Macronutrients during Pregnancy and Life-Threatening Respiratory Syncytial Virus Infections in Children

A maternal high-fat diet predisposes to infant lung disease via increased neutrophil-mediated IL-6 trans-signaling

A poor maternal diet during pregnancy predisposes the infant to severe lower respiratory tract infections (sLRIs), which, in turn, increases childhood asthma risk; however, the underlying mechanisms remain poorly understood. Here, we show that the offspring of high-fat diet (HFD)-fed mothers (HFD-reared pups) developed an sLRI following pneumovirus inoculation in early life and subsequent asthma in later life upon allergen exposure. Prior to infection, HFD-reared pups developed microbial dysbiosis and low-grade systemic inflammation (LGSI), characterized by hyperneutropoiesis in the liver and elevated inflammatory cytokine expression, most notably granulocyte-colony stimulating factor (G-CSF), interleukin-17A (IL-17A), IL-6 and soluble IL-6 receptor (sIL-6R) (indicative of IL-6 trans-signaling) in the circulation and multiple organs but most prominently the liver. Inhibition of IL-6 trans-signaling using sgp130Fc transgenic mice or via specific genetic deletion of IL-6Ra on neutrophils conferred protection against both diseases. Taken together, our findings suggest that a maternal HFD induces neonatal LGSI that predisposes to sLRI and subsequent asthma via neutrophil-mediated IL-6 trans-signaling.

Respiratory syncytial virus burden in children under 2 years old in understudied areas worldwide: gap analysis of available evidence, 2012-2022

Background

We evaluated published evidence (2012-2022) on pediatric RSV burden in 149 countries within World Health Organization (WHO) regions of Africa (AFRO), Americas (AMRO, excluding Canada and the USA), Eastern Mediterranean (EMRO), Europe (EURO, excluding European Union countries and the UK), Southeast Asia (SEARO), and Western Pacific (WPRO, excluding Australia, China, Japan, New Zealand, and South Korea).

Methods

Gap analysis on RSV-associated disease (hospitalizations, hospital course, mortality or case fatality, detection, and incidence) in children ≤2 years old, where hospitalization rates, hospital course, mortality rate, case fatality rate (CFR), and postmortem detection rates were summarized, by region, for each country.

Results

Forty-two publications were identified covering 19% of included countries in AFRO, 18% in AMRO, 14% in EMRO, 15% in EURO, 18% in SEARO, and 13% in WPRO. Methods, case definitions, and age groups varied widely across studies. Of these 42 publications, 25 countries reported hospitalization rate, hospital course, mortality rate, CFR, and/or postmortem detection rate. RSV hospitalization rate (per 1,000 children per year/child-years) was higher among ≤3-month-olds (range, 38 in Nicaragua to 138 in the Philippines) and ≤6-month-olds (range, 2.6 in Singapore to 70 in South Africa) than in 1-2-year-olds (from 0.7 in Guatemala to 19 in Nicaragua). Based on 11 studies, in AFRO (South Africa), AMRO (Chile and Mexico), EMRO (Lebanon and Jordan), EURO (Israel and Turkey), and SEARO (India), hospitalized children ≤2 years old remained hospitalized for 3-8 days, with 9%-30% requiring intensive care and 4%-26% needing mechanical ventilation. Based on a study in India, community-based CFR was considerably higher than that in the hospital (9.1% vs. 0% in ≤3-month-olds; 7.1% vs. 2.8% in ≤6-month-olds).

Conclusions

National and regional heterogeneity of evidence limits estimates of RSV burden in ≤2-year-olds in many WHO region countries, where further country-specific epidemiology is needed to guide prioritization, implementation, and impact assessment of RSV prevention strategies.

Antibody levels against respiratory syncytial virus fusion protein conformations and lack of association with life-threatening infection in previously healthy infants

BACKGROUND

Humoral immune response against the pre-fusion (pre-F) conformation of respiratory syncytial virus (RSV) F protein has been proposed to play a protective role against infection. An RSV pre-F maternal vaccine has been recently approved in several countries to protect young infants against RSV. We aimed to assess serum IgG titers against the pre-F and post-F conformations of RSV F protein and their association with life-threatening RSV disease (LTD) in previously healthy infants.

METHODS

A prospective cohort study including hospitalized infants <12 months with a first RSV infection was conducted during 2017-2019. Patients with LTD required intensive care and mechanical respiratory assistance. RSV pre-F exclusive and post-F antibody responses were determined by post-F competition and non-competition immunoassays, respectively, and neutralizing activity was measured by plaque reduction neutralization test.

RESULTS

Fifty-eight patients were included; the median age was 3.5 months and 41 % were females. Fifteen patients developed LTD. RSV F-specific antibody titers positively correlated with neutralizing antibody titers in acute and convalescent phases but, importantly, they did not associate with LTD. Acute RSV pre-F exclusive and post-F IgG titers negatively correlated with patient age (P = 0.0007 and P < 0.0001), while a positive correlation was observed between the fold changes in RSV F-specific antibody titers between convalescent and acute phase and patient age (P = 0.0014 and P < 0.0001). Infants ≤2 months exhibited significantly lower fold-changes in RSV F-specific and neutralizing antibody titers between convalescence and acute phase than older infants. Additionally, acute RSV antibody titers showed no correlation with nasal RSV load and, furthermore, nasal viral load was not associated with the development of LTD.

CONCLUSIONS

This study highlights that protection against life-threatening RSV disease is not necessarily antibody-dependent. Further characterization of the immune response against RSV and its role in protection against severe disease is important for the development of the safest possible preventive strategies.

The gut-airway microbiome axis in health and respiratory diseases

Communication between the gut and remote organs, such as the brain or the cardiovascular system, has been well established and recent studies provide evidence for a potential bidirectional gut-airway axis. Observations from animal and human studies indicate that respiratory insults influence the activity of the gut microbiome and that microbial ligands and metabolic products generated by the gut microbiome shape respiratory immunity. Information exchange between these two large mucosal surface areas regulates microorganism-immune interactions, with significant implications for the clinical and treatment outcomes of a range of respiratory conditions, including asthma, chronic obstructive pulmonary disease and lung cancer. In this Review, we summarize the most recent data in this field, offering insights into mechanisms of gut-airway crosstalk across spatial and temporal gradients and their relevance for respiratory health.

CXCR3+ effector regulatory T cells associate with disease tolerance during lower respiratory pneumovirus infection

Lifestyle factors like poor maternal diet or antibiotic exposure disrupt early life microbiome assembly in infants, increasing the risk of severe lower respiratory infections (sLRI). Our prior studies in mice indicated that a maternal low-fibre diet (LFD) exacerbates LRI severity in infants by impairing recruitment of plasmacytoid dendritic cells (pDC) and consequently attenuating expansion of lung regulatory T (Treg) cells during pneumonia virus of mice (PVM) infection. Here, we investigated whether maternal dietary fibre intake influences Treg cell phenotypes in the mediastinal lymph nodes (mLN) and lungs of PVM-infected neonatal mice. Using high dimensional flow cytometry, we identified distinct clusters of regulatory T cells (Treg cells), which differed between lungs and mLN during infection, with notably greater effector Treg cell accumulation in the lungs. Compared to high-fibre diet (HFD)-reared pups, frequencies of various effector Treg cell subsets were decreased in the lungs of LFD-reared pups. Particularly, recruitment of chemokine receptor 3 (CXCR3+) expressing Treg cells was attenuated in LFD-reared pups, correlating with lower lung expression of CXCL9 and CXCL10 chemokines. The recruitment of this subset in response to PVM infection was similarly impaired in pDC depleted mice or following anti-CXCR3 treatment, increasing immunopathology in the lungs. In summary, PVM infection leads to the sequential recruitment and expansion of distinct Treg cell subsets to the lungs and mLN. The attenuated recruitment of the CXCR3+ subset in LFD-reared pups increases LRI severity, suggesting that strategies to enhance pDCs or CXCL9/CXCL10 expression will lower immune-mediated pathogenesis.

