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）：老化皮肤通常受到炎性皮肤病或干燥症/湿疹的折磨，这些疾病可追溯到受损的表皮渗透性屏障稳态，或因受损的表皮渗透性屏障稳态而加重。与极老年人相比，我们发现中老年人（50-80岁）和小鼠（12-15个月）患有角质层（SC）酸化缺陷。需要SC酸化来激活关键的pH敏感性脂质加工酶，包括β-GlcCer '酶（β-葡糖脑苷脂酶）。新生儿和成人SC都酸化主要是通过两种内源性机制，Na+/H+逆向转运蛋白（NHE 1）和分泌型磷脂酶（sPLA 2）酶的组合活性，虽然在供应SC酸度的SC的特定区域的每个代理的相对贡献是未知的。我们以前发现，NHE 1蛋白水平和全层SC酸度在中度老化小鼠表皮中降低。我们现在提出确定NHE 1和sPLA 2在年轻成年小鼠和人表皮中SC的特定区域酸化中的相对作用，并确定异常NHE 1或sPLA 2表达、定位和/或功能在产生老年SC中观察到的异常酸化中起什么作用。我们将确定NHE 1和sPLA 2在小鼠和人皮肤中的作用，然后描述小鼠皮肤和培养的人表皮等同物中的负责机制。最后，我们将探索一系列旨在使SC酸化正常化的策略，无论是通过上调sPLA 2活性，还是通过使用已批准用于人类的外源性酸化剂绕过有缺陷的内源性机制。假设：NHE 1转运蛋白和一种或多种sPLA 2亚型控制SC屏障整体酸化或SC微结构域的酸化，其中影响屏障稳态的pH敏感性脂质加工酶被选择性和局部激活。NHE 1和sPLA 2相互补充，在酸化不同的层和microdomain内正常的年轻成人SC。缺陷中的一个或两个酸化机制导致次优功能在中度老化的表皮，这取决于年龄相关的pH值异常的严重程度和本地化。通过增加sPLA 2活性或通过应用外源性酸化剂来增强SC酸度将使脂质加工正常化，从而改善在老化表皮中观察到的SC功能的临床异常。该项目的短期目标是确定老年人与年轻人SC中SC酸度不同的病理生理机制。该项目的长期目标是通过优化控制屏障稳态的SC酸度来恢复老年皮肤的表皮渗透性屏障稳态。 公共卫生关系：来自这些实验的信息将用于优化治疗方案，以恢复老化皮肤中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，并使已经受到常见疾病（如湿疹）影响的皮肤变得更糟。中老年人（年龄50-75岁）的皮肤干燥是由于表皮屏障的丧失引起的，表皮屏障由皮肤最上层正确处理的脂质组成。反过来，这些脂质的处理取决于有效地酸化皮肤的最上层。我们发现，即使是中度老化的皮肤也比年轻人的皮肤酸性更低，使用一种新的非侵入性显微镜技术称为荧光寿命成像。此外，我们发现，将酸性溶液应用于中度老化的皮肤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什么机制导致其最上层在年轻皮肤中被酸化，在老年皮肤中发生什么变化导致这种酸化丧失，以及什么疗法最能恢复酸性和正常的表皮屏障。这些研究将表明，有可能确定和治疗老年人皮肤病的主要原因。