Precision Medicine for More Oxygen (P4O2)-Study Design and First Results of the Long COVID-19 Extension

Introduction: The coronavirus disease 2019 (COVID-19) pandemic has led to the death of almost 7 million people, however, with a cumulative incidence of 0.76 billion, most people survive COVID-19. Several studies indicate that the acute phase of COVID-19 may be followed by persistent symptoms including fatigue, dyspnea, headache, musculoskeletal symptoms, and pulmonary functional-and radiological abnormalities. However, the impact of COVID-19 on long-term health outcomes remains to be elucidated. Aims: The Precision Medicine for more Oxygen (P4O2) consortium COVID-19 extension aims to identify long COVID patients that are at risk for developing chronic lung disease and furthermore, to identify treatable traits and innovative personalized therapeutic strategies for prevention and treatment. This study aims to describe the study design and first results of the P4O2 COVID-19 cohort. Methods: The P4O2 COVID-19 study is a prospective multicenter cohort study that includes nested personalized counseling intervention trial. Patients, aged 40-65 years, were recruited from outpatient post-COVID clinics from five hospitals in The Netherlands. During study visits at 3-6 and 12-18 months post-COVID-19, data from medical records, pulmonary function tests, chest computed tomography scans and biological samples were collected and questionnaires were administered. Furthermore, exposome data was collected at the patient's home and state-of-the-art imaging techniques as well as multi-omics analyses will be performed on collected data. Results: 95 long COVID patients were enrolled between May 2021 and September 2022. The current study showed persistence of clinical symptoms and signs of pulmonary function test/radiological abnormalities in post-COVID patients at 3-6 months post-COVID. The most commonly reported symptoms included respiratory symptoms (78.9%), neurological symptoms (68.4%) and fatigue (67.4%). Female sex and infection with the Delta, compared with the Beta, SARS-CoV-2 variant were significantly associated with more persisting symptom categories. Conclusions: The P4O2 COVID-19 study contributes to our understanding of the long-term health impacts of COVID-19. Furthermore, P4O2 COVID-19 can lead to the identification of different phenotypes of long COVID patients, for example those that are at risk for developing chronic lung disease. Understanding the mechanisms behind the different phenotypes and identifying these patients at an early stage can help to develop and optimize prevention and treatment strategies.

Measuring cystic fibrosis drug responses in organoids derived from 2D differentiated nasal epithelia

Cystic fibrosis is caused by genetic defects that impair the CFTR channel in airway epithelial cells. These defects may be overcome by specific CFTR modulating drugs, for which the efficacy can be predicted in a personalized manner using 3D nasal-brushing-derived airway organoids in a forskolin-induced swelling assay. Despite of this, previously described CFTR function assays in 3D airway organoids were not fully optimal, because of inefficient organoid differentiation and limited scalability. In this report, we therefore describe an alternative method of culturing nasal-brushing-derived airway organoids, which are created from an equally differentiated airway epithelial monolayer of a 2D air-liquid interface culture. In addition, we have defined organoid culture conditions, with the growth factor/cytokine combination neuregulin-1<i>β</i> and interleukin-1<i>β</i>, which enabled consistent detection of CFTR modulator responses in nasal-airway organoid cultures from subjects with cystic fibrosis.

Biologicals in childhood severe asthma: the European PERMEABLE survey on the status quo

Introduction

Severe asthma is a rare disease in children, for which three biologicals, anti-immunoglobulin E, anti-interleukin-5 and anti-IL4RA antibodies, are available in European countries. While global guidelines exist on who should receive biologicals, knowledge is lacking on how those guidelines are implemented in real life and which unmet needs exist in the field. In this survey, we aimed to investigate the status quo and identify open questions in biological therapy of childhood asthma across Europe.

Methods

Structured interviews regarding experience with biologicals, regulations on access to the different treatment options, drug selection, therapy success and discontinuation of therapy were performed. Content analysis was used to analyse data.

Results

We interviewed 37 experts from 25 European countries and Turkey and found a considerable range in the number of children treated with biologicals per centre. All participating countries provide public access to at least one biological. Most countries allow different medical disciplines to prescribe biologicals to children with asthma, and only a few restrict therapy to specialised centres. We observed significant variation in the time point at which treatment success is assessed, in therapy duration and in the success rate of discontinuation. Most participating centres intend to apply a personalised medicine approach in the future to match patients a priori to available biologicals.

Conclusion

Substantial differences exist in the management of childhood severe asthma across Europe, and the need for further studies on biomarkers supporting selection of biologicals, on criteria to assess therapy response and on how/when to end therapy in stable patients is evident.

This study reveals enormous differences in therapy with biologicals for childhood severe asthma across Europe, and demonstrates the urgent need for harmonisation in medication choice, definition of therapy success and how/when to discontinue treatmenthttps://bit.ly/3tnJMTY

High titers and low fucosylation of early human anti-SARS-CoV-2 IgG promote inflammation by alveolar macrophages

Patients diagnosed with coronavirus disease 2019 (COVID-19) become critically ill primarily around the time of activation of the adaptive immune response. Here, we provide evidence that antibodies play a role in the worsening of disease at the time of seroconversion. We show that early-phase severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) spike protein-specific immunoglobulin G (IgG) in serum of critically ill COVID-19 patients induces excessive inflammatory responses by human alveolar macrophages. We identified that this excessive inflammatory response is dependent on two antibody features that are specific for patients with severe COVID-19. First, inflammation is driven by high titers of anti-spike IgG, a hallmark of severe disease. Second, we found that anti-spike IgG from patients with severe COVID-19 is intrinsically more proinflammatory because of different glycosylation, particularly low fucosylation, of the antibody Fc tail. Low fucosylation of anti-spike IgG was normalized in a few weeks after initial infection with SARS-CoV-2, indicating that the increased antibody-dependent inflammation mainly occurs at the time of seroconversion. We identified Fcγ receptor (FcγR) IIa and FcγRIII as the two primary IgG receptors that are responsible for the induction of key COVID-19-associated cytokines such as interleukin-6 and tumor necrosis factor. In addition, we show that anti-spike IgG-activated human macrophages can subsequently break pulmonary endothelial barrier integrity and induce microvascular thrombosis in vitro. Last, we demonstrate that the inflammatory response induced by anti-spike IgG can be specifically counteracted by fostamatinib, an FDA- and EMA-approved therapeutic small-molecule inhibitor of Syk kinase.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

