Search

Background: Bronchiolitis is a leading cause of infant hospitalization, linked to respiratory syncytial virus (RSV) and rhinovirus (RV). Guidelines lack specific viral testing for bronchiolitis management. To establish effective management strategies, it is crucial to assess whether specific respiratory virus types are correlated with distinct examination features., Methods: Through a systematic search of three databases, 21 studies were qualitatively analyzed, with 18 used for meta-analysis. Various outcomes like wheezing on auscultation, fever, atopic traits, and infection severity were evaluated., Results: RSV-positive bronchiolitis was associated with a higher need for oxygen supplementation (OR 1.78, 95% CI 1.04-3.02) in 5 studies, while RV-positive bronchiolitis was more frequently linked to personal history of eczema (OR 0.60, 95% CI 0.41-0.88) in 6 studies. No significant differences were observed in the other outcomes examined., Conclusions: Bronchiolitis caused by RSV or RV presents with similar clinical features. Despite the associations between RSV-positive bronchiolitis and need for oxygen supplementation, and RV-positive bronchiolitis and a history of eczema, our study shows that viral etiology of bronchiolitis cannot be determined solely based on clinical presentation. Tailored management strategies, informed by accurate viral testing, seem crucial in clinical practice for enhancing patient outcomes in severe bronchiolitis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Infants with attenuated type III IFN (IFN-λ) responses are at increased risk of severe lower respiratory tract infection (sLRI). The IL-28Rα-chain and IL-10Rβ-chain form a heterodimeric receptor complex, necessary for IFN-λ signaling. Therefore, to better understand the immunopathogenic mechanisms through which an IFN-λ lo microenvironment predisposes to a sLRI, we inoculated neonatal wild-type and IL-28R-deficient ( IL-28R -/- ) mice with pneumonia virus of mice, a rodent-specific pneumovirus. Infected IL-28R -/- neonates displayed an early, pronounced, and persistent neutrophilia that was associated with enhanced reactive oxygen species (ROS) production, NETosis, and mucus hypersecretion. Targeted deletion of the IL-28R in neutrophils was sufficient to increase neutrophil activation, ROS production, NET formation, and mucus production in the airways. Inhibition of protein-arginine deiminase type 4 (PAD4), a regulator of NETosis, had no effect on myeloperoxidase expression, citrullinated histones, and the magnitude of the inflammatory response in the lungs of infected IL-28R -/- mice. In contrast, inhibition of ROS production decreased NET formation, cellular inflammation, and mucus hypersecretion. These data suggest that IFN-λ signaling in neutrophils dampens ROS-induced NETosis, limiting the magnitude of the inflammatory response and mucus production. Therapeutics that promote IFN-λ signaling may confer protection against sLRI., (Copyright © 2022 by The American Association of Immunologists, Inc.)

Acute viral bronchiolitis causes significant mortality in the developing world, is the number one cause of infant hospitalisation in the developed world, and is associated with the later development of chronic lung diseases such as asthma. A vaccine against respiratory syncytial virus (RSV), the leading cause of viral bronchiolitis in infancy, remains elusive, and hence new therapeutic modalities are needed to limit disease severity. However, much remains unknown about the underlying pathogenic mechanisms. Neutrophilic inflammation is the predominant phenotype observed in infants with both mild and severe disease, however, a clear understanding of the beneficial and deleterious effects of neutrophils is lacking. In this review, we describe the multifaceted roles of neutrophils in host defence and antiviral immunity, consider their contribution to bronchiolitis pathogenesis, and discuss whether new approaches that target neutrophil effector functions will be suitable for treating severe RSV bronchiolitis.

Rationale: Studies of the immune responses at the site of respiratory syncytial virus (RSV) infection are sparse despite nearly five decades of research into understanding RSV disease. Objectives: To investigate the role of mucosal innate immune responses to RSV and respiratory viral load in infants hospitalized with the natural disease. Methods: Cytokines, viral load, and type 2 innate lymphoid cell (ILC2) levels in nasal aspirates, collected within 24 hours of enrollment, from infants hospitalized with RSV infection were quantified. Measurements and Main Results: RSV severity in infants was categorized based on admission to the general ward (moderate) or the pediatric ICU (severe). Evaluable subjects included 30 patients with severe and 63 patients with moderate disease (median age, 74 d; range, 9-297 d). ILC2s were found in the nasal aspirates of patients with severe disease (0.051% of total respiratory CD45 + cells) to a significantly greater extent than in patients with moderate disease (0.018%, P  = 0.004). Levels of IL-4, IL-13, IL-33, and IL-1β were significantly higher in nasal aspirates of patients with severe disease compared with those of patients with moderate disease. Factors associated with disease severity were gestational age (odds ratio, 0.49; 95% confidence interval, 0.29-0.82; P  = 0.007) and IL-4 (odds ratio, 9.67; 95% confidence interval, 2.45-38.15; P  = 0.001). Conclusions: This study shows, for the first time, that elevated levels of ILC2s is associated with infant RSV severity. The findings highlight the dominance of type-2 responses to RSV infection in infants and suggest an important role of ILC2 in shaping the immune response early during RSV infection.

Neutrophils are crucial to antimicrobial defense, but excessive neutrophilic inflammation induces immune pathology. The mechanisms by which neutrophils are regulated to prevent injury and preserve tissue homeostasis are not completely understood. We recently identified the collagen receptor leukocyte-associated immunoglobulin-like receptor (LAIR)-1 as a functional inhibitory receptor on airway-infiltrated neutrophils in viral bronchiolitis patients. In the current study, we sought to examine the role of LAIR-1 in regulating airway neutrophil responses in vivo . LAIR-1-deficient ( Lair1 -/- ) and wild-type mice were infected with respiratory syncytial virus (RSV) or exposed to cigarette smoke as commonly accepted models of neutrophil-driven lung inflammation. Mice were monitored for cellular airway influx, weight loss, cytokine production, and viral loads. After RSV infection, Lair1 -/- mice show enhanced airway inflammation accompanied by increased neutrophil and lymphocyte recruitment to the airways, without effects on viral loads or cytokine production. LAIR-1-Fc administration in wild type mice, which blocks ligand induced LAIR-1 activation, augmented airway inflammation recapitulating the observations in Lair1 -/- mice. Likewise, in the smoke-exposure model, LAIR-1 deficiency enhanced neutrophil recruitment to the airways and worsened disease severity. Intranasal CXCL1-mediated neutrophil recruitment to the airways was enhanced in mice lacking LAIR-1, supporting an intrinsic function of LAIR-1 on neutrophils. In conclusion, the immune inhibitory receptor LAIR-1 suppresses neutrophil tissue migration and acts as a negative regulator of neutrophil-driven airway inflammation during lung diseases. Following our recent observations in humans, this study provides crucial in-vivo evidence that LAIR-1 is a promising target for pharmacological intervention in such pathologies.

