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Rasooly R, Do P, Hernlem B. T-cell receptor Vβ8 for detection of biologically active streptococcal pyrogenic exotoxin type C. J Dairy Sci 2023; 106:6723-6730. [PMID: 37210361 DOI: 10.3168/jds.2023-23286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/21/2023] [Indexed: 05/22/2023]
Abstract
Streptococcus pyogenes is an important human pathogen, commonly spread by airborne droplets but also by ingestion of contaminated food. Apart from causing infection, this pathogen produces 13 distinct types of streptococcal pyrogenic exotoxins (SPE). The current method for detection cannot distinguish between the biologically active form of SPE that has been reported to cause foodborne outbreaks and the inactivated toxin that poses no health risk. To measure the biological activity of SPE type C (SPE-C), one such toxin that was linked to foodborne outbreaks associated with milk and milk products, we developed a cell-based assay that can discern between biologically active and inactive SPE-C. To the best of our knowledge, this is the first showing that SPE-C activates T-cells expressing Vβ8. With this finding, we used a T-cell line natively expressing Vβ8 that was genetically engineered to also express the luciferase reporter gene under the regulation of nuclear factor of activated T-cells response element in combination with a B-cell line to present the recombinant SPE-C (rSPE-C) toxin via major histocompatibility complex (MHC) class II to the Vβ8 T-cell receptor (TCR) in an assay to detect and to discern between biologically active and inactive rSPE-C. By using this system, we demonstrated that SPE-C induced significant IL-2 secretion after 72 h and visible light emission after only 5 h, doubling by 24 h. We utilize this finding to assess the specificity of the assay and the effect of pasteurization on SPE-C activity. We observed no cross-reactivity with SPE-B and significant loss of SPE-C biological activity in spiked phosphate-buffered saline while SPE-C spiked into milk is heat stable. Once SPE-C has formed, it is infeasible to eliminate it from milk by thermal treatment.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710.
| | - Paula Do
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710
| | - Bradley Hernlem
- Western Regional Research Center, Foodborne Toxin Detection and Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710
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Rasooly R, Do P, Hernlem B. Ex Vivo and In Vitro Methods for Detection of Bioactive Staphylococcal Enterotoxins. Methods Mol Biol 2022; 2393:237-255. [PMID: 34837183 DOI: 10.1007/978-1-0716-1803-5_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Staphylococcus aureus is a major bacterial cause of clinical infections and foodborne illnesses.Through the synthesis of a group of Staphylococcal enterotoxins (SEs), gastroenteritis occurs and the SEs function as superantigens to massively activate T cells. The ability to rapidly detect and quantify SEs is imperative in order to learn the causes of staphylococcal outbreaks and to stop similar outbreaks in the future. Also, the ability to discern active toxin is essential for development of food treatment and processing methods. Here, we discuss the various methodologies for detection and analysis of SEs.
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Affiliation(s)
- Reuven Rasooly
- Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, USA.
| | - Paula Do
- Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, USA
| | - Bradley Hernlem
- Western Regional Research Center, Foodborne Toxin Detection & Prevention Research Unit, Agricultural Research Service, United States Department of Agriculture, Albany, CA, USA
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Yang J, Yang X, Pan W, Wang M, Lu Y, Zhang J, Fang Z, Zhang X, Ji Y, Bei JX, Dong J, Wu Y, Pan C, Yu G, Zhou P, Li B. Fucoidan-Supplemented Diet Potentiates Immune Checkpoint Blockage by Enhancing Antitumor Immunity. Front Cell Dev Biol 2021; 9:733246. [PMID: 34434936 PMCID: PMC8382313 DOI: 10.3389/fcell.2021.733246] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 07/20/2021] [Indexed: 11/19/2022] Open
Abstract
Immune checkpoint blockade (ICB) therapies such as PD-1 antibodies have produced significant clinical responses in treating a variety of human malignancies, yet only a subset of cancer patients benefit from such therapy. To improve the ICB efficacy, combinations with additional therapeutics were under intensive investigation. Recently, special dietary compositions that can lower the cancer risk or inhibit cancer progression have drawn significant attention, although few were reported to show synergistic effects with ICB therapies. Interestingly, Fucoidan is naturally derived from edible brown algae and exhibits antitumor and immunomodulatory activities. Here we discover that fucoidan-supplemented diet significantly improves the antitumor activities of PD-1 antibodies in vivo. Specifically, fucoidan as a dietary ingredient strongly inhibits tumor growth when co-administrated with PD-1 antibodies, which effects can be further strengthened when fucoidan is applied before PD-1 treatments. Immune analysis revealed that fucoidan consistently promotes the activation of tumor-infiltrating CD8+ T cells, which support the evident synergies with ICB therapies. RNAseq analysis suggested that the JAK-STAT pathway is critical for fucoidan to enhance the effector function of CD8+ T cells, which could be otherwise attenuated by disruption of the T-cell receptor (TCR)/CD3 complex on the cell surface. Mechanistically, fucoidan interacts with this complex and augments TCR-mediated signaling that cooperate with the JAK-STAT pathway to stimulate T cell activation. Taken together, we demonstrated that fucoidan is a promising dietary supplement combined with ICB therapies to treat malignancies, and dissected an underappreciated mechanism for fucoidan-elicited immunomodulatory effects in cancer.
