Monocyte IL-10 production during respiratory syncytial virus bronchiolitis is associated with recurrent wheezing in a one-year follow-up study

Vitamin D Level and Immune Modulation in Children with Recurrent Wheezing

INTRODUCTION AND AIM

A direct causal relationship between vitamin D (vit D) deficiency and recurrent wheezing has not been proven. The present study investigated the role of vit D in enhancing the risk of asthma or recurrent wheezing by modifying the intensity of the inflammatory process.

MATERIAL AND METHOD

Forty children with wheezing presenting at the emergency service and sixteen healthy control subjects were included in the study. Children with wheezing were either in the first episode (20) or with recurrent wheezing (20). Children with chronic diseases, and other conditions that present with acute wheezing or that might influence the vit D level, were excluded. Blood samples were taken at presentation and 3-6 months later, to evaluate the serum levels of total IgE, vit D, IL-10 and IL-31. Statistical analysis was performed using the SPSS 25 program, with a significance level of p < 0.05.

RESULTS AND CONCLUSION

The vit D level was lower in patients with recurrent wheezing compared with those with a single episode and with the control group, and this increased with time. IL-10 was significantly higher in children with wheezing than in the control group, with the highest values in those with an acute episode of wheezing. IL-31 was higher in children with recurrent wheezing than in those with a first episode only at the initial point, while at the final time point it was lower. Low levels of vit D appear to be detected more frequently in recurrent wheezing than in simple wheezing. Immune modulation, as measured by Th2 status reflected by IL-10 and IL-31 levels, appears to depend on the wheezing phenotype and on the general health status.

Host Responses to Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) infections are a constant public health problem, especially in infants and older adults. Virtually all children will have been infected with RSV by the age of two, and reinfections are common throughout life. Since antigenic variation, which is frequently observed among other respiratory viruses such as SARS-CoV-2 or influenza viruses, can only be observed for RSV to a limited extent, reinfections may result from short-term or incomplete immunity. After decades of research, two RSV vaccines were approved to prevent lower respiratory tract infections in older adults. Recently, the FDA approved a vaccine for active vaccination of pregnant women to prevent severe RSV disease in infants during their first RSV season. This review focuses on the host response to RSV infections mediated by epithelial cells as the first physical barrier, followed by responses of the innate and adaptive immune systems. We address possible RSV-mediated immunomodulatory and pathogenic mechanisms during infections and discuss the current vaccine candidates and alternative treatment options.

Clinical characteristics and differential cytokine expression in hospitalized Taiwanese children with respiratory syncytial virus and rhinovirus bronchiolitis

BACKGROUND

Viral bronchiolitis presents a heterogeneous spectrum. In this study, we investigated the clinical characteristics and the cytokines/chemokines profiles among respiratory syncytial virus (RSV), rhinovirus (RV), and their dual infection in Taiwanese children with viral bronchiolitis.

METHOD

This study was conducted between October 2014 and June 2017. Viral etiology was identified using a Luminex respiratory virus panel and blood cytokines were evaluated using a MILLIPLEX MAP Human Cytokine/Chemokine Panel. Cytokine/Chemokine expressions were compared by clinical severity, steroid treatment, and viral entities.

RESULTS

A total of 184 patients were evaluated; at least one respiratory virus was identified in 163 (88.6%) patients. RSV and RV were the two leading viral etiologies, with 25.5% and 17.3%, respectively. RV bronchiolitis has a comparable severity to RSV but is more common in children of an older age with a history of recurrent wheezing and blood eosinophilia. Decreased tumor necrosis factor-alpha (TNF-α) and interferon gamma (INF-γ) levels were correlated with clinical severity. Patients infected with RV exhibited higher levels of Interleukin (IL)-22, IL-23, IL-25, IL-31, and IL-33 (p < 0.05), whereas those with RSV had higher levels of TNF-α, INF-γ, and IL-10 (p < 0.05). Systemic steroid treatment was associated with higher expressions of IL-4, IL-8, IL-13, and MIP-1α levels (p < 0.05). Cluster analysis revealed a high correlation of IL-33 and IL-31(R² = 0.9731, p < 0.0001).

CONCLUSION

Different viral infections elicited the characteristic clinical presentation and immune profiles in bronchiolitis. Our findings also highlight the role of the IL-33/IL-31 axis in the immunopathogenesis of bronchiolitis.

Mucosal Immune Responses to Respiratory Syncytial Virus

Despite over half a century of research, respiratory syncytial virus (RSV)-induced bronchiolitis remains a major cause of hospitalisation in infancy, while vaccines and specific therapies still await development. Our understanding of mucosal immune responses to RSV continues to evolve, but recent studies again highlight the role of Type-2 immune responses in RSV disease and hint at the possibility that it dampens Type-1 antiviral immunity. Other immunoregulatory pathways implicated in RSV disease highlight the importance of focussing on localised mucosal responses in the respiratory mucosa, as befits a virus that is essentially confined to the ciliated respiratory epithelium. In this review, we discuss studies of mucosal immune cell infiltration and production of inflammatory mediators in RSV bronchiolitis and relate these studies to observations from peripheral blood. We also discuss the advantages and limitations of studying the nasal mucosa in a disease that is most severe in the lower airway. A fresh focus on studies of RSV pathogenesis in the airway mucosa is set to revolutionise our understanding of this common and important infection.

The role of respiratory syncytial virus- and rhinovirus-induced bronchiolitis in recurrent wheeze and asthma-A systematic review and meta-analysis

INTRODUCTION

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis. RSV-induced bronchiolitis has been associated with preschool wheeze and asthma in cohort studies where the comparison groups consist of healthy infants. However, recent studies identify rhinovirus (RV)-induced bronchiolitis as a potentially stronger risk factor for recurrent wheeze and asthma.

AIM

This systematic review and meta-analysis aimed to compare the associations of RSV- and RV-induced bronchiolitis with the development of preschool wheeze and childhood asthma.

METHODS

We performed a systematic search of the published literature in five databases by using a MeSH term-based algorithm. Cohort studies that enrolled infants with bronchiolitis were included. The primary outcomes were recurrent wheeze and asthma diagnosis. Wald risk ratios and odds ratios (ORs) were estimated, along with their 95% confidence intervals (CIs). Individual and summary ORs were visualized with forest plots.

RESULTS

There were 38 studies included in the meta-analysis. Meta-analysis of eight studies that had data on the association between infant bronchiolitis and recurrent wheeze showed that the RV-bronchiolitis group were more likely to develop recurrent wheeze than the RSV-bronchiolitis group (OR 4.11; 95% CI 2.24-7.56). Similarly, meta-analysis of the nine studies that had data on asthma development showed that the RV-bronchiolitis group were more likely to develop asthma (OR 2.72; 95% CI 1.48-4.99).

CONCLUSION

This is the first meta-analysis that directly compares between-virus differences in the magnitude of virus-recurrent wheeze and virus-childhood asthma outcomes. RV-induced bronchiolitis was more strongly associated with the risk of developing wheeze and childhood asthma.

The Role of Interferons in Driving Susceptibility to Asthma Following Bronchiolitis: Controversies and Research Gaps

Bronchiolitis is the most common cause of hospitalization in infancy and is associated with a higher risk for the development of childhood asthma. However, not all children hospitalized with bronchiolitis will develop asthma. The mechanisms underlying asthma development following bronchiolitis hospitalization are complex. Immune responses to respiratory viruses may underlie both bronchiolitis severity and long-term sequela (such as asthma). Interferons (IFNs) are important components of innate immune responses to respiratory viruses and could influence both asthma development and asthma exacerbations. However, the nature of the relationship between interferon production and wheezing illnesses is controversial. For example, low peripheral blood IFN responses at birth have been linked with recurrent wheeze and asthma development. In contrast, there is evidence that severe illnesses (e.g., hospitalization for bronchiolitis) are associated with increased IFN responses during acute infection (bronchiolitis hospitalization) and a higher risk for subsequent asthma diagnosis. Furthermore, mechanistic studies suggest that bronchial epithelial cells from asthmatic children have impaired IFN responses to respiratory viruses, which may enable increased viral replication followed by exaggerated secondary IFN responses. This review aims to discuss controversies around the role of IFNs as drivers of susceptibility to asthma development following bronchiolitis hospitalization. Past evidence from both mechanistic and cohort studies are discussed. We will highlight knowledge gaps that can inform future research study design.

