Effects of rhinovirus infection on the expression and function of cystic fibrosis transmembrane conductance regulator and epithelial sodium channel in human nasal mucosa

Modulator-refractory cystic fibrosis: Defining the scope and challenges of an emerging at-risk population

Cystic fibrosis (CF) causes life-shortening respiratory and systemic disease due to dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. Highly effective modulator therapies (HEMT) improve the lives of many people with cystic fibrosis (PwCF) by correcting the structure and function of the defective CFTR channel at the molecular level. Despite these advancements, a subset of patients-termed modulator-refractory CF-continues to experience two or more pulmonary exacerbations per year requiring hospitalization or intravenous antibiotics, regardless of other modulator benefits. This underrecognized group represents an emerging challenge within the CF community. We discuss the benefits and limitations of current CFTR modulator therapies and the urgent need to investigate this emerging at-risk population. While HEMT improves lung function, decreases exacerbations, reduces the need for lung transplantation, and lowers mortality, increasing evidence shows that not all patients benefit equally. At the University of Virginia, nearly 6% of adults with CF exhibit the modulator-refractory phenotype. The driving factors of modulator-refractory CF are likely multifactorial, including genetic variations, variable immune responses, preexisting bronchiectasis, microbiological colonization, preexisting comorbid conditions, and environmental and socioeconomic factors. This perspective review recognizes and defines modulator-refractory CF as a distinct emerging clinical phenotype in the post-modulator era. Understanding this phenotype is crucial for reducing morbidity and mortality, and for improving the quality of life for PwCF. Raising awareness of modulator-refractory CF will help the community address this population and perform further research to identify causes. The emergence of modulator-refractory CF highlights a significant gap in our current treatment landscape and provides an opportunity to develop innovative therapeutic strategies that may benefit the entire CF community, ensuring that no person with CF is left behind.

Rhinorrhea and increased chloride secretion through the CFTR chloride channel-a systematic review

PURPOSE

Allergic and non-allergic rhinorrhea in the forms of acute or chronic rhinosinusitis can mean a watery nasal discharge that is disabling. Primary objective was to review the evidence supporting the hypothesis that rhinorrhea is due to increased chloride secretion through the CFTR chloride channel.

METHODS

The structure of the evidence review followed the EQUATOR Reporting Guidelines. Databases searched from inception to February 2022 included Pubmed, EMBASE and the Cochrane library using keywords "Rhinorrhea", "chloride", "chloride channel", "CFTR" and "randomized controlled trial". Quality assessment was according to the Oxford Centre for Evidence-based Medicine.

RESULTS

49 articles were included. They included randomized controlled trials out of which subsets of data with the outcome of rhinorrhea on 6038 participants were analysed and in vitro and animal studies. The review revealed that drugs, which activate CFTR are associated with rhinorrhea. Viruses, which cause rhinorrhea like rhinovirus were found to activate CFTR. The chloride concentration in nasal fluid showed an increase in patients with viral upper respiratory tract infection. Increased hydrostatic tissue pressure, which is an activator of CFTR was observed in allergic upper airway inflammation. In this condition exhaled breath condensate chlorine concentration was found to be significantly increased. Drugs, which can reduce CFTR function including steroids, anti-histamines, sympathomimetic and anticholinergic drugs reduced rhinorrhea in randomized controlled trials.

CONCLUSIONS

A model of CFTR activation-mediated rhinorrhea explains the effectiveness of anticholinergic, sympathomimetic, anti-histamine and steroid drugs in reducing rhinorrhea and opens up avenues for further improvement of treatment by already known specific CFTR inhibitors.

Are rhinoviruses implicated in the pathogenesis of sinusitis and chronic rhinosinusitis exacerbations? A comprehensive review

BACKGROUND

Rhinovirus (RV) infections are the most common cause of viral upper respiratory infections (URIs), and in the majority of persons they are self-limiting. However, in others, viral URIs can progress to bacterial sinusitis and induce chronic rhinosinusitis (CRS) exacerbations.

METHODS

We conducted a comprehensive Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) review through April 2018 based on MEDLINE, EMBASE, Web of Science-Science Citation Index (SCI), and Conference Proceedings Citation Index- Science (CPCI-S) using keywords: RV, respiratory virus, sinusitis, and airway epithelial cells. The goal of this systematic review was to: (1) determine the prevalence between RV and CRS, (2) study the changes that occur after experimental RV inoculation, (3) investigate the pathophysiologic mechanisms by which RV induces sinonasal inflammation, and (4) explore the treatment options available for RV-associated sinusitis. Data regarding study design, research question, intervention, subjects, outcomes, and biases was extracted.

