Mechanisms of Blister Formation by Staphylococcal Toxins

葡萄球菌毒素形成水疱的机制

• 批准号: 6879167
• 负责人: John R Stanley
• 金额: $ 32.85万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6879167
• 关键词: Staphylococcus aureus; active sites; antigen antibody reaction; autoantibody; autoantigens; autoimmune disorder; blister; cadherins; chemical cleavage; conformation; exfoliative dermatitis; genetically modified animals; human subject; keratin; laboratory mouse; patient oriented research; pemphigus; protein structure function; receptor binding; receptor expression; serine proteinases; skin infection; staphylococcal exotoxin; toxin metabolism

Exfoliative toxin A (ETA), produced by Staphylococcus aureus, causes staphylococcal scalded skin syndrome (SSSS) and its more localized form, bullous impetigo. The crystal structure of ETA suggests that it is a serine protease with an inactive catalytic site which becomes activated when ETA binds a specific receptor. In pemphigus foliaceus autoantibodies that cause dysfunction of Dsg 1 cause blisters identical to those caused by ETA in the superficial epidermis of mouse and man. Therefore, we hypothesize that Dsg 1 specifically binds and activates ETA, which in turn cleaves the bound Dsg 1, resulting in blister formation. We propose that another staphylococcal toxin, exfoliative toxin B (ETB), that also causes bullous impetigo and SSSS, is also activated by, and cleaves, Dsg 1. Finally, we hypothesize that binding of ETA to Dsg 1 and/or cleavage of Dsg 1 by ETA might elicit an autoimmune response against Dsg 1, thus suggesting a mechanism for autoantibody production in PF patients. We have shown that ETA cleaves Dsg 1. Specific aim 1 will characterize this cleavage by determining if cleavage is dependent on Dsg 1 conformation, and by defining the site of cleavage and the domains of Dsg 1 needed for cleavage. Aim 2 will characterize binding of ETA to Dsg 1, and define the domains of each necessary. Aim 3 will determine, using Dsg 3 knockout and involucrin-Dsg 3 transgenic mice, if compensation by Dsg 3 can compensate for ETA-induced loss of function of Dsg 1, thereby explaining the sites of blister localization. Aim 4 contains studies designed to define the kinetics of Dsg 1 cleavage by ETA. Aim 5 will extend the results of the previous aims to include the mechanisms of action of ETB. The final aim will determine if patients with bullous impetigo and SSSS develop an antibody response against Dsg 1, if patients with pemphigus foliaceus have an enhanced immune response against ETA and ETB, and if mice injected with ETA develop an immune response against Dsg 1. These studies will provide insight regarding the molecular pathophysiology of a very common disease, bullous impetigo, and, for the first time, identify a potential trigger or exacerbating factor in a tissue-specific autoimmune disease, pemphigus.

由金黄色葡萄球菌产生的去角质毒​​素A（ETA）导致葡萄球菌烧结的皮肤综合征（SSSS）及其更本地化的形式Bullous Impetigo。 ETA的晶体结构表明，它是一种具有非活性催化位点的丝氨酸蛋白酶，当ETA结合特定受体时会被激活。 在引起DSG 1的功能障碍的Pemphigus叶子自身抗体中，导致水泡与小鼠和人表皮表皮中的ETA相同。 因此，我们假设DSG 1特异性结合并激活ETA，而ETA又裂解了结合的DSG 1，从而导致泡沫形成。 我们提出，另一种葡萄球菌毒素，脱落性毒素B（ETB）也会引起大胆的浸泡和SSSS，也被DSG 1激活和切割，DSG 1。 PF患者的自身抗体产生。 我们已经表明，ETA裂解DSG1。特定的目标1将通过确定裂解是否取决于DSG 1构象来表征这种裂解，并通过定义切割的切割位点和切割所需的DSG 1的域。 AIM 2将表征ETA与DSG 1的结合，并定义每个必要的域。 如果DSG 3敲除和依赖蛋白-DSG 3转基因小鼠，AIM 3将确定如果DSG 3的补偿可以补偿ETA诱导的DSG 1功能损失，从而解释了泡沫定位的位置。 AIM 4包含旨在定义DSG 1裂解动力学的研究。 AIM 5将扩大先前目标的结果，以包括ETB的作用机理。 The final aim will determine if patients with bullous impetigo and SSSS develop an antibody response against Dsg 1, if patients with pemphigus foliaceus have an enhanced immune response against ETA and ETB, and if mice injected with ETA develop an immune response against Dsg 1. These studies will provide insight regarding the molecular pathophysiology of a very common disease, bullous impetigo, and, for the first time, identify a potential组织特异性自身免疫性疾病Pemphigus中的触发因素或恶化因子。