Human Immune System Mouse Models Research Articles

Development of Advanced Human Immune System Mouse Models for Pre-Clinical Research in Immuno-oncology

Abstract Background The reconstitution of a fully functional human immune system in the NCG mouse (hu-NCG) provides a unique opportunity to assess the efficacy of new drug candidates acting on human immune cells such as T cells, myeloid cells and NK cells. Enhanced NCG mice have been further developed to boost the differentiation of myeloid and NK cells, allowing scientists to efficiently test new antibodies or small molecules targeting these immune cell populations. Methods A fully functional human immune system has been reconstituted in NCG mice after the transplantation of CD34+ human stem cells (hu-NCG model). Then, cell-line derived xenografts (CDX) and patient derived xenografts (PDX) have been engrafted in the hu-NCG model. The tumor growth has been monitored and the immune response assessed by flow cytometry. Results We observed infiltration of human immune cells in the tumors. Furthermore, checkpoint inhibitors such as anti-PD1 strongly reduced tumor growth in hu-NCG demonstrating the potency of this model in onco-immunology. Alternatively, we demonstrated that hu-NCG, immunized against cancer antigens elicits strong T cell response as well as IgG production. Conclusion Collectively, the huNCG mouse model demonstrats its relevance for the preclinical testing (Mono and Combo therapies) of drugs in immuno-oncology. Legal entity responsible for the study The authors. Funding Transcure Bioservices. Disclosure All authors have declared no conflicts of interest.

Accelerated thymopoiesis and improved T-cell responses in HLA-A2/-DR2 transgenic BRGS-based human immune system mice.

Human immune system (HIS) mouse models provide a robust in vivo platform to study human immunity. Nevertheless, the signals that guide human lymphocyte differentiation in HIS mice remain poorly understood. Here, we have developed a novel Balb/c Rag2-/- Il2rg-/- SirpaNOD (BRGS) HIS mouse model expressing human HLA-A2 and -DR2 transgenes (BRGSA2DR2). When comparing BRGS and BRGSA2DR2 HIS mice engrafted with human CD34+ stem cells, a more rapid emergence of T cells in the circulation of hosts bearing human HLA was shown, which may reflect a more efficient human T-cell development in the mouse thymus. Development of CD4+ and CD8+ T cells was accelerated in BRGSA2DR2 HIS mice and generated more balanced B and T-cell compartments in peripheral lymphoid organs. Both B- and T-cell function appeared enhanced in the presence of human HLA transgenes with higher levels of class switched Ig, increased percentages of polyfunctional T cells and clear evidence for antigen-specific T-cell responses following immunization. Taken together, the presence of human HLA class I and II molecules can improve multiple aspects of human B- and T-cell homeostasis and function in the BRGS-based HIS mouse model.

A human immune system mouse model with robust lymph node development.

Lymph nodes (LNs) facilitate the cellular interactions that orchestrate immune responses. Human immune system (HIS) mice are powerful tools for interrogation of human immunity but lack secondary lymphoid tissue (SLT) as a result of a deficiency in Il2rg-dependent lymphoid tissue inducer cells. To restore LN development, we induced expression of thymic-stromal-cell-derived lymphopoietin (TSLP) in a Balb/c Rag2-/-Il2rg-/-SirpaNOD (BRGS) HIS mouse model. The resulting BRGST HIS mice developed a full array of LNs with compartmentalized human B and T cells. Compared with BRGS HIS mice, BRGST HIS mice have a larger thymus, more mature B cells, and abundant IL-21-producing follicular helper T (TFH) cells, and show enhanced antigen-specific responses. Using BRGST HIS mice, we demonstrated that LN TFH cells are targets of acute HIV infection and represent a reservoir for latent HIV. In summary, BRGST HIS mice reflect the effects of SLT development on human immune responses and provide a model for visualization and interrogation of regulators of immunity.

Human Immune System Mice for the Study of Human Immunodeficiency Virus-Type 1 Infection of the Central Nervous System.

Immunodeficient mice transplanted with human cell populations or tissues, also known as human immune system (HIS) mice, have emerged as an important and versatile tool for the in vivo study of human immunodeficiency virus-type 1 (HIV-1) pathogenesis, treatment, and persistence in various biological compartments. Recent work in HIS mice has demonstrated their ability to recapitulate critical aspects of human immune responses to HIV-1 infection, and such studies have informed our knowledge of HIV-1 persistence and latency in the context of combination antiretroviral therapy. The central nervous system (CNS) is a unique, immunologically privileged compartment susceptible to HIV-1 infection, replication, and immune-mediated damage. The unique, neural, and glia-rich cellular composition of this compartment, as well as the important role of infiltrating cells of the myeloid lineage in HIV-1 seeding and replication makes its study of paramount importance, particularly in the context of HIV-1 cure research. Current work on the replication and persistence of HIV-1 in the CNS, as well as cells of the myeloid lineage thought to be important in HIV-1 infection of this compartment, has been aided by the expanded use of these HIS mouse models. In this review, we describe the major HIS mouse models currently in use for the study of HIV-1 neuropathogenesis, recent insights from the field, limitations of the available models, and promising advances in HIS mouse model development.

