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Bactericidal/permeability-increasing protein (BPI) plays a major role in innate immunity through the ability of the N-terminal domain (NTD) to bind LPS, mediate cytotoxicity, and block LPS-induced inflammation. The C-terminal domain mediates phagocytosis of bacteria bound to the NTD. These two domains are linked by a surface-exposed loop at amino acids 231–249 for human BPI, known as the “hinge region.” Autoantibodies to human BPI are prevalent in many chronic lung diseases; their presence is strongly correlated with Pseudomonas aeruginosa and with worse lung function in patients with cystic fibrosis and bronchiectasis. Although prior literature has reported BPI neutralization effect with autoantibodies targeting either NTD or C-terminal domain, the functionality of BPI Ab to the hinge region has never been investigated. Here, we report that Ab responses to the BPI hinge region mediate a remarkably selective potentiation of BPI-dependent phagocytosis of P. aeruginosa with both human and murine neutrophils in vitro and in vivo. These findings indicate that autoantibodies to the BPI hinge region might enhance bacterial clearance.

Introduction. Analysis for TORCH infections is ordered to simultaneously detect several common infections: Toxoplasmosis, Other infections (syphilis, hepatitis B, chickenpox, Epstein-Barr virus, parvovirus and some others), Rubella, Cytomegalovirus and Herpes simplex virus. Contracting a TORCH infection in pregnancy triggers the synthesis of immune factors including antimicrobial peptides (AMPs).Aim: to determine the levels of AMPs – lactoferrin, defensin, endotoxin, BPI (bactericidal/permeability-increasing protein) and hepcidin – in the blood serum of pregnant women with TORCH infections.Materials and methods. The main group included 40 pregnant women with TORCH infections; in 33 of those, pregnancy continued until full-term delivery, and 7 women had miscarriages at the end of the first trimester. The comparison group consisted of 29 pregnant women free of TORCH infections. Blood for AMP measurement was taken in all pregnant women in the first trimester and in women with an ongoing pregnancy also in the III trimester. The control group consisted of 19 healthy non-pregnant women. Serum AMP was determined by enzyme-linked immunosorbent assay (ELISA).Results. In pregnant women with TORCH infections, there was an increase in the serum levels of lactoferrin, defensin, hepcidin, BPI, and endotoxin; the increase was most pronounced in the first trimester of pregnancy. The decrease in AMP levels observed in the III trimester could be due to the antiviral treatment given to the patients in order to prevent the immunological rejection of the embryo and maintain the normal course of pregnancy.Conclusion. The increased level of AMPs reflects the enhanced activity of the immune system and represents one of the pathogenetic links of spontaneous abortion.

Background: There have been varying reports on the prevalence of antineutrophil cytoplasmic antibodies with bactericidal/permeability-increasing protein (BPI-ANCA) specificity in cystic fibrosis (CF) patients. These autoantibodies are believed to develop in response to infection and colonization, especially with Pseudomonas aeruginosa. The aim of this review was to estimate the overall prevalence of BPI-ANCA in CF patients. Methods: We searched PubMed, Scopus, and Embase databases for studies reporting the prevalence of BPI-ANCA in CF patients. We also searched the Journal of Cystic Fibrosis and our institution's library for relevant studies on BPI-ANCA. We calculated the proportion with a 95% confidence interval (CI) to assess the prevalence of BPI-ANCA in the individual studies and then pooled the results using a random effects model. Publication bias was assessed using graphical and statistical methods. Finally, we assessed statistical heterogeneity using the I(2) test. Results: Our search yielded 12 eligible studies published between 1996 and 2015. The prevalence of BPI-ANCA in patients with CF varied from 17.9% to 83% with a pooled prevalence of 49.45% (95% CI 35.53–63.42). No evidence of bias was found. However, there was evidence of statistically significant variation in the prevalence estimate due to heterogeneity (I(2) = 93.4%, P

Chronic Pseudomonas aeruginosa infection mysteriously occurs in the airways of patients with cystic fibrosis (CF), bronchiectasis (BE), and chronic obstructive pulmonary disease (COPD) in the absence of neutrophil dysfunction or neutropenia and is strongly associated with autoimmunity to bactericidal permeability-increasing protein (BPI). Here, we define a critical role for BPI in in vivo immunity against P. aeruginosa. Wild type and BPI-deficient (Bpi-/-) mice were infected with P. aeruginosa, and bacterial clearance, cell infiltrates, cytokine production, and in vivo phagocytosis were quantified. Bpi-/- mice exhibited a decreased ability to clear P. aeruginosa in vivo in concert with increased neutrophil counts and cytokine release. Bpi-/- neutrophils displayed decreased phagocytosis that was corrected by exogenous BPI in vitro. Exogenous BPI also enhanced clearance of P. aeruginosa in Bpi-/- mice in vivo by increasing P. aeruginosa uptake by neutrophils in a CD18-dependent manner. These data indicate that BPI plays an essential role in innate immunity against P. aeruginosa through its opsonic activity and suggest that perturbations in BPI levels or function may contribute to chronic lung infection with P. aeruginosa.

Bactericidal permeability-increasing protein (BPI) and lipopolysaccharide (LPS) binding proteins (LBP) both play important roles in innate immunity against bacterial infection. Herein, we identified a novel full-length cDNA sequence of BPI/LBP from Trachidermus fasciatus (designated as TfBPI/LBP). The full-length cDNA sequence of TfBPI/LBP was 1594bp, which contains an open reading frame (ORF) of 1422bp encoding a secreted protein with 473 amino acid residues. Similar to BPI/LBPs from other teleost and mammals, the peptide of TfBPI/LBP contains an N-terminal BPI/LBP/CETP domain with an LPS-binding motif and a C-terminal BPI/LBP/CETP domain BPI2. Multiple alignments and phylogenetic analysis supported that TfBPI/LBP was a new member of the vertebrate BPI/LBP family. TfBPI/LBP gene was ubiquitously expressed in all detected tissues, with the most abundant in the liver, and could be significantly induced in the skin, blood, liver, spleen post LPS challenge. The recombinant N-terminal domain of TfBPI/LBP (designated as rTfBPI/LBPN) was successfully expressed in Escherichia coli. Sugar binding assay showed that rTfBPI/LBPN could bind to LPS, peptidoglycan (PGN), and lipoteichoic acid (LTA), with the highest affinity to LPS. The results of bacteria binding and agglutinating assay revealed that rTfBPI/LBPN could bind and agglutinate to all of the 9 kinds of bacteria we used. Moreover, membrane integrity analysis indicated that rTfBPI/LBPN could increase the membrane permeability of bacteria. These results suggested that BPI/LBP may play crucial roles in host defense against microorganisms, possibly through non-selective bacterial recognition and induction of membrane penetration.

ObjectiveThe objective of this study was to understand the role of bactericidal permeability increasing protein (BPI) in the pathogenesis of experimental murine colitis.MethodsWe used the Cre-LoxP system to generate BPI knockout (BPI KO) mice. Acute colitis was induced in BPI KO mice and wild-type (WT) mice by subjecting the mice to 5% dextran sulfate sodium (DSS). Mice were observed for symptoms of experimental colitis. The survival of BPI KO mice to infection with Acinetobacter baumannii, a gram-negative bacterium, was also assessed.ResultsSouthern blot, RT-PCR, and western blot results showed that the 2nd and 3rd exons of the murine Bpi gene were knocked out systemically, confirming successful construction of the BPI KO mouse. BPI KO mice subjected to DSS showed increased symptoms of experimental colitis, increased colonic mucosal damage, increased epithelial permeability, elevated levels of serum LPS, and a disrupted fecal microbiome as compared with WT mice. Furthermore, BPI KO mice challenged intraperitoneally with A. baumannii died sooner than WT mice, and the total number of bacteria in the abdominal cavity, spleen, and liver was increased in BPI KO mice as compared to WT mice.ConclusionsWe successfully generated BPI KO mice. The BPI KO mice developed worse colitis than WT mice by increased colitis symptoms and colonic mucosal damage, elevated levels of serum LPS, and a disrupted microbiome. BPI could be a potential target for treatment of ulcerative colitis in humans.

