Mechanisms linking periodontitis and diabetes

Background + Aims

• Matrix metalloproteinase-8 (MMP-8) is a key enzyme involved in tissue breakdown during inflammation, significantly contributing to periodontitis.
• Periodontitis is prevalent in individuals living with diabetes, and the inflammatory environment may further increase MMP-8 expression.
• Diabetes-associated periodontitis has been linked to increased inflammatory markers, but its exact molecular mechanisms need further exploration.
• The study aimed to compare MMP-8 levels in periodontal tissues from:
  • Individuals without diabetes or periodontitis.
  • Individuals with periodontitis alone.
  • Individuals with both periodontitis and living with diabetes.
• Additionally, in vitro experiments were conducted to assess how high glucose levels and bacterial stimuli influence MMP-8 expression in immune cells.

Materials + Methods

• Participants and Groups:
  • Group 1: 7 individuals without diabetes or periodontitis (control).
  • Group 2: 15 individuals with periodontitis alone.
  • Group 3: 10 individuals with both diabetes and periodontitis.
• Periodontal tissues were collected during necessary surgical procedures and analysed for MMP-8 using immunohistochemistry.
• Inclusion criteria for Groups 2 and 3:
  • Moderate to severe periodontitis (probing pocket depth (PPD) ≥6 mm and clinical attachment loss (CAL) ≥5 mm).
  • Glycaemic management was assessed for diabetic participants using HbA1c tests.
• In vitro experiments:
  • Mononuclear cells were exposed to normal (5mM) and high glucose (25mM) conditions.
  • Cells were treated with bacterial lipopolysaccharides (LPS), and MMP-8 levels were quantified via PCR and immunostaining.
• Statistical analyses included non-parametric tests to evaluate differences and trends in MMP-8 expression.

Results

• MMP-8 levels in periodontal tissues:
  • Increased across Groups 1 to 3, with the highest levels in individuals with both diabetes and periodontitis.
  • Group 3 showed significantly higher MMP-8 expression than Group 2 (p = 0.003).
• In vitro findings:
  • High glucose and bacterial stimuli synergistically increased MMP-8 expression.
  • Suggests that hyperglycaemia exacerbates periodontal inflammation by amplifying the immune response to bacterial challenges.
• MMP-8 was predominantly localised to immune cells within inflamed tissues.

Limitations