Gut microbiota diversity and composition in children with autism spectrum disorder

Background: Autism Spectrum Disorder (ASD) is a prevalent neurodevelopmental disorder impairing social and communication skills. Gut microbiota has become key in understanding ASD pathophysiology. However, the relationship between the ASD symptoms and alternation of gut microbiota still remains unknow.Methods: Here, fecal samples from kids (divided in to three groups: healthy, severe ASD and mild ASD) at a hospital were collected, and then the diversity and composition of gut microbiota were detected by high-throughput sequencing.Results: Totally, 2021 ASVs were obtained from 46 fecal samples, with highest in the healthy group. Alpha diversity in bacteria differed between severe and mild ASD. Microbiota health and dysbiosis indices varied with ASD severity. Beta diversity indicated that severe ASD differed from others, and mild ASD was closer to healthy in community structure. At the phylum level, Firmicutes was the dominant bacteria but abundances differed in different groups, and Ascomycota increased in severe ASD fungi. At the genus level, groups had distinct dominants, and mild ASD microbiota resembled that of healthy kids. Function prediction revealed differences in bacteria and fungi, with severe ASD having higher amino acid metabolism, lower cofactor/vitamin metabolism, and more Undefined Saprotrophs.Conclusion: This study revealed gut microbiota differences between ASD kids (varying symptoms) and healthy ones, showing milder ASD closer in microbiota aspects. It offers insights for exploring ASD pathogenesis and devising interventions.

背景：自闭症谱系障碍（Autism Spectrum Disorder，ASD）是一种高发的神经发育障碍，会损害社交与沟通能力。肠道菌群现已成为解析ASD病理生理学机制的关键靶点。然而，ASD症状与肠道菌群失调之间的关联仍未明确。
方法：本研究收集了某医院的儿童粪便样本，将其分为健康对照组、重度ASD组与轻度ASD组三组，随后通过高通量测序技术检测肠道菌群的多样性与组成。
结果：本研究从46份粪便样本中共获得2021个扩增子序列变异体（ASVs），其中健康对照组的ASV数量最高。细菌的α多样性在重度与轻度ASD组间存在显著差异；菌群健康指数与失调指数随ASD严重程度发生变化。β多样性分析显示，重度ASD组的菌群群落结构与其余两组存在明显差异，而轻度ASD组与健康对照组的群落结构更为接近。在门水平上，厚壁菌门（Firmicutes）为优势细菌门，但不同组间的丰度存在显著差异；重度ASD组的子囊菌门（Ascomycota）丰度显著升高。在属水平上，各组的优势菌群存在明显区分，轻度ASD组的菌群组成与健康儿童更为相似。功能预测分析表明，细菌与真菌的功能通路存在显著差异：重度ASD组的氨基酸代谢通路丰度更高，辅因子/维生素代谢通路丰度更低，且存在更多的未定义腐生营养型（Undefined Saprotrophs）菌群。
结论：本研究揭示了不同症状严重程度的ASD患儿与健康儿童的肠道菌群差异，表明轻度ASD患儿的肠道菌群特征更贴近健康儿童。该研究为探索ASD的发病机制及制定干预策略提供了重要的理论参考与研究思路。