Exploring the therapeutic mechanisms of proinflammatory myelin-laden macrophages retention in the injured spinal lesion core

项目摘要 脊髓损伤（SCI）的进展可分为急性期和慢性期。在原发伤之后， 骨髓源性巨噬细胞（BMDM）浸润到损伤中心，在那里它们吞噬髓鞘碎片 成为促炎性的充满髓鞘的巨噬细胞（Mye-M）。Mye-M在受损的核心中积聚 密集，几乎无限期地占据整个受伤区域的震中，这将导致：1） 它们阻止轴突的进入和生长，从而抑制髓鞘再生。2)它们失去了正常的吞噬细胞 死亡细胞和细胞碎片的能力，这可能会加剧炎症微环境。3)他们 释放炎症介质，引发炎症级联反应，阻止组织再生。我们 数据表明，当BMDM β吞噬髓磷脂碎片时，它们的迁移潜力被直接抑制。我们 近年来有报道称，损伤脊髓中新生的微血管及其衬里内皮细胞（EC）， 能够吞噬髓磷脂碎片内皮细胞（Mye-ECs）对髓鞘碎片的吞噬显著增加了内皮细胞的沉积， 细胞外基质（ECM），如胶原蛋白和纤连蛋白，其可以作为促进细胞增殖的外源性因子。 Mye-M-ECs之间的粘附作用导致Mye-M-ECs在损伤的病变中滞留。我们的中央 假设Mye-M蛋白在受损核心中的滞留是由内在和外在机制介导的， 通过ECM粘附促进Mye-M细胞保留。拟议项目的目的是调查 Mye-M囊膜隔离的潜在机制，并确定靶向Mye-M囊膜的治疗策略。 损伤部位，这可能会恢复正常的Mφ功能，并导致病变解决的改善。的理由 这项研究是基于初步调查，证明Mye-M通过 病变内的内在（M β产生）和外在（环境）机制的混合。我们的中央 将在以下具体目标中检验这一假设：1）研究髓鞘碎片是否直接或通过 自分泌途径，抑制BMDM细胞迁移能力，促进其病变保留; 2）确定 由Mye-EC在受损核心中产生的粘附性ECM是否破坏Mye-EC的保留;以及3） 研究是否靶向Mye-Mφ并随后将其表型转换为修复性 表型促进组织愈合。这项研究是创新的，因为我们提出，炎症性Mye- 被困在受伤的脊髓损伤内的脊髓损伤有助于慢性SCI损伤，阻止了脊髓损伤的完全消退。 伤口这项工作意义重大，因为目标1和目标2将确定管理 Mye-Mφ保留，而Aim 3将展示解决慢性SCI炎症的新策略 和损伤。这将对确定新的治疗策略产生积极的影响， 这些干预不仅用于治疗SCI，而且用于产生髓鞘碎片的其他脱髓鞘疾病。

PROJECT SUMMARY Spinal cord injury (SCI) progression can be divided into acute and chronic phases. Following the primary injury, bone marrow-derived macrophages (BMDMɸ) infiltrate to the injured epicenter where they engulf myelin debris to become proinflammatory myelin-laden macrophages (Mye-Mϕ). Mye-Mɸ accumulate in the injured core densely and occupy almost entire epicenter of injured area indefinitely, which would consequently result in: 1) They prevent the entry and growth of axons, which inhibits remyelination. 2) They lose their normal phagocytic capacity for dead cells and cellular debris, which may exacerbate the inflammatory microenvironment. 3) They release inflammatory mediators, which trigger an inflammatory cascade that prevents tissue regeneration. Our data indicated that the migratory potential of BMDMɸ is directly suppressed when they engulf myelin debris. We resently reported that newly formed microvessels and their lining endothelial cells (ECs) in the injured cord are able to engulf myelin debris. Myelin debris engulfment by ECs (Mye-ECs) significantly increased deposition of extracellular matrices (ECM) such as collagen and fibronectin which may serve as extrinsic factor to promote the adhesive interaction between Mye-Mϕ-ECs and lead to Mye-Mϕ retention in the injured lesion. Our central hypothesis is that Mye-Mϕ retention in the injured core is mediated by intrinsic and extrinsic mechanisms which promote Mye-Mɸ retention through ECM adhesion. The objective of the proposed project is to investigate the underlying mechanisms of Mye-Mϕ sequestration and identify treatment strategies that target Mye-Mɸ in the injury site, which may restore normal Mφ functions and lead to improvements in lesion resolution. The rationale for the proposed research is based on preliminary investigations that demonstrate Mye-Mɸ become ‘trapped’ via a mix of intrinsic (Mɸ produced) and extrinsic (environmental) mechanisms within the lesion. Our central hypothesis will be tested in the following specific aims: 1) To study whether myelin debris, either directly or via autocrine pathways, inhibits BMDMϕ migration ability which promotes their lesion retention; 2) To determine whether adhesive ECM produced by Mye-ECs in the injured core aggravates Mye-Mɸ retention; and 3) To investigate whether targeting Mye-Mφ and subsequently switching their phenotype toward a reparative phenotype promotes tissue healing. This research is innovative because we propose that inflammatory Mye- Mɸ trapped within the injured spinal cord lesion contribute to the chronic SCI lesion, preventing full resolution of the injury. This work is significant because Aims 1 and 2 will identify the underlying mechanisms governing Mye-Mφ retention, while Aim 3 will demonstrate novel strategies for the resolution of chronic SCI inflammation and lesions. This will have the positive impact of identifying novel therapeutic strategies for therapeutic interventions not only to treat SCI but also to other demyelinating disorders that generate myelin debris.