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Bánki Z, Wilflingseder D, Ammann CG, Pruenster M, Müllauer B, Holländer K, Meyer M, Sprinzl GM, van Lunzen J, Stellbrink HJ, Dierich MP, Stoiber H. Factor I-mediated processing of complement fragments on HIV immune complexes targets HIV to CR2-expressing B cells and facilitates B cell-mediated transmission of opsonized HIV to T cells. THE JOURNAL OF IMMUNOLOGY 2006; 177:3469-76. [PMID: 16920989 DOI: 10.4049/jimmunol.177.5.3469] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Our study demonstrates that binding of complement-opsonized HIV to complement receptor type 1 on human erythrocytes (E) via C3b fragments is followed by a rapid normal human serum-mediated detachment of HIV from E. The release was dependent on the presence of factor I indicating a conversion of C3b fragments to iC3b and C3d on the viral surface. This in turn resulted in an efficient binding of opsonized HIV to CR2-expressing B cells, thus facilitating B cell-mediated transmission of HIV to T cells. These data provide a new dynamic view of complement opsonization of HIV, suggesting that association of virus with E might be a transient phenomenon and the factor I-mediated processing of C3b to iC3b and C3d on HIV targets the virus to complement receptor type 2-expressing cells. Thus, factor I in concert with CR1 on E and factor H in serum due to their cofactor activity are likely to be important contributors for the generation of C3d-opsonized infectious HIV reservoirs on follicular dendritic cells and/or B cells in HIV-infected individuals.
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Affiliation(s)
- Zoltán Bánki
- Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Austria.
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102
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Donaghy H, Wilkinson J, Cunningham AL. HIV interactions with dendritic cells: has our focus been too narrow? J Leukoc Biol 2006; 80:1001-12. [PMID: 16923917 DOI: 10.1189/jlb.0306158] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although few in number, dendritic cells (DCs) are heterogeneous, ubiquitous, and are crucial for protection against pathogens. In this review, the different DC subpopulations have been described and aspects of DC biology are discussed. DCs are important, not only in the pathogenesis of HIV, but also in the generation of anti-HIV immune responses. This review describes the roles that DC are thought to play in HIV pathogenesis, including uptake and transport of virus. We have also discussed the effects that the virus exerts on DCs such as infection and dysfunction. Then we proceed to focus on DC subsets in different organs and show how widespread the effects of HIV are on DC populations. It is clear that the small number of studies on tissue-derived DCs limits current research into the pathogenesis of HIV.
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Affiliation(s)
- Heather Donaghy
- Centre for Virus Research, Westmead Millennium Institute, Westmead Hosptial, Darcy Rd., Sydney, NSW 2145, Australia
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103
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Sukumar S, Szakal AK, Tew JG. Isolation of functionally active murine follicular dendritic cells. J Immunol Methods 2006; 313:81-95. [PMID: 16824539 DOI: 10.1016/j.jim.2006.03.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 01/31/2006] [Accepted: 03/29/2006] [Indexed: 11/22/2022]
Abstract
Biochemical, genetic, and immunological studies of follicular dendritic cells (FDCs) have been hampered by difficulty in obtaining adequate numbers of purified cells in a functional state. To address this obstacle, we enriched FDCs by irradiating mice to destroy most lymphocytes, excised the lymph nodes, and gently digested the nodes with an enzyme cocktail to form single cell suspensions. The FDCs in suspension were selected using the specific mAb FDC-M1 with magnetic cell separation technology. We were able to get nearly a million viable lymph node FDCs per mouse at about 90% purity. When examined under light and transmission electron microscopy, the cytological features were characteristic of FDCs. Furthermore, the cells were able to trap and retain immune complexes and were positive for important phenotypic markers including FDC-M1, CD21/35, CD32, CD40, and CD54. Moreover, the purified FDCs exhibited classical FDC accessory activities including: the ability to co-stimulate B cell proliferation, augment antibody responses induced by mitogens or antigens, maintain B cell viability for weeks, and protect B lymphocytes from anti-FAS induced apoptosis. In short, this combination of methods made it possible to obtain a substantial number of highly enriched functional murine FDCs.
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Affiliation(s)
- Selvakumar Sukumar
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, 23298-0678, USA
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104
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Lambotte O, Deiva K, Tardieu M. HIV-1 persistence, viral reservoir, and the central nervous system in the HAART era. Brain Pathol 2006; 13:95-103. [PMID: 12580549 PMCID: PMC8095761 DOI: 10.1111/j.1750-3639.2003.tb00010.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
HAART therapy has led to a significant reduction of general and neurological morbidity, and mortality among HIV-1 infected patients. It can also decrease HIV-1 RNA titres in plasma and CSF towards undetectable level. However, the initial hope of achieving total eradication of the virus from the body has vanished. Even in patients who do not develop viral resistance or treatment intolerance, two kinds of viral persistence have been demonstrated both in lymphoid and central nervous system. The first one is a smoldering infection that persists, despite prolonged and apparently efficient HAART, in monocytes, tissue macrophages and most probably microglia. The second one is an integration of proviral DNA in the genome of subpopulations of CD4 lymphocytes of patients receiving efficient HAART. A similar viral integration in astrocytes and less likely in resting microglia is suggested by several studies, although it has yet to be demonstrated conclusively.
