Community study of role of viral infections in exacerbations of asthma in 9-11 year old children

Targeting the NF-kappaB pathway in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease are inflammatory lung disorders responsible for significant morbidity and mortality worldwide. While the importance of allergic responses in asthma is well known, respiratory viral and bacterial infections and pollutants especially cigarette smoke are important factors in the pathogenesis of both diseases. Corticosteroid treatment remains the first preference of treatment in either disease, however these therapies are not always completely effective, and are associated with side effects and steroid resistance. Due to such limitations, development of new treatments represents a major goal for both the pharmaceutical industry and academic researchers. There are now excellent reasons to promote NF-kappaB signalling intermediates and Rel family proteins as potential therapeutic targets for both asthma and chronic obstructive pulmonary disease. This notion is supported by the fact that much of the underlying inflammation of both diseases independent of stimuli, is mediated at least in part, by NF-kappaB mediated signalling events in several cell types. Also, a range of inhibitors of NF-kappaB signalling intermediates are now available, including DNA oligonucleotides and DNA-peptide molecules that act as NF-kappaB decoy sequences, small molecule inhibitors such as IKK-beta inhibitors, and proteasome inhibitors affecting NF-kappaB signalling, that have either shown promise in animal models or have begun clinical trials in other disorders. This review will focus on the role of NF-kappaB in both diseases, will discuss its suitability as a target, and will highlight recent key studies that support the potential of NF-kappaB as a therapeutic target in these two important inflammatory lung diseases.

Targeting eosinophils in asthma

Recruitment of eosinophils has long been recognized as a hallmark of the inflammatory response in asthma. However, the functions of this population of cells in host defense remain poorly understood. Eosinophils play an important part in the inflammatory response and have key regulatory roles in the afferent arm of the immune response. More recently, eosinophils have been demonstrated to participate in host defense against respiratory viruses. The specific contributions of eosinophils to the pathophysiology of asthma remain controversial. However, the balance of evidence indicates that they have a significant role in the disease, suggesting that they may be appropriate targets for therapy. Towards this end, a novel intervention of considerable potential interest is the use of an antibody directed against the beta common chain of the receptor for interleukin-3, interleukin-5 and granulocyte-macrophage colony-stimulating factor. However, eliminating eosinophils may not be a risk-free therapeutic strategy, as there is potentially an increased likelihood of respiratory viral infections. This may predispose to the development of acute exacerbations of asthma, an outcome that would have significant clinical implications.

Respiratory syncytial virus persistence in chronic obstructive pulmonary disease

Respiratory syncytial virus (RSV) is predominantly recognized as a pediatric pathogen although sensitive molecular diagnostic techniques have led to its more frequent detection in some adult settings. In some studies RSV has been detected just as frequently in stable chronic obstructive pulmonary disease (COPD) patients as in those suffering disease exacerbations, leading to the suggestion that RSV may persist in COPD. Although some studies have found negligible RSV in stable COPD, others have detected RSV in one-quarter to one-third of stable COPD samples. Possible reasons for this discrepancy are explored within the article. A relationship between RSV detection and increased disease severity, including rate of decline in lung function and systemic/airway inflammation, has been found on both occasions it has been sought. Susceptibility to persistent RSV infection could involve both host and viral factors. Cigarette smoking and COPD are likely to result in impaired antiviral immunity, and RSV is capable of evading immune responses by inducing skewed type 2 T-helper cell responses, antagonizing antiviral cytokines, mimicking chemokines, inhibiting apoptosis, and entering immune-privileged cells such as pulmonary neurons. It can also escape an established immune response through antigenic drift. This article examines current evidence regarding persistence of RSV in COPD and its possible mechanisms. We also discuss various roles for RSV persistence in COPD pathogenesis. Further elucidation of the contribution of persistent RSV to the pathogenesis of COPD requires interventional studies. Persistence of RSV in COPD may have direct relevance to the pathogenesis of childhood diseases such as postbronchiolitic wheeze and asthma.

Viral respiratory infection and the link to asthma

Viral respiratory infections are closely associated with wheezing illnesses and exacerbations of asthma throughout childhood, and yet there are a number of remaining questions pertaining to the specific nature of this relationship. Infection with an expanding list of respiratory viruses is an important cause of acute wheezing in infancy, and viruses are detected in most exacerbations of asthma throughout childhood. Furthermore, infants who develop severe viral respiratory infections are more likely to have asthma later in childhood. There has been progress in understanding the pathogenesis of viral respiratory illnesses, and this has led to new insights into how these processes might differ in asthma. Several host factors, including respiratory allergy and virus-induced interferon responses, modify the risk of virus-induced wheezing. In the absence of effective antiviral therapies, treatment of virus-induced wheezing and exacerbations of asthma can be challenging, and studies evaluating current treatment strategies are reviewed. Understanding the host-pathogen interactions that determine the severity of respiratory illnesses and long-term sequelae is likely to be of great help in identifying at-risk individuals, and in designing new and more effective treatments.

Rhinovirus infection and house dust mite exposure synergize in inducing bronchial epithelial cell interleukin-8 release

BACKGROUND

Human rhinoviruses (HRVs) and house dust mites (HDMs) are among the most common environmental factors able to induce airway inflammation in asthma. Although epidemiological studies suggest that they also synergize in inducing asthma exacerbations, there is no experimental evidence to support this, nor any information on the possible mechanisms involved.

OBJECTIVE

To investigate their interaction on the induction of airway epithelial inflammatory responses in vitro.

METHODS

BEAS-2B cells were exposed to activated HDM Dermatophagoides pteronyssinus major allergen I (Der p I), HRVs (HRV1b or HRV16) or both in different sequences. IL-8/CXCL8 release, intercellular adhesion molecule (ICAM)-1 surface expression and nuclear factor kappaB (NF-kappaB) translocation were evaluated. Complementary, primary human bronchial epithelial cells (HBECs) exposed to both Der p I and RVs and IL-8, IL-6, IFN-gamma-induced protein (IP)-10/CXCL10, IFN-lambda1/IL-29, regulated upon activation normal T lymphocyte expressed and secreted (RANTES)/CCL5 release were measured.

RESULTS

RV and Der p I up-regulated IL-8 release, ICAM-1 expression and NF-kappaB translocation in BEAS-2B cells. Simultaneous exposure to both factors, as well as when cells were initially exposed to HRV and then to Der p I, resulted in further induction of IL-8 in a synergistic manner. Synergism was not observed when cells were initially exposed to Der p I and then to HRV. This was the pattern in ICAM-1 induction although the phenomenon was not synergistic. Concurrent exposure induced an early synergistic NF-kappaB translocation induction, differentiating with time, partly explaining the above observation. In HBECs, both HRV and Der p I induced IL-8, IL-6, IL-29 and IP-10, while RANTES was induced only by HRV. Synergistic induction was observed only in IL-8.

CONCLUSION

HRV and enzymatically active Der p I can act synergistically in the induction of bronchial epithelial IL-8 release, when HRV infection precedes or is concurrent with Der p I exposure. Such a synergy may represent an important mechanism in virus-induced asthma exacerbations.

