Vitamin D decreases the secretion of eotaxin and RANTES in nasal polyp fibroblasts derived from Taiwanese patients with chronic rhinosinusitis with nasal polyps

Abstract Eosinophils are important inflammatory cells involved in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP). Vitamin D and its derivatives, in addition to their classic role as regulators of electrolytes homeostasis, have modulatory effects in immunological and inflammatory responses. Such properties suggest that vitamin D might also play a role in inflammatory airway diseases such as CRSwNP. In this study, we investigated the effect of vitamin D derivatives (calcitriol and tacalcitol) on the secretion of eotaxin and Regulated on Activation, Normal T Cell Expressed and Secreted (RANTES), the two major eosinophil chemoattractants, in fibroblasts derived from the polyps of Taiwanese CRSwNP patients. Patients diagnosed with eosinophilic CRSwNP but without malignancies or asthma and undergoing elective endoscopic sinus surgery were recruited. Three primary fibroblast cultures were established using the polyp specimens obtained from these patients. The third to eighth passages of the fibroblasts were used for in vitro studies. Nasal polyp‐derived fibroblasts were stimulated with IL‐1β (10 ng/mL) for 24 hours, followed by replacement with media alone or with calcitriol or tacalcitol (10μM) and incubation for another 24 hours. After the treatments, the levels of secreted eotaxin and RANTES were evaluated by ELISA assays. The results showed that IL‐1β could substantially stimulate the secretion of eotaxin ( p < 0.01) and RANTES ( p < 0.01) in nasal polyp‐derived fibroblasts. More importantly, this stimulatory effect was significantly suppressed by adding calcitriol ( p ≤ 0.002 for eotaxin and p ≤ 0.008 for RANTES) or tacalcitol ( p ≤ 0.009 for eotaxin and p ≤ 0.02 for RANTES). Therefore, the inhibitory effect of vitamin D derivatives on eotaxin and RANTES secretion might shed light not only on the disease mechanism, but also on the potential use of vitamin D in pharmacotherapy of Taiwanese patients with CRSwNP.