Regulatory T cells and cancer: an undesired tolerance

Himatanthus drasticus (Apocynaceae) latex reduces oxidative stress and modulates CD4+, CD8+, FoxP3+ and HSP-60+ expressions in Sarcoma 180-bearing mice

ETHNOPHARMACOLOGICAL RELEVANCE

In Brazil, latex of Himatanthus drasticus is used to treat inflammation, wound healing and cancer. The present study evaluated the antitumoral potential of H. drasticus latex (HdCL) in Sarcoma 180-bearing mice (S180).

MATERIALS AND METHODS

HdCL was obtained in Crato-CE, Brazil. Qualitative phytochemicals assays, nuclear magnetic resonance (NMR) and microbiological analyzes were performed. Swiss mice were divided into six groups, according to tumor forms: 1) ascitic model, GI (Control; 0.9% saline), GII (S₁₈₀asc) and GIII (S₁₈₀asc/HdCL/14 days); 2) solid model, GIV (Control; 0.9% saline), GV (S₁₈₀sol) and GVI (S₁₈₀sol/HdCL/10 days). HdCL and 0.9% saline were administered at 0.2 mL, SID, by gavage, for 10 or 14 days. For ascitic model, 0.5 mL of S180 suspension (4×10⁶ cells/mL) was inoculated intraperitoneally and for solid model, cells were inoculated subcutaneously (25 µL) on the right hind paw of mice. Blood samples were collected for hematological and oxidative stress evaluation. Thickness, volume and weight of paws were measured in solid model. After euthanasia, spleen, liver and kidney were collected in order to assess the relative organ weight. Tissue fragments of paws and popliteal lymph nodes (PLN) were analyzed by H&E and CD4⁺, CD8⁺, HSP-60⁺ and Foxp3⁺ immunohistochemistry.

RESULTS

HdCL presented milky aspect and pinkish supernatant. Phenols, flavonols, flavanones, free steroids and cinnamoyl derivatives of lupeol, α-amyrin and β-amyrin were detected at the phytochemistry analysis. HdCL did not alter the relative weight of organs, hematological parameters and volume of ascitic fluid recovered. In solid model, HdCL reduced (P < 0.05) paw volume, but did not altered thickness, paw weight and histological parameters. S180sol induced necrosis, metastasis and destruction of bone, cartilage and muscles. Bleeding, vessel congestion and oncocytes were observed in PLN. In paw, HdCL did not alter FoxP3⁺ and HSP-60⁺ expressions but reduced the CD4⁺ and CD8⁺ expressions, while at PLN, HdCL reduced the expressions of all markers. HdCL decreased (P < 0.05) serum levels of malondialdehyde in ascitic model.

CONCLUSIONS

Treatment with HdCL reduced oxidative damage and modulated the expressions of CD4⁺, CD8⁺, FoxP3⁺and HSP-60⁺ in S180 solid tumor model, which can be associated to the presence of triterpenes, such as α-amyrin, β-amyrin and lupeol cinnamate. Present data emphasizes the importance of immune system in cancer and highlights the evaluation of the pharmacological properties of plants used by population as phytoterapics.

Immunological effects of vaccines combined with granulocyte colony-stimulating factor on a murine WEHI-3 leukemia model

Granulocyte colony-stimulating factor (G-CSF) mobilizes regulatory T cells (Tregs) from bone marrow into the peripheral blood, by reducing the expression of stromal cell-derived factor-1α (SDF-1α). However, G-CSF has rarely been studied in acute myeloid leukemia (AML) immunotherapy. The present study performed a Transwell migration assay in vitro to determine the contribution of SDF-1α to the migration of leukemia cells, and the effects of G-CSF were evaluated. The effects of G-CSF on SDF-1α and Tregs in the AML microenvironment were examined, by employing a WEHI-3-grafted BALB/c mouse AML model (AML-M4). It is evident that G-CSF reversed immunosuppression of the AML microenvironment by reducing SDF-1α in bone marrow and elevating Tregs in the peripheral blood in in vivo studies. Furthermore, AML mice treated with vaccines combined with G-CSF achieved a longer survival time than those treated with vaccines without G-CSF, showing the efficiency of the regimen. The present study demonstrates the effects of G-CSF on the mobilization of leukemia cells and Tregs into the peripheral blood. In addition, immunotherapy with G-CSF priming represents a promising therapeutic strategy of targeting the immunosuppression.

Magnitude of PD-1, PD-L1 and T Lymphocyte Expression on Tissue from Castration-Resistant Prostate Adenocarcinoma: An Exploratory Analysis

BACKGROUND AND AIM

Recent therapeutic strategies for castration-resistant prostate cancer have focused on immunomodulation, especially the PD-1/PD-L1 pathway related to tumor-infiltrating lymphocytes. Few cases of castration-resistant prostate adenocarcinoma have been tested simultaneously for PD-1, PD-L1 and T lymphocytes in cancerous tissue. We quantified the PD-1/PD-L1 immune pathway and T lymphocyte infiltrates in a series of patients with castrate-resistant prostate adenocarcinoma.

PATIENTS AND METHODS

Expression of PD-1, PD-L1, CD3 and FOXP3 was identified in tissue microarrays, with five tissue spots per patient from 16 patients over at least 5 years of follow-up. Two scores were defined. The first described the percentage of PD-1-positive T lymphocytes (CD3+): negative (0), <5 %; low (1+), 5-30 %; high (2+), >30 %. The second described PD-L1 staining intensity: 0 (no signal), 1+ (light signal), 2+ (high signal) in >50 % of neoplastic cells.

RESULTS

Tumor-infiltrating T lymphocytes (CD3+) were seen in 11/16 cases (69 %). Nine of 16 cases expressed PD-1 (56 %), among which 19 % were scored 2+. Eight of 16 cases expressed PD-L1 (50 %), with 19 % scored as strong 2+. The subgroup with high PD1/PD-L1 also exhibited FOXP3 expression.

CONCLUSIONS

Approximately 19 % of patients in our series showed simultaneous high PD-1/PD-L1 immunoscores, and were the best candidates for receiving targeted anti-PD-1/PD-L1 immunotherapy, as determined using a tissue based rationale.

Downregulation of myeloma-induced ICOS-L and regulatory T cell generation by lenalidomide and dexamethasone therapy

Multiple myeloma (MM) produces significant cellular and humoral immune defects. We have previously reported that MM induces CD4(+)CD25(+)FoxP3(+) cells (TRegs), via tumour expression of the immune checkpoint regulator, ICOS-L. We sought to define what impact the immunomodulatory drug lenalidomide, alone or with dexamethasone, has on TReg cell generation. Lenalidomide pre-treatment of MM cell lines reduced TReg generation and the concomitant TReg:TEff (CD4(+)CD25(+)FoxP3(-): effector T cells) ratio, as a consequence of reduced ICOSL transcription. Dexamethasone did not affect surface ICOS-L expression but did induce TReg cell apoptosis without impacting on TEff cell survival. Combined lenalidomide and dexamethasone significantly reduced both TReg induction and the TReg:TEff cell ratio. In vivo, serial analysis of the TReg:TEff ratio in MM patients on lenalidomide-dexamethasone therapy revealed a progressive reduction towards age-matched control values, though not complete correction. Our data demonstrate for the first time immune synergism to explain the observed immune-modulation associated with lenalidomide-dexamethasone therapy.