MUC5AC: A potential biomarker of severity in pediatric patients infected with influenza

Numerous factors can increase the risk of severe influenza; however, a majority of severe cases occur in previously healthy children. Identification of high-risk children is important for targeted preventive interventions and prompt treatment. The aim of this study was to evaluate MUC5AC as a biomarker for influenza disease severity in children. For this, a prospective cohort study was conducted in 2019. Children hospitalized with acute respiratory infection (ARI) with confirmed positive influenza infection were enrolled. Influenza cases were identified by reverse transcriptase-polymerase chain reaction. Life-threatening disease (LTD) was defined by the need for intensive care and ventilatory support. MUC5AC, epidemiologic, and clinical risk factors were assessed. Three hundred and forty-two patients were hospitalized with ARI, of which 49 (14%) had confirmed influenza infection and 6 (12%) of them developed LTD. MUC5AC levels were higher in those patients with mild disease compared to cases with poorer outcomes. Our results show that the severity of influenza infection in children is significantly associated with low levels of MUC5AC. These findings suggest its potential as a suitable biomarker for predicting disease severity.

Assessing the long-term economic impact of wheezing episodes after severe RSV disease in children from Argentina: a cost of illness analysis

Introduction

There is lack of available data on the economic burden of wheezing episodes after severe respiratory syncytial virus (RSV) infection. This study aimed to assess the cost incurred for wheezing episodes after a severe RSV infection in children from Argentina, considering both the public health system and societal perspectives.

Methods

A prospective cohort was conducted from 2014 to 2022 to assess the cost of illness of wheezing episodes after severe RSV disease in children from Buenos Aires, Argentina. Direct medical and non-medical costs were estimated, along with indirect costs per episode and patient. Data pertaining to healthcare resource utilisation, indirect expenses and parental out-of-pocket costs were obtained. The overall cost per hospitalisation and health visits was calculated. Costs were quantified in US dollars using the average exchange rate on the specific date of data collection.

Results

A total of 256 infants experienced severe RSV disease during their first year of life and were followed over a 5-year period in Buenos Aires. Overall, 150 children between 12 and 60 months presented 429 wheezing episodes. The median number of wheezing episodes per patient was 5 (IQR 3-7). The mean cost per wheezing episode was US$191.01 (95% CI 166.37 to 215.64). The total cost per episode of wheezing was significantly higher (p<0.001) in infants under 12 months of age (207.43, 95% CI 154.3 to 260.6) compared with older toddler. The average cumulative cost associated to wheezing per patient was US$415.99 (95% CI 313.35 to 518.63). Considering both acute RSV disease and long-term wheezing outcomes, the cumulative mean cost per patient was US$959.56 (95% CI 832.01 to 1087.10).

Conclusions

This study reveals the economic impact of prolonged wheezing resulting from severe acute RSV infection on Argentina's public health system and society. The estimates obtained serve as valuable inputs for informing cost-effectiveness analyses of upcoming RSV preventive interventions.

Addressing global health disparities in the management of RSV infection in infants and children: Strategies for preventing bronchiolitis and post-bronchiolitis recurrent wheezing

Background: The topic of equitable access to health care and its impact on exacerbating worldwide inequities in child health not only strikes at the heart of our health-care delivery systems but also deeply resonates with our collective social consciences. Nowhere is this better seen on a global scale than in the burden of illness caused by respiratory syncytial virus (RSV) infection, which extracts the most severe morbidity and mortality in infants and children in low- and middle-income countries (LMIC). This report addresses global health disparities that exist in the management of RSV infection in infants and children, and offers strategies for preventing bronchiolitis and postbronchiolitis recurrent wheezing in LMICs. Methods: A systematic literature review was conducted across the PubMed data bases of RSV infection and the socioeconomic impact of bronchiolitis and postbronchiolitis recurrent wheezing in LMICs. Results: The results of the present study address the many issues that deal with the question if prevention of RSV bronchiolitis can mitigate recurrent wheezing episodes and links RSV risks, downstream effects, prevention, malnutrition, and socioeconomic restraints of developing countries with a call for possible global action. Conclusion: The present study stresses the importance of considering the linkage between malnutrition and disease susceptibility because of the known relationships between undernutrition and greater vulnerability to infectious diseases, including RSV infection. These complex interactions between infectious disease and undernutrition also raise issues on the longer-term sequelae of postbronchiolitis recurrent wheezing. This prompts a discussion on whether industrialized countries should prioritize the provision of newly developed monoclonal antibodies and RSV vaccines to LMICs or whether vital nutritional needs should be a first focus. The resolution of these issues will require research and greater international discourse.

Cost of illness due to respiratory syncytial virus acute lower respiratory tract infection among infants hospitalized in Argentina

BACKGROUND

Information is scarce regarding the economic burden of respiratory syncytial virus (RSV) disease in low-resource settings. This study aimed to estimate the cost per episode of hospital admissions due to RSV severe disease in Argentina.

METHODS

This is a prospective cohort study that collected information regarding 256 infants under 12 months of age with acute lower respiratory tract infection (ALRTI) due to RSV in two public hospitals of Buenos Aires between 2014 and 2016. Information on healthcare resource use was collected from the patient's report and its associated costs were estimated based on the financial database and account records of the hospitals. We estimated the total cost per hospitalization due to RSV using the health system perspective. The costs were estimated in US dollars as of December 2022 (1 US dollar = 170 Argentine pesos).

RESULTS

The mean costs per RSV hospitalization in infants was US$587.79 (95% confidence interval [CI] $535.24 - $640.33). The mean costs associated with pediatric intensive care unit (PICU) admission more than doubled from those at regular pediatric wards ($1,556.81 [95% CI $512.21 - $2,601.40] versus $556.53 [95% CI $514.59 - $598.48]).

CONCLUSIONS

This study shows the direct economic impact of acute severe RSV infection on the public health system in Argentina. The estimates obtained from this study could be used to inform cost-effectiveness analyses of new preventive RSV interventions being developed.

Age-related STAT3 signaling regulates severity of respiratory syncytial viral infection in human bronchial epithelial cells

Respiratory syncytial virus (RSV) can cause severe disease especially in infants; however, mechanisms of age-associated disease severity remain elusive. Here, employing human bronchial epithelium models generated from tracheal aspirate-derived basal stem cells of neonates and adults, we investigated whether age regulates RSV-epithelium interaction to determine disease severity. We show that following RSV infection, only neonatal epithelium model exhibited cytopathy and mucus hyperplasia, and neonatal epithelium had more robust viral spread and inflammatory responses than adult epithelium. Mechanistically, RSV-infected neonatal ciliated cells displayed age-related impairment of STAT3 activation, rendering susceptibility to apoptosis, which facilitated viral spread. In contrast, SARS-CoV-2 infection of ciliated cells had no effect on STAT3 activation and was not affected by age. Taken together, our findings identify an age-related and RSV-specific interaction with neonatal bronchial epithelium that critically contributes to severity of infection, and STAT3 activation offers a potential strategy to battle severe RSV disease in infants.

