The alarm secretory leukocyte protease inhibitor increases with progressive metabolic dysfunction.

Background: Secretory leukocyte protease inhibitor (SLPI) is an alarm antiprotease secreted by neutrophils and mucous membranes that potently inhibits the inflammatory cascade; however, the role of SLPI in human disease remains largely unknown. We hypothesized that SLPI is related to chronic low-grade inflammatory diseases, such as metabolic syndrome (MS) or type-2 diabetes (T2DM).

Methods: We examined associations between circulating SLPI (ELISA) and quantitative traits of MS (ATPIII criteria) in 261 Caucasian men with various degrees of metabolic dysfunction. Subjects had neither MS nor T2DM (n=140), either diagnosis (n=44) or both diagnoses (n=77).

Results: Circulating SLPI increased with progressive metabolic dysfunction, with a mean increase of 4.4 ng/ml (95% IC 2.4 to 6.3 ng/ml; p<0.001) for each unit increase in the criteria used to define MS. Circulating SLPI showed independent associations with uric acid [β=5.1 (95% CI 3.4 to 6.7), p<0.00001], serum lipids, pulse pressure and inflammatory markers.

Conclusions: Circulating SLPI increases with progressive metabolic dysfunction and is related to metabolic and inflammatory parameters in men.