PGE2 limits effector expansion of tumour-infiltrating stem-like CD8+ T cells

Cancer-specific TCF1+ stem-like CD8+ T cells can drive protective anticancer immunity through expansion and effector cell differentiation1-4; however, this response is dysfunctional in tumours. Current cancer immunotherapies2,5-9 can promote anticancer responses through TCF1+ stem-like CD8+ T cells in some but not all patients. This variation points towards currently ill-defined mechanisms that limit TCF1+CD8+ T cell-mediated anticancer immunity. Here we demonstrate that tumour-derived prostaglandin E2 (PGE2) restricts the proliferative expansion and effector differentiation of TCF1+CD8+ T cells within tumours, which promotes cancer immune escape. PGE2 does not affect the priming of TCF1+CD8+ T cells in draining lymph nodes. PGE2 acts through EP2 and EP4 (EP2/EP4) receptor signalling in CD8+ T cells to limit the intratumoural generation of early and late effector T cell populations that originate from TCF1+ tumour-infiltrating CD8+ T lymphocytes (TILs). Ablation of EP2/EP4 signalling in cancer-specific CD8+ T cells rescues their expansion and effector differentiation within tumours and leads to tumour elimination in multiple mouse cancer models. Mechanistically, suppression of the interleukin-2 (IL-2) signalling pathway underlies the PGE2-mediated inhibition of TCF1+ TIL responses. Altogether, we uncover a key mechanism that restricts the IL-2 responsiveness of TCF1+ TILs and prevents anticancer T cell responses that originate from these cells. This study identifies the PGE2-EP2/EP4 axis as a molecular target to restore IL-2 responsiveness in anticancer TILs to achieve cancer immune control.

Rational design of PD-1-CD28 immunostimulatory fusion proteins for CAR T cell therapy

BACKGROUND

In many situations, the therapeutic efficacy of CAR T cells is limited due to immune suppression and poor persistence. Immunostimulatory fusion protein (IFP) constructs have been advanced as a tool to convert suppressive signals into stimulation and thus promote the persistence of T cells, but no universal IFP design has been established so far. We now took advantage of a PD-1-CD28 IFP as a clinically relevant structure to define key determinants of IFP activity.

METHODS

We compared different PD-1-CD28 IFP variants in a human leukemia model to assess the impact of distinctive design choices on CAR T cell performance in vitro and a xenograft mouse model.

RESULTS

We observed that IFP constructs that putatively exceed the extracellular length of PD-1 induce T-cell response without CAR target recognition, rendering them unsuitable for tumour-specific therapy. IFP variants with physiological PD-1 length ameliorated CAR T cell effector function and proliferation in response to PD-L1+ tumour cells in vitro and prolonged survival in vivo. Transmembrane or extracellular CD28 domains were found to be replaceable by corresponding PD-1 domains for in vivo efficacy.

CONCLUSION

PD-1-CD28 IFP constructs must mimic the physiological interaction of PD-1 with PD-L1 to retain selectivity and mediate CAR-conditional therapeutic activity.

Bispecific antibodies redirect synthetic agonistic receptor modified T cells against melanoma

BACKGROUND

Melanoma is an immune sensitive disease, as demonstrated by the activity of immune check point blockade (ICB), but many patients will either not respond or relapse. More recently, tumor infiltrating lymphocyte (TIL) therapy has shown promising efficacy in melanoma treatment after ICB failure, indicating the potential of cellular therapies. However, TIL treatment comes with manufacturing limitations, product heterogeneity, as well as toxicity problems, due to the transfer of a large number of phenotypically diverse T cells. To overcome said limitations, we propose a controlled adoptive cell therapy approach, where T cells are armed with synthetic agonistic receptors (SAR) that are selectively activated by bispecific antibodies (BiAb) targeting SAR and melanoma-associated antigens.

METHODS

Human as well as murine SAR constructs were generated and transduced into primary T cells. The approach was validated in murine, human and patient-derived cancer models expressing the melanoma-associated target antigens tyrosinase-related protein 1 (TYRP1) and melanoma-associated chondroitin sulfate proteoglycan (MCSP) (CSPG4). SAR T cells were functionally characterized by assessing their specific stimulation and proliferation, as well as their tumor-directed cytotoxicity, in vitro and in vivo.