Lycopene enrichment of cultured airway epithelial cells decreases the inflammation induced by rhinovirus infection and lipopolysaccharide

Rhinovirus infection results in increased release of inflammatory mediators from airway epithelial cells in asthma. As an antioxidant, lycopene offers protection from adverse effects of inflammation. The aim of this study was to find an appropriate method of lycopene enrichment of airway epithelial cells and to determine the effects of lycopene enrichment on the inflammatory response of cells infected by rhinovirus or exposed to lipopolysaccharide. Lycopene enrichment of airway epithelial cells using solubilisation in tetrahydrofuran versus incorporation in liposomes was compared. After determining that solubilisation of lycopene in tetrahydrofuran was the most suitable method of lycopene supplementation, airway epithelial cells (Calu-3) were incubated with lycopene (dissolved in tetrahydrofuran) for 24 h, followed by rhinovirus infection or lipopolysaccharide exposure for 48 h. The release of interleukin-6, interleukin-8 and interferon-gamma induced protein-10 (IP-10) and their messenger RNA levels were measured using enzyme linked immunosorbent assay and reverse transcription polymerase chain reaction, respectively. Viral replication was measured by tissue culture infective dose of 50% assay. Lycopene concentration of cells and media were analysed using high-performance liquid chromatography. Preincubation of airway epithelial cells with lycopene (dissolved in tetrahydrofuran) delivered lycopene into the cells and resulted in a 24% reduction in interleukin-6 after rhinovirus-1B infection, 31% reduction in IP-10 after rhinovirus-43 infection and 85% reduction in rhinovirus-1B replication. Lycopene also decreased the release of IL-6 and IP-10 following exposure to lipopolysaccharide. We conclude that lycopene has a potential role in suppressing rhinovirus induced airway inflammation.

Influenza vaccination among Canadians with chronic respiratory disease

BACKGROUND

The purposes of this study were to estimate the prevalence of recent influenza vaccination, to identify sociodemographic risk factors and reasons for non-vaccination, and to examine the association between influenza vaccination and respiratory medication use, among individuals with asthma and COPD in Canada.

METHODS

Data from the 2003 Statistics Canada Canadian Community Health Survey (n=134,072, age 12-80+ years) were analyzed. All data were based on self-report.

RESULTS

An estimated 36.3% and 47.9% of individuals with asthma and COPD, respectively, were immunized for influenza within the last year in 2003. These vaccination rates were relatively lower than those seen with other non-respiratory health conditions. Respondents thinking that influenza vaccination was not necessary was the most frequent reason cited for non-vaccination among individuals with asthma and COPD. Men, non-Ontarians, younger age groups, current smokers, and those without a family doctor were less likely to be vaccinated among individuals with asthma and COPD. After controlling for potential sociodemographic confounders, among individuals with asthma, those vaccinated for influenza had significantly greater odds of using inhalers/nebulizers (OR=1.8, 95% CI=1.3-2.4). No other significant medication use associations were observed among individuals with asthma and COPD.

CONCLUSIONS

Recent self-reported influenza vaccination rates among individuals with asthma and COPD were relatively low. Influenza vaccination was not associated with decreased respiratory medication use among individuals with asthma and COPD, suggesting that vaccination may not help prevent exacerbations. More research is needed to fully clarify the role of influenza vaccination in chronic respiratory disease, particularly asthma, to justify policies of mass-immunization.

Atypical bacteria and macrolides in asthma

: Chlamydophila pneumoniae and Mycoplasma pneumoniae are common pathogens causing acute illness in both the upper and lower airways. Several observations are supportive of a possible causative role of these pathogens in asthma; however, more evidence is required before this becomes meaningful in clinical practice. Atypical bacteria can enhance airway hyperresponsiveness and inflammation, both of which have been associated with exacerbations in patients with preexisting asthma. It is less clear whether the above mechanisms might also be responsible for the development of asthma. Difficulties in accurately diagnosing these infections contribute to such uncertainty. In the present report, evidence of the involvement of Chlamydophila and Mycoplasma infection in the development and the progression of asthma are reviewed.

Evidence of a causal role of winter virus infection during infancy in early childhood asthma

RATIONALE

Bronchiolitis during infancy is associated with an increased risk of childhood asthma. Whether winter viral infections cause asthma or are a manifestation of a predisposition to asthma development is unknown.

OBJECTIVES

To study the relationship of winter virus infection during infancy and the development of childhood asthma.

METHODS

We studied over 95,000 infants born between 1995 and 2000 and followed through 2005 who were enrolled in the Tennessee Medicaid program from birth through early childhood to determine whether infant birth in relationship to the winter virus peak alters the risk of developing early childhood asthma.

MEASUREMENTS AND MAIN RESULTS

Among 95,310 children studied during five winter virus seasons from birth through early childhood, the risk of developing asthma tracked with the timing of infant birth in relationship to the winter virus peak. Infant birth approximately 4 months before the winter virus peak carried the highest risk, with a 29% increase in odds of developing asthma compared with birth 12 months before the peak (adjusted odds ratio, 1.29; 95% confidence interval, 1.19-1.40). Infant age at the winter virus peak was comparable to or greater than other known risk factors for asthma.

CONCLUSIONS

Timing of birth in relationship to winter virus season confers a differential and definable risk of developing early childhood asthma, establishing winter virus seasonality as a causal factor in asthma development. Delay of exposure or prevention of winter viral infection during early infancy could prevent asthma.

Rhinovirus-induced lower respiratory illness is increased in asthma and related to virus load and Th1/2 cytokine and IL-10 production

Acute exacerbations are the major cause of asthma morbidity, mortality, and health-care costs and are difficult to treat and prevent. The majority of asthma exacerbations are associated with rhinovirus (RV) infection, but evidence supporting a causal relationship is weak and mechanisms are poorly understood. We hypothesized that in asthmatic, but not normal, subjects RV infection would induce clinical, physiologic, and pathologic lower airway responses typical of an asthma exacerbation and that these changes would be related to virus replication and impaired T helper 1 (Th1)/IL-10 or augmented Th2 immune responses. We investigated physiologic, virologic, and immunopathologic responses to experimental RV infection in blood, induced sputum, and bronchial lavage in 10 asthmatic and 15 normal volunteers. RV infection induced significantly greater lower respiratory symptoms and lung function impairment and increases in bronchial hyperreactivity and eosinophilic lower airway inflammation in asthmatic compared with normal subjects. In asthmatic, but not normal, subjects virus load was significantly related to lower respiratory symptoms, bronchial hyperreactivity, and reductions in blood total and CD8(+) lymphocytes; lung function impairment was significantly related to neutrophilic and eosinophilic lower airway inflammation. The same virologic and clinical outcomes were strongly related to deficient IFN-gamma and IL-10 responses and to augmented IL-4, IL-5, and IL-13 responses. This study demonstrates increased RV-induced clinical illness severity in asthmatic compared with normal subjects, provides evidence of strong relationships between virus load, lower airway virus-induced inflammation and asthma exacerbation severity, and indicates augmented Th2 or impaired Th1 or IL-10 immunity are likely important mechanisms.

The role of infection in asthma

This paper reviews the impact of infections on the onset and clinical course of bronchial asthma. A just emphasis is given to the role viral infections, particularly rhinovirus infections, play in exacerbations, and that played by respiratory syncytial virus, suspected of triggering the asthmatic syndrome. The mechanisms of the immune response to virus attacks are explained, highlighting the asthmatic and allergic patient's weakened response, particularly in the perinatal period. Further stressed is a potentiating effect of viral aggression on the allergic response. The hygiene hypothesis and its lack of scientific consistency is detailed, at least as far as the role it seeks to confer on an unproven antagonism of the Th1 and Th2 lymphocyte responses. The current importance of research not into bacteria, but into bacterial products, including endotoxins, on the modulation of asthma and allergy is noted. Studies which, along these lines, show an environmental impact on genetic secretion in the phenotype are underlined. Also discussed in passing are several mechanisms which go towards explaining neutrophilic asthma - for many a contradiction, given eosinophilia's stranglehold on asthmatic inflammation.