Steroid-resistant human inflammatory ILC2s are marked by CD45RO and elevated in type 2 respiratory diseases

Group 2 innate lymphoid cells (ILC2s) orchestrate protective type 2 immunity and have been implicated in various immune disorders. In the mouse, circulatory inflammatory ILC2s (iILC2s) were identified as a major source of type 2 cytokines. The human equivalent of the iILC2 subset remains unknown. Here, we identify a human inflammatory ILC2 population that resides in inflamed mucosal tissue and is specifically marked by surface CD45RO expression. CD45RO⁺ ILC2s are derived from resting CD45RA⁺ ILC2s upon activation by epithelial alarmins such as IL-33 and TSLP, which is tightly linked to STAT5 activation and up-regulation of the IRF4/BATF transcription factors. Transcriptome analysis reveals marked similarities between human CD45RO⁺ ILC2s and mouse iILC2s. Frequencies of CD45RO⁺ inflammatory ILC2 are increased in inflamed mucosal tissue and in the circulation of patients with chronic rhinosinusitis or asthma, correlating with disease severity and resistance to corticosteroid therapy. CD45RA-to-CD45RO ILC2 conversion is suppressed by corticosteroids via induction of differentiation toward an immunomodulatory ILC2 phenotype characterized by low type 2 cytokine and high amphiregulin expression. Once converted, however, CD45RO⁺ ILC2s are resistant to corticosteroids, which is associated with metabolic reprogramming resulting in the activation of detoxification pathways. Our combined data identify CD45RO⁺ inflammatory ILC2s as a human analog of mouse iILC2s linked to severe type 2 inflammatory disease and therapy resistance.

Novel roles for nasal epithelium in the pathogenesis of chronic rhinosinusitis with nasal polyps

BACKGROUND

Airway epithelial cells have a well-accepted role in the regulation of local inflammatory processes in allergic and innate defence responses. However, their role the pathophysiology of chronic rhinosinusitis with nasal polyps (CRSwNP) is unclear. The objective was to investigate whether potential differences in the mRNA expression profile of nasal epithelia from healthy individuals and from CRSwNP patients would shed new light on disease mechanisms.

METHODS

Primary epithelial cells from nasal polyps of 24 affected individuals and from middle turbinates of 9 healthy controls were obtained using magnetic beat assisted isolation and were used for expression profiling using the Human Genome U133 Plus 2.0 Genechip Array.

RESULTS

Multiple gene probes corresponding to 27 genes showed an aberrant expression profile in polyp epithelial cells compared to healthy controls. Most of these genes are linked to pathogenic mechanisms seen in neoplasm formation, including changes in cell-cell adhesion, metabolic processes, cell cycle control, and differentiation. Remarkably, our data additionally suggest a role for maternally expressed genes in the pathogenesis of CRSwNP and reveal two distinct states of polyp epithelium that could not be linked to the presence or absence of atopy in patients or to the level of eosinophilia or neutrophilia of the polyp.

CONCLUSIONS

Our data suggest new roles for nasal epithelium in the pathogenesis of CRSwNP.

IL-1β, IL-23, and TGF-β drive plasticity of human ILC2s towards IL-17-producing ILCs in nasal inflammation

Innate lymphoid cells (ILCs) are crucial for the immune surveillance at mucosal sites. ILCs coordinate early eradication of pathogens and contribute to tissue healing and remodeling, features that are dysfunctional in patients with cystic fibrosis (CF). The mechanisms by which ILCs contribute to CF-immunopathology are ill-defined. Here, we show that group 2 ILCs (ILC2s) transdifferentiated into IL-17-secreting cells in the presence of the epithelial-derived cytokines IL-1β, IL-23 and TGF-β. This conversion is abrogated by IL-4 or vitamin D3. IL-17 producing ILC2s induce IL-8 secretion by epithelial cells and their presence in nasal polyps of CF patients is associated with neutrophilia. Our data suggest that ILC2s undergo transdifferentiation in CF nasal polyps in response to local cytokines, which are induced by infectious agents.

Dendritic Cell Subsets in Oral Mucosa of Allergic and Healthy Subjects

Immunohistochemistry was used to identify, enumerate, and describe the tissue distribution of Langerhans type (CD1a and CD207), myeloid (CD1c and CD141), and plasmacytoid (CD303 and CD304) dendritic cell subsets in oral mucosa of allergic and non-allergic individuals. Allergic individuals have more CD141+ myeloid cells in epithelium and more CD1a+ Langerhans cells in the lamina propria compared to healthy controls, but similar numbers for the other DC subtypes. Our data are the first to describe the presence of CD303+ plasmacytoid DCs in human oral mucosa and a dense intraepithelial network of CD141+ DCs. The number of Langerhans type DCs (CD1a and CD207) and myeloid DCs (CD1c), was higher in the oral mucosa than in the nasal mucosa of the same individual independent of the atopic status.

Specific Induction of TSLP by the Viral RNA Analogue Poly(I:C) in Primary Epithelial Cells Derived from Nasal Polyps

Introduction

Chronic rhinosinusitis with nasal polyposis is an inflammatory disease that, although not directly linked to allergy, often displays a Th2-skewed inflammation characterized by elevated local IgE and IL-5 levels. The nasal cavity is constantly exposed to bacteria and viruses that may trigger epithelial inflammatory responses. To gain more insight into mechanisms by which such a biased inflammation might arise, we have investigated the epithelial expression of the Th2 skewing mediators (TSLP, IL-25, and IL-33) in relationship to disease and microbial triggers.

Methods

Epithelial cells were obtained from polyp tissues of nasal polyposis patients and from inferior turbinates of non-diseased controls. Cells were exposed to various TLR-specific triggers to study the effect on mRNA and protein expression level of TSLP, IL-25, and IL-33 and the potential regulatory mechanisms through the expression profile the transcription factors ATF-3, DUSP-1, EGR-1, and NFKB-1.