Maternal diet modulates the infant microbiome and intestinal Flt3L necessary for dendritic cell development and immunity to respiratory infection

Poor maternal diet during pregnancy is a risk factor for severe lower respiratory infections (sLRIs) in the offspring, but the underlying mechanisms remain elusive. Here, we demonstrate that in mice a maternal low-fiber diet (LFD) led to enhanced LRI severity in infants because of delayed plasmacytoid dendritic cell (pDC) recruitment and perturbation of regulatory T cell expansion in the lungs. LFD altered the composition of the maternal milk microbiome and assembling infant gut microbiome. These microbial changes reduced the secretion of the DC growth factor Flt3L by neonatal intestinal epithelial cells and impaired downstream pDC hematopoiesis. Therapy with a propionate-producing bacteria isolated from the milk of high-fiber diet-fed mothers, or supplementation with propionate, conferred protection against sLRI by restoring gut Flt3L expression and pDC hematopoiesis. Our findings identify a microbiome-dependent Flt3L axis in the gut that promotes pDC hematopoiesis in early life and confers disease resistance against sLRIs.

What are the risk factors for death among children with pneumonia in low- and middle-income countries? A systematic review

Background

Knowledge of the risk factors for and causes of treatment failure and mortality in childhood pneumonia is important for prevention, diagnosis, and treatment at an individual and population level. This review aimed to identify the most important risk factors for mortality among children aged under ten years with pneumonia.

Methods

We systematically searched MEDLINE, EMBASE, and PubMed for observational and interventional studies reporting risk factors for mortality in children (aged two months to nine years) in low- and middle-income countries (LMICs). We screened articles according to specified inclusion and exclusion criteria, assessed risk of bias using the EPHPP framework, and extracted data on demographic, clinical, and laboratory risk factors for death. We synthesized data descriptively and using Forest plots and did not attempt meta-analysis due to the heterogeneity in study design, definitions, and populations.

Findings

We included 143 studies in this review. Hypoxaemia (low blood oxygen level), decreased conscious state, severe acute malnutrition, and the presence of an underlying chronic condition were the risk factors most strongly and consistently associated with increased mortality in children with pneumonia. Additional important clinical factors that were associated with mortality in the majority of studies included particular clinical signs (cyanosis, pallor, tachypnoea, chest indrawing, convulsions, diarrhoea), chronic comorbidities (anaemia, HIV infection, congenital heart disease, heart failure), as well as other non-severe forms of malnutrition. Important demographic factors associated with mortality in the majority of studies included age <12 months and inadequate immunisation. Important laboratory and investigation findings associated with mortality in the majority of studies included: confirmed Pneumocystis jirovecii pneumonia (PJP), consolidation on chest x-ray, pleural effusion on chest x-ray, and leukopenia. Several other demographic, clinical and laboratory findings were associated with mortality less consistently or in a small numbers of studies.

Conclusions

Risk assessment for children with pneumonia should include routine evaluation for hypoxaemia (pulse oximetry), decreased conscious state (e.g. AVPU), malnutrition (severe, moderate, and stunting), and the presence of an underlying chronic condition as these are strongly and consistently associated with increased mortality. Other potentially useful risk factors include the presence of pallor or anaemia, chest indrawing, young age (<12 months), inadequate immunisation, and leukopenia.

The role of high carbohydrate-rich food intake and severity of asthma exacerbation in children between 2 to 6 years aged

INTRODUCTION

Over the last decades, dietary habits in developing countries have been characterized by low intake of fruits and vegetables and high consumption of sweetened drinks. Most of the evidence linking carbohydrate intake and asthma comes from children over 6 years of age. The aim of this study was to examine the association between macronutrient intake and the severity of asthma exacerbations in children aged 2-6 years.

METHODS

We performed a cross-sectional study that included all children aged 2-6 years hospitalized due to an asthma exacerbation. Dietary data were collected using a food frequency questionnaire (FFQ) validated in the Colombian population. The GINA classification of acute asthma was used to define the severity. To identify factors independently associated with asthma exacerbation severity, we fit the data to ordinal logistic regression.

RESULTS

During the study period, 228 cases of patients with asthma exacerbation were included. Asthma severity was dose-dependently associated with protein and carbohydrate-rich intake. The variables included in the multivariable analysis included reactive C protein (OR 1.05, CI 95% (1.03-1.07)), smoking at home (OR 3.92 (1.82-8.44)), atopic dermatitis (OR 3.82 (1.59-9.21)), and protein and carbohydrate-rich food intake (OR 0.11 (0.03-0.33)) and (OR 2.42 (1.09-5.80)), respectively.

CONCLUSION

High carbohydrate-rich food intake is associated with the severity of asthma exacerbation adjusted by other known risk factors such as atopy, smoking, and reactive C protein. This evidence should motivate the development of public health policies to control the consumption of sugar-rich products in children under 6 years.

Viral Infection and Respiratory Exacerbation in Children: Results from a Local German Pediatric Exacerbation Cohort

Respiratory viruses play an important role in asthma exacerbation, and early exposure can be involved in recurrent bronchitis and the development of asthma. The exact mechanism is not fully clarified, and pathogen-to-host interaction studies are warranted to identify biomarkers of exacerbation in the early phase. Only a limited number of international exacerbation cohorts were studied. Here, we have established a local pediatric exacerbation study in Germany consisting of children with asthma or chronic, recurrent bronchitis and analyzed the viriome within the nasopharyngeal swab specimens derived from the entire cohort (n = 141). Interestingly, 41% of exacerbated children had a positive test result for human rhinovirus (HRV)/human enterovirus (HEV), and 14% were positive for respiratory syncytial virus (RSV). HRV was particularly prevalent in asthmatics (56%), wheezers (50%), and atopic (66%) patients. Lymphocytes were decreased in asthmatics and in HRV-infected subjects, and patients allergic to house dust mites were more susceptible to HRV infection. Our study thus confirms HRV infection as a strong 'biomarker' of exacerbated asthma. Further longitudinal studies will show the clinical progress of those children with a history of an RSV or HRV infection. Vaccination strategies and novel treatment guidelines against HRV are urgently needed to protect those high-risk children from a serious course of disease.

Budget Impact Analysis of Hypertonic Saline Inhalations for Infant Bronchiolitis: The Colombian National Health System Perspective

OBJECTIVES

Nebulized 3% hypertonic solution (HS) is associated with lower total cost and higher quality-adjusted life-years. Nevertheless, the expected budget impact of this drug had not been explicitly estimated. The aim of this study was to evaluate the budget impact of 3% HS in the treatment of acute bronchiolitis in Colombia.

METHODS

A budget impact analysis was performed to evaluate the potential financial impact of the use of 3% HS. The analysis considered a 4-year time horizon and a Colombian national health system perspective. The incremental budget impact was calculated by subtracting the cost of the new treatment, in which 3 % HS (added to humidified oxygen) was reimbursed, from the cost of the conventional treatment without 3 % HS (only humidified oxygen or adrenaline nebulization). Univariate 1-way sensitivity analyses were performed.

RESULTS

In the base-case analysis, the 4-year costs associated with HS and non-3% HS were estimated to be $47 792 230 and $53 312 832, respectively, indicating savings for Colombian national health system equal to $5 520 602 if HS is adopted for the routine management of patients with acute bronchiolitis. This result was robust in univariate 1-way sensitivity analysis.