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Affiliation(s)
- Juan Yang
- Jiangmen Central Hospital, Affiliated Jiangmen Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangdong, China
| | - Xianzhi Yang
- Jiangmen Central Hospital, Affiliated Jiangmen Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Wenfeng Pan
- Jiangmen Central Hospital, Affiliated Jiangmen Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Mingshuo Wang
- Jiangmen Central Hospital, Affiliated Jiangmen Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Yuxiong Lu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangdong, China.,Clinical Biological Resource Bank, Guangzhou Institute of Pediatrics, Guangzhou Women and Children's Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Jianeng Zhang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangdong, China
| | - Ziqian Fang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangdong, China
| | - Xiaomin Zhang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangdong, China
| | - Yin Ji
- State Key Laboratory of Translational Medicine and Innovative Drug Development, Simcere Diagnostics Co., Ltd., Jiangsu, China
| | - Jin-Xin Bei
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangdong, China.,Center for Precision Medicine, Sun Yat-sen University, Guangdong, China
| | - Jiajun Dong
- Jiangmen Central Hospital, Affiliated Jiangmen Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Yi Wu
- Jiangmen Central Hospital, Affiliated Jiangmen Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Chaoyun Pan
- Jiangmen Central Hospital, Affiliated Jiangmen Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China
| | - Guangli Yu
- Key Laboratory of Marine Drugs of Ministry of Education, Shandong Provincial Key Laboratory of Glycoscience and Glycotechnology, School of Medicine and Pharmacy, Ocean University of China, Shandong, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Shandong, China
| | - Penghui Zhou
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangdong, China
| | - Bo Li
- Jiangmen Central Hospital, Affiliated Jiangmen Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangdong, China.,Center for Precision Medicine, Sun Yat-sen University, Guangdong, China
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Rasooly R, Do P, He X, Hernlem B. Human Leukemia T-Cell Lines as Alternatives to Animal Use for Detecting Biologically Active Staphylococcal Enterotoxin Type B. Toxins (Basel) 2021; 13:toxins13050300. [PMID: 33922450 PMCID: PMC8145393 DOI: 10.3390/toxins13050300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 11/17/2022] Open
Abstract
Staphylococcal enterotoxin type B (SEB) is associated with food poisoning. Current methods for the detection of biologically active SEB rely upon its ability to cause emesis when administered to live kittens or monkeys. This technique suffers from poor reproducibility and low sensitivity and is ethically disfavored over concerns for the welfare of laboratory animals. The data presented here show the first successful implementation of an alternative method to live animal testing that utilizes SEB super-antigenic activity to induce cytokine production for specific novel cell-based assays for quantifiable detection of active SEB. Rather than using or sacrificing live animals, we found that SEB can bind to the major histocompatibility complex (MHC) class II molecules on Raji B-cells. We presented this SEB–MHC class II complex to specific Vβ5.3 regions of the human T-cell line HPB-ALL, which led to a dose-dependent secretion of IL-2 that is capable of being quantified and can further detect 10 pg/mL of SEB. This new assay is 100,000 times more sensitive than the ex vivo murine splenocyte method that achieved a detection limit of 1 µg/mL. The data presented here also demonstrate that SEB induced proliferation in a dose-dependent manner for cells obtained by three different selection methods: by splenocyte cells containing 22% of CD4+ T-cells, by CD4+ T-cells enriched to >90% purity by negative selection methods, and by CD4+ T-cells enriched to >95% purity by positive selection methods. The highly enriched and positively isolated CD4+ T-cells with the lowest concentration of antigen-presenting cells (APC) (below 5%) provided higher cell proliferation than the splenocyte cells containing the highest concentration of APC cells.
