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. 2016 Feb 16;44(2):316-29.
doi: 10.1016/j.immuni.2016.01.013. Epub 2016 Feb 9.

Interleukin-35 Limits Anti-Tumor Immunity

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Free PMC article

Interleukin-35 Limits Anti-Tumor Immunity

Meghan E Turnis et al. Immunity. .
Free PMC article

Abstract

Regulatory T (Treg) cells pose a major barrier to effective anti-tumor immunity. Although Treg cell depletion enhances tumor rejection, the ensuing autoimmune sequelae limits its utility in the clinic and highlights the need for limiting Treg cell activity within the tumor microenvironment. Interleukin-35 (IL-35) is a Treg cell-secreted cytokine that inhibits T cell proliferation and function. Using an IL-35 reporter mouse, we observed substantial enrichment of IL-35(+) Treg cells in tumors. Neutralization with an IL-35-specific antibody or Treg cell-restricted deletion of IL-35 production limited tumor growth in multiple murine models of human cancer. Limiting intratumoral IL-35 enhanced T cell proliferation, effector function, antigen-specific responses, and long-term T cell memory. Treg cell-derived IL-35 promoted the expression of multiple inhibitory receptors (PD1, TIM3, LAG3), thereby facilitating intratumoral T cell exhaustion. These findings reveal previously unappreciated roles for IL-35 in limiting anti-tumor immunity and contributing to T cell dysfunction in the tumor microenvironment.

Conflict of interest statement

Competing Financial Interests

The authors declare competing financial interests. DAAV and CJW have submitted patents covering IL-35 that are pending and are entitled to a share in net income generated from licensing of these patent rights for commercial development.