Longitudinal plasma cytokine concentrations and recurrent wheezing after RSV bronchiolitis

BACKGROUND

Respiratory syncytial virus (RSV) bronchiolitis in young children has been associated with increased risk for developing recurrent wheezing, but the underlying mechanisms, are not completely defined. We hypothesized that RSV induces a disregulated immune response defined by a distinct cytokine profile in infants at increased risk for developing recurrent wheezing.

METHODS

Previously healthy infants less than 12 months of age hospitalized with a first episode of RSV bronchiolitis were enrolled and blood samples and clinical and epidemiological data collected. A group of healthy non-infected controls were enrolled in parallel. Children were followed longitudinally and subsequent blood samples collected in RSV-infected infants at one month and at one year after hospital discharge to measure longitudinal plasma concentrations of IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17 and IL1-β. Risk of post-RSV wheezing was assessed by Poisson modelling.

RESULTS

From October 2008 to March 2012 we enrolled 37 infants hospitalized with RSV bronchiolitis and 9 healthy age-matched controls. Within the RSV cohort, 17 (46%) children developed recurrent wheezing within the following 12 months. Plasma cytokine profiles measured during the acute infection were similar in children who developed recurrent wheezing versus those who did not, but lower in healthy controls vs RSV infants who subsequently developed wheezing. At one month and 12 months post-acute RSV infection, infants who developed recurrent wheezing had higher IFN-γ plasma concentrations versus those with no-wheezing (p < 0.05). Moreover, IFN-γ concentrations were identified as independent predictor of post-RSV wheezing.

CONCLUSIONS

Children with RSV-associated recurrent wheezing had persistently elevated plasma concentrations of IFN-γ for a year after acute infection, suggesting that this cytokine could be used as a biomarker for risk of recurrent wheezing and possibly plays a role in the pathogenesis of this condition.

IgE-mediated regulation of IL-10 and type I IFN enhances rhinovirus-induced Th2 differentiation by primary human monocytes

Rhinovirus (RV) infections are linked to the development and exacerbation of allergic diseases including allergic asthma. IgE, another contributor to atopic disease pathogenesis, has been shown to regulate DC antiviral functions and influence T cell priming by monocytes. We previously demonstrated that IgE-mediated stimulation of monocytes alters multiple cellular functions including cytokine secretion, phagocytosis, and influenza-induced Th1 development. In this study, we investigate the effects of IgE-mediated stimulation on monocyte-driven, RV-induced T cell development utilizing primary human monocyte-T cell co-cultures. We demonstrate that IgE crosslinking of RV-exposed monocytes enhances monocyte-driven Th2 differentiation. This increase in RV-induced Th2 development was regulated by IgE-mediated inhibition of virus-induced type I IFN and induction of IL-10. These findings suggest an additional mechanism by which two clinically significant risk factors for allergic disease exacerbations-IgE-mediated stimulation and rhinovirus infection-may synergistically promote Th2 differentiation and allergic inflammation.

IL10 deficiency promotes alveolar enlargement and lymphoid dysmorphogenesis in the aged murine lung

The connection between aging-related immune dysfunction and the lung manifestations of aging is poorly understood. A detailed characterization of the aging IL10-deficient murine lung, a model of accelerated aging and frailty, reconciles features of both immunosenescence and lung aging in a coherent model. Airspace enlargement developed in the middle-aged (12 months old) and aged (20-22 months old) IL10-deficient lung punctuated by an expansion of macrophages and alveolar cell apoptosis. Compared to wild-type (WT) controls, the IL10-deficient lungs from young (4-month-old) mice showed increased oxidative stress which was enhanced in both genotypes by aging. Active caspase 3 staining was increased in the alveolar epithelial cells of aged WT and mutant lungs but was greater in the IL10-deficient milieu. Lung macrophages were increased in the aged IL10-deficient lungs with exuberant expression of MMP12. IL10 treatment of naïve and M2-polarized bone marrow-derived WT macrophages reduced MMP12 expression. Conditioned media studies demonstrated the secretome of aged mutant macrophages harbors reduced AECII prosurvival factors, specifically keratinocyte growth factor (KGF) and hepatocyte growth factor (HGF), promotes cell death, and reduces survival of primary alveolar epithelial cells. Compared to WT controls, aged IL10-deficient mice have increased parenchymal lymphoid collections comprised of a reduced number of apoptotic cells and B cells. We establish that IL10 is a key modulator of airspace homeostasis and lymphoid morphogenesis in the aging lung enabling macrophage-mediated alveolar epithelial cell survival and B-cell survival within tertiary lymphoid structures.

TLRs in pulmonary diseases

Toll-like receptors (TLRs) comprise a clan of proteins involved in identification and triggering a suitable response against pathogenic attacks. As lung is steadily exposed to multiple infectious agents, antigens and host-derived danger signals, the inhabiting stromal and myeloid cells of the lung express an aggregate of TLRs which perceive the endogenously derived damage-associated molecular patterns (DAMPs) along with pathogen associated molecular patterns (PAMPs) and trigger the TLR-associated signalling events involved in host defence. Thus, they form an imperative component of host defence activation in case of microbial infections as well as non-infectious pulmonary disorders such as interstitial lung disease, acute lung injury and airways disease, such as COPD and asthma. They also play an equally important role in lung cancer. Targeting the TLR signalling network would pave ways to the design of more reliable and effective vaccines against infectious agents and control deadly infections, desensitize allergens and reduce inflammation. Moreover, TLR agonists may act as adjuvants by increasing the efficiency of cancer vaccines, thereby contributing their role in treatment of lung cancer too. Overall, TLRs present a compelling and expeditiously bolstered area of research and addressing their signalling events would be of significant use in pulmonary diseases.

Infant Immune Response to Respiratory Viral Infections

Of all respiratory viruses that affect infants, respiratory syncytial virus (RSV) and rhinovirus (RV) represent the leading pathogens causing acute disease (bronchiolitis) and are associated with the development of recurrent wheezing and asthma. The immune system in infants is still developing, and several factors contribute to their increased susceptibility to viral infections. These factors include differences in pathogen detection, weaker interferon responses, lack of immunologic memory toward the invading pathogen, and T-cell responses that are balanced to promote tolerance and restrain inflammation. These aspects are reviewed here with a focus on RSV and RV infections.

Cytokines in the Nasal Washes of Children with Respiratory Syncytial Virus Bronchiolitis

Although respiratory syncytial (RS) virus is the major cause of bronchiolitis and pneumonia in young children, the factors that regulate the associated lung inflammation have not been defined. The levels of interleukin (IL)10, IL-12, and interferon (IFN) were determined in the nasal wash samples from 20 infants with a clinical diagnosis of bronchiolitis, seven with confirmed RS virus infections and 9 control children without respiratory illnesses. IL-10 levels were significantly higher in acute nasal wash samples (1–4 d post-hospitalization) from RS virus- infected infants than in convalescent samples from these children (14–21 d post-hospitalization), from children with other forms of bronchiolitis and from control children. In contrast, only one RS virus-infected infant had detectable IL-12 in an acute nasal wash sample. IFN activity was not detected in any samples from RS virus-infected children. RS virus infection stimulates IL-10 expression but not IL-12 and IFN, possibly contributing to an ineffective cell-mediated immune response.

The impact of respiratory viruses on lung health after preterm birth

Children born preterm, less than 37 weeks' gestation, are at increased risk of viral respiratory infections and associated complications both during their initial birth hospitalisation and in their first years following discharge. This increased burden of viral respiratory infections is likely to have long term implications for lung health and function in individuals born preterm, particularly those with bronchopulmonary dysplasia. Several hypotheses have been put forward to explain the association between early life viral respiratory infection and development of suboptimal lung health and function later in life following preterm birth. Although preterm infants with diminished lung function, particularly small airways, might be particularly susceptible to asthma and wheezing disorders following viral infection, there is evidence that respiratory viruses can activate number of inflammatory and airway re-modelling pathways. Therefore, the aim of this review is to highlight the perinatal and early life risk factors that may contribute to increased susceptibility to viral respiratory infections among preterm infants during early life and to understand how respiratory viral infection may influence the development of abnormal lung health and function later in life.

