RANTES may be predictive of later recurrent wheezing after respiratory syncytial virus bronchiolitis in infants

Serum Levels of Selected Cytokines and Chemokines and IgG4 in Children With Recurrent Respiratory Tract Infections

Background: Respiratory tract infections are a common health problem. Cytokines/chemokines play a critical role in the regulation of the immune system. Their defective production may predispose to recurrent respiratory tract infections (RRIs), and an excessive immune response may lead to chronic inflammation and cause damage to the respiratory tract. Another biomarker of respiratory infections may be immunoglobulin-IgG4. Its meaning has still been little explored. We wanted to assess the suitability of the levels of biomarkers tested: interleukin (IL)-17A, IL-18, IL-23, normal T cells expressed and secreted (RANTES), and induced protein (IP)-10, as well as immunoglobilun G4 (IgG4) to predict recurrent infections. Methods: The study group (SG) included a total of 130 children (68 girls, 62 boys) between 3 and 17 years of age with RRI. The control group (CG) included 86 healthy children with no symptoms of inflammatory or allergic diseases (44 girls and 42 boys) of the same age. Blood samples were collected in fasting state and then serum samples were frozen and stored until biomarker assay. Results: Serum RANTES, IL-18, IL-23, and IgG4 concentration were higher in all children with recurrent infections vs. those in the CG (p  < 0001). Serum levels of IL-17A and IP-10 were also significantly higher in the SG than in the CG, but only in the youngest children. Among the six serum markers, RANTES demonstrated the highest area under the receiver operating characteristic curve (area under curve) value (0.998, 95% confidence interval [CI]: 0.98-1.0, p < 0.001) for the diagnosis of RRIs, followed by IL-23 (0.99, 95% CI 0.966-0,999, p < 0.001) and IL-18 (0.957, 95% CI 0.921-0.980, p < 0.001). Conclusions: RANTES, IL-23, and IL-18 could be strong predictors of respiratory infections recurrence in children.

Changes in inflammatory biomarkers in the nasal mucosal secretion after septoplasty

Deviated nasal septum (DNS) is suggested to be associated with nonspecific inflammation of the nasal mucosa. The authors hypothesized septoplasty may reduce nasal mucosal inflammation, therefore the authors aimed to measure various inflammatory biomarkers in the nasal secretion following septoplasty. Prospectively, 17 patients undergoing elective septoplasty were included. Symptomatic changes after septoplasty were evaluated with Sino-nasal Outcome Test (SNOT-22) and Nasal obstruction symptom evaluation (NOSE) scores. Using acoustic rhinometry, changes of the nasal airway volume were measured. Nasal secretion was collected within 2 weeks and 3 months before and after septoplasty, respectively. The inflammatory biomarker high-mobility group box 1 (HMGB1) and vasoactive intestinal peptide (VIP), and inflammatory cytokines including tumor necrosis factor α (TNF α), interferon γ (IFN-γ), interleukin-4 (IL-4), eotaxin-1, and regulated upon activation, normal T cell expressed and presumably secreted (RANTES) were quantified in the nasal secretion by enzyme-linked immunosorbent assays or multiplex bead array assays. The patients' mean age was 30.5 ± 6.8 (ranging from 19 to 43), consisting of 15 male and 2 female patients. The median SNOT-22 and NOSE scores changed from 54 to 14 and 78 to 15, respectively, both showing a significant decrease. In acoustic rhinometry, nasal cavity volume of convex side significantly increased after septoplasty, whereas significant discrepancy of nasal airway volume between concave and convex sides became insignificant. No significant difference was noted both before and after septoplasty between the concave and convex sides in all seven biomarkers. The HMGB1, RANTES, IL-4, and TNF-α concentrations following septoplasty showed significant decrease in 34 nasal cavities of 17 patients (all p < 0.05). However, when the 17 concave and 17 convex sides were analyzed separately, the significant reduction in four biomarkers were only significant in the concave sides (all p < 0.05), but not significantly reduced in convex sides. Septoplasty may have benefited not only in normalizing the nasal airflow and symptom improvement, but also in nonspecific inflammation attenuation in the nasal airway.

