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Purpose of Review: Epithelial barrier defects are being appreciated in various inflammatory disorders; however, causal underlying mechanisms are lacking. In this review, we describe the disruption of the airway epithelium with regard to upper and lower airway diseases, the role of epigenetic alterations underlying this process, and potential novel ways of interfering with dysfunctional epithelial barriers as a novel therapeutic approach., Recent Findings: A defective epithelial barrier, impaired innate defence mechanisms or hampered epithelial cell renewal are found in upper and lower airway diseases. Barrier dysfunction might facilitate the entrance of foreign substances, initiating and facilitating the onset of disease. Latest data provided novel insights for possible involvement of epigenetic alterations induced by inflammation or other unknown mechanisms as a potential mechanism responsible for epithelial defects. Additionally, these mechanisms might precede disease development, and represent a novel therapeutic approach for restoring epithelial defects., Summary: A better understanding of the role of epigenetics in driving and maintaining epithelial defects in various inflammatory diseases, using state-of-the-art biology tools will be crucial in designing novel therapies to protect or reconstitute a defective airway epithelial barrier.

It is generally believed that the microbiome plays a role in the pathophysiology of chronic rhinosinusitis (CRS), though its exact contribution to disease development and severity remains unclear. Here, samples were collected from the anterior nares, nasopharynx, and maxillary and ethmoid sinuses of 190 CRS patients and from the anterior nares and nasopharynx of 100 controls. Microbial communities were analyzed by Illumina sequencing of the V4 region of 16S rRNA. The phenotype and patient characteristics were documented, and several serum inflammatory markers were measured. Our data indicate a rather strong continuity for the microbiome in the different upper respiratory tract (URT) niches in CRS patients, with the microbiome in the anterior nares being most similar to the sinus microbiome. Bacterial diversity was reduced in CRS patients without nasal polyps compared to that in the controls but not in CRS patients with nasal polyps. Statistically significant differences in the presence/absence or relative abundance of several taxa were found between the CRS patients and the healthy controls. Of these, Dolosigranulum pigrum was clearly more associated with URT samples from healthy subjects, while the Corynebacterium tuberculostearicum , Haemophilus influenzae/H. aegyptius , and Staphylococcus taxa were found to be potential pathobionts in CRS patients. However, CRS versus health as a predictor explained only 1 to 2% of the variance in the microbiome profiles in an adonis model. A history of functional endoscopic sinus surgery, age, and sex also showed a minor association. This study thus indicates that functional studies on the potential beneficial versus pathogenic activity of the different indicator taxa found here are needed to further understand the pathology of CRS and its different phenotypes. (This study has been registered at ClinicalTrials.gov under identifier NCT02933983.) IMPORTANCE There is a clear need to better understand the pathology and specific microbiome features in chronic rhinosinusitis patients, but little is known about the bacterial topography and continuity between the different niches of the upper respiratory tract. Our work showed that the anterior nares could be an important reservoir for potential sinus pathobionts. This has implications for the diagnosis, prevention, and treatment of CRS. In addition, we found a potential pathogenic role for the Corynebacterium tuberculostearicum , Haemophilus influenzae/H. aegyptius , and Staphylococcus taxa and a potential beneficial role for Dolosigranulum Finally, a decreased microbiome diversity was observed in patients with chronic rhinosinusitis without nasal polyps compared to that in healthy controls but not in chronic rhinosinusitis patients with nasal polyps. This suggests a potential role for the microbiome in disease development or progression of mainly this phenotype., (Copyright © 2019 De Boeck et al.)

