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Porter DW, Orandle MS, Hubbs A, Staska LM, Lowry D, Kashon M, Wolfarth MG, McKinney W, Sargent LM. Potent lung tumor promotion by inhaled MWCNT. Nanotoxicology 2024; 18:69-86. [PMID: 38420937 PMCID: PMC11057902 DOI: 10.1080/17435390.2024.2314473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/30/2024] [Indexed: 03/02/2024]
Abstract
In the lung, carcinogenesis is a multi-stage process that includes initiation by a genotoxic agent, promotion that expands the population of cells with damaged DNA to form a tumor, and progression from benign to malignant neoplasms. We have previously shown that Mitsui-7, a long and rigid multi-walled carbon nanotube (MWCNT), promotes pulmonary carcinogenesis in a mouse model. To investigate the potential exposure threshold and dose-response for tumor promotion by this MWCNT, 3-methylcholanthrene (MC) initiated (10 μg/g, i.p., once) or vehicle (corn oil) treated B6C3F1 mice were exposed by inhalation to filtered air or MWCNT (5 mg/m3) for 5 h/day for 0, 2, 5, or 10 days and were followed for 17 months post-exposure for evidence of lung tumors. Pulmonary neoplasia incidence in MC-initiated mice significantly increased with each MWCNT exposure duration. Exposure to either MC or MWCNT alone did not affect pulmonary neoplasia incidence compared with vehicle controls. Lung tumor multiplicity in MC-initiated mice also significantly increased with each MWCNT exposure duration. Thus, a significantly higher lung tumor multiplicity was observed after a 10-day MWCNT exposure than following a 2-day exposure. Both bronchioloalveolar adenoma and bronchioloalveolar adenocarcinoma multiplicity in MC-initiated mice were significantly increased following 5- and 10-day MWCNT exposure, while a 2-day MWCNT exposure in MC-initiated mice significantly increased the multiplicity of adenomas but not adenocarcinomas. In this study, even the lowest MWCNT exposure promoted lung tumors in MC-initiated mice. Our findings indicate that exposure to this MWCNT strongly promotes pulmonary carcinogenesis.
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Affiliation(s)
- Dale W Porter
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Marlene S Orandle
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Ann Hubbs
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | | | - David Lowry
- Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Michael Kashon
- Bioanalytics Branch, Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Michael G Wolfarth
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Walter McKinney
- Physical Effects Research Branch, Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Linda M Sargent
- Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
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Frawley RP, Smith MJ, White KL, Elmore SA, Herbert R, Moore R, Staska LM, Behl M, Hooth MJ, Kissling GE, Germolec DR. Immunotoxic effects of sodium tungstate dihydrate on female B6C3F1/N mice when administered in drinking water. J Immunotoxicol 2016; 13:666-75. [PMID: 27223060 DOI: 10.3109/1547691x.2016.1154118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Tungsten is a naturally occurring, high-tensile strength element that has been used in a number of consumer products. Tungsten has been detected in soil, waterways, groundwater, and human tissue and body fluids. Elevated levels of tungsten in urine were reported for populations exposed to tungstate in drinking water in areas where natural tungsten formations were prevalent. Published reports indicated that sodium tungstate may modulate hematopoiesis, immune cell populations, and immune responses in rodent models. The objective of this study was to assess potential immunotoxicity of sodium tungstate dihydrate (STD), a drinking water contaminant. Female B6C3F1/N mice received 0-2000 mg STD/L in their drinking water for 28 d, and were evaluated for effects on immune cell populations in spleen and bone marrow, and humoral-mediated, cell-mediated, and innate immunity. Three different parameters of cell-mediated immunity were similarly affected at 1000 mg STD/L. T-cell proliferative responses against allogeneic leukocytes and anti-CD3 were decreased 32%, and 21%, respectively. Cytotoxic T-lymphocyte activity was decreased at all effector:target cell ratios examined. At 2000 mg STD/L, the absolute numbers of CD3(+) T-cell progenitor cells in bone marrow were increased 86%, but the alterations in B-lymphocyte and other progenitor cells were not significant. There were no effects on bone marrow DNA synthesis or colony forming capabilities. STD-induced effects on humoral-mediated immunity, innate immunity, and splenocyte sub-populations were limited. Enhanced histopathology did not detect treatment-related lesions in any of the immune tissues. These data suggest exposure to STD in drinking water may adversely affect cell-mediated immunity.