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T cell Receptor Vβ9 in Method for Rapidly Quantifying Active Staphylococcal Enterotoxin Type-A without Live Animals. Toxins (Basel) 2019; 11:toxins11070399. [PMID: 31295829 PMCID: PMC6669470 DOI: 10.3390/toxins11070399] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 07/05/2019] [Accepted: 07/07/2019] [Indexed: 01/24/2023] Open
Abstract
Staphylococcal food poisoning is a result of ingestion of Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus. Staphylococcal enterotoxin type A (SEA) is the predominant toxin produced by S. aureus strains isolated from food-poisoning outbreak cases. For public safety, assays to detect and quantify SEA ideally respond only to the active form of the toxin and this usually means employing disfavored live animal testing which suffers also from poor reproducibility and sensitivity. We developed a cell-based assay for SEA quantification in which biologically-active SEA is presented by Raji B-cells to CCRF-CEM T-cells resulting in internalization of Vβ9 within 2 hours with dose dependency over a 6-log range of SEA concentrations. This bioassay can discern biologically active SEA from heat-inactivated SEA and is specific to SEA with no cross reactivity to the homologically-similar SED or SEE. In this study, we terminated any ongoing biochemical reactions in accessory cells while retaining the morphology of the antigenic sites by using paraformaldehyde fixation and challenged the current model for mechanism of action of the SEA superantigen. We demonstrated for the first time that although fixed, dead accessory cells, having no metabolic functions to process the SEA superantigen into short peptide fragments for display on their cell surface, can instead present intact SEA to induce T-cell activation which leads to cytokine production. However, the level of cytokine secretion induced by intact SEA was statistically significantly lower than with viable accessory cells, which have the ability to internalize and process the SEA superantigen.
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Alternative to Animal Use for Detecting Biologically Active Staphylococcal Enterotoxin Type A. Toxins (Basel) 2018; 10:toxins10120540. [PMID: 30558281 PMCID: PMC6316127 DOI: 10.3390/toxins10120540] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/10/2018] [Accepted: 12/13/2018] [Indexed: 11/17/2022] Open
Abstract
Staphylococcal enterotoxins (SEs) are a food safety concern. Existing methods for biologically active SE detection rely on the emetic response in live kittens or monkeys. This method suffers from low sensitivity, poor reproducibility, and causes ethical concerns regarding the use of experimental animals. The Lautenberg Chemical Safety Act encourages the development and adoption of alternatives to testing on animals for chemical toxicity methodologies. In this study, we utilized the superantigenic effect of SE type A (SEA) and used an ex vivo bioassay as an alternative to live animal testing. We found that interleukin-2 (IL-2) secreted by splenocyte can be utilized for quantifiable detection of SEA in food products. To avoid food matrix interference and attenuation of signal, we separated SEA from spiked food products by employing immunomagnetic beads that were coated with an anti-SEA antibody. This ex vivo method has achieved the detection of 1 ng mL−1 of SEA, which is 107 times more sensitive than the existing live animal testing methods. However, this ex vivo bioassay requires sacrificing of mice. To overcome this limitation, we established a cell based in vitro assay using CCRF-CEM, a human CD4+ T-cell line, for the quantitative detection of SEA. Incubation of SEA with CCRF-CEM human T-cells and Raji cells led to quantifiable and dose dependent secretion of IL-2. This novel cell-based assay is highly specific to biologically active SEA, compared with the related SE toxin subtypes B, D, and E or heat inactivated SEA, which produce no secretion of IL-2. This is the first demonstration of an alternative assay that completely eliminates the use of animals for quantitative detection of active SEA.
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