Bioinformatics analysis and verification of key genes associated with recurrent respiratory tract infections

We evaluated the key genes related with recurrent respiratory tract infections (RRTIs), and then elucidated the possible molecular mechanisms of RRTIs. Neutrophil was isolated from peripheral bloods of the recurrent lower respiratory tract infection patients and healthy volunteers, respectively. The next generation sequencing information was obtained after RNA extraction, purification, library construction and sequencing. The sequencing information was preprocessed. Bioinformatics analysis including analysis of differentially expre-ssed genes (DEGs), Gene Ontology (GO) and pathway enrichment analysis, protein-protein interaction (PPI) analysis and transcription factors analysis were performed. The key genes were verified by real-time PCR. In total, 17 significant DEGs were obtained in case group compared with the control group by bioinformatics analysis. Then, 6 of 17 genes were detected by real-time PCR. There was statistical significance between case and control groups for peroxisome proliferator-activated receptor-γ (PPARG), prostaglandin-endoperoxide synthase 2 (PTGS2), transferrin (TF) and interleukin-10 (IL-10) (P<0.05), and there was no statistical significance between case and control groups for TIMP metallopeptidase inhibitor 1 (TIMP1) and matrix metallopeptidase 1 (MMP1). PPARG, PTGS2, TF and IL-10 are key genes associated with the progression of RRTIs. We speculate that TIMP1 and MMP1 may also be involved in the progression of RRTIs, but further studies with large number of samples are needed for verification.

Functional Impairment of Mononuclear Phagocyte System by the Human Respiratory Syncytial Virus

The mononuclear phagocyte system (MPS) comprises of monocytes, macrophages (MΦ), and dendritic cells (DCs). MPS is part of the first line of immune defense against a wide range of pathogens, including viruses, such as the human respiratory syncytial virus (hRSV). The hRSV is an enveloped virus that belongs to the Pneumoviridae family, Orthopneumovirus genus. This virus is the main etiological agent causing severe acute lower respiratory tract infection, especially in infants, children and the elderly. Human RSV can cause bronchiolitis and pneumonia and it has also been implicated in the development of recurrent wheezing and asthma. Monocytes, MΦ, and DCs significantly contribute to acute inflammation during hRSV-induced bronchiolitis and asthma exacerbation. Furthermore, these cells seem to be an important component for the association between hRSV and reactive airway disease. After hRSV infection, the first cells encountered by the virus are respiratory epithelial cells, alveolar macrophages (AMs), DCs, and monocytes in the airways. Because AMs constitute the predominant cell population at the alveolar space in healthy subjects, these cells work as major innate sentinels for the recognition of pathogens. Although adaptive immunity is crucial for viral clearance, AMs are required for the early immune response against hRSV, promoting viral clearance and controlling immunopathology. Furthermore, exposure to hRSV may affect the phagocytic and microbicidal capacity of monocytes and MΦs against other infectious agents. Finally, different studies have addressed the roles of different DC subsets during infection by hRSV. In this review article, we discuss the role of the lung MPS during hRSV infection and their involvement in the development of bronchiolitis.

The Burden and Long-term Respiratory Morbidity Associated with Respiratory Syncytial Virus Infection in Early Childhood

INTRODUCTION

The REGAL (RSV Evidence-a Geographical Archive of the Literature) series provide a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. The objective of this fifth publication was to determine the long-term respiratory morbidity associated with RSV lower respiratory tract infection (RSV LRTI) in early life.

METHODS

A systematic review was undertaken for articles published between January 1, 1995 and December 31, 2015. This was supplemented by inclusion of papers published whilst drafting the manuscript. Studies reporting data on the incidence and long-term wheezing and asthma following RSV LRTI in early life were included. Study quality and strength of evidence (SOE) were graded using recognized criteria.

RESULTS

A total of 2337 studies were identified of which 74 were included. Prospective, epidemiologic studies consistently demonstrated that RSV LRTI is a significant risk factor for on-going respiratory morbidity characterized by transient early wheezing and recurrent wheezing and asthma within the first decade of life and possibly into adolescence and adulthood (high SOE). RSV LRTI was also associated with impaired lung function in these children (high SOE). Respiratory morbidity has been shown to result in reduced quality of life and increased healthcare resource use (moderate SOE). The mechanisms through which RSV contributes to wheezing/asthma development are not fully understood, but appear to relate to the viral injury, preexisting abnormal lung function and/or other factors that predispose to wheezing/asthma, including genetic susceptibility, altered immunology, eosinophilia, and associated risk factors such as exposure to environmental tobacco smoke (high SOE).

CONCLUSION

There is growing evidence that RSV LRTI in early childhood is associated with long-term wheezing and asthma and impaired lung function. Future research should aim to fully elucidate the pathophysiological mechanisms through which RSV causes recurrent wheezing/asthma.

Bronchiolitis in young infants: is it a risk factor for recurrent wheezing in childhood?

BACKGROUND

Acute bronchiolitis in infancy is considered a risk factor for recurrent wheezing episodes in childhood. The present study assessed prevalence, clinical manifestations and risk factors for recurrent wheezing events during the first 3 years of life and persistent wheezing events beyond this age in children hospitalized as young infants with acute bronchiolitis.

METHODS

Two groups of children aged 6 years were included. The study group comprised 150 children with a history of hospitalization for bronchiolitis, with the first event at <6 months of age. The control group comprised 66 age- and sex-matched children with no history of bronchiolitis before 6 months of age. Children in both groups had been followed until 6 years of age by their pediatricians; data were obtained retrospectively by reviewing ambulatory records during children's visits in pediatricians' clinics. The data included epidemiological parameters, prevalence, age at onset, number of and treatments given for episodes of wheezing events prior to 6 years of age, pathogens detected, and severity of acute bronchiolitis in the study group.

RESULTS

Overall, 58% and 27% of children in the study and control groups, respectively (P=0.001) had recurrent wheezing episodes prior to the age of 3 years. Children in the study group had earlier onset of recurrent wheezing, had more episodes of wheezing, and required more bronchodilator and systemic steroids treatments compared to the control group.

CONCLUSION

Hospitalization within the first six months of life for acute bronchiolitis is an independent risk factor for recurrent wheezing episodes during the first 3 years of life.

Viral Bronchiolitis is Associated With Altered Cytokine Gene Expression and Lymphocyte Activation Status

BACKGROUND

Disease severity in viral bronchiolitis is often difficult to predict at onset, and may be related to the host immune response. Recognizing the particular immunologic features of infants who develop severe disease might offer an opportunity for developing diagnostic tools to facilitate early intervention and improve outcomes.

METHODS

We compared cytokine gene expression (by real-time reverse-transcriptase polymerase chain reaction), cytokine concentrations (by enzyme-linked immunosorbent assay) and the activation status of lymphocytes (by flow cytometry) in the peripheral blood of children hospitalized with moderate and severe viral bronchiolitis and a group of age-matched controls.

RESULTS

Analysis was undertaken on 57 children with viral bronchiolitis and 33 controls. Interleukin-7 mRNA expression at enrollment in peripheral blood mononuclear cells differed significantly between those with moderate and severe bronchiolitis, and correlated with both the subsequent length of hospital stay and need for supplemental oxygen therapy. Serum interleukin-10 concentration also distinguished moderate from severe disease. Participants with viral bronchiolitis demonstrated a more activated γδ-T cell phenotype (Vδ1+), but a more naive TCR αβ-T cell compartment compared with controls.

CONCLUSIONS

Viral bronchiolitis is characterized by a distinct pattern of cytokine expression and lymphocyte activation. These changes suggest an inadequate innate response in severe disease, and may offer potential as markers of disease severity.

Reduced Expression of HLA-DR on Monocytes During Severe Respiratory Syncytial Virus Infections

BACKGROUND

Respiratory syncytial virus (RSV) is a common cause of bronchiolitis in infants with a wide spectrum of disease severity. Besides environmental and genetic factors, it is thought that the innate immune system plays a pivotal role. The aim of this study was to investigate the expression of immune receptors on monocytes and the in vitro responsiveness from infants with severe RSV infections.

