Article
Antimicrobial peptides are highly abundant and active in post-operative pleural drainage fluids
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Published: | October 14, 2013 |
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Objective: The human lung is a non-sterile organ and therefore most surgical interventions take place in a contaminated operation field. Nevertheless, infectious complications following lung surgery are low. Antimicrobial peptides (AMP) are part of the innate immunity and have been demonstrated to kill a broad range of pathogens. Levels of AMP in the postoperative pleural fluid are currently unknown.
Methods: We collected postoperative pleural effusions after lung operations at different time points. Antimicrobial activity was tested against Gram positive and Gram negative pathogens. AMP were determined by ELISA and PCR. In additional experiments the origin of AMP was determined and the impact of proinflammatory triggers on AMP release was evaluated.
Results: Postoperative pleural effusions effectively killed Gram negative (Escherichia coli, Pseudomonas aeruginosa) as well as Gram positive (Staphylococcus aureus, Streptococcus pneumonia and Streptococcus pyogenes) pathogens. AMP were highly abundant in postoperative pleural effusions and were mainly originating from infiltrating leukocytes and pleural epithelium. Although proinflammatory cytokines were heightened in pleural fluids during the postoperative course, AMP expression could not be augmented by triggering of different Toll-like receptors ligands or IL1-β and TNF-α.
Conclusion: Herein, we provide first evidence of a high abundance of AMP in postoperative pleural fluids. These findings might serve as an explanation of the comprehensive protection against postoperative infectious complications after major lung surgery.