Tregs restrain dendritic cell autophagy to ameliorate autoimmunity
Themis Alissafi, … , Ken Cadwell, Panayotis Verginis
Themis Alissafi, … , Ken Cadwell, Panayotis Verginis
Published June 30, 2017; First published June 5, 2017
Citation Information: J Clin Invest. 2017;127(7):2789-2804. https://doi.org/10.1172/JCI92079.
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Categories: Research Article Autoimmunity Immunology

Tregs restrain dendritic cell autophagy to ameliorate autoimmunity

Abstract

Design of efficacious Treg-based therapies and establishment of clinical tolerance in autoimmune diseases have proven to be challenging. The clinical implementation of Treg immunotherapy has been hampered by various impediments related to the stability and isolation procedures of Tregs as well as the specific in vivo targets of Treg modalities. Herein, we have demonstrated that Foxp3+ Tregs potently suppress autoimmune responses in vivo through inhibition of the autophagic machinery in DCs in a cytotoxic T-lymphocyte–associated protein 4–dependent (CTLA4-dependent) manner. Autophagy-deficient DCs exhibited reduced immunogenic potential and failed to prime autoantigen-specific CD4+ T cells to mediate autoimmunity. Mechanistically, CTLA4 binding promoted activation of the PI3K/Akt/mTOR axis and FoxO1 nuclear exclusion in DCs, leading to decreased transcription of the autophagy component microtubule-associated protein 1 light chain 3β (Lc3b). Human DCs treated with CTLA4-Ig, a fusion protein composed of the Fc region of IgG1 and the extracellular domain of CTLA4 (also known as abatacept, marketed as Orencia), demonstrated reduced levels of autophagosome formation, while DCs from CTLA4-Ig–treated rheumatoid arthritis patients displayed diminished LC3B transcripts. Collectively, our data identify the canonical autophagy pathway in DCs as a molecular target of Foxp3+ Treg–mediated suppression that leads to amelioration of autoimmune responses. These findings may pave the way for the development of therapeutic protocols that exploit Tregs for the treatment of autoimmunity as well as diseases in which disturbed tolerance is a common denominator.

Authors

Themis Alissafi, Aggelos Banos, Louis Boon, Tim Sparwasser, Alessandra Ghigo, Kajsa Wing, Dimitrios Vassilopoulos, Dimitrios Boumpas, Triantafyllos Chavakis, Ken Cadwell, Panayotis Verginis

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Figure 7

CTLA4-Ig diminishes autophagy pathway in human DCs and promotes FoxO1 nuclear exclusion.

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CTLA4-Ig diminishes autophagy pathway in human DCs and promotes FoxO1 nu...
(A) CD11c+CD14–HLADR+ DCs were isolated from the periphery of anti–TNF-α–treated (n = 5) or CTLA4-Ig–treated (n = 7) RA patients (DAS > 3). Relative mRNA expression of Lc3b. *P = 0.0252. Results are expressed as mean ± SEM. (B–D) PBMCs were isolated from the periphery of healthy individuals and differentiated toward DCs in the presence of GMCSF and IL-4. DCs were treated with LPS in the presence or absence of CTLA4-Ig or Ly294002 for 16 hours. (B) Immunofluorescence confocal microscopy for LC3 (red) and p62 (silver white). Scale bar: 10 μm. One representative experiment of 3 is shown. LC3 puncta/cell and p62 puncta/cell are depicted. Results are expressed as mean ± SEM; n = 6 donors per group. ***P < 0.0001. (C) Western blot analysis for expression of p-mTOR, total mTOR, p-p85, total p85, p-Akt, and total Akt in DC lysates. One representative experiment of 3 is depicted. *P = 0.0181; †P = 0.0438; ‡P = 0.0432. (D) Immunofluorescence confocal microscopy for FoxO1 (red) and DAPI (blue). Scale bar: 10 μm. One representative experiment is shown. Relative intensity for nuclear FoxO1 is depicted. Results are expressed as mean ± SEM. n = 6 healthy donors per group. Statistical significance was obtained by unpaired Student’s t test. ***P < 0.0001.