Longitudinal Evaluation of GCF Interleukin-18 and Periodontitis in HIV⁺ Patients

Objectives: Interleukin-18 (IL-18) is a proinflammatory cytokine which is involved in the pathogenesis of HIV disease. The purpose of this study was to investigate the relationship between IL-18 in gingival crevicular fluid (GCF) and periodontal status in HIV⁺ patients.

Methods: Medical and demographic variables including age, race, cigarette smoking, oral hygiene practices, current CD4 cell count and viral load values were recorded. Clinical measurements including gingival index (GI), plaque index, bleeding index, probing depth (PD), attachment loss (AL) and GCF samples were taken from 3 periodontitis sites (GI>0, PD>4mm, AL>2mm), 3 gingivitis sites (GI>0, PD<4mm, AL=0), 2 healthy sites (including sites with gingival recession, GI=0, PD<4mm, AL<3mm) of each of the 12 patients at baseline and 6-month visits by means of paper strips. GCF IL-18 levels were determined by sandwich enzyme-linked immunosorbent assays. SAS statistical software package was used to analyze the data.

Results: The mean amounts of IL-18 in diseased sites were significantly higher in gingivitis and periodontitis sites than in healthy sites (p<0.0001). An active site was defined as a site which had 2 mm or more attachment loss during the 6-month study period. GCF levels of IL-18 were significantly correlated with probing depth, attachment loss, CD4, viral load, age, and smoking pack years at baseline and 6-month visits (0.0001<p<0.0002). Repeated measures analysis of 10 active sites versus 86 inactive sites indicated that IL-18 levels were significantly higher in active sites than in inactive sites (p<0.0001).

Conclusions: These data indicate that sites with high GCF levels of IL-18 in HIV⁺ patients are at significantly greater risk for progression of established periodontitis. It is likely that the compromised immune system contributes to the pathogenesis of periodontitis in HIV⁺ patients.