Background

Osteoarthritis (OA) affects the entire joint, initially with a low degree of inflammation. Synovitis is correlated with the severity of OA clinical symptoms and cartilage degradation. The synovial lymphatic system (SLS) plays a prominent role in clearing macromolecules within the joint, including the pro-inflammatory cytokines in arthritic status. Scattered evidence shows that impaired SLS drainage function leads to the accumulation of inflammatory factors in the joint and aggravates the progression of OA, and the role of SLS function in OA is less studied.

Design

This review summarizes the current understanding of synovial lymphatic function in OA progression and potential regulatory pathways and aims to provide a framework of knowledge for the development of OA treatments targeting lymphatic structure and functions.

Results

SLS locates in the subintima layer of the synovium and consists of lymphatic capillaries and lymphatic collecting vessels. Vascular endothelial growth factor C (VEGF-C) is the most critical regulating factor of lymphatic endothelial cells (LECs) and SLS. Nitric oxide production-induced impairment of lymphatic muscle cells (LMCs) and contractile function may attribute to drainage dysfunction. Preclinical evidence suggests that promoting lymphatic drainage may help restore intra-articular homeostasis to attenuate the progression of OA.

Conclusion

SLS is actively involved in the homeostatic maintenance of the joint. Understanding the drainage function of the SLS at different stages of OA development is essential for further design of therapies targeting the function of these vessels.

中文翻译：

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滑膜淋巴功能在骨关节炎中的作用

背景

骨关节炎 (OA) 影响整个关节，最初炎症程度较低。滑膜炎与 OA 临床症状和软骨退化的严重程度相关。滑膜淋巴系统 (SLS) 在清除关节内的大分子方面发挥着重要作用，包括关节炎状态下的促炎细胞因子。分散的证据表明，SLS引流功能受损导致关节内炎性因子堆积，加重OA进展，SLS功能在OA中的作用研究较少。

设计

本综述总结了目前对 OA 进展中滑膜淋巴功能和潜在调节途径的理解，旨在为开发针对淋巴结构和功能的 OA 治疗提供一个知识框架。

结果

SLS位于滑膜的内膜下层，由毛细淋巴管和淋巴集合管组成。血管内皮生长因子 C (VEGF-C) 是淋巴管内皮细胞 (LECs) 和 SLS 最关键的调节因子。一氧化氮产生诱导的淋巴肌细胞 (LMCs) 和收缩功能受损可能归因于引流功能障碍。临床前证据表明，促进淋巴引流可能有助于恢复关节内稳态以减缓 OA 的进展。

结论

SLS 积极参与关节的稳态维护。了解 SLS 在 OA 发展的不同阶段的引流功能对于进一步设计针对这些血管功能的疗法至关重要。