Background: A defective epithelial barrier is found in patients with allergic rhinitis (AR) and asthma; however, the underlying mechanisms remain poorly understood. Histone deacetylase (HDAC) activity has been identified as a crucial driver of allergic inflammation and tight junction dysfunction., Objective: We investigated whether HDAC activity has been altered in patients with AR and in a mouse model of house dust mite (HDM)-induced allergic asthma and whether it contributed to epithelial barrier dysfunction., Methods: Primary nasal epithelial cells of control subjects and patients with AR were cultured at the air-liquid interface to study transepithelial electrical resistance and paracellular flux of fluorescein isothiocyanate-dextran (4 kDa) together with mRNA expression and immunofluorescence staining of tight junctions. Air-liquid interface cultures were stimulated with different concentrations of JNJ-26481585, a broad-spectrum HDAC inhibitor. In vivo the effect of JNJ-26481585 on mucosal permeability and tight junction function was evaluated in a mouse model of HDM-induced allergic airway inflammation., Results: General HDAC activity was greater in nasal epithelial cells of patients with AR and correlated inversely with epithelial integrity. Treatment of nasal epithelial cells with JNJ-26481585 restored epithelial integrity by promoting tight junction expression and protein reorganization. HDM-sensitized mice were treated with JNJ-26481585 to demonstrate the in vivo role of HDACs. Treated mice did not have allergic airway inflammation and had no bronchial hyperreactivity. Moreover, JNJ-26481585 treatment restored nasal mucosal function by promoting tight junction expression., Conclusion: Our findings identify increased HDAC activity as a potential tissue-injury mechanism responsible for dysregulated epithelial cell repair, leading to defective epithelial barriers in AR. Blocking HDAC activity is a promising novel target for therapeutic intervention in patients with airway diseases., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Epithelial cell lines are often used to evaluate the effect of exogenous/endogenous stimuli on epithelial barrier function and innate immune responses in allergic airway diseases, without clear view on differences between epithelial cell lines and primary nasal epithelial cell responses. In this observational study, we compared the response of Calu-3 and primary nasal epithelial cells to two relevant exogenous stimuli: i.e. Staphylococcus aureus enterotoxin B (SEB) and house dust mite (HDM). Stimulation of Calu-3 cells with SEB decreased epithelial integrity in a dose dependent manner, which was associated with a significant increase in IL-6 and IL-8 production. In contrast, no alteration in barrier integrity or IL-6 and IL-8 production was seen when primary nasal epithelial cells were stimulated with SEB. HDM extract altered the integrity of primary nasal epithelial cells, but not of Calu-3 epithelial cells. Increased IL-8 production was seen after stimulation with HDM in primary nasal epithelial cells and not in Calu-3 epithelial cells. In conclusion, immune and barrier function differ between different epithelial cell types studied. As a consequence, care must be taken when interpreting data using different epithelial cell types.

Background: A visual analogue scale (VAS) is a psychometric instrument widely used in the Rhinology field to subjectively quantify patient's symptoms severity. In allergic rhinitis, VAS has been found to correlate well with the allergic rhinitis and its impact on asthma severity classification, as well as with rhinoconjunctivitis quality of life questionnaire. In chronic rhinosinusitis (CRS), total VAS score are often used to classify disease burden into mild, moderate, and severe, with few studies correlating VAS scores with more complex and validated instruments assessing disease-specific burden like Sino-Nasal Outcome Test (SNOT)-22., Methods: We correlated VAS scores for total and individual sino-nasal symptom with SNOT-22 scores in a randomly selected group of 180 CRS patients. Pearson's rho was selected as a correlation coefficient for analysis., Results: VAS scores for total nasal symptom score and individual symptoms correlated significantly with SNOT-22, irrespective of VAS based subclasses for sino-nasal, ocular, and bronchial symptoms., Conclusions: VAS for total sino-nasal symptom severity might be used for assessing disease severity, monitoring the course of the disease, and can be used for treatment decisions and disease burden.

Background: A high burden of lower airway symptoms is found in elite swimmers. To what extent elite swimmers suffer from upper airway symptoms and how these associate with nasal inflammation is less clear. We here aimed to evaluate upper airway symptoms and nasal inflammation in elite athletes., Methodology: Elite swimmers, indoor athletes and age-matched controls were recruited. Upper airway symptoms were assessed by sino-nasal outcome test (SNOT)-22 questionnaire. Visual Analogue score (VAS) for nasal symptoms as well as neurogenic and inflammatory mediators in nasal fluid were assessed at baseline, immediately and 24-hours after sport-specific training. The effect of hypochlorite on nasal epithelial cells was evaluated in vitro., Results: Baseline SNOT-22 and VAS for nasal itch and impaired smell were significantly higher in swimmers compared to controls. Nasal substance P and uric acid levels were increased in elite swimmers 24-hours after swimming compared to baseline. In elite swimmers, uric acid levels 24-hours post-exercise correlated with baseline SNOT-22. As increased symptoms and inflammation were found in swimmers but not in indoor athletes, we hypothesized that hypochlorite exposure might be the underlying mechanism. In vitro, the highest dose of hypochlorite decreased nasal epithelial cell integrity and induced release of uric acid., Conclusion: Upper airway symptoms are frequently reported in elite swimmers. Intensive swimming resulted in a delayed increase of epithelial injury and neurogenic inflammation.