METHODS

Peripheral blood mononuclear cells (PBMCs) from infants with RSV infections were isolated. Classical, intermediate and nonclassical monocytes were immunophenotyped for the expression of CD14, CD16, human leukocyte antigen (HLA)-ABC and HLA-DR. PBMCs were stimulated with lipopolysaccharide to determine the secretion of tumor necrosis factor and interleukin (IL)-10 with enzyme-linked immunosorbent assay.

RESULTS

During RSV infection, intermediate monocytes are increased in the peripheral blood, whereas classical and nonclassical monocytes are reduced. The expression of CD14 and HLA-ABC is increased on monocytes, whereas the expression of HLA-DR is suppressed. Low HLA-DR expression is correlated with increased disease severity. PBMCs from infants with severe RSV infections show an impaired IL-10 response in vitro.

CONCLUSIONS

Phenotyping subpopulations of monocytes combined with in vitro responsiveness reveals significant differences between nonsevere and severe RSV infections. Reduced HLA-DR expression and impaired IL-10 production in vitro during severe RSV infections indicate that an imbalanced innate immune response may play an important role in disease severity.

Inflammatory markers predict episodes of wheezing during the first year of life in Bangladesh

BACKGROUND

Environmental factors that influence wheezing in early childhood in the developing world are not well understood and may be useful in predicting respiratory outcomes. Therefore, our objective was to determine the factors that can predict wheezing.

METHODS

Children from Dhaka, Bangladesh were recruited at birth and episodes of wheezing were measured alongside nutritional, immunological and socioeconomic factors over a one-year period. Poisson Regression with variable selection was utilized to determine what factors were associated with wheezing.

RESULTS

Elevated serum IL-10 (rate ratio (RR) = 1.51, 95% confidence interval (CI): 1.22-1.87), IL-1β (RR = 1.55, 95% CI: 1.26-1.93) C-reactive protein (CRP) (RR = 1.41, 95% CI: 1.03-1.93) in early life, and male gender (RR = 1.52, 95% CI: 1.27-1.82) predicted increased wheezing episodes. Conversely, increased fecal alpha-1-antitrypsin (RR = 0.87, 95% CI: 0.76-1.00) and family income (RR = 0.98, 95% CI: 0.97-0.99) were associated with a decreased number of episodes of wheezing.

CONCLUSIONS

Systemic inflammation early in life, poverty, and male sex placed infants at risk of more episodes of wheezing during their first year of life. These results support the hypothesis that there is a link between inflammation in infancy and the development of respiratory illness later in life and provide specific biomarkers that can predict wheezing in a low-income country.

A systematic review of predictive models for asthma development in children

BACKGROUND

Asthma is the most common pediatric chronic disease affecting 9.6 % of American children. Delay in asthma diagnosis is prevalent, resulting in suboptimal asthma management. To help avoid delay in asthma diagnosis and advance asthma prevention research, researchers have proposed various models to predict asthma development in children. This paper reviews these models.

METHODS

A systematic review was conducted through searching in PubMed, EMBASE, CINAHL, Scopus, the Cochrane Library, the ACM Digital Library, IEEE Xplore, and OpenGrey up to June 3, 2015. The literature on predictive models for asthma development in children was retrieved, with search results limited to human subjects and children (birth to 18 years). Two independent reviewers screened the literature, performed data extraction, and assessed article quality.

RESULTS

The literature search returned 13,101 references in total. After manual review, 32 of these references were determined to be relevant and are discussed in the paper. We identify several limitations of existing predictive models for asthma development in children, and provide preliminary thoughts on how to address these limitations.

CONCLUSIONS

Existing predictive models for asthma development in children have inadequate accuracy. Efforts to improve these models' performance are needed, but are limited by a lack of a gold standard for asthma development in children.

IL-10 Gene Polymorphisms Are Associated with Post-Bronchiolitis Lung Function Abnormalities at Six Years of Age

Aim

Interleukin-10 (IL-10) has been associated with wheezing and asthma in children and the genetic variation of the IL-10 cytokine production may be linked to post-bronchiolitis lung function. We used impulse oscillometry (IOS) to evaluate the associations of IL10 polymorphisms with lung function at a median age of 6.3 years in children hospitalised for bronchiolitis before six months of age.

Methods

We performed baseline and post-exercise IOS on 103 former bronchiolitis patients. Data on single nucleotide polymorphisms (SNP) of IL10 rs1800896 (–1082G/A), rs1800871 (–819C/T), rs1800872 (–592C/A) were available for 99 children and of IL10 rs1800890 (–3575T/A) for 98 children.

Results

IL10 rs1800896, rs1800871 and rs1800872 combined genotype AA+CT+CA and carriage of haplotype ATA, respectively, were associated with higher resistance and lower reactance in baseline IOS in adjusted analyses. At IL10 rs1800890, the A/A-genotype and carriers of A-allele were associated with lower reactance in baseline IOS. There were no significant associations between the studied SNPs and airway hyper-reactivity to exercise.

Conclusion

Low-IL-10-producing polymorphisms in the IL-10 encoding gene were associated with obstructive lung function parameters, suggesting an important role for IL-10 in development of lung function deficit in early bronchiolitis patients.

Objectives, design and enrollment results from the Infant Susceptibility to Pulmonary Infections and Asthma Following RSV Exposure Study (INSPIRE)

Background

Respiratory syncytial virus (RSV) lower respiratory tract infection (LRI) during infancy has been consistently associated with an increased risk of childhood asthma. In addition, evidence supports that this relationship is causal. However, the mechanisms through which RSV contributes to asthma development are not understood. The INSPIRE (Infant Susceptibility to Pulmonary Infections and Asthma Following RSV Exposure) study objectives are to: 1) characterize the host phenotypic response to RSV infection in infancy and the risk of recurrent wheeze and asthma, 2) identify the immune response and lung injury patterns of RSV infection that are associated with the development of early childhood wheezing illness and asthma, and 3) determine the contribution of specific RSV strains to early childhood wheezing and asthma development. This article describes the INSPIRE study, including study aims, design, recruitment results, and enrolled population characteristics.

Methods/design

The cohort is a population based longitudinal birth cohort of term healthy infants enrolled during the first months of life over a two year period. Respiratory infection surveillance was conducted from November to March of the first year of life, through surveys administered every two weeks. In-person illness visits were conducted if infants met pre-specified criteria for a respiratory illness visit. Infants will be followed annually to ages 3-4 years for assessment of the primary endpoint: wheezing illness. Nasal, urine, stool and blood samples were collected at various time points throughout the study for measurements of host and viral factors that predict wheezing illness. Nested case-control studies will additionally be used to address other primary and secondary hypotheses.

Discussion

In the INSPIRE study, 1952 infants (48% female) were enrolled during the two enrollment years and follow-up will continue through 2016. The mean age of enrollment was 60 days. During winter viral season, more than 14,000 surveillance surveys were carried out resulting in 2,103 respiratory illness visits on 1189 infants. First year follow-up has been completed on over 95% percent of participants from the first year of enrollment.

With ongoing follow-up for wheezing and childhood asthma outcomes, the INSPIRE study will advance our understanding of the complex causal relationship between RSV infection and early childhood wheezing and asthma.

The role of macrophage IL-10/innate IFN interplay during virus-induced asthma

Activation through different signaling pathways results in two functionally different types of macrophages, the pro-inflammatory (M1) and the anti-inflammatory (M2). The polarization of macrophages toward the pro-inflammatory M1 phenotype is considered to be critical for efficient antiviral immune responses in the lung. Among the various cell types that are present in the asthmatic airways, macrophages have emerged as significant participants in disease pathogenesis, because of their activation during both the inflammatory and resolution phases, with an impact on disease progression. Polarized M1 and M2 macrophages are able to reversibly undergo functional redifferentiation into anti-inflammatory or pro-inflammatory macrophages, respectively, and therefore, macrophages mediate both processes. Recent studies have indicated a predominance of M2 macrophages in asthmatic airways. During a virus infection, it is likely that M2 macrophages would secrete higher amounts of the suppressor cytokine IL-10, and less innate IFNs. However, the interactions between IL-10 and innate IFNs during virus-induced exacerbations of asthma have not been well studied. The possible role of IL-10 as a therapy in allergic asthma has already been suggested, but the divergent roles of this suppressor molecule in the antiviral immune response raise concerns. This review attempts to shed light on macrophage IL-10-IFNs interactions and discusses the role of IL-10 in virus-induced asthma exacerbations. Whereas IL-10 is important in terminating pro-inflammatory and antiviral immune responses, the presence of this immune regulatory cytokine at the beginning of virus infection could impair the response to viruses and play a role in virus-induced asthma exacerbations.