RESULTS

MCSP and TYRP1 expression was conserved in samples of patients with treated as well as untreated melanoma, supporting their use as melanoma-target antigens. The presence of target cells and anti-TYRP1 × anti-SAR or anti-MCSP × anti-SAR BiAb induced conditional antigen-dependent activation, proliferation of SAR T cells and targeted tumor cell lysis in all tested models. In vivo, antitumoral activity and long-term survival was mediated by the co-administration of SAR T cells and BiAb in a syngeneic tumor model and was further validated in several xenograft models, including a patient-derived xenograft model.

CONCLUSION

The SAR T cell-BiAb approach delivers specific and conditional T cell activation as well as targeted tumor cell lysis in melanoma models. Modularity is a key feature for targeting melanoma and is fundamental towards personalized immunotherapies encompassing cancer heterogeneity. Because antigen expression may vary in primary melanoma tissues, we propose that a dual approach targeting two tumor-associated antigens, either simultaneously or sequentially, could avoid issues of antigen heterogeneity and deliver therapeutic benefit to patients.

T cell-derived interleukin-22 drives the expression of CD155 by cancer cells to suppress NK cell function and promote metastasis

Although T cells can exert potent anti-tumor immunity, a subset of T helper (Th) cells producing interleukin-22 (IL-22) in breast and lung tumors is linked to dismal patient outcome. Here, we examined the mechanisms whereby these T cells contribute to disease. In murine models of lung and breast cancer, constitutional and T cell-specific deletion of Il22 reduced metastases without affecting primary tumor growth. Deletion of the IL-22 receptor on cancer cells decreases metastasis to a degree similar to that seen in IL-22-deficient mice. IL-22 induced high expression of CD155, which bound to the activating receptor CD226 on NK cells. Excessive activation led to decreased amounts of CD226 and functionally impaired NK cells, which elevated the metastatic burden. IL-22 signaling was also associated with CD155 expression in human datasets and with poor patient outcomes. Taken together, our findings reveal an immunosuppressive circuit activated by T cell-derived IL-22 that promotes lung metastasis.

Migratory Engineering of T Cells for Cancer Therapy

Adoptive cell therapy (ACT) and chimeric antigen receptor (CAR) T cell therapy in particular represents an adaptive, yet versatile strategy for cancer treatment. Convincing results in the treatment of hematological malignancies have led to FDA approval for several CAR T cell therapies in defined refractory diseases. In contrast, the treatment of solid tumors with adoptively transferred T cells has not demonstrated convincing efficacy in clinical trials. One of the main reasons for ACT failure in solid tumors is poor trafficking or access of transferred T cells to the tumor site. Tumors employ a variety of mechanisms shielding themselves from immune cell infiltrates, often translating to only fractions of transferred T cells reaching the tumor site. To overcome this bottleneck, extensive efforts are being undertaken at engineering T cells to improve ACT access to solid tumors. In this review, we provide an overview of the immune cell infiltrate in human tumors and the mechanisms tumors employ toward immune exclusion. We will discuss ways in which T cells can be engineered to circumvent these barriers. We give an outlook on ongoing clinical trials targeting immune cell migration to improve ACT and its perspective in solid tumors.

Polymer-Induced Drag Reduction in Dilute Newtonian and Semi-Dilute Non-Newtonian Fluids: An Assessment of the Double-Gap Concentric Cylinder Method