Physical exercise requires proper function of the upper and lower airways in order to meet exertional ventilatory requirements. Athletes performing frequent intensive exercise experience more sino-nasal symptoms and demonstrate objective decreases in sino-nasal function when compared with the general population. Sino-nasal dysfunction is known to interfere with sport performance. Nasal epithelial injury, neutrophilic influx, and decreased mucociliary clearance have been associated with intensive training. In this review, the authors provide a comprehensive overview of the prevalence of sino-nasal disease in athletes, the possible underlying pathophysiologic mechanisms, and a summary of diagnostic and treatment options., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Allergic rhinitis (AR) is characterized by mucosal inflammation, driven by activated immune cells. Mast cells and T H 2 cells might decrease epithelial barrier integrity in AR, maintaining a leaky epithelial barrier., Objective: We sought to investigate the role of histamine and T H 2 cells in driving epithelial barrier dysfunction in AR., Methods: Air-liquid interface cultures of primary nasal epithelial cells were used to measure transepithelial electrical resistance, paracellular flux of fluorescein isothiocyanate-dextran 4 kDa, and mRNA expression of tight junctions. Nasal secretions were collected from healthy control subjects, AR patients, and idiopathic rhinitis patients and were tested in vitro. In addition, the effect of activated T H 1 and T H 2 cells, mast cells, and neurons was tested in vitro. The effect of IL-4, IL-13, IFN-γ, and TNF-α on mucosal permeability was tested in vivo., Results: Histamine as well as nasal secretions of AR but not idiopathic rhinitis patients rapidly decreased epithelial barrier integrity in vitro. Pretreatment with histamine receptor-1 antagonist, azelastine prevented the early effect of nasal secretions of AR patients on epithelial integrity. Supernatant of activated T H 1 and T H 2 cells impaired epithelial integrity, while treatment with anti-TNF-α or anti-IL-4Rα monoclonal antibodies restored the T H 1- and T H 2-induced epithelial barrier dysfunction, respectively. IL-4, IFN-γ, and TNF-α enhanced mucosal permeability in mice. Antagonizing IL-4 prevented mucosal barrier disruption and tight junction downregulation in a mouse model of house dust mite allergic airway inflammation., Conclusions: Our data indicate a key role for allergic inflammatory mediators in modulating nasal epithelial barrier integrity in the pathophysiology in AR., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Lipopolysaccharides (LPS), the major components of the wall of gram-negative bacteria, trigger powerful defensive responses in the airways via mechanisms thought to rely solely on the Toll-like receptor 4 (TLR4) immune pathway. Here we show that airway epithelial cells display an increase in intracellular Ca 2+ concentration within seconds of LPS application. This response occurs in a TLR4-independent manner, via activation of the transient receptor potential vanilloid 4 cation channel (TRPV4). We found that TRPV4 mediates immediate LPS-induced increases in ciliary beat frequency and the production of bactericidal nitric oxide. Upon LPS challenge TRPV4-deficient mice display exacerbated ventilatory changes and recruitment of polymorphonuclear leukocytes into the airways. We conclude that LPS-induced activation of TRPV4 triggers signaling mechanisms that operate faster and independently from the canonical TLR4 immune pathway, leading to immediate protective responses such as direct antimicrobial action, increase in airway clearance, and the regulation of the inflammatory innate immune reaction.

Background: The therapeutic action of capsaicin treatment in patients with idiopathic rhinitis (IR) is based on ablation of the transient receptor potential cation channel subfamily V, receptor 1 (TRPV1)-substance P nociceptive signaling pathway. However, the functional consequences of capsaicin treatment on nasal nerve activation and the association between the reduction in nasal hyperreactivity (NHR) and response to capsaicin treatment remain unknown., Objective: We sought to study the effects of capsaicin nasal spray on the afferent innervation of the nasal mucosa by monitoring trigeminal nerve activity in patients with IR and healthy control (HC) subjects., Methods: A double-blind, placebo-controlled randomized trial with capsaicin nasal spray was performed involving 33 patients with IR and 12 HC subjects. Before and at 4, 12, and 26 weeks after treatment, nasal mucosal potentials (NMPs) were measured while exposing the nasal mucosa of patients with IR and HC subjects to aerosols with increasing doses of the chemical irritants allyl isothiocyanate (AITC; also known as mustard oil) or capsaicin. The threshold for each compound was determined for each subject. The results of the NMP measurements were evaluated in parallel with the therapeutic response, visual analog scale scores for nasal symptoms, self-reported NHR, and mRNA expression of PGP9.5; TRPV1; transient receptor potential cation channel subfamily A, receptor 1 (TRPA1); TRPV4; transient receptor potential cation channel subfamily M, member 8 (TRPM8); and nerve growth factor (NGF) in nasal biopsy specimens., Results: AITC turned out to be the best stimulus because the coughing induced by capsaicin interfered with measurements. At baseline, the threshold for evoking changes in NMPs based on AITC was significantly lower for patients with IR compared with HC subjects (P = .0423). Capsaicin treatment of IR patients increased the threshold for the response to AITC at 4 and 12 weeks compared with placebo (P = .0406 and P = .0325, respectively), which returned to baseline by week 26 (P = .0611). This increase correlated with changes in visual analog scale major symptom (P = .0004) and total symptom (P = .0018) scores. IR patients with self-reported NHR at baseline showed a trend to being better responders to capsaicin treatment compared with patients with IR but without NHR (P = .10)., Conclusion: The lower threshold for AITC based on NMPs in patients with IR compared with HC subjects and the increased threshold for AITC after capsaicin treatment in patients with IR demonstrate the crucial role of TRPA1 and TRPV1 in IR pathophysiology. The strong correlation between the increase in AITC threshold in patients with IR and symptom reduction after capsaicin treatment demonstrates the clinical relevance of these findings., (Copyright © 2017. Published by Elsevier Inc.)

