Mitchell T S, Moots R J, Wright H L
Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK.
Institute of Integrative Biology, University of Liverpool, Liverpool, UK.
Clin Exp Immunol. 2017 Aug;189(2):250-258. doi: 10.1111/cei.12970. Epub 2017 Apr 20.
Neutrophils play a crucial role in the pathophysiology of rheumatoid arthritis (RA) via the release of reactive oxygen species (ROS), proteases and cytokines. Orally active Janus kinase (JAK) inhibitors (JAKi), e.g. baricitinib and tofacitinib, have high clinical efficacy in RA but are linked with neutropenia and increased infections. Our aim was to determine the effect of JAK inhibition with baricitinib and tofacitinib on healthy control and RA neutrophil lifespan and function. RA (n = 7) and healthy control (n = 7) neutrophils were treated with baricitinib or tofacitinib for 30 min, prior to incubation in the absence or presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) or interferon (IFN)-γ. JAKi prevented GM-CSF- and IFN-γ-induced apoptosis delay in RA and healthy control neutrophils in a dose-dependent manner. Baricitinib decreased the rate of chemotaxis towards interleukin (IL)-8, but not f-Met-Leu-Phe (fMLP) in RA neutrophils. While healthy control neutrophils incubated with GM-CSF became primed to produce ROS in response to stimulation with fMLP and phorbol-12-myristate-12-acetate (PMA), RA neutrophils produced increased levels of ROS without the need for priming. JAKi prevented ROS release from primed healthy control neutrophils in response to fMLP, but had no effect on ROS production by RA neutrophils. Baricitinib reversed GM-CSF priming of ROS production in response to fMLP in healthy control, but not RA, neutrophils. We conclude that incubation with JAKi prevents chemotaxis of RA neutrophils towards IL-8, but does not prevent the production of ROS or increase the level of apoptosis. This may be due to the in-vivo exposure of RA neutrophils to priming agents other than those that activate JAK/signal transducer and activator of transcription (STAT) signalling.
中性粒细胞通过释放活性氧(ROS)、蛋白酶和细胞因子在类风湿关节炎(RA)的病理生理学中发挥关键作用。口服活性Janus激酶(JAK)抑制剂(JAKi),如巴瑞替尼和托法替布,在RA中具有较高的临床疗效,但与中性粒细胞减少和感染增加有关。我们的目的是确定巴瑞替尼和托法替布抑制JAK对健康对照者和RA中性粒细胞寿命及功能的影响。在不存在或存在粒细胞-巨噬细胞集落刺激因子(GM-CSF)或干扰素(IFN)-γ的情况下孵育之前,将RA(n = 7)和健康对照者(n = 7)的中性粒细胞用巴瑞替尼或托法替布处理30分钟。JAKi以剂量依赖的方式阻止GM-CSF和IFN-γ诱导的RA和健康对照者中性粒细胞凋亡延迟。巴瑞替尼降低了RA中性粒细胞对白介素(IL)-8的趋化速率,但对f-甲硫氨酰-亮氨酰-苯丙氨酸(fMLP)的趋化速率没有影响。虽然与GM-CSF一起孵育的健康对照者中性粒细胞在受到fMLP和佛波醇-12-肉豆蔻酸酯-13-乙酸酯(PMA)刺激时会被激活以产生活性氧,但RA中性粒细胞无需激活即可产生活性氧水平增加。JAKi可阻止激活的健康对照者中性粒细胞因fMLP而释放活性氧,但对RA中性粒细胞产生活性氧没有影响。巴瑞替尼可逆转GM-CSF对健康对照者(而非RA)中性粒细胞因fMLP而产生活性氧的激活作用。我们得出结论,与JAKi一起孵育可阻止RA中性粒细胞对IL-8的趋化,但不会阻止活性氧的产生或增加细胞凋亡水平。这可能是由于RA中性粒细胞在体内暴露于除激活JAK/信号转导子和转录激活子(STAT)信号通路的物质之外的其他激活剂。