Expression of dermcidin in human sinonasal secretions

Background Antimicrobial peptides (AMPs) produced by the epithelium are important for innate immune defense. In 2001, a novel AMP dermcidin (DCD) was described with no homology to other AMPs and an expression pattern restricted to eccrine sweat glands. In contrast to other AMPs, DCD expression has not been shown to be induced under inflammatory conditions in the skin. After identifying DCD by mass spectrometry in a protein sample isolated from human nasal secretions, we sought to determine the role of DCD in innate defense of the sinonasal airway. Methods After institutional review board approval, sinonasal mucosal tissue specimens were acquired from residual clinical material obtained during sinonasal surgery and used to grow cultures in an air‐liquid interface environment. After stimulation of the cultures with various bitter compounds and phosphate‐buffered saline, airway surface liquid was collected, and a DCD‐specific enzyme‐linked immunoassay was used to quantify DCD in each sample. To localize DCD expression, ALI cultures were fixed and immunofluorescence performed against DCD, β‐tubulin IV, and Muc‐5A. Results Enzyme‐linked immunoassay showed DCD in air‐surface liquid and in clinical nasal secretion samples at concentrations comparable to eccrine sweat. There was no evidence of inducible expression with any of the tested stimulants. Confocal microscopy revealed DCD expression in sinonasal mucosal goblet cells. Conclusion This is the first report of the presence of DCD in nasal mucosa and demonstration of DCD in clinical samples of human nasal secretions at clinically relevant concentrations, which may represent a novel arm of sinonasal airway innate defense.