Objectives: This cross-sectional study examined the distribution and correlates of salivary secretory leukocyte protease inhibitor (SLPI) concentrations within a multinational cohort of men.
Methods: Extracellular SLPI was measured in oral gargle cell supernatants of 378 men from three countries using an ELISA-based assay. Risk factor data were collected by a questionnaire. Factors associated with SLPI were assessed using linear and logistic regression for continuous and categorical SLPI, respectively.
Results: Among men aged 18-73 years, the median SLPI concentration was 492.0 ng ml-1 (range: 2.3-1919.9). In multivariable modeling, men in Brazil and younger men (18-30 years) were more likely to have higher levels of SLPI [adjusted odds ratio (aOR) 3.84; 95% confidence interval (CI): 1.94-7.59, and aOR 3.84; 95% CI: 1.98-7.43, respectively]. Men with a self-reported sexually transmitted diseases diagnosis in the past 6 months were more likely to have higher SLPI levels (aOR 2.98; 95% CI: 1.1-7.83) and men reporting bleeding/swollen gums were less likely to have higher SLPI (aOR 0.34; 95% CI: 0.15-0.79). Similar results were observed for linear regression models.
Conclusions: Secretory leukocyte protease inhibitor concentrations varied significantly by country and decreased with increasing age. The interaction between SLPI, modifiable factors, and oral infections that influence cancer risk warrants further investigation.
Keywords: HIM Study; immune system protein; saliva; secretory leukocyte protease inhibitor.
© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.