Upregulation of Bcl-2 in Nasal Polyps from Patients with Cystic Fibrosis

Background: Nasal polyps in patients with cystic fibrosis (CF) are believed to be phenotypically different than polyps affecting non-CF patients. The aim of this study was to investigate differences in cell cycle regulatory mechanisms between these 2 groups. In this prospective study at a tertiary care academic medical center, multiple techniques were used to confirm the upregulation of antiapoptotic Bcl-2 family proteins in CF polyps.

Methods: Nasal polyps were prospectively obtained from CF and non-CF patients. The Sigma Panorama Protein Microarray for Cell Signaling was used to identify differences in protein expression between the 2 polyp groups. Western blot analysis confirmed altered expression of a subset of these proteins. Immunohistochemical staining was performed on archived tissue to further investigate B-cell lymphoma 2 protein (Bcl-2) expression. Following review by a pathologist, slides were digitized using an Aperio™ ScanScope XT system and staining intensity was quantified with the Positive Pixel Count algorithm. The mean staining intensity for each polyp group was compared.

Results: The protein microarray suggested a greater than 2-fold upregulation of Bcl-xl in CF polyps relative to non-CF polyps. Western blot analysis confirmed the upregulation in CF polyps of Bcl-2, a more commonly studied protein analog of Bcl-xl. The CF polyp group was noted to have a higher quantitative intensity of immunohistochemical staining for Bcl-2 compared to the non-CF group (p < 0.05).

Conclusion: Through multiple modalities of protein investigation, we have demonstrated an upregulation of Bcl-2 family proteins in CF polyps relative to polyps from non-CF patients.