Topographic distribution of gene expression and sinonasal inflammation in chronic rhinosinusitis without nasal polyposis

promotes inflammation in a positive-feedback manner to further enhance the production of other type 1 inflammation- associated cytokines in CRS. 5 Increasing evidence suggests site- specific gene expression patterns within the sinonasal cavity. Platt et al. examined the ex pression level of five genes previously shown to be differentially expressed in nasal polyps in five regional mucosal subsites within the sinonasal cavity, including the lateral nasal wall, middle turbi -nate, inferior turbinate, septum and ethmoids; the authors found gene expression patterns of those analysed to differ significantly. 6 Interestingly, regional expression differences may also associate with disease burden and outcomes. Weibman et al. demonstrated that eosinophil regional expression differences measured between the uncinate process and nasal polyp tissue had utility in predicting both disease burden and outcome of treatment in patients with CRS with nasal polyps. 7 Our data suggest that large locoregional gene expression differences exist between the anterior ethmoid sinuses and the nasal floor. Future investigations should seek to compare gene expression and tissue biomarkers across all subsites within the nose and include a non- CRS control cohort in order to understand the true contribution of CRS to the gene expression differences ob -served. Although we ensured that all patients enrolled had been off oral steroids for 2 weeks, it is possible that their inflammatory profile had not returned to baseline by the end of this timeframe. Finally, comorbidities such as asthma and allergy, including allergic rhinitis, could confound the markers that we have identified locally in the sinuses. Future studies should include prospective biopsy collec tion and gene profiling with increased sample sizes of patients with CRSsNP with and without comorbid asthma and/or allergy, whereby the potential contribution of systemic inflammation can be properly assessed.