Increased expression and role of thymic stromal lymphopoietin in nasal polyposis

Upper Airway Alarmin Cytokine Expression in Asthma of Different Severities

Background: The secretion of alarmin cytokines by epithelial cells, including thymic stromal lymphopoietin (TSLP), interleukin (IL)-25, and IL-33, initiates inflammatory cascades in asthma. However, alarmin cytokine expression in the upper airways in asthma remains largely unknown. Methods: We recruited 40 participants with asthma into four groups as per the Global Initiative for Asthma (GINA) steps (10 in each group of GINA 1/2, 3, 4, and 5). Cells were derived from nasal, buccal, and throat brushings. Intracellular cytokine expression (TSLP, IL-25, and IL-33) was assessed by flow cytometry in cytokeratin 8+ (Ck8+) epithelial cells immediately following collection. Results: TSLP was significantly increased (p < 0.001) in GINA 5 patients across nasal, buccal, and throat Ck8+ epithelial cells, while IL-25 was elevated in nasal and throat samples (p < 0.003), and IL-33 levels were variable, compared with GINA 1-4 patients. Individual GINA subgroup comparison showed that TSLP levels in nasal samples from GINA 5 patients were significantly (p = 0.03) elevated but did not differ between patients with and without nasal comorbidities. IL-25 and IL-33 (obtained from nasal, buccal, and throat samples) were not significantly different in individual groups. Conclusions: Our study demonstrates for the first time that Ck8+ nasal epithelial cells from GINA 5 asthma patients express elevated levels of TSLP.

Endotypic heterogeneity and pathogenesis in chronic rhinosinusitis

PURPOSE OF REVIEW

This review aims to provide updates in realms of endotypic heterogeneity, pathogenesis at the molecular level, potential of biomarkers, and cutting-edge scope of biologics in CRS.

RECENT FINDINGS

High-dimensional analyses, such as transcriptomes, and machine learning, have significantly enhanced CRS endotyping, uncovering diverse pathogenetic mechanisms contributing to its heterogeneity. The dynamic process of epithelial remodeling in CRS pathogenesis has gained more clarity and support as exemplified by IL-13 and oncostatin M (OSM) that are shown intricately linked to epithelial barrier dysfunction. Moreover, anti-dsDNA autoantibody, BAFF, periostin, and cystatin SN show promise as potentials biomarkers, offering diagnostic and prognostic value for CRS.

SUMMARY

The identification of inflammatory molecules involved in endotype specific signaling pathways provides insights into the underlying mechanisms and verifiable biomarkers for diagnosis and prediction of disease severity. More comprehensive clinical studies should be conducted to facilitate biologics from bench to bedside in treating CRS.

Mast Cells in Aspirin-Exacerbated Respiratory Disease

PURPOSE OF REVIEW

Aspirin-exacerbated respiratory disease (AERD) is a syndrome of high type 2 inflammation and is known to critically involve mast cell activation. The mast cell is an important cell in the baseline inflammatory processes in the upper and lower airway by maintaining and amplifying type 2 inflammation. But it also is prominent in the hypersensitivity reaction to COX-1 inhibition which defines this condition.

RECENT FINDINGS

Recent work highlights the mast cell as a focal point in AERD pathogenesis. Using AERD as a specific model of both high type 2 asthma and chronic sinusitis, the role of mast cell activity can be better understood in other aspects of airway inflammation. Further dissecting out the mechanism of COX-1-mediated mast cell activation in AERD will be an important next phase in our understanding of NSAID-induced hypersensitivity as well as AERD pathophysiology.

Tezepelumab Efficacy in Patients with Severe, Uncontrolled Asthma with Comorbid Nasal Polyps in NAVIGATOR

Purpose

Tezepelumab, a human monoclonal antibody, blocks thymic stromal lymphopoietin. In the phase 3 NAVIGATOR study (NCT03347279), tezepelumab reduced annualized asthma exacerbation rates (AAERs) versus placebo, irrespective of baseline disease characteristics, and improved lung function and symptom control versus placebo in adults and adolescents with severe, uncontrolled asthma. We assessed the efficacy of tezepelumab in patients with severe asthma with or without nasal polyps (NPs) in the 2 years before randomization in NAVIGATOR.

Methods

Patients with severe asthma (N=1059) were randomized (1:1) and received tezepelumab 210 mg or placebo every 4 weeks subcutaneously for 52 weeks. Prespecified exploratory analyses included: AAER over 52 weeks and changes from baseline to week 52 in pre-bronchodilator forced expiratory volume in 1 second, Sino-Nasal Outcome Test (SNOT)-22 scores, and asthma control and health-related quality life (HRQoL) outcomes in NP subgroups. Changes from baseline in fractional exhaled nitric oxide (FeNO), blood eosinophil counts, total immunoglobulin E (IgE), eosinophil-derived neurotoxin (EDN), matrix metalloproteinase-10 (MMP-10), and serum interleukin (IL)-5, IL-6, IL-8 and IL-13 were assessed (post hoc).

Results

Tezepelumab reduced the AAER over 52 weeks versus placebo by 85% (95% confidence interval [CI]: 72, 92; n=118) and 51% (95% CI: 40, 60; n=941) in patients with and without NPs, respectively. At week 52, tezepelumab improved lung function, asthma control and HRQoL versus placebo in patients with and without NPs. Tezepelumab reduced SNOT-22 total scores (least-squares mean difference versus placebo [95% CI]) in patients with NPs at 28 weeks (-12.57 points [-19.40, -5.73]) and 52 weeks (-10.58 points [-17.75, -3.41]). At week 52, tezepelumab reduced blood eosinophil counts and FeNO, IgE, IL-5, IL-13, EDN and MMP-10 levels versus placebo, irrespective of NP status.

Conclusion

Tezepelumab resulted in clinically meaningful improvements in sino-nasal symptoms and asthma outcomes in patients with severe asthma with comorbid NPs.

Macroarray expression analysis of cytokines and prostaglandin metabolism-related genes in chronic rhinosinusitis

Background

Chronic rhinosinusitis (CRS) can be divided into endotypes by functional or pathophysiologic findings.

Objective

The aim of this study was to analyze the expression of cytokines, prostaglandin (PG) synthases, and their receptors related to the pathogenesis of CRS, especially those contributing to nasal polyp (NP) formation.

Methods

NPs and uncinate tissue (UT) samples were collected from 90 patients who underwent endoscopic sinus surgery. They included 75 patients with CRS (including 45 with eosinophilic CRS [eCRS] and 30 with non-eCRS) and 15 patients without CRS. A total of 30 genes were selected for our original DNA array plate to analyze the levels of expression of 10 cytokines (IFN-γ, IL-4, IL-5, IL-10, IL-13, IL-17A, IL-22, IL-25, IL-33, and TSLP), 4 prostaglandin synthases (prostaglandin D2 [PGD2] synthase, prostaglandin E2 synthase, COX-1, and COX-2), and their 16 receptors. Clustering analysis was performed according to the expression results, and clinical findings of patients from each cluster were investigated.

Results

The samples could be divided into 3 clusters. Cluster 1 showed elevated levels of expression of IL4, IL5, IL13, TSLP, IL1RL1 (ST2 [an IL-33 receptor]), HPGDS, and GPR44 (CRTH2, a PGD2 receptor); cluster 2 showed elevated levels of expression of IL17A and PTGES; and cluster 3 showed an elevated level of expression of IL25. Regarding clinical features, the main characteristics of each cluster were as follows: NPs from patients with eCRS for cluster 1, NPs and/or UT samples from patients with non-eCRS for cluster 2, and UTs from patients with non-CRS for cluster 3.

