Intracellular conversion and in vivo dose response of favipiravir (T-705) in rodents infected with Ebola virus

During the 2013-2016 Ebola virus (EBOV) outbreak in West Africa, our team at USAMRIID evaluated the antiviral activity of a number of compounds, including favipiravir (T-705), in vitro and in mouse and nonhuman primate (NHP) models of Ebola virus disease. In this short communication, we present our findings for favipiravir in cell culture and in mice, while an accompanying paper presents the results of NHP studies. We confirmed previous reports that favipiravir has anti-EBOV activity in mice. Additionally, we found that the active form of favipiravir is generated in mice in tissues relevant for the pathogenesis of EBOV infection. Finally, we observed that protection can be achieved in mice down to 8 mg/kg/day, which is lower than the dosing regimens previously reported. An accompanying paper reports the results of treating nonhuman primates infected with EBOV or with Marburg virus with oral or intravenous favipiravir.

Efficacy of favipiravir (T-705) in nonhuman primates infected with Ebola virus or Marburg virus

Favipiravir is a broad-spectrum antiviral agent that has demonstrated efficacy against Ebola virus (EBOV) in rodents. However, there are no published reports of favipiravir efficacy for filovirus infection of nonhuman primates (NHPs). Here we evaluated the pharmacokinetic profile of favipiravir in NHPs, as well as in vivo efficacy against two filoviruses, EBOV and Marburg virus (MARV). While no survival benefit was observed in two studies employing once- or twice-daily oral dosing of favipiravir during EBOV infection of NHPs, an antiviral effect was observed in terms of extended time-to-death and reduced levels of viral RNA. However, oral dosing in biosafety level-4 (BSL-4) presents logistical and technical challenges, and repeated anesthesia events may potentially worsen survival outcome in animals. For the third study of treatment of MARV infection, we therefore made use of catheters, jackets, and tethers for intravenous (IV) dosing and blood collection, which minimized the requirement for repeated anesthesia events. When MARV infection was treated with IV favipiravir, five of six animals (83%) survived infection, while all untreated NHPs succumbed. An accompanying report presents the results of favipiravir treatment of EBOV infection in mice.

A novel class of compounds with cutaneous wound healing properties

Impaired wound healing is a major complication underlying several disease processes (such as diabetes). Efficient wound healing is hampered by a wide variety of processes including hypoxia (oxygen deprivation), inflammation, infection, and oxidative stress through the generation of harmful reactive oxygen species (ROS). The inherent complexity of the healing wound has resulted in limited efficacy of most therapies that target single parameters involved in the slow healing processes. Fullerenes are carbon nanospheres previously shown to exhibit a wide range of biological activities. Given that these molecules have been shown to be potent anti-inflammatories and antioxidants we hypothesized that fullerenes could aid in wound healing based on these properties. We designed and synthesized a panel of fullerene derivatives and investigated their ability to accelerate wound healing using a modified scratch assay, an ex vivo human skin model, and a mouse model of skin irritation. Several derivatives supported cell migration, induced wound closure in human skin explants, and greatly accelerated the rate at which wound healing occurred in vivo. Therefore, fullerene derivatives represent a potential new class of wound healing therapies that may aid in wound healing treatment.

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 phorbol myristate acetate-induced inflammation

Inflammation is a natural biological response that occurs when vascular tissues are subjected to harmful stimuli. This process may be beneficial to the host during wound healing and infections but can be detrimental if left unchecked. Oxidative stress, the generation of reactive oxygen species, is thought to be one component of this response. Fullerenes can counteract reactive oxygen species due to their potent antioxidant capabilities. Thus, we hypothesized that these molecules may inhibit inflammation. To test this hypothesis we used an in vivo model of phorbol 12-myristate 13-acetate (PMA)-induced inflammation and examined the effects fullerenes have on mitigating this response. We show that PMA-induced inflammation and oedema is dramatically inhibited when fullerenes are given prior to challenge. Thus, fullerene derivatives may be a novel way to blunt certain inflammatory conditions and facilitate faster recovery of damaged tissue.

