Inhibition of neutrophil migration by hemopexin leads to increased mortality due to sepsis in mice.
BACKGROUND
The reduction of neutrophil migration to the bacterial focus is associated with poor outcome in sepsis.


OBJECTIVE
The objective of this study was to identify soluble substances in the blood of septic mice that inhibit neutrophil migration.


METHODS
A pool of serum obtained from mice 2 hours after the induction of severe sepsis by cecal ligation and puncture inhibited the neutrophil migration. The proteins with inhibitory activity on neutrophil migration were isolated by Blue-Sepharose chromatography, high-performance liquid chromatography, and electrophoresis, and identified by mass spectrometry.


RESULTS
Hemopexin was identified as the serum component responsible for the inhibition of neutrophil migration. In sepsis, the pretreatment of wild-type mice with hemopexin inhibited neutrophil migration to the focus of infection and decreased the survival rate from 87.5 to 50.0%. Hemopexin-null mice subjected to severe sepsis presented normal neutrophil migration, low bacteremia, and an improvement of 40% in survival rate. Moreover, hemopexin inhibited the neutrophil chemotaxis response evoked by C5a or macrophage inflammatory protein-2 and induced a reduction of CXCR2 and L-selectin as well as the up-regulation of CD11b expression in neutrophil membranes. The inhibitory effect of hemopexin on neutrophil chemotaxis was prevented by serine protease inhibitors or ATP. In addition, serum levels of ATP were decreased 2 hours after severe sepsis.


CONCLUSIONS
These data demonstrate for the first time the inhibitory role of hemopexin in neutrophil migration during sepsis and suggest that the therapeutic inhibition of hemopexin or its protease activity could improve neutrophil migration to the focus of infection and survival in sepsis.
Department of Pharmacology, University of São Paulo, Av. Bandeirantes, Ribeirão Preto, SP, Brazil.
Fernando
F
Spiller
Carlotta
C
Costa
Fabrício O
FO
Souto
Francesca
F
Vinchi
Fabíola L A C
FL
Mestriner
Helen J
HJ
Laure
José C
JC
Alves-Filho
Andressa
A
Freitas
José C
JC
Rosa
Sérgio H
SH
Ferreira
Fiorella
F
Altruda
Emilio
E
Hirsch
Lewis J
LJ
Greene
Emanuela
E
Tolosano
Fernando Q
FQ
Cunha
D000704:Analysis of Variance; D000818:Animals; D039481:CD11b Antigen / Q000276:immunology / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects* / Q000276:immunology; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D004195:Disease Models, Animal; D015536:Down-Regulation; D004926:Escherichia coli; D006466:Hemopexin / Q000276:immunology / Q000378:metabolism*; D019041:L-Selectin / Q000378:metabolism; D013058:Mass Spectrometry; D051379:Mice; D008815:Mice, Inbred Strains; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D011897:Random Allocation; D023063:Receptors, Interleukin-8B / Q000276:immunology / Q000378:metabolism; D018805:Sepsis / Q000276:immunology / Q000378:metabolism* / Q000401:mortality*; D015996:Survival Rate; D013864:Thioglycolates / Q000494:pharmacology; D015854:Up-Regulation
D039481:CD11b Antigen; D023063:Receptors, Interleukin-8B; D013864:Thioglycolates; D019041:L-Selectin; D006466:Hemopexin