Supplementary Material for: Cheek Microbial Communities Vary in Young Children with Atopic Dermatitis in China

<b><i>Background:</i></b> Atopic dermatitis (AD) is a chronic, recurrent skin condition with recently increased incidence in younger children. AD development has been correlated with the skin microbiome, and <i>Staphylococcus aureus</i> enrichment causes significant increases in skin lesions. <b><i>Objective:</i></b> Our objectives were to compare the microbial diversity of the cheek skin of children with or without AD aged 0–1 years in China, and to determine whether 4 types of skin-isolated bacteria could inhibit <i>S. aureus</i> in vitro. <b><i>Methods:</i></b> The skin microbial samples of cheek skin of children were sequenced by 16S rRNA V1-V2 region. Four skin isolated bacterial fermentation supernatants were tested for effects on <i>S. aureus</i> growth, membrane formation, and induction of cytokine secretion from HaCaT cells. <b><i>Results:</i></b> Bacterial diversity decreased significantly in skin with severe AD compared to healthy skin (<i>p</i> &lt; 0.01). Seven phyla had content &gt;1%, 4 of which differed in AD (<i>p</i> &lt; 0.05). 38 genera had content &gt;1%, 15 differed (<i>p</i> &lt; 0.05). Differences in 8 species were observed (<i>p</i> &lt; 0.05). In vitro antibacterial and cellular experiments showed that <i>S. aureus</i> growth, biofilm formation, and induction of interleukin (IL)-1α and IL-6 secretion from HaCaT cells were significantly inhibited by <i>Klebsiella oxytoca</i>, <i>Kocuria rhizophila</i>, and <i>Staphylococcus epidermidis</i> culture supernatants (<i>p</i> &lt; 0.05). <b><i>Conclusion:</i></b> Skin microbiome changes in children varied with age and with AD. There were complex interactions between skin isolated bacteria and <i>S. aureus</i> which could inhibit <i>S. aureus</i> growth and biofilm formation in vitro, suggesting that these microorganisms could be used in AD treatment.

**背景**：特应性皮炎（Atopic dermatitis, AD）是一种慢性复发性皮肤疾病，近年来低龄儿童的发病率呈上升趋势。AD的发生与皮肤微生物组密切相关，而金黄色葡萄球菌（Staphylococcus aureus）的富集会显著加重皮肤皮损。**目的**：本研究旨在比较中国0至1岁特应性皮炎患儿与健康儿童脸颊皮肤的微生物多样性，并探究4株皮肤分离菌能否在体外抑制金黄色葡萄球菌。**方法**：采集儿童脸颊皮肤的微生物样本，对16S rRNA V1-V2可变区进行测序。针对4株皮肤分离菌的发酵上清液，检测其对金黄色葡萄球菌生长、生物膜形成的影响，以及对HaCaT细胞细胞因子分泌的诱导作用。**结果**：与健康皮肤相比，重度AD患儿的皮肤微生物多样性显著降低（p < 0.01）。共检出7个相对丰度>1%的菌门，其中4个在AD组与健康组间存在显著差异（p < 0.05）；检出38个相对丰度>1%的菌属，其中15个存在显著差异（p < 0.05）；另有8个菌种存在显著差异（p < 0.05）。体外抗菌及细胞实验结果显示，产酸克雷伯菌（Klebsiella oxytoca）、嗜根库特菌（Kocuria rhizophila）及表皮葡萄球菌（Staphylococcus epidermidis）的培养上清可显著抑制金黄色葡萄球菌的生长、生物膜形成，并抑制HaCaT细胞分泌白细胞介素（interleukin, IL）-1α和IL-6（p < 0.05）。**结论**：儿童皮肤微生物组的变化随年龄及AD状态发生改变。皮肤分离菌与金黄色葡萄球菌之间存在复杂的相互作用，其中部分菌株可在体外抑制金黄色葡萄球菌的生长与生物膜形成，提示这些微生物有望用于AD的治疗。