Lactoferrin content of peripheral blood cells

Potentials of Natural Antioxidants in Reducing Inflammation and Oxidative Stress in Chronic Kidney Disease

Chronic kidney disease (CKD) presents a substantial global public health challenge, with high morbidity and mortality. CKD patients often experience dyslipidaemia and poor glycaemic control, further exacerbating inflammation and oxidative stress in the kidney. If left untreated, these metabolic symptoms can progress to end-stage renal disease, necessitating long-term dialysis or kidney transplantation. Alleviating inflammation responses has become the standard approach in CKD management. Medications such as statins, metformin, and GLP-1 agonists, initially developed for treating metabolic dysregulation, demonstrate promising renal therapeutic benefits. The rising popularity of herbal remedies and supplements, perceived as natural antioxidants, has spurred investigations into their potential efficacy. Notably, lactoferrin, Boerhaavia diffusa, Amauroderma rugosum, and Ganoderma lucidum are known for their anti-inflammatory and antioxidant properties and may support kidney function preservation. However, the mechanisms underlying the effectiveness of Western medications and herbal remedies in alleviating inflammation and oxidative stress occurring in renal dysfunction are not completely known. This review aims to provide a comprehensive overview of CKD treatment strategies and renal function preservation and critically discusses the existing literature's limitations whilst offering insight into the potential antioxidant effects of these interventions. This could provide a useful guide for future clinical trials and facilitate the development of effective treatment strategies for kidney functions.

Lactoferrin: An Effective Weapon in the Battle Against Bacterial Infections

The emergence of multidrug-resistant bacterial strains with respect to commercially available antimicrobial drugs has marked a watershed in treatment therapies to fight pathogens and has stimulated research on alternative remedies. Proteins of the innate immune system of mammals have been highlighted as potentially yielding possible treatment options for infections. Lactoferrin (Lf) is one of these proteins; interestingly, no resistance to it has been found. Lf is a conserved cationic nonheme glycoprotein that is abundant in milk and is also present in low quantities in mucosal secretions. Moreover, Lf is produced and secreted by the secondary granules of neutrophils at infection sites. Lf is a molecule of approximately 80 kDa that displays multiple functions, such as antimicrobial, anti-viral, anti-inflammatory, and anticancer actions. Lf can synergize with antibiotics, increasing its potency against bacteria. Lactoferricins (Lfcins) are peptides resulting from the N-terminal end of Lf by proteolytic cleavage with pepsin. They exhibit several anti-bacterial effects similar to those of the parental glycoprotein. Synthetic analog peptides exhibiting potent antimicrobial properties have been designed. The aim of this review is to update understanding of the structure and effects of Lf and Lfcins as anti-bacterial compounds, focusing on the mechanisms of action in bacteria and the use of Lf in treatment of infections in patients, including those studies where no significant differences were found. Lf could be an excellent option for prevention and treatment of bacterial diseases, mainly in combined therapies with antibiotics or other antimicrobials.

Genetically engineered pH-responsive silk sericin nanospheres with efficient therapeutic effect on ulcerative colitis

Ulcerative colitis (UC) is one type of inflammatory bowel disease (IBD) and lactoferrin (LF) is a promising protein drug to treat UC. However, targeted LF delivery to optimize bioavailability, targeting and effectiveness remains a challenge. Here, we report an effective strategy to fabricate silk sericin nanospheres systems for the delivery of recombinant human lactoferrin (SS-NS-rhLF). The system is based on the use of optimized transgenic silkworms to generate genetically engineered silk fibers (rhLF-silks). The rhLF silks were used for fabricating SS-NS-rhLF by ethanol precipitation. The SS-NS-rhLF were stable with a spherical morphology with an average diameter of 123 nm. The negatively charged sericins in a pH ≥ 5.5 environment achieved specific targeting of the SS-NS-rhLF to positively charged colonic sites. The SS-NS-rhLF achieved efficient uptake by cells in the inflamed colon of mice when compared to free lactoferrin in solution (SOL-rhLF). Furthermore, oral administration of the SS-NS-rhLF with low dose of rhLF significantly relived symptoms of UC in mice and achieved comparable therapeutic effect to the high dose of SOL-rhLF by supporting the reformation of cell structure and length of colon tissue, reducing the release of inflammatory factors, inhibiting the activation of the NF-κB inflammatory pathway, and maintaining a stable intestinal microbial population in mice. These results showed that the SS-NS-rhLF is a promising system for colitis treatment. STATEMENT OF SIGNIFICANCE: Targeting and effective delivery of multiple biological functional protein human lactoferrin (rhLF) is a promising strategy to treat ulcerative colitis in the clinic. Here, rhLF-transgenic silk cocoons were used to fabricate a rhLF-sericin nanosphere delivery system (SS-NS-rhLF). The fabricated SS-NS-rhLF showed identical spherical morphology, stable structure, sustainable rhLF release, efficient cell uptake and negative charge in an environment of pH above 5.5, thus realized the specific targeting to the positively charged colonic sites to treat UC mice through oral administration. The therapeutic effect of SS-NS-rhLF with a low rhLF dose in the UC mice was comparable to the high dose of free rhLF treatment in solution form, suggesting that the SS-NS-rhLF is a promising system for colitis treatment.

Milieu matters: An in vitro wound milieu to recapitulate key features of, and probe new insights into, mixed-species bacterial biofilms

Bacterial biofilms are a major cause of delayed wound healing. Consequently, the study of wound biofilms, particularly in host-relevant conditions, has gained importance. Most in vitro studies employ refined laboratory media to study biofilms, representing conditions that are not relevant to the infection state. To mimic the wound milieu, in vitro biofilm studies often incorporate serum or plasma in growth conditions, or employ clot or matrix-based biofilm models. While incorporating serum or plasma alone is a minimalistic approach, the more complex in vitro wound models are technically demanding, and poorly compatible with standard biofilm assays. Based on previous reports of clinical wound fluid composition, we have developed an in vitro wound milieu (IVWM) that includes, in addition to serum (to recapitulate wound fluid), matrix elements and biochemical factors. With Luria-Bertani broth and Fetal Bovine Serum (FBS) for comparison, the IVWM was used to study planktonic growth, biofilm features, and interspecies interactions, of common wound pathogens, Staphylococcus aureus and Pseudomonas aeruginosa. We demonstrate that the IVWM recapitulates widely reported in vivo biofilm features such as biomass formation, metabolic activity, increased antibiotic tolerance, 3D structure, and interspecies interactions for monospecies and mixed-species biofilms. Further, the IVWM is simple to formulate, uses laboratory-grade components, and is compatible with standard biofilm assays. Given this, it holds potential as a tractable approach to study wound biofilms under host-relevant conditions.