Stem Cell Factor Consistently Improves Thymopoiesis after Experimental Transplantation of Murine or Human Hematopoietic Stem Cells in Immunodeficient Mice

Deficient thymopoiesis is a pivotal determinant of impaired immune competence following hematopoietic stem cell transplantation (HSCT). Stem cell factor (SCF) is essentially involved in early thymopoiesis. We evaluated whether SCF administration would improve recovery of thymopoiesis following HSCT in immunodeficient mice receiving: 1) bone marrow (BM) transplantation of congenic mice; or 2) human fetal liver HSCT in the human immune system mouse model. Following murine BM transplantation, SCF significantly enhanced thymopoiesis and peripheral T cell recovery in lymph nodes and spleen. SCF did not affect BM lymphoid progenitor recovery and/or expansion. Median thymic cellularity increased from 0.9 in PBS- to 266 × 10(4)/thymus in SCF-treated mice (p = 0.05). Following human HSCT in human immune system mice, higher thymic cellularity was observed in SCF-treated mice. Double-negative and early double-positive thymocyte subsets increased, but especially late double-positive, CD4 single-positive, and CD8 single-positive thymocyte subsets were significantly enhanced (p < 0.05). These results show that exogenous supply of SCF may significantly improve murine and human posttransplant thymopoiesis, for which the effect is probably exerted by directly promoting T cell development intrathymically rather than by enhanced entry of prethymically expanded lymphoid progenitors.

HTLV-1-infected HIS Rag2-/-γc-/- mice, a suitable model for in vivo investigating the effects of drugs in ATL treatment?

Adult T cell Leukemia, an aggressive T-cell malignancy linked to HTLV-1 infection, is resistant to chemotherapy. Recently, promising results were obtained with the combination of arsenic trioxide, interferon alpha and zidovudine. However, the cellular and molecular mechanisms of their anti-leukemia activity remain to be investigated. To that aim, we have relied on HIS (Human Immune System) Rag2-/-γc-/- mice. We have indeed observed that when infected with HTLV-1, these mice displayed, five months later, an elevated number of human Tax-expressing T cells in the thymus, the spleen and the mesenteric lymph nodes. Some of them also developed T lymphoproliferative diseases. To determine the effects of these three drugs on the apparition of these pathological features, Rag2-/-γc-/- mice were infected with HTLV-1 and, 16 weeks after infection, daily treated with the drugs for one week and sacrificed. Untreated HIS mice infected with HTLV-1 were used as control. Treatment resulted in a significant decrease in the spleen weight as compared to untreated controls. Interestingly, we also noted a decrease of the proviral load in thymocytes as well as a drop in the number of mature activated T cells in the spleen and in lymph nodes. These data clearly indicate that the HIS mouse model provides us with the opportunity not only for the pre-clinical evaluation of therapeutic approaches against the leukemogenic process associated with HTLV-1 infection, but also for unraveling the corresponding mechanisms.

Abstract 4745: TLR8 agonist and Doxil chemotherapy potently activate human antitumor immune response in a human immune system mouse model

Abstract Because of differences between mouse and human immune systems, many of the effects of immunomodulatory drugs cannot be fully studied in syngeneic mouse models. We thus generated a novel tumor-bearing mouse model with human immune system (HIS) to study interactions between chemotherapy and immune modulatory therapy. We tested the individual effects and the interactions between doxorubicin, a drug which induces immunogenic tumor cell death and activates antigen-presenting cells, and VTX-2337, a novel small-molecule TLR8 agonist, which induces potent activation and type 1 polarization of human myeloid DCs but is inactive on murine leukocytes. Nod/SCID/ILRγc knock out (NSG) mice were inoculated with human CD34+ cord blood cells from HLA-A2+ human donors; transplanted s.c. with human HLA-A2+ OVCAR5 ovarian cancer tumors; and treated with pegylated liposomal doxorubicin (Doxil); VTX-2337; or a combination. NSG-HIS mice exhibited a full human hematopoietic system, including human monocytes, macrophages and plasmacytoid and myeloid DCs as well as T and B cell subsets. In NSG-HIS mice, VTX-2337 induced dose-dependent activation of human Monocytes CD14+ and CD11c+ cells with upregulation of CD80, CD86, CD83, CD40 and MHCII within 6 hrs. Transient, dose-dependent upregulation of human Th1 cytokines but also IL-10 was observed in the plasma of treated mice, reaching peaks within 6 hrs and subsiding within 24 hrs. Doxil induced mild activation of CD11c+ DCs and mild upregulation of Th1 cytokines. The combination of two drugs induced potent activation of CD11c+ DCs and marked increase in Th1 cytokines with significant decrease of IL-10. HLA-A2+ OVCAR5 tumors were successfully engrafted, exhibiting infiltration by human leukocytes. VTX-2337 and Doxil treatment independently induced tumor-infiltrating lymphocytes and restricted growth of human ovarian tumor xenografts in a dose-dependent manner, while the combination of the two drugs induced the highest frequency of Leukocytes (hCD45) and potently restricted growth of ovarian tumors. Combined activation of innate and adaptive immunity by VTX-2337 and Doxil, as well sensitization of tumor cells by Doxil to adaptive and innate immune effector mechanisms was at the basis of the observed interactions suppressing tumor growth. We conclude that the NSG-HIS provided a suitable tool to establish potent interactions between TLR8 agonist and Doxil chemotherapy, which warrant clinical testing. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4745. doi:10.1158/1538-7445.AM2011-4745