Anti-neutrophil cytoplasmatic antibodies and lung disease in cystic fibrosis

Nanoparticle-neutrophils interactions for autoimmune regulation

Neutrophils play an essential role as 'first responders' in the immune response, necessitating many immune-modulating capabilities. Chronic, unresolved inflammation is heavily implicated in the progression and tissue-degrading effects of autoimmune disease. Neutrophils modulate disease pathogenesis by interacting with the inflammatory and autoreactive cells through effector functions, including signaling, degranulation, and neutrophil extracellular traps (NETs) release. Since the current gold standard systemic glucocorticoid administration has many drawbacks and side effects, targeting neutrophils in autoimmunity provides a new approach to developing therapeutics. Nanoparticles enable targeting of specific cell types and controlled release of a loaded drug cargo. Thus, leveraging nanoparticle properties and interactions with neutrophils provides an exciting new direction toward novel therapies for autoimmune diseases. Additionally, recent work has utilized neutrophil properties to design novel targeted particles for delivery into previously inaccessible areas. Here, we outline nanoparticle-based strategies to modulate neutrophil activity in autoimmunity, including various nanoparticle formulations and neutrophil-derived targeting.

Differential Enhancement of Neutrophil Phagocytosis by Anti-Bactericidal/Permeability-Increasing Protein Antibodies

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.

Killing three birds with one BPI: Bactericidal, opsonic, and anti-inflammatory functions

Bactericidal/permeability-increasing protein (BPI) is an anti-microbial protein predominantly expressed in azurophilic granules of neutrophils. BPI has been shown to mediate cytocidal and opsonic activity against Gram-negative bacteria, while also blunting inflammatory activity of lipopolysaccharide (LPS). Despite awareness of these functions in vitro, the magnitude of the contribution of BPI to innate immunity remains unclear, and the nature of the functional role of BPI in vivo has been submitted to limited investigation. Understanding this role takes on particular interest with the recognition that autoimmunity to BPI is tightly linked to a specific infectious trigger like Pseudomonas aeruginosa in chronic lung infection. This has led to the notion that anti-BPI autoantibodies compromise the activity of BPI in innate immunity against P. aeruginosa, which is primarily mediated by neutrophils. In this review, we explore the three main mechanisms in bactericidal, opsonic, and anti-inflammatory of BPI. We address the etiology and the effects of BPI autoreactivity on BPI function. We explore BPI polymorphism and its link to multiple diseases. We summarize BPI therapeutic potential in both animal models and human studies, as well as offer therapeutic approaches to designing a sustainable and promising BPI molecule.

BPI-ANCA is expressed in the airways of cystic fibrosis patients and correlates to platelet numbers and Pseudomonas aeruginosa colonization

BACKGROUND

Autoantibodies to bactericidal/permeability-increasing protein (BPI), BPI-ANCA, are often present in serum of patients with cystic fibrosis (CF), and correlate to airway colonization with Pseudomonas aeruginosa. The aim of the study was to investigate if BPI-ANCA IgA is also present in the airways of CF patients, and if its presence correlates with neutrophil counts, platelets, and P. aeruginosa DNA in sputum.

METHODS

BPI-ANCA IgA was quantified in serum and sputum samples from adult CF patients (n = 45) by ELISA. Sputum neutrophil counts, platelets, and platelet-neutrophil complexes were assessed by flow cytometry, and P. aeruginosa DNA was analysed with RT-PCR.

RESULTS

Serum BPI-ANCA IgA was present in 44% of the study participants, and this group also had significantly enhanced BPI-ANCA levels in sputum compared to serum negative patients. Sputum levels of BPI-ANCA IgA correlated with P. aeruginosa DNA (r = 0.63, p = 0.0003) and platelet counts in sputum (r = 0.60, p = 0.0002).

CONCLUSIONS

BPI-ANCA is expressed in the airways of CF patients and correlates with P. aeruginosa load and platelet counts, suggesting a link to airway inflammation and mucosal immunity.

Prevalence of Bactericidal/Permeability-Increasing Protein Autoantibodies in Cystic Fibrosis Patients: Systematic Review and Meta-Analysis

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 < 0.01). Conclusions: Given the highly varying prevalence of BPI-ANCA in patients with CF, more well-designed prospective clinical studies are needed to determine its true prevalence and clinical relevance.