Results

The TLR3 agonist and viral analogue poly(I:C) induced TSLP mRNA 13.0 ± 3.1 fold (p < 0.05) and protein expression by 12.1 ± 2.3-fold (p < 0.05) higher in epithelium isolated from nasal polyposis patients than in epithelium form healthy controls. This enhanced induction of TSLP may be a consequence of a down-regulated expression of DUSP-1 in polyp epithelium.

Conclusion

The TLR3 induced expression of TSLP introduces a mechanism by which the Th2-skewed tissue environment might arise in nasal polyps and invites a further evaluation of the potential contribution of current or past viral infections to polyposis pathogenesis.

Radioprotection of IDH1-Mutated Cancer Cells by the IDH1-Mutant Inhibitor AGI-5198

Isocitrate dehydrogenase 1 (IDH1) is mutated in various types of human cancer to IDH1(R132H), a structural alteration that leads to catalysis of α-ketoglutarate to the oncometabolite D-2-hydroxyglutarate. In this study, we present evidence that small-molecule inhibitors of IDH1(R132H) that are being developed for cancer therapy may pose risks with coadministration of radiotherapy. Cancer cells heterozygous for the IDH1(R132H) mutation exhibited less IDH-mediated production of NADPH, such that after exposure to ionizing radiation (IR), there were higher levels of reactive oxygen species, DNA double-strand breaks, and cell death compared with IDH1 wild-type cells. These effects were reversed by the IDH1(R132H) inhibitor AGI-5198. Exposure of IDH1 wild-type cells to D-2-hydroxyglutarate was sufficient to reduce IDH-mediated NADPH production and increase IR sensitivity. Mechanistic investigations revealed that the radiosensitivity of heterozygous cells was independent of the well-described DNA hypermethylation phenotype in IDH1-mutated cancers. Thus, our results argue that altered oxidative stress responses are a plausible mechanism to understand the radiosensitivity of IDH1-mutated cancer cells. Further, they offer an explanation for the relatively longer survival of patients with IDH1-mutated tumors, and they imply that administration of IDH1(R132H) inhibitors in these patients may limit irradiation efficacy in this setting.

Capsaicin for non-allergic rhinitis

BACKGROUND

There are many forms of rhinitis. Patients are diagnosed with non-allergic rhinitis when anatomic, infectious and allergic aetiologies have been excluded. The symptoms, including nasal congestion, blockage or obstruction, clear rhinorrhoea, sneezing and, less frequently, nasal itching, can range from mild to debilitating. It affects between 25% and 50% of patients with rhinitis. Several medications are widely used in the treatment of non-allergic rhinitis, including oral and topical nasal antihistamines, intranasal and (rarely) systemic corticosteroids, and anticholinergics. Capsaicin, the active component of chili peppers, delivered intranasally, is considered a treatment option for non-allergic rhinitis.

OBJECTIVES

To assess the effectiveness of capsaicin in the management of non-allergic rhinitis compared with no therapy, placebo or other topical or systemic medications, or two or more of the above therapies in combination, or different capsaicin regimens.

SEARCH METHODS

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 5); PubMed; EMBASE; CINAHL; Web of Science; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the search was 24 June 2015.

SELECTION CRITERIA

Randomised controlled trials in adult patients with non-allergic rhinitis comparing intranasal capsaicin with no therapy, placebo or other topical or systemic medications, or their combinations.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We included four studies (five publications) involving 302 participants with idiopathic non-allergic rhinitis. All the included studies described patients with moderately severe, idiopathic non-allergic rhinitis who were between the ages of 16 and 65. Studies had follow-up periods ranging from four to 38 weeks. The overall risk of bias in the studies was either high or unclear (two studies had overall high risk of bias, while two others had low to unclear risk of bias). Using the GRADE system we assessed the evidence as being of low to moderate quality. A meta-analysis was not possible, given lack of similarity of the reported outcomes.Two studies compared capsaicin with placebo. One study reported that capsaicin resulted in an improvement of overall nasal symptoms (a primary outcome) measured on a visual analogue scale (VAS) of 0 to 10. There was a mean difference (MD) of -3.34 (95% confidence interval (CI) -5.24 to -1.44), MD -3.73 (95% CI -5.45 to -2.01) and MD -3.52 (95% CI -5.55 to -1.48) at two, 12 and 36 weeks post-treatment, respectively. Another study reported that, compared to placebo, capsaicin (at 4 µg/puff) was more likely to produce overall symptom resolution (reduction in nasal blockage, sneezing/itching/coughing and nasal secretion measured with a daily record chart) at four weeks post-treatment (a primary outcome). The risk ratio (RR) was 3.17 (95% CI 1.38 to 7.29).One study compared capsaicin to budesonide (an intranasal corticosteroid). This study found that patients treated with capsaicin had a better overall symptom score compared to those treated with budesonide (MD 2.50, 95% CI 1.06 to 3.94, VAS of 0 to 10). However, there were no differences in the individual symptom scores for headache, postnasal drip, rhinorrhoea, nasal blockage, sneezing and sore throat assessed during the last three days of a four-week treatment.One study compared two different regimens of capsaicin administration: five treatments in one day versus five treatments given every two to three days during two weeks. Using daily record charts, the study reported significant improvement of individual symptom scores for rhinorrhoea in patients treated five times per day, however numerical data were not presented. There were no improvements in the other outcomes: rhinorrhoea, nasal obstruction, sneezing and overall nasal symptoms, measured on a VAS.Finally, one of these studies also compared three doses of capsaicin (to placebo). Patients treated with a 1 µg versus 4 µg per puff dose of capsaicin had a worse daily record chart overall symptom score resolution (RR 0.63, 95% CI 0.34 to 1.16).Only one study attempted to measure adverse effects (a primary outcome), however due to methodological issues with the assessment we are unable to draw any conclusions.We sought to include other secondary outcomes (e.g. quality of life measures, treatment dropouts, endoscopic scores, turbinate or mucosal size, cost of therapy), but none of these were measured or reported in the included studies.

