Early Origins of Asthma. Role of Microbial Dysbiosis and Metabolic Dysfunction

Streptococcus colonization at 2 months of age was significantly associated with chronic wheeze at 5 years of age. Because colonization with Streptococcus was not associated with incidence of infections with streptococci or with S. pneumoniae-specific antibodies at 12 months, the authors concluded that the mechanism explaining the association between Streptococcus colonization and asthma is independent of innate and adaptive immune responses to Streptococcus. [...]in a birth cohort in Detroit, three stool composition states were described at 1 month of age that were associated with different risks for physician-diagnosed asthma at age 4 years (31). [...]the possibility of reverse causation cannot be excluded: dust microbial communities of homes of children who attend daycare are different from those of children not taken to daycare (33), suggesting that dust microbiota may indeed be at least in part determined by the microbiota residing in its inhabitants. [...]future research will need to address systematically whether the protective effects of some environmental exposures, such as living on a farm, on asthma are indeed mediated by alterations in richness and composition of the maternal and infant gut microbiome. A recent study of responses by T-helper cells to different stimuli showed that obese children with asthma (with ethnic minorities highly represented) do not have a predominance of the type-2 phenotype observed in nonobese patients with asthma (46), and this may explain their muffled clinical response to inhaled corticosteroids (47). [...]transcriptomic studies of CD41 T cells from obese children with asthma showed that the CDC42 pathway played a central role in Th1 polarization and in pulmonary function deficits observed in these children but not in normal-weight children with asthma (48).