Differential Regulation of Chemokine Secretion in Tuberculous and Staphylococcal Osteomyelitis
作者:Kathleen M. Wright、Jon S. Friedland
DOI:10.1359/jbmr.2002.17.9.1680
日期:——
Bone infection or osteomyelitis is characterized by uncontrolled inflammation and destructive bone loss although little is known about immunopathogenesis of infection. We investigated control of chemokine secretion from osteoblasts infected with either Mycobacterium tuberculosis, which normally elicits a granulomatous host response, or Staphylococcus aureus, which drives a host response dominated by neutrophil influx. We show that M. tuberculosis infection of cultured and primary osteoblasts induces extensive secretion of the chemokines interleukin (IL)‐8, inducible protein (IP) 10, RANTES, and monocyte chemoattractant protein (MCP) 1 within 72 h (1630 ± 280 pg/ml per 4 × 105 cells, 74,130 ± 8480 pg/ml per 4 × 105 cells, 18,330 ± 3040 pg/ml per 4 × 105 cells, and 13,8670 ± 13,340 pg/ml per 4 × 105 cells, respectively, for MG‐63 osteoblasts). S. aureus infection also results in secretion of these chemokines but secretion is delayed and of lesser magnitude (210 ± 10 pg/ml per 4 × 105 cells, 11,570 ± 1240 pg/ml per 4 × 105 cells, 930 ± 34 pg/ml per 4 × 105 cells, and 13,770 ± 720 pg/ml per 4 × 105 cells for IL‐8, IP‐10, RANTES, and MCP‐1, respectively). The minimal up‐regulation of secretion of the neutrophil attractant IL‐8 in staphylococcal infection is both striking and unexpected. In both infections, chemokine secretion was dependent on the presence of live organisms. Differences in kinetics and magnitude of chemokine secretion are associated with distinct patterns of mRNA expression, as assessed by ribonuclease protection assay (RPA) and reverse‐transcription polymerase chain reaction (RT‐PCR). In addition, nuclear localization of the transcription factor activator protein (AP) 1 in M. tuberculosis‐infected osteoblasts also is distinct as compared with S. aureus‐infected cells. In summary, this study shows that osteoblasts have an important pathogen‐specific role in control of chemokine gene expression and secretion during the human immune response to osteomyelitis.
骨感染或骨髓炎的特征是不受控制的炎症和破坏性骨质流失,但人们对感染的免疫发病机制知之甚少。我们研究了结核分枝杆菌或金黄色葡萄球菌感染成骨细胞后趋化因子分泌的控制,结核分枝杆菌通常会引起肉芽肿宿主反应,而金黄色葡萄球菌则会引起以中性粒细胞流入为主的宿主反应。我们发现,M.结核杆菌感染培养成骨细胞和原代成骨细胞会在 72 小时内诱导白细胞介素(IL)-8、诱导蛋白(IP)10、RANTES 和单核细胞趋化蛋白(MCP)1 的大量分泌(1630 ± 280 pg/ml per 4 × 105 cells、对于 MG-63 成骨细胞,分别为每 4 × 105 个细胞 74,130 ± 8480 pg/ml、每 4 × 105 个细胞 18,330 ± 3040 pg/ml 和每 4 × 105 个细胞 13,8670 ± 13,340 pg/ml)。金黄色葡萄球菌感染也会导致这些趋化因子的分泌,但分泌会延迟,且分泌量较少(IL-8、IP-10、RANTES 和 MCP-1 的分泌量分别为每 4 × 105 个细胞 210 ± 10 pg/ml、每 4 × 105 个细胞 11,570 ± 1240 pg/ml、每 4 × 105 个细胞 930 ± 34 pg/ml 和每 4 × 105 个细胞 13,770 ± 720 pg/ml)。在葡萄球菌感染中,中性粒细胞吸引因子 IL-8 的分泌上调幅度极小,这既令人震惊又出乎意料。在这两种感染中,趋化因子的分泌都依赖于活生物体的存在。通过核糖核酸酶保护试验(RPA)和反转录聚合酶链反应(RT-PCR)评估,趋化因子分泌动力学和幅度的差异与不同的 mRNA 表达模式有关。此外,与金黄色葡萄球菌感染的细胞相比,转录因子激活蛋白(AP)1 在结核杆菌感染的成骨细胞中的核定位也有所不同。总之,本研究表明,在人类对骨髓炎的免疫反应过程中,成骨细胞在控制趋化因子基因表达和分泌方面具有重要的病原体特异性作用。