Spectrum Of Target Cells Research Articles

Serpentoviruses: More than Respiratory Pathogens.

In recent years, nidoviruses have emerged as important respiratory pathogens of reptiles, affecting captive python populations. In pythons, nidovirus (recently reclassified as serpentovirus) infection induces an inflammation of the upper respiratory and alimentary tract which can develop into a severe, often fatal proliferative pneumonia. We observed pyogranulomatous and fibrinonecrotic lesions in organ systems other than the respiratory tract during full postmortem examinations on 30 serpentovirus reverse transcription-PCR (RT-PCR)-positive pythons of varying species originating from Switzerland and Spain. The observations prompted us to study whether this not yet reported wider distribution of lesions is associated with previously unknown serpentoviruses or changes in the serpentovirus genome. RT-PCR and inoculation of Morelia viridis cell cultures served to recruit the cases and obtain virus isolates. Immunohistochemistry and immunofluorescence staining against serpentovirus nucleoprotein demonstrated that the virus infects not only a broad spectrum of epithelia (respiratory and alimentary epithelium, hepatocytes, renal tubules, pancreatic ducts, etc.), but also intravascular monocytes, intralesional macrophages, and endothelial cells. With next-generation sequencing we obtained a full-length genome for a novel serpentovirus species circulating in Switzerland. Analysis of viral genomes recovered from pythons showing serpentovirus infection-associated respiratory or systemic disease did not reveal sequence association to phenotypes; however, functional studies with different strains are needed to confirm this observation. The results indicate that serpentoviruses have a broad cell and tissue tropism, further suggesting that the course of infection could vary and involve lesions in a broad spectrum of tissues and organ systems as a consequence of monocyte-mediated viral systemic spread.IMPORTANCE During the last years, python nidoviruses (now reclassified as serpentoviruses) have become a primary cause of fatal disease in pythons. Serpentoviruses represent a threat to captive snake collections, as they spread rapidly and can be associated with high morbidity and mortality. Our study indicates that, different from previous evidence, the viruses do not only affect the respiratory tract, but can spread in the entire body with blood monocytes, have a broad spectrum of target cells, and can induce a variety of lesions. Nidovirales is an order of animal and human viruses that comprises important zoonotic pathogens such as Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), and SARS-CoV-2. Serpentoviruses belong to the same order as the above-mentioned human viruses and show similar characteristics (rapid spread, respiratory and gastrointestinal tropism, etc.). The present study confirms the relevance of natural animal diseases to better understand the complexity of viruses of the order Nidovirales.

Dextran Enhances the Lentiviral Transduction Efficiency of Murine and Human Primary NK Cells.

Recent advances in cancer immunotherapy emphasize the need for an efficient method to genetically modify effector lymphocytes to express exogenous "synthetic" genes. NK cells represent 10-20% of total lymphocytes in the peripheral blood of humans and play an essential role in clearing infections and malignant cells. A significant number of NK cells express and utilize non-clonotypic receptors that recognize cognate ligands expressed on a broad spectrum of target cells. Thus, NK cells can be utilized as potent immunotherapeutic tools with fewer limitations. Considerable amount of progress in improving effector functions through genetic manipulations has been centered around T cells. However, a similar technological and translational exploration on NK cells is lacking. One major constrain is the significantly low efficiency of lentiviral-mediated gene transductions into primary human or mouse NK cells. We found that dextran, a branched glucan polysaccharide, significantly improves the transduction efficiency of human and mouse primary NK cells. This highly reproducible methodology offers an approach that can help to improve gene delivery into NK cells and thereby cancer immunotherapy.

Tilorone activates NK cells and cytotoxic lymphocytes that kill HLA-negative tumor cells.

