Dataset Information

Splenectomy promotes indirect elimination of intraocular tumors by CD8+ T cells that is associated with IFN?- and Fas/FasL-dependent activation of intratumoral macrophages.

ABSTRACT: Ocular immune privilege (IP) limits the immune surveillance of intraocular tumors as certain immunogenic tumor cell lines (P815, E.G7-OVA) that are rejected when transplanted in the skin grow progressively when placed in the anterior chamber of the eye. As splenectomy (SPLNX) is known to terminate ocular IP, we characterized the immune mechanisms responsible for rejection of intraocular tumors in SPLNX mice as a first step toward identifying how to restore tumoricidal activity within the eye. CD8(+) T cells, IFN?, and FasL, but not perforin, or TNF? were required for the elimination of intraocular E.G7-OVA tumors that culminated in destruction of the eye (ocular phthisis). IFN? and FasL did not target tumor cells directly as the majority of SPLNX IFN?R1(-/-) mice and Fas-defective lpr mice failed to eliminate intraocular E.G7-OVA tumors that expressed Fas and IFN?R1. Bone marrow chimeras revealed that IFN?R1 and Fas expression on immune cells was most critical for rejection, and SPLNX increased the frequency of activated macrophages (M?) within intraocular tumors in an IFN?- and Fas/FasL-dependent manner, suggesting an immune cell target of IFN? and Fas. As depletion of M?s limited CD8 T cell-mediated rejection of intraocular tumors in SPLNX mice, our data support a model in which IFN?- and Fas/FasL-dependent activation of intratumoral M?s by CD8(+) T cells promotes severe intraocular inflammation that indirectly eliminates intraocular tumors by inducing phthisis, and suggests that immunosuppressive mechanisms that maintain ocular IP interfere with the interaction between CD8(+) T cells and M?s to limit the immunosurveillance of intraocular tumors.

SUBMITTER: Miller MR

PROVIDER: S-EPMC4258428 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Splenectomy promotes indirect elimination of intraocular tumors by CD8+ T cells that is associated with IFNγ- and Fas/FasL-dependent activation of intratumoral macrophages.

Miller Maxine R MR Mandell Jonathan B JB Beatty Kelly M KM Harvey Stephen A K SA Rizzo Michael J MJ Previte Dana M DM Thorne Stephen H SH McKenna Kyle C KC

Cancer immunology research 20140923 12

Ocular immune privilege (IP) limits the immune surveillance of intraocular tumors as certain immunogenic tumor cell lines (P815, E.G7-OVA) that are rejected when transplanted in the skin grow progressively when placed in the anterior chamber of the eye. As splenectomy (SPLNX) is known to terminate ocular IP, we characterized the immune mechanisms responsible for rejection of intraocular tumors in SPLNX mice as a first step toward identifying how to restore tumoricidal activity within the eye. CD ...[more]

PMID: 25248763

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Project description:Ocular immune privilege (IP) limits immune surveillance of intraocular tumors as certain immunogenic tumor cell lines (P815, E.G7-OVA) that are rejected when transplanted in the skin grow progressively when placed in the anterior chamber (a.c.) of the eye. As splenectomy (SPLNX) is known to terminate ocular IP, we characterized immune mechanisms responsible for spontaneous rejection of intraocular tumors in SPLNX mice as a first step toward identifying how to restore tumoricidal activity within the eye. Microarray data showed a 3-fold increase in interferon (IFN)-γ and a 2.7-fold increase in Fas ligand (FasL). There was a robust increase in transcripts (127 of 408 surveyed) from interferon (IFN)-stimulated genes and a marked decrease (in 40 of 192 surveyed) in the expression of cell-cycle-associated genes. Non-microarray data confirmed that IFNγ, FasL and CD8+ T cells but not perforin or TNFα were required for elimination of intraocular E.G7-OVA tumors that culminated in destruction of the eye (ocular phthsis). IFNγ and FasL did not target tumor cells directly as the majority of SPLNX IFNγR1-/- mice and Fas-defective lpr mice failed to eliminate ocular E.G7-OVA tumors that expressed Fas and IFNγR1. Bone marrow chimeras showed that immune cell expression of IFNγR1 and Fas was critical and that SPLNX increased the frequency of activated macrophages within ocular tumors in an IFNγ- and Fas/FasL-dependent manner. Rejection of intraocular tumors was associated with increased ocular mRNA expression of several inflammatory genes including FasL, NOS2, CXCL2 and T-bet. Our data support a model in which IFNγ- and Fas/FasL-dependent activation of intratumoral macrophage by CD8+ T cells promotes severe intraocular inflammation that indirectly eliminates intraocular tumors by inducing phthisis. The immunosuppressive mechanisms which maintain ocular IP likely interfere with the interaction between CD8+ T cells and macrophage to limit immunosurveillance of intraocular tumors. C57BL/6 mice that were splenectomized (Tumor_splnx) or were not surgically manipulated (Tumor_intact) were challenged with 10^4 luciferase-expressing E.G7-OVA cells injected into the anterior chamber of the eye. Fifteen days later, the animals were euthanized and tumor-bearing eyes were removed.

Project description:The uncarboxylated form of osteocalcin (GluOC) regulates glucose and lipid metabolism in mice. We previously showed that low-dose (?10?ng/ml) GluOC induces the expression of adiponectin and peroxisome proliferator-activated receptor ? (PPAR?) via a cAMP-PKA-ERK-CREB signaling pathway in 3T3-L1 adipocytes. We also noticed that high-dose (?20?ng/ml) GluOC inhibits the expression of adiponectin and PPAR? in these cells. We have here explored the mechanism underlying these effects of high-dose GluOC. High-dose GluOC triggered morphological changes in 3T3-L1 adipocytes suggestive of the induction of cell death. It activated the putative GluOC receptor GPRC6A and thereby induced the production of cAMP and activation of protein kinase A (PKA), similar to signaling by low-dose GluOC with the exception that the catalytic subunit of PKA also entered the nucleus. Cytosolic PKA induced phosphorylation of cAMP response element-binding protein (CREB) at serine-133 via extracellular signal-regulated kinase (ERK). Nuclear PKA appeared to mediate the inhibitory phosphorylation of salt-inducible kinase 2 (SIK2) at serine-358 and thereby to alleviate the inhibitory phosphorylation of the CREB co-activator p300 at serine-89. The activation of CREB and p300 resulted in increased expression of the transcription factor FoxO1 and consequent upregulation of Fas ligand (FasL) at the plasma membrane. The interaction of FasL with Fas on neighboring adipocytes triggered the phosphorylation at threonine-357/serine-358 and homotrimerization of mixed-lineage kinase domain-like protein (MLKL), a key regulator of necroptosis, as well as Ca2+ influx via transient receptor potential melastatin 7 (TRPM7), the generation of reactive oxygen species and lipid peroxides, and dephosphorylation of dynamin-related protein 1 (DRP1) at serine-637, resulting in mitochondrial fragmentation. Together, our results indicate that high-dose GluOC triggers necroptosis through upregulation of FasL at the plasma membrane in a manner dependent of activation of CREB-p300, followed by the activation of Fas signaling in neighboring adipocytes.

Dataset Information

Splenectomy promotes indirect elimination of intraocular tumors by CD8+ T cells that is associated with IFN?- and Fas/FasL-dependent activation of intratumoral macrophages.

Publications

Splenectomy promotes indirect elimination of intraocular tumors by CD8+ T cells that is associated with IFNγ- and Fas/FasL-dependent activation of intratumoral macrophages.

Similar Datasets

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