Tumour necrosis factor-alpha and leukotriene E4 production in wheezy infants

Enhanced airway hyperresponsiveness in asthmatic children and mice with A(H1N1)pdm09 infection

BACKGROUND

Severe asthma exacerbation is an important comorbidity of the 2009 HIN1 pandemic (A(H1N1)pdm09) in asthmatic patients. However, the mechanisms underlying severe asthma exacerbation remain unknown. In this study, airway hyperresponsiveness (AHR) was measured in pediatric asthma patients infected with A(H1N1)pdm09. We also evaluated AHR in asthmatic mice with A(H1N1)pdm09 infection and those with seasonal influenza for comparison.

METHODS

AHRs in asthmatic children were defined as the provocative acetylcholine concentration causing a 20% reduction in forced expiratory volume in 1 s (PC₂₀ ). To investigate the pathophysiology using animal models, BALB/c mice aged 6-8 weeks were sensitized and challenged with ovalbumin. Either mouse-adapted A(H1N1)pdm09, seasonal H1N1 virus (1 × 10⁵ pfu/20 μl), or mock treatment as a control was administered intranasally. At 3, 7, and 10 days after infection, each group of mice was evaluated for AHR by methacholine challenge using an animal ventilator, flexiVent. Lung samples were resected and observed using light microscopy to assess the degree of airway inflammation.

RESULTS

AHRs in the children with bronchial asthma were temporarily increased, and alleviated by 3 months after discharge. AHR was significantly enhanced in A(H1N1)pdm09-infected asthmatic mice compared to that in seasonal H1N1-infected mice (p < .001), peaking at 7 days postinfection and then becoming similar to control levels by 10 days postinfection. Histopathological examination of lung tissues showed more intense infiltration of inflammatory cells and severe tissue destruction in A(H1N1)pdm09-infected mice at 7 days postinfection than at 10 days postinfection.

CONCLUSION

Our results suggest that enhanced AHR could contribute to severe exacerbation in human asthmatic patients with A(H1N1)pdm09 infection.

Sleep disorders and allergic diseases in Chinese toddlers

OBJECTIVE

Optimal sleep is important for child growth, development, and immune function. We aimed to explore whether sleep disorders were associated with the risk of allergic diseases in Chinese toddlers.

METHODS

This study included 566 children (aged 23.9 ± 0.7 months; 51.1% boys) in Shanghai, China. Sleep parameters (total sleep time, sleep onset latency, nocturnal awaking and snoring) were assessed by an expanded version of the Brief Infant Sleep Questionnaire (BISQ-expanded). Information on four allergic diseases (wheeze, eczema, food allergy, and allergic rhinitis) in the past year was collected via standard questionnaire and judged by pediatricians. We used logistic regression to calculate odds ratios (ORs) and their 95% confidence intervals (CIs) for having any/and each of the four allergic diseases, based on sleep parameters, adjusting for children's age and gender, mode of delivery, any breastfeeding duration, children's body mass index (BMI), children's exposure to passive smoking, maternal education, family income, family allergic history, and children's antibiotic use.

RESULTS

There were 23.3% of children with at least one of the four allergic diseases. Snoring was significantly associated with increased odds of having any allergy (adjusted OR = 1.95; 95% CI: 1.17, 3.26), eczema (OR = 1.83, 95% CI: 1.03, 3.23) and food allergy (OR = 4.31, 95% CI: 1.23, 15.14), after adjustment for potential confounders. Nocturnal awaking ≥2 times per night was associated with higher risk of food allergy (OR = 3.92, 95% CI: 1.00, 15.35) and wheeze (OR = 6.16, 95% CI: 1.28, 29.74).

CONCLUSION

In this study, presence of certain sleep disorders was associated with higher risk of having allergic diseases in Chinese toddlers.

