Manja Idorn

Voluntary Running Suppresses Tumor Growth through Epinephrine- and IL-6-Dependent NK Cell Mobilization and Redistribution

Regular exercise reduces the risk of cancer and disease recurrence. Yet the mechanisms behind this protection remain to be elucidated. In this study, tumor-bearing mice randomized to voluntary wheel running showed over 60% reduction in tumor incidence and growth across five different tumor models. Microarray analysis revealed training-induced upregulation of pathways associated with immune function. NK cell infiltration was significantly increased in tumors from running mice, whereas depletion of NK cells enhanced tumor growth and blunted the beneficial effects of exercise. Mechanistic analyses showed that NK cells were mobilized by epinephrine, and blockade of β-adrenergic signaling blunted training-dependent tumor inhibition. Moreover, epinephrine induced a selective mobilization of IL-6-sensitive NK cells, and IL-6-blocking antibodies blunted training-induced tumor suppression, intratumoral NK cell infiltration, and NK cell activation. Together, these results link exercise, epinephrine, and IL-6 to NK cell mobilization and redistribution, and ultimately to control of tumor growth.

Correlation between frequencies of blood monocytic myeloid-derived suppressor cells, regulatory T cells and negative prognostic markers in patients with castration-resistant metastatic prostate cancer

Abstract Myeloid-derived suppressor cells (MDSC) are believed to play a role in immune suppression and subsequent failure of T cells to mount an efficient anti-tumor response, by employing both direct T-cell inhibition as well as induction of regulatory T cells (Tregs). Investigating the frequency and function of immune suppressive cell subsets in the peripheral blood of 41 patients with prostate cancer (PC) and 36 healthy donors (HD) showed a significant increase in circulating CD14+ HLA-DRlow/neg monocytic MDSC (M-MDSC) and Tregs in patients with PC compared to HD. Furthermore, M-MDSC frequencies correlated positively with Treg levels. In vitro proliferation assay with autologous T cells confirmed M-MDSC-mediated T-cell suppression, and intracellular staining of immune suppressive enzyme iNOS revealed a higher expression in M-MDSC from patients with PC. Increased frequencies of M-MDSC correlated with known negative prognostic markers in patients with PC including elevated levels of lactate dehydrogenase and prostate-specific antigen. Accordingly, high levels of M-MDSC were associated with a shorter median overall survival. Our data strongly suggest that M-MDSC, possibly along with Tregs, play a role in establishing an immune suppressive environment in patients with PC. Moreover, correlation of M-MDSC frequency with known prognostic markers and the observed impact on OS could reflect a possible role in tumor progression. Further insight into the generation and function of MDSC and their interplay with Tregs and other cell types may suggest ways to tackle their induction and/or function to improve immunological tumor control.

Exercise-Dependent Regulation of NK Cells in Cancer Protection

Natural killer (NK) cells are the most responsive immune cells to exercise, displaying an acute mobilization to the circulation during physical exertion. Recently, exercise-dependent mobilization of NK cells was found to play a central role in exercise-mediated protection against cancer. Here, we review the link between exercise and NK cell function, focusing on circulating exercise factors and additional effects, including vascularization, hypoxia, and body temperature in mediating the effects on NK cell functionality. Exercise-dependent mobilization and activation of NK cells provides a mechanistic explanation for the protective effect of exercise on cancer, and we propose that exercise represents a potential strategy as adjuvant therapy in cancer, by improving NK cell recruitment and infiltration in solid tumors.

High frequency of T cells specific for cryptic epitopes in melanoma patients

A number of cytotoxic T-cell epitopes are cryptic epitopes generated from non-conventional sources. These include epitopes that are encoded by alternative open reading frames or in generally non-coding genomic regions, such as introns. We have previously observed a frequent recognition of cryptic epitopes by tumor infiltrating lymphocytes isolated from melanoma patients. Here, we show that such cryptic epitopes are more frequently recognized than antigens of the same class encoded by canonical reading frames. Furthermore, we report the presence of T cells specific for three cryptic epitopes encoded in intronic sequences, as a result of incomplete splicing, in the circulation of melanoma patients. One of these epitopes derives from antigen isolated from immunoselected melanoma 2 (AIM2), while the two others are encoded in an alternative open reading frame of an incompletely spliced form of N-acetylglucosaminyl-transferase V (GNT-V) known as NA17-A. We have detected frequent T-cell responses against AIM2 and NA17-A epitopes in the blood of melanoma patients, both prior and after one round of in vitro peptide stimulation, but not in the circulation of healthy individuals and patients with breast or renal carcinoma. In summary, our findings indicate that the T-cell reactivity against AIM2 and NA17-A in the blood of melanoma patients is extensive, suggesting that—similar to melan A (also known as MART1)—these antigens might be used for immunomonitoring or as model antigens in several clinical and preclinical settings.

