Hendrik Schultz

The endotoxin-binding bactericidal/permeability-increasing protein (BPI): a target antigen of autoantibodies

The bactericidal/permeability‐increasing protein (BPI) is anendotoxin‐binding neutrophil leukocyte‐granule protein withantibacterial and anti‐endotoxin properties. A recombinant form of BPI(rBPI21) has been developed and is being tested as atherapeutic agent to treat Gram‐negative bacterial infections andexposure to Gram‐negative bacterial endotoxin. BPI is also a targetantigen of anti‐neutrophil cytoplasmic autoantibodies (ANCA). BPI‐ANCAare present in cystic fibrosis, inflammatory bowel disease, vasculitis,and primary sclerosing cholangitis; presence of BPI‐ANCA appearsassociated with a higher inflammatory disease activity and greaterorgan damage. BPI‐ANCA as well as ANCA directed at otherneutrophil‐granule proteins may exacerbate inflammation by nonspecificeffects of extracellular and cell‐associated immune complexes. BPI‐ANCAmay further worsen inflammation by reducing the ability of BPI topromote clearance of Gram‐negative bacteria and bacterial‐associatedendotoxin.

Autoantibodies against the bactericidal/permeability-increasing protein from inflammatory bowel disease patients can impair the antibiotic activity of bactericidal/permeability-increasing protein

Bactericidal/permeability-increasing protein (BPI) is an antineutrophil cytoplasmic autoantibody (ANCA) target antigen in inflammatory bowel disease (IBD). The aim of this study was to characterize binding regions of BPI-autoantibodies and to analyze their ability to block the antibiotic effect of BPI. Sera of 24 ulcerative colitis and Crohn’s disease patients were examined in indirect immuno-fluorescence, ANCA enzyme-linked immunosorbent assay (ELISA), and by epitope mapping with 13mer peptides and Western blot for presence of BPI-autoantibodies. IgG preparations were used to determine inhibition of BPI’s antimicrobial function by BPI-autoantibodies in a bacterial growth inhibition assay. BPI-autoantibodies were detected by ELISA in 18/24 patients. Epitope mapping and western blotting revealed an additional 3 patients with BPI-autoantibodies. IgG preparations of all patients with Crohn’s disease and 9 of 12 ulcerative colitis patients could inhibit the antibiotic function of BPI in vitro as compared with healthy control subjects. Inhibiting BPI-autoantibodies correlated with extraintestinal manifestations, peripheral blood leukocyte counts, and anemia. BPI-autoantibodies recognizing the N-terminal portion were associated with greater mucosal damage and intestinal extent of disease. BPI is a frequent target antigen of autoantibodies in ulcerative colitis and Crohn’s disease. Inhibition of the antibiotic function mediated by the N-terminal region of BPI by these autoantibodies may contribute to a proinflammatory environment in IBD patients.

Bactericidal/Permeability-Increasing Protein Is Expressed by Human Dermal Fibroblasts and Upregulated by Interleukin 4

ABSTRACT The bactericidal/permeability-increasing protein (BPI) is an antibiotic- and endotoxin-neutralizing protein of granulocytes and epithelial cells. Constitutive expression of BPI, which increases upon interleukin 4 stimulation, by human dermal fibroblast was demonstrated, suggesting an important role of BPI in gram-negative bacterial clearance and a dampened response to endotoxin in the skin.

Anti-neutrophil cytoplasmic antibodies directed against the bactericidal/permeability-increasing protein (BPI) in pediatric cystic fibrosis patients do not recognize N-terminal regions important for the anti-microbial and lipopolysaccharide-binding activity of BPI

This study was performed to examine the prevalence and clinical correlates of bactericidal/permeability‐increasing protein anti‐neutrophil cytoplasmic antibodies (BPI‐ANCA) in pediatric cystic fibrosis (CF) patients and to elucidate their possible role in CF pulmonary pathology. Sera of 27 CF patients were tested for ANCA by indirect immunofluorescence (IFT) and by enzyme‐linked immunosorbent assay (ELISA) for ANCA sub‐specificities. BPI‐ANCA were examined by using standard ELISA for BPI, lipopolysaccharide‐binding protein (LBP), and BPI/LBP fusion proteins to epitope map the main binding sites and look for cross‐reactivity with LBP. Pulmonary function and serum concentrations of total immunoglobulin G (IgG) were measured and infections were diagnosed. In addition, release of reactive oxygen species (ROS) by neutrophil granulocytes was measured after stimulation with monoclonal BPI‐ANCA. Using IFT, two patients showed atypical ANCA staining, six patients exhibited perinuclear ANCA staining, and no cytoplasmic ANCA staining was detected. Of 27 patients, 13 (48%) were BPI‐ANCA (IgG) positive, and three were also immunoglobulin A (IgA) BPI‐ANCA positive; one patient had ANCA against lactoferrin; and no proteinase 3 ANCA was detected in any of the patients. All BPI‐ANCA bound to the C‐terminal region of the molecule; none bound to the N‐terminus or to LBP. There was no significant correlation between clinical data and the occurence of BPI‐ANCA in this cross‐sectional study. Release of ROS from granulocytes was induced by monoclonal BPI‐ANCA. Activation of neutrophils and possible modulation of BPI‐mediated opsonophagocytosis and disposal of Gram‐negative bacteria and lipopolysaccharides by BPI‐ANCA raise the possibility that they contribute to pulmonary pathology in pediatric CF patients but intervention longitudinal studies in large groups of patients are needed to establish a causative association.

