Perspectives on interactions between lactoferrin and bacteriaThis paper is one of a selection of papers published in this Special Issue, entitled 7th International Conference on Lactoferrin: Structure, Function, and Applications, and has undergone the Journal's usual peer review process

The impact of current investigational drugs for acne on future treatment strategies

INTRODUCTION

Acne vulgaris is one of the most prevalent diseases worldwide with a considerably high cost and a burden on quality of life. There are currently many topical and systemic therapies for acne; however, many are limited by their local adverse event profile. This review provides an update on current, novel Phase I and II trials for acne vulgaris.

AREAS COVERED

This review searched the National Institutes of Health US National Library of Medicine online database of clinical trials (ClinicalTrials.gov) for ongoing Phase I and II trials. Only papers discussing novel therapies were discussed, and combinations of previously FDA-approved drugs were excluded.

EXPERT OPINION

The current investigational approaches to acne treatment reflect an attempt to mitigate the underlying cause of acne pathogenesis. By targeting key mechanisms involved, studies aim to show long-term improvement with less frequent treatment use. This provides potential for more tolerable treatments with better patient adherence, in turn leading to increased efficacy.

Lactoferrin-based food supplements trigger toxin production of enteropathogenic Bacillus cereus

Lactoferrin is an iron-binding glycoprotein exhibiting antibacterial, antiviral, antifungal, antiparasitic, antiinflammatory, antianaemic and anticarcinogenic properties. While its inhibitory effects against bacterial pathogens are well investigated, little is known about its influence on the production and/or mode of action of bacterial toxins. Thus, the present study aimed to determine the impact of food supplements based on bovine lactoferrin on Bacillus cereus enterotoxin production. First, strain-specific growth inhibition of three representative isolates was observed in minimal medium with 1 or 10 mg/mL of a lactoferrin-based food supplement, designated as product no. 1. Growth inhibition did not result from iron deficiency. In contrast to that, all three strains showed increased amounts of enterotoxin component NheB in the supernatant, which corresponded with cytotoxicity. Moreover, lactoferrin product no. 1 enhanced NheB production of further 20 out of 28 B. cereus and Bacillus thuringiensis strains. These findings again suggested a strain-specific response toward lactoferrin. Product-specific differences also became apparent comparing the influence of further six products on highly responsive strain INRA C3. Highest toxin titres were detected after exposure to products no. 7, 1 and 2, containing no ingredients except pure bovine lactoferrin. INRA C3 was also used to determine the transcriptional response toward lactoferrin exposure via RNA sequencing. As control, iron-free medium was also included, which resulted in down-regulation of eight genes, mainly involved in amino acid metabolism, and in up-regulation of 52 genes, mainly involved in iron transport, uptake and utilization. In contrast to that, 153 genes were down-regulated in the presence of lactoferrin, including genes involved in flagellar assembly, motility, chemotaxis and sporulation as well as genes encoding regulatory proteins, transporters, heat and cold shock proteins and virulence factors. Furthermore, 125 genes were up-regulated in the presence of lactoferrin, comprising genes involved in sporulation and germination, nutrient uptake, iron transport and utilization, and resistance. In summary, lactoferrin exposure of B. cereus strain-specifically triggers an extensive transcriptional response that considerably exceeds the response toward iron deficiency and, despite down-regulation of various genes belonging to the PlcR-regulon, ultimately leads to an increased level of secreted enterotoxin by a mechanism, which has yet to be elucidated.

Comparative proteomics analyses of whey proteins from breastmilk collected from two ethnic groups in northeast China

The current study aims to investigate differences in whey protein of breastmilk of volunteered mother collected from two ethnic groups (Korean and Han) in China using data-independent acquisition (DIA) based proteomics technique. The total detected 624 proteins were principally allocated to cellular process of biological process (BP), cell and cell part of cell component (CC) and binding of molecular function (MF) according to Gene Ontology (GO) annotation; and carbohydrate metabolism of Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Among the 54 differently expressed proteins, 8 were related with immunity. Enrichment data showed that intracellular of GO functions and viral myocarditis of KEGG pathways were most significantly enriched (p < 0.05). Protein-protein interaction (PPI) network suggested that 40S ribosomal protein S27a and 60S ribosomal protein L10a which interacted most with other proteins ranked the top two hub proteins by MCC (Maximal Clique Centrality) method. This study may have guiding role for development of infant formula powder for specific infants of Han or Korean groups according to responding breastmilk composition.

Comparison of the Effect of Holder Pasteurization and High-Pressure Processing on Human Milk Bacterial Load and Bioactive Factors Preservation

OBJECTIVES

This project aims at comparing the impact of Holder pasteurization (HoP) and high-pressure processing (HPP) on bacterial load and retention of immunological components in human milk.

METHODS

Human milk samples discarded by the Public Mothers' milk bank (Montreal, Canada) for bacterial purpose were pooled (n = 6) and pasteurized either by heating in a water bath (62.5°C, 30 minutes) or by HPP treatment (425 MPa, four cycles of 6 minutes, initial milk temperature of 4°C or 37°C). Bacterial load, lysozyme activity, and levels of immunoglobulins, lactoferrin, lipase, and 26 cytokines were analyzed. Untreated milk samples from same pools served as control.

