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: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.
Project description:A fine regulation of epithelia cell death is required to maintain tissue integrity and homeostasis. At a cellular level, this life and death decision is controlled by environmental stimuli including death receptors activation. Here, we show that establishment of cell polarity and AJ formation control the pro-apoptotic signaling emanating from the death receptor Fas. We demonstrate that in colon epithelia Fas concentrates at cell-cell junctions together with the E-cadherin, which protects cells from FasL-induced cell death. The Fas-cadherin association requires the C terminal PDZ binding site of Fas and, using a proteomic approach, we showed that this domain allows the association with the polarity molecule Dlg1. We proved that the interaction of Fas with this scaffold molecule participate to this cell death protection. Therefore inhibition of FasL-induced cell death by Fas-cadherin-Dlg1 complex is a double-edged sword mechanism that helps to maintain epithelial homeostasis by (i) protecting normal polarized epithelia from apoptosis (ii) promoting the elimination of compromised non-polarized cells.
Project description:Fas ligand (FasL)/TNFSF6, a member of the tumor necrosis factor (TNF) superfamily, can promote apoptosis in activated primary B cells, T cells, dendritic cells, and synovial fibroblasts through Fas and is involved in the pathogenesis of autoimmune diseases including rheumatoid arthritis (RA). Meanwhile, decoy receptor 3 (DcR3) competitively binds soluble FasL in addition to TL1A and LIGHT and inhibits the signaling of FasL via Fas. Therefore, FasL-DcR3/Fas signaling may be involved in the pathogenesis of RA. We hypothesized that FasL regulates the gene expression in RA-FLS. We used to search for genes in which expression in RA-FLS is regulated by FasL.
Project description:Interferon (IFN)γ and interleukin (IL)-4 are central regulators of T helper 1 (Th1) and T helper 2 (Th2) immune responses, respectively. Both cytokines have a major impact on macrophage phenotypes: IFNγ–priming and subsequent TLR4 activation induces so called classically activated macrophages that are characterized by pronounced pro-inflammatory responses, whereas IL-4–treated macrophages, commonly called alternatively activated, are known to develop enhanced capacity for endocytosis, antigen presentation, and tissue repair and are generally considered anti-inflammatory. Considering IL-4 as priming rather than activating stimulus, we now compared the TLR4–dependent global gene activation program in IFNγ– versus IL-4–pretreated mouse macrophages, which has rarely been studied so far. Although both cytokines frequently induced opposing effects on gene transcription, the subsequent activation of bone marrow-derived macrophages by lipopolysaccharide (LPS) produced a strong, priming dependent pro-inflammatory response in both macrophage types. For example, the production of key pro-inflammatory cytokines IL-6 and IL-12 was significantly higher in IL-4– versus IFNγ–primed macrophages and several cytokine genes, including Il19, Ccl17, Ccl22, Ccl24 and Cxcl5, were preferentially induced in alternatively primed and LPS activated mouse macrophages. In a subset of genes, including IL12a, IFNγ priming was actually found to suppress LPS–induced gene expression in a Stat1–dependent manner. Our data suggest that IL-4–priming is not per se anti-inflammatory but generates a macrophage that is “tissue protective” but still capable of mounting a strong inflammatory response after TLR4–dependent activation. Keywords: Gene expression profiling Gene expression was investigated in mouse bone marrow-derived macrophages (BMM). On day 7, BMM were stimulated with either IL-4 or IFNγ overnight (18h in total). LPS treatment was performed in primed and unprimed macrophages 4 h prior to harvesting. At least three independent experiments were performed for each condition.
Project description:In areas endemic for schistosomiasis, repeated exposure to infective cercariae is a frequent occurrence, and repeated exposure of murine skin to Schistosoma mansoni resulted in CD4+ T cells becoming hypo-responsive. Here potential contributory mechanisms were investigated. In the skin infection site, three mononuclear phagocyte populations were identified (tissue macrophages, dendritic cells, and macrophages) which exhibited up-regulation of genes associated with alternative activation, in particular the gene encoding RELMα. However, in repeatedly infected mice deficient in RELMα, there was no change in the abundance of mononuclear phagocytes in the skin, and CD4+ cells in the skin draining lymph nodes remained hypo-responsive. In mice deficient for IL-4Rα, required for alternative activation, levels of dermal regulatory IL-10 were reduced and there was an increase in the abundance of antigen presenting MHC-IIhigh cells, which was accompanied by increased numbers of CD4+ T cells. Although the absence of IL-4Rα did not translate into increased CD4+ cell responsiveness, they exhibited lower expression of Fas/FasL, resulting in decreased apoptosis/cell death and increased cell viability. This study highlights a mechanism through which IL-4Rα may regulate the immune system through the induction of IL-10 and regulation of Fas/FasL mediated cell death. Mice were infected 1x or 4x with S. mansoni cercariae via the pinnae. Pinnae were harvested 4 days after the final infection and the DEC obtained after an overnight culture in vitro. Cells were then stained with F4/80 APC and MHC-II PE and four different populations sorted (using the MoFlo or the Astrios) based on their expression profiles. Several mice (12-18) from each group were pooled to generate each replicate.
Project description:Webb2002 - Fas/FasL mediated tumor T-cell interaction
This deterministic model of
immunological surveillance involving tumour cell–T-lymphocyte
interaction, cell surface expression of Fas/FasL, and their
secreted soluble forms.
This model is described in the article:
Cells behaving badly: a
theoretical model for the Fas/FasL system in tumour
immunology.
Webb SD, Sherratt JA, Fish RG.