Filaggrin null mutations are associated with increased asthma exacerbations in children and young adults

BACKGROUND

Filaggrin (FLG) null mutations are important genetic predisposing factors for atopic asthma and have recently been shown to influence controller and reliever medication needs in asthmatic children. Our objective was to study the role of FLG null alleles in asthma exacerbations.

METHODS

FLG mutations R501X and 2282del4 were assayed in 1135 individuals ranging from 3 to 22 years old with asthma from Tayside and Dumfries, Scotland. Asthma exacerbations over the previous 6 months were also studied.

RESULTS

The FLG mutations were significantly associated with greater risk of exacerbations in children with asthma. Exacerbations were significant for the R501X but not the 2282del4 mutation and the combined genotype compared to the wild-type with odds ratios of 1.97 (95% CI, 1.19-3.22; P = 0.009) and 1.61 (95% CI, 1.08-2.40; P = 0.021), respectively. Individuals with FLG null alleles were more likely to require oral steroids (31.4%vs 19.5%; OR = 1.89; P = 0.021) for their exacerbations. There was also a 1.71-fold increased risk (42.6%vs 30%; P = 0.041) of school absence owing to asthma exacerbations in asthmatic individuals with FLG null mutation. On sub-group analysis, the effect of FLG mutations on asthma exacerbations is significant (P = 0.045) only for participants with relatively mild asthma controlled on inhaled steroids, with inhaled albuterol according to need.

CONCLUSION

In addition to their effect on asthma medication requirements reported previously, there is an association between the presence of FLG null mutations and the risk of asthma exacerbations in asthmatic children and young adults.

Infecção na modulaçâo da asma11Trabalho apresentado no XXIII Congresso de Pneumologia da SPP – Guarda, Novembro 2007 / Paper presented at the XXIII Congresso de Pneumologia da SPP / PSP Pulmonology Congress, Guarda, November 2007

Faz-se uma revisão da influência das infecções no aparecimento e na clínica da asma brônquica. Dá-se o relevo que merece à intervenção virusal, sobretudo ao rinovírus, pela sua influência nas exacerbações, e ao vírus sincicial respiratório, sobre o qual recai a suspeita de poder ser causa determinante no aparecimento da síndroma asmática. Tentam-se esclarecer os mecanismos da resposta imune à agressão virusal em função das debilidades da resposta do asmático e do atópico, sobretudo no período perinatal, salientando-se, ainda, um efeito de potenciação da agressão virusal sobre a resposta atópica. Aborda-se a hipótese higiénica e a sua falta de consistência científica, pelo menos no papel que pretende atribuir a um não demonstrado antagonismo das respostas linfocitárias Th₁ e Th_2, apontando-se a importância actual da investigação, não das bactérias mas dos produtos bacterianos, como as endotoxinas, na modulação da asma e da atopia, dando-se relevo aos estudos que, a partir deste modelo, demonstram uma influência do ambiente na secreção génica e, consequentemente, no fenótipo. Invocam-se, nas entrelinhas, vários mecanismos que podem explicar a asma neutrofílica que, para muitos, é um paradoxo perante o consagrado domínio do eosinófilo na inflamação asmática.

Rev Port Pneumol 2008; XIV (5): 647-675

High prevalence and young onset of allergic rhinitis in children with bronchial asthma

Bronchial asthma and allergic rhinitis often co-exist, and rhinitis is a major risk factor for the development of asthma. However, the reported incidence of allergic rhinitis in asthmatic children varies widely. The aim of this study was to elucidate the incidence of allergic rhinitis, the onset age of chronic upper and lower airway symptoms, and the correlation of these two symptoms in asthmatic children. A cohort of 130 consecutive children (ages 2-10) with asthma was evaluated. A questionnaire regarding upper and lower airway symptoms was filled out by the parents. Objective diagnosis of allergic rhinitis was also made on the basis of rhinoscopy, nasal cytology, nasal challenge, and specific serum IgE (CAP-RAST). Persistent nasal symptoms were present in 83.8% of the asthmatic children. The incidence of allergic rhinitis was 77.7% based on the objective findings. The mean onset age of asthma was 2.8 yr, and that of rhinitis was 2.9 yr. Nasal symptoms started as early as the first year of life in 8.9% of the children. In children with comorbid asthma and allergic rhinitis, rhinitis preceded in 33.7%, asthma preceded in 31.7%, and both started in the same year in 26.7%. In 7.9%, rhinitis was asymptomatic. Concomitant exacerbation of the upper and lower airways occurred in 34.6% of the total 130 children. These results demonstrate that allergic rhinitis manifested early in life in the majority of the asthmatic children. Persistent nasal symptoms in infancy may point to subsequent development of asthma and possible early intervention.

Molecular and cellular mechanisms in the viral exacerbation of asthma

The aetiology of asthma associated with viral infection is complex. The dynamics that contribute to disease pathogenesis are multifactorial and involve overlapping molecular and cellular mechanisms, particularly the immune response to respiratory virus infection or allergen sensitization. This review summarizes the evidence associated with factors that may contribute to the development or exacerbation of asthma including age, host factors, genetic polymorphisms, altered immune responses, and aspects of viral antigen expression. This review also provides an important perspective of key events linked to the development of asthmatic disease and related pulmonary inflammation from human and animal studies, and discusses their relationship as targets for disease intervention strategies.

Human rhinoviruses: the cold wars resume

BACKGROUND

Human rhinoviruses (HRVs) are the most common cause of viral illness worldwide but today, less than half the strains have been sequenced and only a handful examined structurally. This viral super-group, known for decades, has still to face the full force of a molecular biology onslaught. However, newly identified viruses (NIVs) including human metapneumovirus and bocavirus and emergent viruses including SARS-CoV have already been exhaustively scrutinized. The clinical impact of most respiratory NIVs is attributable to one or two major strains but there are 100+ distinct HRVs and, because we have never sought them independently, we must arbitrarily divide the literature's clinical impact findings among them. Early findings from infection studies and use of inefficient detection methods have shaped the way we think of 'common cold' viruses today.

OBJECTIVES

To review past HRV-related studies in order to put recent HRV discoveries into context.

RESULTS

HRV infections result in undue antibiotic prescriptions, sizable healthcare-related expenditure and exacerbation of expiratory wheezing associated with hospital admission.

CONCLUSION

The finding of many divergent and previously unrecognized HRV strains has drawn attention and resources back to the most widespread and frequent infectious agent of humans; providing us the chance to seize the advantage in a decades-long cold war.

The impact of respiratory viral infection on wheezing illnesses and asthma exacerbations

The etiology and morbidity associated with asthma are thought to stem from both genetic factors and potentially modifiable environmental factors, such as viral infections. Although it is unclear whether respiratory viral infections cause asthma, observational studies have demonstrated a high rate of asthma in children with a history of severe viral lower respiratory tract infections during infancy, and viruses are associated with the majority of asthma exacerbations among both children and adults. This article discusses the pathogens associated with virus-induced wheezing illnesses during infancy and early childhood, the association of bronchiolitis during infancy with an increased risk of childhood asthma, and the association of respiratory viruses with asthma exacerbations in older children and adults.