Conclusion

The results suggest that there are associations between type 2 inflammation/PGD2 and eCRS and also between type 3 inflammation/prostaglandin E2 and non-eCRS.

Long-Term Cryopreservation of Nasal Polyp Tissue in a Biobank for the Isolation and Culture of Primary Epithelial Cells

Epithelial cells may play an important role in the pathologic process of chronic rhinosinusitis with nasal polyps. Therefore, providing epithelial cells from a biobank could greatly contribute to further research. In the present work, the isolation of epithelial cells from long-term cryopreserved tissue is demonstrated. Polyp tissues were cryopreserved in a commercially available freezing medium with dimethyl sulfoxide and stored in liquid nitrogen. The outgrowth and proliferation of epithelial cells from cryopreserved tissue were evaluated and compared to that of fresh tissue. Flow cytometric analysis with anti-cytokeratin, anti-p63, and anti-Ki-67 was performed to identify epithelial cells and determine differentiation and proliferation. A functionality test was performed by determining type 2–relevant proteins, representatively thymic stromal lymphopoietin (TSLP) and periostin, using ELISA. Primary epithelial cells could be isolated from cryopreserved tissues. Cells from cryopreserved tissues showed comparable outgrowth and proliferation to that of fresh tissue. Isolated epithelial cells showed high cytokeratin, p63, and Ki-67 expression and secreted TSLP and periostin. In the present study, a method for long-term cryopreservation of polyp tissue was established, thereby enabling the isolation and cell culture of primary cell culture at a later time. Epithelial cell availability should be greatly improved by including this method in a biobank.

Increased Expression of SERPINB10 Associated with Postoperative Recurrence in Chronic Rhinosinusitis with Nasal Polyps

Background

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common upper airway inflammatory disorder with a high rate of postoperative recurrence. SERPINB10 is a proinflammatory cytokine expressed on epithelial cells, but its role in CRSwNP has not been described. This study is aimed at exploring the SERPINB10 expression in CRSwNP and its relationship with postoperative recidivation.

Methods

We recruited 140 individuals, consisting of 60 patients with CRSwNP, 40 patients with chronic rhinosinusitis without nasal polyps (CRSsNP), and 40 healthy controls (HCs). Tissue specimens were collected during the surgery, and SERPINB10 expression was determined by reverse transcription-polymerase chain reaction, western blotting, and immunofluorescence. We determined the tissue SERPINB10 expression levels in CRSwNP and examined its clinical value in predicting postoperative recurrence.

Results

We determined that tissue SERPINB10 mRNA and protein levels were increased in the CRSwNP group, especially in the recurrent CRSwNP group, compared with the CRSsNP and HC groups (p < 0.05), and SERPINB10 mRNA levels were correlated with peripheral and tissue eosinophil counts and percentages (p < 0.05). Binary logistic regression analysis and receiver operating characteristic (ROC) curves suggested that the expressions of tissue SERPINB10 mRNA were significantly linked to postoperative recurrence in CRSwNP patients (AUC = 0.741, p < 0.001).

Conclusion

Elevated local SERPINB10 levels in patients with CRSwNP were related to tissue eosinophilic inflammation and disease recurrence. These data suggested that SERPINB10 might contribute to the eosinophilic inflammation in CRSwNP and appeared to be a potential biomarker for the prediction of relapse after surgery.

TLR Signals in Epithelial Cells in the Nasal Cavity and Paranasal Sinuses

The respiratory tract is constantly at risk of invasion by microorganisms such as bacteria, viruses, and fungi. In particular, the mucosal epithelium of the nasal cavity and paranasal sinuses is at the very forefront of the battles between the host and the invading pathogens. Recent studies have revealed that the epithelium not only constitutes a physical barrier but also takes an essential role in the activation of the immune system. One of the mechanisms equipped in the epithelium to fight against microorganisms is the Toll-like receptor (TLR) response. TLRs recognize common structural components of microorganisms and activate the innate immune system, resulting in the production of a plethora of cytokines and chemokines in the response against microbes. As the epithelia-derived cytokines are deeply involved in the pathogenesis of inflammatory conditions in the nasal cavity and paranasal sinuses, such as chronic rhinosinusitis (CRS) and allergic rhinitis (AR), the molecules involved in the TLR response may be utilized as therapeutic targets for these diseases. There are several differences in the TLR response between nasal and bronchial epithelial cells, and knowledge of the TLR signals in the upper airway is sparse compared to that in the lower airway. In this review, we provide recent evidence on TLR signaling in the upper airway, focusing on the expression, regulation, and responsiveness of TLRs in human nasal epithelial cells (HNECs). We also discuss how TLRs in the epithelium are involved in the pathogenesis of, and possible therapeutic targeting, for CRS and AR.

Particulate Matter Exposure and the Changes in Immune Biomarkers: Effects of Biyeom-Go on the Nasal Mucosa of Patients with Allergic Rhinitis and a Particulate Matter-Treated Mouse Model

This study was to investigate the effects of Biyeom-go (BYG, an herbal formula) on immune biomarkers present in the nasal mucosa of patients with allergic rhinitis under exposure to particulate matter 2.5 (PM2.5), and on changes in goblet cells and immune biomarkers in mice under exposure to Korea diesel particulate matter (KDP20). Thirty patients showing characteristic allergic rhinitis symptoms were enrolled in Jeonju-si, Korea, and treated with BYG thrice a day for four weeks. Changes in the expression of immune biomarkers (interleukin 4 (IL-4), IL-5, IL-8, IL-13, IL-33, and thymic stromal lymphopoietin (TSLP) mRNA), total nasal symptom scores (TNSS), mini-rhinitis-specific quality of life questionnaire (RQLQ) results, and visual analog scale scores were evaluated after 4 weeks of treatment. Additionally, the difference in PM2.5 concentrations in the air in Jeonju-si, Korea (November, 2019 ∼ March, 2020), was analyzed to determine the change in TNSS. KDP20 (100 μg/mL) was exposed to C57BL/6 mice for 10 days; 0.05% Nasonex (a positive control, mometasone furoate), or BYG was administrated for 5 days twice a day. The expression of inflammatory factors was detected via qRT-PCR using nasopharynx tissue samples of mice. BYG treatment was found to be associated with significant improvement in total nasal symptoms, especially itching and sneezing (p < 0.0001), and mini-RQLQ after 4 weeks. IL-8 (p < 0.01), IL-33 (p < 0.01), and TSLP (p < 0.001) expression levels decreased after BYG treatment. In mice, administration of BYG reduced the number of goblet cells increased through KDP20 treatment. KDP20-induced immune biomarkers (IL-33, TSLP, tumor necrosis factor alpha, and IL-8) were also significantly downregulated in the nasopharynx tissue after BYG treatment. Therefore, BYG may show therapeutic effects against allergic rhinitis in humans, and it was confirmed that the expression of PM-induced inflammatory factors in mice was decreased via BYG treatment.

New concepts for the pathogenesis and management of aspirin-exacerbated respiratory disease

PURPOSE OF REVIEW

The purpose of this review is to provide a comprehensive summary of the current understanding of the pathogenesis of aspirin-exacerbated respiratory disease (AERD), and an update on its management.

RECENT FINDINGS

Elevated levels of 15-oxo-eicosatetraenoic acid (15-Oxo-ETE), a newly described metabolite of arachidonic acid, have been identified in nasal polyps of AERD patients. In nasal polyps, activated basophils, and interleukin-5 -receptor-α-positive IL-5Rα+ plasma cells are associated with more severe nasal polyposis in AERD. Alveolar monocyte-derived macrophages and their persistent proinflammatory activation were suggested as putative factors contributing to AERD. Although not AERD-specific, three biological agents are now available for the management of both nasal polyposis and asthma.

