Objective/hypothesis: Antimicrobial peptides, such as lactoferrin, are an important component of the innate immune system. They offer the body a first line defense against a wide range of invading pathogens. The diverse antipathogenic action of lactoferrin has been well characterized; however, the role that this peptide plays in chronic conditions such as rhinosinusitis remains largely unknown. This study aims to examine the level of lactoferrin expression in the nasal mucosa of patients with chronic rhinosinusitis (CRS).
Study design/methods: Nasal biopsies of 85 chronic rhinosinusitis patients, subclassified into allergic fungal sinusitis (AFS), nonallergic fungal eosinophilic sinusitis (NAFES), nonallergic, nonfungal eosinophilic sinusitis (NANFES), and CRS were studied by quantitative real-time reverse-transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay for their expression of lactoferrin at an mRNA and protein level, respectively.
Results: All groups of patients with CRS showed a decrease in lactoferrin mRNA expression relative to controls (median fold-change of CRS relative to controls, 0.1550; AFS, 0.1800; NANFES, 0.1900; and NAFES, 0.2100). All groups also showed a decreased expression of lactoferrin protein (controls, 163.3 ng/mL; CRS, 82.19 ng/mL; AFS, 104.1 ng/mL; NANFES, 118.9 ng/mL; and NAFES, 74.33 ng/mL). The most significant reduction was evident in the CRS subgroup as well as in patients with nasal polyposis at the time of surgery.
Conclusions: This is the first study of its kind to objectively examine lactoferrin expression in the nasal mucosa of CRS patients. We report a reduction in the expression of this important antimicrobial peptide at both the mRNA and protein level. Such a defect in the innate immune system may explain the predisposition of certain individuals to develop CRS and nasal polyposis, providing further insight into the pathogenesis of such conditions.