Lower respiratory tract infections associated with rhinovirus during infancy and increased risk of wheezing during childhood. A cohort study

Pathogen Profiles in Outpatients with Non-COVID-19 during the 7th Prevalent Period of COVID-19 in Gunma, Japan

The identification of pathogens associated with respiratory symptoms other than the novel coronavirus disease 2019 (COVID-19) can be challenging. However, the diagnosis of pathogens is crucial for assessing the clinical outcome of patients. We comprehensively profiled pathogens causing non-COVID-19 respiratory symptoms during the 7th prevalent period in Gunma, Japan, using deep sequencing combined with a next-generation sequencer (NGS) and advanced bioinformatics technologies. The study included nasopharyngeal swabs from 40 patients who tested negative for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) using immuno-chromatography and/or quantitative reverse transcription polymerase chain reaction (qRT-PCR) methods. Comprehensive pathogen sequencing was conducted through deep sequencing using NGS. Additionally, short reads obtained from NGS were analyzed for comprehensive pathogen estimation using MePIC (Metagenomic Pathogen Identification Pipeline for Clinical Specimens) and/or VirusTap. The results revealed the presence of various pathogens, including respiratory viruses and bacteria, in the present subjects. Notably, human adenovirus (HAdV) was the most frequently detected virus in 16 of the 40 cases (40.0%), followed by coryneforms, which were the most frequently detected bacteria in 21 of the 40 cases (52.5%). Seasonal human coronaviruses (NL63 type, 229E type, HKU1 type, and OC43 type), human bocaviruses, and human herpesviruses (human herpesvirus types 1-7) were not detected. Moreover, multiple pathogens were detected in 50% of the subjects. These results suggest that various respiratory pathogens may be associated with non-COVID-19 patients during the 7th prevalent period in Gunma Prefecture, Japan. Consequently, for an accurate diagnosis of pathogens causing respiratory infections, detailed pathogen analyses may be necessary. Furthermore, it is possible that various pathogens, excluding SARS-CoV-2, may be linked to fever and/or respiratory infections even during the COVID-19 pandemic.

Risk Factors Affecting Development and Persistence of Preschool Wheezing: Consensus Document of the Emilia-Romagna Asthma (ERA) Study Group

Wheezing at preschool age (i.e., before the age of six) is common, occurring in about 30% of children before the age of three. In terms of health care burden, preschool children with wheeze show double the rate of access to the emergency department and five times the rate of hospital admissions compared with school-age asthmatics. The consensus document aims to analyse the underlying mechanisms involved in the pathogenesis of preschool wheezing and define the risk factors (i.e., allergy, atopy, infection, bronchiolitis, genetics, indoor and outdoor pollution, tobacco smoke exposure, obesity, prematurity) and the protective factors (i.e., probiotics, breastfeeding, vitamin D, influenza vaccination, non-specific immunomodulators) associated with the development of the disease in the young child. A multidisciplinary panel of experts from the Emilia-Romagna Region, Italy, addressed twelve key questions regarding managing preschool wheezing. Clinical questions have been formulated by the expert panel using the PICO format (Patients, Intervention, Comparison, Outcomes). Systematic reviews have been conducted on PubMed to answer these specific questions and formulate recommendations. The GRADE approach has been used for each selected paper to assess the quality of the evidence and the degree of recommendations. Based on a panel of experts and extensive updated literature, this consensus document provides insight into the pathogenesis, risk and protective factors associated with the development and persistence of preschool wheezing. Undoubtedly, more research is needed to improve our understanding of the disease and confirm the associations between certain factors and the risk of wheezing in early life. In addition, preventive strategies must be promoted to avoid children's exposure to risk factors that may permanently affect respiratory health.

Wheezing-Related Relevant Factors and the Role of Viral Bronchiolitis

Bronchiolitis is a virus-associated infection of the lower respiratory tract exhibiting signs and symptoms of airway obstruction. Respiratory Syncytial Virus (RSV) is responsible in most cases; however, different rhinoviruses have also been implicated. Specific viruses and time until the first infection, severity of the respiratory condition, and atopic status have a determinant role in the recurrence of wheezing and asthma development. Genetics, lung function, atopic condition, the role of microbiota and environment, pollution, and obesity are considered in the present review. Emergency room visits and hospitalizations because of severe wheezing and smoking during pregnancy among others were identified as risk factors for significant morbidity in our population. Approaching determinant conditions like genetics, allergy, antiviral immunity, and environmental exposures such as farm vs. urban and viral virulence provides an opportunity to minimize morbidity of viral illness and asthma in children.

