Titanium Particles Modulate Lymphocyte and Macrophage Polarization in Peri-Implant Gingival Tissues

Area of Science:

• Biomaterials Science
• Immunology
• Dental Implantology

Background:

• Titanium dental implants are used to replace missing teeth.
• Titanium particle release may trigger immune responses, potentially causing implant failure.
• The immune microenvironment's role in titanium particle-induced peri-implant inflammation is not well understood.

Purpose of the Study:

• To investigate the immune microenvironment in peri-implant tissues.
• To determine the effect of titanium particles on immune cell modulation.
• To elucidate the mechanisms underlying dental implant failure due to immune responses.

Main Methods:

• Whole transcriptome analysis of peri-implant gingival tissues from patients with failed implants, successful implants, and no implants.
• Gene set enrichment analysis, functional clustering, and pathway analysis.
• Hematoxylin and eosin (H&E) and immunohistochemistry (IHC) staining for titanium particles and immune cells.
• In vitro validation of cytokine expression in macrophages.

Main Results:

• Gene set enrichment analysis identified differential expression in macrophage M1/M2 polarization and lymphocyte proliferation.
• Immune response pathways were significantly enriched in comparisons involving failed and successful implants versus no implants.
• Increased infiltration of lymphocytes and macrophages, along with titanium particles, was observed in failed implant tissues.
• In vitro studies showed increased IL-1β, IL-8, and IL-18 expression by macrophages upon exposure to titanium particles.

Conclusions:

• Titanium particles modulate lymphocyte and macrophage polarization in peri-implant gingival tissues.
• These immune cell alterations contribute to the understanding of osteoblast-osteoclast activity imbalance.
• The findings provide insights into the failure of dental implant osseointegration.