Lactoferrin inhibits the lipopolysaccharide-induced expression and proteoglycan-binding ability of interleukin-8 in human endothelial cells

Temporal patterns of gene expression in response to inoculation with a virulent Anaplasma phagocytophilum strain in sheep

The aim of this study was to characterize the gene expression of host immune- and cellular responses to a Norwegian virulent strain of Anaplasma phagocytophilum, the cause of tick-borne fever in sheep. Ten sheep were intravenously inoculated with a live virulent strain of A. phagocytophilum. Clinical-, observational-, hematological data as well as bacterial load, flow cytometric cell count data from peripheral blood mononuclear cells and host's gene expression post infection was analysed. The transcriptomic data were assessed for pre-set time points over the course of 22 days following the inoculation. Briefly, all inoculated sheep responded with clinical signs of infection 3 days post inoculation and onwards with maximum bacterial load observed on day 6, consistent with tick-borne fever. On days, 3-8, the innate immune responses and effector processes such as IFN1 signaling pathways and cytokine mediated signaling pathways were observed. Several pathways associated with the adaptive immune responses, namely T-cell activation, humoral immune responses, B-cell activation, and T- and B-cell differentiation dominated on the days of 8, 10 and 14. Flow-cytometric analysis of the PBMCs showed a reduction in CD4+CD25+ cells on day 10 and 14 post-inoculation and a skewed CD4:CD8 ratio indicating a reduced activation and proliferation of CD4-T-cells. The genes of important co-stimulatory molecules such as CD28 and CD40LG, important in T- and B-cell activation and proliferation, did not significantly change or experienced downregulation throughout the study. The absence of upregulation of several co-stimulatory molecules might be one possible explanation for the low activation and proliferation of CD4-T-cells during A. phagocytophilum infection, indicating a suboptimal CD4-T-cell response. The upregulation of T-BET, EOMES and IFN-γ on days 8-14 post inoculation, indicates a favoured CD4 Th1- and CD8-response. The dynamics and interaction between CD4+CD25+ and co-stimulatory molecules such as CD28, CD80, CD40 and CD40LG during infection with A. phagocytophilum in sheep needs further investigation in the future.

The cellular and immunological dynamics of early and transitional human milk

Human milk is essential for infant nutrition and immunity, providing protection against infections and other immune-mediated diseases during the lactation period and beyond in later childhood. Milk contains a broad range of bioactive factors such as nutrients, hormones, enzymes, immunoglobulins, growth factors, cytokines, and antimicrobial factors, as well as heterogeneous populations of maternal cells. The soluble and cellular components of milk are dynamic over time to meet the needs of the growing infant. In this study, we utilize systems-approaches to define and characterize 62 analytes of the soluble component, including immunoglobulin isotypes, as well as the cellular component of human milk during the first two weeks postpartum from 36 mothers. We identify soluble immune and growth factors that are dynamic over time and could be utilized to classify milk into different phenotypic groups. We identify 24 distinct populations of both epithelial and immune cells by single-cell transcriptome analysis of 128,016 human milk cells. We found that macrophage populations have shifting inflammatory profiles during the first two weeks of lactation. This analysis provides key insights into the soluble and cellular components of human milk and serves as a substantial resource for future studies of human milk.

Preventing Respiratory Viral Diseases with Antimicrobial Peptide Master Regulators in the Lung Airway Habitat

The vast surface area of the respiratory system acts as an initial site of contact for microbes and foreign particles. The whole respiratory epithelium is covered with a thin layer of the airway and alveolar secretions. Respiratory secretions contain host defense peptides (HDPs), such as defensins and cathelicidins, which are the best-studied antimicrobial components expressed in the respiratory tract. HDPs have an important role in the human body's initial line of defense against pathogenic microbes. Epithelial and immunological cells produce HDPs in the surface fluids of the lungs, which act as endogenous antibiotics in the respiratory tract. The production and action of these antimicrobial peptides (AMPs) are critical in the host's defense against respiratory infections. In this study, we have described all the HDPs secreted in the respiratory tract as well as how their expression is regulated during respiratory disorders. We focused on the transcriptional expression and regulation mechanisms of respiratory tract HDPs. Understanding how HDPs are controlled throughout infections might provide an alternative to relying on the host's innate immunity to combat respiratory viral infections.

Immunomodulatory Effect of Human Lactoferrin on Toll-like Receptors 2 Expression as Therapeutic Approach for Keratoconus

Keratoconus (KC) is a corneal disorder whose etiology shares a close relationship with Lactoferrin (LTF) dysregulation and Toll-like Receptors 2 (TLR2) overexpression. This study shows how these two important biomarkers are clinically and molecularly interrelated, increasing knowledge about KC pathophysiology, and opening the door to future therapies. In this prospective clinical study, serum and tear LTF concentrations were quantified in 90 KC patients and 60 controls. A correlation analysis with multiple blood and tear immunoinflammatory mediators, and KC-associated tomographic parameters, was performed. An in vitro study using HEK-BlueTMhTLR2 cell cultures was also conducted to determine the expression and functionality of TLR2 under the influence of LTF treatment. As a result, a LTF decreased was observed in KC patients compared to controls (p < 0.0001), evidencing the strong correlation with TLR2 overexpression at systemic and ocular surface level, with inflammatory mediator upregulation and with KC severity. In stimulated cell cultures, TLR2 expression was decreased using 2 mg/mL of LTF. The levels of secreted embryonic alkaline phosphatase (SEAP) and interleukin-8 (IL-8) were also reduced in supernatants after LTF treatment. As conclusions, the dysregulation of LTF and TLR2 in the ocular surface of KC patients contributes to KC severity by maintaining a detrimental chronic immune−inflammatory state. The immunomodulatory properties of LTF on TLR2 expression suggest its potential as a therapeutic approach for KC.

Lactoferrin Binding to SARS-CoV-2 Spike Glycoprotein Blocks Pseudoviral Entry and Relieves Iron Protein Dysregulation in Several In Vitro Models

SARS-CoV-2 causes COVID-19, a predominantly pulmonary disease characterized by a burst of pro-inflammatory cytokines and an increase in free iron. The viral glycoprotein Spike mediates fusion to the host cell membrane, but its role as a virulence factor is largely unknown. Recently, the antiviral activity of lactoferrin against SARS-CoV-2 was demonstrated in vitro and shown to occur via binding to cell surface receptors, and its putative interaction with Spike was suggested by in silico analyses. We investigated the anti-SARS-CoV-2 activity of bovine and human lactoferrins in epithelial and macrophagic cells using a Spike-decorated pseudovirus. Lactoferrin inhibited pseudoviral fusion and counteracted the deleterious effects of Spike on iron and inflammatory homeostasis by restoring basal levels of iron-handling proteins and of proinflammatory cytokines IL-1β and IL-6. Using pull-down assays, we experimentally proved for the first time that lactoferrin binds to Spike, immediately suggesting a mechanism for the observed effects. The contribution of transferrin receptor 1 to Spike-mediated cell fusion was also experimentally demonstrated. In silico analyses showed that lactoferrin interacts with transferrin receptor 1, suggesting a multifaceted mechanism of action for lactoferrin. Our results give hope for the use of bovine lactoferrin, already available as a nutraceutical, as an adjuvant to standard therapies in COVID-19.

