A component of innate immunity prevents bacterial biofilm development

Antimicrobial factors form one arm of the innate immune system, which protects mucosal surfaces from bacterial infection. These factors can rapidly kill bacteria deposited on mucosal surfaces and prevent acute invasive infections. In many chronic infections, however, bacteria live in biofilms, which are distinct, matrix-encased communities specialized for surface persistence. The transition from a free-living, independent existence to a biofilm lifestyle can be devastating, because biofilms notoriously resist killing by host defence mechanisms and antibiotics. We hypothesized that the innate immune system possesses specific activity to protect against biofilm infections. Here we show that lactoferrin, a ubiquitous and abundant constituent of human external secretions, blocks biofilm development by the opportunistic pathogen Pseudomonas aeruginosa. This occurs at lactoferrin concentrations below those that kill or prevent growth. By chelating iron, lactoferrin stimulates twitching, a specialized form of surface motility, causing the bacteria to wander across the surface instead of forming cell clusters and biofilms. These findings reveal a specific anti-biofilm defence mechanism acting at a critical juncture in biofilm development, the time bacteria stop roaming as individuals and aggregate into durable communities.

Autoimmune-related pancreatitis is associated with autoantibodies and a Th1/Th2-type cellular immune response

BACKGROUND & AIMS

Although autoimmunity may be involved in some cases of pancreatitis, the mechanism is still unknown. To clarify this, we studied serum autoantibodies, subsets of lymphocytes, and the Th1/Th2 balance of cellular immune responses in patients with autoimmune-related pancreatitis (AIP).

METHODS

Seventeen patients with AIP (8 men and 9 women; age, 53.2 +/- 13.0 years) were studied. Autoantibodies including antilactoferrin (ALF) or carbonic anhydrase II antibody (ACA-II) were examined using the enzyme-linked immunosorbent assay (ELISA) or the indirect fluorescein antibody method. Intracellular cytokines (interferon gamma and interleukin 4) and subtypes of peripheral blood lymphocytes were examined by flow cytometry and ELISA.

RESULTS

More than one autoantibody was observed in all 17 patients. Serum antinuclear antibody was detected in 13 of 17 patients, ALF antibody in 13, ACA-II antibody in 10, rheumatoid factor in 5, and anti-smooth muscle antibody in 3, but antimitochondrial antibody in none. The serum levels of ACA-II and LF antibody were not correlated. HLA-DR(+)CD8(+) and HLA-DR(+)CD4(+) cells were significantly increased in peripheral blood (P < 0.05). CD4(+) cells producing interferon gamma and the secreted levels were significantly increased compared with those in controls (P < 0.05), but interleukin 4 was not increased.

CONCLUSIONS

An autoimmune mechanism against CA-II or LF, and Th1-type immune response, may be involved in AIP.

Inhibition of SARS pseudovirus cell entry by lactoferrin binding to heparan sulfate proteoglycans

It has been reported that lactoferrin (LF) participates in the host immune response against Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) invasion by enhancing NK cell activity and stimulating neutrophil aggregation and adhesion. We further investigated the role of LF in the entry of SARS pseudovirus into HEK293E/ACE2-Myc cells. Our results reveal that LF inhibits SARS pseudovirus infection in a dose-dependent manner. Further analysis suggested that LF was able to block the binding of spike protein to host cells at 4°C, indicating that LF exerted its inhibitory function at the viral attachment stage. However, LF did not disrupt the interaction of spike protein with angiotensin-converting enzyme 2 (ACE2), the functional receptor of SARS-CoV. Previous studies have shown that LF colocalizes with the widely distributed cell-surface heparan sulfate proteoglycans (HSPGs). Our experiments have also confirmed this conclusion. Treatment of the cells with heparinase or exogenous heparin prevented binding of spike protein to host cells and inhibited SARS pseudovirus infection, demonstrating that HSPGs provide the binding sites for SARS-CoV invasion at the early attachment phase. Taken together, our results suggest that, in addition to ACE2, HSPGs are essential cell-surface molecules involved in SARS-CoV cell entry. LF may play a protective role in host defense against SARS-CoV infection through binding to HSPGs and blocking the preliminary interaction between SARS-CoV and host cells. Our findings may provide further understanding of SARS-CoV pathogenesis and aid in treatment of this deadly disease.

