The modulation of the TREM-1/PGLYRP1/MMP-8 axis in peri-implant diseases

The aim of this study is to investigate the expression of sTREM-1 and its ligand PGLYRP1, as well as the expression of MMP-8 and its inhibitor TIMP-1, in peri-implant diseases. As a secondary aim, we analyzed the influence of the concomitant existence of periodontitis in the expression of these biomarkers.

This study included 77 patients (29 males and 48 females; mean age 55.0 ± 11.5), 18 having gingivitis, 16 having periodontitis, 20 having mucositis, and 23 having peri-implantitis. Patients were clinically examined, and unstimulated whole saliva was collected. sTREM-1, PGLYRP1, MMP-8, TIMP-1, and MMP-8/TIMP1 ratio were determined by ELISA.

The periodontitis group presented higher probing depth (PD) mean, and higher clinical attachment loss, compared with the other groups. The peri-implantitis group presented higher PD mean in implants compared to the mucositis group. Patients with PD ≥ 6 mm showed significantly higher levels of PGLYRP1, MMP-8, and MMP-8/TIMP-1 ratio than patients with PD < 6 mm. When all four markers were assessed, there were no significant differences between mucositis and peri-implantitis groups. Concomitant periodontitis resulted in higher significant levels of MMP-8 in patients with peri-implant disease.

We did not observe significant differences in the levels of the sTREM-1/PGLYRP1/MMP-8 axis between patients with periodontal and peri-implant diseases, suggesting that these markers are also involved in the inflammatory process around implants. Besides, the presence of periodontitis may affect the levels of MMP-8 in patients with peri-implant disease.

The sTREM-1/PGLYRP1/MMP-8 axis could be useful as potent markers in periodontal and peri-implant diseases.