The effect of fluticasone propionate on respiratory syncytial virus-induced chemokine release by a human bronchial epithelial cell line

Inhaled corticosteroids for the treatment of COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused severe illness and mortality for millions worldwide. Despite the development, approval and rollout of vaccination programmes globally to prevent infection by SARS-CoV-2 and the development of coronavirus disease 2019 (COVID-19), treatments are still urgently needed to improve outcomes. Early in the pandemic it was observed that patients with pre-existing asthma or COPD were underrepresented among those with COVID-19. Evidence from clinical studies indicates that the inhaled corticosteroids (ICS) routinely taken for asthma and COPD could have had a protective role in preventing severe COVID-19 and, therefore, may be a promising treatment for COVID-19. This review summarises the evidence supporting the beneficial effects of ICS on outcomes in patients with COVID-19 and explores the potential protective mechanisms.

Interleukin-23 facilitates Th1 and Th2 cell differentiation in vitro following respiratory syncytial virus infection

Respiratory syncytial virus (RSV) infection induces activation and imbalance of the immune system; however, the role of T helper 17 cells (Th17) in the response to RSV infection remains unclear. Interleukin-23 (IL-23) is a key cytokine in Th17 cell differentiation. The aim of this study was to explore the function of IL-23 in determining the distribution of Th lymphocyte subsets (Th1, Th2, and Th17) after RSV infection in vitro. Human bronchial epithelial cell line BEAS-2B was infected with mock or RSV at various multiplicities of infection (MOI) and transcript expression of IL-6, IL-23p19, and transforming growth factor (TGF-β) was detected by real-time polymerase chain reaction; IL-6, IL-23, and TGF-β in the supernatant were measured by enzyme-linked immunosorbent assay. The Th subset distribution in lymphocytes was determined by flow cytometry after co-culture with supernatants from mock and 72-hr RSV infection cultures. The role of IL-23 in lymphocytes was assessed by specific receptor blockade (IL-23R) prior to co-culture with supernatants from RSV-infected BEAS-2B cells, followed by flow cytometry to analyze Th subset differentiation. Cytokine expression increased after RSV infection. IL-23R blockade suppressed the differentiation of Th1, Th2, and Th17 cells in the presence of supernatants from RSV-infected BEAS-2B cells. RSV infection may induce cytokine secretion, thus inducing Th1, Th2, and Th17 differentiation via an IL-23R-dependent process.

Cytokine profiles, signalling pathways and effects of fluticasone propionate in respiratory syncytial virus-infected human foetal lung fibroblasts

To examine cytokine production in response to RSV infection, we assessed the levels of 29 cytokines released from RSV-infected human foetal lung fibroblasts. We also examined the relationships between the effects of fluticasone propionate and various signalling pathways in the cells. Twenty-four hours after infection (1MOI), RSV-infected cells released cytokines, for example proinflammatory cytokines (IL-1β, IL-6 and TNF-α), anti-inflammatory (IL-1ra), Th1 (IFN-γ, IFN-λ1a, IL-2 and IL-12), Th2 (IL-4, IL-5, IL-10 and IL-13), granulopoiesis-inducing (G-CSF and GM-CSF), eosinophil recruitment-inducing (eotaxin and RANTES) and neutrophil recruitment-inducing cytokines (IL-8, IP-10, MCP-1 and MIP-1α). Aberrant release of most was significantly suppressed by fluticasone propionate. Twelve hours after RSV infection, increased phosphorylation of Akt, p38 MAPK, ERK1/2 and IκB-α was noted. Fluticasone propionate suppressed the phosphorylation of Akt, p38 MAPK, and ERK1/2, but not IκB-α, in virus-infected cells. TLR-4 expression was unchanged in control and RSV-infected cells, and TLR-3 and RIG-I expression was not detected. The results indicate that RSV infection induces aberrant production and release of certain cytokines through these signalling pathways in human lung fibroblasts. Overproduction and imbalance of these cytokines may be associated with the pathophysiology of RSV-induced excessive and allergic inflammation.