The preparation of lactoferrin/magnesium silicate lithium injectable hydrogel and application in promoting wound healing

The development of novel wound dressings with highly effective antibacterial and accelerating wound healing properties has become the focus of current research. In this study, a novel and injectable lactoferrin (LF)/lithium magnesium silicate hydrogel (LMSH) was first synthesized through a simple electrostatic interaction method. The physical and biological properties are systematically characterized. The results show that the synthesized LF/LMSH has good antibacterial properties and biocompatibility. More importantly, it can effectively promote wound healing in the rat full-thickness skin wound model after 14 days post-operation, and the healing rate can reach 99.1 %, which is much higher than that of other groups. Meanwhile, histochemical and immunofluorescent staining confirm that the prepared injectable LF/LMSH has good pro-collagen deposition, pro-angiogenic and anti-inflammatory properties. The healed wounds present a consistently thickened epidermis with more follicular and glandular structures, indicating the great potential of the prepared material for wound management.

Effect of bovine lactoferrin on recurrent urinary tract infections: in vitro and in vivo evidences

Uropathogenic Escherichia coli (UPEC) strains are the primary cause of urinary tract infections (UTIs). UPEC strains are able to invade, multiply and persisting in host cells. Therefore, UPEC strains are associated to recurrent UTIs requiring long-term antibiotic therapy. However, this therapy is suboptimal due to the increase of multidrug-resistant UPEC. The use of non-antibiotic treatments for managing UTIs is required. Among these, bovine lactoferrin (bLf), a multifunctional cationic glycoprotein, could be a promising tool because inhibits the entry into the host cells of several intracellular bacteria. Here, we demonstrate that 100 μg/ml bLf hinders the invasion of 2.0 ± 0.5 × 10⁴ CFU/ml E. coli CFT073, prototype of UPEC, infecting 2.0 ± 0.5 × 10⁵ cells/ml urinary bladder T24 epithelial cells. The highest protection (100%) is due to the bLf binding with host surface components even if an additional binding to bacterial surface components cannot be excluded. Of note, in the absence of bLf, UPEC survives and multiplies, while bLf significantly decreases bacterial intracellular survival. After these encouraging results, an observational survey on thirty-three patients affected by recurrent cystitis was performed. The treatment consisted in the oral administration of bLf alone or in combination with antibiotics and/or probiotics. After the observation period, a marked reduction of cystitis episodes was observed (p < 0.001) in all patients compared to the episodes occurred during the 6 months preceding the bLf-treatment. Twenty-nine patients did not report cystitis episodes (87.9%) whereas the remaining four (12.1%) experienced only one episode, indicating that bLf could be a worthwhile and safe treatment in counteracting recurrent cystitis.

High antimicrobial activity of lactoferricin-expressing Bacillus subtilis strains

The lactoferricin expressed in Bacillus subtilis is relatively low in yield, making it hard to apply in industrial settings. We constructed a six tandem repeat of lactoferricin cDNA driven by promoter PtrnQ. After transformation, two transformants P245 and P263 possessing a stable inheritance of plasmid and high expression of lactoferricin were selected. The bactericidal activities, 1 μl of aliquot of a total 5.5 ml of solution extracted from 5 ml of cultured P245 and P263, were equivalent to the efficacy of 238.25 and 322.7 ng of Ampicillin against Escherichia coli, respectively, and 366.4 and 452.52 ng of Ampicillin against Staphylococcus epidermidis respectively. These extracts were able to kill an Ampicillin‐resistant E. coli strain. The bactericidal activities of P245 and P263 equivalent to the efficacy of Tetracycline against Vibrio parahaemolyticus and V. alginolyticus were also determined. Moreover, the bactericidal activities of P245 and P263 were 168.04 and 249.94 ng of Ampicillin against Edwardsiella tarda, respectively, and 219.7 and 252.43 ng of Tetracycline against Streptococcus iniae respectively. Interestingly, the survival rate of E. tarda‐infected tilapia fry fed the P263 extract displayed a significantly greater than that of the fry‐fed control strain. Collectively, these B. subtilis transgenic strains are highly promising for use in animal husbandry during a disease outbreak.

A Novel Human Recombinant Lactoferrin Inhibits Lung Adenocarcinoma Cell Growth and Migration with No Cytotoxic Effect on Normal Human Epithelial Cells

Lung cancer remains the leading cause of cancer death worldwide. Despite the recent advances in cancer treatment, only a subset of patients responds to targeted and immune therapies, and many patients developing resistance after an initial response. Lactoferrin (Lf) is a natural glycoprotein with immunomodulatory and anticancer activities. We produced a novel recombinant human Lf (rhLf) that exhibits glycosylation profile compatible with the natural hLf for potential parenteral therapeutic applications. The aim of this study was to evaluate the anticancer effects of this novel rhLf in human lung adenocarcinoma cells and its mechanisms of action. The results showed a concentration-dependent inhibition of A549 cancer cell growth in response to rhLf. Treatment with 1 mg/ml of rhLf for 24 h and 72 h resulted in a significant inhibition of cancer cell growth by 32% and 25%, respectively. Moreover, rhLf increased fourfold the percentage of early and late apoptotic cells compared to the control. This effect was accompanied by increased levels of caspase-3 activity and cell cycle arrest at the S phase in rhLf-treated cancer cells. Furthermore, rhLf significantly attenuated A549 cell migration. Importantly, treatment of normal human bronchial epithelial (NHBE) cells with rhLf showed the cell viability and morphology comparable to the control. In contrast, chemotherapeutic etoposide induced cytotoxicity in NHBE cells and reduced the cell viability by 40%. These results demonstrate the selective anticancer effects of rhLf against lung adenocarcinoma cells without cytotoxicity on normal human cells. This study highlights a potential for clinical utility of this novel rhLf in patients with lung cancer.

Anti-Infective, Anti-Inflammatory, and Immunomodulatory Properties of Breast Milk Factors for the Protection of Infants in the Pandemic From COVID-19

COVID-19 pandemic since the end of 2019 spreads worldwide, counting millions of victims. The viral invasion, systemic inflammation, and consequent organ failure are the gravest features of coronavirus disease 2019 (COVID-19), and they are associated with a high mortality rate. The aim of this study is to evaluate the role of breast milk in the COVID-19 pandemic, analyzing its antiviral, anti-inflammatory, and immunoregulatory effects due to its bioactive components, so numerous and important for the protection of infants. The study tried to demonstrate that all the components of human milk are capable of performing functions on all the pathogenic events recognized and described in COVID-19 disease. Those human milk factors are well-tolerated and practically free of side effects, so breast milk should become a research topic to discover therapies even in this epidemic. In the first part, the mechanisms of protection and defense of the breast milk elements will be delineated; in the second section, it will describe the human milk effects in viral infections and it will be hypothesized how the known mechanisms could act in COVID infection.