SUMMARY

A newly downstream product of 15-lipoxygenase, 15-Oxo-ETE, was recently found to be significantly elevated in nasal polyps from AERD patients. This eicosanoid metabolite likely originates from an interplay between epithelial cells and mast cells. Nasal polyp basophils, IL-5Rα+ plasma cells, and alveolar macrophages were identified as important contributors to inflammation in AERD. Besides traditional aspirin desensitization and treatment for AERD management, several biologics for treatment of asthma are available, including three that have been approved for nasal polyposis. These biologic agents show variable rates of success in controlling AERD symptoms.

Cytokine Signature and Involvement in Chronic Rhinosinusitis with Nasal Polyps

Cytokines are well known to play a central role in chronic rhinosinusitis with nasal polyps (CRSwNP), particularly in maintenance of the inflammatory response and the recruitment of eosinophils. The pathophysiological concepts concerning the involvement of inflammatory cytokines in CRSwNP have gradually evolved. Although the Th2 cytokines environment associated with an eosinophilic infiltration has retained a central role in the genesis of polyps, the role of other cytokine subpopulations has also and more recently been detailed, leading to a specific and complex signature in CRSwNP. The purpose of this review is to summarize the current state of knowledge about the cytokine signature in CRSwNP, the role of cytokines in the pathogenesis of this disease and in the intercellular dialog between epithelial cells, fibroblasts and inflammatory cells. Knowledge of this precise cytokine signature in CRSwNP is fundamental in the perspective of potential targeting biotherapies.

Aspirin Actions in Treatment of NSAID-Exacerbated Respiratory Disease

Non-steroidal Anti-inflammatory drugs (NSAID)-exacerbated respiratory disease (N-ERD) is characterized by nasal polyposis, chronic rhinosinusitis, adult-onset asthma and hypersensitive reactions to cyclooxygenase-1 (COX-1) inhibitors. Among the available treatments for this disease, a combination of endoscopic sinus surgery followed by aspirin desensitization and aspirin maintenance therapy has been an effective approach. Studies have shown that long-term aspirin maintenance therapy can reduce the rate of nasal polyp recurrence in patients with N-ERD. However, the exact mechanism by which aspirin can both trigger and suppress airway disease in N-ERD remains poorly understood. In this review, we summarize current knowledge of aspirin effects in N-ERD, cardiovascular disease, and cancer, and consider potential mechanistic pathways accounting for the effects of aspirin in N-ERD.

Efficacy of Tezepelumab in Patients with Severe, Uncontrolled Asthma with and without Nasal Polyposis: A Post Hoc Analysis of the Phase 2b PATHWAY Study

Background

Tezepelumab is a human monoclonal antibody that blocks thymic stromal lymphopoietin, an epithelial cytokine implicated in asthma pathogenesis, from binding to its heterodimeric receptor. In the phase 2b PATHWAY study, tezepelumab significantly reduced annualized asthma exacerbation rates (AAERs) versus placebo, irrespective of baseline disease characteristics, and improved lung function and symptom control, in adults with severe, uncontrolled asthma. This post hoc analysis assessed the efficacy of tezepelumab in adults with severe, uncontrolled asthma with and without nasal polyposis (NP).

Methods

In this post hoc analysis of the PATHWAY study (NCT02054130), participants (N=550) were randomized 1:1:1:1 to receive subcutaneous tezepelumab 70 mg every 4 weeks (Q4W), 210 mg Q4W or 280 mg every 2 weeks (Q2W), or placebo Q2W, for 52 weeks. The AAER over 52 weeks and the change from baseline to week 52 in blood eosinophil count, fractional exhaled nitric oxide (FeNO) levels and serum levels of interleukin (IL)-5 and IL-13 with tezepelumab 210 mg (the phase 3 dose) and placebo were analyzed in patients grouped by self-reported presence (NP+) or absence (NP-) of NP at screening.

Results

At baseline, NP+ patients had higher blood eosinophil counts, higher FeNO levels and higher serum IL-5 and IL-13 levels than NP- patients. Tezepelumab 210 mg reduced the AAER versus placebo to a similar extent in both NP+ and NP- patients (NP+, 75% [95% confidence interval (CI): 15, 93], n=23; NP-, 73% [95% CI: 47, 86], n=112). Patients treated with tezepelumab 210 mg demonstrated greater reductions in blood eosinophil count and levels of FeNO, IL-5 and IL-13 than placebo-treated patients, irrespective of NP status.

Discussion

Tezepelumab reduced exacerbations and reduced type 2 inflammatory biomarkers in patients with and those without NP, supporting its efficacy in a broad population of patients with severe asthma.

The Role of Epigenetics in the Chronic Sinusitis with Nasal Polyp

PURPOSE OF REVIEW

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common and heterogeneous inflammatory disease. The underlying epigenetic mechanisms and treatment of CRSwNP are partially understood. Of the different epigenetic changes in CRSwNP, histone deacetylases (HDACs), methylation of DNA, and the levels of miRNA are widely studied. Here, we review the human studies of epigenetic mechanisms in CRSwNP.

RECENT FINDINGS

The promoters of COL18A1, PTGES, PLAT, and TSLP genes are hypermethylated in CRSwNP compared with those of controls, while the promoters of PGDS, ALOX5AP, LTB4R, IL-8, and FZD5 genes are hypomethylated in CRSwNP. Promoter hypermethylation suppresses the gene expression, while promoter hypomethylation increases the gene expression. Studies have shown the elevation in the levels of HDAC2, HDAC4, and H3K4me3 in CRSwNP. In CRSwNP patients, there is also an upregulation of certain miRNAs including miR-125b, miR-155, miR-19a, miR-142-3p, and miR-21 and downregulation of miR-4492. Epigenetics takes part in the immunology of CRSwNP and may give rise to endotypes of CRSwNP. Both HDAC2 and the miRNA including miR-18a, miR-124a, and miR-142-3p may take function in the regulation of glucocorticoid resistance. HDAC inhibitors and KDM2B have shown effectiveness in decreasing nasal polyp, and DNA methyltransferase (DNMT) or HDAC inhibitors may have a potential efficacy for the treatment of CRSwNP. Recent advances in the epigenetics of CRSwNP have led to the identification of several potential therapeutic targets for this disease. The use of epigenetics may provide novel and effective biomarkers and therapies for the treatment of nasal polyp.

Biologics in chronic rhinosinusitis with nasal polyposis

OBJECTIVE

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common and heterogeneous inflammatory condition, for which the drivers of the underlying inflammation are not yet fully understood. The use of biologic therapies to target specifically relevant effector cells or cytokines in CRSwNP is a growing field of interest. The objectives of this review are to provide an update on the existing studies of biologics in CRSwNP and to identify potential future areas for further research.

DATA SOURCES

An initial literature review of biologic therapies in CRS was performed through publications gathered from a PubMed search for title/abstract containing "biologic" and "chronic rhinosinusitis." Further manuscripts describing scientific premise for each biologic were then reviewed.

STUDY SELECTIONS

A detailed review of all studies describing biologic therapies targeting inflammation in CRSwNP was performed.

RESULTS

Biologic therapies targeting interleukin (IL)-4Rα, IL-5, IL-5Rα, IL-33, immunoglobulin (Ig)E, and thymic stromal lymphopoietin (TSLP) have all been developed and have been investigated for treatment in CRSwNP, or current research suggests that they may have utility in this area. Only dupilumab, which inhibits IL-4Rα, has gained Food and Drug Administration approval for the treatment of adults with inadequately controlled CRSwNP.

