La bronquiolitis es una de las patologías más frecuentemente diagnosticadas en niños. De facto ,creemos que a cualquier infeccion respiratoria, cuando el médico no lotienen muy claro, ante la duda la clasifica como "viriasis" , y le echa el muerto al VRS ( vvirus respiratorio sincitial).
Ahora, en éste artícuo que reproducimos íntegramente en ingés, se ofrece otra posibilidad. infeccione sprionica so alteración de proteínas que generan cuadros respiratorios de compicado tratamiento en los tiernos infantes.
Infant respiratory viral infectionOne of the more common viral infections of the respiratory tract in infants and young children occurs with respiratory syncytial virus (RSV). The virus infects the upper airways but can spread to the lower passages too, lowering the defences of the child to allow co-infection with bacteria. Although the majority of the cases result in mild infection, about 5% require hospitalisation.
Since the upper airways are attacked first, aspirate from the nasopharynx, the part of the throat that connects to the nose, is collected and subjected to immunofluorescence testing for RSV diagnosis. The aspirate is known to contain antibacterial proteins, pathogen recognition compounds and other proteins that are involved in the innate immune system.
However, scientists from Sweden recognised that there have been no compositional studies of the nasopharyngeal aspirate from patients with RSV, so they undertook a proteomics study. Mats Lindahl and colleagues from Linkoping University and the County Council of Ostergotland, Linkoping, analysed aspirate that had been collected from children aged 1-26 months who had been admitted to a local hospital.
They were particularly interested in a recently identified protein named short palate lung and nasal epithelium clone 1, which is fortunately referred to as SPLUNC1. This is known to bind to lipopolysaccharide, which is associated with pathogens, and has been proposed as a member of the innate immune system which fights off bacteria. Indeed, it is active against Pseudomonas aeruginosa and mycoplasma.
The researchers adopted classical proteomics techniques to study the aspirates. The proteins were separated by two-dimensional gel electrophoresis and visualised by silver staining. Each protein spot was cut out from the gel and digested with trypsin for mass spectrometric analysis and identification by database searching.
SPLUNC1 indicator of viral weakness
In all, 35 protein spots were identified in the aspirate with high confidence, corresponding to 15 specific proteins. They included known innate immunity proteins such as phospholipase A2 group X, several S100 proteins (A7, A7-like A8 and A9).
The significance of the proteins for the innate immunity system response to microbial infection was discussed in an attempt to better understand the defence mechanisms. However, the observation of SPLUNC1 in the aspirate was particularly interesting.
The aspirate was also examined by one-dimensional gel electrophoresis followed by immunoblotting for SPLUNC1. This revealed a truncated form of SPLUNC1 with a molecular mass of 15 kDa, as well as the full-length protein at 25 kDa. It was a genuine protein, rather than an artefact of the analytical process, and its identity was confirmed by mass spectrometry.
This is the first report of the truncated form of SPLUNC1 which existed in two isoforms with similar isoelectric points. It was found in 50% of the children tested but was absent from samples taken from healthy adults. The research team thought it unlikely that its presence related to age or is the result of a genetic factor. It is more likely produced by a protease that is activated during infection or inflammation.
The effect of the truncation on the functionality of SPLUNC1 is difficult to assess, say the researchers, but it probably reduces the resistance of individuals to Gram-negative bacteria and renders them more prone to severe respiratory tract infections.
The team also detected a correlation between the levels of full-length SPLUNC1 and the gender of the children. Boys testing positive for RSV had significantly lower amounts in their nasopharyngeal aspirate but the levels of the shorter form were not correspondingly higher, suggesting ongoing degradation of the protein.
So, boys with reduced levels of full-length SPLUNC1 might be at higher risk of RSV infection. This was supported by the clear correlation between the levels of the long and short forms of the protein in all girls and in RSV-negative boys.
Only a small number of children were tested and there were no parallel tests for bacterial or viral infections. A wider study is required to confirm the observations and to attempt to correlate the types and levels of SPLUNC1 to the clinical outcome and to other possible co-infections.
- Proteomics Clinical Applications 2011, 5, 513-522: "Innate immunity proteins and a new truncated form of SPLUNC1 in nasopharyngeal aspirates from infants with respiratory syncytial virus infection"