RHINOLOGY Decreased PLUNC expression in nasal polyps is associated with multibacterial colonization in chronic rhinosinusitis patients Yung-An Tsou • Ming-Te Peng • Yi-Fang Wu • Chih-Ho Lai • Chia-Der Lin • Chih-Jaan Tai • Ming-Hsui Tsai • Chuan-Mu Chen • Hui-Chen Chen Received: 8 March 2013 / Accepted: 25 April 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract PLUNC (palate, lung, and nasal epithelium clone) is an epithelium-secreted protein that plays a crucial role in the host’s defense against bacterial infection. The function of PLUNC in the sinus remains poorly understood. To examine whether the expression levels of PLUNC could serve as a predictive outcome biomarker for patients with CRSwNP and bacterial colonization, we investigated the association of PLUNC expression levels with bacterial colonization in the sinuses. A total of 174 patients who underwent sinus surgery for chronic rhinosinusitis with nasal polyps (CRSwNP) were enrolled in this study. The tissue samples obtained from patients were examined using preoperative sinus computed tomography (CT) scans, postoperative bacterial cultures, and nasal polyp examina- tions. PLUNC mRNA and protein expression were quantified using RT-PCR and immunohistochemistry. We identified that decreased PLUNC expression is associated with multibacterial colonization (P = 0.0001), specifically those mediated by Staphyloccocus aureus (P = 0.037) and Pseudomonas aeruginosa (P = 0.002). The patients who required repeated sinus surgeries for recurrent or persistent sinusitis also presented much lower PLUNC expression than those who did not require repeated sinus surgery (P = 0.001). However, gender, age, and CT scores were not associated with PLUNC expression. These results suggest that reduced PLUNC expression is associated with bacterial colonization as well as treatment outcome in CRSwNP patients. Investigation of the association between PLUNC expressions and chronic rhinosinusitis may lead to the development of a novel biomarker for treatment outcome in CRSwNP patients. Keywords PLUNC Á Sinusitis Á Nasal polyposis Á Bacterial colonization Á Diagnosis Introduction PLUNC (short palate, lung, and nasal epithelium clone), a 25-kDa protein that is a member of the bactericidal/per- meability-increasing protein (BPI) family, is found to play an important role in host defense against microbes [1]. Several reports have shown that PLUNC is expressed specifically in the nasopharyngeal and respiratory epithe- lium [2, 3]. Moreover, the amino acid sequence of PLUNC is highly similar to those of secretory proteins produced by salivary glands and glandular epithelium of the trachea and the parotid secretory protein [4]. The biological function of PLUNC is not well understood. However, its structure is similar to BPI family proteins; hence, PLUNC might be Y.-A. Tsou Á C.-D. Lin Á C.-J. Tai Á M.-H. Tsai Department of Otolaryngology-Head and Neck Surgery, China Medical University Hospital, Taichung, Taiwan Y.-A. Tsou Á C.-D. Lin Á M.-H. Tsai Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan Y.-A. Tsou Department of Pathology, China Medical University Hospital, Taichung, Taiwan Y.-A. Tsou Á C.-M. Chen (&) Department of Life Sciences and Agricultural Biotechnology Center, National Chung Hsing University, 250 Kuo Kuang Rd., Taichung 402, Taiwan e-mail: chchen1@dragon.nchu.edu.tw M.-T. Peng Á Y.-F. Wu Á C.-H. Lai Á H.-C. Chen (&) Graduate Institute of Basic Medical Science, China Medical University, 91 Hsueh-Shih Road, Taichung 40402, Taiwan e-mail: hcchen725@mail.cmu.edu.tw 123 Eur Arch Otorhinolaryngol DOI 10.1007/s00405-013-2535-8