Data_Sheet_1_Intestinal Microbiota and Immune Modulation in Zebrafish by Fucoidan From Okinawa Mozuku (Cladosiphon okamuranus).PDF

Fucoidan represents fucose-rich sulfated polysaccharides derived from brown seaweeds, which exerts various biological activities applicable for functional foods and therapeutic agents. The objective of the present study was to investigate in vivo effects of fucoidan extracted from Okinawa mozuku (Cladosiphon okamuranus), common edible seaweed in Japan, on immune responses and microbiota composition in zebrafish. We treated larvae and adult zebrafish with Okinawa mozuku (OM) fucoidan by immersion (100 and 500 μg/mL, 3 days) and by feeding (3 weeks), respectively. The effect of OM fucoidan on immune responses in zebrafish larvae was evaluated by live imaging of neutrophils and macrophages as well as quantitative polymerase chain reaction of pro- and anti-inflammatory cytokine genes. Whole microbiota of zebrafish larvae and intestinal microbiota of adult zebrafish treated with OM fucoidan were analyzed by Illumina MiSeq pair-end sequencing of the V3–V4 region of 16S rRNA genes. Fucoidan treatment only slightly affected the composition of the larvae microbiota and the number of neutrophils and macrophages, while pro- and anti-inflammatory cytokine gene expression levels were upregulated in the larvae treated with 500 μg/mL OM fucoidan. In contrast, feeding of OM fucoidan clearly altered the intestinal microbiota composition of adult zebrafish, which was characterized by the emergence and predominance of multiple bacterial operational taxonomic units (OTUs) affiliated with Rhizobiaceae and Comamonadaceae at the expense of E. coli-related Enterobacteriaceae, the dominant OTUs throughout the studied samples. These changes were accompanied by decreased expression levels of pro-inflammatory cytokine il1b in the intestines of the adult zebrafish. Our current study provides the first insights into in vivo modulatory effects of fucoidan on microbiota and immune responses of unchallenged zebrafish, which underscores the potential of fucoidan to play a modulatory role in the diet–microbiota–host interplay.

岩藻聚糖（fucoidan）是一类源自褐藻的富含岩藻糖的硫酸化多糖，具备多种可应用于功能食品与治疗制剂的生物学活性。本研究旨在探究从日本常见食用海藻冲绳mozuku（冈村枝管藻，Cladosiphon okamuranus）中提取的岩藻聚糖对斑马鱼免疫应答与菌群组成的体内效应。研究分别采用浸泡法（浓度100、500 μg/mL，处理3天）与投喂法（连续投喂3周），对斑马鱼幼体及成体进行冲绳mozuku岩藻聚糖（OM fucoidan）干预。通过中性粒细胞与巨噬细胞的活体成像，以及促炎、抗炎细胞因子基因的定量聚合酶链反应（quantitative polymerase chain reaction），评估OM岩藻聚糖对斑马鱼幼体免疫应答的影响。采用Illumina MiSeq平台对16S rRNA基因V3–V4可变区进行双端测序，分析经OM岩藻聚糖干预的斑马鱼幼体全菌群与成体肠道菌群结构。岩藻聚糖干预对斑马鱼幼体的菌群组成及中性粒细胞、巨噬细胞数量仅产生轻微影响，但经500 μg/mL OM岩藻聚糖干预的幼体中，促炎与抗炎细胞因子基因的表达水平均出现上调。与之相反，OM岩藻聚糖投喂干预可显著改变斑马鱼成体的肠道菌群结构，表现为多个隶属于根瘤菌科（Rhizobiaceae）与丛毛单胞菌科（Comamonadaceae）的细菌操作分类单元（operational taxonomic units, OTUs）得以出现并占据优势，同时以本研究样本中原先占主导的大肠杆菌相关肠杆菌科（Enterobacteriaceae）的OTUs为代价。上述菌群结构变化伴随斑马鱼成体肠道内促炎细胞因子il1b的表达水平下调。本研究首次揭示了岩藻聚糖对未受免疫挑战的斑马鱼菌群与免疫应答的体内调控效应，凸显了岩藻聚糖在“饮食-菌群-宿主”互作中发挥调控作用的潜力。