Aging Stratum Corneum pH and Barrier Function

老化角质层pH值与屏障功能

• 批准号: 7676051
• 负责人: Theodora M Mauro
• 金额: $ 30.31万
• 依托单位: NORTHERN CALIFORNIA INSTITUTE/RES/EDU
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7676051
• 关键词: 6-carboxyfluorescein; Abbreviations; Acidity; Acids; Adult; Affect; Age; Aging; Animals; Area; Biopsy; Bypass; Cell membrane; Clinical; Complement; Defect; Disease; Down-Regulation; Dryness; Eczema; Enzymes; Epidermis; Family; Fluorescence; Future; Goals; Homeostasis; Human; Image; Immunoelectron Microscopy; Immunohistochemistry; Impairment; Individual; Inflammatory; Knockout Mice; Lead; Ligands; Lipids; Liver; Measures; Mediating; Methylguanidine; Microscopy; Mus; NHE1; Neonatal; Pattern; Permeability; Peroxisome Proliferator-Activated Receptors; Phospholipase; Phospholipase A2; Play; Predisposition; Process; Protein Isoforms; Proteins; Protocols documentation; Recovery; Relative (related person); Role; Severities; Skin; Skin Aging; Solutions; Stratum Granulosum; Stratum corneum; Techniques; Testing; Therapeutic; Thick; Water; Work; acronyms; aged; alveolar lamellar body; antiporter; compare effectiveness; glucosylceramidase; human subject; improved; inhibitor/antagonist; lactobionic acid; public health relevance; receptor; research study; resorufin; sPLA2 enzyme; skin disorder; small hairpin RNA; young adult

DESCRIPTION (provided by applicant): Aged skin commonly is afflicted by inflammatory skin diseases or xerosis/eczema that can be traced to, or exacerbated by, impaired epidermal permeability barrier homeostasis. In contrast to extremely aged individuals, we find that moderately aged humans (50-80 years) and mice (12-15 mos) suffer from defective stratum corneum (SC) acidification. SC acidification is required to activate key pH-sensitive lipid processing enzymes, including beta-GlcCer'ase (beta-glucocerebrosidase). Neonatal and adult SC both are acidified largely through the combined activity of two endogenous mechanisms, the Na+/H+ antiporter (NHE1) and the secretory phospholipase (sPLA2) enzymes, although the relative contribution of each agent in supplying SC acidity to specific regions of the SC is not known. We previously found that NHE1 protein levels and full- thickness SC acidity are decreased in moderately aged mouse epidermis. We now propose to define the relative roles of NHE1 and sPLA2 in acidifying specific regions of the SC in young adult mouse and human epidermis, and determine what role abnormal NHE1 or sPLA2 expression, localization and/or function play in producing the abnormal acidification seen in aged SC. We will define the roles of the NHE1 and sPLA2 in both murine and human skin, and then delineate the responsible mechanisms in mouse skin and cultured human epidermal equivalents. Finally, we will explore a broad set of strategies aimed at normalizing SC acidification, either by upregulating sPLA2 activity, or by bypassing defective endogenous mechanisms with exogenous acidifying agents already approved for use in humans. HYPOTHESIS: Both the NHE1 transporter and one or more sPLA2 isoforms control SC barrier bulk acidification, or acidification of SC microdomains, where the pH-sensitive lipid processing enzymes that influence barrier homeostasis are selectively and locally activated. The NHE1 and sPLA2 complement each other in acidifying different layers and microdomains within normal young adult SC. Defects in one or both acidifying mechanisms result in suboptimal function in moderately aged epidermis, depending on the severity and localization of the age-associated pH abnormality. Enhancing SC acidity, either through increased sPLA2 activity, or by applying exogenous acidifying agents, will normalize lipid processing, thereby improving the clinical abnormalities in SC function seen in aged epidermis. The short-term goal of this project is to determine the pathophysiologic mechanisms by which SC acidity differs in aged vs. young SC. The long-term goal of this project is to restore epidermal permeability barrier homeostasis in aged skin, by optimizing the SC acidity that controls barrier homeostasis. PUBLIC HEALTH RELEVANCE: Information form these experiments will be used to optimize therapeutic protocols that restore effective epidermal barrier homeostasis in aged skin. As normal skin ages, it tends to become dry. This dryness makes even normal skin itchy, and makes skin that already is affected by common diseases, such as eczema, worse. Dry skin in moderately aged people (age 50-75 years) is caused by the loss of an epidermal barrier, made up of correctly processed lipids in the uppermost layer of the skin. Processing these lipids, in turn, depends on effectively acidifying this uppermost layer of the skin. We have found that even moderately aged skin is less acidic than skin of young adults, using a new non-invasive microscopy technique called fluorescence lifetime imaging. Further, we have found that applying acidic solutions to moderately aged skin restores skin acidity and normal lipid processing, thus improving the epidermal barrier. These experiments will study what mechanisms in the skin cause its uppermost layer to be acidified in young skin, what changes occur in aged skin that cause this acidification to be lost, and what therapies work best to restore acidity and a normal epidermal barrier to aged skin. These studies will show that it is possible to identify and treat a major cause of skin disease in the aged.