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Affiliation(s)
- Rachel P Frawley
- a Division of the National Toxicology Program , National Institute of Environmental Health Sciences (NIEHS) Research Triangle Park , NC , USA
| | - Matthew J Smith
- b Department of Pharmacology and Toxicology , Virginia Commonwealth University , Richmond , VA
| | - Kimber L White
- b Department of Pharmacology and Toxicology , Virginia Commonwealth University , Richmond , VA
| | - Susan A Elmore
- a Division of the National Toxicology Program , National Institute of Environmental Health Sciences (NIEHS) Research Triangle Park , NC , USA
| | - Ron Herbert
- a Division of the National Toxicology Program , National Institute of Environmental Health Sciences (NIEHS) Research Triangle Park , NC , USA
| | - Rebecca Moore
- c Experimental Pathology Laboratories Inc., Research Triangle Park , NC , USA
| | | | - Mamta Behl
- a Division of the National Toxicology Program , National Institute of Environmental Health Sciences (NIEHS) Research Triangle Park , NC , USA
| | - Michelle J Hooth
- a Division of the National Toxicology Program , National Institute of Environmental Health Sciences (NIEHS) Research Triangle Park , NC , USA
| | - Grace E Kissling
- e Division of Intramural Research , NIEHS, Research Triangle Park , NC , USA
| | - Dori R Germolec
- a Division of the National Toxicology Program , National Institute of Environmental Health Sciences (NIEHS) Research Triangle Park , NC , USA
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Rumelhard M, Hosako H, Eurlings IMJ, Westerink WMA, Staska LM, van de Wiel JAG, La Marta J. Safety evaluation of rebaudioside A produced by fermentation. Food Chem Toxicol 2016; 89:73-84. [PMID: 26776281 DOI: 10.1016/j.fct.2016.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/17/2015] [Accepted: 01/13/2016] [Indexed: 11/19/2022]
Abstract
The safety of rebaudioside A, produced fermentatively by Yarrowia lipolytica encoding the Stevia rebaudiana metabolic pathway (fermentative Reb A), is based on several elements: first, the safety of steviol glycosides has been extensively evaluated and an acceptable daily intake has been defined; second, the use of Y. lipolytica, an avirulent yeast naturally found in foods and used for multiple applications; and third the high purity of fermentative Reb A and its compliance with internationally defined specifications. A bacterial reverse mutation assay and an in vitro micronucleus test conducted with fermentative Reb A provide evidence for its absence of mutagenicity, clastogenicity and aneugenicity. The oral administration of fermentative Reb A to Sprague-Dawley rats for at least 91 days did not lead to any adverse effects at consumption levels up to 2057 mg/kg bw/day for males and 2023 mg/kg bw/day for females, which were concluded to be the No Observed Adverse Effect Levels. The results were consistent with outcomes of previous studies conducted with plant-derived rebaudioside A, suggesting similar safety profiles for fermentative and plant-derived rebaudioside A. The results of the toxicity studies reported here support the safety of rebaudioside A produced fermentatively from Y. lipolytica, as a general purpose sweetener.
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Affiliation(s)
- Mélina Rumelhard
- DSM Food Specialties B.V., Alexander Fleminglaan 1, 2613 AX, Delft, The Netherlands.
| | - Hiromi Hosako
- WIL Research Laboratories LLC, 1407 George Rd., Ashland, OH, 44805, USA.
| | - Irene M J Eurlings
- WIL Research Europe B.V., Hambakenwetering 7, 5231 DD, 's-Hertogenbosch, The Netherlands.
| | - Walter M A Westerink
- WIL Research Europe B.V., Hambakenwetering 7, 5231 DD, 's-Hertogenbosch, The Netherlands.
| | - Lauren M Staska
- WIL Research Laboratories LLC, 310 Millstone Drive, Hillsborough, NC, 27278, USA.
| | | | - James La Marta
- DSM Nutritional Products, 45 Waterview Boulevard, Parsippany, NJ, 07054-1298, USA.