Lactoferrin promotes osteogenesis of MC3T3-E1 cells induced by mechanical strain in an extracellular signal-regulated kinase 1/2-dependent manner

INTRODUCTION

This study aimed to investigate the role of lactoferrin (LF) in the mechanical strain-induced osteogenesis of nontransformed osteoblastic cells (MC3T3-E1 cells) and related mechanism.

METHODS

MC3T3-E1 cells were cultured in vitro and treated with 100 μg/mL LF, followed by a 2000 μ mechanical strain load. U0126 was used to determine the role of extracellular signal-regulated kinase 1/2 (Erk1/2). Alizarin red S staining was performed to observe the cell mineralization potential. The osteogenic results were analyzed by reverse transcription-polymerase chain reaction and western blotting.

RESULTS

The expression of Col1, Alp, Ocn, Bsp, and Opn mRNA and p-Erk1/2 proteins was significantly upregulated under mechanical strain load. In addition, mineralized nodule formation was increased. After adding LF, the expression of the biomarkers and the formation of mineralized nodules were further promoted. On treatment with the Erk1/2 inhibitor U0126, the expression of Col1, Alp, and p-Erk1/2 mRNA and protein was significantly downregulated.

CONCLUSIONS

These findings demonstrate that LF promotes osteogenic activity by activating osteogenesis-related biomarkers, corroborating that the effects of mechanical strain depend on Erk1/2 signaling pathway.

Lactoferrin and Its Derived Peptides: An Alternative for Combating Virulence Mechanisms Developed by Pathogens

Due to the emergence of multidrug-resistant pathogens, it is necessary to develop options to fight infections caused by these agents. Lactoferrin (Lf) is a cationic nonheme multifunctional glycoprotein of the innate immune system of mammals that provides numerous benefits. Lf is bacteriostatic and/or bactericidal, can stimulate cell proliferation and differentiation, facilitate iron absorption, improve neural development and cognition, promote bone growth, prevent cancer and exert anti-inflammatory and immunoregulatory effects. Lactoferrin is present in colostrum and milk and is also produced by the secondary granules of polymorphonuclear leukocytes, which store this glycoprotein and release it at sites of infection. Lf is also present in many fluids and exocrine secretions, on the surfaces of the digestive, respiratory and reproductive systems that are commonly exposed to pathogens. Apo-Lf (an iron-free molecule) can be microbiostatic due to its ability to capture ferric iron, blocking the availability of host iron to pathogens. However, apo-Lf is mostly microbicidal via its interaction with the microbial surface, causing membrane damage and altering its permeability function. Lf can inhibit viral entry by binding to cell receptors or viral particles. Lf is also able to counter different important mechanisms evolved by microbial pathogens to infect and invade the host, such as adherence, colonization, invasion, production of biofilms and production of virulence factors such as proteases and toxins. Lf can also cause mitochondrial and caspase-dependent regulated cell death and apoptosis-like in pathogenic yeasts. All of these mechanisms are important targets for treatment with Lf. Holo-Lf (the iron-saturated molecule) can contain up to two ferric ions and can also be microbicidal against some pathogens. On the other hand, lactoferricins (Lfcins) are peptides derived from the N-terminus of Lf that are produced by proteolysis with pepsin under acidic conditions, and they cause similar effects on pathogens to those caused by the parental Lf. Synthetic analog peptides comprising the N-terminus Lf region similarly exhibit potent antimicrobial properties. Importantly, there are no reported pathogens that are resistant to Lf and Lfcins; in addition, Lf and Lfcins have shown a synergistic effect with antimicrobial and antiviral drugs. Due to the Lf properties being microbiostatic, microbicidal, anti-inflammatory and an immune modulator, it represents an excellent natural alternative either alone or as adjuvant in the combat to antibiotic multidrug-resistant bacteria and other pathogens. This review aimed to evaluate the data that appeared in the literature about the effects of Lf and its derived peptides on pathogenic bacteria, protozoa, fungi and viruses and how Lf and Lfcins inhibit the mechanisms developed by these pathogens to cause disease.

Quantitative proteomic characterization of microvesicles/exosomes from the cerebrospinal fluid of patients with acute bilirubin encephalopathy

Severe hyperbilirubinemia causes neurotoxicity and may lead to acute bilirubin encephalopathy (ABE) during the critical period of central nervous system development. The aim of the present study was to identify differentially expressed proteins (DEPs) in microvesicles/exosomes (MV/E) isolated from the cerebrospinal fluid (CSF) of patients with ABE. Co-precipitation was used to isolate the MV/E from the CSF of patients with ABE and age-matched controls. Isobaric tagging for relative and absolute quantification-based proteomic technology combined with liquid chromatography/tandem mass spectrometry was used to identify DEPs in the MV/E. Bioinformatics analysis was subsequently performed to investigate Gene Ontology functional annotation and Kyoto Encyclopedia of Genes and Genomes enriched signaling pathways of these DEPs. A total of four proteins were selected for further validation via western blotting. A total of 291 dysregulated proteins were identified by comparing the patients with ABE with the controls. Bioinformatics analysis indicated the involvement of immune-inflammation-associated cellular processes and signaling pathways in the pathophysiology of ABE. In conclusion, the present study identified the proteomic profile of MV/E isolated from the CSF of patients with ABE. These results may provide an improved understanding of the pathogenesis of ABE and may help to identify early diagnostic biomarkers and therapeutic targets.

Lactoferrin quantification in cattle faeces by ELISA

Background

Promoting and maintaining health is critical to ruminant welfare and productivity. Within human medicine, faecal lactoferrin is quantified for routine assessment of various gastrointestinal illnesses avoiding the need for blood sampling. This approach might also be adapted and applied for non-invasive health assessments in animals.

Methods

In this proof-of-concept study, a bovine lactoferrin enzyme-linked immunosorbent assays (ELISA), designed for serum and milk, was applied to a faecal supernatant to assess its potential for quantifying lactoferrin in the faeces of cattle. Faecal lactoferrin concentrations were compared to background levels to assess the viability of the technique. A comparison was then made against serum lactoferrin levels to determine if they were or were not reflective of one another.

Results

The optical densities of faecal samples were significantly greater than background readings, supporting the hypothesis that the assay was effective in quantifying faecal lactoferrin (T_{13, 115} = 11.99, p < 0.0005). The mean faecal lactoferrin concentration was 0.269 µg mL⁻¹ (S.E. 0.031) and the mean serum concentration 0.074 µg mL⁻¹ (S.E. 0.005). Lactoferrin concentrations of faecal and serum samples, taken from the same animals on the same day, were significantly different (T₂₁ = 2.20, p = 0.039) and did not correlate (r = 0.2699, p = 0.238).

