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Macedo AB, Novis CL, Bosque A. Targeting Cellular and Tissue HIV Reservoirs With Toll-Like Receptor Agonists. Front Immunol 2019; 10:2450. [PMID: 31681325 PMCID: PMC6804373 DOI: 10.3389/fimmu.2019.02450] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 10/01/2019] [Indexed: 01/04/2023] Open
Abstract
The elimination of both cellular and tissue latent reservoirs is a challenge toward a successful HIV cure. "Shock and Kill" are among the therapeutic strategies that have been more extensively studied to target these reservoirs. These strategies are aimed toward the reactivation of the latent reservoir using a latency-reversal agent (LRA) with the subsequent killing of the reactivated cell either by the cytotoxic arm of the immune system, including NK and CD8 T cells, or by viral cytopathic mechanisms. Numerous LRAs are currently being investigated in vitro, ex vivo as well as in vivo for their ability to reactivate and reduce latent reservoirs. Among those, several toll-like receptor (TLR) agonists have been shown to reactivate latent HIV. In humans, there are 10 TLRs that recognize different pathogen-associated molecular patterns. TLRs are present in several cell types, including CD4 T cells, the cell compartment that harbors the majority of the latent reservoir. Besides their ability to reactivate latent HIV, TLR agonists also increase immune activation and promote an antiviral response. These combined properties make TLR agonists unique among the different LRAs characterized to date. Additionally, some of these agonists have shown promise toward finding an HIV cure in animal models. When in combination with broadly neutralizing antibodies, TLR-7 agonists have shown to impact the SIV latent reservoir and delay viral rebound. Moreover, there are FDA-approved TLR agonists that are currently being investigated for cancer therapy and other diseases. All these has prompted clinical trials using TLR agonists either alone or in combination toward HIV eradication approaches. In this review, we provide an extensive characterization of the state-of-the-art of the use of TLR agonists toward HIV eradication strategies and the mechanism behind how TLR agonists target both cellular and tissue HIV reservoirs.
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Affiliation(s)
- Amanda B. Macedo
- Department of Microbiology, Immunology and Tropical Medicine, George Washington University, Washington, DC, United States
| | - Camille L. Novis
- Department of Pathology, Division of Microbiology and Immunology, The University of Utah, Salt Lake City, UT, United States
| | - Alberto Bosque
- Department of Microbiology, Immunology and Tropical Medicine, George Washington University, Washington, DC, United States
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Chen Q, Pang MH, Ye XH, Yang G, Lin C. The Toxoplasma gondii ME-49 strain upregulates levels of A20 that inhibit NF-κB activation and promotes apoptosis in human leukaemia T-cell lines. Parasit Vectors 2018; 11:305. [PMID: 29776374 PMCID: PMC5960183 DOI: 10.1186/s13071-018-2837-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 04/09/2018] [Indexed: 01/01/2023] Open
Abstract
Background Acute T-lymphocyte leukaemia is a form of haematological malignancy with abnormal activation of NF-κB pathway, which results in high expression of A20 and ABIN1, which constitute a negative feedback mechanism for the regulation of NF-κB activation. Clinical studies have found that acute T-lymphocyte leukaemia patients are susceptible to Toxoplasma gondii infection; however, the effect of T. gondii on the proliferation and apoptosis of human leukaemia T-cells remains unclear. Here, we used the T. gondii ME-49 strain to infect human leukaemia T-cell lines Jurkat and Molt-4, to explore the effect of T. gondii on proliferation and apoptosis, which is mediated by NF-κB in human leukaemia T-cells. Methods The Tunel assay was used to detect cell apoptosis. Cell Counting Kit-8 was used to detect cell proliferation viability. The apoptosis level and the expression level of NF-κB related proteins in human leukaemia T-cells were detected by flow cytometry and Western blotting. Results Western blotting analyses revealed that the T. gondii ME-49 strain increased the expression of A20 and decreased both ABIN1 expression and NF-κB p65 phosphorylation. By constructing a lentiviral-mediated shRNA to knockdown the A20 gene in Jurkat T-cells and Molt-4 T-cells, the apoptosis levels of the two cell lines decreased after T. gondii ME-49 infection, and levels of NF-κB p65 phosphorylation and ABIN1 were higher than in the non-konckdown group. After knockingdown ABIN1 gene expression by constructing the lentiviral-mediated shRNA and transfecting the recombinant expression plasmid containing the ABIN1 gene into two cell lines, apoptosis levels and cleaved caspase-8 expression increased or decreased in response to T. gondii ME-49 infection, respectively. Conclusions Our data suggest that ABIN1 protects human leukaemia T-cells by allowing them to resist the apoptosis induced by T. gondii ME-49 and that the T. gondii ME-49 strain induces the apoptosis of human leukaemia T-cells via A20-mediated downregulation of ABIN1 expression.
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Affiliation(s)
- Qian Chen
- Department of Microbiology and Immunology, Medical College, Jinan University, Guangzhou, Guangdong Province, 510632, People's Republic of China
| | - Min-Hui Pang
- Department of Epidemiology and Health statistics, Medical College, Jinan University, Guangzhou, Guangdong Province, 510632, People's Republic of China
| | - Xiao-Hong Ye
- Department of Parasitology, Medical College, Jinan University, Guangzhou, Guangdong Province, 510632, People's Republic of China
| | - Guang Yang
- Department of Parasitology, Medical College, Jinan University, Guangzhou, Guangdong Province, 510632, People's Republic of China
| | - Chen Lin
- Department of Microbiology and Immunology, Medical College, Jinan University, Guangzhou, Guangdong Province, 510632, People's Republic of China.
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Sancineto L, Iraci N, Tabarrini O, Santi C. NCp7: targeting a multitasking protein for next-generation anti-HIV drug development part 1: covalent inhibitors. Drug Discov Today 2017; 23:260-271. [PMID: 29107765 DOI: 10.1016/j.drudis.2017.10.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 10/02/2017] [Accepted: 10/17/2017] [Indexed: 11/16/2022]
Abstract
The major internal component of the HIV virion core is the nucleocapsid protein 7 (NCp7), a small, highly basic protein that is essential for multiple stages of the viral replicative cycle, and whose structure is preserved in all viral strains, including clinical isolates from therapy-experienced patients. This key protein is recognised as a potential target for an effective next-generation antiretroviral therapy, because it could offer the possibility to develop broad-spectrum agents that are less prone to select for resistant strains. Here, we provide a comprehensive overview of the covalent NCp7 inhibitors that have emerged over the past 25 years of drug discovery campaigns, emphasising, where possible, their structure-activity relationships (SARs) and pharmacophoric features.
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Affiliation(s)
- Luca Sancineto
- Department of Heterorganic Chemistry, Centre of Molecular and Macromolecular Studies, Lodz, Poland.
| | - Nunzio Iraci
- Department of Pharmacy, University of Salerno, Fisciano, Salerno, Italy
| | - Oriana Tabarrini
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
| | - Claudio Santi
- Department of Pharmaceutical Sciences, University of Perugia, Perugia, Italy
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Rosowski EE, Lu D, Julien L, Rodda L, Gaiser RA, Jensen KDC, Saeij JPJ. Strain-specific activation of the NF-kappaB pathway by GRA15, a novel Toxoplasma gondii dense granule protein. ACTA ACUST UNITED AC 2011; 208:195-212. [PMID: 21199955 PMCID: PMC3023140 DOI: 10.1084/jem.20100717] [Citation(s) in RCA: 300] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
NF-κB is an integral component of the immune response to Toxoplasma gondii. Although evidence exists that T. gondii can directly modulate the NF-κB pathway, the parasite-derived effectors involved are unknown. We determined that type II strains of T. gondii activate more NF-κB than type I or type III strains, and using forward genetics we found that this difference is a result of the polymorphic protein GRA15, a novel dense granule protein which T. gondii secretes into the host cell upon invasion. A GRA15-deficient type II strain has a severe defect in both NF-κB nuclear translocation and NF-κB-mediated transcription. Furthermore, human cells expressing type II GRA15 also activate NF-κB, demonstrating that GRA15 alone is sufficient for NF-κB activation. Along with the rhoptry protein ROP16, GRA15 is responsible for a large part of the strain differences in the induction of IL-12 secretion by infected mouse macrophages. In vivo bioluminescent imaging showed that a GRA15-deficient type II strain grows faster compared with wild-type, most likely through its reduced induction of IFN-γ. These results show for the first time that a dense granule protein can modulate host signaling pathways, and dense granule proteins can therefore join rhoptry proteins in T. gondii's host cell-modifying arsenal.
