title: Sphingosine-1-Phosphate Prevents Egress of Hematopoietic Stem Cells From Liver to Reduce Fibrosis.
abstract: There is growing interest in the use of bone marrow cells to treat liver fibrosis, however, little is known about their antifibrotic efficacy or the identity of their effector cell(s). Sphingosine-1-phosphate (S1P) mediates egress of immune cells from the lymphoid organs into the lymphatic vessels; we investigated its role in the response of hematopoietic stem cells (HSCs) to liver fibrosis in mice.
  
  
  
  Purified (c-kit+/sca1+/lin-) HSCs were infused repeatedly into mice undergoing fibrotic liver injury. Chronic liver injury was induced in BoyJ mice by injection of carbon tetrachloride (CCl4) or placement on a methionine-choline-deficient diet. Some mice were irradiated and given transplants of bone marrow cells from C57BL6 mice, with or without the S1P antagonist FTY720; we then studied HSC mobilization and localization. Migration of HSC lines was quantified in Transwell assays. Levels of S1P in liver, bone marrow, and lymph fluid were measured using an enzyme-linked immunosorbent assay. Liver tissues were collected and analyzed by immunohistochemical quantitative polymerase chain reaction and sphingosine kinase activity assays. We performed quantitative polymerase chain reaction analyses of the expression of sphingosine kinase 1 and 2, sphingosine-1-phosphate lyase 1, and sphingosine-1-phosphate phosphatase 1 in normal human liver and cirrhotic liver from patients with alcohol-related liver disease (n = 6).
  
  
  
  Infusions of HSCs into mice with liver injury reduced liver scarring based on picrosirius red staining (49.7% reduction in mice given HSCs vs control mice; P < .001), and hepatic hydroxyproline content (328 mg/g in mice given HSCs vs 428 mg/g in control mice; P < .01). HSC infusion also reduced hepatic expression of α-smooth muscle actin (0.19 ± 0.007-fold compared with controls; P < .0001) and collagen type I α 1 chain (0.29 ± 0.17-fold compared with controls; P < .0001). These antifibrotic effects were maintained with infusion of lymphoid progenitors that lack myeloid potential and were associated with increased numbers of recipient neutrophils and macrophages in liver. In studies of HSC cell lines, we found HSCs to recruit monocytes, and this process to require C-C motif chemokine receptor 2. In fibrotic liver tissue from mice and patients, hepatic S1P levels increased owing to increased hepatic sphingosine kinase-1 expression, which contributed to a reduced liver:lymph S1P gradient and limited HSC egress from the liver. Mice given the S1P antagonist (FTY720) with HSCs had increased hepatic retention of HSCs (1697 ± 247 cells in mice given FTY720 vs 982 ± 110 cells in controls; P < .05), and further reductions in fibrosis.
  
  
  
  In studies of mice with chronic liver injury, we showed the antifibrotic effects of repeated infusions of purified HSCs. We found that HSCs promote recruitment of endogenous macrophages and neutrophils. Strategies to reduce SIP signaling and increase retention of HSCs in the liver could increase their antifibrotic activities and be developed for treatment of patients with liver fibrosis.
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom. Electronic address: andyking@doctors.org.uk.
authors.forename: Andrew
authors.initials: A
authors.lastname: King
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Diarmaid D
authors.initials: DD
authors.lastname: Houlihan
authors.affiliation: Centre for Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Dean
authors.initials: D
authors.lastname: Kavanagh
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Debashis
authors.initials: D
authors.lastname: Haldar
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Nguyet
authors.initials: N
authors.lastname: Luu
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Owen
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Shankar
authors.initials: S
authors.lastname: Suresh
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Nwe Ni
authors.initials: NN
authors.lastname: Than
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Gary
authors.initials: G
authors.lastname: Reynolds
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Jasmine
authors.initials: J
authors.lastname: Penny
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Henry
authors.initials: H
authors.lastname: Sumption
authors.affiliation: Medical Research Council Centre for Inflammation Research, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Prakash
authors.initials: P
authors.lastname: Ramachandran
authors.affiliation: Medical Research Council Centre for Inflammation Research, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Neil C
authors.initials: NC
authors.lastname: Henderson
authors.affiliation: Centre for Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Neena
authors.initials: N
authors.lastname: Kalia
authors.affiliation: School Institute of Immunology and Immunotherapy, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Jon
authors.initials: J
authors.lastname: Frampton
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom.
authors.forename: David H
authors.initials: DH
authors.lastname: Adams
authors.affiliation: Birmingham Liver Biomedical Research Unit, National Institute for Health Research, Centre for Liver Research, University of Birmingham, Birmingham, United Kingdom. Electronic address: P.N.Newsome@bham.ac.uk.
authors.forename: Philip N
authors.initials: PN
authors.lastname: Newsome
mesh_terms: D000199:Actins / Q000378:metabolism; D000446:Aldehyde-Lyases / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects*; D056487:Chemical and Drug Induced Liver Injury, Chronic / Q000150:complications; D024042:Collagen Type I / Q000378:metabolism; D000090602:Collagen Type I, alpha 1 Chain; D005260:Female; D000068876:Fingolimod Hydrochloride / Q000627:therapeutic use; D015870:Gene Expression; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008103:Liver Cirrhosis / Q000209:etiology / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*; D008196:Lymph / Q000378:metabolism; D008246:Lysophospholipids / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D008264:Macrophages; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D009000:Monocytes; D009504:Neutrophils; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism; D000099157:Sphingosine Kinase
chemical_list: D000199:Actins; D000446:Aldehyde-Lyases; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D000068876:Fingolimod Hydrochloride; D007166:Immunosuppressive Agents; D008246:Lysophospholipids; D008565:Membrane Proteins; D010744:Phosphoric Monoester Hydrolases; D017853:Phosphotransferases (Alcohol Group Acceptor); D013110:Sphingosine; D000099157:Sphingosine Kinase; C000716127:COL1A1 protein, human; C544013:alpha-smooth muscle actin, mouse; C060506:sphingosine 1-phosphate; C401298:sphingosine-1-phosphate phosphatase; C022649:sphingosine 1-phosphate lyase (aldolase)
keywords: CCR2; Immune Cell Localization; Mouse Model; Sphingolipid