Diet-mediated constitutive induction of novel IL4+ ILC2 cells maintains intestinal homeostasis in mice

Group 2 innate lymphoid cells (ILC2s) expressing IL-5 and IL-13 are localized at various mucosal tissues and play critical roles in the induction of type 2 inflammation, response to helminth infection, and tissue repair. Here we reveal a unique ILC2 subset in the mouse intestine that constitutively expresses IL-4 together with GATA3, ST2, KLRG1, IL-17RB, and IL-5. In this subset, IL-4 expression is regulated by mechanisms similar to but distinct from those observed in T cells and is partly affected by IL-25 signaling. Although the absence of the microbiota had marginal effects, feeding mice with a vitamin B1-deficient diet compromised the number of intestinal IL-4+ ILC2s. The decrease in the number of IL-4+ ILC2s caused by the vitamin B1 deficiency was accompanied by a reduction in IL-25-producing tuft cells. Our findings reveal that dietary vitamin B1 plays a critical role in maintaining interaction between tuft cells and IL-4+ ILC2s, a previously uncharacterized immune cell population..., ILC2 cells were isolated from colon and lung of GF mice and SPF mice. Colonic epithelial cells were isolated from mice fed with control diet or vitamin B1-free diet. Total RNA was extracted using TRIzol (Invitrogen) and an RNA library was prepared using a NEBNext Ultra RNA Library Prep Kit for Illumina (New England Biolabs) according to the manufacturer’s instructions. After assessing the library quality, sequencing was conducted on a HiSeq 1500 system (Illumina) using single-ended 50-bp reads. The sequenced reads were mapped to the mouse reference genome (mm9, NCBI build 37) and normalized to fragments per kilobase per million reads (FPKM) values using the Tophat and Cufflinks software pipeline. ,

表达白细胞介素-5（IL-5）与白细胞介素-13（IL-13）的2型先天淋巴细胞（Group 2 innate lymphoid cells, ILC2s）广泛分布于多种黏膜组织，在2型炎症诱导、蠕虫感染应答及组织修复中发挥关键调控作用。本研究首次鉴定出小鼠肠道内一类独特的ILC2亚群，该亚群可组成性表达白细胞介素-4（IL-4），同时共表达GATA3、ST2、KLRG1、IL-17RB与IL-5。在该亚群中，IL-4的表达调控机制与T细胞既有相似性又存在特异性，且部分受IL-25信号通路调控。尽管微生物群缺失仅产生微弱影响，但喂食维生素B1缺乏饲料的小鼠，其肠道IL-4+ ILC2的数量显著降低。由维生素B1缺乏引发的IL-4+ ILC2数量减少，同时伴随产IL-25的簇细胞（tuft cells）数量下降。本研究结果显示，膳食维生素B1在维持簇细胞与IL-4+ ILC2（一类此前未被充分表征的免疫细胞群）的相互作用中发挥关键作用……研究人员从无菌（germ-free, GF）小鼠与无特定病原体（specific pathogen free, SPF）小鼠的结肠和肺组织中分离ILC2细胞；从喂食对照饲料或无维生素B1饲料的小鼠体内分离结肠上皮细胞。采用TRIzol（Invitrogen公司）提取总RNA，并严格按照制造商说明书，使用NEBNext Ultra RNA Library Prep Kit for Illumina（New England Biolabs公司）构建RNA文库。完成文库质量评估后，采用HiSeq 1500测序系统（Illumina公司）进行单端50bp读长测序。将测序得到的读段（reads）比对至小鼠参考基因组（mm9，NCBI Build 37），并通过Tophat与Cufflinks软件流程将其标准化为每百万读段每千碱基片段数（FPKM）值。