Lactoferrin as a natural immune modulator

Lactoferrin, an iron-binding glycoprotein, is a cell-secreted mediator that bridges innate and adaptive immune function in mammals. It is a pleiotropic molecule that directly assists in the influence of presenting cells for the development of T-helper cell polarization. The aim of this review is to provide an overview of research regarding the role of lactoferrin in maintaining immune homeostasis, in particular as a mediator of immune responses to infectious assault, trauma and injury. These findings are critically relevant in the development of both prophylactic and therapeutic interventions in humans. Understanding these particular effects of lactoferrin will provide a logical framework for determining its role in health and disease.

Lactoferrin down-regulates the LPS-induced cytokine production in monocytic cells via NF-kappa B

Lactoferrin, a glycoprotein present in milk, mucosal secretions and neutrophils contributes to host defense. We have previously shown that orally given milk lactoferrin (LF) mediates anti-infectious and anti-inflammatory activities in vivo. Moreover, we have shown that LF could inhibit the LPS-induced IL-6 secretion in a human monocytic cell line, THP-1. This observation was expanded in the present study investigating the capacity of LF to inhibit cytokine mRNA expression and the involvement of nuclear transcription factor kappa B (NF-kappa B). Cells (THP-1 and Mono Mac 6 monocytic cell lines) were stimulated with Escherichia coli LPS (5-10 ng/10(6) cells) and LF was added (50-500 microg/10(6) cells) 30 min before, or after the LPS addition. By a semiquantitative RT-PCR lower levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 mRNA expression were detected at the peak of the expression in THP-1 cells treated with LF. The reduction in the cytokine expression was followed by a similar reduction in the secreted cytokines as analyzed by ELISA. LF down-regulated also the IL-10 secretion (detected only in LPS-stimulated Mono Mac 6 cells). A similar level of inhibition of these cytokines was detected regardless of the time at which LF was added to the cells in relation to LPS. In addition, LF was internalized into cells and detected in the nucleoli as determined by immunostaining and immunofluorescence. Moreover, by electrophoretic mobility shift assay (EMSA) analysis LF decreased the LPS-induced binding of NF-kappa B to the TNF-alpha promoter. The results show that LF down-regulates the LPS-induced cytokine production in monocytic cells. The inhibitory mechanism is suggested to involve the interference of LF with NF-kappa B activation.

An immune-based biomarker signature is associated with mortality in COVID-19 patients

Immune and inflammatory responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contribute to disease severity of coronavirus disease 2019 (COVID-19). However, the utility of specific immune-based biomarkers to predict clinical outcome remains elusive. Here, we analyzed levels of 66 soluble biomarkers in 175 Italian patients with COVID-19 ranging from mild/moderate to critical severity and assessed type I IFN-, type II IFN-, and NF-κB-dependent whole-blood transcriptional signatures. A broad inflammatory signature was observed, implicating activation of various immune and nonhematopoietic cell subsets. Discordance between IFN-α2a protein and IFNA2 transcript levels in blood suggests that type I IFNs during COVID-19 may be primarily produced by tissue-resident cells. Multivariable analysis of patients' first samples revealed 12 biomarkers (CCL2, IL-15, soluble ST2 [sST2], NGAL, sTNFRSF1A, ferritin, IL-6, S100A9, MMP-9, IL-2, sVEGFR1, IL-10) that when increased were independently associated with mortality. Multivariate analyses of longitudinal biomarker trajectories identified 8 of the aforementioned biomarkers (IL-15, IL-2, NGAL, CCL2, MMP-9, sTNFRSF1A, sST2, IL-10) and 2 additional biomarkers (lactoferrin, CXCL9) that were substantially associated with mortality when increased, while IL-1α was associated with mortality when decreased. Among these, sST2, sTNFRSF1A, IL-10, and IL-15 were consistently higher throughout the hospitalization in patients who died versus those who recovered, suggesting that these biomarkers may provide an early warning of eventual disease outcome.

