Antimicrobial lipids: Novel innate defense molecules are elevated in sinus secretions of patients with chronic rhinosinusitis

Background: Airway secretions possess intrinsic antimicrobial properties that contribute to the innate host defense of the respiratory tract These microbicidal capabilities have largely been attributed to the presence of antibacterial polypeptides However, recent investigation has indicated that host-derived lipids including cholesteryl esters also exhibit antimicrobial properties The purpose of tins study was to determine whether sinus secretions contain such antimicrobial lipids and to compare the lipid composition in patients with and without chronic rhinosinusitis (CRS) Methods: Maxillary sinus fluid was obtained via antral lavage from subjects with (seven patients) and without (nine patients) a history of CRS After specimen collection, total lipid was extracted according to Bligh and Dyer (Bligh EG and Dyer WJ, A rapid method of total hind extraction and purification, Can J Biochem Physiol 37 911-918, 1959) and lipid profiles were obtained by reverse phase high-performance liquid chromatography on an amide-embedded C18 column In addition, the neutrophil-specific antimicrobial peptides human neutrophil peptides 1-3 (HNP1-3) were quantified by Western immunoblotting Results: Lipids, including cholesteryl esters, were identified in the maxillary sinus secretions of patients with and without CRS However, levels of lipid composition differed between the two groups with CRS patients exhibiting greater amounts of all classes of lipids, reaching over 10-fold higher concentration when compared with non-CRS patients Tins increase was independent of HNP1-3 content Conclusion: Sinus secretions of patients with CRS appear to show elevated levels of antimicrobial lipids compared with controls independent from neutrophil influx Tins up-regulation suggests that host-derived lipids act as mediators of mucosal immunity in CRS Further study is necessary to determine if such antimicrobial lipids function alone or synergistically with antibacterial peptides in conferring such inherent microbicidal properties (Am J Rhinol Allergy 24, 99-104, 2010, doi 10.2500/ajra.2010.24.3444)