The vimentin intermediate filament network restrains regulatory T cell suppression of graft-versus-host disease
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
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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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 3

Vimentin disruption increases Treg-mediated suppression of Tcon priming and GI tract damage.

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Vimentin disruption increases Treg-mediated suppression of Tcon priming ...
(A–C) GVHD transplantation with recipient mice given BM plus Tcons alone or BM plus Tcons plus Tregs. Tregs were either (A and B) pretreated with DMSO or AEB071 or (C) transfected with control or vimentin siRNA. (A) CFSE analysis of splenic donor CD8+ Tcon proliferation on day 4 after transplantation. (B and C) Analysis of splenic donor CD4+ and CD8+ Tcon numbers on day 4 after transplantation. (D and E) Multiphoton analysis of day-4 post-transplantation brachial lymph nodes from mice given BM and EGFP-TEα CD4+ and CMTMR-labeled OT-I CD8+ alone (BM+T) or BM plus Tcons plus DMSO-pretreated (DMSO) or AEB071-pretreated (AEB071) polyclonal Tregs. Graphs show (D) velocities and (E) confinement ratios for each TEα cell. Each dot represents a single TEα cell (300 cells/group). Red line indicates the mean. (F and G) Histopathology scoring (0 = no pathology, 4 = severe pathology) for H&E-stained small intestine and colon sections harvested on day 14 after transplantation. Recipient mice were given BM, BM plus Tcons, or BM plus Tcons plus Tregs. Tregs were (F) pretreated with either DMSO or AEB071 or (G) transfected with control or vimentin siRNA. Data show 1 representative experiment of 4 (A–C), 3 (D and E), or 2 (F and G) independent experiments. n = 6 mice/group (G); n = 5 mice/group (C), n = 4 mice/group (A, B, and F), and n = 3 mice/group (D and E). *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001, by 1-way ANOVA with multiple comparisons analysis and Tukey’s post test. Error bars indicate the SEM.