title: CX3CL1 (fractalkine) and TNFα production by perfused human placental lobules under normoxic and hypoxic conditions in vitro: the importance of CX3CR1 signaling.
abstract: OBJECTIVE
  Inflammation and hypoxia activate the fractalkine (CX3CL1) receptor (CX3CR1)-related signaling pathway. Tumor necrosis factor alpha (TNFα) induces CX3CL1, influencing a mechanism of CX3CL1 autoregulation by CX3CR1 expression. We compared spontaneous and lipopolysaccharide (LPS)-induced CX3CL1 and TNFα production by human placenta under normoxic vs. hypoxic conditions, with respect to CX3CR1 expression and its functional status.
  
  
  METHODS
  Placental lobules of term placentae (N = 24) were perfused extracorporeally. CX3CL1 and TNFα concentrations were measured in the perfusion fluid by ELISA. LPS, anti-CX3CR1 antibodies and pirfenidone were used in respective subgroups. After perfusion, CX3CR1 expression was estimated in placental tissue using quantitative immunohistochemistry, and the final results were adjusted for the mean microvascular density.
  
  
  RESULTS
  The highest increase in CX3CL1 concentration in response to LPS was observed in hypoxia (p < 0.05). Unlike in normoxia, anti-CX3CR1 administration in hypoxia significantly reduced the LPS-evoked response. CX3CR1 expression was augmented by hypoxia and reached 260.9 ± 41 (% ±SEM) of the reference value in normoxia. Positive immunostaining for CX3CR1 corresponded to the vascular endothelium. Pirfenidone inhibited hypoxia + LPS-related increase in TNFα production and prevented the up-regulation of CX3CR1.
  
  
  CONCLUSIONS
  The modulatory influence of TNFα on CX3CR1 expression in hypoxia and CX3CL1/CX3CR1 interaction may serve as a compensatory mechanism to preserve or augment the pro-inflammatory course of intercellular interactions in placental endothelium.
authors.affiliation: Department of General and Experimental Pathology, Second Faculty of Medicine, Medical University of Warsaw, ul. Krakowskie Przedmiescie 26/28, 00-928, Warsaw, Poland, Dszukiewicz@hotmail.com.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Szukiewicz
authors.forename: Jan
authors.initials: J
authors.lastname: Kochanowski
authors.forename: Tarun Kumar
authors.initials: TK
authors.lastname: Mittal
authors.forename: Michal
authors.initials: M
authors.lastname: Pyzlak
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Szewczyk
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Cendrowski
mesh_terms: D000328:Adult; D000073883:CX3C Chemokine Receptor 1; D002196:Capillaries / Q000033:anatomy & histology / Q000502:physiology; D054428:Chemokine CX3CL1 / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology; D010477:Perfusion; D010920:Placenta / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D019707:Receptors, Chemokine / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D000073883:CX3C Chemokine Receptor 1; C095235:CX3CR1 protein, human; D054428:Chemokine CX3CL1; D008070:Lipopolysaccharides; D019707:Receptors, Chemokine; D014409:Tumor Necrosis Factor-alpha