Risk factors and prognosis of recurrent wheezing in Chinese young children: a prospective cohort study

Background

Nearly all the investigations into the risk factors for wheezing and asthma were conducted in developed countries with a high prevalence rate of asthma and allergy, but the studies in developing countries are limited. In this study, we aimed to investigate the risk factors for different wheezing phenotypes in Chinese young children and to explore the prognosis of recurrent wheezing.

Methods

This cohort study contained the recruitment stage and the follow-up stage conducted by phone questionnaire survey. According to the information collected at the follow-up for wheezing episodes and remission age, our cohort was divided into transient wheezing, persistent wheezing and late-onset wheezing. The wheezing symptoms and potential risk factors were compared between these three wheezing groups.

Results

From the initial 109 participants, 78.0% completed the follow-up survey. The frequency of current wheezing at followup was significantly reduced in all three groups compared to the recruitment stage (p < 0.01). We observe a trend that the rhinovirus (RV) and respiratory syncytial virus (RSV) infection rates were higher in the persistent wheezing group, and the overall infection rates appear to be the lowest in late-onset wheezing group at recruitment. At follow-up stage, the rates of rhinitis ever and current rhinitis were both higher in the persistent wheezing (63.0%, 50.0%) and late-onset wheezing groups (88.2%, 58.8%), compared to the transient wheezing group (14.3%, 14.3%). The incidence of current wheezing episodes increased cumulatively if the participant had concomitant risk factors of rhinitis ever, aeroallergens sensitization at recruitment, either alone or together with previous RV infection at the time of recruitment.

Conclusion

While the incidence of wheezing declined overall with age, but in addition to transient wheezers, additional subsets of children manifest persistent wheeze or late onset wheeze, and moreover the risk factors for wheezing display phenotypic variability between these subgroups. Rhinitis ever and aeroallergens sensitization, either alone or together with previous RV infection, were the most significant predictors for persistent wheezing in children in an eastern environment, such as in China.

Single-Cell Tracking Reveals a Role for Pre-Existing CCR5+ Memory Th1 Cells in the Control of Rhinovirus-A39 After Experimental Challenge in Humans

Background

Little is known about T cells that respond to human rhinovirus in vivo, due to timing of infection, viral diversity, and complex T-cell specificities. We tracked circulating CD4+ T cells with identical epitope specificities that responded to intranasal challenge with rhinovirus (RV)-A39, and we assessed T-cell signatures in the nose.

Methods

Cells were monitored using a mixture of 2 capsid-specific major histocompatibility complex II tetramers over a 7-week period, before and after RV-A39 challenge, in 16 human leukocyte antigen-DR4+ subjects who participated in a trial of Bifidobacterium lactis (Bl-04) supplementation.

Results

Pre-existing tetramer+ T cells were linked to delayed viral shedding, enriched for activated CCR5+ Th1 effectors, and included a minor interleukin-21+ T follicular helper cell subset. After RV challenge, expansion and activation of virus-specific CCR5+ Th1 effectors was restricted to subjects who had a rise in neutralizing antibodies, and tetramer-negative CCR5+ effector memory types were comodulated. In the nose, CXCR3-CCR5+ T cells present during acute infection were activated effector memory type, whereas CXCR3+ cells were central memory type, and cognate chemokine ligands were elevated over baseline. Probiotic had no T-cell effects.

Conclusions

We conclude that virus-specific CCR5+ effector memory CD4+ T cells primed by previous exposure to related viruses contribute to the control of rhinovirus.

The role of respiratory tract infections and the microbiome in the development of asthma: A narrative review

Asthma is a common disease in childhood, and might predispose for chronic obstructive respiratory morbidity in adolescence and adulthood. Various early-life risk factors might influence the risk of wheezing, asthma, and lower lung function in childhood. Cohort studies demonstrated that lower respiratory tract infections in the first years of life are associated with an increased risk of wheezing and asthma, while the association with lung function is less clear. Additionally, the gut and airway microbiome might influence the risk of wheezing and asthma. The interaction between respiratory tract infections and the microbiome complicates studies of their associations with wheezing, asthma, and lung function. Furthermore, the causality behind these observations is still unclear, and several other factors such as genetic susceptibility and the immune system might be of importance. This review is focused on the association of early-life respiratory tract infections and the microbiome with wheezing, asthma, and lung function, it is possible influencing factors and perspectives for future studies.