RNA sequencing data from neutrophils of patients with cystic fibrosis reveals potential for developing biomarkers for pulmonary exacerbations

BACKGROUND

There is no effective way to predict cystic fibrosis (CF) pulmonary exacerbations (CFPE) before they become symptomatic or to assess satisfactory treatment responses.

METHODS

RNA sequencing of peripheral blood neutrophils from CF patients before and after therapy for CFPE was used to create transcriptome profiles. Transcripts with an average transcripts per million (TPM) level > 1.0 and a false discovery rate (FDR) < 0.05 were used in a cosine K-nearest neighbor (KNN) model. Real time PCR was used to corroborate RNA sequencing expression differences in both neutrophils and whole blood samples from an independent cohort of CF patients. Furthermore, sandwich ELISA was conducted to assess plasma levels of MRP8/14 complexes in CF patients before and after therapy.

RESULTS

We found differential expression of 136 transcripts and 83 isoforms when we compared neutrophils from CF patients before and after therapy (>1.5 fold change, FDR-adjusted P < 0.05). The model was able to successfully separate CF flare samples from those taken from the same patients in convalescence with an accuracy of 0.75 in both the training and testing cohorts. Six differently expressed genes were confirmed by real time PCR using both isolated neutrophils and whole blood from an independent cohort of CF patients before and after therapy, even though levels of myeloid related protein MRP8/14 dimers in plasma of CF patients were essentially unchanged by therapy.

CONCLUSIONS

Our findings demonstrate the potential of machine learning approaches for classifying disease states and thus developing sensitive biomarkers that can be used to monitor pulmonary disease activity in CF.

Burkholderia cepacia complex and limited cutaneous vasculitis in patients with cystic fibrosis: a case series

There is a high association of reactive skin presentations, mainly limited cutaneous vasculitis in patients with cystic fibrosis and Burkholderia cepcia complex chronic infection. This may be due to raised levels of circulating inflammatory mediators.

Pseudomonas toxin pyocyanin triggers autophagy: Implications for pathoadaptive mutations

Pseudomonas aeruginosa can establish life-long chronic infection in patients with cystic fibrosis by generating genetic loss-of-function mutations, which enhance fitness of the bacterium in the airways. However, the precise role of the pathoadaptive mutations in persistence in chronic airways infection remains largely unknown. Here we demonstrate that pyocyanin, a well-described P. aeruginosa virulence factor that plays an important role in the initial infection, promotes autophagy in bronchial epithelial cells. Disruption of phzM, which is required for pyocyanin biosynthesis, leads to a significant reduction in autophagy in Beas-2B cells and lung tissues. Pyocyanin-induced autophagy is mediated by the EIF2AK4/GCN2-EIF2S1/eIF2α-ATF4 pathway. Interestingly, rats infected with the phzMΔ mutant strain have high mortality rate and numbers of colony-forming units, compared to those infected with wild-type (WT) P. aeruginosa PA14 strain, during chronic P. aeruginosa infection. In addition, the phzMΔ mutant strain induces more extensive alveolar wall thickening than the WT strain in the pulmonary airways of rats. As autophagy plays an essential role in suppressing bacterial burden, our findings provide a detailed understanding of why reduction of pyocyanin production in P. aeruginosa in chronic airways infections has been associated with better host adaptation and worse outcomes in cystic fibrosis.

Evaluation of genome-wide expression profiles of blood and sputum neutrophils in cystic fibrosis patients before and after antibiotic therapy