AUTHORS' CONCLUSIONS

Capsaicin may be an option in the treatment of idiopathic non-allergic rhinitis. It is given in the form of brief treatments, usually during the same day. It appears to have beneficial effects on overall nasal symptoms up to 36 weeks after treatment, based on a few, small studies (low-quality evidence). Well-conducted randomised controlled trials are required to further advance our understanding of the effectiveness of capsaicin in non-allergic rhinitis, especially in patients with non-allergic rhinitis of different types and severity, and using different methods of capsaicin application.

Capsaicin for non-allergic rhinitis

BACKGROUND

There are many forms of rhinitis. Patients are diagnosed with non-allergic rhinitis when anatomic, infectious and allergic aetiologies have been excluded. The symptoms, including nasal congestion, blockage or obstruction, clear rhinorrhoea, sneezing and, less frequently, nasal itching, can range from mild to debilitating. It affects between 25% and 50% of patients with rhinitis. Several medications are widely used in the treatment of non-allergic rhinitis, including oral and topical nasal antihistamines, intranasal and (rarely) systemic corticosteroids, and anticholinergics. Capsaicin, the active component of chili peppers, delivered intranasally, is considered a treatment option for non-allergic rhinitis.

OBJECTIVES

To assess the effectiveness of capsaicin in the management of non-allergic rhinitis compared with no therapy, placebo or other topical or systemic medications, or two or more of the above therapies in combination, or different capsaicin regimens.

SEARCH METHODS

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 5); PubMed; EMBASE; CINAHL; Web of Science; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the search was 24 June 2015.

SELECTION CRITERIA

Randomised controlled trials in adult patients with non-allergic rhinitis comparing intranasal capsaicin with no therapy, placebo or other topical or systemic medications, or their combinations.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We included four studies (five publications) involving 302 participants with idiopathic non-allergic rhinitis. All the included studies described patients with moderately severe, idiopathic non-allergic rhinitis who were between the ages of 16 and 65. Studies had follow-up periods ranging from four to 38 weeks. The overall risk of bias in the studies was either high or unclear (two studies had overall high risk of bias, while two others had low to unclear risk of bias). Using the GRADE system we assessed the evidence as being of low to moderate quality. A meta-analysis was not possible, given lack of similarity of the reported outcomes.Two studies compared capsaicin with placebo. One study reported that capsaicin resulted in an improvement of overall nasal symptoms (a primary outcome) measured on a visual analogue scale (VAS) of 0 to 10. There was a mean difference (MD) of -3.34 (95% confidence interval (CI) -5.24 to -1.44), MD -3.73 (95% CI -5.45 to -2.01) and MD -3.52 (95% CI -5.55 to -1.48) at two, 12 and 36 weeks post-treatment, respectively. Another study reported that, compared to placebo, capsaicin (at 4 µg/puff) was more likely to produce overall symptom resolution (reduction in nasal blockage, sneezing/itching/coughing and nasal secretion measured with a daily record chart) at four weeks post-treatment (a primary outcome). The risk ratio (RR) was 3.17 (95% CI 1.38 to 7.29).One study compared capsaicin to budesonide (an intranasal corticosteroid). This study found that patients treated with capsaicin had a better overall symptom score compared to those treated with budesonide (MD 2.50, 95% CI 1.06 to 3.94, VAS of 0 to 10). However, there were no differences in the individual symptom scores for headache, postnasal drip, rhinorrhoea, nasal blockage, sneezing and sore throat assessed during the last three days of a four-week treatment.One study compared two different regimens of capsaicin administration: five treatments in one day versus five treatments given every two to three days during two weeks. Using daily record charts, the study reported significant improvement of individual symptom scores for rhinorrhoea in patients treated five times per day, however numerical data were not presented. There were no improvements in the other outcomes: rhinorrhoea, nasal obstruction, sneezing and overall nasal symptoms, measured on a VAS.Finally, one of these studies also compared three doses of capsaicin (to placebo). Patients treated with a 1 µg versus 4 µg per puff dose of capsaicin had a worse daily record chart overall symptom score resolution (RR 0.63, 95% CI 0.34 to 1.16).Only one study attempted to measure adverse effects (a primary outcome), however due to methodological issues with the assessment we are unable to draw any conclusions.We sought to include other secondary outcomes (e.g. quality of life measures, treatment dropouts, endoscopic scores, turbinate or mucosal size, cost of therapy), but none of these were measured or reported in the included studies.

AUTHORS' CONCLUSIONS

Capsaicin may be an option in the treatment of idiopathic non-allergic rhinitis. It is given in the form of brief treatments, usually during the same day. It appears to have beneficial effects on overall nasal symptoms up to 36 weeks after treatment, based on a few, small studies (low-quality evidence). Well-conducted randomised controlled trials are required to further advance our understanding of the effectiveness of capsaicin in non-allergic rhinitis, especially in patients with non-allergic rhinitis of different types and severity, and using different methods of capsaicin application.

Molecular mechanisms of nasal epithelium in rhinitis and rhinosinusitis

Allergic rhinitis, nonallergic rhinitis, and chronic rhinosinusitis are multifactorial upper airway diseases with high prevalence. Several genetic and environmental factors are proposed to predispose to the pathogenesis of the inflammatory upper airway diseases. Still, the molecular mechanisms leading toward the onset and progression of upper airway diseases are largely unknown. The upper airway epithelium has an important role in sensing the environment and regulating the inhaled air. As such, it links environmental insults to the host immunity. Human sinonasal epithelium serves as an excellent target for observing induced early-phase events, in vivo, and with a systems biological perspective. Actually, increasing number of investigations have provided evidence that altered homeostasis in the sinonasal epithelium might be important in the chronic upper airway inflammation.

Synergy between TLR-2 and TLR-3 signaling in primary human nasal epithelial cells

INTRODUCTION

Although we have a detailed understanding of how single microbial derived triggers activate specialized Toll-like receptors (TLR) on airway epithelial cells, we know little of how these receptors react in a more complex environment. In everyday life, nasal epithelial cells are exposed to multiple TLR agonists, therefore we explored whether exposure to one trigger could affect the responsiveness to another TLR trigger.

METHODS

Primary nasal epithelium from healthy individuals and the bronchial epithelium cell line NCI-H292 were exposed in vitro to different TLR specific agonists. The effect on the expression of different TLRs was determined using the q-PCR. We also evaluated the effect of TLR-3 stimulation on TLR-2, functionally using ELISA to determine levels of secreted mediators.