Antibody autoreactivity against bactericidal/permeability-increasing protein (BPI) is strongly associated with Pseudomonas aeruginosa infection in cystic fibrosis (CF), non-CF bronchiectasis (BE), and chronic obstructive pulmonary disease (COPD). We examined the pathogen-specific nature of this autoreactivity by examining antibodies to BPI in bacteremia patients. Antibodies to BPI and bacterial antigens were measured in sera by ELISA from five patient cohorts (n = 214). Antibody avidity was investigated. Bacteremic patient sera (n = 32) exhibited IgG antibody autoreactivity against BPI in 64.7% and 46.7% of patients with positive blood cultures for P. aeruginosa and Escherichia coli, respectively. Autoantibody titers correlated with IgG responses to bacterial extracts and lipopolysaccharide (LPS). A prospective cohort of bacteremic patient sera exhibited anti-BPI IgG responses in 23/154 (14.9%) patients with autoreactivity present at the time of positive blood cultures in patients with Gram-negative and Gram-positive bacteria, including 8/60 (13.3%) patients with Staphylococcus aureus. Chronic tissue infection with S. aureus was associated with BPI antibody autoreactivity in 2/15 patients (13.3%). Previously, we demonstrated that BPI autoreactivity in CF patient sera exhibits high avidity. Here, a similar pattern was seen in BE patient sera. In contrast, sera from patients with bacteremia exhibited low avidity. These data indicate that low-avidity IgG responses to BPI can arise acutely in response to bacteremia and that this association is not limited to P. aeruginosa. This is to be contrasted with chronic respiratory infection with P. aeruginosa, suggesting that either the chronicity or the site of infection selects for the generation of high-avidity responses, with biologic consequences for airway immunity.

In people with cystic fibrosis (PWCF), inflammation with concurrent infection occurs from a young age and significantly influences lung disease progression. Studies indicate that neutrophils are important effector cells in the pathogenesis of CF and in the development of anti-neutrophil cytoplasmic autoantibodies (ANCA). ANCA specific for bactericidal permeability increasing protein (BPI-ANCA) are detected in people with CF, and correlate with infection with Pseudomonas aeruginosa. The aim of this study was to determine the signaling mechanism leading to increased BPI release by CF neutrophils, while identifying IgG class BPI-ANCA in CF airways samples as the cause for impaired antimicrobial activity of BPI against P. aeruginosa. Plasma and/or bronchoalveolar lavage fluid (BAL) was collected from PWCF (n = 40), CF receiving ivacaftor therapy (n = 10), non-CF patient cohorts (n = 7) and healthy controls (n = 38). Plasma and BAL BPI and BPI-ANCA were measured by ELISA and GTP-bound Rac2 detected using an in vitro assay. The antibacterial effect of all treatments tested was determined by colony forming units enumeration. Levels of BPI are significantly increased in plasma (p = 0.007) and BALF (p < 0.0001) of PWCF. The signaling mechanism leading to increased degranulation and exocytosis of BPI by CF neutrophils (p = 0.02) involved enhancement of Rac2 GTP-loading (p = 0.03). The full-length BPI protein was detectable in all CF BAL samples and patients displayed ANCA with BPI specificity. IgG class autoantibodies were purified from CF BAL complexed to BPI (n=5), with IgG autoantibody cross-linking of antigen preventing BPI induced P. aeruginosa killing (p < 0.0001). Results indicate that the immune-mediated diminished antimicrobial defense, attributed to anti-BPI-IgG, necessitates the formation of a drug/immune complex intermediate that can maintain cytotoxic effects of BPI towards Gram-negative pathogens, with the potential to transform the current treatment of CF airways disease.

This document follows up on a 2017 revised international consensus on anti-neutrophil cytoplasm antibodies (ANCA) testing in granulomatosis with polyangiitis and microscopic polyangiitis and focuses on the clinical and diagnostic value of ANCA detection in patients with connective tissue diseases, idiopathic interstitial pneumonia, autoimmune liver diseases, inflammatory bowel diseases, anti-glomerular basement membrane (GBM) disease, infections, malignancy, and during drug treatment. Current evidence suggests that in certain settings beyond systemic vasculitis, ANCA may have clinical, pathogenic and/or diagnostic relevance. Antigen-specific ANCA targeting proteinase-3 and myeloperoxidase should be tested by solid phase immunoassays in any patient with clinical features suggesting ANCA-associated vasculitis and in all patients with anti-GBM disease, idiopathic interstitial pneumonia, and infective endocarditis associated with nephritis, whereas in patients with other aforementioned disorders routine ANCA testing is not recommended. Among patients with autoimmune liver diseases or inflammatory bowel diseases, ANCA testing may be justified in patients with suspected autoimmune hepatitis type 1 who do not have conventional autoantibodies or in case of diagnostic uncertainty to discriminate ulcerative colitis from Crohn's disease. In these cases, ANCA should be tested by indirect immunofluorescence as the target antigens are not yet well characterized. Many questions concerning the optimal use of ANCA testing in patients without ANCA-associated vasculitis remain to be answered.

The interaction between host immune response and the associated microbiota has recently become a fundamental aspect of vertebrate and invertebrate animal health. This interaction allows the specific association of microbial communities, which participate in a variety of processes in the host including protection against pathogens. Marine aquatic invertebrates such as scallops are also colonized by diverse microbial communities. Scallops remain healthy most of the time, and in general, only a few species are fatally affected on adult stage by viral and bacterial pathogens. Still, high mortalities at larval stages are widely reported and they are associated with pathogenic Vibrio. Thus, to give new insights into the interaction between scallop immune response and its associated microbiota, we assessed the involvement of two host antimicrobial effectors in shaping the abundances of bacterial communities present in the scallop Argopecten purpuratus hemolymph. To do this, we first characterized the microbiota composition in the hemolymph from non-stimulated scallops, finding both common and distinct bacterial communities dominated by the Proteobacteria, Spirochaetes and Bacteroidetes phyla. Next, we identified dynamic shifts of certain bacterial communities in the scallop hemolymph along immune response progression, where host antimicrobial effectors were expressed at basal level and early induced after a bacterial challenge. Finally, the transcript silencing of the antimicrobial peptide big defensin ApBD1 and the bactericidal/permeability-increasing protein ApLBP/BPI1 by RNA interference led to an imbalance of target bacterial groups from scallop hemolymph. Specifically, a significant increase in the class Gammaproteobacteria and the proliferation of Vibrio spp. was observed in scallops silenced for each antimicrobial. Overall, our results strongly suggest that scallop antimicrobial peptides and proteins are implicated in the maintenance of microbial homeostasis and are key molecules in orchestrating host-microbiota interactions. This new evidence depicts the delicate balance that exists between the immune response of A. purpuratus and the hemolymph microbiota. info:eu-repo/semantics/publishedVersion