Rhinitis and rhinosinusitis are the two major clinical entities of chronic upper airway disease. Chronic rhinosinusitis (CRS) and allergic rhinitis (AR) affect respectively up to 10 and 30% of the total population, hence being associated with an important socio-economic burden. Different phenotypes of rhinitis and CRS have been described based on symptom severity and duration, atopy status, level of control, comorbidities and presence or absence of nasal polyps in CRS. The underlying pathophysiological mechanisms are diverse, with different, and sometimes overlapping, endotypes being recognized. Type 2 inflammation is well characterized in both AR and CRS with nasal polyps (CRSwNP), whereas type 1 inflammation is found in infectious rhinitis and CRS without nasal polyps (CRSsNP). The neurogenic endotype has been demonstrated in some forms of non-allergic rhinitis. Epithelial barrier dysfunction is shown in AR and CRSwNP. Emerging therapies are targeting one specific pathophysiological pathway or endotype. This endotype-driven treatment approach requires careful selection of the patient population who might benefit from a specific treatment. Personalized medicine is addressing the issue of providing targeted treatment for the right patient and should be seen as one aspect of the promising trend towards precision medicine. This review provides a comprehensive overview of the current state of endotypes, biomarkers and targeted treatments in chronic inflammatory conditions of the nose and paranasal sinuses.

Objectives: This study sought to investigate the influence of scar extent and location on the motion pattern of the left ventricle (LV) and its interaction with LV conduction delays., Background: Different echocardiographic parameters have been proposed to identify responders to cardiac resynchronization therapy based on the detection of LV mechanical dyssynchrony. However, the impact of infarct scar on the diagnostic performance of these parameters remains unknown., Methods: We included 11 healthy volunteers and 122 patients with normal and severely reduced function, wide and narrow QRS, as well as with and without infarct scar. Location and extent of infarct scar was defined by contrast-enhanced cardiac magnetic resonance. Influence of infarct scar on the motion pattern of the LV was examined by measuring direction and amplitude of apical rocking. The influence of scar on different echocardiographic dyssynchrony parameters was investigated., Results: Scar in the absence of conduction delay caused most apical rocking in the presence of 3 to 4 infarct segments. Pure apical infarction caused no rocking. In wide QRS patients without infarct scar, apical rocking was mainly dominated by the conduction delay, whereas in wide QRS patients with ischemic cardiomyopathy, this pattern was modulated by the scar. Apical rocking was inversely related to scar extent (r = -0.54, p < 0.05). Apical rocking was better associated with cardiac resynchronization therapy response than conventional dyssynchrony measurements., Conclusions: LV motion patterns are mainly dominated by conduction delays, but they are also modulated by infarct scar. Higher scar burden resulted in less pronounced apical rocking. Apical rocking is more strongly associated with cardiac resynchronization therapy response than with conventional echocardiographic parameters and may therefore be used as a screening parameter., (Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Galectin-1 (Gal-1) is a naturally occurring galactose-binding lectin, which is overexpressed in glioblastoma multiforme (GBM). Gal-1 is associated with tumor progression, and is a potent immune suppressor in the tumor micro-environment. To inhibit Gal-1 in GBM, an effective therapy is required that reaches the central nervous system tumor, with limited systemic effects. In this study, we report for the first time that concentrated chitosan nanoparticle suspensions can deliver small interfering RNA (siRNA) into the central nervous system tumor within hours after intranasal administration. These nanoparticles are able to complex siRNA targeting Gal-1 to a high percentage, and protect them from RNAse degradation. Moreover, a successful intracellular delivery of anti-Gal-1 siRNA resulted in a decreased expression of Gal-1 in both murine and human GBM cells. Sequence specific RNAinterference, resulted in more than 