Series de Pediatría Garrahan. El niño con problemas respiratorios / Garrahan Pediatrics Series. The child with respiratory problems

La patología respiratoria presenta un gran desafío para las instituciones de salud, por su frecuencia, su complejidad diagnóstica y terapéutica y la carga que representa en costos económicos y vitales. Estos conceptos se extienden a todos los grupos etarios y sus características han ido cambiando a lo largo del tiempo ante los avances producidos en las inmunizaciones, los métodos diagnósticos y los tratamientos. Aún así, las infecciones respiratorias bajas son todavía la causa más frecuente de consulta, internación, morbilidad crónica, discapacidad y mortalidad en pediatría. Este nuevo volumen aborda esta temática especial y entre sus características se destacan: El estudio de las patologías más frecuentes en los diferentes ámbitos de atención pero en particular en el primer nivel, con una exposición centrada en los aspectos que facilitan el diagnóstico rápido y el tratamiento adecuado, con el menor uso de recursos y con pautas que fijan la derivación oportuna hacia el especialista o hacia una institución de mayor complejidad. El desarrollo de importantes temas, como la patología obstructiva de la vía aérea superior, su estudio diagnóstico y sus formas recurrentes; bronquiolitis; las intercurrencias respiratorias en pacientes con condiciones clínicas especiales; y la supuración pleuropulmonar. La inclusión, en todos los capítulos, de casos clínicos con su evolución y desenlace, textos destacados con los principales conceptos y puntos claves para recordar. Una obra sólida y práctica, que transmite la experiencia de los profesionales de una institución del prestigio internacional del Hospital dePediatría Prof. Dr. Juan P. Garrahan, dedicada a todos los pediatras, dondequiera que trabajen al servicio de la salud de los niños.

Post-infectious bronchiolitis obliterans and mannose-binding lectin insufficiency in Argentinean children.

BACKGROUND AND OBJECTIVE: Post-infectious bronchiolitis obliterans (PIBO) is a severe disorder following acute lower pulmonary infection in young children, especially caused by adenovirus. Mannose-binding lectin (MBL) deficiency arising from polymorphisms in the coding and non-coding region on the MBL2 gene has been associated with more frequent and severe respiratory infections. Our aim was to evaluate the influence of MBL variants in the susceptibility and evolution of children with PIBO. METHODS: One hundred eleven children with PIBO diagnosis were studied. The coding A, B, D and X promoter variants of MBL2 gene were assessed by PCR-RFLP. B and D alleles were pooled as O. The combined genotypes A/A and YA/O were grouped as sufficient MBL (sMBL), and O/O and XA/O as insufficient MBL (iMBL) groups. To evaluate the frequency of MBL2 polymorphisms in the general population, we studied DNA samples from 127 healthy donors from the blood bank of the hospital (control group). RESULTS: iMBL variants were significantly more frequent in PIBO children compared with controls (21.6% vs 10.2%, P = 0.01). PIBO patients with iMBL required intensive care unit (P = 0.001) and mechanical assistance at the moment of viral injury (P = 0.001) more frequently than those with sMBL. CONCLUSIONS: Insufficiency of MBL was more common in PIBO children than in healthy controls. This genetic condition was significantly associated with more severe initial disease, illustrating the relevance of innate immune defence factors prior to the maturation of the adaptative immune system.

TLR4 genotype and environmental LPS mediate RSV bronchiolitis through Th2 polarization.

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.