The study shows that people with chronic sinusitis and nasal polyps have higher levels of the antimicrobial peptide LL‑37 and the inflammation marker IL‑8 in the polyp tissue compared to normal nasal tissue, suggesting LL‑37 is part of the local immune response in this condition.

To investigate the expressions of LL-37 and IL-8 in chronic sinusitis with nasal polyps. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical staining were used to detect the expressions of LL-37 and IL-8 in nasal polyp tissues of 31 patients with chronic sinusitis and inferior turbinate tissues of 11 patients with chronic rhinitis. LL-37 and IL-8 mRNA were all positively expressed in all nasal polyps and inferior turbinate tissues. There were significant increases of LL-37 and IL-8 mRNA expressions in nasal polyps compared with the inferior turbinate tissues (P < 0.01). There were also significant increases of positive expression rates of LL-37 and IL-8 protein in nasal polyps, compared with the inferior turbinate tissues (P < 0.01). There was a positive relationship between the mRNA and protein expressions of LL37 and IL-8 (P < 0.01). The expressions of LL-37 and IL-8 in nasal polyps suggest that they may play a role in the pathogenesis of chronic sinusitis. Besides its innate immune, LL-37 could enhance human body's anti-infected function by increasing acquired immune.