NOD-scid IL2rγnull mice lacking TLR4 support human immune system development and the study of human-specific innate immunity

Agents that induce inflammation have been used since the 18th century for the treatment of cancer. The inflammation induced by agents such as Toll-like receptor agonists is thought to stimulate tumor-specific immunity in patients and augment control of tumor burden. While NOD-scid IL2rγnull mice lack murine adaptive immunity (T cells and B cells), these mice maintain a residual murine innate immune system that responds to Toll-like receptor agonists. Here we describe a novel NOD-scid IL2rγnull mouse lacking murine TLR4 that fails to respond to lipopolysaccharide. NSG-Tlr4null mice support human immune system engraftment and enable the study of human-specific responses to TLR4 agonists in the absence of the confounding effects of a murine response. Our data demonstrate that specific stimulation of TLR4 activates human innate immune systems and delays the growth kinetics of a human patient-derived xenograft melanoma tumor.

Abstract 1070: Evaluation of human NK cell responses to PDX tumors in humanized NOD-scid IL2rg null (NSG) mice expressing human IL15

Human innate immunity plays a critical role in tumor surveillance and in immunoregulation within the tumor microenvironment. Natural killer (NK) cells are innate lymphoid cells that have opposing roles in the tumor microenvironment, including NK cell subsets that mediate tumor cell cytotoxicity and subsets with regulatory function that contribute to the tumor immune suppressive environment. The balance between effector and regulatory NK cell subsets has been studied extensively in murine models of cancer, but there is a paucity of models to study human NK cell function in tumorigenesis. Humanized mice are a powerful alternative to syngeneic mouse tumor models for the study of human immuno-oncology and have proven effective tools to test immunotherapies targeting T cells. However human NK cell development and survival in humanized mice are severely limited. To enhance NK cell development, we have developed NSG mice that constitutively expresses human IL15 using a BAC containing the human IL15 gene: NSG-Tg(Hu-IL15) (NOD.Cg-Prkdcscid Il2rgtm1Wjl Tg(IL15)1Sz/SzJ; JAX stock number 030890). NSG-Tg(Hu-IL15) mice express a physiological level of human IL15 (7.1 ± 0.3 pg/ml) and support engraftment of human CD34+ hematopoietic stem cells (HSC). Following HSC-engraftment of NSG-Tg(Hu-IL15) mice, significantly higher levels of human CD56+ NK cells are detectable as compared to NSG mice in peripheral blood and within the spleen and bone marrow. Levels of circulating human CD3+ T cells, CD20+ B cells and CD33+ myeloid cells are similar between the HSC-engrafted NSG-Tg(Hu-IL15) and NSG mice. We have described that the human NK cells developing in HSC-engrafted NSG-Tg(Hu-IL15) mice are functional, mediating direct cytotoxicity and ADCC. We have now extended these observation by evaluating the ability of human NK cells to control growth of a PDX melanoma in humanized NSG-Tg(Hu-IL15) mice. Our observations indicate that the growth kinetics of the PDX melanoma are significantly delayed in HSC-engrafted NSG-Tg(Hu-IL15) mice as compared to HSC-engrafted NSG mice. Importantly PDX melanoma growth is not significantly different in NSG-Tg(Hu-IL15) and NSG that are not engrafted with human immune systems. To determine the immune cell subsets contributing to the delayed PDX growth in HSC-engrafted NSG-Tg(Hu-IL15) mice we performed experiments where either human CD8 T cells or human NK cells were depleted. Depletion of human CD8 T cells did not alter the PDX growth kinetics in HSC-engrafted NSG-Tg(Hu-IL15). In contrast, NK cell depletion abrogated the delayed growth of the PDX melanoma, suggesting that human NK cells are directly suppressing tumor growth in HSC-engrafted NSG-Tg(Hu-IL15) mice. Together these data demonstrate that HSC-engrafted NSG-Tg(Hu-IL15) mice support enhanced development of functional human NK cells and that these NK cells limit the growth of PDX tumors.

Citation Format: Ken-Edwin Aryee, Lisa Burzenski, Dale L. Greiner, Giles F. Whalen, Li-Chin Yao, Leonard D. Shultz, James G. Keck, Michael A. Brehm. Evaluation of human NK cell responses to PDX tumors in humanized NOD-scid IL2rgnull (NSG) mice expressing human IL15 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1070.

