HIF-1alpha Mediated Wound Healing in Periapical Lesion

描述(申请人提供)：根尖周围病变是一种感染引起的颌骨炎症，最终导致围绕牙根根尖的骨质破坏。根尖周围病变通常难以治疗，需要重新治疗，最糟糕的情况是拔牙。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的炎症和骨破坏后调控伤口愈合的分子网络。我们的初步研究表明，感染常见牙髓病原体的Toll样受体2(TLR2)/白介素10(IL-10)双缺陷(DKO)小鼠表现出急性根尖周病变，随后表现出伤口的自发愈合，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1α)的表达上调以及促炎症M1和抗炎M2巨噬细胞的激活密切相关。这些发现表明，HIF-1a的激活是促进根尖周伤口愈合的关键因素。这一建议的中心假设是，HIF-1a的激活通过诱导M1巨噬细胞的激活和M2的出现来促进根尖周围伤口的愈合，从而促进病变的最终清除。相反，HIF-1a激活失败导致M1激活失败，随后M2巨噬细胞激活延迟和极化，从而导致慢性炎症和神经根性肉芽肿。因此，HIF-1a介导的反应是促进根尖周伤口愈合的新疗法发展的靶向途径。这一探索性建议的总体目标是确定HIF-1a激活是否会可预测地导致免疫活性(WT)小鼠的根尖周围损害。这一目标将通过两个具体目标来实现。目的1评估HIF-1a对WT小鼠根尖周病变形成和愈合的影响。编码HIF-1a shRNA和构成活性形式的HIF-1a的慢病毒载体将被用来调节HIF-1a的活性。目的2确定内源性HIF-1a在体内对巨噬细胞活化和表型的影响。在dKO小鼠中，HIF-1a将被灭活，内源性HIF-1a将通过化学抑制对HIF-1激活所必需的Pro-羟基酶来激活，以衡量其对巨噬细胞激活和病程感染的影响。这项研究将提供有关HIF-1a在根尖周病变中的基础作用的新信息，这是一种涉及M1/M2顺序巨噬细胞激活的新的伤口愈合途径，并展示了HIF-1a在牙槽骨炎症中的治疗潜力。这些结果针对的是新的治疗策略，以改善牙槽感染的愈合过程，这将在其他慢性纤维和肉芽肿疾病中具有潜在的应用价值。

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.