Clinical and epidemiological profiles including meteorological factors of low respiratory tract infection due to human rhinovirus in hospitalized children

BACKGROUND

Lower respiratory tract infection (LRTI) is a major cause of morbidity and mortality in children. Human rhinovirus (HRV) is confirmed to be associated with pediatric lower respiratory tract infection. Seasonal and meteorological factors may play a key role in the epidemiology of HRV. The purposes of this study were to investigate the frequency, seasonal distribution, and clinical characteristics of hospitalized children with LRTI caused by HRVs. In addition, associations between incidence of HRVs and meteorological factors in a subtropical region of China were discussed.

METHODS

Hospitalized children <14 years old admitted to the Respiratory Department of the Children's Hospital, which is affiliated to Soochow University, between January 1, 2013 and December 31, 2015, were enrolled in this study. Multi-pathogens were detected in nasopharyngeal aspirate samples. Meanwhile, meteorological factors were recorded.

RESULTS

The average incidence of HRVs infection was 11.4% (707/6194) and 240 cases of which were co-infection cases with other pathogens. Children with co-infection presented more frequent fever and tachypnea compared to children infected with HRVs only (both P < 0.05). Among 707 HRV positive children, the mean age was 23.2 months (range 1 to 140 months). Among all respiratory infections, the highest incidence of HRVs cases occurred in children age 13-36 months old (15.1%, 203/1341). Of all 228 HRV cases in 2014, 85 cases (37.3%) were HRV-C positive. HRVs and HRV-C infection occurred throughout the year during the study period, although a higher incidence was observed in summer and autumn seasons. HRVs or HRV-C incidence in hospitalized children with LRTI was associated with the monthly mean temperature (both P < 0.05).

CONCLUSION

HRV was one of the most common viral pathogen detected in hospitalized children with LRTI at the Children's Hospital of Suzhou, China, and had its own seasonal distribution including HRV-C, which was partly caused by temperature.

Circulating Memory CD4+ T Cells Target Conserved Epitopes of Rhinovirus Capsid Proteins and Respond Rapidly to Experimental Infection in Humans

Rhinovirus (RV) is a major cause of common cold and an important trigger of acute episodes of chronic lung diseases. Antigenic variation across the numerous RV strains results in frequent infections and a lack of durable cross-protection. Because the nature of human CD4⁺ T cells that target RV is largely unknown, T cell epitopes of RV capsid proteins were analyzed, and cognate T cells were characterized in healthy subjects and those infected by intranasal challenge. Peptide epitopes of the RV-A16 capsid proteins VP1 and VP2 were identified by peptide/MHC class II tetramer-guided epitope mapping, validated by direct ex vivo enumeration, and interrogated using a variety of in silico methods. Among noninfected subjects, those circulating RV-A16-specific CD4⁺ T cells detected at the highest frequencies targeted 10 unique epitopes that bound to diverse HLA-DR molecules. T cell epitopes localized to conserved molecular regions of biological significance to the virus were enriched for HLA class I and II binding motifs, and constituted both species-specific (RV-A) and pan-species (RV-A, -B, and -C) varieties. Circulating epitope-specific T cells comprised both memory Th1 and T follicular helper cells, and were rapidly expanded and activated after intranasal challenge with RV-A16. Cross-reactivity was evidenced by identification of a common *0401-restricted epitope for RV-A16 and RV-A39 by tetramer-guided epitope mapping and the ability for RV-A16-specific Th1 cells to proliferate in response to their RV-A39 peptide counterpart. The preferential persistence of high-frequency RV-specific memory Th1 cells that recognize a limited set of conserved epitopes likely arises from iterative priming by previous exposures to different RV strains.

Pediatric Asthma and Viral Infection

Respiratory viral infections, particularly respiratory syncytial virus (RSV) and rhinovirus, are the most importance risk factors for the onset of wheezing in infants and small children. Bronchiolitis is the most common acute respiratory infection in children under 1year of age, and the most common cause of hospitalization in this age group. RSV accounts for approximately 70% of all these cases, followed by rhinovirus, adenovirus, metapneumovirus and bocavirus. The association between bronchiolitis caused by RSV and the development of recurrent wheezing and/or asthma was first described more than 40years ago, but it is still unclear whether bronchiolitis causes chronic respiratory symptoms, or if it is a marker for children with a genetic predisposition for developing asthma in the medium or long term. In any case, sufficient evidence is available to corroborate the existence of this association, which is particularly strong when the causative agent of bronchiolitis is rhinovirus. The pathogenic role of respiratory viruses as triggers for exacerbations in asthmatic patients has not been fully characterized. However, it is clear that respiratory viruses, and in particular rhinovirus, are the most common causes of exacerbation in children, and some type of respiratory virus has been identified in over 90% of children hospitalized for an episode of wheezing. Changes in the immune response to viral infections in genetically predisposed individuals are very likely to be the main factors involved in the association between viral infection and asthma.