RESULTS

HPP treatment of milk allows a similar elimination of bacteria than HoP; bacterial counts were under the detection limit [<3 colony-forming units (CFU)/mL] in 50% of milk pools after HPP treatment, compared to 17% for HoP. With initial heating of samples to 37°C before HPP treatment, inactivation to an extent under the detection limit was reached in 67% of pools. There is no significant difference in IgA, lysozyme, and cytokines concentrations between untreated milk and all treatment methods. While no significant difference was observed in the amount of lipase (P > 0.07) and IgG (P > 0.11) between untreated milk and HPP-treated milk samples, HoP seems to be damaging for these factors (P < 0.04). IgM is well preserved in HPP-4°C samples compared to untreated milk (P = 0.07) whereas a decrease is observed for this immunoglobulin levels in HPP-37°C and HoP samples (P < 0.01). Lactoferrin activity, is well maintained in HPP-37°C milk samples in comparison to untreated milk samples (P = 0.52). A decrease in activity of this molecule is noted for samples treated with HPP at 4°C (P = 0.02) and this decrease is even more pronounced for HoP samples (P = 0.004).

CONCLUSIONS

HPP is a promising alternative to HoP for treatment of human milk intended to preterm babies. Our results demonstrate that HPP treatment of human milk provides safe milk with less detrimental effects on the biochemically and immunologically active milk components than HoP.

Lactoferrin, a unique molecule with diverse therapeutical and nanotechnological applications

Lactoferrin (LF) is a naturally glycoprotein with iron-binding properties and diverse biological applications including; antiviral, anti-inflammatory, antioxidant, anti-cancer and immune stimulating effects. In addition, LF was found to be an ideal nanocarrier for some hydrophobic therapeutics because of its active targeting potential due to overexpression of its receptor on the surface of many cells. Moreover, it was proven to be a good candidate for fabrication of nanocarriers to specifically deliver drugs in case of brain tumors owing to the capability of LF to cross the blood brain barrier (BBB). Consequently, it seems to be a promising molecule with multiple applications in the field of cancer therapy and nanomedicine.

Lactoferrin is a dynamic protein in human melioidosis and is a TLR4-dependent driver of TNF-α release in Burkholderia thailandensis infection in vitro

Melioidosis is an often-severe tropical infection caused by Burkholderia pseudomallei (Bp) with high associated morbidity and mortality. Burkholderia thailandensis (Bt) is a closely related surrogate that does not require BSL-3 conditions for study. Lactoferrin is an iron-binding glycoprotein that can modulate the innate inflammatory response. Here we investigated the impact of lactoferrin on the host immune response in melioidosis. Lactoferrin concentrations were measured in plasma from patients with melioidosis and following ex vivo stimulation of blood from healthy individuals. Bt growth was quantified in liquid media in the presence of purified and recombinant human lactoferrin. Differentiated THP-1 cells and human blood monocytes were infected with Bt in the presence of purified and recombinant human lactoferrin, and bacterial intracellular replication and cytokine responses (tumor necrosis factor-α (TNF-α), interleukin-1β and interferon-γ) were measured. In a cohort of 49 melioidosis patients, non-survivors to 28 days had significantly higher plasma lactoferrin concentrations compared to survivors (median (interquartile range (IQR)): 326 ng/ml (230–748) vs 144 ng/ml (99–277), p<0.001). In blood stimulated with heat-killed Bp, plasma lactoferrin concentration significantly increased compared to unstimulated blood (median (IQR): 424 ng/ml (349–479) vs 130 ng/ml (91–214), respectively; p<0.001). Neither purified nor recombinant human lactoferrin impaired growth of Bt in media. Lactoferrin significantly increased TNF-α production by differentiated THP-1 cells and blood monocytes after Bt infection. This phenotype was largely abrogated when Toll-like receptor 4 (TLR4) was blocked with a monoclonal antibody. In sum, lactoferrin is produced by blood cells after exposure to Bp and lactoferrin concentrations are higher in 28-day survivors in melioidosis. Lactoferrin induces proinflammatory cytokine production after Bt infection that may be TLR4 dependent.

Melioidosis is a severe tropical infection caused by the bacterium Burkholderia pseudomallei. Despite antibiotics, mortality in some regions remains very high, necessitating the need for alternative treatment strategies, including targeting the immune system. Lactoferrin is an iron-binding protein with a variety of different functions. In this study, we wanted to test whether lactoferrin alters how the immune system responds during melioidosis. To achieve this, we first tested the blood of melioidosis patients and found that patients who later died had higher lactoferrin levels compared to those who survived. We also stimulated blood obtained from healthy individuals with B. pseudomallei and found that lactoferrin levels increase. We next analyzed whether lactoferrin impaired how the bacteria grows and found that the growth of Burkholderia thailandensis, a closely related bacterium, was not affected by the addition of lactoferrin to the media. When human immune cells, called monocytes, were infected with B. thailandensis, we found that levels of a specific inflammatory protein, TNF-α, increased after adding lactoferrin and that this effect was related to a specific immune recognition pathway called Toll-like receptor 4. These findings provide new data about the role of lactoferrin in modulating the immune response in melioidosis.

