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Dubytska LP, Koirala R, Sanchez A, Thune R. Edwardsiella ictaluri T3SS Effector EseN Modulates Expression of Host Genes Involved in the Immune Response. Microorganisms 2022; 10:microorganisms10071334. [PMID: 35889053 PMCID: PMC9323599 DOI: 10.3390/microorganisms10071334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 12/10/2022] Open
Abstract
The type III secretion system (T3SS) effector EseN is encoded on the Edwardsiella ictaluri chromosome and is homologous to a family of T3SS effector proteins with phosphothreonine lyase activity. Previously we demonstrated that E. ictaluri invasion activates extracellular signal-regulated kinases 1 and 2 (ERK1/2) early in the infection, which are subsequently inactivated by EseN. Comparative transcriptomic analysis showed a total of 753 significant differentially expressed genes in head-kidney-derived macrophages (HKDM) infected with an EseN mutant (∆EseN) compared to HKDM infected with wild-type (WT) strains. This data strongly indicates classical activation of macrophages (the M1 phenotype) in response to E. ictaluri infection and a significant role for EseN in the manipulation of this process. Our data also indicates that E. ictaluri EseN is involved in the modulation of pathways involved in the immune response to infection and expression of several transcription factors, including NF-κβ (c-rel and relB), creb3L4, socs6 and foxo3a. Regulation of transcription factors leads to regulation of proinflammatory interleukins (IL-8, IL-12a, IL-15, IL-6) and cyclooxygenase-2 (COX-2) expression. Inhibition of COX-2 mRNA by WT E. ictaluri leads to decreased production of prostaglandin E2 (PGE2), which is the product of COX-2 activity. Collectively, our results indicate that E. ictaluri EseN is an important player in the modulation of host immune responses to E.ictaluri infection.
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Affiliation(s)
- Lidiya P. Dubytska
- Department of Biology and Chemistry, Southern University and A & M College, Baton Rouge, LA 70813, USA; (R.K.); (A.S.)
- Correspondence: ; Tel.: +1-225-771-33743
| | - Ranjan Koirala
- Department of Biology and Chemistry, Southern University and A & M College, Baton Rouge, LA 70813, USA; (R.K.); (A.S.)
| | - Azhia Sanchez
- Department of Biology and Chemistry, Southern University and A & M College, Baton Rouge, LA 70813, USA; (R.K.); (A.S.)
| | - Ronald Thune
- Department of Pathobiological Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, LA 70803, USA;
- School of Animal Science, Louisiana State University Agricultural Experiment Station, Baton Rouge, LA 70803, USA
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Impact of secondary TCR engagement on the heterogeneity of pathogen-specific CD8+ T cell response during acute and chronic toxoplasmosis. PLoS Pathog 2022; 18:e1010296. [PMID: 35727849 PMCID: PMC9249239 DOI: 10.1371/journal.ppat.1010296] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 07/01/2022] [Accepted: 05/06/2022] [Indexed: 11/19/2022] Open
Abstract
Initial TCR engagement (priming) of naive CD8+ T cells results in T cell expansion, and these early events influence the generation of diverse effector and memory populations. During infection, activated T cells can re-encounter cognate antigen, but how these events influence local effector responses or formation of memory populations is unclear. To address this issue, OT-I T cells which express the Nur77-GFP reporter of TCR activation were paired with the parasite Toxoplasma gondii that expresses OVA to assess how secondary encounter with antigen influences CD8+ T cell responses. During acute infection, TCR stimulation in affected tissues correlated with parasite burden and was associated with markers of effector cells while Nur77-GFP- OT-I showed signs of effector memory potential. However, both Nur77-GFP- and Nur77-GFP+ OT-I from acutely infected mice formed similar memory populations when transferred into naive mice. During the chronic stage of infection in the CNS, TCR activation was associated with large scale transcriptional changes and the acquisition of an effector T cell phenotype as well as the generation of a population of CD103+ CD69+ Trm like cells. While inhibition of parasite replication resulted in reduced effector responses it did not alter the Trm population. These data sets highlight that recent TCR activation contributes to the phenotypic heterogeneity of the CD8+ T cell response but suggest that this process has a limited impact on memory populations at acute and chronic stages of infection.
