Daily practices put humans in close contact with the surrounding environment, and differences in these practices have an impact on human physiology, development, and health. There is mounting evidence that the microbiome represents an interface that mediates interactions between the human body and the environment. In particular, the skin microbiome serves as the primary interface with the external environment and aids in host immune function by contributing as the first line of defense against pathogens. Despite these important connections, we have only a basic understanding of how the skin microbiome is first established, or which environmental factors contribute to its development. To this end, this study compared the skin bacterial communities of infants (n = 47) living in four populations in Mexico and the United States that span the socioeconomic gradient, where we predicted that variation in physical and social environments would shape the infant skin microbiome. Results of 16S rRNA bacterial gene sequencing on 119 samples (armpit, hand, and forehead) showed that infant skin bacterial diversity and composition are shaped by population-level factors, including those related to socioeconomic status and household composition, and vary by skin site and infant age. Differences in infant-environment interactions, including with other people, appear to vary across the populations, likely influencing infant microbial exposures and, in turn, the composition of infant skin bacterial communities. These findings suggest that variation in microbial exposures stemming from the local environment in infancy can impact the establishment of the skin microbiome across body sites, with implications for developmental and health outcomes.

中文翻译：

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墨西哥和美国不同人口的婴儿皮肤细菌群落因皮肤部位和婴儿年龄而异

日常实践使人类与周围环境紧密接触，这些实践的差异会影响人类的生理，发育和健康。越来越多的证据表明，微生物组代表了介导人体与环境之间相互作用的界面。特别地，皮肤微生物组充当与外部环境的主要界面，并通过作为抵抗病原体的第一道防线而有助于宿主的免疫功能。尽管有这些重要的联系，但我们对皮肤微生物组的最初建立方法或哪些环境因素对其发展有基本的了解。为此，本研究比较了婴儿的皮肤细菌群落（n= 47）居住在墨西哥和美国的四个人口中，这些人口跨越了社会经济梯度，我们预测物理和社会环境的变化将影响婴儿皮肤微生物组。对119个样品（腋下，手和前额）进行16S rRNA细菌基因测序的结果表明，婴儿皮肤细菌的多样性和组成受群体水平因素的影响，包括与社会经济状况和家庭组成有关的因素，并且随皮肤部位和婴儿年龄。婴儿与环境之间的相互作用（包括与其他人的相互作用）在人群中似乎有所不同，可能会影响婴儿的微生物暴露，进而影响婴儿皮肤细菌群落的组成。