Towards a structure-function analysis of bovine lactoferricin and related tryptophan- and arginine-containing peptides

The iron-binding protein lactoferrin is a multifunctional protein that has antibacterial, antifungal, antiviral, antitumour, anti-inflammatory, and immunoregulatory properties. All of these additional properties appear to be related to its highly basic N-terminal region. This part of the protein can be released in the stomach by pepsin cleavage at acid pH. The 25-residue antimicrobial peptide that is released is called lactoferricin. In this work, we review our knowledge about the structure of the peptide and attempt to relate this to its many functions. Microcalorimetry and fluorescence spectroscopy data regarding the interaction of the peptide with model membranes show that binding to net negatively charged bacterial and cancer cell membranes is preferred over neutral eukaryotic membranes. Binding of the peptide destabilizes the regular membrane bilayer structure. Residues that are of particular importance for the activity of lactoferricin are tryptophan and arginine. These two amino acids are also prevalent in "penetratins", which are regions of proteins or synthetic peptides that can spontaneously cross membranes and in short hexapeptide antimicrobial peptides derived through combinatorial chemistry. While the antimicrobial, antifungal, antitumour, and antiviral properties of lactoferricin can be related to the Trp/Arg-rich portion of the peptide, we suggest that the anti-inflammatory and immunomodulating properties are more related to a positively charged region of the molecule, which, like the alpha- and beta-defensins, may act as a chemokine. Few small peptides are involved in as wide a range of host defense functions as bovine and human lactoferricin.

Salivary defense proteins: their network and role in innate and acquired oral immunity

There are numerous defense proteins present in the saliva. Although some of these molecules are present in rather low concentrations, their effects are additive and/or synergistic, resulting in an efficient molecular defense network of the oral cavity. Moreover, local concentrations of these proteins near the mucosal surfaces (mucosal transudate), periodontal sulcus (gingival crevicular fluid) and oral wounds and ulcers (transudate) may be much greater, and in many cases reinforced by immune and/or inflammatory reactions of the oral mucosa. Some defense proteins, like salivary immunoglobulins and salivary chaperokine HSP70/HSPAs (70 kDa heat shock proteins), are involved in both innate and acquired immunity. Cationic peptides and other defense proteins like lysozyme, bactericidal/permeability increasing protein (BPI), BPI-like proteins, PLUNC (palate lung and nasal epithelial clone) proteins, salivary amylase, cystatins, prolin-rich proteins, mucins, peroxidases, statherin and others are primarily responsible for innate immunity. In this paper, this complex system and function of the salivary defense proteins will be reviewed.

Identification of lactoferrin as the granulocyte-derived inhibitor of colony-stimulating activity production

Lactoferrin (LF), the iron-binding protein present in the specific granules of mature granulocytes has been identified as colony inhibitory factor (CIF) which suppresses granulocyte--macrophage colony stimulating activity (CSA) production by monocytes and macrophages in vitro and rebound granulopoiesis in vivo. Separation of LF and CIF by isoelectric focusing confirmed that the regions of inhibitory activity corresponded in both to a pH of congruent to 6.5. In addition, the purified immunoglobulin fraction of rabbit anti-human LF antiserum, but not rabbit anti-transferrin (TF), inactivated the capacity of LF and CIF to inhibit CSA production, an effect blocked by prior incubation of anti-LF with neutralizing concentrations of LF. Suppression of CSA production correlated with the iron-saturation of LF; APO-LF (depleted of iron) was only active concentrations greater than 10(-7) M, native LF (8% iron saturated) was active at 10(-15) M, and fully iron-saturated LF inhibited at 10(-17) M. Suppression of CSA production occurred within a 1/2-h preincubation period with human blood monocytes but was reversed by bacterial lipopolysaccharide (LPS). This reversal was dependent on the relative concentrations of LF to LPS. Serum TF, a biochemically similar iron-binding protein which is antigenically distinct from LF, was only minimally active at concentrations greater than 10(-6) M. LF did not inhibit exogenously stimulated human granylocyte and macrophage colony-forming cells or erythropoietin-dependent human or murine erythroid colony- or erythroid burst-forming cells. Microgram quantities of LF acted in vivo to inhibit rebound granulopoiesis and CSA production in CD1 and C57Bl/6 mice pretreated with cyclophosphamide. These results strongly implicate LF as a physiological regulator of granulopoiesis.

