Department of Dermatology, Chongqing University Three Gorges Hospital, School of Medicine, Chongqing University, No.165, Xincheng Road, Wanzhou District, Chongqing 400030, China.
Department of Pediatrics, The Third Affiliated Hospital of Chongqing Medical University, No.1, Shuanghu Road, Yubei District, Chongqing 401120, China.
J Leukoc Biol. 2023 May 2;113(5):461-470. doi: 10.1093/jleuko/qiad025.
Inflammation centered on non-IgE-mediated mast cell activation characterizes chronic spontaneous urticaria resistant to nonsedating H1-antihistamines. We recently uncovered a strong positive association between inflammation and the fecal Escherichia. To further explore the actions of bacterial DNA derived from Escherichia on mast cells, intestinal permeability of patients with chronic spontaneous urticaria with or without nonsedating H1-antihistamine resistance and healthy controls were determined, and LAD2 cells with knockdown of Syk, Nedd4L, or Sgk1 or with incubation of inhibitors GS9973, GSK650394, and MG132 were posttreated with btDNA. We found that (i) serum intestinal permeability indices and bacterial DNA markedly increased in patients with chronic spontaneous urticaria with nonsedating H1-antihistamine resistance compared with those without (all P < 0.001), and bacterial DNA positively correlated with the degree of inflammation; (ii) IL-6 and TNF-α levels were time- and dose-dependently upregulated in bacterial DNA-stimulated LAD2 cells, which relied on unmethylated CpG in bacterial DNA and Toll-like receptor 9 protein in cells; (iii) Syk knockdown or inhibition of Syk Tyr525/526 phosphorylation blocked bacterial DNA-initiated cytokine production; (iv) Nedd4L interacted with Tyr525/526-phosphorylated Syk, and inhibition of Nedd4L Ser448 phosphorylation induced by bacterial DNA-activated Sgk1 was mandatory for bacterial DNA's proinflammatory property; and (v) Sgk1 suppression showed an inhibitory effect on bacterial DNA-induced inflammation by ensuring Nedd4L-mediated ubiquitination of Tyr525/526-phosphorylated Syk. Collectively, we identified previously unknown contributory roles of bacterial translocation and serum bacterial DNA on the inflammation phenotype in patients with chronic spontaneous urticaria with nonsedating H1-antihistamine resistance and further uncovered a vital negative regulatory role for the Sgk1/Nedd4L/Syk pathway in bacterial DNA-induced inflammation in LAD2 cells.
以非 IgE 介导的肥大细胞活化为中心的炎症是慢性自发性荨麻疹的特征，这种荨麻疹对非镇静 H1 抗组胺药有抗性。我们最近发现炎症与粪便大肠杆菌之间存在强烈的正相关。为了进一步探索源自大肠杆菌的细菌 DNA 对肥大细胞的作用，我们测定了慢性自发性荨麻疹患者（包括对非镇静 H1 抗组胺药有抗性和无抗性的患者）和健康对照者的肠道通透性，并用 Syk、Nedd4L 或 Sgk1 敲低的 LAD2 细胞或用 GS9973、GSK650394 和 MG132 孵育的 LAD2 细胞处理 btDNA。我们发现：（i）与无非镇静 H1 抗组胺药抗性的慢性自发性荨麻疹患者相比，对非镇静 H1 抗组胺药有抗性的慢性自发性荨麻疹患者的血清肠道通透性指数和细菌 DNA 显著增加（均 P < 0.001），并且细菌 DNA 与炎症程度呈正相关；（ii）细菌 DNA 刺激的 LAD2 细胞中 IL-6 和 TNF-α 水平呈时间和剂量依赖性上调，这依赖于细菌 DNA 中的未甲基化 CpG 和细胞中的 Toll 样受体 9 蛋白；（iii）Syk 敲低或抑制 Syk Tyr525/526 磷酸化可阻断细菌 DNA 引发的细胞因子产生；（iv）Nedd4L 与 Tyr525/526 磷酸化的 Syk 相互作用，并且细菌 DNA 激活的 Sgk1 诱导的 Nedd4L Ser448 磷酸化对于细菌 DNA 的促炎特性是必需的；（v）Sgk1 抑制通过确保 Nedd4L 介导的 Tyr525/526 磷酸化的 Syk 泛素化，对细菌 DNA 诱导的炎症具有抑制作用。总的来说，我们确定了先前未知的细菌易位和血清细菌 DNA 对非镇静 H1 抗组胺药有抗性的慢性自发性荨麻疹患者炎症表型的促炎作用，并进一步发现 Sgk1/Nedd4L/Syk 途径在细菌 DNA 诱导的 LAD2 细胞炎症中具有重要的负调控作用。