Abstract 1522: NovelNOD-scid IL2rg null(NSG)mice for preclinical evaluation of TLR agonists in cancer immunotherapy

TLR agonists that induce inflammation have been used since the 18thcentury for the treatment of cancer. The inflammation induced by TLR agonists is thought to stimulate tumor-specific immunity in patients and augment control of tumor burden. Although only two forms of TLR agonists are currently FDA approved for cancer treatment, Bacillus Calmette-Guerin and monophosphoryl lipid A, several clinical trials are ongoing with new TLR agonists, including trials targeting TLR3 and TLR4 pathways. Currently there is a paucity of preclinical models to evaluate the efficacy of TLR agonists in activating human immune responses and to assess the impact on tumor growth.Humanized mice are emerging as an exciting translationalplatform to study human immuno-oncology and provide tools to test new immunotherapies. Our laboratory uses NSG mice that have been humanized with hematopoietic stem cells (HSC) to study human immunity and to evaluate therapeutics. While NSG mice lack murine adaptive immunity (T and B cells), these mice maintain a residual innate immune system with the potential to respond to TLR agonists. Challenge of unengrafted NSG mice with either LPS or poly(I:C) stimulates production of mouse cytokines and maturation of murine innate immune cells. Moreover, LPS or poly(I:C) challenge of NSG bearing a PDX melanoma significantly delays tumor growth kinetics in the absence of an engrafted human immune system. Thus differentiating between human and mouse responses to TLR agonist is difficult in currently available NSG mice. To address this issue, we have created NSG mice lacking TLR4 and Type 1 IFNR1 that fail to respond to LPS and poly(I:C), respectively. Challenge of unengrafted NSG-TLR4nulland NSG-IFNR1nullmice bearing a PDX melanoma with LPS and poly(I:C), respectively, had minimal impact on tumor growth kinetics, confirming the utility of these novel NSG strains to study specifically human immune responses to TLR agonists. To validate the NSG-TLR4nullmouse, we humanized these mice with HSC and evaluated human immune system development and function as compared to HSC-engrafted NSG mice. Our results show that human immune system development in HSC-engrafted NSG-TLR4nullmice is comparable to HSC-engrafted NSG mice with similar levels of human CD45+ cells, CD3+ T cells, CD20+ B cells, and CD33+ myeloid cells detectable in blood and spleen. Moreover, both HSC-engrafted NSG-TLR4nulland NSG mice show similar activation profiles of human innate immune cells and human cytokine production following challenge with LPS. Lastly, LPS challenge of HSC-engrafted NSG-TLR4nullmice bearing a PDX melanoma significantly reduced tumor growth kinetics. These findings demonstrate that NSG-TLR4nullmice are an effective tool to test TLR4 agonists for the ability to activate human immunity and to assess impacts on tumor growth in the absence of the confounding effects of the murine innate immune system.

Citation Format: Ken-Edwin Aryee, Lisa Burzenski, Dale Greiner, Giles F. Whalen, Leonard Shultz, James Keck, Michael Brehm. NovelNOD-scid IL2rgnull(NSG)mice for preclinical evaluation of TLR agonists in cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1522.

Creation of PDX-Bearing Humanized Mice to Study Immuno-oncology

A significant obstacle to the study of human cancer biology and the testing of human specific immunotherapeutics is the paucity of translational models that recapitulate both the growth of human tumors and the functionality of human immune systems. Humanized mice engrafted with human hematopoietic stem cells (HSC) and patient-derived xenografts (PDX) enable preclinical investigation of the interactions between the human immune system and human cancer. We use immunodeficient non-obese diabetic (NOD, scid, gamma) NSG™ or NSG™-SGM3 mice as hosts for establishment of human immunity following HSC injection and for engraftment of human tumors. Here we describe a refined protocol for the subcutaneous implant of solid PDX tumors into humanized mice. Protocols to recover infiltrating immune cells from growing tumors and to evaluate the immune cell subsets by flow cytometry are also described.

Abstract 5674: Transgenic expression of human IL15 in NOD-scid IL2rg null (NSG) mice enhances the development and survival of functional human NK cells