CONCLUSION

Recent advances in our understanding of the fundamental drivers of the chronic respiratory inflammation in CRSwNP has led to the identification of several potential therapeutic targets for this disease. Future clinical success will rely on the availability of biomarker-based endotyping and responder analyses so that clinicians can precisely match each patient to the appropriate biologic, thereby optimizing the proper treatment strategy.

Epithelial cell function and remodeling in nasal polyposis

OBJECTIVE

To review the latest discoveries on airway epithelial cell diversity and remodeling in type 2 inflammation, including nasal polyposis.

DATA SOURCES

Reviews and primary research manuscripts were identified from PubMed, Google, and Bioarchives, using the search words airway epithelium, nasal polyposis, or chronic rhinosinusitis with nasal polyposis AND basal cell, ciliated cell, secretory cell, goblet cell, neuroendocrine cell, pulmonary neuroendocrine cell, ionocyte, brush cell, solitary chemosensory cell, microvillus cell, or tuft cell.

STUDY SELECTIONS

Studies were selected based on novelty and likely relevance to airway epithelial innate immune functions or the pathobiology of type 2 inflammation.

RESULTS

Airway epithelial cells are more diverse than previously appreciated, with specialized subsets, including ionocytes, solitary chemosensory cells, and neuroendocrine cells that contribute to important innate immune functions. In chronic rhinosinusitis with nasal polyposis, the composition of the epithelium is significantly altered. Loss of ciliated cells and submucosal glands and an increase in basal airway epithelial progenitors leads to loss of innate immune functions and an expansion of proinflammatory potential. Type 2 cytokines play a major role in driving this process.

CONCLUSION

Airway epithelial remodeling in chronic rhinosinusitis is extensive, leading to loss of innate immune function and enhanced proinflammatory potential. The mechanisms driving airway remodeling and its sequelae deserve further attention before restitution of epithelial differentiation can be considered a reasonable therapeutic target.

Interleukin-7 Receptor Alpha in Innate Lymphoid Cells: More Than a Marker

Innate lymphoid cells (ILCs) are a group of immune cells that are important for defense against pathogens, tissue repair, and lymphoid organogenesis. They share similar characteristics with various subsets of helper T cells but lack specific antigen receptors. Interleukin-7 (IL-7) and thymic stromal lymphopoietin (TSLP) are cytokines that engage the IL-7Rα and have major roles in dictating the fate of ILCs. Recent advances in the field have revealed transcriptional programs associated with ILC development and function. In this article, we will review recent studies of the role of IL-7 and TSLP in ILC development and function during infection and inflammation.

Association between methylation in nasal epithelial TSLP gene and chronic rhinosinusitis with nasal polyps

Background

This study was performed to determine whether there was any association between abnormal DNA methylation of a thymic stromal lymphopoietin (TSLP) locus and pathogenesis of chronic rhinosinusitis (CRS).

Methods

A total of 48 CRS patients with nasal polyps (CRSwNP), 28 CRS patients without nasal polyps (CRSsNP) and 21 control subjects were enrolled into the study; and evaluated for serum total IgE level, olfactory score and nasal resistance. Samples were obtained from nasal polyps of CRSwNP patients, ethmoid mucosae of CRSsNP patients and inferior turbinate (IT) mucosa of control subjects during surgery, and used to isolate purified primary human nasal epithelial cells (HNECs). Genomic DNA was extracted from purified primary HNECs of each subject and DNA methylation ratios for a selected region of the TSLP gene were screened the using MassARRAY EpiTYPER.

Results

A total of 17 CpG units were analyzed; of which two CpG units (CpG3 and 22:23:24) had increased methylation ratios in the CRSwNP patients compared to the CRSsNP and control subjects after correction for false discovery rate (FDR) (Q < 0.1). The methylation ratios at both CpG3 and CpG22:23:24 units were positively correlated with olfactory score (r = 0.41, P = 0.0001; r = 0.25, P = 0.021) and unilateral nasal resistance at 75 Pa (r = 0.24, P = 0.04; r = 0.24, P = 0.036) and 150 Pa (r = 0.34, P = 0.004; r = 0.25, P = 0.031). Total nasal resistance at 75 Pa/150 Pa or serum total IgE levels were not correlated with the methylation ratios at either CpG unit.

Conclusions

Increased DNA methylation at the TSLP locus is likely to be associated with CRSwNP pathogenesis; however these findings need to be confirmed in larger multicentre group studies.

[Immunology of chronic rhinosinusitis with nasal polyps as a basis for treatment with biologicals]

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous and multifactorial inflammation of the nasal and paranasal mucosa. Until now, no internationally standardized classification could be developed. In most cases, CRS is phenotypically classified according to chronic rhinosinusitis with (CRScNP) and without nasal polyps (CRSsNP). However, recent studies could show that there are numerous endotypes within these phenotypes based on different inflammatory mechanisms. This review describes the important immunological mechanisms of CRScNP and highlights modern treatment options with biologicals directly addressing particular immunological processes.

METHODS

Current knowledge on immunological and molecular processes of CRS, particularly CRScNP, was extracted from Medline, PubMed, national and international study- and guideline-registers, and the Cochrane library by a systematic review of the literature.

RESULTS

Based on current literature, various immunological mechanisms for CRS and CRScNP could be identified. Relevant studies for the treatment of eosinophilic conditions such as asthma or CRScNP are presented and, if available, results of these studies are discussed.

CONCLUSION

The growing insight into the underlying immunological mechanisms of CRScNP could pave the way for new personalized treatment options such as biologicals in the future.

Increased TSLP, IL-33, IL-25, IL-19, IL 21 and amphiregulin (AREG) levels in chronic rhinosinusitis with nasal polyp

OBJECTIVE

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease. The surrogate indicating biomarkers in patients with CRSwNP need further evaluation. The aim of this study was to investigate the association of thymic stromal lymphopoietin (TSLP) and amphiregulin (AREG) cytokines in patients with CRSwNP.

METHODS

Sinonasal tissue samples were collected from 33 patients with CRSwNP and 29 controls. Levels of AREG, IL-19, IL-21, IL-25, IL-33 and TSLP in nasal polyp and control sinonasal tissues were determined following the enzyme-linked immunosorbent assay method.

RESULTS

We found that AREG, IL-19, IL-21, IL-25, IL-33 and TSLP levels were significantly higher in the CRSwNP group compared to the control group (p < 0.000; p < 0.000; p < 0.000; p < 0.000; p < 0.003; p < 0.021, respectively).

CONCLUSIONS

Our findings indicated that AREG, IL-19, IL-21, IL-25, IL-33 and TSLP were significantly increased in tissue samples of CRSwNP patients and may be considered as molecular indicators and targets for therapeutic developments for patients with CRSwNP.

Sentinels at the wall: epithelial-derived cytokines serve as triggers of upper airway type 2 inflammation

Recent evidence has demonstrated an expanding role of respiratory epithelial cells in immune surveillance and modulation. Studies have been focusing on the earliest events that link epithelial injury to downstream inflammatory responses. Cytokines produced by and released from respiratory epithelial cells are among these early trigger signals. Epithelial-derived cytokines, namely thymic stromal lymphopoietin (TSLP), interleukin (IL)-25, and IL-33, have come to the forefront of recent investigations. Each of these 3 cytokines has been implicated in chronic rhinosinusitis (CRS), asthma, and atopy. Herein we review studies elucidating the roles of epithelial-derived cytokines in the pathobiology of upper airway disease, with particular emphasis on type 2 inflammatory conditions.

