirrhosis

Academic Editor: Yoshiyuki Ueno
Received12 May 2011
Accepted15 Jun 2011
Published09 Aug 2011


Primary biliary cirrhosis (PBC) is characterized by the autoimmune injury of small intrahepatic bile duct. On this basis, it has been suggested that the targeted biliary epithelial cells (BEC) play an active role in the perpetuation of autoimmunity by attracting immune cells via chemokine secretion. To address this issue, we challenged BEC using multiple toll-like receptor (TLR) ligands as well as autologous liver infiltrating mononuclear cells (LMNC) with subsequent measurement of BEC phenotype and chemokine production and LMNC chemotaxis by quantifying specific chemokines, specially CX3CL1 (fractalkine). We submit the hypothesis that BEC are in fact the innocent victims of the autoimmune injury and that the adaptive immune response is critical in PBC.

1. Introduction

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease recognized at histology as chronic nonsuppurative destructive cholangitis with an autoimmune pathogenesis supported by Th1 or Th17 cells producing IFN-γ or IL-17 [1, 2]. Several inflammatory cell populations, including T and B cells, are found around the affected intrahepatic bile ducts, and chemokines are believed to play a pivotal role for the infiltration of inflammatory cells [3].

A better understanding of the role of specific chemokines in liver injury is ancillary to understanding the molecular mechanisms regulating the autoimmunity process and is expected to unravel new strategies to treat PBC.

The observed patterns of chemokine expression in normal and PBC liver are illustrated in Table 1 [4]. In our recent experiments, we cultured EpCAM-positive cells (i.e., biliary epithelial cells and BEC) isolated by immunobeads from explanted liver tissue and examined the production of chemokines by protein array following the stimulation by inflammatory cytokines or Toll-like receptor (TLR) ligands [5]. Our data illustrated that BEC produce proinflammatory chemokines such as CXCL1, CXCL5, CXCL6, and CXCL8 without any specific stimulation as shown in Figure 1. On the other hand, BEC challenged with a TLR3 ligand (poly I : C) manifest a Th1 shift and the production of CCL3, CCL4, CCL5, and CXCL10. Such production of Th1 chemokines was further prompted by the interaction between CD40 on BEC and CD154 on liver infiltrating lymphocytes. Taken altogether, the evidence support the observation that BEC induces a proinflammatory environment in the absence of innate immunity stimulation and induces Th1-sifted environment when such stimulation is present.

ChemokinePortal veinSinusoidal ECBile duct

CXCL9 ± +(?) ± ND+
CXCL10 ± +(?) ± ND+

2. Fractalkine

Fractalkine is characterized as a type-1 transmembrane molecule with the chemokine domain tethered by a 241-amino acid glycosylated stalk, a 19-amino acid transmembrane region, and 37-amino acid intracellular tail [6]. The surface-expressed transmembrane fractalkine induces the firm adhesion of leukocytes expressing its receptor CX3CR1. After shedding by the disintegrins and metalloproteinases (ADAM) 10 and 17, fractalkine also acts as a soluble leukocyte chemoattractant. Transmembrane fractalkine expressed on both endothelial and epithelial cells induces leukocyte transmigration [7]. Fractalkine is upregulated by inflammation cytokines such as TNF-α or IFN-γ, it has been proposed to contribute to inflammatory diseases by promoting the transmigration of CX3CR1-expressing cells to inflamed tissues in Crohn disease [8], rheumatoid arthritis, atherosclerosis [9], systemic lupus erythematosus [10], and most recently PBC [5]. CX3CR1 is expressed on natural killer cells, monocytes, macrophages, mucosal dendritic cells, CD8+ T cells, and a subset of effector-memory CD4+ T cells [11, 12]. Human Th1 cells express high levels of CX3CR1 mRNA, different from polarized Th2 cells [13, 14]. Fractalkine is expressed in limited amounts in the normal human liver, particularly near branches of the hepatic artery and in small bile ducts located at the interface between the portal tract and the hepatic lobule. In the case of acute or chronic viral hepatitis, fractalkine is detected in the areas of necrosis and inflammatory infiltration and also at the interface between the expanded portal tract and the regenerating nodule. Regenerating epithelial cells of the ductular reaction are also positive for fractalkine [15]. In kidney allograft transplantation, fractalkine is expressed in renal tubular epithelial cells, and the expression is upregulated by TNF-α, the recognized key proinflammatory cytokine in acute rejection [16]. The CD4+ and CD8+ T cells expressing CX3CR1 predominantly produce IFN-γ and TNF-α, and these T cells infiltrate the synovium in patients with rheumatoid arthritis [17]. In inflammatory bowel disease (IBD), intestinal microvascular endothelial cells produce high amounts of fractalkine, and IBD mucosa as well as periphery contained significantly more CX3CR1+ cells than control. Fractalkine is a major contributor to T- and monocytic-cell adhesion to endothelial cells [18]. In HCV infection, CX3CR1 is susceptible gene for hepatic fibrosis [19]. In mice models, it is unclear whether CX3CR1 positive cells are protective or trigger disease [2025].