The human innate immune system plays critical roles in tumor surveillance and in immunoregulation within the tumor microenvironment. Natural killer (NK) cells are innate lymphoid cells that mediate tumor cell killing by antibody-dependent cell mediated cytotoxicity (ADCC), through direct recognition, and by the expression of chimeric antigen receptors that directly target tumors. However, NK cell subsets with regulatory functionality also contribute to the tumor immune suppressive environment that enables tumor growth. The balance between effector and regulatory NK cell subsets has been studied extensively in murine models of cancer, but there is a paucity of models to study human NK cell function in tumorigenesis, which is restricted primarily to in vitro experiments. Humanized mice are a powerful alternative to syngeneic mouse tumor models for the study of human immuno-oncology and have proven effective tools to test immunotherapies targeting T cells. However human NK cell development and survival in humanized mice are severely limited. Previous studies have demonstrated that injection or transient expression of human IL15 enables efficient development of functional human NK cells within immunodeficient mice that were engrafted with CD34+ HSC. Based on these results we established NSG mice that constitutively expresses human IL15. The NSG-Tg(Hu-IL15) mice were generated using a BAC containing the human IL15 gene, and express a physiological level of human IL15 (7.1 ± 0.3 pg/ml). To evaluate human NK cell development, 8 to 12-week-old NSG and NSG-Tg(Hu-IL15) mice received 200 cGy irradiation and were then injected intravenously with 1x105 CD34+ HSC derived from umbilical cord blood. No difference in overall survival of HSC-engrafted NSG-Tg(Hu-IL15) mice compared to NSG mice were observed during the experiment, indicating that expression of IL15 did not increase mortality. Levels of circulating human CD45+ cells, T cells and B cells were similar between the HSC-engrafted NSG-Tg(Hu-IL15) and NSG mice. Significantly higher levels of human CD56+ NK cells were found in NSG-Tg(Hu-IL15) mice as compared to NSG mice at all time points tested in the peripheral blood and within the spleen and bone marrow. A higher proportion of human CD56+ NK cells recovered from the blood and spleen of NSG-Tg(Hu-IL15) mice expressed granzyme A, granzyme B and perforin as compared to NK cells from NSG mice, suggesting that the NK cells were functional. Moreover, human NK cells enriched from the NSG-Tg(Hu-IL15) mice lysed K562 cells in an in vitro cytotoxicity assay. These data demonstrate that HSC-engrafted NSG mice expressing human IL15 support enhanced development of functional human NK cells and suggest that HSC-engrafted NSG-Tg(Hu-IL15) mice are a powerful model to study the role of NK cells in tumor-immune system interactions and to test immunotherapies targeting NK cells.

Citation Format: Ken-Edwin Aryee, Lisa Burzenski, Dale L. Greiner, Raymond M. Welsh, Leonard D. Shultz, James G. Keck, Michael A. Brehm. Transgenic expression of human IL15 in NOD-scid IL2rgnull (NSG) mice enhances the development and survival of functional human NK cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5674.

Abstract 5676: Patient-derived tumor xenografts in humanized NSG-SGM3 mice: An improved immuno-oncology platform

The JAX® Onco-Hu® platform utilizes humanized mice engrafted with tumors to enable in vivo investigation of the interactions between the human immune system and human cancer. We have recently shown that humanized NOD-scid IL2Rγnull (NSG™) mice bearing patient-derived xenografts (PDX) allow efficacy studies of checkpoint inhibitors. A major avenue of our investigation is to generate murine humanized models containing a more complete human hematopoietic system and robust innate immune cell population. Next-generation NSG strains include triple transgenic NSG mice (NSG-SGM3) expressing myelosupportive human cytokines KITLG, CSF2, and IL-3. When engrafted with CD34+ human hematopoietic progenitor cells (HPCs) from CD3-depleted umbilical cord blood, NSG-SGM3 mice produce higher myeloid and Treg populations in the circulation as compared to NSG mice over 18 weeks post engraftment. We implanted an array of PDX tumors into humanized NSG-SGM3 mice at 2-3 months post engraftment. Tumors were dissociated and single-cell infiltrates were analyzed by multicolor flow cytometry with a focus on examining overall immune cell infiltration and the levels of hCD33+ myeloid cells. In the PS4050 melanoma PDX model, we found that hCD45+ cell infiltration was significantly increased in hu-NSG-SGM3 mice as compared to hu-NSG mice engrafted with the same HPC donor (3.7% vs. 1% of viable cells). The majority of tumor-infiltrating cells in hu-NSG-SGM3 mice expressed hCD33 (55% of hCD45+) and the percentage was significantly higher than that in hu-NSG mice (13%). hCD3+T cell infiltration level was similar between these two strains (~20% of hCD45+). PS4050-bearing hu-NSG-SGM3 mice treated with the anti-PD-1 antibody pembrolizumab (Keytruda) showed a significant reduction in tumor growth and the PD-1 levels in tumor-infiltrating T cells were greatly reduced by flow cytometry analysis. The overall hCD45+ cell infiltration and the frequencies of hCD4+T, hCD8+T, and hCD33+myeloid cells in tumors remained similar after treatment. Lastly, we observed that the effect of Keytruda on tumor growth reduction in hu-NSG-SGM3 mice is PD-L1-dependent using the human lung carcinoma cell line NCI-H460 depleted of PD-L1 expression by CRISPR. Keytruda treatment significantly reduced mock-transfected NCI-H460 cell growth. By comparison, PD-L1 KO NCI-H460 cells grew more slowly than the mock cells and lost the response to Keytruda. Together, these results indicate that PDX tumor-implanted hu-NSG-SGM3 mice serve as an important platform for understanding human immune system and tumor microenvironment interactions and for preclinical immuno-oncology efficacy studies.