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Snyder-Talkington BN, Dong C, Sargent LM, Porter DW, Staska LM, Hubbs AF, Raese R, McKinney W, Chen BT, Battelli L, Lowry DT, Reynolds SH, Castranova V, Qian Y, Guo NL. mRNAs and miRNAs in whole blood associated with lung hyperplasia, fibrosis, and bronchiolo-alveolar adenoma and adenocarcinoma after multi-walled carbon nanotube inhalation exposure in mice. J Appl Toxicol 2016; 36:161-74. [PMID: 25926378 PMCID: PMC4418205 DOI: 10.1002/jat.3157] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 03/02/2015] [Accepted: 03/03/2015] [Indexed: 12/28/2022]
Abstract
Inhalation exposure to multi-walled carbon nanotubes (MWCNT) in mice results in inflammation, fibrosis and the promotion of lung adenocarcinoma; however, the molecular basis behind these pathologies is unknown. This study determined global mRNA and miRNA profiles in whole blood from mice exposed by inhalation to MWCNT that correlated with the presence of lung hyperplasia, fibrosis, and bronchiolo-alveolar adenoma and adenocarcinoma. Six-week-old, male, B6C3F1 mice received a single intraperitoneal injection of either the DNA-damaging agent methylcholanthrene (MCA, 10 µg g(-1) body weight) or vehicle (corn oil). One week after injections, mice were exposed by inhalation to MWCNT (5 mg m(-3), 5 hours per day, 5 days per week) or filtered air (control) for a total of 15 days. At 17 months post-exposure, mice were euthanized and examined for the development of pathological changes in the lung, and whole blood was collected and analyzed using microarray analysis for global mRNA and miRNA expression. Numerous mRNAs and miRNAs in the blood were significantly up- or down-regulated in animals developing pathological changes in the lung after MCA/corn oil administration followed by MWCNT/air inhalation, including fcrl5 and miR-122-5p in the presence of hyperplasia, mthfd2 and miR-206-3p in the presence of fibrosis, fam178a and miR-130a-3p in the presence of bronchiolo-alveolar adenoma, and il7r and miR-210-3p in the presence of bronchiolo-alveolar adenocarcinoma, among others. The changes in miRNA and mRNA expression, and their respective regulatory networks, identified in this study may potentially serve as blood biomarkers for MWCNT-induced lung pathological changes.
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Affiliation(s)
- Brandi N. Snyder-Talkington
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Chunlin Dong
- Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV 26506-9300, USA
| | - Linda M. Sargent
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Dale W. Porter
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | | | - Ann F. Hubbs
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Rebecca Raese
- Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV 26506-9300, USA
| | - Walter McKinney
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Bean T. Chen
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Lori Battelli
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - David T. Lowry
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Steven H. Reynolds
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Vincent Castranova
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV 26506, USA
| | - Yong Qian
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Nancy L. Guo
- Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV 26506-9300, USA
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Sargent LM, Porter DW, Staska LM, Hubbs AF, Lowry DT, Battelli L, Siegrist KJ, Kashon ML, Mercer RR, Bauer AK, Chen BT, Salisbury JL, Frazer D, McKinney W, Andrew M, Tsuruoka S, Endo M, Fluharty KL, Castranova V, Reynolds SH. Promotion of lung adenocarcinoma following inhalation exposure to multi-walled carbon nanotubes. Part Fibre Toxicol 2014; 11:3. [PMID: 24405760 PMCID: PMC3895742 DOI: 10.1186/1743-8977-11-3] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 11/06/2013] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Engineered carbon nanotubes are currently used in many consumer and industrial products such as paints, sunscreens, cosmetics, toiletries, electronic processes and industrial lubricants. Carbon nanotubes are among the more widely used nanoparticles and come in two major commercial forms, single-walled carbon nanotubes (SWCNT) and the more rigid, multi-walled carbon nanotubes (MWCNT). The low density and small size of these particles makes respiratory exposures likely. Many of the potential health hazards have not been investigated, including their potential for carcinogenicity. We, therefore, utilized a two stage initiation/promotion protocol to determine whether inhaled MWCNT act as a complete carcinogen and/or promote the growth of cells with existing DNA damage. Six week old, male, B6C3F1 mice received a single intraperitoneal (ip) injection of either the initiator methylcholanthrene(MCA, 10 μg/g BW, i.p.), or vehicle (corn oil). One week after i.p. injections, mice were exposed by inhalation to MWCNT (5 mg/m³, 5 hours/day, 5 days/week) or filtered air (controls) for a total of 15 days. At 17 months post-exposure, mice were euthanized and examined