Laboratorio de Citometría de Flujo, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
Área de Fisiopatología, Departamento de Patología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
Cytokine. 2019 Sep;121:154732. doi: 10.1016/j.cyto.2019.05.019. Epub 2019 May 30.
The inflammatory response of the host to Shiga toxin and/or lipopolysaccharide (LPS) of Escherichia coli (E. coli) is included in (HUS). The TLR4-LPS complex is internalized and TLR4 induced inflammatory signaling is stopped by targeting the complex for degradation. Rab7b, a small guanosine triphosphatase (GTPase) expressed in monocytes, regulates the later stages of the endocytic pathway.
we studied the Rab7b participation on the TLR4 endocytic pathway and its effect on monocyte cytokine production along the acute course of pediatric Shiga toxin-associated HUS.
Monocytes were identified according to their positivity in CD14 expression. Surface TLR4 expression in monocytes from 18 HUS patients significantly increased by day 1 to 6, showing the highest increase on day 4 compared to monocytes of 10 healthy children. Significant higher surface TLR4 expression was accompanied by increased proinflammatory intracellular cytokines, tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). In contrast, after these time points, surface TLR4 expression and intracellular TNF-α levels, returned to near control levels after 10 days. Furthermore, confocal immunofluorescence microscopy proved colocalization of increased intracellular TLR4/Rab7b determined by Pearson's coefficient in monocytes from HUS patients from day 1 on the highest colocalization of both proteins by day 4. Decreased TLR4/Rab7b colocalization was shown 10 days after HUS onset.
The colocalization of TLR4 and Rab7b allows us to suggest Rab7b participation in the control of the TLR4 endocytic pathway in HUS patient monocytes. A consequential fall in cytokine production throughout the early follow up of HUS is demonstrated.
宿主对大肠杆菌（E. coli）志贺毒素和/或脂多糖（LPS）的炎症反应包括在（HUS）中。TLR4-LPS 复合物被内化，通过靶向复合物进行降解来阻止 TLR4 诱导的炎症信号。Rab7b 是一种在单核细胞中表达的小 G 三磷酸酶（GTPase），调节内吞途径的后期阶段。
我们研究了 Rab7b 对 TLR4 内吞途径的参与及其对单核细胞细胞因子产生的影响，以研究儿科志贺毒素相关性 HUS 的急性病程。
根据 CD14 表达的阳性，鉴定单核细胞。18 例 HUS 患者的单核细胞表面 TLR4 表达在第 1 天至第 6 天显著增加，与 10 名健康儿童的单核细胞相比，第 4 天的增加最为显著。表面 TLR4 表达增加伴随着促炎细胞内细胞因子肿瘤坏死因子-α（TNF-α）和白细胞介素 6（IL-6）的增加。相比之下，在这些时间点之后，表面 TLR4 表达和细胞内 TNF-α 水平在 10 天后恢复到接近对照水平。此外，共聚焦免疫荧光显微镜证实了 HUS 患者单核细胞中 TLR4/Rab7b 表达的增加，通过 Pearson 系数确定，在第 1 天就可以观察到两者之间的高度共定位，到第 4 天两者之间的共定位达到最高。在 HUS 发病后 10 天观察到 TLR4/Rab7b 共定位减少。
TLR4 和 Rab7b 的共定位使我们能够推测 Rab7b 参与 HUS 患者单核细胞 TLR4 内吞途径的控制。在 HUS 的早期随访过程中，细胞因子产生的减少得到了证明。
