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(申请人提供)：老化的皮肤通常受到炎症性皮肤病或干燥症/湿疹的困扰，这些疾病可以追溯到或加剧受损的表皮通透性屏障稳态。与极老年个体相比，我们发现中老年人类(50-80岁)和小鼠(12-15个月)患有缺陷性角质层(SC)酸化。SC酸化是激活关键的对pH敏感的脂质处理酶所必需的，包括β-GlcCer‘ase(β-葡萄糖脑苷酶)。新生儿和成人SC的酸化主要是通过两种内源性机制的联合作用，即Na+/H+逆向转运体(NHE1)和分泌型磷脂酶(SPLA2)，尽管每种因素在向SC的特定区域提供SC酸度方面的相对贡献尚不清楚。我们先前发现，NHE1蛋白水平和全层SC酸度在中等年龄的小鼠表皮中降低。我们现在建议确定NHE1和sPLA2在青年小鼠和人类表皮中对SC特定区域的酸化中的相对作用，并确定NHE1或sPLA2的异常表达、定位和/或功能在老年SC异常酸化中所起的作用。我们将确定NHE1和sPLA2在小鼠和人皮肤中的作用，然后描述在小鼠皮肤和培养的人表皮等价物中的相关机制。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，要么通过绕过有缺陷的内源性机制，使用已被批准用于人类的外源性酸化剂。假设：NHE1转运体和一个或多个sPLA2亚型都控制SC屏障整体酸化，或SC微域的酸化，其中影响屏障动态平衡的对pH敏感的脂处理酶被选择性和局部激活。NHE1和sPLA2在酸化正常青年SC的不同层和微区方面相辅相成。一种或两种酸化机制的缺陷导致中老年表皮功能不佳，这取决于与年龄相关的pH异常的严重程度和部位。无论是通过增加sPLA2活性，还是通过应用外源性酸化剂来增强SC的酸性，都将使脂质处理正常化，从而改善老年表皮中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，恢复老化皮肤的表皮通透性屏障稳态。 公共卫生相关性：来自这些实验的信息将被用于优化治疗方案，以恢复老年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。这种干燥甚至会让正常的皮肤发痒，并使已经受到湿疹等常见疾病影响的皮肤变得更糟。中老年人(年龄50-75岁)的皮肤干燥是由于皮肤最上层的表皮屏障的丧失造成的，表皮屏障由正确处理的脂肪组成。反过来，这些脂肪的处理依赖于有效地酸化皮肤的这一最上层。我们发现，使用一种名为荧光寿命成像的新的非侵入性显微镜技术，即使是中等年龄的皮肤也比年轻人的皮肤酸性更弱。此外，我们还发现，将酸性溶液应用于中等年龄的皮肤可以恢复皮肤的酸度和正常的脂肪处理，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年轻皮肤最上层的酸化，衰老皮肤发生了什么变化，导致这种酸化消失，以及什么疗法最有效地恢复酸度和衰老皮肤的正常表皮屏障。这些研究将表明，识别和治疗老年人皮肤病的主要原因是可能的。