Use of native and recombinant bactericidal/permeability-increasing proteins (BPI) as antigens for detection of BPI-ANCA

Anti-neutrophil cytoplasmic antibodies (ANCA) against native bactericidal/permeability-increasing protein (nBPI) have gained increasing diagnostic significance in inflammatory bowel disease and cystic fibrosis. However, routine detection of BPI-ANCA requires pure antigen in large quantities. As nBPI is difficult to isolate and is very susceptible to proteolytic cleavage with subsequent epitope loss, it was the aim of this study to determine whether recombinant BPI (rBPI) can be used as an alternative to nBPI as target antigen for ANCA in diagnostic procedures. Therefore, 93 BPI-ELISA-positive sera and controls were compared in different ELISAs using nBPI, rBPI, unglycosylated rBPI and a 21-kDa amino-terminal fragment of rBPI. ELISA results were confirmed by immunoblotting and all sera were tested in indirect immunofluorescence (IFT). There was an 88% (82/93) agreement in recognition of nBPI and rBPI by ANCA in both ELISA systems, yet the quantitation of BPI-ANCA in relative units showed a less optimal result and correlated only by 45% (p < 0.01). Most sera recognized nBPI, rBPI and unglycosylated rBPI equally suggesting that glycosylation has no influence on antigen recognition. Only two sera were positive for the 21-kDa nBPI indicating that the binding sites for ANCA are either conformational epitopes and/or are located mainly on the carboxy-terminal part of the BPI molecule. Most BPI-ELISA-positive sera were negative in IFT (43%), but a perinuclear (pANCA, 30%), a cytoplasmic (cANCA,10%) or an atypical ANCA (aANCA, 2%) staining pattern, as well as a cytoplasmic pattern only on formaldehyde-fixed granulocytes (13%) were also observed. Overall, no characteristic pattern was seen for BPI-ELISA-positive sera in IFT. Taken together, these data suggest that rBPI offers an excellent alternative to nBPI for broad-based BPI-ANCA ELISA and will be of great value in further investigations of BPI-ANCA interactions.

BPI-ANCA is found in reactive arthritis caused by Yersinia and Salmonella infection and recognise exclusively the C-terminal part of the BPI molecule

Objective: To examine the prevalence, binding sites and functional interactions of antineutrophil cytoplasmic autoantibodies (ANCA) against the bactericidal/permeability increasing protein (BPI) in reactive arthritis (ReA). Methods: Sera were analysed for the occurrence of ANCA by indirect immunofluorescence microscopy (IIF) and ELISA. Binding sites were determined using BPI, lipopolysaccharid binding protein (LBP), and fusion proteins of both proteins in ELISA. In addition, the effect of antibodies on the antibiotic activity of BPI was examined. Results: BPI-ANCA was found in patients with Yersinia- and Salmonella-triggered ReA and directed against the C-terminal portion of BPI. Goat anti BPI antibodies recognising this part inhibited the antibiotic activity of BPI in vitro. Conclusion: BPI-ANCA was associated with ReA triggered by Salmonella and Yersinia infection. Directed against the C-terminal part of BPI, it can potentially inhibit its antibiotic activity and might be useful to identify patients with infectious bowel disease prone to extraintestinal sequelae.OBJECTIVE To examine the prevalence, binding sites and functional interactions of antineutrophil cytoplasmic autoantibodies (ANCA) against the bactericidal/permeability increasing protein (BPI) in reactive arthritis (ReA). METHODS Sera were analysed for the occurrence of ANCA by indirect immunofluorescence microscopy (IIF) and ELISA. Binding sites were determined using BPI, lipopolysaccharid binding protein (LBP), and fusion proteins of both proteins in ELISA. In addition, the effect of antibodies on the antibiotic activity of BPI was examined. RESULTS BPI-ANCA was found in patients with Yersinia- and Salmonella-triggered ReA and directed against the C-terminal portion of BPI. Goat anti BPI antibodies recognising this part inhibited the antibiotic activity of BPI in vitro. CONCLUSION BPI-ANCA was associated with ReA triggered by Salmonella and Yersinia infection. Directed against the C-terminal part of BPI, it can potentially inhibit its antibiotic activity and might be useful to identify patients with infectious bowel disease prone to extraintestinal sequelae.