In seeking more specific biomarkers of the cystic fibrosis (CF) lung inflammatory disease that would be sensitive to antibiotic therapy, we sought to evaluate the gene expression profiles of neutrophils in CF patients before treatment in comparison with non-CF healthy individuals and after antibiotic treatment. Genes involved in neutrophil-mediated inflammation, i.e. chemotaxis, respiratory burst, apoptosis, and granule exocytosis, were the targets of this study. Microarray analysis was carried out in blood and airway neutrophils from CF patients and in control subjects. A fold change (log) threshold of 1.4 and a cut-off of p<0.05 were utilized to identify significant genes. Community networks and principal component analysis were used to distinguish the groups of controls, pre- and post-therapy patients. Control subjects and CF patients before therapy were readily separated, whereas a clear distinction between patients before and after antibiotic therapy was not possible. Blood neutrophils before therapy presented 269 genes down-regulated and 56 up-regulated as compared with control subjects. Comparison between the same patients before and after therapy showed instead 44 genes down-regulated and 72 up-regulated. Three genes appeared to be sensitive to therapy and returned to "healthy" condition: phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1), hydrogen voltage-gated channel 1 (HVCN1), and β-arrestin 1 (ARRB1). The up-regulation of these genes after therapy were confirmed by real time PCR. In airway neutrophils, 1029 genes were differentially expressed post- vs pre-therapy. Of these, 30 genes were up-regulated and 75 down-regulated following antibiotic treatment. However, biological plausibility determined that only down-regulated genes belonged to the gene classes studied for blood neutrophils. Finally, it was observed that commonly expressed genes showed a greater variability in airway neutrophils than that found in blood neutrophils, both before and after therapy. These results indicate more specific targets for future interventions in CF patients involving respiratory burst, apoptosis, and granule exocytosis.

Anti-BPIFA1/SPLUNC1: a new autoantibody prevalent in patients with endstage cystic fibrosis

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.

Effects of treatment in the levels of circulating cytokines and growth factors in cystic fibrosis and dialyzed patients by multi-analytical determination with a biochip array platform

Chronic inflammatory diseases need non-invasive sensitive, reliable and predictive clinical biomarkers for diagnosis and monitoring therapy. Since inflammation is a complex phenomenon, simultaneous evaluation of different analytes in the same sample may help in defining this complexity and in developing specific anti-inflammatory intervention strategies. In this study, we used a biochip array system capable of measuring 12 cytokines and growth factors (IL-2, IL-4, IL-6, IL-8, IL-10, IL-1 α, IL-1 β, IFN-γ, TNF-α, MCP-1, VEGF, and EGF) in three groups: 97 control subjects; 24 cystic fibrosis (CF) patients before and during the antibiotic treatment (6 and 15days) for acute pulmonary exacerbation as well as 15days after the withdrawal of therapy; 22 children and young adults on chronic hemodialysis (HD) at the beginning and at the end of a standard HD session. CF patients in acute exacerbation displayed higher IL-2, IL-6, VEGF and MCP-1 levels than the control subjects. IL-6 significantly decreased during therapy (P<0.01) but not 15days after the withdrawal of therapy. IL-8 and EGF levels were significantly lower after 15days from the interruption of therapy (P<0.05 and P<0.01 respectively). Regression analysis showed that IL-4 and IL-6 correlated with the amelioration of the respiratory function during therapy. Patients on HD displayed higher IL-6 but lower IL-2, IL-4, IL-8, IFN-γ and EGF levels than control subjects. Serum levels of IL-8, IL-10 and IFN-γ were significantly higher at the end of the HD session (P<0.05 for all three). A biochip array allowed to define a pattern of cytokines/growth factors associated with an acute exacerbation in CF patients and IL-4 and IL-6 as predictors of response to therapy. In younger HD patients, we identified a biomarker pattern which is different from that of older patients. Finally, further studies are warranted to examine the role of these biomarkers in the pathogenesis of complications in HD patients.

Glomerular disease in patients with infectious processes developing antineutrophil cytoplasmic antibodies

To identify differences in treatment and outcome of various types of glomerulonephritis developing in the course of infections triggering antineutrophil cytoplasmic antibody (ANCA) formation, we analyzed published reports of 50 patients. Immunosuppressives were added to antibiotics in 22 of 23 patients with pauci-immune glomerulonephritis. Improvement was noted in 85% of 20 patients with information on outcomes. Death rate was 13%. Corticosteroids were added to antibiotics in about 50% of 19 patients with postinfectious glomerulonephritis. Improvement rate was 74%, and death rate was 26%. Two patients with mixed histological features were analyzed under both pauci-immune and post-infectious glomerulonephritis categories. In 9 patients with other renal histology, treatment consisted of antibiotics alone (7 patients), antibiotics plus immunosuppressives (1 patient), or immunosuppressives alone (1 patient). Improvement rate was 67%, permanent renal failure rate was 22%, and death rate was 11%. One patient with antiglomerular basement disease glomerulonephritis required maintenance hemodialysis. Glomerulonephritis developing in patients who became ANCA-positive during the course of an infection is associated with significant mortality. The histological type of the glomerulonephritis guides the choice of treatment. Pauci-immune glomerulonephritis is usually treated with addition of immunosuppressives to antibiotics.