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Sana M, Rashid M, Rashid I, Akbar H, Gomez-Marin JE, Dimier-Poisson I. Immune response against toxoplasmosis-some recent updates RH: Toxoplasma gondii immune response. Int J Immunopathol Pharmacol 2022; 36:3946320221078436. [PMID: 35227108 PMCID: PMC8891885 DOI: 10.1177/03946320221078436] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AIMS Cytokines, soluble mediators of immunity, are key factors of the innate and adaptive immune system. They are secreted from and interact with various types of immune cells to manipulate host body's immune cell physiology for a counter-attack on the foreign body. A study was designed to explore the mechanism of Toxoplasma gondii (T. gondii) resistance from host immune response. METHODS AND RESULTS The published data on aspect of host (murine and human) immune response against T. gondii was taken from Google scholar and PubMed. Most relevant literature was included in this study. The basic mechanism of immune response starts from the interactions of antigens with host immune cells to trigger the production of cytokines (pro-inflammatory and anti-inflammatory) which then act by forming a cytokinome (network of cytokine). Their secretory equilibrium is essential for endowing resistance to the host against infectious diseases, particularly toxoplasmosis. A narrow balance lying between Th1, Th2, and Th17 cytokines (as demonstrated until now) is essential for the development of resistance against T. gondii as well as for the survival of host. Excessive production of pro-inflammatory cytokines leads to tissue damage resulting in the production of anti-inflammatory cytokines which enhances the proliferation of Toxoplasma. Stress and other infectious diseases (human immunodeficiency virus (HIV)) that weaken the host immunity particularly the cellular component, make the host susceptible to toxoplasmosis especially in pregnant women. CONCLUSION The current review findings state that in vitro harvesting of IL12 from DCs, Np and MΦ upon exposure with T. gondii might be a source for therapeutic use in toxoplasmosis. Current review also suggests that therapeutic interventions leading to up-regulation/supplementation of SOCS-3, IL12, and IFNγ to the infected host could be a solution to sterile immunity against T. gondii infection. This would be of interest particularly in patients passing through immunosuppression owing to any reason like the ones receiving anti-cancer therapy, the ones undergoing immunosuppressive therapy for graft/transplantation, the ones suffering from immunodeficiency virus (HIV) or having AIDS. Another imortant suggestion is to launch the efforts for a vaccine based on GRA6Nt or other similar antigens of T. gondii as a probable tool to destroy tissue cysts.
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Affiliation(s)
- Madiha Sana
- Department of Parasitology, 66920University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Muhammad Rashid
- Department of Parasitology, Faculty of Veterinary and Animal Sciences, 66920The Islamia University of Bahawalpur, Pakistan
| | - Imran Rashid
- Department of Parasitology, 66920University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Haroon Akbar
- Department of Parasitology, 66920University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Jorge E Gomez-Marin
- Grupo Gepamol, Centro de Investigaciones Biomedicas, Universidad del Quindio, Armenia, CO, South America
| | - Isabelle Dimier-Poisson
- Université de Tours, Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE), Unité mixte de recherche 1282 (UMR1282), Infectiologie et santé publique (ISP), Tours, France
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Li T, Li X, Zamani A, Wang W, Lee CN, Li M, Luo G, Eiler E, Sun H, Ghosh S, Jin J, Murali R, Ruan Q, Shi W, Chen YH. c-Rel Is a Myeloid Checkpoint for Cancer Immunotherapy. ACTA ACUST UNITED AC 2020; 1:507-517. [PMID: 33458695 DOI: 10.1038/s43018-020-0061-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Immunotherapy that targets lymphoid cell checkpoints holds great promise for curing cancer. However, a majority of cancer patients do not respond to this form of therapy. In addition to lymphoid cells, myeloid cells play essential roles in controlling immunity to cancer. Whether myeloid checkpoints exist that can be targeted to treat cancer is not well established. Here we show that c-Rel, a member of the nuclear factor (NF)-B family, specified the generation of myeloid-derived suppressor cells (MDSCs) by selectively turning on pro-tumoral genes while switching off anti-tumoral genes through a c-Rel enhanceosome. c-Rel deficiency in myeloid cells markedly inhibited cancer growth in mice, and pharmaceutical inhibition of c-Rel had the same effect. Combination therapy that blocked both c-Rel and the lymphoid checkpoint protein PD1 was more effective in treating cancer than blocking either alone. Thus, c-Rel is a myeloid checkpoint that can be targeted for treating cancer.
