NOTCH-induced rerouting of endosomal trafficking disables regulatory T cells in vasculitis
Ke Jin, … , Jorg J. Goronzy, Cornelia M. Weyand
Ke Jin, … , Jorg J. Goronzy, Cornelia M. Weyand
Published September 22, 2020
Citation Information: J Clin Invest. 2021;131(1):e136042. https://doi.org/10.1172/JCI136042.
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Research Article Autoimmunity Immunology

NOTCH-induced rerouting of endosomal trafficking disables regulatory T cells in vasculitis

Abstract

The aorta and the large conductive arteries are immunoprivileged tissues and are protected against inflammatory attack. A breakdown of immunoprivilege leads to autoimmune vasculitis, such as giant cell arteritis, in which CD8+ Treg cells fail to contain CD4+ T cells and macrophages, resulting in the formation of tissue-destructive granulomatous lesions. Here, we report that the molecular defect of malfunctioning CD8+ Treg cells lies in aberrant NOTCH4 signaling that deviates endosomal trafficking and minimizes exosome production. By transcriptionally controlling the profile of RAB GTPases, NOTCH4 signaling restricted vesicular secretion of the enzyme NADPH oxidase 2 (NOX2). Specifically, NOTCH4hiCD8+ Treg cells increased RAB5A and RAB11A expression and suppressed RAB7A, culminating in the accumulation of early and recycling endosomes and sequestering of NOX2 in an intracellular compartment. RAB7AloCD8+ Treg cells failed in the surface translocation and exosomal release of NOX2. NOTCH4hiRAB5AhiRAB7AloRAB11AhiCD8+ Treg cells left adaptive immunity unopposed, enabling a breakdown in tissue tolerance and aggressive vessel wall inflammation. Inhibiting NOTCH4 signaling corrected the defect and protected arteries from inflammatory insult. This study implicates NOTCH4-dependent transcriptional control of RAB proteins and intracellular vesicle trafficking in autoimmune disease and in vascular inflammation.

Authors

Ke Jin, Zhenke Wen, Bowen Wu, Hui Zhang, Jingtao Qiu, Yanan Wang, Kenneth J. Warrington, Gerald J. Berry, Jorg J. Goronzy, Cornelia M. Weyand

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Figure 6

NOTCH4 signaling regulates RAB5A and RAB11A transcription.

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NOTCH4 signaling regulates RAB5A and RAB11A transcription. (A) CD8+ Treg...
(A) CD8+ Tregs were induced from controls or GCA patients. RAB5A and RAB11A transcripts were determined by q-PCR. Mean ± SEM from 10 samples each. (B) Healthy CD8+ Tregs were transfected with empty vector or a NOTCH4 ICD overexpression plasmid, and RAB5A and RAB11A transcript levels were determined by q-PCR. Mean ± SEM from 6 control and 6 GCA samples. (C) GCA CD8+ Tregs were treated with DAPT or vehicle. RAB5A and RAB11A mRNA were quantified by q-PCR. Mean ± SEM from 10 samples. (D) GCA CD8+ Tregs were transfected with control or NOTCH4 siRNA. RAB5A and RAB11A transcript expression was determined by q-PCR. Mean ± SEM from 6 samples. (E) CD8+ Tregs were generated from GCA patients. ChIP assays targeting NOTCH4 or control IgG were performed on the promoter of RAB5A or a negative site. The signal was normalized to 10% of input. Mean ± SEM from 6 samples. (F) GCA CD8+ Tregs were treated with DAPT or vehicle. ChIP assays targeting NOTCH4 were performed on the promoter of RAB5A. The signal was normalized to 10% of input. Mean ± SEM from 6 samples. (G) In GCA CD8+ Tregs, ChIP assays targeting NOTCH4 or control IgG were performed on the promoter of RAB11A or a negative site. The signal was normalized to 10% of input. Mean ± SEM from 6 samples. (H) CD8+ Tregs were treated with DAPT or vehicle. The occupancy of NOTCH4 on the RAB11A promoter was determined by ChIP assay and normalized to 10% of input. Mean ± SEM from 6 samples. CD8+ Treg cells were induced ex vivo for all experiments. *P < 0.05; **P < 0.01; ***P < 0.001 by unpaired Mann-Whitney-Wilcoxon rank test (A) or paired Mann-Whitney-Wilcoxon rank test (B–D, F, and H).