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Affiliation(s)
- Emily E Rosowski
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Dieckhoff B, Kessler B, Jobst D, Kues W, Petersen B, Pfeifer A, Kurth R, Niemann H, Wolf E, Denner J. Distribution and expression of porcine endogenous retroviruses in multi-transgenic pigs generated for xenotransplantation. Xenotransplantation 2009; 16:64-73. [DOI: 10.1111/j.1399-3089.2009.00515.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
The modulation of apoptosis has emerged as an important weapon in the pathogenic arsenal of multiple intracellular protozoan parasites. Cryptosporidium parvum, Leishmania spp., Trypanosoma cruzi, Theileria spp., Toxoplasma gondii and Plasmodium spp. have all been shown to inhibit the apoptotic response of their host cell. While the pathogen mediators responsible for this modulation are unknown, the parasites are interacting with multiple apoptotic regulatory systems to render their host cell refractory to apoptosis during critical phases of intracellular infection, including parasite invasion, establishment and replication. Additionally, emerging evidence suggests that the parasite life cycle stage impacts the modulation of apoptosis and possibly parasite differentiation. Dissection of the host-pathogen interactions involved in modulating apoptosis reveals a dynamic and complex interaction that recent studies are beginning to unravel.
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Affiliation(s)
- John C Carmen
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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Hunter CA, Whitworth JAG. Immune deficiencies and parasitic diseases. Parasite Immunol 2006; 28:545-7. [PMID: 17042926 DOI: 10.1111/j.1365-3024.2006.00919.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Infectious agents and gene–environmental interactions in the etiopathogenesis of schizophrenia. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.cnr.2006.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Sun J, Soos T, Kewalramani VN, Osiecki K, Zheng JH, Falkin L, Santambrogio L, Littman DR, Goldstein H. CD4-specific transgenic expression of human cyclin T1 markedly increases human immunodeficiency virus type 1 (HIV-1) production by CD4+ T lymphocytes and myeloid cells in mice transgenic for a provirus encoding a monocyte-tropic HIV-1 isolate. J Virol 2006; 80:1850-62. [PMID: 16439541 PMCID: PMC1367149 DOI: 10.1128/jvi.80.4.1850-1862.2006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1)-encoded Tat provides transcriptional activation critical for efficient HIV-1 replication by interacting with cyclin T1 and recruiting P-TEFb to efficiently elongate the nascent HIV transcript. Tat-mediated transcriptional activation in mice is precluded by species-specific structural differences that prevent Tat interaction with mouse cyclin T1 and severely compromise HIV-1 replication in mouse cells. We investigated whether transgenic mice expressing human cyclin T1 under the control of a murine CD4 promoter/enhancer cassette that directs gene expression to CD4(+) T lymphocytes and monocytes/macrophages (hu-cycT1 mice) would display Tat responsiveness in their CD4-expressing mouse cells and selectively increase HIV-1 production in this cellular population, which is infected primarily in HIV-1-positive individuals. To this end, we crossed hu-cycT1 mice with JR-CSF transgenic mice carrying the full-length HIV-1(JR-CSF) provirus under the control of the endogenous HIV-1 long terminal repeat and demonstrated that human cyclin T1 expression is sufficient to support Tat-mediated transactivation in primary mouse CD4 T lymphocytes and monocytes/macrophages and increases in vitro and in vivo HIV-1 production by these stimulated cells. Increased HIV-1 production by CD4(+) T lymphocytes was paralleled with their specific depletion in the peripheral blood of the JR-CSF/hu-cycT1 mice, which increased over time. In addition, increased HIV-1 transgene expression due to human cyclin T1 expression was associated with increased lipopolysaccharide-stimulated monocyte chemoattractant protein 1 production by JR-CSF mouse monocytes/macrophages in vitro. Therefore, the JR-CSF/hu-cycT1 mice should provide an improved mouse system for investigating the pathogenesis of various aspects of HIV-1-mediated disease and the efficacies of therapeutic interventions.
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Affiliation(s)
- Jinglin Sun
- Albert Einstein College of Medicine, Forschheimer Building, Room 408, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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Zhang J, Li G, Bafica A, Pantelic M, Zhang P, Broxmeyer H, Liu Y, Wetzler L, He JJ, Chen T. Neisseria gonorrhoeae enhances infection of dendritic cells by HIV type 1. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2005; 174:7995-8002. [PMID: 15944306 DOI: 10.4049/jimmunol.174.12.7995] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Clinical studies indicate that Neisseria gonorrhoeae (gonococci (GC)) has the capacity to enhance HIV type 1 (HIV-1) infection. We studied whether GC enhances HIV infection of activated dendritic cells (DCs). The results show that GC can dramatically enhance HIV replication in human DCs during coinfection. The GC component responsible for HIV infection enhancement may be peptidoglycan, which activates TLR2. TLR2 involvement is suggested by bacterial lipoprotein, a TLR2-specific inducer, which stimulates a strong enhancement of HIV infection by human DCs. Moreover, participation of TLR2 is further implicated because GC is unable to stimulate expression of HIV in DCs of TLR2-deficient HIV-1-transgenic mice. These results provide one potential mechanism through which GC infection increases HIV replication in patients infected with both GC and HIV.
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MESH Headings
- Animals
- Antigens, CD
- CD4 Antigens/biosynthesis
- Cell Adhesion Molecules/biosynthesis
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Dendritic Cells/microbiology
- Dendritic Cells/virology
- Female
- HIV Infections/immunology
- HIV Infections/microbiology
- HIV Infections/virology
- HIV-1/genetics
- HIV-1/immunology
- HIV-1/pathogenicity
- HeLa Cells
- Histocompatibility Antigens Class I/biosynthesis
- Humans
- Immunoglobulins/biosynthesis
- Lectins, C-Type/biosynthesis
- Lipoproteins/physiology
- Male
- Membrane Glycoproteins/biosynthesis
- Membrane Glycoproteins/deficiency
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/physiology
- Mice
- Mice, Knockout
- Mice, Transgenic
- Monocytes/immunology
- Monocytes/microbiology
- Monocytes/virology
- Neisseria gonorrhoeae/immunology
- Peptidoglycan/pharmacology
- Receptors, CCR5/biosynthesis
- Receptors, CXCR4/biosynthesis
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Toll-Like Receptor 2
- Toll-Like Receptors
- Up-Regulation/immunology
- CD83 Antigen
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Affiliation(s)
- Jizhong Zhang
- Department of Microbiology and Immunology, Division of Infectious Diseases, Walther Oncology Center, Walther Oncology Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Srivastava P, Schito M, Fattah RJ, Hara T, Hartman T, Buckheit RW, Turpin JA, Inman JK, Appella E. Optimization of unique, uncharged thioesters as inhibitors of HIV replication. Bioorg Med Chem 2005; 12:6437-50. [PMID: 15556761 DOI: 10.1016/j.bmc.2004.09.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 09/16/2004] [Accepted: 09/16/2004] [Indexed: 11/27/2022]
Abstract
A combinatorial chemistry approach was employed to prepare a restricted library of N-substituted S-acyl-2-mercaptobenzamide thioesters. It was shown that many members of this chemotype display anti-HIV activity via their ability to interact with HIV-1, HIV-2, SIV-infected cells, cell-free virus, and chronically and latently infected cells in a manner consistent with targeting of the highly conserved HIV-1 NCp7 zinc fingers. Compounds were initially screened using two different in vitro antiviral assays and evaluated for stability in neutral buffer containing 10% pooled human serum using a spectrophotometric assay. These data revealed that there was no significant correlation between thioester stability and antiviral activity, however, a slight inverse correlation between serum stability and virucidal activity was noted. Based on the virucidal capability and the ability to select lead compounds to inhibit virus expression from latently infected TNFalpha-induced U1 cells, we next determined if these compounds could prevent HIV cell-to-cell transmission. Several thioesters demonstrated potent inhibition of HIV cell-to-cell transmission with EC50 values in the 80-100 nM range. Thus, we have optimized a series of restricted thioesters and provided evidence that serum stability is not required for antiviral activity. Moreover, selected compounds show potential for development as topical microbicides.
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Affiliation(s)
- Pratibha Srivastava
- Laboratory of Cell Biology, National Cancer Institute, National Institute of Health, Bethesda, MD 20892, USA
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Osiecki K, Xie L, Zheng JH, Squires R, Pettoello-Mantovani M, Goldstein H. Identification of granulocyte-macrophage colony-stimulating factor and lipopolysaccharide-induced signal transduction pathways that synergize to stimulate HIV type 1 production by monocytes from HIV type 1 transgenic mice. AIDS Res Hum Retroviruses 2005; 21:125-39. [PMID: 15725751 DOI: 10.1089/aid.2005.21.125] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
HIV-1-infected monocyte/macrophages located in lymph nodes and tissues are highly productive sources of HIV-1 and may function as a persistent reservoir contributing to the rebound viremia observed after highly active antiretroviral therapy is stopped. Mechanisms activating latently infected, primary monocyte/macrophages to produce HIV-1 were investigated using monocytes isolated from a transgenic mouse line carrying a full-length proviral clone of a monocyte-tropic HIV-1 isolate, HIV-1(JR-CSF), regulated by the endogenous long terminal repeat (LTR) (JR-CSF mice). Granulocyte-macrophage colony-stimulating factor (GM-CSF) combined with lipopolysaccharide (LPS) induced infectious HIV-1 production by JR-CSF mouse monocytes over 10-fold and 100-fold higher than that stimulated by GM-CSF or LPS alone, respectively. We examined mechanisms of GM-CSF synergy with LPS and demonstrated that GM-CSF up-regulated the LPS receptor, TLR-4, and also synergized with LPS to activate mitogen-activated protein (MAP) kinase/ERK kinase and the Sp1 transcription factor. Inhibitors of either MAP kinase/ERK kinase or p38 kinase but not PI 3-kinase potently suppressed GM-CSF and LPS-induced HIV-1 production by JR-CSF mouse monocytes. Because Sp1 is activated by both the MAP kinase/ERK kinase and p38 kinase pathways, we postulate that synergistic activation of these pathways by GM-CSF and LPS induced sufficient levels of Sp1 to activate the HIV-1 LTR in a Tat-independent manner and induced HIV-1 production by JR-CSF mouse monocytes. Thus, our study delineated the pathway of HIV-1 LTR activation by GM-CSF and LPS and indicated that JR-CSF transgenic mice may provide a new in vitro and in vivo system for investigating the mechanism by which inflammatory and infectious stimuli activate HIV-1 production from latently infected monocytes.