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Affiliation(s)
- Ting Li
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Contributed equally to this work
| | - Xinyuan Li
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Contributed equally to this work
| | - Ali Zamani
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Wei Wang
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Chin-Nien Lee
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mingyue Li
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - George Luo
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Emily Eiler
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Honghong Sun
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sankar Ghosh
- Department of Microbiology and Immunology, College of Physicians & Surgeons, Columbia University, New York, NY, USA
| | - Jian Jin
- Mount Sinai Center for Therapeutics Discovery, Departments of Pharmacological Sciences and Oncological Sciences, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ramachandran Murali
- Department of Biomedical Sciences, Research Division of Immunology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Qingguo Ruan
- Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, China
| | - Weiyun Shi
- Shandong Eye Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, China
| | - Youhai H Chen
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Caspase-8 promotes c-Rel-dependent inflammatory cytokine expression and resistance against Toxoplasma gondii. Proc Natl Acad Sci U S A 2019; 116:11926-11935. [PMID: 31147458 DOI: 10.1073/pnas.1820529116] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Caspase-8 is a key integrator of cell survival and cell death decisions during infection and inflammation. Following engagement of tumor necrosis factor superfamily receptors or certain Toll-like receptors (TLRs), caspase-8 initiates cell-extrinsic apoptosis while inhibiting RIPK3-dependent programmed necrosis. In addition, caspase-8 has an important, albeit less well understood, role in cell-intrinsic inflammatory gene expression. Macrophages lacking caspase-8 or the adaptor FADD have defective inflammatory cytokine expression and inflammasome priming in response to bacterial infection or TLR stimulation. How caspase-8 regulates cytokine gene expression, and whether caspase-8-mediated gene regulation has a physiological role during infection, remain poorly defined. Here we demonstrate that both caspase-8 enzymatic activity and scaffolding functions contribute to inflammatory cytokine gene expression. Caspase-8 enzymatic activity was necessary for maximal expression of Il1b and Il12b, but caspase-8 deficient cells exhibited a further decrease in expression of these genes. Furthermore, the ability of TLR stimuli to induce optimal IκB kinase phosphorylation and nuclear translocation of the nuclear factor kappa light chain enhancer of activated B cells family member c-Rel required caspase activity. Interestingly, overexpression of c-Rel was sufficient to restore expression of IL-12 and IL-1β in caspase-8-deficient cells. Moreover, Ripk3 -/- Casp8 -/- mice were unable to control infection by the intracellular parasite Toxoplasma gondii, which corresponded to defects in monocyte recruitment to the peritoneal cavity, and exogenous IL-12 restored monocyte recruitment and protection of caspase-8-deficient mice during acute toxoplasmosis. These findings provide insight into how caspase-8 controls inflammatory gene expression and identify a critical role for caspase-8 in host defense against eukaryotic pathogens.