Polymer-induced drag reduction (DR) in fluids was studied using a rotational rheometer with double-gap concentric cylinder geometry. Although both polymers (polyacrylamide (PAM) and 2-acrylamido-2-methylpropane sulfonic acid (SPAM)) had molecular weights of several MDa, the contrasting polymer charge, nonionic and anionic, led to different polymer overlap concentrations (c*), PAM ≫ SPAM, and fluid rheology, with PAM fluids mostly Newtonian and SPAM fluids non-Newtonian (shear-thinning). Based on these differences, it was important to account for the infinite shear viscosity and normalize the polymer concentration by the intrinsic concentration (c_int) so that the DR performance of the two polymer fluids could be accurately compared. Both polymers induced DR, and the maximum DR by SPAM (DR% = 28) was slightly higher than that by PAM (DR% = 22) when Re_p ∼ 1700. For PAM, the loss of DR with time diminished at higher polymer concentrations (≥100 ppm, at Re_p = 3149) but was found to be sensitive to high Re_p, with polymer chain scission the likely cause of the reduced performance. For the semi-dilute SPAM fluids, the shear stability contrasted that of PAM, showing negligible dependence on the polymer concentration and Re_p. The apparent rapid loss of DR was predominantly attributed to a time-dependent effect and not polymer degradation. In pipe flow, the maximum DR for SPAM was higher than that measured by rheometry and was attributed to differences in the flow conditions. However, changes in the normalized DR/c with polymer concentration were found to be consistent between the two flow geometries. Furthermore, the high fluid stresses in pipe flow (at high Re_p) led to drag reduction losses consistent with PAM, as the time-dependent effect was not seen.

CAR T Cells Targeting Membrane-Bound Hsp70 on Tumor Cells Mimic Hsp70-Primed NK Cells

Strategies to boost anti-tumor immunity are urgently needed to treat therapy-resistant late-stage cancers, including colorectal cancers (CRCs). Cytokine stimulation and genetic modifications with chimeric antigen receptors (CAR) represent promising strategies to more specifically redirect anti-tumor activities of effector cells like natural killer (NK) and T cells. However, these approaches are critically dependent on tumor-specific antigens while circumventing the suppressive power of the solid tumor microenvironment and avoiding off-tumor toxicities. Previously, we have shown that the stress-inducible heat shock protein 70 (Hsp70) is frequently and specifically expressed on the cell surface of many different, highly aggressive tumors but not normal tissues. We could take advantage of tumors expressing Hsp70 on their membrane (‘mHsp70’) to attract and engage NK cells after in vitro stimulation with the 14-mer Hsp70 peptide TKDNNLLGRFELSG (TKD) plus low dose interleukin (IL)-2. However, a potential limitation of activated primary NK cells after adoptive transfer is their comparably short life span. T cells are typically long-lived but do not recognize mHsp70 on tumor cells, even after stimulation with TKD/IL-2. To combine the advantages of mHsp70-specificity with longevity, we constructed a CAR having specificity for mHsp70 and retrovirally transduced it into primary T cells. Co-culture of anti-Hsp70 CAR-transduced T cells with mHsp70-positive tumor cells stimulates their functional responsiveness. Herein, we demonstrated that human CRCs with a high mHsp70 expression similarly attract TKD/IL-2 stimulated NK cells and anti-Hsp70 CAR T cells, triggering the release of their lytic effector protein granzyme B (GrB) and the pro-inflammatory cytokine interferon (IFN)-γ, after 4 and 24 hours, respectively. In sum, stimulated NK cells and anti-Hsp70 CAR T cells demonstrated comparable anti-tumor effects, albeit with somewhat differing kinetics. These findings, together with the fact that mHsp70 is expressed on a large variety of different cancer entities, highlight the potential of TKD/IL-2 pre-stimulated NK, as well as anti-Hsp70 CAR T cells to provide a promising direction in the field of targeted, cell-based immunotherapies which can address significant unmet clinical needs in a wide range of cancer settings.

Ets-1 is up-regulated together with its target gene products matrix metalloproteinase-2 and matrix metalloproteinase-9 in atypical and anaplastic meningiomas

AIMS

Matrix metalloproteinases (MMPs) are a pivotal enzyme system involved in extracellular matrix (ECM) degradation and are considered to be important in the development and invasion of human tumours. Little is known about the regulation of MMPs in meningioma development and prognosis. The transcription factor Ets-1 is the main regulator of several MMPs, including MMP-2 and -9. The aim of this study was to determine the relationship between the expression of Ets-1, MMP-2 and -9 and the malignant potential of meningiomas.