Citation Format: Li-Chin Yao, Mingshan Cheng, Ken-Edwin Aryee, Pooja Kumar, Nicole Walsh, Dale Greiner, Leonard Shultz, Edison T. Liu, Michael Brehm, James G. Keck. Patient-derived tumor xenografts in humanized NSG-SGM3 mice: An improved immuno-oncology platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5676.

Transgenic expression of human IL15 in NOD-scid IL2rg null (NSG) mice enhances the development and survival of functional human NK cells

Human NK cells have critical roles in tumor surveillance and in immunoregulation within the tumor microenvironment. The balance between effector and regulatory NK cell subsets has been studied extensively in murine models of cancer, but there is a paucity of models to study human NK cell function. Humanized mice are a powerful alternative to study of human immuno-oncology and have proven effective tools to test immunotherapies targeting T cells. However human NK cell development and survival in humanized mice are severely limited. Based on previous studies showing the importance of human IL15 for NK cell development, we established NSG mice that constitutively expresses human IL15 (7.1 ± 0.3 pg/ml). To evaluate human NK cell development, 8 to 12-week-old NSG and NSG-Tg(Hu-IL15) mice were irradiated and injected intravenously with CD34+ HSC derived from umbilical cord blood. Levels of circulating human CD45+ cells, T cells and B cells were similar between the HSC-engrafted NSG-Tg(Hu-IL15) and NSG mice. Significantly higher levels of human CD56+ NK cells were found in NSG-Tg(Hu-IL15) mice as compared to NSG mice at all time points and in all tissues tested. A higher proportion of human CD56+ NK cells recovered from the blood and spleen of NSG-Tg(Hu-IL15) mice expressed granzyme A, granzyme B and perforin as compared to NK cells from NSG mice, suggesting that the NK cells were functional. Moreover, human NK cells enriched from the NSG-Tg(Hu-IL15) mice lysed K562 cells in an in vitro cytotoxicity assay. These data demonstrate that HSC-engrafted NSG mice expressing human IL15 support enhanced development of functional human NK cells and suggest that HSC-engrafted NSG-Tg(Hu-IL15) mice are a powerful model to study human NK cells.

Possible type 1 diabetes risk prediction: Using ultrasound imaging to assess pancreas inflammation in the inducible autoimmune diabetes BBDR model

Background/Aims

Studies of human cadaveric pancreas specimens indicate that pancreas inflammation plays an important role in type 1 diabetes pathogenesis. Due to the inaccessibility of pancreas in living patients, imaging technology to visualize pancreas inflammation is much in need. In this study, we investigated the feasibility of utilizing ultrasound imaging to assess pancreas inflammation longitudinally in living rats during the progression leading to type 1 diabetes onset.

Methods

The virus-inducible BBDR type 1 diabetes rat model was used to systematically investigate pancreas changes that occur prior to and during development of autoimmunity. The nearly 100% diabetes incidence upon virus induction and the highly consistent time course of this rat model make longitudinal imaging examination possible. A combination of histology, immunoblotting, flow cytometry, and ultrasound imaging technology was used to identify stage-specific pancreas changes.

Results

Our histology data indicated that exocrine pancreas tissue of the diabetes-induced rats underwent dramatic changes, including blood vessel dilation and increased CD8+ cell infiltration, at a very early stage of disease initiation. Ultrasound imaging data revealed significant acute and persistent pancreas inflammation in the diabetes-induced rats. The pancreas micro-vasculature was significantly dilated one day after diabetes induction, and large blood vessel (superior mesenteric artery in this study) dilation and inflammation occurred several days later, but still prior to any observable autoimmune cell infiltration of the pancreatic islets.

Conclusions

Our data demonstrate that ultrasound imaging technology can detect pancreas inflammation in living rats during the development of type 1 diabetes. Due to ultrasound’s established use as a non-invasive diagnostic tool, it may prove useful in a clinical setting for type 1 diabetes risk prediction prior to autoimmunity and to assess the effectiveness of potential therapeutics.

