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Updated: Aug 22, 2026
Isolation and Flow Cytometric Analysis of Glioma-infiltrating Peripheral Blood Mononuclear Cells
Published on: November 28, 2015
Induction of a CD4+ T regulatory type 1 response by cyclooxygenase-2-overexpressing glioma
Yasuharu Akasaki1, Gentao Liu, Nancy H C Chung
1Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
Abstract:
PGE(2), synthesized by cyclooxygenase-2 (COX-2)-overexpressing tumor, is known to contribute to cellular immune suppression in cancer patients, but the mechanism remains unclear. We report the mechanism of a CD4(+) T regulatory type 1 (Tr1) induction by CD11c(+) mature dendritic cells (DCs) that phagocytose allogeneic and autologous COX-2-overexpressing glioma. A human glioma cell line, U-87MG, and primary cultured glioblastoma cells (MG-377) overexpressed COX-2. We did not detect IL-10Ralpha expression in these gliomas, and rIL-10 did not suppress their COX-2 expression. Exposure to COX-2-overexpressing glioma induced mature DCs to overexpress IL-10 and decreased IL-12p70 production. These DCs induced a Tr1 response, which is characterized by robust secretion of IL-10 and TGF-beta with negligible IL-4 secretion by CD4(+) T cells, and an inhibitory effect on admixed lymphocytes. Peripheral CD4(+) T cell populations isolated from an MG-377 patient also predominantly demonstrated a Tr1 response against MG-377 cells. Selective COX-2 inhibition in COX-2-overexpressing gliomas at the time of phagocytic uptake by DCs abrogated this regulatory response and instead elicited Th1 activity. COX-2 stable transfectants in LN-18 (LN-18-COX2) also induced a Tr1 response. The effect of a COX-2 inhibition in LN-18-COX2 is reversible after administration of PGE(2). Taken together, robust levels of PGE(2) from COX-2-overexpressing glioma, which is unresponsive to IL-10 within the local microenvironment, may cause DCs to secrete high levels of IL-10. These results indicate that COX-2-overexpressing tumors induce a Tr1 response, which is mediated by tumor-exposed, IL-10-enhanced DCs.
Insights
Cyclooxygenase-2 (COX-2) in gliomas promotes immune suppression by inducing regulatory type 1 (Tr1) cells via dendritic cells (DCs). Inhibiting COX-2 reverses this, promoting anti-tumor T-helper 1 (Th1) activity.
Area of Science:
- Immunology
- Oncology
- Molecular Biology
Background:
- Tumor-associated cyclooxygenase-2 (COX-2) contributes to immune suppression in cancer.
- The precise mechanism by which COX-2 induces immune evasion in glioma remains incompletely understood.
- Dendritic cells (DCs) play a crucial role in modulating T-cell responses in the tumor microenvironment.
Purpose of the Study:
- To elucidate the mechanism by which COX-2-overexpressing gliomas induce immune suppression.
- To investigate the role of dendritic cells (DCs) in mediating the immunosuppressive effects of glioma.
- To determine the potential of targeting COX-2 to restore anti-tumor immunity.
Main Methods:
- Co-culture of human glioma cell lines and primary glioblastoma cells with mature dendritic cells (DCs).
- Analysis of cytokine production (IL-10, IL-12p70, TGF-beta, IL-4) by DCs and CD4+ T cells.
- Assessment of T-regulatory type 1 (Tr1) cell induction and functional assays on T-cell proliferation.
- Pharmacological inhibition of COX-2 in glioma cells and evaluation of its impact on DC and T-cell responses.
Main Results:
- Exposure to COX-2-overexpressing glioma induced mature DCs to produce high levels of IL-10 and reduced IL-12p70.
- These DCs promoted the development of CD4+ T regulatory type 1 (Tr1) cells, characterized by IL-10 and TGF-beta secretion.
- Tr1 cells exhibited immunosuppressive activity, inhibiting the proliferation of other lymphocytes.
- Selective COX-2 inhibition in gliomas abrogated Tr1 induction and promoted T-helper 1 (Th1) activity.
Conclusions:
- COX-2-overexpressing gliomas induce a potent immunosuppressive Tr1 response mediated by IL-10-producing dendritic cells.
- Prostaglandin E2 (PGE(2)), synthesized by COX-2, is a key driver of this DC-mediated Tr1 induction.
- Targeting COX-2 represents a viable strategy to overcome glioma-induced immune suppression and enhance anti-tumor immunity.