Abstract LB-383: In vitro and in vivo MRI evaluation of a novel metallofullerene nanoparticle

Some disadvantages of conventional small molecule contrast agents, such as Magnevist® (Gd - DTPA), are that they extravasate rapidly and are quickly eliminated from blood, limiting the viable MRI time. Macromolecular magnetic resonance imaging (MRI) contrast agents, on the other hand, are useful blood-pool agents and have found application in monitoring tumor vasculature and angiogenesis. There is an urgent need for new MRI contrast agents with higher relaxivity and longer blood half-life. Here, we report in vitro and in vivo characterization of a water-soluble derivatized fullerene nanoparticle contrast agent (NCL124) in comparison to the market standard, Magnevist. In comparison to Magnevist, NCL124 had higher R1and R2 relaxivities in human plasma at 22° C and 37°C. In vivo MRI imaging was performed on a LS174T dual-flank xenografts following a single intravenous injection of NCL 124 or Magnevist contrast agent (0.2 mmol Gd/Kg) using a 3.0 Tesla clinical whole-body MRI. Based on the relaxivity-time profiles, the Vss for NCL124 was similar to that of albumin (∼ 100 mL/Kg), suggesting high protein binding, while the Vss of Magnevist was similar to that of extracellular tissue water (∼200 mL/Kg), as expected for an extracellular diffusible tracer. NCL124 also had a longer blood half-life (∼ 100 min) than Magnevist (19 min). Taken together, the higher concentration (Cmax) and exposure (AUCall) of NCL124 in the blood, coupled with slow elimination, supports the use of NCL124 as a blood-pool contrast agent. Intriguingly, the half-life of NCL124 varied by tumor size, while Magnevist showed similar half-life in both tumors. This suggests NCL124 may have significant utility in predicting differences in tumor vascular and lymphatic permeability, and potentially be useful as a marker for antiangiogenic therapy. Funded by NCI contract # HHSN261200800001E.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-383.

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.

A Novel Nanomedicine Platform for Controlling Mast Cell Activation (36.14)

Mast cells play a critical role in the initiation and propagation of several inflammatory diseases and are well known for their function in the allergic response. Fullerenes are a class of novel carbon allotropes with a wide variety of applications in biotechnology and medicine. Here we use a fullerene-based chemistry platform to develop and test several different fullerene derivatives to evaluate on cellular viability, anti-IgE receptor-mediated degranulation, and cytokine release from human skin mast cells (MC). The biological response depended on the properties of the addition group; some fullerene structures were effective inhibitors of degranulation and also blocked cytokine release, while others were ineffective. None were toxic to the cells using concentrations up to 100 µg/ml. Further, we demonstrate that mitochondrial membrane potential (MMP) closely paralleled IgE-mediated SMC degranulatory responses and this response was greatly inhibited by fullerene pre-incubation. Additionally, the fullerene inhibition was due to the inhibition of FcεRI-mediated MAP kinase activation. These findings suggest the biological properties of fullerene derivatives depends on the derivatization of the carbon cage which can be manipulated to compounds which may control those diseases associated with MC activation.

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.

[Intra-orbital space occupying lesion. Differential diagnostic considerations based on a rare case]

The differential diagnosis of an intraorbital tumor is discussed on the basis of a rare case of cyst formation that presented clinically in the lacrimal duct. Rapid progression of exophthalmos and visual loss required an immediate surgical intervention. Using a medial orbitotomy, a cystic tumor was extirpated that had no connection to the paranasal sinuses. Postoperatively, the visual defect and exophthalmos resolved completely. This case demonstrates the problems of differential diagnosis within the orbit that require close interdisciplinary cooperation. The final diagnosis can often be made only after surgical exploration and histopathology of tissue specimens.

[Preliminary studies of the content of lead, cadmium and arsenic in feed, cattle and food of animal origin from different production regions of Saxony]

The modern industrial and agricultural production provides many contact points for the food animals with several toxic substances. After their ingestion by the way of feed or water they may endanger the human health as residues or environmental contaminants in food of animal origin. Currently meat, milk and eggs produced on farms in the new federal states of Germany are considered to be dangerous with respect to their xenobiotic burden by numerous consumers. The own trials have been made to give first information about lead, cadmium and arsenic concentrations in feedstuffs, meat and milk from different dairy farms in Saxonia. No serious problems could be detected referring to the metal contents in roughage, grain and crops. Only a few feed samples reached eg. exceeded the permissible upper limits for arsenic and cadmium. But none of the examined feedstuffs contained inadmissible lead concentration. Milk and muscle produced in a metal polluted and not polluted areas were very low in cadmium, lead and arsenic. Total different is the situation in the cases of liver and kidney. Both organs of cows held on farms near a smelter were rich in cadmium and lead. The cadmium concentration in liver and kidney often and the lead concentration sometimes exceeded the permissible upper limits for food. In this context cadmium in kidney of older cows seems to be a problem in general. The results of the own examinations give no information about differences in the mean metal burden of feed and food between new and old federal states of Germany.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of electrically charged drug molecules with phospholipid membranes