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

INTRODUCTION

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

CCL5 persists in RSV stocks following sucrose-gradient purification

Respiratory syncytial virus (RSV) is associated with bronchiolitis in infancy and the later development of asthma. Research on RSV in vitro requires preparation of a purified RSV stock. The objective for this work was to develop best methods for RSV purification, while monitoring the samples for potential contaminating proinflammatory mediators. Using polyethylene glycol concentration, and sucrose-gradient ultracentrifugation, we collected samples at each step of purification and measured the values of RSV titer, total protein (µg/mL), and proinflammatory cytokines (ELISA). We analyzed the efficacy of each step in the purification procedure. In so doing, we also determined that despite optimal purification methods, a well-known chemokine in the field of allergic disease, CCL5 (RANTES), persisted within the virus preparations, whereas other cytokines did not. We suggest that researchers should be aware that CCL5 appears to co-purify with RSV. Despite reasonable purification methods, a significant level of CCL5 (RANTES) persists in the virus preparation. This is relevant to the study of RSV-induced allergic disease.

The Human Immune Response to Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is an important etiological agent of respiratory infections, particularly in children. Much information regarding the immune response to RSV comes from animal models and in vitro studies. Here, we provide a comprehensive description of the human immune response to RSV infection, based on a systematic literature review of research on infected humans. There is an initial strong neutrophil response to RSV infection in humans, which is positively correlated with disease severity and mediated by interleukin-8 (IL-8). Dendritic cells migrate to the lungs as the primary antigen-presenting cell. An initial systemic T-cell lymphopenia is followed by a pulmonary CD8+ T-cell response, mediating viral clearance. Humoral immunity to reinfection is incomplete, but RSV IgG and IgA are protective. B-cell-stimulating factors derived from airway epithelium play a major role in protective antibody generation. Gamma interferon (IFN-γ) has a strongly protective role, and a Th2-biased response may be deleterious. Other cytokines (particularly IL-17A), chemokines (particularly CCL-5 and CCL-3), and local innate immune factors (including cathelicidins and IFN-λ) contribute to pathogenesis. In summary, neutrophilic inflammation is incriminated as a harmful response, whereas CD8+ T cells and IFN-γ have protective roles. These may represent important therapeutic targets to modulate the immunopathogenesis of RSV infection.

A systematic review of predictive models for asthma development in children

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A systematic review of predictive modeling for bronchiolitis

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

CONCLUSION

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

The infectious march: the complex interaction between microbes and the immune system in asthma

There has been significant progress in our knowledge about the relationship between infectious disease and the immune system in relation to asthma, but many unanswered questions still remain. Respiratory tract infections such as those caused by respiratory syncytial virus and rhinovirus during the first 2 years of life are still clearly associated with later wheezing and asthma, but the mechanism has not been completely worked out. Is there an "infectious march" triggered by infection in infancy that progresses to disease pathology or are infants who contract respiratory infections predisposed to developing asthma? This review focuses on the common themes in the interaction between microbes and the immune system, and presents a critical appraisal of the evidence to date. The various mechanisms whereby microbes alter the immune response and how this might influence asthma are discussed along with new and promising clinical practices for prevention and therapy. Recent advances in using sensitive polymerase chain reaction detection methods have allowed more rigorous testing of the causality hypothesis of virus infection leading to asthma, but the evidence is still equivocal. Various exceptions and inconsistencies in the clinical trials are discussed in light of new guidelines for subject inclusion/exclusion in hopes of providing some standardization. Despite past failures in vaccination and disappointing results of some clinical trials, the new strategies for prophylaxis including RNA interference and targeted delivery of microbicides offer a large dose of hope to a world suffering from an increasing incidence of asthma as well as a huge burden of health care cost and loss of quality of life.

