|
|
||||||||
CUTTING EDGE |

* M. D. Anderson Cancer Center, Houston, TX 77030; and
Juntendo University School of Medicine, Tokyo, Japan
| Abstract |
|---|
|
|
|---|
, and IL-2 production. Thus, during the presentation of tissue Ags to CD8+ T cells, PD-1/PD-L1 interaction crucially controls the effector differentiation of autoreactive T cells to maintain self-tolerance. | Introduction |
|---|
|
|
|---|
cells and the kidney proximal tube (4). When naive OT-I CD8+ T cells specific for the class I-restricted, OVA-derived SIINFEKL peptide were transferred into RIP-mOVA mice, OT-I cells proliferated in pancreatic lymph nodes (PLNs), but diabetes developed only with high numbers of OT-I cells or when OVA-specific CD4+ T cells were cotransferred (5). Small numbers of OT-I cells, when transferred, divided in PLNs but were largely deleted afterward. Costimulation critically regulates the commitment to T cell activation or tolerance. The lack of positive costimulation, especially B7.1 and B7.2 engagement of CD28, has been attributed to the induction of T cell tolerance in the resting state (6). However, TLR ligands that up-regulate B7 expression on DCs did not prevent CD8+ T cell tolerance to pancreatic Ags in the RIP-mOVA model (7). Thus, additional mechanism(s) must exist to regulate CD8+ T cell tolerance.
Programmed death (PD)-1, an inhibitory receptor of the CD28-family, critically regulates T cell tolerance. PD-1 is expressed on activated CD4+ and CD8+ T cells and has two ligands, PD ligand (PD-L)-1 (called PD-L1 or B7-H1) and PD-L2 (or B7-DC) (8). PD-L1 is expressed in hemopoetic cells and can be up-regulated upon activation (9). PD-L1 is also found in several tissues including pancreatic islets, heart, endothelium, small intestine, and placenta (10). In contrast, PD-L2 expression is restricted to macrophages and DCs and can be up-regulated upon activation with IFN-
, GM-CSF, and IL-4 (9). The expression pattern of PD1 ligands suggests overlapping and differential roles in immune regulation. Interestingly, we found that CD11c+CD8
+ DCs, which were previously shown to cross-present pancreatic Ags to CD8+ T cells in PLN (11), express PD-L1 but not PD-L2, whereas CD11c+CD11b+CD8
- cells express PD-L1 and PD-L2 (data not shown).
PD-1-deficient mice develop spontaneous autoimmune diseases (12, 13, 14), indicating an essential function of PD-1 in immune tolerance mechanisms. PD-1 blockade or deficiency resulted in accelerated type-I diabetes (T1D) in NOD/LtJ mice (15, 16), although it is not clear whether PD-1 functions in resistant animals to mediate protection against autoimmune diabetes. Investigations on the role of PD-1 ligands in tolerance, however, have led to contradictory results, with evidence supporting their roles as negative regulators in some scenarios and positive regulators in others (8). Recently it was reported that the PD-L1 protein expressed on islet cells mediates peripheral tolerance and prevents autoimmune attack in NOD/LtJ mice (17). Previously, an opposite conclusion was drawn on the transgenic expression of PD-L1 in the islet cells of C57BL/6J mice, where PD-L1 in the islet cells appears to promote spontaneous autoimmunity (18). In this study, we specifically analyze the function of PD-1 and its ligands in the regulation of CD8+ T cell tolerance to tissue Ags. We found that a blockade of PD-1 in the RIP-mOVA mice resulted in T1D mediated by adoptively transferred OT-I T cells. PD-L1 but not PD-L2 was required for CD8+ T cell tolerance induction. Blockade of PD-1/PD-L1 interaction during the priming phase did not significantly affect divisions of autoreactive T cells but greatly enhanced their effector differentiation.
| Materials and Methods |
|---|
|
|
|---|
C57BL/6J and OT-I transgenic mice (C57BL/6-Tg (TcraTcrb)1100 Mjb/J) were from The Jackson Laboratory, and the RIP-mOVA mice provided by W. Heath of the Walter and Eliza Hall Institute of Medical Research (Parkville, Australia) (4) were bred in M. D. Anderson Cancer Center animal facility.
Antibodies
Anti-PD-1 Abs clone J43 and clone RMP1-14 (19) were affinity purified using a protein G column. The anti-PD-L1 clone MIH5 was purchased from eBioscience (20). Anti-PD-L2 from clone TY25 was purified as previously described (9). Control IgGs were from Jackson ImmunoResearch Laboratories.
