Understanding synovial macrophage inflamm-aging within osteoarthritis

项目摘要 患者年龄是骨关节炎（OA）（一种退行性关节疾病）发生率的主要风险因素 这被认为是由持续的低度炎症引起的，即，“炎症老化”巨噬细胞（MΦ）， 排列在滑膜上的免疫细胞通过分泌 炎症细胞因子和基质金属蛋白酶（MMPs），加入促炎反馈回路 和OA症状的进展。MΦ功能高度依赖于环境线索，如组织 硬度、细胞外基质（ECM）组成和损伤相关分子模式（DAMP）; 然而，关于环境因素是否直接导致滑膜MΦ- 炎性老化或老化的MΦ固有地获得固有缺陷。这种知识差距限制了我们的能力， 确定和预防MΦ在OA中的炎症-衰老作用。然而，目前没有强大的 体外或体内模型研究MΦ的炎症-衰老机制。细胞系或短寿命原代细胞 滑膜MΦs培养物对于阐明体外年龄特异性驱动因子没有用，而建立的小鼠OA在体外培养中没有用。 体内模型，例如内侧半月板（DMM）手术的不稳定，尚未应用于 MΦ特异性炎症-衰老。缺乏适当的模型系统的研究， 确定驱动MΦ炎症-老化的因素，并最终阻碍治愈性治疗的发展。 目前仍然需要确定OA中MΦ炎症-老化的根本原因， 有意义的临床前工具，可以模拟它们。利用合成纳米颗粒（NP）系统， 与滑膜MΦ（SMΦs）的界面，本提案的目的是建立体内和体外工具， 解决我们的中心问题：SMΦ功能如何受到年龄的影响？我们的工作将向前推进 了解MΦ炎症-衰老机制有两个目的：1）详细描述SMΦ表型和行为， 在小鼠OA模型中使用SMΦ-选择性NP探针的受试者年龄的函数，其捕获了全部复杂性 阐明SMΦ功能的内在衰老效应，以及2）开发动态水凝胶培养模型 在体外重建体内反应，以确定外部环境因素在MΦ炎症-老化中的作用。 我们的体外方法将是第一次尝试通过微环境模拟来重建MΦ炎症老化 并在公认的OA模型中用体内发现进行验证。这些综合研究将评估我们的中心 假设SMΦ炎症-衰老表型直接受年龄（内在）和 微环境（外部）线索。该项目的总体科学影响将是产生新的证据 MΦ对孤立的外部环境线索的反应的内在年龄效应和一种新的体外研究工具 MΦ炎性老化。这两个结果将直接支持未来开发新的治疗方法，以逆转 SMΦ具有抗炎作用，减轻OA症状。

PROJECT SUMMARY Patient age is the predominant risk factor in the incidence of osteoarthritis (OA), a degenerative joint disease that is thought to result from persistent low-grade inflammation, i.e., “inflamm-aging.” Macrophages (MΦ), immune cells that line the synovial membrane, contribute to cartilage degradation through the secretion of inflammatory cytokines and matrix metalloproteinases (MMPs), adding to the proinflammatory feedback loop and progression of OA symptoms. MΦ functions are highly dependent on environmental cues, such as tissue stiffness, extracellular matrix (ECM) composition, and damage-associated molecular patterns (DAMPs); however, there are conflicting hypotheses as to whether environmental cues directly cause synovial MΦ- inflamm-aging or if aged MΦs inherently obtain intrinsic defects. This knowledge gap has limited our ability to determine and prevent the contribution of MΦ inflamm-aging in OA. However, there are currently no robust in vitro or in vivo models to study the mechanism of MΦ inflamm-aging. Cell lines or short-lived primary synovial MΦs cultures are not useful for elucidating age-specific drivers in vitro, while established murine OA in vivo models, such as destabilization of medial meniscus (DMM) surgery, have not been applied to the study of MΦ-specific inflamm-aging. The dearth of studies in suitable model systems prevents the mechanistic determination of factors driving MΦ inflamm-aging and ultimately hinders development of curative therapeutics. There remains a fundamental need to identify the underlying causes of MΦ inflamm-aging in OA and to develop meaningful preclinical tools that can model them. Utilizing synthetic nanoparticle (NP) systems that can directly interface with synovial MΦ (SMΦs), the objective of this proposal is to establish in vivo and in vitro tools that address our central question: how is SMΦ function impacted specifically by age? Our work will advance knowledge of MΦ inflamm-aging mechanisms in two aims; we will 1) detail SMΦ phenotype and behavior as a function of subject age using SMΦ-selective NP probes in a murine OA model that captures the full complexity of disease to elucidate intrinsic aging effects in SMΦ function, and 2) develop a dynamic hydrogel culture model that recreates in vivo responses in vitro to identify the role of extrinsic environmental cues in MΦ inflamm-aging. Our in vitro approach will be the first attempt in recreating MΦ inflamm-aging through microenvironment mimicry and validated with in vivo findings in an accepted OA model. These combined studies will assess our central hypothesis—that the SMΦ inflamm-aging phenotype is directly regulated by both age (intrinsic) and microenvironment (extrinsic) cues. The overall scientific impact of this project will be generation of new evidence of intrinsic age effects on MΦ response to isolated extrinsic environmental cues and a novel in vitro tool to study MΦ inflamm-aging. Both outcomes will directly support future development of novel therapeutics to reverse SMΦs inflamm-aging and decrease OA symptoms.