Epoxyeicosatrienoic acids are involved in the C(70) fullerene derivative-induced control of allergic asthma.

BACKGROUND: Fullerenes are molecules being investigated for a wide range of therapeutic applications. We have shown previously that certain fullerene derivatives (FDs) inhibit mast cell (MC) function in vitro, and here we examine their in vivo therapeutic effect on asthma, a disease in which MCs play a predominant role. OBJECTIVE: We sought to determine whether an efficient MC-stabilizing FD (C(70)-tetraglycolate [TGA]) can inhibit asthma pathogenesis in vivo and to examine its in vivo mechanism of action. METHODS: Asthma was induced in mice, and animals were treated intranasally with TGA either simultaneously with treatment or after induction of pathogenesis. The efficacy of TGA was determined through the measurement of airway inflammation, bronchoconstriction, serum IgE levels, and bronchoalveolar lavage fluid cytokine and eicosanoid levels. RESULTS: We found that TGA-treated mice have significantly reduced airway inflammation, eosinophilia, and bronchoconstriction. The TGA treatments are effective, even when given after disease is established. Moreover, we report a novel inhibitory mechanism because TGA stimulates the production of an anti-inflammatory P-450 eicosanoid metabolites (cis-epoxyeicosatrienoic acids [EETs]) in the lung. Inhibitors of these anti-inflammatory EETs reversed TGA inhibition. In human lung MCs incubated with TGA, there was a significant upregulation of CYP1B gene expression, and TGA also reduced IgE production from B cells. Lastly, MCs incubated with EET and challenged through FcεRI had a significant blunting of mediator release compared with nontreated cells. CONCLUSION: The inhibitory capabilities of TGA reported here suggest that FDs might be used a platform for developing treatments for asthma.

IL-4 and TGF-beta 1 counterbalance one another while regulating mast cell homeostasis.

Mast cell responses can be altered by cytokines, including those secreted by Th2 and regulatory T cells (Treg). Given the important role of mast cells in Th2-mediated inflammation and recent demonstrations of Treg-mast cell interactions, we examined the ability of IL-4 and TGF-beta1 to regulate mast cell homeostasis. Using in vitro and in vivo studies of mouse and human mast cells, we demonstrate that IL-4 suppresses TGF-beta1 receptor expression and signaling, and vice versa. In vitro studies demonstrated that IL-4 and TGF-beta1 had balancing effects on mast cell survival, migration, and FcepsilonRI expression, with each cytokine cancelling the effects of the other. However, in vivo analysis of peritoneal inflammation during Nippostrongylus brasiliensis infection in mice revealed a dominant suppressive function for TGF-beta1. These data support the existence of a cytokine network involving the Th2 cytokine IL-4 and the Treg cytokine TGF-beta1 that can regulate mast cell homeostasis. Dysregulation of this balance may impact allergic disease and be amenable to targeted therapy.

Uptake and distribution of fullerenes in human mast cells.

Fullerenes are carbon cages of variable size that can be derivatized with various side chain moieties resulting in compounds that are being developed into nanomedicines. Although fullerene use in several preclinical in vitro and in vivo models of disease has demonstrated their potential as diagnostic and therapeutic agents, little is known about how they enter cells, what organelles they target, and the time course for their cellular deposition. Fullerenes (C(70)) that have already been shown to be potent inhibitors of mast cell (MC)-mediated allergic inflammation were conjugated with Texas red (TR) and used in conjunction with confocal microscopy to determine mechanisms of uptake, the organelle localization, and the duration they can be detected in situ. We show that C(70)-TR are nonspecifically endocytosed into MCs, where they are shuttled throughout the cytoplasm, lysosomes, mitochondria, and into endoplasmic reticulum at different times. No nuclear or secretory granule localization was observed. The C(70)-TR remained detectable within cells at 1 week. These studies show that MCs endocytose fullerenes, where they are shuttled to organelles involved with calcium and reactive oxygen species production, which may explain their efficacy as cellular inhibitors. From the clinical editor: Fullerenes are carbon cages of variable size that have already been shown to be potent inhibitors of mast cell (MC)-mediated allergic inflammation. These were conjugated with Texas red (TR) and used in conjunction with confocal microscopy to determine mechanisms of uptake, the organelle localization, and duration, demonstrating that MCs endocytose fullerenes, which are shuttled to organelles involved with calcium and reactive oxygen species production. This intracellular trafficking may explain the efficacy of fullerenes as cellular inhibitors.