RESULTS

The initial search yielded 2395 unique abstracts, of which 614 were selected for full-text review; 147 were included in the final review. We determined that (1) the prevalence of RV infections is increased in those with CRS, (2) humans challenged in vivo with RV secrete local inflammatory mediators with radiographic mucosal thickening, (3) RV species RV-A and RV-C challenges in vitro to sinonasal epithelia produce robust cytokine responses and differential gene changes, and (4) no current therapies have produced consistent and significant resolution of disease.

CONCLUSION

RV infections are common in persons with CRS, and incite inflammatory reactions that may result in CRS exacerbations and progression of disease. Further studies assessing RV species, and the host-virome response are required to develop new strategies targeting RV-induced CRS.

Determination of nasal mucociliary clearance time and nasal symptom in patients with Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is an important health problem in Turkey. Number of studies on symptoms of ear nose throat system and indicating whether or not the organs are affected in patients with CCHF is limited. The aim of the present study was to investigate whether CCHF infections caused any change in nasal physiology in adult patients or not by using saccharin transit time (STT) and nasal symptom scoring. Twenty subjects with laboratory-confirmed diagnosis of CCHF and 28 healthy control subjects were included in the present study. A saccharin test was used to evaluate nasal mucociliary clearance time (NMCT) and the nasal symptom scoring used in allergic rhinitis was modified and used to examine the symptoms of the patients. The average STT of CCHF and control groups were 472.70 ± 151.58 and 276.07 ± 89.65 sec, respectively. The difference between them was statistically significant (P = 0.00, P < 0.05). When those in CCHF group were classified according to timing of the test, STT average of those undergoing the test on the 1st-3rd days (n = 10) and 4th-6th (n = 10) days was 547.00 ± 154.37 and 398.40 ± 111.39 sec, respectively. The difference between them was statistically significant (P = 0.024; P < 0.05). The results of the present study showed that NMCT prolonged in adult patients with CCHF compared to those in the control group despite the fact that it was within normal limits. For these reasons, clinicians should follow-up CCHF patients more closely for respiratory tract diseases and sinonasal and middle ear infections. J. Med. Virol. 89:960-965, 2017. © 2016 Wiley Periodicals, Inc.

Update on Human Rhinovirus and Coronavirus Infections

Human rhinovirus (HRV) and coronavirus (HCoV) infections are associated with both upper respiratory tract illness (“the common cold”) and lower respiratory tract illness (pneumonia). New species of HRVs and HCoVs have been diagnosed in the past decade. More sensitive diagnostic tests such as reverse transcription-polymerase chain reaction have expanded our understanding of the role these viruses play in both immunocompetent and immunosuppressed hosts. Recent identification of severe acute respiratory syndrome and Middle East respiratory syndrome viruses causing serious respiratory illnesses has led to renewed efforts for vaccine development. The role these viruses play in patients with chronic lung disease such as asthma makes the search for antiviral agents of increased importance.

Epithelial Sodium and Chloride Channels and Asthma

Objective:

To focus on the asthmatic pathogenesis and clinical manifestations related to epithelial sodium channel (ENaC)/chlorine ion channel.

Data Sources:

The data analyzed in this review were the English articles from 1980 to 2015 from journal databases, primarily PubMed and Google Scholar. The terms used in the literature search were: (1) ENaCs; cystic fibrosis (CF) transmembrane conductance regulator (CFTR); asthma/asthmatic, (2) ENaC/sodium salt; CF; asthma/asthmatic, (3) CFTR/chlorine ion channels; asthma/asthmatic, (4) ENaC/sodium channel/scnn1a/scnn1b/scnn1g/scnn1d/amiloride-sensitive/amiloride-inhibtable sodium channels/sodium salt; asthma/asthmatic, lung/pulmonary/respiratory/tracheal/alveolar, and (5) CFTR; CF; asthma/asthmatic (ti).

Study Selection:

These studies included randomized controlled trials or studies covering asthma pathogenesis and clinical manifestations related to ENaC/chlorine ion channels within the last 25 years (from 1990 to 2015). The data involving chronic obstructive pulmonary disease and CF obtained from individual studies were also reviewed by the authors.

Results:

Airway surface liquid dehydration can cause airway inflammation and obstruction. ENaC and CFTR are closely related to the airway mucociliary clearance. Ion transporters may play a critical role in pathogenesis of asthmatic exacerbations.

Conclusions:

Ion channels have been the center of many studies aiming to understand asthmatic pathophysiological mechanisms or to identify therapeutic targets for better control of the disease.

Human Rhinovirus-induced Proinflammatory Cytokine and Interferon-β Responses in Nasal Epithelial Cells From Chronic Rhinosinusitis Patients

Purpose

Asthma exacerbation from human rhinovirus (HRV) infection is associated with deficient antiviral interferon (IFN) secretion. Although chronic rhinosinusitis (CRS), an inflammatory upper airway disease, is closely linked to asthma, IFN-β responses to HRV infections in human nasal epithelial cells (HNECs) from CRS patients remain to be studied. We evaluated inflammatory and antiviral responses to HRV infection in HNECs from CRS patients.