Conclusion

Results support the hypothesis that lactoferrin can be quantified in cattle faeces by ELISA. Whilst further research is required to determine the physiological source of the lactoferrin, this highlights the potential of the method for non-invasive assessment of cattle immunology and pathology.

Dietary lactoferrin supplementation to gilts during gestation and lactation improves pig production and immunity

Lactoferrin (LF), a sialylated iron-binding glycoprotein, performs multiple beneficial functions including modulating immunity and improves neurodevelopment, health and growth performance. Maternal LF intervention for gilts (first parity sows) on the performance of gilts and their offspring remains unknown. In the current study gilts were fed with a commercial pig feed supplemented with 1g LF /day (treatment group) or 1g milk casein/day (control group) from day 1 post mating throughout pregnancy and lactation for about 135 days. The milk production and body weight gain was monitored. The immunoglobulin concentrations in the serum of gilts and piglets were measured using ELISA. Our study showed that maternal LF supplementation to the gilt (1) significantly increased milk production at different time points (day 1, 3, 7 and 19) of lactation compared to the control (p<0.001); (2) significantly increased body weight gain of their piglets during the first 19 days of life compared to the control group (p<0.05); (3) tended to increase pregnancy rate, litter size and birth weight, number of piglets born alive, and decrease the number of dead and intrauterine growth restriction (IUGR) piglets; (4) significantly increased the concentration of serum IgA in gilt and serum sIgA in piglet (p<0.05). In summary, maternal Lf intervention in gilts can improve milk production, pig production and serum IgA and sIgA levels, and therefore plays a key role in shaping the performance of their progeny.

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 from Milk: Nutraceutical and Pharmacological Properties

Lactoferrin is an iron-binding protein present in large quantities in colostrum and in breast milk, in external secretions and in polymorphonuclear leukocytes. Lactoferrin's main function is non-immune protection. Among several protective activities shown by lactoferrin, those displayed by orally administered lactoferrin are: (i) antimicrobial activity, which has been presumed due to iron deprivation, but more recently attributed also to a specific interaction with the bacterial cell wall and extended to viruses and parasites; (ii) immunomodulatory activity, with a direct effect on the development of the immune system in the newborn, together with a specific antinflammatory effects; (iii) a more recently discovered anticancer activity. It is worth noting that most of the protective activities of lactoferrin have been found, sometimes to a greater extent, also in peptides derived from limited proteolysis of lactoferrin that could be generated after lactoferrin ingestion. Lactoferrin could therefore be considered an ideal nutraceutic product because of its relatively cheap production from bovine milk and of its widely recognized tolerance after ingestion, along with its well demonstrated protective activities. The most important protective activities shown by orally administered bovine lactoferrin are reviewed in this article.

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.

Lactoferrin from bovine colostrum regulates prolyl hydroxylase 2 activity and prevents prion protein-mediated neuronal cell damage via cellular prion protein

Prion disorders are associated with the conversion of normal cellular prion protein (PrPc) to the abnormal scrapie isoform of prion protein (PrPsc). Recent studies have shown that expression of normal PrPc is regulated by hypoxia-inducible factor-1 alpha (HIF-1α), and that lactoferrin increases full-length PrPc on the cell surface. Lactoferrin is an 80-kDa iron-binding glycoprotein with various biological activities, including iron-chelating ability. HIF-1α and the associated ubiquitin-proteasome pathway are regulated by HIF prolyl-hydroxylases 2 (PHD2). We hypothesized that lactoferrin regulates PHD2 expression and enzymatic activity, and the PHD2 regulation promotes HIF-1α stability and prevention of neuronal cell death mediated by prion protein (PrP) residues (106-126). Lactoferrin prevented PrP (106-126)-induced neurotoxicity by the induction of PrPc expression via promoting HIF-1α stability in neuronal cells. Our results demonstrated that lactoferrin prevented PrP (106-126)-induced neurotoxicity via the up-regulation of HIF-1α stability determined by PHD2 expression and enzymatic activity. These findings suggest that possible therapies such as PHD2 inhibition, or promotion of lactoferrin secretion, may have clinical benefits in neurodegenerative diseases, including prion disease.

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.

Lactoferrin directly scavenges hydroxyl radicals and undergoes oxidative self-degradation: a possible role in protection against oxidative DNA damage

In this study, we examined the protective effect of lactoferrin against DNA damage induced by various hydroxyl radical generation systems. Lactoferrin (LF) was examined with regard to its potential role as a scavenger against radical oxygen species using bovine milk LF. Native LF, iron-saturated LF (holo-LF), and apolactoferrin (apo-LF) effectively suppressed strand breaks in plasmid DNA due to hydroxyl radicals produced by the Fenton reaction. In addition, both native LF and holo-LF clearly protected calf thymus DNA from fragmentation due to ultraviolet irradiation in the presence of H2O2. We also demonstrated a protective effect of all three LF molecules against 8-hydroxydeoxyguanosine (8-OHdG) formation in calf thymus DNA following ultraviolet (UV) irradiation with H2O2. Our results clearly indicate that native LF has reactive oxygen species-scavenging ability, independent of its nature as a masking component for transient metals. We also demonstrated that the protective effect of LF against oxidative DNA damage is due to degradation of LF itself, which is more susceptible to degradation than other bovine milk proteins.

Lack of effect of bovine lactoferrin in respiratory syncytial virus replication and clinical disease severity in the mouse model

BACKGROUND

Lactoferrin (LF) is a glycoprotein present in human milk with known antimicrobial effects. In vitro, LF has demonstrated antiviral activity against respiratory syncytial virus (RSV). We sought to assess the effect of bovine (b)LF in RSV replication, lung inflammation and function, cytokine profiles and clinical disease in an in vivo murine model.

METHODS

Female BALB/c mice were inoculated with 10(7)PFU RSV A2 or 10% EMEM. bLF or placebo (DPBS) were administered once or twice daily by oral gavage or intraperitoneal (IP) injection at doses ranging from 2 to 10mg/animal/day, from 48h before until 96h post-RSV inoculation. Bronchoalveolar lavage (BAL), whole lung and serum samples were harvested on day 5 post-inoculation to asses RSV loads, lung inflammation and cytokine concentrations. Weight loss, airway obstruction and disease severity were assessed daily in all groups.

RESULTS

On day 5 post-inoculation BAL RSV loads, lung inflammation and serum innate, Th1, Th2 and Th17 cytokine concentrations showed no differences between RSV infected mice treated with bLF and RSV infected but untreated mice independent of bLF dosing and administration route (p>0.05). In addition, all bLF groups showed similar weight loss, degree of airway obstruction, and disease severity scores on days 1-5 post-inoculation which was comparable to infected untreated mice (p>0.05) but higher than uninfected controls.

