Schultz Hendrik, Schinke Susanne, Mosler Katharina, Herlyn Karen, Schuster Antje, Gross Wolfgang L
Department of Rheumatology, University of Lübeck, Lübeck, Germany.
Pediatr Pulmonol. 2004 Feb;37(2):158-64. doi: 10.1002/ppul.10416.
Gram-negative bacterial lung infections and chronic bacterial colonization are major threats for pediatric cystic fibrosis (CF) patients. Besides impeded mucociliary clearance, other mechanisms that contribute to increased susceptibility to infections are presumed. The bactericidal/permeability-increasing protein (BPI), which is delivered by neutrophil granulocytes and mucosal epithelial cells, is one of the most potent innate antibiotics against Gram-negative bacteria and endotoxin. Antineutrophil cytoplasmic autoantibodies against BPI (BPI-ANCA) have been found in up to 90% of CF patients, and titers correlated inversely with lung function parameters. As major pulmonary damage is mediated by Gram-negative bacteria and their products, the question was raised as to whether BPI-ANCA can inhibit the antibiotic function of BPI in these patients. Sera of 23 pediatric CF patients were analyzed for the presence of BPI-ANCA by indirect immunofluorescence, ELISA, epitope mapping, and Western blotting. Patients' IgG were tested in a bacterial growth inhibition assay with recombinant BPI (rBPI) and an amino-terminal fragment of BPI (rBPI(21)) that retains antibiotic activity for inhibition of the antibiotic function of BPI against E. coli DH5alpha in vitro. BPI was recognized by 21 of 23 patients' sera in our detection assays. Thirteen of 23 patients' BPI-ANCA (56%) could inhibit the antibiotic function in vitro. Moreover, epitope mapping over the whole BPI sequence revealed that more patients' BPI-ANCA recognize the amino-terminal part of BPI than can be detected by ELISA. Thus, in pediatric CF patients, BPI-ANCA may contribute to diminished bacterial clearance by inhibiting the antibiotic function of BPI.
革兰氏阴性菌肺部感染和慢性细菌定植是小儿囊性纤维化（CF）患者面临的主要威胁。除了黏液纤毛清除功能受阻外，推测还有其他机制导致患者对感染的易感性增加。由中性粒细胞和黏膜上皮细胞产生的杀菌/通透性增加蛋白（BPI）是对抗革兰氏阴性菌和内毒素最有效的天然抗生素之一。在高达90%的CF患者中发现了抗BPI的抗中性粒细胞胞浆自身抗体（BPI-ANCA），其滴度与肺功能参数呈负相关。由于主要的肺部损伤是由革兰氏阴性菌及其产物介导的，因此有人提出疑问，BPI-ANCA是否会抑制这些患者中BPI的抗生素功能。通过间接免疫荧光、酶联免疫吸附测定（ELISA）、表位作图和蛋白质印迹法，对23例小儿CF患者的血清进行分析，以检测BPI-ANCA的存在。在体外细菌生长抑制试验中，用重组BPI（rBPI）和保留抗生素活性的BPI氨基末端片段（rBPI(21)）检测患者的IgG，以抑制BPI对大肠杆菌DH5α的抗生素功能。在我们的检测试验中，23例患者的血清中有21例识别出BPI。23例患者中的13例（56%）BPI-ANCA在体外可抑制抗生素功能。此外，对整个BPI序列进行表位作图显示，与ELISA检测相比，更多患者的BPI-ANCA识别BPI的氨基末端部分。因此，在小儿CF患者中，BPI-ANCA可能通过抑制BPI的抗生素功能导致细菌清除减少。
