Early Effects of HTLV-1 Infection on the Activation, Exhaustion, and Differentiation of T-Cells in Humanized NSG Mice.

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive malignancy of CD4 T-cells associated with HTLV-1 infection. In this study, we used the model of immunodeficient NSG mice reconstituted with a functional human immune system (HIS) to investigate early events in HTLV-1 pathogenesis. Upon infection, human T-cells rapidly increased in the blood and lymphoid tissues, particularly CD4CD25 T-cells.

Diverse HIV-1 escape pathways from broadly neutralizing antibody PGDM1400 in humanized mice.

Recent studies have shown the potential of broadly neutralizing antibodies (bnAbs) for HIV-1 treatment. One of the candidate antibodies moving into clinical trials is the bnAb PGDM1400. Here, we studied the therapeutic potency and escape pathways of bnAb PGDM1400 during monovalent therapy in human immune system (HIS) mice using the BG505, REJO, MJ4 and AMC008 virus isolates.

Short Communication: Protective Efficacy of Broadly Neutralizing Antibody PGDM1400 Against HIV-1 Challenge in Humanized Mice.

Broadly neutralizing antibodies (bNAbs) such as PGDM1400 show promise as prophylactic and therapeutic agents against HIV-1. Human immune system mice were passively immunized with different doses of PGDM1400 and challenged 24 h later with a high dose of HIV-1. We found that PGDM1400 provided protection against HIV-1 challenge in a concentration dependent manner and that the protective concentration in blood was ∼75-fold higher than the in vitro 50% inhibitory concentration.

The NOTCH1/CD44 axis drives pathogenesis in a T cell acute lymphoblastic leukemia model.

NOTCH1 is a prevalent signaling pathway in T cell acute lymphoblastic leukemia (T-ALL), but crucial NOTCH1 downstream signals and target genes contributing to T-ALL pathogenesis cannot be retrospectively analyzed in patients and thus remain ill defined. This information is clinically relevant, as initiating lesions that lead to cell transformation and leukemia-initiating cell (LIC) activity are promising therapeutic targets against the major hurdle of T-ALL relapse. Here, we describe the generation in vivo of a human T cell leukemia that recapitulates T-ALL in patients, which arises de novo in immunodeficient mice reconstituted with human hematopoietic progenitors ectopically expressing active NOTCH1.

Different Balance of Wnt Signaling in Adult and Fetal Bone Marrow-Derived Mesenchymal Stromal Cells.

Mesenchymal stromal cells (MSCs) are applied as novel therapeutics for their regenerative and immune-suppressive capacities. Clinical applications, however, require extensive expansion of MSCs. Fetal bone marrow-derived MSCs (FBMSCs) proliferate faster than adult bone marrow-derived MSC (ABMSCs).

A novel mouse model for stable engraftment of a human immune system and human hepatocytes.

Hepatic infections by hepatitis B virus (HBV), hepatitis C virus (HCV) and Plasmodium parasites leading to acute or chronic diseases constitute a global health challenge. The species tropism of these hepatotropic pathogens is restricted to chimpanzees and humans, thus model systems to study their pathological mechanisms are severely limited. Although these pathogens infect hepatocytes, disease pathology is intimately related to the degree and quality of the immune response.

Acoustic devices for particle and cell manipulation and sensing.

An emerging demand for the precise manipulation of cells and particles for applications in cell biology and analytical chemistry has driven rapid development of ultrasonic manipulation technology. Compared to the other manipulation technologies, such as magnetic tweezing, dielectrophoresis and optical tweezing, ultrasonic manipulation has shown potential in a variety of applications, with its advantages of versatile, inexpensive and easy integration into microfluidic systems, maintenance of cell viability, and generation of sufficient forces to handle particles, cells and their agglomerates. This article briefly reviews current practice and reports our development of various ultrasonic standing wave manipulation devices, including simple devices integrated with high frequency (>20 MHz) ultrasonic transducers for the investigation of biological cells and complex ultrasonic transducer array systems to explore the feasibility of electronically controlled 2-D and 3-D manipulation.

Preclinical in vivo evaluation of the safety of a multi-shRNA-based gene therapy against HIV-1.