描述（由申请人提供）：老化皮肤通常患有炎症性皮肤病或干燥症/湿疹，这些疾病可以追溯到表皮渗透性屏障稳态受损或因表皮渗透性屏障稳态受损而加剧。与极度老龄化的个体相比，我们发现中年人类（50-80 岁）和小鼠（12-15 个月）的角质层 (SC) 酸化存在缺陷。 SC 酸化需要激活关键的 pH 敏感脂质加工酶，包括 β-GlcCer'ase（β-葡萄糖脑苷脂酶）。新生儿和成人 SC 的酸化主要是通过两种内源性机制（Na+/H+ 逆向转运蛋白 (NHE1) 和分泌性磷脂酶 (sPLA2)）的联合活性实现的，尽管每种试剂在向 SC 特定区域提供 SC 酸度方面的相对贡献尚不清楚。我们之前发现，中年小鼠表皮中 NHE1 蛋白水平和全层 SC 酸度降低。我们现在建议定义 NHE1 和 sPLA2 在酸化年轻成年小鼠和人类表皮 SC 特定区域中的相对作用，并确定异常 NHE1 或 sPLA2 表达、定位和/或功能在产生老年 SC 中出现的异常酸化中发挥什么作用。我们将定义 NHE1 和 sPLA2 在小鼠和人类皮肤中的作用，然后描述小鼠皮肤和培养的人类表皮等效物中的作用机制。最后，我们将探索一系列旨在使 SC 酸化正常化的策略，要么通过上调 sPLA2 活性，要么通过使用已批准用于人类的外源酸化剂绕过有缺陷的内源机制。假设：NHE1 转运蛋白和一种或多种 sPLA2 亚型均控制 SC 屏障整体酸化或 SC 微区酸化，其中影响屏障稳态的 pH 敏感脂质加工酶被选择性局部激活。 NHE1 和 sPLA2 在酸化正常年轻成人 SC 内的不同层和微区方面相互补充。一种或两种酸化机制的缺陷会导致中度老化表皮的功能欠佳，具体取决于与年龄相关的 pH 异常的严重程度和部位。通过增加 sPLA2 活性或应用外源酸化剂来增强 SC 酸度，将使脂质加工正常化，从而改善老化表皮中 SC 功能的临床异常。该项目的短期目标是确定老年 SC 与年轻 SC 酸度差异的病理生理机制。该项目的长期目标是通过优化控制屏障稳态的 SC 酸度来恢复老化皮肤的表皮渗透性屏障稳态。 公共健康相关性：这些实验的信息将用于优化治疗方案，以恢复老化皮肤有效的表皮屏障稳态。随着正常皮肤的老化，它往往会变得干燥。这种干燥甚至会使正常皮肤发痒，并使已经受到湿疹等常见疾病影响的皮肤变得更糟。中年人（50-75 岁）的皮肤干燥是由于表皮屏障丧失造成的，表皮屏障由皮肤最上层经过正确处理的脂质组成。反过来，处理这些脂质取决于有效酸化皮肤的最上层。我们使用一种称为荧光寿命成像的新型非侵入性显微镜技术发现，即使是中老年皮肤的酸性也低于年轻人的皮肤。此外，我们发现，在中度老化的皮肤上涂抹酸性溶液可以恢复皮肤酸度和正常的脂质加工，从而改善表皮屏障。这些实验将研究皮肤中的哪些机制导致年轻皮肤的最上层被酸化，老化皮肤发生哪些变化导致这种酸化消失，以及哪些疗法最能恢复老化皮肤的酸度和正常表皮屏障。这些研究将表明，有可能识别和治疗老年人皮肤病的主要原因。