Transition metals at the host-pathogen interface: how Neisseria exploit human metalloproteins for acquiring iron and zinc

Transition metals are essential nutrients for all organisms and important players in the host-microbe interaction. During bacterial infection, a tug-of-war between the host and microbe for nutrient metals occurs: the host innate immune system responds to the pathogen by reducing metal availability and the pathogen tries to outmaneuver this response. The outcome of this competition, which involves metal-sequestering host-defense proteins and microbial metal acquisition machinery, is an important determinant for whether infection occurs. One strategy bacterial pathogens employ to overcome metal restriction involves hijacking abundant host metalloproteins. The obligate human pathogens Neisseria meningitidis and N. gonorrhoeae express TonB-dependent transport systems that capture human metalloproteins, extract the bound metal ions, and deliver these nutrients into the bacterial cell. This review highlights structural and mechanistic investigations that provide insights into how Neisseria acquire iron from the Fe(III)-transport protein transferrin (TF), the Fe(III)-chelating host-defense protein lactoferrin (LF), and the oxygen-transport protein hemoglobin (Hb), and obtain zinc from the metal-sequestering antimicrobial protein calprotectin (CP).

A randomized, double-blind, placebo-controlled trial to determine the efficacy and safety of lactoferrin with vitamin E and zinc as an oral therapy for mild to moderate acne vulgaris

Lactoferrin is an iron-binding milk-derived protein that has shown antibacterial and anti-inflammatory effects in vitro and in vivo. The objective of this study was to determine the efficacy and safety of lactoferrin, combined with vitamin E and zinc, for mild to moderate acne vulgaris. In this randomized, double-blind, placebo-controlled trial, 168 subjects aged 13-40 years old were randomly assigned to take either a capsule formulation containing lactoferrin with vitamin E and zinc or placebo twice a day for 3 months. The primary outcome measure was a reduction in the number of acne lesions compared to placebo. A total of 164 subjects completed the study per protocol. The lactoferrin group (n = 82) showed a significant median percent reduction in total lesions as early as 2 weeks (14.5%, P = 0.0120), with the maximum reduction occurring at week 10 (28.5%, P < 0.0001) compared to placebo group (n = 82). Maximum reduction in comedones (32.5%, P < 0.0001) and inflammatory lesions (44%, P < 0.0001) was also seen at week 10 compared to placebo. Sebum scores were improved by week 12. No adverse events were observed during the trial. A twice daily regimen of lactoferrin with vitamin E and zinc significantly reduced acne lesions in people with mild to moderate acne vulgaris.

Lactoferrin: Balancing Ups and Downs of Inflammation Due to Microbial Infections

Lactoferrin (Lf) is a glycoprotein of the primary innate immune-defense system of mammals present in milk and other mucosal secretions. This protein of the transferrin family has broad antimicrobial properties by depriving pathogens from iron, or disrupting their plasma membranes through its highly cationic charge. Noteworthy, Lf also exhibits immunomodulatory activities performing up- and down-regulation of innate and adaptive immune cells, contributing to the homeostasis in mucosal surfaces exposed to myriad of microbial agents, such as the gastrointestinal and respiratory tracts. Although the inflammatory process is essential for the control of invasive infectious agents, the development of an exacerbated or chronic inflammation results in tissue damage with life-threatening consequences. In this review, we highlight recent findings in in vitro and in vivo models of the gut, lung, oral cavity, mammary gland, and liver infections that provide experimental evidence supporting the therapeutic role of human and bovine Lf in promoting some parameters of inflammation and protecting against the deleterious effects of bacterial, viral, fungal and protozoan-associated inflammation. Thus, this new knowledge of Lf immunomodulation paves the way to more effective design of treatments that include native or synthetic Lf derivatives, which may be useful to reduce immune-mediated tissue damage in infectious diseases.

Lactoferrin-Immobilized Surfaces onto Functionalized PLA Assisted by the Gamma-Rays and Nitrogen Plasma to Create Materials with Multifunctional Properties

Both cold nitrogen radiofrequency plasma and gamma irradiation have been applied to activate and functionalize the polylactic acid (PLA) surface and the subsequent lactoferrin immobilization. Modified films were comparatively characterized with respect to the procedure of activation and also with unmodified sample by water contact angle measurements, mass loss, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), and chemiluminescence measurements. All modified samples exhibit enhanced surface properties mainly those concerning biocompatibility, antimicrobial, and antioxidant properties, and furthermore, they are biodegradable and environmentally friendly. Lactoferrin deposited layer by covalent coupling using carbodiimide chemistry showed a good stability. It was found that the lactoferrin-modified PLA materials present significantly increased oxidative stability. Gamma-irradiated samples and lactoferrin-functionalized samples show higher antioxidant, antimicrobial, and cell proliferation activity than plasma-activated and lactoferrin-functionalized ones. The multifunctional materials thus obtained could find application as biomaterials or as bioactive packaging films.