Lactoferrin and host defense

Lactoferrin is a multifunctional member of the transferrin family of nonheme iron-binding glycoproteins. Lactoferrin is found at the mucosal surface where it functions as a prominent component of the first line of host defense against infection and inflammation. The protein is also an abundant component of the specific granules of neutrophils and can be released into the serum upon neutrophil degranulation. While the iron-binding properties were originally believed to be solely responsible for the host defense properties ascribed to lactoferrin, it is now known that other mechanisms contribute to the broad spectrum anti-infective and anti-inflammatory roles of this protein. In this article, current information on the functions and mechanism of action of lactoferrin are reviewed, with particular emphasis on the activities that contribute to this protein's role in host defense. In addition, studies demonstrating that lactoferrin inhibits allergen-induced skin inflammation in both mice and humans, most likely secondary to TNF-alpha (tumor necrosis factor alpha) production, are summarized. Collectively, these results suggest that lactoferrin functions as a key component of mammalian host defense at the mucosal surface.

PspA protects Streptococcus pneumoniae from killing by apolactoferrin, and antibody to PspA enhances killing of pneumococci by apolactoferrin [corrected]

Lactoferrin is an important component of innate immunity through its sequestration of iron, bactericidal activity, and immune modulatory activity. Apolactoferrin (ALF) is the iron-depleted form of lactoferrin and is bactericidal against pneumococci and several other species of bacteria. We observed that lactoferricin (LFN), an 11-amino-acid peptide from the N terminus of lactoferrin, is bactericidal for Streptococcus pneumoniae. Strains of S. pneumoniae varied in their susceptibility to ALF. Lactoferrin is bound to the pneumococcal surface by pneumococcal surface protein A (PspA). Using mutant PspA(-) pneumococci of four different strains, we observed that PspA offers significant protection against killing by ALF. Knockout mutations in genes for two other choline-binding proteins (PspC and PcpA) did not affect killing by ALF. PspA did not have to be attached to the bacterial surface to inhibit killing, because the soluble recombinant N-terminal half of PspA could prevent killing by both ALF and LFN. An 11-amino-acid fragment of PspA was also able to reduce the killing by LFN. Antibody to PspA enhanced killing by lactoferrin. These findings suggested that the binding of ALF to PspA probably blocks the active site(s) of ALF that is responsible for killing.

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.

Clinical analysis of autoimmune-related pancreatitis

OBJECTIVE

Several investigators have reported on autoimmune-related pancreatitis, but the clinical findings and pathophysiology still remain unclear. To clarify it, we analyzed eight patients with autoimmune pancreatitis.

METHODS

We evaluated clinical findings in eight patients (four men and four women) with autoimmune-related pancreatitis. Patients were aged 45-73 yr (mean, 57.5 yr). We examined blood chemistry and immunological studies, including autoantibodies against lactoferrin or carbonic anhydrase II, and compared ERCP images with clinical findings. In two patients, we studied the subset of lymphocytes infiltrating in the pancreas by immunohistochemistry and flow cytometry.