Figures

Fig 1
Fig 1. IL-35 blockade reduces tumor burden in multiple transplantable tumor models
(A) Schematic of transplantable tumor models (Prophylactic and Therapeutic) and timeline for antibody dosage. Mice were injected on day 0 with tumor cells (1.25×105 B16 i.d. or 5×105 MC38 s.c.). In the prophylactic model, mice received weekly administration of anti-IL-35 or IgG2b antibody (Ab) where indicated (100 μg first dose, 50 μg additional doses) (Figures 1B–D, 1G). For therapeutic analysis (Figures 1E and 1F), mice received antibody treatments at the indicated time-points once the tumor became palpable. (B) Tumor growth curves of C57BL/6 mice injected i.d. with B16 plus weekly antibody administration as in part (A). (C) Tumor growth curves of C57BL/6 mice injected s.c. with MC38 plus weekly antibody administration as in part (A). (D) Tumor growth curves of C57BL/6 mice injected i.d. with B16 on day 0 plus weekly antibody administration (anti-IL-35, anti-PD1, or IgG2b) as in part (A). (E) Tumor growth curves of C57BL/6 mice injected i.d. with B16 on day 0 followed by anti-IL-35/anti-PD1 or matched IgG controls every four days once the tumors were palpable (days 8, 12 and 16). (F) Tumor growth curves of C57BL/6 mice injected s.c. with MC38 on day 0 followed by anti-IL-35/anti-PD1 or matched IgG controls every three days once the tumors were palpable (days 6, 9 and 12). (G) C57BL/6 mice were injected i.v. with a low dose of B16 (1.25×105) on day 0 along with weekly antibody administration as in part (A). Mice were euthanized on day 21 and lung metastases were counted by microscopy. (H) Tumor growth curves of Foxp3Cre-YFP.Ebi3L/L and Foxp3Cre-YFP control mice injected i.d. with B16. (I) Lung metastases counts in Foxp3Cre-YFP.Ebi3L/L and Foxp3Cre-YFP control mice injected i.v. with a higher dose of B16 (2.5×105), assessed day 14 post-injection. Data represent 3–4 independent experiments (6 for panel 1G) with total number of mice per group in parentheses. Error bars represent SEM; *, p < 0.05; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001; ns, non-significant as determined by 2way ANOVA with multiple comparisons (panels 1B, 1C, 1D, 1E, 1F, 1H) or Unpaired Student’s t-test (panels 1G and 1I). See also Figures S1, S2 and S3.
Fig 2
Fig 2. Neutralization of IL-35 enhances anti-tumor immune memory
(A) Diagram of treatment, surgery, and re-challenge strategy. C57BL/6 mice were injected i.d. with B16 on day 0. Anti-IL-35 or IgG2b was administered weekly on days 0, 7, and 14 (100μg, 50μg, 50μg). Tumors were surgically resected on day 16–18. (B,C) Mice were re-challenged with B16 i.v. 4 (B) or 10 (C) weeks following surgery. Three weeks after re-challenge, lung metastases were counted by microscopy. (D) Photograph of lungs from 4–week re-challenged mice. (E,F) Cumulative CD44/CD62L staining from lungs of 4–week re-challenged mice, gated on CD8+ (E) or CD4+Foxp3 (F) T cells. Data represent 3–4 independent experiments; Error bars represent SEM; *, p < 0.05; ***, p < 0.001; ns, non-significant (Unpaired Student’s t-test).
Fig 3
Fig 3. Neutralization of IL-35 enhances anti-tumor immunity in a genetically-induced tumor model
(A) Schematic of the K-rasLSL-G12D/+;Trp53L/L (KP) mouse model. Mice were inoculated i.t. with 2.5×107 IU AdV-Cre, then injected therapeutically with ten weekly doses of anti-IL-35 or IgG2b isotype control (100μg/week) starting at week eight. (B) Cumulative survival curve of AdV-Cre inoculated, antibody-treated mice. (C-G) Following antibody treatments, lungs and lymph nodes were harvested at 18 weeks. (C) Quantification of lung lesions by MRI in control (PBS) and induced (AdV-Cre) mice treated with anti-IL-35 or IgG2b antibodies. (D) Representative picture of lung lobes from each treatment group. (E) Representative MRI slice from each treatment group with outline of ROIs, used to quantify lesion number and volume, shown in green. (F) Flow cytometric analysis of lung tissue indicating number of CD8+ T cells (top) and CD4+Foxp3+ Tregs (bottom) for the various treatment groups (PBS, IgG2b and anti-IL-35). (G) Flow cytometric analysis of lung tissue indicating MFI of BCL2 on Tregs (bottom) for the various treatment groups (PBS, IgG2b and anti-IL-35). Data represent 3 independent experiments. Survival curves were analyzed for statistical significance by log-rank test. Error bars represent SEM; *, p < 0.05; ***, p < 0.001; ns, non-significant as determined by Unpaired Student’s t-test (panel C) and 1 way ANOVA (panels F and G). See also Figure S4.
Fig 4
Fig 4. Increased percentages of functionally superior IL-35-expressing Tregs in TILs
(A) Tumors and spleens were harvested from day 16–18 B16-bearing Foxp3GFP mice and sorted for Treg (CD4+GFP+) and Teff (CD4+GFP) cells. Quantitative RT-PCR analysis of IL-35 subunits Il12a and Ebi3, with β-actin used as endogenous control. Controls are whole B16 cDNA isolated from Rag1−/− B16-bearing mice. (B) Representative flow cytometric plots of NDLN, DLN, and TILs from B16-bearing Foxp3Cre-YFP or Foxp3Cre-YFP.Ebi3Tom (IL-35 reporter) mice, gated on CD4+ T cells. (C) Pie charts representing percentages of Ebi3+ and Ebi3 Foxp3+ Tregs and Foxp3 Teffs in NDLN, DLN and TILs of B16-bearing IL-35 reporter mice, gated on CD4+ T cells. (D) Scatter plots representing percentages of Ebi3+Foxp3+ Tregs in the total Treg compartment (gated on CD4+Foxp3+ T cells) (left) and Ebi3+Foxp3 iTr35 cells in the total Teff compartment (gated on CD4+Foxp3 T cells) at NDLN, DLN and TIL. (E) Micro-suppression assays using sorted Ebi3+Foxp3+ and Ebi3Foxp3+ Tregs from NDLN (open circles) and TIL (closed circles) of B16 tumor-bearing mice (Top). Micro-suppression assays using sorted Foxp3Cre-YFP and Foxp3Cre-YFPEbi3L/L Tregs from NDLN (open circles) and TIL (closed circles) of B16 tumor-bearing mice (Bottom). For both experiments, CD4+Foxp3 splenocytes were used as responders (Tresponders). Plots represent percent suppression at the indicated Treg/Tresponder ratios; representative experiment of 3–4 independent replicates shown. (F) MFI of Nur77GFP gated on CD4+ T cells; Foxp3/Ebi3-expressing Tregs and Teff sub-populations from Foxp3Cre-YFP.Ebi3Tom x Nur77GFP BAC reporter mice with representative histograms shown, DLN, top; TIL, bottom. Data represent 3–4 independent experiments; Error bars represent SEM; *, p < 0.05; **, p < 0.01; ****, p < 0.0001 ns, non-significant (Unpaired Student’s t-test). See also Figure S5.
Fig 5
Fig 5. Increased infiltration and activation in the TILs of IL-35-neutralized mice
Tissues were harvested at day 16–18 from B16-bearing mice treated prophylactically with IgG2b− or anti-IL-35 and analyzed by flow cytometry. (A) Representative scatter dot plots representing absolute number of infiltrating lymphocytes (left) or T cell subsets (right) per mm3 tumor mass from IgG2b− or anti-IL-35–treated B16-bearing mice. (B and C) Percentage and absolute number of CD8+ T cells in NDLN, DLN, and TILs of IgG2b− or anti-IL-35–treated B16-bearing mice. (D) Ratio of CD8+ T cells to Foxp3+ Tregs in NDLN, DLN, and TILs of IgG2b− or anti-IL-35-treated B16-bearing mice. (E) Cumulative CD44/CD62L staining in indicated organs, gated on CD8+ (left) or CD4+Foxp3 (right) with representative flow cytometric plots shown above. (F) 18 hours prior to harvest, B16-bearing, IgG2b − or anti-IL-35–treated C57BL/6 mice were injected with BrdU. Absolute number of BrdU+Ki-67+ cells (gated on CD8+) in indicated tissues (left). Absolute number of BrdU+Ki-67+ cells (gated on CD8+CD44hiCD62Llo) in indicated tissues (right). Data represent 3 independent experiments. Error bars represent SEM; *, p < 0.05; **, p < 0.01; ns, non-significant (1way ANOVA). See also Figure S6.
Fig 6
Fig 6. Enhanced cytokine production in tumor-associated tissues of IL-35-neutralized animals
Tissues were harvested at day 16–18 from B16-bearing mice treated prophylactically with IgG2b− or anti-IL-35 and analyzed by intracellular staining under the following conditions: unstimulated, stimulated with PMA-Ionomycin (PMA-I) or stimulated with PepMix. (A,B) Scatter plots depicting percentage of IFNγ+, TNFα+ and IFNγ+TNFα+ CD8+ T cells from DLN and TIL. (C,D) Scatter plots depicting percentage of TNFα+ and TNFα+IL2+ CD4+Foxp3T cells from DLN and TIL. (E) Representative flow cytometric plots of polyfunctional DLN, stimulated as indicated. Numbers represent percent positive of parent population in each quadrant. (F) Representative flow cytometric plots of IFNγ expression from TIL, stimulated as indicated. Numbers represent percent positive of parent population. (G) H2-Kb–restricted TRP2180-188 pentamer (“SVY”) analysis of freshly isolated tissues from IgG2b− or anti-IL-35–treated tumor-bearing mice, numbers represent percent positive of CD8+ T cells. (H) Percent and absolute numbers of H2-Kb–restricted TRP2180-188 pentamer-positive CD8+ cells from DLN and TILs of IgG2b- or anti-IL-35-treated tumor-bearing mice. (I) B16-OVA tumor-bearing Foxp3Cre-YFP.Ebi3L/L and Foxp3Cre-YFP mice received 5×106 TCR transgenic (Tg) OT-I Thy1.1+ CD8+ T cells i.v. once palpable tumors developed (day 10–12). Scatter plot depicting percent infiltration of OT-I Thy1.1+ Tg CD8+ T cells 4-days post adoptive transfer into tumors of recipient mice assessed by flow analysis. Data represent 3–4 independent experiments; Error bars represent SEM; *, p < 0.05; **, p < 0.01; ns, non-significant (1way ANOVA for panels A-D and H, Unpaired Student’s t-test for panel I).
Fig 7
Fig 7. Treg-specific IL-35 deletion results in loss of exhausted T cells in the tumor microenvironment
Tissues were harvested at day 14 from B16-bearing Foxp3Cre-YFP.Ebi3L/L and Foxp3Cre-YFP control mice and analyzed by flow cytometry. (A) Flow cytometric analysis depicting expression of inhibitory receptors (PD1/TIM3 and PD1/LAG3) on tumor-infiltrating CD8+ T cells from B16 tumor-bearing Foxp3Cre-YFP.Ebi3L/L and Foxp3Cre-YFP control mice. Cells gated on CD8+ T cells, and assessed for percentage of PD1-high (PD1hi), PD1-intermediate (PD1int) and PD1-negative (PD1neg) fractions co-expressing TIM3 or LAG3. (B) Scatter plots representing percentages of the four PD1/TIM3 and PD1/LAG3-expressing CD8+ TIL populations as described in (A). (C) SPICE analysis representing percent expression and co-expression of inhibitory receptors on CD8+ TILs of B16-tumor bearing Foxp3Cre-YFP.Ebi3L/L mice and Foxp3Cre-YFP control mice. (D) Flow cytometric analysis depicting expression of inhibitory receptors (PD1/TIM3 and PD1/LAG3) on tumor-infiltrating CD4+Foxp3 T cells from B16 tumor-bearing Foxp3Cre-YFP.Ebi3L/L mice and Foxp3Cre-YFP control mice. Cells gated on CD4+Foxp3 T cells, and assessed for percentages of PD1-high (PD1hi), PD1-intermediate (PD1int) and PD1-negative (PD1neg) fractions co-expressing TIM3 or LAG3. (E) Scatter plots representing percentages of the four PD1/TIM3 and PD1/LAG3-expressing CD4+Foxp3 TIL populations as described in (D). (F) SPICE analysis representing percent expression and co-expression of inhibitory receptors on CD4+Foxp3 TILs of B16-tumor bearing Foxp3Cre-YFP.Ebi3L/L mice and Foxp3Cre-YFP control mice. Data represents 4 independent experiments; Error bars represent SEM; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001; ns, non-significant (Unpaired Student’s t-test). See also Figure S7.

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