Application of intracellular alkaline phosphatase activity measurement in detection of neutrophil adherence in vitro

Cerium(iii)-directed assembly of glutathione-capped gold nanoclusters for sensing and imaging of alkaline phosphatase-mediated hydrolysis of adenosine triphosphate

Aggregation-induced emission enhancement (AIEE) of thiolated gold nanoclusters (AuNCs) has emerged as an attractive and alternative strategy to improve their brightness. This study demonstrates Ce(iii)-triggered AIEE of glutathione-capped AuNCs (GSH-AuNCs) through the coordination between two carboxylic groups of GSH and Ce(iii). The cluster size and valence state of GSH-AuNCs are almost identical to those of a Ce(iii)-induced assembly of GSH-AuNCs (named Ce(iii)-GSH-AuNCs). More importantly, the as-prepared Ce(iii)-GSH-AuNCs exhibit a higher quantum yield (up to 13%), longer luminescence lifetime, and shorter maximum luminescence peak than GSH-AuNCs. Additionally, Ce(iii)-GSH-AuNCs possess redox-switchable luminescence, high salt stability, and long-term storage stability. These findings provide clear evidence that the Ce(iii)-triggered aggregation of GSH-AuNCs is a crucial factor to improve the luminescence property of GSH-AuNCs. Intriguingly, the presence of adenosine triphosphate (ATP) switches off the luminescence of Ce(iii)-GSH AuNCs through the significant formation of Ce(iii)-ATP complexes. Furthermore, the ATP-induced luminescence quenching of Ce(iii)-GSH-AuNCs can be paired with the alkaline phosphatase (ALP)-ATP system to design a turn-on luminescent probe for ALP; the limit of detection for ALP is estimated to be 0.03 U L-1. Also, the biocompatibility of Ce(iii)-GSH-AuNCs enables the proposed system to detect ALP in human serum and HeLa cells.

[Effects of neutrophils alkaline phosphatase on functions of neutrophils in vitro]

目的

探讨中性粒细胞碱性磷酸酶（neutrophils alkaline phosphatase, NAP）对中性粒细胞迁移、活性氧（ROS）生成以及凋亡的影响。

方法

通过慢病毒感染人早幼粒细胞白血病细胞株HL-60获得NAP高表达细胞株，采用RT-PCR和Western blot技术分别检测感染后细胞NAP的基因转录及蛋白表达水平。HL-60细胞经1.5% DMSO体外诱导分化为类中性粒细胞后进行相关实验：分别利用Transwell迁移实验和流式细胞术检测高表达NAP中性粒细胞的迁移及ROS生成能力；流式细胞术检测细胞凋亡；Western blot法检测高表达NAP中性粒细胞中凋亡相关蛋白Bax、caspase-3和caspase-9的表达情况。

结果

经慢病毒感染的HL-60细胞通过嘌呤霉素筛选后80％以上细胞可见绿色荧光，且NAP在基因及蛋白水平表达均明显升高。HL-60细胞经1.5% DMSO体外诱导分化5 d后，细胞体积变小、表面出现许多突起，核质比例降低，核仁消失，核染色质由密集趋向疏松，细胞核扭曲折叠呈杆状或分叶，CD11b⁺细胞百分比明显升高。Transwell迁移实验结果显示，高表达NAP的中性粒细胞迁移细胞数多于阴性对照组[（15.30±3.65）×10³对（8.00±0.78）×10³，P<0.001]。流式细胞术检测结果表明，高表达NAP的中性粒细胞胞内ROS的平均荧光强度高于阴性对照组（355.70±20.10对103.22±4.71，P<0.001）；与阴性对照组比较，高表达NAP中性粒细胞胞凋亡率及凋亡相关蛋白Bax、active-caspase-3以及active-caspase-9的表达水平明显上调。

结论

NAP具有促进类中性粒细胞迁移及ROS生成、加速细胞凋亡的生物学作用。

Seasonal changes in activities of human neutrophils in vitro

Objective and design

We present a retrospective analysis of previously collected blood samples to determine whether the immune response of neutrophils depends on the season i.e., short versus long days, in which blood samples were collected.

Methods

The bactericidal activity and adhesive capacity of neutrophils, the production of reactive oxygen species (ROS), and CD11b/CD18 molecule expression level were investigated. The investigated neutrophils were divided into two groups based on the time of blood collection: the winter season with short days and the summer season with long days.

Results

We found seasonal variation in measurements of all the analyzed functional responses of neutrophils to stimuli. The strongest adhesion, as well as maximum values of ROS production, was presented by neutrophils isolated from the summer group. The highest bactericidal activity of neutrophils was also observed in blood donors from summer group.

Conclusions

The magnitude of the immune functional activity of neutrophils varies with the season of the year and is decreased in winter.

Extracellular ATP and P2 receptors are required for IL-8 to induce neutrophil migration

The chemokine interleukin 8 (IL-8) is a major chemoattractant for human neutrophils. Here, we demonstrate novel evidence that IL-8-induced neutrophil chemotaxis requires a concurrent activation of P2 receptors, most likely the P2Y(2) which is dominantly expressed in these cells. Indeed, the migration of human neutrophils towards IL-8 was significantly inhibited by the P2Y receptor antagonists, suramin and reactive blue 2 (RB-2) and potentiated by a P2Y(2) ligand, ATP, but insensitive to specific antagonists of P2Y(1), P2Y(6) and P2Y(11) receptors. Adenosine had no effect on neutrophil migration towards IL-8 which contrasted with the stimulatory effect of this molecule on neutrophil chemotaxis caused by formyl-Met-Leu-Phe (fMLP or fMLF). Taken together, these data suggest that extracellular ATP is necessary for IL-8 to exert its chemotactic effect on neutrophils.