Halwani Rabih, Sultana Asma, Vazquez-Tello Alejandro, Jamhawi Amer, Al-Masri Abeer A, Al-Muhsen Saleh
a Department of Pediatrics, Prince Naif Center for Immunology Research, Asthma Research Chair , College of Medicine, King Saud University , Riyadh , Saudi Arabia.
b Prince Naif Health Research Center , King Saud University , Riyadh , Saudi Arabia.
J Asthma. 2017 Nov;54(9):893-904. doi: 10.1080/02770903.2017.1283696. Epub 2017 Mar 2.
In a subset of severe asthma patients, chronic airway inflammation is associated with infiltration of neutrophils, Th-17 cells and elevated expression of Th-17-derived cytokines (e.g., interleukin [IL]-17, IL-21, IL-22). Peripheral neutrophils from allergic asthmatics are known to express higher IL-17 cytokine levels than those from healthy subjects, but the regulatory mechanisms involved are not well understood. We hypothesize that Th-17 regulatory cytokines could modulate IL-17 expression in neutrophils.
Peripheral blood neutrophils isolated from asthmatics were stimulated with IL-21, IL-23, and IL-6 cytokines and their ability to produce IL-17A and IL-17F was determined relative to healthy controls. Signal transducer and activator of transcription 3 (STAT3) phosphorylation levels were measured in stimulated neutrophil using flow cytometry. The requirement for STAT3 phosphorylation was determined by blocking its activation using a specific chemical inhibitor.
Stimulating asthmatic neutrophils with IL-21, 23, and 6 enhanced the production of IL-17A and IL-17F at significantly higher levels comparatively to healthy controls. Stimulating neutrophils with IL-21, IL-23, and IL-6 cytokines enhanced STAT3 phosphorylation, in all cases. Interestingly, inhibiting STAT3 phosphorylation using a specific chemical inhibitor dramatically blocked the ability of neutrophils to produce IL-17, demonstrating that STAT3 activation is the major factor mediating IL-17 gene expression.
These findings suggest that neutrophil infiltration in lungs of severe asthmatics may represent an important source of pro-inflammatory IL-17A and -F cytokines, a production enhanced by Th-17 regulatory cytokines, and thus providing a feedback mechanism that sustains inflammation. Our results suggest that STAT3 pathway could be a potential target for regulating neutrophilic inflammation during severe asthma.
在一部分重度哮喘患者中，慢性气道炎症与中性粒细胞、Th-17细胞浸润以及Th-17衍生细胞因子（如白细胞介素[IL]-17、IL-21、IL-22）表达升高有关。已知过敏性哮喘患者外周血中性粒细胞表达的IL-17细胞因子水平高于健康受试者，但其中涉及的调控机制尚不清楚。我们推测Th-17调控细胞因子可调节中性粒细胞中IL-17的表达。
用IL-21、IL-23和IL-6细胞因子刺激从哮喘患者中分离出的外周血中性粒细胞，并相对于健康对照测定其产生IL-17A和IL-17F的能力。使用流式细胞术测量刺激的中性粒细胞中信号转导和转录激活因子3（STAT3）的磷酸化水平。通过使用特异性化学抑制剂阻断其激活来确定STAT3磷酸化的必要性。
与健康对照相比，用IL-21、23和6刺激哮喘患者的中性粒细胞可显著提高IL-17A和IL-17F的产生水平。在所有情况下，用IL-21、IL-23和IL-6细胞因子刺激中性粒细胞均可增强STAT3磷酸化。有趣的是，使用特异性化学抑制剂抑制STAT3磷酸化可显著阻断中性粒细胞产生IL-17的能力，表明STAT3激活是介导IL-17基因表达的主要因素。
这些发现表明，重度哮喘患者肺部的中性粒细胞浸润可能是促炎IL-17A和-F细胞因子的重要来源，Th-17调控细胞因子可增强其产生，从而提供一种维持炎症的反馈机制。我们的结果表明，STAT3通路可能是重度哮喘期间调节嗜中性粒细胞炎症的潜在靶点。