CONCLUSIONS

Administration of oral or IP bLF at different doses did not demonstrate antiviral activity or significant effects on disease severity in the RSV mouse model. Whether these observations could be extrapolated to infants at risk for RSV infection needs to be further explored.

Iron-containing proteins lactoferrin and ferritin in biological media of patients with pulmonary tuberculosis

Salivary and serum levels of lactoferrin and ferritin were measured in patients with pulmonary tuberculosis and patients with other nonspecific respiratory diseases. Measurements of lactoferrin in biological media and particularly in the serum of patients with pulmonary tuberculosis proved to be a highly informative test for monitoring the disease course, i.e. for evaluation of inflammatory process activity. Ferritin level can serve as an indicator of tissue destruction during inflammation and of the course of rehabilitation processes.

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.

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.

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 targets T cells in the small intestine

BACKGROUND

Lactoferrin (Lf) belongs to the transferrin family of non-heme iron-binding proteins and is found in milk and mucosal secretions. Consequently, it is now considered a multifunctional protein mainly involved in both the innate and adaptive immune defenses of the organism against various pathogens, and Lf receptors have been identified at the surfaces of a number of different cells. In the small intestine Lf binds to the luminal surface, but its further interaction with the epithelial cells is controversial.

METHODS

In the present work, we studied the uptake of Lf in cultured mucosal explants of pig small intestine by immunofluorescence and immunogold microscopy.

RESULTS

Lf rapidly bound to the brush border and subsequently appeared in punctae in the apical cytoplasm, indicating internalization into an endosomal compartment. Essentially, no labeling was detected elsewhere in the enterocytes by 2 h incubation. However, in addition to enterocytes, a distinct subpopulation of cells in the lamina propria also took up Lf, most likely from the serosal side of the explants. None of these cells were apoptotic, nor did they belong to the predominant group of immunoglobulin-synthesizing plasma cells in the lamina propria. However, they were CD3(+), identifying them as T lymphocytes. Lf labeling of these cells was mainly seen in the cytosol, but occasionally nuclear staining was seen as well, suggesting a direct regulatory role of Lf.

CONCLUSION

We propose that Lf functions in the immune defense of the small intestinal mucosa by targeting the population of T cells in the lamina propria.

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.

Lactoferrin decreases LPS-induced mitochondrial dysfunction in cultured cells and in animal endotoxemia model

Lactoferrin is a non-heme iron-binding glycoprotein, produced by mucosal epithelial cells and granulocytes in most mammalian species. It is involved in regulation of immune responses, possesses anti-oxidant, anti-carcinogenic, anti-inflammatory properties, and provides protection against various microbial infections. In addition, lactoferrin has been implicated in protection against the development of insult-induced systemic inflammatory response syndrome (SIRS) and its progression into septic conditions in vivo. Here we show a potential mechanism by which lactoferrin lessens oxidative insult at the cellular and tissue levels after lipopolysaccharide (LPS) exposure. Lactoferrin pretreatment of cells decreased LPS-mediated oxidative insults in a dose-dependent manner. Lipopolysaccharide-induced oxidative burst was found to be of mitochondrial origin, and release of reactive oxygen species (ROS) was localized to the respiratory complex III. Importantly, lactoferrin nearly abolished LPS-induced increases in mitochondrial ROS generation and the accumulation of oxidative damage in the DNA. In vivo, pretreatment of experimental animals with lactoferrin significantly (P<0.05) lowered LPS-induced mitochondrial dysfunction as shown by both decreased release of H(2)O(2) and DNA damage in the mitochondria. In contrast, deferoxamine, an iron chelating compound, provided only partial protection in LPS-treated animals. Together, these data suggest that lactoferrin protects against oxidative insult at the mitochondrial level, and indicate a potential utility of lactoferrin in prevention and treatment of SIRS.

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.

Human recombinant lactoferrin acts synergistically with antimicrobials commonly used in neonatal practice against coagulase-negative staphylococci and Candida albicans causing neonatal sepsis

Neonatal sepsis causes significant mortality and morbidity. Coagulase-negative staphylococci (CoNS) and Candida frequently cause neonatal sepsis at >72 h of age. Lactoferrin, which is present in human milk, is a component of innate immunity and has broad-spectrum antimicrobial activity. The synergistic effects of lactoferrin with antibiotics against neonatal isolates have not been systematically evaluated. Here, eight clinical strains (seven neonatal) of CoNS and three strains (two neonatal) of Candida albicans were studied. MIC50 and MIC90 values of human recombinant lactoferrin (talactoferrin; TLF), vancomycin (VAN) and nafcillin (NAF) against CoNS, and of TLF, amphotericin B (AMB) and fluconazole (FLC) against C. albicans, were evaluated according to established guidelines. Antimicrobial combinations of TLF with NAF or VAN against CoNS, and TLF with AMB or FLC against C. albicans, were evaluated by a checkerboard method with serial twofold dilutions. Synergy was evaluated by the median effects principle, and combination indices and dose reduction indices were reported at 50, 75 and 90% inhibitory effect at several drug-dose ratios. It was found that TLF acted synergistically with NAF and VAN against CoNS, and with AMB and FLC against C. albicans, at multiple dose effects and drug-dose ratios with few exceptions. In synergistic combinations, drug reduction indices indicated a significant reduction in doses of antibiotics, which may be clinically relevant. Thus TLF acts synergistically with anti-staphylococcal and anti-Candida agents commonly used in neonatal practice and is a promising agent that needs to be evaluated in clinical studies.

Lactoferrin acts as an alarmin to promote the recruitment and activation of APCs and antigen-specific immune responses

Lactoferrin is an 80-kDa iron-binding protein present at high concentrations in milk and in the granules of neutrophils. It possesses multiple activities, including antibacterial, antiviral, antifungal, and even antitumor effects. Most of its antimicrobial effects are due to direct interaction with pathogens, but a few reports show that it has direct interactions with cells of the immune system. In this study, we show the ability of recombinant human lactoferrin (talactoferrin alfa (TLF)) to chemoattract monocytes. What is more, addition of TLF to human peripheral blood or monocyte-derived dendritic cell cultures resulted in cell maturation, as evidenced by up-regulated expression of CD80, CD83, and CD86, production of proinflammatory cytokines, and increased capacity to stimulate the proliferation of allogeneic lymphocytes. When injected into the mouse peritoneal cavity, lactoferrin also caused a marked recruitment of neutrophils and macrophages. Immunization of mice with OVA in the presence of TLF promoted Th1-polarized Ag-specific immune responses. These results suggest that lactoferrin contributes to the activation of both the innate and adaptive immune responses by promoting the recruitment of leukocytes and activation of dendritic cells.