RESULTS

Four of eight patients had jaundice, two had renal dysfunction, two had abdominal pain, and two had back pain. Three patients were complicated with other autoimmune diseases. Three patients showed abnormal pancreatic exocrine function by an N-benzoyl-L-tyrosyl-para-aminobenzoic acid excretion test. Antinuclear antibody was detected in four of eight patients, antilactoferrin antibody in three of six, anticarbonic anhydrase II antibody in two of six, antismooth muscle antibody in two of seven, and rheumatoid factor in one of eight. All eight patients showed segmental stenosis of the main pancreatic duct by ERCP. Four patients showed stenosis of the common bile duct as well as the pancreatic duct. Microscopic findings showed infiltration of CD4-positive lymphocytes around the pancreatic duct, and HLA-DR was expressed on both CD4-positive cells and pancreatic duct cells. In two patients, stenosis of the pancreatic duct improved by prednisolone.

CONCLUSIONS

Autoimmune mechanism may be involved in some patients with idiopathic pancreatitis associated with hypergammaglobulinemia.

N-terminal stretch Arg2, Arg3, Arg4 and Arg5 of human lactoferrin is essential for binding to heparin, bacterial lipopolysaccharide, human lysozyme and DNA

Human lactoferrin (hLF), a protein involved in host defence against infection and excessive inflammation, interacts with heparin, the lipid A moiety of bacterial lipopolysaccharide, human lysozyme (hLZ) and DNA. To determine which region of the molecule is important in these interactions, solid-phase ligand binding assays were performed with hLF from human milk (natural hLF) and N-terminally deleted hLF variants. Iron-saturated and natural hLF bound equally well to heparin, lipid A, hLZ and DNA. Natural hLF lacking the first two N-terminal amino acids (Gly1-Arg2) showed reactivities of one-half, two-thirds, one-third and one-third towards heparin, lipid A, hLZ and DNA respectively compared with N-terminally intact hLF. A lack of the first three residues (Gly1-Arg2-Arg3) decreased binding to the same ligands to one-eighth, one-quarter, one-twentieth and one-seventeenth respectively. No binding occurred with a mutant lacking the first five residues (Gly1-Arg2-Arg3-Arg4-Arg5). An anti-hLF monoclonal antibody (E11) that reacts to an N-lobe epitope including Arg5 completely blocked hLF-ligand interaction. These results show that the N-terminal stretch of four consecutive arginine residues, Arg2-Arg3-Arg4-Arg5, has a decisive role in the interaction of hLF with heparin, lipid A, hLZ and DNA. The role of limited N-terminal proteolysis of hLF in its anti-infective and anti-inflammatory properties is discussed.

Antibacterial and antiviral activity of camel milk protective proteins

Lysozyme (LZ), lactoferrin (LF), lactoperoxidase (LP), immunoglobulin G and secretory immunoglobulin A were extracted from camel milk. The activity of these protective proteins was assayed against Lactococcus lactis subsp. cremoris, Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and rotavirus. Comparative activities of egg white LZ, bovine LZ and bovine LF are also presented. The antibacterial activity spectrum of camel milk LZ was similar to that of egg white LZ, and differed from bovine milk LZ. Bovine and camel milk LF antibacterial activity spectra were similar. The camel milk LP was bacteriostatic against the Gram-positive strains and was bactericidal against Gram-negative cultures. The immunoglobulins had little effect against the bacteria but high titres of antibodies against rotavirus were found in camel milk. The LP system was ineffective against rotavirus.

Bovine lactoferrin and lactoferricin derived from milk: production and applications

Bovine lactoferrin is produced on an industrial scale from cheese whey or skim milk. The safety of purified lactoferrin has been confirmed from the results of a reverse mutation test using bacteria, a 13-week oral repeated-dose toxicity study in rats, and clinical studies. In order to apply active lactoferrin to various products, a process for its pasteurization was developed. Subsequently, lactoferrin has been used in a wide variety of products since it was first added to infant formula in 1986. A pepsin hydrolysate of lactoferrin is also used in infant formula. This hydrolysate contains a potent antimicrobial peptide named lactoferricin that is derived from the lactoferrin molecule by pepsin digestion. Semilarge-scale purification of lactoferricin can be performed by hydrophobic interaction chromatography. Lactoferricin also exhibits several biological actions and appears to be the functional domain of lactoferrin. Recent studies have demonstrated that oral administration of lactoferrin or lactoferricin exerts a host-protective effect in various animals and in humans. The results of these studies strongly suggest that the effects of oral lactoferrin are mediated by modulation of the immune system. Further elucidation of the clinical efficacy and mechanism of action of lactoferrin will increase the value of lactoferrin-containing products.