Wheezing due to rhinovirus infection in infancy: Bronchial hyperresponsiveness at school age

BACKGROUND

Characteristics related to decreased lung function and increased bronchial responsiveness after early childhood wheezing requiring hospitalization are not fully established.

METHODS

Seventy-nine children with wheezing requiring hospitalization at age <2 years were prospectively followed up and re-investigated at age 5.6-8.8 years when the measurements of baseline lung function and bronchial responsiveness to exercise were performed.

RESULTS

At early school age, 23% of children had decreased lung function, and 13% had increased bronchial responsiveness to exercise. Predictors of decreased lung function were maternal history of smoking during pregnancy (odds ratio [OR], 12.8; 95% confidence interval [CI]: 1.2-139.6), parental history of asthma (OR, 4.3; 95%CI: 1.1-17.1), and female gender (OR, 4.0; 95%CI: 1.2-13.7). Increased bronchial responsiveness was associated with rhinovirus infection-induced wheezing in infancy (OR, 6.5; 95%CI: 1.2-36.3), and early cat or dog exposure leading to sensitization (OR, 26.6; 95%CI: 1.3-525.2). Inhaled anti-inflammatory therapy was common in children with rhinovirus infection-induced wheezing in infancy (n = 13/19; P = 0.001 vs children with other/no confirmed virus infection etiology for wheezing in infancy, n = 16/60), which may have improved lung function and attenuated bronchial responsiveness in them.

CONCLUSIONS

After early childhood wheezing requiring hospitalization, one-fourth of children will have decreased lung function and one-eighth of children will show increased bronchial responsiveness at school age. Gender, heredity of asthma, and antenatal exposure to tobacco smoke are predictors of decreased lung function, whereas rhinovirus infection etiology of wheeze and early animal exposure leading to sensitization are associated with increased bronchial responsiveness later in childhood.

Anti-inflammatory effects of long-chain n-3 PUFA in rhinovirus-infected cultured airway epithelial cells

Long-chain n-3 PUFA (LCn-3PUFA) including DHA and EPA, are known to decrease inflammation by inhibiting arachidonic acid (AA) metabolism to eicosanoids, decreasing the production of pro-inflammatory cytokines and reducing immune cell function. The aim of this study was to determine if EPA and DHA reduced the release of inflammatory mediators from airway epithelial cells infected with rhinovirus (RV). Airway epithelial cells (Calu-3) were incubated with EPA, DHA and AA for 24 h, followed by rhinovirus infection for 48 h. IL-6, IL-8 and interferon-γ-induced protein-10 (IP-10) released by cells were measured using ELISA. Viral replication was measured by serial titration assays. The fatty acid content of cells was analysed using GC. Cellular viability was determined by visual inspection of cells and lactate dehydrogenase release. DHA (400 μm) resulted in a significant 16 % reduction in IL-6 release after RV-43 infection, 29 % reduction in IL-6 release after RV-1B infection, 28 % reduction in IP-10 release after RV-43 infection and 23 % reduction in IP-10 release after RV-1B infection. Cellular DHA content negatively correlated with IL-6 and IP-10 release. None of the fatty acids significantly modified rhinovirus replication. DHA supplementation resulted in increased cellular content of DHA at the cost of AA, which may explain the decreased inflammatory response of cells. EPA and AA did not change the release of inflammatory biomarkers significantly. It is concluded that DHA has a potential role in suppressing RV-induced airway inflammation.

Clinical assessment of asthma progression in children and adults

Asthma is a heterogeneous disorder with a variable course, characterized by episodes of cough, wheezing and shortness of breath, reversible airflow limitation, and bronchial hyperresponsiveness. It begins early in life in many subjects with intermittent symptoms occurring with viral respiratory tract infections. Over time, and in genetically susceptible children (those with an atopic predisposition), the disease becomes more persistent with symptoms occurring in the absence of respiratory tract infections. Children with persistent wheezing are eventually diagnosed with asthma, with those at greatest risk having developed allergic sensitization early in life. Among children with asthma, some will have lifelong asthma with active symptoms and progressive loss of lung function over time, whereas other children will undergo asthma remission in adolescence. Once in remission, the disease may remain quiescent, or it may relapse in midadult life. This review focuses on studies that have enhanced our understanding of the progression of asthma from infancy to adulthood. Studies evaluating progressive loss of lung function, the best-studied measure of asthma progression, are also reviewed, followed by a brief discussion of whether asthma progression can be modified by inhaled glucocorticoid therapy.

Virus-induced eosinophil mediator release requires antigen-presenting and CD4+ T cells

BACKGROUND

The most frequent trigger of asthma exacerbation is infection with common airway viruses; however, the precise mechanism regulating such severe reactions is not understood. The presence of airway eosinophil products is a unique feature detected in asthmatic airways. Using an animal model, we previously demonstrated that T cells play an important role in regulating an eosinophil-dependant pathway of virus-induced airway hyperreactivity. We hypothesize that human eosinophils respond to viruses, although only after interaction with T cells.

OBJECTIVES

We sought to determine whether eosinophils can respond to airway viruses in vitro and determine the mechanism of response.

METHODS

An in vitro coculture model of human eosinophils, antigen-presenting cells, and T cells was used with parainfluenza virus, respiratory syncytial virus, or rhinovirus. We measured release of eosinophil peroxidase (EPO) in concert with T-cell proliferation, cytokine release, and changes in T-cell phenotype.

RESULTS

The viruses induced release of EPO when coincubated in the presence of antigen-presenting cells (dendritic cells or macrophages) and T cells. Virus-mediated release was associated with proliferation of CD3(+)CD4(+) T cells and release of cytokines. UV inactivation of the virus did not prevent virus-induced EPO release or T-cell proliferation. Proliferating CD4(+) T cells show increased expression of CD25 and CD45RO. CD8(+) T cells were not activated.

CONCLUSION

Virus-induced EPO release can occur in the context of antigen presentation to CD4(+) T cells.

Role of human metapneumovirus, human coronavirus NL63 and human bocavirus in infants and young children with acute wheezing

The role of the novel respiratory viruses, human metapneumovirus (hMPV), human coronavirus NL63 (HCoV NL63) and human bocavirus (HBoV), in wheezing illness in children has not been well studied, especially in Africa. The aim of this study was to investigate the prevalence of hMPV, HCoV NL63 and HBoV in South African children with acute wheezing. A prospective study of consecutive children presenting with acute wheezing to a pediatric hospital from May 2004 to November 2005 was undertaken. A nasal swab was taken for reverse transcription-polymerase chain reaction (RT-PCR) and PCR for hMPV, HCoV NL63 and HBoV; when positive, the genes were sequenced. Shell vial culture for RSV, influenza A and B viruses, adenovirus and parainfluenza viruses 1, 2, 3 was performed on every 5th sample. Two hundred and forty two nasal swabs were collected from 238 children (median age 12.4 months). A novel respiratory virus was found in 44/242 (18.2%). hMPV, HBoV, and HCoV NL63 was found in 20 (8.3%), 18 (7.4%), and 6 (2.4%) of samples, respectively. Fifteen of 59 (25%) samples were positive for other respiratory viruses. Viral co-infections, occurred in 6/242 (2.5%). Phylogenetic analysis showed co-circulation of hMPV and HCoV NL63 A and B lineages, although only HBoV genotype st2 was found. Viruses are an important cause of wheezing in preschool children; hMPV, HCoV NL63, and HBoV are less common than the usual respiratory pathogens.

