Department of Systems Medicine, University of 'Tor Vergata', Rome, Italy.
Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy.
J Crohns Colitis. 2019 May 27;13(6):772-784. doi: 10.1093/ecco-jcc/jjy215.
In ulcerative colitis [UC], mucosal damage occurs in areas that are infiltrated with neutrophils. The antimicrobial function of neutrophils relies in part on the formation of extracellular web-like structures, named neutrophil extracellular traps [NETs]. The formation and/or clearance of aberrant NETs have been associated with several immune diseases. Here we investigated the role of NETs in UC-related inflammation.
The expression of NET-associated proteins was evaluated in colonic biopsies of patients with Crohn's disease [CD], UC and in normal controls [NC] by Western blotting, immunofluorescence and immunohistochemistry. Colonic biopsies of UC patients were analysed before and after anti-tumour necrosis factor α [anti-TNF-α] treatment. The capacity of neutrophils to produce NETs upon activation was tested in vitro. UC lamina propria mononuclear cells [LPMCs] were cultured with NETs in the presence or absence of an extracellular signal-regulated kinase-1/2 [ERK1/2] inhibitor and inflammatory cytokine induction was assessed by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. We also characterized the contribution of NETs in dextran sodium sulfate [DSS]-induced colitis.
NET-associated proteins were over-expressed in inflamed colon of UC patients as compared to CD patients and NC. Circulating neutrophils of UC patients produced NETs in response to TNF-α stimulation, and reduced expression of NET-related proteins and diminished NET formation were seen in patients receiving successful treatment with anti-TNF-α. Treatment of UC LPMCs with NETs activated ERK1/2, thus enhancing TNF-α and interleukin-1β [IL-1β] production. NETs were induced in mice with DSS-colitis and in vivo inhibition of NET release attenuated colitis.
Our data show that NET release occurs in UC and suggest a role for NETs in sustaining mucosal inflammation in this disorder.
在溃疡性结肠炎（UC）中，黏膜损伤发生在浸润中性粒细胞的区域。中性粒细胞的抗菌功能部分依赖于形成细胞外网状结构，称为中性粒细胞胞外陷阱（NETs）。异常 NET 的形成和/或清除与几种免疫疾病有关。在这里，我们研究了 NET 在 UC 相关炎症中的作用。
通过 Western blot、免疫荧光和免疫组织化学评估克罗恩病（CD）、UC 患者和正常对照（NC）的结肠活检组织中与 NET 相关的蛋白表达。分析 UC 患者在抗肿瘤坏死因子-α（抗-TNF-α）治疗前后的结肠活检组织。在体外检测中性粒细胞激活后产生 NET 的能力。在存在或不存在细胞外信号调节激酶 1/2（ERK1/2）抑制剂的情况下，用 NET 培养 UC 固有层单核细胞（LPMCs），并通过实时聚合酶链反应和酶联免疫吸附试验评估炎症细胞因子的诱导。我们还研究了 NET 在葡聚糖硫酸钠（DSS）诱导的结肠炎中的作用。
与 CD 患者和 NC 相比，UC 患者炎症结肠中表达的 NET 相关蛋白增加。UC 患者的循环中性粒细胞在 TNF-α刺激下产生 NET，抗-TNF-α治疗成功的患者中观察到 NET 相关蛋白表达减少和 NET 形成减少。用 NET 处理 UC LPMCs 激活了 ERK1/2，从而增强了 TNF-α和白细胞介素-1β（IL-1β）的产生。DSS 结肠炎小鼠中诱导了 NET，体内抑制 NET 释放可减轻结肠炎。
我们的数据表明 NET 在 UC 中释放，并提示 NET 在维持这种疾病的黏膜炎症中起作用。
