Oleuropein in Nasal Epithelial Cells: A Breakthrough Candidate for Anti-Inflammatory Topical Therapy.

[OBJECTIVES] This research examined interactions between oleuropein and epithelial cells in human nasal tissue.

[METHODS] As is standard practice in septorhinoplasty, nasal epithelial specimens were obtained from clinically healthy tissue. To reduce the risk of microbiological contamination, the tissue specimen was placed in a sterile 15 mL conical tube and rinsed 3 times with phosphate-buffered saline (PBS) containing a 2% (v/v) Antibiotic-Antimycotic solution, which is twice the typical working concentration. After 48 hours, the distinctive monolayer epithelial appearance of the cells became apparent, and cell proliferation was well underway. After the cultures reached confluence (about day 7), they were passed to the next round of tests. Concentrations of 200, 400, 600, 800, 1000, and 1200 µg of Oleuroein were freshly produced just before each experiment. The MTT colorimetric assay was used to quantify cell metabolic activity.

[RESULTS] The majority of the cells in the sample had a polygonal shape and were very closely packed; these features were evident in representative phase-contrast images taken 72 hours after tissue isolation. Applying a differential adhesion (preplating) step selectively preserved fast adherent mesenchymal cells, thereby enhancing the epithelial cell fraction and significantly reducing the presence of fibroblast-like cells. The association between Oleuropein concentration and cell viability was shown to be sigmoidal, according to dose-response curve analysis. According to the results of the nonlinear regression analysis, the IC₅₀ value was 1023 µg/mL, indicating that lower concentrations of Oleuropein are tolerated by primary nasal epithelial cells, while higher concentrations exhibit moderate cytotoxicity. In general, the visual findings indicate that primary nasal epithelial cells tolerate lower doses of Oleuropein well, but cellular viability is progressively impaired at higher concentrations. Between 400 and 600 µg/mL, there is a noticeable shift from mild to strong cytotoxic effects, which aligns with the dose-response profile seen in the related curve analysis.

[CONCLUSION] While recognizing the intrinsic variety of primary cultures, these observations show that epithelial-like cells were successfully isolated and enriched. At lower concentrations, oleuropein may promote wound healing in nasal epithelial cells without causing cytotoxicity. These findings could pave the way for the development of novel topical medicines to aid healing after septoplasty and rhinoplasty in humans.