CONCLUSION

HS was cost saving in emergency settings for treating infants with acute bronchiolitis. This evidence can be used by decision makers in Colombia to improve clinical practice guidelines and should be replicated to validate their results in other middle-income countries.

The cost-utility of early use of high-flow nasal cannula in bronchiolitis

BACKGROUND

High-flow nasal cannula (HFNC) oxygen is a non-invasive ventilation system that was introduced as an alternative to CPAP (continuous positive airway pressure), with a marked increase in its use in pediatric care settings. This study aimed to evaluate the cost-effectiveness of early use of HFNC compared to oxygen by nasal cannula in an infant with bronchiolitis in the emergency setting.

METHODS

A decision tree model was used to estimate the cost-effectiveness of HFNC compared with oxygen by nasal cannula (control strategy) in an infant with bronchiolitis in the emergency setting. Cost data were obtained from a retrospective study on bronchiolitis from tertiary centers in Rionegro, Colombia, while utilities were collected from the literature.

RESULTS

The QALYs per patient calculated in the base-case model were 0.9141 (95% CI 0.913-0.915) in the HFNC and 0.9105 (95% CI 0.910-0.911) in control group. The cost per patient was US$368 (95% CI US$ 323-411) in HFNC and US$441 (95% CI US$ 384-498) per patient in the control group.

CONCLUSIONS

HFNC was cost-effective HFNC compared to oxygen by nasal cannula in an infant with bronchiolitis in the emergency setting. The use of this technology in emergency settings will allow a more efficient use of resources, especially in low-resource countries with high prevalence of bronchiolitis .

Nurturing the Early Life Gut Microbiome and Immune Maturation for Long Term Health

Early life is characterized by developmental milestones such as holding up the head, turning over, sitting up and walking that are typically achieved sequentially in specific time windows. Similarly, the early gut microbiome maturation can be characterized by specific temporal microorganism acquisition, colonization and selection with differential functional features over time. This orchestrated microbial sequence occurs from birth during the first years of age before the microbiome reaches an adult-like composition and function between 3 and 5 years of age. Increasingly, these different steps of microbiome development are recognized as crucial windows of opportunity for long term health, primarily linked to appropriate immune and metabolic development. For instance, microbiome disruptors such as preterm and Cesarean-section birth, malnutrition and antibiotic use are associated with increased risk to negatively affect long-term immune and metabolic health. Different age discriminant microbiome taxa and functionalities are used to describe age-appropriate microbiome development, and advanced modelling techniques enable an understanding and visualization of an optimal microbiome maturation trajectory. Specific microbiome features can be related to later health conditions, however, whether such features have a causal relationship is the topic of intense research. Early life nutrition is an important microbiome modulator, and 'Mother Nature' provides the model with breast milk as the sole source of nutrition for the early postnatal period, while dietary choices during the prenatal and weaning period are to a large extent guided by tradition and culture. Increasing evidence suggests prenatal maternal diet and infant and child nutrition impact the infant microbiome trajectory and immune competence development. The lack of a universal feeding reference for such phases represents a knowledge gap, but also a great opportunity to provide adequate nutritional guidance to maintain an age-appropriate microbiome for long term health. Here, we provide a narrative review and perspective on our current understanding of age-appropriate microbiome maturation, its relation to long term health and how nutrition shapes and influences this relationship.

Community Mortality Due to Respiratory Syncytial Virus in Argentina: Population-based Surveillance Study

Background

Many deaths in infants from low-middle income countries (LMICs) occur at home or upon arrival to health facilities. Although acute lower respiratory tract illness plays an important role in community mortality, the accuracy of mortality rates due to respiratory syncytial virus (RSV) remains unknown.

Methods

An active surveillance study among children aged under 5 years old (U5) was performed in Buenos Aires, Argentina, between January and December 2019, to define the burden and role of RSV in childhood community mortality.

Results

A total of 63 families of children U5 participated in the study. Based on a combined approach of tissue sampling, verbal autopsies, and expert’s analysis, RSV infection was found in the causal chain of 11 from 12 cases with positive molecular biology results in respiratory samples. The estimated mortality rate due to RSV among infants was 0.27 deaths/1000 live births. The mean age of RSV-related household deaths was 2.8 months of age (standard deviation [SD] 1.7), and 8/12 were male infants (66.7%). Dying at home from RSV was associated with Streptococcus pneumoniae and/or Moraxella catarrhalis lung coinfection (75%), living in slums and settlement (odds ratio [OR], 17.09; 95% confidence interval [CI], 1.3–219.2), and other underlying comorbidities (OR, 14.87; 95% CI, 1.3–164.6).

Conclusions

Infant community mortality rates due to RSV are higher than those reported in industrialized countries and similar to those reported in hospital-based studies in the same catchment population.

Challenges of Assessing Community Mortality Due to Respiratory Viruses in Children Aged Less Than 5 Years

Background

Estimating the real impact of respiratory syncytial virus (RSV) disease is key for the development of vaccines and treatments. Ascertaining the burden of community mortality due to RSV is challenging due to the lack of primary data. Therefore, conducting observational studies to determine the factors associated with community mortality due to the virus in developing countries is important.

Objective

Our aim in this study was to describe the obstacles, gaps, and challenges that investigators face in low-income, vulnerable regions in 4 developing countries on 3 continents.

Results

The main obstacles and challenges of ascertaining community mortality due to RSV were defining strategies to consent families for testing before burial, sampling individuals at the household level, supporting bereaved parents with different cultural and religious backgrounds, establishing tailored strategies for studies in challenging settings, and integrating RSV mortality data from nasopharyngeal samples.

Conclusion

Detailed logistical planning based on population sociodemographic information, grief counseling, staff training, and a multidisciplinary approach with adequate laboratory infrastructure is critical to successful observational community-based RSV studies.

TRIM22 inhibits respiratory syncytial virus replication by targeting JAK-STAT1/2 signaling

Respiratory syncytial virus (RSV) infection is a major cause of lower respiratory tract disease. Although RSV causes major economic losses every year, effective treatments have not been found so far. Recent studies have shown that the tripartite motif-containing (TRIM) superfamily plays an essential role in the immune response. In this study, we found that TRIM22 had an inhibitory effect on RSV infection, and downregulation of TRIM22 moderately enhanced RSV replication. Our data further demonstrated that RSV infection induced TRIM22 expression through the activation of JAK-STAT1/2 signaling. RSV infection also induced TRIM22 expression. Taken together, these data points showed that the TRIM family member, TRIM22, had an essential role in resisting RSV infection, and this effect was closely related to the JAK-STAT1/2 pathway. Our results provide promising evidence for a novel target for the prevention and treatment of RSV.

Intestinal Microbiota-A Promising Target for Antiviral Therapy?

The intestinal microbiota is thought to be an important biological barrier against enteric pathogens. Its depletion, however, also has curative effects against some viral infections, suggesting that different components of the intestinal microbiota can play both promoting and inhibitory roles depending on the type of viral infection. The two primary mechanisms by which the microbiota facilitates or inhibits viral invasion involve participation in the innate and adaptive immune responses and direct or indirect interaction with the virus, during which the abundance and composition of the intestinal microbiota might be changed by the virus. Oral administration of probiotics, faecal microbiota transplantation (FMT), and antibiotics are major therapeutic strategies for regulating intestinal microbiota balance. However, these three methods have shown limited curative effects in clinical trials. Therefore, the intestinal microbiota might represent a new and promising supplementary antiviral therapeutic target, and more efficient and safer methods for regulating the microbiota require deeper investigation. This review summarizes the latest research on the relationship among the intestinal microbiota, anti-viral immunity and viruses and the most commonly used methods for regulating the intestinal microbiota with the goal of providing new insight into the antiviral effects of the gut microbiota.

