Antigen-presenting cells transfected with Hsp65 messenger RNA fail to treat experimental tuberculosis

In the last several years, the use of dendritic cells has been studied as a therapeutic strategy against tumors. Dendritic cells can be pulsed with peptides or full-length protein, or they can be transfected with DNA or RNA. However, comparative studies suggest that transfecting dendritic cells with messenger RNA (mRNA) is superior to other antigen-loading techniques in generating immunocompetent dendritic cells. In the present study, we evaluated a new therapeutic strategy to fight tuberculosis using dendritic cells and macrophages transfected with Hsp65 mRNA. First, we demonstrated that antigen-presenting cells transfected with Hsp65 mRNA exhibit a higher level of expression of co-stimulatory molecules, suggesting that Hsp65 mRNA has immunostimulatory properties. We also demonstrated that spleen cells obtained from animals immunized with mock and Hsp65 mRNA-transfected dendritic cells were able to generate a mixed Th1/Th2 response with production not only of IFN-γ but also of IL-5 and IL-10. In contrast, cells recovered from mice immunized with Hsp65 mRNA-transfected macrophages were able to produce only IL-5. When mice were infected with Mycobacterium tuberculosis and treated with antigen-presenting cells transfected with Hsp65 mRNA (therapeutic immunization), we did not detect any decrease in the lung bacterial load or any preservation of the lung parenchyma, indicating the inability of transfected cells to confer curative effects against tuberculosis. In spite of the lack of therapeutic efficacy, this study reports for the first time the use of antigen-presenting cells transfected with mRNA in experimental tuberculosis

Toxicogenomic effects of nano- and bulk-TiO2 particles in the soil nematode Caenorhabditis elegans

The toxicity and toxicogenomics of selected anatase and rutile nanoparticles (NP) and bulk titanium dioxide (TiO2) particles were evaluated in the soil nematode Caenorhabditis elegans. Results indicated that bulk or nano-TiO2 particles were slightly toxic to soil nematode C. elegans, as measured by reproduction EC50 values ranging from 4 to 32\u2009mg/L. Whole-genome microarray results indicated that the regulation of glutathione-S-transferase gst-3, cytochrome P450 cypp33-c11, stress resistance regulator scl-1, oxidoreductase wah-1 and embryonic development pod-2 genes were significantly affected by nano-sized and bulk-TiO2 particles. More specifically, it was determined that anatase particles exerted a greater effect on metabolic pathways, whereas rutile particles had a greater effect on developmental processes. The up-regulation of the pod-2 gene corroborated the phenotypic effect observed in the reproduction test. Our results demonstrated that C. elegans is a good genomic model for nano-TiO2 toxicity assessment.Peer reviewed: YesNRC publication: Ye

Assessment of a sewage sludge treatment on cadmium, copper and zinc bioavailability in barley, ryegrass and earthworms

The toxicity and bioavailability of metals were assessed to verify the efficiency of a new chemical leaching process (METIX-AC) to minimizethe risk of metals found in municipal sewage sludge. For this purpose, sludge samples were spiked with cadmium, copper and/or zincbefore being treated using METIX-AC. The sludge decontamination resulted in a removal of spiked metals (79e89%), in a decrease of themore labile fractions, and in a corresponding increase of the residual fraction. The toxicity observed after exposure of two plant species, barley(Hordeum vulgare) and ryegrass (Lolium perenne), and a terrestrial invertebrate, Eisenia andrei, to sludge-soil mixtures, disappeared after treatment, although the adverse effects were minor before treatment. The sludge treatment also significantly decreased the bioaccumulation of cadmium, copper, and zinc in the exposed species. For cadmium, maximum tissue concentrations of 0.45 0.08 mg/kg in barley, 0.79 0.27 mg/kg in ryegrass, and 21.82 1.85 mg/kg in earthworm exposed to sludge before treatment decreased after treatment to values similar to thoseobserved with negative controls.NRC publication: Ye

Preliminary ecotoxicological characterization of a new energetic substance, CL-20