Prophylaxis with lactoferrin, a novel antimicrobial agent, in a neonatal rat model of coinfection

Lactoferrin has broad-spectrum antimicrobial activity, and the authors hypothesized that recombinant human lactoferrin (Talactoferrin alfa [TLF]) would reduce mortality and morbidity in a coinfection model. The MIC 50 (minimum inhibitory concentration required to inhibit the growth of 50% of organisms) of TLF against Candida albicans and Staphylococcus epidermidis was determined. Neonatal Wistar rats were infected with C albicans or S epidermidis or both, at doses of 2 x10(8) colony-forming units (CFUs) given subcutaneously. Rat pups in each group were randomly given TLF intraperitoneally at 40 mg/kg/dose or 300 mg/kg/dose, or saline in 0.2 mL, once a day for 4 d and were monitored for mortality, weight gain, and blood culture positivity. Trough serum levels of TLF were measured at 24, 48, 72, 96, and 144 h. MIC 50 of TLF was 30 microg/mL and 500 microg/mL for C albicans and S epidermidis, respectively. TLF prophylaxis significantly improved survival in the coinfection group at 40 mg/kg/dose (by 16.1%; P=.019) and at 300 mg/kg/dose (by 15.1%; P=.027) and in the S epidermidis group at a dose of 40 mg/kg/dose (by 18.6%; P=.04). Weight gain was not affected by TLF prophylaxis. Serum trough levels of TLF were 1000-fold lower than in vitro MIC 50. The authors conclude that lactoferrin prophylaxis significantly enhanced survival in coinfection and in the subgroup of S epidermidis infection (40 mg/kg/dose) through indirect mechanisms.

Interactions of lactoferrin with cells involved in immune function

The antimicrobial activities of lactoferrin (Lf) depend on its capacity to bind iron and on its direct interaction with the surface of microorganisms. Its protective effect also extends to the regulation of the host response to infections. Depending on the immune status of an individual, Lf can have anti-inflammatory properties that downregulate the immune response and prevent septic shock and damage to tissues. It also acts as a promoter of the activation, differentiation, and (or) proliferation of immune cells. Although most of the anti-inflammatory activities are correlated with the neutralization of proinflammatory molecules by Lf, the promoting activity seems to be related to a direct effect of Lf on immune cells. Although the mechanisms that govern these activities are not clearly defined, and probably differ from cell to cell, several cellular targets and possible mechanisms of action are highlighted. The majority of the molecular targets at the surface of cells are multiligand receptors but, interestingly, most of them have been reported as signaling, endocytosis, and nuclear-targeting molecules. This review focuses on the known and putative mechanisms that allow the immunoregulating effect of Lf in its interactions with immune cells.

Zinc, Iron, Copper, Selenium, Lactoferrin, and Ferritin in Human Pus

BACKGROUND

Restriction of zinc and iron available for microbial growth in tissues are well-recognized host defense mechanisms. The present studies were performed to characterize some constituents of human pus that may affect these important host defenses.

METHODS

Zinc, iron, copper, calcium, and magnesium in pus were measured using an atomic absorption spectrophotometer; selenium was measured fluorometrically. Ferritin was measured with a fluorometric enzyme immunoassay, and lactoferrin was measured with a radial diffusion assay. The growth of Escherichia coli at 37 degrees C was measured in pus supernate adjusted to pH 5.5 or 7.4, in boiled supernate, or in supernate adjusted with 1.3 mM iron or 0.9 mM zinc singly or together.

RESULTS

Zinc and iron concentrations in pus exceeded normal serum. Calcium and magnesium levels were 2- to 3-fold lower and higher, respectively, than normal serum values. Lactoferrin concentrations of were 880 +/- 48 microg/mL and ferritin levels were 20,726 +/- 2,667 ng/mL. Growth of an E coli strain was inhibited in pus at pH 5.5 but not at pH 7.4, and growth was enhanced by addition of iron or zinc to E coli suspended in pus at pH 6.7.

CONCLUSIONS

To our knowledge, this is the first report of the zinc, iron, copper, selenium, lactoferrin, and ferritin levels of human pus. These studies provide additional insight into host defense mechanisms mediated by the restriction of the bioavailability of zinc and iron in suppurative infection.

Compromised host defense on Pseudomonas aeruginosa biofilms: characterization of neutrophil and biofilm interactions

Pseudomonas aeruginosa is an opportunistic pathogen that forms biofilms on tissues and other surfaces. We characterized the interaction of purified human neutrophils with P. aeruginosa, growing in biofilms, with regard to morphology, oxygen consumption, phagocytosis, and degranulation. Scanning electron and confocal laser microscopy indicated that the neutrophils retained a round, unpolarized, unstimulated morphology when exposed to P. aeruginosa PAO1 biofilms. However, transmission electron microscopy demonstrated that neutrophils, although rounded on their dorsal side, were phagocytically active with moderate membrane rearrangement on their bacteria-adjacent surfaces. The settled neutrophils lacked pseudopodia, were impaired in motility, and were enveloped by a cloud of planktonic bacteria released from the biofilms. The oxygen consumption of the biofilm/neutrophil system increased 6- and 8-fold over that of the biofilm alone or unstimulated neutrophils in suspension, respectively. H(2)O(2) accumulation was transient, reaching a maximal measured value of 1 micro M. Following contact, stimulated degranulation was 20-40% (myeloperoxidase, beta-glucuronidase) and 40-80% (lactoferrin) of maximal when compared with formylmethionylleucylphenylalanine plus cytochalasin B stimulation. In summary, after neutrophils settle on P. aeruginosa biofilms, they become phagocytically engorged, partially degranulated, immobilized, and rounded. The settling also causes an increase in oxygen consumption of the system, apparently resulting from a combination of a bacterial respiration and escape response and the neutrophil respiratory burst but with little increase in the soluble concentration of H(2)O(2). Thus, host defense becomes compromised as biofilm bacteria escape while neutrophils remain immobilized with a diminished oxidative potential.

Monitoring the allergic inflammation

Individual symptoms of allergy such as asthma, dermatitis, rhinitis have many different underlying mechanisms. The detailed characterization of the inflammatory mechanisms underlying symptom development in the individual patient is important in order to optimally control treatment. Measurement of eosinophil cationic protein (ECP) in sputum or blood and eosinophil protein X/eosinophil derived neurotoxin (EPX/EDN) in urine may be used to read the involvement of the eosinophil granulocyte in the process. An important information as eosinophil dominated processes seem to be particularly sensitive to corticosteroid treatment. The possibilities to measure the involvement of other inflammatory cells exist today, but are only used to a small extent. The dream would be that every patient with an inflammatory disease is characterized with respect to the profile of involving cells and mediators. Such information would provide us with a unique understanding of the underlying mechanisms of the development of disease symptoms and the possibilities of treating these.