Tilorone hydrochloride, a low-molecular-weight synthetic compound, induces interferon production and has been reported to have both antiviral and antitumor activities. Here, we have demonstrated the ability of tilorone to activate NK cells and specific subpopulations of cytotoxic CD4+ and CD8+ T lymphocytes that recognize immune-evasive tumor cells and kill them via the FasL-Fas interaction. We have also performed a comparative analysis of characteristics between lymphocytes activated in the fraction of human peripheral blood mononuclear cells (PBMCs) upon treatment with different stimulants of the immune response: tilorone, innate immunity protein Tag7, and cytokine IL-2, a regulator of adaptive immunity. The results show that all the three stimulants, regardless of their nature, activate lymphocytes that are identical with respect to the spectrum of target cells, phenotype, and mechanism of cytotoxic action However, these stimulants induce different mechanisms of lymphocyte activation at early stages of the immune response. © 2018 IUBMB Life, 71(3):376-384, 2019.

The role of IL-3 in bone.

In the recent past, there has been a burgeoning interest in targeting cytokines such as IL-3 for specific disease conditions of bone such as rheumatoid arthritis and multiple myeloma. Unlike other cytokines, IL-3 is a cytokine with a multilineage potential and broad spectrum of target cells and it plays a vital role in hematopoiesis. Due to its common receptor subunit, the action of IL-3 shows functional redundancy with other cytokines such as the granulocyte-macrophage colony-stimulating factor and IL-5. IL-3 has been successfully used in ameliorating radiation-induced bone marrow aplasia and similar conditions. However, the role of IL-3 in bone cells has not been fully unraveled yet; therefore, the aim of this overview is to present the effects of IL-3 in bone with a special emphasis on osteoclasts and osteoblasts in a concise manner.

Innate immunity protein Tag7 (PGRP-S) activates lymphocytes capable of Fasl-Fas-dependent contact killing of virus-infected cells.

The innate immunity protein Tag7 (PGRP-S, PGLYRP1) is involved in antimicrobial and antitumor defense. As shown in our previous studies, Tag7 specifically interacts with the major heat shock protein Hsp70 to form a stable Tag7-Hsp70 complex with cytotoxic activity against tumor cells. A stable complex of Tag7 with the calcium-binding protein Mts1 (S100A4) stimulates migration of lymphocytes. Moreover, Tag7 can activate cytotoxic lymphocytes that recognize and kill HLA-negative tumor cells. Here, we have shown that Tag 7 treatment of human peripheral blood mononuclear cells (PBMCs) results in activation of different cytotoxic lymphocyte populations-natural killer (NK) cells and CD8+ NKG2D+ T lymphocytes-that kill Moloney murine leukemia virus (MMLV) infected SC-1 cells using different mechanisms of cell death induction. This mechanism in NK cells is based on the release of granzymes, which activate apoptosis in target cells, while CD8+ NKG2D+ T lymphocytes recognize the noncanonical MicA antigen on the surface of virus-containing cells and kill them via the FasL-Fas interaction, triggering the apoptotic or necroptotic cell death pathway. Preliminary incubation of PBMCs with virus-infected cells and following incubation with Tag7 results in activation of lymphocytes with a different phenotype. These lymphocytes change the spectrum of target cells and the mechanism of cell death induction, and their interaction with target cells is not species-specific. © 2017 IUBMB Life, 69(12):971-977, 2017.

The Soluble Interleukin 6 Receptor: Advanced Therapeutic Options in Inflammation.

Interleukin (IL)-6 binds to IL-6R and the complex of IL-6 and IL-6R associates with the receptor subunit gp130, which initiates signaling. gp130 is expressed on all cells. IL-6R is cleaved by the ADAM17, generating a soluble IL-6R (sIL-6R). The sIL-6R binds IL-6 and the complex of IL-6 and sIL-6R binds to gp130 even on cells that do not express IL-6R. This process, which has been called IL-6 trans-signaling, increases the spectrum of target cells for IL-6. We generated a protein, sgp130Fc, which inhibits IL-6 trans-signaling without affecting IL-6 classic signaling. Using the sgp130Fc protein we demonstrated that IL-6 classic signaling is antiinflammatory and protective, whereas IL-6 trans-signaling is proinflammatory. Blocking IL-6 trans-signaling does not compromise the defense of the body against bacterial infections. We suggest that sgp130Fc is a superior agent as compared to IL-6 or IL-6R antibodies to block IL-6. The sgp130Fc protein is in phase II clinical trials.

CCL4 as an adjuvant for DNA vaccination in a Her2/neu mouse tumor model.