RESULTS

Stimulation of airway epithelial cells with a specific TLR agonist affects gene expression of other TLRs. In primary nasal epithelium, poly(I:C) challenge results in an up-regulation of the TLR-1, TLR-2, and TLR-3 genes and reduction of expression of TLR-5. Poly(I:C) induced activation of TLR-2 contributes to stronger cell responses to a TLR-2 agonist and regulation of these synergistic responses may take place at the mRNA level of IL-6 and IL-8. The effect of TLR-3 stimulation on TLR-2 functionality and most of the effects on the expression of other TLRs could be replicated in NCI-H292. Poly(I:C) failed to up-regulate TLR-1 and showed an additional up-regulation of TLR-4.

CONCLUSION

Our data suggest that to better understand TLR mediated innate responses we need to consider the impact of the presence of multiple triggers.

dsRNA-induced changes in gene expression profiles of primary nasal and bronchial epithelial cells from patients with asthma, rhinitis and controls

Background

Rhinovirus infections are the most common cause of asthma exacerbations. The complex responses by airway epithelium to rhinovirus can be captured by gene expression profiling. We hypothesized that: a) upper and lower airway epithelium exhibit differential responses to double-stranded RNA (dsRNA), and b) that this is modulated by the presence of asthma and allergic rhinitis.

Objectives

Identification of dsRNA-induced gene expression profiles of primary nasal and bronchial epithelial cells from the same individuals and examining the impact of allergic rhinitis with and without concomitant allergic asthma on expression profiles.

Methods

This study had a cross-sectional design including 18 subjects: 6 patients with allergic asthma with concomitant rhinitis, 6 patients with allergic rhinitis, and 6 healthy controls. Comparing 6 subjects per group, the estimated false discovery rate was approximately 5%. RNA was extracted from isolated and cultured primary epithelial cells from nasal biopsies and bronchial brushings stimulated with dsRNA (poly(I:C)), and analyzed by microarray (Affymetrix U133+ PM Genechip Array). Data were analysed using R and the Bioconductor Limma package. Overrepresentation of gene ontology groups were captured by GeneSpring GX12.

Results

In total, 17 subjects completed the study successfully (6 allergic asthma with rhinitis, 5 allergic rhinitis, 6 healthy controls). dsRNA-stimulated upper and lower airway epithelium from asthma patients demonstrated significantly fewer induced genes, exhibiting reduced down-regulation of mitochondrial genes. The majority of genes related to viral responses appeared to be similarly induced in upper and lower airways in all groups. However, the induction of several interferon-related genes (IRF3, IFNAR1, IFNB1, IFNGR1, IL28B) was impaired in patients with asthma.

Conclusions

dsRNA differentially changes transcriptional profiles of primary nasal and bronchial epithelial cells from patients with allergic rhinitis with or without asthma and controls. Our data suggest that respiratory viruses affect mitochondrial genes, and we identified disease-specific genes that provide potential targets for drug development.

Characterisation of interleukin-10 expression on different vascular structures in allergic nasal mucosa

BACKGROUND

Interleukin-10 (IL-10) is a negative regulator of immune responses and was previously shown to be expressed by human nasal endothelial cells, while the adhesion molecule MECA-79 plays a role in trans-endothelial migration of immune competent cells. In this study we investigate the relationship between endothelial IL-10 and MECA-79 expression to address the question whether immune competent cells could be affected at the mucosal entry site.

METHODS

Nasal turbinate biopsies were taken from house dust mite allergic patients, before and after nasal allergen provocation. Subsequent slides of biopsies were stained for IL10, MECA-79, CD34, and IL10-Receptor. Capillaries, arteries/veins, and sinusoids were evaluated separately.

RESULTS

90% of sinusoids are IL-10 positive and all sinusoids are negative for MECA-79, while 4.8% of capillaries are positive for IL-10, and 2.2% are positive for MECA-79. Although about 47% of arteries/veins are positive for IL-10 and 57.1% are positive for MECA-79, only about 20% are positive for both markers. Furthermore, we showed that the myo-fibroblasts surrounding all sinusoids stain positive for IL10R.

CONCLUSIONS

IL10 expression on vascular structures is not related to MECA expression for sinusoids and capillaries and only partly related on arteries/veins, however sinusoidal endothelial IL10 expression is always seen in combination with IL-10R expression of sinusoidal myo-fibroblasts.

The impact of allergic rhinitis and asthma on human nasal and bronchial epithelial gene expression

Background

The link between upper and lower airways in patients with both asthma and allergic rhinitis is still poorly understood. As the biological complexity of these disorders can be captured by gene expression profiling we hypothesized that the clinical expression of rhinitis and/or asthma is related to differential gene expression between upper and lower airways epithelium.

Objective

Defining gene expression profiles of primary nasal and bronchial epithelial cells from the same individuals and examining the impact of allergic rhinitis with and without concomitant allergic asthma on expression profiles.

Methods

This cross-sectional study included 18 subjects (6 allergic asthma and allergic rhinitis; 6 allergic rhinitis; 6 healthy controls). The estimated false discovery rate comparing 6 subjects per group was approximately 5%. RNA was extracted from isolated and cultured epithelial cells from bronchial brushings and nasal biopsies, and analyzed by microarray (Affymetrix U133+ PM Genechip Array). Data were analysed using R and Bioconductor Limma package. For gene ontology GeneSpring GX12 was used.

Results

The study was successfully completed by 17 subjects (6 allergic asthma and allergic rhinitis; 5 allergic rhinitis; 6 healthy controls). Using correction for multiple testing, 1988 genes were differentially expressed between healthy lower and upper airway epithelium, whereas in allergic rhinitis with or without asthma this was only 40 and 301 genes, respectively. Genes influenced by allergic rhinitis with or without asthma were linked to lung development, remodeling, regulation of peptidases and normal epithelial barrier functions.

Conclusions

Differences in epithelial gene expression between the upper and lower airway epithelium, as observed in healthy subjects, largely disappear in patients with allergic rhinitis with or without asthma, whilst new differences emerge. The present data identify several pathways and genes that might be potential targets for future drug development.