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Affiliation(s)
- Kristin Osiecki
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Hsu WM, Chiou SH, Chen SSL, Shyong MP, Ho CK, Chen SJ, Wu CC, Kung SH, Chi CW. The HIV RNA Levels of Plasma and Ocular Fluids in AIDS Patients with Ophthalmic Infections. ACTA ACUST UNITED AC 2004; 218:328-32. [PMID: 15334014 DOI: 10.1159/000079475] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2003] [Accepted: 01/16/2004] [Indexed: 11/19/2022]
Abstract
The aim of the present study was to evaluate the impact of highly active antiretroviral therapy (HAART) on HIV viral load of plasma and intraocular fluids in AIDS patients with ophthalmic opportunistic infections. We further compared the treatment effect of HAART on these patients. From June 1997 to July 2003, we examined and followed up the ophthalmic conditions of 49 patients receiving HAART with ophthalmic diseases during this period. The method of reverse-transcriptase polymerase chain reaction was used to detect and monitor HIV load in plasma and/or aqueous humor of AIDS patients. Before HAART, the HIV levels in the plasma and aqueous humor in 8 AIDS patients with ophthalmic opportunistic infections were significantly higher than those in 6 patients with HIV-related retinopathy (p < 0.05). Compared to the eye findings and clinical improvement, HIV loads of aqueous humor in 10 of 14 AIDS patients (6 with HIV-related retinopathy, 5 with cytomegalovirus retinitis, 2 with toxoplasmic retinitis and 1 with cryptococcal chorioretinitis) declined to undetectable levels (< 400 copies/ml) after 4-8 months of HAART. HIV virus levels in the plasma of AIDS patients were significantly decreased, and the CD4 counts of these patients were significantly increased (Wilcoxon test) after initiation of HAART.
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Affiliation(s)
- Wen-Ming Hsu
- Department of Ophthalmology, Taipei Veterans General Hospital and National Yang-Ming University and Institutes of Clinical Medicine, Taipei, Taiwan, ROC
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Báfica A, Scanga CA, Schito M, Chaussabel D, Sher A. Influence of Coinfecting Pathogens on HIV Expression: Evidence for a Role of Toll-Like Receptors. THE JOURNAL OF IMMUNOLOGY 2004; 172:7229-34. [PMID: 15187096 DOI: 10.4049/jimmunol.172.12.7229] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Immune activation of HIV gene expression as a consequence of the host response to coinfecting pathogens has been implicated as an important factor in AIDS progression. Immune responsiveness to many of the infectious agents associated with HIV has been demonstrated to depend on a family of innate recognition molecules, known as Toll-like receptors (TLR). Therefore, TLR-pathogen interactions could play an indirect role in regulating HIV-associated disease. In this review, we summarize emerging evidence for the influence of TLR recognition on HIV gene activation and AIDS progression.
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Affiliation(s)
- André Báfica
- Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 50, Rm. 6146, 50 South Drive, Bethesda, MD 20892, USA.
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15
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Dickie P, Roberts A, Uwiera R, Witmer J, Sharma K, Kopp JB. Focal glomerulosclerosis in proviral and c-fms transgenic mice links Vpr expression to HIV-associated nephropathy. Virology 2004; 322:69-81. [PMID: 15063118 DOI: 10.1016/j.virol.2004.01.026] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Revised: 12/16/2003] [Accepted: 01/14/2004] [Indexed: 10/26/2022]
Abstract
Clinical and morphologic features of human immunodeficiency virus (HIV)-associated nephropathy (HIVAN), such as proteinuria, sclerosing glomerulopathy, tubular degeneration, and interstitial disease, have been modeled in mice bearing an HIV proviral transgene rendered noninfectious through a deletion in gag/pol. Exploring the genetic basis of HIVAN, HIV transgenic mice bearing mutations in either or both of the accessory genes nef and vpr were created. Proteinuria and focal glomerulosclerosis (FGS) only developed in mice with an intact vpr gene. Transgenic mice bearing a simplified proviral DNA (encoding only Tat and Vpr) developed renal disease characterized by FGS in which Vpr protein was localized to glomerular and tubular epithelia by immunohistochemistry. The dual transgenic progeny of HIV[Tat/Vpr] mice bred to HIV[DeltaVpr] proviral transgenic mice displayed a more severe nephropathy with no apparent increase in Vpr expression, implying that multiple viral genes contribute to HIVAN. However, the unique contribution of macrophage-specific Vpr expression in the development of glomerular disease was underscored by the induction of FGS in multiple murine lines bearing a c-fms/vpr transgene.
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Affiliation(s)
- Peter Dickie
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada T6G 2S2.
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Abstract
Recent epidemiologic studies indicate that infectious agents may contribute to some cases of schizophrenia. In animals, infection with Toxoplasma gondii can alter behavior and neurotransmitter function. In humans, acute infection with T. gondii can produce psychotic symptoms similar to those displayed by persons with schizophrenia. Since 1953, a total of 19 studies of T. gondii antibodies in persons with schizophrenia and other severe psychiatric disorders and in controls have been reported; 18 reported a higher percentage of antibodies in the affected persons; in 11 studies the difference was statistically significant. Two other studies found that exposure to cats in childhood was a risk factor for the development of schizophrenia. Some medications used to treat schizophrenia inhibit the replication of T. gondii in cell culture. Establishing the role of T. gondii in the etiopathogenesis of schizophrenia might lead to new medications for its prevention and treatment.
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Affiliation(s)
- E Fuller Torrey
- Stanley medical REsearch Institute, Bethesda, Maryland 20814-2142, USA.
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17
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Báfica A, Scanga CA, Equils O, Sher A. The induction of Toll-like receptor tolerance enhances rather than suppresses HIV-1 gene expression in transgenic mice. J Leukoc Biol 2003; 75:460-6. [PMID: 14657211 DOI: 10.1189/jlb.0803388] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Microbial-induced proinflammatory pathways are thought to play a key role in the activation of human immunodeficiency virus type 1 (HIV-1) gene expression. The induction of Toll-like receptor (TLR) tolerance leads to a complex reprogramming in the pattern of inflammatory gene expression and down-modulates tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1, and IL-6 production. Using transgenic (Tg) mice that incorporate the entire HIV-1 genome, including the long-terminal repeat, we have previously demonstrated that a number of different TLR ligands induce HIV-1 gene expression in cultured splenocytes as well as purified antigen-presenting cell populations. Here, we have used this model to determine the effect of TLR-mediated tolerance as an approach to inhibiting microbial-induced viral gene expression in vivo. Unexpectedly, Tg splenocytes and macrophages, rendered tolerant in vitro to TLR2, TLR4, and TLR9 ligands as assessed by proinflammatory cytokine secretion and nuclear factor-kappaB activation, showed enhanced HIV-1 p24 production. A similar enhancement was observed in splenocytes tolerized and then challenged with heterologous TLR ligands. Moreover, TLR2- and TLR4-homotolerized mice demonstrated significantly increased plasma p24 production in vivo despite lower levels of TNF-alpha. Together, these results demonstrate that HIV-1 expression is enhanced in TLR-reprogrammed host cells, possibly reflecting a mechanism used by the virus to escape the effects of microbial-induced tolerance during natural infection in vivo.
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Affiliation(s)
- André Báfica
- Immunobiology Section, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20982, USA.
