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Chronic rhinosinusitis (CRS) is a complex, heterogenous condition that is likely associated with infectious and inflammatory causative factors. Renewed interest in the role that microbes play in this condition has stemmed from advancements in microbe identification and parallel research implicating the microbiome as having a role in other chronic inflammatory conditions. This clinical commentary provides a review of the current literature relevant to chronic rhinosinusitis. Particular focus is placed on factors specific to investigation of the sinonasal microbiome, evidence for the role of dysbiosis in the disease state, and influences that may affect the microbiome. Possible mechanisms of disease and therapeutic implications through microbial manipulation are also reviewed, as are deficiencies and limitations of the current body of research., (Copyright © 2022 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Emerging evidence suggests that chronic rhinosinusitis with nasal polyps (CRSwNP) is a highly heterogeneous disease with disparate inflammatory characteristics between different racial groups and geographies. Currently, little is known about possible underlying distinguishing factors between these inflammatory differences., Objective: Our aim was to interrogate differences in CRSwNP disease between White/non-Asian patients and Japanese patients by using whole transcriptome and single-cell RNA gene expression profiling of nasal polyps (NPs)., Methods: We performed whole transcriptome RNA sequencing with endotype stratification of NPs from 8 White patients (residing in the United States) and 9 Japanese patients (residing in Japan). Reproducibility was confirmed by quantitative PCR in an independent validation set of 46 White and 31 Japanese patients. Single-cell RNA sequencing (scRNAseq) was used to stratify key cell types for contributory transcriptional signatures., Results: Unsupervised clustering analysis identified 2 major endotypes that were present within both cohorts of patients with NPs and had previously been reported at the cytokine level: (1) type 2 endotype and (2) non-type 2 endotype. Importantly, there was a statistically significant difference in the proportion of these endotypes between these geographically distinct subgroups with NPs (P = .03). Droplet-based single-cell RNA sequencing further identified prominent type 2 inflammatory transcript expression: C-C motif chemokine ligand 13 (CCL13) and CCL18 in M2 macrophages, as well as cystatin SN (CST1) and CCL26 in basal, suprabasal, and secretory epithelial cells., Conclusion: NPs from both racial groups harbor the same 2 major endotypes, which we have determined to be present in differing ratios between each cohort with CRSwNP disease. Distinct inflammatory and epithelial cells contribute to the type 2 inflammatory profiles observed., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Although chronic rhinosinusitis (CRS) is considered the most treatable form of olfactory dysfunction, there has been relatively little clinical attention focused on assessing endotypes as they pertain to olfactory loss., Objectives: The goal of this study was to explore inflammatory endotypes in CRS using an unsupervised cluster analysis of olfactory cleft (OC) biomarkers in a phenotype-free approach., Methods: Patients with CRS were prospectively recruited and psychophysical olfactory testing, Questionnaire of Olfactory Dysfunction (QOD-NS), and bilateral OC endoscopy were obtained. Mucus was collected from the OC and evaluated for 26 biomarkers using principal component analysis. Cluster analysis was performed using only OC biomarkers and differences in olfactory measures were compared across clusters., Results: A total of 198 subjects (128 with CRS and 70 controls) were evaluated. Evaluation of OC biomarkers indicated 6 principal components, explaining 69.50% of the variance, with type 2, mixed type 1/T h 17-cell, growth factor, and neutrophil chemoattractant inflammatory signatures. A total of 10 clusters were identified that differed significantly in frequency of controls, and subjects with CRS with nasal polyps, and subjects with CRS without nasal polyps across the clusters (likelihood ratio test, χ 18 2 =178.64; P < .001). Olfactory measures differed significantly across clusters, including olfactory testing, QOD-NS, and OC endoscopy (P < .001 for all)., Conclusions: Clustering based solely on OC biomarkers can organize patients into clinically meaningful endotypes that discriminate between subjects with CRS and controls. Validation studies are necessary to confirm these findings and further refine olfactory endotypes., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Respiratory tract viruses are the second most common cause of olfactory dysfunction. As we learn more about the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with the recognition that olfactory dysfunction is a key symptom of this disease process, there is a greater need than ever for evidence-based management of postinfectious olfactory dysfunction (PIOD)., Objective: Our aim was to provide an evidence-based practical guide to the management of PIOD (including post-coronavirus 2019 cases) for both primary care practitioners and hospital specialists., Methods: A systematic review of the treatment options available for the management of PIOD was performed. The written systematic review was then circulated among the members of the Clinical Olfactory Working Group for their perusal before roundtable expert discussion of the treatment options. The group also undertook a survey to determine their current clinical practice with regard to treatment of PIOD., Results: The search resulted in 467 citations, of which 107 articles were fully reviewed and analyzed for eligibility; 40 citations fulfilled the inclusion criteria, 11 of which were randomized controlled trials. In total, 15 of the articles specifically looked at PIOD whereas the other 25 included other etiologies for olfactory dysfunction., Conclusions: The Clinical Olfactory Working Group members made an overwhelming recommendation for olfactory training; none recommended monocycline antibiotics. The diagnostic role of oral steroids was discussed; some group members were in favor of vitamin A drops. Further research is needed to confirm the place of other therapeutic options., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Chronic rhinosinusitis (CRS) is a prevalent multifactorial disease process in which bacteria are believed to play a role in the propagation of inflammation. Multiple subtypes of CRS have been described based on clinical and pathologic features, but a detailed examination of the sinus microbiota in patients with CRS and its clinical subtypes has yet to be performed., Objective: We sought to examine the resident microbiota of CRS subtypes and determine whether bacterial diversity is a predictor of disease outcomes., Methods: Sinus swabs from patients with CRS and healthy subjects collected during endoscopic sinus surgery were analyzed by means of molecular phylogenetic analysis of 16S rDNA pyrosequences., Results: Fifty-six patients with CRS and 26 control subjects were studied. Biodiversity was similar between the CRS and control groups. Among the CRS subtypes examined, only 2 conditions (presence of purulence and comorbid condition of asthma) were associated with significant alterations in microbial community composition. In 27 patients with CRS who were followed postoperatively, those with better outcomes had more diverse bacterial communities present at the time of surgery, along with higher relative abundances of Actinobacteria., Conclusion: Analysis of microbiota in a large cohort reveals that particular CRS phenotypes (asthma and purulence) are characterized by distinct compositions of resident bacterial communities. We found that bacterial diversity and composition are predictors of surgical outcome, promoting the concept of community ecology in patients with CRS., (Copyright © 2015 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)