Molecular mechanisms of drug-induced ONJ and osteomucosal chronic wounds

描述（由申请人提供）：与皮肤相比，口腔粘膜因其无瘢痕和加速伤口愈合而独特。然而，越来越多的证据表明，用于治疗骨相关疾病的某些药物特异性地诱导颌骨骨坏死（ONJ）并延迟口腔粘膜的伤口愈合，导致相当多的临床并发症并损害患者的生活质量。这些药物（双膦酸盐（BP）和狄诺塞单抗）的长期使用者发生ONJ的风险较高，临床定义为暴露的坏死骨伴未愈合的覆盖口腔粘膜至少8周。这两种药物具有共同的作用机制;它们抑制破骨细胞的功能，破骨细胞是对骨重建至关重要的骨吸收细胞。然而，关于这些骨相关药物为什么以及如何损害覆盖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，可能是由于缺乏关于“骨粘膜愈合”的知识空白，“骨粘膜愈合”是软组织和硬组织作为一个实体的组合愈合过程，其独特地发生在口腔中。为了解决这一问题，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。我们进一步开发了DRONJ的小鼠模型，并发现了类似的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由软组织和硬组织中的细胞之间通过伤口部位的分泌蛋白的交叉相互作用协调的，并且药物诱导的ONJ是通过BP和狄诺塞单抗解除这种相互作用而形成的，导致明显的分子改变和骨粘膜愈合受损。本提案的目的是：1）研究RANKL的作用，RANKL是一种分泌蛋白，对 骨重建和愈合，使用基因工程小鼠; 2）鉴定基因/蛋白质，通常是去调节的BRONJ和DRONJ样病变使用高通量微阵列和蛋白质组学;和3）研究交叉之间的相互作用，不同的细胞类型使用共培养系统，以及我们新开发的骨粘液组织构建体在体外。口腔粘膜组织在解剖学上与下层骨组织非常接近，这表明口腔中药物诱导的ONJ可能与骨粘膜伤口愈合过程中这两种实体之间的受损交叉相关。目前的提议将有助于解开骨粘膜伤口愈合研究中尚未探索的领域的分子机制，并为BRONJ和DRONJ的未来治疗应用提供知识。

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.