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A re-examination of former concepts is required to meet today’s medical challenges in allergic rhinitis. Previously, neutrophils have been treated as a relatively homogenous cell population found in the nose both when the patient is suffering at the height of the allergic season as well as when the patient report no symptoms. However, new data indicates that neutrophils can be divided into different subsets with diverse roles in inflammation. We showed increased levels of neutrophils in peripheral blood, nasal biopsies and nasal lavage fluid (NAL) from allergic patients during the pollen season compared to healthy controls. A closer examination revealed that the activated subset of neutrophils, CD16high CD62Ldim, outweighed the normal form CD16high CD62Lhigh in nasal tissue among these patients. This skewed distribution was not seen in controls. The normal subset prevailed in peripheral blood from patients as well as controls, whereas CD16high CD62Ldim and CD16dim CD62Ldim subsets, the latter considered “end state” neutrophils before apoptosis, were elevated in NAL. Functional in vitro experiments revealed that activated neutrophils exhibit a T cell priming capacity and an ability to enhance eosinophil migration. Activated neutrophils may thus contribute to allergic inflammation seen in allergic rhinitis by priming T cells and attracting eosinophils.

Background: Current phenotyping of chronic rhinosinusitis (CRS) into chronic rhinosinusitis with nasal polyps (CRSwNP) and chronic rhinosinusitis without nasal polyps (CRSsNP) might not adequately reflect the pathophysiologic diversity within patients with CRS. Objective: We sought to identify inflammatory endotypes of CRS. Therefore we aimed to cluster patients with CRS based solely on immune markers in a phenotype-free approach. Secondarily, we aimed to match clusters to phenotypes. Methods: In this multicenter case-control study patients with CRS and control subjects underwent surgery, and tissue was analyzed for IL-5, IFN-gamma, IL-17A, TNF-alpha, IL-22, IL-1 beta, IL-6, IL-8, eosinophilic cationic protein, myeloperoxidase, TGF-beta 1, IgE, Staphylococcus aureus enterotoxin-specific IgE, and albumin. We used partition-based clustering. Results: Clustering of 173 cases resulted in 10 clusters, of which 4 clusters with low or undetectable IL-5, eosinophilic cationic protein, IgE, and albumin concentrations, and 6 clusters with high concentrations of those markers. The group of IL-5-negative clusters, 3 clusters clinically resembled a predominant chronic rhinosinusitis without nasal polyps (CRSsNP) phenotype without increased asthma prevalence, and 1 cluster had a T(H)17 profile and had mixed CRSsNP/CRSwNP. The IL-5-positive clusters were divided into a group with moderate IL-5 concentrations, a mixed CRSsNP/CRSwNP and increased asthma phenotype, and a group with high IL-5 levels, an almost exclusive nasal polyp phenotype with strongly increased asthma prevalence. In the latter group, 2 clusters demonstrated the highest concentrations of IgE and asthma prevalence, with all samples expressing Staphylococcus aureus enterotoxin-specific IgE. Conclusion: Distinct CRS clusters with diverse inflammatory mechanisms largely correlated with phenotypes and further differentiated them and provided a more accurate description of the inflammatory mechanisms involved than phenotype information only.

Background The origin of nasal polyps in chronic rhinosinusitis is unknown, but the role of viral infections in polyp growth is clinically well established. Toll-like receptors (TLRs) have recently emerged as key players in our local airway defense against microbes. Among these, TLR9 has gained special interest in viral diseases. Many studies on chronic rhinosinusitis with nasal polyps (CRSwNP) compare polyp tissue with nasal mucosa from polyp-free individuals. Knowledge about changes in the turbinate tissue bordering the polyp tissue is limited. Objectives To analyse the role of TLR9 mediated microbial defense in tissue bordering the polyp. Methods Nasal polyps and turbinate tissue from 11 patients with CRSwNP and turbinate tissue from 11 healthy controls in total were used. Five biopsies from either group were analysed immediately with flow cytometry regarding receptor expression and 6 biopsies were used for in vitro stimulation with a TLR9 agonist, CpG. Cytokine release was analysed using Luminex. Eight patients with CRSwNP in total were intranasally challenged with CpG/placebo 24 hours before surgery and the biopsies were collected and analysed as above. Results TLR9 expression was detected on turbinate epithelial cells from healthy controls and polyp epithelial cells from patients, whereas TLR9 was absent in turbinate epithelial cells from patients. CpG stimulation increased the percentage cells expressing TLR9 and decreased percentage cells expressing VEGFR2 in turbinate tissue from patients. After CpG stimulation the elevated levels of IL-6, G-CSF and MIP-1β in the turbinate tissue from patients were reduced towards the levels demonstrated in healthy controls. Conclusion Defects in the TLR9 mediated microbial defense in the mucosa adjacent to the anatomic origin of the polyp might explain virus induced polyp growth. CpG stimulation decreased VEGFR2, suggesting a role for CpG in polyp formation. The focus on turbinate tissue in patients with CRSwNP opens new perspectives in CRSwNP-research.

Results Human nasal epithelial cells were shown to take up dextran, which ended up in intracellular endosome-like structures. In addition, MHC class II and co-stimulatory molecules were found on human and mouse nasal epithelial cells. Functionally, nasal epithelial cells from ovalbumin-sensitized mice activated and induced antigen-specific proliferation of naive OT-II CD4+ T cells in vitro. A similar activation was not seen in naive MNECs. Finally, nasal epithelial cells from allergic rhinitis patients were able to activate autologous T cells against Bet v 1 and induce IL-13 release.

Background The Global Allergy and Asthma European Network (GALEN) is a network of the leading European allergy clinical and research facilities and the GALEN Sinusitis Cohort is a database within this network. The aim of this cohort is to intensify research on rhinosinusitis phenoand endotypes, thus differentiating chronic rhinosinusitis (CRS) into smaller disease entities based on clinical, biological, and patient-reported outcomes.