Bactericidal Permeability Increasing Protein (BPI)-ANCA markiert chronische entzündliche Darmerkrankungen und entzündliche hepatobiliäre Erkrankungen

Zusammenfassung□ HintergrundBactericidal permeability increasing protein (BPI) ist ein antibakteriell wirksames Granulozytenprodukt, das Zielantigen für Antineutrophilenzytoplasma-Antikörper (ANCA) sein kann. Die klinischen Assoziationen von Autoantikörpern gegen BPI (BPI-ANCA) sind weitgehend unklar.□ Patienten und MethodenEs wurden 587 Seren von Patienten mit chronischen entzündlichen Darmerkrankungen, entzündlichen hepatobiliären Erkrankungen, primären systemischen Vaskulitiden und anderen entzündlichen rheumatischen Erkrankungen mittels indirektem Immunfluoreszenztest und monospezifischem ELISA auf BPI-ANCA untersucht.□ ErgebnisseDie Prävalenz von BPI-ANCA betrug 43% bei der Colitis ulcerosa, 23% beim Morbus Crohn, 35% bei der primären sklerosierenden Cholangitis, 25% bei der primären biliären Leberzirrhose und 29% bei autoimmunen Hepatitiden. Die Prävalenz bei einem Spektrum von systemischen Vaskulitiden, entzündlichen Gelenkerkrankungen und Kollagenosen lag bei lediglich 3 bis 11%. Im Gegensatz zu PR3-ANCA und MPO-ANCA zeigte BPI-ANCA keine Assoziation zu einem bestimmten Färbemuster im Immunfluoreszenztest auf äthanol- und formalinfixierten Granulozyten.□ SchlußfolgerungDiese Studie zeigt, daß BPI-ANCA neben PR3-ANCA und MPO-ANCA die dritte immundiagnostisch nutzbare ANCA-Spezifität mit einem begrenzten Spektrum von klinischen Assoziationen ist. Die diagnostische und prognostische Relevanz von BPI-ANCA bei den beschriebenen Erkrankungen wird derzeit prospektiv untersucht.Summary□ BackgroundBactericidal permeability increasing protein (BPI) is an antibacterial product of neutrophilic granulocytes that can serve as target antigen for antineutrophil cytoplasmic antibodies (ANCA). The clinical associations of autoantibodies angainst BPI (BPI-ANCA) are essentially unclear.□ Patients and Methods587 sera from patients with chronic inflammatory bowel diseases, inflammatory hepatobiliary diseases, primary systemic vasculitides and other rheumatological diseases were examined for BPI-ANCA by monospecific ELISA and a standard indirect immunofluorescence test for ANCA.□ ResultsThe prevalence of BPI-ANCA was 43% in ulcerative colitis, 23% in Crohn’s disease, 35% in primary sclerosing cholangitis, 25% in primary biliary cirrhosis and 29% in autoimmune hepatitides. In a spectrum of systemic vasculitides, inflammatory joint diseases and collagen vascular diseases the prevalence was only 3 to 11%. In contrast to PR3-ANCA and MPO-ANCA, BPI-ANCA was not associated with a particular pattern of fluorescence in the immunofluorescence test on ethanol- and formalin-fixed neutrophils.□ ConclusionThis study shows that BPI-ANCA is the third ANCA specificity, besides PR3-ANCA and MPO-ANCA, with a limited spectrum of clinical associations. The diagnostic and prognostic relevance of BPI-ANCA in the above clinical conditions is being examined prospectively.BACKGROUND Bactericidal permeability increasing protein (BPI) is an antibacterial product of neutrophilic granulocytes that can serve as target antigen for antineutrophil cytoplasmic antibodies (ANCA). The clinical associations of autoantibodies against BPI (BPI-ANCA) are essentially unclear. PATIENTS AND METHODS 587 sera from patients with chronic inflammatory bowel diseases, inflammatory hepatobiliary diseases, primary systemic vasculitides and other rheumatological diseases were examined for BPI-ANCA by mono-specific ELISA and a standard indirect immunofluorescence test for ANCA. (ACD-CPR versus S-CPR). The treatment groups were similar with respect to age, sex, time interval from collapse to CPR, defibrillation and first epinephrine medication. There was no difference between the ACD group and the standard CPR group in terms of survival rates and neurologic outcome. No differences occurred concerning complications of CPR. CONCLUSION In our two-tiered EMS system with physician-staffed ambulances ACD-CPR neither improved nor impaired the survival rates and the neurological prognosis in patients with out-of-hospital cardiac arrest. Our results are in accordance with other studies carried out in EMS systems, with first tier call-response intervals between 4 and 6 min. RESULTS The prevalence of BPI-ANCA was 43% in ulcerative colitis, 23% in Crohns disease, 35% in primary sclerosing cholangitis, 25% in primary biliary cirrhosis and 29% in autoimmune hepatitides. In a spectrum of systemic vasculitides, inflammatory joint diseases and collagen vascular diseases the prevalence was only 3 to 11%. In contrast to PR3-ANCA and MPO-ANCA, BPI-ANCA was not associated with a particular pattern of fluorescence in the immuno-fluorescence test on ethanol- and formalin-fixed neutrophils. CONCLUSION This study shows that BPI-ANCA is the third ANCA specificity, besides PR3-ANCA and MPO-ANCA, with a limited spectrum of clinical associations. The diagnostic and prognostic relevance of BPI-ANCA in the above clinical conditions is being examined prospectively.