The N-glycans of lactoferrin: more than just a sweet decoration

Nearly all extracellular proteins undergo post-translational modification with sugar chains during their transit through the endoplasmic reticulum and the Golgi apparatus. These “sweet” modifications not only influence the activity of its carrier protein, but they themselves often have bioactivity, independent of the carrier function. Lactoferrin belongs to the group of glycoproteins and is modified with several different N-glycans. This minireview summarizes several studies dealing with the diverse glycosylation patterns of lactoferrin from different origins, and the potential impact of these post-translational modifications on the functionality of lactoferrin. A special emphasis is placed on the differences between human and bovine lactoferrin, because the latter form is often selected for the development of novel therapeutic approaches in humans. For this reason, the potential impact of the bovine-specific glycosylation patterns on the observed heterogeneous effects of lactoferrin in humans is discussed within this minireview.

COVID-19 during Pregnancy and Postpartum

As the COVID-19 pandemic intensified the global health crisis, the containment of SARS-CoV-2 infection in pregnancies, and the inherent risk of vertical transmission of virus from mother-to-fetus (or neonate) poses a major concern. Most COVID-19-Pregnancy patients showed mild to moderate COVID-19 pneumonia with no pregnancy loss and no congenital transmission of the virus; however, an increase in hypoxia-induced preterm deliveries was apparent. Also, the breastmilk of several mothers with COVID-19 tested negative for the virus. Taken together, the natural barrier function during pregnancy and postpartum seems to deter the SARS-CoV-2 transmission from mother-to-child. This clinical observation warrants to explore the maternal-fetal interface and identify the innate defense factors for prevention and control of COVID-19-Pregnancy. Lactoferrin (LF) is a potent antiviral iron-binding protein present in the maternal-fetal interface. In concert with immune co-factors, maternal-LF modulates chemokine release and lymphocyte migration and amplify host defense during pregnancy. LF levels during pregnancy may resolve hypertension via down-regulation of ACE2; consequently, may limit the membrane receptor access to SARS-CoV-2 for cellular entry. Furthermore, an LF-derived peptide (LRPVAA) has been shown to block ACE receptor activity in vitro. LF may also reduce viral docking and entry into host cells and limit the early phase of COVID-19 infection. An in-depth understanding of LF and other soluble mammalian milk-derived innate antiviral factors may provide insights to reduce co-morbidities and vertical transmission of SARS-CoV-2 infection and may lead to the development of effective nutraceutical supplements.

Lactoferrin: A Critical Mediator of Both Host Immune Response and Antimicrobial Activity in Response to Streptococcal Infections

Streptococcal species are Gram-positive bacteria responsible for a variety of disease outcomes including pneumonia, meningitis, endocarditis, erysipelas, necrotizing fasciitis, periodontitis, skin and soft tissue infections, chorioamnionitis, premature rupture of membranes, preterm birth, and neonatal sepsis. In response to streptococcal infections, the host innate immune system deploys a repertoire of antimicrobial and immune modulating molecules. One important molecule that is produced in response to streptococcal infections is lactoferrin. Lactoferrin has antimicrobial properties including the ability to bind iron with high affinity and sequester this important nutrient from an invading pathogen. Additionally, lactoferrin has the capacity to alter the host inflammatory response and contribute to disease outcome. This Review presents the most recent published work that studies the interaction between the host innate immune protein lactoferrin and the invading pathogen, Streptococcus.

Lactoferrin, a versatile natural antimicrobial glycoprotein that modulates the host's innate immunity

Lactoferrin is a multifunctional protein found in the secretions of mammals. The antimicrobial activity of lactoferrin was the first to be discovered and was assumed to be solely dependent on its iron-chelating ability. However, lactoferrin has been reported to display proteolytic activity towards bacterial virulence factors and to modulate the host defence by stimulating the immune system and balancing pathogen-induced inflammation. Here, we review the current understandings of the antimicrobial effect, interaction with host cells, and innate immune modulation of lactoferrin, and put forward this moonlighting protein as a possible alternative for antibiotics.

Lactoferrin: A Critical Player in Neonatal Host Defense

Newborn infants are at a high risk for infection due to an under-developed immune system, and human milk has been shown to exhibit substantial anti-infective properties that serve to bolster neonatal defenses against multiple infections. Lactoferrin is the dominant whey protein in human milk and has been demonstrated to perform a wide array of antimicrobial and immunomodulatory functions and play a critical role in protecting the newborn infant from infection. This review summarizes data describing the structure and important functions performed by lactoferrin in protecting the neonate from infection and contributing to the maturation of the newborn innate and adaptive immune systems. We also briefly discuss clinical trials examining the utility of lactoferrin supplementation in the prevention of sepsis and necrotizing enterocolitis in newborn infants. The data reviewed provide rationale for the continuation of studies to examine the effects of lactoferrin administration on the prevention of sepsis in the neonate.

Immunomodulation to Prevent or Treat Neonatal Sepsis: Past, Present, and Future

Despite continued advances in neonatal medicine, sepsis remains a leading cause of death worldwide in neonatal intensive care units. The clinical presentation of sepsis in neonates varies markedly from that in older children and adults, and distinct acute inflammatory responses results in age-specific inflammatory and protective immune response to infection. This review first provides an overview of the neonatal immune system, then covers current mainstream, and experimental preventive and adjuvant therapies in neonatal sepsis. We also discuss how the distinct physiology of the perinatal period shapes early life immune responses and review strategies to reduce neonatal sepsis-related morbidity and mortality. A summary of studies that characterize immune ontogeny and neonatal sepsis is presented, followed by discussion of clinical trials assessing interventions such as breast milk, lactoferrin, probiotics, and pentoxifylline. Finally, we critically appraise future treatment options such as stem cell therapy, other antimicrobial protein and peptides, and targeting of pattern recognition receptors in an effort to prevent and/or treat sepsis in this highly vulnerable neonatal population.