Immunological mechanisms underlying chronic rhinosinusitis with nasal polyps

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common and quality-of-life impacting disorder, with an underlying immunological mechanism similar to other conditions such as eosinophilic asthma or atopic eczema. Areas covered: This review article summarizes the most recent evidence on the main immunological mechanisms involved in the pathogenesis and the perpetuation of CRSwNP, with a particular focus on the key role of epithelium-derived inflammation as a consequence of the interaction with the airborne environment. Expert commentary: The increase in knowledge of the immunology of CRSwNP leads to the development of therapeutical strategies based upon the use of biologic agents that, according to a personalized and precision medicine approach, will provide each single patient with the most suitable immunological treatment.

Periostin as a novel biomarker for postoperative recurrence of chronic rhinosinitis with nasal polyps

We previously reported that chronic rhinosinusitis with nasal polyps (CRSwNP) was subdivided into four chronic rhinosinusitis (CRS) subtypes using the JESREC scoring system. We sought to identify the gene expression profile and biomarkers related with CRSwNP by RNA-sequence. RNA-sequencing was performed to identify differentially expressed genes between nasal polyps (NPs) and inferior turbinate mucosa from 6 patients with CRSwNP, and subsequently, quantitative real-time PCR was performed to verify the results. ELISA was performed to identify possible biomarkers for postoperative recurrence. In the RNA-sequencing results, periostin (POSTN) expression was the highest in NP. We focused on POSTN and investigated the protein level of POSTN by immunohistochemistry and ELISA. POSTN was diffusely expressed in moderate and severe eosinophilic CRS using immunohistochemistry, and its staining pattern was associated with the severity of the phenotype of the CRSwNP (P < 0.05). There was a significant difference between the POSTN high/low groups for postoperative recurrence when the cutoff point was set at 115.5 ng/ml (P = 0.0072). Our data suggests that the protein expression level of POSTN was associated with the severity of CRSwNP, and serum POSTN can be a novel biomarker for postoperative recurrence of CRSwNP.

Type 2 immunity: Expanding our view

The classical vision of type 2 immune reactions is that they are characterized by a distinct cellular and cytokine repertoire that is critical for host resistance against helminthic worm infections but, when dysregulated, may cause atopic reactions that result in conditions such as asthma, rhinitis, dermatitis, and anaphylaxis. In this traditional view, the type 2 response is categorized as an adaptive immune response with differentiated T helper cells taking center stage, driving eosinophil recruitment and immunoglobulin production via the secretion of a distinct repertoire of cytokines that include interleukin-4 (IL-4), IL-5, and IL-13. The recent discovery of a group of innate cells that has the capacity to secrete copious amounts of type 2 cytokines, potentially in the absence of adaptive immunity, has reignited interest in type 2 biology. The discovery that these innate lymphoid cells and type 2 cytokines are involved in diverse biological processes-including wound healing, control of metabolic homeostasis, and temperature-has considerably changed our view of type 2 responses and the cytokines, chemokines, and receptors that regulate these responses.

IL-17A+GM-CSF+ Neutrophils Are the Major Infiltrating Cells in Interstitial Lung Disease in an Autoimmune Arthritis Model

Objective

To gain a better understanding of the pathogenesis of autoimmune arthritis-associated interstitial lung disease (ILD), we sought to identify the characteristics of lung-infiltrating cells in SKG mice with ILD.

Methods

We injected curdlan in SKG mice at 8 weeks of age, and identified the presence of ILD by PET-MRI at 20 weeks post-injection and histological analysis at 22 weeks post-injection. Lung-infiltrating cells were examined by flow cytometry. Analysis of serum cytokines by the Luminex multiplex cytokine assay was performed at 14 and 22 weeks post-injection, and cytokine profiles before and after the development of ILD were compared. Opal multiplexed immunofluorescent staining of lung tissue was also performed.

Results

At 20 weeks post-injection, curdlan-treated SKG mice developed not only arthritis but also lung inflammation combined with fibrosis, which was identified by PET-MRI and histological analysis. The majority of inflammatory cells that accumulated in the lungs of curdlan-treated SKG mice were CD11b⁺Gr1⁺ neutrophils, which co-express IL-17A and GM-CSF, rather than TNF-α. Compared with 14 weeks post-injection, serum levels of GM-CSF, MCP1, IL-17A, IL-23, TSLP, and soluble IL-7Rα had increased at 22 weeks post-injection, whereas those of IFN-γ, IL-22, IL-6, and TNF-α remained unchanged. Furthermore, IL-23, CXCL5, IL-17A, and GM-CSF, but not TNF-α, were observed in immunofluorescent-stained lung tissue.

Conclusion

We found that IL-17A⁺GM-CSF⁺ neutrophils represented the major inflammatory cells in the lungs of curdlan-treated SKG mice. In addition, GM-CSF and IL-17A appear to play a more important role than TNF-α in ILD development.

Decreased expression of CCL17 in the disrupted nasal polyp epithelium and its regulation by IL-4 and IL-5

Background

In airway epithelium, thymus and activation-regulated chemokine (CCL17) and macrophage-derived chemokine (CCL22) are induced by defective epithelial barriers such as E-cadherin and attract the effector cells of Th2 immunity. However, the association between the epithelial barrier and CCL17 expression has not been studied in chronic rhinosinusitis with nasal polyp (CRSwNP). Thus, we aimed to evaluate the expression of CCL17 and its regulation by Th cytokines in nasal polyp (NP) epithelial cells.

Methods

The expression and distribution of CCL17, CCL22, E-cadherin and/or epidermal growth factor receptor (EGFR) were measured using real-time PCR, western blot, and immunohistochemistry and compared between normal ethmoid sinus epithelium and NP epithelium. In addition, the expression level of CCL17 was determined in cultured epithelial cells treated with IL-4, IL-5, IL-13, TNF-α, and IFN-γ.

Results

The expression of CCL17 was decreased in the NP epithelium compared to the epithelium of normal ethmoid sinus, whereas the expression of CCL22 was not decreased. E-cadherin was differentially distributed between the epithelium of normal ethmoid sinus and NP epithelium. EGFR was also decreased in NPs. Interestingly, the stimulation of cultured epithelial cells with Th2 cytokines, IL-4 and IL-5, resulted in an upregulation of CCL17 expression only in NP epithelial cells whereas the expression of CCL17 was increased in both normal epithelial cells and NP epithelial cells by Th1 cytokines.

Conclusion

Our results suggest that the decreased expression of CCL17 in defective NP epithelium may be closely connected to NP pathogenesis and can be differentially regulated by cytokines in the NP epithelium of patients with CRSwNP.

Sentinels of the Type 2 Immune Response

Type 2 immune responses have evolved to sense and respond to large, non-replicating infections or non-microbial noxious compounds in tissues. The development of these responses therefore depends upon highly coordinated and tightly regulated tissue-residing cellular sensors and responders. Multiple exposure to type 2 helper T cell (Th2)-inducing stimuli further enhances both the diversity and potency of the response. This review discusses advances in our understanding of the interacting cellular subsets that comprise both primary and secondary type 2 responses. Current knowledge regarding type 2 immune responses in the lung are initially presented and are then contrasted with what is known about the small intestine. The studies described portray an immune response that depends upon well-organized tissue structures, and suggest their modulation as a therapeutic strategy.

International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis

BACKGROUND

Critical examination of the quality and validity of available allergic rhinitis (AR) literature is necessary to improve understanding and to appropriately translate this knowledge to clinical care of the AR patient. To evaluate the existing AR literature, international multidisciplinary experts with an interest in AR have produced the International Consensus statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR).