for lung tumor formation. RESULTS Twenty-three percent of the filtered air controls, 26.5% of the MWCNT-exposed, and 51.9% of the MCA-exposed mice, had lung bronchiolo-alveolar adenomas and lung adenocarcinomas. The average number of tumors per mouse was 0.25, 0.81 and 0.38 respectively. By contrast, 90.5% of the mice which received MCA followed by MWCNT had bronchiolo-alveolar adenomas and adenocarcinomas with an average of 2.9 tumors per mouse 17 months after exposure. Indeed, 62% of the mice exposed to MCA followed by MWCNT had bronchiolo-alveolar adenocarcinomas compared to 13% of the mice that received filtered air, 22% of the MCA-exposed, or 14% of the MWCNT-exposed. Mice with early morbidity resulting in euthanasia had the highest rate of metastatic disease. Three mice exposed to both MCA and MWCNT that were euthanized early had lung adenocarcinoma with evidence of metastasis (5.5%). Five mice (9%) exposed to MCA and MWCNT and 1 (1.6%) exposed to MCA developed serosal tumors morphologically consistent with sarcomatous mesotheliomas, whereas mice administered MWCNT or air alone did not develop similar neoplasms. CONCLUSIONS These data demonstrate that some MWCNT exposures promote the growth and neoplastic progression of initiated lung cells in B6C3F1 mice. In this study, the mouse MWCNT lung burden of 31.2 μg/mouse approximates feasible human occupational exposures. Therefore, the results of this study indicate that caution should be used to limit human exposures to MWCNT.
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Affiliation(s)
- Linda M Sargent
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Dale W Porter
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | | | - Ann F Hubbs
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - David T Lowry
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Lori Battelli
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Katelyn J Siegrist
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Michael L Kashon
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Robert R Mercer
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | | | - Bean T Chen
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | | | - David Frazer
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Walter McKinney
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Michael Andrew
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | | | | | - Kara L Fluharty
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Vince Castranova
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
| | - Steven H Reynolds
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
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Baker GL, Gupta A, Clark ML, Valenzuela BR, Staska LM, Harbo SJ, Pierce JT, Dill JA. Inhalation toxicity and lung toxicokinetics of C60 fullerene nanoparticles and microparticles. Toxicol Sci 2007; 101:122-31. [PMID: 17878152 DOI: 10.1093/toxsci/kfm243] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
While several recent reports have described the toxicity of water-soluble C60 fullerene nanoparticles, none have reported the toxicity resulting from the inhalation exposures to C60 fullerene nanoparticles or microparticles. To address this knowledge gap, we exposed male rats to C60 fullerene nanoparticles (2.22 mg/m3, 55 nm diameter) and microparticles (2.35 mg/m3, 0.93 microm diameter) for 3 h a day, for 10 consecutive days using a nose-only exposure system. Nanoparticles were created utilizing an aerosol vaporization and condensation process. Nanoparticles and microparticles were subjected to high-pressure liquid chromatography (HPLC), XRD, and scanning laser Raman spectroscopy, which cumulatively indicated no chemical modification of the C60 fullerenes occurred during the aerosol generation. At necropsy, no gross or microscopic lesions were observed in either group of C60 fullerene exposures rats. Hematology and serum chemistry results found statistically significant differences, although small in magnitude, in both exposure groups. Comparisons of bronchoalveolar (BAL) lavage fluid parameters identified a significant increase in protein concentration in rats exposed to C60 fullerene nanoparticles. BAL fluid macrophages from both exposure groups contained brown pigments, consistent with C60 fullerenes. C60 lung particle burdens were greater in nanoparticle-exposed rats than in microparticle-exposed rats. The calculated lung deposition rate and deposition fraction were 41 and 50% greater, respectively, in C60 fullerene nanoparticle-exposed group than the C60 fullerene microparticle-exposed group. Lung half-lives for C60 fullerene nanoparticles and microparticles were 26 and 29 days, respectively. In summary, this first in vivo assessment of the toxicity resulting from inhalation exposures to C60 fullerene nanoparticles and microparticles found minimal changes in the toxicological endpoints examined. Additional toxicological assessments involving longer duration inhalation exposures are needed to develop a better and more conclusive understanding of the potential toxicity of inhaled C60 fullerenes whether in nanoparticle or microparticle form.