The bactericidal permeability-increasing protein (BPI) is a multifunctional cationic protein produced by neutrophils with antibacterial, antitumor, and LPS-neutralizing properties. In teleost, a number of BPIs have been reported, but their functions are very limited. In this study, an N-terminal peptide, BO18 (with 18 amino acids), derived from rock bream (Oplegnathus fasciatus) BPI, was synthesized and investigated for its antibacterial spectrum, action mechanism, immunoregulatory property as well as the inhibition effects on bacterial invasion and human colon cancer cells growth. The results showed that BO18 was active against Gram-positive bacteria Bscillus subiilis, Micrococcus luteus, and Staphylococcus aureus, as well as Gram-negative bacteria Vibrio alginolyticus, Vibrio litoralis, Vibrio parahaemolyticus and Vibrio vulnificus. BO18 treatment facilitated the bactericidal process of erythromycin and rifampicin by enhancing the permeability of the outer membrane. During its interaction with V. alginolyticus, BO18 exerted its antibacterial activity by destroying cell membrane integrity, penetrating into the cytoplasm and binding to genomic DNA and total RNA. In vitro analysis indicated BO18 could enhance the respiratory burst ability and regulate the expression of immune related genes of macrophages. In vivo detection showed the administration of fish with BO18 before bacterial infection significantly reduced pathogen dissemination and replication in tissues. In addition, BO18 exerted a cytotoxic effect on the growth of human colon cancer cells HT-29. Together, these results add new insights into the function of teleost BPIs, and support that BO18 is a novel and broad-spectrum antibacterial peptide with potential to apply in fighting pathogenic infection in aquaculture.

The gut barrier plays a crucial role by spatially compartmentalizing bacteria to the lumen through the production of secreted mucus and is fortified by the production of secretory IgA (sIgA) and antimicrobial peptides and proteins. With the exception of sIgA, expression of these protective barrier factors is largely controlled by innate immune recognition of microbial molecular ligands. Several specialized adaptations and checkpoints are operating in the mucosa to scale the immune response according to the threat and prevent overreaction to the trillions of symbionts inhabiting the human intestine. A healthy microbiota plays a key role influencing epithelial barrier functions through the production of short-chain fatty acids (SCFAs) and interactions with innate pattern recognition receptors in the mucosa, driving the steady-state expression of mucus and antimicrobial factors. However, perturbation of gut barrier homeostasis can lead to increased inflammatory signaling, increased epithelial permeability, and dysbiosis of the microbiota, which are recognized to play a role in the pathophysiology of a variety of gastrointestinal disorders. Additionally, gut-brain signaling may be affected by prolonged mucosal immune activation, leading to increased afferent sensory signaling and abdominal symptoms. In turn, neuronal mechanisms can affect the intestinal barrier partly by activation of the hypothalamus-pituitary-adrenal axis and both mast cell-dependent and mast cell-independent mechanisms. The modulation of gut barrier function through nutritional interventions, including strategies to manipulate the microbiota, is considered a relevant target for novel therapeutic and preventive treatments against a range of diseases. Several biomarkers have been used to measure gut permeability and loss of barrier integrity in intestinal diseases, but there remains a need to explore their use in assessing the effect of nutritional factors on gut barrier function. Future studies should aim to establish normal ranges of available biomarkers and their predictive value for gut health in human cohorts.

Introduction The inflammatory marker patterns of community-acquired Pneumonia (CAP) induced by different microorganisms in adult patients remained unclear. Objectives We aim to explore the inflammatory marker patterns of adult CAP patients induced by different pathogens. Methods Adult CAP patients with definite etiologies were enrolled from September 2010 to June 2012. They were divided into three groups according to the causative pathogens: typical bacteria, Mycoplasma pneumoniae (MP), and viruses. Twenty-seven cytokines and bactericidal/permeability-increasing protein (BPI) levels of serum collected within 7 days onset in these groups were compared. Results One hundred twenty-four cases were enrolled for serum detection and analysis, including 10 typical bacterial pneumonia patients, 56 cases with MP pneumonia and 58 with viral pneumonia. Three kinds (PDGF-BB, IP-10, RANTES) of 27 cytokines and BPI levels were significantly elevated in patients with acute pneumonia than healthy controls. Distinct inflammatory marker patterns were released by different pathogens: typical bacterial pneumonia patients had highest levels of BPI, IL-6, IL-8, IL-1rα; while patients caused by MP presented higher levels of PDGF-BB, IL-17A, G-CSF than those caused by viruses. Rhinovirus owned a higher inflammatory response level than the other viruses. The area under the curve (AUC) of PDGF-BB to differentiate MP and virus infection was biggest, which was 0.708. Conclusion Distinct inflammatory marker patterns were released by different pathogens during acute pneumonia. Significantly increased level of PDGF-BB was observed in acute pneumonia for the first time. It showed a better ability to differentiate MP and virus infection.

Bactericidal permeability-increasing protein (BPI)/lipopolysaccharide (LPS) binding proteins (LBPs) are well-known proteins that play an indispensable role in host antimicrobial defense. Herein, we report a homolog of BPI/LBP from black rockfish (Sebastes schlegelii) (designated as RfBPI/LBP) and characterize its structural and functional features at the molecular level. We identified the putative complete open reading frame (1422 bp) of RfLBP that encodes a 474 amino acid protein with a predicted molecular mass of ∼51.5 kDa. The primary protein sequence of RfBPI/LBP contains domain features of BPI/LBP family proteins and shares significant sequence consistency with its homologs. Our phylogenetic analysis clearly demonstrated the vertebrate ancestral origin of RfBPI/LBP, further reinforcing its evolutionary relationship with teleostean homologs. Recombinant RfBPI/LBP demonstrated in vitro LPS-binding activity and antibacterial activity against Escherichia coli, but not against Streptococcus iniae. Moreover, RfBPI/LBP exhibited temporal transcriptional activation against pathogens and pathogen-associated molecular patterns. Collectively, our findings suggest that RfBPI/LBP plays an essential role in host antimicrobial defense, plausibly through selective eradication of invading bacteria.

Anti-neutrophil cytoplasmic antibodies specific for bactericidal/permeability-increasing protein (BPI-ANCA) are frequently present in cystic fibrosis patients. These autoantibodies are believed to develop in response to infection and colonization by Pseudomonas aeruginosa. Development of BPI-ANCA has been shown to correlate with the severity of lung infection and poor prognosis in cystic fibrosis patients.

Adequate perception of immunologically important pathogen-associated molecular patterns like lipopolysaccharide and bacterial lipoproteins is essential for efficient innate and adaptive immune responses. In the context of Gram-negative infection, bactericidal/permeability-increasing protein (BPI) neutralizes endotoxic activity of lipopolysaccharides, and thus prohibits hyperactivation. So far, no immunological function of BPI has been described in Gram-positive infections. Here, we show a significant elevation of BPI in Gram-positive meningitis and, surprisingly, a positive correlation between BPI and pro-inflammatory markers like TNF alpha. To clarify the underlying mechanisms, we identify BPI ligands of Gram-positive origin, specifically bacterial lipopeptides and lipoteichoic acids, and determine essential structural motifs for this interaction. Importantly, the interaction of BPI with these newly defined ligands significantly enhances the immune response in peripheral blood mononuclear cells (PBMCs) mediated by Gram-positive bacteria, and thereby ensures their sensitive perception. In conclusion, we define BPI as an immune enhancing pattern recognition molecule in Gram-positive infections.

Objectives We investigated the association between autoantibodies against non-myeloperoxidase (MPO) neutrophil granule antigens and activity of Behcet's disease (BD). Methods We consecutively enrolled 51 BD patients. We assessed clinical data and BD activity using patients' index scores from the Behcet's Disease Current Activity Form and we performed tests for antibodies against proteinase 3 (PR3), MPO, bactericidal permeability increasing protein (BPI), cathepsin G, elastase, lactoferrin and lysozyme. Results The median patient index score was 2.0, and 56.9% of patients had active BD. In multivariate analysis of variables with significant correlations, only anti-lysozyme showed a significant correlation with BD activity (P = 0.002). In multivariate logistic regression analyses of variables, when patients were classified into groups according to the optimal cutoff levels of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and anti-lysozyme (ESR > 42.5 mm/h, CRP > 1.35 mg/L and anti-lysozyme > 2.95 IU/mL), the variable with independent predictive value was anti-lysozyme (odds ratio 8.384, P = 0.015). Conclusion Anti-lysozyme was significantly correlated with disease activity score and it was the only independent value to predict active disease in patients with BD. Furthermore, patients having anti-lysozyme levels ≥ 2.95 IU/mL had a significantly higher risk of having active BD than those who did not.

