Inflammatory bowel diseases (IBDs) result in diarrhea and abdominal pain with further potential complications such as tissue fibrosis and stenosis. Animal models help in understanding the immunopathogenesis of IBDs and in the design of novel therapeutic concepts. Here we present an updated version of a protocol we published in 2007 for key models of acute and chronic forms of colitis induced by 2,4,6-trinitro-benzene sulfonic acid (TNBS), oxazolone and dextran sulfate sodium (DSS). This protocol update describes an adaptation of the existing protocol that modifies the technique. This protocol has been used to generate improved mouse models that better reflect the nature of IBDs in humans. In TNBS and oxazolone colitis models, topical administration of hapten reagents results in T-cell-mediated immunity against haptenized proteins and luminal antigens. By contrast, to generate DSS colitis models, mice orally receive DSS, causing death of epithelial cells, compromising barrier function and causing subsequent inflammation. The analysis of the acute colitis models can be performed within 1-2 weeks, whereas that of the chronic models may take 2-4 months. The strengths of the acute models are that they are based on the analysis of short-lasting barrier alterations, innate immune effects and flares. The advantages of the chronic models are that they may offer better insight into adaptive immunity and complications such as neoplasia and tissue fibrosis. The protocol requires basic skills in laboratory animal research.

The molecular checkpoints that drive inflammatory bowel diseases are incompletely understood. Here we found more T cells expressing the transcription factor PU.1 and interleukin 9 (IL-9) in patients with ulcerative colitis. In an animal model, citrine reporter mice had more IL-9-expressing mucosal T cells in experimental oxazolone-induced colitis. IL-9 deficiency suppressed acute and chronic colitis. Mice with PU.1 deficiency in T cells were protected from colitis, whereas treatment with antibody to IL-9 suppressed colitis. Functionally, IL-9 impaired intestinal barrier function and prevented mucosal wound healing in vivo. Thus, our findings suggest that the TH9 subset of helper T cells serves an important role in driving ulcerative colitis by regulating intestinal epithelial cells and that TH9 cells represent a likely target for the treatment of chronic intestinal inflammation.

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Summary Obesity and type-2 diabetes are associated with tissue-inflammation and metabolic defects in fat depots. Foxp3+regulatory T(Treg) cells mediate T-cell tolerance, thereby controlling tissue inflammation. However, the molecular underpinnings how environmental stimuli interlink T-cell tolerance with adipose tissue function remain largely unknown. Here, we report that cold exposure or beta3-adrenergic receptor (ADRB3) stimulation induces T-cell tolerance in vitro and in murine and humanized models. Tolerance induction was verified by CD4+T-cell-proteomes revealing higher protein expression of Foxp3 regulatory networks. Specifically, Ragulator-interacting protein C17orf59, which limits mTORC1 activity, was upregulated by either ADRB3-stimulation or cold-exposure, and therefore might enhance Treg induction. By loss and gain-of-function studies, including Treg depletion and transfers in vivo, we demonstrated that a T-cell-specific Stat6/Pten axis links cold-exposure or ADRB3 stimulation with Foxp3+Treg induction and adipose tissue function. Our findings open new avenues in understanding tissue-specific T-cell tolerance and the design of precision concepts toward personalized immune-metabolic health.

Molecular checkpoints that trigger the onset of islet autoimmunity or progression to human type 1 diabetes (T1D) are incompletely understood. Using T cells from children at an early stage of islet autoimmunity without clinical T1D, we find that a microRNA181a (miRNA181a)–mediated increase in signal strength of stimulation and costimulation links nuclear factor of activated T cells 5 (NFAT5) with impaired tolerance induction and autoimmune activation. We show that enhancing miRNA181a activity increases NFAT5 expression while inhibiting FOXP3+ regulatory T cell (Treg) induction in vitro. Accordingly, Treg induction is improved using T cells from NFAT5 knockout (NFAT5ko) animals, whereas altering miRNA181a activity does not affect Treg induction in NFAT5ko T cells. Moreover, high costimulatory signals result in phosphoinositide 3-kinase (PI3K)–mediated NFAT5, which interferes with FoxP3+ Treg induction. Blocking miRNA181a or NFAT5 increases Treg induction in murine and humanized models and reduces murine islet autoimmunity in vivo. These findings suggest targeting miRNA181a and/or NFAT5 signaling for the development of innovative personalized medicines to limit islet autoimmunity.