Pediatric Asthma and Viral Infection

Respiratory viral infections, particularly respiratory syncytial virus (RSV) and rhinovirus, are the most importance risk factors for the onset of wheezing in infants and small children. Bronchiolitis is the most common acute respiratory infection in children under 1 year of age, and the most common cause of hospitalization in this age group. RSV accounts for approximately 70% of all these cases, followed by rhinovirus, adenovirus, metapneumovirus and bocavirus. The association between bronchiolitis caused by RSV and the development of recurrent wheezing and/or asthma was first described more than 40 years ago, but it is still unclear whether bronchiolitis causes chronic respiratory symptoms, or if it is a marker for children with a genetic predisposition for developing asthma in the medium or long term. In any case, sufficient evidence is available to corroborate the existence of this association, which is particularly strong when the causative agent of bronchiolitis is rhinovirus.

The pathogenic role of respiratory viruses as triggers for exacerbations in asthmatic patients has not been fully characterized. However, it is clear that respiratory viruses, and in particular rhinovirus, are the most common causes of exacerbation in children, and some type of respiratory virus has been identified in over 90% of children hospitalized for an episode of wheezing. Changes in the immune response to viral infections in genetically predisposed individuals are very likely to be the main factors involved in the association between viral infection and asthma.

Prevention of Influenza Virus-Induced Immunopathology by TGF-β Produced during Allergic Asthma

Asthma is believed to be a risk factor for influenza infection, however little experimental evidence exists to directly demonstrate the impact of asthma on susceptibility to influenza infection. Using a mouse model, we now report that asthmatic mice are actually significantly more resistant to a lethal influenza virus challenge. Notably, the observed increased resistance was not attributable to enhanced viral clearance, but instead, was due to reduced lung inflammation. Asthmatic mice exhibited a significantly reduced cytokine storm, as well as reduced total protein levels and cytotoxicity in the airways, indicators of decreased tissue injury. Further, asthmatic mice had significantly increased levels of TGF-β1 and the heightened resistance of asthmatic mice was abrogated in the absence of TGF-β receptor II. We conclude that a transient increase in TGF-β expression following acute asthma can induce protection against influenza-induced immunopathology.

Influenza and asthma represent the two major lung diseases in humans. While most studies have focused on exacerbation of asthma symptoms by influenza virus infection, the effects of asthma on susceptibility to influenza virus infections has been far less studied. Using a novel mouse model of asthma and influenza infection, we show that asthmatic mice are highly resistant to primary challenge with the 2009 influenza pandemic strain (CA04) compared to non-asthmatic mice. The increased resistance of asthmatic mice is not due to the enhanced T or B cell immunity but rather, to a strong anti-inflammatory TGF-beta response triggered by asthma. This study is the first to provide a mechanistic explanation for asthma-mediated protection during the 2009 influenza pandemic.

Infant respiratory infections and later respiratory hospitalisation in childhood

Acute respiratory infections (ARI) cause significant morbidity in infancy. We sought to quantify the relationship between ARI and development of respiratory morbidity in early childhood. Population-based longitudinal hospitalisation data were linked to perinatal, birth and death records for 145,580 Western Australian children from 1997 to 2002. We conducted Cox regression with sensitivity analyses to quantify the risk of recurrent ARI in infancy for respiratory hospitalisation after the age of 3 years. ARI in infancy was significantly related to respiratory hospitalisation before (hazard ratio (HR) 3.5, 95% CI 3.1-3.8) and after (HR 3.0, 95% CI 2.6-3.4) adjusting for known risk factors including maternal smoking during pregnancy, season of birth, delivery mode and gestational age. We noted a dose response with the number and length of infant ARI hospitalisations and increasing risk with no effect modification by gestational age. Results were similar when later respiratory hospitalisations were restricted to asthma hospitalisations only. Recurrent hospitalisations for ARI in infancy significantly increase the risk of respiratory morbidity and asthma requiring hospitalisation after the age of 3 years in a dose-response fashion. The increase in relative risk is not modified by gestational age. Efforts to reduce the occurrence of infant ARI are likely to have significant public health benefits.

