Rusalatide Acetate (TP508) Mitigation Effect on Radiation Induced Keratopathy

摘要 放射性角膜病变导致严重的眼表疾病，干细胞缺乏，视力丧失， 不适，以及随之而来的不良生活质量，影响高达23%的接受放射治疗的患者 对于头部和颈部恶性肿瘤[1]。研究指出，角膜神经元和 泪腺分泌细胞在放射性角膜病变病因中的作用。这项研究旨在 研究已知的放射缓解药物醋酸鲁沙拉肽(TP508)保护或修复的效果 照射小鼠模型中的角膜上皮细胞、角膜神经元和泪液细胞。对一只小鼠的研究 角膜病变模型表明免疫稳态的破坏可归因于角膜 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丢失和白细胞流入和激活的增加 并暗示慢性神经丢失对角膜免疫稳态的影响[2]。研究 也表明泪腺直接受到辐射的影响，房水分泌物减少。 发生在照射后3天内，持续30天以上[3]。持续性的眼部炎症 反应通常导致对自身抗原的自我持久的适应性免疫T细胞反应，从而进一步 使病理永久化。TP508通过其精氨酸、甘氨酸和天冬氨酸(RGD)结合位点是一个 整合素受体的配体，先前已表明通过这一机制下调 促炎症途径和上调再生机制缓解细胞凋亡和干细胞 激活。这项研究的假设是，已知的TP508分子活性在 先前对大范围细胞的辐射防护研究在逆转角膜方面也有类似的效果。 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 Gy的计量辐射剂量，以前被证明对Balb/c小鼠是亚致死的，并且 导致角膜病变[2]。目的1将调查一天内注射TP508的情况 照射后24小时对角膜上皮细胞、角膜神经元和泪液的保护作用 腺体结构。剂量为200微克/毫升(5毫克/公斤)和500微克/毫升(12.5毫克/公斤)的TP508剂量的影响将是 已评估。分析将包括荧光素角膜染色在1个月时是否有损害 术后2个月及免疫组织化学检测角膜神经元和泪液细胞免疫标志物 2月龄泪腺结构的超微结构分析。目标2将调查一种外用眼药水 提供相同的两次剂量，照射后一天(24小时)和两周一次，共两周 使用在1个月和2个月时间点收集的相同数据点。预计将进行调查 建议TP508在减轻放射性角膜病变方面的潜在作用和最佳给药途径。

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.