Modulation of Corneal Wound Healing using Pre-Surgical Dietary Restriction

 描述(由研究人员提供)：饮食限制(DR)被定义为在没有营养不良的情况下减少食物摄入量，已被证明可以延长各种生物体的寿命，并增强对多种形式的急性应激的抵抗力。虽然大多数研究都集中在脑、心、肾和肝脏的缺血再灌注损伤上，但DR也被证明可以改善非缺血性肝切除手术后的存活率和肝脏再生，并在真皮伤口愈合过程中减少成纤维细胞的增殖和细胞外基质的合成。这些结果以及来自其他组织的基因表达数据表明，DR可能有潜力通过减少细胞死亡、炎症和纤维化来改善手术后眼部伤口的愈合反应；然而，这一点尚未得到直接或定量的评估。由于角膜直接暴露在环境中，因此容易受到物理损伤、化学损伤和感染。角膜疤痕是世界范围内导致失明的主要原因，可因这些侮辱而发展。由于它的可及性和光学功能，角膜也是视力矫正手术的目标，如准分子激光屈光性角膜切削术(PRK)和LASIK-在美国每年进行超过50万次手术。由于间质纤维化导致的角膜混浊的发展仍然是这些患者的一个重要并发症。这项拟议研究的目标是通过以下方式在细胞水平上初步评估DR对角膜创伤愈合的影响：1)使用体内共聚焦成像，评估长期DR和短期禁食对小鼠机械清创或经角膜冷冻损伤后角膜上皮和基质厚度、角质细胞密度、细胞和ECM背向散射的影响；2)使用原位成像、免疫细胞化学和生化分析方法，将这些临床结果与初始细胞死亡、炎症、促炎细胞因子的表达以及肌成纤维细胞转化和纤维化标志物的表达和定位直接相关。这项拟议的研究将首次确定长期禁食或短期禁食是否会减少损伤后的角膜纤维化。这些探索性研究最终可能导致识别新的靶点和模拟药物，以减轻损伤或屈光手术后可能发生的角膜透明度(从而减轻视力)的损失。由于角膜中伤口愈合和纤维化的主要介质与大多数其他组织中的相同，这些研究中获得的信息也应该为深入了解DR对全身手术后伤口愈合的潜在影响提供依据。在资助过程中，将为一名生物医学工程专业毕业生(博士)提供培训。学生，1名博士后，以及2名暑期医学生和2名本科生研究员。

 DESCRIPTION (provided by investigator): Dietary restriction (DR), defined as reduced food intake without malnutrition, has been shown to extend lifespan in a wide variety of organisms, as well as provide increased resistance to many forms of acute stress. While most studies have focused on ischemia reperfusion injury to the brain, heart, kidney and liver, DR has also been shown to improve survival and hepatic regeneration following non-ischemic liver resection surgery, and to reduce fibroblast proliferation and extracellular matrix synthesis during dermal wound healing. These results, along with gene expression data from other tissues, suggest that DR may have the potential to improve post-surgical ocular wound healing responses by reducing cell death, inflammation and fibrosis; however, this has not yet been directly or quantitatively assessed. Since it is directly exposed to the environment, the cornea is susceptible to physical trauma, chemical injury and infection. Corneal scarring, which can develop in response to these insults, is a leading cause of blindness worldwide. Because of its accessibility and optical power, the cornea is also the target for vision correction procedures such as photorefractive keratectomy (PRK) and LASIK - with over 500,000 procedures performed annually in the US. The development of corneal haze due to stromal fibrosis remains a significant complication in a subset of these patients. The goal of the proposed research is to perform an initial assessment of the effects of DR on corneal wound healing at the cellular level by: 1) Using in vivo confocal imaging to assess the effects of both long-term DR and short term fasting on changes in corneal epithelial and stromal thickness, keratocyte density, and cell and ECM backscattering after mechanical debridement or transcorneal freeze injury in the mouse; and, 2) Using in situ imaging, immunocytochemistry and biochemical assays to directly correlate these clinical outcome measurements with differences in initial cell death, inflammation, expression of pro-inflammatory cytokines, and the expression and localization of markers for myofibroblast transformation and fibrosis. The proposed research will be the first to determine whether long-term dietary restriction or short-term fasting results in reduced corneal fibrosis following injury. These exploratory studies could ultimately lead to the identification of new targets and mimetics for mitigating the loss of corneal transparency (and thus visual acuity) that can occur following injury or refractive surgery. Because the primary mediators of wound healing and fibrosis in the cornea are the same as those in most other tissues, information gained in these studies should also provide insights into the potential impact of DR on post-surgical wound healing throughout the body. During the course of the grant, training will be provided to one biomedical engineering graduate (Ph.D.) student, one post-doc, as well as 2 summer medical students and 2 undergraduate research fellows.