Extensive endoscopic image-guided sinus surgery decreases BPI-ANCA in patients with cystic fibrosis

Antineutrophil cytoplasm autoantibodies (ANCA) directed against bactericidal/permeability-increasing protein (BPI) are common in patients with cystic fibrosis (CF), and serum levels are correlated with lung colonization by Pseudomonas aeruginosa and the severity of lung damage. The production of BPI-ANCA may be due to the costimulation of BPI when mounting an immune response against P. aeruginosa. The effect of surgery aiming to eradicate bacteria and infected tissue on BPI-ANCA levels is sparsely described. A cohort of patients with CF were included: 53 patients having extensive image-guided sinus surgery (EIGSS) with topical postoperative antibiotic treatment, 131 non-operated controls and 36 who had double lung transplantation (LTX). In all 219 patients, serum samples before and after surgery or at similar intervals were analysed for IgG and IgA BPI-ANCA. The EIGSS group showed a highly significant decrease in both IgA and IgG BPI-ANCA levels compared with their own preoperative values and control group values (P < 0.001-0.02). The LTX patients also showed a highly significant decrease in both IgA and IgG BPI-ANCA levels (P < 0.001). EIGSS and LTX decrease IgA and IgG BPI-ANCA levels in patients with CF, indicating that extensive removal of infected tissue influences the pathogenic process of autoantibody production. The results shown herein are in favour of applying EIGSS in selected patients with CF and for using BPI-ANCA as a surrogate marker for guiding further therapeutic interventions.

Systemic vasculitis associated with anti-neutrophil cytoplasmic antibodies against bactericidal/permeability increasing protein

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.

BPI-ANCA and long-term prognosis among 46 adult CF patients: a prospective 10-year follow-up study

Introduction. Anti-neutrophil cytoplasmic antibodies specific for bactericidal/permeability-increasing protein (BPI-ANCA) are frequent in CF patients and mainly develop in response to infection with Pseudomonas aeruginosa. It is not known to what extent BPI-ANCA correlates to prognosis. Objectives. To evaluate the prognostic value of IgA-BPI-ANCA, measured at the beginning of the study, for transplantation-free survival. Methods. A cohort of 46 adult, nontransplanted CF patients was generated, 1995–1998, and characterized using Leeds criteria, lung function, and IgA-BPI-ANCA levels measured by ELISA. The cohort was followed until December 2009, using the combined endpoint of death or lung transplantation. Results. Lung function and IgA-BPI-ANCA, but not Leeds criteria, were significantly associated with adverse outcome. No patient with normal lung function at baseline reached endpoint. Within 10 years 8/11 with high BPI-ANCA reached an endpoint compared to 3/17 ANCA-negative patients. A similar result was seen within the Leeds I group where 7 out of 9 BPI-ANCA-positive patients reached endpoint, compared to none of the 5 patients without BPI-ANCA. Conclusions. IgA-BPI-ANCA is associated with adverse outcome among Pseudomonas aeruginosa infected CF patients, suggesting that BPI-ANCA is a biomarker of an unfavourable host-pathogen interaction.

The bactericidal/permeability-increasing protein (BPI) in the innate defence of the lower airways

The human BPI (bactericidal/permeability-increasing protein), stored in primary azurophilic granula of neutrophil granulocytes and produced by mucosal epithelia, has been known for decades to bind LPS (lipopolysaccharide) with very high affinity and to efficiently kill Gram-negative bacteria. Thus BPI potentially represents a central component of the innate immune system to directly combat microbes and modulate subsequent adaptive immune responses. Especially in the lungs, which are frequently exposed to a variety of inhaled pathogens, antimicrobial innate defence molecules such as BPI, are of exceptional relevance. In the present review, we highlight possible functions of BPI during acute pneumonia and CF (cystic fibrosis)-associated chronic infections in the lung.