METHODS

Using previously described methodology, specific topics were developed relating to AR. Each topic was assigned a literature review, evidence-based review (EBR), or evidence-based review with recommendations (EBRR) format as dictated by available evidence and purpose within the ICAR:AR document. Following iterative reviews of each topic, the ICAR:AR document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:AR document addresses over 100 individual topics related to AR, including diagnosis, pathophysiology, epidemiology, disease burden, risk factors for the development of AR, allergy testing modalities, treatment, and other conditions/comorbidities associated with AR.

CONCLUSION

This critical review of the AR literature has identified several strengths; providers can be confident that treatment decisions are supported by rigorous studies. However, there are also substantial gaps in the AR literature. These knowledge gaps should be viewed as opportunities for improvement, as often the things that we teach and the medicine that we practice are not based on the best quality evidence. This document aims to highlight the strengths and weaknesses of the AR literature to identify areas for future AR research and improved understanding.

Subtyping of polyposis nasi: phenotypes, endotypes and comorbidities

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous, multifactorial inflammatory disease of the nasal and paranasal mucosa. It has not been possible to date to develop an internationally standardized, uniform classification for this disorder. A phenotype classification according to CRS with (CRSwNP) and without polyposis (CRSsNP) is usually made. However, a large number of studies have shown that there are also different endotypes of CRS within these phenotypes, with different pathophysiologies of chronic inflammation of the nasal mucosa. This review describes the central immunological processes in nasal polyps, as well as the impact of related diseases on the inflammatory profile of nasal polyps.

MATERIALS AND METHODS

The current knowledge on the immunological and molecular processes of CRS, in particular CRSwNP and its classification into specific endotypes, was put together by means of a structured literature search in Medline, PubMed, the national and international guideline registers, and the Cochrane Library.

RESULTS

Based on the current literature, the different immunological processes in CRS and nasal polyps were elaborated and a graphical representation in the form of an immunological network developed. In addition, different inflammatory profiles can be found in CRSwNP depending on related diseases, such as bronchial asthma, cystic fibrosis (CF), or NASID-Exacerbated Respiratory Disease (N‑ERD).

CONCLUSION

The identification of different endotypes of CRSwNP may help to improve diagnostics and develop novel individual treatment approaches in CRSwNP.

Treatment of allergic rhinitis with CpG oligodeoxynucleotides alleviates the lower airway outcomes of combined allergic rhinitis and asthma syndrome via a mechanism that possibly involves in TSLP

PURPOSE

Thymic stromal lymphopoietin (TSLP) is a critical regulator of immune responses associated with Th2 cytokine-mediated inflammation. Intranasal administration of oligodeoxynucleotides with CpG motifs (CpG-ODNs) might improve lower airway outcomes of combined allergic rhinitis and asthma syndrome (CARAS), but the inherent mechanisms of CpG-ODNs are not well defined. This study investigated whether CpG-ODNs treated to upper airway could reduce lower airway TSLP expression as well as whether this reduction could contribute to the alleviation of lower allergic inflammation and airway hyper-reactivity (AHR) in CARAS mice.

MATERIALS AND METHODS

Ovalbumin (OVA)-sensitized BALB/c mice were intranasal OVA exposure three times a week for 3 weeks. CpG-ODNs or an anti-TSLP mAb was administered to a subset of these mice 1 hour after intranasal OVA challenge, followed by 5 days of OVA aerosol challenge. The resulting immunological variables, nasal symptoms, and nasal mucosa and lung tissues pathology were evaluated. TSLP production in the lung tissues and bronchoalveolar lavage fluid (BALF) were determined by RT-PCR, western blotting or enzyme-linked immunosorbent assay.

RESULTS

The CARAS mice exhibited overexpression of TSLP in the lung tissues and BALF, and also demonstrated significant increases in BALF and splenocyte Th2-associated cytokine production, serum OVA-specific IgE, nose and lung pathologies, and AHR. Intranasal administration of CpG-ODNs restored TSLP in the lower airway, and it significantly reduced the following parameters: Th2-type cytokine production levels; the percentage of eosinophils in the BALF; IL-4 and IL-5 concentrations in the supernatants of cultured splenic lymphocytes; serum OVA-specific IgE; peribronchial inflammation score in the lungs; and nose pathology and nasal symptoms. Similar results were obtained when the CARAS mice were treated with an anti-TSLP mAb to block intranasal TSLP activity.

CONCLUSIONS

Treatment with intranasal CpG-ODNs improves lower airway immunological variable outcomes in the CARAS model via a mechanism that possibly involves in suppressing pulmonary TSLP-triggered allergic inflammation.

Cytokine and Lipid Mediator Regulation of Group 2 Innate Lymphoid Cells (ILC2s) in Human Allergic Airway Disease

The recent discovery of group 2 innate lymphoid cells (ILC2s) has caused a paradigm shift in the understanding of allergic airway disease pathogenesis. Prior to the discovery of ILC2s, Th2 cells were largely thought to be the primary source of type 2 cytokines; however, activated ILC2s have since been shown to contribute significantly, and in some cases, dominantly to type 2 cytokine production. Since the discovery of ILC2s in 2010, many mediators have been shown to regulate their effector functions. Initial studies identified the epithelial derived cytokines IL-25, IL-33, and TSLP as activators of ILC2s, and recent studies have identified many additional cytokine and lipid mediators that are involved in ILC2 regulation. ILC2s and their mediators represent novel therapeutic targets for allergic airway diseases and intensive investigation is underway to better understand ILC2 biology and upstream and downstream pathways that lead to ILC2-driven airway pathology. In this review, we will focus on the cytokine and lipid mediators that regulate ILC2s in human allergic airway disease, as well as highlight newly discovered mediators of mouse ILC2s that may eventually translate to humans.

Upregulation of interleukin-33 and thymic stromal lymphopoietin levels in the lungs of idiopathic pulmonary fibrosis

BACKGROUND

Innate T helper type 2 (Th2) immune responses mediated by interleukin (IL)-33, thymic stromal lymphopoietin (TSLP), and IL-25 have been shown to play an important role in pulmonary fibrosis of animal models; however, their clinical implications remain poorly understood.

METHODS

TSLP, IL-25, and IL-33 concentrations were measured in bronchoalveolar lavage fluids obtained from normal controls (NCs; n = 40) and from patients with idiopathic pulmonary fibrosis (IPF; n = 100), non-specific interstitial pneumonia (NSIP; n = 22), hypersensitivity pneumonitis (HP; n = 20), and sarcoidosis (n = 19).

RESULTS

The TSLP and IL-33 levels were significantly higher in patients with IPF relative to the NCs (p = 0.01 and p = 0.0001, respectively), NSIP (p = 4.95E - 7 and p = 0.0002, respectively), HP (p = 0.00003 and p = 0.000005, respectively), and sarcoidosis groups (p = 0.003 and p = 0.0001, respectively). However, the IL-25 levels were not significantly different between NC and IPF group (p = 0.432). Receiver operating characteristic curves of the TSLP and IL-33 levels revealed clear differences between the IPF and NC groups (AUC = 0.655 and 0.706, respectively), as well as between the IPF and the other lung disease groups (AUC = 0.786 and 0.781, respectively). Cut-off values of 3.52 pg/μg TSLP and 3.77 pg/μg IL-33 were shown to differentiate between the IPF and NC groups with 99.2 and 94.3% accuracy. Cut-off values of 4.66 pg/μg TSLP and 2.52 pg/μg IL-33 possessed 99.4 and 93.2% accuracy for differentiating among the IPF and other interstitial lung disease groups.

CONCLUSIONS

Innate immune responses may be associated with the development of IPF. Furthermore, the IL-33 and TSLP levels in BAL fluids may be useful for differentiating IPF from other chronic interstitial lung diseases.

