THE INSULIN-LIKE GROWTH FACTOR AXIS IN OSTEOARTHRITIS

骨关节炎中的胰岛素样生长因子轴

• 批准号: 6695276
• 负责人: TERESA I. MORALES
• 金额: $ 32.52万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6695276
• 关键词: articular cartilage; chondrocytes; fibronectins; homeostasis; hormone binding protein; human tissue; immunocytochemistry; immunoelectron microscopy; insulin receptor; insulinlike growth factor; osteoarthritis; pathologic process; protein structure function; tissue /cell culture

DESCRIPTION (provided by applicant): The Insulin-like growth factors (IGFs) are key regulators of matrix homeostasis in articular cartilage, and it has been proposed that dysregulation of metabolism during osteoarthritis (OA) is due to IGF insensitivity. The IGF binding proteins (IGFBPs) can either promote or inhibit IGF activity or may act independently of IGFs. Preliminary studies by the applicant indicate that IGFBP-3 is increased during OA, as assessed directly in extracts of uncultured OA cartilage. The working hypothesis states that IGFBP-2 is Iocated on the cell membrane and acts to maintain matrix homeostasis. IGFBP-3 content in cartilage, but not IGFBP-2, increases 2-3 fold during OA. IGFBP-3 can bind to its own specific, high affinity proteins on the chondrocyte and can also bind to abundant extracellular anchoring sites. The latter include sites in the fibronectin (FN) matrix, where anchored IGFBP-3 acts to sequester IGFs. The overall effect of IGFBP-3 is to restrict IGF action and repair of cartilage. The Specific Aims are: (1) the localization of IGFBP-3, IGFBP-2, IGF-I and II and the IGF receptor (IGF-IR) during OA progression in human cartilage (immunohistochemical studies) and, as appropriate, the possible co-localization of IGF with BP-3 and FN (by immunoelectron microscopy); to examine selected interactions of IGFBP-3 and IGF in vitro; and to test isolated chondrocytes for the presence of high affinity IGFBP-3 association proteins (putative receptors); (2) changes in the levels and synthesis of the components of the IGF axis (IGFBPs, IGFs, IGFIR), as well as in the putative IGFBP-3 anchor, fibronectin, during OA; and (3) the function of the IGFBPs, as assessed by their effects on matrix synthesis and cell division. The overall function of resident IGFBPs will be determined during OA by culturing human cartilage slices and examining the role of IGFBPs by addition of IGFs and various IGF analogs that have been mutated to selectively lose their capacity to bind IGFBPs, or to lose only their ability to bind to the IGF receptor. In addition, antisense oligodeoxynucleotides will be used to block IGFBP-3, as well as blocking antibodies following permeabilization of the cartilage matrix. The long-term goal is to design plausible protocols to shift the IGF axis towards a repair mode so as to define therapeutic candidates for human OA management.

描述（由申请人提供）：胰岛素样生长因子（IGF）是关节软骨基质稳态的关键调节剂，并且已经提出骨关节炎（OA）期间的代谢失调是由于IGF不敏感。 IGF 结合蛋白 (IGFBP) 可以促进或抑制 IGF 活性，也可以独立于 IGF 发挥作用。申请人的初步研究表明，如直接在未培养的 OA 软骨提取物中评估的那样，IGFBP-3 在 OA 期间增加。工作假设指出 IGFBP-2 位于细胞膜上并起到维持基质稳态的作用。软骨中的 IGFBP-3 含量（而非 IGFBP-2）在 OA 期间增加 2-3 倍。 IGFBP-3 可以结合软骨细胞上其自身特异的高亲和力蛋白，还可以结合丰富的细胞外锚定位点。后者包括纤连蛋白 (FN) 基质中的位点，其中锚定的 IGFBP-3 起到隔离 IGF 的作用。 IGFBP-3 的总体作用是限制 IGF 的作用和软骨的修复。具体目标是：(1) 在人类软骨 OA 进展过程中 IGFBP-3、IGFBP-2、IGF-I 和 II 以及 IGF 受体 (IGF-IR) 的定位（免疫组织化学研究），并酌情确定 IGF 与 BP-3 和 FN 可能的共定位（通过免疫电子显微镜）；体外检查 IGFBP-3 和 IGF 的选定相互作用；并测试分离的软骨细胞是否存在高亲和力 IGFBP-3 关联蛋白（推定受体）； (2) OA 期间 IGF 轴成分（IGFBP、IGF、IGFIR）以及假定的 IGFBP-3 锚、纤连蛋白的水平和合成发生变化； (3) IGFBP 的功能，通过其对基质合成和细胞分裂的影响来评估。常驻 IGFBP 的整体功能将在 OA 期间通过培养人软骨切片并通过添加 IGF 和各种 IGF 类似物来检查 IGFBP 的作用来确定，这些 IGF 类似物已发生突变，选择性丧失与 IGFBP 结合的能力，或仅丧失与 IGF 受体结合的能力。此外，反义寡脱氧核苷酸将用于阻断 IGFBP-3，以及在软骨基质透化后阻断抗体。长期目标是设计合理的方案，将 IGF 轴转向修复模式，从而确定人类 OA 管理的候选治疗方案。