50% Gal-1 reduction in tumor bearing mice. This study indicates that the intranasal pathway is an underexplored transport route for delivering siRNA-based therapies targeting Gal-1 in the treatment of GBM., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Tight junction (TJ) defects have recently been associated with asthma and chronic rhinosinusitis. The expression, function, and regulation of nasal epithelial TJs remain unknown in patients with allergic rhinitis (AR)., Objective: We investigated the expression, function, and regulation of TJs in the nasal epithelium of patients with house dust mite (HDM)-induced AR and in an HDM-induced murine model of allergic airway disease., Methods: Air-liquid interface cultures of primary nasal epithelial cells of control subjects and patients with HDM-induced AR were used for measuring transepithelial resistance and passage to fluorescein isothiocyanate-dextran 4 kDa (FD4). Ex vivo transtissue resistance and FD4 permeability of nasal mucosal explants were measured. TJ expression was evaluated by using real-time quantitative PCR and immunofluorescence. In addition, the effects of IL-4, IFN-γ, and fluticasone propionate (FP) on nasal epithelial cells were investigated in vitro. An HDM murine model was used to study the effects of allergic inflammation and FP treatment on transmucosal passage of FD4 in vivo., Results: A decreased resistance in vitro and ex vivo was found in patients with HDM-induced AR, with increased FD4 permeability and reduced occludin and zonula occludens-1 expression. AR symptoms correlated inversely with resistance in patients with HDM-induced AR. In vitro IL-4 decreased transepithelial resistance and increased FD4 permeability, whereas IFN-γ had no effect. FP prevented IL-4-induced barrier dysfunction in vitro. In an HDM murine model FP prevented the allergen-induced increased mucosal permeability., Conclusion: We found impaired nasal epithelial barrier function in patients with HDM-induced AR, with lower occludin and zonula occludens-1 expression. IL-4 disrupted epithelial integrity in vitro, and FP restored barrier function. Better understanding of nasal barrier regulation might lead to a better understanding and treatment of AR., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: The naso-ocular interaction in allergic rhinoconjunctivitis is well recognized from epidemiological, clinical, and experimental observations. The precise mechanisms remain incompletely understood. A new mouse model of allergic rhinoconjunctivitis was used to investigate the contribution of mast cells and trigeminal ganglia activation to conjunctival (conj.) inflammation after nasal allergen provocation., Methods: Sensitized mice were exposed to ovalbumin (OVA) via the nose and/or conjunctiva, and conj. homogenates were analyzed for histamine and substance P (using ELISA) and by eosinophil peroxidase (EPO) and beta-hexosaminidase assays. The conj. effects of nasal allergen deposition were compared with those induced by the mast cell activator C48/80 and with pretreatment of the mast cell stabilizer ketotifen or the transient receptor potential channel receptor (TRP) agonist capsaicin. Protachykinin 1 (TAC1) expression was quantified in the trigeminal ganglia using real time polymerase chain reaction., Results: At 1 hour after nasal application of OVA, increased conj. levels of beta-hexosaminidase (0.68 ± 0.03 nm versus 0.56 ± 0.02 nm; p = 0.02), histamine (751.1 ± 52.17 ng/mL versus 546.3 ± 76.91 ng/mL; p = 0.05), and EPO (0.66 ± 0.09 nm versus 0.37 ± 0.03 nm; p = 0.02) were detected compared with saline. Higher levels of TAC1 expression were found in the trigeminal ganglia at 24 hours after OVA application (1326 ± 255 versus 687.5 ± 90.77 TAC1/beta-actin; p = 0.04). Nasal challenge with C48/80 increased substance P and beta-hexosaminidase levels in the conjunctiva, as well as TAC1 expression. Pretreatment with ketotifen resulted in lower levels of substance P as well as TAC1 expression. Destruction of sensory nerves in the nose by capsaicin reduced the OVA-induced conj. levels of substance P, histamine, and beta-hexosaminidase., Conclusion: Nasal allergen deposition in sensitized mice induced trigeminal TAC1 expression and conj. mast cell degranulation. These data represent a significant step forward in understanding the close interaction between nasal and conj. inflammation in allergy.