Correlation between inflammatory mediators in the nasopharyngeal secretion and in the serum of children with lower respiratory tract infection caused by respiratory syncytial virus and disease severity

OBJECTIVE

To determine whether the concentrations of inflammatory mediators (CCL5, soluble intercellular adhesion molecule type 1 [sICAM-1], TNF-alpha, IL-6 and IL-10) in the nasopharyngeal secretion and in the serum of children with lower respiratory tract infection (LRTI) caused by respiratory syncytial virus (RSV) correlate with the clinical markers of disease severity.

METHODS

Between July of 2004 and December of 2005, 30 children less than three months of age, diagnosed with LRTI caused by RSV and admitted to a neonatal ICU, were included in this study.

RESULTS

The severity of disease at hospital admission, as determined with a modified clinical scoring system, presented a significant positive correlation with sICAM-1 and IL-10 concentrations in the nasopharyngeal secretion, as well as with IL-6 concentrations in the serum, of the patients. In addition, serum IL-6 concentrations presented a significant positive correlation with the duration of oxygen therapy and with the length of hospital stay.

CONCLUSIONS

At hospital admission, the concentrations of sICAM-1 and IL-10 in the nasopharyngeal secretion, as well as the concentration of IL-6 in the serum, could be used as markers of severity in patients with LRTI caused by RSV. The serum levels of IL-6 determined at admission could also be used to predict prolonged oxygen supplementation and hospital stay.

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

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

Fosfomycin suppresses chemokine induction in airway epithelial cells infected with respiratory syncytial virus

Respiratory syncytial virus (RSV) infects airway epithelial cells, causing bronchiolitis and pneumonia. Inflammation is mediated by various cytokines secreted from RSV-infected airway epithelial cells, and it promotes the pathogenesis of RSV-related diseases. Fosfomycin (FOF) is approved as a treatment for various bacterial infectious diseases, including respiratory infectious diseases, in Japan. FOF is suggested to exhibit immunomodulatory effects on lipopolysaccharide-stimulated monocytes and T lymphocytes, in addition to its antimicrobial activity. We investigated the effect of FOF on the cytokine production of an airway epithelial cell line, A549, infected with RSV. RSV-induced cytokines, such as regulated on activation, normal T-cell expressed and secreted (RANTES), interleukin-8 (IL-8), and IL-6, in infected A549 cells. We found that FOF decreased the levels of RSV-induced RANTES and IL-8 but not the level of RSV-induced IL-6. The RANTES promoter was activated by RSV infection. Site-directed mutagenesis analysis of the RANTES promoter showed that NF-kappaB-binding motifs had a critical role in RSV-induced RANTES promoter activity. A luciferase reporter gene assay and a DNA-binding assay indicated that FOF suppressed the NF-kappaB activity induced by RSV infection. These results demonstrate that FOF treatment suppresses the RSV-induced transcription of the chemokines RANTES and IL-8 in airway epithelial cells.

Presence of eosinophils in nasal secretion during acute respiratory tract infection in young children predicts subsequent wheezing within two months

BACKGROUND

In young children with wheezing or bronchiolitis, especially with respiratory syncitial virus, blood eosinophilia and a high eosinophil cationic protein level in nasal secretions predicts subsequent wheezing in later childhood. However, whether eosinophil activation results from virus-induced inflammation or local eosinophilia per se precedes the onset of wheezing remains unknown. In the present study, we examined the association between the presence of nasal eosinophils during respiratory tract infection (RTI) and subsequent wheezing in young children.

METHODS

A total of 35 young children less than 3 years of age who visited our outpatient clinic with rhinorrhea between April and July 2004 were enrolled in this prospective cohort study. Subjects who were given diagnoses of allergic rhinitis were excluded. In all the subjects, the presence of eosinophils in nasal secretions was determined. The subjects were followed, and the cumulative incidences of wheezing during the subsequent 2- and 12-month periods were examined.