Highly active antiretroviral therapy (HAART) has significantly improved the quality of life and the life expectancy of HIV-infected individuals. Still, drug-induced side effects and emergence of drug-resistant viral variants remain important issues that justify the exploration of alternative therapeutic options. One strategy consists of a gene therapy based on RNA interference to induce the sequence-specific degradation of the HIV-1 RNA genome.

Human type 1 innate lymphoid cells accumulate in inflamed mucosal tissues.

Innate lymphoid cells (ILCs) are effectors of innate immunity and regulators of tissue modeling. Recently identified ILC populations have a cytokine expression pattern that resembles that of the helper T cell subsets T(H)2, T(H)17 and T(H)22. Here we describe a distinct ILC subset similar to T(H)1 cells, which we call 'ILC1'.

A novel mouse model for Sézary syndrome using xenotransplantation of Sézary cells into immunodeficient RAG2(-/-) γc(-/-) mice.

Sézary syndrome (SS) is an aggressive cutaneous T-cell lymphoma with CD4+ tumor cells localized in the skin, lymph nodes and peripheral blood. Characteristic molecular aberrancies in SS have been identified; however, paucity of functional models severely hampered the translation of these observations into pathogenic mechanisms, and subsequent validation of novel therapeutic targets. We therefore developed a mouse model for SS using intrahepatic injection of SS cells in newborn immunodeficient RAG2(-/-) γc(-/-) mice that are completely devoid of T-, B- and NK-cell activity.

A doxycycline-dependent human immunodeficiency virus type 1 replicates in vivo without inducing CD4+ T-cell depletion.

A novel genetic approach for the control of virus replication was used for the design of a conditionally replicating human immunodeficiency virus (HIV) variant, HIV-rtTA. HIV-rtTA gene expression and virus replication are strictly dependent on the presence of a non-toxic effector molecule, doxycycline (dox), and thus can be turned on and off at will in a graded and reversible manner. The in vivo replication capacity, pathogenicity and genetic stability of this HIV-rtTA variant were evaluated in a humanized mouse model of haematopoiesis that harbours lymphoid and myeloid components of the human immune system (HIS).

Functional CD47/signal regulatory protein alpha (SIRP(alpha)) interaction is required for optimal human T- and natural killer- (NK) cell homeostasis in vivo.

The homeostatic control mechanisms regulating human leukocyte numbers are poorly understood. Here, we assessed the role of phagocytes in this process using human immune system (HIS) BALB/c Rag2(-/-)IL-2Rγc(-/-) mice in which human leukocytes are generated from transplanted hematopoietic progenitor cells. Interactions between signal regulatory protein alpha (SIRPα; expressed on phagocytes) and CD47 (expressed on hematopoietic cells) negatively regulate phagocyte activity of macrophages and other phagocytic cells.

Autonomous and extrinsic regulation of thymopoiesis in human immune system (HIS) mice.

Human Immune System (HIS) mice represent a novel biotechnology platform to dissect human haematopoiesis and immune responses. However, the limited human T-cell development that is observed in HIS mice restricts its utility for these applications. Here, we address whether reduced thymopoiesis in HIS mice reflects an autonomous defect in T-cell precursors and/or a defect in the murine thymic niche.

Idiopathic CD4+ T lymphopenia without autoimmunity or granulomatous disease in the slipstream of RAG mutations.

A girl presented during childhood with a single course of extensive chickenpox and moderate albeit recurrent pneumonia in the presence of idiopathic CD4+ T lymphocytopenia (ICL). Her clinical condition remained stable over the past 10 years without infections, any granulomatous disease, or autoimmunity. Immunophenotyping demonstrated strongly reduced naive T and B cells with intact proliferative capacity.

Nuclear receptors Nur77 and Nurr1 modulate mesenchymal stromal cell migration.

Detailed understanding of mesenchymal stromal cells (MSC) migration is imperative for future cellular therapies. To identify genes involved in the process of MSC migration, we generated gene expression profiles of migrating and nonmigrating fetal bone marrow MSC (FBMSC). Only 12 genes showed differential expression in migrating versus nonmigrating FBMSC.

Disruption of heparan sulfate proteoglycan conformation perturbs B-cell maturation and APRIL-mediated plasma cell survival.