Leukotriene receptor antagonists in virus-induced wheezing : evidence to date

Virus-induced wheezing is a relatively benign entity that is usually transient in early childhood but is responsible for much health care utilization. The condition, seen traditionally as a subset of those children diagnosed as having frequent episodic asthma, is often treated with inhaled corticosteroids, despite their lack of efficacy. However, there remains some confusion differentiating atopic asthma from virus-induced wheezing in young children and their respective treatment strategies.The demonstration of cysteinyl leukotrienes in the nasopharyngeal secretions of infants and young children who wheeze prompted investigation of the role of leukotriene receptor antagonists in the treatment of virus-induced wheezing for young children with bronchiolitis and virus-induced wheezing.Montelukast, the only leukotriene receptor antagonist studied in young children, has been proven useful in increasing the number of symptom-free days and delaying the recurrence of wheeze in the month following a diagnosis of respiratory syncytial virus-induced wheezing in children aged 3-36 months. Subsequently, in children aged 2-5 years with frequent episodic asthma, primarily involving viral induced attacks in this age group, regular therapy with daily montelukast for 12 months reduced the rate of asthma exacerbations by 31% over placebo, delayed the time to the first exacerbation by 2 months, and lowered the need to prescribe inhaled corticosteroids as preventative therapy. Additionally, montelukast has been demonstrated to be efficacious as an acute episode modifier in children aged 2-14 years (85% children <6 years) with virus-induced wheezing where it was prescribed at the onset of a viral infection in children with an established pattern of viral induced episodes of wheeze in the preceding year. In this study, emergency department visits were reduced by 45%, visits to all health care practitioners were reduced by 23%, and time of preschool/school and parental time off work was reduced by 33% for children who took montelukast for a median of 10 days.At present, there is good evidence to support the use of bronchodilators in the acute treatment of virus- induced wheezing, and increasing evidence to support the use of leukotriene receptor antagonists, in particular montelukast, in the management of children with virus-induced wheezing.

The Use of Antiallergic and Antiasthmatic Drugs in Viral Infections of the Upper Respiratory Tract

Despite their frequency, upper respiratory tract infections (URTIs) constitute an area with few, if any, effective treatment remedies. Asthma and airway allergies share similar pathogenetic mechanisms to URTIs and it is not surprising, therefore, that agents used to treat allergic disorders have also been studied in URTIs. Their possible effects, limitations and hypothetical modes of action in URTIs are reviewed. In controlled clinical trials of satisfactory scientific standard, symptom reductions in both experimental rhinovirus infections and natural colds have occurred with topical anticholinergics, oral antihistamines and topical chromones. Future treatment alternatives for URTIs may include the intranasal anticholinergic ipratropium bromide, new nonsedating antihistamines and sodium cromoglycate (cromolyn sodium). The latter has a record of safety and an absence of adverse effects that would make it an attractive alternative for this common but not particularly serious condition in otherwise healthy individuals.

Virus infection-induced bronchial asthma exacerbation

Infection with respiratory viruses, including rhinoviruses, influenza virus, and respiratory syncytial virus, exacerbates asthma, which is associated with processes such as airway inflammation, airway hyperresponsiveness, and mucus hypersecretion. In patients with viral infections and with infection-induced asthma exacerbation, inflammatory mediators and substances, including interleukins (ILs), leukotrienes and histamine, have been identified in the airway secretions, serum, plasma, and urine. Viral infections induce an accumulation of inflammatory cells in the airway mucosa and submucosa, including neutrophils, lymphocytes and eosinophils. Viral infections also enhance the production of inflammatory mediators and substances in airway epithelial cells, mast cells, and other inflammatory cells, such as IL-1, IL-6, IL-8, GM-CSF, RANTES, histamine, and intercellular adhesion molecule-1. Viral infections affect the barrier function of the airway epithelial cells and vascular endothelial cells. Recent reports have demonstrated augmented viral production mediated by an impaired interferon response in the airway epithelial cells of asthma patients. Several drugs used for the treatment of bronchial asthma reduce viral and pro-inflammatory cytokine release from airway epithelial cells infected with viruses. Here, I review the literature on the pathogenesis of the viral infection-induced exacerbation of asthma and on the modulation of viral infection-induced airway inflammation.

Low level laser therapy (LLLT): attenuation of cholinergic hyperreactivity, beta(2)-adrenergic hyporesponsiveness and TNF-alpha mRNA expression in rat bronchi segments in E. coli lipopolysaccharide-induced airway inflammation by a NF-kappaB dependent mechanism

BACKGROUND AND OBJECTIVES

It is unknown if the decreased ability to relax airways smooth muscles in asthma and other inflammatory disorders, such as acute respiratory distress syndrome (ARDS), can be influenced by low level laser therapy (LLLT) irradiation. In this context, the present work was developed in order to investigate if LLLT could reduce dysfunction in inflamed bronchi smooth muscles (BSM) in rats.

STUDY DESIGN/MATERIALS AND METHODS

A controlled ex vivo study was developed where bronchi from Wistar rat were dissected and mounted in an organ bath apparatus with or without a TNF-alpha.