RESULTS

According to a logistic regression analysis adjusted for age, sex, family history, allergies, and wheezing at entry, young children with nasal eosinophil infiltration during acute RTI had a significantly higher risk of wheezing during the subsequent 2 months, compared with those without nasal eosinophil infiltration (adjusted odds ratio, 27.618, p = 0.016).

CONCLUSIONS

Our findings not only suggest that nasal eosinophil testing may serve as a convenient clinical marker for identifying young children at risk for subsequent wheezing, but also shed new light on the role of eosinophils in the onset of wheezing in young children.

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

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

IL-10 and RANTES are elevated in nasopharyngeal secretions of children with respiratory syncytial virus infection

BACKGROUND

Respiratory syncytial virus (RSV) infection causes asthma-like symptoms in infants and young children. Although an increase in several mediators in the airway during RSV infection has been reported, the mechanisms involved in airway inflammation are not fully understood. The aim of this study was to investigate the immunological deviation associated with airway inflammation by measuring cytokine and chemokine levels in the airway during RSV infection.

METHODS

One hundred and ten children under 3 years of age with respiratory symptoms were enrolled in this study from November 2004 through January 2005. Nasopharyngeal secretions (NPAs) were gently aspirated and analyzed with RSV antigen, thereafter the concentrations of IL-4, IL-10, IFN-gamma, and RANTES were measured using an ELISA kit. We also investigated the prognosis of each child after 1 year by reference to clinical records or by interviews and re-evaluated the cytokine and chemokine levels.

RESULTS

Of the subjects, 70 children were RSV positive and 40 were negative. Only 4 children were given a diagnosis of asthma by the pediatrician when NPAs were collected. The levels of IL-4, IL-10, and RANTES were significantly higher in the RSV-positive patients than RSV-negative patients with P values at 0.0362, 0.0007, and 0.0047, respectively. In contrast, there was no significant difference in the levels of IFN-gamma. Furthermore, there was a significant positive correlation between IL-10 and RANTES.

CONCLUSIONS

The increased production of IL-4, IL-10, and RANTES in the airway may play an important role in the pathophysiological mechanisms of RSV infection.

Eosinophil cationic protein and chemokines in nasopharyngeal secretions of infants with respiratory syncytial virus (RSV) bronchiolitis and non-RSV bronchiolitis

Bronchiolitis is a risk factor for the development of childhood asthma. Eosinophilic inflammation in airways plays an important role in the pathophysiology of both bronchiolitis and asthma. To investigate this inflammation, we measured the eosinophil cationic protein (ECP), regulated on activation normal T-cell expressed and secreted (RANTES) and eotaxin levels in nasopharyngeal secretions (NPS). Twenty-eight patients with RSV bronchiolitis (RSV group), 11 patients with non-RSV bronchiolitis (non-RSV group) and 7 controls were enrolled in this study. ECP, RANTES, and eotaxin levels were measured by enzyme immunoassays. The ECP level in the NPS of the RSV group was significantly higher than that in the NPS of the non-RSV group and controls. RANTES and eotaxin levels in infants with bronchiolitis were significantly higher than those in the controls, but there was no significant difference between the RSV and non-RSV groups. In conclusion, with regard to eosinophilic airway inflammation, as compared with non-RSV bronchiolitis, RSV bronchiolitis may be more similar to childhood asthma.

Bronchiolitis

Bronchiolitis is a distressing, potentially life-threatening respiratory condition that affects young babies. Around 2-3% of all infants younger than 1 year are admitted to hospital with bronchiolitis, usually during the seasonal epidemic. The majority of these infants are infected with respiratory syncytial virus and all have an intense inflammatory response in their airways. Although most infants recover, they have an increased risk of recurrent wheezing. Although bronchiolitis is common, little is known about what causes infants to be susceptible. Diagnostic interventions have little effect on clinical outcome, and apart from supportive measures, there is no specific treatment. Bronchiolitis therefore presents an intriguing clinical conundrum and a major challenge to researchers. High quality clinical studies are needed to clarify assessment of disease severity and criteria for hospital admission, particularly the use of pulse oximetry and chest radiography. Careful mapping of the inflammatory pathways in the pathogenesis of bronchiolitis should lead to development of new therapies to alleviate symptoms.