Respiratory syncytial virus infections in the adult asthmatic--mechanisms of host susceptibility and viral subversion

Respiratory syncytial virus (RSV), a single-stranded RNA virus of the Paramyxoviridae family, is a major cause of bronchiolitis in infants and is also conjectured to be an early-life influence on the development of asthma. Although the data supporting a role for RSV in bronchiolitis in children are robust and evidence to support its role in juvenile asthmatics exists, RSV's role in asthma pathogenesis in adults is not as clearly defined. The authors review the literature to further elucidate RSV's impact on adult asthmatics, including its importance as a cause of asthma exacerbations. They examine the morbidity associated with RSV infection and how the immune response may differ between adult asthmatics and nonasthmatics. They review the responses by specific cell types from adults with asthma that are stimulated by RSV. They also consider the role of early-life exposure to RSV and its contribution to asthma in adults. Lastly, they review the mechanisms by which RSV evades normal host immune responses and subverts these responses to its benefit.

THE EFFECT OF RESPIRATORY SYNCTIAL VIRUS ON CHEMOKINE RELEASE BY DIFFERENTIATED AIRWAY EPITHELIUM

Respiratory synctial virus (RSV) infection of undifferentiated airway epithelial cells has been shown to induce the production of chemokines. The purpose of this study was to investigate the vectorial release of interleukin (IL-8) and Released on Activation, Normal T-cell Expressed and Secreted (RANTES) by polarized, well-differentiated respiratory epithelial cells after RSV infection. Human bronchial epithelial cultures were differentiated under air-liquid interface conditions and infected with RSV by the apical or basolateral route. RSV infection was specific to the apical surface. Supernatants were collected at 6 and 48 hours after RSV inoculation, and IL-8 and RANTES were measured by enzyme-linked immunosorbent assay (ELISA). Both IL-8 and RANTES were significantly released by 48 hours following inoculation with RSV. The secretion of each chemokine was greatest after apical inoculation, and secretion was polarized to the basolateral supernatant. Immunohistochemical staining confirmed that RSV infection was specific to ciliated cells, and immunohistochemical staining for chemokines was localized to RSV-infected ciliated cells. The authors conclude that, in differentiated human airway epithelium in vitro, RSV-induced increases in IL-8 and RANTES release are predominantly in the basolateral direction. In epithelial layers, virus-containing cells are the predominant source of the increased chemokine release. The authors speculate that similar processes in vivo influence recruitment of leukocytes to sites of RSV infection.

Inhibition by salmeterol and cilomilast of fluticasone-enhanced IP-10 release in airway epithelial cells

The CXC chemokines, IP-10/CXCL10 and IL-8/CXCL8, play a role in obstructive lung disease by attracting Th1/Tc1 lymphocytes and neutrophils, respectively. Inhaled corticosteroids (ICS) and long acting beta 2-agonists (LABA) are widely used. However, their effect(s) on the release of IP-10 and IL-8 by airway epithelial cells are poorly understood. This study examined the effects of fluticasone, salmeterol, and agents which raise intracellular cAMP (cilomilast and db-cAMP) on the expression of IP-10 and IL-8 protein and mRNA. Studies were performed in cultured human airway epithelial cells during cytokine-stimulated IP-10 and IL-8 release. Cytokine treatment (TNF-alpha, IL-1beta and IFN-gamma) increased IP-10 and IL-8 protein and mRNA levels. Fluticasone (0.1 nM to 1 microM) increased IP-10 but reduced IL-8 protein release without changing IP-10 mRNA levels assessed by real time RT-PCR. The combination of salmeterol (1 micro M) and cilomilast (1-10 mu M) reduced IP-10 but had no effect on IL-8 protein. Salmeterol alone (1 micro M) and db-cAMP alone (1 mM) antagonised the effects of fluticasone on IP-10 but not IL-8 protein. In human airway epithelial cells, inhibition by salmeterol of fluticasone-enhanced IP-10 release may be an important therapeutic effect of the LABA/ICS combination not present when the two drugs are used separately.

Pathogen-directed therapy in acute exacerbations of chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are important events in the natural history of this chronic lung disorder. These events can be caused by a large number of infectious and noninfectious agents and are associated with an increased local and systemic inflammatory response. Their frequency and severity have been linked to progressive deterioration in lung function and health status. Infectious pathogens ranging from viral to atypical and typical bacteria have been implicated in the majority of episodes. Most therapeutic regimens to date have emphasized broad, nonspecific approaches to bronchoconstriction and pulmonary inflammation. Increasingly, therapy that targets specific etiologic pathogens has been advocated. These include clinical and laboratory-based methods to identify bacterial infections. Further additional investigation has suggested specific pathogens within this broad class. As specific antiviral therapies become available, better diagnostic approaches to identify specific pathogens will be required. Furthermore, prophylactic therapy for at-risk individuals during high-risk times may become a standard therapeutic approach. As such, the future will likely include aggressive diagnostic algorithms based on the combination of clinical syndromes and rapid laboratory modalities to identify specific causative bacteria or viruses.