Vaccines for preventing influenza in people with asthma

BACKGROUND

Influenza vaccination is recommended for asthmatic patients in many countries as observational studies have shown that influenza infection can be associated with asthma exacerbations, but influenza vaccination itself has the potential to adversely affect pulmonary function. A recent overview concluded that there was no clear benefit of influenza vaccination in patients with asthma but this conclusion was not based on a systematic search of the literature.

OBJECTIVES

Whilst influenza may cause asthma exacerbations, there is controversy about the use of influenza vaccinations, since they may precipitate an asthma attack in some people. The objective of this review was to assess the efficacy of influenza vaccination in children and adults with asthma.

SEARCH STRATEGY

We searched the Cochrane Airways Group trials register and checked reference lists of articles. The last search was carried out in September 2007.

SELECTION CRITERIA

Randomised trials of influenza vaccination in children (over two years of age) and adults with asthma. Studies involving people with chronic obstructive pulmonary disease were excluded.

DATA COLLECTION AND ANALYSIS

Inclusion criteria and assessment of trial quality were applied by two reviewers independently. Data extraction was done by two reviewers independently. Study authors were contacted for missing information.

MAIN RESULTS

Nine trials were initially included. Four of these trials were of high quality. Six further articles have been included in three updates (Bueving 2003; Castro 2001; Fleming 2006; Redding 2002; Reid 1998). The included studies covered a wide diversity of people, settings and types of influenza vaccination, but data from the more recent studies that used similar vaccines have been pooled.

BENEFITS

Bueving 2003 studied 696 children with asthma and did not demonstrate a significant reduction in influenza related asthma exacerbations (Risk Difference 0.01; 95% confidence interval -0.02 to 0.04).

HARMS

The pooled results of two trials involving 2306 people with asthma did not demonstrate a significant increase in asthma exacerbations in the two weeks following influenza vaccination (Risk Difference 0.00; 95% confidence interval -0.02 to 0.02).

AUTHORS' CONCLUSIONS

Uncertainty remains about the degree of protection vaccination affords against asthma exacerbations that are related to influenza infection. Evidence from recently published trials indicates that there is no significant increase in asthma exacerbations immediately after vaccination (at least with inactivated influenza vaccination). There is concern regarding possible increased wheezing and hospital admissions in infants given live intranasal vaccination.

Modulation of the epithelial inflammatory response to rhinovirus in an atopic environment

BACKGROUND

Immune responses to rhinovirus (RV) as well as direct effects of RV on respiratory epithelium may contribute to the induction of asthma exacerbations.

OBJECTIVE

To evaluate the effect of the environment resulting from an atopic immune response on RV-induced epithelial inflammation, replication and cytotoxicity.

METHODS

Peripheral blood mononuclear cells (PBMC) from atopic asthmatic subjects and matched controls (12 pairs) were isolated and stimulated by RVs. Human bronchial epithelial (BEAS-2B) cells were infected with RV in the presence of conditioned media from RV-stimulated PBMC cultures. IL-6, IL-8, RANTES and TGF-beta1 levels were measured by ELISA, RV-induced cytotoxicity by a colorimetric method and RV titres on Ohio-HeLa cells.

RESULTS

RV-induced epithelial production of IL-6, IL-8 and RANTES was significantly lower, while TGF-beta1 was higher when cells were exposed to conditioned media from atopic asthmatic subjects compared with those from normal controls. Exposure to the 'atopic' environment also resulted in elevated RV titres and increased RV-induced cytotoxicity.

CONCLUSIONS

Under the influence of an atopic environment, the epithelial inflammatory response to RV is down-regulated, associated with increased viral proliferation and augmented cell damage, while TGF is up-regulated. These changes may help explain the propensity of atopic asthmatic individuals to develop lower airway symptoms after respiratory infections and indicate a mechanism through which viral infections may promote airway remodelling.

Impact of admission-day crowding on the length of stay of pediatric hospitalizations

OBJECTIVE

Increased crowding may affect the care that is delivered to hospitalized patients, particularly around the time of admission. There is little information about the impact of admission-day crowding on the outcome of children who are hospitalized with common pediatric conditions.

METHODS

A population cohort was constructed of children who were aged 1 to 17 years and were hospitalized in Pennsylvania and New York between April 1, 1996, and June 30, 1998, with 1 of 19 common pediatric conditions (N = 116,235). Condition-specific Cox regression and logit models were developed to estimate the effect of admission-day occupancy on 4 outcome measures after controlling for illness severity and site of care: length of stay; 21-day readmission; prolonged stay or a stay longer than the typical, uncomplicated stay for that condition as a measure of care delivered to patients with uncomplicated courses; and conditional length of stay as a measure of care delivered to patients whose stays are prolonged.

RESULTS

For children who were admitted with respiratory disease, increasing admission-day occupancy from 60% to 100% was associated with a 0.25-day increase in the average length of stay. Increased admission-day occupancy above 60% was also associated with higher odds of a prolonged stay but not with a change in 21-day readmission rates or conditional length of stay. For children who were admitted with nonrespiratory conditions, increased admission-day occupancy was not associated with changes to any length-of-stay outcome.

CONCLUSIONS

Increased admission-day occupancy was associated with longer lengths of stay for less complicated respiratory admissions but not for children who were admitted with the most serious conditions. These results suggest that medical professionals, during times of increased workload, first focus their attention on more acutely ill children with a complicated course and thus delay treatment of children who have less complicated courses but require time-consuming management and treatment.

Cyclooxygenase-2/prostaglandin D2/CRTH2 pathway mediates double-stranded RNA-induced enhancement of allergic airway inflammation

Respiratory RNA viruses responsible for the common cold often worsen airway inflammation and bronchial responsiveness, two characteristic features of human asthma. We studied the effects of dsRNA, a nucleotide synthesized during viral replication, on airway inflammation and bronchial hyperresponsiveness in murine models of asthma. Intratracheal instillation of poly I:C, a synthetic dsRNA, increased the airway eosinophilia and enhanced bronchial hyperresponsiveness to methacholine in OVA-sensitized, exposed rats. These changes were associated with induction of cyclooxygenase-2 (COX-2) expression and COX-2-dependent PGD2 synthesis in the lungs, particularly in alveolar macrophages. The direct intratracheal instillation of PGD2 enhanced the eosinophilic inflammation in OVA-exposed animals, whereas pretreatment with a dual antagonist against the PGD2 receptor-(CRTH2) and the thromboxane A2 receptor, but not with a thromboxane A2 receptor-specific antagonist, nearly completely eliminated the dsRNA-induced worsening of airway inflammation and bronchial hyperresponsiveness. CRTH2-deficient mice had the same degree of allergen-induced airway eosinophilia as wild-type mice, but they did not exhibit a dsRNA-induced increase in eosinophil accumulation. Our data demonstrate that COX-2-dependent production of PGD2 followed by eosinophil recruitment into the airways via a CRTH2 receptor are the major pathogenetic factors responsible for the dsRNA-induced enhancement of airway inflammation and responsiveness.