Chemokines are key regulators of both innate and adaptive immune responses. CCL4 (macrophage inflammatory protein-1β, MIP-1β) is a CC chemokine that has a broad spectrum of target cells including immature dendritic cells, which express the cognate receptor CCR5. We asked whether a plasmid encoding CCL4 is able to improve tumor protection and immune responses in a Her2/neu+ mouse tumor model. Balb/c mice were immunized twice intramuscularly with plasmid DNA on days 1 and 15. On day 25, a tumor challenge was performed with 2 × 10(5) syngeneic Her2/neu+ D2F2/E2 tumor cells. Different groups of mice were vaccinated with pDNA(Her2/neu) plus pDNA(CCL4), pDNA(Her2/neu), pDNA(CCL4) or mock vector alone. Our results show that CCL4 is able to (i) improve tumor protection and (ii) augment a TH1-polarized immune response against Her2/neu. Although Her2/neu-specific humoral and T-cell immune responses were comparable with that induced in previous studies using CCL19 or CCL21 as adjuvants, tumor protection conferred by CCL4 was inferior. Whether this is due to a different spectrum of (innate) immune cells, remains to be clarified. However, combination of CCL19/21 with CCL4 might be a reasonable approach in the future, particularly for DNA vaccination in Her2/neu+ breast cancer in the situation of minimal residual disease.

Alanine-Scanning Mutational Analysis of Durancin GL Reveals Residues Important for Its Antimicrobial Activity.

Durancin GL is a novel class IIa bacteriocin with 43 residues produced by Enterococcus durans 41D. This bacteriocin demonstrates narrow inhibition spectrum and potent antimicrobial activity against several Listeria monocytogenes strains, including nisin-resistant L. monocytogenes NR30. A systematic alanine-scanning mutational analysis with site-directed mutagenesis was performed to analyze durancin GL residues important for antimicrobial activity and specificity. Results showed that three mutations lost their antimicrobial activity, ten mutations demonstrated a decreased effect on the activity, and seven mutations exhibited relatively high activity. With regard to inhibitory spectrum, four mutants demonstrated a narrower antimicrobial spectrum than wild-type durancin GL. Another four mutants displayed a broader target cell spectrum and increased potency relative to wild-type durancin GL. These findings broaden our understanding of durancin GL residues important for its antimicrobial activity and contribute to future rational design of variants with increased potency.

Comparative Analysis of Host Cell Entry of Ebola Virus From Sierra Leone, 2014, and Zaire, 1976.

The ongoing Ebola virus (EBOV) disease (EVD) epidemic in Western Africa is the largest EVD outbreak recorded to date and requires the rapid development and deployment of antiviral measures. The viral glycoprotein (GP) facilitates host cell entry and, jointly with cellular interaction partners, constitutes a potential target for antiviral intervention. However, it is unknown whether the GPs of the currently and previously circulating EBOVs use the same mechanisms for cellular entry and are thus susceptible to inhibition by the same antivirals and cellular defenses. Here, we show that the GPs of the EBOVs circulating in 1976 and 2014 transduce the same spectrum of target cells, use the same cellular factors for host cell entry, and are comparably susceptible to blockade by antiviral interferon-induced transmembrane proteins and neutralizing antibody KZ52. Thus, the viruses responsible for the ongoing EVD epidemic should be fully susceptible to established antiviral strategies targeting GP and cellular entry factors.

Integration-deficient Lentiviral Vectors Expressing Codon-optimized R338L Human FIX Restore Normal Hemostasis in Hemophilia B Mice