Efficacy of dexamethasone injection for acute bronchiolitis in hospitalized children: a randomized, double-blind, placebo-controlled trial

Controversy over the efficacy of systemic corticosteroids for acute bronchiolitis initiated this study. We conducted a randomized, double-blind, placebo-controlled trial to examine the efficacy of single dexamethasone injection for the treatment of acute bronchiolitis in young hospitalized children. The study, performed at the pediatric wards of a University Hospital and its affiliated hospital in Thailand, included 174 previously healthy children under 2 years of age, hospitalized with acute bronchiolitis. Each child received either a single intramuscular injection of 0.6 mg/kg dexamethasone or a placebo in addition to regular management. The primary outcome was the time from study entry to resolution of respiratory distress, determined by a clinical score derived from the respiratory rate, occurrence of wheezing, chest retraction, and oxygen saturation. Survival analysis using the Kaplan-Meier method and a log-rank test were performed. A single-dose, dexamethasone injection versus placebo produced a significant: (1) decrease in the time needed for resolution of respiratory distress (hazard ratio 1.56; 95% CI, 1.14-2.13; P = 0.005), (2) decrease in the mean duration of symptoms of 11.8 hr (95% CI, 3.9-19.7; P = 0.004), (3) decrease in the mean duration of oxygen therapy of 14.9 hr (95% CI, 5.3-24.4; P = 0.003), and (4) decrease in the mean length of hospital stay of 13.4 hr (95%CI, 2.6-24.2; P = 0.02). In conclusion, a single injection of dexamethasone yielded a significant clinical benefit for the treatment of previously healthy, young children hospitalized with acute bronchiolitis.

Persistent airway obstruction after virus infection is not associated with airway inflammation

BACKGROUND

This study examined the contribution of airway inflammation to the delayed lung function recovery that occurs in some people following virus-induced asthma exacerbations.

METHODS

Subjects (n = 40) were recruited at hospital admission for acute asthma exacerbation. Respiratory virus infection was diagnosed by viral nucleic acid detection and/or cell culture, using induced sputum, nasal, or throat swabs. Data collected included lung function, answers to common cold and asthma control questionnaires, and induced sputum cellular profiles. Subjects were reexamined 4 to 6 weeks postexacerbation and were compared with stable asthmatic subjects (n = 26) who had been recruited from ambulatory care clinics.

RESULTS

Persistent airway obstruction, defined as lung function improvement at follow-up (ie, change in FEV1 percent predicted [Delta%FEV1]) of <15%, was observed in 10 subjects (25%). Airway recovery (Delta%FEV1, > or = 15%) was observed in the remaining subjects (30 subjects; 75%). During the acute episode, the airway-recovery group had increased total cell count (p = 0.019), increased number of neutrophils (p = 0.005), and increased percentage of neutrophils (p = 0.0043) compared to the group of stable subjects with asthma. Postexacerbation, the airway-recovery group had reduced numbers of neutrophils and an increased percentage of eosinophils. In contrast, during exacerbation, subjects with persistent airway obstruction showed no differences in inflammatory cell counts compared to stable subjects with asthma, nor did cell counts change postexacerbation. Symptoms improved in both groups postexacerbation. However, in the persistent-airway-obstruction group, asthma remained uncontrolled.

CONCLUSION

Persistent airway obstruction and uncontrolled asthma are observed in some people after viral asthma exacerbations. These abnormalities are not associated with inflammatory cell influx into the airway lining fluid during the exacerbation and may reflect the involvement of noncellular elements. Further work should explore other mechanisms leading to incomplete airway recovery.

Combined fluticasone propionate and salmeterol reduces RSV infection more effectively than either of them alone in allergen-sensitized mice

BACKGROUND

Respiratory syncytial virus (RSV) infection is the major cause of bronchiolitis in infants and is a risk factor for the development of asthma. Allergic asthmatics are more susceptible to RSV infection and viral exacerbation.

METHODS

Since the effectiveness of corticosteroids in treating RSV infection has been controversial, we tested fluticasone propionate (FP) and salmeterol (Sal) alone versus FP plus Sal (FPS) on RSV-induced airway inflammation. Mice were sensitized and challenged with ovalbumin (OVA) and infected with RSV. Following infection they were treated with FP, Sal, or FPS intranasally and airway hyperreactivity (AHR), inflammation and RSV titers were examined.

