Bovine Lactoferrin Inhibits the Efficiency of Invasion of Respiratory A549 Cells of Different Iron-Regulated Morphological Forms of Pseudomonas Aeruginosa and Burkholderia Cenocepacia

Abstract

Pseudomonas aeruginosa and Burkholderia cenocepacia are two important opportunistic respiratory pathogens of cystic fibrosis (CF) patients. Infections caused by these microorganisms are particularly difficult to eradicate because they are usually highly resistant to several currently available broad-spectrum antibiotics. Lactoferrin (Lf), a glycoprotein found in physiological fluids of mammals and present at high concentrations in infected and inflamed tissues, plays an important role in the natural defence mechanism against pathogens and in immune regulation. In the present study, we evaluate the ability of bovine lactoferrin (bLf) to influence P. aeruginosa PAO1 and B. cenocepacia PV1 adhesiveness and invasiveness, using the A549 human bronchial cell line. Three different iron-induced morphological forms of bacteria (free-living, aggregates and biofilm) were assayed. The addition of bLf to cells just before infection had little influence on adhesion efficiency for all three of the morphological forms of B. cenocepacia PV1, while a slight increase in adhesion efficiency by P. aeruginosa PAO1 was noticed. Conversely, invasion of all three morphological forms of both P. aeruginosa and B. cenocepacia was strongly inhibited by the presence of bLf, independently of its degree of iron-binding activity. This is the first report demonstrating an anti-invasive property of bLf for strains of P. aeruginosa and B. cenocepacia.

Iron acquisition in the cystic fibrosis lung and potential for novel therapeutic strategies

“…Taken together, these data provide strong evidence for iron chelation to be an effective adjunctive therapy in treating P. aeruginosa lung infections. Treatment with the host iron-binding protein lactoferrin reduces both the epithelial invasion of Burkholderia cenocepacia and the inflammatory response of CF bronchial epithelial cells to Burkholderia cenocepacia biofilm (Berlutti et al, 2008). Whether these effects are the result of iron chelation or an alternative mechanism is unknown.…”

Lactoferrin and Cystic Fibrosis Airway Infection

“…In any case, the intracellular lifestyle ensures the bacteria a protective niche to replicate, persist, and avoid the host defenses. Lf interferes with the bacterial invasion process of host cells, probably through its binding to bacterial and/ or cell surfaces [15,[95][96][97]. This ability is not related to the Lf iron-chelating function because apo-saturated, iron unsaturated, and iron-saturated Lf exerts an inhibiting activity against the microbial internalization.…”

Bovine lactoferrin interacts with cable pili of Burkholderia cenocepacia

“…Apo-bLf was prepared by the depletion of iron in 0.1 M citric acid, pH 2.3, containing 500 mg/l disodium EDTA, followed by exhaustive dialysis against deionized water. Iron saturated-bLF was obtained by adding adequate molar ratio of ferric ions according procedure described by Berlutti et al (2008). The iron saturation rates were approximately 4.5% for apo-bLf, 19.4% for native bLf, and 95.6% for iron saturated-bLf.…”

“…Previously, we demonstrated that bovine lactoferrin (bLf) was able to influence the efficiency of invasion of different iron-regulated morphological forms of B. cenocepacia; bLf showed to efficiently inhibit invasion of alveolar epithelial cells by freeliving, aggregates or biofilm bacterial forms ironinduced (Berlutti et al 2008). To further investigate the inhibitory action of bLf against B. cenocepacia, we focused this study on the examination of the interaction between bLf and B. cenocepacia, by testing the ability of bLf to bind to bacterial surface.…”