Tregs restrain dendritic cell autophagy to ameliorate autoimmunity
Themis Alissafi, … , Ken Cadwell, Panayotis Verginis
Themis Alissafi, … , Ken Cadwell, Panayotis Verginis
Published June 5, 2017
Citation Information: J Clin Invest. 2017;127(7):2789-2804. https://doi.org/10.1172/JCI92079.
View: Text | PDF
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

×

Figure 3

Restrained DC autophagy impairs antigen presentation and CD4+ T cell responses.

Options: View larger image (or click on image) Download as PowerPoint
Restrained DC autophagy impairs antigen presentation and CD4+ T cell res...
(A) Carboxylated beads conjugated to LPS/OVA-Fluor (green) were internalized by DCs from Rag1–/– immunized mice adoptively transferred with Foxp3+ or Foxp3–CD4+ T cells and analyzed for LC3 (red). ***P < 0.0001, Pearson’s correlation coefficient. Representative images from 3 experiments Scale bars: 5 μm. (B and C) DCs from naive mice were treated with LPS and MOG35–55 in the presence or absence of NH4Cl (B) or MRT37607 (C) for 4 hours and cultured with CellTrace-labeled 2D2 T cells. CellTrace dilution and division index are shown. *P = 0.0187; **P = 0.0070; †P = 0.0363. (D) DCs from Atg16l1ΔCd11lc or Atg16l1fl/fl MOG35–55–immunized mice were pulsed with MOG35–55 for 4 hours and cultured with CellTrace-labeled 2D2 T cells. CellTrace dilution and division index are shown. *P = 0.0438; **P = 0.0012. (E) DCs from Atg16l1ΔCd11lc or Atg16l1fl/fl mice were pulsed with OVA protein for 18 hours and cultured with CellTrace-labeled OT-II T cells. CellTrace dilution and division index are shown. Representative images from 3 experiments. **P = 0.0073. (F) Experimental design for EAE induction upon adoptive transfer of DCs from Atg16l1ΔCd11lc or Atg16l1fl/fl mice and 2D2 T cells into Rag1–/– mice. (G) Mean clinical score and EAE severity. *P = 0.0494; †P = 0.0180; ‡P = 0.0196; §P = 0.0121; P = 0.0066; **P = 0.0061; ***P < 0.0001. (H) Representative H&E sections from spinal cords of Atg16l1ΔCd11lc (clinical score 3.5) and Atg16l1fl/fl (clinical score 1.5) mice at 14 days after immunization. ***P < 0.0001. Results are expressed as mean ± SEM. n = 4 mice per group. Statistical significance was obtained by unpaired Student’s t test (B–H) or 2-way ANOVA (A).