Osteitis is associated with P-glycoprotein overexpression in patients with chronic sinusitis without nasal polyps.
BACKGROUND
P-glycoprotein (P-gp) is a membrane-bound efflux pump that is up-regulated in eosinophilic chronic rhinosinusitis and participates in epithelial cytokine secretion. Osteitis is associated with eosinophilic inflammation and may represent a method to predict patients with P-gp overexpression. The purpose of this article was to determine whether P-gp overexpression and increased osteitis scores are associated in patients with chronic rhinosinusitis (CRS).


METHODS
An Institutional Review Board-approved study was performed using sinus tissue in 38 patients with CRS. P-gp expression was calculated using quantitative fluorescent immunohistochemistry to generate an epithelial-to-background staining ratio. Patients were stratified into low and high P-gp expression groups. Osteitis was scored radiologically using the Kennedy Osteitis Score (KOS) and Global Osteitis Score (GOS). Serum eosinophilia was assessed. KOS and GOS were compared using a Pearson's correlation coefficient. Osteitis scores and serum eosinophil concentrations between P-gp expression groups were compared using a nonparametric Mann-Whitney U test (two tailed).


RESULTS
Among the 38 patients, 7(18.42%) had high P-gp expression (mean ± SD, 4.86 ± 1.33) whereas 31(81.57%) had low expression ratios (1.93 ± 0.45). No patients in the high P-gp expression group had undergone prior surgery. Median serum eosinophil values were significantly greater in the high versus low P-gp expression group (6.98 ± 2.17 versus 2.36 ± 1.38, p < 0.001). GOS and KOS values were significantly greater in the high versus low P-gp expression group (15.86 ± 4.91 versus 6.29 ± 1.25 and 4.55 ± 4.33 verus 2.23 ± 1.71; p < 0.001). KOS and GOS values were significantly correlated (r = 0.835; p < 0.001).


CONCLUSIONS
Increased osteitis burden as measured by either the KOS or the GOS is associated with increased P-gp membranous expression in CRS. Radiographic quantification of osteitis may therefore be used to identify patients with P-gp overexpression thereby providing a novel potential therapeutic target.
1Department of Otolaryngology-Head and Neck Surgery, Adnan Menderes University Medical School Hospital, Aydın, Turkey.
Ceren
C
Günel
Rachel E
RE
Feldman
Benjamin S
BS
Bleier
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D002908:Chronic Disease; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009298:Nasal Polyps / Q000150:complications / Q000175:diagnosis*; D010000:Osteitis / Q000150:complications / Q000175:diagnosis*; D010256:Paranasal Sinuses / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D012852:Sinusitis / Q000150:complications / Q000175:diagnosis*; D015854:Up-Regulation
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1