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Affiliation(s)
- Olivier Lambotte
- Laboratoire—Immunité antivirale systémique et cérébrale—Equipe Mixte INSERM et Université Paris Sud N° 0109 et Hôpital Bicêtre Assistance Publique‐Hôpitaux de Paris, France
| | - Kumaran Deiva
- Laboratoire—Immunité antivirale systémique et cérébrale—Equipe Mixte INSERM et Université Paris Sud N° 0109 et Hôpital Bicêtre Assistance Publique‐Hôpitaux de Paris, France
| | - Marc Tardieu
- Laboratoire—Immunité antivirale systémique et cérébrale—Equipe Mixte INSERM et Université Paris Sud N° 0109 et Hôpital Bicêtre Assistance Publique‐Hôpitaux de Paris, France
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105
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Anthonypillai C, Gibbs JE, Thomas SA. The distribution of the anti-HIV drug, tenofovir (PMPA), into the brain, CSF and choroid plexuses. Cerebrospinal Fluid Res 2006; 3:1. [PMID: 16390539 PMCID: PMC1343584 DOI: 10.1186/1743-8454-3-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Accepted: 01/03/2006] [Indexed: 02/03/2023] Open
Abstract
Background Tenofovir disoproxil fumarate, a prodrug of the nucleotide reverse transcriptase inhibitor, tenofovir (9-[9(R)-2-(phosphonomethoxy)propyl]adenine; PMPA), was recently approved for use in the combination therapy of human immunodeficiency virus (HIV)-1 infection. This study was undertaken to understand PMPA distribution to the virus sanctuary sites located in the brain, CSF and choroid plexuses and to clarify its possible role in reducing the neurological problems associated with HIV infection. Methods The methods used included an established bilateral carotid artery perfusion of [3H]PMPA and a vascular marker, D-[14C]mannitol, in anaesthetised guinea-pigs followed by scintillation counting, HPLC and capillary depletion analyses. Movement of [3H]PMPA into the brain, cisternal CSF and lateral ventricle choroid plexus was also examined in the absence and presence of additional anti-HIV drugs and a transport inhibitor. Control and test groups were compared by ANOVA or Student's t-test, as appropriate. Results The distribution of [3H]PMPA in the cerebrum, cerebellum, pituitary gland and cerebral capillary endothelial cells was not significantly different to that measured for D-[14C]mannitol. However, [3H]PMPA accumulation was significantly higher than that of D-[14C]mannitol in the choroid plexus and CSF. Further experiments revealed no cross-competition for transport of [3H]PMPA by probenecid, a non-specific inhibitor of organic anion transport, or the nucleoside reverse transcriptase inhibitors into any of the CNS regions studied. The octanol-saline partition coefficient measurement for [3H]PMPA was 0.0134 ± 0.00003, which is higher that the 0.002 ± 0.0004 measured for D-[14C]mannitol in an earlier study. Conclusion There is negligible transport of [3H]PMPA across the blood-brain barrier, but it can cross the blood-CSF barrier. This is a reflection of the differing physiological and functional characteristics of the blood-CNS interfaces. Self- and cross-inhibition studies did not suggest the involvement of a transport system in the CNS distribution of this drug. However, the ability of PMPA to accumulate in the choroid plexus tissue, but not the cerebral capillary endothelial cells, and the hydrophilic nature of PMPA, does point to the possibility of a transporter at the level of the choroid plexus. PMPA that has crossed the choroid plexus and is in the CSF could treat HIV-infected perivascular and meningeal macrophages, but it is unlikely to reach the infected microglia of deep brain sites.
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Affiliation(s)
- Christy Anthonypillai
- King's College London, Wolfson Centre for Age-related Diseases, Guy's Campus, Hodgkin Building, London SE1 1UL, UK
| | - Julie E Gibbs
- King's College London, Wolfson Centre for Age-related Diseases, Guy's Campus, Hodgkin Building, London SE1 1UL, UK
- Clinical Neurosciences (Epilepsy Group), St Georges University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Sarah A Thomas
- King's College London, Wolfson Centre for Age-related Diseases, Guy's Campus, Hodgkin Building, London SE1 1UL, UK
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106
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Dumaurier MJ, Gratton S, Wain-Hobson S, Cheynier R. The majority of human immunodeficiency virus type 1 particles present within splenic germinal centres are produced locally. J Gen Virol 2005; 86:3369-3373. [PMID: 16298984 DOI: 10.1099/vir.0.81133-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In most stages of human immunodeficiency virus (HIV) infection, cell-free viral particles can be detected in germinal centres (GCs) that are principally retained, in the form of immune complexes, on the surface of follicular dendritic cells (FDCs). The source of this virus remains unknown, although it is agreed that the FDCs themselves are not infected productively. By sequencing HIV viral DNA, genomic RNA and spliced mRNA isolated from individual splenic white pulps, it was shown here that the majority of HIV-1 viral particles are produced locally within the supporting lymphoid structure and do not result from trapping of circulating viruses or immune complexes. These findings underline the exquisite spatial organization of HIV-1 replication in vivo, suggesting a local origin for viruses trapped in splenic GCs.
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Affiliation(s)
| | - Sophie Gratton
- Unité de Rétrovirologie Moléculaire, Institut Pasteur, Paris, France
| | - Simon Wain-Hobson
- Unité de Rétrovirologie Moléculaire, Institut Pasteur, Paris, France
| | - Rémi Cheynier
- Unité de Rétrovirologie Moléculaire, Institut Pasteur, Paris, France
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107
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Heinemann DEH, Peters JH. Follicular dendritic-like cells derived from human monocytes. BMC Immunol 2005; 6:23. [PMID: 16179091 PMCID: PMC1249575 DOI: 10.1186/1471-2172-6-23] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Accepted: 09/22/2005] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Follicular dendritic cells (FDCs) play a central role in controlling B-cell response maturation, isotype switching and the maintenance of B-cell memory. These functions are based on prolonged preservation of antigen and its presentation in its native form by FDCs. However, when entrapping entire pathogens, FDCs can turn into dangerous long-term reservoirs that may preserve viruses or prions in highly infectious form. Despite various efforts, the ontogeny of FDCs has remained elusive. They have been proposed to derive either from bone marrow stromal cells, myeloid cells or local mesenchymal precursors. Still, differentiating FDCs from their precursors in vitro may allow addressing many unsolved issues associated with the (patho-) biology of these important antigen-presenting cells. The aim of our study was to demonstrate that FDC-like cells can be deduced from monocytes, and to develop a protocol in order to quantitatively generate them in vitro. RESULTS Employing highly purified human monocytes as a starter population, low concentrations of Il-4 (25 U/ml) and GM-CSF (3 U/ml) in combination with Dexamethasone (Dex) (0.5 microM) in serum-free medium trigger the differentiation into FDC-like cells. After transient de-novo membrane expression of alkaline phosphatase (AP), such cells highly up-regulate surface expression of complement receptor I (CD35). Co-expression of CD68 confirms the monocytic origin of both, APpos and CD35pos cells. The common leukocyte antigen CD45 is strongly down-regulated. Successive stimulation with TNF-alpha up-regulates adhesion molecules ICAM-1 (CD54) and VCAM (CD106). Importantly, both, APpos as well as APneg FDC-like cells, heterotypically cluster with and emperipolese B cells and exhibit the FDC characteristic ability to entrap functionally preserved antigen for prolonged times. Identical characteristics are found in monocytes which were highly expanded in vitro by higher doses of GM-CSF (25 U/ml) in the absence of Dex and Il-4 before employing the above differentiation cocktail. CONCLUSION In this work we provide evidence that FDC-like cells can be derived from monocytes in vitro. Monocyte-derived FDC-like cells quantitatively produced offer a broad utility covering basic research as well as clinical application.
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Affiliation(s)
- Dagmar EH Heinemann
- Max-Planck-Institut für Biophysikalische Chemie, D-37077 Goettingen, Germany
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108
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García JA, Soto-Ramírez LE, Cocho G, Govezensky T, José MV. HIV-1 dynamics at different time scales under antiretroviral therapy. J Theor Biol 2005; 238:220-9. [PMID: 16005903 DOI: 10.1016/j.jtbi.2005.05.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 04/27/2005] [Accepted: 05/10/2005] [Indexed: 11/25/2022]
Abstract
We exploit a model that considers three compartments: blood plasma (BP), lymphoid tissue-interstitial spaces (LT-IS), and follicular dendritic cells (FDC), for the HIV-1 dynamics under the application of highly active antiretroviral therapy (HAART) which allowed us to unravel distinct viral dynamics occurring in short- (2 days), middle- (21 days), and long-term (183 days) time scales. The different time scales are determined by the viral clearance rate, the ratio of productively infected CD4(+) T cells to chronically infected cells, and the dissociation rate of HIV-1 complexes from FDC. This generates a scenario in which, after an initial transient stage, the viral BP dynamics decouples and becomes governed by the lymphoid tissue (LT) dynamics; in a later stage, a new decoupling occurs in which the LT-IS dynamics is slaved to that of the FDC dynamics. We observed an initial increase in the viremia after HAART in a patient who did not receive protease inhibitors (PI). By means of the above-mentioned model we were able to highlight the relevant parameters which need to be estimated at three different time scales after HAART.
