Peroxynitrite mediates the failure of neutrophil migration in severe polymicrobial sepsis in mice.
OBJECTIVE
Sepsis is a systemic inflammatory response resulting from the inability of the host to restrict local infection. The failure of neutrophil migration to the infection site is one of the mechanisms involved in this process. Recently, it was demonstrated that this event is mediated by nitric oxide (NO). The present study addresses the possibility that peroxynitrite (ONOO(-)), a NO-derived powerful oxidizing and nitrating compound, could also be involved in neutrophil migration failure.


METHODS
Male C57Bl/6 mice were subjected to moderate (MSI) or severe (SSI) septic injury, both induced by cecal ligation and puncture (CLP). The leukocyte rolling and adhesion in the mesentery was evaluated by intravital microscopy. Cytokines (TNF-alpha and MIP-1alpha) were measured by ELISA and 3-nitrotyrosine (3-NT) by immunofluorescence.


RESULTS
Compared with saline pretreatment of SSI mice, pre-treatment with uric acid, a ONOO(-) scavenger, partially restored the failure of neutrophil rolling, adhesion and migration to the site of infection. These mice also presented low circulating bacterial counts and diminished systemic inflammatory response. Pretreatment with uric acid reduced 3-NT labelling in leukocytes in mesenteric tissues and in neutrophils obtained from peritoneal exudates. Finally, uric acid pretreatment enhanced significantly the survival rate in the SSI mice. Similarly, treatment with FeTPPs, a more specific ONOO(-) scavenger, re-established neutrophil migration and increased mice survival rate.


CONCLUSIONS
These results indicate that ONOO(-) contributed to the reduction of neutrophil/endothelium interaction and the consequent failure of neutrophil migration into infection foci and hence susceptibility to severe sepsis.
Torres-Dueñas
D
D
Department of Pharmacology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Avenida Bandeirantes, 3900, Ribeirão Preto, São Paulo, Brazil.
Celes
M R N
MR
Freitas
A
A
Alves-Filho
J C
JC
Spiller
F
F
Dal-Secco
D
D
Dalto
V F
VF
Rossi
M A
MA
Ferreira
S H
SH
Cunha
F Q
FQ
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002432:Cecum; D002448:Cell Adhesion / Q000276:immunology; D002465:Cell Movement / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D008026:Ligation; D008297:Male; D008643:Mesentery / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D020556:Neutrophil Infiltration / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology* / Q000473:pathology; D030421:Peroxynitrous Acid / Q000378:metabolism*; D011677:Punctures; D018805:Sepsis / Q000503:physiopathology*; D012720:Severity of Illness Index; D015996:Survival Rate; D014527:Uric Acid / Q000494:pharmacology
D000975:Antioxidants; D016207:Cytokines; D030421:Peroxynitrous Acid; D014527:Uric Acid