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18
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Fighting HIV: a little help from Toxoplasma? Blood 2003. [DOI: 10.1182/blood-2003-08-2846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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19
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Báfica A, Scanga CA, Schito ML, Hieny S, Sher A. Cutting edge: in vivo induction of integrated HIV-1 expression by mycobacteria is critically dependent on Toll-like receptor 2. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:1123-7. [PMID: 12874196 DOI: 10.4049/jimmunol.171.3.1123] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mycobacterial infection has been implicated as a possible factor in AIDS progression in populations where HIV-1 and Mycobacterium tuberculosis are coendemic. In support of this concept, we have previously shown that HIV-1-transgenic (Tg) mice infected with mycobacteria display enhanced viral gene and protein expression. In this study, we demonstrate that the induction of HIV-1 observed in this model is dependent on Toll-like receptor 2 (TLR2), a pattern recognition receptor known to be involved in mycobacteria-host interaction. Spleen cells from HIV-1-Tg mice deficient in TLR2 (Tg/TLR2(-/-)) were found to be completely defective in p24 production induced in response to live M. tuberculosis or Mycobacterium avium as well as certain mycobacterial products. Importantly, following in vivo mycobacterial infection, Tg/TLR2(-/-) mice failed to display the enhanced HIV-1 gag/env mRNA and p24 protein synthesis exhibited by wild-type Tg animals. Together, these results argue that TLR2 plays a crucial role in the activation of HIV-1 expression by mycobacterial coinfections.
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Affiliation(s)
- André Báfica
- Immunobiology Section, National Institute of Allergy and Infectious Diseases and. Chemical Immunology Section, Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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20
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Equils O, Schito ML, Karahashi H, Madak Z, Yarali A, Michelsen KS, Sher A, Arditi M. Toll-like receptor 2 (TLR2) and TLR9 signaling results in HIV-long terminal repeat trans-activation and HIV replication in HIV-1 transgenic mouse spleen cells: implications of simultaneous activation of TLRs on HIV replication. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:5159-64. [PMID: 12734363 DOI: 10.4049/jimmunol.170.10.5159] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Opportunistic infections are common in HIV-infected patients; they activate HIV replication and contribute to disease progression. In the present study we examined the role of Toll-like receptor 2 (TLR2) and TLR9 in HIV-long terminal repeat (HIV-LTR) trans-activation and assessed whether TLR4 synergized with TLR2 or TLR9 to induce HIV replication. Soluble Mycobacterium tuberculosis factor (STF) and phenol-soluble modulin from Staphylococcus epidermidis induced HIV-LTR trans-activation in human microvessel endothelial cells cotransfected with TLR2 cDNA. Stimulation of ex vivo spleen cells from HIV-1 transgenic mice with TLR4, TLR2, and TLR9 ligands (LPS, STF, and CpG DNA, respectively) induced p24 Ag production in a dose-dependent manner. Costimulation of HIV-1 transgenic mice spleen cells with LPS and STF or CpG DNA induced TNF-alpha and IFN-gamma production in a synergistic manner and p24 production in an additive fashion. In the THP-1 human monocytic cell line stably expressing the HIV-LTR-luciferase construct, LPS and STF also induced HIV-LTR trans-activation in an additive manner. This is the first time that TLR2 and TLR9 and costimulation of TLRs have been shown to induce HIV replication. Together these results underscore the importance of TLRs in bacterial Ag- and CpG DNA-induced HIV-LTR trans-activation and HIV replication. These observations may be important in understanding the role of the innate immune system and the molecular mechanisms involved in the increased HIV replication and HIV disease progression associated with multiple opportunistic infections.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Adjuvants, Immunologic/metabolism
- Adjuvants, Immunologic/physiology
- Animals
- Antigens, Differentiation/pharmacology
- Cell Line, Transformed
- Cells, Cultured
- Cytokines/biosynthesis
- DNA-Binding Proteins/metabolism
- DNA-Binding Proteins/physiology
- HIV Long Terminal Repeat/genetics
- HIV Long Terminal Repeat/immunology
- HIV-1/genetics
- HIV-1/immunology
- HIV-1/physiology
- Humans
- Ligands
- Lipopolysaccharides/pharmacology
- Membrane Glycoproteins/metabolism
- Membrane Glycoproteins/physiology
- Mice
- Mice, Transgenic
- Mycobacterium tuberculosis/immunology
- Myeloid Differentiation Factor 88
- Receptors, Cell Surface/metabolism
- Receptors, Cell Surface/physiology
- Receptors, Immunologic
- Signal Transduction/genetics
- Signal Transduction/immunology
- Spleen/cytology
- Spleen/immunology
- Spleen/metabolism
- Spleen/virology
- Th1 Cells/immunology
- Th1 Cells/metabolism
- Toll-Like Receptor 2
- Toll-Like Receptor 4
- Toll-Like Receptor 9
- Toll-Like Receptors
- Transcriptional Activation/immunology
- Tumor Cells, Cultured
- Up-Regulation/genetics
- Up-Regulation/immunology
- Virus Replication/genetics
- Virus Replication/immunology
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Affiliation(s)
- Ozlem Equils
- Division of Pediatric Infectious Diseases, Steven Spielberg Pediatric Research Center, Burns and Allen Research Institute, Cedars-Sinai Medical Center, University of California School of Medicine, Los Angeles, CA 90048, USA.
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21
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Schito ML, Goel A, Song Y, Inman JK, Fattah RJ, Rice WG, Turpin JA, Sher A, Appella E. In vivo antiviral activity of novel human immunodeficiency virus type 1 nucleocapsid p7 zinc finger inhibitors in a transgenic murine model. AIDS Res Hum Retroviruses 2003; 19:91-101. [PMID: 12639244 DOI: 10.1089/088922203762688595] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Control of human immunodeficiency virus through the use of inexpensive chemotherapeutics, with minimal side effects and decreased potential for engendering resistant virus, is a long-term therapeutic goal. In principle, this goal can be accomplished if viral replication in reservoirs of chronically and latently infected cells is addressed. As a first step, we have developed novel antiviral compounds based on a 2-mercaptobenzamide thioester chemotype, including the pyridinioalkanoyl thioesters, which specifically target the zinc fingers of the human immunodeficiency virus nucleocapsid protein (NCp7). Using these compounds in a murine transgenic model, in which infectious human immunodeficiency virus is induced from an integrated provirus, we show inhibition of transgenic spleen cell p24 expression with potencies comparable to acute infection assays using human peripheral blood lymphocytes. More importantly, transgenic mice treated in vivo with two 2-mercaptobenzamide thioesters expressed significantly lower plasma p24, and splenocytes from these animals produced fewer infectious virions. Thus, these thioesters may provide an effective means for inhibiting the expression of human immunodeficiency virus from integrated viral reservoirs.
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Affiliation(s)
- Marco L Schito
- Chemical Immunology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland 20892, USA.
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22
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Lieberman LA, Hunter CA. The role of cytokines and their signaling pathways in the regulation of immunity to Toxoplasma gondii. Int Rev Immunol 2002; 21:373-403. [PMID: 12486820 DOI: 10.1080/08830180213281] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The development of a strong cellular immune response is critical for the control of the intracellular pathogen Toxoplasma gondii. This occurs by activation of a complex, integrated immune response, which utilizes cells of the innate and adaptive immune systems. In the last two decades there have been major advances in our understanding of the role of cytokines in the initiation and maintenance of protective immunity to T. gondii, and IFN-gamma has been identified as the major mediator of resistance to this pathogen. This article provides an overview of the biology of toxoplasmosis and focuses on the pivotal role of cytokines and their signaling pathways during infection. It also addresses the role of cytokines in modulating other immune functions that are critical in determining the balance between a protective and a pathological immune response.
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Affiliation(s)
- Linda A Lieberman
- Department of Pathobiology, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania, USA
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23
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Caamaño J, Hunter CA. NF-kappaB family of transcription factors: central regulators of innate and adaptive immune functions. Clin Microbiol Rev 2002; 15:414-29. [PMID: 12097249 PMCID: PMC118079 DOI: 10.1128/cmr.15.3.414-429.2002] [Citation(s) in RCA: 387] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Transcription factors of the Rel/NF-kappaB family are activated in response to signals that lead to cell growth, differentiation, and apoptosis, and these proteins are critical elements involved in the regulation of immune responses. The conservation of this family of transcription factors in many phyla and their association with antimicrobial responses indicate their central role in the regulation of innate immunity. This is illustrated by the association of homologues of NF-kappaB, and their regulatory proteins, with resistance to infection in insects and plants (M. S. Dushay, B. Asling, and D. Hultmark, Proc. Natl. Acad. Sci. USA 93:10343-10347, 1996; D. Hultmark, Trends Genet. 9:178-183, 1993; J. Ryals et al., Plant Cell 9:425-439, 1997). The aim of this review is to provide a background on the biology of NF-kappaB and to highlight areas of the innate and adaptive immune response in which these transcription factors have a key regulatory function and to review what is currently known about their roles in resistance to infection, the host-pathogen interaction, and development of human disease.
