Siqi Zhu,1– 3,* Yajun Cui,2,3,* Weidong Zhang,2,3 Yu Ji,2,3 Lingshuang Li,2,3 Shenglei Luo,4 Jing Cui,5,6 Minqi Li2,3 

1School of Stomatology, Jinzhou Medical University, Jinzhou, People’s Republic of China; 2Department of Bone Metabolism, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University & Shandong Key Laboratory of Oral Tissue Regeneration & Shandong Engineering Research Center of Dental Materials and Oral Tissue Regeneration & Shandong Provincial Clinical Research Center for Oral Diseases, Jinan, People’s Republic of China; 3Center of Osteoporosis and Bone Mineral Research, Shandong University, Jinan, People’s Republic of China; 4Department of Oral and Maxillofacial Surgery, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, People’s Republic of China; 5Department of Oral and Maxillofacial Surgery, Jinan Stomatological Hospital, Jinan, People’s Republic of China; 6Central Laboratory, Jinan Key Laboratory of oral tissue regeneration, Shandong Provincial Health Commission Key Laboratory of Oral Diseases and Tissue Regeneration, Jinan, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Jing Cui, Department of Oral and Maxillofacial Surgery, Jinan Stomatological Hospital, Jinglv Road 101, Jinan, 250001, People’s Republic of China, Tel +86-0531-86261960, Email 2005cuijing@163.com Minqi Li, Department of Bone Metabolism, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University & Shandong Key Laboratory of Oral Tissue Regeneration & Shandong Engineering Research Center of Dental Materials and Oral Tissue Regeneration & Shandong Provincial Clinical Research Center for Oral Diseases, Wenhua West Road 44-1, Jinan, 250012, People’s Republic of China, Tel +86-0531-88382095, Email liminqi@sdu.edu.cn

Purpose: Zoledronate (ZA) stands as a highly effective antiresorptive agent known to trigger medication-related osteonecrosis of the jaw (MRONJ). Its clinical dosages primarily encompass those used for oncologic and osteoporosis treatments. While inflammation is recognized as a potential disruptor of mucosal healing processes associated with ZA, prior research has overlooked the influence of varying ZA dosages on tissue adaptability. Therefore, a deeper understanding of the specific mechanisms by which inflammation exacerbates ZA-induced MRONJ, particularly when inflammation acts as a risk factor, remains crucial.
Methods: Cell proliferation and migration of human oral keratinocytes (HOK) was analyzed after treatment with different doses of ZA and/or lipopolysaccharide (LPS) to assess their possible effect on mucosal healing of extraction wounds. Mouse periodontitis models were established using LPS, and histological changes in extraction wounds were observed after the administration of oncologic dose ZA. Hematoxylin and eosin (HE) staining and immunofluorescence were used to evaluate mucosal healing.
Results: In vitro, LPS did not exacerbate the effects of osteoporosis therapeutic dose of ZA on the proliferation and migration of HOK cells, while aggravated these with the oncologic dose of ZA treatment by inducing mitochondrial dysfunction and oxidative stress via regulating SIRT1 expression. Furthermore, SIRT1 overexpression can alleviate this process. In vivo, local injection of LPS increased the nonunion of mucous membranes in MRONJ and decreased the expression of SIRT1, PGC-1α, and MnSOD.
Conclusion: Inflammation aggravates oncologic dose of ZA-induced mitochondrial dysfunction and oxidative stress via a SIRT1-dependent pathway, enhancing the risk of impaired mucosal healing in MRONJ. Our study implies that inflammation becomes a critical risk factor for MRONJ development at higher ZA concentrations. Elucidating the mechanisms of inflammation as a risk factor for mucosal non-healing in MRONJ could inform the development of SIRT1-targeted therapies.

Keywords: MRONJ, mucosal healing, inflammation, oxidative stress, mitochondrial dysfunction, SIRT1