Apoptosis and Fibrosis

说明(申请人提供)：组织纤维化可由辐射、创伤、药物或毒素引起，纤维化可发生在身体的任何部位，包括口腔粘膜、肺、肾、肝脏和皮肤。纤维化的一个特征是I型胶原(COL1)的合成增加，COL3的合成和CO1的降解都减少。收缩成纤维细胞(FB)的存在被称为肌成纤维细胞(MyoFB)，被认为是纤维化反应的标志。纤维化的另一个特征是肝细胞、肺泡上皮细胞和内皮细胞(ECs)细胞死亡增加。在肝、肺、肾纤维化中，细胞凋亡水平与纤维化程度密切相关，提示细胞凋亡直接影响纤维化的发展。决定细胞凋亡和纤维化相互作用的机制还知之甚少。EC细胞凋亡是口腔和真皮伤口愈合后期的一个显著特征，因为细胞凋亡是修剪伤口愈合过程中产生的强大血管床所必需的。在愈合的伤口中存在高水平的凋亡内皮细胞，这表明内皮-成纤维细胞的相互作用可能在瘢痕形成和纤维化结果中发挥作用。在肾、肝和博莱霉素诱导的纤维化中，已经确定了由凋亡的内皮细胞分泌的强大的旁分泌信号因子。这些因子可以直接作用于FBS，诱导其增殖、分化和胶原合成。我们假设，凋亡的内皮细胞通过分泌促进真皮MyoFB分化、胶原合成和FB增殖的因子，同时减少FBS中的胶原降解，从而促进纤维化和瘢痕形成。目前的研究将首次对真皮纤维化中凋亡的内皮细胞和胎牛血清之间的相互作用机制进行研究。目的1将在体内确立凋亡的EC作为纤维化介质的作用。在体内，通过皮内注射凋亡内皮细胞或其分泌因子后，通过监测myoFB分化、胶原合成和FB增殖来检测凋亡内皮细胞的TE效应。目的2体外研究凋亡内皮细胞与FB功能相互作用的机制。正常的人真皮FBS将暴露在来自凋亡内皮细胞的条件培养液中。将检查纤维化反应和下游信号转导。在整个实验计划中，将通过确定CO1：COL3和MMP1：TIMP1的比率来评估纤维化反应，这两个比率都是纤维化反应的已知特征。这项拟议研究的长期目标是揭示影响皮肤疤痕形成和纤维化的机制。该项目有可能对瘢痕形成中的纤维化以及其他相关疾病，如肾、肝、肺和心脏纤维化的描述不足产生重大影响。这些机制的阐明将为纤维化的治疗干预寻找机会。

DESCRIPTION (provided by applicant): Tissue fibrosis can be caused by radiation, trauma, medications, or toxins, and fibrosis can occur anywhere in the body including the oral mucosa, lung, kidney, liver, and skin. One characteristic of fibrosis is an increase in the synthesis of collagen type I (COL1) and decreases in both synthesis of COL3 and degradation of COL1. The presence of contractile fibroblasts (FB), termed myofibroblasts (myoFB), is considered a hallmark of the fibrotic response. Another hallmark of fibrosis is increased cell death of hepatocytes, alveolar epithelial cells, and endothelial cells (ECs). The level of apoptosis and degree of fibrosis have been related in hepatic, pulmonary, and renal fibrosis, suggesting that apoptotic cells directly influence the development of fibrosis. The mechanisms that dictate the interaction of apoptotic cells and fibrosis are poorly understood. EC apoptosis is a prominent feature in the latter stages of oral and dermal wound healing, as apoptosis is requisite to the pruning of the robust vascular bed that is produced during wound healing. The presence of high levels of apoptotic ECs in the resolving wound suggests that endothelial-fibroblast interactions may play a role in scarring and fibrotic outcomes. In renal, hepatic, and bleomycin-induced fibrosis, potent paracrine signaling factors secreted by apoptotic ECs have been identified. These factors can act directly on FBs to induce proliferation, myoFB differentiation, and collagen synthesis. We hypothesize that apoptotic ECs contribute to fibrosis and scar formation by secreting factors that increase dermal myoFB differentiation, collagen synthesis, and FB proliferation, while decreasing collagen degradation in FBs. The current research will provide the first examination of the mechanism of interaction between apoptotic ECs and FBs in dermal fibrosis. Aim 1 will establish a role for apoptotic EC as mediators of fibrosis in vivo. In vivo, te effect of apoptotic ECs will be examined by monitoring myoFB differentiation, collagen synthesis, and FB proliferation following intradermal injection of apoptotic ECs or their secreted factors. Aim 2 will determine the mechanism of interaction between apoptotic ECs and FB function in vitro. Normal human dermal FBs will be exposed to conditioned media from apoptotic ECs. The fibrogenic response and downstream signaling will be examined. Throughout the experimental plan, the fibrogenic response will be assessed by determining the ratios of COL1:COL3 and MMP1:TIMP1, both known characteristics of a fibrotic reaction. The long term goal of the proposed research is to uncover the mechanisms that influence scar formation and fibrosis in skin. This project has the potential to have a significant impact on the understating o fibrosis in scar formation as well as other related conditions, such as renal, hepatic, pulmonary, and cardiac fibrosis. Elucidation of these mechanisms will identify opportunities for therapeutic intervention in fibrosis.