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Affiliation(s)
- José A García
- Research Department, La Salle University, Benjamin Franklin 47, Col. Hipódromo-Condesa, México, D.F. 06140, México
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109
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Bánki Z, Kacani L, Rusert P, Pruenster M, Wilflingseder D, Falkensammer B, Stellbrink HJ, van Lunzen J, Trkola A, Dierich MP, Stoiber H. Complement dependent trapping of infectious HIV in human lymphoid tissues. AIDS 2005; 19:481-6. [PMID: 15764853 DOI: 10.1097/01.aids.0000162336.20439.8d] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES HIV-1 bound extracellularly to follicular dendritic cells (FDC) in germinal centers (GC) of lymphoid tissues (LT) represents the largest viral reservoir in HIV-infected individuals; however there is no direct evidence as to whether HIV trapped in human GC remains infectious. In the GC, complement receptors and Fc gamma receptors have been suggested to participate in trapping of HIV; therefore, the relative contribution of complement- and Fc gamma receptors in binding HIV on LT was investigated and the infectivity of this virus was tested. DESIGN As it is difficult to isolate FDC without contaminations of productively infected cells, HIV was detached from LT of HIV positive individuals using antibodies blocking complement- and Fc gamma receptors. Isolated virus was tested in an infectivity assay. METHODS HIV detached from LT was quantified by HIV p24 ELISA, PCR and in an in vitro infectivity assay. Presence and accessibility of viral envelope proteins, complement factors and immunoglobulins on the surface of detached viral particles were evaluated through viral capture by respective antibodies. RESULTS Although both C3d-fragments and IgG molecules were identified on the surface of HIV detached from LT, trapping of HIV was mediated solely by CR2-C3d interactions, whereas contribution of Fc gamma receptors was not detectable. Infectivity assays with HIV stripped from LT of HIV positive individuals revealed that in four out of ten patients HIV particles were infectious. CONCLUSIONS These findings indicate that in the GC infectious virus is trapped on CR2-expressing FDC (or B cells). Reduction of this pool of HIV could be a therapeutic goal.
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Affiliation(s)
- Zoltán Bánki
- Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University and Ludwig-Boltzmann-Institute for AIDS Research, 6020 Innsbruck, Austria
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110
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Arrighi JF, Pion M, Garcia E, Escola JM, van Kooyk Y, Geijtenbeek TB, Piguet V. DC-SIGN-mediated infectious synapse formation enhances X4 HIV-1 transmission from dendritic cells to T cells. ACTA ACUST UNITED AC 2005; 200:1279-88. [PMID: 15545354 PMCID: PMC2211914 DOI: 10.1084/jem.20041356] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Dendritic cells (DCs) are essential for the early events of human immunodeficiency virus (HIV) infection. Model systems of HIV sexual transmission have shown that DCs expressing the DC-specific C-type lectin DC-SIGN capture and internalize HIV at mucosal surfaces and efficiently transfer HIV to CD4+ T cells in lymph nodes, where viral replication occurs. Upon DC–T cell clustering, internalized HIV accumulates on the DC side at the contact zone (infectious synapse), between DCs and T cells, whereas HIV receptors and coreceptors are enriched on the T cell side. Viral concentration at the infectious synapse may explain, at least in part, why DC transmission of HIV to T cells is so efficient. Here, we have investigated the role of DC-SIGN on primary DCs in X4 HIV-1 capture and transmission using small interfering RNA–expressing lentiviral vectors to specifically knockdown DC-SIGN. We demonstrate that DC-SIGN− DCs internalize X4 HIV-1 as well as DC-SIGN+ DCs, although binding of virions is reduced. Strikingly, DC-SIGN knockdown in DCs selectively impairs infectious synapse formation between DCs and resting CD4+ T cells, but does not prevent the formation of DC–T cells conjugates. Our results demonstrate that DC-SIGN is required downstream from viral capture for the formation of the infectious synapse between DCs and T cells. These findings provide a novel explanation for the role of DC-SIGN in the transfer and enhancement of HIV infection from DCs to T cells, a crucial step for HIV transmission and pathogenesis.
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Affiliation(s)
- Jean-François Arrighi
- Dept. of Dermatology and Venereology, University Hospital of Geneva, 4-752, 24 Rue Micheli-du-Crest, 1211 Geneva, Switzerland
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111
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Estes JD, Thacker TC, Hampton DL, Kell SA, Keele BF, Palenske EA, Druey KM, Burton GF. Follicular Dendritic Cell Regulation of CXCR4-Mediated Germinal Center CD4 T Cell Migration. THE JOURNAL OF IMMUNOLOGY 2004; 173:6169-78. [PMID: 15528354 DOI: 10.4049/jimmunol.173.10.6169] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Follicular dendritic cells (FDCs) up-regulate the chemokine receptor CXCR4 on CD4 T cells, and a major subpopulation of germinal center (GC) T cells (CD4(+)CD57(+)), which are adjacent to FDCs in vivo, expresses high levels of CXCR4. We therefore reasoned that GC T cells would actively migrate to stromal cell-derived factor-1 (CXCL12), the CXCR4 ligand, and tested this using Transwell migration assays with GC T cells and other CD4 T cells (CD57(-)) that expressed much lower levels of CXCR4. Unexpectedly, GC T cells were virtually nonresponsive to CXCL12, whereas CD57(-)CD4 T cells migrated efficiently despite reduced CXCR4 expression. In contrast, GC T cells efficiently migrated to B cell chemoattractant-1/CXCL13 and FDC supernatant, which contained CXCL13 produced by FDCs. Importantly, GC T cell nonresponsiveness to CXCL12 correlated with high ex vivo expression of regulator of G protein signaling (RGS), RGS13 and RGS16, mRNA and expression of protein in vivo. Furthermore, FDCs up-regulated both RGS13 and RGS16 mRNA expression in non-GC T cells, resulting in their impaired migration to CXCL12. Finally, GC T cells down-regulated RGS13 and RGS16 expression in the absence of FDCs and regained migratory competence to CXCL12. Although GC T cells express high levels of CXCR4, signaling through this receptor appears to be specifically inhibited by FDC-mediated expression of RGS13 and RGS16. Thus, FDCs appear to directly affect GC T cell migration within lymphoid follicles.