3. Fractalkine and PBC

Fractalkine is peripherally expressed dominantly in patients with PBC, and is upregulated in BEC of the PBC liver. CX3CR1 is expressed on infiltrating lymphocytes in the portal tracts and on intraepithelial T cells of injured bile ducts [26]. BEC manifesting senescent features in damaged small bile ducts also overexpress fractalkine [27]. As previously introduced, in our recent work, we separated BEC as EpCAM positive and endothelial cells as CD31 positive by immunobeads and evaluated the production of fractalkine as chemokine by ELISA. Figure 2(a) illustrates the elevated production of fractalkine by endothelial cells challenged with TLR3 ligand (poly I : C) or TLR4 ligand (LPS). Conversely, BEC did not produce fractalkine with any other TLR ligand stimulation (Figure 2(b)), and this was not reversed with the addition of established inflammatory cytokines such as TNF-α or IFN-γ. Further, we investigated the production of fractalkine following the interaction between BEC or endothelial cells and liver infiltrating lymphocytes. As shown in Figure 3, mononuclear cells adhered with higher affinity to BEC compared to endothelial cells in the TLR4 ligand (LPS) stimulation, and this adherence was increased more in PBC than in other control diseases [5]. Fractalkine works to modulate inflammation in the BEC of PBC, thus suggesting that novel therapies to block fractalkine induced environment may prove beneficial. Based on our data, we propose a working model on the role of fractalkine as chemokine or cell adhesion molecule by vascular endothelial cells and BEC, summarized in Figure 4. First, fractalkine as chemokine from vascular endothelial cells stimulated via TLR3 or TLR4 induce CX3CR1 positive monocytes or NK cells. Second, fractalkine as cell adhesion molecule from TLR4-stimulated BEC recruit CX3CR1 positive cells around target cells. This mechanism may trigger the onset of chronic nonsuppurative destructive cholangitis and autoimmune mechanism perpetuating the cholangitis. We further submit that Th1 chemokines produced by BEC stimulated from TLR3 are important contributors to the autoimmune mechanism.