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Chen Y, Sharma S, Assis PA, Jiang Z, Elling R, Olive AJ, Hang S, Bernier J, Huh JR, Sassetti CM, Knipe DM, Gazzinelli RT, Fitzgerald KA. CNBP controls IL-12 gene transcription and Th1 immunity. J Exp Med 2018; 215:3136-3150. [PMID: 30442645 PMCID: PMC6279399 DOI: 10.1084/jem.20181031] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/05/2018] [Accepted: 10/23/2018] [Indexed: 12/22/2022] Open
Abstract
These studies reveal a previously unrecognized role for Cnbp as a novel transcriptional regulator engaged downstream of innate immune receptors controlling the c-Rel–IL-12–Th1 axis, which has important implications for both host defense and inflammatory disease. An inducible program of inflammatory gene expression is a hallmark of antimicrobial defenses. Recently, cellular nucleic acid–binding protein (CNBP) was identified as a regulator of nuclear factor-kappaB (NF-κB)–dependent proinflammatory cytokine gene expression. Here, we generated mice lacking CNBP and found that CNBP regulates a very restricted gene signature that includes IL-12β. CNBP resides in the cytosol of macrophages and translocates to the nucleus in response to diverse microbial pathogens and pathogen-derived products. Cnbp-deficient macrophages induced canonical NF-κB/Rel signaling normally but were impaired in their ability to control the activation of c-Rel, a key driver of IL-12β gene transcription. The nuclear translocation and DNA-binding activity of c-Rel required CNBP. Lastly, Cnbp-deficient mice were more susceptible to acute toxoplasmosis associated with reduced production of IL-12β, as well as a reduced T helper type 1 (Th1) cell IFN-γ response essential to controlling parasite replication. Collectively, these findings identify CNBP as important regulator of c-Rel–dependent IL-12β gene transcription and Th1 immunity.
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Affiliation(s)
- Yongzhi Chen
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Shruti Sharma
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA.,Department of Immunology, Tufts University School of Medicine, Boston, MA
| | - Patricia A Assis
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Zhaozhao Jiang
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Roland Elling
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Andrew J Olive
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA
| | - Saiyu Hang
- Division of Immunology, Department of Microbiology and Immunology, Harvard Medical School, Boston, MA
| | - Jennifer Bernier
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Jun R Huh
- Division of Immunology, Department of Microbiology and Immunology, Harvard Medical School, Boston, MA
| | - Christopher M Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA
| | - David M Knipe
- Department of Microbiology and Immunology, Harvard Medical School, Boston, MA
| | - Ricardo T Gazzinelli
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA.,Departamento de Bioquímica e Imunologia, Universidade Federal of Minas Gerais, Belo Horizonte, Brazil.,Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Brazil
| | - Katherine A Fitzgerald
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA .,Centre for Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Trondheim, Norway
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Toxoplasma gondii superinfection and virulence during secondary infection correlate with the exact ROP5/ROP18 allelic combination. mBio 2015; 6:e02280. [PMID: 25714710 PMCID: PMC4358003 DOI: 10.1128/mbio.02280-14] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The intracellular parasite Toxoplasma gondii infects a wide variety of vertebrate species globally. Infection in most hosts causes a lifelong chronic infection and generates immunological memory responses that protect the host against new infections. In regions where the organism is endemic, multiple exposures to T. gondii likely occur with great frequency, yet little is known about the interaction between a chronically infected host and the parasite strains from these areas. A widely used model to explore secondary infection entails challenge of chronically infected or vaccinated mice with the highly virulent type I RH strain. Here, we show that although vaccinated or chronically infected C57BL/6 mice are protected against the type I RH strain, they are not protected against challenge with most strains prevalent in South America or another type I strain, GT1. Genetic and genomic analyses implicated the parasite-secreted rhoptry effectors ROP5 and ROP18, which antagonize the host’s gamma interferon-induced immunity-regulated GTPases (IRGs), as primary requirements for virulence during secondary infection. ROP5 and ROP18 promoted parasite superinfection in the brains of challenged survivors. We hypothesize that superinfection may be an important mechanism to generate T. gondii strain diversity, simply because two parasite strains would be present in a single meal consumed by the feline definitive host. Superinfection may drive the genetic diversity of Toxoplasma strains in South America, where most isolates are IRG resistant, compared to North America, where most strains are IRG susceptible and are derived from a few clonal lineages. In summary, ROP5 and ROP18 promote Toxoplasma virulence during reinfection. Toxoplasma gondii is a widespread parasite of warm-blooded animals and currently infects one-third of the human population. A long-standing assumption in the field is that prior exposure to this parasite protects the host from subsequent reexposure, due to the generation of protective immunological memory. However, this assumption is based on clinical data and mouse models that analyze infections with strains common to Europe and North America. In contrast, we found that the majority of strains sampled from around the world, in particular those from South America, were able to kill or reinfect the brains of hosts previously exposed to T. gondii. The T. gondii virulence factors ROP5 and ROP18, which inhibit key host effectors that mediate parasite killing, were required for these phenotypes. We speculate that these results underpin clinical observations that pregnant women previously exposed to Toxoplasma can develop congenital infection upon reexposure to South American strains.