Folate cycle gene polymorphisms and the levels of endogenous antimicrobial peptides and proteins in the blood and coprofiltrates were studied in 45 children aged 3 to 12 months with cow’s milk protein allergy. The polymorphic variants of the MTHFR, MTRR, and MTR genes were shown to be considered as a risk factor for the development of allergy. There was a significant increase in the levels of zonulin, β-defensin 2, transthyretin, and eosinophil cationic protein in the coprofiltrates and in those of eotaxin, fatty acidbinding proteins, and membrane permeability-increasing protein in the serum (p

Bactericidal permeability-increasing protein (BPI) and lipopolysaccharide-binding protein (LBP) belong to the lipid transfer protein/lipopolysaccharide-binding protein family and play a critical role in the innate immune response to Gram-negative bacteria. In the present study, a novel BPI/LBP from blunt snout bream, Megalobrama amblycephala (maBPI/LBP) was isolated by RACE techniques. The open reading frame (ORF) of maBPI/LBP gene encoded a polypeptide of 474 amino acids with a putative 18-aa hydrophobic signal peptide. Structurally, the maBPI/LBP showed highly similar to those of BPI/LBPs from invertebrate and teleost, LBPs and BPIs from mammal, which contained an N-terminal BPI/LBP/CETP domain BPI1 with a LPS-binding domain, a C-terminal BPI/LBP/CETP domain BPI2, and proline-rich domain. The homologous identities of deduced amino acid sequences displayed that the maBPI/LBP possessed significant similarity (96.61% and 90.07%) with those of grass carp and common carp, respectively. The recombinant protein of maBPI/LBP showed effectively kill Gram-negative bacteria. The maBPI/LBP gene was expressed in a wide range of normal tested tissues, with the highest expression levels in the kidney. The experiments revealed that the mRNA expression of maBPI/LBP in spleen considerably up-regulated from 2 h to 8 h post LPS stimulation, and peaked rapidly at 2 h (7.40-fold, P < 0.05), which confirmed that maBPI/LBP was the absolute sensitive to LPS stimulation. Furthermore, the level of maBPI/LBP mRNA expression reached the maximum for a second time at 24 h after LPS stimulation. These results suggested that maBPI/LBP was a constitutive and inducible acute-phase protein contributing to the host immune defense against pathogenic bacterial infection in M. amblycephala. This study will further our understanding of the function of BPI/LBP and the molecular mechanism of innate immunity in teleost.

Any vaginal product that alters the mucosal environment and impairs the immune barrier increases the risk of sexually transmitted infections, especially HIV infection, which thrives on mucosal damage and inflammation. The FDA-recommended rabbit vaginal irritation (RVI) model serves as a first line selection tool for vaginal products; however, for decades it has been limited to histopathology scoring, insufficient to select safe anti-HIV microbicides. In this study we incorporate to the RVI model a novel quantitative nuclease protection assay (qNPA) to quantify mRNA levels of 25 genes representing leukocyte differentiation markers, toll-like receptors (TLR), cytokines, chemokines, epithelial repair, microbicidal and vascular markers, by designing two multiplex arrays. Tissue sections were obtained from 36 rabbits (6 per treatment arm) after 14 daily applications of a placebo gel, saline, 4% nonoxynol-9 (N-9), and three combinations of the anti-HIV microbicides tenofovir (TFV) and UC781 in escalating concentrations (highest: 10% TFV+2.5%UC781). Results showed that increased expression levels of toll-like receptor (TLR)-4, interleukin (IL)-1β, CXCL8, epithelial membrane protein (EMP)-1 (P

Bactericidal/permeability-increasing protein fold–containing family member A1 (BPIFA1), formerly known as SPLUNC1, is one of the most abundant proteins in respiratory secretions and has been identified with increasing frequency in studies of pulmonary disease. Its expression is largely restricted to the respiratory tract, being highly concentrated in the upper airways and proximal trachea. BPIFA1 is highly responsive to airborne pathogens, allergens, and irritants. BPIFA1 actively participates in host protection through antimicrobial, surfactant, airway surface liquid regulation, and immunomodulatory properties. Its expression is modulated in multiple lung diseases, including cystic fibrosis, chronic obstructive pulmonary disease, respiratory malignancies, and idiopathic pulmonary fibrosis. However, the role of BPIFA1 in pulmonary pathogenesis remains to be elucidated. This review highlights the versatile properties of BPIFA1 in antimicrobial protection and its roles as a sensor of environmental exposure and regulator of immune cell function. A greater understanding of the contribution of BPIFA1 to disease pathogenesis and activity may clarify if BPIFA1 is a biomarker and potential drug target in pulmonary disease.

Background Bactericidal/permeability-increasing protein (BPI) is a cationic protein mainly produced by polymorphonuclear cells (PMN) which exerts an antimicrobial activity by damaging bacterial membranes and interacts with specific cell surface receptors, such as toll-like receptors (TLRs). BPI has been detected in synovial fluid of patients with different arthritis, including crystal-induced arthritis. Objectives To evaluate the effects and mechanisms of action of BPI in in vitro and in vivo models of crystal-induced inflammation. Methods The human monocytic cell line THP-1 was primed for 3 h with phorbole myristate acetate (300 ng/ml), reincubated overnight, and treated with sterile synthetic monosodium urate (MSU) (0.5 mg/ml) or calcium pyrophosphate (CPP) (0.1 mg/ml) crystals for 24 h in presence or absence of BPI (5 μ g/ml). In some experiments, cells or crystals were pretreated with BPI for 2 h before stimulation. BPI inhibition experiments were carried out with antibody against TLR2 or TLR4. Cell supernatants were tested by ELISA for interleukin (IL)-1β and IL-8 production. Chemotactic effect of culture supernatants was evaluated in chemotaxis chamber by the migration of freshly isolated peripheral blood PMN. As regard the study in vivo, air pouches were raised on the backs of CD1 mice (n=7 per condition). 2 mg of MSU crystals in 1 ml of PBS were injected into the pouch in the presence or absence of 0.1 mg of BPI for 3 h. Controls received 1 ml of PBS. After the sacrifice, pouch fluids were recovered by washing with 2 ml of PBS. Leukocyte count in lavage fluids was obtained using a hemocytometer and the percentage of PMN was determined by May-Grunwald-Giemsa staining. IL-1β, chemokine (C-X-C motif) ligand 1 (CXCL1) and IL-6 levels were measured in exudates by ELISA. Results Exposure of THP-1 cells to different types of crystals increased the production of IL-1β (MSU: 406.62±12.00 pg/ml; CPP: 357.07±25.17 pg/ml) and IL-8 (MSU: 3798.56±24.64 pg/ml; CPP: 3427.74±22.33 pg/ml). The release of both cytokines induced by crystals was significantly diminished in the presence of BPI (76% IL-1β, 58% IL-8), and tended to be more pronounced when cells, but not crystals, were pretreated with the protein (90% IL-1β, 65% IL-8). The presence of antibody anti-TLR2 or anti-TLR4 did not affect the BPI inhibitory effect. Supernatants of crystal-stimulated cells increased the migration of PMN cells which was reduced in the presence of BPI. The injection of MSU crystals into the subcutaneous pouches of mice induced leukocyte infiltration (10.2±3.39 x 105 cells/ml) comprising 68.6±8.75% of PMN. IL-1β (32.33±6.35 pg/ml), CXCL1 (467.07±27.47 pg/ml) and IL-6 (624.61±29.41 pg/ml) were measured in lavage fluids. The co-injection of MSU crystals and BPI inhibited leukocyte influx by 60% and PMN infiltration by 87% and, in turn, the levels of all assessed cytokines were reduced (81% IL-1β, 70% CXCL1, 35% IL-6). Conclusions This study shows that BPI reduces the crystal-induced inflammatory process in vitro and in vivo by inhibiting pro-inflammatory cytokine release and PMN recruitment. The mechanism of action of BPI may include the direct interaction with activated cells in a TLR-independent manner. Disclosure of Interest None declared