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Affiliation(s)
- Jorge Caamaño
- Department of Pathobiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6008, USA
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24
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Keppler OT, Welte FJ, Ngo TA, Chin PS, Patton KS, Tsou CL, Abbey NW, Sharkey ME, Grant RM, You Y, Scarborough JD, Ellmeier W, Littman DR, Stevenson M, Charo IF, Herndier BG, Speck RF, Goldsmith MA. Progress toward a human CD4/CCR5 transgenic rat model for de novo infection by human immunodeficiency virus type 1. J Exp Med 2002; 195:719-36. [PMID: 11901198 PMCID: PMC2193739 DOI: 10.1084/jem.20011549] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The development of a permissive small animal model for the study of human immunodeficiency virus type (HIV)-1 pathogenesis and the testing of antiviral strategies has been hampered by the inability of HIV-1 to infect primary rodent cells productively. In this study, we explored transgenic rats expressing the HIV-1 receptor complex as a susceptible host. Rats transgenic for human CD4 (hCD4) and the human chemokine receptor CCR5 (hCCR5) were generated that express the transgenes in CD4(+) T lymphocytes, macrophages, and microglia. In ex vivo cultures, CD4(+) T lymphocytes, macrophages, and microglia from hCD4/hCCR5 transgenic rats were highly susceptible to infection by HIV-1 R5 viruses leading to expression of abundant levels of early HIV-1 gene products comparable to those found in human reference cultures. Primary rat macrophages and microglia, but not lymphocytes, from double-transgenic rats could be productively infected by various recombinant and primary R5 strains of HIV-1. Moreover, after systemic challenge with HIV-1, lymphatic organs from hCD4/hCCR5 transgenic rats contained episomal 2-long terminal repeat (LTR) circles, integrated provirus, and early viral gene products, demonstrating susceptibility to HIV-1 in vivo. Transgenic rats also displayed a low-level plasma viremia early in infection. Thus, transgenic rats expressing the appropriate human receptor complex are promising candidates for a small animal model of HIV-1 infection.
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Affiliation(s)
- Oliver T Keppler
- Gladstone Institute of Virology and Immunology, School of Medicine, University of California at San Francisco, San Francisco, CA 94141, USA
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25
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Shapira S, Speirs K, Gerstein A, Caamano J, Hunter CA. Suppression of NF-kappaB activation by infection with Toxoplasma gondii. J Infect Dis 2002; 185 Suppl 1:S66-72. [PMID: 11865442 DOI: 10.1086/338000] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The interaction of host cells with microbial products or their invasion by pathogens frequently results in activation of the NF-kappaB family of transcription factors. The studies presented here reveal that in vivo, infection with Toxoplasma gondii results in the activation of NF-kappaB. To determine whether host cells could activate NF-kappaB in response to invasion by T. gondii, Western blots, immunofluorescence, and electrophoretic mobility shift assays were used to assess the response of host cells to infection. In these studies, infection of macrophages or fibroblasts with T. gondii did not result in the activation of NF-kappaB. In addition, the ability of lipopolysaccharide to activate NF-kappaB was impaired in cultures of macrophages infected with T. gondii. Together, these data demonstrate that invasion of cells by T. gondii does not lead to the activation of NF-kappaB and suggest that the parasite may actively interfere with the pathways that lead to NF-kappaB activation.
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Affiliation(s)
- S Shapira
- Department of Pathobiology, University of Pennsylvania, Philadelphia, PA 19104-6008, USA
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26
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Dickie P, Roberts A, Lee R. A defect in HIV‐1 transgenic murine macrophages results in deficient nitric oxide production. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.4.592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Peter Dickie
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Amanda Roberts
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Raymond Lee
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
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27
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Abstract
Protozoan parasites which reside inside a host cell avoid direct destruction by the immune system of the host. The infected cell, however, still has the capacity to counteract the invasive pathogen by initiating its own death, a process which is called programmed cell death or apoptosis. Apoptotic cells are recognised and phagocytosed by macrophages and the parasite is potentially eliminated together with the infected cell. This potent defence mechanism of the host cell puts strong selective pressure on the parasites which have, in turn, evolved strategies to modulate the apoptotic program of the host cell to their favour. Within the last decade, the existence of cellular signalling pathways which inhibit the apoptotic machinery has been demonstrated. It is not surprising that intracellular pathogens subvert these pathways to ensure their own survival in the infected cell. Molecular mechanisms which interfere with apoptotic pathways have been studied extensively for viruses and parasitic bacteria, but protozoan parasites have come into focus only recently. Intracellular protozoan parasites which have been reported to inhibit the apoptotic program of the host cell, are Toxoplasma gondii, Trypanosoma cruzi, Leishmania sp., Theileria sp., Cryptosporidium parvum, and the microsporidian Nosema algerae. Although these parasites differ in their mechanism of host cell entry and in their final intracellular localisation, they might activate similar pathways in their host cells to inhibit apoptosis. In this respect, two families of molecules, which are known for their capacity to interrupt the apoptotic program, are currently discussed in the literature. First, the expression of heat shock proteins is often induced upon parasite infection and can directly interfere with molecules of the cellular death machinery. Secondly, a more indirect effect is attributed to the parasite-dependent activation of NF-kappaB, a transcription factor that regulates the transcription of anti-apoptotic molecules.
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Affiliation(s)
- V T Heussler
- Molecular Pathology, Institute of Animal Pathology, University of Berne, Switzerland.
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28
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Chougnet C, Freitag C, Schito M, Thomas EK, Sher A, Shearer GM. In vivo CD40-CD154 (CD40 ligand) interaction induces integrated HIV expression by APC in an HIV-1-transgenic mouse model. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:3210-7. [PMID: 11207274 DOI: 10.4049/jimmunol.166.5.3210] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Because of their relative resistance to viral cytopathic effects, APC can provide an alternative reservoir for latently integrated HIV. We used an HIV-transgenic mouse model in which APC serve as the major source of inducible HIV expression to study mechanisms by which integrated virus can be activated in these cells. When admixed with transgenic APC, activated T lymphocytes provided a major contact-dependent stimulus for viral protein expression in vitro. Using blocking anti-CD154 mAb as well as CD154-deficient T cells, the HIV response induced by activated T lymphocytes was demonstrated to require CD40-CD154 interaction. The role of this pathway in the induction of HIV expression from APC in vivo was further studied in an experimental model involving infection of the HIV-transgenic mice with PLASMODIUM: chabaudi parasites. Enhanced viral production by dendritic cells and macrophages in infected mice was associated with up-regulated CD40 expression. More importantly, in vivo treatment with blocking anti-CD154 mAb markedly reduced viral expression in P. chabaudi-infected animals. Together, these findings indicate that immune activation of integrated HIV can be driven by the costimulatory interaction of activated T cells with APC. Because chronic T cell activation driven by coinfections as well as HIV-1 itself is a characteristic of HIV disease, this pathway may be important in sustaining viral expression from APC reservoirs.
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Affiliation(s)
- C Chougnet
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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29
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Tanaka J, Ozaki H, Yasuda J, Horai R, Tagawa Y, Asano M, Saijo S, Imai M, Sekikawa K, Kopf M, Iwakura Y. Lipopolysaccharide-induced HIV-1 expression in transgenic mice is mediated by tumor necrosis factor-alpha and interleukin-1, but not by interferon-gamma nor interleukin-6. AIDS 2000; 14:1299-307. [PMID: 10930143 DOI: 10.1097/00002030-200007070-00001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND As serum HIV-1 load correlates well with the prognosis of the disease, it is suggested that the viral load is one of the major determinants of the disease progression of AIDS. Accordingly, HIV-1 activation mechanisms were extensively studied in vitro, and involvement of cytokines including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6 and interferon (IFN)-gamma has been suggested in this process. However, so far the roles of these cytokines in the HIV-1 expression in vivo have not been well elucidated because of the lack of appropriate animal disease models. OBJECTIVE To elucidate the roles of cytokines in HIV-1 activation in vivo. DESIGN AND METHODS Transgenic mice carrying a defective HIV-1 genome were used as a model for HIV-1 carriers. In order to examine the possible involvement of cytokines in HIV-1 expression, TNF-alpha-, IL-1-, IL-6- and IFN-gamma-deficient HIV-1 transgenic mice, were produced and HIV-1 expression was analyzed after activation with bacterial lipopolysaccharides (LPS). RESULTS HIV-1 expression in the transgenic mouse spleen was activated 10- to 20-fold by LPS, and the serum p24 Gag protein levels reached 400 pg/ml, which is nearly equal to the levels that occur in AIDS patients. However, this augmentation was suppressed by 60% in TNF-alpha-deficient mice and by 40% in IL-1alpha/beta-deficient mice. In contrast, no suppression was observed in either IL-6-, IFN-gamma-, IL-1alpha, or IL-1beta-deficient mice. CONCLUSIONS Results suggest that TNF-alpha and IL-1 play important roles in HIV-1 gene activation and selective suppression of these cytokines could improve clinical prognosis and potentially slow progression of the disease.
