The world has seen an explosive rise in asthma over the past three decades. Such a rise in prevalence cannot be only a result of genetic variation and leads us to believe that environmental factors play an important role in this change. There are several possible explanations for this including what we call the “hygiene hypothesis”, or the idea that we now live in an environment that is too clean and we are no longer exposed to the bacteria and germs that earlier generations were exposed to. Another possible explanation is as the world changes and becomes more modern, these environmental changes are affecting our microbiome and the “normal” microbiome is shifting to a new normal.
To better understand why some children are at high risk for becoming asthmatic, scientists in Canada studied the microbiome of 319 children in the Canadian Healthy Infant Longitudinal Development (CHILD) Study. They sequenced fecal samples from the children and found that 4 groups of bacteria that were decreased in prevalence compared to the children without asthma. Bacteria from the genus Lachnospira, Veillonella, Faecalibacterium, and Rothia (FLVR) were at lower levels after 3 months for the children at high risk for asthma however over time, this leveled out and was similar to the children not at risk for asthma.
The study did not identify what exactly caused these differences as there could be several reasons for these differences including antibiotic use, the method in which the child was delivered either vaginally or by C-section, and if the child was breastfed or not. It is also possible and maybe even likely that some of the mother’s behaviors during the pregnancy such as diet could play an important role in the early development of the child’s microbiome.
The next obvious question is what can we do about this? Does this mean that we can now treat children that are deficient of these bacteria and they won’t get asthma? While it sounds simple, we don’t yet know too much about these bacteria and it will be important to better understand the impact his would have on the rest of development. Promising results from this study did show that when mice with low levels of FLVR were treated with probiotic samples of the bacteria, it protected them from getting asthma.
This is a very exciting study that may lead to new diagnostics for asthma and with more research and understanding, allow us to prevent the disease from developing.