Lactoferrin reduces in vitro osteoclast differentiation and resorbing activity

Lactoferrin (LF) is a key modulator of inflammatory response. Since bone and immune systems are genetically and functionally linked, we were interested to know if LF could influence bone remodeling. Bovine LF (bLF) inhibited in vitro bone resorbing activity (IC50, 200 microg/ml) in a rabbit mixed bone cell culture, consisting of authentic osteoclasts in an environment of osteoblast and stromal cells. Using human CD14 selected cells committed toward osteoclasts, bLF (10 microg/ml) stimulated cell proliferation, however, led to an inhibition of calcitonin receptor mRNA expression, a main marker of osteoclast phenotype, and decreased the global resorbing activity. No modulation of RANK mRNA expression was observed and mRNA for RANKL and OPG were not detected in this culture system, suggesting that bLF inhibits osteoclastogenesis and reduces bone resorption through a mechanism independent of OPG/RANKL/RANK. In conclusion, bLF appears to modulate bone remodeling. Its mechanism of action remains to be elucidated.

Oxidative stress in phagocytes--"the enemy within"

Phagocytes represent a powerful defense system against invading microorganisms that threaten the life or functional integrity of the host. The capacity to generate and release substantial amounts of reactive oxygen species is a unique property of activated polymorphonuclear and mononuclear phagocytes. The crucial role of these molecules in killing microorganisms and their consecutive contribution to tissue damage during injury and inflammation is widely known. Although much research has been done to explore the molecular events involved in the interaction of oxygen intermediates with microbes or host tissue, surprisingly little attention has been paid to the effect of reactive metabolites on the phagocyte itself. This fact is especially surprising, since it is apparent that the activated phagocyte is directly exposed to its own toxic metabolites. The potential damage occurring during excessive radical formation might notably alter the vital functions of these primarily immunocompetent cells. Moreover, the critical role of oxygen radicals in apoptosis of leukocytes has been recently revealed. Apoptosis is now supposed to represent a key mechanism in neutrophil deactivation and resolution of inflammation. Therefore, this review will focus on the delicate balance between released oxidants and antioxidative protection within the phagocytes themselves. General and phagocyte-specific antioxidative mechanisms, which have co-evolved with the radical generating machinery of phagocytes, are discussed, since the outcome of local inflammation can directly depend on this antioxidative capacity and might range from adequate elimination of the pathogen with minimal acute tissue damage to progression towards a systemic inflammatory response syndrome.

Neutrophil beta(2)-microglobulin and lactoferrin content in renal failure patients

Multiple dysfunctions of polymorphonuclear leukocytes (PMNLs) contribute significantly to the increased morbidity and mortality among patients with end-stage renal disease. In the present study, we measured the PMNL content of beta(2)-microglobulin (beta(2)m) and lactoferrin in different states of renal insufficiency and after kidney transplantation. PMNLs were lysed ultrasonically and, after centrifugation, both proteins were assayed in the supernatant by enzyme-linked immunosorbent assay technique. Despite marked differences in plasma beta(2)m levels, no significant difference in PMNL content of beta(2)m and lactoferrin could be shown among the groups analyzed. There was also no correlation between plasma beta(2)m level and PMNL beta(2)m content. In control subjects, as well as in renal allograft recipients with a well-functioning graft, PMNL beta(2)m level correlated positively with PMNL lactoferrin level (pooled data, r = 0.55; P < 0.001; n = 55). Both proteins are considered to colocalize in peroxidase-negative PMNL granules. However, no correlation was found in the azotemic and uremic patient groups. Standard immunofluorescence staining of control PMNLs showed a cytoplasmic granular distribution of both granule proteins. However, in PMNLs of uremic patients, lactoferrin shifted to a perinuclear localization. PMNLs obtained from uremic individuals failed to elicit an increase in lactoferrin release after stimulation with the chemotactic peptide f-Met-Leu-Phe compared with PMNLs obtained from healthy volunteers. These data indicate abnormalities in uremic patients of PMNL granule lactoferrin content and release that are reversible after successful renal transplantation.

Progesterone via its receptor antagonizes the pro-inflammatory activity of estrogen in the mouse uterus

Populations of macrophages and neutrophils in the uterus are under the control of the female sex steroids estrogen and progesterone (P4). Their influx is induced by estrogen, while P4 can both stimulate and inhibit leukocyte influx depending on the timing of P4 with respect to estrogen. Regulation of leukocytes has been implicated in changes in uterine immune responses during the estrous cycle, pregnancy, and implantation. This work demonstrates that P4 given concurrently with estrogen to ovariectomized mice for 4 days antagonizes the ability of estrogen to recruit macrophages and neutrophils into the mouse uterus. Using progesterone receptor knockout (PRKO) mice, we show that this effect is dependent on progesterone receptors (PR). In the absence of PR, neutrophils recruited by estrogen were found to be degranulated, partially explaining the edema that is observed with long-term treatment of PRKO mice with estrogen and P4. Populations of B lymphocyte cells were shown to be unchanged by estrogen and P4 treatment in both wild-type and PRKO mice. The neutrophil chemotactic chemokine MIP-2 was examined for down-regulation by P4 but was found to be unaffected by hormonal treatment. Together, these observations demonstrate that PR has a strong anti-inflammatory role in the mouse uterus when estrogen and P4 are present together.

Targeted imaging of infection

The prompt identification, localization and characterization of focal sites of infection in the patients with fever is a critical step in clinical management, particularly, when localizing symptoms are not present. Although the classic signs of inflammation are suitable to localize injury at superficial sites or in the extremities, inflammation of internal structures, such as in the brain, chest and abdomen, can be difficult to localize without additional diagnostic procedures. Tissue injury, regardless of cause or anatomical site, results in a complex series of physiologic changes that we recognize as the inflammatory response. The inflammatory response is characterized by a series of biochemical events in the insulted cells and surrounding structures that results in the three major pathophysiological components: increased tissue perfusion, increased vascular permeability, and leukocytic exudation. Exploitation of the early attributes of the inflammatory process are not sufficient for the routine detection of inflammation. Currently, reagents for targeting infection represent cellular or protein components involved in the inflammatory process. Such approaches have met with some success as these agents comprise integral parts of the complex phenomena known as inflammation. This same fact also limits their utility. Improved agents for targeting infection will likely be based on small molecules whose diffusion into the lesion is not hindered by molecular size constraints and which bind to molecular targets at the site of infection/inflammation. In general, the lower molecular weight should also lead to enhanced blood clearance, avoiding elevated blood pool activity which contributes to background. New agents should also obviate the need to handle blood, as this represents potential hazards to both patient and the medical personnel alike.