Methods

HNECs, isolated from turbinate tissue of 13 patients with CRS and 14 non-CRS controls, were infected with HRV16 for 4 hours. The HRV titer, LDH activity, production of proinflammatory cytokines and IFN-β proteins, and expression levels of RIG-I and MDA5 mRNA were assessed at 8, 24, and 48 hours after HRV16 infection.

Results

The reduction in viral titer was slightly delayed in the CRS group compared to the non-CRS control group. IL-6 and IL-8 were significantly increased to a similar extent in both groups after HRV infection. In the control group, IFN-β production and MDA5 mRNA expression were significantly increased at 8 and 24 hours after HRV16 infection, respectively. By contrast, in the CRS group, IFN-β was not induced by HRV infection; however, HRV-induced MDA5 mRNA expression was increased, but the increase was slightly delayed compared to the non-CRS control group. The RIG-I mRNA level was not significantly increased by HRV16 infection in either group.

Conclusions

HRV-induced secretion of proinflammatory cytokines in CRS patients was not different from that in the non-CRS controls. However, reductions in viral titer, IFN-β secretion, and MDA5 mRNA expression in response to HRV infection in CRS patients were slightly impaired compared to those in the controls, suggesting that HRV clearance in CRS patients might be slightly deficient.

Expression and distribution of epithelial sodium channel in nasal polyp and nasal mucosa

To evaluate the expression and location of epithelial sodium channels (ENaCs) in human nasal polyp and normal nasal mucosa, and to characterize the relevance of ENaCs to the development of NPs. Nasal polyp tissue from 17 patients and nasal mucosa from ten patients were obtained through endoscopic sinus surgery. The mRNA concentrations of ENaC-α, β, and γ were detected by real-time polymerase chain reaction. The expression of ENaC-α was detected using western blot and immunofluorescence techniques. The distribution of ENaC-α in mucosal tissue was observed using a laser scanning confocal microscope. The transcriptional expression of three subunits of ENaC was in the following order: α > β > γ, in both groups. The transcriptional expression of α, β, and γ subunits of ENaC was elevated in nasal polyp compared to nasal mucosa (p < 0.01). ENaC-α expression was higher in nasal polyp than in nasal mucosa (p < 0.05). Immunofluorescent staining indicated that ENaC-α protein was distributed in the epithelial cell apical membrane. The expression of ENaC is upregulated in human nasal polyp, which might in turn facilitate the formation and development of nasal polyp.

Modulation of ENaC, CFTR, and iNOS expression in bronchial epithelial cells after stimulation with Staphylococcus epidermidis (94B080) and Staphylococcus aureus (90B083)

Bacteria affect the respiratory epithelium, which is covered by airway surface liquid (ASL) and mucus. Ion concentrations in the ASL are determined by the cystic fibrosis transmembrane conductance regulator (CFTR) and the epithelial Na(+) channel (ENaC). Neonatal sepsis is a major risk factor for subsequent pulmonary disease in preterm newborns. Predominating are coagulase-negative staphylococci (e.g., Staphylococccus epidermidis and Staphylococccus aureus). The aim of this study was to investigate modulation of CFTR, ENaC, mucins, proinflammatory cytokines, and inducible nitric oxide synthase (iNOS) in respiratory epithelial cells after S. epidermidis 94B080 and S. aureus 90B083 exposure. Bronchial epithelial cells were incubated with S. epidermidis 94B080 and S. aureus 90B083 (neonatal blood isolates) for 1-36 h. Expression of CFTR, ENaC, iNOS, and mucins was analyzed by real-time PCR and Western blotting. Release of cytokines was analyzed by ELISA, and production of NO by the Griess assay. Expression of CFTR significantly decreased after 36 h incubation with S. epidermidis and more prominently with S. aureus, whereas S. epidermidis caused a significant increase in the expression of β- and γ-ENaC. Expression of iNOS increased, but NO was not detected. Both staphylococci caused a decrease in the intracellular Ca(2+) concentration. S. aureus induced increased secretion of IL-6, IL-8, and transforming nuclear factor (TNF)-α in a time-dependent manner as compared with S. epidermidis. In conclusion, expression of ENaC, CFTR, and iNOS is modulated by exposure to S. aureus 90B083 and S. epidermidis 94B080. S. aureus is more potent in causing release of IL-6, IL-8, and TNF-α by bronchial epithelial cells as compared with S. epidermidis. The mRNA expression for the mucus proteins MUC2, MUC5AC, and MUC5B could not be measured, neither in the presence nor in the absence of bacteria.