Respiratory Failure and Death in Vulnerable Premature Children With Lower Respiratory Tract Illness

Background

Efforts to better understand the risk factors associated with respiratory failure (RF) and fatal lower respiratory tract infection (LRTI) in premature children in developing countries are necessary to elaborate evidenced-based preventive interventions. We aim to characterize the burden of respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) LRTI in premature children and determine risk factors for RF and fatal illness in a vulnerable population.

Methods

This is a prospective, population-based, cross-sectional study. Subjects with severe LRTI were enrolled during respiratory season. Risk factors for RF and death in premature infants were investigated.

Results

A total of 664 premature children participated. Infant’s hospitalization rate due to LRTI was 82.6/1000 (95% confidence interval [CI], 68.6–96.7/1000). Infant’s RSV and hMPV rates were 40.9/1000 (95% CI, 36.3–45.6/1000) and 6.6/1000 (95% CI, 3.9–9.2/1000), respectively. The RF rate was 8.2/1000 (95% CI, 4.9–11.5/1000). The LRTI mortality was 2.2/1000 (95% CI, 0.7–3.7/1000); for RSV, the rate was 0.8/1000 (95% CI, 0–1.7/1000) with a case-fatality ratio of 1.8%. Never breastfeeding, malnutrition, younger than 6 months, congenital heart disease, and lower hematocrit were risk factors for RF. Experiencing pneumonia, pneumothorax, sepsis, or apnea were clinical determinants of poor outcomes.

Conclusions

Premature children under 2 years old in vulnerable environments experience RF and death more often than term counterparts. Modifiable risk factors associated with poor outcomes should prompt evidence-based interventions.

The cost-effectiveness of hypertonic saline inhalations for infant bronchiolitis

BACKGROUND

Pharmacological treatment for bronchiolitis is primarily supportive because bronchodilators, steroids, and antibiotics, show little benefit. Clinical studies have suggested that nebulized 3% hypertonic solution is useful for infants with bronchiolitis. This study aims to evaluate the cost-effectiveness of the HS inhalations in infant bronchiolitis in a tropical country.

METHODS

Decision tree analysis was used to calculate the expected costs and QALYs. All cost and use of resources were collected directly from medical invoices of 193 patient hospitalized with diagnosis of bronchiolitis in tertiary centers, of Rionegro, Colombia. The utility values applied to QALYs calculations were collected from the literature. The economic analysis was carried out from a societal perspective.

RESULTS

The model showed that nebulized 3% hypertonic solution, was associated with lower total cost than controls (US $200vs US $240 average cost per patient), and higher QALYs (0.92 vs 0.91 average per patient); showing dominance. A position of dominance negates the need to calculate an incremental cost-effectiveness ratio.

CONCLUSION

The nebulized 3% hypertonic solution was cost-effective in the inpatient treatment of infant bronchiolitis. Our study provides evidence that should be used by decision-makers to improve clinical practice guidelines and should be replicated to validate their results in other tropical countries.

Genetic Susceptibility to Life-threatening Respiratory Syncytial Virus Infection in Previously Healthy Infants

BACKGROUND

Genetic background may be an important host determinant of respiratory syncytial virus (RSV) disease severity, but full characterization of susceptibility genes remains unclear. This study aimed to assess the presence of specific single-nucleotide polymorphisms (SNPs) in selected genes codifying for different components of the antiviral innate immune response, to determine their role for developing RSV life-threatening disease (LTD).

METHODS

Prospective cohort study including previously healthy full-term infants hospitalized with a first RSV infection during 2017-2018. RSV detection, quantification and subgroup determination, and genotyping for SNPs in Toll-like receptor 4 (TLR4 rs4986790, rs4986791), Toll-like receptor 8 (TLR8 rs3761624), macrophage receptor with collagenous structure(MARCO rs1318645) and myxovirus resistance 1(MX1 rs469390) were performed by real-time polymerase chain reaction in nasopharyngeal aspirates obtained on admission. Patients with LTD were those admitted to the intensive care unit requiring ventilatory support.

RESULTS

Seventy-five patients were studied, 15 (20%) developed LTD. Infants with concurrent SNPs in MX1 and TLR8, MARCO and TLR8 or MARCO, MX1 and TLR8 had an increased risk of developing LTD. Multivariable logistic regression analysis confirmed this significant association (odds ratio [OR] = 3.75, P = 0.046; OR = 3.92, P = 0.040; OR = 5.56, P = 0.010, respectively). No differences were seen in viral load of patients with LTD compared with those with better outcome (P = 0.737). In addition, no differences in viral load were seen in patients with the described high-risk SNPs compared with those without these polymorphisms.

CONCLUSIONS

Life-threatening RSV infection in previously healthy infants was significantly associated with the presence of combined SNPs in MARCO, MX1 and TLR8.

LPS aggravates lung inflammation induced by RSV by promoting the ERK-MMP-12 signaling pathway in mice

Background

RSV can lead to persistent airway inflammation and airway hyperresponsiveness (AHR), and is intimately associated with childhood recurrent wheezing and asthma, but the underlying mechanisms remain unclear. Lipopolysaccharide (LPS) is also implicated in the onset and exacerbation of asthma. However, whether inhalation of LPS can boost airway inflammation induced by RSV is not clear. In this study, we utilized an LPS- and RSV-superinfected mouse model to explore underlying pathogenesis.

Methods

Mice were infected with RSV on day 0 and inoculated with LPS from day 35 to day 41, samples were collected on day 42. Inflammatory cells, lung histopathology and AHR were measured. Cytokines were detected by ELISA and ERK, JNK, p38 was determined by western blot. MMP408, PD98059, SP600125 and SB203580 were used to inhibit MMP-12, ERK, JNK and p38 respectively.

Results

LPS exposure superimposed on RSV-infected lungs could lead to more vigorous cellular influx, lung structures damage, augmented AHR and higher MMP-12 levels. Inhibition of MMP-12 or ERK signaling pathway in vivo both diminished LPS-driven airway inflammation and AHR.

Conclusions

Exposure to LPS in RSV-infected mice is associated with enhanced increases in ERK-MMP-12 expression that translates into increased lung inflammation and AHR. These findings contribute novel information to the field investigating the onset of post-RSV bronchiolitis recurrent wheezing as a result of LPS exposure.

Respiratory syncytial virus infection: why does disease severity vary among individuals?

Introduction: Respiratory syncytial virus (RSV) is the most common cause of acute lower respiratory tract infections in infancy. While many infants are infected with RSV, the nature and severity of the disease vary among individuals. RSV causes bronchiolitis, pneumonia, and asthma exacerbation. However, most children infected with RSV have only mild upper airways disease and may be asymptomatic.Areas covered: Despite efforts to elucidate mechanisms for the various clinical responses to RSV infection, they remain largely unknown, suggesting that susceptibility and disease are influenced by multiple intrinsic and extrinsic factors. This article reviews the available literature on the field of RSV disease severity and discusses important factors associated to susceptibility and different disease outcome.Expert opinion: The severity of RSV-induced illness is a phenomenon that depends on a variety of graded mechanisms of interaction between the host, virus, and environment. This may lead to differences in the intensity of immune response in the lung and different courses of the disease. By characterizing, classifying, and grading the affecting factors in high-risk patients versus those who do not fall ill by RSV, we may find therapies or point to disease-limiting medications.

