It's good to have a house in the village
Childhood in rural dust was associated with a reduced risk of asthma
It's about the microbiota that lives on the floor of farmhouses
Maxim Abdulaev, "The Attic"
Scientists have found out which microbes live in the dust of farm and suburban houses in Finland, and, in addition, they found that the more microbiota in house dust resembles rural dust in composition, the lower the risk of developing asthma in a child.
According to the authors of a paper published in Nature Medicine (Kirjavainen et al., Farm-like indoor microbiota in non-farm homes protects children from asthma development), the incidence of asthma also increases with increasing urbanization. There are also studies that show that children who grew up in rural areas have a lower risk of becoming asthmatic than citizens. Perhaps the reason for this is a specific microbiota peculiar to farms. Scientists from Finland conducted a study of rural and urban microbiota to find out if this is the case.
They collected dust samples from homes whose residents participated in the LUKAS1 and LUKAS2 cohort studies aimed at identifying the causes of asthma. Dust was taken for analysis in village houses, where a total of 197 children aged 2 months lived, as well as in suburban townhouses, which cannot be attributed to rural ones — only 182 two-month-old children lived there. Six years later, scientists looked at which of almost 400 children had asthma, and compared this with data on the microbiota of their homes.
Scientists compared the metagenomes of dust samples and found differences between "rural" and "urban" microbial communities. In the microbiota data in the village dust samples, they identified a characteristic pattern, which they called FaRMI. It is characterized by the predominance of microbes from the detachments Bacteroidales, Clostridiales, Lactobacillales and also archaea of the genus Methanobrevibacter, which usually live in the cow's rumen (the largest part of the animal's stomach). Streptococci and staphylococci predominated in the dust of city houses. There was a difference between the microbiota, but in some suburban homes, the microbiota close to FaRMI still prevailed.
Then the scientists compared the resulting "microbial map" with medical data and found out that the more the microbiome from the dust was similar to the rural one, the less the child living in its environment was at risk of becoming asthmatic. On average, rural children developed asthma about half as often as children from the suburbs.
The scientists applied their data on the FaRMI pattern to the data of a similar study of house dust conducted by their colleagues from Germany and Switzerland. It turned out that there, too, the risk of developing asthma was inversely correlated with the degree of proximity of the household microbiome to FaRMI — the closer, the less risk.
At the final stage, the researchers studied the blood of children from the LUKAS1 and LUKAS2 studies. It turned out that white blood cells in children whose homes were dominated by the "farmer" microbiota, emit less pro-inflammatory interleukins in contact with substances from the bacterial cell wall. Apparently, their body is calmer about the invasions of microbes and responds with less severe inflammation than the body of citizens. Perhaps this is somehow connected with a reduced risk of asthma.
The scientists noted that the microbes abounding in FaRMI are characteristic mainly of cattle, whereas microbes from urban dust are more characteristic of humans. Such microorganisms more easily penetrate into our body and settle in it. Perhaps this also affects the tendency to asthma.
Anyway, the study revealed an inverse correlation between the "village" microbiota in dust and the development of asthma in children, but it is impossible to say with certainty why the microbial composition of dust is associated with asthma.
Portal "Eternal youth" http://vechnayamolodost.ru