Neutrophils are key players in the pathophysiological process underlying inflammatory conditions not only by release of tissue-damaging cytotoxic enzymes, reactive oxygen species (ROS) but also by secretion of important immunomodulatory chemokines and cytokines. Here, we report the effects of the novel agent APPA, undergoing formal clinical development for treatment of osteoarthritis, and its constituent components, apocynin (AP) and paeonol (PA) on a number of neutrophil functions, including effects on TNFα- expression and signalling. Neutrophils were treated with APPA (10-1000 µg/mL) prior to the measurement of cell functions, including ROS production, chemotaxis, apoptosis and surface receptor expression. Expression levels of several key genes and proteins were measured after incubation with APPA and the chromatin re-modelling agent, R848. APPA did not significantly affect phagocytosis, bacterial killing or expression of surface receptors, while chemotactic migration was affected only at the highest concentrations. However, APPA down-regulated neutrophil degranulation and ROS levels, and decreased the formation of neutrophil extracellular traps. APPA also decreased cytokine-stimulated gene expression, inhibiting both TNFα- and GM-CSF-induced cell signalling. APPA was as effective as infliximab in down-regulating chemokine and IL-6 expression following incubation with R848. Whilst APPA does not interfere with neutrophil host defence against infections, it does inhibit neutrophil degranulation, and cytokine-driven signalling pathways (e.g. autocrine signalling and NF-κB activation), processes that are associated with inflammation. These observations may explain the mechanisms by which APPA exerts anti-inflammatory effects and suggests a potential therapeutic role in inflammatory diseases in which neutrophils and TNFα signalling are important in pathology, such as rheumatoid arthritis.

中文翻译：

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APPA（夹竹桃麻素和丹皮酚）可调节人中性粒细胞功能的病理学方面，而不抑制抗菌能力，并抑制 TNFα 表达和信号传导。


中性粒细胞是炎症病理生理过程中的关键参与者，不仅通过释放组织损伤性细胞毒性酶、活性氧 (ROS)，还通过分泌重要的免疫调节趋化因子和细胞因子。在这里，我们报告了新药 APPA（正在进行正式临床开发，用于治疗骨关节炎）及其成分夹竹桃麻素 (AP) 和丹皮酚 (PA) 对许多中性粒细胞功能的影响，包括对 TNFα 表达和信号传导的影响。在测量细胞功能（包括 ROS 产生、趋化性、细胞凋亡和表面受体表达）之前，用 APPA (10-1000 µg/mL) 处理中性粒细胞。与 APPA 和染色质重塑剂 R848 孵育后，测量了几个关键基因和蛋白质的表达水平。 APPA 不会显着影响吞噬作用、细菌杀灭或表面受体的表达，而趋化迁移仅在最高浓度时受到影响。然而，APPA 下调中性粒细胞脱颗粒和 ROS 水平，并减少中性粒细胞胞外陷阱的形成。 APPA 还降低细胞因子刺激的基因表达，抑制 TNFα 和 GM-CSF 诱导的细胞信号传导。与 R848 孵育后，APPA 在下调趋化因子和 IL-6 表达方面与英夫利昔单抗一样有效。虽然 APPA 不会干扰中性粒细胞宿主对感染的防御，但它确实会抑制中性粒细胞脱粒和细胞因子驱动的信号传导途径（例如自分泌信号传导和 NF-κB 激活）以及与炎症相关的过程。 这些观察结果可能解释了 APPA 发挥抗炎作用的机制，并提示其在炎症性疾病（如类风湿性关节炎）中具有潜在的治疗作用，其中中性粒细胞和 TNFα 信号传导在病理学中很重要。