RESULTS

The group treated with FPS showed significantly lower AHR compared to the group treated with FP or Sal alone. The group treated with FP alone showed slightly decreased (non-significant) AHR compared to controls. Treatment with FPS resulted in significant decreases in the percentage of eosinophils and neutrophils in bronchoalveolar lavage fluid and in lung pathology compared to FP or Sal. FP alone decreased eosinophils but not neutrophils or lymphocytes, while Sal alone decreased eosinophils and neutrophils but not lymphocytes. FPS treatment of mice infected with RSV in the absence of allergen sensitization resulted in a 50% decrease of RSV titer in the lung and a reduction in neutrophils compared to FP or Sal.

CONCLUSION

Together, these results indicate that fluticasone in combination with salmeterol is a more effective treatment for decreasing airway hyperreactivity and inflammation than either of them alone in allergen-sensitized, RSV-infected mice.

Role of infection and antimicrobial therapy in acute exacerbations of chronic obstructive pulmonary disease

Over the past several years, the significance of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) in patients with chronic airflow obstruction has become increasingly apparent due to the impact these episodes have on the natural history of disease. It is now known that frequent AECOPD can adversely affect a patient's health-related quality of life and short- and long-term pulmonary function. The economic burden of these episodes is also substantial. AECOPDs represent a local and systemic inflammatory response to both infectious and noninfectious stimuli, but the majority of episodes are likely related to bacterial or viral pathogens. Patients with purulent sputum and multiple symptoms are the most likely to benefit from treatment with antibiotics. Antibiotic choice should be tailored to the individual patient, taking into account the severity of the episode and host factors which might increase the likelihood of treatment failure. Current evidence suggests that therapeutic goals not only include resolution of the acute episode, but also prolonging the time to the next event. In the future, preventing exacerbations will likely become increasingly accepted as an additional therapeutic goal in chronic obstructive pulmonary disease patients.

3-nitrotyrosine attenuates respiratory syncytial virus infection in human bronchial epithelial cell line

3-nitrotyrosine (NO2Tyr), an L-tyrosine derivative during nitrative stress, can substitute the COOH-terminal tyrosine of alpha-tubulin, posttranslationally altering microtubular functions. Because infection of the cells by respiratory syncytial virus (RSV) may require intact microtubules, we tested the hypothesis that NO2Tyr would inhibit RSV infection and intracellular signaling via nitrotyrosination of alpha-tubulin. A human bronchial epithelial cell line (BEAS-2B) was incubated with RSV with or without NO2Tyr. The release of chemokines and viral particles and activation of interferon regulatory factor-3 (IRF-3) were measured. Incubation with NO2Tyr increased nitrotyrosinated alpha-tubulin, and NO2Tyr colocalized with microtubules. RSV-infected cells released viral particles, RANTES, and IL-8 in a time- and dose-dependent manner, and intracellular RSV proteins coprecipitated with alpha-tubulin. NO2Tyr attenuated the RSV-induced release of RANTES, IL-8, and viral particles by 50-90% and decreased alpha-tubulin-associated RSV proteins. 3-chlorotyrosine, another L-tyrosine derivative, had no effects. NO2Tyr also inhibited the RSV-induced shift of the unphosphorylated form I of IRF-3 to the phosphorylated form II. Pre-exposure of the cells to NO(2) (0.15 ppm, 4 h), which produced diffuse protein tyrosine nitration, did not affect RSV-induced release of RANTES, IL-8, or viral particles. NO2Tyr did not affect the potential of viral spreading to the neighboring cells since the RSV titers were not decreased when the uninfected cells were cocultured with the preinfected cells in NO2Tyr-containing medium. These results indicate that NO2Tyr, by replacing the COOH-terminal tyrosine of alpha-tubulin, attenuated RSV infection, and the inhibition appeared to occur at the early stages of RSV infection.

Additive effects of dexamethasone in nebulized salbutamol or L-epinephrine treated infants with acute bronchiolitis

BACKGROUND

Although it is the most common lower respiratory infection of infancy, the optimal treatment for acute bronchiolitis is still controversial. The aim of this study was to compare the early and late effects of nebulized L-epinephrine (EPI) and intramuscular dexamethasone (DEX) combination therapy with nebulized salbutamol (SAL) and dexamethasone combination and bronchodilators alone in outpatients with acute bronchiolitis.