Syk associates with clathrin and mediates phosphatidylinositol 3-kinase activation during human rhinovirus internalization

Human rhinovirus (HRV) causes the common cold. The most common acute infection in humans, HRV is a leading cause of exacerbations of asthma and chronic obstruction pulmonary disease because of its ability to exacerbate airway inflammation by altering epithelial cell biology upon binding to its receptor, ICAM-1. ICAM-1 regulates not only viral entry and replication but also signaling pathways that lead to inflammatory mediator production. We recently demonstrated the Syk tyrosine kinase to be an important mediator of HRV-ICAM-1 signaling: Syk regulates replication-independent p38 MAPK activation and IL-8 expression. In leukocytes, Syk regulates receptor-mediated internalization via PI3K. Although PI3K has been shown to regulate HRV-induced IL-8 expression and clathrin-mediated endocytosis of HRV, the role of airway epithelial Syk in this signaling pathway is not known. We postulated that Syk regulates PI3K activation and HRV endocytosis in the airway epithelium. Using confocal microscopy and immunoprecipitation, we demonstrated recruitment of the normally cytosolic Syk to the plasma membrane upon HRV16-ICAM-1 binding, along with Syk-clathrin coassociation. Subsequent incubation at 37 degrees C to permit internalization revealed redistribution of Syk to punctate structures resembling endosomes and colocalization with HRV16. Internalized HRV was not detected in cells overexpressing the kinase inactive Syk(K396R) mutant, indicating that kinase activity was necessary for endocytosis. HRV-induced PI3K activation was dependent on Syk; Syk knockdown by small interfering RNA significantly decreased phosphorylation of the PI3K substrate Akt. Together, these data reveal Syk to be an important mediator of HRV endocytosis and HRV-induced PI3K activation.

Antigen sensitization influences organophosphorus pesticide-induced airway hyperreactivity

BACKGROUND

Recent epidemiologic studies have identified organophosphorus pesticides (OPs) as environmental factors potentially contributing to the increase in asthma prevalence over the last 25 years. In support of this hypothesis, we have demonstrated that environmentally relevant concentrations of OPs induce airway hyperreactivity in guinea pigs.

OBJECTIVES

Sensitization to allergen is a significant contributing factor in asthma, and we have shown that sensitization changes virus-induced airway hyperreactivity from an eosinophil-independent mechanism to one mediated by eosinophils. Here, we determine whether sensitization similarly influences OP-induced airway hyperreactivity.

METHODS

Nonsensitized and ovalbumin-sensitized guinea pigs were injected subcutaneously with the OP parathion (0.001-1.0 mg/kg). Twenty-four hours later, animals were anesthetized and ventilated, and bronchoconstriction was measured in response to either vagal stimulation or intravenous acetylcholine. Inflammatory cells and acetylcholinesterase activity were assessed in tissues collected immediately after physiologic measurements.

RESULTS

Ovalbumin sensitization decreased the threshold dose for parathion-induced airway hyperreactivity and exacerbated parathion effects on vagally induced bronchoconstriction. Pretreatment with antibody to interleukin (IL)-5 prevented parathion-induced hyperreactivity in sensitized but not in nonsensitized guinea pigs. Parathion did not increase the number of eosinophils in airways or the number of eosinophils associated with airway nerves nor did it alter eosinophil activation as assessed by major basic protein deposition.

CONCLUSIONS

Antigen sensitization increases vulnerability to parathion-induced airway hyperreactivity and changes the mechanism to one that is dependent on IL-5. Because sensitization to allergens is characteristic of 50% of the general population and 80% of asthmatics (including children), these findings have significant implications for OP risk assessment, intervention, and treatment strategies.

Plasma UGRP1 levels associate with promoter G-112A polymorphism and the severity of asthma

BACKGROUND

Uteroglobin-related protein 1 (UGRP1) is a secretory protein expressed in the airways and is speculated to have anti-inflammatory activity. In the mouse, its gene expression is down-regulated by interleukin (IL)-5 and -9, and up-regulated by IL-10. However, the precise role of UGRP1 in human inflammatory airway diseases such as asthma has not been clarified. The objectives of this study were to establish an ELISA system to quantify UGRP1 protein, and to examine whether plasma UGRP1 levels are associated with the G-112A polymorphism, asthma susceptibility, and its severity.

METHODS

152 asthma patients and 103 normal controls were involved in this study. Mice were immunized with recombinant UGRP1 and hybridoma cell lines were established. A sandwich ELISA system was established by using two monoclonal antibodies recognizing different epitopes. Plasma UGRP1 levels were measured with the ELISA system and the G-112A allele was detected by using real-time PCR.

RESULTS

An ELISA system was established that allowed determination of UGRP1 levels within the range of 9.6-1250 pg/ml. The mean plasma UGRP1 levels for subjects with -112A allele were significantly lower than those without it (p = 0.025). Although there was no significant difference in the plasma UGRP1 levels between asthma patients and controls (p = 0.13), severe asthma patients without oral corticosteroid had significantly lower plasma UGRP1 levels compared to mild- or moderate- asthma patients and controls (p = 0.004, 0.03 and 0.003, respectively).

CONCLUSIONS

The ELISA system for quantifying UGRP1 protein was established, and plasma UGRP1 levels were associated with the G-112A UGRP1 gene promoter polymorphism and the severity of asthma.

Understanding the mechanisms of viral induced asthma: new therapeutic directions

Asthma is a common and debilitating disease that has substantially increased in prevalence in Western Societies in the last 2 decades. Respiratory tract infections by respiratory syncytial virus (RSV) and rhinovirus (RV) are widely implicated as common causes of the induction and exacerbation of asthma. These infections in early life are associated with the induction of wheeze that may progress to the development of asthma. Infections may also promote airway inflammation and enhance T helper type 2 lymphocyte (Th2 cell) responses that result in exacerbations of established asthma. The mechanisms of how RSV and RV induce and exacerbate asthma are currently being elucidated by clinical studies, in vitro work with human cells and animal models of disease. This research has led to many potential therapeutic strategies and, although none are yet part of clinical practise, they show much promise for the prevention and treatment of viral disease and subsequent asthma.

The presence of rhinovirus in lower airways of patients with bronchial asthma

RATIONALE

The common cold virus, human rhinovirus (HRV), is the most frequent cause of asthma exacerbations. However, a possible contribution of HRV to the pathogenesis of chronic, persistent asthma has not been defined.

OBJECTIVES

To determine if patients with stable asthma, who are free of clinical signs of a respiratory infection for at least 3 weeks, harbor HRV in their bronchi more frequently than nonasthmatic control subjects, and whether clinical features of asthma are associated with the presence of HRV.

METHODS

Immunohistochemistry and the indirect in situ reverse transcription-polymerase chain reaction method were used to detect the presence of HRV in bronchial mucosal biopsies in patients with asthma and nonasthmatic control subjects.

MEASUREMENTS AND MAIN RESULTS

HRV was found by immunohistochemistry in 9 of 14 bronchial biopsies from subjects with asthma (64.3%) and 2 of 6 nonasthmatic control subjects (33.3%) (P = 0.38). With the more sensitive indirect in situ reverse transcription-polymerase chain reaction method, HRV was found in the mucosal biopsies of 73% of patients with asthma and 22% of nonasthmatic control subjects (P < 0.001). Subjects positive for HRV had lower pulmonary function, higher numbers of blood eosinophils and leukocytes, and eosinophilic infiltration in bronchial mucosa.

CONCLUSIONS

HRV was detected in the lower airway tissue of patients with asthma significantly more often than in nonasthmatic subjects, and its presence was associated with clinical features of more severe disease.

