Sickle Cell Branch, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, United States of America.
Flow Cytometry Core Facility, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, United States of America.
PLoS One. 2019 Dec 23;14(12):e0226583. doi: 10.1371/journal.pone.0226583. eCollection 2019.
Neutrophilia is a feature of sickle cell disease (SCD) that has been consistently correlated with clinical severity and has been shown to remain highly activated even at steady state. In addition to induction of fetal hemoglobin (HbF), hydroxyurea (HU) leads to reduction in neutrophil count and their adhesion properties, which contributes to the clinical efficacy of HU in SCD. Although HU reduces the frequency and severity of acute vaso-occlusive crises (VOCs) and chest syndrome, HU therapy does not abolish these acute clinical events. In this study we investigated whether neutrophils in SCD patients whilst on HU therapy retained features of detrimental pro-inflammatory activity. Freshly isolated neutrophils from SCD patients on HU therapy at steady state and from ethnic-matched healthy controls were evaluated ex vivo for their degranulation response and production of neutrophil extracellular traps (NETs). Unstimulated SCD patient neutrophils already produced NETs within 30 minutes, compared to none for healthy neutrophils, and by 4 hours, these neutrophils produced significantly more NETs than the control neutrophils (P = 0.0079**). Higher numbers of neutrophils from SCD patients also showed higher degree of degranulation-related intracellular features compared to healthy neutrophils, including rough-textured cellular membranes (P = 0.03*), double-positivity for F-Actin and CD63 (P = 0.02*) and re-located CD63 within cytoplasm more efficiently than their healthy counterparts (P = 0.02*). The neutrophils from SCD donors released more myeloperoxidase (P = 0.02*) in the absence of any trigger. Our data showed that neutrophils from patients with SCD at steady state remained active during hydroxyurea treatment and are likely to be able to contribute to the SCD pro-inflammatory environment.
中性粒细胞增多症是镰状细胞病（SCD）的一个特征，它与临床严重程度一直呈正相关，并且在稳定状态下仍保持高度激活。除了诱导胎儿血红蛋白（HbF）外，羟基脲（HU）还导致中性粒细胞计数及其粘附特性减少，这有助于 HU 在 SCD 中的临床疗效。尽管 HU 减少了急性血管阻塞性危象（VOC）和胸部综合征的频率和严重程度，但 HU 治疗并未消除这些急性临床事件。在这项研究中，我们研究了在 HU 治疗下的 SCD 患者的中性粒细胞是否仍保留有害促炎活性的特征。在稳定状态下接受 HU 治疗的 SCD 患者和来自同种族匹配的健康对照者的新鲜分离的中性粒细胞，在体外评估其脱颗粒反应和产生中性粒细胞胞外陷阱（NETs）的情况。与健康中性粒细胞相比，HU 治疗下的 SCD 患者的未刺激中性粒细胞在 30 分钟内已经产生了 NETs，而健康中性粒细胞则没有，并且在 4 小时时，这些中性粒细胞产生的 NETs明显多于对照中性粒细胞（P=0.0079**）。与健康中性粒细胞相比，SCD 患者的中性粒细胞数量也显示出更高程度的与脱颗粒相关的细胞内特征，包括粗糙纹理的细胞膜（P=0.03*）、F-肌动蛋白和 CD63 的双重阳性（P=0.02*）以及 CD63 在细胞质内的再定位比健康对照者更有效（P=0.02*）。在没有任何触发的情况下，SCD 供体的中性粒细胞释放出更多的髓过氧化物酶（P=0.02*）。我们的数据表明，在 HU 治疗期间，稳定状态下的 SCD 患者的中性粒细胞仍然活跃，并且可能有助于 SCD 的促炎环境。