Pulmonary hypertension (PH) has been observed in up to 75% of infants with moderate to severe respiratory syncytial virus (RSV) bronchiolitis and is associated with significant morbidity and mortality in infants with congenital heart disease. The purpose of the present study was to establish a mouse model of PH secondary to RSV bronchiolitis that mimics the disease etiology as it occurs in infants. Neonatal mice were infected with RSV at 5 days of age and then reinfected 4 wk later. Serum-free medium was administered to age-matched mice as a control. Echocardiography and right ventricular systolic pressure (RVSP) measurements via right jugular vein catheterization were conducted 5 and 6 days after the second infection, respectively. Peripheral capillary oxygen saturation monitoring did not indicate hypoxia at 2-4 days post-RSV infection, before reinfection, and at 2-7 days after reinfection. RSV-infected mice had significantly higher RVSP than control mice. Pulsed-wave Doppler recording of the pulmonary blood flow by echocardiogram demonstrated a significantly shortened pulmonary artery acceleration time and decreased pulmonary artery acceleration time-to-ejection time ratio in RSV-infected mice. Morphometry showed that RSV-infected mice exhibited a significantly higher pulmonary artery medial wall thickness and had an increased number of muscularized pulmonary arteries compared with control mice. These findings, confirmed by RVSP measurements, demonstrate the development of PH in the lungs of mice infected with RSV as neonates. This animal model can be used to study the pathogenesis of PH secondary to RSV bronchiolitis and to assess the effect of treatment interventions. NEW & NOTEWORTHY This is the first mouse model of respiratory syncytial virus-induced pulmonary hypertension, to our knowledge. This model will allow us to decipher molecular mechanisms responsible for the pathogenesis of pulmonary hypertension secondary to respiratory syncytial virus bronchiolitis with the use of knockout and/or transgenic animals and to monitor therapeutic effects with echocardiography.

Prostaglandin D2 (PGD2) signals through PGD2 receptor 2 (DP2, also known as CRTH2) on type 2 effector cells to promote asthma pathogenesis; however, little is known about its role during respiratory syncytial virus (RSV) bronchiolitis, a major risk factor for asthma development. We show that RSV infection up-regulated hematopoietic prostaglandin D synthase expression and increased PGD2 release by cultured human primary airway epithelial cells (AECs). Moreover, PGD2 production was elevated in nasopharyngeal samples from young infants hospitalized with RSV bronchiolitis compared to healthy controls. In a neonatal mouse model of severe viral bronchiolitis, DP2 antagonism decreased viral load, immunopathology, and morbidity and ablated the predisposition for subsequent asthma onset in later life. This protective response was abolished upon dual DP1/DP2 antagonism and replicated with a specific DP1 agonist. Rather than mediating an effect via type 2 inflammation, the beneficial effects of DP2 blockade or DP1 agonism were associated with increased interferon-λ (IFN-λ) [interleukin-28A/B (IL-28A/B)] expression and were lost upon IL-28A neutralization. In RSV-infected AEC cultures, DP1 activation up-regulated IFN-λ production, which, in turn, increased IFN-stimulated gene expression, accelerating viral clearance. Our findings suggest that DP2 antagonists or DP1 agonists may be useful antivirals for the treatment of viral bronchiolitis and possibly as primary preventatives for asthma., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Background: As the expression of type III IFN receptor is restricted to the mucosal surfaces, its evaluation could be crucial to characterize the role of IFNλs during bronchiolitis., Objectives: This study was designed to investigate airway type III IFN receptor (IFNLR1/IL10RB) expression during respiratory syncytial virus (RSV) or human rhinovirus (HRV) bronchiolitis., Study Design: Seventy-one 1-6 month old infants hospitalized with their first episode of acute RSV or HRV bronchiolitis were selected for this study. Expression of IFNLR1, IL10RB and IFN-stimulated genes (ISGs) MxA and ISG56 in cells of nasopharyngeal washings taken within the first 48 h of admission were determined by a real-time hydrolysis probe RT-PCR assay. The ability of types I and III IFNs to induce the expression of both IFNLR1 and IL10RB in vitro was also evaluated., Results: Airway IFNLR1 transcript levels were significantly higher in HRV bronchiolitis infants compared to those with RSV bronchiolitis. No differences were recorded for IL10RB-mRNA between RSV or HRV infection. IFNLR1 mRNA levels increased significantly in infants infected with the C species of HRV and in those with a higher clinical score index and with an eosinophil count >3%. There were no correlations in vivo between type III IFN receptors and those of ISGs and neither IFNLR1 nor IL10RB were induced in vitro by IFNs., Conclusions: These results suggest that IFNLR1 are increased in HRV-infected infants with more severe bronchiolitis and blood eosinophilia and in those infected with the HRVC species., (Copyright © 2018. Published by Elsevier B.V.)

Background: Data on how respiratory syncytial virus (RSV) genotypes influence disease severity and host immune responses is limited. Here, we characterized the genetic variability of RSV during 5 seasons, and evaluated the role of RSV subtypes, genotypes, and viral loads in disease severity and host transcriptional profiles., Methods: A prospective, observational study was carried out, including a convenience sample of healthy infants hospitalized with RSV bronchiolitis. Nasopharyngeal samples for viral load quantitation, typing, and genotyping, and blood samples for transcriptome analyses were obtained within 24 hours of hospitalization. Multivariate models were constructed to identify virologic and clinical variables predictive of clinical outcomes., Results: We enrolled 253 infants (median age 2.1 [25%-75% interquartile range] months). RSV A infections predominated over RSV B and showed greater genotype variability. RSV A/GA2, A/GA5, and RSV B/BA were the most common genotypes identified. Compared to GA2 or BA, infants with GA5 infections had higher viral loads. GA5 infections were associated with longer hospital stay, and with less activation of interferon and increased overexpression of neutrophil genes., Conclusions: RSV A infections were more frequent than RSV B, and displayed greater variability. GA5 infections were associated with enhanced disease severity and distinct host immune responses., (© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infections in infants and is characterized by pulmonary infiltration of B cells in fatal cases. We analyzed the B cell compartment in human newborns and identified a population of neonatal regulatory B lymphocytes (nBreg cells) that produced interleukin 10 (IL-10) in response to RSV infection. The polyreactive B cell receptor of nBreg cells interacted with RSV protein F and induced upregulation of chemokine receptor CX3CR1. CX3CR1 interacted with RSV glycoprotein G, leading to nBreg cell infection and IL-10 production that dampened T helper 1 (Th1) cytokine production. In the respiratory tract of neonates with severe RSV-induced acute bronchiolitis, RSV-infected nBreg cell frequencies correlated with increased viral load and decreased blood memory Th1 cell frequencies. Thus, the frequency of nBreg cells is predictive of the severity of acute bronchiolitis disease and nBreg cell activity may constitute an early-life host response that favors microbial pathogenesis., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Severe infection with respiratory syncytial virus (RSV) during infancy is strongly associated with the development of asthma. To identify genetic variation that contributes to asthma following severe RSV bronchiolitis during infancy, we sequenced the coding exons of 131 asthma candidate genes in 182 European and African American children with severe RSV bronchiolitis in infancy using anonymous pools for variant discovery, and then directly genotyped a set of 190 nonsynonymous variants. Association testing was performed for physician-diagnosed asthma before the 7th birthday (asthma) using genotypes from 6,500 individuals from the Exome Sequencing Project (ESP) as controls to gain statistical power. In addition, among patients with severe RSV bronchiolitis during infancy, we examined genetic associations with asthma, active asthma, persistent wheeze, and bronchial hyperreactivity (methacholine PC20) at age 6 years. We identified four rare nonsynonymous variants that were significantly associated with asthma following severe RSV bronchiolitis, including single variants in ADRB2, FLG and NCAM1 in European Americans (p = 4.6x10-4, 1.9x10-13 and 5.0x10-5, respectively), and NOS1 in African Americans (p = 2.3x10-11). One of the variants was a highly functional nonsynonymous variant in ADRB2 (rs1800888), which was also nominally associated with asthma (p = 0.027) and active asthma (p = 0.013) among European Americans with severe RSV bronchiolitis without including the ESP. Our results suggest that rare nonsynonymous variants contribute to the development of asthma following severe RSV bronchiolitis in infancy, notably in ADRB2. Additional studies are required to explore the role of rare variants in the etiology of asthma and asthma-related traits following severe RSV bronchiolitis.