Infantile respiratory syncytial virus and human rhinovirus infections: respective role in inception and persistence of wheezing

There is evidence that respiratory viruses play a key role in the development and exacerbation of obstructive respiratory diseases in children. This review attempts to juxtapose the separate profiles and prototypes of pathogenetic mechanisms represented by the two most common amongst such viruses: respiratory syncytial virus (RSV) and human rhinovirus (HRV). RSV represents the most common agent of severe airway disease in infants and young children, and is predominant in winter months. Large epidemiological studies have revealed an unequivocal relationship between RSV infection and subsequent wheezing into childhood, thought to be related to long-term changes in neuroimmune control of the airways rather than allergic sensitisation. HRV is a highly diverse group of viruses that affect subjects of all ages, is ubiquitous and occurs year-round. In contrast to RSV, infections with HRV cause minimal cytotoxicity but induce a rapid production of cytokines and chemokines with amplification of the inflammatory response. The susceptibility to HRV-induced bronchiolitis and subsequent wheezing appears to be linked to individual predisposition since it is often associated with a family or personal history of asthma/atopy. Thus, RSV probably serves as an "inducer" rather than a "trigger". Conversely, HRVs seem to serve as a "trigger" rather than an "inducer" in predisposed individuals.

'They said it was bronchiolitis; is it going to turn into asthma doctor?'

Acute bronchiolitis is a common paediatric disease of infancy. Its association with subsequent asthma development has puzzled clinicians and epidemiologists for decades. This article reviews the current state of knowledge regarding the role of acute bronchiolitis in the inception of asthma. There is little doubt that acute bronchiolitis is associated with an increased risk of recurrent wheezing throughout the primary school years although the direction of causality--i.e. whether bronchiolitis in infancy leads to asthma or it merely represents the first clinical presentation of predisposition to asthma--is uncertain. Existing evidence suggests that both host factors (e.g. prematurity, atopic predisposition) and acute viral infection characteristics (e.g. type of virus, severity) are operating in this relationship, perhaps with variable involvement in different individuals. Further clarification of these issues will help paediatricians provide evidence-based information regarding the long-term prognosis of this common disease to the families, and at the same time, it will facilitate prophylactic approaches and therapeutic strategies.

A systematic review of predictive modeling for bronchiolitis

PURPOSE

Bronchiolitis is the most common cause of illness leading to hospitalization in young children. At present, many bronchiolitis management decisions are made subjectively, leading to significant practice variation among hospitals and physicians caring for children with bronchiolitis. To standardize care for bronchiolitis, researchers have proposed various models to predict the disease course to help determine a proper management plan. This paper reviews the existing state of the art of predictive modeling for bronchiolitis. Predictive modeling for respiratory syncytial virus (RSV) infection is covered whenever appropriate, as RSV accounts for about 70% of bronchiolitis cases.

METHODS

A systematic review was conducted through a PubMed search up to April 25, 2014. The literature on predictive modeling for bronchiolitis was retrieved using a comprehensive search query, which was developed through an iterative process. Search results were limited to human subjects, the English language, and children (birth to 18 years).

RESULTS

The literature search returned 2312 references in total. After manual review, 168 of these references were determined to be relevant and are discussed in this paper. We identify several limitations and open problems in predictive modeling for bronchiolitis, and provide some preliminary thoughts on how to address them, with the hope to stimulate future research in this domain.

CONCLUSIONS

Many problems remain open in predictive modeling for bronchiolitis. Future studies will need to address them to achieve optimal predictive models.

Clinical and epidemiologic factors related to subsequent wheezing after virus-induced lower respiratory tract infections in hospitalized pediatric patients younger than 3 years

Most wheezing episodes in infants are caused and exacerbated by virus-induced lower respiratory tract infections. However, there are few reports of epidemiologic and clinical virus-specific research with a focus on virus-induced wheezing. The purpose of the current study was to characterize the clinical presentation of virus-induced wheezing in pediatric patients <3 years of age who were hospitalized with lower respiratory tract infections. Of the 412 patients in the study, 216 were followed for 3 years. Nasopharyngeal aspirates collected from the patients at the time of admission were examined for the presence of respiratory syncytial virus (RSV), rhinovirus (RV), parainfluenza-3 virus (PIV-3), human metapneumovirus (hMPV), and influenza virus (Flu) using reverse-transcription polymerase chain reaction and rapid diagnostic tests. Clinical signs were assessed using a severity scoring system. In patients with wheezing at the time of admission, RSV, RV, RSV+RV, Flu, PIV-3, and hMPV were detected in 33, 14, 8, 8, 5, and 3 % of samples, respectively. There were no differences in age and severity scores between patients harboring more prevalent viruses (RSV and RV) and those with less common infections. Patients with wheezing and RV-positive aspirates at the time of admission were more likely to develop subsequent wheezing during the following 3 years.

CONCLUSION

RSV and RV infections are factors in the development and exacerbation of wheezing after virus-induced lower respiratory tract infections. Moreover, RV-induced wheezing may be associated with subsequent recurrent wheezing and the development of asthma.

Abnormalities in iNKT cells are associated with impaired ability of monocytes to produce IL-10 and suppress T-cell proliferation in sarcoidosis

Sarcoidosis is a multisystem granulomatous disorder characterized by marked T‐cell expansion of T helper 1 (Th1) cells. The cause of T‐cell overactivity is unknown. We hypothesized that interleukin‐10 (IL‐10) production by a yet undefined cell type might be defective, resulting in loss of regulation of T‐cell activity. Focusing on IL‐10‐producing monocytes, we first showed that monocytes isolated from the peripheral blood of corticosteroid‐naïve sarcoidosis patients (n = 51) produced less IL‐10 compared to controls, and were less able to suppress T‐cell proliferation. In addition, monocytic IL‐10 production correlated negatively with disease activity score. As invariant natural killer T (iNKT) cells are known to both interact with monocytes and be reduced in sarcoidosis patients, we then asked whether iNKT‐specific defects might be responsible for this reduced IL‐10 production. We found that greater numbers of circulating iNKT cells was associated with higher IL‐10 production. Moreover, iNKT cells enhanced monocytic IL‐10 production in vitro. Defective IL‐10 production and T‐cell suppression by sarcoidosis monocytes could be restored following their coculture with iNKT cells, in a CD1d‐ and cell contact‐dependent process. We suggest that reduced iNKT‐cell numbers in sarcoidosis may lead to impaired monocytic IL‐10 production and unchecked T‐cell expansion in sarcoidosis. These findings provide fresh insight into the mechanism of sarcoidosis disease, and interaction between iNKT cells and monocytes.

Increased risk of wheeze and decreased lung function after respiratory syncytial virus infection

Background

A relationship between hospitalization for respiratory syncytial virus (RSV) bronchiolitis and asthma development has been suggested in case-control studies.

Objective

The aim of this study was to assess the risk of current wheeze, asthma, and lung function at school age in infants previously hospitalized for RSV bronchiolitis compared to non-hospitalized children.

Methods

For this study, data from a prospective birth cohort of unselected, term-born infants (n = 553), of whom 4 (0.7%) were hospitalized for RSV bronchiolitis, and a prospective patient cohort of 155 term infants hospitalized for RSV bronchiolitis were used. Respiratory outcomes at age 6 in children hospitalized for RSV bronchiolitis were compared to non-hospitalized children.

Results

The risk of current wheeze was higher in hospitalized patients (n = 159) compared to non-hospitalized children (n = 549) (adjusted odds ratio (OR) 3.2 (95% CI 1.2–8.1). Similarly, the risk of current asthma, defined as a doctor’s diagnosis of asthma plus current symptoms or medication use, was higher in hospitalized patients (adjusted OR 3.1 (95% CI 1.3–7.5). Compared to non-hospitalized children, RSV bronchiolitis hospitalization was associated with lower lung function (mean difference FEV1% predicted −6.8 l (95% CI (−10.2 to −3.4).

