HIF-1alpha Mediated Wound Healing in Periapical Lesion

描述（由申请人提供）：根尖周病变是颌骨内感染引起的炎症，最终导致牙根根尖周围的骨质破坏。根尖周病变通常难以治疗，需要再次治疗，或者在最坏的情况下，拔牙。因此，迫切需要改善根尖周病变愈合的新型治疗方法。该项目的长期目标是确定在感染诱导的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，Toll样受体2（TLR 2）/白细胞介素-10（IL-10）双缺陷（dKO）小鼠感染常见牙髓病原体后，表现出急性根尖周病变，随后表现出以骨再生为主的自发性伤口愈合。（缺氧诱导因子1 α）在病变中的表达和促炎性M1和抗炎性M2巨噬细胞的顺序激活。这些发现表明，HIF-1a活化是改善根尖周伤口愈合的关键因素。该提议的中心假设是HIF-1a活化通过诱导M1巨噬细胞活化，随后出现M2以促进病变的最终清除，从而导致根尖周伤口愈合。相反，HIF-1a活化失败导致M1活化失败，随后是延迟和极化的M2巨噬细胞活化，这导致慢性炎症和根性肉芽肿。因此，HIF-1a介导的反应是开发用于改善根尖周伤口愈合的新疗法的靶向途径。这项探索性建议的总体目标是确定HIF-1a激活是否会可预测地诱导免疫活性（WT）小鼠的根尖周病变。这一目标将通过两个具体目标实现。目的1：探讨缺氧诱导因子-1 α（HIF-1a）对野生型小鼠根尖周病变形成和愈合的影响。编码HIF-1a shRNA和HIF-1a的组成型活性形式的慢病毒载体将用于调节HIF-1a活性。目的2探讨内源性HIF-1a对巨噬细胞活化和表型的影响。HIF-1 a在dKO小鼠中失活，内源性HIF-1 a通过化学抑制HIF-1活化所必需的脯氨酰羟化酶来活化，以测量对巨噬细胞活化和感染过程的影响。拟议的研究将提供有关HIF-1a在根尖周病变中的基本作用的新信息，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在牙槽炎症中的治疗潜力。这些结果的目标是新的治疗策略，以改善愈合过程中的牙槽感染，将有潜在的应用在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.