Two outer membrane proteins are bovine lactoferrin-binding proteins in Mannheimia haemolytica A1

Mannheimia haemolytica is a Gram negative bacterium that is part of the bovine respiratory disease, which causes important economic losses in the livestock industry. In the present work, the interaction between M. haemolytica A1 and bovine lactoferrin (BLf) was studied. This iron-chelating glycoprotein is part of the mammalian innate-immune system and is present in milk and mucosal secretions; Lf is also contained in neutrophils secondary granules, which release this glycoprotein at infection sites. It was evidenced that M. haemolytica was not able to use iron-charged BLf (BholoLf) as a sole iron source; nevertheless, iron-lacked BLf (BapoLf) showed a bactericidal effect against M. haemolytica with MIC of 4.88 ± 1.88 and 7.31 ± 1.62 μM for M. haemolytica strain F (field isolate) and M. haemolytica strain R (reference strain), respectively. Through overlay assays and 2-D electrophoresis, two OMP of 32.9 and 34.2 kDa with estimated IP of 8.18 and 9.35, respectively, were observed to bind both BapoLf and BholoLf; these OMP were identified by Maldi-Tof as OmpA (heat-modifiable OMP) and a membrane protein (porin). These M. haemolytica BLf binding proteins could be interacting in vivo with both forms of BLf depending on the iron state of the bovine.

Lactoferrin affects the adherence and invasion of Streptococcus dysgalactiae ssp. dysgalactiae in mammary epithelial cells

Streptococcus dysgalactiae ssp. dysgalactiae is an important causative agent of bovine mastitis worldwide. Lactoferrin is an innate immune protein that is associated with many functions including immunomodulatory, antiproliferative, and antimicrobial properties. This study aimed to investigate the interactions between lactoferrin and a clinical bovine mastitis isolate, Strep. dysgalactiae ssp. dysgalactiae DPC5345. Initially a deliberate in vivo bovine intramammary challenge was performed with Strep. dysgalactiae DPC5345. Results demonstrated a significant difference in lactoferrin mRNA levels in milk cells between the control and infused quarters 7h postinfusion. Milk lactoferrin levels in the Strep. dysgalactiae DPC5345 infused quarters were significantly increased compared with control quarters at 48h postinfusion. In vitro studies demonstrated that lactoferrin had a bacteriostatic effect on the growth of Strep. dysgalactiae DPC5345 and significantly decreased the ability of the bacteria to internalize into HC-11 mammary epithelial cells. Confocal microscopy images of HC-11 cells exposed to Strep. dysgalactiae and lactoferrin further supported this effect by demonstrating reduced invasion of bacteria to HC-11 cells. The combined data suggest that a bovine immune response to Strep. dysgalactiae infection includes a significant increase in lactoferrin expression in vivo, and based on in vitro data, lactoferrin limits mammary cell invasion of this pathogen by binding to the bacteria and preventing its adherence.

Comparison of lactoferrin activity in fresh and stored human milk

OBJECTIVE

Lactoferrin (Lf), the dominant protein in human milk (HM), has been shown to have anti-inflammatory and anti-microbial activity in the neonatal gut. Previous studies indicate that freezing significantly decreases the concentration of Lf in HM. The objective of our study was to compare the activity of Lf in fresh and frozen HM over time.

STUDY DESIGN

HM samples were examined fresh and after storage at -20 °C for 3 and 6 months. Lf concentration was determined by enzyme-linked immunoassay, and the activity was measured by examination of nitric oxide (NO) production and tumor necrosis factor-α secretion from rat macrophages exposed to HM samples.

RESULT

After 3 and 6 months at -20 °C, the average decrease in Lf concentrations was 55% and 65%, respectively. The bioactivity of Lf also decreased significantly over 6 months.

CONCLUSION

Freezing HM for 3 or more months significantly decreases Lf levels and activity. Periodically providing fresh HM may benefit vulnerable preterm neonates.

Effects of Fermented Dairy Products on Skin: A Systematic Review

OBJECTIVE

Fermented dairy products, such as yogurt, have been proposed as a natural source of probiotics to promote intestinal health. Growing evidence shows that modulation of the gastrointestinal tract microbiota can modulate skin disease as well. This systematic review was conducted to examine the evidence for the use of ingested fermented dairy products to modulate skin health and function. We also sought to review the effects of the topical application of dairy products.

DESIGN

The PubMed and Embase databases were systematically searched for clinical studies involving humans only that examined the relationship between fermented dairy products and skin health.

RESULTS

A total of 312 articles were found and a total of 4 studies met inclusion criteria. Three studies evaluated the effects of ingestion, while one evaluated the effects of topical application. All studies noted improvement with the use of fermented dairy.