RESULTS

LLLT administered perpendicularly to a point in the middle of the dissected bronchi with a wavelength of 655 nm and a dose of 2.6 J/cm(2), partially decreased BSM hyperreactivity to cholinergic agonist, restored BSM relaxation to isoproterenol and reduced the TNF-alpha mRNA expression. An NF-kappaB antagonist (BMS205820) blocked the LLLT effect on dysfunction in inflamed BSM.

CONCLUSION

The results obtained in this work indicate that the LLLT effect on alterations in responsiveness of airway smooth muscles observed in TNF-alpha-induced experimental acute lung inflammation seems to be dependent of NF-kappaB activation.

Low level laser therapy partially restores trachea muscle relaxation response in rats with tumor necrosis factor alpha-mediated smooth airway muscle dysfunction

BACKGROUND AND OBJECTIVE

It is unknown if the decreased ability to relax airway smooth muscles in asthma and other inflammatory airways disorders can be influenced by low level laser therapy (LLLT) irradiation. To investigate if LLLT could reduce impairment in inflamed trachea smooth muscles (TSM) in rats.

STUDY DESIGN/MATERIALS AND METHODS

Controlled rat study where trachea was dissected and mounted in an organ bath apparatus with or without a TNF-alpha solution.

RESULTS

Low level laser therapy administered perpendicularly to a point in the middle of the dissected trachea with a wavelength of 655 nm and a dose of 2.6 J/cm(2), partially restored TSM relaxation response to isoproterenol. Tension reduction was 47.0 % (+/-2.85) in the laser-irradiated group compared to 22.0% (+/-2.21) in the control group (P < 0.01). Accumulation of cAMP was almost normalized after LLLT at 22.3 pmol/mg (+/-2.1) compared to 17.6 pmol/mg (+/-2.1) in the non-irradiated control group (P < 0.01).

CONCLUSION

Low level laser therapy partially restores the normal relaxation response in inflamed TSM and normalizes accumulation of cAMP in the presence of isoproterenol.

TNF-308 modifies the effect of second-hand smoke on respiratory illness-related school absences

RATIONALE

Exposure to second-hand smoke (SHS) has been associated with increased risk of respiratory illness in children including respiratory illness-related school absences. The role of genetic susceptibility in risk for adverse effects from SHS has not been extensively investigated in children.

OBJECTIVE

To determine whether the tumor necrosis factor (TNF) G-308A genotype influences the risk for respiratory illness-related school absences associated with SHS exposure.

METHODS

Incident school absences were collected, using an active surveillance system, between January and June 1996, as part of the Air Pollution and Absence Study, a prospective cohort study nested in the Children's Health Study. Buccal cells and absence reports were collected on 1,351 students from 27 elementary schools in California.

MEASUREMENTS AND MAIN RESULTS

Illness-related school absences were classified as nonrespiratory and respiratory illness-related, which were further categorized into upper or lower respiratory illness-related absences based on symptoms. The effect of SHS exposure on respiratory illness-related absences differed by TNF genotype (p interaction, 0.02). In children possessing at least one copy of the TNF-308 A variant, exposure to two or more household smokers was associated with a twofold risk of a school absence due to respiratory illness (relative risk, 2.13; 95% confidence interval, 1.34, 3.40) and a fourfold risk of lower respiratory illness-related school absence (relative risk, 4.15; 95% confidence interval, 2.57, 6.71) compared with unexposed children homozygous for the common TNF-308 G allele.

CONCLUSIONS

These results indicate that a subgroup of genetically susceptible children are at substantially greater risk of respiratory illness if exposed to SHS.

Rhinovirus and asthma

Rhinoviruses (RVs) cause the majority of common colds, which often provoke wheezing in patients with asthma. The precise mechanisms responsible for the RV infection-induced exacerbations of bronchial asthma are still uncertain. However, several reports reveal airway hyperresponsiveness, increases in chemical mediators in airway secretions such as kinin and histamine, and airway inflammation in patients with bronchial asthma after RV infection. RV infection induces an accumulation of inflammatory cells in airway mucosa and submucosa including neutrophils, lymphocytes and eosinophils. RV affects the barrier function of airway epithelial cells, and activates the airway epithelial cells and other cells in the lung to produce pro-inflammatory cytokines, including various kinds of interleukins, GM-CSF and RANTES, and histamine. RV also stimulates the expression of intercellular adhesion molecule-1 (ICAM-1) and low-density lipoprotein receptors in the airway epithelium, receptors for major and minor RVs. On the other hand, RV infection is inhibited by treatment with soluble ICAM-1, and by reduction of ICAM-1 expression in the airway epithelial cells after treatment with erythromycin. Both soluble ICAM-1 and erythromycin were reported to reduce the frequency of common colds. Here, we review the pathogenesis and management of RV infection-induced exacerbation of bronchial asthma.