Pseudomonas aeruginosa in cystic fibrosis: pyocyanin negative strains are associated with BPI-ANCA and progressive lung disease

The clinical consequence of chronic Pseudomonas aeruginosa colonization in cystic fibrosis (CF) varies between individuals for unknown reasons. Auto-antibodies against bactericidal/permeability increasing protein (BPI-ANCA) are associated with poor prognosis in CF. We hypothesize that there is a correlation between the presence of BPI-ANCA, the properties of the colonizing bacteria and the clinical conditions of the host. We compared isolates of P. aeruginosa from BPI-ANCA positive CF patients who have deteriorating lung disease with BPI-ANCA negative CF patients who are in stable clinical conditions. Epithelial cells (A549) and isolated polymorphonuclear granulocytes (PMNs) were stimulated with the isolates and cell death was analyzed with flow cytometry. We found that the ANCA associated strains in most cases showed pyocyanin negative phenotypes. These strains also induced less inflammatory response than the non-ANCA associated strains as shown by apoptosis and necrosis of epithelial cells and neutrophils. Our results suggest that colonization with strains of P. aeruginosa that induce a weak inflammatory response is associated with unfavorable outcome in CF. We speculate that inadequate control of pathogen proliferation through an insufficient inflammatory response results in a slowly increasing number of bacteria and accumulation of dying PMNs in the airways, contributing to progression in CF lung disease.

Potential of anti-inflammatory treatment for cystic fibrosis lung disease

Cystic fibrosis (CF) is the most common life-shortening genetic disorder in Caucasians. With improved diagnosis and treatment, survival has steadily increased. Unfortunately, the overwhelming majority of patients still die from respiratory failure caused by structural damage resulting from airway obstruction, recurrent infection, and inflammation. Here, we discuss the role of inflammation and the development of anti-inflammatory therapies to treat CF lung disease. The inflammatory host response is the least addressed component of CF airway disease at this time. Current challenges in both preclinical and clinical investigation make the identification of suitable anti-inflammatory drugs more difficult. Despite this, many researchers are making significant progress toward this goal and the CF research community has reason to believe that new therapies will emerge from these efforts.

[Renal diseases in cystic fibrosis]

Patients with cystic fibrosis (CF) show a continuing improvement in their life expectancy thanks to advances in knowledge of this disorder, allowing better multidisciplinary routine monitoring and earlier therapeutic interventions. Likewise, more than of 40% of these patients are adults and CF is no more only a pediatric disease. Due to their higher life expectancy, CF patients present new and unusual complications that were not recorded before. Among them, some renal disorders have to be added to the CF-related renal diseases. They are due to frequent and prolonged exposure to various potentially nephrotoxic factors that need to be taken into account early enough in order to avoid renal failure : essentially risk factors for kidney stones formation, bacterial infections with their associated immune complexes diseases, nephrotoxic effects of antibiotics, diabetes mellitus. Because we observed a case of IgA glomerulonephritis in a 35-year-old patient with cystic fibrosis, we have searched about all these renal consequences due to this affection and here report them.

Sputum biomarkers of inflammation in cystic fibrosis lung disease

Pulmonary biomarkers are being used more frequently to monitor disease activity and evaluate response to treatment in individuals with cystic fibrosis (CF). This article summarizes the current state of knowledge of biomarkers of inflammation relevant to CF lung disease, and the tools to measure inflammation, with specific emphasis on sputum. Sputum is a rich, noninvasive source of biomarkers of inflammation and infection. Sputum induction, through the inhalation of hypertonic saline, has expanded the possibilities for monitoring airway inflammation and infection, especially in individuals who do not routinely expectorate sputum. We critically examine the existing data supporting the validity of sputum biomarkers in CF, with an eye toward their application as surrogate endpoints or outcome measures in CF clinical trials. Further validation studies are needed regarding the variability of inflammatory biomarker measurements, and to evaluate how these biomarkers relate to disease severity, and to longitudinal changes in lung function and other clinical endpoints. We highlight the need to incorporate sputum collection, by induction if necessary, and measurement of sputum biomarkers into routine CF clinical care. In the future, pulmonary biomarkers will likely be useful in predicting disease progression, indicating the onset and resolution of a pulmonary exacerbation, and assessing response to current therapies or candidate therapeutics.

