The vimentin intermediate filament network restrains regulatory T cell suppression of graft-versus-host disease
Cameron McDonald-Hyman, … , Michael L. Dustin, Bruce R. Blazar
Cameron McDonald-Hyman, … , Michael L. Dustin, Bruce R. Blazar
Published August 14, 2018
Citation Information: J Clin Invest. 2018;128(10):4604-4621. https://doi.org/10.1172/JCI95713.
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Research Article Immunology

The vimentin intermediate filament network restrains regulatory T cell suppression of graft-versus-host disease

Abstract

Regulatory T cells (Tregs) are critical for maintaining immune homeostasis. However, current Treg immunotherapies do not optimally treat inflammatory diseases in patients. Understanding the cellular processes that control Treg function may allow for the augmentation of therapeutic efficacy. In contrast to activated conventional T cells, in which protein kinase C-θ (PKC-θ) localizes to the contact point between T cells and antigen-presenting cells, in human and mouse Tregs, PKC-θ localizes to the opposite end of the cell in the distal pole complex (DPC). Here, using a phosphoproteomic screen, we identified the intermediate filament vimentin as a PKC-θ phospho target and show that vimentin forms a DPC superstructure on which PKC-θ accumulates. Treatment of mouse Tregs with either a clinically relevant PKC-θ inhibitor or vimentin siRNA disrupted vimentin and enhanced Treg metabolic and suppressive activity. Moreover, vimentin-disrupted mouse Tregs were significantly better than controls at suppressing alloreactive T cell priming in graft-versus-host disease (GVHD) and GVHD lethality, using a complete MHC-mismatch mouse model of acute GVHD (C57BL/6 donor into BALB/c host). Interestingly, vimentin disruption augmented the suppressor function of PKC-θ–deficient mouse Tregs. This suggests that enhanced Treg activity after PKC-θ inhibition is secondary to effects on vimentin, not just PKC-θ kinase activity inhibition. Our data demonstrate that vimentin is a key metabolic and functional controller of Treg activity and provide proof of principle that disruption of vimentin is a feasible, translationally relevant method to enhance Treg potency.

Authors

Cameron McDonald-Hyman, James T. Muller, Michael Loschi, Govindarajan Thangavelu, Asim Saha, Sudha Kumari, Dawn K. Reichenbach, Michelle J. Smith, Guoan Zhang, Brent H. Koehn, Jiqiang Lin, Jason S. Mitchell, Brian T. Fife, Angela Panoskaltsis-Mortari, Colby J. Feser, Andrew Kemal Kirchmeier, Mark J. Osborn, Keli L. Hippen, Ameeta Kelekar, Jonathan S. Serody, Laurence A. Turka, David H. Munn, Hongbo Chi, Thomas A. Neubert, Michael L. Dustin, Bruce R. Blazar

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Figure 5

Vimentin disruption increases Nrp1 and Lag3 expression.

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Vimentin disruption increases Nrp1 and Lag3 expression. (A–C) Analysis o...
(A–C) Analysis of Nrp1 and Lag3 expression on splenic donor Tregs on day 4 after GVHD transplantation, with recipient mice given BM plus Tcons plus Tregs. Mice were given either (A and B) DMSO- or AEB071-pretreated Tregs or (C) control or vimentin siRNA–transfected Tregs. (D) Suppression of CD4+ Tcon proliferation by DMSO- and AEB071-pretreated or control and vimentin siRNA–pretreated Tregs in classical in vitro suppression assays with either isotype or anti-Lag3–blocking mAb (α-Lag3) or anti-Nrp1–blocking mAb (α-Nrp1). 1:3 Treg/Tcon ratio. (E) Quantifications of the percentage of reduction of suppression with the anti-Lag3 treatment shown in D. (F and G) Percentage of in vitro Transwell suppression of CD4+ Tcon proliferation by (F) DMSO- or AEB071-pretreated Tregs or (G) control or vimentin siRNA–pretreated Tregs. Groups were given isotype, anti-Lag3–blocking mAb, or anti-Nrp1–blocking mAb. (H) Quantification of the percentage of reduction in Transwell suppression with the anti-Nrp1 treatment shown in F and G. Data for 1 representative experiment of 4 independent experiments are shown. n = 4 mice/group (A–C); n = 4 replicates/group (D–H). *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by unpaired Student’s t test (B, C, E, and H) and 1-way ANOVA with multiple comparisons analysis and Tukey’s post test (D, F, and G). Error bars indicate the SEM.