Clinical risk factors associated with the development of wheezing in children less than 2 years of age who required hospitalization for viral lower respiratory tract infections

Purpose

Wheezing following viral lower respiratory tract infections (LRTIs) in children <2 years of age is an important risk factor for the development of asthma later in life; however, not all children with viral LRTIs develop wheezing. This study investigated risk factors for the development of wheezing during viral LRTIs requiring hospitalization.

Methods

The study included 142 children <2 years of age hospitalized for LRTIs with at least one virus identified as the cause and classified them into children diagnosed with LRTIs with wheezing (n=70) and those diagnosed with LRTIs without wheezing (n=72).

Results

There were no significant differences in the viruses detected between the two groups. Multivariate logistic regression analysis showed that, after adjusting for potentially confounding variables including sex and age, the development of wheezing was strongly associated with parental history of allergic diseases (adjusted odds ratio [aOR], 20.19; 95% confidence interval [CI], 3.22-126.48), past history of allergic diseases (aOR, 13.95; 95% CI, 1.34-145.06), past history of hospitalization for respiratory illnesses (aOR, 21.36; 95% CI, 3.77-120.88), exposure to secondhand smoke at home (aOR, 14.45; 95% CI, 4.74-44.07), and total eosinophil count (aOR, 1.01; 95% CI, 1.01-1.02).

Conclusion

Past and parental history of allergic diseases, past history of hospitalization for respiratory illnesses, exposure to secondhand smoke at home, and total eosinophil count were closely associated with the development of wheezing in children <2 years of age who required hospitalization for viral LRTIs. Clinicians should take these factors into consideration when treating, counseling, and monitoring young children admitted for viral LRTIs.

Inflammation and infections in asthma

INTRODUCTION

Asthma is driven by an inflammatory response against normally harmless environmental inorganic and organic compounds in the respiratory tract. Immune responses to airborne pathogens such as viruses and bacteria may reduce the allergic responses but are also known to trigger asthma attacks and eventually lead to severe disease condition.

OBJECTIVE

To investigate the role of respiratory pathogens concerning the induction or protection against acute or chronic asthma manifestations.

METHODS

We included 131 articles for the final review according to their relevance with the subject.

RESULTS

There is apparently contradictory interaction of respiratory germs in the airways of asthmatics which may be protective on one angle but deleterious on the other.

CONCLUSION

The relationship between inflammation and remodeling and the pathogenic role of viral and bacterial infection in the airways of asthmatic patients is still highly debatable and incompletely understood.

[Value of routine identification of respiratory infectious agents in children hospitalized with an acute asthma exacerbation]

Introduction

Chez l’enfant les exacerbations d’asthme sont le plus souvent déclenchées par une infection respiratoire. L’objectif de cette étude était d’évaluer l’intérêt de l’identification des pathogènes respiratoires chez les enfants hospitalisés pour une exacerbation d’asthme.

Patients et méthodes

Il s’agit d’une étude rétrospective incluant tout enfant hospitalisé pour une exacerbation d’asthme dans notre unité entre janvier 2010 et décembre 2011 et analysant la prescription des examens microbiologiques, leurs indications, leur rendement, leur impact sur la prise en charge médicale et leur coût.

Résultats

Cent quatre-vingt-dix-sept enfants ont été inclus. Une recherche d’agent pathogène respiratoire avait été réalisée chez 157 enfants (79,7 %), surtout en cas d’infection oto-rhino-laryngologique (ORL), d’hypoxémie ou de pneumonie. Un virus avait été identifié chez 30 (23,8 %) des 126 enfants prélevés. Les analyses bactériologiques avaient eu un rendement faible puisque seulement 3,2 % des analyses par amplification génique (PCR) pour Mycoplasma pneumoniae avaient été positives (n = 4/125). Aucune autre bactérie n’avait été identifiée. Aucun lien n’a pu être établi entre les résultats microbiologiques et la gravité de l’exacerbation. La prise en charge thérapeutique avait été peu modifiée par ces résultats. Le coût global avait été de plus de 40 400 euros pour les 2 ans d’étude.

Conclusion

D’après nos résultats la recherche de pathogènes respiratoires au cours des exacerbations d’asthme a un intérêt modéré en dehors de l’aspect épidémiologique. L’impact du rhinovirus, du coronavirus, du bocavirus et de l’entérovirus, non recherchés en routine hospitalière, reste cependant à préciser.