NADPH-oxidase activity and lipid peroxidation in neutrophils from rats fed fat-rich diets

In order to investigate the effect of fat-rich diets on neutrophil functions, 21 day-aged rats were fed for 6 weeks with a control diet consisting of a regular laboratory rodent chow (4 per cent final fat content), a control diet supplied with soybean oil (15 per cent final fat content), or a control diet supplied with coconut oil (15 per cent final fat content). Glycogen-elicited peritoneal neutrophils from rats fed soybean and coconut oil-enriched diets presented a reduction in spontaneous and PMA-stimulated H2O2 generation relative to neutrophils from rats fed the control diet. The activity of superoxide dismutase, glutathione peroxidase and catalase did not change in animals fed fat-rich diets. In addition, the capacity to generate O2-, spontaneously or in response to PMA, did not change in neutrophils from animals fed fat-rich diets. Values attained matched those observed in animals fed the control diet, regardless of the method used to measure O2-, the superoxide dismutase-inhibitable reduction of cytochrome c or the lucigenin-dependent chemiluminescence. However, the initial rate of O2- generation both in resting neutrophils and in PMA-stimulated cells was significantly reduced when animals were fed with coconut or soybean oil-enriched diets due, at least in part, to a reduction in the activity of glucose-6-phosphate dehydrogenase. The concentration of thiobarbituric acid reactive substances, an index of lipid peroxidation, was increased in animals fed both fat-rich diets. This was accompanied by an increase in arachidonic acid content in these cells. Results presented suggest that lipid peroxidation in neutrophils from animals fed fat-rich diets may be associated with a consumption of H2O2 yielding more reactive oxygen-derived species such as the hydroxyl radical.

Detection of stable and active periodontitis sites by clinical assessment and gingival crevicular acute-phase protein levels

The aim of the present study was to investigate whether incipient periodontal disease breakdown could be associated with changes in gingival crevicular fluid (GCF) acute-phase protein levels. In addition, the potential of clinical indices to act as predictors of significant attachment level (AL) change was investigated. AL measurements were taken at baseline and 3 months using the Florida Probe stent handpiece from a total of 384 sites in 38 patients. The average standard deviation of duplicate AL measurements was 0.423. When the tolerance method was used to detect significant AL change, 3.9% of the sites lost attachment. When a less stringent criterion of AL change of > or = 1 mm was used 9.9% of the sites lost attachment during the 3-month period. With the exception of probing depth, baseline clinical parameters failed to predict AL change. Fourteen active periodontitis sites that demonstrated significant attachment loss were paired to stable periodontitis sites within the same patient. The levels of four acute-phase proteins, namely alpha 2-macroglobulin (alpha 2-M), alpha 1-antitrypsin (alpha 1-AT), transferrin (TF) and lactoferrin (LF), and also albumin (Alb) were assessed in the same gingival crevicular fluid sample using sandwich ELISAs. Results were expressed either as ng/30 s and ng/microgram Alb. Acute-phase protein levels in GCF failed to differentiate between active and stable periodontitis sites at baseline. In conclusion, the degree of gingival inflammation of the tissues adjacent to the crevice/pocket seems to influence the levels of protease inhibitors and iron-binding proteins in GCF to a greater extent than probing attachment loss.

Assessment of eosinophil and neutrophil participation in atopic dermatitis: comparison with the IgE-mediated late-phase reaction

We hypothesized that repeated IgE-mediated late-phase reactions are critical in the pathogenesis of atopic dermatitis (AD). Prior studies have shown that extracellular deposition of eosinophil granule major basic protein (MBP) occurs in lesional AD skin, despite a paucity of infiltrating eosinophils, and that deposition of both neutrophil and eosinophil granule proteins occurs in the IgE-mediated late-phase reaction. We evaluated the participation of both eosinophil and neutrophil granule proteins in AD. Cutaneous biopsy specimens and serum and urine samples were obtained from 22 patients with AD. Lesional tissue was examined by means of immunofluorescence for neutrophil elastase and lactoferrin and for eosinophil granule MBP, eosinophil-derived neurotoxin (EDN), and eosinophil cationic protein (ECP). Serum levels of elastase, MBP, EDN, and ECP and urine levels of MBP, EDN, and ECP were measured. Marked extracellular deposition of at least one of the eosinophil granule proteins was present in the dermis of 15 of the 22 AD skin specimens, but minimal or no extracellular neutrophil elastase or lactoferrin deposition was observed in any specimens. Serum and urine levels of MBP, EDN, and ECP in the patients were elevated when compared with those of normal controls, whereas serum levels of neutrophil elastase were not elevated. Serum MPB levels correlated with extent of body surface involvement. These results suggest that eosinophil degranulation occurs in AD but that neutrophil degranulation does not. Although eosinophil degranulation is prominent in both the late-phase reaction and in AD, the lack of neutrophil degranulation in AD demonstrates differences in the inflammatory reactions.

Elastase and lactoferrin in gingival crevicular fluid: possible indicators of a granulocyte-associated specific host response

Periodontitis affects a limited number of susceptible humans. The aim of this study was to determine whether there is a difference in the inflammatory reaction between patients with gingivitis and those with periodontitis. For this purpose the levels of elastase and lactoferrin were measured in gingival crevicular fluid (GCF) from three types of sites: i) inflamed sites in patients with gingivitis alone, inflamed sites both ii) with and iii) without tissue destruction in patients with periodontitis. Elastase activity, measured with a chromogenic substrate was significantly higher in the two types of sites in periodontitis patients. Lactoferrin levels, measured with ELISA were the same in the three types of sites. In vitro activation of granulocytes from healthy volunteers with Fc-receptor stimulation showed that the entire release of lactoferrin occurred immediately. In contrast, elastase release was time-dependent and continued throughout the experiment. Thus, the degranulation of the specific (lactoferrin) and azurophil granule (elastase) are under separate control and the two parameters can be combined in a ratio in order to characterize the granulocytes of a given patient. Assuming an immediate release of lactoferrin from the activated granulocytes in vivo, similar amounts of lactoferrin in the three types of sites can be regarded as reflecting similar numbers of granulocytes in the three types of sites. Consequently, a higher elastase activity in GCF from patients with periodontitis indicates a higher rate of release from the cells per se and a granulocyte-associated specific host response.