The development and antigen-dependent differentiation of B lymphocytes are orchestrated by an array of growth factors, cytokines, and chemokines that require tight spatiotemporal regulation. Heparan sulfate proteoglycans specifically bind and regulate the bioavailability of soluble protein ligands, but their role in the immune system has remained largely unexplored. Modification of heparan sulfate by glucuronyl C5-epimerase (Glce) controls heparan sulfate-chain flexibility and thereby affects ligand binding.

IL-15 transpresentation promotes both human T-cell reconstitution and T-cell-dependent antibody responses in vivo.

Cytokine immunotherapies targeting T lymphocytes are attractive clinical interventions against viruses and tumors. In the mouse, the homeostasis of memory α/β CD8(+) T cells and natural killer (NK) cells is significantly improved with increased IL-15 bioavailability. In contrast, the role of "transpresented" IL-15 on human T-cell development and homeostasis in vivo is unknown.

Generation of human antigen-specific monoclonal IgM antibodies using vaccinated "human immune system" mice.

Background: Passive transfer of antibodies not only provides immediate short-term protection against disease, but also can be exploited as a therapeutic tool. However, the 'humanization' of murine monoclonal antibodies (mAbs) is a time-consuming and expensive process that has the inherent drawback of potentially altering antigenic specificity and/or affinity. The immortalization of human B cells represents an alternative for obtaining human mAbs, but relies on the availability of biological samples from vaccinated individuals or convalescent patients.

Thymic stromal lymphopoietin induces early human B-cell proliferation and differentiation.

Thymic stromal lymphopoietin (TSLP) is a cytokine that binds the IL-7-receptor-alpha chain and a unique TSLP receptor (TSLPR) chain. The role of TSLP in human B-cell development has not been elucidated. We show that TSLPR transcripts are expressed most prominently in CD34(+) cells from fetal liver and BM.

In vivo modulation of gene expression by lentiviral transduction in "human immune system" Rag2-/- gamma c -/- mice.

Over the last two decades, several humanized mouse models have been used to experimentally analyze the function and development of the human immune system. Recent advances have lead to the establishment of new murine-human chimeric models with improved characteristics, both in terms of human engraftment efficiency and in situ multilineage human hematopoietic development. We describe here the use of newborn BALB/c Rag2(-/-)gamma(c) (-/-) mice as recipients of human hematopoietic progenitor cells to produce "human immune system" (HIS) (BALB-Rag/gamma) mice, using human fetal liver progenitors.

IL-7 enhances thymic human T cell development in "human immune system" Rag2-/-IL-2Rgammac-/- mice without affecting peripheral T cell homeostasis.

IL-7 is a central cytokine in the development of hematopoietic cells, although interspecies discrepancies have been reported. By coculturing human postnatal thymus hematopoietic progenitors and OP9-huDL1 stromal cells, we found that murine IL-7 is approximately 100-fold less potent than human IL-7 for supporting human T cell development in vitro. We investigated the role of human IL-7 in newborn BALB/c Rag2(-/-)gamma(c)(-/-) mice transplanted with human hematopoietic stem cells (HSC) as an in vivo model of human hematopoiesis using three approaches to improve IL-7 signaling: administration of human IL-7, ectopic expression of human IL-7 by the transplanted human HSC, or enforced expression of a murine/human chimeric IL-7 receptor binding murine IL-7.

Cell cycle and tissue of origin contribute to the migratory behaviour of human fetal and adult mesenchymal stromal cells.

Mesenchymal stromal cells (MSC) are potential cells for cellular therapies, in which the recruitment and migration of MSC towards injured tissue is crucial. Our data show that culture-expanded MSC from fetal lung and bone marrow, adult bone marrow and adipose tissue contained a small percentage of migrating cells in vitro, but the optimal stimulus was different. Overall, fetal lung-MSC had the highest migratory capacity.

Autoregulatory lentiviral vectors allow multiple cycles of doxycycline-inducible gene expression in human hematopoietic cells in vivo.

The efficient control of gene expression in vivo from lentiviral vectors remains technically challenging. To analyze inducible gene expression in a human setting, we generated 'human immune system' (HIS) mice by transplanting newborn BALB/c Rag2(-/-)IL-2Rgamma(c)(-/-) immunodeficient mice with human hematopoietic stem cells transduced with a doxycycline-inducible lentiviral vector. We compared several methods of doxycycline delivery to mice, and could accurately measure doxycycline in vivo using a new sensitive detection assay.