RNAseq analysis for tails, and ears from Ikbkb mut/mut and Ikbkb wt/wt mice

Loss-of-function mutations have provided crucial insights into the immunoregulatory actions of Foxp3+ regulatory T cells (Tregs). By contrast, we know very little about the consequences of defects that amplify aspects of Treg function or differentiation. We report that mice heterozygous for an Ikbkb gain-of-function (GoF) mutation develop psoriasis. Doubling the gene dose (IkbkbGoF/GoF) results in dactylitis, spondylitis, and characteristic nail changes, which are features of psoriatic arthritis. IkbkbGoF mice exhibit a selective expansion of Foxp3+ CD25+ Tregs of which a subset express IL-17. These modified Tregs were enriched at the inflamed tissues and spleen, and their transfer was sufficient to induce disease without conventional T cells. Single-cell transcriptional and phenotyping analyses of isolated Tregs revealed expansion of non-lymphoid tissue (tissue-resident) Tregs expressing Th17-related genes, Helios, tissue-resident markers including CD103 and CD69, and a prominent NF-kB transcriptome. Thus, IKK2 regulates tissue-resident Treg differentiation, and overactivity drives dose-dependent skin and systemic inflammation. By comparing transcriptome of tissues from Ikbkbmut/mut and Ikbkb+/+ mice, it revealed that tail and ear tissues from Ikbkbmut/mut mice with inflammation had the upregulation of psoriasis markers. By contrast, atopic dermatitis were lowly expressed and/or not significantly differentially expressed.功能丧失型突变为解析Foxp3阳性调节性T细胞（Foxp3+ regulatory T cells，Tregs）的免疫调节作用提供了关键研究见解。与之相对，学界对于能够增强调节性T细胞功能或分化过程的缺陷所产生的影响却知之甚少。本研究报道，携带Ikbkb功能获得型（gain-of-function，GoF）突变的杂合子小鼠会出现银屑病（psoriasis）。将该基因剂量加倍（即IkbkbGoF/GoF纯合突变）则会引发指（趾）炎、脊柱炎以及特征性甲病变，这些均为银屑病关节炎（psoriatic arthritis）的典型表现。Ikbkb功能获得型突变小鼠会出现Foxp3阳性CD25阳性调节性T细胞的选择性扩增，其中部分亚群可表达白介素17（IL-17）。此类表型发生改变的调节性T细胞会在炎症组织与脾脏中富集，且仅通过过继转移这些细胞即可在缺乏常规T细胞的小鼠中诱发疾病。对分离得到的调节性T细胞开展单细胞转录组与表型分析后发现，表达Th17相关基因、Helios蛋白、包括CD103与CD69在内的组织驻留标志物，且具有显著核因子κB（NF-κB）转录组特征的非淋巴组织驻留型调节性T细胞发生了扩增。由此可见，IKK2可调控组织驻留型调节性T细胞的分化，其过度活化会以剂量依赖的方式诱发皮肤炎症与全身性炎症。通过对比Ikbkb纯合突变型（Ikbkbmut/mut）与野生型（Ikbkb+/+）小鼠的组织转录组，研究发现存在炎症的Ikbkb纯合突变型小鼠的尾组织与耳组织中银屑病标志物呈现上调表达。与之相对，特应性皮炎相关基因的表达水平较低，且未出现显著的差异表达。