Pro- and anti-inflammatory responses in respiratory syncytial virus bronchiolitis

Abstract

Respiratory syncytial virus (RSV) bronchiolitis is an important cause of severe respiratory disease in infants. This study aimed to characterise changes in pulmonary pro-and anti-inflammatory responses in infants with RSV bronchiolitis over the course of the illness.On the day of intubation (Day 1) and the day of extubation (Day X), nonbronchoscopic bronchoalveolar lavage was performed on term and preterm infants ventilated for RSV bronchiolitis and on control infants on Day 1. Tumour necrosis factor (TNF)-a, soluble TNF receptor (sTNFR) and interleukin (IL)-6 messenger ribonucleic acid (mRNA) and protein were measured.Twenty-four infants, born at term and 23 infants born preterm with RSV bronchiolitis and 10 controls were recruited. TNF-a and IL-6 mRNA and protein in infants with bronchiolitis were greater than the control group on Day 1. In preterm infants, who were ventilated for longer than term infants, TNF-a and IL-6 proteins decreased between Day 1 and Day X. Concentrations of sTNFRs differed between groups on Day 1, but levels did not change between Day 1 and Day X.Large amounts of tumour necrosis factor-a and interleukin-6 in the respiratory syncytial virus-infected lung suggest important roles for these cytokines in the pathogenesis of respiratory syncytial virus bronchiolitis. The decrease in tumour necrosis factor-a and interleukin-6 protein in preterm infants may reflect the prolonged clinical course seen in these infants.

Aberrant T cell immunity triggered by human Respiratory Syncytial Virus and human Metapneumovirus infection

“…This observation suggest that a mixed T H 1/T H 2 response is generated at the first stage of the disease. 79 Consistently with this observation, a mixed T H 1/T H 2 response was also observed in the lung of hRSV-infected mice, although with a significant increase of IL-13, which is known to induce airway hyperreactivity. 80,81 The predominant T H 2 immune response observed in infants and children could be due to the capacity of hRSV to polarize the adaptive immune response from a protective T H 1 phenotype to a T H 2-type response.…”

Age-dependent differences in the pathogenesis of bovine respiratory syncytial virus infections related to the development of natural immunocompetence

“…TNF-a is known as a potent mediator of inflammation and plays a key role during the inflammatory responses of hRSV bronchiolitis (Becnel et al, 2005;McNamara et al, 2004;Morrison et al, 2007). TNF-a may play a protective role in RSV infection (Neuzil et al, 1996).…”

Cytokine responses in primary and secondary respiratory syncytial virus infections

“…IL-17-producing T cells are induced in primary infections through pathways that involve STAT3 and IL-6 (16,17). High levels of IL-6 have been found in the airways of infants with RSV bronchiolitis (18,19), and a number of studies have identified IL-17 in the airways (20)(21)(22)(23)(24) and plasma (21,24) of infants with RSV infection. Two studies have found lower levels of IL-17 in the airways of the most severely affected infants, and the authors suggested that higher IL-17 levels were associated with protection against more severe disease (21,24).…”