CX3CL1-CX3CR1 interaction prevents carbon tetrachloride-induced liver inflammation and fibrosis in mice.
Chronic liver disease is associated with hepatocyte injury, inflammation, and fibrosis. Chemokines and chemokine receptors are key factors for the migration of inflammatory cells such as macrophages and noninflammatory cells such as hepatic stellate cells (HSCs). The expression of CX3CR1 and its ligand, CX3CL1, is up-regulated in chronic liver diseases such as chronic hepatitis C. However, the precise role of CX3CR1 in the liver is still unclear. Here we investigated the role of the CX3CL1-CX3CR1 interaction in a carbon tetrachloride (CCl(4))-induced liver inflammation and fibrosis model. CX3CR1 was dominantly expressed in Kupffer cells in the liver. In contrast, the main source of CX3CL1 was HSCs. Mice deficient in CX3CR1 showed significant increases in inflammatory cell recruitment and cytokine production [including tumor necrosis factor α (TNF-α); monocyte chemoattractant protein 1; macrophage inflammatory protein 1β; and regulated upon activation, normal T cell expressed, and secreted (RANTES)] after CCl(4) treatment versus wild-type (WT) mice. This suggested that CX3CR1 signaling prevented liver inflammation. Kupffer cells in CX3CR1-deficient mice after CCl(4) treatment showed increased expression of TNF-α and transforming growth factor β and reduced expression of the anti-inflammatory markers interleukin-10 (IL-10) and arginase-1. Coculture experiments showed that HSCs experienced significantly greater activation by Kupffer cells from CCl(4)-treated CX3CR1-deficient mice versus WT mice. Indeed, augmented fibrosis was observed in CX3CR1-deficient mice versus WT mice after CCl(4) treatment. Finally, CX3CL1 treatment induced the expression of IL-10 and arginase-1 in WT cultured Kupffer cells through CX3CR1, which in turn suppressed HSC activation.


CONCLUSIONS
The CX3CL1-CX3CR1 interaction inhibits inflammatory properties in Kupffer cells/macrophages and results in decreased liver inflammation and fibrosis.
Aoyama
Tomonori
T
Division of Gastroenterology, Department of Medicine, University of California San Diego School of Medicine, La Jolla, CA 92093-0702, USA.
Inokuchi
Sayaka
S
Brenner
David A
DA
Seki
Ekihiro
E
D000818:Animals; D000073883:CX3C Chemokine Receptor 1; D002252:Carbon Tetrachloride Poisoning / Q000473:pathology* / Q000517:prevention & control; D002465:Cell Movement / Q000187:drug effects; D056486:Chemical and Drug Induced Liver Injury / Q000517:prevention & control*; D054428:Chemokine CX3CL1 / Q000502:physiology*; D018920:Coculture Techniques; D055166:Hepatic Stellate Cells / Q000378:metabolism; D016753:Interleukin-10 / Q000096:biosynthesis; D007728:Kupffer Cells / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D019707:Receptors, Chemokine / Q000502:physiology*; D015398:Signal Transduction
D000073883:CX3C Chemokine Receptor 1; D054428:Chemokine CX3CL1; C471885:Cx3cr1 protein, mouse; D019707:Receptors, Chemokine; D016753:Interleukin-10