Conclusions and Clinical Relevance

This is the first study showing that hospitalization for RSV bronchiolitis during infancy is associated with increased risk of wheezing, current asthma, and impaired lung function as compared to an unselected birth cohort at age 6.

Dual role of interleukin-10 in the regulation of respiratory syncitial virus (RSV)-induced lung inflammation

RSV lower respiratory tract infections (LRTI) are among the most common diseases necessitating hospital admission in children. In addition to causing acute respiratory failure, RSV infections are associated with sequelae such as secondary bacterial infections and reactive airway disease. One characteristic host response observed in severe RSV-induced LRTI and/or subsequent development of asthma is increased expression of interleukin (IL)-10. However, contradictory results have been reported regarding whether IL-10 inhibits asthmatic responses or intensifies the disease. We aimed to reconcile these discordant observations by elucidating the role of IL-10 in regulating the host response to RSV LRTI. In this study, we used a lung-specific, inducible IL-10 over-expression (OE) transgenic mouse model to address this question. Our results showed that the presence of IL-10 at the time of RSV infection not only attenuated acute inflammatory process (i.e. 24 h post-infection), but also late inflammatory changes [characterized by T helper type 2 (Th2) cytokine and chemokine expression]. While this result appears contradictory to some clinical observations where elevated IL-10 levels are observed in asthmatic patients, we also found that delaying IL-10 OE until the late immune response to RSV infection, additive effects rather than inhibitory effects were observed. Importantly, in non-infected, IL-10 OE mice, IL-10 OE alone induced up-regulation of Th2 cytokine (IL-13 and IL-5) and Th2-related chemokine [monocyte chemoattractant protein 1 (MCP-1), chemokine (C-C motif) ligand 3 (CCL3) and regulated upon activation normal T cell expressed and secreted (RANTES)] expression. We identified a subset of CD11b(+)CD11c(+)CD49b(+)F4/80(-)Gr-1(-) myeloid cells as a prinicipal source of IL-10-induced IL-13 production. Therefore, the augmented pathological responses observed in our 'delayed' IL-10 over-expression model could be attributed to IL-10 OE alone. Taken together, our study indicated dual roles of IL-10 on RSV-induced lung inflammation which appear to depend upon the timing of when elevated IL-10 is expressed in the lung.

Respiratory syncytial virus and recurrent wheeze in healthy preterm infants

BACKGROUND

Respiratory syncytial virus (RSV) infection is associated with subsequent recurrent wheeze. Observational studies cannot determine whether RSV infection is the cause of recurrent wheeze or the first indication of preexistent pulmonary vulnerability in preterm infants. The monoclonal antibody palivizumab has shown efficacy in preventing severe RSV infection in high-risk infants.

METHODS

In the double-blind, placebo-controlled MAKI trial, we randomly assigned 429 otherwise healthy preterm infants born at a gestational age of 33 to 35 weeks to receive either monthly palivizumab injections (214 infants) or placebo (215 infants) during the RSV season. The prespecified primary outcome was the total number of parent-reported wheezing days in the first year of life. Nasopharyngeal swabs were taken during respiratory episodes for viral analysis.

RESULTS

Palivizumab treatment resulted in a relative reduction of 61% (95% confidence interval, 56 to 65) in the total number of wheezing days during the first year of life (930 of 53,075 days in the RSV-prevention group [1.8%] vs. 2309 of 51,726 days [4.5%] in the placebo group). During this time, the proportion of infants with recurrent wheeze was 10 percentage points lower in patients treated with palivizumab (11% vs. 21%, P=0.01).

CONCLUSIONS

In otherwise healthy preterm infants, palivizumab treatment resulted in a significant reduction in wheezing days during the first year of life, even after the end of treatment. These findings implicate RSV infection as an important mechanism of recurrent wheeze during the first year of life in such infants. (Funded by Abbott Laboratories and by the Netherlands Organization for Health Research and Development; MAKI Controlled Clinical Trials number, ISRCTN73641710.).

Respiratory syncytial virus infection modifies and accelerates pulmonary disease via DC activation and migration

In the present studies, we have established that RSV can elicit a more pathogenic environment dependent on improper DC-associated sensitization. Our initial studies demonstrated that RSV, but not influenza, infection during an allergen exposure into the airway induced a more severe allergen response. The RSV-induced exacerbation included an increased Th2 cytokine response and pathophysiology as monitored by AHR and mucus overproduction. DCs played a central role in the allergen-induced responses, as instilling RSV-infected BMDC into the airway could recapitulate a live virus challenge. With the use of CCR6-/- mice that have a primary defect in the recruitment of mDC subsets, reduced exacerbation of disease was observed when RSV was administered along with allergen. Furthermore, sensitization of mice with RSV-infected BMDC into the airway produced a more severe immune response to a live virus challenge. Subsequently, using RSV-infected BMDC from CCR7-/- mice (that do not migrate efficiently to LNs) to sensitize the exacerbated response demonstrated that the response was dependent on DC migration to the LN. Finally, the ability of RSV-infected DCs to elicit an exacerbated, allergen-induced pathogenic response could be maintained for as long as 3 weeks, suggesting that RSV-infected DCs themselves created an altered immune environment that impacts off-target mucosal responses that could have prolonged effects.

Respiratory syncytial virus infection and chronic respiratory morbidity - is there a functional or genetic predisposition?

A systematic literature review has been undertaken. Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) in infancy is associated with chronic respiratory morbidity. Premorbid abnormal lung function may predispose to RVS LRTI in prematurely born infants.

CONCLUSION

  Single-nucleotide polymorphisms in genes coding for IL-8, IL-19, IL-20, IL-13 mannose-binding lectin, IFNG and a RANTES polymorphism have been associated with subsequent wheeze following RSV LRTI in term-born infants.

Ethical considerations and rationale of the MAKI trial: a multicenter double-blind randomized placebo-controlled trial into the preventive effect of palivizumab on recurrent wheezing associated with respiratory syncytial virus infection in children with a gestational age of 33-35 weeks

BACKGROUND

Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is the most frequent cause of bronchiolitis during infancy. Long-term airway morbidity with recurrent post bronchiolitis wheezing (PBW) episodes, which are probably associated with respiratory infections, occurs in 30 to 70% of infants that were hospitalised with RSV LRTI.

METHODS

We set up a multicenter, placebo-controlled double-blind randomized clinical trial in healthy preterm infants born between 33 and 35 weeks gestational age (WGA). The children received either one-monthly intramuscular palivizumab or placebo injection during the RSV season with a minimum of 2 injections.

RESULTS

The primary objective was to determine the preventive effect of RSV immunoprophylaxis (palivizumab) on the development of recurrent wheezing during the first year of life. The primary outcome measure was the number of wheezing days during the first year of life as obtained by daily logs. As a secondary outcome nasal swabs were taken for viral analysis in case of respiratory symptoms. We will also examine wheezing at age 1, 3 and 6 years both reported by the parents and the general practitioner and quality of life as secondary outcomes. This trial is possible because RSV immunoprophylaxis, although effective in this population, is not completely used in the Netherlands due to its high costs.

CONCLUSION

The Institutional review board (IRB) concluded the study has high clinical relevance because the benefit of 50% chance of protection by palivizumab outweighs the risk of side adverse events due to intramuscular administration of placebo.

Nasopharyngeal prostaglandin E(2) in infant bronchiolitis

The mechanism by which severe bronchiolitis can result in the development of recurrent childhood wheeze is unclear. However, mucosal inflammation and immune activation may play a major role. Prostaglandin (PG) E(2) has been highlighted as a possible therapeutic target for both the treatment of bronchiolitis and the prevention of subsequent airway hyperresponsiveness. The aim of this pilot study was to examine PGE(2) in the airways of infants hospitalised with bronchiolitis. Nasopharyngeal aspirates (NPA) were collected from 18 infants within 12 hours of admission and assayed by enzyme immunoassays for PGE(2), interleukin (IL)-10, and IL-12, as well as cyclooxygenase (COX) 1 and 2 activity. NPA PGE(2) concentration correlated with length of illness preadmission, but was not related to disease severity, causal virus, or IL-10. NPA COX 1 and 2 activity and IL-12 were all below the level of detection. Neither NPA PGE(2) nor disease severity was related to development of recurrent wheeze over 3 years following bronchiolitis. These data suggest that nasopharygeal PGE(2) at hospital admission may be neither directly causal or diagnostic of severity of infant bronchiolitis, or prognostic of development of recurrent wheeze. However, large-cohort temporal examinations are required to adequately define this mediator as a therapeutic target for bronchiolitis.

