Antimicrobial activity of recombinant human lactoferrin from Aspergillus awamori, human milk lactoferrin and their hydrolysates

Antimicrobial Properties of Colostrum and Milk

The growing number of antibiotic resistance genes is putting a strain on the ecosystem and harming human health. In addition, consumers have developed a cautious attitude towards chemical preservatives. Colostrum and milk are excellent sources of antibacterial components that help to strengthen the immunity of the offspring and accelerate the maturation of the immune system. It is possible to study these important defenses of milk and colostrum, such as lactoferrin, lysozyme, immunoglobulins, oligosaccharides, etc., as biotherapeutic agents for the prevention and treatment of numerous infections caused by microbes. Each of these components has different mechanisms and interactions in various places. The compound's mechanisms of action determine where the antibacterial activity appears. The activation of the antibacterial activity of milk and colostrum compounds can start in the infant's mouth during lactation and continue in the gastrointestinal regions. These antibacterial properties possess potential for therapeutic uses. In order to discover new perspectives and methods for the treatment of bacterial infections, additional investigations of the mechanisms of action and potential complexes are required.

Encapsulation and stabilization of lactoferrin in polyelectrolyte ternary complexes

Effective delivery of the bioactive protein, lactoferrin (LF), remains a challenge as it is sensitive to environmental changes and easily denatured during heating, restricting its application in functional food products. To overcome these challenges, we formulated novel polyelectrolyte ternary complexes of LF with gelatin (G) and negatively charged polysaccharides, to improve the thermal stability of LF with retained antibacterial activity. Linear, highly charged polysaccharides were able to form interpolymeric complexes with LF and G, while coacervates were formed with branched polysaccharides. A unique multiphase coacervate was observed in the gum Arabic GA-LF-G complex, where a special coacervate-in-coacervate structure was found. The ternary complexes made with GA, soy soluble polysaccharide (SSP), or high methoxyl pectin (HMP) preserved the protein structures and demonstrated enhanced thermal stability of LF. The GA-LF-G complex was especially stable with >90% retention of the native LF after treatment at 90 °C for 2 min in a water bath or at 145 °C for 30 s, while the LF control had only ~ 7% undenatured LF under both conditions. In comparison to untreated LF, LF in ternary complex retained significant antibacterial activity on both Gram-positive and Gram-negative bacteria, even after heat treatment. These ternary complexes of LF maintain the desired functionality of LF, thermal stability and antibacterial activity, in the final products. The ternary complex structure, particularly the multiphase coacervate, may serve as a template for the encapsulation and stabilization of other bioactives and peptides.

Augmentation of Urinary Lactoferrin Enhances Host Innate Immune Clearance of Uropathogenic Escherichia coli

Urinary tract infection (UTI) is a prominent global health care burden. Although UTI is readily treated with antibiotics in healthy adults, complicated cases in immune-compromised individuals and the emerging antibiotic resistance of several uropathogens have accelerated the need for new treatment strategies. Here, we surveyed the composition of urinary exosomes in a mouse model of uropathgenic Escherichia coli (UPEC) UTI to identify specific urinary tract defense constituents for therapeutic development. We found an enrichment of the iron-binding glycoprotein lactoferrin in the urinary exosomes of infected mice. In subsequent in vitro studies, we identified human bladder epithelial cells as a source of lactoferrin during UPEC infection. We further established that exogenous treatment with human lactoferrin (hLf) reduces UPEC epithelial adherence and enhances neutrophil antimicrobial functions including bacterial killing and extracellular trap production. Notably, a single intravesicular dose of hLf drastically reduced bladder bacterial burden and neutrophil infiltration in our murine UTI model. We propose that lactoferrin is an important modulator of innate immune responses in the urinary tract and has potential application in novel therapeutic design for UTI.

Antirotaviral potential of lactoferrin from different origin: effect of thermal and high pressure treatments

Rotaviral gastroenteritis causes a high rate of infant mortality and severe healthcare implications worldwide. Several studies have pointed out that human milk and dairy fractions, such as whey and buttermilk, possess antirotaviral activity. This activity has been mainly associated with glycoproteins, among them lactoferrin (LF). Thermal treatments are necessary to provide microbiological safety and extend the shelf life of milk products, though they may diminish their biological value. High hydrostatic pressure (HHP) treatment is a non-thermal method that causes lower degradation of food components than other treatments. Thus, the main objective of this study was to prove the antirotaviral activity of LFs from different origin and to evaluate the effect of several thermal and HHP treatments on that activity. LF exerted a high antirotaviral activity, regardless of its origin. Native LFs from bovine, ovine, swine and camel milk, and the human recombinant forms, at 1 mg/mL, showed neutralizing values in the range 87.5-98.6%, while human LF neutralized 58.2%. Iron saturation of bovine LF did not modify its antirotaviral activity. Results revealed interspecies differences in LFs heat susceptibility. Thus, pasteurization at 63 °C for 30 min led to a decrease of 60.1, 44.5, 87.1, 3.8 and 8% of neutralizing activity for human, bovine, swine, ovine and camel LFs, respectively. Pasteurization at 75 °C for 20 s was less harmful to the activity of LFs, with losses ranging from 0 to 13.8%. HHP treatment at 600 MPa for 15 min did not cause any significant decrease in the neutralizing activity of LFs.

Effect of high pressure on the structure and antibacterial activity of bovine lactoferrin treated in different media

The effect of high-pressure treatment (400, 500 and 650 MPa) on the structure and activity of bovine lactoferrin in different iron-saturation forms has been studied by several techniques. The structural changes produced in lactoferrin by high-pressure were analysed by differential scanning calorimetry and fluorescence spectroscopy, and the immunoreactivity by ELISA. The effect of high-pressure was also studied on some biological properties of lactoferrin, such as iron binding capacity, retention of the bound iron, and antibacterial activity against Escherichia coli O157:H7. Results obtained indicate that treatment at 400 MPa does not substantially modify the conformation of lactoferrin, meanwhile treatments at 500 and 650 MPa greatly affect some of its properties. With respect to the antibacterial activity, the apo and native forms of lactoferrin maintain that activity against Esch. coli only after 400 MPa treatment.