Role for Maternal Asthma in Severe Human Metapneumovirus Lung Disease Susceptibility in Children

Background

Severity of human metapneumovirus (hMPV) lower respiratory illness (LRTI) is considered similar to that observed for respiratory syncytial virus (RSV). However, differences in severity between these pathogens have been noted, suggesting the degree of illness may vary in different populations. Moreover, a potential association between hMPV and asthma also suggests that hMPV may preferentially affect asthmatic subjects.

Methods

In a population-based surveillance study in children aged <2 years admitted for severe LRTI in Argentina, nasopharyngeal aspirates were tested by RT-PCR for hMPV, RSV, influenza A, and human rhinovirus.

Results

Of 3947 children, 383 (10%) were infected with hMPV. The hospitalization rate for hMPV LRTI was 2.26 per 1000 children (95% confidence interval [CI], 2.04–2.49). Thirty-nine (10.2%) patients infected with hMPV experienced life-threatening disease (LTD; 0.23 per 1000 children; 95% CI, .16–.31/1000), and 2 died (mortality rate 0.024 per 1000; 95% CI, .003–.086). In hMPV-infected children birth to an asthmatic mother was an increased risk for LTD (odds ratio, 4.72; 95% CI, 1.39–16.01). We observed a specific interaction between maternal asthma and hMPV infection affecting risk for LTD.

Conclusions

Maternal asthma increases the risk for LTD in children <2 years old hospitalized for severe hMPV LRTI.

Impact of pregravid obesity on maternal and fetal immunity: Fertile grounds for reprogramming

Maternal pregravid obesity results in several adverse health outcomes during pregnancy, including increased risk of gestational diabetes, preeclampsia, placental abruption, and complications at delivery. Additionally, pregravid obesity and in utero exposure to high fat diet have been shown to have detrimental effects on fetal programming, predisposing the offspring to adverse cardiometabolic, endocrine, and neurodevelopmental outcomes. More recently, a deeper appreciation for the modulation of offspring immunity and infectious disease-related outcomes by maternal pregravid obesity has emerged. This review will describe currently available animal models for studying the impact of maternal pregravid obesity on fetal immunity and review the data from clinical and animal model studies. We also examine the burden of pregravid obesity on the maternal-fetal interface and the link between placental and systemic inflammation. Finally, we discuss future studies needed to identify key mechanistic underpinnings that link maternal inflammatory changes and fetal cellular reprogramming events.

Microbiota-derived acetate protects against respiratory syncytial virus infection through a GPR43-type 1 interferon response

Severe respiratory syncytial virus (RSV) infection is a major cause of morbidity and mortality in infants <2 years-old. Here we describe that high-fiber diet protects mice from RSV infection. This effect was dependent on intestinal microbiota and production of acetate. Oral administration of acetate mediated interferon-β (IFN-β) response by increasing expression of interferon-stimulated genes in the lung. These effects were associated with reduction of viral load and pulmonary inflammation in RSV-infected mice. Type 1 IFN signaling via the IFN-1 receptor (IFNAR) was essential for acetate antiviral activity in pulmonary epithelial cell lines and for the acetate protective effect in RSV-infected mice. Activation of Gpr43 in pulmonary epithelial cells reduced virus-induced cytotoxicity and promoted antiviral effects through IFN-β response. The effect of acetate on RSV infection was abolished in Gpr43^−/− mice. Our findings reveal antiviral effects of acetate involving IFN-β in lung epithelial cells and engagement of GPR43 and IFNAR.

Dietary fibers and SCFAs can exert a protective effect against respiratory syncytial virus (RSV). Here, the authors report that microbiota-derived acetate protects mice against RSV infection via GPR43- mediated type 1 interferon response induction in the lungs.

Interleukin-13 associates with life-threatening rhinovirus infections in infants and young children

OBJECTIVE

Delineate risk factors associated with severe hypoxemia (O₂ sat ≤87%) in infants and children younger than 2 years hospitalized with single pathogen HRV infection.

STUDY DESIGN

Prospective study in a yearly catchment population of 56 560 children <2 years old between 2011 and 2013 in Argentina. All children with respiratory signs and O₂ sat <93% on admission were included. HRV infections were identified by reverse transcriptase-polymerase chain reaction. Epidemiologic, clinical, viral, and immunological risk factors were assessed.

RESULTS

Among 5012 hospitalized patients, HRV was detected as a single pathogen in 347 (6.92%) subjects. Thirty-two (9.2%) had life-threatening disease. Traditional risk factors for severe bronchiolitis did not affect severity of illness. HRV viral load, HRV groups, and type II and III interferons did not associate with severe hypoxemia. Interleukin-13 Levels in respiratory secretions at the time of admission (OR = 7.43 (3-18.4); P < 0.001 for IL-13 >10 pg/mL) predisposed to life-threatening disease.

CONCLUSIONS

Targeted interventions against IL-13 should be evaluated to decrease severity of HRV illness in infancy and early childhood.

Respiratory syncytial virus is an "opportunistic" killer

Respiratory syncytial virus (RSV), responsible for more than three million yearly hospitalizations and up to 118 000 deaths in children under 5 years, is the leading pulmonary cause of death for this age group that lacks a licensed vaccine. Ninety-nine percent of deaths due to the virus occur in developing countries. In-hospital RSV fatalities affect previously healthy term infants in association with bacterial sepsis, clinically significant pneumothoraxes and, to a lesser extent, comorbid conditions. Community deaths affect low-income children from socially vulnerable families and appear to be as frequent as inpatient fatalities. In industrialized countries, RSV deaths occur almost exclusively in children with premorbid conditions. In a sense, RSV is an "opportunistic" killer. It needs a synergistic premorbid, medical practice-related, infectious, or social co-factor to cause a fatal outcome. But while the complex problems associated with these co-factors await solutions, candidate vaccines, long-lived monoclonal antibodies and antivirals against RSV are under clinical evaluation. It seems reasonable to predict that the landscape of RSV infections will look different in the next decade.

Viral bronchiolitis in young infants: new perspectives for management and treatment

OBJECTIVE

The aim of this review was to address advances in management and treatment of acute viral bronchiolitis in infants.

SOURCES

A systematic review search was made including all articles published in English between 2010 and 2017, and available in the electronic databases PubMed and Cochrane Central Register of Controlled Trials (CENTRAL) and specialized register of the Acute Respiratory Infections Group (Cochrane review group). The following MESH terms in English were included, using different Boolean operators for the search strategy: "bronchiolitis, viral," "diagnosis," "epidemiology," "etiology," "therapy," "virology," "prevention and control," "respiratory syncytial virus, human." Additional filters were used.

SUMMARY OF FINDINGS

Few effective interventions are recommended for the management of RSV bronchiolitis in young infants. The main goal is to ensure an adequate oxygen supplementation and fluid balance whenever deemed necessary. Hypertonic saline nebulization is helpful only for hospitalized infants. Numerous antiviral drugs and specific vaccines for RSV are under evaluation and foretell advances in disease management in the near future.

CONCLUSION

A number of promising new technologies are advancing in the field. Until new interventions became feasible, early detection and modification of preventable risk factors is essential to improve outcomes.