Math Biosci 2002 Sep-Oct; 179(2):
113-129
Abstract:
One proposed mechanism of tumour escape from immune
surveillance is tumour up-regulation of the cell surface ligand
FasL, which can lead to apoptosis of Fas receptor (Fas)
positive lymphocytes. Based upon this 'counterattack', we have
developed a mathematical model involving tumour cell-lymphocyte
interaction, cell surface expression of Fas/FasL, and their
secreted soluble forms. The model predicts that (a) the
production of soluble forms of Fas and FasL will lead to the
down-regulation of the immune response; (b) matrix
metalloproteinase (MMP) inactivation should lead to increased
membrane FasL and result in a higher rate of Fas-mediated
apoptosis for lymphocytes than for tumour cells. Recent studies
on cancer patients lend support for these predictions. The
clinical implications are two-fold. Firstly, the use of broad
spectrum MMP inhibitors as anti-angiogenic agents may be
compromised by their adverse effect on tumour FasL
up-regulation. Also, Fas/FasL interactions may have an impact
on the outcome of numerous ongoing immunotherapeutic trials
since the final common pathway of all these approaches is the
transduction of death signals within the tumour cell.
This model is hosted on
BioModels Database
and identified by:
BIOMD0000000661.
To cite BioModels Database, please use:
Chelliah V et al. BioModels: ten-year
anniversary. Nucl. Acids Res. 2015, 43(Database
issue):D542-8.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
Project description:Some unicellular organisms exhibit collective decision-making through intercellular communication once a quorum of members sense an environmental stress. Whether T cells at different states of differentiation may also synchronize their behavior on a population basis through direct interactions remains unclear. We report that memory CD8+ T cells (TMem) directly interact with naive T cells (TN) during priming, affecting the phenotypic, functional, transcriptional and metabolic differentiation of TN-derived progeny. This previously unrecognized, contact and concentration-dependent interaction between naive (TN) and memory CD8+ T cells (TMem) directly enhanced TN effector differentiation through non-apoptotic Fas signaling resulting in downstream Akt pathway activation. TN primed with TMem exhibited significantly impaired persistence and antitumor activity compared with TN primed alone. Disruption of FasL-Fas signaling in TN cells limited differentiation and enhanced anti-tumor immunity while provision of exogenous FasL in the absence of TMem impaired anti-tumor immunity by augmenting TN differentiation. These findings reveal that the full therapeutic potential of TN-derived cells for adoptive immunotherapy requires physical separation from TMem prior to priming or antagonism of Fas-signaling.
Project description:In areas endemic for schistosomiasis, repeated exposure to infective cercariae is a frequent occurrence, and repeated exposure of murine skin to Schistosoma mansoni resulted in CD4+ T cells becoming hypo-responsive. Here potential contributory mechanisms were investigated. In the skin infection site, three mononuclear phagocyte populations were identified (tissue macrophages, dendritic cells, and macrophages) which exhibited up-regulation of genes associated with alternative activation, in particular the gene encoding RELMα. However, in repeatedly infected mice deficient in RELMα, there was no change in the abundance of mononuclear phagocytes in the skin, and CD4+ cells in the skin draining lymph nodes remained hypo-responsive. In mice deficient for IL-4Rα, required for alternative activation, levels of dermal regulatory IL-10 were reduced and there was an increase in the abundance of antigen presenting MHC-IIhigh cells, which was accompanied by increased numbers of CD4+ T cells. Although the absence of IL-4Rα did not translate into increased CD4+ cell responsiveness, they exhibited lower expression of Fas/FasL, resulting in decreased apoptosis/cell death and increased cell viability. This study highlights a mechanism through which IL-4Rα may regulate the immune system through the induction of IL-10 and regulation of Fas/FasL mediated cell death.
Project description:Human mutations in the death receptor Fas or its ligand FasL cause autoimmune lymphoproliferative syndrome (ALPS), whereas mutations in caspase-8 or its adaptor FADD â which mediate cell death downstream of Fas/FasL â cause severe immunodeficiency in addition to ALPS. Mouse models have corroborated a role for FADD-caspase-8 in promoting inflammatory responses, but the mechanisms underlying immunodeficiency remain undefined. Here, we identify NEDD4-binding protein 1 (N4BP1) as a suppressor of cytokine production that is cleaved and inactivated by caspase-8. N4BP1 deletion in mice significantly increased production of select cytokines upon Toll-like receptor (TLR) 1/2, TLR7, or TLR9 stimulation, but not upon TLR3 or TLR4 engagement. N4BP1 did not suppress TLR3 or TLR4 responses in wild-type macrophages owing to TRIF- and caspase-8-dependent cleavage of N4BP1. Notably, impaired TLR3 and TLR4 cytokine responses of caspase-8-deficient macrophages were largely rescued by co-deletion of N4BP1. Thus, persistence of intact N4BP1 in caspase-8-deficient macrophages impairs their ability to mount robust cytokine responses. Tumor necrosis factor (TNF), like TLR3 or TLR4 agonists, also induced caspase-8-dependent cleavage of N4BP1, thereby licensing TRIF-independent TLRs to produce higher levels of inflammatory cytokines. Illustrating the importance of this function of TNF in vivo, TNF blockade increased the mortality of mice infected with Streptococcus Pneumoniae, but did not do so when infected mice lacked N4BP1. Collectively, our results identify N4BP1 as a potent suppressor of cytokine responses; reveal N4BP1 cleavage by Caspase-8 as a point of signal integration during inflammation; and offer an explanation for immunodeficiency caused by FADD-caspase-8 mutations.