RESUMEN
The bactericidal/permeability-increasing protein (BPI) is an endotoxin-binding neutrophil leukocyte-granule protein with antibacterial and anti-endotoxin properties. A recombinant form of BPI (rBPI21) has been developed and is being tested as a therapeutic agent to treat gram-negative bacterial infections and exposure to gram-negative bacterial endotoxin. BPI is also a target antigen of anti-neutrophil cytoplasmic autoantibodies (ANCA). BPI-ANCA are present in cystic fibrosis, inflammatory bowel disease, vasculitis, and primary sclerosing cholangitis; presence of BPI-ANCA appears associated with a higher inflammatory disease activity and greater organ damage. BPI-ANCA as well as ANCA directed at other neutrophil-granule proteins may exacerbate inflammation by nonspecific effects of extracellular and cell-associated immune complexes. BPI-ANCA may further worsen inflammation by reducing the ability of BPI to promote clearance of gram-negative bacteria and bacterial-associated endotoxin.
Asunto(s)
Anticuerpos Anticitoplasma de Neutrófilos/inmunología , Autoantígenos/inmunología , Proteínas Sanguíneas/inmunología , Proteínas de la Membrana , Adulto , Animales , Especificidad de Anticuerpos , Péptidos Catiónicos Antimicrobianos , Enfermedades Autoinmunes/inmunología , Proteínas Sanguíneas/química , Niño , Preescolar , Ensayos Clínicos Fase I como Asunto , Ensayos Clínicos Fase II como Asunto , Citocinas/metabolismo , Gránulos Citoplasmáticos/química , Evaluación Preclínica de Medicamentos , Endotoxinas/metabolismo , Eosinófilos/metabolismo , Predicción , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Humanos , Lactante , Inflamación/inmunología , Ratones , Estudios Multicéntricos como Asunto , Neutrófilos/metabolismo , Ensayos Clínicos Controlados Aleatorios como Asunto , Proteínas Recombinantes de Fusión/inmunología , Proteínas Recombinantes de Fusión/uso terapéutico , Vasculitis/inmunologíaRESUMEN
A procedure is described for purification of the primary bactericidal component of normal rabbit serum active in vitro against Bacillus subtilis. A 65 000-fold increase in specific bactericidal activity per milligram of serum protein was obtained, yielding a low molecular weight, heat-stable polypeptide fraction (PC-III) exhibiting biological activity at protein concentrations below 10 ng/mL. This preparation appeared homogeneous as judged by column chromatography and analytical NaDodSO4-polyacrylamide gel eletrophoresis; recovery of serum bactericidal activity was routinely greater than 80%. Analysis of dansylated or 125I-labeled samples in peptide-resolving polyacrylamide gels revealed a single band with an Mr of 1800. Optimal antibacterial activity of PC-III against B. subtilis occurred at an ionic strength of 0.24 and was absolutely dependent upon divalent cations; calcium was the most effective. Under optimum conditions, 4 ng/mL of PC-III reduced the viability of B. subtilis test innocula by 90% within 10 min at 37 degrees C. Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium were all sensitive to the action of PC-III, but higher bactericide concentrations were required to produce similar reductions in viability as observed with B. subtilis. All strains were killed by PC-III concentrations well below 1 microgram/mL, roughly that found in normal serum. The activity of PC-III preparations was significantly reduced by pretreatment with trypsin or proteinase K but not by neuraminidase or periodate.