Integration-deficient lentiviral vectors (IDLVs) have been shown to transduce a wide spectrum of target cells and organs in vitro and in vivo and to maintain long-term transgene expression in nondividing cells. However, epigenetic silencing of episomal vector genomes reduces IDLV transgene expression levels and renders these safe vectors less efficient. In this article, we describe for the first time a complete correction of factor IX (FIX) deficiency in hemophilia B mice by IDLVs carrying a novel, highly potent human FIX cDNA. A 50-fold increase in human FIX cDNA potency was achieved by combining two mechanistically independent yet synergistic strategies: (i) optimization of the human FIX cDNA codon usage to increase human FIX protein production per vector genome and (ii) generation of a highly catalytic mutant human FIX protein in which the arginine residue at position 338 was substituted with leucine. The enhanced human FIX activity was not associated with liver damage or with the formation of human FIX-directed inhibitory antibodies and rendered IDLV-treated FIX-knockout mice resistant to a challenging tail-clipping assay. A novel S1 nuclease-based B1-quantitative polymerase chain reaction assay showed low levels of IDLV integration in mouse liver. Overall, this study demonstrates that IDLVs carrying an improved human FIX cDNA safely and efficiently cure hemophilia B in a mouse model.

Oncogenic herpesviruses sending mixed signals.

Human herpesvirus infections are generally asymptomatic in immune-competent hosts; however, immune dysfunction can unveil inherent oncogenic properties associated with Epstein-Barr virus (EBV) and Kaposi’s sarcoma herpesvirus (KSHV) infection. Although these viruses were first discovered in human tumor specimens in 1964 and 1994, respectively, it was discovered later on that large proportions of the human population are persistently infected with EBV and to a lesser extent KSHV. To colonize immune-competent hosts, EBV and KSHV drive proliferation of newly infected cells by latent transcription programs. EBV infection is principally limited to B cells, and few infected epithelial cells in the oral mucosa that produce infectious virus for host–host transmission via the saliva. In contrast, KSHV has a broader spectrum of target cells while transmission and life cycle are less well understood. However, these viruses share a host-colonization and persistence strategy that involves activation of NF-κB, a critical survival factor for developing human B cells. Deregulated NF-κB activation can cause uncontrolled B-cell proliferation and secretion of proinflammatory factors that support cancer development. Apart from protumorigenic soluble factors, many tumor cells release endosome-derived vesicles, called exosomes, which mediate intercellular communication. In PNAS, Meckes et al. describe that EBV- and KSHV-infected lymphoma cells secrete exosomes with distinct repertoires of cellular proteins (1). In light of recent studies demonstrating that tumor cell-derived exosomes exert protumorigenic signaling properties (2), the data presented by Meckes et al. suggest that virus and tumor cells share common strategies in shaping a permissive microenvironment by modulating the cargo of secreted exosomes (Fig. 1).

Tumors with processing defects display novel tumor antigens via the non-classical HLA-E