Management of suspected acute viral upper respiratory tract infection in children with intranasal sodium cromoglicate: a randomised controlled trial

BACKGROUND

Upper respiratory tract infection in children is one of the most frequent reasons for visiting a family doctor, and antibiotics are often prescribed inappropriately. Sodium cromoglicate inhibits the ICAM-1 molecule, which is the receptor for human rhinoviruses. We aimed to investigate whether intranasal cromoglicate shortens duration of infection of the upper respiratory tract.

METHODS

We randomly assigned 290 children diagnosed with suspected acute viral upper respiratory tract infection by their family doctor (137 boys, 153 girls; mean age 5.2 years [SD 3.39]) either intranasal 4% sodium cromoglicate spray or intranasal normal saline spray. Follow-up was by daily symptom diary for 2 weeks and by telephone. Canadian Acute Respiratory Illness and Flu Scale (CARIFS) score was the primary outcome measure.

FINDINGS

195 patients returned symptom diaries, and 20 of these could not be included in the main analysis. 246 patients completed the telephone interview at week 1. There was no difference in recovery rate over the first week between the two groups, with the estimated difference in slope of log (CARIFS) being -0.01 (95% CI -0.05 to 0.03). There were no differences between the two groups in side-effects or re-consultation rates. 43 (17%) of 246 children with suspected acute viral upper respiratory tract infection went back to see their family doctor, and 220 (89%) of 246 were managed without prescription of antibiotics.

INTERPRETATION

Intranasal sodium cromoglicate is not a useful additional treatment for this infection. Our results further clarify the role of prescribed drugs for children with these frequent illnesses.

Issues and unmet needs in pediatric asthma

Asthma is common and becoming more so in childhood. Although mild asthma may incur low average annual costs per child, these estimates need to be viewed in the context of the very large numbers of affected individuals. Whereas asthma and wheezing illness in childhood had in the past been broadly subdivided into asthma (often associated with atopy) and wheezy bronchitis (wheeze only, with associated upper respiratory tract infection), this distinction was lost during the 1970s in view of the demonstrated underdiagnosis and undertreatment of symptomatic school-age children. The acceptance of asthma as a chronic inflammatory disease and evidence for airway remodeling and progressive deterioration in airway function in association with symptoms and atopy have led to earlier use of topical steroids at higher starting doses delivered by improved age-appropriate devices. Treating all children as if they were destined to become atopic asthmatics and at risk of airway remodeling may not be rational, particularly in those whose symptoms will subsequently resolve. However, there are as yet no screening tests which can clearly identify individuals at risk of long-term chronic airway inflammation and airway remodeling. The large number of infants and young children with current symptoms suggestive of asthma and in whom resolution is likely in the majority poses problems for the clinician in deciding the best initial therapy. There is an urgent need to develop simple and reliable measures that can identify the early manifestations of atopic airway sensitisation and to establish the place of early intervention with nonsteroidal drugs, including leukotriene antigonists.

The role of respiratory viruses in acute and chronic asthma

Respiratory infections can have dual effects related to asthma. First, there is increasing evidence that severe infections with RSV and PIV in infancy can alter lung development and physiology to increase the risks of subsequent wheezing and asthma. Second, infections with common cold viruses and influenza commonly precipitate wheezing symptoms in children and adults who already have established asthma, and RV appears to be the most important virus in producing exacerbations of the disease. The principal mechanisms by which this occurs appears to be viral replication in epithelial cells, triggering a cascade of inflammation involving granulocytes, macrophages, T cells, and secreted cytokines and mediators. The inflammatory process, although essential to clear the infection, augments pre-existing airway inflammation in asthma, leading to increased airway obstruction and lower respiratory tract symptoms. Greater understanding of virus-induced changes in inflammation and corresponding changes in airway physiology may lead to new therapeutic approaches to the treatment and prevention of virus-induced airway dysfunction.