Flow cytometry
CD4, CD8, CD44, IL-2, IFN-
, and V
2 Abs were from BD Biosciences, and granzyme B (16G6) and PD-1 Abs and isotype controls were from eBioscience. An OT-I pentamer was purchased from ProImmune. All cell suspensions were incubated with anti-CD32/CD16 for 30 min at 4°C before staining with the Ab mixture. Cells were analyzed on a FACSCalibur cytometer (BD Biosciences).
Adoptive transfer and Ab treatment
CD8 cells from OT-I mice were purified using anti-CD8 Miltenyi beads and an autoMACS cell separator (Miltenyi Biotec). Cells (5 x 105 per 100 µl of PBS) were i.v injected into RIP-mOVA mice or C57BL/6J mice. Blocking Abs were i.p. administered at 100 µg per 100 µl of PBS on days 1, 4, and 7. Mice were monitored daily for urine glucose levels (Diastix; Bayer Pharmaceuticals) and high reads were confirmed by blood glucose measurements (Ascencia Elite; Bayer Pharmaceuticals). Diabetes was scored after three consecutive reads higher than 13.5 mM/L.
Proliferation, cytokine analysis, and CTL
Purified OT-I cells were adjusted to 20 x 106 cells/ml and labeled in RPMI 1640 containing 1% FBS and 10µM CFSE for 15 min at 37°C. Cells were then washed twice with RPMI 1640 and 10% FBS and one time with PBS before injection into RIP-mOVA mice or C57BL/6J mice. Blocking Abs were administered as described above. For intracellular cytokines, cell suspensions were culture for 5 h with 5 µg/ml SIINFEKL peptide and 1 µl/ml GolgiPlug, and further intracellular staining was performed with the Cytofix/Cytoperm kit (BD Biosciences). For IFN-
ELISPOT, T cells from organs were cultured for 18 h with 3 µg/ml SIINFEKL peptide and, for the CTL assay, for 5 days with 1 µg/ml peptide. A CTL assay was done by the caspase-3 cleavage assay described in Ref. 21 using EL4 cells as targets.
Histology
Pancreata from RIP-mOVA mice were fixed in 10% formalin and embedded in paraffin. Six-micrometer sections were cut every 100 microns through the total tissue and H&E staining was performed. Fifty to 100 islets per mice were scored for the presence and type of insulitis.
| Results and Discussion |
|---|
|
|
|---|
To study the role of PD-1 on peripheral tolerance of CD8+ T cells, we used the RIP-mOVA model (22). Purified CD8+ T cells from OT-I mice were transferred into RIP-mOVA mice, and a blocking Ab against PD-1 or a control IgG was administered three times in the recipient mice. Consistent with previous literature (22, 23), control mice did not develop diabetes for at least 30 days (Fig. 1A). However, all mice that received anti-PD-1 developed diabetes; hyperglycemic mice were observed 6 days after transfer. Pancreata from mice treated with anti-PD-1 showed aggressive insulitis with infiltration of CD8+ cells in the islets and also their surrounding areas, whereas mice treated with control IgG showed only peri-insulitis or no infiltration (Fig. 1, B and C). Thus, PD-1 is required for controlling the autoimmunity mediated by islet-specific CD8+ T cells.
|
Expression of PD-L1 but not PD-L2 in PLN CD11c+CD11bCD8
+ DC suggests that PD-L1 mediates cross-tolerance of CD8+ T cells. We thus used antagonistic Abs against PD-L1 and PD-L2 in the same transfer system of OT-I cells into RIP-mOVA mice. We found that 100% of the mice treated with anti-PD-L1 developed diabetes (Fig. 2). The insulitic lesions in mice treated with anti-PD-L1 were similar to the ones provoked by anti-PD-1, with predominant infiltrating CD8+ cells (data not shown). A blocking Ab against PD-L2 (9) did not have any effect; none of the RIP-mOVA mice that received OT-I cells and anti-PD-L2 developed diabetes (Fig. 2). Thus, PD-1 engagement by PD-L1 is critical in protection against autoimmunity mediated by transferred OT-I cells.