Role of Lactobacilli and Lactoferrin in the Mucosal Cervicovaginal Defense

The innate defense system of the female mucosal genital tract involves a close and complex interaction among the healthy vaginal microbiota, different cells, and various proteins that protect the host from pathogens. Vaginal lactobacilli and lactoferrin represent two essential actors in the vaginal environment. Lactobacilli represent the dominant bacterial species able to prevent facultative and obligate anaerobes outnumber in vaginal microbiota maintaining healthy microbial homeostasis. Several mechanisms underlie the protection exerted by lactobacilli: competition for nutrients and tissue adherence, reduction of the vaginal pH, modulation of immunity, and production of bioactive compounds. Among bioactive factors of cervicovaginal mucosa, lactoferrin, an iron-binding cationic glycoprotein, is a multifunctional glycoprotein with antibacterial, antifungal, antiviral, and antiparasitic activities, recently emerging as an important modulator of inflammation. Lactobacilli and lactoferrin are largely under the influence of female hormones and of paracrine production of various cytokines. Lactoferrin is strongly increased in lower genital tract mucosal fluid of women affected by Neisseria gonorrheae, Chlamydia trachomatis, and Trichomonas vaginalis infections promoting both innate and adaptive immune responses. In vaginal dysbiosis characterized by low amounts of vaginal lactobacilli and increased levels of endogenous anaerobic bacteria, the increase in lactoferrin could act as an immune modulator assuming the role normally played by the healthy microbiota in vaginal mucosa. Then lactoferrin and lactobacilli may be considered as biomarkers of altered microbial homeostasis at vaginal level. Considering the shortage of effective treatments to counteract recurrent and/or antibiotic-resistant bacterial infections, the intravaginal administration of lactobacilli and lactoferrin could be a novel efficient therapeutic strategy and a valuable tool to restore mucosal immune homeostasis.

In vitro effectiveness of recombinant human lactoferrin and its hydrolysate in alleviating LPS-induced inflammatory response

This study aimed to evaluate the potential anti-inflammatory role of the most produced form of lactoferrin expressed in various expression systems (Fe-saturated recombinant human Lf, rhLf) and its hydrolysate in concentrations resembles that found in mature human milk. Co-culture model consisted of CaCo-2 and RAW 246.7 cell lines was used to evaluate the potential anti-inflammatory activity of rhLf and its hydrolysate. During this experiment, CaCo-2 monolayer permeability and integrity was assayed through the measurement of transepithelial electrical resistance (TEER values). Also, the production of reactive oxygen species (ROS), nitric oxide (NO) and different cytokines (IL-8, IL-1β, IL-6, IL-10, IL-12p70, and TNF-α) were measured. The treatment with rhLf and its hydrolysate protected the monolayer integrity against LPS effect and reduced IL-8 and ROS production. This effect was dependent on the dose and 2mgmL^-1 of rhLf hydrolysate was more effective. The addition of rhLf and its hydrolysate to infant formula is a prominent step towards improving both infant formula functionality and newborn health. Thus, these functional ingredients could be incorporated in infant foods. In this context, ongoing researches are conducted to clarify this effect whether by using synthetic peptides or by using LPS-sepsis animal.

Modulation of Interleukin-12 activity in the presence of heparin

Glycosaminoglycans (GAGs), especially heparin and heparan sulfate (HS), modulate the functions of numerous cytokines. The aims of this multidisciplinary research were to characterize heparin binding to interleukin-12 (IL-12) and determine the mechanism(s) by which heparin influences IL-12 bioactivity. Heparin and HS were found to bind human IL-12 (hIL-12) with low micromolar affinity and increase hIL-12 bioactivity by more than 6-fold. Conversely, other GAGs did not demonstrate significant binding, nor did their addition affect hIL-12 bioactivity. Biophysical studies demonstrated that heparin induced only minor conformational changes while size-exclusion chromatography and small angle X-ray scattering studies indicated that heparin induced dimerization of hIL-12. Heparin modestly protected hIL-12 from proteolytic degradation, however, this was not a likely mechanism for increased cytokine activity in vitro. Flow cytometry studies revealed that heparin increased the amount of hIL-12 bound to cell surfaces. Heparin also facilitated hIL-12 binding and signaling in cells in which both hIL-12 receptor subunits were functionally deleted. Results of this study demonstrate a new role for heparin in modulating the biological activity of IL-12.

Chemokines and Their Receptors in Islet Allograft Rejection and as Targets for Tolerance Induction

Graft rejection is a major barrier to successful outcome of transplantation surgery. Islet transplantation introduces insulin secreting tissue into type 1 diabetes mellitus recipients, relieving patients from exogenous insulin injection. However, insulitis of grafted tissue and allograft rejection prevent long-term insulin independence. Leukocyte trafficking is necessary for the launch of successful immune responses to pathogen or allograft. Chemokines, small chemotactic cytokines, direct the migration of leukocytes through their interaction with chemokine receptors found on cell surfaces of immune cells. Unique receptor expression of leukocytes, and the specificity of chemokine secretion during various states of immune response, suggest that the extracellular chemokine milieu specifically homes certain leukocyte subsets. Thus, only those leukocytes required for the current immune task are attracted to the inflammatory site. Chemokine blockade, using antagonists and monoclonal antibodies directed against chemokine receptors, is an emerging and specific immunosuppressive strategy. Importantly, chemokine blockade may potentiate tolerance induction regimens to be used following transplantation surgery, and prevent the need for life-long immunosuppression of islet transplant recipients. Here, the role for chemokine blockade in islet transplant rejection and tolerance is reviewed.

Liver argininosuccinate synthase binds to bacterial lipopolysaccharides and lipid A and inactivates their biological activities

The liver is known to clear and detoxify circulating lipopolysaccharide (LPS). To characterize the molecules involved in this process in the liver, we attempted to purify mouse liver protein(s) that can interact with lipid A, a biologically active portion of LPS. By partially purifying the inactivating activity against a synthetic lipid A analog, we observed the enrichment of a 45-kDa protein in the active fractions. The internal amino acid sequences of the protein were identical with those of argininosuccinate synthase (EC 6.3.4.5). To examine whether argininosuccinate synthase can interact with lipid A, we purified the enzyme from mouse liver and found the co-elevation of the specific enzyme activity and specific lipid A-inactivating activity, indicating that argininosuccinate synthase is the major lipid A-interacting protein in liver. Argininosuccinate synthase also inhibited the biological activities (macrophage activation and Limulus test) of natural lipid A and rough-type LPS but not smooth-type LPS. The enzyme activity was inhibited by lipid A and rough-type LPS and also by smooth-type LPS. Native gel electrophoresis of a mixture of argininosuccinate synthase and LPS and immunoprecipitation of a mixture of argininosuccinate synthase and [3H]-LPS with anti-argininosuccinate synthase antiserum showed that argininosuccinate synthase stably bound lipid A and LPS. These findings, together, indicate that argininosuccinate synthase can effectively bind LPS in the liver.

Immunology of breast milk

Summary In the critical phase of immunological immaturity of the newborn, particularly for the immune system of mucous membranes, infants receive large amounts of bioactive components through colostrum and breast milk. Colostrum is the most potent natural immune booster known to science. Breastfeeding protects infants against infections mainly via secretory IgA (SIgA) antibodies, but also via other various bioactive factors. It is striking that the defense factors of human milk function without causing inflammation; some components are even anti-inflammatory. Protection against infections has been well evidenced during lactation against, e.g., acute and prolonged diarrhea, respiratory tract infections, including otitis media, urinary tract infection, neonatal septicemia, and necrotizing enterocolitis. The milk’s immunity content changes over time. In the early stages of lactation, IgA, anti-inflammatory factors and, more likely, immunologically active cells provide additional support for the immature immune system of the neonate. After this period, breast milk continues to adapt extraordinarily to the infant’s ontogeny and needs regarding immune protection and nutrition. The need to encourage breastfeeding is therefore justifiable, at least during the first 6 months of life, when the infant’s secretory IgA production is insignificant.

