Rusalatide Acetate (TP508) Mitigation Effect on Radiation Induced Keratopathy

摘要 辐射诱导的角膜病变导致显著的眼表疾病、干细胞缺乏、视力丧失， 不适和随后的生活质量差，影响高达23%的接受放射治疗的患者 头颈部恶性肿瘤[1]。研究指出了角膜神经元的功能作用， 泪腺分泌细胞与放射性角膜病变的关系本研究旨在 研究一种已知的放射性缓解药物醋酸雷帕霉素（TP 508）对保护或修复 角膜上皮细胞、角膜神经元和泪腺细胞。小鼠研究 角膜病变模型表明，免疫稳态的破坏可归因于角膜病变。 神经损伤可能是放射性角膜病变的关键病理机制[2]。一项研究 在几个月内表现出显著的神经丧失和白细胞流入和激活的增加， 照射，并暗示慢性神经丧失对角膜免疫稳态的影响[2]。研究 还表明泪腺直接受到辐射的影响，水分泌减少 在照射后3天内发生，并持续超过30天[3]。持续性眼部炎症 免疫应答通常导致对自身抗原的自我持续的适应性免疫T细胞应答， 使病理学永久化。TP 508通过其精氨酸、甘氨酸和天冬氨酸（RGD）结合位点是一种具有生物活性的多肽。 整合素受体的配体，并且之前已证明通过这种机制下调 促炎途径和上调细胞凋亡缓解和干细胞再生机制 activation.本研究的假设是，在本研究中证明的TP 508的已知分子活性是由一种或多种蛋白质组成的。 以前对广泛细胞的辐射防护研究将在逆转角膜炎中具有类似的效果。 和泪腺辐射损伤研究将包括全身和局部给药途径。Balb/ c小鼠将接受11戈伊的计量辐射剂量，先前显示对Balb/c小鼠是亚致死的， 导致角膜病变[2]。目的1将研究腹膜内注射TP 508一天 (24小时），以观察其对角膜上皮细胞、角膜神经元和泪腺的保护作用。 腺体结构TP 508剂量为200 µg/ml（5 mg/kg）和500 µg/ml（12.5 mg/kg）时的效应将被 评估。分析将包括1个月时是否存在病变的荧光素角膜染色 角膜神经元和泪腺细胞的免疫标记物的免疫组织化学 术后2个月泪腺超微结构分析。目标2将研究一种局部滴眼液 在照射后一天（24小时）和两周一次给予相同的2个剂量， 在1个月和2个月时间点收集相同的数据点。预计调查将 提示TP 508在减轻放射性角膜病变中的潜在作用和最佳递送途径。

Abstract Radiation induced keratopathy results in significant ocular surface disease, stem cell deficiency, vision loss, discomfort, and subsequent poor quality of life, affecting up to 23% of patients receiving radiation therapy for head and neck malignancies [1]. Studies have pointed out functional roles of corneal neurons and secretory cells of the lacrimal gland in the etiology of radiation induced keratopathy. This study is aimed to investigate the effect of a known radio-mitigating drug, rusalatide acetate (TP508), to protect or repair corneal epithelial cells, corneal neurons and lacrimal cells in an irradated mouse model. Studies in a murine model of keratopathy indicate that the breakdown of immune homeostasis can be attributed to corneal nerve damage which may be a key pathologic mechanism of radiation keratopathy [2]. One study demonstrated significant nerve loss and increase in leukocyte influx and activation within months of irradiation and implicated the effects of chronic nerve loss on corneal immune homeostasis [2]. Studies have also shown that the lacrimal gland is directly affected by radiation with decreased aqueous secretion occurring within 3 days of irradiation and persisting beyond 30 days [3]. A persistent ocular inflammatory response often leads to a self-perpetuating adaptive immune T-cell response to self-antigens that further perpetuates the pathology. TP508, through its Arginine, Glycine, and Aspartate (RGD) binding site is a ligand for integrin receptors and has been previously shown through this mechanism to down regulate proinflammatory pathways and upregulate regenerative mechanisms for apoptosis mitigation and stem cell activation. The hypothesis for this study is that the known molecular activity of TP508 demonstrated in previous radioprotection studies across a wide range of cells will have a similar effect in reversing corneal and lacrimal gland radiation damage. Studies will include systemic and topical routes of drug delivery. Balb/ c mice will receive a metered radiation dose of 11 Gy, previously shown to be sublethal to Balb/c mice and to cause keratopathy [2]. Aim 1 will investigate an intraperitoneal injection of TP508 administered one day (24 hours) post irradiation for effects in protecting corneal epithelial cells, corneal neurons and lacrimal gland structure. Effects from TP508 doses of 200 µg/ml (5mg/kg) and 500 µg/ml (12.5mg/kg), will be evaluated. Analysis will include fluorescein corneal staining for presence or absence of lesions at 1 month and 2 months and immunohistochemistry for immune markers for corneal neurons and lacrimal cells with ultrastrucural analysis of lacrimal gland structure at 2 months. Aim 2 will investigate a topical eye drop delivery of the same 2 doses, administered one day (24 hours) and biweekly for two weeks post irradiation with the same data points collected at the 1- and 2-month time points. Investigations are expected to suggest potential effects of TP508 in mitigation of radiation keratopathy and optimal routes of delivery.