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Zaph C, Artis D. Parasitic Infection of the Mucosal Surfaces. Mucosal Immunol 2015. [DOI: 10.1016/b978-0-12-415847-4.00054-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Immune response and immunopathology during toxoplasmosis. Semin Immunopathol 2012; 34:793-813. [PMID: 22955326 DOI: 10.1007/s00281-012-0339-3] [Citation(s) in RCA: 229] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 08/21/2012] [Indexed: 12/18/2022]
Abstract
Toxoplasma gondii is a protozoan parasite of medical and veterinary significance that is able to infect any warm-blooded vertebrate host. In addition to its importance to public health, several inherent features of the biology of T. gondii have made it an important model organism to study host-pathogen interactions. One factor is the genetic tractability of the parasite, which allows studies on the microbial factors that affect virulence and allows the development of tools that facilitate immune studies. Additionally, mice are natural hosts for T. gondii, and the availability of numerous reagents to study the murine immune system makes this an ideal experimental system to understand the functions of cytokines and effector mechanisms involved in immunity to intracellular microorganisms. In this article, we will review current knowledge of the innate and adaptive immune responses required for resistance to toxoplasmosis, the events that lead to the development of immunopathology, and the natural regulatory mechanisms that limit excessive inflammation during this infection.
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Gilmore TD, Gerondakis S. The c-Rel Transcription Factor in Development and Disease. Genes Cancer 2012; 2:695-711. [PMID: 22207895 DOI: 10.1177/1947601911421925] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 08/08/2011] [Indexed: 12/21/2022] Open
Abstract
c-Rel is a member of the nuclear factor κB (NF-κB) transcription factor family. Unlike other NF-κB proteins that are expressed in a variety of cell types, high levels of c-Rel expression are found primarily in B and T cells, with many c-Rel target genes involved in lymphoid cell growth and survival. In addition to c-Rel playing a major role in mammalian B and T cell function, the human c-rel gene (REL) is a susceptibility locus for certain autoimmune diseases such as arthritis, psoriasis, and celiac disease. The REL locus is also frequently altered (amplified, mutated, rearranged), and expression of REL is increased in a variety of B and T cell malignancies and, to a lesser extent, in other cancer types. Thus, agents that modulate REL activity may have therapeutic benefits for certain human cancers and chronic inflammatory diseases.
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Abstract
Transgenesis is an essential tool for assessing gene function in any organism, and it is especially crucial for parasitic nematodes given the dwindling armamentarium of effective anthelmintics and the consequent need to validate essential molecular targets for new drugs and vaccines. Two of the major routes of gene delivery evaluated to date in parasitic nematodes, bombardment with DNA-coated microparticles and intragonadal microinjection of DNA constructs, draw upon experience with the free-living nematode Caenorhabditis elegans. Bombardment has been used to transiently transfect Ascaris suum, Brugia malayi and Litomosoides sigmodontis with both RNA and DNA. Microinjection has been used to achieve heritable transgenesis in Strongyloides stercoralis, S. ratti and Parastrongyloides trichosuri and for additional transient expression studies in B. malayi. A third route of gene delivery revisits a classic method involving DNA transfer facilitated by calcium-mediated permeabilization of recipient cells in developing B. malayi larvae and results in transgene inheritance through host and vector passage. Assembly of microinjected transgenes into multi-copy episomal arrays likely results in their transcriptional silencing in some parasitic nematodes. Methods such as transposon-mediated transgenesis that favour low-copy number chromosomal integration may remedy this impediment to establishing stable transgenic lines. In the future, stable transgenesis in parasitic nematodes could enable loss-of-function approaches by insertional mutagenesis, in situ expression of inhibitory double-stranded RNA or boosting RNAi susceptibility through heterologous expression of dsRNA processing and transport proteins.
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Affiliation(s)
- James B Lok
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA.
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