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Mechanisms of T-cell protection from death by IRX-2: a new immunotherapeutic.

ABSTRACT: IRX-2 is a novel immunotherapeutic containing physiologic quantities of several cytokines which protects human T lymphocytes from tumor-induced or drug-induced apoptosis. Here, we investigate the mechanisms responsible for IRX-2-mediated protection of T lymphocytes exposed to tumor-derived microvesicles (TMV).Jurkat cells or primary human T cells ± IRX-2 were co-incubated with TMV and then examined by flow cytometry or Western blots for expression of molecules regulating cell survival (FLIP, Bcl-2, Bcl-xL, Mcl-1) or death (Fas, caspase 8, caspase 9, Bax, Bid). ANX V binding, caspase activation or cytochrome c release were also measured ± cycloheximide (CHX) or ± the Akt-specific inhibitor. Jurkat cells transfected with the cFLIP gene were used to evaluate the role of cFLIP in IRX-2-mediated protection. Effects of CHX on IRX-2-mediated protection and activation of NF-?B upon the TMV/IRX-2 treatment were also measured.IRX-2 protected T cells from apoptosis by preventing Fas overexpression induced by TMV and blocking caspase 8 activation by up-regulating cFLIP. Jurkat cells overexpressing cFLIP were more resistant to TMV-induced apoptosis than the mock-transfected cells (p < 0.02). Signaling via the PI3K/Akt pathway, IRX-2 corrected the imbalance of pro- versus anti-apoptotic proteins induced by TMV and promoted NF-?B translocation to the nucleus. CHX abolished IRX-2-mediated protection in T cells, suggesting that IRX-2 induces de novo synthesis of one or more proteins that are required for protection.This biologic may be therapeutically useful for protection of activated T cells from tumor-induced immune suppression and death.

SUBMITTER: Czystowska M

PROVIDER: S-EPMC3708464 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Mechanisms of T-cell protection from death by IRX-2: a new immunotherapeutic.

Czystowska Malgorzata M Szczepanski Miroslaw J MJ Szajnik Marta M Quadrini Karen K Brandwein Harvey H Hadden John W JW Whiteside Theresa L TL

Cancer immunology, immunotherapy : CII 20101223 4

<h4>Objectives</h4>IRX-2 is a novel immunotherapeutic containing physiologic quantities of several cytokines which protects human T lymphocytes from tumor-induced or drug-induced apoptosis. Here, we investigate the mechanisms responsible for IRX-2-mediated protection of T lymphocytes exposed to tumor-derived microvesicles (TMV).<h4>Methods</h4>Jurkat cells or primary human T cells ± IRX-2 were co-incubated with TMV and then examined by flow cytometry or Western blots for expression of molecules ...[more]

PMID: 21181158

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Project description:OBJECTIVE:Alternative activation (M2) of adipose tissue resident macrophage (ATM) inhibits obesity-induced metabolic inflammation. The underlying mechanisms remain unclear. Recent studies have shown that dysregulated lipid homeostasis caused by increased lipolysis in white adipose tissue (WAT) in the obese state is a trigger of inflammatory responses. We investigated the role of M2 macrophages in lipotoxicity-induced inflammation. METHODS:We used microarray experiments to profile macrophage gene expression regulated by two M2 inducers, interleukin-4 (Il-4), and peroxisome proliferator-activated receptor delta/gamma (Ppar?/Ppar?) agonists. Functional validation studies were performed in bone marrow-derived macrophages and mice deprived of the signal transducer and activator of transcription 6 gene (Stat6; downstream effector of Il-4) or Ppar?/Ppar? genes (downstream effectors of Stat6). Palmitic acid (PA) and ?-adrenergic agonist were employed to induce macrophage lipid loading in vitro and in vivo, respectively. RESULTS:Profiling of genes regulated by Il-4 or Ppar?/Ppar? agonists reveals that alternative activation promotes the cell survival program, while inhibiting that of inflammation-related cell death. Deletion of Stat6 or Ppar?/Ppar? increases the susceptibility of macrophages to PA-induced cell death. NLR family pyrin domain containing 3 (Nlrp3) inflammasome activation by PA in the presence of lipopolysaccharide is also increased in Stat6-/- macrophages and to a lesser extent, in Ppar?/?-/- macrophages. In concert, ?-adrenergic agonist-induced lipolysis results in higher levels of cell death and inflammatory markers in ATMs derived from myeloid-specific Ppar?/?-/- or Stat6-/- mice. CONCLUSIONS:Our data suggest that ATM cell death is closely linked to metabolic inflammation. Within WAT where concentrations of free fatty acids fluctuate, M2 polarization regulated by the Stat6-Ppar axis enhances ATM's tolerance to lipid-mediated stress, thereby maintaining the homeostatic state.

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Mechanisms of T-cell protection from death by IRX-2: a new immunotherapeutic.

Publications

Mechanisms of T-cell protection from death by IRX-2: a new immunotherapeutic.

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