|
OT-I cells transferred into RIP-mOVA mice undergo deletion after brief proliferation (5). We thus analyzed OT-I cells from peripheral lymph nodes and spleens of recipient RIP-mOVA mice by staining with a MHC-I pentamer containing the SIINFEKEL peptide. Seven days after the transfer, the majority of tetramer-positive cells were localized in the PLNs of both anti-PD-L1- and control Ab-treated mice (Fig. 3A). Moreover, OT-I cells recovered from both groups of mice expressed high levels of CD44, indicating that they were all Ag-experienced. However, mice treated with anti-PD-L1 contained 510 times more OT-I cells per lymph node when compared with the mice treated with control Ab (Fig. 3A). Furthermore, the absolute number of OT-I cells was greatly increased in the anti-PD-L1-treated mice (Fig. 3C). Thus, PD-1-PDL1 signaling appears to mediate immune tolerance by restricting the expansion or survival of autoreactive CD8+ T cells.
|
than those from control mice (Fig. 3, D and E). Thus, PD-1/PD-L1 prevents the progression of autoreactive CD8+ T cells to long-lasting effector cells. PD-1/PD-L1 interaction restricts effector differentiation of autoreactive CD8+ T cells
The above results indicate a critical role of PD-1/PD-L1 in the control of autoimmune diabetes mediated by CD8+ T cells. Because PD-L1 is broadly expressed, it is unclear whether its interaction with PD-1 regulates CD8+ T cell tolerance during the initial priming or beyond. We thus tested the effect of anti-PD-L1 treatment on OT-I cells when they first encountered Ag-presenting DC in PLN. Cell division of CFSE-labeled OT-I cells in PLNs and spleens was first evaluated at 60 h after their transfer into RIP-mOVA or C57BL/6J mice. Divisions of OT-I cells occurred only in RIP-mOVA mice and primarily in PLNs (Fig. 4A). Anti-PD-L1 only moderately increased (by
7%) OT-I cell division in PLN, which was reflected in cells recirculating into the spleen (Fig. 4A). This suggests that PD-1 signaling does not primarily control the activation or proliferation of OT-I cells in vivo. In contrast, a profound effect on IL-2 and especially IFN-
production was observed after blocking PD-L1, where the number of cytokine-producing cells was doubled in the dividing OT-I cells (Fig. 4B). Interestingly, cytokine-expressing cells were among those exhibiting the highest numbers of cell division, which suggests a role of PD-1 in sustaining T cell activation programs. In addition, the blockade of PD-1 also resulted in greatly enhanced granzyme B expression in dividing OT-I cells (Fig. 4C). In contrast, we did not observe an enhanced proliferation or effector differentiation of OT-I cells when an anti-PD-L2 blocking Ab was administered in a similar manner (data not shown). These results indicate that PD-L1/PD-1 interaction regulates the tolerance of autoreactive CD8+ T cells during the priming phase by controlling their differentiation into effector cells. Subsequently, "nonexhausted" effector T cell likely exhibits prolonged survival because larger numbers of OT-I cells can be recovered from RIP-m OVA mice treated with anti-PD-L1 Abs at day 7 (Fig. 3, A and C).
|
| Acknowledgments |
|---|
| Disclosures |
|---|
|
|
|---|
| Footnotes |
|---|
1 This work is supported in part by grants from the National Institutes of Health (to C.D.). C.D. is a Cancer Research Institute Investigator and a Trust Fellow of the M. D. Anderson Cancer Center. ![]()
2 Address correspondence and reprint requests to Dr. Chen Dong, Department of Immunology, M. D. Anderson Cancer Center, 7455 Fannin, Unit 906, Houston, TX 77030. E-mail address: cdong{at}mdanderson.org ![]()
3 Abbreviations used in this paper: DC, dendritic cell; LN, lymph node; mOVA, membrane-bound chicken OVA; PD, programmed death; PD-L, PD ligand; PLN, pancreatic LN; RIP, rat insulin promoter. ![]()
Received for publication September 11, 2006. Accepted for publication October 17, 2006.