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Affiliation(s)
- Gregory L Baker
- Battelle Toxicology Northwest, Richland, Washington 99354, USA.
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Staska LM, Davies CJ, Brown WC, McGuire TC, Suarez CE, Park JY, Mathison BA, Abbott JR, Baszler TV. Identification of vaccine candidate peptides in the NcSRS2 surface protein of Neospora caninum by using CD4+ cytotoxic T lymphocytes and gamma interferon-secreting T lymphocytes of infected holstein cattle. Infect Immun 2005; 73:1321-9. [PMID: 15731029 PMCID: PMC1064910 DOI: 10.1128/iai.73.3.1321-1329.2005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previously, our laboratory showed that Holstein cattle experimentally infected with Neospora caninum develop parasite-specific CD4+ cytotoxic T lymphocytes (CTL) that lyse infected, autologous target cells through a perforin-granzyme pathway. To identify specific parasite antigens inducing bovine CTL and helper T-lymphocyte responses for vaccine development against bovine neosporosis, the tachyzoite major surface proteins NcSAG1 and NcSRS2 were targeted. In whole tachyzoite antigen-expanded bovine T-lymphocyte lines, recombinant NcSRS2 induced potent memory CD4+- and CD8+-T-lymphocyte activation, as indicated by proliferation and gamma interferon (IFN-gamma) secretion, while recombinant NcSAG1 induced a minimal memory response. Subsequently, T-lymphocyte epitope-bearing peptides of NcSRS2 were mapped by using overlapping peptides covering the entire NcSRS2 sequence. Four experimentally infected cattle with six different major histocompatibility complex (MHC) class II haplotypes were the source of immune cells used to identify NcSRS2 peptides presented by Holstein MHC haplotypes. NcSRS2 peptides were mapped by using IFN-gamma secretion by rNcSRS2-stimulated, short-term T-lymphocyte cell lines, IFN-gamma enzyme-linked immunospot (ELISPOT) assay with peripheral blood mononuclear cells, and 51Cr release cytotoxicity assay of rNcSRS2-stimulated effector cells. Four N. caninum-infected Holstein cattle developed NcSRS2 peptide-specific T lymphocytes detected ex vivo in peripheral blood by IFN-gamma ELISPOT and in vitro by measuring T-lymphocyte IFN-gamma production and cytotoxicity. An immunodominant region of NcSRS2 spanning amino acids 133 to 155 was recognized by CD4+ T lymphocytes from the four cattle. These findings support investigation of subunit N. caninum vaccines incorporating NcSRS2 gene sequences or peptides for induction of NcSRS2 peptide-specific CTL and IFN-gamma-secreting T lymphocytes in cattle with varied MHC genotypes.
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Affiliation(s)
- Lauren M Staska
- Department of Veterinary Microbiology and Pathology, Bustad Hall, Washington State University, Pullman, WA 99164-7040, USA
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Abstract
Cattle infected with Neospora caninum readily experience transplacental parasite transmission, presumably after maternal parasitemia, leading to abortion or birth of congenitally infected calves. Cytotoxic T lymphocytes (CTL) are important mediators of protective immunity against Toxoplasma gondii, an intracellular apicomplexan protozoan closely related to N. caninum. In this study, N. caninum-specific CTL expanded from peripheral blood mononuclear cells of two major histocompatibility complex-mismatched, experimentally infected cattle were identified by using a (51)Cr release cytotoxicity assay. Enrichment and blocking of CD4(+)- and CD8(+)-T-lymphocyte effector subsets indicated that CD4(+) CTL killed N. caninum-infected, autologous target cells and that killing was mediated through a perforin/granzyme pathway. Detection and characterization of CTL responses to N. caninum in the natural, outbred, bovine host will facilitate identification of immunogens and design of immunization strategies to induce parasite-specific CTL against transplacental N. caninum transmission in cattle.
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Affiliation(s)
- Lauren M Staska
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman 99164, USA
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