Viral infections and asthma: an inflammatory interface?

Asthma is a chronic inflammatory disease of the airways in which the majority of patients respond to treatment with corticosteroids and β₂-adrenoceptor agonists. Acute exacerbations of asthma substantially contribute to disease morbidity, mortality and healthcare costs, and are not restricted to patients who are not compliant with their treatment regimens. Given that respiratory viral infections are the principal cause of asthma exacerbations, this review article will explore the relationship between viral infections and asthma, and will put forward hypotheses as to why virus-induced exacerbations occur. Potential mechanisms that may explain why current therapeutics do not fully inhibit virus-induced exacerbations, for example, β₂-adrenergic desensitisation and corticosteroid insensitivity, are explored, as well as which aspects of virus-induced inflammation are likely to be attenuated by current therapy.

The use of a multiplex real-time PCR assay for diagnosing acute respiratory viral infections in children attending an emergency unit

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Evaluate the use of multiplex real-time PCR for diagnosing respiratory infections.

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857/966 samples from 914 children were positive for one or multiple viruses.

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Respiratory syncytial virus and rhinovirus were the most prevalent.

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Co-infections were associated with severe respiratory symptoms.

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The spread of respiratory viruses returned to the one it was before the flu outbreak.

Background

The use of a multiplex molecular technique to identify the etiological pathogen of respiratory viral infections might be a support as clinical signs are not characteristic.

Objectives

The aim of the study was to evaluate a multiplex molecular real-time assay for the routine diagnosis of respiratory viruses, to analyze the symptoms associated with the pathogens detected and to determine the spread of virus during the period.

Study design

Respiratory samples were collected from children presenting with respiratory symptoms and attending the emergency unit during the 2010–2011 winter seasons. Samples were tested with the multiplex RespiFinder^® 15 assay (PathoFinder™) which potentially detects 15 viruses.

Results

857 (88.7%) of the 966 samples collected from 914 children were positive for one (683 samples) or multiple viruses (174 samples). The most prevalent were the respiratory syncytial virus (39.5%) and the rhinovirus (24.4%). Influenza viruses were detected in 139 (14.4%) samples. Adenovirus was detected in 93 (9.6%) samples, coronaviruses in 88 (9.1%), metapneumovirus in 51 (5.3%) and parainfluenzae in 47 (4.9%). Rhinovirus (40%) was the most prevalent pathogen in upper respiratory tract infections while respiratory syncytial virus (49.9%) was the most prevalent in lower respiratory tract infections. Co-infections were associated with severe respiratory symptoms.

Conclusion

The multiplex assay detected clinically important viruses in a single genomic test and thus will be useful for detecting several viruses causing respiratory tract disorders.

Pharmacological approach to wheezing in preschool children

INTRODUCTION

Wheezing disorders are very common during childhood (particularly among preschool children), and represent a significant burden for patients, their families, the healthcare system, and society as a whole. Identifying wheezing phenotypes, and recognizing the risk factors associated with each, may help to predict long-term outcomes, distinguish high-risk children who may benefit from secondary prevention measures, and ensure that the most effective therapy is prescribed for each case.

AREAS COVERED

The main aim of this review is to analyze the characteristics of the drugs currently used to treat wheezing in preschool children, and discuss the results obtained in children with different wheezing phenotypes.

EXPERT OPINION

The continuous or intermittent administration of various oral or inhaled drugs could theoretically be effective in preventing or controlling wheezing in preschool children. However, the optimal management of acute preschool wheezing episodes has not yet been determined mainly because of their phenotypical heterogeneity.

A Review of the CD4+ T Cell Contribution to Lung Infection, Inflammation and Repair with a Focus on Wheeze and Asthma in the Pediatric Population

Childhood asthma and wheezing are very common, especially in those born preterm. Genetic and environmental factors are associated with developing asthma and wheezing. Respiratory syncytial virus and rhinovirus infections have been implicated in playing a causal role in the development of childhood asthma and wheezing, perhaps by altering the development of the immune system. Several subtypes of asthma and wheezing have been described which involve different mechanisms of pathophysiology. Much of the recent work in the field of asthma research has focused on describing unique aspects of these disease subtypes, which could lead to new drug targets. Alterations in CD4+ T cells have been described with alterations in the T helper 1, 2, 17 and regulatory cell balance could provide valuable targets for the development of new treatment strategies for the various subtypes of disease. This review article focuses on factors involved in childhood asthma and wheeze and potential drug targets.