Department of Oral and Maxillofacial Surgery, The Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
State Key Laboratory Cultivation Base of Research, Prevention and Treatment for Oral Diseases, Nanjing Medical University, Nanjing, Jiangsu, China.
Clin Transl Med. 2024 Nov;14(11):e70082. doi: 10.1002/ctm2.70082.
Bisphosphonates (BPs) are the first-line treatment to stop bone resorption in diseases, including osteoporosis, Paget's disease, multiple myeloma and bone metastases of cancer. However, BPs-related osteonecrosis of the jaw (BRONJ), characterized by local inflammation and jawbone necrosis, is a severe intractable complication. The cumulative inflammatory burden often accompanies impaired lymphatic drainage, but its specific impact on BRONJ and the underlying mechanisms remain unclear.
The mouse BRONJ model was established to assess the integrity and drainage function of lymphatic vessels by tissue clearing techniques, injected indocyanine green lymphatic clearance assay, flow cytometry analysis and histopathological staining. RNA sequencing, metabolome analysis, transmission electron microscopy and Western blotting were utilized to analyze the impacts of Zoledronate acid (ZA) on endoplasmic reticulum stress (ERS) and function of lymphatic endothelial cells (LECs). By constructing Lyve1; SIRT6 and Lyve1; ATG5 mice, we evaluated the role of ERS-induced LECs apoptosis in the progression of BRONJ. Additionally, we developed a nanoparticle-loaded ZA and rapamycin (ZDPR) to enhance autophagy and evaluated its potential in mitigating BRONJ.
The mouse BRONJ model displayed impaired lymphatic drainage, accompanied by significant local inflammation and bone necrosis. The prolonged stimulation of ZA resulted in the extension of ERS and the inhibition of autophagy in LECs, ultimately leading to apoptosis. Mechanistically, ZA activated XBP1s through the NAD/SIRT6 pathway, initiating ERS-induced apoptosis in LECs. The conditional knockout mouse models demonstrated that the deletion of SIRT6 or ATG5 significantly worsened lymphatic drainage and inflammatory infiltration in BRONJ. Additionally, the innovative nanoparticle ZDPR alleviated ERS-apoptosis in LECs and enhanced lymphatic function, facilitating inflammation resolution.
Our study has elucidated the role of the NAD/SIRT6/XBP1s pathway in ERS-induced apoptosis in ZA-treated LECs, and further confirmed the therapeutic potential of ZDPR in restoring endothelial function and improving lymphatic drainage, thereby effectively mitigating BRONJ.
Bisphosphonate-induced lymphatic drainage impairment exacerbates bone necrosis. Zoledronate acid triggers endoplasmic reticulum stress and apoptosis in lymphatic endothelial cells via the NAD+/SIRT6/XBP1s pathway. Novel nanoparticle-loaded Zoledronate acid and rapamycin enhances autophagy, restores lymphatic function, and mitigates bisphosphonates-related osteonecrosis of the jaw progression.
双膦酸盐（BPs）是治疗骨质疏松症、佩吉特病、多发性骨髓瘤和癌症骨转移等疾病中骨吸收的一线药物。然而，BPs 相关的下颌骨坏死（BRONJ），其特征为局部炎症和颌骨坏死，是一种严重的难治性并发症。累积性炎症负担常伴有淋巴引流受损，但 BRONJ 及其潜在机制仍不清楚。
通过组织透明技术、吲哚菁绿淋巴清除试验、流式细胞术分析和组织学染色，建立小鼠 BRONJ 模型，评估淋巴管的完整性和引流功能。利用 RNA 测序、代谢组分析、透射电子显微镜和 Western blot 分析唑来膦酸（ZA）对内质网应激（ERS）和淋巴管内皮细胞（LEC）功能的影响。通过构建 Lyve1; SIRT6 和 Lyve1; ATG5 小鼠，评估 ERS 诱导的 LEC 凋亡在 BRONJ 进展中的作用。此外，我们构建了负载 ZA 和雷帕霉素（ZDPR）的纳米颗粒，以增强自噬，并评估其在缓解 BRONJ 方面的潜力。
小鼠 BRONJ 模型显示出淋巴引流受损，伴有明显的局部炎症和骨坏死。ZA 的长期刺激导致 LECs 中的 ERS 延长和自噬抑制，最终导致细胞凋亡。机制上，ZA 通过 NAD/SIRT6 途径激活 XBP1s，引发 LECs 中的 ERS 诱导性凋亡。条件性敲除小鼠模型表明，SIRT6 或 ATG5 的缺失显著加重了 BRONJ 中的淋巴引流和炎症浸润。此外，创新的纳米颗粒 ZDPR 减轻了 LECs 中的 ERS 凋亡，增强了淋巴管功能，促进了炎症的消退。
本研究阐明了 NAD/SIRT6/XBP1s 通路在 ZA 处理的 LECs 中 ERS 诱导性凋亡中的作用，并进一步证实了 ZDPR 恢复内皮功能和改善淋巴引流，从而有效缓解 BRONJ 的治疗潜力。
双膦酸盐诱导的淋巴引流受损加重骨坏死。唑来膦酸通过 NAD+/SIRT6/XBP1s 途径触发淋巴管内皮细胞中的内质网应激和凋亡。负载唑来膦酸和雷帕霉素的新型纳米颗粒增强自噬，恢复淋巴管功能，减轻双膦酸盐相关性下颌骨坏死的进展。