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Affiliation(s)
- Jacob D Estes
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602, USA
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112
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Davies ML, Hopkins LJ, Halliday S, Houston F, Hunter N, McConnell I. Architecture of secondary lymphoid tissue in sheep experimentally challenged with scrapie. Immunology 2004; 111:230-6. [PMID: 15027909 PMCID: PMC1782407 DOI: 10.1111/j.0019-2805.2003.01789.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Scrapie is a transmissible spongiform encephalopathy in which there is an accumulation of the abnormal form of the prion protein, PrPsc, in the lymphoreticular system and nervous system. There is a particular accumulation of PrPsc on follicular dendritic cells within the germinal centre of B-cell follicles. Because accumulation of PrPsc in the nervous system leads to neuronal cell loss we have examined PrPsc accumulation in the prescapular and mesenteric lymph nodes in relation to lymph node architecture of scrapie-challenged sheep. We demonstrate that an accumulation of PrPsc in the lymph node fails to result in gross defects in the microanatomy and phenotype of T- and B-cell areas in the lymph nodes.
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Affiliation(s)
- Marie L Davies
- Centre for Veterinary Science, Department of Clinical Veterinary Medicine, University of Cambridge, Cambridge, UK
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113
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Ghosn J, Viard JP, Katlama C, de Almeida M, Tubiana R, Letourneur F, Aaron L, Goujard C, Salmon D, Leruez-Ville M, Rouzioux C, Chaix ML. Evidence of genotypic resistance diversity of archived and circulating viral strains in blood and semen of pre-treated HIV-infected men. AIDS 2004; 18:447-57. [PMID: 15090797 DOI: 10.1097/00002030-200402200-00011] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To study the genetic diversity of drug-resistant HIV strains present in blood and in semen, especially those archived in peripheral blood mononuclear cells (PBMC) and non-sperm cells (NSC). METHODS Paired blood and semen samples were collected from twenty heavily pre-treated HIV-infected men. HIV RNA in blood plasma (BP) and seminal plasma (SP), as well as proviral DNA in PBMC and NSC were quantified and used for resistance genotyping. Phylogenetic analysis of protease gene clones was used to explore the diversity of the viral quasi-species. RESULTS Median BP HIV RNA, PBMC proviral DNA, SP HIV RNA and non-sperm cell proviral DNA loads were respectively: 4.77, 3.65, 3.16 and 1.77 log10 copies per ml or per 10 cells. Resistant HIV strains were found in the BP and PBMC of all the patients, in the SP of 14 patients, and in the NSC of five patients. Overall, the blood and genital compartments exhibited different genotypic resistance patterns in six patients (30%), with additional resistance mutations in the semen of four patients. Phylogenetic analysis of clones of HIV protease gene showed that viral strains in SP originated not only from passive diffusion from BP, but also from local production in semen. The storage of archived proviruses differed according to the anatomic reservoir. CONCLUSION HIV resistant strains are frequent (70%) in the semen of heavily pre-treated men, and the diversity of genotypic resistance pattern confirms HIV compartmentalization. Thus, the risk of sexual transmission of resistant strains can only be partly predicted by standard tests applied to BP.
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Affiliation(s)
- Jade Ghosn
- Laboratoire de Virologie, EA MRT 3620 Université R. Descartes, CHU Necker, Paris.
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114
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Affiliation(s)
- Mario Stevenson
- Program in Molecular medicine, University of Massachusetts Medical School, Worcester, 01605, USA.
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115
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Rambaut A, Posada D, Crandall KA, Holmes EC. The causes and consequences of HIV evolution. Nat Rev Genet 2004; 5:52-61. [PMID: 14708016 DOI: 10.1038/nrg1246] [Citation(s) in RCA: 354] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Andrew Rambaut
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
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Mélot F, Defaweux V, Jolois O, Collard A, Robert B, Heinen E, Antoine N. FDC-B1: a new monoclonal antibody directed against bovine follicular dendritic cells. Vet Immunol Immunopathol 2004; 97:1-9. [PMID: 14700533 DOI: 10.1016/s0165-2427(03)00160-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Follicular dendritic cells (FDCs) are a unique population of accessory cells located in the light zone of the germinal centres of lymphoid follicles. Their involvement in the generation of humoral immune responses implies a potential role for these cells in many disorders. Indeed, in prion diseases, FDCs seem to be the major sites of extraneuronal cellular prion protein expression and the principal sites of the infectious agent accumulation in lymphoid organs. The identification of FDC is useful for the analysis of their distribution in reactive lymphoid tissue as well as in pathological conditions. The production and characterisation of a new mouse monoclonal antibody directed against bovine follicular dendritic cells (FDC-B1) is reported. The antigen detected by FDC-B1 is expressed exclusively on the surface of FDCs in ruminant lymphoid organs. The antigen has an approximate molecular weight of 28 kDa.
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Affiliation(s)
- F Mélot
- Institute of Human Histology, University of Liège, Rue de Pitteurs, 20, B-4020 Liège, Belgium
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117
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Otero M, Nunnari G, Leto D, Sullivan J, Wang FX, Frank I, Xu Y, Patel C, Dornadula G, Kulkosky J, Pomerantz RJ. Peripheral blood Dendritic cells are not a major reservoir for HIV type 1 in infected individuals on virally suppressive HAART. AIDS Res Hum Retroviruses 2003; 19:1097-103. [PMID: 14709246 DOI: 10.1089/088922203771881194] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Dendritic cells (DCs) are potent antigen-presenting cells, and their physiological localization in tissues that interact with the external environment is important as a first barrier against pathogens such as human immunodeficiency virus type I (HIV-1). Several models have been proposed to explain the possible role of DCs as a reservoir for HIV-1 in patients on virally suppressive highly active antiretroviral therapy (HAART). However, the low yield of cell isolates has made this evaluation a difficult task. The present study analyzes whether peripheral blood DCs from HIV-1-infected individuals on virally suppressive HAART, with plasma HIV-1 RNA levels of less than 50 copies/ml, carry either HIV-1 provirus and/or HIV-1 virions. Peripheral blood DCs were isolated from a cohort of 10 HIV-1-seropositive men taking suppressive HAART. In five patients, plasmacytoid and myeloid dendritic cells were isolated to attempt to identify their respective roles in HIV-1 residual disease. Viral out-growth assays were performed in vitro, as well as gag and R/U5 polymerase chain reaction (PCR) amplification of viral RNA and DNA, respectively, from DC and peripheral blood mononuclear cell (PBMC) extracts. Fluorescence activated cell-sorting (FACS) data revealed cellular yields from 85.90 to 95.18%, of relatively pure DCs isolated from patients' PBMCs. Although HIV-1 RNA gag and DNA RU/5 were detected in all PBMC samples isolated from the patients, proviral DNA and viral RNA forms were not detected in any of the DC isolates. In addition, no replication-competent virus was demonstrated in DC coculture assays, while virus was isolated from each patients' CD8+ T-lymphocyte-depleted PBMC cocultures. Furthermore, HIV-1 gag proviral DNA was not detected in either plasmacytoid or myeloid DC subfractions. The current study suggests that in HIV-1-infected individuals treated with suppressive HAART, peripheral blood DCs do not carry HIV-1 proviral DNA or viral particles attached to their surface. These populations of peripheral blood DCs are likely not a major HIV-1 reservoir in patients on HAART with clinically undetectable plasma viral RNA.
