Chronic Rhinosinusitis With Nasal Polyps: A Proteomic Analysis
David C. Upton, MD; Nathan V. Welham, PhD; John S. Kuo, MD, PhD; Jeffery W. Walker, PhDf ;ThomasR.Pasic,MD
Objectives: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a severe subtype of chronic rhinosinusitis that can affect patients despite medical and surgical interventions. The purpose of this study was to utilize the techniques of proteomics to investigate differences in protein abundance within the sinonasal mucosa of patients with CRSwNP compared to healthy controls. Methods: In a case-control study at a tertiary-care academic medical center, sinonasal mucosa was harvested from 3 patients with CRSwNP and 3 control patients undergoing transsphenoidal excision of pituitary tumors. Two-dimensional gel electrophoresis was used to identify proteins with elevated or reduced abundance in CRSwNP patients compared to controls. The proteins showing the greatest abundance difference were characterized by mass spectrometry. Results: More than 300 differentially abundant proteins (p < 0.05) were identified. Many of these protein species were involved in the host inflammatory response. Proteins up-regulated in CRSwNP patients included eosinophil lysophospholipase by a ratio (R) of 18.13, RHO-GDP dissociation inhibitor 2 (R = 2.80), and apolipoprotein A-1 (R = 1.73). Down-regulated proteins in CRSwNP patients included catalase (R = -5.87), annexin Al (R = -6.27), and keratin II-8 (R =-6.73) . A detailed analysis of additional protein species is outlined. Conclusions: The proteomic approach allows detection of significant differences in protein abundance in CRSwNP and provides unique insight into the pathophysiology of this common disease. Key Words: annexin A1 , apolipoprotein A-1 , chronic rhinosinusitis, eosinophil, nasal polyp, polyposis pathophysiology, proteomics.
INTRODUCTION
Chronic rhinosinusitis (CRS) is a common chronic illness in the United States that affects 14% to16% of the urban population.' Although significant multidisciplinary research has been devoted to studying the disease, the pathophysiology of CRSis not yet fully understood. It is thought to have anumber of contributing causes, including infection, inflammation, anatomic abnormalities, and genetic susceptibility. Along the spectrum of this disease, chronic rhinosinusitis with nasal polyps (CRSwNP) is a severe subtype, characterized by persistent eo- sinophilic inflammation, edematous mucosa withpolyps, and thickened sinonasal secretions, that pos-es a therapeutic challenge to clinicians despite medi-cal and surgical interventions .2 Previous complementary DNA microarray and immunohistochemical studies on the pathophysiology of the disease have suggested that CRS may represent a dysregulation of normal mucosal immune mechanisms that act to protect or repair the sino- nasal epithelium.-^-4 More recently, proteomics has been used to study CRS, primarily because it allows the simultaneous system-wide characterization of all proteins present in a given biological condition at a given time. The techniques used in proteomic research consist of 1) separating protein molecules via gel electrophoresis or liquid capillary chroma-tography, 2) subjecting the separated proteins to mass spectrometry (MS) to generate characteris- tic mass spectra, and 3) comparing the mass spec- tra against established databases to identify the pro- teins of interest. These techniques have been usedto identify qualitative and quantitative differences in ject s and patients with CRS.^ The majority of previ- ously identified proteins are involved in innate and From the Department of Surgery, Division of Otolaryngology (Upton, Welham, Pasic), and the Department of Neurological Surgery (Kuo), University of Wisconsin Hospital and Clinics, Madison, Wisconsin, and the Department of Physiology, University of Arizona, Tucson, Arizona (Walker). Supported by grant funding from the American Academy of Otolaryngic Allergy (ROAD scholarship) and the University of Wisconsin Department of Surgery, Division of Otolaryngology. †Deceased. Presented at the meeting of the American Academy of Otolaryngic Allergy, San Diego, California, October 2-4,2009, and the meeting of the Wisconsin Society of Otolaryngology, Madison, Wisconsin, October 24-25,2009 .Correspondence: Thomas R. Pasic, MD, Dept of Surgery, Division of Otolaryngology, University of Wisconsin Hospital and Clinics, 600 Highland Ave, Madison, WI 53792.