Overview of Lactoferrin as a Natural Immune Modulator

Lactoferrin is thought to be the most polyvalent protein present in host defense against tissue injuries and infections in vertebrates. Owing to the propensity of its basic N-terminal domain to interact with various microbial and host targets, lactoferrin not only has antimicrobial properties, but also modulates the innate and adaptive immune responses. Lactoferrin may indeed up- and downregulate immune cell activation, migration, and growth. Whereas the immunomodulatory properties of lactoferrin are evidenced from in vivo studies using either lactoferrin-knockout, lactoferrin-overexpressing transgenic models, and dietary lactoferrin, few mechanisms from in vitro studies have been proposed to explain these properties. The best characterized lactoferrin targets are negatively charged molecules. They encompass pro-inflammatory microbial molecules, such as pathogen-associated molecular patterns (eg, lipopolysaccharide), but also host components such as DNA, the glycosaminoglycan chains of proteoglycans, and surface cell receptors. Signaling through these receptors is thought to be the main lever used by lactoferrin to influence immune cells and cytokine-balance-controlling cell activity. This article aims to review our current understanding, though incomplete, of the many ways lactoferrin influences the complex immune machinery and the known and putative mechanisms that may explain its properties.

Renoprotective Effect of Lactoferrin against Chromium-Induced Acute Kidney Injury in Rats: Involvement of IL-18 and IGF-1 Inhibition

Hexavalent chromium (CrVI) is a heavy metal widely used in more than 50 industries. Nephrotoxicity is a major adverse effect of chromium poisoning. The present study investigated the potential renoprotective effect of lactoferrin (Lf) against potassium dichromate (PDC)-induced acute kidney injury (AKI) in rats. Beside, because previous studies suggest that interlukin-18 (IL-18) and insulin-like growth factor-1 (IGF-1) play important roles in promoting kidney damage, the present work aimed to evaluate the involvement of these two cytokines in PDC model of AKI and in the potential renoprotective effect of lactoferrin. Adult male albino Wistar rats were pretreated with Lf (200mg/kg/day, p.o.) or (300mg/kg/day, p.o.); the doses that are usually used in the experiment studies, for 14 days followed by a single dose of PDC (15mg/kg, s.c.). PDC caused significant increase in serum urea, creatinine, and total protein levels. This was accompanied with decreased renal glutathione content, and increased renal malondialdehyde, IL-18, IL-4, nuclear factor kappa B (NFκB), IGF-1, and the phosphorylated form of forkhead box protein O1 (FoxO1) levels. Moreover, normal expression IFN-γ mRNA and enhanced expression of TNF-α mRNA was demonstrated in renal tissues. Histopathological investigations provoked deleterious changes in the renal tissues. Tubular epithelial hyperplasia and apoptosis were demonstrated immunohistochemically by positive proliferating cell nuclear antigen (PCNA), Bax, and Caspase-3 expression, respectively. Pretreatment of rats with Lf in both doses significantly corrected all previously mentioned PDC-induced changes with no significant difference between both doses. In conclusion, the findings of the present study demonstrated the involvement of oxidative stress, inflammatory reactions, tubular hyperplasia and apoptosis in PDC-induced AKI. It suggested a role of IL-18 through stimulation of IL-4-induced inflammatory pathway, and IGF-1 through triggering FoxO1-induced cell proliferation. Moreover, the study revealed that Lf protected the kidney against Cr-induced AKI in rats and significantly showed antioxidant, anti-inflammatory, and anti-proliferative properties with down-regulation of IL-18 and IGF-1.

Innate Humoral Defense Factors

Although innate immunity came into the research spotlight in the late 1990s when its instructive role in the adaptive immune response was recognized, innate humoral defense factors have a much older history. The exocrine secretions of the body contain a plethora of distinct soluble factors (lysozyme, lactoferrin, peroxidases, proline-rich proteins, histatins, etc.) that protect the body from mucosal microbial pathogens. More recent studies have established that the humoral arm of innate immunity contains a heterogeneous group of pattern-recognition molecules (e.g., pentraxins, collectins, and ficolins), which perform diverse host-defense functions, such as agglutination and neutralization, opsonization, control of inflammation, and complement activation and regulation. These pattern-recognition molecules, which act as functional predecessors of antibodies (“ante-antibodies”), and the classic soluble innate defense factors form an integrated system with complementary specificity, action, and tissue distribution, and they are the subject of this chapter.

Therapeutic interventions in sepsis: current and anticipated pharmacological agents

Sepsis is a clinical syndrome characterized by a multisystem response to a pathogenic assault due to underlying infection that involves a combination of interconnected biochemical, cellular and organ-organ interactive networks. After the withdrawal of recombinant human-activated protein C (rAPC), researchers and physicians have continued to search for new therapeutic approaches and targets against sepsis, effective in both hypo- and hyperinflammatory states. Currently, statins are being evaluated as a viable option in clinical trials. Many agents that have shown favourable results in experimental sepsis are not clinically effective or have not been clinically evaluated. Apart from developing new therapeutic molecules, there is great scope for for developing a variety of drug delivery strategies, such as nanoparticulate carriers and phospholipid-based systems. These nanoparticulate carriers neutralize intracorporeal LPS as well as deliver therapeutic agents to targeted tissues and subcellular locations. Here, we review and critically discuss the present status and new experimental and clinical approaches for therapeutic intervention in sepsis.

The Use of Chitosan–Dextran Gel Shows Anti-Inflammatory, Antibiofilm, and Antiproliferative Properties in Fibroblast Cell Culture

Background

Chitosan-dextran gel has been used as an antihemostatic agent and antiadhesive agent after endoscopic sinus surgery. Because Staphylococcus aureus biofilms have been implicated in recalcitrant chronic rhinosinusitis, this study aimed to further investigate the (i) anti-inflammatory, (ii) bacterial biofilm inhibition, (iii) antiproliferative effects, and (iv) wound-healing properties of chitosan and chitosan-dextran gel.

Methods

Fibroblasts were isolated from human nasal tissue and were used to determine the effects of chitosan and chitosan-dextran gel on (i) cell proliferation, (ii) wound healing, (iii) inflammation in fibroblast cultures challenged with superantigens S. aureus enterotoxin B (SEB) and toxic shock syndrome toxin (TSST), and (iv) on S. aureus biofilms.