METHODS

A total of 69 infants aged 2-21 months who were admitted to the Pediatrics Department of the Faculty of Medicine, Mersin University, with acute bronchiolitis were included in a randomized, placebo-controlled, prospective trial study. Patients were assigned to receive either nebulized L-epinephrine (3 mg) or salbutamol (0.15 mg/kg) and 15 min later, either dexamethasone 0.6 mg/kg or placebo (PLA), intramuscularly, in a double-blind randomized fashion. The study groups were: epinephrine + dexamethasone group (group 1, n=23), salbutamol + dexamethasone group (group 2, n=23), epinephrine + placebo group (group 3, n=11), and salbutamol + placebo group (group 4, n=12). The outcome measures were heart rate, respiratory rate and Respiratory Distress Assessment Instrument (RDAI) score determined at 30, 60, 90 and 120 min, 24 h, and 5 days after the first therapy. Patients were then followed-up during the subsequent 2 months for the prevalance of respiratory complaints regarding bronchial hyperreactivity.

RESULTS

There were no significant differences between the outcome variables of the four groups within the first 120 min and at 24 hours, or between the rates of requirement of a second dose of the same bronchodilator. However, fifth day RDAI score values of both DEX groups were significantly lower than that of SAL + PLA group (P=0.000 and P=0.01, respectively). The fifth day score value of group 1 was also significantly better than that value of EPI + PLA group but not different from group 2.

CONCLUSIONS

A single dose of intramuscular dexamethasone added to nebulized L-epinephrine, or salbutamol therapies resulted in better outcome measures than bronchodilators alone in the late phase (fifth day) of mild to moderate degree bronchiolitis attack. However, effects of EPI + DEX combination was not different from SAL + DEX combination.

Efficacy of oral dexamethasone in outpatients with acute bronchiolitis

OBJECTIVE

To examine the efficacy of oral dexamethasone in acute bronchiolitis.

STUDY DESIGN

A double-blind randomized, placebo-controlled trial involving 70 children < 24 months old in the emergency department with Respiratory Disease Assessment Instrument > or = 6. Each patient received either 1 dose of 1 mg/kg of oral dexamethasone or placebo and was assessed hourly for a 4-hour period. Repeated measures regression analysis evaluated a change in the Respiratory Assessment Change Score (RACS).

RESULTS

The 2 groups had similar baseline characteristics with Respiratory Disease Assessment Inventory of 9.4 +/- 2.3 in the dexamethasone group (n = 36) and 10.0 +/- 2.7 in the placebo group (n = 34). The RACS was -5.0 +/- 3.1 in the dexamethasone group and -3.2 +/- 3.7 in the placebo group (P =.029). Poor RACS occurred in 41% and 17% of the placebo and dexamethasone groups, respectively (P =.034). Of the children treated with dexamethasone, 19% were hospitalized compared with 44% in the placebo group (P =.039). There was no difference in RACS between the groups on day 7 (P =.75).

CONCLUSION

Outpatients with moderate-to-severe acute bronchiolitis derive significant clinical and hospitalization benefit from oral dexamethasone treatment in the initial 4 hours of therapy.

The interaction of neutrophils with respiratory epithelial cells in viral infection

Viral respiratory infection is very common. Respiratory syncytial virus (RSV) infects almost all children during the first 2 years of life. Respiratory syncytial virus is the most frequent cause of bronchiolitis, which is strongly linked with asthma. However, the pathophysiology of RSV bronchiolitis is unclear. Neutrophils are the predominant airway leucocytes in RSV bronchiolitis and other viral infections. Neutrophils and their products are likely to play an important role in viral infection. Current evidence indicates that: (i) viral infection of epithelial cells increases the production of neutrophil chemoattractants or chemokines, which induce neutrophil migration into the inflammatory sites; (ii) the expression of adhesion molecules on neutrophils and epithelial cells is up-regulated in viral infection, and neutrophil-epithelial adhesion is increased; (iii) neutrophils augment epithelial damage and detachment induced by viral infection and contribute to the pathophysiology of viral disease; (iv) neutrophil apoptosis is up-regulated in RSV infection, which may be an in vivo mechanism to limit neutrophil-induced epithelial damage; (v) inhibitors of chemokines, adhesion molecules or neutrophil proteases may be useful in prevention of neutrophil-induced epithelial damage. In conclusion, neutrophils play an important role in viral infection, and intervention to prevent neutrophil-induced epithelial damage may be a potential clinical therapy.