The bactericidal/permeability-increasing protein (BPI) in infection and inflammatory disease

Gram-negative bacteria (GNB) and their endotoxin present a constant environmental challenge. Endotoxins can potently signal mobilization of host defenses against invading GNB but also potentially induce severe pathophysiology, necessitating controlled initiation and resolution of endotoxin-induced inflammation to maintain host integrity. The bactericidal/permeability-increasing protein (BPI) is a pluripotent protein expressed, in humans, mainly neutrophils. BPI exhibits strong antimicrobial activity against GNB and potent endotoxin-neutralizing activity. BPI mobilized with neutrophils in response to invading GNB can promote intracellular and extracellular bacterial killing, endotoxin neutralization and clearance, and delivery of GNB outer membrane antigens to dendritic cells. Tissue expression by dermal fibroblasts and epithelia could further amplify local levels of BPI and local interaction with GNB and endotoxin, helping to constrain local tissue infection and inflammation and prevent systemic infection and systemic inflammation. This review article focuses on the structural and functional properties of BPI with respect to its contribution to host defense during GNB infections and endotoxin-induced inflammation and the genesis of autoantibodies against BPI that can blunt BPI activity and potentially contribute to chronic inflammatory disease.

Anticuerpos anticitoplasma de neutrófilo en enfermedades distintas a las vasculitis idiopáticas: correlaciones clínicas y especificidades antigénicas

The value of antineutrophil cytoplasmic antibodies (ANCA) in the diagnosis of several types of idiopathic vasculitis has been well-documented: In these diseases the ANCA show two classical immunofluorescence patterns, C-ANCA and P-ANCA, which have antigen specificity for the myeloperoxidase and proteinase 3, respectively. However, the appearance of ANCA in very different diseases other than the mentioned vasculitis, has been documented in recent years. In these diseases, the ANCA generally have atypical immunofluorescence patterns and are directed against neutrophil antigens that are different from the previous two, their clinical value still being under debate.

Autoantibody response to BPI predict disease severity and outcome in cystic fibrosis

BACKGROUND

Autoantibodies against bactericidal permeability increasing protein (BPI-ANCA) are frequently present in cystic fibrosis patients and have been reported to be associated to colonization with Pseudomonas (P) aeruginosa and lung damage. In the present study, we investigated BPI-ANCA as a prognostic marker and its relation to P. aeruginosa colonization and lung function.

METHODS

BPI-ANCA, measured by ELISA, was examined relative to lung function and microbiological findings. The prognostic value of BPI-ANCA was assessed in 46 adult patients followed for 1.2-8.9 years. The cross-sectional investigation was performed in 366 patients (age 0.5-55).

RESULTS

The presence of BPI-ANCA predicted poor prognosis. An adverse outcome occurred in 15/28 BPI-ANCA positive patients and in 2/18 BPI-ANCA negative patients (p=0.01). This result remained valid when the patients were stratified according to lung function (p=0.03). Findings of BPI-ANCA were correlated to P. aeruginosa colonization and lung damage. Development of BPI-ANCA occurred after colonization with P. aeruginosa. All colonized patients did not develop BPI-ANCA. The BPI-ANCA levels were fairly stable during the disease course, but decreased significantly following lung transplantation.

CONCLUSION

BPI-ANCA responses follow colonization with P. aeruginosa and may be predictive for lung damage.

Expression and antimicrobial function of bactericidal permeability-increasing protein in cystic fibrosis patients

In cystic fibrosis (CF), the condition limiting the prognosis of affected children is the chronic obstructive lung disease accompanied by chronic and persistent infection with mostly mucoid strains of Pseudomonas aeruginosa. The majority of CF patients have antineutrophil cytoplasmic antibodies (ANCA) primarily directed against the bactericidal permeability-increasing protein (BPI) potentially interfering with antimicrobial effects of BPI. We analyzed the expression of BPI in the airways of patients with CF. In their sputum samples or bronchoalveolar lavage specimens, nearly all patients expressed BPI mRNA and protein, which were mainly products of neutrophil granulocytes as revealed by intracellular staining and subsequent flow cytometry. Repeated measurements revealed consistent individual BPI expression levels during several months quantitatively correlating with interleukin-8. In vitro, P. aeruginosa isolates from CF patients initiated the rapid release of BPI occurring independently of protein de novo syntheses. Furthermore, purified natural BPI as well as a 27-mer BPI-derived peptide displayed antimicrobial activity against even patient-derived mucoid P. aeruginosa strains and bacteria resistant against all antibiotics tested. Thus, BPI that is functionally active against mucoid P. aeruginosa strains is expressed in the airways of CF patients but may be hampered by autoantibodies, resulting in chronic infection.