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.

Backgroud: Children who suffer a viral lower respiratory infection early in life are prone to subsequent wheezing and asthma: RSV and rhinovirus are thought to be the primary causative pathogens. Epidemiologic and long-term data on these pathogens in Thailand are limited., Objectives: To detect the causative pathogens in children hospitalized with a first episode of acute wheezing and to compare the respective impact on the recurrence of wheezing and development of asthma., Method: We conducted a 5-year cohort study of children under 2 hospitalized with acute bronchiolitis at two tertiary hospitals. Nasopharyngeal secretions were collected at admission to determine the causative pathogens by RT-PCR., Results: 145/170 samples (85%) were positive for pathogens. RSV, rhinovirus, influenza, bacteria and hMPV was found in 64.7%, 18.2%, 17.6%, 12.9% and 3.5% of children respectively. The majority (94/152; 62%) of participants reported having recurrent wheezing within the first year of follow-up (mean duration 5.5 ± 7.2 months). Only 16% still had wheezing episodes after 5 years. Asthma was diagnosed in 41 children (45%), most of whom were treated with inhaled corticosteroid. There were no statistically significant differences among the various etiologies., Conclusion: Rhinovirus ranked second after RSV as the cause of hospitalizations of children with acute bronchiolitis. More than half of these children had recurrent wheezing which mostly disappeared before the age of 6. Nearly half were subsequently diagnosed with asthma at the 5th year of follow-up. The specific pathogens did not account for a statistically significant difference in subsequent wheezing or asthma development.

Introduction: Respiratory insufficiency due to severe respiratory syncytial virus (RSV) infection is the most frequent cause of paediatric intensive care unit admission in infants during the winter season. Previous studies have shown increased levels of inflammatory mediators in airways of mechanically ventilated children compared to spontaneous breathing children with viral bronchiolitis. In this prospective observational multi-center study we aimed to investigate whether this increase was related to disease severity or caused by mechanical ventilation., Materials and Methods: Nasopharyngeal aspirates were collected <1 hour before intubation and 24 hours later in RSV bronchiolitis patients with respiratory failure (n = 18) and non-ventilated RSV bronchiolitis controls (n = 18). Concentrations of the following cytokines were measured: interleukin (IL)-1α, IL-1β, IL-6, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-1α., Results: Baseline cytokine levels were comparable between ventilated and non-ventilated infants. After 24 hours of mechanical ventilation mean cytokine levels, except for MIP-1α, were elevated compared to non-ventilated infected controls: IL-1α (159 versus 4 pg/ml, p<0.01), IL-1β (1068 versus 99 pg/ml, p<0.01), IL-6 (2343 versus 958 pg/ml, p<0.05) and MCP-1 (174 versus 26 pg/ml, p<0.05)., Conclusions: Using pre- and post-intubation observations, this study suggests that endotracheal intubation and subsequent mechanical ventilation cause a robust pulmonary inflammation in infants with RSV bronchiolitis.

Viral illness with wheezing during infancy is associated with the inception of childhood asthma. Small airway dysfunction is a component of childhood asthma, but little is known about how viral illness at an early age may affect the structure and function of small airways. We used a well-characterized rat model of postbronchiolitis chronic airway dysfunction to address how postinfectious small airway lesions affect airway physiological function and if the structure/function correlates persist into maturity. Brown Norway rats were sham- or virus inoculated at 3 to 4 weeks of age and allowed to recover from the acute illness. At 3 to 14 months of age, physiology (respiratory system resistance, Newtonian resistance, tissue damping, and static lung volumes) was assessed in anesthetized, intubated rats. Serial lung sections revealed lesions in the terminal bronchioles that reduced luminal area and interrupted further branching, affecting 26% (range, 13-39%) of the small airways at 3 months of age and 22% (range, 6-40%) at 12 to 14 months of age. At 3 months of age (n = 29 virus; n = 7 sham), small airway lesions correlated with tissue damping (rs = 0.69) but not with Newtonian resistance (rs = 0.23), and Newtonian resistance was not elevated compared with control rats, indicating that distal airways were primarily responsible for the airflow obstruction. Older rats (n = 7 virus; n = 6 sham) had persistent small airway dysfunction and significantly increased Newtonian resistance in the postbronchiolitis group. We conclude that viral airway injury at an early age may induce small airway lesions that are associated quantitatively with small airway physiological dysfunction early on and that these defects persist into maturity.