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Affiliation(s)
- Miguel Otero
- The Dorrance H. Hamilton Laboratories, Center for Human Virology and Biodefense, Division of Infectious Diseases and Environmental Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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118
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Crowe S, Zhu T, Muller WA. The contribution of monocyte infection and trafficking to viral persistence, and maintenance of the viral reservoir in HIV infection. J Leukoc Biol 2003; 74:635-41. [PMID: 12960232 DOI: 10.1189/jlb.0503204] [Citation(s) in RCA: 192] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Cellular viral reservoirs and anatomic sanctuary sites allow continuing HIV-1 replication in patients with suppressed plasma viremia who are receiving highly active antiretroviral therapy and prevent eradication of HIV-1 by these regimens. Cells of macrophage lineage, including monocytes subsets within the blood, play a role in HIV-1 persistence. Evidence of sequence evolution in blood monocytes, in comparison to resting CD4+ T cells, demonstrates their distinct contribution to plasma viremia. There is evidence to suggest that a specific monocyte subset, of CD14loCD16hi phenotype, is more susceptible to HIV-1 infection than the majority of blood monocytes. Trafficking of monocytes through various tissues following their emigration from the bloodstream allows these cells to differentiate into tissue macrophages, or potentially to egress from the tissues as migratory dendritic cells. This review provides an evaluation of the contribution of monocytes to HIV-1 persistence and the HIV-1 reservoir, essential for the effective design of therapeutic eradication strategies.
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Affiliation(s)
- Suzanne Crowe
- AIDS Pathogenesis & Clinical Research Programme, The Macfarlane Burnet Institute for Medical Research nad Public Health, Melbourne, Australia.
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119
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Abstract
Despite considerable advances in HIV science in the past 20 years, the reason why HIV-1 infection is pathogenic is still debated and the goal of eradicating HIV-1 infection remains elusive. A deeper understanding of the interplay between HIV-1 and its host and why simian immunodeficiency virus (SIV) is nonpathogenic in some natural hosts may provide a few answers.
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Affiliation(s)
- Mario Stevenson
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Biotech 2, Suite 319, Worcester, Massachusetts 01605, USA.
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120
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Ferrantelli F, Hofmann-Lehmann R, Rasmussen RA, Wang T, Xu W, Li PL, Montefiori DC, Cavacini LA, Katinger H, Stiegler G, Anderson DC, McClure HM, Ruprecht RM. Post-exposure prophylaxis with human monoclonal antibodies prevented SHIV89.6P infection or disease in neonatal macaques. AIDS 2003; 17:301-9. [PMID: 12556683 DOI: 10.1097/00002030-200302140-00003] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The majority of infants infected through maternal transmission acquire the virus during birth or postpartum through breastfeeding: mucosal exposure is considered to be a major route of infection. OBJECTIVES To develop passive immunization with human neutralizing monoclonal antibodies (mAbs) against mother-to-child transmission of HIV during delivery and through breastfeeding. DESIGN An oral challenge model in newborn rhesus macaques mimicked peri- and postpartum virus transmission. METHODS Neonatal rhesus macaques were challenged orally with the highly pathogenic, chimeric simian-human immunodeficiency virus SHIV89.6P and given post-exposure prophylaxis with a quadruple combination of neutralizing human mAbs, IgG1b12, 2G12, 2F5, and 4E10, directed against conserved epitopes of HIV envelope glycoproteins. Control animals were virus challenged but left untreated. All infants were followed prospectively for signs of viremia and immunodeficiency. RESULTS Two out of four macaque infants treated with neutralizing mAbs showed no evidence of infection; the other two maintained normal CD4 T cell counts. In contrast, all control animals became highly viremic and had profound CD4 T cell losses; three out of four died from AIDS within 1.5-6 weeks of the challenge. CONCLUSIONS Passive immunization with this quadruple neutralizing mAbs combination may represent a promising approach to prevent peri- and postnatal HIV transmission. Furthermore, the epitopes recognized by the four neutralizing mAbs are key determinants to achieve complete protection and represent important targets against which to develop active, antibody-response-based AIDS vaccines.
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Affiliation(s)
- Flavia Ferrantelli
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA
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121
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Maeda K, Matsuda M, Suzuki H, Saitoh HA. Immunohistochemical recognition of human follicular dendritic cells (FDCs) in routinely processed paraffin sections. J Histochem Cytochem 2002; 50:1475-86. [PMID: 12417613 DOI: 10.1177/002215540205001107] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A number of monoclonal antibodies (MAbs) that recognize human follicular dendritic cells (FDCs) have been identified. Although some of them have already been applied individually in routine immunolabeling using formalin-fixed paraffin sections for diagnostic and experimental purposes, many antibodies are still employed only for immunolabeling using cryostat sections or particularly processed sections because they have been thought unsuitable for routine sections. A comprehensive examination re-evaluating their suitability in paraffin sections has not been reported. Accordingly, there is limited ability to examine the immunopathological contribution or diagnostic value of FDCs using routinely processed specimens or archived materials. In this study a broad panel of antibodies was systematically applied to the immunolabeling of paraffin sections of reactive tonsils or lymph nodes, in combination with advanced antigen retrieval (AR) techniques. Several antibodies, including Ki-M4p, X-11, 12B1, CNA.42, 1F8/BU32 (anti-CD21), BU38/1B12 (anti-CD23), Ber-MAC-DRC/To5 (anti-CD35), 1.4C3 (anti-CD106), NGFR5 (anti-nerve growth factor receptor p75), IIH6 (anti-CD55), 55K-2 (anti-fascin), and anti-S100 protein alpha-chain, were found to label FDCs in routine sections when combined with suitable AR techniques. Our results are easily adaptable for routine practice and provided useful suggestions concerning the immunopathological behavior and diversity of the particular cells.