CONCLUSIONS

Overall, there is early and limited evidence that fermented dairy products, used both topically and orally, may provide benefits for skin health. However, existing studies are limited and further studies will be important to better assess efficacy and the mechanisms involved.

Mucosal Immune Development in Early Life: Setting the Stage

Our environment poses a constant threat to our health. To survive, all organisms must be able to discriminate between good (food ingredients and microbes that help digest our food) and bad (pathogenic microbes, viruses and toxins). In vertebrates, discrimination between beneficial and harmful antigens mainly occurs at the mucosal surfaces of the respiratory, digestive, urinary and genital tract. Here, an extensive network of cells and organs form the basis of what we have come to know as the mucosal immune system. The mucosal immune system is composed of a single epithelial cell layer protected by a mucus layer. Different immune cells monitor the baso-lateral side of the epithelial cells and dispersed secondary lymphoid organs, such as Peyer’s patches and isolated lymphoid follicles are equipped with immune cells able to mount appropriate and specific responses. This review will focus on the current knowledge on host, dietary and bacterial-derived factors that shape the mucosal immune system before and after birth. We will discuss current knowledge on fetal immunity (both responsiveness and lymphoid organ development) as well as the impact of diet and microbial colonization on neonatal immunity and disease susceptibility. Lastly, inflammatory bowel disease will be discussed as an example of how the composition of the microbiota might predispose to disease later in life. A fundamental understanding of the mechanisms involved in mucosal immune development and tolerance will aid nutritional intervention strategies to improve health in neonatal and adult life.

Dietary bovine lactoferrin alters mucosal and systemic immune cell responses in neonatal piglets

Lactoferrin (LF) is a multifunctional immune protein found at high concentrations in human milk. Herein, the effect of dietary bovine LF (bLF) on mucosal and systemic immune development was investigated. Colostrum-deprived piglets were fed formula containing 130 [control (Ctrl)], 367 (LF1), or 1300 (LF3) mg of bLF/(kg body weight · d). To provide passive immunity, sow serum was provided orally during the first 36 h of life. Blood, spleen, mesenteric lymph node (MLN), and ascending colon (Asc) contents were collected on day 7 (n = 10-14/group) and day 14 (n = 10-12/group). Immune cell populations were quantified by flow cytometry and immunoglobulins (Igs) were measured by ELISA. Additionally, immune cells were isolated from spleen and MLNs (n = 7/group) on day 7 and stimulated ex vivo with phytohemagglutinin or lipopolysaccharide (LPS) ± LF for 72 h. Secreted cytokine concentrations were quantified by multiplex assay. Lymphocyte populations [cluster determinant (CD)4, CD8, and natural killer cells] developed normally and were unaffected by dietary bLF. LF3 piglets tended to have 1.4 to 2 times more serum IgG than Ctrl piglets (P = 0.07) or LF1 piglets (P = 0.03), but IgA in Asc contents was unaffected by bLF. Asc IgA was 4 times higher on day 14 than day 7. Spleen cells from LF3 piglets produced 2 times more interleukin (IL)-10 and tumor necrosis factor (TNF)-α ex vivo than those from Ctrl or LF1 piglets. MLN cells from LF1 and LF3 piglets produced 40% more IL-10 and tended to produce 40% more IL-6 (P = 0.05) than those from Ctrl piglets. However, ex vivo bLF did not affect the cytokine response of spleen or MLN cells to LPS. In summary, dietary bLF alters the capacity of MLN and spleen immune cells to respond to stimulation, supporting a role for LF in the initiation of protective immune responses in these immunologically challenged neonates.

Lactoferrin

Lactoferrin is found in milk - human and animal. It has therapeutic potential as an iron supplement, against infection, inflammation and cancer.

The evidence is so far mainly laboratory and animal data, with a small number of human trials beginning to be published, to this point with mixed results. An example is its use as treatment for Helicobacter pylori infection.

Mini-review: Lactoferrin: a bioinspired, anti-biofilm therapeutic

Medically relevant biofilms have gained a significant level of interest, in part because of the epidemic rise in obesity and an aging population in the developed world. The associated comorbidities of chronic wounds such as pressure ulcers, venous leg ulcers, and diabetic foot wounds remain recalcitrant to the therapies available currently. Development of chronicity in the wound is due primarily to an inability to complete the wound healing process owing to the presence of a bioburden, specifically bacterial biofilms. New therapies are clearly needed which specifically target biofilms. Lactoferrin is a multifaceted molecule of the innate immune system found primarily in milk. While further investigation is warranted to elucidate mechanisms of action, in vitro analyses of lactoferrin and its derivatives have demonstrated that these complex molecules are structurally and functionally well suited to address the heterogeneity of bacterial biofilms. In addition, use of lactoferrin and its derivatives has proven promising in the clinic.