ROS production is an important effector mechanism mediating intracellular killing of microbes by phagocytes. Inappropriate or untimely ROS production can lead to tissue damage, thus tight regulation is essential. We recently characterized signal inhibitory receptor on leukocytes-1 (SIRL-1) as an inhibitory receptor expressed by human phagocytes. Here, we demonstrate that ligation of SIRL-1 dampens Fc receptor-induced ROS production in primary human phagocytes. In accordance, SIRL-1 engagement on these cells impairs the microbicidal activity of neutrophils, without affecting phagocytosis. The inhibition of ROS production may result from reduced ERK activation, since co-ligation of Fc receptors and SIRL-1 on phagocytes inhibited phosphorylation of ERK. Importantly, we demonstrate that microbial and inflammatory stimuli cause rapid downregulation of SIRL-1 expression on the surface of primary neutrophils and monocytes. In accordance, SIRL-1 expression levels on neutrophils in bronchoalveolar lavage fluid from patients with neutrophilic airway inflammation are greatly reduced. We propose that SIRL-1 on phagocytes sets an activation threshold to prevent inappropriate production of oxygen radicals. Upon infection, SIRL-1 expression is downregulated, allowing microbial killing and clearance of the pathogen., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Viruses are detected in most hospitalized children admitted for acute respiratory infections. Etiologic understanding is needed to improve clinical management and prevention, particularly in resource-limited tropical countries., Methods: A 3-year prospective descriptive study was conducted among Cambodian children admitted to 2 provincial hospitals for acute lower respiratory tract infection. Molecular detection for 18 viral pathogens using multiplex polymerase chain reaction/reverse transcription polymerase chain reactions was performed., Results: We enrolled 1006 children less than 5 years of age of whom 423 (42%), 428 (42%) and 155 (16%) had pneumonia, bronchiolitis and unclassified lower respiratory tract infections, respectively. Of the 551 (55%) with documented viral infection, a single virus was detected in 491 (89%), including rhinovirus (n = 169; 34%), respiratory syncytial virus (n = 167; 34%), parainfluenza virus (n = 40; 8%), human metapneumovirus (n = 39; 8%), influenza virus (n = 31; 6%), bocavirus (n = 16; 3%), adenovirus (n = 15; 3%), coronavirus (n = 9; 2%) and enterovirus (n = 5; 1%). Coinfections with multiple viruses were detected in 6% (2 viruses detected in 59 cases; 3 viruses detected in 1 case)., Conclusion: Similar to other tropical countries, rhinovirus and respiratory syncytial virus were the principal viral pathogens detected among children hospitalized for lower tract respiratory infection in Cambodia.

Human parainfluenza viruses (HPIVs) are a common cause of acute respiratory illness throughout life. Infants, children, and the immunocompromised are the most likely to develop severe disease. HPIV1 and HPIV2 are best known to cause croup while HPIV3 is a common cause of bronchiolitis and pneumonia. HPIVs replicate productively in respiratory epithelial cells and do not spread systemically unless the host is severely immunocompromised. Molecular studies have delineated how HPIVs evade and block cellular innate immune responses to permit efficient replication, local spread, and host-to-host transmission. Studies using ex vivo human airway epithelium have focused on virus tropism, cellular pathology and the epithelial inflammatory response, elucidating how events early in infection shape the adaptive immune response and disease outcome., (Published by Elsevier B.V.)

Objective: To study the pulmonary pathology in patients died of fatal human influenza A(H1N1) infection., Methods: Eight cases of fatal human influenza A (H1N1) infection, including 2 autopsy cases and 6 paramortem needle puncture biopsies, were enrolled into the study. Histologic examination, immunohistochemitry, flow cytometry and Western blotting were carried out., Results: The major pathologic changes included necrotizing bronchiolitis with surrounding inflammation, diffuse alveolar damage and pulmonary hemorrhage. Influenza viral antigen expression was detected in the lung tissue by Western blotting. Immunohistochemical study demonstrated the presence of nuclear protein and hemagglutinin virus antigens in parts of trachea, bronchial epithelium and glands, alveolar epithelium, macrophages and endothelium. Flow cytometry showed that the apoptotic rate of type II pneumocytes (32.15%, 78.15%) was significantly higher than that of the controls (1.93%, 3.77%)., Conclusion: Necrotizing bronchiolitis, diffuse alveolar damage and pulmonary hemorrhage followed by pulmonary fibrosis in late stage are the major pathologic changes in fatal human influenza A (H1N1) infection.

The objective of this study was to determine the efficacy and safety of frequently inhaled nebulized hypertonic saline (HS) in infants with moderate to severe bronchiolitis. One hundred and twenty-six infants were randomized to receive either nebulized 3% hypertonic saline (HS) or 0.9% normal saline (NS), but only 112 patients completed the whole study. Cough, wheezing, pulmonary physical signs, clinical severity scores and the hospital length of stay (LOS) were recorded. The wheezing remission time was 4.8 ± 1.0 days in the NS group and 3.6 ± 0.9 days in the HS group (p <0.01). The cough remission time was 5.5 ± 0.9 days in the NS group and 4.3 ± 0.7 days in the HS group (p <0.01). The moist crackles disappeared at 6.2 ± 0.7 days in the NS group and at 4.4 ± 0.9 days in the HS group (p <0.01). The clinical severity scores decreased more significantly in the HS group than in the NS group on each day within 96 h after enrolment (p <0.01). The LOS decreased from 6.4 ± 1.4 days in the NS group to 4.8 ± 1.2 days in the HS group (p <0.01). The treatment was well tolerated, with no adverse effects attributable to nebulized HS. The conclusions are that frequently inhaled HS relieved symptoms and signs faster than NS, and shortened LOS significantly for infants with moderate to severe bronchiolitis, without apparent adverse effects., (© 2011 The Authors. Journal Compilation © 2011 European Society of Clinical Microbiology and Infectious Diseases.)

We report a case of a 67 year-old-male patient admitted to the intensive care unit in the post-coronary bypass surgery period who presented cardiogenic shock, acute renal failure and three episodes of sepsis, the latter with pulmonary distress at the 30th post-operative day. The patient expired within five days in spite of treatment with vancomycin, imipenem, colistimethate and amphotericin B. At autopsy severe adenovirus pneumonia was found. Viral pulmonary infections following cardiovascular surgery are uncommon. We highlight the importance of etiological diagnosis to a correct treatment approach.

Epidemiological studies demonstrated that the number of emergency-room visits for respiratory indications increases during periods of Florida Red Tides. The purpose of this study was to examine whether or not repeated brevetoxin inhalation, as may occur during a Florida Red Tide, affects pulmonary responses to influenza A. Male F344 rats were divided into four groups: (1) sham aerosol/no influenza; (2) sham aerosol/influenza; (3) brevetoxin/no influenza; and (4) brevetoxin/influenza. Animals were exposed by nose-only inhalation to vehicle or 50 μg brevetoxin-3/m3, 2 h/d for 12 d. On d 6 of aerosol exposure, groups 2 and 4 were administered 10,000 plaque-forming units of influenza A, strain HKX-31 (H3N2), by intratracheal instillation. Subgroups were euthanized at 2, 4, and 7 d post influenza treatment. Lungs were evaluated for viral load, cytokine content, and histopathologic changes. Influenza virus was cleared from the lungs over the 7-d period; however, there was significantly more virus remaining in the group 4 lungs compared to group 2. Influenza virus significantly increased interleukins-1α and -6 and monocyte chemotactic protein-1 in lung; brevetoxin exposure significantly enhanced the influenza-induced response. At 7 d, the severity of perivascular and peribronchiolar inflammatory cell infiltrates was greatest in group 4. Bronchiolitis persisted, with low incidence and severity, only in group 4 at d 7. These results suggest that repeated inhalation exposure to brevetoxin may delay virus particle clearance and recovery from influenza A infection in the rat lung.

Myocarditis in the pediatric population is commonly caused by viral pathogens, notably entero virus and adeno virus. Respiratory syncytial virus, although widespread among this population, is rarely associated with myocarditis. The incidence of myocarditis is unknown due to the variability of clinical presentation and diagnostic limitations. Data regarding prognosis is lacking in children. Patients should be monitored in a pediatric intensive care unit secondary to the risk of hemodynamic compromise. We present the case of fulminant myocarditis in a seven-month old female in the setting of respiratory syncytial virus bronchiolitis.