Role of innate immunity in the pathogenesis of chronic rhinosinusitis: progress and new avenues

Chronic rhinosinusitis is a heterogeneous and multifactorial disease with unknown etiology. Aberrant responses to microorganisms have been suggested to play a role in the pathophysiology of the disease. Research has focused on the presence, detection, response to, and eradication of these potential threats. Main topics seem to center on the contribution of structural cells such as epithelium and fibroblasts, on the consequences of activation of pattern-recognition receptors, and on the role of antimicrobial agents. This research should be viewed not only in the light of a comparison between healthy and diseased individuals, but also in a comparison between patients who do or do not respond to treatment. New players that could play a role in the pathophysiology seem to surface at regular intervals, adding to our understanding (and the complexity) of the disease and opening new avenues that may help fight this incapacitating disease.

The transcription factor GATA3 is essential for the function of human type 2 innate lymphoid cells

Type 2 innate lymphoid cells (ILC2s) are part of a large family of ILCs that are important effectors in innate immunity, lymphoid organogenesis, and tissue remodeling. ILC2s mediate parasite expulsion but also contribute to airway inflammation, emphasizing the functional similarity between these cells and Th2 cells. Consistent with this, we report that the transcription factor GATA3 was highly expressed by human ILC2s. CRTH2(+) ILC2s were enriched in nasal polyps of patients with chronic rhinosinusitis, a typical type 2-mediated disease. Nasal polyp epithelial cells expressed TSLP, which enhanced STAT5 activation, GATA3 expression, and type 2 cytokine production in ILC2s. Ectopic expression of GATA3 in Lin(-)CD127(+)CRTH2(-) cells resulted in induction of CRTH2 and the capacity to produce high amounts of type 2 cytokines in response to TSLP plus IL-33. Hence, we identify GATA3, potently regulated by TSLP, as an essential transcription factor for the function of human ILC2s.

No mucosal atrophy and reduced inflammatory cells: active-controlled trial with yearlong fluticasone furoate nasal spray

BACKGROUND

Fluticasone furoate nasal spray (FFNS) and mometasone furoate nasal spray (MFNS) are well tolerated and more effective than placebo at relieving the symptoms of seasonal and perennial allergic rhinitis. Effects of FFNS on the nasal histology have not been previously reported. This study examines the effects of FFNS and MFNS, administered daily for 1 year, on the nasal mucosa in subjects with perennial allergic rhinitis.

METHODS

Subjects with perennial allergic rhinitis were randomized 1:1 to q.d., open-label treatment with FFNS, 110 μg, or MFNS, 200 μg, for 1 year. These groups and a healthy control group that did not receive study medication underwent nasal biopsies at baseline and 12 months.

RESULTS

The nasal biopsy population comprised 96 participants (37 using FFNS, 42 using MFNS, and 17 healthy controls). Epithelial thickness did not change appreciably from baseline to week 52 in any of the groups and mean change from baseline did not differ between FFNS and MFNS (least square mean difference, -0.001 mm, 95% confidence interval, -0.007, 0.006). Although not tested for significance, improvements over baseline were observed in epithelial histology in the FFNS group with more epithelium including intact columnar and ciliated epithelial cells. No appreciable change in the percentage of goblet cells was established. FFNS and MFNS were associated with decreases in epithelial and subepithelial nasal mucosal eosinophils and basophils from baseline to week 52. The percentage of subjects with no inflammatory cells at week 52 was 49 and 33% for eosinophils and 46 and 24% for basophils, for FFNS and MFNS, respectively.

CONCLUSION

Yearlong therapy with either FFNS or MFNS showed no changes in epithelial thickness or the percentage of goblet cells as well as a reduction in inflammatory cell infiltrate. FFNS was associated with improvements in epithelial histology. These data support the long-term safety of FFNS in subjects with perennial allergic rhinitis.

Fungus: a role in pathophysiology of chronic rhinosinusitis, disease modifier, a treatment target, or no role at all?

Fungal spores, due to their ubiquitous nature, are continuously inhaled and deposited on the airway mucosa. This article focuses on the potential role of fungi in chronic rhinosinusitis (CRS). Five forms of fungal disease affecting the nose and paranasal sinuses have been recognized: (1) acute invasive fungal rhinosinusitis (including rhinocerebral mucormycosis), (2) chronic invasive fungal rhinosinusitis, (3) granulomatous invasive fungal rhinosinusitis, (4) fungal ball (mycetoma), and (5) noninvasive (allergic) fungal rhinosinusitis. There are several potential deficits in the innate and potentially also acquired immunity of CRS patients that might reduce or change their ability to react to fungi. There are not many arguments to suggest a causative role for fungi in CRS with or without nasal polyps. However, due to the intrinsic or induced change in immunity of CRS patients, fungi might have a disease-modifying role.

Selective accumulation of langerhans-type dendritic cells in small airways of patients with COPD

Background

Dendritic cells (DC) linking innate and adaptive immune responses are present in human lungs, but the characterization of different subsets and their role in COPD pathogenesis remain to be elucidated. The aim of this study is to characterize and quantify pulmonary myeloid DC subsets in small airways of current and ex-smokers with or without COPD.

Methods

Myeloid DC were characterized using flowcytometry on single cell suspensions of digested human lung tissue. Immunohistochemical staining for langerin, BDCA-1, CD1a and DC-SIGN was performed on surgical resection specimens from 85 patients. Expression of factors inducing Langerhans-type DC (LDC) differentiation was evaluated by RT-PCR on total lung RNA.

Results

Two segregated subsets of tissue resident pulmonary myeloid DC were identified in single cell suspensions by flowcytometry: the langerin+ LDC and the DC-SIGN+ interstitial-type DC (intDC). LDC partially expressed the markers CD1a and BDCA-1, which are also present on their known blood precursors. In contrast, intDC did not express langerin, CD1a or BDCA-1, but were more closely related to monocytes.

Quantification of DC in the small airways by immunohistochemistry revealed a higher number of LDC in current smokers without COPD and in COPD patients compared to never smokers and ex-smokers without COPD. Importantly, there was no difference in the number of LDC between current and ex-smoking COPD patients.

