Titanium implants trigger extra-periodontal T cell-mediated immunity

Peri-implant inflammation and periodontitis share a common etiology rooted in periodontopathic bacterial invasion, with periodontitis notably linked to systemic inflammatory comorbidities involving T cells. However, the intricate processes within the peri-implant microenvironment and systemic repercussions of implants, particularly related to implant materials, remain inadequately understood. We aim to elucidate the impact of contact with titanium materials, widely employed in dental implants for their high biocompatibility and excellent corrosion resistance, on diverse T cell subpopulations. This study adopts a comprehensive approach, encompassing (1) transcriptomic profiling of peri-implant epithelium in a rat model, (2) examination of phenotypic and functional changes in T cell immunity in human blood cells cultured on titanium discs, and (3) in vivo validation of T cells in implanted mice. Transcriptomic evidence and functional in vitro results revealed that exposure to titanium materials promoted T cell activation and differentiation towards inflammatory subsets, and escalated the secretion of corresponding cytokines. In vivo results showed that most of the gingiva-extracted T cells were activated in both healthy and implanted mice, the latter exhibiting significant lymphadenitis. High-dimensional flow cytometric findings in the in vivo lymphadenitis model indicated titanium-induced T cell immunity, involving preferential activation of Th1, Th17, and Tc1 cells over Tregs in adjacent lymph nodes within three days after implant placement. These findings highlight the pivotal role of T cells in the initiation of peri-implant inflammation, emphasizing the need to understand extra-periodontal inflammatory complications associated with implant surgeries. Our study provides a foundation for future therapeutic strategies targeting T cell responses to enhance the success and longevity of dental implant treatments.