Serum regulated upon activation, normal T cell expressed and presumably secreted concentrations and eosinophils in respiratory syncytial virus infection

BACKGROUND

The aim of this study was to characterize respiratory syncytial virus (RSV) infection. To do this, the authors evaluated eosinophil counts and chemokines including regulated upon activation, normal T cell expressed and presumably secreted (RANTES) in children with RSV, adenoviral, and influenza virus infections.

METHODS

The authors enrolled 80 patients who had been diagnosed with acute viral respiratory infection caused by RSV, adenoviral, or influenza viruses. In total, 35 patients (Group A) had RSV infection, 18 (Group B) had adenoviral infection, and 27 (Group C) had influenza virus infection. The authors evaluated clinical manifestations, white blood cell and eosinophil counts, and serum chemokines including RANTES concentrations in the acute and recovery phases in each group.

RESULTS

In recovery phase, eosinophil counts were higher in Group A than Groups B and C. In Group A, eosinophil counts were higher in recovery phase than in the acute phase. In Group A, serum RANTES concentration was significantly higher in the recovery phase than in the acute phase (132+/-76 pg/mL vs 52+/-25 pg/mL, P<0.05).

CONCLUSION

The findings suggest that high values of RANTES in children with RSV infection may be associated with the presence of eosinophils and be an important mediator of inflammatory response.

Peroxisome-proliferator-activated receptor-gamma agonists inhibit the release of proinflammatory cytokines from RSV-infected epithelial cells

The epithelial cells of the airways are the target cells for respiratory syncytial virus (RSV) infection and the site of the majority of the inflammation associated with the disease. Recently, peroxisome-proliferator-activated receptor gamma (PPARgamma), a member of the nuclear hormone receptor superfamily, has been shown to possess anti-inflammatory properties. Therefore, we investigated the role of PPARgamma agonists (15d-PGJ(2), ciglitazone and troglitazone) on the synthesis of RSV-induced cytokine release from RSV-infected human lung epithelial cells (A549). We observed that all PPARgamma ligands inhibited dose-dependently the release of TNF-alpha, GM-CSF, IL-1alpha, IL-6 and the chemokines CXCL8 (IL-8) and CCL5 (RANTES) from RSV-infected A549 cells. Concomitantly, the PPARgamma ligands diminished the cellular amount of mRNA encoding for IL-6, CXCL8 and CCL5 and the RSV-induced binding activity of the transcription factors NF-kappaB (p65/p50) and AP-1 (c-fos), respectively. Our data presented herein suggest a potential application of PPARgamma ligands in the anti-inflammatory treatment of RSV infection.

Immune responses and disease enhancement during respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is one of the commonest and most troublesome viruses of infancy. It causes most cases of bronchiolitis, which is associated with wheezing in later childhood. In primary infection, the peak of disease typically coincides with the development of specific T- and B-cell responses, which seem, in large part, to be responsible for disease. Animal models clearly show that a range of immune responses can enhance disease severity, particularly after vaccination with formalin-inactivated RSV. Prior immune sensitization leads to exuberant chemokine production, an excessive cellular influx, and an overabundance of cytokines during RSV challenge. Under different circumstances, specific mediators and T-cell subsets and antibody-antigen immune complex deposition are incriminated as major factors in disease. Animal models of immune enhancement permit a deep understanding of the role of specific immune responses in RSV disease, assist in vaccine design, and indicate which immunomodulatory therapy might be beneficial to children with bronchiolitis.