Bacterial translocation (BT) is an important mechanism in the development of infection in liver cirrhosis. The migration and colonization of bacteria and/or bacterial products from the bowel to mesenteric lymph nodes is a controlled process in healthy persons. Increased intestinal permeability, bacterial overgrowth and defect of gut-associated lymphatic tissue promote impaired BT in cirrhotics. We reviewed the reports on markers used for the evaluation of BT published between 1987 and 2016. We focused on the clinical consequences of BT in cirrhosis, as indicated by the values of the BT markers. Patients with cirrhosis are reported to have elevated levels of surrogate markers associated with BT compared with controls. The most widely used BT parameters are C-reactive protein, procalcitonin, bacterial DNA, endotoxin or lipopolysaccharide, lipopolysaccharide binding protein, calprotectin, and bactericidal/permeability increasing protein. High levels of these factors in serum and/or ascitic fluid in humans may be associated with advanced liver disease, hemodynamic instability, high levels of proinflammatory cytokines, susceptibility to the development of severe or recurrent infections, acute-on-chronic liver failure, hepatic encephalopathy, hepatorenal syndrome and poor prognosis during follow up. In conclusion, high levels of BT markers are associated with a high inflammatory response, increased complications of liver cirrhosis and occasionally high fatality rates. Keywords C-reactive protein, bacterial DNA, lipopolysaccharide binding protein, calprotectin, bactericidal/permeability increasing protein, soluble form of receptor for lipopolysaccharide Ann Gastroenterol 2017; 30 (5): 486-497

Background Bactericidal/permeability increasing protein fold containing family A (BPIFA) 1, is a secreted protein of the upper airways that shares structural homology with BPI and exhibits comparable antimicrobial capacities. We hypothesized that CF patients have circulating IgG or IgA anti-BPIFA1 autoantibodies, similarly as reported for BPI autoantibodies. Methods We analyzed pre- and post-transplantation sera from 67 endstage lung disease patients who underwent lung transplantation (LTx) because of COPD (n=27), CF (n=25), and ILD (n=15). Results Anti-BPIFA1 (48%) and anti-BPI (92%) were elevated in CF patients compared to healthy controls, with anti-BPIFA1 IgG isotype being most prevalent, whereas anti-BPI is of the IgA isotype. Levels of anti-BPI autoantibodies significantly declined post-LTx, whereas anti-BPIFA1 did not. No relation was found between autoantibodies against BPIFA1 and BPI. Conclusion Our results indicate that BPIFA1 is a novel target for autoantibodies in CF. The function of these autoantibodies needed to be investigated in future studies.

Bactericidal/permeability increasing protein (BPI) gene polymorphisms have been extensively investigated in terms of their associations with inflammatory bowel disease (IBD), with contradictory results. The aim of this meta-analysis was to evaluate associations between BPI gene polymorphisms and the risk of IBD, Crohn’s disease (CD), and ulcerative colitis (UC). Eligible studies from PubMed, Embase, and Cochrane library databases were identified. Ten studies (five CD and five UC) published in five papers were included in this meta-analysis. G645A polymorphism was associated with a decreased risk of UC in allele model, dominant model, and homozygous model. Our data suggested that BPI G645A polymorphism was associated with a decreased risk of UC; the BPI G645A polymorphism was not associated with the risk of CD.

Item does not contain fulltext Lipopolysaccharide (LPS) binding protein (LBP) is an acute-phase protein that initiates an immune response after recognition of bacterial LPS. Here, we report the crystal structure of murine LBP at 2.9 A resolution. Several structural differences were observed between LBP and the related bactericidal/permeability-increasing protein (BPI), and the LBP C-terminal domain contained a negatively charged groove and a hydrophobic "phenylalanine core." A frequent human LBP SNP (allelic frequency 0.08) affected this region, potentially generating a proteinase cleavage site. The mutant protein had a reduced binding capacity for LPS and lipopeptides. SNP carriers displayed a reduced cytokine response after in vivo LPS exposure and lower cytokine concentrations in pneumonia. In a retrospective trial, the LBP SNP was associated with increased mortality rates during sepsis and pneumonia. Thus, the structural integrity of LBP may be crucial for fighting infections efficiently, and future patient stratification might help to develop better therapeutic strategies.

Bactericidal permeability-increasing protein (BPI) and lipopolysaccharide-binding protein (LBP) are the numbers of the lipid transfer protein/lipopolysaccharide-binding protein family and play crucial roles in the innate immune response to Gram-negative bacteria. A novel Sb-BPI/LBP1 from ark shell Scapharca broughtonii was isolated by expressed sequence tag (EST) and RACE techniques. The Sb-BPI/LBP1 cDNA encoded a polypeptide of 484 amino acids with a putative signal peptide of 21 amino acid residues and a mature protein of 463 amino acids. The deduced amino acid sequence of Sb-BPI/LBP1 contained an N-terminal BPI/LBP/CETP domain BPI1 with three functional regions that display LPS-binding activity, and a C-terminal BPI/LBP/CETP domain BPI2. In structure and sequence, Sb-BPI/LBP1 showed highly similar to those of the BPI/LBPs from invertebrate and non-mammalian vertebrate, the LBPs and BPIs from mammal. By quantitative real-time RT-PCR, Sb-BPI/LBP1 transcripts could be detected in all normal tested tissues, including hepatopancreas, adductor muscle, mantle margin, heart, gonad, gill and hemocytes, and was universally up-regulatable at 24 h post LPS challenge. The mRNA expression of Sb-BPI/LBP1 in hemocytes was the most sensitive to LPS challenge, significantly up-regulated at 12 h post LPS challenge and peaked at 24 h (16.76-fold, P < 0.05). These results suggested that Sb-BPI/LBP1 was a constitutive and inducible acute-phase protein contributing to the host immune defense against Gram-negative bacterial infection in ark shell S. broughtonii.

Myeloperoxidase- and proteinase 3-anti-neutrophil cytoplasmic antibodies (ANCAs) are often negative in cases in which systemic vasculitis is highly suspected. We herein present a case of bactericidal/permeability increasing protein (BPI)-ANCA-positive systemic vasculitis. This case highlights the possible role of BPI-ANCA in the pathogenesis of systemic vasculitis as well as the possible use of BPI as a diagnostic tool. The accumulation of further case-based reports is expected to shed some light on the pathogesis of systemic vasculitis.

Bactericidal permeability increasing protein (BPI), a 55–60 kDa protein, first reported in 1975, has gone a long way as a protein with multifunctional roles. Its classical role in neutralizing endotoxin (LPS) raised high hopes among septic shock patients. Today, BPI is not just a LPS-neutralizing protein, but a protein with diverse functions. These functions can be as varied as inhibition of endothelial cell growth and inhibition of dendritic cell maturation, or as an anti-angiogenic, chemoattractant or opsonization agent. Though the literature available is extremely limited, it is fascinating to look into how BPI is gaining major importance as a signalling molecule. In this review, we briefly summarize the recent research focused on the multiple roles of BPI and its use as a therapeutic.