In contrast, the number of intDC did not differ between study groups. Interestingly, the number of BDCA-1+ DC was significantly lower in COPD patients compared to never smokers and further decreased with the severity of the disease. In addition, the accumulation of LDC in the small airways significantly correlated with the expression of the LDC inducing differentiation factor activin-A.

Conclusions

Myeloid DC differentiation is altered in small airways of current smokers and COPD patients resulting in a selective accumulation of the LDC subset which correlates with the pulmonary expression of the LDC-inducing differentiation factor activin-A. This study identified the LDC subset as an interesting focus for future research in COPD pathogenesis.

Diminished response to grass pollen allergen challenge in subjects with concurrent house dust mite allergy

INTRODUCTION

The clinical manifestation of allergic rhinitis is influenced by many factors; while different subpopulations are not well defined. Different combinations of allergic sensitization may lead to different clinical manifestations of allergic disease.

METHODS

In a nasal allergen challenge model we compared allergic rhinitis symptoms between subjects mono-sensitized to grass pollen or house dust mite, poly-sensitized subjects, and healthy controls. We measured visual analogue scales of symptoms and peak nasal inspiratory flow. We also compared serum total IgE, allergen-specific IgE and IgG4, and basophil histamine release.

RESULTS

Nasal challenge with grass pollen extract led to a significantly larger increase in subjective (p = 0.031) and objective (p = 0.001) nasal symptoms in grass pollen mono-sensitized subjects than in poly-sensitized subjects. No differences were found in serum levels of allergen-specific IgE and IgG4 or in biological activity of IgE (basophil histamine release) between mono-sensitized and poly-sensitized subjects. We found a strong inverse correlation between serum allergen-specific IgE and basophil histamine release (-0.789, p = 0.001).

CONCLUSIONS

Grass pollen mono-sensitized subjects have a more severe clinical response to nasal challenge than poly-sensitized subjects. This cannot be explained by serum levels of IgE or its biological activity. The continuous allergen exposure in poly-sensitized subjects may alter local immuno-regulatory processes, leading to a reduced clinical response to allergen challenge.

The effect of topical amphotericin B on inflammatory markers in patients with chronic rhinosinusitis: a multicenter randomized controlled study

BACKGROUND

It has been suggested that an exaggerated immune response to fungi is crucial in the pathogenesis of chronic rhinosinusitis (CRS). Based on this rationale, the use of topical antifungals (amphotericin B) has been advocated. Studies on its clinical effectiveness are, however, contradictory.

OBJECTIVES

To examine the effect of nasal antifungal treatment on secreted mediators in samples of nasal lavage fluid from patients with CRS with or without nasal polyps (NP).

METHODS

Part two of a prospective double-blind, placebo-controlled multicenter clinical trial investigating the effect of 13 weeks of treatment with amphotericin B or placebo on the levels of pro-inflammatory cytokines, chemokines and growth factors (i.e., IL-1beta, IL-1RA, IL-2, IL-2R, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12 (p40/p70 subunits), IL-13, IL-15, IL-17, TNF-alpha, IFN-alpha, IFN-gamma, G-CSF, GM-CSF, MIP-1alpha, MIP-1beta, IP-10, MIG, eotaxin, RANTES, MCP-1, MCP-2, MCP-3, VEGF, EGF, FGF-basic, HGF, Gro-alpha) and albumin via a fluorescent enzyme immunoassay in nasal lavage specimens of CRS patients with or without NP.

RESULTS

Topical amphotericin B had no significant effect on the level of any of the tested pro-inflammatory cytokines, chemokines, and growth factors in CRS nasal lavage samples. Treatment with placebo, however, increased the level of MIP-1alpha and MIP-1beta, which are mediators involved in wound healing.

CONCLUSIONS

Topical amphotericin B has no significant effect on activation markers of nasal inflammatory cells in chronic rhinosinusitis with or without nasal polyps.

Comparison of four nasal sampling methods for the detection of viral pathogens by RT-PCR-A GA(2)LEN project

The aim of this study was to compare the efficacy and patient discomfort between four techniques for obtaining nasal secretions. Nasal secretions from 58 patients with symptoms of a common cold, from three clinical centers (Amsterdam, Lodz, Oslo), were obtained by four different methods: swab, aspirate, brush, and wash. In each patient all four sampling procedures were performed and patient discomfort was evaluated by a visual discomfort scale (scale 1–5) after each procedure. Single pathogen RT-PCRs for Rhinovirus (RV), Influenza virus and Adenovirus, and multiplex real-time PCR for RV, Enterovirus, Influenza virus, Adenovirus, Respiratory Syncytial Virus (RSV), Parainfluenza virus, Coronavirus, Metapneumovirus, Bocavirus and Parechovirus were performed in all samples. A specific viral cause of respiratory tract infection was determined in 48 patients (83%). In these, the detection rate for any virus was 88% (wash), 79% (aspirate), 77% (swab) and 74% (brush). The degree of discomfort reported was 2.54 for swabs, 2.63 for washes, 2.68 for aspirates and 3.61 for brushings. Nasal washes yielded the highest rate of viral detection without excessive patient discomfort. In contrast, nasal brushes produced the lowest detection rates and demonstrated the highest level of discomfort.

Primary Nasal Epithelium Exposed to House Dust Mite Extract Shows Activated Expression in Allergic Individuals

Nasal epithelial cells form the outermost protective layer against environmental factors. However, this defense is not just physical; it has been shown that epithelial cells respond by the production of inflammatory mediators that may affect local immune responses. In this research we set out to characterize potential differences between the responses of nasal epithelium from healthy and allergic individuals to house dust mite (HDM) allergen. These differences will help us to define local mechanisms that could contribute to allergic disease expression. Epithelial cells were cultured from nasal biopsies taken from five healthy and five allergic individuals. These cultures were exposed for 24 hours to culture medium containing HDM allergen, or to culture medium alone. Isolated RNA was used for microarray analysis. Gene-ontology of the response in healthy epithelium revealed mainly up-regulation of chemokines, growth factors, and structural proteins. Moreover, we saw increased expression of two transcription factors (NF-kappaB and AP-1) and their regulatory members. The expression pattern of epithelium from allergic individuals in the absence of the HDM stimulus suggests that it is already in an activated state. Most striking is that, while the already activated NF-kappaB regulatory pathway remained unchanged in allergic epithelium, the AP-1 pathway is down-regulated upon exposure to HDM allergen; this is contrary to what we see in healthy epithelium. Clear differences in the expression pattern exist between epithelial cells isolated from healthy and allergic individuals at baseline and between their responses to allergen exposure; these differences may contribute to the inflammatory response.

