The Contribution of the Hypoxia Inducible Factor-1α Axis to Periodontitis.

Periodontitis is a complex, multifactorial inflammatory condition characterized by progressive destruction of the periodontal supporting structures. It profoundly affects oral health, esthetics, and masticatory function and is increasingly recognized as a contributing risk factor for systemic disorders. Deep periodontal pockets establish a severely hypoxic microenvironment induced by periodontal pathogens, increased oxygen consumption of infiltrated inflammatory cells, and accompanying periodontal vascular changes. The cellular response to hypoxia is centrally regulated by hypoxia-inducible factor 1 alpha (HIF-1α), which is also recognized as a critical factor driving the progression of periodontal tissue destruction. In vivo and in vitro studies have shown the upregulation of HIF-1α in both animal periodontitis models and clinical samples from individuals with periodontitis, where its expression correlates positively with deteriorating clinical periodontal parameters. Experimental and clinical studies using mouse conditional knockout models, selective small-molecule inhibitors, and human-derived materials have demonstrated clear causal roles for hypoxia-driven HIF-1α signaling in the progression of periodontitis. This conclusion is supported by mechanistic evidence demonstrating that HIF-1α induces aberrant neovascularization, enhances osteoclastogenesis leading to subsequent alveolar bone resorption, and promotes M1 macrophage polarization along with proinflammatory cytokine production. Hypoxia, via HIF-1α, synergistically acts with periodontal pathogens to amplify periodontal inflammation and oxidative stress, driving persistent extracellular matrix destruction in periodontal tissues. This critical review summarizes recent findings, using in vitro and in vivo approaches using animal and human-derived materials, on the role of hypoxia, primarily through the HIF-1α pathway, in periodontitis pathogenesis as well as the potential of hypoxia-based strategies and targeted modulation of HIF-1α signaling through HIF-1α stabilizers for managing periodontitis and promoting periodontal regeneration, while highlighting the existing gaps in our understanding and the limitations of current research, which can serve as a foundation for guiding future studies in this area.