Release of Type 2 Cytokines by Epithelial Cells of Nasal Polyps

Background. T2 inflammation of chronic rhinosinusitis with nasal polyps (CRSwNP) may be influenced by epithelial cytokines release (TSLP, IL-25, and IL-33). We investigated the release of TSLP, IL-25, and IL-33 by epithelial CRSwNP cells compared to epithelial sinus mucosa cells of patients with chronic rhinosinusitis without nasal polyps (CRSsNP). Methods. IL-25, IL-33, and TSLP were measured by ELISA in the supernatant of cell cultures derived by CRSwNP (9 patients, 6 atopic) and CRSsNP (7 patients, 2 atopic) in baseline condition and following stimulation with Dermatophagoides pteronyssinus (DP), Aspergillus fumigatus (AF), and poly(I:C). Results. CRSwNP epithelial cells released increased levels of IL-25 (from 0.12 ± 0.06 pg/ml to 0.27 ± 0.1 pg/ml, p < 0.01) and TSLP (from 0.77 ± 0.5 pg/ml to 2.53 ± 1.17 pg/ml, p < 0.001) following poly(I:C) stimulation, while CRSsNP epithelial cells released increased levels of IL-25 and IL-33 following AF and DP stimulation, respectively (IL-25: from 0.18 ± 0.07 pg/ml to 0.51 ± 0.1 pg/ml, p < 0.001; IL-33: from 2.57 ± 1.3 pg/ml to 5.7 ± 3.1 pg/ml, p < 0.001). Conclusions. CRSwNP epithelial cells release TSLP and IL-25 when stimulated by poly(I:C) but not by DP or AF, suggesting that viral infection may contribute to maintain and amplify the T2 immune response seen in CRSwNP.

New insights into basophil heterogeneity

Basophils have become increasingly recognized as important innate immune cells that mediate antihelminth immunity and barrier inflammation. Recent discoveries have uncovered previously unrecognized heterogeneity in basophil populations. However, how diversity in basophil regulation and function impacts human disease remains poorly defined. The goal of the present review is to highlight how new insights into basophil heterogeneity can help us to better understand disease pathogenesis and inform the development of new therapeutics.

Insights into Group 2 Innate Lymphoid Cells in Human Airway Disease

Recent discoveries have led to the identification of a novel group of immune cells, the innate lymphoid cells (ILCs). The members of this group are divided into three subpopulations: ILC1s, ILC2s, and ILC3s. ILC2s produce Th2 cytokines, IL-4, IL-5, and IL-13, upon activation by epithelial cell-derived cytokines, lipid mediators (cysteinyl leukotrienes and prostaglandin D2), and TNF family member TL1A and promote structural and immune cell responses in the airways after antigen exposure. In addition, ILC2 function is also influenced by inducible T cell costimulator (ICOS)/ICOS-ligand (ICOS-L) interactions via direct contact between immune cells. The most common airway antigens are allergens and viruses which are highly linked to the induction of airway diseases with underlying type 2 inflammation including asthma and allergic rhinitis. Based on recent findings linking ILC2s and airway Th2 responses, there is intensive investigation into the role of ILC2s in human disease with the hope of a better understanding of the pathophysiology and the discovery of novel potential therapeutic targets. This review summarizes the recent advances made in elucidating ILC2 involvement in human Th2 airway disease.

A Player and Coordinator: The Versatile Roles of Eosinophils in the Immune System

Eosinophils have traditionally been associated with allergic diseases and parasite infection. Research advances in the recent decades have brought evolutionary changes in our understanding of eosinophil biology and its roles in immunity. It is currently recognized that eosinophils play multiple roles in both innate and adaptive immunity. As effector cells in innate immunity, eosinophils exert a pro-inflammatory and destructive role in the Th2 immune response associated with allergic inflammation or parasite infection. Eosinophils can also be recruited by danger signals released by pathogen infections or tissue injury, inducing host defense against parasitic, fungal, bacterial or viral infection or promoting tissue repair and remodeling. Eosinophils also serve as nonprofessional antigen-presenting cells in response to allergen challenge or helminth infection, and, meanwhile, are known to function as a versatile coordinator that actively regulates or interacts with various immune cells including T lymphocytes and dendritic cells. More roles of eosinophils implicated in immunity have been proposed including in immune homeostasis, allograft rejection, and anti-tumor immunity. Eosinophil interactions with structural cells are also implicated in the mechanisms in allergic inflammation and in Helicobacter pylori gastritis. These multifaceted roles of eosinophils as both players and coordinators in immune system are discussed in this review.

Thymic stromal lymphopoietin controls prostaglandin D2 generation in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Prostaglandin (PG) D2 is the dominant COX product of mast cells and is an effector of aspirin-induced respiratory reactions in patients with aspirin-exacerbated respiratory disease (AERD).

OBJECTIVE

We evaluated the role of the innate cytokine thymic stromal lymphopoietin (TSLP) acting on mast cells to generate PGD2 and facilitate tissue eosinophilia and nasal polyposis in patients with AERD.

METHODS

Urinary eicosanoid levels were measured in aspirin-tolerant control subjects and patients with AERD. Nasal polyp specimens from patients with AERD and chronic rhinosinusitis were analyzed by using quantitative PCR, Western blotting, and immunohistochemistry. Human cord blood-and peripheral blood-derived mast cells were stimulated with TSLP in vitro to assess PGD2 generation.

RESULTS

Urinary levels of a stable PGD2 metabolite (uPGD-M) were 2-fold higher in patients with AERD relative to those in control subjects and increased further during aspirin-induced reactions. Peak uPGD-M levels during aspirin reactions correlated with reductions in blood eosinophil counts and lung function and increases in nasal congestion. Mast cells sorted from nasal polyps expressed PGD2 synthase (hematopoietic PGD2 synthase) mRNA at higher levels than did eosinophils from the same tissue. Whole nasal polyp TSLP mRNA expression correlated strongly with mRNA encoding hematopoietic PGD2 synthase (r = .75), the mast cell-specific marker carboxypeptidase A3 (r = .74), and uPGD-M (r = 0.74). Levels of the cleaved active form of TSLP were increased in nasal polyps from patients with AERD relative to those in aspirin-tolerant control subjects. Recombinant TSLP induced PGD2 generation by cultured human mast cells.

CONCLUSIONS

Our study demonstrates that mast cell-derived PGD2 is a major effector of type 2 immune responses driven by TSLP and suggests that dysregulation of this innate system contributes significantly to the pathophysiology of AERD.

The paradigm of cytokine networks in allergic airway inflammation

PURPOSE OF REVIEW

Cytokines are immunomodulatory proteins important in cell signaling. Complex interactions of innate and adaptive immune cells, as well as structural cells and their cytokines, play crucial roles in regulating allergic airway inflammation. Here, we summarize current knowledge about the potential roles of known and newly identified helper T cells and epithelial cell-derived cytokines [interleukin (IL)-9, IL-17, IL-22, IL-25, and IL-33] in allergic rhinitis and asthma.

RECENT FINDINGS

Although T-helper (Th)2 cells were considered to be the main orchestrators of allergic airway inflammation, recent studies have revealed the potential interaction of other helper T cells and their cytokines in this process. Th17 cells may have a role in allergic rhinitis and asthma, and chronic rhinosinusitis with nasal polyps. An IL-9-producing subset called Th9 cells, Th22 cells which primarily secrete IL-22, IL-13, tumor necrosis factor-α, Th25 cells via producing IL-25 and epithelial cell-derived thymic stromal lymphopoietin, IL-33, IL-31, and IL-25 are believed to be important for the initiation of allergic reactions and inducing airway inflammation.

SUMMARY

A new paradigm of an interplay of cytokines is important in allergic rhinitis and asthma in orchestrating the allergic inflammatory response. Potential therapeutic applications emerging from the roles of these cytokines are promising, but need further research.