Macrophages as immune cells prevent the spreading of pathogens by means of active phagocytosis and killing. We report here the presence of an anti-microbial protein, bactericidal/permeability-increasing protein (BPI) in human macrophages, which actively participates in engulfment and killing of Gram-negative pathogens. Our studies revealed increased expression of BPI in human macrophages during bacterial infection and upon stimulation with various PAMPs (Pathogen-associated molecular patterns) viz., LPS, flagellin. Further, during the course of an infection, BPI interacted with Gram- negative bacteria, resulting in enhanced phagocytosis and subsequent control of the bacterial replication. However, it was observed that bacteria which can maintain an active replicating niche (Salmonella Typhimurium) avoid the interaction with BPI during later stages of infection. On the other hand, Salmonella mutants, which cannot maintain a replicating niche, as well as Shigella flexneri, which quit the endosomal vesicle, showed interaction with BPI. These results propose an active role of BPI in Gram-negative bacterial clearance by human macrophages.

Lipopolysaccharide (LPS) is a major trigger of septic shock resulting in multiple organ damage through excessive stimulation of the host's immune cells resulting in the release of cytokines. Previous studies have shown that hesperidin has several beneficial properties against inflammation and oxidative stress.The influence of hesperidin on endotoxemia, endothelial dysfunction, inflammation, and oxidative stress was investigated using a murine model of sepsis.Rats were pretreated for 15 d with three doses (50 mg/kg, 100 mg/kg, and 200 mg/kg) of hesperidin prior to LPS administration. Afterwards, the levels of biomarkers of endotoxemia, endothelial dysfunction, and oxidative stress were assessed. Reverse transcriptase PCR technique was used to assess the expression of hepatic proinflammatory cytokines.Hesperidin pretreatment significantly (p 0.05) reduced circulating endotoxin, as well as the levels of bactericidal permeability increasing protein and procalcitonin, and the associated endothelial dysfunction by reducing the levels of plasma soluble intercellular adhesion molecules 1 and inducible nitric oxide (iNO) synthase. There was also down-regulation of the expression of gene for interleukin 1α, interleukin 1β, interleukin 1 receptor, interleukin 6, and tumor necrosis factor α (TNFα) in the liver of rats treated with LPS as a result of hesperidin pretreatment. Hesperidin also showed anti-oxidative properties through the significant (p 0.05) reduction of NO, hydroperoxides, and thiobarbituric acid reactive substances and increase of glutathione, glutathione reductase, glutathione peroxidase, and glutathione-S-transferase in the organs.Different doses of hesperidin can prevent endotoxemia-induced oxidative stress as well as inflammatory and endothelial perturbation in rats when administered for as few as 15 d before exposure to endotoxin.

Coronary atherosclerosis represents the major cause of death in Western societies. As atherosclerosis typically progresses over years without giving rise to clinical symptoms, biomarkers are urgently needed to identify patients at risk. Over the past decade, evidence has accumulated suggesting cross-talk between the diseased vasculature and cells of the innate immune system. We therefore employed proteomics to search for biomarkers associated with severe atherosclerotic coronary lumen stenosis in circulating leukocytes. In a two-phase approach, we first performed in-depth quantitative profiling of the granulocyte proteome on a small pooled cohort of patients suffering from chronic (sub)total coronary occlusion and matched control patients using stable isotope peptide labeling, two-dimensional LC-MS/MS and data-dependent decision tree fragmentation. Over 3000 proteins were quantified, among which 57 candidate biomarker proteins remained after stringent filtering. The most promising biomarker candidates were subsequently verified in the individual samples of the discovery cohort using label-free, single-run LC-MS/MS analysis, as well as in an independent verification cohort of 25 patients with total coronary occlusion (CTO) and 19 matched controls. Our data reveal bactericidal/permeability-increasing protein (BPI) as a promising biomarker for severe atherosclerotic coronary stenosis, being down-regulated in circulating granulocytes of CTO patients.

We identified two cDNAs designated as RbBPI/LBP-1 and RbBPI/LBP2, respectively, which were identified by expressed sequence tag (EST) analysis of a lipopolysaccharide (LPS)-stimulated rock bream liver cDNA library. The two cDNA displayed 36.9% identity at the translated amino acid level. Despite the low level of identity between the two genes, high conservation was seen in the BPI/LBP/CETP N-terminal, LPS-binding, the proline-rich central and the BPI/LBP/CETP C-terminal domains. The full-length RbBPI/LBP-1 cDNA (1945 bp) contained an open reading frame (ORF) of 1431 bp encoding 476 amino acids. The full-length RbBPI/LBP-2 cDNA was 2652 bp in length and contained an ORF of 1422 bp encoding 473 amino acids. RbBPI/LBP-1 was significantly expressed in the spleen, liver, intestine and gill. On the other hand, RbBPI/LBP-2 showed significant expression in the kidney, peripheral blood leukocytes, and spleen. Real-time RT-PCR was used to examine RbBPI/LBP-1 and RbBPI/LBP-2 mRNA expression in kidney under conditions of bacterial and viral challenge. Experimental infection of rock bream with Streptococcus iniae, Edwardsiella tarda, and red sea bream iridovirus resulted in significant increases in RbBPI/LBP-1 and RbBPI/LBP-2 mRNA levels in the kidneys, however, the increases in transcription was seen at different time points.

Background: Increasing Increasing evidence suggests that innate immune system may have a key role in the pathogenesis of the inflammatory bowel disease (IBD). Bactericidal/permeability increasing protein (BPI) has an important role in the recognition and neutralization of gram-negative bacteria by host innate immune system. The polymorphism on BPI gene called Lys216Glu is on the suspected list of IBD pathogenesis. Methods: We studied the Lys216Glu polymorphism on BPI gene, in a Turkish IBD patient population. A total of 238 IBD patients; 116 Crohn's disease (CD) and 122 ulcerative colitis (UC), besides 197 healthy controls were included in this study. Results: The Glu/Glu genotype and allele frequencies were found to be statistically higher compared to healthy control group not only in CD patients [P: 0.03, OR: 1.87 (CI 95% 1.02-3.42) and P: 0.00001 (OR: 2.07 CI 95% 1.47-2.91) respectively] but also in UC patients [P: 0.0002, OR: 2.71 (CI 95% 1.53-4.80) and P: 0.00002 (OR: 2.71 CI 95% 1.53-4.80) respectively]. Conclusions: BPI polymorphism (Lys216Glu) is associated both to CD and UC. Our findings differ from the two Western European studies; one without any association and the other indicating an association only with CD. Our study is the first one reporting a novel association between BPI gene mutation (Lys216Glu) and UC. (C) 2010 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.

To determine if common polymorphisms in the endotoxin recognition complex influence the acute phase response as determined by the development of the systemic inflammatory response syndrome (SIRS) and platelet count on admission.This was a prospective observational cohort study. Paediatric intensive care patients (n = 913) were genotyped for common functional polymorphisms in the endotoxin recognition complex, including Toll-like receptor 4 (TLR4). We also selected potentially confounding polymorphisms in other genes of the innate immune system. SIRS was defined by age-specific consensus criteria. Platelet counts were recorded on admission.The development of SIRS was primarily determined by the nature of the insult, but carriers of TLR4 variant alleles had lower platelet counts than children with wild-type genotype [mean +/- standard error of the mean (SEM) 143 +/- 7 vs. 175 +/- 4; p = 0.0001)--independent of other innate immune system polymorphisms. These findings were validated using a patient cohort of 1,170 adults with coronary artery disease. Carriers of TLR4 polymorphisms with a history of myocardial infarction (n = 573) had lower platelet counts than those with the wild-type genotype (217 +/- 7 vs. 237 +/- 2.8; p = 0.021).Our results show that TLR4 variant alleles are associated with lower platelet counts across a range of ages and precipitating insults but that they do not influence the incidence of SIRS. This result may reflect redundancy and 'robustness' in the pathways leading to SIRS or the lack of specificity of this endpoint. Platelet count may vary with TLR4 genotype because it may be sufficiently sensitive and more linearly related to inflammation than other markers or, alternatively, there may be a direct TLR4-mediated platelet effect.