Cow's milk allergens identification by two-dimensional immunoblotting and mass spectrometry

Cow's milk allergy (CMA) has become a common disease in early childhood, its prevalence ranging from 1.6% to 2.8% among children younger than 2 years of age. The role of different cow's milk protein (CMP) in the pathogenesis of CMA is still controversial. Even if the proteins most frequently and most intensively recognized by immunoglobulin E (IgE) seem to be the most abundant in milk (caseins and beta-lactoglobulin), with an although great variability all milk proteins appear to be potential allergens, even those that are present in trace amounts (i.e., lactoferrin, IgG, and BSA). In this work proteomics techniques have been applied for CMP allergens analysis. Allergens have been identified by immunoblotting following resolution of CMP components by two-dimensional electrophoresis. Sera from 20 milk-allergic subjects, as proven by oral provocation test, CAP-RAST and skin prick test, have been used for cow's milk major allergen identification. Cow's milk proteins and their isoforms were identified by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF)-mass spectrometry. In our group of patients, the prevalence of CMP allergens, i.e., the total number of subjects sensitized to CMP divided by the total number of the subjects enrolled in the study, was: 55% alpha(s1)-casein, 90% alpha(s2)-casein, 15% beta-casein, 50% kappa-casein, 45% beta-lactoglobulin, 45% BSA, 95% IgG-heavy chain, 50% lactoferrin, and 0% alpha-lactalbumin.

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.

Identification of a novel autoantibody against pancreatic secretory trypsin inhibitor in patients with autoimmune pancreatitis

OBJECTIVES

Although autoimmune pancreatitis (AIP) has been recently recognized as a new disease entity of chronic pancreatitis, the clinical diagnosis of the disease remains disputed. Autoantibodies against carbonic anhydrase II and lactoferrin are detected in most patients with AIP, but not in about 10%. We undertook this study to determine whether additional autoantibodies are present in the serum level of AIP patients.

METHODS

We recruited 26 patients with AIP for the study. For comparison, we also recruited 53 patients with various pancreatic diseases and 12 healthy subjects. We immunoscreened human pancreatic cDNA library using patients' sera. Positive clones were analyzed by DNA sequencing and were constructed into a pGEX-4T-1 expression vector. The recombinant proteins were used as antigens in enzyme-linked immunosorbent assay to screen the subjects' sera for autoantibodies.

RESULTS

We cloned a cDNA encoding the pancreatic secretory trypsin inhibitor (PSTI). Among 26 patients with AIP, autoantibodies against PSTI were significantly positive in 11 (42.3%) by western blotting and in 8 (30.8%) by enzyme-linked immunosorbent assay, respectively. However, none of control subjects was positive for anti-PSTI antibodies.

CONCLUSIONS

These findings suggest that PSTI may be related to the pathogenesis of AIP, and autoantibodies against PSTI can be a useful diagnostic marker for the disease.

Antiinflammatory activities of lactoferrin

Lactoferrin is a non-heme iron binding glycoprotein produced during lactation and by epithelial cells at mucosal surfaces. The protein is a prominent component of the first line of mammalian host defense and its expression is upregulated in response to inflammatory stimuli. In this paper, the antibacterial and immune modulatory properties of lactoferrin that contribute to host defense are reviewed. In addition, the results of recent preclinical and clinical studies demonstrating that lactoferrin acts as an inhibitor of dermal inflammatory cytokine production are summarized. The results indicate that lactoferrin may act as a potent anti-inflammatory protein at local sites of inflammation including the respiratory and gastrointestinal tracts.