Maternal body mass index: Relation with infant respiratory symptoms and infections

BACKGROUND

Maternal obesity is increasingly prevalent in many westernized countries. Many studies report associations between maternal obesity and childhood wheeze or asthma but few have considered maternal obesity in relation to respiratory infections or symptoms other than wheeze during infancy. This study assesses the relationship between maternal BMI and reported wheeze, cough and respiratory infections during the first year of life.

METHODS

In 2799 mother-child pairs, we examined the relations between maternal pre-pregnancy BMI and pregnancy weight gain and reported offspring wheeze, prolonged cough, lower respiratory tract infection, croup, and ear infection before age 1 year, along with reported diarrhea or vomiting. Maternally reported paternal BMI was included in the models as a proxy for unmeasured confounding by shared familial factors.

RESULTS

Higher maternal BMI was associated with increased risks of offspring wheeze, prolonged cough and lower respiratory tract infection (relative risks (95%CI) per 5 kg/m² 1.09 (1.05-1.13), 1.09 (1.03-1.14), and 1.13 (1.07-1.20), respectively). These associations remained after adjusting for maternally reported paternal BMI. No associations were found with croup, ear infection, or diarrhea or vomiting. Pregnancy weight gain was not associated with any of the offspring symptoms or illnesses.

DISCUSSION

Higher maternal BMI is associated with increased risk of wheeze, cough, and maternally reported lower respiratory tract infection in infancy. These associations were independent of maternally reported paternal BMI. These observations might be explained by intrauterine effects of maternal obesity upon respiratory or immune development.

Mortality due to Respiratory Syncytial Virus. Burden and Risk Factors

RATIONALE

Respiratory syncytial virus (RSV) is the most frequent cause of hospitalization and an important cause of death in infants in the developing world. The relative contribution of social, biologic, and clinical risk factors to RSV mortality in low-income regions is unclear.

OBJECTIVES

To determine the burden and risk factors for mortality due to RSV in a low-income population of 84,840 infants.

METHODS

This was a prospective, population-based, cross-sectional, multicenter study conducted between 2011 and 2013. Hospitalizations and deaths due to severe lower respiratory tract illness (LRTI) were recorded during the RSV season. All-cause hospital deaths and community deaths were monitored. Risk factors for respiratory failure (RF) and mortality due to RSV were assessed using a hierarchical, logistic regression model.

MEASUREMENTS AND MAIN RESULTS

A total of 2,588 (65.5%) infants with severe LRTI were infected with RSV. A total of 157 infants (148 postneonatal) experienced RF or died with RSV. RSV LRTI accounted for 57% fatal LRTI tested for the virus. A diagnosis of sepsis (odds ratio [OR], 17.03; 95% confidence interval [CI], 13.14-21.16 for RF) (OR, 119.39; 95% CI, 50.98-273.34 for death) and pneumothorax (OR, 17.15; 95% CI, 13.07-21.01 for RF) (OR, 65.49; 95% CI, 28.90-139.17 for death) were the main determinants of poor outcomes.

CONCLUSIONS

RSV was the most frequent cause of mortality in low-income postneonatal infants. RF and death due to RSV LRTI, almost exclusively associated with prematurity and cardiopulmonary diseases in industrialized countries, primarily affect term infants in a developing world environment. Poor outcomes at hospitals are frequent and associated with the cooccurrence of bacterial sepsis and clinically significant pneumothoraxes.

Respiratory syncytial virus hospitalization and mortality: Systematic review and meta-analysis

BACKGROUND

Respiratory syncytial virus (RSV) is a major public health burden worldwide. We aimed to review the current literature on the incidence and mortality of severe RSV in children globally.

METHODS

Systematic literature review and meta-analysis of published data from 2000 onwards, reporting on burden of acute respiratory infection (ARI) due to RSV in children. Main outcomes were hospitalization for severe RSV-ARI and death.

RESULTS

Five thousand two hundred and seventy-four references were identified. Fifty-five studies were included from 32 countries. The global RSV-ARI hospitalization estimates, reported per 1,000 children per year (95% Credible Interval (CrI), were 4.37 (2.98, 6.42) among children <5 years, 19.19 (15.04, 24.48) among children <1 year, 20.01 (9.65, 41.31) among children <6 months and 63.85 (37.52, 109.70) among premature children <1 year. The RSV-ARI global case-fatality estimates, reported per 1,000 children, (95% Crl) were 6.21 (2.64, 13.73) among children <5 years, 6.60 (1.85, 16.93) for children <1 year, and 1.04 (0.17, 12.06) among preterm children <1 year.

CONCLUSIONS

A substantial proportion of RSV-associated morbidity occurs in the first year of life, especially in children born prematurely. These data affirm the importance of RSV disease in the causation of hospitalization and as a significant contributor to pediatric mortality and further demonstrate gestational age as a critical determinant of disease severity. An important limitation of case-fatality ratios is the absence of individual patient characteristics of non-surviving patients. Moreover, case-fatality ratios cannot be translated to population-based mortality. Pediatr Pulmonol. 2017;52:556-569. © 2016 The Authors. Pediatric Pulmonology. Published by Wiley Periodicals, Inc.

The Influence of the Microbiome on Early-Life Severe Viral Lower Respiratory Infections and Asthma-Food for Thought?

Severe viral lower respiratory infections are a major cause of infant morbidity. In developing countries, respiratory syncytial virus (RSV)-bronchiolitis induces significant mortality, whereas in developed nations the disease represents a major risk factor for subsequent asthma. Susceptibility to severe RSV-bronchiolitis is governed by gene-environmental interactions that affect the host response to RSV infection. Emerging evidence suggests that the excessive inflammatory response and ensuing immunopathology, typically as a consequence of insufficient immunoregulation, leads to long-term changes in immune cells and structural cells that render the host susceptible to subsequent environmental incursions. Thus, the initial host response to RSV may represent a tipping point in the balance between long-term respiratory health or chronic disease (e.g., asthma). The composition and diversity of the microbiota, which in humans stabilizes in the first year of life, critically affects the development and function of the immune system. Hence, perturbations to the maternal and/or infant microbiota are likely to have a profound impact on the host response to RSV and susceptibility to childhood asthma. Here, we review recent insights describing the effects of the microbiota on immune system homeostasis and respiratory disease and discuss the environmental factors that promote microbial dysbiosis in infancy. Ultimately, this knowledge will be harnessed for the prevention and treatment of severe viral bronchiolitis as a strategy to prevent the onset and development of asthma.

Ferolla F, Hijano DR, Acosta PL, Erviti A, Polack FP. Alcohol during pregnancy worsens acute respiratory infections in children

AIM

This study explored whether alcohol consumption during pregnancy increased the risk of life-threatening respiratory infections in children.

METHODS

We prospectively evaluated children under the age of two years admitted to hospitals in Buenos Aires, Argentina, with severe acute respiratory infections during the winters of 2011 and 2012. Information on maternal alcohol consumption during the third trimester of pregnancy was collected using standardised questionnaires and categorised as never, low if it was once a week and high if it was equal or more than once a week.

RESULTS

Of the 3423 children hospitalised with acute respiratory infection, 2089 (63.7%) had respiratory syncytial virus (RSV). Alcohol consumption during the last trimester was reported by 398 mothers (12.4%) and categorised as low (n = 210, 6.5%) or high (n = 188, 5.9%). A greater effect on life-threatening respiratory infection, defined as oxygen saturation of or up to 87%, was observed with higher alcohol intake due to all viruses and specifically RSV in the logistic regression analyses. Alcohol consumption was strongly associated with life-threatening disease, particularly in boys whose adjusted odds ratio rose from 3.67 to 13.52 when their mothers drank alcohol.