Results

Chitosan was highly effective at reducing IL-8 expression after TSST and SEB challenge. Chitosan was also effective at reducing IL-8 expression of nonchallenged fibroblasts showing its anti-inflammatory effects on fibroblasts in a diseased state. Chitosan-dextran gel showed strong antibiofilm properties at 50% (v/v) concentration in vitro. Dextran, on its own, showed antibiofilm properties at 1.25% (w/v) concentration. Chitosan, on its own, reduced proliferation of fibroblasts to 82% of control proliferation and chitosan-dextran gel reduced proliferation of the fibroblasts to 0.04% of control proliferation. Relative to the no treatment controls, chitosan-dextran gel significantly delayed the wound-healing rate over the first 48 hours of the experiment.

Conclusion

Chitosan-dextran gel reduced fibroblast proliferation and wound-healing time, showing a possible mechanism of reducing adhesions in the postsurgical period. Chitosan reduced IL-8 levels, showing its anti-inflammatory properties. Chitosan-dextran gel and dextran treatment showed antibiofilm properties in our model.

SILAC-based proteomic profiling of the human MDA-MB-231 metastatic breast cancer cell line in response to the two antitumoral lactoferrin isoforms: the secreted lactoferrin and the intracellular delta-lactoferrin

Background

Lactoferrins exhibit antitumoral activities either as a secretory lactoferrin or an intracellular delta-lactoferrin isoform. These activities involve processes such as regulation of the cell cycle and apoptosis. While lactoferrin has been shown to exert its function by activating different transduction pathways, delta-lactoferrin has been proven to act as a transcription factor. Like many tumor suppressors, these two proteins are under-expressed in several types of cancer, particularly in breast cancer.

Methodology/Principal Findings

In order to compare the differential effects of the re-introduction of lactoferrin isoforms in breast cancer cells we chose the cancerous mammary gland MDA-MB-231 cell line as a model. We produced a cell line stably expressing delta-lactoferrin. We also treated these cells with fresh purified human breast lactoferrin. We performed two quantitative proteomic studies in parallel using SILAC coupled to mass spectrometry in order to compare the effects of different doses of the two lactoferrin isoforms. The proteome of untreated, delta-lactoferrin expressing and human lactoferrin treated MDA-MB-231 cells were compared. Overall, around 5300 proteins were identified and quantified using the in-house developed MFPaQ software. Among these, expression was increased by 1.5-fold or more for around 300 proteins in delta-lactoferrin expressing cells and 190 proteins in lactoferrin treated cells. At the same time, about 200 and 40 proteins were found to be downregulated (0-0.7-fold) in response to delta-lactoferrin and lactoferrin, respectively.

Conclusions/Significance

Re-introduction of delta-lactoferrin and lactoferrin expression in MDA-MB-231 mainly leads to modifications of protein profiles involved in processes such as proliferation, apoptosis, oxidative stress, the ubiquitin pathway, translation and mRNA quality control. Moreover, this study identified new target genes of delta-lactoferrin transcriptional activity such as SelH, GTF2F2 and UBE2E1.

Increased plasma lactoferrin levels in leucocytapheresis therapy in patients with rheumatoid arthritis

OBJECTIVE

The aim of this study was to clarify the mechanism of leucocytapheresis (LCAP) in patients with RA.

METHODS

Protein profiles of blood samples from two patients with RA obtained via LCAP column inlet and outlet lines were analysed by two-dimensional fluorescence difference gel electrophoresis and mass spectrometry. The lactoferrin (LTF) levels of peripheral and circulating blood samples from seven patients obtained via the LCAP column blood circuit were then determined by ELISA. Peripheral blood samples from 14 patients with RA were exposed to unwoven polyester fibre filters and the LTF level was determined. In addition, morphological changes in neutrophils after exposure to the filter were examined by optical microscopy, electronic microscopy and LTF immunostaining.

RESULTS

LTF levels were increased in both samples from the LCAP column outlet and peripheral blood at the end of LCAP treatment. Furthermore, peripheral blood samples exposed to the filter revealed a decreased number of neutrophils and an increased level of LTF. Morphological analysis of the exposed neutrophils showed vacuolization of the cytoplasm and degranulation of LTF-positive granules. These data suggest that LTF stored in the granules of neutrophils is released from the neutrophils caught in the LCAP column.

CONCLUSION

Because LTF has been reported to have multiple anti-inflammatory properties, increased levels of LTF may contribute to the clinical effect of LCAP in patients with RA.

Lactoferrin and the newborn: current perspectives

Neonatal sepsis and necrotizing enterocolitis (NEC) are associated with significant mortality and morbidity. Inflammation secondary to sepsis and NEC increases morbidity, especially those related to the lung, brain and eye. Therapeutic strategies that target inflammation and decrease the emergence of antibiotic resistance are urgently needed. Lactoferrin (Lf) is a multifunctional protein that modulates inflammation, cell growth and differentiation and has broad antimicrobial activity. Studies evaluating the efficacy and safety of Lf in the prevention of neonatal sepsis and NEC are currently in progress, and one completed study shows significant promise. In this article, the functions of this multifunctional molecule and current clinical evidence for its use in the newborn are reviewed. Lf prophylaxis and therapy may have a significant impact in improving clinical outcomes of vulnerable preterm neonates.

Structural characterization of the interaction of human lactoferrin with calmodulin

Lactoferrin (Lf) is an 80 kDa, iron (Fe³⁺)-binding immunoregulatory glycoprotein secreted into most exocrine fluids, found in high concentrations in colostrum and milk, and released from neutrophil secondary granules at sites of infection and inflammation. In a number of cell types, Lf is internalized through receptor-mediated endocytosis and targeted to the nucleus where it has been demonstrated to act as a transcriptional trans-activator. Here we characterize human Lf’s interaction with calmodulin (CaM), a ubiquitous, 17 kDa regulatory calcium (Ca²⁺)-binding protein localized in the cytoplasm and nucleus of activated cells. Due to the size of this intermolecular complex (∼100 kDa), TROSY-based NMR techniques were employed to structurally characterize Ca²⁺-CaM when bound to intact apo-Lf. Both CaM’s backbone amides and the ε-methyl group of key methionine residues were used as probes in chemical shift perturbation and cross-saturation experiments to define the binding interface of apo-Lf on Ca²⁺-CaM. Unlike the collapsed conformation through which Ca²⁺-CaM binds the CaM-binding domains of its classical targets, Ca²⁺-CaM assumes an extended structure when bound to apo-Lf. Apo-Lf appears to interact predominantly with the C-terminal lobe of Ca²⁺-CaM, enabling the N-terminal lobe to potentially bind another target. Our use of intact apo-Lf has made possible the identification of a secondary interaction interface, removed from CaM’s primary binding domain. Secondary interfaces play a key role in the target’s response to CaM binding, highlighting the importance of studying intact complexes. This solution-based approach can be applied to study other regulatory calcium-binding EF-hand proteins in intact intermolecular complexes.