  1. K. Harada, J. Van De Water, P. S. Leung et al., “In situ nucleic acid hybridization of cytokines in primary biliary cirrhosis: predominance of the Th1 subset,” Hepatology, vol. 25, no. 4, pp. 791–796, 1997. View at: Publisher Site | Google Scholar
  2. K. Harada, S. Shimoda, Y. Sato, K. Isse, H. Ikeda, and Y. Nakanuma, “Periductal interleukin-17 production in association with biliary innate immunity contributes to the pathogenesis of cholangiopathy in primary biliary cirrhosis,” Clinical and Experimental Immunology, vol. 157, no. 2, pp. 261–270, 2009. View at: Publisher Site | Google Scholar
  3. C. T. Wu, P. A. Davis, V. A. Luketic, and M. E. Gershwin, “A review of the physiological and immunological functions of biliary epithelial cells: targets for primary biliary cirrhosis, primary sclerosing cholangitis and drug-induced ductopenias,” Clinical and Developmental Immunology, vol. 11, no. 3-4, pp. 205–213, 2004. View at: Publisher Site | Google Scholar
  4. A. T. Borchers, S. Shimoda, C. Bowlus, C. L. Keen, and M. E. Gershwin, “Lymphocyte recruitment and homing to the liver in primary biliary cirrhosis and primary sclerosing cholangitis,” Seminars in Immunopathology, vol. 31, no. 3, pp. 309–322, 2009. View at: Publisher Site | Google Scholar
  5. S. Shimoda, K. Harada, H. Niiro et al., “CX3CL1 (fractalkine): a signpost for biliary inflammation in primary biliary cirrhosis,” Hepatology, vol. 51, no. 2, pp. 567–575, 2010. View at: Publisher Site | Google Scholar
  6. T. Imai, K. Hieshima, C. Haskell et al., “Identification and molecular characterization of fractalkine receptor CX3CR1, which mediates both leukocyte migration and adhesion,” Cell, vol. 91, no. 4, pp. 521–530, 1997. View at: Google Scholar
  7. J. F. Bazan, K. B. Bacon, G. Hardiman et al., “A new class of membrane-bound chemokine with a CX3C motif,” Nature, vol. 385, no. 6617, pp. 640–644, 1997. View at: Publisher Site | Google Scholar
  8. A. Muehlhoefer, L. J. Saubermann, X. Gu et al., “Fractalkine is an epithelial and endothelial cell-derived chemoattractant for intraepithelial lymphocytes in the small intestinal mucosa,” Journal of Immunology, vol. 164, no. 6, pp. 3368–3376, 2000. View at: Google Scholar
  9. T. Nanki, Y. Urasaki, T. Imai et al., “Inhibition of fractalkine ameliorates murine collagen-induced arthritis,” Journal of Immunology, vol. 173, no. 11, pp. 7010–7016, 2004. View at: Google Scholar
  10. N. Yajima, T. Kasama, T. Isozaki et al., “Elevated levels of soluble fractalkine in active systemic lupus erythematosus: potential involvement in neuropsychiatric manifestations,” Arthritis and Rheumatism, vol. 52, no. 6, pp. 1670–1675, 2005. View at: Publisher Site | Google Scholar
  11. F. Geissmann, S. Jung, and D. R. Littman, “Blood monocytes consist of two principal subsets with distinct migratory properties,” Immunity, vol. 19, no. 1, pp. 71–82, 2003. View at: Publisher Site | Google Scholar
  12. T. Imai, K. Hieshima, C. Haskell et al., “Identification and molecular characterization of fractalkine receptor CX3CR1, which mediates both leukocyte migration and adhesion,” Cell, vol. 91, no. 4, pp. 521–530, 1997. View at: Google Scholar
  13. P. Fraticelli, M. Sironi, G. Bianchi et al., “Fractalkine (CX3CL1) as an amplification circuit of polarized Th1 responses,” Journal of Clinical Investigation, vol. 107, no. 9, pp. 1173–1181, 2001. View at: Google Scholar
  14. M. Nishimura, H. Umehara, T. Nakayama et al., “Dual functions of fractalkine/CX3C ligand 1 in trafficking of perforin+/granzyme B+ cytotoxic effector lymphocytes that are defined by Cx3CR1 expression,” Journal of Immunology, vol. 168, no. 12, pp. 6173–6180, 2002. View at: Google Scholar
