TREM-1在细菌性化脓性角膜炎中的作用及其分子机制

【目的】 探讨髓样细胞诱发受体1(TREM-1)在铜绿假单胞菌(PA)感染角膜炎中的作用及其分子机制。【方法】为了揭示TREM-1在细菌性角膜炎中的作用,我们建立了PA角膜炎小鼠模型和PA感染的腹腔巨噬细胞模型,real-time PCR和免疫荧光法检测感染前后TREM-1的表达水平;用丝裂原活化蛋白激酶(MAPKs)的抑制剂或磷脂酰肌醇3-激酶(PI3K)抑制剂预处理巨噬细胞,再用脂多糖(LPS)和TREM-1活化抗体刺激,real-time PCR检测IL-1β、MIP-2、TNF-α和IL-6等促炎因子的表达水平,进一步探讨TREM-1调控PA角膜炎的分子机制;用Th1细胞因子IFN-γ或者Th2细胞因子IL-4?IL-10刺激巨噬细胞,real-time PCR检测Th1/Th2细胞因子对TREM-1表达的调控。【结果】 PA感染的C57BL/6小鼠角膜中TREM-1表达高于BALB/c小鼠;体外研究显示PA感染和LPS刺激均诱导TREM-1高表达;TREM-1通过MAPK和PI3K-Akt通路调节促炎因子生成;Th1细胞因子促进TREM-1表达,而Th2细胞因子不影响TREM-1的表达。【结论】 PA 感染上调TREM-1的表达,TREM-1通过调控Th1/Th2细胞因子的表达进一步放大炎症,导致角膜溃疡穿孔,这一发现可能为化脓性角膜炎的防治提供了新的理论依据。

Role of TREM-1 in Pseudomonas aeruginosa Keratitis

【Objective】 To investigate the role of triggering receptor expressed on myeloid cells-1 (TREM-1) in Pseudomonas aeruginosa (PA) keratitis and the possible molecular mechanism involved. 【Methods】 To determine the relationship between TREM-1 and PA keratitis, we established the resistant (BALB/c) and susceptible (C57BL/6) PA keratitis murine model, and then examined TREM-1 mRNA and protein levels in the normal and infected corneas of BALB/c and C57BL/6 mice by real-time PCR and immunostaining, respectively. To further explore the mechanism of TREM-1 in PA keratitis, peritoneal M were challenged with lipopolysaccharide (LPS) or live PA, and then TREM-1 expression was tested by real-time PCR. Peritoneal macrophages (MΦ) were pretreated with inhibitors for mitogen activated protein kinases (MAPKs) or phosphatidylinositol 3-kinase (PI3K), and after challenge with LPS and agonistic mTREM-1 Ab, mRNA levels of pro-inflammatory cytokines including IL-1, MIP-2, TNF, and IL-6 was determined using real-time PCR. TREM-1 mRNA levels were also tested by real-time PCR in peritoneal MΦ pretreated with IFN or IL-4, IL-10. 【Results】 TREM-1 expression levels were significantly increased in C57BL/6 vs BALB/c corneas after PA infection. In peritoneal MΦ, TREM-1 expression was also increased after LPS stimulation or PA infection. TREM-1 modulated pro-inflammatory cytokine production through MAPK and PI3K-Akt signaling pathway. TREM-1 expression levels were significantly increased after stimulation with LPS and Th1 cytokine, but not Th2 cytokine. 【Conclusion】 The PA-induced up-regulation of TREM-1 amplified corneal inflammation by modulating production of Th1 and Th2 cytokines, thereby accelerating the disease progression of PA keratitis. These findings may provide a promising target for treatment of PA keratitis.