The role of lactoferrin binding protein B in mediating protection against human lactoferricin

Bacteria that inhabit the mucosal surfaces of the respiratory and genitourinary tracts of mammals encounter an iron-deficient environment because of iron sequestration by the host iron-binding proteins transferrin and lactoferrin. Lactoferrin is also present in high concentrations at sites of inflammation where the cationic, antimicrobial peptide lactoferricin is produced by proteolysis of lactoferrin. Several Gram-negative pathogens express a lactoferrin receptor that enables the bacteria to use lactoferrin as an iron source. The receptor is composed of an integral membrane protein, lactoferrin binding protein A (LbpA), and a membrane-bound lipoprotein, lactoferrin binding protein B (LbpB). LbpA is essential for growth with lactoferrin as the sole iron source, whereas the role of LbpB in iron acquisition is not yet known. In this study, we demonstrate that LbpB from 2 different species is capable of providing protection against the killing activity of a human lactoferrin-derived peptide. We investigated the prevalence of lactoferrin receptors in bacteria and examined their sequence diversity. We propose that the protection against the cationic antimicrobial human lactoferrin-derived peptide is associated with clusters of negatively charged amino acids in the C-terminal lobe of LbpB that is a common feature of this protein.

Human lactoferrin increases Helicobacter pylori internalisation into AGS cells

Helicobacter pylori has high global infection rates and can cause other undesirable clinical manifestations such as duodenal ulcer (DU) and gastric cancer (GC). Frequencies of re-infection after therapeutic clearance and rates of DU versus GC vary geographically and differ markedly between developed and developing countries, which suggests additional factors may be involved. The possibility that, in vivo, lactoferrin (Lf) may play a subtle role in modulating micronutrient availability or bacterial internalisation with implications for disease etiology is considered. Lf is an iron binding protein produced in mammals that has antimicrobial and immunomodulatory properties. Some bacteria that regularly colonise mammalian hosts have adapted to living in high Lf environments and we investigated if this included the gastric pathogen H. pylori. We found that H. pylori was able to use iron from fully iron-saturated human Lf (hLf) whereas partially iron-saturated hLf (apo) did not increase H. pylori growth. Instead, apo-hLf increased adherence to and internalisation of bacteria into cultured epithelial cells. By increasing internalisation, we speculate that apo-human lactoferrin may contribute to H. pylori's ability to persistence in the human stomach, an observation that potentially has implications for the risk of H. pylori-associated disease.

Efficacy and tolerability of oral lactoferrin supplementation in mild to moderate acne vulgaris: an exploratory study

OBJECTIVE

Lactoferrin, an innate defense iron-binding protein, possesses antimicrobial and anti-inflammatory activities. Beneficial systemic effects on inflammatory diseases have been proposed. The aim of the present study was to explore the efficacy and tolerability of oral bovine lactoferrin supplementation in subjects with mild to moderate facial acne vulgaris.

METHODS

In this open-label, single-arm study, 43 adolescents and young adults were enrolled to take a chewable tablet formulation of bovine lactoferrin twice daily for 8 weeks. The primary efficacy endpoint was the improvement in acne lesion counts compared with baseline. Tolerability was evaluated on the basis of adverse event frequencies.

RESULTS

Thirty-nine subjects, aged 17.5 ± 3.8 years, completed the study per protocol. At the end of the study (week 8), a mean reduction in inflammatory lesion count of 20.2% (-2.2 ± 7.0, p = 0.054), in non-inflammatory lesion count of 23.5% (-6.2 ± 9.8, p < 0.001), and in total lesion count of 22.5% (-8.4 ± 13.1, p < 0.001) was observed as compared with baseline. At study conclusion, 76.9% (30 of 39) of subjects showed a reduction in total lesion count. The results for inflammatory acne lesions were variable over the study course. None of the subjects experienced a lactoferrin-related adverse event during the trial.

CONCLUSION

Despite the limitations of an uncontrolled, open-label study, the results from this study indicate that lactoferrin in mild to moderate acne vulgaris is well tolerated and may lead to an overall improvement in acne lesion counts in the majority of affected adolescents and young adults when administered as a dietary supplement on a twice daily regimen. Further randomized, placebo-controlled trials of longer duration appear warranted.

Deletion of sua gene reduces the ability of Streptococcus uberis to adhere to and internalize into bovine mammary epithelial cells

To elucidate the role of Streptococcus uberis adhesion molecule (SUAM) in the pathogenesis of S. uberis mastitis, sua deletion in S. uberis UT888 was achieved by homologous recombination using a thermosensitive plasmid. The deletion mutant was analyzed for sua deletion by PCR, southern blot and DNA sequencing, and was designated Δsua S. uberis UT888. As compared to the isogenic parent strain, Δsua S. uberis UT888 did not produce SUAM based on SDS-PAGE gel and western blot. Deletion of sua and lack of expression of SUAM by Δsua S. uberis UT888 markedly reduced the ability of the sua gene deletion mutant of S. uberis to adhere to and internalize into mammary epithelial cells. These results confirm the central role of SUAM in adherence to and internalization of S. uberis into host cells.