Dendritic cell populations in colon and mesenteric lymph nodes of patients with Crohn's disease

Dendritic cells (DCs) are key cells in innate and adaptive immune responses that determine the pathophysiology of Crohn's disease. Intestinal DCs migrate from the mucosa into mesenteric lymph nodes (MLNs). A number of different markers are described to define the DC populations. In this study we have identified the phenotype and localization of intestinal and MLN DCs in patients with Crohn's disease and non-IBD patients based on these markers. We used immunohistochemistry to demonstrate that all markers (S-100, CD83, DC-SIGN, BDCA1-4, and CD1a) showed a different staining pattern varying from localization in T-cell areas of lymph follicles around blood vessels or single cells in the lamina propria and in the MLN in the medullary cords and in the subcapsular sinuses around blood vessels and in the T-cell areas. In conclusion, all different DC markers give variable staining patterns so there is no marker for the DC.

Immuno-histological analysis of dendritic cells in nasal biopsies of IgA nephropathy patients

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Intranasal vaccination of patients with IgAN has shown mucosal and systemic IgA hyporesponsiveness. Here, we investigated whether this IgA hyporesponse in IgAN patients can be explained by reduced numbers or altered subset distribution of dendritic cells (DCs) in nasal mucosa.

METHODS

Eighteen IgAN patients and 18 healthy volunteers were recruited for this study. Nasal biopsies were taken, after local anaesthesia, from the lower edge of the inferior turbinate. Staining for different subsets of DCs was performed using specific monoclonal antibodies. To detect myeloid DCs, we used CD1a, DC-SIGN and blood dendritic cell antigen-1 (BDCA-1) as a marker and for plasmacytoid DCs we used BDCA-2. DC-cell numbers in the epithelium and in lamina propria were counted separately and expressed as positively stained cells per mm(2).

RESULTS

Both myeloid and plasmacytoid DC could be demonstrated in nasal biopsies. Quantification showed that IgAN patients contained significantly more DC-SIGN-positive cells in the lamina propria compared to controls. In addition, in IgAN patients, we observed more CD1a-positive cells in the epithelium. No differences in BDCA-1 and BDCA-2-positive cells were found between patients and controls. The number of positively stained cells in the epithelial layer correlated strongly with the number of positively stained cells in the lamina propria.

CONCLUSIONS

Patients with IgAN have higher numbers of CD1a-positive cells in the epithelial layer and more DC-SIGN-positive cells in the lamina propria. Therefore, the earlier observed IgA hyporesponsiveness in IgAN patients after mucosal vaccination cannot be explained by lower numbers of nasal DCs.

Radical surgery: effect on quality of life and pain in chronic rhinosinusitis

OBJECTIVES

Despite effective medical therapy and repetitive endoscopic sinus surgery in the treatment of chronic rhinosinusitis, there still remains a small group of patients without improvement of symptoms. This study evaluates the effect of radical surgery on quality of life and pain in these patients with recalcitrant disease.

STUDY DESIGN

A prospective, questionnaire-based study was conducted in 23 patients who underwent Denker's procedure for refractory chronic rhinosinusitis. Quality of life and pain were evaluated before surgery and 12 months and 2 years after surgery with the SF-36 and McGill Pain Questionnaire.

RESULTS

Seven of the eight mean scores of the SF-36 postoperatively improved after surgery, with statistical significance for Role Physical (RP) P=0.048. Bodily pain showed a strong tendency to significance. Results of the McGill Pain Questionnaire show a significant improvement in most of the subscores after surgery implying less pain.

CONCLUSION

Radical surgery improves the physical burden of chronic rhinosinusitis and pain experience in patients with therapy resistant chronic rhinosinusitis.

RSV-induced bronchiolitis but not upper respiratory tract infection is accompanied by an increased nasal IL-18 response

The aim of this study was to investigate potential differences in the local nasal immune response between bronchiolitis and upper respiratory tract infection induced by respiratory syncytial virus (RSV). Nasal brush samples were obtained from 14 infants with RSV bronchiolitis and from 8 infants with RSV upper respiratory tract infection. The samples were taken during infection (acute phase) and 2-4 weeks later (convalescent phase). Cytospin preparations were stained immunohistochemically for T cells, macrophages, and eosinophils. Staining also took place for intercellular adhesion molecule-1 (ICAM-1), T-helper 1 (Th1)-like (interleukin-12 [IL-12], interferon-gamma [IFN-gamma]), Th2-like (IL-4, IL-10), and proinflammatory cytokines (IL-6, IL-8, IL-18). During both RSV-induced bronchiolitis and upper respiratory tract infection, cellular inflammation was observed. This was characterised by an increase in the numbers of nasal macrophages, which tended to be higher in bronchiolitis than in upper respiratory tract infection. Numbers of T lymphocytes and ICAM-1 positive cells increased during both bronchiolitis and upper respiratory tract infection. There were no differences between numbers in the groups. Interestingly, a distinct nasal proinflammatory cytokine response was observed in RSV-induced bronchiolitis. This is characterised by an increase in the number of IL-18 positive cells. This increase is specific for bronchiolitis, as a similar increase could not be detected in RSV-induced upper respiratory tract infection. Numbers of IL-6 and IL-12 positive cells were higher in both bronchiolitis and upper respiratory tract infection, and there were no differences between the groups. By contrast, the number of IL-8, IFN-gamma, IL-4, and IL-10-positive cells remained constant. In conclusion, clear differences were found in nasal immune responses of children with RSV-induced upper respiratory tract infection or bronchiolitis. The induction of a strong IL-18 response was typical for bronchiolitis, as this could not be observed in RSV-induced upper respiratory tract infection, and could explain the eosinophilia that is observed frequently during bronchiolitis.