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Affiliation(s)
- J Tanaka
- Center for Experimental Medicine, Institute of Medical Science, University of Tokyo, Japan
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30
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Dickie P. Nef modulation of HIV type 1 gene expression and cytopathicity in tissues of HIV transgenic mice. AIDS Res Hum Retroviruses 2000; 16:777-90. [PMID: 10826484 DOI: 10.1089/088922200308774] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Transgenic mice bearing HIV-1 proviral DNA deleted in the gag/pol region (HIVd1443 mice) model a chronic, nonproductive form of viral gene expression in various cell types including macrophages. They display a disease phenotype that includes HIV-associated nephropathy (HIVAN), congenital cataracts, papillomatosis, and growth failure. The role of HIV-1 Nef in viral gene regulation and the development of disease was explored in mice bearing an isogenic HIV transgene in which nef was mutated by frameshift mutation. Like its Nef+ counterpart, HIVd1443[Nef-] mice expressed HIV gene products in the skin, muscle, kidney, and peritoneal macrophages. While these mice did not develop cataracts, papillomatous skin lesions, or display any apparent growth defect, they did develop HIVAN. Nef expression was introduced to HIVd1443[Nef-] mice through breeding to mice bearing an HIV LTR-linked nef transgene. Nef-complemented HIVd1443[Nef-] mice had reduced levels of viral gene products in the muscle and kidney. In contrast, HIV gene expression in the skin of these mice remained high and papillomatous lesions emerged that were more severe than those on wild-type HIVd1443 mice. Still, Nef had a negative effect on LPS-induced viral gene expression in visibly normal skin. In comparisons of peritoneal macrophages, viral RNA expression was significantly reduced in resident macrophages of Nef+ mice. HIV inflammatory macrophages expressed viral genes and displayed an altered FACS profile. In particular, Nef+ populations were marked by an increased proportion of F4/80med/Mac-1-cells as well as fewer Mac-1 cells and reduced F4/80 staining. This HIV proviral transgenic model has demonstrated the capacity of HIV-1 Nef to contribute to HIV cytopathicity by altering cellular maturation and viral gene expression in vivo.
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Affiliation(s)
- P Dickie
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Canada.
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31
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Haque S, Hanna S, Gharbi S, Franck J, Dumon H, Haque A. Infection of mice by a Toxoplasma gondii isolate from an AIDS patient: virulence and activation of hosts' immune responses are independent of parasite genotype. Parasite Immunol 1999; 21:649-57. [PMID: 10583867 DOI: 10.1046/j.1365-3024.1999.00273.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Virulence of a Toxoplasma gondii isolate from an AIDS patient (designated as PTN) was compared with that of PLK, a variant of P-strain. Virulence was assessed in term of host survival upon inoculation in different strains of mice. All C57BL/6 mice died of acute toxoplasmosis by 7-10 days following intraperitoneal infection with 1 x 105 tachyzoites of PTN and 40% of BALB/c died on day 23 of infection, whereas 100% CBA/J infected with the same dose of PTN survived, as did outbred Swiss Webster mice. All C57BL/6, BALB/c, CBA/J, or Swiss Webster died of acute toxoplasmosis by 3-9 days postinfection upon inoculation with same dose of tachyzoites of the PLK strain. Further studies in CBA/J mice demonstrated that mice infected with PTN elicited a significantly higher lymphoproliferative response to crosslinked anti-CD3 mAb or Con A than PLK infected mice, and augmented production of TNFalpha, lower levels of nitrite and a higher number of NK cells. Genetical analysis indicated that both PLK and PTN strains of T. gondii are from type ll. Interestingly, being of the same genotype, the later showed less virulence upon inoculation in mice and had greater capacity to activate host immune system than the PLK strain.
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Affiliation(s)
- S Haque
- Department of Medicine and Microbiology, Dartmouth Medical School Hanover, NH 03755, USA; Immunologie et Génétique Des Maladies Parasitaires, INSERM U 399, Universite de Mediterranée Faculté de Médecine, 13385 Marseille, France
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32
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Fernandez PC, Machado J, Heussler VT, Botteron C, Palmer GH, Dobbelaere DA. The inhibition of NF-kappaB activation pathways and the induction of apoptosis by dithiocarbamates in T cells are blocked by the glutathione precursor N-acetyl-L-cysteine. Biol Chem 1999; 380:1383-94. [PMID: 10661865 DOI: 10.1515/bc.1999.178] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Nuclear factor-kappaB regulates genes that control immune and inflammatory responses and are involved in the pathogenesis of several diseases, including AIDS and cancer. It has been proposed that reactive oxygen intermediates participate in NF-kappaB activation pathways, and compounds with putative antioxidant activity such as N-acetyl-L-cysteine (NAC) and pyrrolidine dithiocarbamate (PDTC) have been used interchangeably to demonstrate this point. We examined their effects, separately and combined, on different stages of the NF-kappaB activation pathway, in primary and in transformed T cells. We show that NAC, contrary to its reported role as an NF-kappaB inhibitor, can actually enhance rather than inhibit IkappaB degradation and, most importantly, show that in all cases NAC exerts a dominant antagonistic effect on PDTC-mediated NF-kappaB inhibition. This was observed at the level of IkappaB degradation, NF-kappaB DNA binding, and HIV-LTR-driven reporter gene expression. NAC also counteracted growth arrest and apoptosis induced by dithiocarbamates. Antagonistic effects were further observed at the level of jun-NH2-terminal kinase, p38 and ATF-2 activation. Our findings argue against the widely accepted assumption that NAC inhibits all NF-kappaB activation pathways and shows that two compounds, previously thought to function through a common inhibitory mechanism, can also have antagonistic effects.
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Affiliation(s)
- P C Fernandez
- Laboratory of Molecular Pathology, Institute of Animal Pathology, University of Berne, Switzerland
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33
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Cohen SS, Li C, Ding L, Cao Y, Pardee AB, Shevach EM, Cohen DI. Pronounced acute immunosuppression in vivo mediated by HIV Tat challenge. Proc Natl Acad Sci U S A 1999; 96:10842-7. [PMID: 10485913 PMCID: PMC17970 DOI: 10.1073/pnas.96.19.10842] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
HIV infection is accompanied by an early immune dysfunction limiting host control of virus and likely contributing to difficulties in achieving a successful vaccine against HIV. We report here that the HIV Tat protein is strongly immunosuppressive, both immediately after immunization of mice with soluble protein (sTat), and in seroconverting humans, and propose that Tat-induced suppression cripples immune surveillance to HIV infection. We show that macrophages are sensitive to sTat stimulation at concentrations 1,000-fold lower (500 pM) than T cells, and this stimulation is accompanied by the immunosuppressive induction of Fas ligand on the macrophage. T cell proliferative defects induced by sTat in vitro can be completely (at lower concentrations of sTat) or partially (at higher concentrations) reversed by antagonists to Fas/Fas ligand interaction. We further report a method to preserve immunogenicity while inactivating Tat immunosuppression through oxidation, which advances the use of oxidized Tat as a component of an anti-HIV vaccine. These observations define additional methods to study the immunosuppressive functions of sTat that now may be rapidly applied to primary isolates from individuals with differing clinical courses. Our findings have immediate relevance for vaccine development, by describing and supporting a strategy that includes inactivated sTat in a multicomponent, anti-HIV vaccine.
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MESH Headings
- AIDS Vaccines/metabolism
- Animals
- Cells, Cultured
- Dose-Response Relationship, Drug
- Fas Ligand Protein
- Flow Cytometry
- Gene Products, tat/immunology
- Gene Products, tat/metabolism
- Gene Products, tat/pharmacology
- HIV Infections/immunology
- HIV Infections/metabolism
- Humans
- Immune Tolerance/physiology
- Immunoblotting
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/metabolism
- Macrophages/drug effects
- Macrophages/immunology
- Macrophages/metabolism
- Membrane Glycoproteins/antagonists & inhibitors
- Membrane Glycoproteins/metabolism
- Mice
- Mice, Inbred BALB C
- Recombinant Proteins/pharmacology
- T-Lymphocytes, Helper-Inducer/drug effects
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- S S Cohen
- Dermatology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Doherty TM, Chougnet C, Schito M, Patterson BK, Fox C, Shearer GM, Englund G, Sher A. Infection of HIV-1 Transgenic Mice with Mycobacterium avium Induces the Expression of Infectious Virus Selectively from a Mac-1-Positive Host Cell Population. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.3.1506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Infection of HIV-1-transgenic mice with Mycobacterium avium, a common opportunistic pathogen in AIDS patients, was shown to result in increased tissue expression of viral specific transcripts. Moreover, by coculturing splenocytes from the transgenic animals with human T cells it was possible to demonstrate that the elevation in HIV-1 mRNA triggered by M. avium infection reflects increased production of infectious virions. Viral immune activation was also shown to correlate with a marked elevation of p24 in supernatants of ex vivo-cultured tissues and, more importantly, in systemic increases in the HIV-1 protein in plasma. Interestingly, these tissue and systemic p24 responses were found to be differentially regulated. Thus, while in vitro p24 production by cultured splenocytes increased concurrently with bacterial loads during the first 6 wk of infection, levels of the Ag in plasma actually decreased. In situ localization experiments together with FACS analysis of HIV-1-expressing splenocytes indicated that virus production is restricted largely to cells of the monocyte/macrophage lineage. Indeed, in vitro p24 expression by cells from noninfected transgenic mice was up-regulated by polyclonal stimulation of macrophages but not T cells. Together these results underscore the importance of the macrophage reservoir in persistent virus expression and establish a convenient and relevant animal model for studying the factors responsible for immune activation of HIV-1 induced by mycobacterial as well as other common coinfections encountered by AIDS patients.
