Immunopathogenesis of respiratory syncytial virus bronchiolitis.
BACKGROUND
The objective of this study was to elucidate the relation between respiratory syncytial virus (RSV) infection and cytokine/chemokine concentrations, as well as the impact that these factors have on the severity of bronchiolitis.


METHODS
Children <24 months old who presented to the emergency department with clinical symptoms of bronchiolitis were prospectively enrolled in the study. Nasal-wash samples were analyzed to identify viral pathogens and to quantify RSV and cytokine/chemokine concentrations. Severe cases of disease were defined as those requiring hospitalization, and severity was further determined on the basis of the duration of supplemental-oxygen and/or intravenous-fluid therapy.


RESULTS
A total of 101 children were enrolled, 63 of whom were infected with RSV and 13 of whom were infected with other respiratory viruses; in 22 children, no virus was detected. RSV bronchiolitis was associated with a greater inflammatory response than was non-RSV bronchiolitis, although RSV infection was not associated with more-severe disease. Levels of interleukin (IL)-6, IL-8, IL-10, interferon (IFN)-gamma, and macrophage inflammatory protein (MIP)-1beta were significantly inversely correlated with the duration of supplemental-oxygen therapy.


CONCLUSIONS
The robust inflammatory response associated with RSV infection does not contribute to the severity of RSV bronchiolitis any more than it contributes to the severity of non-RSV bronchiolitis. Elevated levels of proinflammatory mediators IL-6, IL-8, IFN-gamma, and MIP-1beta, as well as of the regulatory cytokine IL-10, may be protective against hypoxia in bronchiolitis.
Bennett
Berkeley L
BL
Department of Pediatrics, Division of Emergency Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA. ppiedra@bcm.tmc.edu.
Garofalo
Roberto P
RP
Cron
Stanley G
SG
Hosakote
Yashoda M
YM
Atmar
Robert L
RL
Macias
Charles G
CG
Piedra
Pedro A
PA
D001988:Bronchiolitis / Q000276:immunology / Q000473:pathology / Q000821:virology; D018925:Chemokines / Q000032:analysis; D016207:Cytokines / Q000032:analysis; D005260:Female; D020022:Genetic Predisposition to Disease; D006330:Heart Defects, Congenital / Q000150:complications; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D009297:Nasal Mucosa / Q000503:physiopathology; D011446:Prospective Studies; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology* / Q000473:pathology; D012136:Respiratory Syncytial Viruses / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D012141:Respiratory Tract Infections / Q000821:virology
D018925:Chemokines; D016207:Cytokines