Abstract
INTRODUCTION: Oxidative stress plays an important role in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP). The 8-Hydroxydeoxyguanosine (8-OHdG) is a major oxidative DNA adduct, and its levels have been noted as a triggering factor for inflammation-related carcinogenesis, but have not been assessed in CRSwNP. The MAPK/ERK pathway importance in the pathogenesis of CRSwNP has previously been reported. Mutations in RAS family genes occur in neoplastic and non-neoplastic proliferative lesions, and it has been previously demonstrated that KRAS mutations do not occur in CRSwNP. OBJECTIVE: To assess the levels of 8-OHdG in nasal polyps occurring in CRSwNP, to associate these levels with clinicopathological parameters, and to investigate HRAS and NRAS hotspot mutations in the same samples. METHODS: Both the HRAS (codons 49 and 61) and NRAS (codon 61) mutations were investigated through Sanger sequencing, and the levels of 8-OHdG were determined using ELISA in 14 freshly collected snap-frozen samples of nasal polyps occurring in CRSwNP. The associations between the levels of 8-OHdG and patients' age, presence of asthma, and eosinophil counts in nasal polyps were tested. RESULTS: No mutations were detected. The association between higher levels of 8-OHdG and higher eosinophil counts was observed, whereas there was no association between it and age or the presence of asthma. CONCLUSION: Based on the results in the present cohort, higher levels of 8-OHdG, indicative of oxidative stress, are associated with higher eosinophil counts in CRSwNP. Additionally, HRAS and NRAS mutations do not occur in nasal polyps or occur at a very low frequency.