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Affiliation(s)
- T. Mark Doherty
- *Immunobiology Section, Laboratory of Parasitic Diseases, and
| | - Claire Chougnet
- ‡Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Marco Schito
- *Immunobiology Section, Laboratory of Parasitic Diseases, and
| | - Bruce K. Patterson
- §Department of Obstetrics/Gynecology and Medicine, Division of Infectious Diseases, Northwestern University Medical School, Chicago IL 60611; and
| | - Cecil Fox
- ¶Molecular Histology, Inc., Gaithersburg, MD 20879
| | - Gene M. Shearer
- ‡Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - George Englund
- †Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, and
| | - Alan Sher
- *Immunobiology Section, Laboratory of Parasitic Diseases, and
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Jilling T, Haddad IY, Cheng SH, Matalon S. Nitric oxide inhibits heterologous CFTR expression in polarized epithelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:L89-96. [PMID: 10409234 DOI: 10.1152/ajplung.1999.277.1.l89] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (. NO) has been implicated in a wide range of autocrine and paracrine signaling mechanisms. Herein, we assessed the role of exogenous. NO in the modulation of heterologous gene expression in polarized kidney epithelial cells (LLC-PK(1)) that were stably transduced with a cDNA encoding human wild-type cystic fibrosis transmembrane conductance regulator (CFTR) under the control of a heavy metal-sensitive metallothionein promoter (LLC-PK(1)-WTCFTR). Exposure of these cells to 125 microM DETA NONOate at 37 degrees C for 24 h (a chemical. NO donor) diminished Zn(2+)-induced and uninduced CFTR protein levels by 43.3 +/- 5.1 and 34.4 +/- 17.1% from their corresponding control values, respectively. These changes did not occur if red blood cells, effective scavengers of. NO, were added to the medium. Exposure to. NO did not alter lactate dehydrogenase release in the medium or the extent of apoptosis. Coculturing LLC-PK(1)-WTCFTR cells with murine fibroblasts that were stably transduced with the human inducible. NO synthase cDNA gene also inhibited CFTR protein expression in a manner that was antagonized by 1 mM N(G)-monomethyl-L-arginine in the medium. Pretreatment of LLC-PK(1)-WTCFTR with ODQ, an inhibitor of guanylyl cyclase, did not affect the ability of. NO to inhibit heterologous CFTR expression; furthermore, 8-bromo-cGMP had no effect on heterologous CFTR expression. These data indicate that. NO impairs the heterologous expression of CFTR in epithelial cells at the protein level via cGMP-independent mechanisms.
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Affiliation(s)
- T Jilling
- Department of Pediatrics, The Evanston Hospital, Northwestern University Medical School, Evanston, Illinois 60201, USA
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Heussler VT, Machado J, Fernandez PC, Botteron C, Chen CG, Pearse MJ, Dobbelaere DA. The intracellular parasite Theileria parva protects infected T cells from apoptosis. Proc Natl Acad Sci U S A 1999; 96:7312-7. [PMID: 10377411 PMCID: PMC22082 DOI: 10.1073/pnas.96.13.7312] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Parasites have evolved a plethora of strategies to ensure their survival. The intracellular parasite Theileria parva secures its propagation and spreads through the infected animal by infecting and transforming T cells, inducing their continuous proliferation and rendering them metastatic. In previous work, we have shown that the parasite induces constitutive activation of the transcription factor NF-kappaB, by inducing the constitutive degradation of its cytoplasmic inhibitors. The biological significance of NF-kappaB activation in T. parva-infected cells, however, has not yet been defined. Cells that have been transformed by viruses or oncogenes can persist only if they manage to avoid destruction by the apoptotic mechanisms that are activated on transformation and that contribute to maintain cellular homeostasis. We now demonstrate that parasite-induced NF-kappaB activation plays a crucial role in the survival of T. parva-transformed T cells by conveying protection against an apoptotic signal that accompanies parasite-mediated transformation. Consequently, inhibition of NF-kappaB nuclear translocation and the expression of dominant negative mutant forms of components of the NF-kappaB activation pathway, such as IkappaBalpha or p65, prompt rapid apoptosis of T. parva-transformed T cells. Our findings offer important insights into parasite survival strategies and demonstrate that parasite-induced constitutive NF-kappaB activation is an essential step in maintaining the transformed phenotype of the infected cells.
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Affiliation(s)
- V T Heussler
- Laboratory of Immunopathology, Institute of Animal Pathology, University of Berne, CH-3012 Berne, Switzerland
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37
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Moriuchi M, Moriuchi H, Turner W, Fauci AS. Exposure to bacterial products renders macrophages highly susceptible to T-tropic HIV-1. J Clin Invest 1998; 102:1540-50. [PMID: 9788967 PMCID: PMC509004 DOI: 10.1172/jci4151] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Microbial coinfections variably influence HIV-1 infection through immune activation or direct interaction of microorganisms with HIV-1 or its target cells. In this study, we investigated whether exposure of macrophages to bacterial products impacts the susceptibility of these cells to HIV-1 of different cellular tropisms. We demonstrate that () macrophages exposed to bacterial cell wall components such as lipopolysaccharide (LPS) (Gram-negative rods), lipoteichoic acid (Gram-positive cocci), and lipoarabinomannan (Mycobacteria) become highly susceptible to T cell (T)-tropic HIV-1 (which otherwise poorly replicate in macrophages) and variably susceptible to macrophage (M)-tropic HIV-1; () LPS-stimulated macrophages secrete a number of soluble factors (i.e., chemokines, interferon, and proinflammatory cytokines) that variably affect HIV infection of macrophages, depending on the virus phenotype in question; and () LPS-stimulated macrophages express CCR5 (a major coreceptor for M-tropic HIV-1) at lower levels and CXCR4 (a major coreceptor for T-tropic HIV-1) at higher levels compared with unstimulated macrophages. We hypothesize that a more favorable environment for T-tropic HIV-1 and a less favorable or even unfavorable environment for M-tropic HIV-1 secondary to exposure of macrophages to those bacterial products may accerelate a transition from M- to T-tropic viral phenotype, which is indicative of disease progression.
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Affiliation(s)
- M Moriuchi
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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38
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Wahl SM, Greenwell-Wild T, Peng G, Hale-Donze H, Doherty TM, Mizel D, Orenstein JM. Mycobacterium avium complex augments macrophage HIV-1 production and increases CCR5 expression. Proc Natl Acad Sci U S A 1998; 95:12574-9. [PMID: 9770527 PMCID: PMC22872 DOI: 10.1073/pnas.95.21.12574] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/1998] [Accepted: 06/26/1998] [Indexed: 11/18/2022] Open
Abstract
Infection with HIV-1 results in pronounced immune suppression and susceptibility to opportunistic infections (OI). Reciprocally, OI augment HIV-1 replication. As we have shown for Mycobacterium avium complex (MAC) and Pneumocystis carinii, macrophages infected with opportunistic pathogens and within lymphoid tissues containing OI, exhibit striking levels of viral replication. To explore potential underlying mechanisms for increased HIV-1 replication associated with coinfection, blood monocytes were exposed to MAC antigens (MAg) or viable MAC and their levels of tumor necrosis factor alpha (TNFalpha) and HIV-1 coreceptors monitored. MAC enhanced TNFalpha production in vitro, consistent with its expression in coinfected lymph nodes. Using a polyclonal antibody to the CCR5 coreceptor that mediates viral entry of macrophage tropic HIV-1, a subset of unstimulated monocytes was shown to be CCR5-positive by fluorescence-activated cell sorter analysis. After stimulation with MAg or infection with MAC, CCR5 expression was increased at both the mRNA level and on the cell surface. Up-regulation of CCR5 by MAC was not paralleled by an increase in the T cell tropic coreceptor, CXCR4. Increases in NF-kappaB, TNFalpha, and CCR5 were consistent with the enhanced production of HIV-1 in MAg-treated adherent macrophage cultures as measured by HIV-1 p24 levels. Increased CCR5 was also detected in coinfected lymph nodes as compared with tissues with only HIV-1. The increased production of TNFalpha, together with elevated expression of CCR5, provide potential mechanisms for enhanced infection and replication of HIV-1 by macrophages in OI-infected cells and tissues. Consequently, treating OI may inhibit not only the OI-induced pathology, but also limit the viral burden.
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Affiliation(s)
- S M Wahl
- Oral Infection and Immunity Branch, National Institute of Dental Research, 30 Convent Drive, MSC 4352, MD 20892, USA.