IL10 family member genes IL19 and IL20 are associated with recurrent wheeze after respiratory syncytial virus bronchiolitis

Mechanisms underlying the increased risk of recurrent wheeze after respiratory syncytial virus lower respiratory tract infection (RSV LRTI) are unclear. Specifically, information about genetic determinants of recurrent wheeze after RSV LRTI is limited. We performed a candidate gene association study to identify genetic determinants of recurrent wheeze after RSV LRTI. We investigated 346 single nucleotide polymorphisms (SNPs) in 220 candidate genes in 166 Dutch infants hospitalized for RSV LRTI. Logistic regression analysis was used to study associations between genotypes and haplotypes and recurrent wheeze after RSV LRTI. We found associations with recurrent wheeze for SNPs in IL19, IL20, MUC5AC, TNFRSF1B, C3, CTLA4, CXCL9, IL4R, and IL7 genes. Haplotype analysis of the combined IL19/IL20 genotyped polymorphisms demonstrated an inverse association between the TGG haplotype and recurrent wheeze after RSV LRTI. IL19 and IL20 genes were notably associated with recurrent wheeze in infants without asthmatic parents. The association of IL20 SNP rs2981573 with recurrent wheeze was confirmed in a healthy birth cohort. We concluded that genetic variation in adaptive immunity genes and particularly in IL19/IL20 genes associates with the development of recurrent wheeze after RSV LRTI, suggesting a role for these IL10 family members in the etiology of airway disease during infancy.

Local interleukin-10 production during respiratory syncytial virus bronchiolitis is associated with post-bronchiolitis wheeze

Background

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis in infants. Following RSV bronchiolitis, 50% of children develop post-bronchiolitis wheeze (PBW). Animal studies have suggested that interleukin (IL)-10 plays a critical role in the pathogenesis of RSV bronchiolitis and subsequent airway hyperresponsiveness. Previously, we showed that ex vivo monocyte IL-10 production is a predictor of PBW. Additionally, heterozygosity of the single-nucleotide polymorphism (SNP) rs1800872 in the IL10 promoter region was associated with protection against RSV bronchiolitis.

Methods

This study aimed to determine the in vivo role of IL-10 in RSV pathogenesis and recurrent wheeze in a new cohort of 235 infants hospitalized for RSV bronchiolitis. IL-10 levels in nasopharyngeal aspirates (NPAs) were measured at the time of hospitalization and the IL10 SNP rs1800872 genotype was determined. Follow-up data were available for 185 children (79%).

Results

Local IL-10 levels during RSV infection turned out to be higher in infants that later developed physician diagnosed PBW as compared to infants without PBW in the first year after RSV infection (958 vs 692 pg/ml, p = 0.02). The IL10 promoter SNP rs1800872 was not associated with IL-10 concentration in NPAs.

Conclusion

The relationship between high local IL-10 levels during the initial RSV infection and physician diagnosed PBW provides further evidence of the importance of the IL-10 response during RSV bronchiolitis.

The role of toll-like receptors in acute and chronic lung inflammation

By virtue of its direct contact with the environment, the lung is constantly challenged by infectious and non-infectious stimuli that necessitate a robust yet highly controlled host response coordinated by the innate and adaptive arms of the immune system. Mammalian Toll-like receptors (TLRs) function as crucial sentinels of microbial and non-infectious antigens throughout the respiratory tract and mediate host innate immunity. Selective induction of inflammatory responses to harmful environmental exposures and tolerance to innocuous antigens are required to maintain tissue homeostasis and integrity. Conversely, dysregulated innate immune responses manifest as sustained and self-perpetuating tissue damage rather than controlled tissue repair. In this article we review aspects of Toll-like receptor function that are relevant to the development of acute lung injury and chronic obstructive lung diseases as well as resistance to frequently associated microbial infections.

Common cold decreases lung function in infants with recurrent wheezing

Background

Common acute viral respiratory infections (colds) are the most frequent cause of exacerbations in infants with recurrent wheezing (RW). However, there is no quantitative information about the effect of colds on the lung function of infants with RW. This study was undertaken to determine the effect of common cold on forced expiratory parameters measured from raised lung volume in infants with RW.

Methods

Spirometric lung function (expiratory flows from raised lung volume) was randomly assessed in 28 infants with RW while they had a common cold and when asymptomatic.

Results

It was found that during colds there was a significant decrease in all forced expiratory parameters and this was much more evident for flows (FEF_50%, FEF_75% and FEF_25–75%) which were definitively abnormal (less than −1.65 z-score) in the majority of infants. There was not association between family asthma, tobacco exposure, and other factors, with the extent of lung function decrease during colds. Tobacco during pregnancy but not a history of family asthma was significantly associated to lower expiratory flows; however, the association was significant only when infants were asymptomatic.

Conclusion

This study shows that common colds cause a marked reduction of lung function in infants with RW.

[Consensus conference on acute bronchiolitis (VI): prognosis of acute bronchiolitis. Review of scientific evidence]

We present a review of the evidence on prognosis of acute bronchiolitis, risk factors for severe forms, symptom or severity scores and risk of post-bronchiolitis asthma. Documented risk factors of long stay or PICU admission in hospitalized patients are: bronchopulmonary dysplasia and/or chronic lung disease, prematurity, congenital heart disease and age less than 3 months. Other less well documented risk factors are: tobacco exposure, history of neonatal mechanical ventilation, breastfeeding for less than 4 months, viral co-infection and other chronic diseases. There are several markers of severity: toxic appearance, tachypnea, hypoxia, atelectasis or infiltrate on chest radiograph, increased breathing effort, signs of dehydration, tachycardia and fever. Although we have some predictive models of severity, none has shown sufficient predictive validity to recommend its use in clinical practice. While there are different symptom or severity scores, none has proven to be valid or accurate enough to recommend their preferable application in clinical practice. There seems to be a consistent and strong association between admission due to bronchiolitis and recurrent episodes of wheezing in the first five years of life. However it is unclear whether this association continues in subsequent years, as there are discordant data on the association between bronchiolitis and asthma.

High incidence of recurrent wheeze in children with down syndrome with and without previous respiratory syncytial virus lower respiratory tract infection

BACKGROUND

Respiratory syncytial virus (RSV)-induced lower respiratory tract infection (LRTI) is associated with the subsequent development of recurrent wheeze. In a recent study, we found a high incidence (9.9%) of hospitalization for RSV-induced LRTI among children with Down syndrome (DS), indicating DS as a new risk factor for RSV-induced LRTI. In the current study we aimed to investigate the development of long-term airway morbidity in children with DS after hospitalization for RSV-induced LRTI.

METHODS

A combined retrospective cohort and prospective birth cohort of children with DS with a history of hospitalization for RSV-induced LRTI was studied (n = 53). Three control populations were included: children with DS without hospitalization for RSV-induced LRTI (n = 110), children without DS but with hospitalization for RSV-induced LRTI (n = 48), and healthy siblings of the previous 3 groups mentioned (n = 49). The primary outcome was physician-diagnosed wheeze up to 2 years of age.

RESULTS

The incidence of physician-diagnosed recurrent wheeze in children with DS with a history of hospitalization for RSV-induced LRTI was 36%. Unexpectedly, up to 30% of children with DS without a history of RSV-induced LRTI had physician-diagnosed recurrent wheeze (no significant difference). In children without DS physician-diagnosed wheeze was found more frequently in children hospitalized for RSV-induced LRTI than healthy controls (31% vs. 8%, P = 0.004).

CONCLUSIONS

In this combined retrospective/prospective cohort study RSV-induced LRTI did not significantly contribute to the risk of recurrent wheeze in children with DS. An unexpected finding was that recurrent wheeze was very common among children with DS.

