Effects of recombinant human lactoferrin on calcium signaling and functional responses of human neutrophils

Abstract

Lactoferrin is a non-heme iron-binding glycoprotein with multiple health-beneficial functions including antimicrobial, antioxidant, anticarcinogenic, and immunomodulatory effects. There is emerging evidence that neutrophils may serve as targets of lactoferrin in vivo, and here we show how recombinant human lactoferrin (rhLf) can contribute to this regulation. Indeed, our results demonstrate that rhLf binds efficiently to human neutrophils and induces a variety of early cellular responses such as mobilization of intracellular Ca²⁺, remodeling of actin cytoskeleton, and degranulation (release of lysozyme and myeloperoxidase). In addition, rhLf facilitates lectin-induced H₂O₂ production and stabilization of lectin-induced cellular aggregates. The role of calcium signaling seems to be essential for rhLf-induced activation of neutrophils, as Ca²⁺-chelators inhibit degranulation response while lectin-induced H₂O₂ production correlates significantly with cytoplasmic Ca²⁺ elevation. Taken together, our findings justify that rhLf can activate neutrophil functions in a calcium-dependent manner and hence, can potentiate innate immune responses.

Keywords: Calcium ions; Cell aggregation; Degranulation; Neutrophils; Recombinant human lactoferrin; Respiratory burst.