P>Background:The toll-like receptor (TLR)-related pathway is important in host defence and may be crucial in the development of asthma and atopy. Numerous studies have shown associations of TLR-related pathway genes with asthma and atopy phenotypes. So far it has not been investigated whether gene-gene interactions in this pathway contribute to atopy and asthma development.Methods:One hundred and sixty-nine haplotype tagging single nucleotide polymorphisms (SNPs) of 29 genes (i.e. membrane and intracellular receptors, TLR4 or lipopolysaccharide-binding/facilitating proteins, adaptors, interleukin-1 receptor associated kinases, kinases, chaperone molecules, transcription factors and inhibitors) were analysed for single- and multilocus associations with atopy [total and specific immunglobulin E (IgE) at 1-2 and 6-8 years] and asthma (6-8 years). A total of 3062 Dutch children from the birth cohorts PIAMA, PREVASC and KOALA (Allergenic study) were investigated. Chi-squared test, logistic regression and the data mining approach multifactor dimensionality reduction method (MDR) were used in analysis.Results:Several genes in the TLR-related pathway were associated with atopy and/or asthma [e.g. IL1RL1, BPI, NOD1, NOD2 and MAP3K7IP1]. Multiple, single associations were found with the phenotypes under study. MDR analysis showed novel, significant gene-gene interactions in association with atopy and asthma phenotypes (e.g. IL1RL1 and TLR4 with sIgE to indoor allergens and IRAK1, NOD1 and MAP3K7IP1 with asthma). Interestingly, gene-gene interactions were identified with SNPs that did not have an effect on their own.Conclusion:Our unbiased approach provided suggestive evidence for interaction between several TLR-related pathway genes important in atopy and/or asthma development and pointed to novel genes.

Antineutrophil cytoplasmic antibodies directed against bactericidal/permeability-increasing protein (BPI), an inhibitor of a lipopolysaccharide of gram-negative bacteria, are a common feature of chronic neutrophilic inflammatory processes such as cystic fibrosis. We investigated whether serum and salivary anti-BPI autoantibodies also appear in the course of acute pneumonia in 24 otherwise healthy children. Nine (38%) and four (17%) patients had detectable serum anti-BPI immunoglobulin G (IgG) (> or =4 IU mL(-1)) and IgA (ratio> or =1.2), respectively, on the day of hospital admission (day 0). There was no increase in the rate of occurrence or the concentration of these antibodies in the convalescent sera obtained on day 30. The presence of anti-BPI IgG on admission did not correlate with inflammatory markers (peripheral white blood cell count, C-reactive protein) or temperature on admission. Also, salivary anti-BPI IgA, determined on days 0, 3-5 and 30, did not appear during the course of acute pneumonia. In summary, a substantial proportion of previously healthy children have pre-existing anti-BPI IgG autoantibodies. Acute neutrophilic infection, i.e. pneumonia, however, neither triggered the appearance of new antibodies nor boosted the concentrations of pre-existing ones. Thus, in typical acute pneumonia in children, autoantibodies directed against BPI may not have clinical significance.

Escherichia coli intramammary infection elicits localized and systemic responses, some of which have been characterized in mammary secretory tissue. Our objective was to characterize gene expression patterns that become activated in different regions of the mammary gland during the acute phase of experimentally induced E. coli mastitis. Tissues evaluated were from Fürstenburg's rosette, teat cistern (TC), gland cistern (GC), and lobulo-alveolar (LA) regions of control and infected mammary glands, 12 and 24 h after bacterial (or control) infusions. The main networks activated by E. coli infection pertained to immune and inflammatory response, with marked induction of genes encoding proteins that function in chemotaxis and leukocyte activation and signaling. Genomic response at 12 h post-infection was greatest in tissues of the TC and GC. Only at 24 h post-infection did tissue from the LA region respond, at which time the response was the greatest of all regions. Similar genetic networks were impacted in all regions during early phases of intramammary infection, although regional differences throughout the gland were noted. Data support an important sentinel function for the teat, as these tissues responded rapidly and intensely, with production of cytokines and antimicrobial peptides.

At mucosal surfaces, we must co-exist with a high density of diverse microorganisms; therefore, protection against these occurs on multiple levels. Leukocyte- and epithelial derived-antimicrobial peptides and proteins (AMPs) comprise an essential component of immune defense. These molecules possess antibacterial, antifungal and signalling properties and probably contribute to defence and maintenance of homeostasis between the host and commensal microorganisms. Among these AMPs is bactericidal/permeability-increasing protein (BPI), an antimicrobial protein with potent endotoxin-neutralising activity, and several homologs. This review explores the roles of BPI and and its homologs at the mucosal interface. Congeners of BPI are under biopharmaceutical development as novel anti-infective agents, highlighting the potential therapeutic relevance of this protein family.

The bactericidal/permeability-increasing protein (BPI) is thought to play an important role in killing and clearance of Gram-negative bacteria and the neutralization of endotoxin. A possible role for BPI in clearance of cell-free endotoxin has also been suggested based on studies with purified endotoxin aggregates and blood monocytes. Because the interaction of BPI with cell-free endotoxin, during infection, occurs mainly in tissue and most likely in the form of shed bacterial outer membrane vesicles (“blebs”), we examined the effect of BPI on interactions of metabolically labeled ([14C]-acetate) blebs purified from Neisseria meningitidis serogroup B with either human monocyte-derived macrophages or monocyte-derived dendritic cells (MDDC). BPI produced a dose-dependent increase (up to 3-fold) in delivery of 14C-labeled blebs to MDDC, but not to monocyte-derived macrophages in the presence or absence of serum. Both, fluorescently labeled blebs and BPI were internalized by MDDC under these conditions. The closely related LPS-binding protein, in contrast to BPI, did not increase association of the blebs with MDDC. BPI-enhanced delivery of the blebs to MDDC did not increase cell activation but permitted CD14-dependent signaling by the blebs as measured by changes in MDDC morphology, surface expression of CD80, CD83, CD86, and MHC class II and secretion of IL-8, RANTES, and IP-10. These findings suggest a novel role of BPI in the interaction of bacterial outer membrane vesicles with dendritic cells that may help link innate immune recognition of endotoxin to Ag delivery and presentation.

Proinflammatory cytokines are now thought to play a key role in the pathophysiology of chronic heart failure, driving both symptomatic presentation and disease progression. We propose that this proinflammatory state, in turn, may be sustained through a chronic release of enterically derived bacterial endotoxin. Human trials have indicated that bacterial decontamination of the gut with concomitant decrease in lipopolysaccharide (LPS) has a positive outcome on heart disease patients. Antiendotoxin antibodies may thus represent therapeutic agents in this setting. Previously, antiendotoxin antibodies were targeted to the inner hydrophobic lipid A moiety of endotoxin in an attempt to neutralize its toxicity. These antibodies failed because they lacked specificity and bound to LPS weakly. In contrast, our studies on antiendotoxin antibodies have revealed that antibodies targeted to the hydrophilic oligosaccharides of the endotoxin have the potential to bind specifically with high affinity. Development of immunotherapeutics that can reduce systemic LPS or other agents, such as bactericidal/permeability-increasing protein that can neutralize LPS and limit inflammation safely, will enable the role of LPS in chronic heart failure to be elucidated and may pave the way to develop a new generation of effective therapeutic agents that may be directed to the treatment of chronic heart failure.

