Functions of mammalian PGLYRPs in the cornea

描述(申请人提供)：角膜是一种透明的、屈光的、保护性的眼粘膜屏障。角膜感染对健康视力构成严重威胁。感染的风险随着受伤、手术、日常戴隐形眼镜和年龄的增加而增加。抗菌蛋白和抗菌肽的研究对于阐明角膜的自然保护机制和基于这些机制的治疗至关重要。我们的研究重点是哺乳动物肽聚糖识别蛋白(PGLYRP)家族的四种抗微生物蛋白，它们存在于各种粘膜屏障中，并在十多年前被发现。我们在人和小鼠角膜中发现了PGLYRP1，随后在人和小鼠的角膜中发现了其他的PGLYRP2、-3和-4。哺乳动物PGLYRP成员的功能通常被研究得很少，尤其是在眼睛中对这些功能知之甚少。昆虫中的PGLYRP大家族已知得更多：它们大多是杀菌的，一些水解肽多糖(PGN)以抑制炎症，而另一些则信号转导宿主Toll和IMD途径以诱导先天免疫和抗菌肽(AMP)基因。哺乳动物PGLYRP1、-3和-4对革兰氏阳性菌和革兰氏阴性菌都有杀菌作用，而PGLYRP2是一种酰胺酶。在体外，它们与AMP具有协同作用，但在体内的协同作用尚不清楚，但有人怀疑。哺乳动物的PGLYRPs是否也调节先天免疫信号仍有待充分研究。因此，哺乳动物的PGLYRPs可能代表了一类新的角膜抗菌免疫调节剂。我们在这个R21提案中的中心假设是，哺乳动物角膜中的PGLYRPs可能具有双重作用，既可以阻止病原体感染，又可以促进角膜愈合和动态平衡的先天性免疫信号。有两个目的将验证这一中心假设1)在假单胞菌(P).铜绿假单胞菌角膜炎模型中测试Pglrp1-4基因缺失小鼠的抗菌防御能力。2a)测试PGLYRPs是否与角膜中的天然免疫信号(TLR2、4和NOD2)相互作用，以上调细胞因子和b-防御素；以及2b)PGLYRPs是否通过促进上皮迁移来加速角膜愈合。这项对PGLYRP家族的探索性研究将为其在角膜中的作用提供必要的评估，并为未来对每个成员在促进角膜健康、控制感染和开发靶向治疗方面的详细研究奠定基础。在未来，我们的研究可能会导致预防或治疗方法，以调整手术前/后角膜上皮中PGLYRP水平，以及移植角膜的感染和储存。 公共卫生相关性：我们对这个肽聚糖识别蛋白家族的发现将阐明角膜中的天然抗菌防御机制，以及在角膜感染和损伤或手术相关创伤、移植角膜或隐形眼镜储存期间调节其水平和功能的治疗/预防策略。

DESCRIPTION (provided by applicant): The cornea is a transparent, refractive, protective mucosal barrier of the eye. Corneal infections pose a serious threat to healthy vision. Risks of infections increase with injury, surgery, daily contact lens wear and age. Research on antimicrobial proteins and peptides is critical for elucidating natural protective mechanisms in the cornea and therapies based on these. Our proposal focuses on the mammalian peptidoglycan recognition protein (PGLYRP) family of four antimicrobial proteins, which exist in various mucosal barriers, and identified just over a decade ago. We found PGLYRP1, and subsequently others PGLYRP2, -3 and -4 in the human and mouse cornea. Functions of mammalian PGLYRP members are generally underexplored, and in particular little is known of these in the eye. Much more is known of the large PGLYRP family in insects: they are mostly bactericidal, some hydrolyze peptidoglycans (PGN) to restrict inflammation, while others signal to host toll and imd pathways to induce genes of innate immunity and antimicrobial peptides (AMP). Mammalian PGLYRP1, - 3 and -4 are bactericidal against gram positive and negative bacteria, and PGLYRP2 is an amidase. In vitro, they work synergistically with AMPs, synergy in vivo is not known, but suspected. Whether the mammalian PGLYRPs also modulate innate immune signals remains to be fully investigated.. Thus, the mammalian PGLYRPs may represent a new class of antimicrobial immune modulators in the cornea. Our central hypothesis in this R21 proposal is that PGLYRPs in the mammalian cornea may have a dual role in deterring pathogenic bacterial infections while promoting innate immune signals for corneal healing and homeostasis. Two aims will test this central hypothesis.1) Test antibacterial defense capabilities of Pglyrp1-4 null mice in a Pseudomonas (P).aeruginosa keratitis model. 2a)Test if the PGLYRPs cross talk with innate immune signals (TLR2, 4 and Nod2) in the cornea to up regulate cytokines and b- defensins, and 2b) whether the PGLYRPs expedite corneal healing by promoting epithelial migration. This exploratory study of the PGLYRP family will provide the necessary assessment of its role in the cornea and the groundwork for future detailed studies of each member in promoting corneal health, curbing infections and developing targeted therapies. In the future our study may lead to prophylactic or therapeutic approaches that tweak PGLYRP levels in the corneal epithelium before/after surgery, infection and storage of transplant corneas. PUBLIC HEALTH RELEVANCE: Our findings on this peptidoglycan recognition protein family will elucidate natural antimicrobial defense mechanisms in the cornea, therapeutic/prophylactic strategies for regulating their levels and functions during corneal infections and injury or surgery-related trauma, transplant cornea or contact lens storage.