Research progress on the roles and mechanisms of γδT cells in periodontitis

Periodontitis is a chronic infectious disease that occurs in periodontal support tissues. Plaque microorganisms are its initiating factor, while local inflammation and alveolar bone loss resulting from periodontitis are the most common causes of tooth loss. Interleukin-17 (IL-17), which plays an important role in the immune response to periodontitis, mostly originates from T helper cell 17 (Th17) and γδT cells. In periodontitis, the role of Th17 cells has been demonstrated broadly, but the role of γδT cells was not revealed until recent years. As a highly heterogeneous group of T lymphocytes, γδT cells are considered a link between innate immunity and adaptive immunity. Studies have found that γδT cells are mostly distributed in the oral epithelium near the biofilm, where they can interact with microorganisms to produce IL-17, recruit neutrophils, macrophages, etc., and participate in the host immune response to periodontitis. They also play a role in the association between periodontitis and relevant systemic diseases. In addition, γδT cells have been proven to produce tissue repair-related factors with a protective effect against periodontitis. The possible mechanism of γδT cells in periodontitis is discussed in this review.