Local Interferon‐γ Levels during Respiratory Syncytial Virus Lower Respiratory Tract Infection Are Associated with Disease Severity
Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands. The Journal of Infectious Diseases
(Impact Factor: 6).
09/2001; 184(3):355-8. DOI: 10.1086/322035
To investigate the role of cell-mediated immunity during respiratory syncytial virus (RSV) infection, interferon (IFN)-gamma and interleukin (IL)-10 levels in nasopharyngeal secretions were measured in infants with lower respiratory tract infection (LRTI) caused by RSV. A novel technique was used to measure in vivo cytokine levels in nasopharyngeal aspirates (NPAs). Cytokine levels in the NPAs of 17 mechanically ventilated infants and 43 nonventilated hospitalized infants were compared. As expected, mechanically ventilated infants were significantly younger than nonventilated infants (7 vs. 14 weeks). IFN-gamma levels were above the limit of detection in the NPAs of 3 (18%) mechanically ventilated infants and in the NPAs of 26 (60%) nonventilated infants. IL-10 levels in the NPAs of mechanically ventilated and nonventilated infants were comparable. It is hypothesized that maturation-related mechanisms have a key role in the development of RSV LRTI that results in mechanical ventilation.
Available from: Marije P Hennus
- "For this study we measured cytokine levels in nasopharyngeal aspirates (NPA). A strong correlation exists between cytokine concentrations determined in upper and lower airways , , ,  In order to collect material before the onset of mechanical ventilation as well as to optimize the overall sample collection rate, undiluted NPAs were collected shortly (< 1 hour) before intubation. A second NPA was collected 24 hours after intubation. "
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ABSTRACT: 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.
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.
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).
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.
Available from: PubMed Central
- "Severe RSV bronchiolitis has been associated with deficient IFN-γ production in humans (Bont et al., 2001; Bennett et al., 2007; Garcia et al., 2012), but the role of this cytokine in determining the outcome of re-infection is unknown. To define the role of IFN-γ in the development of RSV-induced AHR and lung histopathology in mice, WT and IFN-γ-/- mice were infected with RSV at a newborn or weaning stage and were re-infected 5 weeks later. "
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ABSTRACT: Asthma inception is associated with respiratory viral infection, especially infection with respiratory syncytial virus (RSV) and/or human rhinovirus (HRV), in the vast majority of cases. However, the reason why RSV and HRV induce the majority of bronchiolitis cases during early childhood and why only a small percentage of children with RSV- and HRV-induced bronchiolitis later develop asthma remains unclear. A genetic association study has revealed the important interaction between viral illness and genetic variants in patients with asthma. Severe RSV- and HRV-induced bronchiolitis may be associated with a deficiency in the innate immune response to RSV and HRV. RSV and HRV infections in infants with deficient innate immune response and the dysfunction of regulatory T cells are considered to be a risk factor for the development of asthma. Sensitization to aeroallergens, beginning in the first year of life, consistently predisposes children to HRV-induced wheezing illnesses, but the converse is not true. Some evidence of virus specificity exists, in that allergic sensitization specifically increased the risk of wheezing in individuals infected with HRV, but not RSV. Administration of Palivizumab, a humanized monoclonal antibody that targets the A antigenic site of the Fusion-protein of RSV, decreases the risk of hospitalization in high-risk infants and the risk of recurrent of wheezing. However, palivizumab did not have any effect on subsequent recurrent wheezing in children with a family history of atopy. These findings suggest that infection with RSV and infection with HRV might predispose individuals to recurrent wheezing through an atopy-independent and an atopy-dependent mechanism, respectively. Respiratory virus-induced wheezing illnesses may encompass multiple sub-phenotypes that relate to asthma in different ways.
Available from: Robert Welliver
- "In all of these studies, the differences in ratios of IFN-γ to Th2 cytokines were determined only by variations in IFN-γ concentrations between the groups. The findings of subsequent studies have also suggested a protective role for IFN-γ in RSV infection of infants [59, 60]. "
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ABSTRACT: Dendritic cells (DCs) are important cells of our innate immune system. Their role is critical in inducing adaptive immunity, tolerance, or allergic response in peripheral organs-lung and skin. The lung DCs are not developed prenatally before birth. The DCs develop after birth presumably during the first year of life; exposures to any foreign antigen or infectious organisms during this period can significantly affect DC developmental programming and generation of distinct DC phenotypes and functions. These changes can have both short-term and long-term health effects which may be very relevant in childhood asthma and predisposition for a persistent response in adulthood. An understanding of DC development at molecular and cellular levels can help in protecting neonates and infants against problematic environmental exposures and developmental immunotoxicity. This knowledge can eventually help in designing novel pharmacological modulators to skew the DC characteristics and immune responses to benefit the host across a lifetime.
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