Epidermal growth factor receptor signaling to Erk1/2 and STATs control the intensity of the epithelial inflammatory responses to rhinovirus infection

Rhinovirus infection is the most common cause of acute exacerbations of inflammatory lung diseases, such as asthma and chronic obstructive pulmonary disease, where it provokes steroid refractory and abnormally intense neutrophilic inflammation that can be life threatening. Epidermal growth factor receptor (EGFR) expression correlates with disease severity and neutrophil infiltration in these conditions. However, the role of EGFR signaling in rhinovirus infection is unknown. We measured the key determinants of neutrophilic inflammation interleukin (IL)-8 and ICAM-1 in rhinovirus (RV16 serotype)-infected bronchial epithelial cells, BEAS-2B. RV16 infection stimulated IL-8 and ICAM-1 expression, which was further elevated (2-fold) by transient up-regulation of EGFR levels. Detection of viral RNA by quantitative real time PCR confirmed that enhanced expression was not associated with increased viral replication. EGFR ligands (epiregulin, amphiregulin, and heparin-binding epidermal growth factor) were induced by RV16 infection, and inhibition of metalloproteases responsible for ligand shedding partially suppressed this response. The EGFR inhibitor AG1478, completely blocked IL-8 and ICAM-1 expression to basal levels, as did the specific Erk1/2 inhibitor U0126. The p38 mitogen-activated protein kinase inhibitor SB203580 blocked IL-8 secretion but not ICAM-1 expression, whereas the PI3K inhibitor wortmannin was ineffective in both responses. Kinase inactive K721R EGFR, which is selectively deficient in STAT signaling, reversed RV16 responses associated with EGFR overexpression. In conclusion, RV16 infection rapidly promotes induction of EGFR ligands and utilizes EGFR signaling to increase IL-8 and ICAM-1 levels. These results suggest that targeting EGFR may provide a selective therapy that dampens neutrophil-driven inflammation without compromising essential antiviral pathways mediated by pathogen recognition receptors such as TLR3.

Attenuation of the type I interferon response in cells infected with human rhinovirus

The type I interferon (IFN) response requires the coordinated activation of the latent transcription factors NF-kappaB, IRF-3 and ATF-2 which in turn activate transcription from the IFN-beta promoter. Here we have examined the type I interferon response in rhinovirus type 14-infected A549 cells, with particular emphasis on the status of the transcription factor IRF-3. Our results indicate that although rhinovirus type 14 (RV14) infection induces the activation of NF-kappaB and ATF-2, only very low levels of IFN-beta mRNA are detected. Analysis of ISG54 mRNA levels revealed very little induction of this IRF-3 responsive transcript and suggested that IRF-3 activation might be impaired. Examination of IRF-3 in RV14-infected cells demonstrated only low levels of phosphorylation, a lack of homodimer formation and an absence of nuclear accumulation indicating that this transcription factor is not activated. Inhibition of viral protein synthesis following infection resulted in an increase in IFN-beta mRNA levels indicating that viral gene products prevent induction of this pathway. Collectively, these results indicate that RV14 infection inhibits the host type I interferon response by interfering with IRF-3 activation.

Murine cytomegalovirus influences Foxj1 expression, ciliogenesis, and mucus plugging in mice with allergic airway disease

We have followed throughout time the development of allergic airway disease (AAD) in both uninfected mice and mice infected intranasally with murine cytomegalovirus (MCMV). Histological evaluation of lung tissue from uninfected mice with AAD demonstrated mucus plugging after 14 and 21 days of ovalbumin-aerosol challenge, with resolution of mucus plugging occurring by 42 days. In MCMV/AAD mice, mucus plugging was observed after 7 days of ovalbumin-aerosol challenge and remained present at 42 days. The level of interleukin-13 in bronchoalveolar lavage fluid from MCMV/AAD mice was decreased compared with AAD mice and was accompanied by increased levels of interferon-gamma. Levels of Muc5A/C, Muc5B, or Muc2 mucin mRNA in the lungs of MCMV/AAD mice were not elevated compared with AAD mice. MCMV was able to infect the airway epithelium, resulting in decreased expression of Foxj1, a transcription factor critical for ciliogenesis, and a loss of ciliated epithelial cells. In addition, an increase in the number of epithelial cells staining positive for periodic acid-Schiff was observed in MCMV/AAD airways. Together, these findings suggest that MCMV infection of the airway epithelium enhances goblet cell metaplasia and diminishes efficient mucociliary clearance in mice with AAD, resulting in increased mucus plugging.

The role of respiratory viruses in cystic fibrosis

Background

Previous studies have suggested a role played by respiratory viruses in the exacerbation of cystic fibrosis (CF). However, the impact of respiratory viruses could have been underestimated because of the low detection rate by conventional laboratory methods.

Methods

Children with CF had nasal swabs and sputum samples obtained on a routine basis and when they developed respiratory exacerbations. Nucleic Acid Sequence Based Amplification (NASBA) was used to detect respiratory viruses from nasal swabs. The definition of a respiratory exacerbation was when the symptom score totalled to 4 or more, or if the peak expiratory flow fell by more than 50 l/min from the child's usual best value, or if the parent subjectively felt that the child was developing a cold.

Results

71 patients had 165 reported episodes of respiratory exacerbations. 138 exacerbation samples were obtained of which 63 (46%) were positive for respiratory viruses. In contrast, 23 of 136 asymptomatic nasal swabs (16.9%) were positive for respiratory viruses. There was significantly more viruses being detected during respiratory exacerbations, in particular influenza A, influenza B and rhinovirus (p < 0.05).

Upper respiratory symptoms significantly correlated with positive respiratory viral detection (p < 0.05). This study also showed that viral respiratory exacerbations in CF could be independent from bacterial infections.

Conclusions

Respiratory viruses are associated with exacerbations in CF and upper respiratory symptoms are strong predictors for their presence. ‘Real-time’ NASBA has a rapid turn-around time and has the potential to aid clinical decision making, such as the use of anti-virals and administration of antibiotics.

New developments in the epidemiology and clinical spectrum of rhinovirus infections

PURPOSE OF REVIEW

The purpose of this review is to summarize the recent changes in our understanding of the epidemiology and clinical manifestations of rhinovirus infection that have occurred as a result of the improved diagnostic sensitivity provided by the reverse transcriptase PCR assays.

RECENT FINDINGS

Rhinovirus infection is now recognized as an important cause of acute exacerbations of asthma in school-aged children. Along with other respiratory viruses, rhinovirus infection is also a cause of exacerbations of cystic fibrosis. There is evidence that rhinovirus can infect the lower airways and may be associated with bronchiolitis and pneumonia in immunocompetent children and with lower respiratory tract disease in the immunocompromised host.

SUMMARY

The use of nucleic acid hybridization-based assays has expanded our understanding of the spectrum of clinical illness that is associated with rhinovirus infection. The prevalence of rhinovirus infection in children is high and presents a risk for coincidental detection of rhinovirus in the face of other infectious syndromes. The detection of rhinovirus from patients with new or unusual clinical syndromes does not permit the assumption that rhinovirus is playing a causal role in the illness.