Trichomoniasis and lactoferrin: future prospects

Trichomonas vaginalis is a parasitic protozoan which infects the urogenital tract and requires iron as an essential nutrient. Iron is known to upregulate various adhesins required for cytoadherance and other factors involved in pathogenesis. At mucosal surfaces, iron is chelated by lactoferrin resulting in low levels of free iron. However, pathogens have evolved mechanisms for an increased uptake of iron. The present review highlights the role of iron in survival of Trichomonas during fluctuating concentrations of iron at mucosal surfaces during the menstrual cycle. Future prospects in terms of new drug and vaccine targets related to iron and its receptors have also been described.

LF immunomodulatory strategies: mastering bacterial endotoxin1This article is part of a Special Issue entitled Lactoferrin and has undergone the Journal's usual peer review process

Lactoferrin (LF), an iron-binding glycoprotein expressed in most biological fluids, represents a major component of mammalian innate immune system. The multiple activities of LF rely not only on its capacity to bind iron but also to interact with molecular and cellular components of both the host and pathogens. LF can bind and sequester lipopolysaccharide thus preventing proinflammatory pathway activation, sepsis, and tissue damage. However, the interplay between LF and lipopolysaccharide is complex and may lead to different outcomes including both the suppression of inflammatory response and immune activation. Understanding the molecular basis and the functional consequences of this complex interaction is critically relevant in the development of LF-based therapeutic interventions in humans.

Iron-saturated lactoferrin and pathogenic protozoa: could this protein be an iron source for their parasitic style of life?

Iron is an essential nutrient for the survival of pathogens inside a host. As a general strategy against microbes, mammals have evolved complex iron-withholding systems for efficiently decreasing the iron accessible to invaders. Pathogens that inhabit the respiratory, intestinal and genitourinary tracts encounter an iron-deficient environment on the mucosal surface, where ferric iron is chelated by lactoferrin, an extracellular glycoprotein of the innate immune system. However, parasitic protozoa have developed several mechanisms to obtain iron from host holo-lactoferrin. Tritrichomonas fetus, Trichomonas vaginalis, Toxoplasma gondii and Entamoeba histolytica express lactoferrin-binding proteins and use holo-lactoferrin as an iron source for growth in vitro; in some species, these binding proteins are immunogenic and, therefore, may serve as potential vaccine targets. Another mechanism to acquire lactoferrin iron has been reported in Leishmania spp. promastigotes, which use a surface reductase to recognize and reduce ferric iron to the accessible ferrous form. Cysteine proteases that cleave lactoferrin have been reported in E. histolytica. This review summarizes the available information on how parasites uptake and use the iron from lactoferrin to survive in hostile host environments.

Analysis of polymorphisms in the lactotransferrin gene promoter and dental caries

Regarding host aspects, there has been strong evidence for a genetic component in the etiology of caries. The salivary protein lactotransferrin (LTF) exhibits antibacterial activity, but there is no study investigating the association of polymorphisms in the promoter region of LTF gene with caries. The objective of this study was firstly to search the promoter region of the human LTF gene for variations and, if existent, to investigate the association of the identified polymorphisms with dental caries in 12-year-old students. From 687 unrelated, 12-year-old, both sex students, 50 individuals were selected and divided into two groups of extreme phenotypes according to caries experience: 25 students without (DMFT = 0) and 25 with caries experience (DMFT ≥ 4). The selection of individuals with extreme phenotypes augments the chances to find gene variations which could be associated with such phenotypes. LTF gene-putative promoter region (+39 to −1143) of the selected 50 individuals was analyzed by high-resolution melting technique. Fifteen students, 8 without (DMFT = 0) and 7 with caries experience (mean DMFT = 6.28), presented deviations of the pattern curve suggestive of gene variations and were sequenced. However, no polymorphisms were identified in the putative promoter region of the LTF gene.

Lactoferrin, a key molecule in immune and inflammatory processes

Lactoferrin (Lf) belongs to the family of antimicrobial molecules that constitute the principal defense line of nonvertebrate organisms. In human immunity, their roles are considerably extended, and actually exceed mere direct antimicrobial properties. As a result, Lf is involved in both innate and adaptive immunities where its modulating effects not only help the host fight against microbes but also protect the host against harmful effects of inflammation. Such beneficial effects have been noticed in studies using dietary Lf, without the experimenters always explaining the exact modes of action of Lf. Effects on mucosal and systemic immunities are indeed often observed, which make the roles of Lf tricky to decipher. It is now known that the immunomodulatory properties of Lf are due to its ability to interact with numerous cellular and molecular targets. At the cellular level, Lf modulates the migration, maturation, and functions of immune cells. At the molecular level, in addition to iron binding, interactions of Lf with a plethora of compounds, either soluble or cell-surface molecules, account for its modulatory properties. This paper reviews our current understanding of the mechanisms that explain the regulatory properties of Lf in immune and inflammatory processes.

Lactoferrin-lipopolysaccharide (LPS) binding as key to antibacterial and antiendotoxic effects

Lactoferrin (Lf), a multifunctional protein of the innate immune response, seems to act as a permeabilizing agent of Gram negative bacteria, apparently due to its interaction with enterobacterial lipopolysaccharide (LPS) on the bacterial surface. In both human and bovine Lf, a six residue sequence lying in an 18-loop region of the lactoferricin domain is key to Lf-LPS binding. There is much evidence that, by its action on LPS, Lf destabilizes the bacterial membrane and therefore increases bacterial permeability. By itself, Lf is not an effective antibacterial agent, but it permits the penetration of the bacterial membrane by some antibacterial substances whose hydrophobicity otherwise limits their efficacy. Additionally, Lf neutralizes free LPS by keeping the latter from forming complexes that activate TLR-4 signaling pathways. Such pathways, when over-activated, lead to the abundant production of pro-inflammatory mediators such as tumor necrosis factor (TNF) with fatal consequences to the host. The effect of Lf in reducing inflammation and destabilizing Gram negative bacteria has clinical implications in the control of sepsis, multiple organ dysfunction and bacterial invasion.

Proteome analysis of proteins related to aggressive periodontitis combined with neutrophil chemotaxis dysfunction

AIM

Some patients suffering from aggressive periodontitis (Ag-P) also display neutrophil chemotaxis dysfunction. In this study, we attempted to identify the proteins involved in Ag-P associated with neutrophil chemotaxis dysfunction using proteome analysis.

MATERIAL AND METHODS

A two-dimensional fluorescence difference gel electrophoresis system was used to detect differences in protein expression between neutrophils from four patients suffering from Ag-P combined with neutrophil chemotaxis dysfunction and those from four controls. Moreover, the mRNA levels of the proteins identified by the above method were examined in neutrophils from four types of subjects using the real-time polymerase chain reaction: twenty patients suffering from Ag-P with or without the dysfunction, 15 patients with chronic periodontitis, and 15 controls.