Corticosteroid-sparing options in the treatment of childhood asthma

During the last 30 years, a significant rise in wheezing illness has occurred in the child population. Despite its high prevalence there is no clear definition of the disease, which includes a heterogeneous group of syndromes ranging from transient wheezing in infancy to atopic asthma with persistence into adult life. Molecular advances and further epidemiological information from well characterised individuals and their families are likely to clarify the different subtypes of wheezing illness and inform therapeutic options. With the recognition that chronic airway inflammation is a feature of persistent disease, at least in adults, there has been a trend towards the early introduction of anti-inflammatory treatment and particularly inhaled corticosteroids (ICS). However, the natural resolution of much wheezing illness, particularly in young children and in children with viral-induced episodes, suggests that newly presenting children should remain on symptomatic therapy alone while the severity of the disease is being assessed. Although ICS have become a cornerstone of management of chronic persistent disease, their ability to protect against exacerbations in young and mildly affected children is questionable. Alongside concerns about long term use of ICS and possible systemic adverse effects, there remains a need for alternative approaches to the control of the disease in children. Extrapolation of the findings of large multicentre adult studies into childhood, particularly for doubling the doses of ICS and long-acting beta2-agonists, may be unsound. Other approaches include the early introduction of inhaled cromones, use of second generation antihistamines, low dose theophyllines and, more recently, leukotriene modifiers. As the majority of preschool children will become asymptomatic by mid-childhood, there is an urgent need to identify those in whom chronic airway inflammation is developing, as it is in this group that early introduction of ICS may be of maximum benefit. In the remainder, other approaches, including use of corticosteroid-sparing longacting P2-agonists and leukotriene modifying drugs, may be more appropriate. Safe and effective oral preparations such as leukotriene modifying drugs are likely to establish a significant role in the management of symptoms in children of all ages and with all types of asthma and wheezing illness.

Association of rhinovirus infections with asthma

Rhinoviruses are the most common cause of the common cold, but they can cause more severe illnesses in people with underlying lung disorders such as asthma, chronic obstructive pulmonary disease, or cystic fibrosis. Epidemiologic studies with sensitive detection methods such as PCR have identified rhinovirus infection as a major source of asthma exacerbations in both children and adults, especially during the spring and fall. Since rhinoviruses cause little tissue destruction, it is presumed that the immune response to the infection may play an important role in the pathogenesis of rhinovirus-induced exacerbations of asthma. This review examines the epidemiologic association between rhinovirus infections and exacerbations of asthma and outlines current information on immune responses to rhinovirus infection and potential connections between antiviral responses and preexisting allergic inflammation. Finally, current and future strategies for treating rhinovirus infections and virus-induced exacerbations of asthma are discussed.

The effect of inhaled and intranasal sodium cromoglycate on symptoms of upper respiratory tract infections

Background A well established drug for the treatment of asthma and allergy, sodium cromoglycale, was found in open trials to be useful as a symptomalic treatment for upper respiratory tract infections.

Objective To compare the efficacy of inhaled and intranasal sodium cromoglyeate and matching placebos on the symptoms of upper respiratory tract infections.

Methods Adult subjects with symptoms of runny nose, throat pain, or cough for less than 24 h were recruited. They were treated for 7 days using a randomized, double‐blind, placebo‐controlled, group comparative design. The medication given was: sodium cromoglyeate dry powder 20mg per inhalation in spincaps; sodium cromoglycate aqueous nasal spray delivering 5.2mg per dose; or matching placebo as dry powder and nasal spray. One spincap and one spray per nostril were taken every 2h during waking hours on days 1 and 2 and then four times daily on days 3–7. Severity of nine symptoms (general malaise, body aches and pains, chills and shivering, snzeening, nasal running, nasal blocking, sore throat, cough and voice disturbance) was recorded twice daily by subjects on diary cards, using a scale of 0 (absent) to 3 (severe).

Results The sludy was conducted between February and April 1993. One hundred and eighteen patients aged 21–63 years (mean 41 years) were included. Symptoms resolved faster (P < 0.001) and the severity in the last three days of treatment was significantly less in patients treated with sodium cromoglycate than with placebo (P < 0.05‐day 5; P < 0.01‐day 6; P < 0.001‐day 7). Side‐effects were local and mild and did not differ between the treatment groups.

Conclusion Sodium cromoglyeate administered both by inhalation and intranasally is an effective treatment for the symptoms of upper respiratory tract infection. Its combined safety and efficacy would make it an acceptable form of treatment for these conditions.