In June-July 2009, an outbreak of pandemic (H1N1) 2009 infection occurred on a pig farm in Argentina. Molecular analysis indicated that the virus was genetically related to the pandemic (H1N1) 2009 influenza virus strain. The outbreak presumably resulted from direct human-to-pig transmission.

Rationale: There are no reports of the systemic human pathology of the novel swine H1N1 influenza (S-OIV) infection., Objectives: The autopsy findings of 21 Brazilian patients with confirmed S-OIV infection are presented. These patients died in the winter of the southern hemisphere 2009 pandemic, with acute respiratory failure., Methods: Lung tissue was submitted to virologic and bacteriologic analysis with real-time reverse transcriptase polymerase chain reaction and electron microscopy. Expression of toll-like receptor (TLR)-3, IFN-gamma, tumor necrosis factor-alpha, CD8(+) T cells and granzyme B(+) cells in the lungs was investigated by immunohistochemistry., Measurements and Main Results: Patients were aged from 1 to 68 years (72% between 30 and 59 yr) and 12 were male. Sixteen patients had preexisting medical conditions. Diffuse alveolar damage was present in 20 individuals. In six patients, diffuse alveolar damage was associated with necrotizing bronchiolitis and in five with extensive hemorrhage. There was also a cytopathic effect in the bronchial and alveolar epithelial cells, as well as necrosis, epithelial hyperplasia, and squamous metaplasia of the large airways. There was marked expression of TLR-3 and IFN-gamma and a large number of CD8(+) T cells and granzyme B(+) cells within the lung tissue. Changes in other organs were mainly secondary to multiple organ failure., Conclusions: Autopsies have shown that the main pathological changes associated with S-OIV infection are localized to the lungs, where three distinct histological patterns can be identified. We also show evidence of ongoing pulmonary aberrant immune response. Our results reinforce the usefulness of autopsy in increasing the understanding of the novel human influenza A (H1N1) infection.

To evaluate whether KL-6 concentration is a useful biomarker of the severity of respiratory syncytial virus (RSV) bronchiolitis, we determined KL-6 concentrations in patients with RSV bronchiolitis with or without chronic heart disease (CHD). We enrolled 52 patients who had been diagnosed with RSV bronchiolitis and required admission to the hospital at the Department of Pediatrics of Fukushima Medical University School of Medicine from 2004 to 2005. These patients were divided into two groups: Group 1 consisted of patients without any underlying disease, and Group 2 consisted of patients with CHD. These patients were assigned to three categories. Stage A consisted of patients without oxygen dosage, stage B of patients who required oxygen dosage, and stage C of patients required artificial respiration. We evaluated baseline characteristics, clinical features, and serum KL-6 concentration in Group 1, Group 2, and a control group (healthy infants without infection). Mean serum KL-6 concentrations in patients with RSV bronchiolitis were higher than those in the control group (471.8 +/- 236.9 and 127.1 +/- 69.1 U/ml, respectively). Mean serum KL-6 concentration was higher in Group 2 than in Group 1 (692.8 +/- 313.1 and 390.4 +/- 132.7 U/ml, respectively). Mean serum KL-6 concentrations were higher in stage C than in stages A and B, and mean serum KL-6 concentrations were higher in stage B than in stage A. These findings suggest that serum KL-6 is associated with the severity of RSV bronchiolitis and that it may be a useful biomarker for the severity of RSV bronchiolitis., ((c) 2009 Wiley-Liss, Inc.)

Respiratory syncytial virus (RSV) and influenza virus are common causes of infantile lower respiratory tract infection (LRTI). It is widely believed that both viral replication and inappropriately enhanced immune responses contribute to disease severity. In infants, RSV LRTI is known to be more severe than influenza virus LRTI. We compared cytokines and chemokines in secretions of infants surviving various forms of respiratory illness caused by RSV or influenza viruses, to determine which mediators were associated with more severe illness. We analyzed lung tissue from fatal cases of RSV and influenza LRTI to determine the types of inflammatory cells present. Quantities of lymphocyte-derived cytokines were minimal in secretions from infants with RSV infection. Concentrations of most cytokines were greater in influenza, rather than RSV, infection. Lung tissues from fatal RSV and influenza LRTI cases demonstrated extensive presence of viral antigen and a near absence of CD8-positive lymphocytes and natural killer cells, with marked expression of markers of apoptosis. Severe infantile RSV and influenza virus LRTI is characterized by inadequate (rather than excessive) adaptive immune responses, robust viral replication and apoptotic crisis.

The present study included 80 Egyptians infants with acute bronchiolitis; age ranged from 2 to 22 month and consisted of 60 males and 20 females. In addition, 30 apparently healthy infants of matched age and sex were also included as controls. Besides taking history, thorough clinical examination and routine laboratorial investigations, arterial oxygen saturation, RSV tissue culture of nasopharyngeal lavage, indirect immnoflourescence for serum IgM against RSV, serum IL-4 and IFN-gamma were done. Results obtained showed that viral bronchiolitis is predominant in male around 6 month of age and in winter months. RSV was identified in 72.5% of cases. Level of serum IL-4 was significantly higher in RSV positive patients than either RSV negative patients or controls (P < 0.001). Furthermore, in RSV positive patients, IL-4 level was significantly higher in severe and fatal cases than in milder and surviving cases (P < 0.001). Serum IFN-gamma showed no significant difference between RSV positive and RSV negative patients in RSV positive cases it was significantly lower in more severe and fatal cases than milder and living ones (P < 0.05). The ratio IL-4/ IFN-gamma was significantly higher in RSV positive than RSV negative and controls (P < 0.001 and P < 0.05 respectively). Absolute eosinophilic count (AEC) and percent of oxygen saturation (SaO2%) showed significantly lower values in RSV positive patients than RSV negative (P < 0.001), but the latter showed significantly higher AEC than controls (P < 0.05). In RSV positive group, both parameters were significantly lower in more severe and fatal cases than milder and living ones (P < 0.001). In RSV positive group, significant positive correlations were found between disease severity and either serum IL-4 or IL-4 /IFN-gamma ratio (r = 0.789 and r = 0.823, P < 0.001 respectively) but disease severity was inversely correlated with either AEC or SaO2 % (r = -0.962 and r = -0.828, P < 0.001 respectively). RSV was identified as the major etiologic virus of bronchiolitis in young infants. Viral tissue cultures and indirect immunoflourescene are of equally diagnostic value but both may be needed. Most of the severe and fatal cases are in RSV positive group. Th2/Th1 imbalance reflected on IL-4/IFN-gamma ratio is more deranged in RSV bronchiolitis with Th2 predominance especially in more severe and fatal cases. These conclusions may be a rationale for the implementation of antiviral drugs in severe cases of bronchiolitis, however, further studies are needed to demonstrate the effect of antiviral drugs on cytokines levels during therapy.