Interaction of thymic stromal lymphopoietin, IL-33, and their receptors in epithelial cells in eosinophilic chronic rhinosinusitis with nasal polyps

BACKGROUND

Thymic stromal lymphopoietin (TSLP), IL-25, and IL-33 system contribute to the initiation and development of Th2 responses. This study aimed to explore the involvement of TSLP, IL-25, IL-33, and their receptors in type 2 T-helper (Th) responses in chronic rhinosinusitis with nasal polyps (CRSwNPs) and their cross-regulation in human nasal epithelial cells (HNECs).

METHODS

Immunohistochemistry, quantitative RT-PCR, ELISA, Bio-Plex assay, and flow cytometry were used to detect the expression of TSLP/common γ-like TSLP receptor (TSLPR)/IL-7 receptor α (IL-7Rα), IL-25/IL-17B receptor (IL-17RB), and IL-33/membrane-bound ST2 (ST2L)/soluble ST2 (sST2) in sinonasal mucosa and HNECs. HNECs cultured at an air-liquid interface were used to explore the expression in regulation of these cytokine systems.

RESULTS

Compared with controls and noneosinophilic CRSwNP, the expression of TSLP/TSLPR/IL-7Rα and ST2L/sST2 was significantly increased in eosinophilic CRSwNP, predominantly in epithelial cells. In contrast, the expression of IL-33 and IL-25/IL-17RB was enhanced in epithelial cells in both eosinophilic and noneosinophilic CRSwNP compared to controls. The expression of TSLP, TSLPR, and ST2L was positively correlated with symptom and computer tomography scan scores in eosinophilic CRSwNP and with Th2 cytokine expression in sinonasal mucosa. The expression of ST2L was correlated with TSLP and its receptor expression. TSLP could induce ST2L expression that promoted IL-33-induced TSLP expression in HNECs. In addition, TSLP/TSLPR/IL-7Rα and ST2L could be induced by Th2 cytokines, while IL-25/IL-17RB and IL-33 could be upregulated by Th1/Th17 cytokines, in HNECs.

CONCLUSIONS

The positive feedback loop between TSLP, IL-33 and their receptors, and Th2 cytokines may facilitate Th2-skewed inflammation in eosinophilic CRSwNP.

Thymic stromal lymphopoietin (TSLP) secretion from human nasal epithelium is a function of TSLP genotype

Recent candidate gene and genome-wide association studies have identified "protective" associations between the single-nucleotide polymorphism (SNP) rs1837253 in the TSLP gene and risk for allergy, asthma, and airway hyperresponsiveness. The absence of linkage disequilibrium of rs1837253 with other SNPs in the region suggests it is likely a causal polymorphism for these associations, having functional consequences. We hypothesized that rs1837253 genotype would influence TSLP secretion from mucosal surfaces. We therefore evaluated the secretion of TSLP protein from primary nasal epithelial cells (NECs) of atopic and nonatopic individuals and its association with rs1837253 genotype. We found that although atopic sensitization does not affect the secretion of TSLP from NECs, there was decreased TSLP secretion in NECs obtained from heterozygous (CT; 1.8-fold) and homozygous minor allele (TT; 2.5-fold) individuals, as compared with NECs from homozygous major allele individuals (CC; P<0.05), after double-stranded RNA (dsRNA) stimulation (50 μg ml(-1)). Our novel results show that rs1837253 polymorphism may be directly involved in the regulation of TSLP secretion. This may help explain the protective association of this genetic variant with asthma and related traits. Identifying functional consequences of SNPs in genes with previously reported clinical associations is critical in understanding and targeting allergic inflammation.

Alternaria Induces Production of Thymic Stromal Lymphopoietin in Nasal Fibroblasts Through Toll-like Receptor 2

Purpose

Chronic rhinosinusitis with nasal polyps is a chronic inflammatory disease with markedly increased eosinophils, Th2-type lymphocytes, fibroblasts, and goblet cells. Fungi are commonly associated with airway inflammatory diseases, and thymic stromal lymphopoietin (TSLP) is important in the development of Th2 inflammatory responses. The aim of this study was to investigate the interaction between airborne fungi and nasal fibroblasts in TSLP mRNA and protein expression.

Methods

Inferior turbinate and nasal polyp fibroblasts were stimulated with Alternaria and Aspergillus, respectively, for 48 hours, and TSLP mRNA and protein expressions were measured. The reverse transcriptase polymerase chain reaction was performed for the Toll-like receptor (TLR) mRNA expression of the nasal fibroblasts. To determine the role of TLR in the induction of TSLP, the fibroblasts were transfected with siRNA against TLR2 and TLR5.

Results

Alternaria induced TSLP mRNA and protein expression in both inferior turbinate and nasal polyp fibroblasts. The nasal polyp fibroblasts responded more strongly to the fungi. TLR2 and TLR5 mRNA expressions were significantly increased with fungal stimulation and TSLP production was significantly inhibited by siRNA against TLR2.

Conclusions

The results of this study show that TSLP expression could be induced in nasal fibroblasts by exposure to Alternaria and that TLR2 may be involved in the process. The promotion of TSLP production in nasal fibroblasts by airborne fungi may facilitate the development or exacerbation of Th2-type nasal inflammation, especially in CRS with nasal polyps.

Proallergic cytokines and group 2 innate lymphoid cells in allergic nasal diseases

Recent advances in our understanding of proallergic cytokines and group 2 innate lymphoid cells (ILC2s) indicate their critical roles in type 2 immunity-mediated disorders. Proallergic cytokines, interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin, are released from epithelial cells in inflamed tissues and drive type 2 inflammation by acting on innate and acquired immune systems. ILC2s are an innate immune population that responds to proallergic cytokines by producing type 2 cytokines. In line with allergic disorders in the lung, skin, and intestine, emerging evidence suggests the involvement of proallergic cytokines and ILC2s in allergic nasal diseases such as chronic rhinosinusitis with polyps (CRSwNP), allergic fungal rhinosinusitis, and allergic rhinitis (AR). In CRSwNP patients, both proallergic cytokine levels and ILC2s frequency are increased in the nasal mucosa. Increased proallergic cytokine levels correlate with poorer disease outcomes in CRSwNP. Levels of nasal proallergic cytokines are also elevated in AR patients. In addition, animal studies demonstrate that cytokines are essential for the development of AR. It is becoming clear that the proallergic cytokine/ILC2s axis participates in allergic diseases by multiple mechanisms dependent upon the inflammatory context. Thus, a thorough understanding of these cytokines and ILC2s including their tissue- and disease-specific roles is essential for targeting the pathways to achieve therapeutic applications.

Local immunoglobulin e in the nasal mucosa: clinical implications

Immunoglobulin E (IgE) can be highly elevated in the airway mucosa independently of IgE serum levels and atopic status. Mostly, systemic markers are assessed to investigate inflammation in airway disease for research or clinical practice. A more accurate but more cumbersome approach to determine inflammation at the target organ would be to evaluate markers locally. We review evidence for local production of IgE in allergic rhinitis (AR) and chronic rhinosinusitis with nasal polyps (CRSwNP). Diagnostic and therapeutic consequences in clinical practice are discussed. We describe that the airway mucosa has the intrinsic capability to produce IgE. Moreover, not only do IgE-positive B cells reside within the mucosa, but all tools are present locally for affinity maturation by somatic hypermutation (SHM), clonal expansion, and class switch recombination to IgE. Recognizing local IgE in the absence of systemic IgE has diagnostic and therapeutic consequences. Therefore, we emphasize the importance of local IgE in patients with a history of AR or CRSwNP.