Event Abstract Back to Event Tumors with processing defects display novel tumor antigens via the non-classical HLA-E Elien M. Doorduijn1, Claudia Cunha Oliveira1, Bianca Querido1, Marjolein Sluijter1 and Thorbald Van Hall1* 1 Leiden University Medical Center, Netherlands The non-classical HLA-E accommodates monomorphic leader peptides and functions as a ligand for germ line receptors CD94/NKG2, expressed by natural killer cells and CD8+ T cells. We previously described that the conserved peptides are replaced by a novel peptide repertoire of surprising diversity as a result of impairments in the antigen processing pathway. Whereas the monomorphic peptide/HLA-E complex represents the ‘innate face’ of HLA-E, this novel peptide repertoire constitutes immunogenic neo-antigens for CD8+ T cells. We found that T cells restricted by the mouse equivalent Qa-1b dominantly participated in the response to tumors with processing deficiencies. A surprisingly wide spectrum of target cells, irrespective of transformation status, MHC background or type of processing deficiency was recognized by this T cell subset, complying with the conserved nature of Qa-1b. Target cell recognition depended on T cell receptor and Qa-1b interaction and immunization with identified peptide-epitopes demonstrated in vivo priming of CD8+ T cells. Current investigations are focused on the involved rearranged TCRs that confer the tumor reactivity Although this CD8 T cell subset does arise in the periphery of TCR-transgenic animals, the thymic selection process seems to be very inefficient. Our data reveal that HLA-E and its mouse homolog Qa-1b are important for the defense against processing deficient cells by displacing the monomorphic leader peptides, which relieves the inhibition through CD94/NKG2A on lymphocytes and by presenting a novel repertoire of immunogenic peptides, which recruits a subset of cytotoxic CD8+ T cells. References Oliveira CC, van Veelen PA, Querido B, de Ru A, Sluijter M, Laban S, Drijfhout JW, van der Burg SH, Offringa R, van Hall T. The nonpolymorphic MHC Qa-1b mediates CD8+ T cell surveillance of antigen-processing defects. J Exp Med. 2010 Jan 18;207(1):207-21. Seidel UJ, Oliveira CC, Lampen MH, Hall Tv. A novel category of antigens enabling CTL immunity to tumor escape variants: Cinderella antigens. Cancer Immunol Immunother. 2012 Jan;61(1):119-25. van Hall T, Wolpert EZ, van Veelen P, Laban S, van der Veer M, Roseboom M, Bres S, Grufman P, de Ru A, Meiring H, de Jong A, Franken K, Teixeira A, Valentijn R, Drijfhout JW, Koning F, Camps M, Ossendorp F, Kärre K, Ljunggren HG, Melief CJ, Offringa R. Selective cytotoxic T-lymphocyte targeting of tumor immune escape variants. Nat Med. 2006 Apr;12(4):417-24. Lampen MH, van Hall T. Strategies to counteract MHC-I defects in tumors. Curr Opin Immunol. 2011 Apr;23(2):293-8. Oliveira CC, Querido B, Sluijter M, Derbinski J, van der Burg SH, van Hall T. Peptide transporter TAP mediates between competing antigen sources generating distinct surface MHC class I peptide repertoires. Eur J Immunol. 2011 Nov;41(11):3114-24. Keywords: HLA-E, CTL, neoantigen, Qa-1, tumorimmunology Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Adaptive Immunity Citation: Doorduijn EM, Cunha Oliveira C, Querido B, Sluijter M and Van Hall T (2013). Tumors with processing defects display novel tumor antigens via the non-classical HLA-E. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00728 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 Jun 2013; Published Online: 22 Aug 2013. * Correspondence: Mr. Thorbald Van Hall, Leiden University Medical Center, Leiden, 2333 ZA, Netherlands, t.van_hall@lumc.nl Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Elien M Doorduijn Claudia Cunha Oliveira Bianca Querido Marjolein Sluijter Thorbald Van Hall Google Elien M Doorduijn Claudia Cunha Oliveira Bianca Querido Marjolein Sluijter Thorbald Van Hall Google Scholar Elien M Doorduijn Claudia Cunha Oliveira Bianca Querido Marjolein Sluijter Thorbald Van Hall PubMed Elien M Doorduijn Claudia Cunha Oliveira Bianca Querido Marjolein Sluijter Thorbald Van Hall Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The nonpolymorphic MHC Qa-1b mediates CD8+ T cell surveillance of antigen-processing defects

The nonclassical major histocompatibility complex (MHC) Qa-1b accommodates monomorphic leader peptides and functions as a ligand for germ line receptors CD94/NKG2, which are expressed by natural killer cells and CD8+ T cells. We here describe that the conserved peptides are replaced by a novel peptide repertoire of surprising diversity as a result of impairments in the antigen-processing pathway. This novel peptide repertoire represents immunogenic neoantigens for CD8+ T cells, as we found that these Qa-1b-restricted T cells dominantly participated in the response to tumors with processing deficiencies. A surprisingly wide spectrum of target cells, irrespective of transformation status, MHC background, or type of processing deficiency, was recognized by this T cell subset, complying with the conserved nature of Qa-1b. Target cell recognition depended on T cell receptor and Qa-1b interaction, and immunization with identified peptide epitopes demonstrated in vivo priming of CD8+ T cells. Our data reveal that Qa-1b, and most likely its human homologue human leukocyte antigen-E, is important for the defense against processing-deficient cells by displacing the monomorphic leader peptides, which relieves the inhibition through CD94/NKG2A on lymphocytes, and by presenting a novel repertoire of immunogenic peptides, which recruits a subset of cytotoxic CD8+ T cells.

