HIF-1alpha Mediated Wound Healing in Periapical Lesion

描述（由申请人提供）：根尖周病变是颌内感染引起的炎症，最终导致牙根尖周围的骨破坏。根尖周围病变通常难以治疗，需要再治疗，在最坏的情况下，需要拔牙。因此，迫切需要新的治疗方法来改善根尖周围病变的愈合。该项目的长期目标是确定在感染诱导炎症和骨破坏后调节伤口愈合的分子网络。我们的初步研究表明，感染常见根管病原体的toll样受体2 (TLR2)/白细胞介素-10 （IL-10）双缺陷（dKO）小鼠表现出急性根尖周围病变，随后表现出自发的伤口愈合，主要是骨再生。dKO小鼠的愈合反应与病变中HIF-1a（缺氧诱导因子1 α）表达上调和促炎M1和序列激活密切相关抗炎M2巨噬细胞。这些发现表明HIF-1a的激活是改善根尖周围伤口愈合的关键因素。该建议的中心假设是HIF-1a激活通过诱导M1巨噬细胞激活，随后出现M2以促进病变的最终清除，从而导致根尖周围伤口愈合。相反，HIF-1a激活失败导致M1激活失败，随之而来的是M2巨噬细胞激活延迟和极化，从而导致慢性炎症和根状肉芽肿。因此，HIF-1a介导的反应是开发改善根尖周围伤口愈合的新疗法的靶标途径。本探索性提案的总体目标是确定HIF-1a激活是否可预测地诱导免疫功能正常（WT）小鼠的根尖周围病变。这一目标将通过两个具体目标来实现。目的1是评估HIF-1a调节对WT小鼠根尖周围病变形成和愈合的影响。慢病毒载体编码HIF-1a shRNA和HIF-1a的组成活性形式将用于调节HIF-1a的活性。AIM 2旨在确定内源性HIF-1a在体内对巨噬细胞活化和表型的作用。HIF-1a在dKO小鼠中失活，内源性HIF-1a通过化学抑制脯氨酰羟化酶被激活，以测量对巨噬细胞活化和感染过程的影响。脯氨酰羟化酶是HIF-1激活所必需的。这些研究将为HIF-1a在根尖周围病变中的基本作用提供新的信息，这是一种涉及M1/M2顺序巨噬细胞激活的新型伤口愈合途径，并证明HIF-1a在牙槽炎中的治疗潜力。这些结果是针对新的治疗策略，以改善牙槽骨感染的愈合过程，这将有潜在的应用于其他慢性纤维化和肉芽肿性疾病。

DESCRIPTION (provided by applicant): A periapical lesion is an infection-induced inflammation within the jaws that ultimately results in the destruction of bone that surrounds the apex of the tooth root. Periapical lesions are often refractory to treatment and require retreatments or, in worst case, tooth extraction. Thus, there is an acute need for novel therapeutic approaches that improve the healing of periapical lesions. The long-term goal of this project is to identify the molecular networks that regulate wound healing after infection-induced inflammation and bone destruction. Our preliminary studies showed that the Toll-like receptor 2 (TLR2)/Interleukin-10 (IL-10) double deficient (dKO) mouse infected with common endodontic pathogens exhibits an acute periapical lesion that subsequently exhibiting spontaneous wound healing principally bone regeneration The healing response present in dKO mice is strongly associated with up-regulation of HIF-1a (hypoxia inducible factor 1 alpha) expression in the lesion and sequential activation of proinflammatory M1 and anti-inflammatory M2 macrophages. These findings suggest that HIF-1a activation is a key element for improved periapical wound healing. The central hypothesis of this proposal is that HIF-1a activation leads to periapical wound healing via induction of M1 macrophage activation followed by emergence of M2 to facilitate final clearance of the lesion. Conversely, failure of HIF-1a activation results in failue of M1 activation followed by delayed and polarized M2 macrophage activation, which leads to chronic inflammation and radicular granuloma. Thus, the HIF-1a- mediated response is a target pathway for the development of novel therapeutics for improving periapical wound healing. The overall goal of this exploratory proposal is to determine whether HIF-1a activation will predictably induce periapical lesion in immunocompetent (WT) mice. The goal will be achieved through two specific aims. AIM 1 is to assess the impact of HIF-1a modulation on periapical lesion formation and healing in WT mice. Lentiviral vectors coding HIF-1a shRNA and constitutively active form of HIF-1a will be used to modulate HIF-1a activity. AIM 2 is to determine the role of endogenous HIF-1a on macrophage activation and phenotype in vivo. HIF-1a will be inactivated in dKO mice, and endogenous HIF-1a will activated by chemically inhibiting prolyl hydroxylase that is essential for HIF-1 activation in order to measure the effect on macrophage activation and the course infection. The proposed studies will provide new information about the fundamental role HIF-1a in periapical lesions, which is a novel wound healing pathway that involves M1/M2 sequential macrophage activation, and demonstrate a therapeutic potential of HIF-1a in dentoalveolar inflammation. These outcomes are targeted to novel treatment strategies to improve the healing process in dentoalveolar infections that will have potential application in other chronic fibrotic and granulomatous diseases.