Single‐cell sequencing identifies inflammation‐promoting fibroblast–neutrophil interaction in peri‐implantitis.

Aim: To reveal the cellular composition and molecular environment of the periodontal and peri‐implant inflammatory infiltrates through a single‐cell sequencing technique, which may explain the pathological difference between these two diseases. A special focus was placed on the phenotypes and potential roles of neutrophils and fibroblasts in peri‐implant/periodontal tissue immunity. Materials and Methods: High‐throughput single‐cell transcriptomic profiling of peri‐implant tissues from patients with peri‐implantitis as well as periodontal tissues from patients with periodontitis and healthy donors was performed. Immunofluorescence analysis was carried out to further validate the identified cell subtypes and their involvement in peri‐implantitis and periodontitis. Results: Based on our single‐cell resolution analysis, a quantified proportional increase of neutrophil (Neu) subtypes was shown in peri‐implantitis. Among these, a predominance of Neutro_CXCR2 was revealed. We also found the involvement of inflammation‐promoting fibroblasts as well as a predominance of CXCL8+ fibroblast–CXCR2+ neutrophil interaction in peri‐implantitis. Conclusions: Our study indicated that the predominance of CXCL8+ fibroblast–CXCR2+ neutrophil interaction might underline the enhanced host response in peri‐implantitis compared with periodontitis. This information offers a molecular basis by which fibroblast and neutrophil subtypes might be diagnostically and therapeutically targeted in peri‐implantitis. [ABSTRACT FROM AUTHOR]