Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
J Immunol. 2009 Dec 15;183(12):8054-60. doi: 10.4049/jimmunol.0902140.
Defensins play an important role in both innate and adaptive immunity due to their antimicrobial, regulatory, and chemotactic effects. Nonetheless, the role of murine beta-defensins (mBD) 3 and 4, the murine homologs of human beta-defensins (hBD) 2 and 3, remains unknown in Pseudomonas aeruginosa keratitis. This study explored their role in corneal infection and potential synergy with mBD2, a defensin associated with better outcome in this disease. Immunostaining and real-time RT-PCR data demonstrated that mBD3 and mBD4 expression was inducible and differentially regulated in the infected cornea of resistant BALB/c vs susceptible C57BL/6 (B6) mice. Knockdown studies using small interfering RNA treatment indicated that mBD3, but not mBD4, is required in ocular defense. Moreover, in vivo studies demonstrated individual and combined effects of mBD2 and mBD3 that modulate bacterial load, polymorphonuclear neutrophil (PMN) infiltration, and production of IFN-gamma, MIP-2, IL-1beta, TNF-alpha, inducible NO synthase (iNOS), TLR2, TLR4, MyD88, and NF-kappaB. Most notably, bacterial load was increased at 5 days postinfection by silencing either mBD2 or mBD3, but it was elevated at both 1 and 5 days postinfection when silencing both defensins. PMN infiltration was increased at 1 day postinfection by silencing both defensins or mBD3, but not mBD2 alone. iNOS expression was elevated by silencing mBD2, but it was reduced after silencing mBD3 or both defensins. Additionally, cell sources of mBD2 (macrophages, PMN and fibroblasts) and mBD3 (PMN) in corneal stroma were identified by dual label immunostaining after infection. Collectively, the data provide evidence that mBD2 and mBD3 together promote resistance against corneal infection.
防御素在先天免疫和适应性免疫中都发挥着重要作用，因为它们具有抗菌、调节和趋化作用。然而，鼠β-防御素（mBD）3 和 4，即人类β-防御素（hBD）2 和 3 的鼠同源物，在铜绿假单胞菌角膜炎中的作用仍不清楚。本研究探讨了它们在角膜感染中的作用，以及与 mBD2 的潜在协同作用，mBD2 是一种与该疾病更好预后相关的防御素。免疫染色和实时 RT-PCR 数据表明，mBD3 和 mBD4 的表达在抗性 BALB/c 与易感 C57BL/6（B6）小鼠的感染角膜中是可诱导的，并受到差异调控。使用小干扰 RNA 处理的敲低研究表明，mBD3 而不是 mBD4，在眼部防御中是必需的。此外，体内研究表明 mBD2 和 mBD3 的单独和联合作用可调节细菌负荷、多形核中性粒细胞（PMN）浸润以及 IFN-γ、MIP-2、IL-1β、TNF-α、诱导型一氧化氮合酶（iNOS）、TLR2、TLR4、MyD88 和 NF-κB 的产生。值得注意的是，沉默 mBD2 或 mBD3 均可在感染后 5 天增加细菌负荷，但同时沉默两种防御素时，在感染后 1 天和 5 天都可增加细菌负荷。沉默两种防御素或 mBD3 可在感染后 1 天增加 PMN 浸润，但单独沉默 mBD2 则不然。沉默 mBD2 可增加 iNOS 的表达，但沉默 mBD3 或两种防御素后，其表达减少。此外，在感染后通过双重免疫染色鉴定了角膜基质中 mBD2（巨噬细胞、PMN 和成纤维细胞）和 mBD3（PMN）的细胞来源。总之，这些数据提供了证据表明 mBD2 和 mBD3 共同促进了对角膜感染的抵抗。
