Stimulus-response coupling in monocytes infected with Leishmania. Attenuation of calcium transients is related to defective agonist-induced accumulation of inositol phosphates.
Stimulus-response coupling in monocytes infected with Leishmania. Attenuation of calcium transients is related to defective agonist-induced accumulation of inositol phosphates.
复制标题
感染利什曼原虫的单核细胞中的刺激-反应耦合。
DOI：
10.4049/jimmunol.148.4.1188
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发表时间：
1992
影响因子：
4.4
通讯作者：
N. Reiner
中科院分区：
文献类型：
--
作者：
Martin Olivier;K. Baimbridge;N. Reiner
已证明感染利什曼原虫的单核吞噬细胞对细胞外刺激的反应有缺陷。为了研究这些发现与钙依赖性信号通路改变的潜在关系，在感染杜氏利什曼原虫无鞭毛体的人外周血单核细胞中检查了[Ca 2 +]i浓度的调节。通过显微荧光法在单细胞水平上测量负载Fura-2的单核细胞中的[Ca 2 +]i。在正常单核细胞中，静息[Ca 2 +]i为56 +/- 2 nM（平均值+/- SEM）。相比之下，在利什曼原虫感染的单核细胞中，基础[Ca 2 +]i增加约两倍（122 +/- 5 nM，p小于0.01 vs对照）。在感染前用百日咳毒素处理细胞不能消除感染诱导的基础[Ca 2 +]i的增加，这表明这种作用不是通过激活与磷脂酶C偶联的G蛋白介导的。然而，升高的静息[Ca 2 +]i确实与感染单核细胞的45 Ca 2+摄取速率增加相关。正如预期的那样，在对10（-7）M FMLP处理的响应中，对照单核细胞显示[Ca 2 +]i快速净增加303 +/- 19 nM。相比之下，受感染的单核细胞中响应于FMLP的[Ca 2 +]i的净瞬变减弱至仅137 +/- 9 nM（p小于0.01 vs对照）。该结果与感染细胞中[Ca 2 +]i的过度缓冲无关，因为对照和感染的单核细胞均显示响应钙离子载体A23187的[Ca 2 +]i的等效瞬变。相反，抑制激动剂诱导的钙释放在感染的细胞似乎与缺陷的第二信使的产生，因为与对照细胞标记的肌-[2- 3 H]肌醇，肌醇1，4，5-三磷酸很少积累被检测到感染的单核细胞。趋化肽引起的磷酸肌醇积累和钙释放的减弱与受感染单核细胞FMLP诱导的超氧化物和过氧化氢产生减少相关。这些结果为利什曼原虫感染的单核细胞中[Ca 2 +]i和钙依赖性信号传导的调节缺陷提供了直接证据，并为理解激活相关反应（涉及通过Ca（2+）调节途径的信号传导）中的异常提供了基础。
Mononuclear phagocytes infected with Leishmania have been shown to have defective responses to extracellular stimuli. To investigate the potential relationship of these findings to alterations in calcium-dependent signaling pathways, the regulation of [Ca2+]i concentrations was examined in human peripheral blood monocytes infected with amastigotes of Leishmania donovani. Measurements of [Ca2+]i in fura-2-loaded monocytes were made at the single cell level by microfluorimetry. In normal monocytes, resting [Ca2+]i was 56 +/- 2 nM (mean +/- SEM). In contrast, in monocytes infected with Leishmania there was an approximately twofold increase in basal [Ca2+]i (122 +/- 5 nM, p less than 0.01 vs control). Treatment of cells with pertussis toxin before infection did not abrogate infection-induced increases in basal [Ca2+]i, suggesting that this effect was not mediated via the activation of a G protein coupled to phospholipase C. However, elevated resting [Ca2+]i did correlate with increased rates of 45Ca2+ uptake by infected monocytes. As expected, in response to treatment with 10(-7) M FMLP, control monocytes showed rapid net increases in [Ca2+]i of 303 +/- 19 nM. In contrast, net transients of [Ca2+]i in infected monocytes in response to FMLP were attenuated to only 137 +/- 9 nM (p less than 0.01 vs control). This result was not related to excess buffering of [Ca2+]i in infected cells as both control and infected monocytes showed equivalent transients of [Ca2+]i in response to the calcium ionophore A23187. Rather, inhibition of agonist-induced calcium release in infected cells appeared related to defective generation of second messenger because compared to control cells labeled with myo-[2-3H]inositol, little accumulation of inositol 1,4,5-trisphosphate was detected in infected monocytes. Attenuation of inositol phosphate accumulation and calcium release in response to chemotactic peptide correlated with decreased FMLP-induced superoxide and hydrogen peroxide production by infected monocytes. These results provide direct evidence for defective regulation of [Ca2+]i and calcium-dependent signaling in Leishmania-infected monocytes and provide a basis for understanding abnormalities in activation-related responses that involve signaling through Ca(2+)-regulated pathways.