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Denkers EY, Gazzinelli RT. Regulation and function of T-cell-mediated immunity during Toxoplasma gondii infection. Clin Microbiol Rev 1998; 11:569-88. [PMID: 9767056 PMCID: PMC88897 DOI: 10.1128/cmr.11.4.569] [Citation(s) in RCA: 529] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The intracellular protozoan Toxoplasma gondii is a widespread opportunistic parasite of humans and animals. Normally, T. gondii establishes itself within brain and skeletal muscle tissues, persisting for the life of the host. Initiating and sustaining strong T-cell-mediated immunity is crucial in preventing the emergence of T. gondii as a serious pathogen. The parasite induces high levels of gamma interferon (IFN-gamma) during initial infection as a result of early T-cell as well as natural killer (NK) cell activation. Induction of interleukin-12 by macrophages is a major mechanism driving early IFN-gamma synthesis. The latter cytokine, in addition to promoting the differentiation of Th1 effectors, is important in macrophage activation and acquisition of microbicidal functions, such as nitric oxide release. During chronic infection, parasite-specific T lymphocytes release high levels of IFN-gamma, which is required to prevent cyst reactivation. T-cell-mediated cytolytic activity against infected cells, while easily demonstrable, plays a secondary role to inflammatory cytokine production. While part of the clinical manifestations of toxoplasmosis results from direct tissue destruction by the parasite, inflammatory cytokine-mediated immunopathologic changes may also contribute to disease progression.
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Affiliation(s)
- E Y Denkers
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401, USA.
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Yap GS, Scharton-Kersten T, Charest H, Sher A. Decreased Resistance of TNF Receptor p55- and p75-Deficient Mice to Chronic Toxoplasmosis Despite Normal Activation of Inducible Nitric Oxide Synthase In Vivo. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.3.1340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The importance of TNF-α in host defense to the intracellular parasite, Toxoplasma gondii, was investigated in mice lacking both the p55 and p75 receptors for this cytokine. Upon i.p. infection with the avirulent ME49 strain, knockout mice were capable of limiting acute i.p. infection, but succumbed within 3 to 4 wk to a fulminant necrotizing encephalitis. Receptor-deficient mice harbored higher cyst burdens and exhibited uncontrolled tachyzoite replication in the brain. The lack of TNF receptors did not adversely affect the development of a type 1 IFN-γ response. In vitro studies with peritoneal macrophages stimulated with IFN-γ and tachyzoites indicated that under limiting concentrations of IFN-γ, nitric oxide-mediated toxoplasmastatic activity is TNF-α dependent. However, this requirement is overcome by increasing the dose of IFN-γ. Furthermore, both ex vivo and in vivo studies demonstrated that inducible nitric oxide synthase induction in the peritoneal cavity and brain is unimpaired in receptor-deficient mice. Thus, TNF-dependent immune control of T. gondii expansion in the brain involves an effector function distinct from inducible nitric oxide synthase activation.
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Affiliation(s)
- George S. Yap
- Immunobiology Section, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Tanya Scharton-Kersten
- Immunobiology Section, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Hugues Charest
- Immunobiology Section, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Alan Sher
- Immunobiology Section, Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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Sher A, Gazzinelli RT, Jankovic D, Scharton-Kersten T, Yap G, Doherty TM, Wynn T. Cytokines as determinants of disease and disease interactions. Braz J Med Biol Res 1998; 31:85-7. [PMID: 9686183 DOI: 10.1590/s0100-879x1998000100011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The immune response to pathogens results in both host resistance and immunopathology. Cytokines and in particular those lymphokines produced by Th1 and Th2 cells play a key role in determining the balance between these two immunologic outcomes. Recent data suggest that interleukin-10, a product of both Th2 cells and macrophages, protects the host against excessive immunopathology. The cytokine environment generated by different pathogens may also influence the course and outcome of infections with unrelated organisms. This relationship may be particularly important in the case of HIV-1 where prior Th1 or Th2 biases established by helminth or intracellular infections may influence either initial viral susceptibility or drive progression to AIDS through immune activation.
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Affiliation(s)
- A Sher
- Immunobiology Section, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA
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42
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Reiter-Owona I, Bialek R, Rockstroh JK, Seitz HM. The probability of acquiring primary Toxoplasma infection in HIV-infected patients: results of an 8-year retrospective study. Infection 1998; 26:20-5. [PMID: 9505175 DOI: 10.1007/bf02768747] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
There is much hope that HIV-infected patients and AIDS patients can reckon with a prolonged survival in future. The increased survival of AIDS patients with positive Toxoplasma serology is not necessarily associated with an increased risk of developing Toxoplasma encephalitis. For HIV-infected patients with negative Toxoplasma serology, the probability of acquiring a primary Toxoplasma infection in highly endemic areas such as Germany had not been studied to date. One hundred eighty-three HIV-infected patients were followed up between 1987 and 1995 in a retrospective study. Within the cohort, 95% of the patients were male and 83% haemophiliacs. The initial (1987) and final (1995) prevalence rate of Toxoplasma antibodies was 33.3% and 36.6%, respectively. The annual rise of the primary infection rate was calculated as 0.41%. The dye test was used for the detection of Toxoplasma-specific antibodies. This assay proved to be reliable and stable during long-term observation. The rate of primary toxoplasmosis found in this long-term study was not higher than that of pregnant women in Germany. Chemoprophylactic measurements for seronegative HIV-infected patients are therefore not recommended, but regular serological screening to detect seroconverters is.
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Affiliation(s)
- I Reiter-Owona
- Institut für Medizinische Parasitologie, Universität Bonn, Germany
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43
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Dickie P, Mounts P, Purcell D, Miller G, Fredrickson T, Chang LJ, Martin MA. Myopathy and spontaneous Pasteurella pneumotropica-induced abscess formation in an HIV-1 transgenic mouse model. JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES AND HUMAN RETROVIROLOGY : OFFICIAL PUBLICATION OF THE INTERNATIONAL RETROVIROLOGY ASSOCIATION 1996; 13:101-16. [PMID: 8862275 DOI: 10.1097/00042560-199610010-00001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In an effort to augment human immunodeficiency virus type 1 (HIV-1) gene expression in transgenic mice, an infectious proviral DNA clone was modified by deleting the two NF kappa B binding sites and some adjacent upstream LTR sequences and replacing them with the core enhancer of Moloney murine leukemia virus (MLV). Two independent lines of MLV/HIV transgenic mice were established that expressed HIV-1-specific RNA in lymphoid tissue, striated skeletal muscle, and the eye lens. Heterozygous animals from each transgenic line spontaneously developed an inflammatory disease of the eye associated with the production of copious amounts of purulent lacrimal secretions beginning at 2 weeks of age. Periorbital abscess formation became grossly apparent by 2 months of age and Pasteurella pneumotropica was cultured from the harderian glands and conjunctival surfaces of many of the MLV/HIV animals but not their nontransgenic, cohabiting littermates. This gram-negative commensal bacterium has been previously associated with a similar disease phenotype in immunocompromised (e.g., nude mice) rodent colonies. MLV/HIV mice developed normally until 15 weeks of age, when weight loss and wasting occurred, culminating in premature death (as earlier as 6 months of age). The cachexia was associated with an initially focal and subsequently progressive myopathy, coinciding with age-related increases of HIV gene expression in muscle.
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Affiliation(s)
- P Dickie
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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44
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Dickie P, Gazzinelli R, Chang LJ. Models of HIV type 1 proviral gene expression in wild-type HIV and MLV/HIV transgenic mice. AIDS Res Hum Retroviruses 1996; 12:1103-16. [PMID: 8844015 DOI: 10.1089/aid.1996.12.1103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Two proviral HIV transgenic mouse models, one bearing wild-type HIV proviral DNA and the other a modified provirus in which the viral LTRs contained the core enhancer of the Moloney murine leukemia virus (MLV), were compared. The MLV/HIV chimeric LTR, in which the MLV enhancer replaced the NF-kappa B-binding motifs, was transcriptionally active in human and murine cells in vitro and virus containing the chimeric LTR was replication competent in human cell cultures. Transgenic mice derived from microinjections of chimeric MLV/HIV proviral DNA transcribed HIV genes at a greater frequency and at higher levels than wild-type HIV proviral transgenic mice. MLV/HIV mice were also more apt to develop disease; wasting, periocular infections, and a degenerative myopathy characterized the most predominant phenotype. The tissue specificities of the wild-type and chimeric LTRs in transgenic mice were remarkably similar, but a significant difference was apparent in lymphoid cells. Basal level and LPS-inducible HIV gene expression occurred in peritoneal and bone marrow-derived macrophages from wild-type HIV transgenic mice. In contrast, HIV gene expression in macrophages from MLV/HIV mice was undetectable, even following LPS induction. However, cultured splenocytes from MLV/HIV mice supported HIV proviral gene transcription better than splenocytes from HIV mice, particularly after induction with LPS or anti-IgD antibody but not with concanavalin A. These data suggest that in transgenic mice, the HIV and MLV/HIV LTRs display a differential tropism for macrophages and B cells, respectively. HIV and MLV/HIV transgenic mice represent alternative models amenable to in vivo studies of HIV gene regulation in lymphoid cells, the induction of HIV-related disease and the evaluation of anti-HIV therapies.
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Affiliation(s)
- P Dickie
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA
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