Aging Stratum Corneum pH and Barrier Function

老化角质层pH值与屏障功能

• 批准号: 8111874
• 负责人: Theodora M Mauro
• 金额: $ 29.38万
• 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/8111874
• 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）：衰老的皮肤通常受到炎症性皮肤疾病或疾病/湿疹的折磨，可以追溯到或加剧表皮渗透性屏障稳态受损或加剧。与极年迈的个体相反，我们发现中等年龄的人（50-80岁）和小鼠（12-15 MO）患有缺陷的角质层（SC）酸化。需要SC酸化来激活关键的pH敏感性脂质加工酶，包括β-葡萄球菌（β-葡萄糖核苷酶）。新生儿和成年SC在很大程度上通过两种内源性机制的合并活性（Na+/H+抗胞剂（NHE1）和分泌磷脂酶（SPLA2）酶酸化，尽管未知每个药物在供应SC酸度对SC的特定区域的相对贡献。我们先前发现，中适中的小鼠表皮中NHE1蛋白水平和全厚度SC酸度降低。现在，我们建议在年轻的小鼠和人类表皮中定义NHE1和SPLA2在SC的酸化特定区域中的相对作用，并确定在产生年龄SC中观察到的异常酸化中的NHE1或SPLA2表达异常，定位和/或功能在产生异常酸化方面发挥作用。我们将定义NHE1和SPLA2在鼠和人类皮肤中的作用，然后描述小鼠皮肤和培养的人表皮等效物中负责任的机制。最后，我们将通过上调SPLA2活性或绕过已经批准用于人类使用的外源性酸化剂的内源性机制来探索旨在通过上调SPLA2活性或绕过有缺陷的内源性机制来归一化策略的广泛策略。假设：NHE1转运蛋白和一个或多个SPLA2同工型控制SC屏障大量酸化或SC微区的酸化，其中pH敏感的脂质加工酶会选择性地影响屏障稳态并局部激活。 NHE1和SPLA2在正常的年轻成人SC中酸化不同的层和微区域中相互补充。一种或两种酸化机制的缺陷导致表皮中适中的表皮功能次优功能，具体取决于年龄相关的pH异常的严重程度和定位。通过增加的SPLA2活性或通过施用外源酸化剂来增强SC酸度，将使脂质加工正常化，从而改善衰老表皮中SC功能的临床异常。该项目的短期目标是确定SC酸度在老年人与Young SC中不同的病理生理机制。该项目的长期目标是通过优化控制障碍稳态的SC酸度来恢复老年皮肤中表皮渗透性障碍稳态。 公共卫生相关性：这些实验将用于优化恢复老年皮肤中有效表皮屏障稳态的治疗方案。随着正常皮肤的年龄，它往往会变干。这种干燥使皮肤发痒，并使皮肤已经受到常见疾病（例如湿疹）的影响。中等年龄的人（50-75岁）的皮肤干燥是由表皮屏障的丧失引起的，该表皮屏障由皮肤上层的正确处理的脂质组成。加工这些脂质反过来取决于有效酸化皮肤的这层。我们发现，使用一种称为荧光寿命成像的新的非侵入性显微镜技术，即使是适度年龄的皮肤也比年轻人的皮肤酸度低。此外，我们发现，应用酸性溶液中适度老化的皮肤可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其上层在年轻的皮肤中酸化，在衰老的皮肤中发生了什么变化，导致这种酸化丢失，哪些疗法最有用，可以恢复酸度和正常的年龄皮肤表皮屏障。这些研究将表明，在老年人中可以识别和治疗皮肤疾病的主要原因。