Acute viral bronchiolitis is a common respiratory infectious disease of infancy. A prospective study was carried out with 175 infants aged up to six months to evaluate their nutritional and breastfeeding status as possible risk factors for unfavourable evolution of previously-healthy infants from a care hospital. Immunofluorescence test for virus and anthropometric assessment were performed. Outcomes were length of oxygen-use, length of hospital stay, and type of hospital unit needed. Seventy-three percent of the infants were well-nourished, 6% undernourished, 8.6% at a nutritional risk, 10.9% overweight, and 1.7% obese. Eighty-one percent of the undernourished and nutritionally at-risk infants and 72% of the well-nourished, overweight, and obese infants did not receive exclusive breastfeeding. The median length of hospital stay was four days and of oxygen-use was 60 hours. The nutritional status did not affect the clinical course of previously-healthy infants with acute viral brochiolitis. The duration of exclusive breastfeeding, but not type of breastfeeding, was inversely related to the length of oxygen-use and the length of hospital stay. Shorter exclusive breastfeeding was observed in infants who were assigned to a paediatric ward or to an intensive care unit. In conclusion, longer duration of breastfeeding was associated with better clinical outcomes.

The pathology of respiratory syncytial virus (RSV) infection was evaluated 1 day after an outpatient diagnosis of RSV in a child who died in a motor vehicle accident. We then identified 11 children with bronchiolitis from the Vanderbilt University autopsy log between 1925 and 1959 who met criteria for possible RSV infection in the preintensivist era. Their tissue was re-embedded and evaluated by routine hematoxylin and eosin and PAS staining and immunostaining with RSV-specific antibodies. Tissue from three cases was immunostain-positive for RSV antigen and was examined in detail. Small bronchiole epithelium was circumferentially infected, but basal cells were spared. Both type 1 and 2 alveolar pneumocytes were also infected. Although, not possible for archival cases, tissue from the index case was evaluated by immunostaining with antibodies to define the cellular components of the inflammatory response. Inflammatory infiltrates were centered on bronchial and pulmonary arterioles and consisted of primarily CD69+ monocytes, CD3+ double-negative T cells, CD8+ T cells, and neutrophils. The neutrophil distribution was predominantly between arterioles and airways, while the mononuclear cell distribution was in both airways and lung parenchyma. Most inflammatory cells were concentrated submuscular to the airway, but many cells traversed the smooth muscle into the airway epithelium and lumen. Airway obstruction was a prominent feature in all cases attributed to epithelial and inflammatory cell debris mixed with fibrin, mucus, and edema, and compounded by compression from hyperplastic lymphoid follicles. These findings inform our understanding of RSV pathogenesis and may facilitate the development of new approaches for prevention and treatment.

Exposure to immunosuppressive environmental contaminants is a possible contributing factor to increased occurrence of viral respiratory diseases. The objective of this study was to test the hypothesis that the trichothecene mycotoxin T-2 toxin (T-2), a frequent food contaminant, alters host resistance to lung infection by reovirus, a model respiratory virus. Balb/c mice (4 week old) were treated intraperitoneally with T-2 toxin (1.75 mg/kg bw) or saline vehicle and then intranasally instilled 2 h later with 10(7) plaque forming unit (PFU) of reovirus, strain Lang (T1/L) or saline vehicle. At 10 days post-instillation (PI), both virus plaque-forming responses and reovirus L2 gene expression were 10-fold higher in lungs of T-2-treated mice compared to controls. No-effect and lowest-effect levels for T-2-induced suppression of reovirus clearance were 20 and 200 microg/kg bw, respectively. Respiratory reovirus infection resulted in a mild bronchiolitis with minimal alveolitis, which was markedly exacerbated by T-2 pretreatment. Reovirus exposure induced marked increases in total cells, neutrophils and lymphocytes at 3 and 7 days PI in bronchial alveolar lavage fluid (BALF) whereas macrophages were increased only at 7 days PI. Although prior T-2 exposure attenuated total cell and macrophage counts in BALF of control and infected mice at 3 days PI, the toxin potentiated total cell, macrophage, neutrophil and lymphocyte counts in infected mice at 7 days PI. At 3 days PI, T-2 suppressed reovirus-induced IFN-gamma elevation in BALF, but enhanced production of IL-6 and MCP-1. T-2 pretreatment also suppressed reovirus-specific mucosal IgA responses in lung and enteric tract, but potentiated serum IgA and IgG responses. Taken together, T-2 increased lung viral burden, bronchopneumonia and pulmonary cellular infiltration in reovirus-infected mice. These effects might be attributable to reduced alveolar macrophage levels as well as modulated cytokine and mucosal Ig responses.

Complex airway diseases such as asthma and chronic obstructive pulmonary disease exhibit stereotyped traits (especially airway hyperreactivity and mucous cell metaplasia) that are variably expressed in each patient. Here, we used a mouse model for virus-induced long-term expression of these traits to determine whether individual traits can be genetically segregated and thereby linked to separate determinants. We showed that an F2 intercross population derived from susceptible and nonsusceptible mouse strains can manifest individual phenotypic extremes that exhibit one or the other disease trait. Functional genomic analysis of these extremes further indicated that a member of the calcium-activated chloride channel (CLCA) gene family designated mClca3 was inducible with mucous cell metaplasia but not airway hyperreactivity. In confirmation of this finding, we found that mClca3 gene transfer to mouse airway epithelium was sufficient to induce mucous cell metaplasia but not airway hyperreactivity. However, newly developed mClca3(-/-) mice exhibited the same degree of mucous cell metaplasia and airway hyperreactivity as wild-type mice. Bioinformatic analysis of the Clca locus led to the identification of mClca5, and gene transfer indicated that mClca5 also selectively drives mucous cell metaplasia. Thus, in addition to the capacity of CLCA family members to exhibit diverse functional activities, there is also preserved function so that more than one family member mediates mucous cell metaplasia. Nonetheless, Clca expression appears to be a selective determinant of mucous cell metaplasia so that shared homologies between CLCA family members may still represent a useful target for focused therapeutic intervention in hypersecretory airway disease.

Background: Cysteinyl leukotrienes (CysLTs), including LTC4, LTD4 and LTE4, are pivotal mediators in the pathophysiology of asthma., Aim: To determine whether CysLT levels are increased in the lower airways of children with respiratory syncytial virus (RSV) bronchiolitis, as they are in asthmatic children, and to investigate a possible heterogeneity in CysLT levels in children with RSV bronchiolitis., Methods: Bronchoalveolar lavage (BAL) fluids were obtained from children with acute RSV bronchiolitis (n = 20), from children with acute asthma who had no identifiable virus infection (n = 16) and from control subjects (n = 14). BAL cell counts and differentials were determined, and the concentrations of CysLTs were measured by ELISA., Results: CysLT levels in the asthma (70.6 +/- 52.7 pg/ml, p < 0.001) and bronchiolitis groups (21.9 +/- 23.3 pg/ml, p < 0.05) were significantly higher than in the control group (8.7 +/- 5.2 pg/ml). Among bronchiolitis subjects, the eosinophil-positive subgroup (n = 6) showed significantly higher CysLT levels (49.0 +/- 26.7 pg/ml, p = 0.001) than the control group, but this was not observed in the eosinophil-negative subgroup (n = 14, 10.3 +/- 6.3 pg/ml, p = 0.47)., Conclusion: CysLT levels are increased in the lower airways during RSV bronchiolitis, although their intensities are lower than those in acute asthma. Among bronchiolitis subjects, high CysLT producers could be distinguished from low CysLT producers by the presence of eosinophilia in BAL fluids, suggesting a pathophysiological heterogeneity in RSV bronchiolitis.