acquired immunity and mucosal defense. To date proteomic investigation of the sinonasal mucosa of patients with CRSwNP has been promising.^ techniques have the potential to identify unique proteins expressed in the mucosa of patients with CRSwNP, which in turn may improve understanding of the pathophysiology of the disease and uncover new targets for therapeutic intervention. purpose of this study was to investigate differences in protein abundance within the sinonasal mucosa patients with CRSwNP compared to healthy subjects by use of a proteomic approach the absence of active sinonasal inflammation con- firmed on preoperative magnetic resonance imaging and nasal endoscopy before tissue sampling. Fxclu- sion criteria included active tobacco use, inability to give informed consent, pregnancy or lactation, autoimmune disease affecting the nose and sinuses (eg, Wegener's granulomatosis), and sinonasal neoplasms.
MATERIALS AND METHODS
Patient Selection. This study was approved by the Institutional Review Board at the University of Wisconsin Hospitals and Clinics (Madison, Wiscon-sin), and all subjects gave signed informed consent. A case-control study was performed to determinedifferences in protein abundance in patients with CRSwNP compared to normal subjects. The patient swere recruited from the senior author's (T.R.P.) prac-tice. A total of 6 individuals (3 patients, 3 controls) participated in the study. The diagnosis of CRSwNPwas based on a set of clinical criteria previously de-fined by the American Academy of Otolaryngolo-gy-Head and Neck Surgery Chronic RhinosinusitisTask Force and was confirmed on nasal endoscopy.^ All patients underwent a preoperative coronal com- puted tomographic scan of the sinuses in bone win- dow settings to further assess the extent of sinona-sal disease (Fig 1). Before endoscopie sinus surgery, the patients with CRSwNP received 1 week of oralprednisone and oral antibiotics. Individuals selected to act as controls in this study were recruited from patients who were undergoing resection of pituitary gery for clinical symptoms of rhinosinusitis and had
Sample Collection.Tissue samples of the mucosal lining of the paranasal sinuses were collected under endoscopie guidance, rinsed of overlying debris in 0.9% sodium chloride solution, and then snap-fro- zen in liquid nitrogen. The tissue samples were kept at -80°C until analysis. All tissue specimens were taken from either the ethmoid or sphenoid sinuses; tissue from olfactory-bearing regions of the nasal cavity was not harvested. All tissue was sent fresh for microbiological analysis, bacterial and fungal culture, and histologie examination.
Two-Dimensional Gel Electwphoresis. The sam- ples were homogenized with glass dounces in 1 mL each of osmotic lysis buffer containing nucle- ase, phosphatase inhibitors, and a protease inhibitor. Next, 500 |iL sodium dodecyl sulfate (SDS) boiling buffer without ß-mercaptoethanol was added, and the samples were heated in a boiling water bath for 5 minutes. Total protein quantization was performed by the bicinchoninic acid assay (Pierce, Rockford, Illinois). The samples were then diluted to 6.0 mg/ mL in equal parts SDS boiling buffer and urea sam- ple buffer before loading. Two-dimensional electro- phoresis was performed according to the carrier am- pholine method by Kendrick Labs, Inc (Madison), as follows. Isoelectric focusing was carried out in a glass tube of inner diameter 3.0 mm with 2.0% pH 3.5 to 10 ampholines (Amersham Biosciences, Pis- cataway. New Jersey) for 20 kilovolt hours. One mi- crogram of an isoelectric focusing internal standard.
tropomyosin, was added to the sample. After equili-bration for 10 minutes in "buffer 0" (10% glycer- ol, 50 mmol/L dithiothreitol, 2.3% SDS, and 0.0625 mol/L Tris, pH 6.8), the tube gel was sealed to the top of a stacking gel that overlaid a 10% acrylamide slab gel (1.0 mm thick). SDS slab gel electro pho-resis w