title: Exogenous nitric oxide decreases brain vascular inflammation, leakage and venular resistance during Plasmodium berghei ANKA infection in mice.
abstract: BACKGROUND
  Cerebral malaria (CM) is a lethal complication of Plasmodium falciparum infections. In the Plasmodium berghei ANKA (PbA) murine model, CM is associated with marked brain inflammation, increased expression of endothelial cell adhesion molecules and leukocyte and platelet accumulation in brain vessels, causing vascular occlusion and decreased blood flow, damaging the endothelium and leading to blood-brain barrier breakdown, leakage and hemorrhages. Exogenous nitric oxide (NO) administration largely prevents the syndrome. Here we evaluated whether the mechanism of action of NO in preventing murine CM is related to its anti-inflammatory properties and to protection of the endothelium.
  
  
  METHODS
  C57Bl/6 mice infected with PbA were treated twice a day with saline or dipropylenetriamineNONOate (DPTA-NO). Endothelial cell adhesion molecule (ICAM-1, VCAM, E- and P-selectin) expression in brain tissue on day 6 of infection was assessed in both groups by western blot. For intravital microscopy studies, DPTA-NO-treated and saline-treated mice with a previously implanted closed cranial window were injected with albumin-FITC, anti-CD45-TxR and anti-CD41-FITC antibodies on day 6 of infection for quantification of albumin leakage, leukocyte and platelet adherence in pial vessels.
  
  
  RESULTS
  PbA-infected mice treated with the NO-donor DPTA-NO showed decreased expression of ICAM-1 and P-selectin, but not VCAM-1, in the brain, compared to saline-treated mice. DPTA-NO treatment also decreased the number of adherent leukocytes and platelets in pial vessels, particularly in venules 30-50 μm in diameter, decreased inflammatory vascular resistance and prevented the occurrence of arteriolar and venular albumin leakage observed in saline-treated PbA-infected mice, as assessed by intravital microscopy.
  
  
  CONCLUSIONS
  These results indicate that the protective effect of exogenous NO on murine CM is associated with decreased brain vascular expression of inflammatory markers resulting in attenuated endothelial junction damage and facilitating blood flow.
authors.affiliation: La Jolla Bioengineering Institute, San Diego, CA, USA.
authors.forename: Graziela M
authors.initials: GM
authors.lastname: Zanini
authors.forename: Pedro
authors.initials: P
authors.lastname: Cabrales
authors.forename: Wisam
authors.initials: W
authors.lastname: Barkho
authors.forename: John A
authors.initials: JA
authors.lastname: Frangos
authors.forename: Leonardo J M
authors.initials: LJ
authors.lastname: Carvalho
mesh_terms: D000475:Alkenes / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects; D019040:E-Selectin / Q000378:metabolism; D004660:Encephalitis / Q000188:drug therapy* / Q000382:microbiology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007962:Leukocytes / Q000166:cytology / Q000378:metabolism; D016779:Malaria, Cerebral / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000494:pharmacology* / Q000627:therapeutic use*; D019007:P-Selectin / Q000378:metabolism; D010962:Plasmodium berghei / Q000472:pathogenicity*; D010973:Platelet Adhesiveness; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D014655:Vascular Resistance / Q000187:drug effects*; D014699:Venules / Q000378:metabolism*
chemical_list: D000475:Alkenes; D019040:E-Selectin; D019007:P-Selectin; D019010:Vascular Cell Adhesion Molecule-1; C453079:dipropylenetriamine-NONOate; D018799:Intercellular Adhesion Molecule-1; D009569:Nitric Oxide