Background: Little is known about the longitudinal changes in the ciliated respiratory epithelium of infants following viral bronchiolitis. A study was undertaken to investigate the time required for the ciliated epithelium to return to normal following bronchiolitis in infants treated with inhaled steroids or placebo., Methods: Thirty one previously healthy term infants were studied as part of a clinical trial to determine the effect of 12 weeks of treatment with inhaled fluticasone (FP) or placebo via a spacer device (17 FP, 14 placebo). Nineteen healthy children aged 0-6 years previously studied in our department were used as controls. Nasal biopsy specimens were taken from infants with bronchiolitis and ciliary beat frequency (CBF) was measured before treatment and repeated 3, 6, 12, and 24 weeks later. The epithelial ultrastructure was examined by transmission electron microscopy and a normal errors mixed model based on normal controls was used to examine the time for cilia to return to normal in bronchiolitic infants., Results: The mean CBF of infants with bronchiolitis (in Hz) at weeks 0, 3, 6, 12, and 24 were 0.5 (n = 4), 10.9 (n = 4), 12.0 (n = 9), 11.9 (n = 8), and 12.1 (n = 7) in the placebo group and 10.6 (n = 6), 11.4 (n = 9), 8.8 (n = 8), 10.9 (n = 4), and 13.2 (n = 7) in the FP group. The time for the epithelial ultrastructure to normalise was as follows: epithelial integrity score (13.1 weeks), % ciliated cells with loss of cilia (14.0 weeks), and % epithelial cells with abnormalities in projection (16.7 weeks) or mitochondria (15.9 weeks). Inhaled steroids had no significant effects on CBF or epithelial ultrastructure., Conclusion: Ciliary loss and epithelial abnormalities persist on average for 13-17 weeks following acute bronchiolitis in infancy.

Respiratory syncytial virus-induced bronchiolitis has been linked to the development of allergy and atopic asthma. IL-12 and possibly IL-18 are central mediators orchestrating Th1 and/or Th2 immune responses to infection. To determine a possible role for IL-12 in regulating the immune response to acute respiratory syncytial virus infection, IL-12p40 gene-targeted (IL-12p40-/-) and wild-type mice were intratracheally infected with respiratory syncytial virus, and lung inflammatory and immune responses were assessed. Lung inflammation and mucus production were increased in the airways of IL-12p40-/- mice as compared with those of wild-type mice, concurrent with increased levels of the Th2 effector cytokines IL-5 and IL-13. Respiratory syncytial virus clearance and levels of Th1 effector cytokine IFN-gamma were not altered. Interestingly, IL-18, another mediator of IFN-gamma production, was significantly increased in the lungs of IL-12p40-/- mice early during the course of infection. Abrogation of IL-18-mediated signaling in IL-12p40-/- mice further enhanced Th2 immune response and mucus production in the airways during respiratory syncytial virus infection but failed to modulate IFN-gamma production or viral clearance. These findings implicate a role for IL-12 and IL-18 in modulating respiratory syncytial virus-induced airway inflammation distinct from that of viral clearance., (Copyright 2004 The American Association of Immunologists, Inc.)

Aim: To examine over time, the cellular response within the lungs of infants ventilated with respiratory syncytial virus (RSV) bronchiolitis and to compare this response in infants born at term with those born preterm., Methods: Non-bronchoscopic bronchoalveolar lavage (BAL) samples were taken from 47 infants (24 born at term and 23 born preterm) who were ventilated for RSV positive bronchiolitis and 10 control infants. BAL cellularity and differential cell counts were calculated using standard techniques., Results: Total cellularity in BAL over the first four days of ventilation in infants with RSV bronchiolitis was greater in term infants (median 2.2 (IQR 4.27) x 10(6) cells/ml) compared with preterm infants (0.58 (1.28) x 10(6) cells/ml). The magnitude of the cellular response in preterm infants with bronchiolitis was similar to that in the control group measured on day 1 (0.62 (0.77) x 10(6) cells/ml). BAL cellularity decreased progressively from the time of intubation in term infants, but remained relatively constant in preterm infants up to seven days after intubation., Conclusions: There are differences in the magnitude and type of pulmonary cellular response in term and preterm infants ventilated with RSV bronchiolitis. The cellular response in term infants with bronchiolitis differs from that in a control group of infants. These differences may reflect variations in cellular recruitment in the lung and/or variations in airway calibre.

Background: Respiratory syncytial virus (RSV) infection causes bronchiolitis in a minority of children. Using a guinea pig model to determine if an allergic predisposition in the host increases permissiveness to RSV infection or severity of experimental "bronchiolitis," we compared the effects of RSV inoculation between strain 2 (allergy-resistant) and strain 13 (allergy-susceptible) inbred animals., Methods: One month-old, juvenile guinea pigs were classified into four groups (eight guinea pigs per group): (group 1) strain 2, uninfected; (group 2) strain 13, uninfected; (group 3) strain 2, RSV infected; and (group 4) strain 13, RSV infected. Seven days after inoculation, the animals were studied by the following: viral plaque assays for quantification of intrapulmonary RSV; immunohistochemical localization of RSV antigens in lung tissue sections; physiologic assessment of airway obstruction and nonspecific bronchial hyperresponsiveness; quantitative histology of airway T lymphocytes, neutrophils, and eosinophils; and semiquantitative reverse transcriptase-polymerase chain reaction for levels of messenger RNA expression of a panel of proinflammatory cytokines and chemokines., Results: Significantly higher titers of replicating RSV were isolated from the lungs of strain 13 vs strain 2 animals (p < or = 0.001). The two guinea pig strains showed similar cell types with positive viral immunostaining; RSV-associated changes in airway obstruction and nonspecific bronchial hyperresponsiveness; airway T cells, neutrophils, and eosinophils; and messenger RNA expression of cytokines and chemokines., Conclusions: Strain 13 guinea pigs show increased pulmonary RSV replication than strain 2 animals, but this increased permissiveness to the virus is not reflected by more severe virus-induced changes in airway obstruction, nonspecific bronchial hyperresponsiveness, airway inflammation, or gene expression of proinflammatory cytokines and chemokines.

