MicroRNAs: emerging players in apical periodontitis

Abstract Apical periodontitis is an inflammatory disorder of periradicular tissues developed from endodontic infections. Understanding its pathophysiology and the underlying molecular mechanisms is key to the advancement of endodontics. MicroRNAs (miRNAs), a group of evolutionarily conserved small non-coding RNAs, may be phenotypically and functionally associated with the pathogenesis of apical periodontitis. Several studies have focused on the role of miRNAs in the pulp and periradicular biology, and they have demonstrated their essential functions, such as initiating odontogenic differentiation and promoting pro- or anti-inflammatory responses in pulpitis. Up to date, over 2,000 miRNAs have been discovered in humans; however, only few have been reported to associate with apical periodontitis. Therefore, identifying miRNAs involved in diseased apical tissues and conducting functional studies are important in expanding our current knowledge of pulp and periradicular biology and exploring novel therapeutic avenues. In this review, we revisit current models of apical periodontitis and miRNA biogenesis, analyze existing evidence of the involvement of miRNAs in diseased apical tissues, and discuss their diverse functions and potential values. Based on their sheer abundance, prolonged stability in biofluid, and relative ease of sampling, miRNAs may be a useful tool to be developed as diagnostic biomarkers for apical periodontitis. Furthermore, it can be used as therapeutic targets in conjunction with conventional endodontic therapies.

摘要 根尖周炎（Apical periodontitis）是由牙髓感染引发的根尖周组织炎症性疾病。阐明其病理生理学过程与潜在分子机制，是推动牙髓病学发展的关键。微小核糖核酸（microRNAs，以下简称miRNAs）是一类进化保守的小型非编码RNA，其表型与功能或与根尖周炎的发病机制相关。已有多项研究聚焦miRNAs在牙髓及根尖周生物学中的作用，证实其可启动成牙本质分化并调控牙髓炎中的促炎或抗炎应答等重要生物学功能。截至目前，人类中已发现超过2000种miRNAs，但仅有极少数被报道与根尖周炎存在关联。因此，鉴定病变根尖组织中的相关miRNAs并开展功能研究，对于拓展我们对牙髓及根尖周生物学的认知、探索全新治疗途径具有重要意义。本综述回顾了当前根尖周炎及miRNA生物发生的研究模型，分析了miRNAs参与病变根尖组织调控的现有证据，并探讨了其多样的生物学功能与潜在应用价值。鉴于miRNAs在生物体液中丰度高、稳定性强且易于采样，其有望被开发为根尖周炎的诊断生物标志物；此外，其还可作为治疗靶点，与传统牙髓治疗手段联合应用。