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Affiliation(s)
- Kunihiko Maeda
- Department of Pathology, Yamagata University School of Medicine, Yamagata, Japan
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122
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Gommerman JL, Mackay F, Donskoy E, Meier W, Martin P, Browning JL. Manipulation of lymphoid microenvironments in nonhuman primates by an inhibitor of the lymphotoxin pathway. J Clin Invest 2002; 110:1359-69. [PMID: 12417575 PMCID: PMC151614 DOI: 10.1172/jci15975] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2002] [Accepted: 08/27/2002] [Indexed: 12/11/2022] Open
Abstract
Reticular networks in lymphoid organs play critical roles in the organization of local microenvironments. A number of these elements are maintained by continual signaling through the lymphotoxin system. Evaluation of the lymphotoxin (LT) pathway in primates using a fusion protein decoy provides a unique opportunity to assess modulation of splenic microenvironments in a species with considerably greater background immunological activity compared with rodents. Within the germinal center microenvironment, treatment resulted in a collapse of follicular dendritic cell (FDC) networks and in the disappearance of a ringlike network of immune complex-carrying cells, although some other attributes of the germinal center appeared to be unaltered. Treatment also resulted in changes in the splenic marginal zone, a microenvironment where the architecture is notably different from that of the rodent. Cessation of treatment and recovery allowed us to monitor reemergence of these cell types and revealed that FDCs rely on LT-dependent signals to recompact into appropriately positioned tight networks. Despite the loss of FDC networks, the primary Ab response to keyhole limpet hemocyanin was unaltered over a 20-day period. Manipulation of these microenvironments may represent a novel approach to modulating immune function in human disease.
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Affiliation(s)
- Jennifer L Gommerman
- Department of Exploratory Sciences, Biogen Inc., Cambridge, Massachusetts 02142, USA
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123
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Gommerman JL, Mackay F, Donskoy E, Meier W, Martin P, Browning JL. Manipulation of lymphoid microenvironments in nonhuman primates by an inhibitor of the lymphotoxin pathway. J Clin Invest 2002. [DOI: 10.1172/jci0215975] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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124
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Ljungberg K, Rollman E, Eriksson L, Hinkula J, Wahren B. Enhanced immune responses after DNA vaccination with combined envelope genes from different HIV-1 subtypes. Virology 2002; 302:44-57. [PMID: 12429515 DOI: 10.1006/viro.2002.1547] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In a multisubtype approach to HIV-1 vaccination, mice were immunized with HIV-1 envelope gp160 genes from subtypes A, B, and C. Subsequently the mice were challenged with syngeneic primary splenocytes infected with a HIV-1/MuLV pseudovirus carrying a subtype B genome. HIV-specific immune responses and protection were strongest in the group of animals immunized with a combination of subtype A, B, and C specific gp160 genes as compared to subtype B only. Immunization with the combination of the cross-reactive subtypes A and C envelope genes induced HIV-specific immune responses but did not result in significant protection to challenge with subtype B infected cells. From this we conclude that immunization with the envelope genes from several HIV-1 subtypes may indeed enhance immune responses. This study shows that by using a mix of subtype envelope genes, an enhanced protective immunity can be obtained experimentally, potentially also in humans.
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Affiliation(s)
- Karl Ljungberg
- Department of Virology, Swedish Institute for Infectious Disease Control and Microbiology and Tumor Biology Center, Karolinska Institute, SE-17182, Stockholm, Sweden.
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125
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Walter H, Löw P, Harrer T, Schmitt M, Schwingel E, Tschochner M, Helm M, Korn K, Uberla K, Schmidt B. No evidence for persistence of multidrug-resistant viral strains after a 7-month treatment interruption in an HIV-1-infected individual. J Acquir Immune Defic Syndr 2002; 31:137-46. [PMID: 12394791 DOI: 10.1097/00126334-200210010-00003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The number of HIV-1-infected patients harboring multidrug-resistant viruses is increasing. Since new antiretroviral drugs with favorable resistance profiles are limited, innovative strategies are urgently needed. Treatment interruptions can lead to a loss in HIV resistance followed by improved response to reinitiated therapy. The authors report the case of a patient with sustained antiretroviral response for 3.5 years after a 7-month treatment interruption. Concomitant with an increase in replication capacity, multidrug-resistant viruses gradually disappeared during treatment interruption. Resistance to protease inhibitors (PI) was completely lost, and resistance to reverse transcriptase inhibitors was still present when therapy was reinitiated. PI-resistant variants were not detected at four time points after treatment reinitiation. The alignment of the nucleic acid sequences from all different time points suggested that the viruses obtained after treatment reinitiation evolved from less-resistant variants prior to treatment interruption. This was supported by in vitro propagation of the viral plasma population and an individual clone derived from the time point of treatment interruption. This is consistent with a model favoring reversible binding of HIV-1 to reservoirs, as has recently been proposed for follicular dendritic cells. Understanding of this process could help to exploit the reduced fitness of drug-resistant viruses for treatment interruptions.
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Affiliation(s)
- Hauke Walter
- Institute of Clinical and Molecular Virology, German National Reference Centre for Retroviruses, University of Erlangen-Nürnberg
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126
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Estes JD, Keele BF, Tenner-Racz K, Racz P, Redd MA, Thacker TC, Jiang Y, Lloyd MJ, Gartner S, Burton GF. Follicular dendritic cell-mediated up-regulation of CXCR4 expression on CD4 T cells and HIV pathogenesis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:2313-22. [PMID: 12193696 DOI: 10.4049/jimmunol.169.5.2313] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Follicular dendritic cells (FDCs) represent a major reservoir of HIV, and active infection occurs surrounding these cells, suggesting that this microenvironment is highly conducive to virus transmission. Because CD4 T cells around FDCs in germinal centers express the HIV coreceptor, CXCR4, whereas CD4 lymphocytes in many other sites do not, it prompted the hypothesis that FDCs may increase CXCR4 expression on CD4 T cells, thereby facilitating infection. To test this, HIV receptor/coreceptor expression was determined on CD4 T cells cultured with or without FDCs, and its consequence to infection was assessed by measuring virus binding and entry. FDCs had little effect on CCR5 or CD4 expression but increased CXCR4 expression on CD4 T cells. FDC-mediated up-regulation of CXCR4 on CD4 T cells occurred by 24 h and was sustained for at least 96 h in vitro, and FDC-CD4 T cell contact was necessary. Importantly, increased CXCR4 expression directly correlated with increased binding and entry of HIV-1 X4 isolates. Furthermore, CD4(+)CD57(+) germinal center T cells expressed high levels of CXCR4 and supported enhanced entry of X4 HIV compared with other CD4 T cells from the same tissue. Thus, in addition to serving as a reservoir of infectious virus, FDCs render surrounding germinal center T cells highly susceptible to infection with X4 isolates of HIV-1.
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Affiliation(s)
- Jacob D Estes
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602, USA
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127
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Tumanov A, Kuprash D, Lagarkova M, Grivennikov S, Abe K, Shakhov A, Drutskaya L, Stewart C, Chervonsky A, Nedospasov S. Distinct role of surface lymphotoxin expressed by B cells in the organization of secondary lymphoid tissues. Immunity 2002; 17:239-50. [PMID: 12354378 DOI: 10.1016/s1074-7613(02)00397-7] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In order to definitively ascertain the functional contribution of lymphotoxin (LT) expressed by B cells, we produced mice with the LTbeta gene deleted from B cells (B-LTbeta KO mice). In contrast to systemic LTbeta deletion, in B-LTbeta KO mice only splenic microarchitecture was affected, while lymph nodes and Peyer's patches (PP) were normal, except for PP's reduced size. Even though B-LTbeta KO spleens retained a small number of follicular dendritic cells (FDC) which appeared to be dependent on LTbeta produced by T cells, IgG responses to sheep red blood cells were markedly reduced. Thus, the organogenic function of B-LTbeta is almost entirely restricted to spleen, where it supports the correct lymphoid architecture that is critical for an effective humoral immune response.
