Thursday, July 2, 2015
The mechanism or mechanisms driving atopic asthma initiation: The infant respiratory microbiome moves to center stage
It is acknowledged that key events that determine risk for the development of allergic disease frequently occur years before manifestation of symptoms. Recent culture-based studies, in combination with population-wide bacterial metagenomic data, suggest that parallel bacterial interactions may contribute to disease development. Holt reviews these and related issues of immune competence in infancy (J Allergy Clin Immunol 2015; 136(1): 15-22).
A number of factors specific to infancy can contribute to disease development. Prospective tracking of postnatal IgE titres in serum samples collected over the first five years of life strongly suggests IgE antibody production against aeroallergens rarely begins before the age of six months. Airway mucosal dendritic cells (AMDC) transmit aeroallergen-specific signals from the airway mucosal surface to the central immune system and program the balance between the Th2 and T regulatory cell components of the immunological memory that results. The immaturity of this network in infants is likely a risk factor for early respiratory infection, itself a risk factor for early atopic asthma.