Cryopreserved bovine mammary cells to model epithelial response to infection

Mammary gland epithelial cells are likely to be important effectors in defending against mastitis, yet little is known about their response mechanisms. Here, we describe a cryopreserved bovine mammary epithelial cell model to study the infection response. Primary cell cultures from four Holstein cows were prepared, and frozen after two passages. The cell cultures from each cow were then thawed and maintained separately, yet simultaneously, and exposed to treatments that included infection with Staphylococcus aureus or exposure to LPS from Escherichia coli. A clear inflammatory response was shown by a significant (P < 0.05), dose dependent, increase of lactoferrin and IL-8 secretion within 24h in response to S. aureus or LPS. Marked increases (P < 0.05) in lactoferrin, TNF-alpha and serum amyloid A (SAA) mRNA expression were also observed. The results indicate the usefulness of our model to study infection responses of mammary epithelial cells, where all cells are simultaneously exposed to the same infection pressure. These responses can be studied over time, and most importantly, biological replication is provided by the four different genotypes being investigated individually. Finally, the results indicate that mammary epithelial cells play an important role in inflammatory response, through the production of pro-inflammatory cytokines, an acute phase protein, and lactoferrin.

Lactoferrin activates macrophages via TLR4-dependent and -independent signaling pathways

Lactoferrin (LF) is a component of innate immunity and is known to interact with accessory molecules involved in the TLR4 pathway, including CD14 and LPS binding protein, suggesting that LF may activate components of the TLR4 pathway. In the present study, we have asked whether bovine LF (bLF)-induced macrophage activation is TLR4-dependent. Both bLF and LPS stimulated IL-6 production and CD40 expression in RAW 264.7 macrophages and in BALB/cJ peritoneal exudate macrophages. However, in macrophages from congenic TLR4(-/-) C.C3-Tlr4(lps-d) mice, CD40 was not expressed while IL-6 secretion was increased relative to wild-type cells. The signaling components NF-kappaB, p38, ERK and JNK were activated in RAW 264.7 cells and BALB/cJ macrophages after bLF or LPS stimulation, demonstrating that the TLR4-dependent bLF activation pathway utilizes signaling components common to LPS activation. In TLR4 deficient macrophages, bLF-induced activation of NF-kappaB, p38, ERK and JNK whereas LPS-induced cell signaling was absent. We conclude from these studies that bLF induces limited and defined macrophage activation and cell signaling events via TLR4-dependent and -independent mechanisms. bLF-induced CD40 expression was TLR4-dependent whereas bLF-induced IL-6 secretion was TLR4-independent, indicating potentially separate pathways for bLF mediated macrophage activation events in innate immunity.

Anti-lactoferrin antibodies and other types of ANCA in ulcerative colitis, primary sclerosing cholangitis, and Crohn's disease

Fifty two serum samples from patients with Crohn's disease, 24 from patients with ulcerative colitis, and 12 from patients with primary sclerosing cholangitis were analysed for the presence of anti-neutrophil cytoplasm antibodies (ANCA) of IgG and IgA class by means of enzyme linked immunosorbent assays using lactoferrin, myeloperoxidase, and antigen extracted from azurophil granules, 'alpha antigen' (that is, an antigen preparation containing proteinase 3) as substrates. A high frequency of positive tests for IgG anti-lactoferrin antibodies was found in sera from patients with ulcerative colitis (50%) and primary sclerosing cholangitis (50%). In Crohn's disease only 4 of 52 (8%) sera had anti-lactoferrin antibodies--in all four instances the sera belonged to patients with disease involving the colon. All patients with sclerosing cholangitis and positive tests for anti-lactoferrin had ulcerative colitis. Low levels of IgG antibodies against myeloperoxidase or alpha antigen were also found occasionally in sera from patients with ulcerative colitis and primary sclerosing cholangitis. IgA antibodies directed against lactoferrin and alpha antigen (but not myeloperoxidase) were seen in all three conditions.