Harrison Lisa M, Cherla Rama P, van den Hoogen Christel, van Haaften Wilhelmina C E, Lee Sang-Yun, Tesh Vernon L
Department of Medical Microbiology and Immunology, Texas A and M University System Health Science Center, 407 Reynolds Medical Building, College Station, TX 77843-1114, USA.
Microb Pathog. 2005 Feb-Mar;38(2-3):63-76. doi: 10.1016/j.micpath.2004.12.003.
The enteric pathogens Shigella dysenteriae serotype 1 and Shiga toxin-producing Escherichia coli share the property of expressing the structurally and functionally related cytotoxins that comprise the Shiga toxin (Stx) family. Stx-producing bacteria are causative agents of bloody diarrheal diseases that may progress to life threatening complications involving the destruction of blood vessels in the kidneys and the central nervous system (CNS). The precise mechanisms of toxin transport across the gut epithelial barrier, and the role of innate immunity in the development of systemic complications, remain to be fully characterized. Earlier studies suggested that Stxs and lipopolysaccharides (LPS) induce the expression of proinflammatory cytokines from differentiated (macrophage-like) THP-1 cells. These cytokines may exacerbate vascular damage by up-regulating the expression of toxin receptors on endothelial cells. Purified Stxs have also been shown to induce apoptosis of epithelial and endothelial cells in vitro, but a comparative evaluation of Stx-induced apoptosis of monocytes and macrophages has not been reported. We used FACS, TUNEL, and DNA laddering analyses to show that Shiga toxin-1 (Stx1) and LPS induce apoptosis in undifferentiated and differentiated THP-1 cells, although the kinetics and extent of apoptosis induction differ between monocytic and macrophage-like cells. Stx1-induced apoptosis is A-subunit-dependent. Stx1 and LPS trigger DNA fragmentation and caspase-3 activation, as evidenced by the cleavage of poly(ADP-ribose) polymerase (PARP). Induction of apoptosis in response to Stx1 and/or LPS treatment occurs without the widespread transcriptional activation of apoptosis-related genes. Finally, we present a model of the role of macrophages and monocytes in the pathogenesis of disease caused by Stxs.
肠道病原体痢疾志贺氏菌1型和产志贺毒素大肠杆菌具有共同特性，即表达结构和功能相关的细胞毒素，这些毒素构成志贺毒素（Stx）家族。产Stx细菌是血性腹泻疾病的病原体，可能发展为危及生命的并发症，包括肾脏和中枢神经系统（CNS）血管的破坏。毒素穿过肠道上皮屏障的精确机制以及先天免疫在全身并发症发展中的作用仍有待充分阐明。早期研究表明，Stxs和脂多糖（LPS）可诱导分化的（巨噬细胞样）THP-1细胞表达促炎细胞因子。这些细胞因子可能通过上调内皮细胞上毒素受体的表达而加剧血管损伤。纯化的Stxs在体外也已显示可诱导上皮细胞和内皮细胞凋亡，但尚未见关于Stx诱导单核细胞和巨噬细胞凋亡的比较评估报道。我们使用流式细胞术、TUNEL和DNA梯状分析表明，志贺毒素-1（Stx1）和LPS可诱导未分化和分化的THP-1细胞凋亡，尽管单核细胞样细胞和巨噬细胞样细胞之间凋亡诱导的动力学和程度有所不同。Stx1诱导的凋亡依赖于A亚基。Stx1和LPS触发DNA片段化和半胱天冬酶-3激活，聚（ADP-核糖）聚合酶（PARP）的裂解证明了这一点。对Stx1和/或LPS处理的凋亡诱导发生时，凋亡相关基因并未广泛转录激活。最后，我们提出了一个关于巨噬细胞和单核细胞在由Stxs引起的疾病发病机制中作用的模型。
