Puliti Manuela, von Hunolstein Christina, Bistoni Francesco, Castronari Roberto, Orefici Graziella, Tissi Luciana
Microbiology Section, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Via del Giochetto, 06122 Perugia, Italy.
Cell Microbiol. 2002 Oct;4(10):691-700. doi: 10.1046/j.1462-5822.2002.00223.x.
Septic arthritis is a clinical manifestation of group B Streptococcus (GBS) infection in both neonates and adults. Because macrophages are known to participate in tissue injury, the role of this cell population in GBS-induced arthritis was investigated. Mice were rendered monocytopenic by administration of etoposide, a drug that selectively depletes the monocyte/macrophage population and then injected with GBS (1 x 10(7) colony-forming units per mouse). Appearance of arthritis, mortality, GBS growth in the organs, and local and systemic cytokine production were examined. Etoposide-treated mice had a significantly less severe arthritis than control animals. Histopathological analysis of the joints confirmed clinical observations. Decreased joint levels of the proinflammatory cytokines interleukin 1 (IL-1) beta and IL-6 accompanied the less severe development of arthritis in monocytopenic mice. In contrast, mortality was increased in the etoposide-treated mice compared with controls. Monocytopenic mice exhibited elevated bacterial load in the blood and kidneys at all time points examined. These results indicate that lack of macrophages leads to less severe joint lesions, but also results in impaired clearance of bacteria, and consequent enhancement of mortality rates.
脓毒性关节炎是新生儿和成人B族链球菌（GBS）感染的一种临床表现。由于已知巨噬细胞参与组织损伤，因此研究了该细胞群在GBS诱导的关节炎中的作用。通过给予依托泊苷使小鼠单核细胞减少，依托泊苷是一种能选择性消耗单核细胞/巨噬细胞群的药物，然后给小鼠注射GBS（每只小鼠1×10⁷ 菌落形成单位）。检查关节炎的出现、死亡率、GBS在器官中的生长以及局部和全身细胞因子的产生。与对照动物相比，接受依托泊苷治疗的小鼠关节炎严重程度明显较低。关节的组织病理学分析证实了临床观察结果。在单核细胞减少的小鼠中，促炎细胞因子白细胞介素1（IL-1）β和IL-6的关节水平降低，同时关节炎的发展程度较轻。相比之下，与对照组相比，接受依托泊苷治疗的小鼠死亡率增加。在所有检查时间点，单核细胞减少的小鼠血液和肾脏中的细菌载量均升高。这些结果表明，巨噬细胞的缺乏导致关节损伤较轻，但也会导致细菌清除受损，从而提高死亡率。
