Protective effects of lactoferrin in Escherichia coli-induced bacteremia in mice: relationship to reduced serum TNF alpha level and increased turnover of neutrophils.
OBJECTIVE
Previous studies demonstrated that lactoferrin (LF), given intravenously (i.v.), 24 h before lethal Escherichia coli ( E. coli) infection, protects mice against mortality. The aim of this investigation was to determine whether downregulation of serum TNF alpha activity and increase of neutrophil number in the circulation and bone marrow by LF could contribute to the protective action of LF against E. coli-induced sepsis.


METHODS
CBA female mice, 10-12 week old, weight 20-22 g, were used.


METHODS
Mice were given 10 mg LF i.v. either 2 h or 24 h before i.v. administration of lethal dose of E. coli (5 x 10(8)).


METHODS
Serum activities of TNF alpha and IL-1 were determined by bioassays 2 h following E. coli or LF injection. The blood and bone marrow smears were stained with Giemsa and May-Grünwald reagents and reviewed histologically.


RESULTS
LF given 24 h before E. coli caused a 60% reduction of TNF alpha released into circulation. However, pretreatment of mice with LF 2 h before bacterial challenge resulted in strong (15 fold) increase of TNF alpha serum level. Analysis of bone marrow cell composition revealed a significant increase in neutrophil lineage cell content (myelocytes, bands and mature neutrophils) following 24 h pretreatment with LF (51.8% of the total cell count), versus PBS control (32.7%) and 2 h LF pretreatment (35.8%). The percentage of neutrophils (bands and mature forms) in the peripheral blood rose to 47.4% versus 32% and 32%, respectively. Intravenous administration of LF increased also interleukin 1 (IL-1) concentration in the circulation of noninfected mice.


CONCLUSIONS
This investigation has added more information regarding the mechanism of the protective action of LF in E. coli-induced bacteremia by revealing the phenomenon of accelerated neutrophil recruitment and down-regulation of E. coli-induced TNF alpha serum level.
Zimecki
M
M
Department of Experimental Therapy, Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wroclaw, Poland.
Artym
J
J
Chodaczek
G
G
Kocieba
M
M
Kruzel
M L
ML
D000818:Animals; D016470:Bacteremia / Q000188:drug therapy*; D001853:Bone Marrow / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000188:drug therapy* / Q000382:microbiology*; D005260:Female; D007375:Interleukin-1 / Q000378:metabolism; D007781:Lactoferrin / Q000494:pharmacology*; D051379:Mice; D008808:Mice, Inbred CBA; D009504:Neutrophils / Q000378:metabolism*; D018805:Sepsis; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000378:metabolism
D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D007781:Lactoferrin