Myeloid-derived suppressor cells enhance IgE-mediated mast cell responses.

Mast cells and MDSCs are increased by parasitic infection and tumor growth. We previously demonstrated that enhanced MDSC development in ADAM10 transgenic mice yielded resistance to Nb infection and that coculturing MDSCs and mast cells enhanced cytokine production. In the current work, we show that MDSC-mast cell coculture selectively enhances IgE-mediated cytokine secretion among mast cells, without increasing MDSC cytokine production. This effect was independent of cell contact and elicited by Ly6C(+) and Ly6C/G+ MDSC subsets. These interactions were functionally important. MDSC depletion with the FDA-approved drug gemcitabine exacerbated Nb or Trichinella spiralis infection and reduced mast cell-dependent AHR and lung inflammation. Adoptive transfer of MDSC worsened AHR in WT but not mast cell-deficient Wsh/Wsh mice. These data support the hypothesis that MDSCs enhance mast cell inflammatory responses and demonstrate that this interaction can be altered by an existing chemotherapeutic.

A new class of human mast cell and peripheral blood basophil stabilizers that differentially control allergic mediator release.

Treatments for allergic disease block the effects of mediators released from activated mast cells and blood basophils. A panel of fullerene derivatives was synthesized and tested for their ability to preempt the release of allergic mediators in vitro and in vivo. The fullerene C(70)-tetraglycolic acid significantly inhibited degranulation and cytokine production from mast cells and basophils, while C(70)-tetrainositol blocked only cytokine production in mast cells and degranulation and cytokine production in basophils. The early phase of FcepsilonRI inhibition was dependent on the blunted release of intracellular calcium stores, elevations in reactive oxygen species, and several signaling molecules. Gene microarray studies further showed the two fullerene derivatives inhibited late phase responses in very different ways. C(70)-tetraglycolic acid was able to block mast cell-driven anaphylaxis in vivo, while C(70)-tetrainositol did not. No toxicity was observed with either compound. These findings demonstrate the biological effects of fullerenes critically depends on the moieties added to the carbon cage and suggest they act on different FcepsilonRI-specific molecules in mast cells and basophils. These next generation fullerene derivatives represent a new class of compounds that interfere with FcepsilonRI signaling pathways to stabilize mast cells and basophils. Thus, fullerene-based therapies may be a new approach for treating allergic diseases.

Fullerene nanomaterials inhibit the allergic response.

Fullerenes are a class of novel carbon allotropes that may have practical applications in biotechnology and medicine. Human mast cells (MC) and peripheral blood basophils are critical cells involved in the initiation and propagation of several inflammatory conditions, mainly type I hypersensitivity. We report an unanticipated role of fullerenes as a negative regulator of allergic mediator release that suppresses Ag-driven type I hypersensitivity. Human MC and peripheral blood basophils exhibited a significant inhibition of IgE dependent mediator release when preincubated with C(60) fullerenes. Protein microarray demonstrated that inhibition of mediator release involves profound reductions in the activation of signaling molecules involved in mediator release and oxidative stress. Follow-up studies demonstrated that the tyrosine phosphorylation of Syk was dramatically inhibited in Ag-challenged cells first incubated with fullerenes. In addition, fullerene preincubation significantly inhibited IgE-induced elevation in cytoplasmic reactive oxygen species levels. Furthermore, fullerenes prevented the in vivo release of histamine and drop in core body temperature in vivo using a MC-dependent model of anaphylaxis. These findings identify a new biological function for fullerenes and may represent a novel way to control MC-dependent diseases including asthma, inflammatory arthritis, heart disease, and multiple sclerosis.