Acquired Immune Resistance Follows Complete Tumor Regression without Loss of Target Antigens or IFNγ Signaling

Cancer immunotherapy can result in durable tumor regressions in some patients. However, patients who initially respond often experience tumor progression. Here, we report mechanistic evidence of tumoral immune escape in an exemplary clinical case: a patient with metastatic melanoma who developed disease recurrence following an initial, unequivocal radiologic complete regression after T-cell-based immunotherapy. Functional cytotoxic T-cell responses, including responses to one mutant neoantigen, were amplified effectively with therapy and generated durable immunologic memory. However, these immune responses, including apparently effective surveillance of the tumor mutanome, did not prevent recurrence. Alterations of the MHC class I antigen-processing and presentation machinery (APM) in resistant cancer cells, but not antigen loss or impaired IFNγ signaling, led to impaired recognition by tumor-specific CD8+ T cells. Our results suggest that future immunotherapy combinations should take into account targeting cancer cells with intact and impaired MHC class I-related APM. Loss of target antigens or impaired IFNγ signaling does not appear to be mandatory for tumor relapse after a complete radiologic regression. Personalized studies to uncover mechanisms leading to disease recurrence within each individual patient are warranted. Cancer Res; 77(17); 4562-6. ©2017 AACR.

Clonal expansion of renal cell carcinoma-infiltrating T lymphocytes

T lymphocytes can mediate the destruction of cancer cells by virtue of their ability to recognize tumor-derived antigenic peptides that are presented on the cell surface in complex with HLA molecules and expand. Thus, the presence of clonally expanded T cells within neoplastic lesions is an indication of ongoing HLA-restricted T cell-mediated immune responses. Multiple tumors, including renal cell carcinomas (RCCs), are often infiltrated by significant amounts of T cells, the so-called tumor-infiltrating lymphocytes (TILs). In the present study, we analyzed RCC lesions (n = 13) for the presence of expanded T-cell clonotypes using T-cell receptor clonotype mapping. Surprisingly, we found that RCCs comprise relatively low numbers of distinct expanded T-cell clonotypes as compared with melanoma lesions. The numbers of different T-cell clonotypes detected among RCC-infiltrating lymphocytes were in the range of 1–17 (median = 5), and in several patients, the number of clonotypes expanded within tumor lesions resembled that observed among autologous peripheral blood mononuclear cells. Moreover, several of these clonotypes were identical in TILs and PBMCs. Flow cytometry data demonstrated that the general differentiation status of CD8+ TILs differed from that of circulating CD8+ T cells. Furthermore, PD-1 and LAG-3 were expressed by a significantly higher percentage of CD8+ RCC-infiltrating lymphocytes as compared with PBMCs obtained from RCC patients or healthy individuals. Thus, CD8+ TILs display a differentiated phenotype and express activation markers as well as surface molecules associated with the inhibition of T-cell functions. However, TILs are characterized by a low amount of expanded T-cell clonotypes.

Exercise and cancer: from “healthy” to “therapeutic”?

Exercise improves functional capacity and patient-reported outcomes across a range of cancer diagnoses. The mechanisms behind this protection have been largely unknown, but exercise-mediated changes in body composition, sex hormone levels, systemic inflammation, and immune cell function have been suggested to play a role. We recently demonstrated that voluntary exercise leads to an influx of immune cells in tumors, and a more than 60% reduction in tumor incidence and growth across several mouse models. Given the common mechanisms of immune cell mobilization in mouse and man during exercise, we hypothesize that this link between exercise and the immune system can be exploited in cancer therapy in particular in combination with immunotherapy. Thus, we believe that exercise may not just be “healthy” but may in fact be therapeutic.

