Apoptotic human cells inhibit migration of granulocytes via release of lactoferrin
Irini Bournazou, … , Adriano G. Rossi, Christopher D. Gregory
Irini Bournazou, … , Adriano G. Rossi, Christopher D. Gregory
Published December 1, 2008
Citation Information: J Clin Invest. 2009;119(1):20-32. https://doi.org/10.1172/JCI36226.
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Research Article Immunology

Apoptotic human cells inhibit migration of granulocytes via release of lactoferrin

Abstract

Apoptosis is a noninflammatory, programmed form of cell death. One mechanism underlying the non-phlogistic nature of the apoptosis program is the swift phagocytosis of the dying cells. How apoptotic cells attract mononuclear phagocytes and not granulocytes, the professional phagocytes that accumulate at sites of inflammation, has not been determined. Here, we show that apoptotic human cell lines of diverse lineages synthesize and secrete lactoferrin, a pleiotropic glycoprotein with known antiinflammatory properties. We further demonstrated that lactoferrin selectively inhibited migration of granulocytes but not mononuclear phagocytes, both in vitro and in vivo. Finally, we were able to attribute this antiinflammatory function of lactoferrin to its effects on granulocyte signaling pathways that regulate cell adhesion and motility. Together, our results identify lactoferrin as an antiinflammatory component of the apoptosis milieu and define what we believe to be a novel antiinflammatory property of lactoferrin: the ability to function as a negative regulator of granulocyte migration.

Authors

Irini Bournazou, John D. Pound, Rodger Duffin, Stylianos Bournazos, Lynsey A. Melville, Simon B. Brown, Adriano G. Rossi, Christopher D. Gregory

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Figure 4

Neutrophil chemotaxis toward lactoferrin is irrespective of the chemoattractant used and its iron saturation status.

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Neutrophil chemotaxis toward lactoferrin is irrespective of the chemoatt...
(A) Neutrophil chemotaxis toward different chemoattractants. n = 3; *P < 0.05. (B) Neutrophil chemotaxis toward chemoattractants (control) or chemoattractants that were incubated with lactoferrin (10 μg/ml) followed by the addition of isotype or anti-lactoferrin monoclonal antibody (10 μg/ml). Antibodies were removed using magnetic IgG beads. n = 3; *P < 0.05, NS compared with chemoattractant control. (C) Immunoblot analysis of lysates of neutrophils incubated with or without biotinylated lactoferrin (10 μg/ml) at 37°C for 1 hour. (D) Neutrophil chemotaxis toward lactoferrin (10 μg/ml) purified from human neutrophils or human milk. **P < 0.001 vs. fMLP. C5a-induced monocyte (E) or macrophage (F) chemotaxis. (G) Neutrophil migration in the presence of lactoferrin (10 μg/ml) in the top or bottom compartment of the Transwell insert (n = 3; NS vs. corresponding +LTF controls). (H) Chemotaxis assay to determine neutrophil migration toward purified recombinant iron-depleted (Apo-), partially iron-saturated, and fully iron-saturated (Holo-) recombinant lactoferrin (10 μg/ml). Milk-purified lactoferrin and partially iron-saturated transferrin (TF; 10 μg/ml) were added as control. n = 4; †P < 0.001 compared with fMLP control. Error bars indicate SEM.