Effect of dexamethasone on respiratory syncytial virus-induced lung inflammation in children: results of a randomized, placebo controlled clinical trial

Inflammatory mediators play a major role in the pathogenesis of respiratory syncytial virus (RSV) infection. The objective of this study was to evaluate the effect of i.v. dexamethasone on cytokine concentrations in tracheal aspirates (TA) of children with severe RSV disease and to correlate them with disease severity. Twenty-five cytokines were measured in TA obtained from children <2 yr old intubated for severe RSV disease, and enrolled in a double-blind study of i.v. dexamethasone (0.5 mg/kg; n = 22) vs. placebo (n = 19). Cytokine concentrations, measured at baseline and days 1 and 5 post-randomization using a multiplex assay, were compared within both treatment groups and correlated with: (i) tracheal white blood cell counts, (ii) tracheal RSV loads by culture and (iii) parameters of disease severity, including number of days of requirement for mechanical ventilation, intensive care unit (ICU), and hospitalization. At baseline interleukin (IL)-13 and IL-15 concentrations were significantly higher in the dexamethasone treatment group. On day 1 post-treatment, only MCP-1, eotaxin and IL-6 concentrations were significantly different but higher in the placebo group. On day 5: IL-13, IL-7, IL-8 and MIP-1alpha concentrations were higher in dexamethasone-treated patients. In both groups MIP-1beta inversely correlated with the days of ventilator support; MIP-1alpha, MIP-1beta and eotaxin inversely correlated with ICU days; and IL-6 inversely correlated with hospitalization regardless of the treatment assigned. Systemic administration of dexamethasone did not have a consistent effect on TA concentrations of pro-inflammatory cytokines. This may help explain, at least in part, the lack of clinical benefit of steroid treatment in children with severe RSV bronchiolitis.

Effect of variation in RANTES promoter on serum RANTES levels and risk of recurrent wheezing after RSV bronchiolitis in children from Han, Southern China

To investigate the association among RANTES (regulated on activation normal T cell expressed and secreted) gene promoter polymorphism, serum RANTES levels, and recurrent wheezing after RSV (respiratory syncytial virus) bronchiolitis in children (1-12 months of age) from Han, Southern china. Three hundred twenty children with RSV bronchiolitis and 272 controls were enrolled in the 3-year follow-up study. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP), enzyme-linked immunosorbent assay (ELISA) kit and luciferase analysis were the mainly used methods, which were used to genotype the RANTES (-403 G/A), assess the serum RANTES levels and the RANTES promoter activity. As the results showed, the RANTES (-403 G/A) in the promoter region was associated with recurrent wheezing after RSV bronchiolitis (p < 0.05) and serum RANTES levels (RANTES genotype G/G: 26.03 +/- 7.46 ng/ml G/A: 28.22 +/- 6.44 ng/ml A/A: 30.12 +/- 5.88 ng/ml). Functional analyses of RANTES promoter activity indicated that the RANTES (-403 G to A) mutation increases the transcriptional activity of the RANTES promoter. In conclusion, the RANTES (-403 G/A) polymorphism increases RANTES transcriptional activity resulted in a high serum RANTES levels, thus increased the risk of recurrent wheezing after RSV bronchiolitis.

The effect of high dose inhaled corticosteroids on wheeze in infants after respiratory syncytial virus infection: randomised double blind placebo controlled trial

OBJECTIVE

To determine whether early initiated anti-inflammatory therapy with prolonged high dose inhaled glucocorticoids influences the occurrence and severity of recurrent wheeze after respiratory syncytial virus related lower respiratory tract infections.

DESIGN

Randomised double blind placebo controlled trial.

SETTING

Paediatric departments of 19 Dutch clinical centres.

PARTICIPANTS

243 previously healthy infants (126 boys, 117 girls) aged less than 13 months and admitted to hospital with respiratory syncytial virus infection.

INTERVENTIONS

200 mug extra fine hydrofluoroalkane (HFA) beclometasone dipropionate twice daily or matched placebo administered by a pressurised metered dose inhaler and a spacer during the first three months after hospital admission.

MAIN OUTCOME MEASURE

The primary outcome was the number of days with wheeze in the year after the three month intervention period.

RESULTS

Of the 243 eligible infants, 119 were randomised to receive beclometasone and 124 to receive placebo. No significant difference was found in the number of days with wheeze between the two groups (total days, 1761/33 568 in the beclometasone group v 2301/36 556 in the placebo group, P=0.31) and the proportion of infants with wheeze did not differ between the groups (61% in the beclometasone group v 62% in the placebo group, P=0.90). In the predefined subgroup of infants who did not need mechanical ventilation (n=221), beclometasone reduced the number of days with wheeze by 32% (relative reduction in total days, 1315/30 405 in the beclometasone group v 2120/33 149 in the placebo group, P=0.046). This reduction was most pronounced during the first six months of the follow-up year after intervention. The proportion of infants with wheeze did not differ between the groups (59% in the beclometasone group v 60% in the placebo group, P=0.89).

CONCLUSIONS

Early initiated high dose extra fine HFA beclometasone to infants during the first three months after hospital admission for respiratory syncytial virus infection has no major effect on recurrent wheeze. The general use of such treatment during lower respiratory tract infection with respiratory syncytial virus should not be advocated.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN12352714.

Attenuated P2X7 pore function as a risk factor for virus-induced loss of asthma control

RATIONALE

Upper respiratory tract infection is a guideline accepted risk domain for the loss of asthma control. The ionotrophic nucleotide receptor P2X(7) regulates compartmentalized acute inflammation and the immune response to airway pathogens.

OBJECTIVES

We hypothesized that variability in P2X(7) function contributes to neutrophilic airway inflammation during a cold and thereby is linked to acute asthma.

METHODS

Research volunteers with asthma were enrolled at the onset of a naturally occurring cold and monitored through convalescence, assessing symptoms, lung function, and airway inflammation. P2X(7) pore activity in whole blood samples was measured using a genomically validated flow cytometric assay.

MEASUREMENTS AND MAIN RESULTS

Thirty-five participants with mild to moderate allergic asthma were enrolled and 31 completed all visits. P2X(7) pore function correlated with the change in nasal lavage neutrophil counts during the cold (R(s) = 0.514, P = 0.004) and was inversely related to the change in asthma symptoms (R(s) = -0.486, P = 0.009). The change in peak expiratory flow recordings, precold use of inhaled corticosteroids, and P2X(7) pore function were multivariate predictors of asthma symptoms (P = 0.001, < 0.001 and = 0.003 respectively). Attenuated P2X(7) activity was associated with the risk of losing asthma control (crude odds ratio, 11.0; 95% confidence interval, 1.1-106.4) even after adjustment for inhaled corticosteroids and rhinovirus (odds ratio, 15.0).

CONCLUSIONS

A whole blood P2X(7) pore assay robustly identifies participants with loss-of-function genotypes. Using this assay as an epidemiologic tool, attenuated P2X(7) pore activity may be a novel biomarker of virus-induced loss of asthma control.

Relation between serum IL-4, IL-13 and IFN-gamma levels and recurrence of wheezing episodes in infants with acute bronchiolitis

Lower respiratory tract infections are the most important factors among various causes which trigger wheezing in the first year of life. The factors associated with episodic wheezing in children with acute bronchiolitis are still subjects of research. Infections, environmental factors, immunologic mechanisms are sorted as etiologic risk factors of episodic wheezing. We aimed to investigate the relationship between serum interleukin (IL)-4, IL-13 and gamma-interferon (IFN-gamma) levels and recurrence of wheezing episodes in infants with acute bronchiolitis. One hundred twenty infants between 3 and 36 months with acute bronchiolitis enrolled in the study. Personal histories, clinical and laboratory data of infants were recorded. The patients were followed for a year. Venous blood samples were obtained to determine serum IL-4, IL-13, and IFN-gamma levels during acute bronchiolitis episode. The number of wheezing episodes was significantly higher in infants with a positive family history of allergy. A statistically significant correlation was determined between serum IL-13 levels of infants and number of wheezing episodes. High serum IL-13 levels and a positive history of allergy may have important roles in the recurrence of acute bronchiolitis.

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.