Molecular mechanisms of drug-induced ONJ and osteomucosal chronic wounds

描述（由申请人提供）：与皮肤相比，口腔黏膜以其无疤痕和加速伤口愈合而闻名。尽管如此，越来越多的证据表明，某些用于治疗骨相关疾病的药物会特异性地诱发颌骨骨坏死（ONJ）并延迟口腔黏膜伤口愈合，导致相当多的临床并发症并损害患者的生活质量。长期服用双膦酸盐（BP）和地诺单抗（denosumab）的患者发生ONJ的风险更高，临床定义为暴露的坏死骨伴未愈合的口腔黏膜覆盖至少8周。两种药物具有共同的作用机制；它们抑制破骨细胞的功能，骨吸收细胞对骨重塑至关重要。然而，这些与骨相关的药物为什么以及如何损害口腔粘膜组织愈合的确切机制在很大程度上是未知的。对药物诱导的ONJ缺乏基本的了解可能是由于对“骨粘膜愈合”知识的缺失，“骨粘膜愈合”是一种软硬组织作为一个实体的组合愈合过程，只发生在口腔中。为了解决这个问题，我们使用BRONJ小鼠模型在骨粘膜损伤部位进行了高通量微阵列分析，发现了一系列差异表达的基因，包括分泌蛋白。我们进一步建立了小鼠DRONJ模型，发现了类似的onj样病变。基于我们的初步研究，我们假设骨粘膜伤口愈合是通过伤口部位的分泌蛋白在软硬组织细胞之间的交叉相互作用来协调的，而药物诱导的ONJ是通过BP和denosumab解除这种相互作用而产生的，导致明显的分子改变和骨粘膜愈合受损。本研究的目的是：1)研究RANKL的作用，RANKL是一种重要的分泌蛋白

DESCRIPTION (provided by applicant): Oral mucosa is uniquely known for its scarless and expedited wound healing compared to skin. Nonetheless, lines of evidence accumulate at the alarming rate that certain drugs used to treat bone- associated diseases specifically induce osteonecrosis of the jaw (ONJ) and delay wound healing of oral mucosa, leading to considerable clinical complications and compromising the patients' quality of life. The long- term users of these drugs, bisphosphonates (BP) and denosumab, are at the higher risk of developing ONJ, clinically defined as exposed necrotic bone with unhealed overlaying oral mucosa for at least 8 weeks. Both drugs have the common mechanisms of actions; they inhibit functions of osteoclasts, bone resorbing cells that are critically important for bone remodeling. However, the exact mechanisms as to why and how these bone- related drugs compromise the healing of the overlaying oral mucosal tissues are largely unknown. The lack of fundamental understanding in drug-induced ONJ is presumably due to the missing gaps in knowledge about "osteomucosal healing," a combinatorial healing process of the soft and hard tissues as one entity that uniquely occurs in the oral cavity. To address this issue, we performed the high-throughput microarray analysis using the BRONJ mouse model at the sites of osteomucosal wounds and found series of differentially expressed genes including secretory proteins. We further developed a mouse model for DRONJ and found similar ONJ-like lesions. Based on our preliminary studies, we hypothesize that the osteomucosal wound healing is orchestrated by cross interactions among cells in soft and hard tissues via secretory proteins at the site of wound, and that drug-induced ONJ is developed by deregulating such interactions by BP and denosumab, leading to distinct molecular alterations and impaired osteomucosal healing. The objectives of this proposal are: 1) to investigate role of RANKL, a secretory protein important for bone remodeling and healing, using genetically engineered mice; 2) to identify genes/proteins that are commonly deregulated in BRONJ- and DRONJ-like lesions using the high-throughput microarray and proteomics; and 3) to investigate the cross interactions between different cell types using co-culture systems as well as our newly developed osteomucosal tissue constructs in vitro. Oral mucosal tissues are anatomically situated in close proximity to the underlying bone tissues, suggesting that the drug-induced ONJ in the oral cavity may be associated with the impaired cross-talks between these two entities during the osteomucosal wound healing processes. Current proposal would help unraveling the molecular mechanisms of rather unexplored areas of research in osteomucosal wound healing and provide knowledge for future therapeutic applications to both BRONJ and DRONJ.