RESULTS

Four proteins, lactoferrin, caldesmon, heat shock protein 70, and stac, displayed a higher protein expression level in the neutrophils from the patients suffering from Ag-P combined with the neutrophil dysfunction than in those from the control group. The caldesmon mRNA levels in the neutrophils from the patients suffering from Ag-P combined with the neutrophil dysfunction were high compared with those in the neutrophils from the patients suffering from the other two types of periodontitis and those from the control group.

CONCLUSION

Caldesmon may be a marker of Ag-P combined with neutrophil chemotaxis dysfunction.

Immunohistochemical evidence of lactoferrin in human embryo-fetal bone and cartilage tissues

Lf (lactoferrin) is an 80-kDa iron-binding protein, which has been suggested to promote bone growth in murine models. In view of this, we aimed to analyse the immunohistochemical distribution of Lf in human embryonal and fetal bone and cartilaginous tissues at different gestational weeks in order to evaluate whether a role for this protein might be proposed also in human osteogenesis. Bone and cartilaginous specimens were taken at autopsy from 25 fetuses (8-34 weeks of gestation). Ten samples of human adult bone and cartilage were also submitted to the immunohistochemical procedures. Sections, 4-microm thick, were cut from formalin-fixed paraffin-embedded tissue blocks and stained with a monoclonal antibody against human Lf, following antigen retrieval procedures. Lf immunoreactivity was mainly localized in the mesenchymal cells forming the periosteum as well as in chondroblasts at the eighth gestational week; a strong Lf immunoexpression in immature osteocytes and osteoblasts was noted up to the 18th gestation week, with a considerable decrease by the 24th week. No Lf expression was found in any bone area after the 30th and up to the 34th week of gestation. Our data seem to suggest an important role for Lf as a bone growth regulator in the early phases of the human endochondral ossification, with an anabolic action similar to that previously reported in cell culture lines and in animal models.

A preliminary approach to creating an overview of lactoferrin multi-functionality utilizing a text mining method

Lactoferrin is a multi-functional metal-binding glycoprotein that exhibits many biological functions of interest to many researchers from the fields of clinical medicine, dentistry, pharmacology, veterinary medicine, nutrition and milk science. To date, a number of academic reports concerning the biological activities of lactoferrin have been published and are easily accessible through public data repositories. However, as the literature is expanding daily, this presents challenges in understanding the larger picture of lactoferrin function and mechanisms. In order to overcome the "analysis paralysis" associated with lactoferrin information, we attempted to apply a text mining method to the accumulated lactoferrin literature. To this end, we used the information extraction system GENPAC (provided by Nalapro Technologies Inc., Tokyo). This information extraction system uses natural language processing and text mining technology. This system analyzes the sentences and titles from abstracts stored in the PubMed database, and can automatically extract binary relations that consist of interactions between genes/proteins, chemicals and diseases/functions. We expect that such information visualization analysis will be useful in determining novel relationships among a multitude of lactoferrin functions and mechanisms. We have demonstrated the utilization of this method to find pathways of lactoferrin participation in neovascularization, Helicobacter pylori attack on gastric mucosa, atopic dermatitis and lipid metabolism.

Immunoregulatory role of lactoferrin-lipopolysaccharide interactions

Lactoferrin (Lf) is a mammalian exclusive protein widely distributed in milk and exocrine secretions exhibiting multifunctional properties. Many of the proven or proposed functions of Lf, apart from its iron binding activity, depend on its capacity to bind to other macromolecules. Lf can bind and sequester lipopolysaccharide (LPS), thus preventing pro-inflammatory pathway activation, sepsis and tissue damage. However, the interplay between Lf and LPS is complex, and may result in different outcomes, including both suppression of the inflammatory response and immune activation. These findings are critically relevant in the development of Lf-based therapeutic interventions in humans. Understanding the molecular basis and functional consequences of Lf-LPS interaction will provide insights for determining its role in health and disease.

A critical review of the roles of host lactoferrin in immunity

Lactoferrin (Lf) is an essential element of innate immunity, which refers to antigen-nonspecific defense mechanisms that a host uses immediately or within hours after exposure to an antigen. Following infection, Lf is released from neutrophils (PMNs) in blood and inflamed tissues and, such as other soluble pattern-recognition receptors of the innate immunity, Lf recognizes unique microbial molecules called pathogen-associated molecular patterns (PAMPs): LPS from the gram-negative cell wall and bacterial unmethylated CpG DNA. However, unlike classical PAMPs receptors involved in the activation of immune cells, Lf may act either as a competitor for these receptors or as a partner molecule, depending on the physiological status of the organism. These immunomodulatory properties are explained by the ability of Lf to interact with proteoglycans and receptors on the surface of mammalian cells: cells of the innate (NK cells, neutrophils, macrophages, basophils, neutrophils and mast cells) and adaptive [lymphocytes and antigen-presenting cells (APCs)] immune systems, and also epithelial and endothelial cells. Through these interactions, Lf is able to modulate the migration, maturation and functions of immune cells, and thus to influence both adaptive and innate immunities. The understanding of the roles of the host-expressed Lf in immunity comes from in vivo and in vitro studies with exogenous Lf which, although informative, rarely reflect the pathological, or non-pathological, conditions in the organism. In this review, the data from the literature will be critically analyzed in order to present a real picture of the regulatory roles of host Lf in immunity.

Reciprocal interactions between lactoferrin and bacterial endotoxins and their role in the regulation of the immune response

Lactoferrin (Lf), an iron-binding glycoprotein expressed in most biological fluids, represents a major component of the mammalian innate immune system. Lf’s multiple activities rely not only on its capacity to bind iron, but also to interact with molecular and cellular components of both host and pathogens. Lf can bind and sequester lipopolysaccharide (LPS), thus preventing pro-inflammatory pathway activation, sepsis and tissue damage. However, Lf-bound LPS may retain the capacity to induce cell activation via Toll-like receptor 4-dependent and -independent mechanisms. This review discusses the complex interplay between Lf and LPS and its relevance in the regulation of the immune response.

Can lactoferrin prevent neonatal sepsis and necrotizing enterocolitis?

Despite the use of potent antimicrobials, neonatal sepsis and necrotizing enterocolitis are associated with significant mortality and morbidity. The emergence of microbial antibiotic resistance is a grave concern. Inflammation secondary to sepsis and necrotizing enterocolitis increases pulmonary and cerebral morbidity. New strategies that target inflammation and reduce the emergence of antibiotic resistance are urgently needed. Lactoferrin has broad-spectrum antimicrobial and immunomodulatory activities. In animal models of colitis, lactoferrin reduces inflammatory injury. Lactoferrin also induces the receptor-mediated proliferation and differentiation of intestinal cells. A randomized, controlled trial of lactoferrin in premature neonates to prevent late-onset sepsis is currently in progress. Lactoferrin is a promising agent in the prevention of neonatal sepsis and necrotizing enterocolitis but needs further evaluation to confirm its safety, tolerability and efficacy.