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Affiliation(s)
- Alexei Tumanov
- Laboratory of Molecular Immunology, Engelhardt Institute of Molecular Biology and Belozersky Institute of Physico-Chemical Biology, Moscow, Russia.
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128
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Piguet V, Blauvelt A. Essential roles for dendritic cells in the pathogenesis and potential treatment of HIV disease. J Invest Dermatol 2002; 119:365-9. [PMID: 12190858 DOI: 10.1046/j.1523-1747.2002.01840.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
During sexual transmission of HIV, virus crosses mucosal epithelium and eventually reaches lymphoid tissue where it establishes a permanent infection. Evidence has accumulated that infection of Langerhans cells, which are resident dendritic cells in pluristratified epithelia, plays a crucial role in the early events of HIV transmission. HIV infection of Langerhans cells is regulated by surface expression of CD4 and CCR5. Thus, topical microbicides that interfere with HIV infection of Langerhans cells represent an attractive strategy for blocking sexual transmission of virus. Capture and uptake of HIV virions is another major pathway by which HIV interacts with dendritic cells. By contrast, this process is mediated by a newly described C-type lectin, DC-SIGN. It is well established that HIV-exposed dendritic cells transmit virus efficiently to cocultured T cells. Indeed, dendritic cell-T cell interaction, critical in the generation of immune responses, is a rich microenvironment for HIV replication both in vitro and in vivo. Dendritic cells that have captured virus via DC-SIGN, and not HIV-infected dendritic cells, probably facilitate most infection of T cells in chronically infected individuals. Therefore, blocking DC-SIGN-mediated capture of HIV represents a potential therapeutic antiviral strategy for HIV disease. Lastly, dendritic cells have been targeted both ex vivo and in vivo to initiate and enhance HIV-specific immunity. Although these approaches are promising for both therapeutic and prophylactic vaccines, much additional work is needed in order to optimize dendritic-cell-based immunization strategies.
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Affiliation(s)
- Vincent Piguet
- Department of Dermatology, University Hospital of Geneva, Switzerland; Dermatology Branch, National Cancer Institute, Bethesda, Maryland , USA.
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129
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Louie M, Markowitz M. Goals and milestones during treatment of HIV-1 infection with antiretroviral therapy: a pathogenesis-based perspective. Antiviral Res 2002; 55:15-25. [PMID: 12076748 DOI: 10.1016/s0166-3542(02)00022-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Highly active antiretroviral therapy (HAART) has reduced the morbidity and mortality related to infection with the human immunodeficiency virus-1 (HIV-1) through its ability to suppress viral replication and preserve and reconstitute specific immune responses in many infected individuals. However, the complete eradication of HIV-1 with current HAART regimens is not considered possible by most experts. Moreover, many current antivirals have metabolic complications and limiting side effects. Consequently, the treatment paradigm has shifted from 'hit hard and early' to delaying the initiation of therapy until later in the course of HIV-1-related disease, with corresponding modifications of consensus treatment guidelines. Factors that need to be considered in deciding when to initiate therapy and with what regimen include the patient's risk of disease progression, the possible adverse drug effects, the patient's ability to adhere to the prescribed therapy, and the need to preserve future therapeutic options. In this article, we discuss the issues surrounding the initiation of HAART, and describe the virologic and immunologic milestones that may be achieved with effective antiretroviral therapy.
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Affiliation(s)
- Michael Louie
- Aaron Diamond AIDS Research Center, 455 First Ave., 7th Floor, New York, NY 10016, USA
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130
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Affiliation(s)
- F P Siegal
- St. Vincents Hospital Medical Center, New York, New York, USA
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131
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Abstract
A viral reservoir is a cell type or anatomical site in association with which a replication-competent form of the virus accumulates and persists with more stable kinetic properties than the main pool of actively replicating virus. This article reviews several cell types and anatomical sites proposed as potential reservoirs for HIV-1. It is now clear that HIV-1 persists in a small reservoir of latently infected resting memory CD4(+) T cells, which shows minimal decay even in patients on highly active antiretroviral therapy (HAART). The persistence of virus in this reservoir is consistent with the biology of these cells and the long-term persistence of immunologic memory. The viral replication that continues in patients on suppressive HAART may also contribute to the stability of this reservoir. There may be other reservoirs, but the latent reservoir in resting CD4(+) T cells appears to be sufficient to guarantee lifetime persistence of HIV-1 in the majority of patients on current HAART regimens, and unless new approaches are developed, eradication will not be possible. The clinical implications of this and other HIV-1 reservoirs are discussed.
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Affiliation(s)
- Joel N Blankson
- Departments of Medicine and Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; e-mail:
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132
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Hlavacek WS, Percus JK, Percus OE, Perelson AS, Wofsy C. Retention of antigen on follicular dendritic cells and B lymphocytes through complement-mediated multivalent ligand-receptor interactions: theory and application to HIV treatment. Math Biosci 2002; 176:185-202. [PMID: 11916508 DOI: 10.1016/s0025-5564(02)00091-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In HIV-infected patients, large quantities of HIV are associated with follicular dendritic cells (FDCs) in lymphoid tissue. During antiretroviral therapy, most of this virus disappears after six months of treatment, suggesting that FDC-associated virus has little influence on the eventual outcome of long-term therapy. However, a recent theoretical study using a stochastic model for the interaction of HIV with FDCs indicated that some virus may be retained on FDCs for years, where it can potentially reignite infection if treatment is interrupted. In that study, an approximate expression was used to estimate the time an individual virion remains on FDCs during therapy. Here, we determine the conditions under which this approximation is valid, and we develop expressions for the time a virion spends in any bound state and for the effect of rebinding on retention. We find that rebinding, which is influenced by diffusion, may play a major role in retention of HIV on FDCs. We also consider the possibility that HIV is retained on B cells during therapy, which like FDCs also interact with HIV. We find that virus associated with B cells is unlikely to persist during therapy.
