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.
Spiller
Fernando
F
Department of Pharmacology, University of São Paulo, Av. Bandeirantes, Ribeirão Preto, SP, Brazil.
Costa
Carlotta
C
Souto
Fabrício O
FO
Vinchi
Francesca
F
Mestriner
Fabíola L A C
FL
Laure
Helen J
HJ
Alves-Filho
José C
JC
Freitas
Andressa
A
Rosa
José C
JC
Ferreira
Sérgio H
SH
Altruda
Fiorella
F
Hirsch
Emilio
E
Greene
Lewis J
LJ
Tolosano
Emanuela
E
Cunha
Fernando Q
FQ
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