Acute-phase proteins in gingival crevicular fluid during experimentally induced gingivitis

The dynamics of four acute-phase proteins were investigated in gingival crevicular fluid (GCF) during the course of a 21 day experimental gingivitis study. These acute-phase proteins were the protease inhibitors alpha 2-macroglobulin (alpha 2-M) and alpha 1-antitrypsin (alpha 1-AT) and the iron-binding proteins transferrin (TF) and lactoferrin (LF). 6 healthy volunteers ceased all oral hygiene procedures for 3 weeks. GCF was sampled at seven day intervals from two sites per subject by paper strips for 30 s during the experimental gingivitis period and for two additional weeks after the reinstitution of oral hygiene. The mainly serum derived alpha 2-M, alpha 1-AT and TF exhibited very similar dynamics which reflects their common origin in GCF. Their levels increased significantly from baseline and remained high for at least one week after the reinstitution of oral hygiene measures (repeated measures MANOVA; alpha 2-M: p = 0.015; alpha 1-AT: p = 0.012; TF: p = 0.02). This probably reflects increased vascular permeability in the gingivae and, to a lesser degree, local production by gingival inflammatory cells. In contrast to the serum derived acute-phase proteins, the neutrophil derived LF rose significantly from baseline (repeated measures MANOVA; p = 0.001) but dropped rapidly after the reinstitution of oral hygiene measures. This could be because dental plaque was removed and thus neutrophil chemotactic agents in the crevice were decreased.

Radioimmunometric quantification of surface lactoferrin in blood mononuclear cells

A radioimmunometric method was developed for the quantification of lactoferrin molecules natively bound to blood monocyte and lymphocyte surfaces and the estimation of the surface lactoferrin-binding capacity of these cells after their incubation with exogenous lactoferrin. Values of surface lactoferrin obtained were greatest for monocyte-rich isolates (9,168 +/- 1,713 molecules/cell; n = 19). The values of monocyte surface lactoferrin for males were similar to those of premenopausal females (8,980 +/- 2,378 (n = 8) and 9,427 +/- 2,606 molecules/cell (n = 11), respectively), but males had slightly lower values of monocyte surface lactoferrin binding capacity than did premenopausal females (10,447 +/- 2,478 molecules/cell versus 15,958 +/- 3,731 molecules/cell, respectively; p > 0.05). Expressed as saturation of the monocyte surface lactoferrin binding capacity, values of 97.2% +/- 22.6% for males and 76.6% +/- 14.3% for females were calculated. Intermediate values of surface lactoferrin were found in B-lymphocyte-rich isolates from five patients with B-cell chronic lymphocytic leukemia. In T-lymphocyte-rich preparations, there were low levels of native lactoferrin expression (154 +/- 63 molecules of lactoferrin/cell; 3 isolates). The present technique should permit additional quantitative studies of mononuclear cell surface lactoferrin to determine the role of lactoferrin surface binding and analyses of factors that modulate this binding.

Maternal lactoferrin in the urine of preterm infants. Evidence for retention of structure and function

Intact (i.e., 78-kDa) lactoferrin has been purified from the urine of preterm infants fed human milk. The maternal origin of this lactoferrin, and the integrity of its primary structure have been documented. Computer analyses of the circular dichroism spectra revealed a composite secondary structure for the urinary lactoferrin that was indistinguishable from that of purified human milk lactoferrin and similar to that observed in the crystal structure. Intact function was suggested by iron binding; an approximate 2:1 molar ratio of iron to lactoferrin was confirmed. Thus, maternal lactoferrin is absorbed intact by the preterm infant and appears to remain structurally and functionally intact within the circulatory system and during urinary excretion. It is possible, therefore, that maternal lactoferrin has an immunoregulatory influence in newborn infants fed human milk.

Nitric oxide interaction with lactoferrin and its production by macrophage cells studied by EPR and spin trapping

The production of nitrate (NO3-) and nitrite (NO2-) from macrophage-derived NO was studied using EPR and spin trapping. The formation of NO3- was determined via EPR in reactions involving the iron-binding protein, lactoferrin. The formation of NO2- was determined via EPR/spin trapping in the reaction between NO2- and H2O2. Dissolved nitric oxide (NO.) was reacted with lactoferrin yielding an EPR spectrum (77 degrees K) different from the normal EPR spectrum obtained for lactoferrin, suggesting that NO. interacts with the ferric ions bound to lactoferrin forming a ferric-nitrosyl type complex. The EPR spectrum (77 degrees K) of this ferric-nitrosyl type complex was also observed in the supernatant fluid of macrophage cell suspensions following their stimulation with lipopolysaccharide (LPS). During LPS stimulation of macrophages, these cells generate NO. which in turn produces NO3- and NO2-. The ferric-nitrosyl type complex is formed in a reaction mixture containing apolactoferrin and bicarbonate following the reaction of Fe+2 with NO3-, generated from macrophage-derived NO(.), to produce Fe+3 and NO(.). Furthermore, in an acidic medium, NO2- reacts with H2O2 forming peroxynitrous acid (HOONO) which rapidly decomposes into hydroxyl radicals (.OH) and the nitrogen dioxide (NO2.) radical. In the supernatant fluid of LPS-stimulated macrophage suspensions, the production of .OH was verified by spin trapping using 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) as the spin trap and ethanol as the .OH scavenger. The EPR spectra corresponding to the DMPO-OH and the DMPO-hydroxyethyl adducts were identified.(ABSTRACT TRUNCATED AT 250 WORDS)

An enzyme-linked immunosorbent assay for plasma-lactoferrin. Concentrations in 362 healthy, adult blood donors

Very different concentrations of plasma-lactoferrin in healthy adults have been reported in the literature. We compared three commercially available lactoferrins and lactoferrin purified in our laboratory as calibrators in an ELISA. No statistical differences among these preparations of lactoferrin were detected. The concentration of purified lactoferrin was measured by dry weight, and efforts were made in order to minimize loss of purified lactoferrin by adhesion to tubes etc. and thus, secure accuracy of the method. Dilutions were made in PBS 0.01 mol l-1 with NaCl 0.436 mol l-1, (NH4)2SO4 0.5 mol l-1, BSA 5 gl-1 and normal rabbit IgG 10 mg l-1, which was shown to give parallel dilution curves of primary calibrator, secondary calibrator and plasma samples. No significant difference in the content of lactoferrin in neutrophils (median; range) among men (1.78; 0.83-4.48 micrograms 10(-6) neutrophils; n = 20) and women (2.12; 1.16-9.30 micrograms 10(-6) neutrophils; n = 14) was found. Lactoferrin was analysed in EDTA-plasma obtained from 135 female and 227 male blood donors. Median concentrations were 84.7 and 97.8 micrograms l-1 respectively, while 2.5% and 97.5% reference limits (with 90% confidence intervals) were estimated to 42.9 (38.7-47.4) micrograms l-1 and 166.9 (151.0-186.3) micrograms l-1 for women and 52.3 (49.1-55.6) micrograms l-1 and 189.9 (175.9-206.4) micrograms l-1 for men, respectively.