Antineutrophil cytoplasmic autoantibodies against the neutrophil granule bactericidal/permeability increasing protein (BPI-ANCA) have been found in diseases of different etiologies, such as cystic fibrosis, TAP deficiency or inflammatory bowel diseases. A common feature of these conditions is the chronic or profuse exposure of the host to Gram-negative bacteria and their endotoxin. BPI plays an important role in killing Gram-negative bacteria as well as neutralization and disposal of their endotoxin. During this interaction BPI can direct the delivery of complexes which contain endotoxin and bacterial outer membrane proteins to antigen presenting cells. Based on recent findings on how complexes of endotoxin and protein antigens need to be processed by dendritic cells in order to become presented on MHC class II molecules, a model can be proposed how Gram-negative bacterial infections can be linked to the generation of autoantibodies against BPI.

WOS:000358778800010 PubMed: 26228368 Background/Aims: Inflammatory bowel disease, a chronic inflammatory disease with unknown etiology, affects the small and large bowel at different levels. It is increasingly considered that innate immune system may have a central position in the pathogenesis of the disease. As a part of the innate immune system, bactericidal permeability increasing protein has an important role in the recognition and neutralization of gram-negative bacteria. The aim of our study was to investigate the involvement of bactericidal permeability increasing protein gene polymorphism (bactericidal permeability increasing protein Lys216Glu) in inflammatory bowel disease in a large group of Turkish patients. Patients and Methods: The present study included 528 inflammatory bowel disease patients, 224 with Crohn's disease and 304 with ulcerative colitis, and 339 healthy controls. Results: Bactericidal permeability increasing protein Lys216Glu polymorphism was found to be associated with both Crohn's disease and ulcerative colitis (P = 0.0001). The frequency of the Glu/Glu genotype was significantly lower in patients using steroids and in those with steroid dependence (P = 0.012, OR, 0.80; 95% confidence interval [CI]: 0.68-0.94; P = 0.0286, OR, 0.75; 95% CI: 0.66-0.86, respectively). There was no other association between bactericidal permeability increasing protein gene polymorphism and phenotypes of inflammatory bowel disease. Conclusions: Bactericidal permeability increasing protein Lys216Glu polymorphism is associated with both Crohn's disease and ulcerative colitis. This is the first study reporting the association of bactericidal permeability increasing protein gene polymorphism with steroid use and dependence in Crohn's disease.

Bactericidal/permeability-increasing protein (BPI) neutralizes the proinflammatory effects of lipopolysaccharide and is of potential clinical use in the treatment of fulminant Gram-negative infections. BPI is a cationic protein with antibacterial activity stored in azurophil (primary) granules of neutrophil granulocytes. However, the absence of BPI in patients with specific granule deficiency indicates a transcriptional control of BPI, which is distinct from that of other azurophil granule proteins. Accordingly, we demonstrate in vivo that the BPI mRNA level peaks, together with mRNA for specific granule proteins, during the myelocytic and metamyelocytic stage of granulocytic maturation. The human promyelocytic cell line NB4 expresses several azurophil granule proteins, but expression of BPI is undetectable. We show that treatment of NB4 cells with all-trans retinoic acid (ATRA) induces BPI expression at mRNA and at protein level. The induction is dependent on de novo protein synthesis, as judged by sensitivity to cycloheximide. Previous investigations have indicated a potential role of CCAAT/enhancer-binding protein (C/EBP) transcription factors in the regulation of BPI expression. Here, we show that induction of NB4 cells with ATRA correlates to direct binding of C/EBPβ and C/EBPε to the proximal BPI promoter, as determined by electrophoretic mobility shift analysis and chromatin immunoprecipitation. The dependency on C/EBPβ and C/EBPε provides an explanation for delayed BPI mRNA expression, as compared with mRNA of other azurophil granule proteins.

Epithelial surfaces constitute natural immunobarriers against environmental threats. These barriers are brimming with fluids that bind, transport, cleave or degrade bacterial cells and their endotoxic by-products. Saliva and the airway surface-lining fluid (ASL) comprise the important fluid constituents. Short palate, lung and nasal epithelium clone 1 (SPLUNC1) is a potential host defensive protein that is secreted from the submucosal gland to the saliva and nasal lavage fluid. However, its antimicrobial spectrum and antimicrobial mechanism is not clear. Through green fluorescence protein (GFP) mediated subcellular localization experiments in nasopharyngeal carcinoma (NPC) HNE1 cell line, we determined that the intracellular GFP-tagged SPLUNC1 protein binds to a miniscule microorganisms, approximately 50–400 nm in size, after the bactericidal permeability increasing protein (BPI) domain was deleted, GFP-tagged truncated SPLUNC1 protein lost its function of binding to the miniscule microorganisms. We verified that these microorganisms are nanobacteria (NB) with a negative staining using transmitted electronic microscope (TEM) and immunofluorescent analysis using an NB-specific antibody. We isolated and cultured the NB from the cultured nasopharyngeal carcinoma epithelia HNE1 cell supernatant. We found that the NB did not absorb the Hoechst stain, even when we extended the staining time to 35 min. However, with the time extension the larger sized NB (larger than 300 nm) did stain positively. From the biopsy specimen of NPC, we also detected the NB, which can lead to the swelling of mitochondria in the infected host cells. We hypothesize that SPLUNC1 and NB co-localization is due to the GFP-tagged SPLUNC1 protein binding to the lipopolysaccharide (LPS) of the Gram-negative NB, which can play an important role in the host defense of nasopharyngeal epithelium. This research sheds new light on the mechanism of SPLUNC1 involvement in the host upper respiratory tract defense system.

Autoantibodies against bactericidal/permeability-increasing protein (BPI-ANCA) were found in patients with cystic fibrosis (CF). It is speculated that they represent a marker of the chronic endobronchial infection and sustained inflammatory response in CF. Our aim was to evaluate whether azithromycin (AZM), through its antiinflammatory effect, could affect the level of BPI-ANCA in CF patients. Eighteen patients with CF aged 5.5-36.3 years (median 15.1) were enrolled in a randomised, double-blind, placebo-controlled trial of AZM (250 mg twice a week to 10 patients) or placebo (8 patients) for 12 weeks. BPI-ANCA levels were recorded pre- and post-treatment and compared to a group of 18 matched healthy controls. Chi-square analysis, Kruskal-Wallis and Mann-Whitney tests were used to compare between the groups. Pre- and post-treatment values were compared using the Wilcoxon Signed-Ranked test. BPI-ANCA was found in 12 CF patients (67%) and four (22%) healthy subjects (P0.001). The mean BPI-ANCA level was 3.94+/-6.15 U/ml (mean+/-SD) in healthy subjects and 38.11+/-42.34 U/ml in CF patients (P=0.023). The mean BPI-ANCA level was higher in patients with Pseudomonas aeruginosa compared to those without (64+/-35 U/ml and 25+/-41 U/ml respectively, P=0.032). No change in BPI-ANCA levels occurred in the AZM-treated patients [35 (0-127) U/ml (median (range) and 30 (0-120) U/ml, respectively] or in the placebo group [10 (0-66) U/ml and 13 (0-83) U/ml, respectively]. BPI-ANCA levels are significantly higher in patients with CF compared to healthy controls. BPIANCA levels are higher among patients colonised with P. aeruginosa. Twelve weeks of AZM therapy did not lower the BPI-ANCA level in patients with CF.