Mouse models of rhinovirus-induced disease and exacerbation of allergic airway inflammation

Rhinoviruses cause serious morbidity and mortality as the major etiological agents of asthma exacerbations and the common cold. A major obstacle to understanding disease pathogenesis and to the development of effective therapies has been the lack of a small-animal model for rhinovirus infection. Of the 100 known rhinovirus serotypes, 90% (the major group) use human intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor and do not bind mouse ICAM-1; the remaining 10% (the minor group) use a member of the low-density lipoprotein receptor family and can bind the mouse counterpart. Here we describe three novel mouse models of rhinovirus infection: minor-group rhinovirus infection of BALB/c mice, major-group rhinovirus infection of transgenic BALB/c mice expressing a mouse-human ICAM-1 chimera and rhinovirus-induced exacerbation of allergic airway inflammation. These models have features similar to those observed in rhinovirus infection in humans, including augmentation of allergic airway inflammation, and will be useful in the development of future therapies for colds and asthma exacerbations.

BSACI guidelines for the management of allergic and non-allergic rhinitis

This guidance for the management of patients with allergic and non-allergic rhinitis has been prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI). The guideline is based on evidence as well as on expert opinion and is for use by both adult physicians and paediatricians practicing in allergy. The recommendations are evidence graded. During the development of these guidelines, all BSACI members were included in the consultation process using a web-based system. Their comments and suggestions were carefully considered by the SOCC. Where evidence was lacking, consensus was reached by the experts on the committee. Included in this guideline are clinical classification of rhinitis, aetiology, diagnosis, investigations and management including subcutaneous and sublingual immunotherapy. There are also special sections for children, co-morbid associations and pregnancy. Finally, we have made recommendations for potential areas of future research.

Asthma

Asthma has been recognized as a disease since the earliest times. In the Corpus Hippocraticum, Hippocrates used the term “ασθμα” to indicate any form of breathing difficulty manifesting itself by panting. Aretaeus of Cappadocia, a well-known Greek physician (second century A.D.), is credited with providing the first detailed description of an asthma attack [13], and to Celsus it was a disease with wheezing and noisy, violent breathing. In the history of Rome, we find many members of the Julio-Claudian family affected with probable atopic respiratory disorders: Caesar Augustus suffered from bronchoconstriction, seasonal rhinitis as well as a highly pruritic skin disease. Claudius suffered from rhinoconjunctivitis and Britannicus was allergic to horse dander [529]. Maimonides (1136–1204) warned that to neglect treatment of asthma could prove fatal, whereas until the 19th century, European scholars defined it as “nervous asthma,” a term that was given to mean a defect of conductivity of the ninth pair of cranial nerves.

Diagnosis and treatment of asthma in childhood: a PRACTALL consensus report

Asthma is the leading chronic disease among children in most industrialized countries. However, the evidence base on specific aspects of pediatric asthma, including therapeutic strategies, is limited and no recent international guidelines have focused exclusively on pediatric asthma. As a result, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology nominated expert teams to find a consensus to serve as a guideline for clinical practice in Europe as well as in North America. This consensus report recommends strategies that include pharmacological treatment, allergen and trigger avoidance and asthma education. The report is part of the PRACTALL initiative, which is endorsed by both academies.

Outbreaks of human coronavirus in a pediatric and neonatal intensive care unit

Human coronavirus 229E (HCoV) has been recently recognized as a potential agent of nosocomial viral respiratory infections (NRVI) in high-risk infants. We have confirmed this as fact through the study of a 1-year period of HCoV outbreaks occurring during a prospective survey of NRVI in a paediatric and neonatal intensive care unit (PNICU) using new molecular techniques for HCoV detection. Nasal samples obtained at admission and weekly thereafter for all hospitalised children, as well as monthly nasal samples from staff, were analysed using immunofluorescence for respiratory syncytial virus (RSV), influenza viruses A and B, paramyxoviruses 1, 2, 3 and adenoviruses. RT-PCR was used for HCoV detection. During the year 1998, 43 HCoV-related NRVI were detected in 152 neonates (incidence 28.3%), and 7 HCoV-related NRVI were found in 92 children (incidence 7.6%). Three HCoV-related outbreaks were observed (February, August and December), associated with a high prevalence of HCoV infection in the staff. During the August outbreak, 50% to 78% of hospitalised neonates and children were infected. Seventy-five percent of hospitalised preterm neonates with a gestational age less than 32 weeks and 52.4% of staff members were infected. Risk factors for NRVI in neonates were birth weight, gestational age, ventilation, oxygenation and hospitalisation length. Ninety-two percent of infected preterm neonates were symptomatic, mainly with bradycardia and respiratory worsening. These data provide additional evidence for a possibly significant role of HCoV in NRVI in a PNICU. The role of staff or hospitalised children in spreading HCoV is hypothesised.

Thymic stromal lymphopoietin (TSLP) as a bridge between infection and atopy

The rising worldwide prevalence of asthma has intensified interest in the natural history of asthma. An improved understanding of the genetic, environmental, and developmental factors contributing to the inception and exacerbation of asthma will be crucial to efforts to devise effective preventive and therapeutic interventions. There is increasing evidence that the complex interplay of early life respiratory viral infections and allergic sensitization is important in the development of asthma. Major causes of asthma exacerbations are respiratory viral infections and aeroallergen exposure, which may have interactive co-morbid effects. This review describes the potential role of thymic stromal lymphopoietin (TSLP) as a connection between the innate immune response to respiratory viral infections and the type-2 adaptive immune response in the development and exacerbation of asthma.

Enhanced severity of virus associated lower respiratory tract disease in asthma patients may not be associated with delayed viral clearance and increased viral load in the upper respiratory tract

BACKGROUND

Viral respiratory infections, particularly human rhinovirus (HRV) infections, are the most common cause of asthma exacerbation. HRV infections usually lead to more severe and longer duration of lower respiratory tract (LRT) symptoms in asthmatics than in otherwise healthy individuals. However, the exact mechanism by which viruses contribute to exacerbation of asthma is unknown.

OBJECTIVES

The main objective of our study was to investigate the relationship of the enhanced severity of LRT symptoms to viral dynamics or cytokine responses in the upper respiratory tract (URT).

STUDY DESIGN

Therefore, we conducted a longitudinal study in which asthmatics and healthy controls were followed during natural viral respiratory tract infections.

RESULTS

Our study confirmed that viral respiratory tract infections caused more severe problems of the LRT in asthma patients as compared to healthy controls. However, for all subjects, the severity of LRT symptoms were not related to viral load or prolonged viral shedding in the URT. In addition, we did not detect differences in proinflammatory cytokines in the URT between asthmatics and controls.

CONCLUSION

Persistence of the virus, as well as viral load in the URT, may not be associated with the induction and/or persistence of asthmatic symptoms.

[Association between asthma and viral infections]

A pesar de que las infecciones respiratorias virales son el factor asociado con más frecuencia con la expresión del asma (independientemente del fenotipo, edad y fase de la historia natural asmática en la cual la infección ocurre) y de la fuerte asociación temporal existente entre las infecciones y las crisis obstructivas/asmáticas, el rol de los virus en la patogénesis del asma no está aún bien dilucidado. Los factores que explicarían esta conexión son heterogéneos y, a veces, contradictorios. Probablemente las alteraciones en la función y tamaño de la vía aérea, la desregulación (congénita y adquirida) del tono de la vía aérea, las alteraciones en la respuesta inmunitaria a las infecciones y las variantes genéticas en dicha respuesta sean los cuatro mecanismos principales implicados en la asociación entre las infecciones respiratorias virales y el posterior desarrollo del asma o sibilancias en los niños. Futuras estrategias terapéuticas y de prevención deberían considerar estos mecanismos.