Respiratory syncytial virus deficient in soluble G protein induced an increased proinflammatory response in human lung epithelial cells

Respiratory syncytial virus (RSV) is worldwide the single most important respiratory pathogen in infancy and early childhood. The G glycoprotein of RSV, named attachment protein, is produced by RSV-infected lung epithelial cells in both a membrane-anchored (mG protein) and a soluble form (sG protein) that is secreted by the epithelial cell. Currently, the biological role of the sG protein in primary RSV infection is still elusive. Therefore, we analyzed the inflammatory response of human lung epithelial cells (A549) infected either with wild-type RSV (RSV-WT) or a spontaneous mutant thereof deficient in the production of secreted G protein (RSV-DeltasG). Our data reveal that RSV-DeltasG, in comparison to RSV-WT, induced an increased cell surface expression of ICAM-1 on A549 cells and an enhanced release of the chemokines IL-8 and RANTES after 20 h postinfection. The increased protein expression pattern correlated with an enhanced mRNA level encoding for ICAM-1, IL-8, and RANTES, respectively. Furthermore, epithelial cells infected with RSV-DeltasG showed a more increased binding activity of the transcription factor NF-kappaB when compared to RSV-WT. In contrast, the mutant RSV-DeltasG replicated less efficiently in A549 cells than RSV-WT. Our data suggest that RSV, in the course of an ongoing infection, reduces by the production of sG protein the detrimental inflammatory response evolved by the infected resident lung epithelial cell and thereby supports its own replication.

Recombinant respiratory syncytial virus lacking secreted glycoprotein G is attenuated, non-pathogenic but induces protective immunity

Respiratory syncytial virus (RSV) causes intense pulmonary inflammatory responses in some infected infants. The surface attachment protein 'G' of RSV has membrane-bound and secreted forms and shows homology to the CX3C chemokine fractalkine. Using recombinant techniques, we generated replication-competent recombinant clonal RSV expressing normal G proteins ('rRSV') or only the membrane-bound form of G ('Gmem rRSV'). Both recombinants grew well in HEp-2 cells, but after primary intranasal infection in mice, pulmonary Gmem rRSV replication was reduced tenfold compared to parental or rRSV; moreover, CCL2 and CCL5 production was greatly reduced and no apparent disease or pulmonary cellular infiltration was observed. However, Gmem rRSV-infected mice developed good antibody responses and were fully protected against subsequent intranasal challenge with parental virus. Even in mice sensitized to G by cutaneous infection with recombinant vaccinia expressing G, intranasal challenge with Gmem rRSV caused insignificant disease. We conclude that secreted G is a key viral product assisting virus replication in vivo, enhancing CCL2 and CCL5 production and promoting illness. Engineered RSV mutants lacking the ability to secrete G are thus promising vaccine candidates.

The role of RANTES in a murine model of food allergy

Food allergy is an important and common health issue, and there is a need to identify and characterize the sensitizing mechanisms. One of the common causes of food allergy is ovalbumin (OVA), a dietary antigen from eggs. We hypothesized that OVA-induced food allergy in the gut involves the activation of the chemokine regulated on activation, normal T cell expressed and secreted (RANTES), which then recruits eosinophils to lesioned tissue. The purpose of this study was to clarify whether RANTES expression correlates with eosinophil infiltration in the gut of OVA-sensitized BALB/c mice in response to oral OVA challenge. BALB/c mice were immunized with OVA 1 microg and sensitized after 2 weeks by intragastric administration of OVA. Sensitization to the oral OVA challenge was analyzed by examining eosinophil infiltration into the gut tissue (immunohistochemistry), mucosal eosinophil cationic protein (ECP) concentration, and RANTES mRNA expression (reverse-transcriptase polymerase chain reaction and Southern blotting) at 3, 6, 12, and 24 h after the challenge. There was marked edema of the intestinal villi, and eosinophil infiltration to the lamina propria peaked at 6 h in OVA-sensitized mice. RANTES mRNA expression peaked at 3 h and 6 h and declined thereafter. The expression of RANTES mRNA in the allergic mice was much higher than in the nonallergic, normal, or unsensitized control mice. Tissue eosinophilia and intestinal ECP levels were significantly correlated with the RANTES mRNA level. We conclude that RANTES may play a central role in the pathogenesis of food-mediated gastrointestinal allergy.