• Open Access

P-glycoprotein is a marker of tissue eosinophilia and radiographic inflammation in chronic rhinosinusitis without nasal polyps

Authors

  • Rachel E. Feldman BA,

    1. Department of Otology and Laryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA
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  • Allen C. Lam MD,

    1. Department of Otology and Laryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA
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  • Peter M. Sadow MD, PhD,

    1. Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
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  • Benjamin S. Bleier MD

    Corresponding author
    1. Department of Otology and Laryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA
    • Correspondence to: Benjamin S. Bleier, MD, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Department of Otology and Laryngology, 243 Charles Street, Boston, MA 02114; e-mail: bleierb@gmail.com

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  • Potential conflict of interest: B.S.B. is an inventor on a provisional patent regarding modulation of P-glycoprotein in the treatment of chronic rhinosinusitis.

Abstract

Background

P-glycoprotein (P-gp) is a membrane-bound efflux pump that is upregulated in chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) and participates in epithelial cytokine secretion. Eosinophilic CRS (ECRS) shares a similar cytokine profile with CRSwNP and is associated with significant inflammation and poor surgical outcomes. The goal of this study is to determine if P-gp expression is associated with degree of eosinophilia and severity of radiographic inflammation in patients with CRS without polyps (CRSsNP).

Methods

An institutional review board (IRB)-approved study using sinus tissue in 39 steroid-naive patients with CRS. P-gp expression was calculated using quantitative fluorescent immunohistochemistry (Q-FIHC) to generate an epithelial to background staining ratio. Patients were stratified into low and high epithelial expression groups (<3 and ≥3, respectively). Average eosinophils per high powered field (hpf) and Lund-Mackay scores were calculated and compared with P-gp staining ratios using a 2-tailed Student t test.

Results

Among the 39 patients, 7 (17.95%) had high P-gp expression ratios (mean ± SD, 4.86 ± 1.33) while 32 (82.05%) had low expression ratios (1.91 ± 0.45). The number of eosinophils/hpf were significantly greater in the high P-gp expression group as compared to the low expression group (62.38 ± 83.69 vs 5.11 ± 10.12, p = 0.0003). The Lund-Mackay scores were significantly greater in the high P-gp expression group as compared to the low expression group (11.86 ± 2.79 vs 6.84 ± 4.19, p = 0.005).

Conclusion

P-gp is known to be overexpressed in CRSwNP. This study suggests that among patients with CRSsNP, P-gp is similarly overexpressed in those with high tissue eosinophilia and correlates with severity of radiographic inflammation.

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