NalP-mediated proteolytic release of lactoferrin-binding protein B from the meningococcal cell surface

Bacteria have developed several mechanisms for iron uptake during colonization of mammalian hosts, where the availability of free iron is limiting for growth. Neisseria meningitidis expresses under iron-limiting conditions a receptor complex consisting of the lactoferrin-binding proteins A (LbpA) and LbpB to acquire iron from lactoferrin, which is abundantly present on the mucosal surfaces of the human nasopharynx. LbpA is an integral outer membrane-embedded iron transporter, whereas LbpB is a cell surface-exposed lipoprotein. In this study, we demonstrate that LbpB is also released into the culture medium. We identified NalP, an autotransporter known to be involved in the processing of other autotransporters, as the protease responsible for LbpB release. This release of LbpB reduced the complement-mediated killing of the bacteria when incubated with an LbpB-specific bactericidal antiserum. Since antibodies directed against LbpB are found in convalescent-patient sera, the release of an immunogenic protein as LbpB may represent a novel means for N. meningitidis to escape the human immune response.

Study of the interaction of lactoferricin B with phospholipid monolayers and bilayers

Bovine lactoferricin (LfcinB) is an antimicrobial peptide obtained from the pepsin cleavage of lactoferrin. The activity of LfcinB has been extensively studied on diverse pathogens, but its mechanism of action still has to be elucidated. Because of its nonspecificity, its mode of action is assumed to be related to interactions with membranes. In this study, the interaction of LfcinB with a negatively charged monolayer of dipalmitoylphosphatidylglycerol has been investigated as a function of the surface pressure of the lipid film using in situ Brewster angle and polarization modulation infrared reflection absorption spectroscopy and on transferred monolayers by atomic force microscopy and polarized attenuated total reflection infrared spectroscopy. The data show clearly that LfcinB forms stable films at the air-water interface. They also reveal that the interaction of LfcinB with the lipid monolayer is modulated by the surface pressure. At low surface pressure, LfcinB inserts within the lipid film with its long molecular axis oriented mainly parallel to the acyl chains, while at high surface pressure, LfcinB is adsorbed under the lipid film, the hairpin being preferentially aligned parallel to the plane of the interface. The threshold for which the behavior changes is 20 mN/m. At this critical surface pressure, LfcinB interacts with the monolayer to form discoidal lipid-peptide assemblies. This structure may actually represent the mechanism of action of this peptide. The results obtained on monolayers are correlated by fluorescent probe release measurements of dye-containing vesicles made of lipids in different phases and support the important role of the lipid fluidity and packing on the activity of LfcinB.

The serine protease marapsin is expressed in stratified squamous epithelia and is up-regulated in the hyperproliferative epidermis of psoriasis and regenerating wounds

The trypsin-like serine protease marapsin is a member of the large protease gene cluster at human chromosome 16p13.3, which also contains the structurally related proteases testisin, tryptase epsilon, tryptase gamma, and EOS. To gain insight into the biological functions of marapsin, we undertook a detailed gene expression analysis. It showed that marapsin expression was restricted to tissues containing stratified squamous epithelia and was absent or only weakly expressed in all other tissues, including the pancreas. Marapsin was constitutively expressed in nonkeratinizing stratified squamous epithelia of human esophagus, tonsil, cervix, larynx, and cornea. In the keratinizing stratified squamous epidermis of skin, however, its expression was induced only during epidermal hyperproliferation, such as in psoriasis and in murine wound healing. In fact, marapsin was the second most strongly up-regulated protease in psoriatic lesions, where expression was localized to the upper region of the hyperplastic epidermis. Similarly, in the hyperproliferative epithelium of regenerating murine skin wounds, marapsin localized to the suprabasal layers, where keratinocytes undergo squamous differentiation. The transient up-regulation of marapsin, which closely correlated with re-epithelialization, was virtually absent in a genetic mouse model of delayed wound closure. These results suggested a function during the process of re-epithelialization. Furthermore, in reconstituted human epidermis, a model system of epidermal differentiation, members of the IL-20 subfamily of cytokines, such as IL-22, induced marapsin expression. Consistent with a physiologic role in marapsin regulation, IL-22 was also strongly expressed in re-epithelializing skin wounds. Marapsin's restricted expression, localization, and cytokine-inducible expression suggest a role in the terminal differentiation of keratinocytes in hyperproliferating squamous epithelia.

Selectivity and antimicrobial action of bovine lactoferrin derived peptides against wine lactic acid bacteria

In this study, the antibacterial activities of a bovine Lactoferrin pepsin hydrolysate (LFH) and a synthetic peptide derived from bovine lactoferricin (LfcinB(17-31)) have been evaluated against Oenococcus oeni and three additional lactic acid bacteria (LAB) known to cause spoilage during winemaking processes. Inhibition of bacterial growth was demonstrated in vitro in synthetic broth media (MRS) for both LFH and LfcinB(17-31). The bactericidal activity of the synthetic peptide was also assayed and found to vary depending on the bacterial species and the matrix in which exposure to peptide occurred (either MRS broth or white must). Specificity of LfcinB(17-31) for Lactobacillus brevis, Pediococcus damnosus, and O. oeni was demonstrated in must fermentation experiments in which these three LAB co-existed with the winemaking Saccharomyces cerevisiae T73 in the presence of the peptide. Finally, fermentation experiments also showed that LfcinB(17-31) at inhibitory concentrations did not alter either fermentation kinetics or specific enological parameters.

