HIF-1α抑制人牙周膜成纤维细胞内毒素耐受在缺氧加重牙周炎中的作用和机制研究

Our previous studies found that hypoxia can aggravate the injury of periodontitis, but the mechanism is undefined. Evidences indicate that endotoxin tolerance play an important role in sustaining the immunological homeostasis of periodontal tissues and manipulating the pathogenesis of periodontitis. Aforementioned studies detected that human periodontal ligament fibroblasts (hPDLF), the main composition cells of periodontal ligament, exist endotoxin tolerance in normoxia, while the abilities of endotoxin tolerance were inhibited with a significant increase in the secretion of inflammatory cytokines in hypoxia, which may be one reason for worsening lesions of periodontitis in plateau. Further studies showed that hypoxia is mainly induced through hypoxia inducible factor-1 alpha (HIF-1α) to inhibit the endotoxin tolerance of hPDLF, but the mechanism is still unclear. At present many studies have confirmed that hypoxia can interact with inflammation, that is, the interaction between HIF-1α and inflammatory reaction transcription regulation factor nuclear factor-Kappa B (NF-κB) can modulate the secretion of inflammatory modulators in host cells. Our study found that the activity of NF-κB was increased when the endotoxin tolerance of hPDLF was inhibited by hypoxia. In view of this, this study intends, on the basis of the previous research, on the one hand to explore the molecular mechanism of hypoxia suppressing the endotoxin tolerance of hPDLF through flow cytometry, western blot and other experimental methods in vitro; on the other hand to observe that the role in promoting periodontitis by the inhibition of hypoxia on endotoxin tolerance of PDLF using hypoxic rabbit periodontitis model in vivo. It can not only be helpful for clarifying the possible mechanisms of hypoxia affecting on periodontitis, but also provide new strategies and theoretical bases for the prevention and treatment of periodontitis in hypoxic environment.

牙周炎病变可因缺氧而加重，但缺氧对牙周炎的作用机制尚不明确。研究证实，内毒素耐受在维持牙周局部免疫稳态以及控制牙周炎病程中作用关键。课题组研究发现常氧时人牙周膜成纤维细胞(hPDLF)存在内毒素耐受，而缺氧时其内毒素耐受受到抑制，炎症因子分泌大量增加，这可能是缺氧加重牙周炎病变的原因之一。我们进一步研究发现缺氧通过缺氧诱导因子-1α(HIF-1α)抑制hPDLF内毒素耐受，但作用机制尚不清楚。缺氧与炎症能相互影响，同时我们发现缺氧抑制hPDLF内毒素耐受后，其核转录因子-κB(NF-κB)活性增高。鉴此，本项目拟一方面通过流式细胞技术、Western Blot等实验方法，探讨缺氧抑制hPDLF内毒素耐受的分子机制；另一方面利用缺氧兔牙周炎模型在体观察缺氧抑制PDLF内毒素耐受在加重牙周炎病变中的作用。这有助于阐明缺氧对牙周炎可能的作用机制，同时可为缺氧环境下牙周炎的防治提供理论依据。

牙周炎病变可因缺氧而加重，但缺氧对牙周炎的作用机制尚不明确。本项目紧紧围绕缺氧加重牙周炎病理机制这一重要科学问题开展研究，主要包含以下几部分：1) 通过探讨缺氧抑制人牙周膜成纤维细胞(hPDLF)内毒素耐受在牙周炎中的作用及机制研究，明确证实缺氧可以通过缺氧诱导因子-1α(HIF-1α)调节TLR4介导的下游信号通路，抑制hPDLF内毒素耐受，加重牙周组织损伤；2) 通过观察缺氧对hPDLF与外周血单个核细胞(PBMCs)共培养体系中两种细胞活性的影响及其在牙周炎发生发展中的作用，发现缺氧可以抑制共培养体系中hPDLF成骨分化，促进PBMCs破骨分化，从而加重牙周炎损伤；3) 通过探讨HIF-1α在hPDLF成骨分化中的作用，明确证实缺氧可以通过HIF-1α保持hPDLF成骨分化活性，维持牙周膜稳态；4) 通过系统研究牙龈卟啉单胞菌(P.g)LPS诱导hPDLF转录组学变化，找到了牙周炎发生发展中的部分关键致病因子。上述研究成果对于深入阐明牙周炎的病理机制提供了一定的理论基础，同时对于高原牙周炎的防治提供了新的思路。