METHODS AND RESULTS

Seventy-four meningiomas of different histological grades were investigated immunohistochemically. Up-regulation of Ets-1, MMP-2 and MMP-9 expression was observed in atypical and anaplastic meningiomas. Invasive meningiomas showed increased immunohistochemical expression of these proteins compared with non-invasive meningiomas. We also observed a correlation between the expression of Ets-1 and of its target genes MMP-2 and MMP-9.

CONCLUSIONS

Ets-1 may be involved in the transcriptional regulation of MMP-2 and MMP-9 as well as in the invasive process in meningiomas. Evaluation of these expressions might be of prognostic value for meningiomas.

Decreased C4 complement component serum levels correlate with the degree of emphysema in patients with chronic bronchitis

Patients with COPD who fulfill the diagnostic criteria of chronic bronchitis have been shown to exhibit lower serum levels of complement components C3 and C4 than healthy subjects, and this may indicate sustained complement activation as a result of recurrent respiratory tract infections. Since activation of complement leads to influx of inflammatory cells into the lung parenchyma with subsequent release of elastases and oxidants that cause damage to elastic lung tissue, we postulated that there might be a quantitative relationship between complement consumption and degree of elastic tissue destruction. In this study, we tried to investigate possible correlations between serum levels of C3 and C4 and degree of emphysema among patients with COPD of the bronchitic type. We studied 20 patients with chronic bronchitis aged 68+/-1 years (mean+/-SEM) without significant fluctuations of serum C3 and C4 levels over a 3-month period by performing detailed lung function tests, recording of emphysema score in chest radiogram, and the incidence of infective exacerbations during the past 3 years. Measured C3 and C4 serum levels were 124+/-9 and 28.5+/-2 mg/dL, respectively, lower than the respective levels in control subjects (141+/-3 and 39+/-2 mg/dL, respectively). Significant correlations were observed between levels of C4 and (1) incidence of respiratory tract infections during the past 3 years (r=-0.747, p<0.001), (2) radiologic emphysema score (r=-0.936, p<0.001), and (3) various functional indexes, such as midexpiratory flow rate, percent of predicted (r=0.629, p<0.01), forced expiratory flow rate at 50% of vital capacity, percent of predicted (r=0.606, p<0.01), residual volume/total lung capacity ratio (r=-0.651, p<0.01), and the exponential constant of static pressure-volume curve (r=-0.606, p<0.01). These results suggest that patients with chronic bronchitis with the lowest levels of C4 are those experiencing more frequent respiratory infections, tend to have more signs indicative of emphysema in their chest radiograph, have a more prominent small airways dysfunction and gas trapping, and present a greater defect in lung elastic recoil.

Relationship between immunoglobulin levels, tuberculin hypersensitivity and radiological extent of disease in Greek patients with pulmonary tuberculosis

Greek patients with pulmonary tuberculosis, who were studied before receiving any form of treatment, tended to have elevated immunoglobulin (Ig) levels in the IgG and IgA, but not the IgM, classes. This is in agreement with the findings of the majority of studies on immunoglobulin levels in other countries. The levels of IgA were particularly associated with the extent of disease and were significantly higher in smear-positive than in smear-negative patients. There was no significant relationship between the intensity of tuberculin sensitivity and immunoglobulin levels except for a weak tendency for patients with high IgA levels to have small skin reactions to tuberculin.

Relationship between immunoglobulin levels, tuberculin hypersensitivity and radiological extent of disease in Greek patients with pulmonary tuberculosis

Greek patients with pulmonary tuberculosis, who were studied before receiving any form of treatment, tended to have elevated immunoglobulin (Ig) levels in the IgG and IgA, but not the IgM, classes. This is in agreement with the findings of the majority of studies on immunoglobulin levels in other countries. The levels of IgA were particularly associated with the extent of disease and were significantly higher in smear-positive than in smear-negative patients. There was no significant relationship between the intensity of tuberculin sensitivity and immunoglobulin levels except for a weak tendency for patients with high IgA levels to have small skin reactions to tuberculin.