  15. E. Efsen, C. Grappone, R. M. DeFranco et al., “Up-regulated expression of fractalkine and its receptor CX3CR1 during liver injury in humans,” Journal of Hepatology, vol. 37, no. 1, pp. 39–47, 2002. View at: Publisher Site | Google Scholar
  16. S. J. Chakravorty, P. Cockwell, J. Girdlestone, C. J. Brooks, and C. O. S. Savage, “Fractalkine expression on human renal tubular epithelial cells: potential role in mononuclear cell adhesion,” Clinical and Experimental Immunology, vol. 129, no. 1, pp. 150–159, 2002. View at: Publisher Site | Google Scholar
  17. T. Nanki, T. Imai, K. Nagasaka et al., “Migration of CX3CR1-positive T cells producing type 1 cytokines and cytotoxic molecules into the synovium of patients with rheumatoid arthritis,” Arthritis and Rheumatism, vol. 46, no. 11, pp. 2878–2883, 2002. View at: Publisher Site | Google Scholar
  18. M. Sans, S. Danese, C. de la Motte et al., “Enhanced recruitment of CX3CR1+ T cells by mucosal endothelial cell-derived fractalkine in inflammatory Bowel disease,” Gastroenterology, vol. 132, no. 1, pp. 139–153, 2007. View at: Publisher Site | Google Scholar
  19. H. E. Wasmuth, M. M. Zaldivar, M. L. Berres et al., “The fractalkine receptor CX3CR1 is involved in liver fibrosis due to chronic hepatitis C infection,” Journal of Hepatology, vol. 48, no. 2, pp. 208–215, 2008. View at: Publisher Site | Google Scholar
  20. M. Inui, Y. Ishida, A. Kimura, Y. Kuninaka, N. Mukaida, and T. Kondo, “Protective roles of CX3CR1-mediated signals in toxin A-induced enteritis through the induction of heme oxygenase-1 expression,” Journal of Immunology, vol. 186, no. 1, pp. 423–431, 2011. View at: Publisher Site | Google Scholar
  21. T. Aoyama, S. Inokuchi, D. A. Brenner, and E. Seki, “CX3CL1-CX3CR1 interaction prevents carbon tetrachloride-induced liver inflammation and fibrosis in mice,” Hepatology, vol. 52, no. 4, pp. 1390–1400, 2010. View at: Publisher Site | Google Scholar
  22. C. Mionnet, V. Buatois, A. Kanda et al., “CX3CR1 is required for airway inflammation by promoting T helper cell survival and maintenance in inflamed lung,” Nature Medicine, vol. 16, no. 11, pp. 1305–1312, 2010. View at: Publisher Site | Google Scholar
  23. S. Lee, N. H. Varvel, M. E. Konerth et al., “CX3CR1 deficiency alters microglial activation and reduces beta-amyloid deposition in two Alzheimer's disease mouse models,” American Journal of Pathology, vol. 177, no. 5, pp. 2549–2562, 2010. View at: Publisher Site | Google Scholar
  24. M. Fuhrmann, T. Bittner, C. K. Jung et al., “Microglial Cx3cr1 knockout prevents neuron loss in a mouse model of Alzheimer's disease,” Nature Neuroscience, vol. 13, no. 4, pp. 411–413, 2010. View at: Publisher Site | Google Scholar
  25. K. R. Karlmark, H. W. Zimmermann, C. Roderburg et al., “The fractalkine receptor CX3CR1 protects against liver fibrosis by controlling differentiation and survival of infiltrating hepatic monocytes,” Hepatology, vol. 52, no. 5, pp. 1769–1782, 2010. View at: Publisher Site | Google Scholar
  26. K. Isse, K. Harada, Y. Zen et al., “Fractalkine and CX3CR1 are involved in the recruitment of intraepithelial lymphocytes of intrahepatic bile ducts,” Hepatology, vol. 41, no. 3, pp. 506–516, 2005. View at: Publisher Site | Google Scholar
  27. M. Sasaki, M. Miyakoshi, Y. Sato, and Y. Nakanuma, “Modulation of the microenvironment by senescent biliary epithelial cells may be involved in the pathogenesis of primary biliary cirrhosis,” Journal of Hepatology, vol. 53, no. 2, pp. 318–325, 2010. View at: Publisher Site | Google Scholar

Copyright © 2012 Shinji Shimoda et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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