Understanding synovial macrophage inflamm-aging within osteoarthritis

项目总结 患者年龄是骨关节炎发病率的主要危险因素，骨关节炎是一种退行性关节疾病。 这被认为是持续的低度炎症所致，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 炎性细胞因子和基质金属蛋白酶(MMPs)，加入促炎反馈循环 以及骨性关节炎症状的进展。MΦ的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M-Φ，存在相互矛盾的假设。 炎性衰老或如果衰老MΦS天生就会获得内在缺陷。这一知识鸿沟限制了我们 确定和预防M-Φ炎症老化在骨性关节炎中的作用。然而，目前还没有健壮的 体外或体内模型研究M-Φ的炎症衰老机制。细胞系或短暂的原代细胞 滑膜MΦS培养对阐明年龄特异性驱动因素没有用处，而建立的小鼠骨性关节炎模型 体内模型，如内侧半月板失稳(DMM)手术，尚未被应用于研究 M-Φ特异性炎症-衰老。缺乏对合适的模型系统的研究，阻碍了 确定导致MΦ炎症老化的因素，并最终阻碍治疗疗法的发展。 仍然有一个根本的需要，就是确定骨性关节炎中M-Φ炎症老化的根本原因，并发展 有意义的临床前工具可以对它们进行建模。利用合成纳米颗粒(NP)系统，可以直接 与滑膜MΦ(SMΦS)的接口，本建议的目的是建立体内和体外工具，以 回答我们的核心问题：SMΦ功能受年龄的影响如何？我们的工作将会向前推进 了解MΦ的炎症老化机制有两个目的；1)我们将详细说明SMΦ的表型和行为 SMΦ选择性NP探针在捕捉全部复杂性的小鼠OA模型中对受试者年龄的作用 以阐明SMΦ功能中的内在衰老效应；2)建立动态水凝胶培养模型 这在体外重建了体内反应，以确定外部环境线索在MΦ炎症老化中的作用。 我们的体外方法将是首次尝试通过模拟微环境来重建M-Φ的炎症老化 并在公认的骨性关节炎模型中用体内研究结果进行了验证。这些综合研究将评估我们的中央 假设--SMΦ的炎症衰老表型直接受年龄(内在)和 微环境(外在)线索。这个项目的总体科学影响将是产生新的证据 个体年龄对M-Φ反应的影响及一种新的体外研究工具 MΦ发炎老化。这两个结果将直接支持未来逆转新疗法的发展 SMΦS具有抗炎、抗衰老、减轻骨性关节炎症状的作用。

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.