[The role of neutrophil density in neutrophils-mediated inflammatory response induced by monosodium urate crystals].

Objective: To study the role of neutrophil density and molecular mechanism in neutrophils-mediated inflammatory response induced by monosodium urate (MSU) crystals. Methods: Polymorphonuclear neutrophils (PMNs) isolated from healthy human peripheral blood were treated with MSU crystals at different density (5×10(6)/ml, 20×10(6)/ml, 100×10(6)/ml) in vitro. The mean fluorescence intensity (MFI) of PMNs and production of reactive oxygen species (ROS) were detected by flow cytometry. The distribution of MSU crystals was observed by polarized light microscopy. The neutrophil extracellular traps (NETs) formation was detected by immune fluorescence. The cytokines in cell supernatant were measured by beads assay including interleukin 1β (IL-1β) , tumor necrosis factor α (TNFα) , interleukin 8 (IL-8) , interferon inducible protein 10 (IP-10) , macrophage inflammatory protein 1 (MIP-1) , monokine induced by interferon-γ (MIG) , macrophage inflammatory protein 1α (MIP-1α) , macrophage inflammatory protein 1β (MIP-1β) . Results: (1) After MSU crystal intervention, the side scatters (SSC) of neutrophils with medium-cell density (20×10(6)/ml) and high-cell density (100×10(6)/ml) were 128±13 and 93±9 respectively, both significantly lower than 170±19 in low-cell density (5×10(6)/ml) group.(2) Similarly, compared with low-cell density group, the MFI (lucifer yellow) of PMNs with high-cell density was 1.8±0.2, also significantly decreased (P<0.05). When co-treated with oxygenated adenosine triphosphate (oxATP), MFI of PMNs were all enhanced consistently. (3) In MSU crystals stimulated PMNs, after adding 2',7'-dichlorodihydrofluorescein diacetate, the MFI values were 0.85±0.32, 2.49±0.78, 4.54±1.02 in low cell density groups, medium cell density groups, and high cell density groups respectively, indicating that the generation of ROS was positively correlated with the increase of PMN density (P<0.05). After the intervention of oxATP, the ROS production was significantly reduced. (4) MSU crystal induced NETs formation, especially at high cell density. NETs formation promotes MSU crystal aggregation, which could be partially overcome by oxATP pretreatment. (5) The expression of cytokines were all significantly decreased in the supernatant of PMNs at high cell density exposed to MSU crystals compared with PMNs at medium cell density (P<0.05) . Conclusion: The PMN-mediated inflammation induced by MSU crystals is cell density dependent, and ATP may play a role in partially overcoming the process.目的： 研究中性粒细胞密度对单钠尿酸盐（MSU）晶体诱导中性粒细胞产生炎症反应的影响，初步探讨三磷酸腺苷的参与机制。 方法： 制备MSU晶体，分离健康人外周血中性粒细胞，分别采用MSU晶体刺激不同密度中性粒细胞（5×10(6)/ml为低细胞密度，20×10(6)/ml为中细胞密度，100×10(6)/ml为高细胞密度）后，流式细胞仪检测刺激后细胞荧光强度及活性氧产生，偏振光显微镜观察MSU晶体分布，免疫荧光检测中性粒细胞胞外陷阱（NETs）的形成，流式微球检测上清中白细胞介素（IL）-1β、肿瘤坏死因子（TNF）α、IL-8、干扰素诱导蛋白（IP）-10、巨噬细胞炎症蛋白（MIP）-1、干扰素γ诱导单核细胞因子（MIG）、MIP-1α、MIP-1β水平。 结果： （1）低细胞密度下，经MSU晶体干预后，中性粒细胞后侧向散射角（SSC）值为170±19；中细胞密度为128±13；高细胞密度为93±9，较低细胞密度显著降低（P<0.05）。（2）与低细胞密度比，高细胞密度下经MSU晶体干预后中性粒细胞的荧光强度显著降低（1.8±0.2比6.2±0.7，P<0.05）；而使用氧化三磷酸腺苷和MSU晶体干预后，中性粒细胞的荧光强度较单纯MSU晶体干预明显增加（低细胞密度为7.5±0.3，中细胞密度为4.6±0.2，高细胞密度为3.4±0.5，P<0.05）。（3）经MSU晶体刺激后，加入活性氧荧光探针的中性粒细胞活性氧产生增多，且随着中性粒细胞密度增加，活性氧产生明显增加（荧光强度0.85±0.32比2.49±0.78比4.54±1.02），差异有统计学意义（P<0.05），而加入氧化三磷酸腺苷干预后中性粒细胞活性氧产生显著降低。（4）MSU晶体刺激中性粒细胞后诱导中性粒细胞胞外陷阱形成，高细胞密度下中性粒细胞胞外陷阱形成较多，进而促进MSU晶体聚集，氧化三磷酸腺苷可减少MSU晶体干预后中性粒细胞胞外陷阱形成。（5）高细胞密度下，中性粒细胞经MSU晶体刺激后上清中IL-1β、TNFα、IL-8、MIP-1、MIG、MIP-1α、MIP-1β水平均显著低于中细胞密度（P<0.05）。 结论： MSU晶体刺激中性粒细胞后，对其生物学功能的影响呈细胞密度依赖性，三磷酸腺苷可能在上述过程中发挥作用。.