CONCLUSION

Alcohol consumption during pregnancy was associated with life-threatening respiratory infections in boys.

TLR4 genotype and environmental LPS mediate RSV bronchiolitis through Th2 polarization

While 30%-70% of RSV-infected infants develop bronchiolitis, 2% require hospitalization. It is not clear why disease severity differs among healthy, full-term infants; however, virus titers, inflammation, and Th2 bias are proposed explanations. While TLR4 is associated with these disease phenotypes, the role of this receptor in respiratory syncytial virus (RSV) pathogenesis is controversial. Here, we evaluated the interaction between TLR4 and environmental factors in RSV disease and defined the immune mediators associated with severe illness. Two independent populations of infants with RSV bronchiolitis revealed that the severity of RSV infection is determined by the TLR4 genotype of the individual and by environmental exposure to LPS. RSV-infected infants with severe disease exhibited a high GATA3/T-bet ratio, which manifested as a high IL-4/IFN-γ ratio in respiratory secretions. The IL-4/IFN-γ ratio present in infants with severe RSV is indicative of Th2 polarization. Murine models of RSV infection confirmed that LPS exposure, Tlr4 genotype, and Th2 polarization influence disease phenotypes. Together, the results of this study identify environmental and genetic factors that influence RSV pathogenesis and reveal that a high IL-4/IFN-γ ratio is associated with severe disease. Moreover, these molecules should be explored as potential targets for therapeutic intervention.

Systematic review and meta-analysis of respiratory syncytial virus infection epidemiology in Latin America

Respiratory syncytial virus (RSV) is a frequent cause of acute respiratory infection and the most common cause of bronchiolitis in infants. The aim of this systematic review and meta-analysis was to obtain a comprehensive epidemiological picture of the data available on disease burden, surveillance, and use of resources in Latin America. Pooled estimates are useful for cross-country comparisons. Data from published studies reporting patients with probable or confirmed RSV infection in medical databases and gray literature were included from 74 studies selected from the 291 initially identified. When considering all countries, the largest pooled percentage RSV in low respiratory tract infection patients was found in the group between 0 and 11 months old, 41.5% (95% CI 32.0–51.4). In all countries, percentages were increasingly lower as older children were included in the analyses. The pooled percentage of RSV in LRTIs in the elderly people was 12.6 (95% CI 4.2–24.6). The percentage of RSV infection in hospitalized newborns was 40.9% (95% CI 28.28–54.34). The pooled case fatality ratio for RSV infection was 1.74% (95% CI 1.2–2.4) in the first 2 years of life. The average length of stay excluding intensive care unit admissions among children with risk factors for severe disease was 12.8 (95% CI 8.9–16.7) days, whereas it averaged 7.3 (95% CI 6.1/8.5) days in otherwise healthy children.We could conclude that infants in their first year of age were the most vulnerable population. To our knowledge, this is the first systematic review on RSV disease burden and use of health resources in Latin America.

Immunity to RSV in Early-Life

Respiratory Syncytial Virus (RSV) is the commonest cause of severe respiratory infection in infants, leading to over 3 million hospitalizations and around 66,000 deaths worldwide each year. RSV bronchiolitis predominantly strikes apparently healthy infants, with age as the principal risk factor for severe disease. The differences in the immune response to RSV in the very young are likely to be key to determining the clinical outcome of this common infection. Remarkable age-related differences in innate cytokine responses follow recognition of RSV by numerous pattern recognition receptors, and the importance of this early response is supported by polymorphisms in many early innate genes, which associate with bronchiolitis. In the absence of strong, Th1 polarizing signals, infants develop T cell responses that can be biased away from protective Th1 and cytotoxic T cell immunity toward dysregulated, Th2 and Th17 polarization. This may contribute not only to the initial inflammation in bronchiolitis, but also to the long-term increased risk of developing wheeze and asthma later in life. An early-life vaccine for RSV will need to overcome the difficulties of generating a protective response in infants, and the proven risks associated with generating an inappropriate response. Infantile T follicular helper and B cell responses are immature, but maternal antibodies can afford some protection. Thus, maternal vaccination is a promising alternative approach. However, even in adults adaptive immunity following natural infection is poorly protective, allowing re-infection even with the same strain of RSV. This gives us few clues as to how effective vaccination could be achieved. Challenges remain in understanding how respiratory immunity matures with age, and the external factors influencing its development. Determining why some infants develop bronchiolitis should lead to new therapies to lessen the clinical impact of RSV and aid the rational design of protective vaccines.

Update in sepsis and pulmonary infections 2013

The Journal has been in the vanguard of publications of the respiratory microbiome, including a National Institutes of Health Workshop report, establishing the normal microbiome in patients with various risks, and in the correlation of microbiome changes with disease exacerbations and lung transplant. A new classification scheme for healthcare-associated pneumonia, risks for nosocomial Pseudomonas pneumonia, and associations between community-acquired pneumonia and risks or outcomes have been reported. The increasingly recognized role of viral respiratory tract infections was reflected in publications regarding incidence rates, risk factors, and associations with other respiratory diseases. Significant contributions to understanding and treating sepsis emerged in 2013. The role of tissue damage was highlighted in a series of publications. A much greater understanding of the importance of pathways that directly impact the pathogen at the site of infection and subsequent pathogen clearance has emerged. The Journal published important contributions across the spectrum of ineffective therapy (activated protein C), novel therapeutic ideas (statins and extracorporeal membrane oxygenation), and solidly beneficial approaches (early protocolized care). Biomarker development is maturing to include a wide array of molecular measurements increasingly aimed at aiding improved therapy.

Current concepts and progress in RSV vaccine development

Respiratory syncytial virus (RSV) disease is an important cause of morbidity and mortality in children and debilitated adults and remains one of the major global unmet challenges for vaccine development. Several immunological issues have delayed the development of vaccines, especially the poorly protective response to natural infection and the enhancement of disease following administration of formalin inactivated vaccines during trials conducted in the 1960s. Advances in knowledge of the immune system, of the virus and its antigenic properties combined with new vaccine technologies are now injecting new hope into the field and have given rise to many promising vaccine approaches. Some of these may be optimal for use in children, while others may be more appropriate for pregnant women or vulnerable older adults. With a multi-pronged approach to prevention, we propose that it may be possible to destabilise community circulation of RSV and thus to significantly lessen the impact of RSV disease.

Recent advances in diagnosis, prevention, and treatment of human respiratory syncytial virus

Human respiratory syncytial virus (RSV) is a common cause of respiratory infection in infants and the elderly, leading to significant morbidity and mortality. The interdisciplinary fields, especially biotechnology and nanotechnology, have facilitated the development of modern detection systems for RSV. Many anti-RSV compounds like fusion inhibitors and RNAi molecules have been successful in laboratory and clinical trials. But, currently, there are no effective drugs for RSV infection even after decades of research. Effective diagnosis can result in effective treatment, but the progress in both of these facets must be concurrent. The development in prevention and treatment measures for RSV is at appreciable pace, but the implementation into clinical practice still seems a challenge. This review attempts to present the promising diverse research approaches and advancements in the area of diagnosis, prevention, and treatment that contribute to RSV management.