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Affiliation(s)
- William S Hlavacek
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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133
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Smith-Franklin BA, Keele BF, Tew JG, Gartner S, Szakal AK, Estes JD, Thacker TC, Burton GF. Follicular dendritic cells and the persistence of HIV infectivity: the role of antibodies and Fcgamma receptors. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:2408-14. [PMID: 11859132 DOI: 10.4049/jimmunol.168.5.2408] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Large quantities of HIV are found trapped on the surface of follicular dendritic cells (FDCs), and virus persists on these cells until they ultimately die. We recently found that FDCs maintain HIV infectivity for long periods in vivo and in vitro. Because FDCs trap Ags (and virus) in the form of immune complexes and are rich in FcgammaRs, we reasoned that Ab and FcgammaRs may be required for FDC-mediated maintenance of HIV infectivity. To investigate this hypothesis, HIV immune complexes were formed in vitro and incubated for increasing times with or without FDCs, after which the remaining infectious virus was determined by HIV-p24 production in rescue cultures. FDCs maintained HIV infectivity in vitro in a dose-dependent manner but required the presence of specific Ab for this activity regardless of whether laboratory-adapted or primary X4 and R5 isolates were tested. In addition, Abs against either virally or host-encoded proteins on the virion permitted FDC-mediated maintenance of HIV infectivity. We found that the addition of FDCs to HIV immune complexes at the onset of culture gave optimal maintenance of infectivity. Moreover, blocking FDC-FcgammaRs or killing the FDCs dramatically reduced their ability to preserve virus infectivity. Finally, FDCs appeared to decrease the spontaneous release of HIV-1 gp120, suggesting that FDC-virus interactions stabilize the virus particle, thus contributing to the maintenance of infectivity. Therefore, optimal maintenance of HIV infectivity requires both Ab against particle-associated determinants and FDC-FcgammaRs.
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Affiliation(s)
- Beverly A Smith-Franklin
- Department of Microbiology/Immunology and Anatomy, Division of Immunobiology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, USA
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134
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Frost SDW, Martinez-Picado J, Ruiz L, Clotet B, Brown AJL. Viral dynamics during structured treatment interruptions of chronic human immunodeficiency virus type 1 infection. J Virol 2002; 76:968-79. [PMID: 11773372 PMCID: PMC135793 DOI: 10.1128/jvi.76.3.968-979.2002] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although antiviral agents which block human immunodeficiency virus (HIV) replication can result in long-term suppression of viral loads to undetectable levels in plasma, long-term therapy fails to eradicate virus, which generally rebounds after a single treatment interruption. Multiple structured treatment interruptions (STIs) have been suggested as a possible strategy that may boost HIV-specific immune responses and control viral replication. We analyze viral dynamics during four consecutive STI cycles in 12 chronically infected patients with a history (>2 years) of viral suppression under highly active antiretroviral therapy. We fitted a simple model of viral rebound to the viral load data from each patient by using a novel statistical approach that allows us to overcome problems of estimating viral dynamics parameters when there are many viral load measurements below the limit of detection. There is an approximate halving of the average viral growth rate between the first and fourth STI cycles, yet the average time between treatment interruption and detection of viral loads in the plasma is approximately the same in the first and fourth interruptions. We hypothesize that reseeding of viral reservoirs during treatment interruptions can account for this discrepancy, although factors such as stochastic effects and the strength of HIV-specific immune responses may also affect the time to viral rebound. We also demonstrate spontaneous drops in viral load in later STIs, which reflect fluctuations in the rates of viral production and/or clearance that may be caused by a complex interaction between virus and target cells and/or immune responses.
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Affiliation(s)
- Simon D W Frost
- Department of Pathology, University of California, San Diego, California 92103, USA.
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135
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Kwon DS, Gregorio G, Bitton N, Hendrickson WA, Littman DR. DC-SIGN-mediated internalization of HIV is required for trans-enhancement of T cell infection. Immunity 2002; 16:135-44. [PMID: 11825572 DOI: 10.1016/s1074-7613(02)00259-5] [Citation(s) in RCA: 404] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Fusion of the human immunodeficiency virus (HIV) to the plasma membrane of target cells is mediated by interaction of its envelope glycoprotein, gp120, with CD4 and appropriate chemokine receptors. gp120 additionally binds to DC-SIGN, a C-type lectin expressed on immature dendritic cells. This interaction does not result in viral fusion, but instead contributes to enhanced infection in trans of target cells that express CD4 and chemokine receptors. Here we show that DC-SIGN mediates rapid internalization of intact HIV into a low pH nonlysosomal compartment. Internalized virus retains competence to infect target cells. Removal of the DC-SIGN cytoplasmic tail reduced viral uptake and abrogated the trans-enhancement of T cell infection. We propose that HIV binds to DC-SIGN to gain access to an intracellular compartment that contributes to augmentation or retention of viral infectivity.
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Affiliation(s)
- Douglas S Kwon
- Molecular Pathogenesis Program, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
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136
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Abstract
During the past 6 years, there have been substantial advances in our understanding of human immunodeficiency virus 1 and other viruses, such as hepatitis B virus and hepatitis C virus, that cause chronic infection. The use of mathematical modelling to interpret experimental results has made a significant contribution to this field. Mathematical modelling is also improving our understanding of T-cell dynamics and the quantitative events that underlie the immune response to pathogens.
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Affiliation(s)
- Alan S Perelson
- Theoretical Division, Los Alamos National Laboratory, New Mexico 87545, USA.
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137
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Sonza S, Crowe SM. Reservoirs for HIV infection and their persistence in the face of undetectable viral load. AIDS Patient Care STDS 2001; 15:511-8. [PMID: 11689138 DOI: 10.1089/108729101753205676] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- S Sonza
- AIDS Pathogenesis Research Unit, Macfarlane Burnet Centre for Medical Research, Fairfield, Victoria, Australia
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138
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Kaeser PS, Klein MA, Schwarz P, Aguzzi A. Efficient lymphoreticular prion propagation requires PrP(c) in stromal and hematopoietic cells. J Virol 2001; 75:7097-106. [PMID: 11435590 PMCID: PMC114438 DOI: 10.1128/jvi.75.15.7097-7106.2001] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In most prion diseases, infectivity accumulates in lymphoreticular organs early after infection. Defects in hematopoietic compartments, such as impaired B-cell maturation, or in stromal compartments, such as abrogation of follicular dendritic cells, can delay or prevent lymphoreticular prion colonization. However, the nature of the compartment in which prion replication takes place is controversial, and it is unclear whether this compartment coincides with that expressing the normal prion protein (PrP(c)). Here we studied the distribution of infectivity in splenic fractions of wild-type and fetal liver chimeric mice carrying the gene that encodes PrP(c) (Prnp) solely on hematopoietic or on stromal cells. We fractionated spleens at various times after intraperitoneal challenge with prions and assayed infectivity by bioassay. Upon high-dose challenge, chimeras carrying PrP(c) on hematopoietic cells accumulated prions in stroma and in purified splenocytes. In contrast, after low-dose challenge ablation of Prnp in either compartment prevented splenic accumulation of infectivity, indicating that optimal prion replication requires PrP(c) expression by both stromal and hematopoietic compartments.
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Affiliation(s)
- P S Kaeser
- Institute of Neuropathology, University Hospital, 8091 Zurich, Switzerland
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