A new energetic substance hexanitrohexaazaisowurtzitane (or CL-20) was tested for its toxicities to various ecological receptors. CL-20 (epsilon-polymorph) was amended to soil or deionized water to construct concentration gradients. Results of Microtox (15-min contact) and 96-h algae growth inhibition tests indicate that CL-20 showed no adverse effects on the bioluminescence of marine bacteria Vibrio fischeri and the cell density of freshwater green algae Selenastrum capricornutum respectively, up to its water solubility (ca. 3.6 mg 1-1). CL-20 and its possible biotransformation products did not inhibit seed germination and early seedling (16-19 d) growth of alfalfa (Medicago sativa) and perennial ryegrass (Lolium perenne) up to 10 000 mg kg-1 in a Sassafras sandy loam soil (SSL). Indigenous soil microorganisms in SSL and a garden soil were exposed to CL-20 for one or two weeks before dehydrogenase activity (DHA) or potential nitrification activity (PNA) were assayed. Results indicate that up to 10 000 mg kg-1 soil of CL-20 had no statistically significant effects on microbial communities measured as DHA or on the ammonium oxidizing bacteria determined as PNA in both soils. Data indicates that CL-20 was not acutely toxic to the species or microbial communities tested and that further studies are required to address the potential long-term environmental impact of CL-20 and its possible degradation products. Crown Copyright Copyright 2004 Published by Elsevier Ltd. All rights reserved.NRC publication: Ye

Ecotoxicity of canola and tallow biodiesel blends to selected soil organisms

In view of depleting fossil fuel resources and environmental concern, biodiesel couldpotentially replace petroleum-derived diesel. Aquatic toxicity of diesel and biodiesel has beenextensively studied over the past decades but little is still known about their toxicity in soilenvironment. The scope of this study was to evaluate the environmental impact of biodiesel,biodiesel blends and petroleum diesel in soil using direct contact toxicity assays. The selectedbiodiesels included canola-source biodiesel (B100 and B20). and tallow-source biodiesel (B100and B20), which were compared to petroleum ultra-low-sulfur based diesel (ULSD). Selectedstandard terrestrial toxicity tests included ryegrass Lolium perenne seedling emergence andgrowth, earthworm Eisenia fetida survival, and soil microbial dehydrogenase activity. Soilcharacterization included the quantification of total extractable materials (corresponding to the n-alkane range of C10-C34). Preliminary results indicate that: 1) canola and tallow B20 biodieselblends were less toxic to earthworm than ULSD; 2) canola and tallow B20 blends had similartoxic effects to ryegrass as ULSD; and 3) petroleum ULSD inhibited the DHA activity at allconcentrations tested, and B20 canola biodiesel had a deleterious effect on the DHA activity atthe lowest nominal loadings tested (1 and 10 ml/kg dry soil). Therefore, this study providesuseful toxicological data for the evaluation of potential adverse impact of biodiesel in theenvironment, such as an accidental release or spill. This project was funded by EnvironmentCanada and Natural Resources Canada and is part of the Advanced Fuels and Technologies forEmissions Reduction (AFTER) Program for energy research and development (PERD).NRC publication: Ye

Toxicity and uptake of cyclic nitramine explosives in ryegrass Lolium perenne

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) are cyclic nitramines used as explosives. Their ecotoxicities have been characterized incompletely and little is known about their accumulation potential in soil organisms. We assessed the toxicity and uptake of these explosives in perennial ryegrass Lolium perenne L. exposed in a Sassafras sandy loam (SSL) or in a sandy soil (DRDC, CL-20 only) containing contrasting clay contents (11% and 0.3%, respectively). A 21-d exposure to RDX, HMX or CL-20 in either soil had no adverse effects on ryegrass growth. RDX and HMX were translocated to ryegrass shoots, with bioconcentration factors (BCF) of up to 15 and 11, respectively. In contrast, CL-20 was taken up by the roots (BCF up to 19) with no translocation to the shoots. These studies showed that RDX, HMX, and CL-20 can accumulate in plants and may potentially pose a risk of biomagnification across the food chain.NRC publication: Ye