Model membranes (egg-yolk PC liposomes) were exposed to the cationic form of amphiphilic drugs. Microelectrophoresis was used to measure the change of the electrokinetic potential as a function of the drug concentration. By use of the Gouy-Chapman theory the surface potential and surface charge density were calculated. A theoretical model postulating a simple partition equilibrium of the charged drug molecules between the membrane and the aqueous phase in the vicinity of the membrane failed to describe the experimental results. Modification of the partition law by introducing a mechanism of saturation at high drug concentrations, however, resulted in concordance of model and experiment. Some parameters of the model can be used as a means of evaluating the efficiency of neuroactive drugs.

The cytoskeletal framework and poliovirus metabolism

The cytoskeletal framework prepared by detergent lysis of suspension-grown HeLa cells is compared to the structure obtained from poliovirus-infected cells. This framework, which retains major features of cell morphology and carries the cellular polyribosomes as well as the major structural filaments, is profoundly reorganized following virus infection. This reorganization underlies, at least in part, the morphological changes termed the "cytoplasmic effect." These cytoskeletal changes appear related to the involvement of the framework with viral-specific metabolism. Extensive cytoskeleton alterations occur even when guanidine inhibits viral replication, and thus result from small amounts of early viral products. The normally spheroidal nucleus deforms, allowing a modified region of the cytoplasm to occupy a central position in the cell, and many membrane-enclosed vesicles peculiar to the infected cell are elaborated here. The skeleton preparation reveals that this region contains intermediate filaments arranged in a pattern unique to infected cells. Further changes occur when viral replication is permitted. The central region filaments become coated with darkly staining material which may be viral RNA. Numerous small particles appear on the filaments which resemble partially assembled virions. Mature virions, however, have no affinity for the cytoskeleton and appear to be free in the cytoplasm. Host cell messenger RNA, normally attached to the skeletal framework, is released in infected cells and is replaced by the viral-specific polyribosomes. The trabecular network which carries polyribosomes appears to be rearranged; the viral polyribosomes are located principally at the cell periphery and are excluded from the central region. The viral replication complex with its double-stranded RNA is also attached to the skeletal framework and may comprise the dark staining material coating the filaments of the central cell region.

Messenger RNA abundance and lifetime: a correlation in Drosophila cells but not in HeLa

Messenger RNA in eukaryotes is comprised of several abundance classes. Also, the decay of these unstable molecules shows at least two very different lifetimes. Two independent techniques are used here to examine the relation between message abundance and lifetime in cell lines from very different organisms. The methods give consistent results for each cell line; however, the two cell types show very different results. In brosophile cells, slowly decaying sequences fall in the abundant class while scarce sequences turn over rapidly. In contrast, in HeLa cells the abundant and scarce message classes are each comprised of long- and short-lived molecules.

A cytoskeletal structure with associated polyribosomes obtained from HeLa cells

A method is described by which HeLa cells can be fractionated to reveal a skeletal-like structure in the cytoplasm. This cytoskeleton has many of the cell's ultrastructural features, such as 100A filaments, microfilaments, centrioles, and microspikes, although most of the cellular protein, membranes, and microtubules have been extracted. Associated with the cytoskeleton are most of the polysomal, but not the monomeric, ribosomes. These polysomes are distributed throughout the cytoskeleton except in the region of the 100A filaments, which resembles the distribution in intact cells. Degradation of mRNA with low levels of ribonuclease releases most ribosomes from the cytoskeleton. Prior disaggregation of polyribosomes in vivo releases ribosomes but not mRNA. Cytochalasin B administered in vivo releases the mRNA from the cytoskeleton. These results suggest an attachment of polyribosomes to the cytoskeleton via mRNA.