| References |
|---|
|
|
|---|
+ dendritic cell is responsible for inducing peripheral self-tolerance to tissue-associated antigens. J. Exp. Med. 196: 1099-1104. This article has been cited by other articles:
![]() |
S. Chikuma, S. Terawaki, T. Hayashi, R. Nabeshima, T. Yoshida, S. Shibayama, T. Okazaki, and T. Honjo PD-1-Mediated Suppression of IL-2 Production Induces CD8+ T Cell Anergy In Vivo J. Immunol., June 1, 2009; 182(11): 6682 - 6689. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Ciric, M. El-behi, R. Cabrera, G.-X. Zhang, and A. Rostami IL-23 Drives Pathogenic IL-17-Producing CD8+ T Cells J. Immunol., May 1, 2009; 182(9): 5296 - 5305. [Abstract] [Full Text] [PDF] |
||||
![]() |
X. Liu, M. Alexiou, N. Martin-Orozco, Y. Chung, R. I. Nurieva, L. Ma, Q. Tian, G. Kollias, S. Lu, D. Graf, et al. Cutting Edge: A Critical Role of B and T Lymphocyte Attenuator in Peripheral T Cell Tolerance Induction J. Immunol., April 15, 2009; 182(8): 4516 - 4520. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. D. Reynoso, K. G. Elpek, L. Francisco, R. Bronson, A. Bellemare-Pelletier, A. H. Sharpe, G. J. Freeman, and S. J. Turley Intestinal Tolerance Is Converted to Autoimmune Enteritis upon PD-1 Ligand Blockade J. Immunol., February 15, 2009; 182(4): 2102 - 2112. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. H. Koehn, M. L. Ford, I. R. Ferrer, K. Borom, S. Gangappa, A. D. Kirk, and C. P. Larsen PD-1-Dependent Mechanisms Maintain Peripheral Tolerance of Donor-Reactive CD8+ T Cells to Transplanted Tissue J. Immunol., October 15, 2008; 181(8): 5313 - 5322. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. S. Taglauer, A. S. Trikhacheva, J. G. Slusser, and M. G. Petroff Expression and Function of PDCD1 at the Human Maternal-Fetal Interface Biol Reprod, September 1, 2008; 79(3): 562 - 569. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Mozaffarian, A. E. Wiedeman, and A. M. Stevens Active systemic lupus erythematosus is associated with failure of antigen-presenting cells to express programmed death ligand-1 Rheumatology, September 1, 2008; 47(9): 1335 - 1341. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Haspot, T. Fehr, C. Gibbons, G. Zhao, T. Hogan, T. Honjo, G. J. Freeman, and M. Sykes Peripheral deletional tolerance of alloreactive CD8 but not CD4 T cells is dependent on the PD-1/PD-L1 pathway Blood, September 1, 2008; 112(5): 2149 - 2155. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Calbo, H. Delagreverie, C. Arnoult, F.-J. Authier, F. Tron, and O. Boyer Functional Tolerance of CD8+ T Cells Induced by Muscle-Specific Antigen Expression J. Immunol., July 1, 2008; 181(1): 408 - 417. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. L. Alderson, Q. Zhou, V. Berner, D. E. C. Wilkins, J. M. Weiss, B. R. Blazar, L. A. Welniak, R. H. Wiltrout, D. Redelman, and W. J. Murphy Regulatory and Conventional CD4+ T Cells Show Differential Effects Correlating with PD-1 and B7-H1 Expression after Immunotherapy J. Immunol., March 1, 2008; 180(5): 2981 - 2988. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Menke, J. A. Lucas, G. C. Zeller, M. E. Keir, X. R. Huang, N. Tsuboi, T. N. Mayadas, H. Y. Lan, A. H. Sharpe, and V. R. Kelley Programmed Death 1 Ligand (PD-L) 1 and PD-L2 Limit Autoimmune Kidney Disease: Distinct Roles J. Immunol., December 1, 2007; 179(11): 7466 - 7477. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Otahal, B. B. Knowles, S. S. Tevethia, and T. D. Schell Anti-CD40 Conditioning Enhances the TCD8 Response to a Highly Tolerogenic Epitope and Subsequent Immunotherapy of Simian Virus 40 T Antigen-Induced Pancreatic Tumors J. Immunol., November 15, 2007; 179(10): 6686 - 6695. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. E. Keir, G. J. Freeman, and A. H. Sharpe PD-1 Regulates Self-Reactive CD8+ T Cell Responses to Antigen in Lymph Nodes and Tissues J. Immunol., October 15, 2007; 179(8): 5064 - 5070. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Chen, Z. Zhang, W. Chen, Z. Zhang, Y. Li, M. Shi, J. Zhang, L. Chen, S. Wang, and F.-S. Wang B7-H1 Up-Regulation on Myeloid Dendritic Cells Significantly Suppresses T Cell Immune Function in Patients with Chronic Hepatitis B J. Immunol., May 15, 2007; 178(10): 6634 - 6641. [Abstract] [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |