scholarly journals 4071 Dynamic Control of Tumor Vessels Augments Antitumor Responses

2020 ◽  
Vol 4 (s1) ◽  
pp. 6-6
Author(s):  
Emmanuel M Gabriel ◽  
Deborah Bahr ◽  
Sanjay Bagaria ◽  
Debrabata Muhkopadhyay ◽  
Keith Knutson
Keyword(s):  
Drug Delivery ◽  
T Cells ◽  
Blood Flow ◽  
Tumor Growth ◽  
Dynamic Control ◽  
Effector T Cells ◽  
Cell Trafficking ◽  
Tumor Vessels ◽  
Vessel Response ◽  
Therapy Model

OBJECTIVES/GOALS: Our overall objective is to develop a directly observable and reproducible method of enhanced blood flow through tumor vessels (i.e. dynamic control) at the time of systemic treatment delivery. Our central hypothesis is that the dynamic control of tumor vessels will improve (1) systemic drug delivery and (2) effector cell trafficking to target tumor. METHODS/STUDY POPULATION: B16 melanoma cells were inoculated into C57BL/6 (B6) mice (male and female) in both regional (hind leg) and systemic (flank) models. Dynamic control consisted of an IV saline bolus (500 ul) and phenylephrine (10 ug). Tumor vessel response was observed in real-time through window chambers using intravital microscopy (IVM). Dynamic control was combined with melphalan (20 mg/ml) either regionally (isolated limb perfusion) or systemically. Outcomes included tumor growth, survival, IHC, and toxicity. Dynamic control will be combined with adoptive transfer of effector T cells. B6 mice will be inoculated with B16/OVA (flank with window chamber) and treated with fluorescently labeled (calcein), OVA-specific CD8+ T cells from OT-1 transgenic mice. IVM, IHC, and flow cytometry will be used to measure T cell trafficking. RESULTS/ANTICIPATED RESULTS: Dynamic control (1) restored blood flow in non-functional tumor vessels and (2) increased and then transiently reversed blood flow in functional vessels. Vessel diameters did not change, suggesting that shunting of systemic blood to the tumor vasculature accounted for the observed changes. Dynamic control augmented tumor responses in our regional therapy model of melanoma. Increases in DNA adduct formation (melphalan mechanism of action) detected by IHC, decreased tumor growth, and increased survival were observed with dynamic control. There was no increased limb toxicity. Similarly, dynamic control augmented responses in our systemic therapy model (decreased tumor growth and improved survival). We anticipate that dynamic control will improve trafficking of effector T cells in the next set of experiments. DISCUSSION/SIGNIFICANCE OF IMPACT: Heterogeneous responses to systemic therapies represent a major gap in current cancer treatment. An essential requirement for any effective therapy is its ability to reach tumor via the tumor-associated vasculature. We have therefore developed an approach to enhance drug delivery (dynamic control), which we also plan to test in clinical trials.

scholarly journals Live imaging of effector cell trafficking and autoantigen recognition within the unfolding autoimmune encephalomyelitis lesion

2005 ◽  
Vol 201 (11) ◽  
pp. 1805-1814 ◽  
Author(s):  
Naoto Kawakami ◽  
U. Valentin Nägerl ◽  
Francesca Odoardi ◽  
Tobias Bonhoeffer ◽  
Hartmut Wekerle ◽  
...  
Keyword(s):  
T Cells ◽  
Fixed Point ◽  
Intrathecal Injection ◽  
Cell Receptor ◽  
Effector T Cells ◽  
Cell Trafficking ◽  
Lymphocyte Function ◽  
Autoimmune Encephalomyelitis ◽  
Two Photon ◽  
Maximal Speed

We tracked pathogenic myelin basic protein-specific CD4+ effector T cells in early central nervous system (CNS) lesions of experimental autoimmune encephalomyelitis (EAE) by combining two-photon imaging and fluorescence video microscopy. We made two key observations: (a) the majority of the cells (65%) moved fast (maximal speed 25 μm/min) and apparently nondirected through the compact tissue; and (b) a second group of effector T cells (35%) appeared tethered to a fixed point. Polarization of T cell receptor and adhesion molecules (lymphocyte function-associated antigen 1) towards this fixed point suggests the formation of immune synapses. Nonpathogenic, ovalbumin-specific T cells were not tethered in the CNS and did not form synapse-like contacts, but moved through the tissue. After intrathecal injection of antigen, 40% of ovalbumin-specific T cells became tethered. Conversely, injection of anti–major histocompatibility complex class II antibodies profoundly reduced the number of stationary pathogenic T cells within the CNS (to 15%). We propose that rapid penetration of the CNS parenchyma by numerous autoimmune effector T cells along with multiple autoantigen-presentation events are responsible for the fulminate development of clinical EAE.

scholarly journals Phosphoinositide (3,4,5)-Triphosphate Binding to Phosphoinositide-Dependent Kinase 1 Regulates a Protein Kinase B/Akt Signaling Threshold That Dictates T-Cell Migration, Not Proliferation

2009 ◽  
Vol 29 (21) ◽  
pp. 5952-5962 ◽  
Author(s):  
Caryll Waugh ◽  
Linda Sinclair ◽  
David Finlay ◽  
Jose R. Bayascas ◽  
Doreen Cantrell
Keyword(s):  
T Cells ◽  
T Cell ◽  
Protein Kinase ◽  
Protein Kinase B ◽  
Effector T Cells ◽  
T Cell Response ◽  
Cell Trafficking ◽  
Ph Domain ◽  
Activated T Cells ◽  
Phosphoinositide Dependent Kinase

ABSTRACT The present study explored the consequences of phosphoinositide (3,4,5)-triphosphate [PI(3,4,5)P3] binding to the pleckstrin homology (PH) domain of the serine/threonine kinase 3-phosphoinositide-dependent kinase 1 (PDK1). The salient finding is that PDK1 directly transduces the PI(3,4,5)P3 signaling that determines T-cell trafficking programs but not T-cell growth and proliferation. The integrity of the PDK1 PH domain thus is not required for PDK1 catalytic activity or to support cell survival and the proliferation of thymic and peripheral T cells. However, a PDK1 mutant that cannot bind PI(3,4,5)P3 cannot trigger the signals that terminate the expression of the transcription factor KLF2 in activated T cells and cannot switch the chemokine and adhesion receptor profile of naïve T cells to the profile of effector T cells. The PDK1 PH domain also is required for the maximal activation of Akt/protein kinase B (PKB) and for the maximal phosphorylation and inactivation of Foxo family transcription factors in T cells. PI(3,4,5)P3 binding to PDK1 and the strength of PKB activity thus can dictate the nature of the T-cell response. Low levels of PKB activity can be sufficient for T-cell proliferation but insufficient to initiate the migratory program of effector T cells.

scholarly journals Leveraging the Treg-intrinsic CTLA4–PKCη signaling pathway for cancer immunotherapy

2021 ◽  
Vol 9 (9) ◽  
pp. e002792
Author(s):  
Hsin-Yu Liu ◽  
Christophe Pedros ◽  
Kok-Fai Kong ◽  
Ann J Canonigo-Balancio ◽  
Wen Xue ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Antitumor Immunity ◽  
Effector T Cells ◽  
Clinical Approach ◽  
Antitumor Effects ◽  
Tumor Implantation ◽  
Therapeutic Model

BackgroundOur previous studies revealed a critical role of a novel CTLA4-protein kinase C-eta (PKCη) signaling axis in mediating the suppressive activity of regulatory T cells (Tregs) in antitumor immunity. These studies have employed adoptive transfer of germline PKCη-deficient (Prkch−/−) Tregs into Prkch+/+ mice prior to tumor implantation. Here, we extended these findings into a biologically and clinically more relevant context.MethodsWe have analyzed the role of PKCη in antitumor immunity and the tumor microenvironment (TME) in intact tumor-bearing mice with Treg-specific or CD8+ T cell-specific Prkch deletion, including in a therapeutic model of combinatorial treatment. In addition to measuring tumor growth, we analyzed the phenotype and functional attributes of tumor-infiltrating immune cells, particularly Tregs and dendritic cells (DCs).ResultsUsing two models of mouse transplantable cancer and a genetically engineered autochthonous hepatocellular carcinoma (HCC) model, we found, first, that mice with Treg-specific Prkch deletion displayed a significantly reduced growth of B16–F10 melanoma and TRAMP-C1 adenocarcinoma tumors. Tumor growth reduction was associated with a less immunosuppressive TME, indicated by increased numbers and function of tumor-infiltrating CD8+ effector T cells and elevated expression of the costimulatory ligand CD86 on intratumoral DCs. In contrast, CD8+ T cell-specific Prkch deletion had no effect on tumor growth or the abundance and functionality of CD8+ effector T cells, consistent with findings that Prkch−/− CD8+ T cells proliferated normally in response to in vitro polyclonal or specific antigen stimulation. Similar beneficial antitumor effects were found in mice with germline or Treg-specific Prkch deletion that were induced to develop an autochthonous HCC. Lastly, using a therapeutic model, we found that monotherapies consisting of Treg-specific Prkch deletion or vaccination with irradiated Fms-like tyrosine kinase 3 ligand (Flt3L)-expressing B16–F10 tumor cells post-tumor implantation significantly delayed tumor growth. This effect was more pronounced in mice receiving a combination of the two immunotherapies.ConclusionThese findings demonstrate the potential utility of PKCη inhibition as a viable clinical approach to treat patients with cancer, especially when combined with adjuvant therapies.

scholarly journals Generation and decay of the immune response to a progressive fibrosarcoma. I. Ly-1+2- suppressor T cells down-regulate the generation of Ly-1-2+ effector T cells.

1984 ◽  
Vol 159 (5) ◽  
pp. 1295-1311 ◽  
Author(s):  
R J North ◽  
I Bursuker
Keyword(s):  
T Cells ◽  
Tumor Growth ◽  
Effector T Cells ◽  
Suppressor T Cells ◽  
Established Tumor ◽  
Concomitant Immunity ◽  
Progressive Growth ◽  
Adoptive Immunity ◽  
Gamma Irradiated ◽  
Tumor Implant

It was shown that the progressive growth of the immunogenic meth A fibrosarcoma in its semisyngeneic host results in the generation of concomitant immunity to the growth of a tumor implant. The generation of immunity occurred between days 6 and 9 of tumor growth and was associated with the generation of sensitized T cells that were capable, on passive transfer, of causing regression of a 3-d tumor in gamma-irradiated recipients. After day 9 of tumor growth, concomitant immunity and the T cells able to passively transfer it were progressively lost, and this was associated with the generation of splenic suppressor T cells able to suppress the expression of adoptive immunity against an established tumor in T cell-deficient ( TXB ) recipients. The T cells that passively transferred concomitant immunity were shown to be of the Ly-1-2+ phenotype, in contrast to the T cells that transferred suppression, which were shown with the same reagents to be Ly-1+2-. The results are consistent with the hypothesis that the progressive growth of an immunogenic tumor results in the generation of Ly-1-2+-sensitized effector T cells that fail to reach a number sufficient to destroy the tumor because their generation is down-regulated by tumor-induced Ly-1+2- suppressor T cells.

The Role of Pretransplant Conditioning On Graft-Versus-Leukemia Effects: Migration Matters.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3563-3563
Author(s):  
Ji-Young Lim ◽  
Mi-Sun Choi ◽  
Eun Young Choi ◽  
Hyewon Youn ◽  
Chang-Ki Min
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Cd4 T Cells ◽  
Tumor Tissue ◽  
Cell Trafficking ◽  
Tnf Α ◽  
Ifn Γ ◽  
Conditioning Intensity

Abstract Abstract 3563 Poster Board III-500 The therapeutic potential of allogeneic hematopoietic stem cell transplantation (HSCT) relies on the graft-versus-leukemia (GVL) effect to eradicate residual tumor cells by immunologic mechanisms. However, the relationship of conditioning intensity to GVL effect has not been clearly established independent of immunosuppression or the tolerance induced by mixed donor-host chimerism. Using a murine allogeneic HSCT model, we have compared two total body irradiation (TBI) doses (1,300 vs. 900 cGy), both of which provided complete donor engraftment and elimination of host lympho-hematopoetic cells. We used C57BL/6 (H-2b) → B6D2F1 (H-2b/d) model of GVHD, which differ at major and minor histocompatibility loci, to address the role of conditioning intensity on the GVL effect. Lethally irradiated (either 900 or 1300 cGy) recipient mice were transplanted with either C57BL/6 (allogeneic) or B6D2F1 (syngeneic) bone marrow (5 × 106) and spleen T cells (1 × 106) on day 0 and then P815 (H-2d) mastocytoma cells (1 × 106) injected subcutaneously on day 1 to generate a GVL model. As expected, GVHD morbidity after the higher TBI dose was aggravated compared to the lower TBI dose (P<.05). Among the syngeneic recipients, the injection of P815 cells into the recipient skin led to progressive tumor growth and death of about 100% 21 days after transplant regardless of the TBI dose. In contrast, tumor growth was remarkably suppressed and tumor death was not observed in the allogeneic recipients. Surprisingly, tumors in the allogeneic recipients receiving 1300 cGy TBI exhibited markedly delayed growth in vivo compared to those with 900 cGy (tumor volume on day 42, 428 vs. 8735mm3, P<.01), which was associated with an increase in the in vivo cytotoxicity using comparing the clearance of infused allogeneic B cells labeled with CFSE reflecting the enhanced alloimmune reactivity. To ask whether the diminished GVL effect after the lower TBI dose was due to reduced production of inflammatory cytokines, we measured the levels of TNF-α or IFN-γ in recipient sera on days 6, 28 and 42 after transplantation and did not find any significant difference according to the intensity of radiation dose (P>.05). In parallel, the in vitro P815-specific TNF-α or IFN-γ responses of splenocytes were comparable between the two doses. The percentages of donor T cells to undergo proliferation or apoptosis in response to alloantigens in vivo between the two TBI doses also were comparable (P>.05). Collectively, these data indicate that the impaired ability of alloreacive T cells to inhibit tumor growth after the lower TBI dose was not attributed to an intrinsic defect in T-cell expansion and activation. We next analyzed the spleen for the number of donor CD4+ and CD8+ T cells and observed no difference between the two TBI doses. In contrast to spleen, the number of CD8+ but not CD4+ T cells from the recipients that had received 1300 cGy was significantly increased in the skin (P<05). The effector function of donor CD8+ and CD4+ cells in both spleen and tumor tissue was examined by intracellular staining for IFN-γ. In the spleen, the percentages of CD8+ and CD4+ T cells expressing IFN-γ were not different between the two TBI doses. (5.9% vs 4.8%, P>.05, and 7.6% vs. 6.5%, P>.05 respectively) By contrast, 45.5% and 50.3% of CD8+ and CD4+ T cells, respectively, isolated from the tumor tissue of recipients receiving the higher TBI dose were IFN-γ; secreting cells, whereas only 25.5% and 16.3% of those cells from the tumor tissue of recipients treated with the lower dose showed this phenotype (P<.01 and <.05, respectively). After the higher TBI dose, secondary lymphoid organ homing receptors including CD62L and CCR7 were down-regulated on donor CD8+ T cells while CD44 expression was up-regulated compared to the lower TBI dose, which may facilitate migration to the tumor sites. In summary, the higher TBI dose (1300 vs. 900 cGy) resulted in significantly enhanced GVL effect, and the alterations in effector T cell trafficking into tumor tissue are the most likely mechanism. Moreover, T-cell activation and function were largely comparable between these conditioning regimens. This provides the rationale for targeting T cell trafficking by inflammation, possibly in combination with integrin or chemokine receptor agonists as a new therapeutic approach in leukemia relapse after allogeneic HSCT. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Radiation-induced, immunologically mediated regression of an established tumor as an example of successful therapeutic immunomanipulation. Preferential elimination of suppressor T cells allows sustained production of effector T cells.

1986 ◽  
Vol 164 (5) ◽  
pp. 1652-1666 ◽  
Author(s):  
R J North
Keyword(s):  
T Cells ◽  
Tumor Growth ◽  
Tumor Regression ◽  
Effector T Cells ◽  
Whole Body ◽  
Suppressor T Cells ◽  
Established Tumor ◽  
Published Evidence ◽  
The One ◽  
Immunocompetent Mice

The results of this study confirm results published by others by showing that sublethal whole-body irradiation of mice bearing immunogenic tumors can result in complete tumor regression. The results show, in addition, that irradiation-induced tumor regression can be prevented by infusion, after irradiation, of Ly-1+,2-,L3T4+ suppressor T cells from the spleens of donors bearing an established tumor, but not by infusion of normal spleen cells. This evidence, plus the demonstration that irradiation fails to cause regression of tumors growing in immunocompetent mice, is consistent with the hypothesis that irradiation-induced regression is immunologically mediated, and that it depends on the ability of irradiation to preferentially eliminate suppressor T cells. By using passive transfer assays to measure the production of effector T cells and suppressor T cells against time of tumor growth, it was shown that irradiation of tumor-bearing mice on day 5 of tumor growth resulted in a failure to generate suppressor T cells on the one hand, and in a sustained production, effector T cells on the other. In other words, irradiation prevented the concomitant antitumor immune response from being downregulated by suppressor T cells. However, giving radiation on day 1 of tumor growth, in contrast to giving it 3-6 d later, caused immunodepression and enhancement of tumor growth. This is in keeping with published evidence showing that, whereas resting effector T cells are highly radiosensitive, antigen-activated effector T cells are relatively radioresistant. It is suggested that the radioresistance of activated effector T cells, coupled with the radiosensitivity of activated suppressor T cells, is the reason for the selectivity of ionizing radiation for suppressor T cells and why a tumor needs to be palpable to undergo regression in response to radiation therapy.

scholarly journals Bcl6 Preserves the Suppressive Function of Regulatory T Cells during Tumorigenesis

2020 ◽  
Author(s):  
Yiding Li ◽  
Zhiming Wang ◽  
Huayu Lin ◽  
Lisha Wang ◽  
Xiangyu Chen ◽  
...  
Keyword(s):  
T Cells ◽  
Tumor Microenvironment ◽  
Tumor Growth ◽  
Treg Cell ◽  
Synergistic Effects ◽  
Treg Cells ◽  
Immune Checkpoint Blockade ◽  
Effector T Cells ◽  
Tumor Control ◽  
Suppressive Function

AbstractDuring tumorigenesis, tumor infiltrating regulatory T (Treg) cells restrict the function of effector T cells in tumor microenvironment and thereby promoting tumor growth. The anti-tumor activity of effector T cells can be therapeutically unleashed, and is now being exploited for the treatment of various types of human cancers. However, the immune suppressive function of Treg cells remains a major hurdle to broader effectiveness of tumor immunotherapy. In this article, we reported that the deletion of Bcl6 specifically in Treg cells led to stunted tumor growth, which was caused by impaired Treg cell responses. Notably, Bcl6 is essential in maintaining the lineage stability of Treg cells in tumor microenvironment. Meanwhile, we found that the absence of follicular regulatory T (Tfr) cells, which is a result of Bcl6 deletion in Foxp3+ cells, was dispensable for tumor control. Importantly, the increased Bcl6 expression in Treg cells is associated with poor prognosis of human colorectal cancer and lymph node metastasis of skin melanoma. Furthermore, Bcl6 deletion in Treg cells exhibits synergistic effects with immune checkpoint blockade therapy. Collectively, these results indicate that Bcl6 actively participates in regulating Treg cell immune responses during tumorigenesis and can be exploited as a therapeutic target of anti-tumor immunity.

scholarly journals Reversing Epigenetic Gene Silencing to Overcome Immune Evasion in CNS Malignancies

2021 ◽  
Vol 11 ◽  
Author(s):  
Nivedita M. Ratnam ◽  
Heather M. Sonnemann ◽  
Stephen C. Frederico ◽  
Huanwen Chen ◽  
Marsha-Kay N. D. Hutchinson ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Immune Evasion ◽  
Immune Cell ◽  
Single Agent ◽  
Cell Infiltration ◽  
Cell Trafficking ◽  
T Cell Infiltration ◽  
Dismal Prognosis

Glioblastoma (GBM) is an aggressive brain malignancy with a dismal prognosis. With emerging evidence to disprove brain-immune privilege, there has been much interest in examining immunotherapy strategies to treat central nervous system (CNS) cancers. Unfortunately, the limited success of clinical studies investigating immunotherapy regimens, has led to questions about the suitability of immunotherapy for these cancers. Inadequate inherent populations of tumor infiltrating lymphocytes (TILs) and limited trafficking of systemic, circulating T cells into the CNS likely contribute to the poor response to immunotherapy. This paucity of TILs is in concert with the finding of epigenetic silencing of genes that promote immune cell movement (chemotaxis) to the tumor. In this study we evaluated the ability of GSK126, a blood-brain barrier (BBB) permeable small molecule inhibitor of EZH2, to reverse GBM immune evasion by epigenetic suppression of T cell chemotaxis. We also evaluated the in vivo efficacy of this drug in combination with anti-PD-1 treatment on tumor growth, survival and T cell infiltration in syngeneic mouse models. GSK126 reversed H3K27me3 in murine and human GBM cell lines. When combined with anti-PD-1 treatment, a significant increase in activated T cell infiltration into the tumor was observed. This resulted in decreased tumor growth and enhanced survival both in sub-cutaneous and intracranial tumors of immunocompetent, syngeneic murine models of GBM. Additionally, a significant increase in CXCR3+ T cells was also seen in the draining lymph nodes, suggesting their readiness to migrate to the tumor. Closer examination of the mechanism of action of GSK126 revealed its ability to promote the expression of IFN-γ driven chemokines CXCL9 and CXCL10 from the tumor cells, that work to traffic T cells without directly affecting T maturation and/or proliferation. The loss of survival benefit either with single agent or combination in immunocompromised SCID mice, suggest that the therapeutic efficacy of GSK126 in GBM is primarily driven by lymphocytes. Taken together, our data suggests that in glioblastoma, epigenetic modulation using GSK126 could improve current immunotherapy strategies by reversing the epigenetic changes that enable immune cell evasion leading to enhanced immune cell trafficking to the tumor.

scholarly journals Improvement of PD-1 Blockade Efficacy and Elimination of Immune-Related Gastrointestinal Adverse Effect by mTOR Inhibitor

2021 ◽  
Vol 12 ◽  
Author(s):  
Xin Bai ◽  
Xueyan Wang ◽  
Guozhen Ma ◽  
Jinen Song ◽  
Xiaowei Liu ◽  
...  
Keyword(s):  
T Cells ◽  
Tumor Growth ◽  
Mtor Inhibitor ◽  
Immune Checkpoint Blockade ◽  
Effector T Cells ◽  
Mtor Pathway ◽  
T Cell Infiltration ◽  
Mouse Melanoma Model ◽  
Melanoma Model

During the past decades, immunotherapy, especially the antibody-mediated immune checkpoint blockade (ICB) has shown durable tumor inhibition and changed the paradigm of cancer treatment. However, a growing body of evidence suggests that ICB treatment induces severe immune-related adverse events (irAEs), and the side effect even leads to the discontinuation of lifesaving treatment. Here, we found that ICB treatment induces colitis in melanoma patients and promotes the infiltration of CD8+ effector T cells into colitic lesions. Further transcriptomic dissection indicated the PI3K-AKT-mTOR pathway was highly activated in CD8+ effector T cells of colitic lesions. Moreover, we developed a mouse melanoma model to recapitulate the gastrointestinal toxicity of anti-PD-1 treatment in clinical settings. Anti-PD-1 treatment significantly contributed to the infiltration of CD8+ T cells, and correspondingly induced severe enteritis. Immunohistochemistry experiments showed that the PI3K-AKT-mTOR pathway of T cells was activated by anti-PD-1 treatment. Blockade of the pathway with mTOR inhibitor sirolimus not only inhibits tumor growth but also suppresses the T cell infiltration in colitic lesions. More importantly, combination with sirolimus and anti-PD-1 synergistically inhibits tumor growth via inducing the immunogenic cell death of tumor cells in vivo. In summary, our research demonstrated the principle of mTOR inhibitor and anti-PD-1 combinatorial therapeutic regimen, which provided a novel therapeutic strategy for irAEs in clinics.

scholarly journals Pre-existing intratumoral CD8 T cells substantially contribute to control tumors following therapeutic anti-CD40 and polyI:C based vaccination

2020 ◽  
Author(s):  
Aaron D. Stevens ◽  
Timothy N.J. Bullock
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Cd8 T Cells ◽  
Tumor Control ◽  
Cell Trafficking ◽  
T Cell Trafficking ◽  
Cell Numbers

ABSTRACTBackgroundDendritic cells are potently activated by the synergistic action of CD40 stimulation in conjunction with signaling through toll like receptors, subsequently activating antigen specific T cells. Cancer vaccines targeting the activation of dendritic cells in this manner show promise in murine models and are being developed for human cancer patients. While vaccine efficacy has been established, further investigation is needed to understand the mechanism of tumor control and how vaccination alters tumor infiltrating immune cells.MethodsMice bearing established murine melanoma tumors were vaccinated with agonist anti-CD40, polyI:C, and tumor antigen. Intratumoral T cell numbers, differentiation state, proliferation, and survival were assessed by flow cytometry. T cell effector function was measured both within the tumor and ex vivo by flow cytometry. T cell trafficking was blocked to examine changes to intratumoral T cells present at the time of vaccination.ResultsVaccination led to increased intratumoral T cell numbers and delayed tumor growth. Expansion of T cells and tumor control did not require trafficking of T cells from the periphery. The increase in intratumoral T cells was associated with an acute burst in proliferation but not changes in viability. Intratumoral T cells had lower PD-1 and Eomes expression but were less functional after vaccination on a per cell basis. However, the increased intratumoral T cell numbers yielded increased effector T cells per tumor.ConclusionsPre-infiltrated CD8 T cells are responsive to CD40/TLR-mediated vaccination and sufficient for vaccination to delay tumor growth when additional T cell trafficking is blocked. This indicates that the existing T cell response and intratumoral DC could be critical for vaccination efficacy. This also suggests that circulating T cells may not be an appropriate biomarker for vaccination efficacy.

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