Molecular mechanisms of drug-induced ONJ and osteomucosal chronic wounds

描述(申请人提供)：与皮肤相比，口腔粘膜以其无疤痕和加速伤口愈合而闻名。然而，以惊人的速度积累的证据表明，某些用于治疗骨相关疾病的药物专门导致颌骨骨坏死(ONJ)并延迟口腔粘膜伤口的愈合，导致相当大的临床并发症，并损害患者的生活质量。这些药物的长期使用者，双磷酸盐(BP)和Denosumab，发生ONJ的风险更高，ONJ的临床定义是暴露的坏死骨，覆盖在口腔粘膜上至少8周未愈合。这两种药物都有共同的作用机制：它们抑制破骨细胞的功能，破骨细胞是骨吸收细胞，对骨重建至关重要。然而，这些与骨相关的药物为什么以及如何影响覆盖的口腔粘膜组织的愈合的确切机制在很大程度上尚不清楚。对药物诱导的ONJ缺乏基本的了解，可能是由于缺乏关于“骨粘膜愈合”的知识空白，骨粘膜愈合是一种软组织和硬组织作为一个实体的组合愈合过程，唯一地发生在口腔中。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，发现了包括分泌蛋白在内的一系列差异表达基因。我们进一步发展了DRONJ的小鼠模型，并发现了类似的ONJ样病变。根据我们的初步研究，我们假设骨粘膜伤口的愈合是由软组织和硬组织中的细胞通过伤口部位的分泌蛋白进行交叉相互作用来调控的，药物诱导的ONJ是通过BP和Denosumab解除这种相互作用而发展起来的，导致明显的分子变化和受损的骨粘膜愈合。这项提议的目的是：1)研究RANKL的作用，RANKL是一种重要的分泌蛋白，对 这些研究包括：1)利用基因工程小鼠进行骨重建和愈合方面的研究；2)利用高通量微阵列和蛋白质组学技术确定在BRONJ和DRONJ样皮损中通常被解除调控的基因/蛋白质；3)使用共培养系统以及我们新开发的体外骨粘膜组织结构来研究不同细胞类型之间的交叉作用。口腔粘膜组织在解剖学上与下层骨组织非常接近，提示口腔内药物诱导的ONJ可能与这两个实体在骨粘膜创伤愈合过程中的相互作用受损有关。目前的建议将有助于揭开骨粘膜伤口愈合研究中相当未被探索的领域的分子机制，并为BRONJ和DRONJ未来的治疗应用提供知识。

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.