The nonpolymorphic MHC Qa-1b mediates CD8+ T cell surveillance of antigen-processing defects

The nonclassical major histocompatibility complex (MHC) Qa-1b accommodates monomorphic leader peptides and functions as a ligand for germ line receptors CD94/NKG2, which are expressed by natural killer cells and CD8+ T cells. We here describe that the conserved peptides are replaced by a novel peptide repertoire of surprising diversity as a result of impairments in the antigen-processing pathway. This novel peptide repertoire represents immunogenic neoantigens for CD8+ T cells, as we found that these Qa-1b–restricted T cells dominantly participated in the response to tumors with processing deficiencies. A surprisingly wide spectrum of target cells, irrespective of transformation status, MHC background, or type of processing deficiency, was recognized by this T cell subset, complying with the conserved nature of Qa-1b. Target cell recognition depended on T cell receptor and Qa-1b interaction, and immunization with identified peptide epitopes demonstrated in vivo priming of CD8+ T cells. Our data reveal that Qa-1b, and most likely its human homologue human leukocyte antigen-E, is important for the defense against processing-deficient cells by displacing the monomorphic leader peptides, which relieves the inhibition through CD94/NKG2A on lymphocytes, and by presenting a novel repertoire of immunogenic peptides, which recruits a subset of cytotoxic CD8+ T cells.

434. Recombinant Adeno-Associated Virus 2 -Mediated Anti-Angiogenic Gene Therapy in a Mouse Model of Intraperitoneal Ovarian Cancer

Tumor anti-angiogenic therapy using gene transfer vectors widens the promise of adjuvant cancer therapy by its ability to produce therapeutic molecules at high concentration within the localized target cells for a sustained period of time with a single administration. Recombinant adeno-associated virus vectors (rAAV) are promising for gene therapy applications due to their long-term transgene expression and wide spectrum of target cells. Our recent studies demonstrated that intramuscular administration of rAAV encoding secretable forms of angiostatin and/or endostatin provided significant growth inhibition of subcutaneously implanted human ovarian cancer cell line, SKOV3.ip1. In the present studies, we sought to evaluate the potential of rAAV encoding angiostatin and endostatin in inhibiting intraperitoneal (i.p.) ovarian cancer growth and dissemination. An i.p. model of ovarian cancer in female athymic mice was established with injection of SKOV3ip1 xenografts. Mice were injected intramuscularly with 1.2 × 1011 v.p./mouse, rAAV encoding endostatin and angiostatin. Control mice either did not receive any vector or were injected with equivalent dose of rAAV-GFP. Three weeks after virus administration, 106 SKOV3ip1 cells were intraperitoneally injected.

Sp1 and Sp3 transcription factors synergistically regulate HGF receptor gene expression in kidney.

We investigated the expression pattern and underlying mechanism that controls hepatocyte growth factor (HGF) receptor (c-met) expression in normal kidney and a variety of kidney cells. Immunohistochemical staining showed widespread expression of c-met in mouse kidney, a pattern closely correlated with renal expression of Sp1 and Sp3 transcription factors. In vitro, all types of kidney cells tested expressed different levels of c-met, which was tightly proportional to the cellular abundances of Sp1 and Sp3. Both Sp1 and Sp3 bound to the multiple GC boxes in the promoter region of the c-met gene. Coimmunoprecipitation suggested a physical interaction between Sp1 and Sp3. Functionally, Sp1 markedly stimulated c-met promoter activity. Although Sp3 only weakly activated the c-met promoter, its combination with Sp1 synergistically stimulated c-met transcription. Conversely, deprivation of Sp proteins by transfection of decoy Sp1 oligonucleotide or blockade of Sp1 binding with mithramycin A inhibited c-met expression. The c-met receptor in all types of kidney cells was functional and induced protein kinase B/Akt phosphorylation in a distinctly dynamic pattern after HGF stimulation. These results indicate that members of the Sp family of transcription factors play an important role in regulating constitutive expression of the c-met gene in all types of renal cells. Our findings suggest that HGF may have a broader spectrum of target cells and possess wider implications in kidney structure and function than originally thought.