Cloning and expression of antibacterial goat lactoferricin from Escherichia coli AD494(DE3)pLysS expression system

Goat lactoferricin (GLfcin), an antibacterial peptide, is released from the N terminus of goat lactoferrin by pepsin digestion. Two GLfcin-related cDNAs, GLfcin L and GLfcin S, encoding Ala20-Ser60 and Ser36-Ser60 of goat lactoferrin, respectively, were cloned into the pET-23a(+) expression vector upstream from (His)6-Tag gene and transformed into Escherichia coli AD494(DE3)pLysS expression host. After being induced by isopropyl-beta-D-thiogalactopyranoside (IPTG), two (His)6-Tag fused recombinant lactoferricins, GLfcin L-His*Tag and GLfcin S-His*Tag, were expressed in soluble form within the E. coli cytoplasm. The GLfcin L-His*Tag and GLfcin S-His*Tag were purified using HisTrap affinity chromatography. According to an antibacterial activity assay using the agar diffusion method, GLfcin L-His*Tag had antibacterial activity against E. coli BCRC 11549, Staphylococcus aureus BCRC 25923, and Propionibacterium acnes BCRC 10723, while GLfcin S-His*Tag was able to inhibit the growth of E. coli BCRC 11549 and P. acnes BCRC 10723. These two recombinant lactoferricins behaved as thermostable peptides, which could retain their activity for up to 30 min of exposure at 100 degrees C.

Staphylococcus aureus evasion of innate antimicrobial defense

Bacterial pathogens colonize human body surfaces soon after birth. In order to survive the constant threat of invasion and infection, the human innate immune system has evolved several efficient mechanisms to prevent harmful microorganisms from traversing epithelial barriers. These include cationic antimicrobial peptides (CAMPs) such as defensins and the cathelicidin LL-37, bacteriolytic enzymes such as lysozyme, antimicrobial fatty acids, toxic oxygen- or nitrogen-containing molecules, the bacteriolytic complement components and further mechanisms with indirect impacts on bacterial multiplication. Staphylococcus aureus is an important human commensal and pathogen. In order to successfully establish an infection, S. aureus has evolved several mechanisms to resist the innate immune system. In this review, we focus on the mechanisms employed by S. aureus to achieve protection against antimicrobial host defense molecules with special emphasis on CAMPs. Lessons from recent studies on antimicrobial host defense molecules and cognate bacterial resistance adaptation should help in the development of more sustainable anti-infective compounds.

IsdA protects Staphylococcus aureus against the bactericidal protease activity of apolactoferrin

An important facet of the Staphylococcus aureus host-pathogen interaction is the ability of the invading bacterium to evade host innate defenses, particularly the cocktail of host antimicrobial peptides. In this work, we showed that IsdA, a surface protein of S. aureus which is required for nasal colonization, binds to lactoferrin, the most abundant antistaphylococcal polypeptide in human nasal secretions. The presence of IsdA on the surface of S. aureus confers resistance to killing by lactoferrin. In addition, the bactericidal activity of lactoferrin was inhibited by addition of phenylmethylsulfonyl fluoride, implicating the serine protease activity of lactoferrin in the killing of S. aureus. Recombinant IsdA was a competitive inhibitor of lactoferrin protease activity. Reciprocally, antibody reactive to IsdA enhanced killing of S. aureus. Thus, IsdA can protect S. aureus against lactoferrin and acts as a protease inhibitor.

Structure of a complex of human lactoferrin N-lobe with pneumococcal surface protein a provides insight into microbial defense mechanism

Human lactoferrin, a component of the innate immune system, kills a wide variety of microorganisms including the Gram positive bacteria Streptococcus pneumoniae. Pneumococcal surface protein A (PspA) efficiently inhibits this bactericidal action. The crystal structure of a complex of the lactoferrin-binding domain of PspA with the N-lobe of human lactoferrin reveals direct and specific interactions between the negatively charged surface of PspA helices and the highly cationic lactoferricin moiety of lactoferrin. Binding of PspA blocks surface accessibility of this bactericidal peptide preventing it from penetrating the bacterial membrane. Results of site-directed mutagenesis, in vitro protein binding assays and isothermal titration calorimetry measurements corroborate that the specific electrostatic interactions observed in the crystal structure represent major associations between PspA and lactoferrin. The structure provides a snapshot of the protective mechanism utilized by pathogens against the host's first line of defense. PspA represents a major virulence factor and a promising vaccine candidate. Insights from the structure of the complex have implications for designing therapeutic strategies for treatment and prevention of pneumococcal diseases that remain a major public health problem worldwide.