Ceramide通过IL-23介导支气管哮喘糖皮质激素抵抗的作用及机制研究

The overall increased mortality in asthma is mainly due to steroid-resistant asthma. The pathogenetic mechanism of steroid-resistant asthma is still unclear and there are no effective therapies. In the preliminary studies we have found that ceramide level was higher in patients with steroid-resistant asthma compared with those with steroid-sensitive asthma. Intratracheal instillation of ceramide in mice significantly promoted steroid-resistant airway inflammation and IL-23 production. Treatment with neutralizing anti-IL-23 antibody suppressed the features of ceramide-induced steroid-resistant asthma. The in vitro studies on macrophages showed that ceramide induced IL-23 production probably through the activation of PKCζ. Thus, we proposed that IL-23 induced by ceramide mediated activation of the PKCζ-NF-κB pathway promoted steroid-resistant asthma development. The roles for targeting of ceramide in experimental steroid-resistant asthma will be examined using ceramide synthesis inhibitor myriocin. We will also test whether direct intratracheal instillation of ceramide recapitulates the phenotype of steroid-resistant asthma. We will use PKCζ and NF-κB siRNA and IL-23p19 knock-out mice to investigate the mechanism of ceramide in steroid-resistant asthma development. This study will provide a new therapeutic idea for the prevention and treatment of steroid-resistant asthma.

激素抵抗是导致哮喘病死率升高的主要原因之一，其发病机制尚未阐明，亦无有效治疗方案。神经酰胺（Ceramide，Cer）是介导哮喘气道炎症的重要因素，然而Cer促进哮喘激素抵抗的作用未见报道。我们前期研究发现存在激素抵抗的哮喘患者痰液Cer水平明显升高，气管滴入Cer促进哮喘小鼠激素抵抗和IL-23分泌，而中和性抗体阻断IL-23明显逆转Cer诱导的哮喘小鼠激素抵抗，体外实验显示Cer促进IL-23分泌的作用与PKCζ激活相关，因此我们提出假说“Cer通过激活PKCζ-NF-κB通路促进IL-23分泌从而介导哮喘激素抵抗的发生发展”。本研究将建立哮喘小鼠模型，通过抑制Cer生成及气管滴入Cer证实其促进哮喘激素抵抗的作用；IL-23p19敲除小鼠及细胞水平干扰IL-23、PKCζ、NF-κB表达，阐明Cer的作用机制。该研究将为激素抵抗型哮喘病理机制研究及药物筛选靶点建立提供新的思路。

激素抵抗是导致哮喘病死率升高的主要原因之一，然而其发病机制尚未完全明确，对糖皮质激素抵抗型哮喘的治疗尚无有效方案。本项目通过收集哮喘患者痰液发现急性加重期哮喘患者血清Ceramide水平明显升高，Ceramide 24:0、Ceramide 26:0水平与NEU%水平成正相关。通过建立哮喘小鼠模型，我们发现，与糖皮质激素敏感型哮喘模型小鼠比较，糖皮质激素抵抗型哮喘模型小鼠支气管肺泡灌洗液中Ceramide水平明显升高。同时，我们还发现，气管滴入Ceramide能够促进哮喘糖皮质激素抵抗的发展，而采用抑制剂抑制Ceramide生成能够抑制哮喘糖皮质激素抵抗的发展，上述结果阐明了Ceramide介导哮喘糖皮质激素抵抗的作用。在细胞模型中，采用Ceramide刺激巨噬细胞，糖皮质激素抵抗相关炎性因子IL-1β和IL-23水平明显升高。同时，本项目资助的研究还有另外发现，Ceramide通过激活肺上皮细胞JAK2-STAT3通路诱导MMP-9表达，从而促进气道重塑的发生发展。本项目研究结果有效阐释了Ceramide促进哮喘气道炎症发生发展的作用，有助于补充哮喘糖皮质激素抵抗机制，为发现潜在的能够逆转哮喘糖皮质激素抵抗药物提供新思路和新靶点。