Interleukin 6 Present in Inflammatory Ascites from Advanced Epithelial Ovarian Cancer Patients Promotes Tumor Necrosis Factor Receptor 2-Expressing Regulatory T Cells

Abstract

BackgroundEpithelial ovarian cancer (EOC) remains a highly lethal gynecological malignancy. Ascites, an accumulation of peritoneal fluid present in one-third of patients at presentation, is linked to poor prognosis. High levels of regulatory T cells (Tregs) in ascites are correlated with tumor progression and reduced survival. Malignant ascites harbors high levels of Tregs expressing the tumor necrosis factor receptor 2 (TNFR2), as well as pro-inflammatory factors such as interleukin 6 (IL-6) and tumor necrosis factor (TNF). IL-6 is also associated with poor prognosis. Herein, we study the effect of IL-6 and TNF present in ascites on the modulation of TNFR2 expression on T cells, and specifically Tregs.MethodsAscites and respective peripheral blood sera were collected from 18 patients with advanced EOC and soluble biomarkers, including IL-6, sTNFR2, IL-10, TGF-β, and TNF, were quantified using multiplexed bead-based immunoassay. Peripheral blood mononuclear cells (PBMC) from healthy donors were incubated with cell-free ascites for 48 h (or media as a negative control). In some experiments, IL-6 or TNF within the ascites were neutralized by using monoclonal antibodies. The phenotype of TNFR2+ Tregs and TNFR2− Tregs were characterized post incubation in ascites. In some experiments, cell sorted Tregs were utilized instead of PBMC.ResultsHigh levels of immunosuppressive (sTNFR2, IL-10, and TGF-β) and pro-inflammatory cytokines (IL-6 and TNF) were present in malignant ascites. TNFR2 expression on all T cell subsets was higher in post culture in ascites and highest on CD4+CD25hiFoxP3+ Tregs, resulting in an increased TNFR2+ Treg/effector T cell ratio. Furthermore, TNFR2+ Tregs conditioned in ascites expressed higher levels of the functional immunosuppressive molecules programmed cell death ligand-1, CTLA-4, and GARP. Functionally, TNFR2+ Treg frequency was inversely correlated with interferon-gamma (IFN-γ) production by effector T cells, and was uniquely able to suppress TNFR2+ T effectors. Blockade of IL-6, but not TNF, within ascites decreased TNFR2+ Treg frequency. Results indicating malignant ascites promotes TNFR2 expression, and increased suppressive Treg activity using PBMC were confirmed using purified Treg subsets.ConclusionIL-6 present in malignant ovarian cancer ascites promotes increased TNFR2 expression and frequency of highly suppressive Tregs.

Natural Compounds with Potential to Modulate Cancer Therapies and Self-Reactive Immune Cells

“…The data on effects of polyphenols on immune cells is increasing, especially in the context of cancer [130], with a lot of research understandably focusing on the effects on Tregs [131]. Modulating this cell type is especially important for ovarian cancer [132][133][134]. Curcumin can modulate Treg numbers and FoxP3 expression [135].…”

Lysophosphatidic acid induces tumor necrosis factor‐alpha to regulate a pro‐inflammatory cytokine network in ovarian cancer

“…[62][63][64][65][66][67] Many cytokines and chemokines including TNF-α, IL-6, IL-8, and CXCL1 are significantly increased in serum, ascites or tumor samples of ovarian cancer patients. [7][8][9][10]30 Biological studies have shown that both ovarian tumor cells and tumor-infiltrating immune cells contribute to elevated levels of TNF-α and other inflammatory mediators in ovarian tumors. 1,2,6 As a primary pro-inflammatory factor, TNF-α acts as an endogenous promoter of a variety of oncogenic processes such as cellular transformation, survival, proliferation, invasion, angiogenesis, and metastasis.…”

“…1 TNF-α and other inflammatory mediators were detected at elevated levels in the serum and ascites of ovarian cancer patients. [7][8][9][10] It is now well established that, in addition to host immune cells, ovarian tumor cells are a clinically relevant source of these elevated inflammatory cytokines in vivo.…”

Mesenchymal Stem/Stromal Cells Derived from Dental Tissues: A Comparative In Vitro Evaluation of Their Immunoregulatory Properties Against T cells

“…Several studies have shown that molecules, such as IL-10, IL-4, and PGE2, are involved in the induction of differentiation into regulatory T-cells [22,26,30]. Since we identified increased levels of these mediators in co-cultures with MSCs, which are related to the inhibition of CD4 + and CD8 + T- Similarly, PGE 2 is a molecule that decreases T-cell proliferation, stimulates the secretion of IL-4 and IL-10 and promotes T-cell differentiation toward lymphocytes with the regulatory phenotype CD4 + CD25 + Foxp3 + [29].…”

“…Several studies have shown that molecules, such as IL-10, IL-4, and PGE 2 , are involved in the induction of differentiation into regulatory T-cells [22,26,30]. Since we identified increased levels of these mediators in co-cultures with MSCs, which are related to the inhibition of CD4 + and CD8 + T-cell proliferation and an increased frequency of CD4 + CTLA-4 + cells, we assessed whether these findings were related to the generation of regulatory CD4 + CD25 + CTLA-4 + and/or CD4 + CD25 + Foxp3 + T-cells (Figure 6a-c).…”