The effects of immunosuppression were examined in 1.5-month-old calves that were given dexamethasone (DM) before endobronchial inoculation with bovine adenovirus type 3 (BAV-3). Immunohistopathologically, severe necrotizing bronchiolitis with eosinophilic and basophilic intranuclear inclusion bodies was observed both in DM-treated 1.5-month-old infected calves and in non-DM-treated 7-day-old infected calves. These inclusion bodies were correlated with the detection of BAV-3 antigen and viral particles. The presence of inclusion bodies in the desquamated epithelial cells or of BAV-3 antigen, or both, correlated well with the isolated level of BAV-3 in bronchoalveolar lavage (BAL) fluid. Few immunoglobulin (IgG, IgM, and IgA)-containing B lymphocytes or CD8+ T lymphocytes infiltrated the pneumonic lesion in both the 7-day-old and the DM-treated 1.5-month-old infected calves. Thus, depletion of CD8+ T lymphocytes in calves might influence the clearance of BAV-3 from respiratory tissues.

In the last few years, newly recognized paramyxoviruses have been associated with severe disease in several animal species, including swine, as well as in human beings. Recently, a paramyxovirus was isolated from a swine herd in the northcentral United States that experienced an epizootic of respiratory and central nervous system disease. Affected pigs had interstitial pneumonia with necrotizing bronchiolitis and encephalitis characterized by lymphocytic perivasculitis and diffuse gliosis. Germ-free pigs inoculated with this isolate developed mild clinical illness and similar but less severe histopathologic lesions in lungs and brain.

TNF antagonists are effective treatments for rheumatoid arthritis and Crohn's disease, and have been tried with variable success in other diseases caused by immune damage. To test the hypothesis that viral lung diseases caused by respiratory syncytial virus or influenza virus are partly due to overproduction of TNF, we used anti-TNF antibody to treat mice with lung disease caused by these viruses. TNF depletion reduced pulmonary recruitment of inflammatory cells, cytokine production by T cells and the severity of illness without preventing virus clearance. These broad beneficial effects suggest that TNF antagonists might be tested as treatments of human viral lung diseases.

Human (RSV) and bovine (BRSV) respiratory syncytial virus cause similar infections of the lower respiratory tract. Therefore, experimentally infected calves are suited to the study of RSV-induced chronic bronchiolitis. Colostrum-fed calves aged 17-24 days were successfully infected with BRSV. BRSV strain 375 was applied as an aerosol on 4 consecutive days. Clinical symptoms were already evident on the 1st day after infection. The calves were necropsied 12 weeks after the first infection. Focal severe chronic bronchiolitis with atelectasis and focal bronchiolitis obliterans were demonstrated. The bronchiolar lumina were filled with secretion. Transmission electron microscopy revealed an alteration of the ciliogenesis and partial loss of cilia. Immunhistochemically virus P protein could still be detected, mainly in the epithelial cells of the inflamed bronchioli.

Nedocromil sodium is a nonsteroidal anti-inflammatory drug used to control asthmatic attacks. Our hypothesis is that nedocromil sodium inhibits virus-induced airway inflammation, a common trigger of asthma. We nebulized nedocromil sodium into beagle dogs (n = 10, mean +/- SEM ages: 149 +/- 13 days) before and after inoculation with canine adenovirus type 2 (CAV2). Control dogs (n = 10) received saline aerosols and were either infected with CAV2 (Sal/CAV2, n = 7, mean +/- SEM ages: 140 +/- 11 days) or were not infected (Sal/Sal, n = 3, ages: 143 +/- 0 days). All dogs were anesthetized with choralose (80 mg/kg i.v.), intubated, and mechanically ventilated. Pulmonary function tests and bronchoalveolar lavage (BAL) were performed using standard techniques. Pulmonary function tests revealed no significant change between the nedocromil sodium and non-nedocromil-treated groups. The percentage of infected bronchioles was quantitated as the number of inflamed airways of 40 bronchioles examined times 100 for each dog. Nedocromil-treated dogs had significantly (p < 0.05) less mucosal inflammation (mean +/- SEM, 39% +/- 5%), epithelial denudation (36% +/- 5%), and BAL neutrophilia (11 +/- 3) than did Sal/CAV2 dogs (51% +/- 6%, 57% +/- 4%, and 33% +/- 8%, respectively). We concluded that pretreatment with nedocromil sodium aerosols attenuated CAV2-induced airway inflammation in these beagle puppies.

After viral bronchiolitis at an early age, Brown Norway (BN) rats develop chronic airway dysfunction consisting of inflammation, remodeling, episodic reversible obstruction, and hyperresponsiveness. We hypothesized that supplementation of interferon gamma (IFN-gamma) during viral illness would alter the inflammatory response and attenuate the postviral sequelae. Weanling rats were treated daily with aerosolized interferon gamma (IFN-gamma), from 2 d prior through 7 d after inoculation, and compared with saline-treated infected rats and with noninfected control rats. The IFN-gamma treatment had no significant effect on viral titers, growth retardation, or total bronchoalveolar leukocytes, but there was a slight decrease in lung interleukin-4 (IL-4) mRNA (p = 0.015) during the first week. Despite having minimal effects on the acute illness, the IFN-gamma had marked effects on postviral sequelae, the IFN-gamma group having less bronchiolar inflammation (p = 0.025) and fibrosis (p = 0.01), and lacking abnormalities in pulmonary resistance (p = 0.028) and dynamic compliance (p = 0.006) compared with the untreated postviral group. We conclude that IFN-gamma modulated the inflammatory response to viral illness, such that acute airway injury did not evolve into chronic airway dysfunction. If similar processes contribute to the development of human asthma, it may be possible to interrupt the progression of airway dysfunction with an early immunomodulatory intervention.

The aim of this study was to determine whether interleukin (IL)-8 is released within the upper respiratory tract of infants during respiratory syncytial virus (RSV) bronchiolitis and whether the large number of polymorphonuclear neutrophils (PMNs) present in the respiratory tract of these infants are contributing to the inflammation through release of inflammatory mediators. Twenty-seven infants with acute bronchiolitis were recruited during one winter epidemic and 20 infant control subjects were recruited from a cohort participating in a community-based vaccine study. Samples of airways fluid were obtained using nasal lavage. The lavage fluid was spun to remove the cells, and the supernatant was stored at -70 degrees C. The supernatants were subsequently assayed for the presence of IL-8, total human neutrophil elastase (HNE) and neutrophil elastase activity. In the children with bronchiolitis compared with control infants, elevated levels of IL-8 (median (range) 1.53 (0-153) versus 0 (0-5.6) ng x mL(-1)) HNE (136 (32-694) versus 14 (0-516) ng x mL(-1)) and elastase activity (4 (1-220) versus 1 (0-339) mU x mL(-1)) were found. These results indicate that interleukin-8 is released in the upper respiratory tract in response to respiratory syncytial virus infection and suggest that polymorphonuclear neutrophil products are playing an important role in the inflammatory response to respiratory syncytial virus infection in infants with acute bronchiolitis. This contrasts with the predominantly eosinophilic response evident in atopic upper and lower respiratory tract disease.