SPM Biodegradation: A Novel Mechanism for Impaired Healing of Chronic Wounds in Aging

摘要 如“PA-16-231衰老中的不愈合溃疡性伤口（R21）"中所述，“糖尿病溃疡发生率更高， 通常发生在老年人身上一些研究探讨了衰老如何影响这些（伤口愈合）过程， 我们认识上的差距限制了新疗法的适用性”。慢性疾病消退受阻 炎症在很大程度上是由于衰老和糖尿病的结合而损害愈合的原因。 解决慢性炎症是克服这种损害的关键，这是由于专门的亲- 分解脂质介质（SPM）。我们的长期目标是阐明受损愈合的机制， 糖尿病和衰老的影响，并开发更好的模式，有效地治疗老年人的慢性伤口。 SPM是由多不饱和脂肪酸内源性酶促制备的。在正常愈合的皮肤中的SPM- 伤口包括SPM 1（即，14 S，21 R-二羟基-二十二碳-4Z，7Z，10 Z，12 E，16 Z，19 Z-六烯酸）和 神经保护素D1（NPD 1）。SPM 1和NPD 1可以有效地解决慢性炎症， 糖尿病伤口的愈合糖尿病或老年人和小鼠的慢性伤口是SPM 1和NPD 1 与正常愈合相比，缺乏并含有更高水平的SPM 1和NPD 1生物降解产物 这表明SPM缺乏是愈合障碍的重要因素。我们的飞行员 研究发现，SPM 1和NPD 1被15-羟基前列腺素转化为降解产物 脱氢酶（PGDH，降解含羟基脂质介质的关键内源性酶）。因此 我们假设伤口SPM的生物降解加剧至少是造成伤口愈合的部分原因。 老年人糖尿病伤口愈合障碍。这将在已确定的老年糖尿病db/db中进行测试 夹板切除伤口的小鼠模型。我们还将使用PGDH敲除和抑制，以及我们独特的 水性手性（ac）LC-UV-MS/MS脂质组学平台。目标1。试验预测生物降解 在老年糖尿病小鼠的伤口愈合中使内源性SPM失活。1A）确定时间进程 伤口SPM的降解。我们将建立老年人伤口SPM生物降解的时间曲线， 1B）测试SPM 1和NPD 1生物降解物是否能够 促进小鼠伤口愈合。目标二。测试抑制关键酶途径的预测， SPM生物降解可恢复老年糖尿病小鼠的伤口愈合。我们将决定治愈， 伤口的炎症消退：2A）具有关键生物降解酶PGDH的老年糖尿病小鼠 被抑制剂阻断;和2B）PGDH敲除的小鼠，以验证2A的结果。总体影响： 该项目将定义新的机制，并探索抑制降解的治疗潜力。 的SPMs，在恢复衰老的糖尿病伤口愈合。这些研究将填补临床上的重大空白 关于糖尿病伤口衰老、脂质介质生物学和药理学的基础科学知识 与SPMs相关。提出的新机制是高度平移。

ABSTRACT As stated in “PA-16-231 Non-healing Ulcerative Wounds in Aging (R21)”, “diabetic ulcers occur more commonly in the elderly... few studies have explored how aging impacts these (wound healing) processes and this gap in our understanding limits the applicability of novel therapies”. Impeded resolution of chronic inflammation contributes largely to the impairment of healing by the combination of aging and diabetes. Resolving chronic inflammation is pivotal in overcoming this impairment, and is attributable to specialized pro- resolving lipid mediators (SPMs). Our long-term goal is to delineate the mechanisms of healing impaired by diabetes and aging and develop better modalities for effective treatment of chronic wounds in the elderly. SPMs are endogenously made enzymatically from polyunsaturated fatty acids. SPMs in normally healing skin- wounds include SPM1 (i.e., 14S,21R-dihydroxy-docosa-4Z,7Z,10Z,12E,16Z,19Z-hexaenoic acid) and neuroprotectin D1 (NPD1). SPM1 and NPD1 can potently resolve chronic inflammation and restoring the healing of diabetic wounds. Chronic wounds of diabetic or aged humans and mice are SPM1 and NPD1 deficient and contain higher levels of SPM1 and NPD1 biodegradation products, compared to normally healing wounds, suggesting that the SPM deficiency is an important contributor to the healing impairment. Our pilot study found that SPM1 and NPD1 were converted to the degradation products by 15-hydroxyprostaglandin dehydrogenase (PGDH, the key endogenous enzyme that degrade hydroxyl-containing lipid mediators). Thus we hypothesize that the exacerbated biodegradation of wound SPMs is at least partially responsible for the healing impairment in diabetic wounds in the elderly. This will be tested in an established aged diabetic db/db mouse model of splinted excisional wounds. We will also use PGDH knockout and inhibition, and our unique aqueous chiral (ac) LC-UV-MS/MS lipidomics platform. Aim 1. Test the prediction that the biodegradation deactivates endogenous SPMs in healing the wounds of aged diabetic mice. 1A) Determine the time course of degradation of wound SPMs. We will establish the temporal profiles of biodegradants of wound SPMs of aged diabetic mice using acLC-UV-MS/MS. 1B) Test whether or not the SPM1 and NPD1 biodegradants are able to promote wound healing in mice. Aim 2. Test the prediction that suppressing the key enzymatic pathway for SPM biodegradation restores the wound healing in aged diabetic mice. We will determine the healing and inflammation resolution of wounds: 2A) of the aged diabetic mice with the key biodegradation enzyme PGDH blocked by inhibitors; and 2B) of mice with PGDH knocked out to verify the results from 2A. Overall impact: This project will define novel mechanisms and explore the therapeutic potential of suppressing the degradation of SPMs, in restoring the healing of diabetic wound in aging. These studies will fill the clinically significant gap of basic scientific knowledge about diabetic wounds in aging, lipid mediator biology, and pharmacology associated with SPMs. The proposed novel mechanism is highly translational.