Cell-Type-Specific Characteristics Modulate the Transduction Efficiency of Adeno-Associated Virus Type 2 and Restrain Infection of Endothelial Cells

Adeno-associated viruses (AAVs) are promising vectors for various gene therapy applications due to their long-lasting transgene expression and wide spectrum of target cells. Recently, however, it has become apparent that there are considerable differences in the efficiencies of transduction of different cell types by AAVs. Here, we analyzed the efficiencies of transduction and the transport mechanisms of AAV type 2 (AAV-2) in different cell types, emphasizing endothelial cells. Expression analyses in both cultured cells and the rabbit carotid artery assay showed a remarkably low level of endothelial cell transduction in comparison to the highly permissive cell types. The study of the endosomal pathways of AAV-2 with fluorescently labeled virus showed clear targeting of the Golgi area in permissive cell lines, but this phenomenon was absent in the endothelial cell line EAhy-926. On the other hand, the response to the block of endosomal acidification by bafilomycin A1 also showed differences among the permissive cell types. We also analyzed the effect of proteasome inhibitors on endothelial cells, but their impact on the primary cells and in vivo was not significant. On the contrary, analysis of the expression pattern of heparan sulfate proteoglycans (HSPGs), the primary receptors of AAV-2, revealed massive deposits of HSPG in the extracellular matrix of endothelial cells. The matrix-associated receptors may therefore compete for virus binding and reduce transduction in endothelial cells. Accordingly, in endothelial cells detached from their matrix, AAV-2 transduction was significantly increased. Altogether, these results point to a more complex cell-type-specific mode of transduction of AAV-2 than previously appreciated.

The chemokine system: tuning and shaping by regulation of receptor expression and coupling in polarized responses.

The chemokine system: tuning and shaping by regulation of receptor expression and coupling in polarized responses.

Transduction of human MCP-3 by a parvoviral vector induces leukocyte infiltration and reduces growth of human cervical carcinoma cell xenografts.

The oncosuppressive properties of some autonomous parvoviruses such as H-1 virus, together with their low pathogenicity, make them attractive vectors for tumor-directed gene therapy. Indeed, it was recently shown that these viruses became endowed with an enhanced oncosuppressive activity after they had been engineered to deliver a recognized therapeutic transgene. This prompted us to use a parvoviral vector to analyse the antineoplastic capacity of MCP-3 (monocyte chemotactic protein-3), a CC chemokine which has a broad spectrum of target cells, and can thus be considered to be a promising candidate for cancer treatment. We explored the use of a parvovirus H-1-based vector encoding human MCP-3 for its antitumor potential on human cervical carcinoma cells. HeLa cells were infected in vitro with the recombinant virus hH1/MCP-3 at a low multiplicity [1 replication unit (RU)/cell] and we investigated the effect of parvovirus-mediated MCP-3 transduction on tumor formation and growth upon implantation of HeLa cells in nude mice. Infection of HeLa cells with hH1/MCP-3 led to secretion of high levels of MCP-3 and to significant retardation of tumor growth in recipient mice, as compared with HeLa cells that were either buffer-treated or infected with a MCP-3-free vector. Tumors from hH1/MCP-3-infected HeLa cells were heavily infiltrated with activated macrophages and showed increased numbers of dendritic cells. In addition, activated natural killer (NK) cells were also recruited into MCP-3-transduced tumors. These observations indicate that parvovirus H-1-transduced MCP-3 is able to exert a significant antitumor activity which is mediated, at least in part, through macrophages and NK cells, under conditions in which activated T cells are lacking.

Hepatocytes are permissive for human cytomegalovirus infection in human liver cell culture and In vivo.

The cytopathic potential of human cytomegalovirus (HCMV) in human liver cells was analyzed in cell culture and in tissue sections from patients with HCMV hepatitis. Liver cell cultures, consisting of hepatocytes, bile duct epithelial cells, and stromal cells were infected by various HCMV strains. Cytopathic effects, viral gene expression, and virus production were detected. Infected cell types were identified by immunocytochemical double labeling. Hepatocytes were the predominant target cells of HCMV infection in liver tissues and in cell culture. Late-stage infected cultured hepatocytes produced infectious progeny virus, and infectious virus was propagated from liver tissue specimens. HCMV infection in cultured liver cells closely resembled in vivo infection of the liver with regard to the target cell spectrum and the permissive course of infection. It is concluded that HCMV can cause direct liver parenchyma damage by efficient cytolytic infection of hepatocytes.