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2.
J Pathol ; 251(2): 160-174, 2020 06.
Article in English | MEDLINE | ID: mdl-32222043

ABSTRACT

The IκB kinase (IKK)-NF-κB signaling pathway plays a multifaceted role in inflammatory bowel disease (IBD): on the one hand, it protects from apoptosis; on the other, it activates transcription of numerous inflammatory cytokines and chemokines. Although several murine models of IBD rely on disruption of IKK-NF-κB signaling, these involve either knockouts of a single family member of NF-κB or of upstream kinases that are known to have additional, NF-κB-independent, functions. This has made the distinct contribution of NF-κB to homeostasis in intestinal epithelium cells difficult to assess. To examine the role of constitutive NF-κB activation in intestinal epithelial cells, we generated a mouse model with a tissue-specific knockout of the direct inhibitor of NF-κB, Nfkbia/IκBα. We demonstrate that constitutive activation of NF-κB in intestinal epithelial cells induces several hallmarks of IBD including increased apoptosis, mucosal inflammation in both the small intestine and the colon, crypt hyperplasia, and depletion of Paneth cells, concomitant with aberrant Wnt signaling. To determine which NF-κB-driven phenotypes are cell-intrinsic, and which are extrinsic and thus require the immune compartment, we established a long-term organoid culture. Constitutive NF-κB promoted stem-cell proliferation, mis-localization of Paneth cells, and sensitization of intestinal epithelial cells to apoptosis in a cell-intrinsic manner. Increased number of stem cells was accompanied by a net increase in Wnt activity in organoids. Because aberrant Wnt signaling is associated with increased risk of cancer in IBD patients and because NFKBIA has recently emerged as a risk locus for IBD, our findings have critical implications for the clinic. In a context of constitutive NF-κB, our findings imply that general anti-inflammatory or immunosuppressive therapies should be supplemented with direct targeting of NF-κB within the epithelial compartment in order to attenuate apoptosis, inflammation, and hyperproliferation. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.


Subject(s)
Apoptosis , Inflammatory Bowel Diseases/metabolism , Intestine, Small/metabolism , NF-KappaB Inhibitor alpha/deficiency , Paneth Cells/metabolism , Stem Cells/metabolism , Animals , Cells, Cultured , Cytokines/metabolism , Inflammatory Bowel Diseases/genetics , Inflammatory Bowel Diseases/pathology , Intestine, Small/pathology , Mice, Knockout , NF-KappaB Inhibitor alpha/genetics , Organoids/metabolism , Organoids/pathology , Paneth Cells/pathology , Stem Cells/pathology , Transcription Factor RelA/metabolism , Wnt Signaling Pathway
4.
J Immunol ; 199(3): 920-930, 2017 08 01.
Article in English | MEDLINE | ID: mdl-28652399

ABSTRACT

Foxp3-expressing regulatory T cells (Tregs) are essential regulators of immune homeostasis and, thus, are prime targets for therapeutic interventions of diseases such as cancer and autoimmunity. c-REL and IκBNS are important regulators of Foxp3 induction in Treg precursors upon γ-chain cytokine stimulation. In c-REL/IκBNS double-deficient mice, Treg numbers were dramatically reduced, indicating that together, c-REL and IκBNS are pivotal for Treg development. However, despite the highly reduced Treg compartment, double-deficient mice did not develop autoimmunity even when aged to more than 1 y, suggesting that c-REL and IκBNS are required for T cell effector function as well. Analyzing Treg development in more detail, we identified a CD122+ subset within the CD25-Foxp3- precursor population, which gave rise to classical CD25+Foxp3- Treg precursors. Importantly, c-REL, but not IκBNS, controlled the generation of classical CD25+Foxp3- precursors via direct binding to the Cd25 locus. Thus, we propose that CD4+GITR+CD122+CD25-Foxp3- cells represent a Treg pre-precursor population, whose transition into Treg precursors is mediated via c-REL.


Subject(s)
Cell Differentiation , Forkhead Transcription Factors/metabolism , NF-KappaB Inhibitor alpha/metabolism , Proto-Oncogene Proteins c-rel/metabolism , T-Lymphocytes, Regulatory/physiology , Animals , Autoimmunity , Forkhead Transcription Factors/genetics , Gene Expression Regulation , Interleukin-2 Receptor alpha Subunit/immunology , Interleukin-2 Receptor alpha Subunit/metabolism , Interleukin-2 Receptor beta Subunit/genetics , Interleukin-2 Receptor beta Subunit/immunology , Mice , NF-KappaB Inhibitor alpha/deficiency , NF-KappaB Inhibitor alpha/genetics , Protein Binding , Proto-Oncogene Proteins c-rel/deficiency , Proto-Oncogene Proteins c-rel/genetics , T-Lymphocyte Subsets/immunology , T-Lymphocytes, Regulatory/immunology
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