Pre-Vaccination Frequencies of Th17 Cells Correlate with Vaccine-Induced T-Cell Responses to Survivin-Derived Peptide Epitopes

Various subsets of immune regulatory cells are suggested to influence the outcome of therapeutic antigen-specific anti-tumor vaccinations. We performed an exploratory analysis of a possible correlation of pre-vaccination Th17 cells, MDSCs, and Tregs with both vaccination-induced T-cell responses as well as clinical outcome in metastatic melanoma patients vaccinated with survivin-derived peptides. Notably, we observed dysfunctional Th1 and cytotoxic T cells, i.e. down-regulation of the CD3ζchain (p=0.001) and an impaired IFNγ-production (p=0.001) in patients compared to healthy donors, suggesting an altered activity of immune regulatory cells. Moreover, the frequencies of Th17 cells (p=0.03) and Tregs (p=0.02) were elevated as compared to healthy donors. IL-17-secreting CD4+ T cells displayed an impact on the immunological and clinical effects of vaccination: Patients characterized by high frequencies of Th17 cells at pre-vaccination were more likely to develop survivin-specific T-cell reactivity post-vaccination (p=0.03). Furthermore, the frequency of Th17 (p=0.09) and Th17/IFNγ+ (p=0.19) cells associated with patient survival after vaccination. In summary, our explorative, hypothesis-generating study demonstrated that immune regulatory cells, in particular Th17 cells, play a relevant role for generation of the vaccine-induced anti-tumor immunity in cancer patients, hence warranting further investigation to test for validity as predictive biomarkers.

Association of a functional Indoleamine 2,3-dioxygenase 2 genotype with specific immune responses

Two frequent single-nucleotide-polymorphisms (SNPs) are present in the indoleamine 2,3-dioxygenase 2 (IDO2) gene that influence its enzymatic activity. Thus, one SNP (R248W) is associated with a reduction in IDO2 catalytic activity, whereas the other SNP (Y359stop) generates a premature stop codon abolishing activity completely. In the present study, we describe the presence of a specific cellular immune response in the periphery which correlated with the functional status of the IDO2 protein. Hence, the induction of IDO2-specific T cells in peripheral blood requires the presence of a functional IDO2 protein and, consequently, is restricted to individuals that are not homozygous for the stop codon. Furthermore, we detected stronger T-cell responses in donors with the homozygous Y wild type at position 359 when compared with the heterozygous genotype. Interestingly, we found a higher number of immune responses against IDO2 in patients homozygous for the 248W giving reduction in IDO2 activity compared with the 248R. Hence, spontaneous immune responses against IDO2 seem to be correlated with reduced enzymatic activity of IDO2. The patient IDO2 genotype may well influence the outcome of IDO2-based anti-cancer vaccination.

Chemokine receptor engineering of T cells with CXCR2 improves homing towards subcutaneous human melanomas in xenograft mouse model

ABSTRACT Adoptive cell therapy (ACT) using in vitro expanded tumor infiltrating T lymphocytes (TILs) from biopsy material represents a highly promising treatment of disseminated cancer. A crucial prerequisite for successful ACT is sufficient recruitment of transferred lymphocytes to the tumor site; however, despite infusion of billions of lymphocytes, T cell infiltration into the tumor post ACT is limited. By PCR and Luminex analyses we found that a majority of malignant melanoma (MM) cell lines expressed chemokines CXCL1/Groα, CXCL8/IL-8, CXCL12/SDF-1 and CCL2. Concerning expression of the corresponding receptors on T cells, only the IL-8 receptor, CXCR2, was not expressed on T cells. CXCR2 was therefore expressed in T cells by lentiviral transduction, and shown to lead to ligand specific transwell migration of engineered T cells, as well as increased migration towards MM conditioned medium. In vivo homing was assessed in a xenograft NOG mouse model. Mice with subcutaneous human melanoma were treated with MAGE-A3 specific T cells transduced with either CXCR2 or MOCK. Transducing T cells carrying the MAGE-A3a3a high affinity T cell receptor with CXCR2 increased tumor infiltration. Flow cytometry analysis 7 days after ACT showed a doubling in CD3+ T cells in tumor digest of mice receiving CXCR2 transduced T cells compared to MOCK treated mice, a finding confirmed by immunohistochemistry. In conclusion, our CXCR2 transduced T cells are functional in vitro and transduction with CXCR2 increases in vivo homing of T cells to tumor site.