Humanized Mouse Models of Clinical Disease

Immunodeficient mice engrafted with functional human cells and tissues, that is, humanized mice, have become increasingly important as small, preclinical animal models for the study of human diseases. Since the description of immunodeficient mice bearing mutations in the IL2 receptor common gamma chain (IL2rg^null) in the early 2000s, investigators have been able to engraft murine recipients with human hematopoietic stem cells that develop into functional human immune systems. These mice can also be engrafted with human tissues such as islets, liver, skin, and most solid and hematologic cancers. Humanized mice are permitting significant progress in studies of human infectious disease, cancer, regenerative medicine, graft-versus-host disease, allergies, and immunity. Ultimately, use of humanized mice may lead to the implementation of truly personalized medicine in the clinic. This review discusses recent progress in the development and use of humanized mice and highlights their utility for the study of human diseases.

A novel transgenic mouse model of lysosomal storage disorder

Knockout technology has proven useful for delineating functional roles of specific genes. Here we describe and provide an explanation for striking pathology that occurs in a subset of genetically engineered mice expressing a rat Ca_Vβ2a transgene under control of the cardiac α-myosin heavy chain promoter. Lesions were limited to mice homozygous for transgene and independent of native Cacnb2 genomic copy number. Gross findings included an atrophied pancreas; decreased adipose tissue; thickened, orange intestines; and enlarged liver, spleen, and abdominal lymph nodes. Immune cell infiltration and cell engulfment by macrophages were associated with loss of pancreatic acinar cells. Foamy macrophages diffusely infiltrated the small intestine's lamina propria, while similar macrophage aggregates packed liver and splenic red pulp sinusoids. Periodic acid-Schiff-positive, diastase-resistant, iron-negative, Oil Red O-positive, and autofluorescent cytoplasm was indicative of a lipid storage disorder. Electron microscopic analysis revealed liver sinusoids distended by clusters of macrophages containing intracellular myelin "swirls" and hepatocytes with enlarged lysosomes. Additionally, build up of cholesterol, cholesterol esters, and triglycerides, along with changes in liver metabolic enzyme levels, were consistent with a lipid processing defect. Because of this complex pathology, we examined the transgene insertion site. Multiple transgene copies inserted into chromosome 19; at this same site, an approximate 180,000 base pair deletion occurred, ablating cholesterol 25-hydroxylase and partially deleting lysosomal acid lipase and CD95 Loss of gene function can account for the altered lipid processing, along with hypertrophy of the immune system, which define this phenotype, and serendipitously provides a novel mouse model of lysosomal storage disorder.

Modeling immune system-tumor interactions using humanized mice

The interplay between tumor cells, the non-malignant stoma and hematolymphoid cells (of both innate and adoptive lineages) determines the kinetics of cancer progression. However, the study of tumor-immune system interactions has primarily been restricted to mouse models. The implant of tumors into humanized mice that are engrafted with human immune systems provides a unique opportunity to interrogate the interactions between human immune cells and malignancies, and to test novel anti-tumor immunotherapies. Here we show the use of the BLT (bone marrow/liver/thymus) humanized mouse model to study the interactions between the human immune system and melanoma. The BLT mouse supports high levels of human immune system development including HLA-restricted T cells, B cells and innate immune cells. For these studies, we used NOD-scid IL2rnull (NSG) transgenically expressing SCF, GM-CSF and IL-3 (NSG-SGM3), which enhances human innate immune cell development and function. Following implant of patient derived melanomas into NSG-SGM3 BLT mice, we observed the infiltration of human T cells, mast cells, NK cells and macrophages into the tumor microenviroment. Moreover the recovery of high levels of FoxP3+ regulatory T cells, M2 macrophage and conventional CD4 and CD8 T cells expressing PD-1 and CTLA4 from the tumor suggests that the melanoma growing within NSG-SGM3 BLT mice creates an immune regulatory environment similar to that seen in patients. These results indicate that tumors implanted into NSG-SGM3 BLT mice can be used as an effective model for understanding tumor-immune system interactions.

Beyond the brain: disrupted in schizophrenia 1 regulates pancreatic β-cell function via glycogen synthase kinase-3β

Individuals with schizophrenia and their first-degree relatives have higher rates of type 2 diabetes (T2D) than the general population (18-30 vs. 1.2-6.3%), independent of body mass index and antipsychotic medication, suggesting shared genetic components may contribute to both diseases. The cause of this association remains unknown. Mutations in disrupted in schizophrenia 1 (DISC1) increase the risk of developing psychiatric disorders [logarithm (base 10) of odds = 7.1]. Here, we identified DISC1 as a major player controlling pancreatic β-cell proliferation and insulin secretion via regulation of glycogen synthase kinase-3β (GSK3β). DISC1 expression was enriched in developing mouse and human pancreas and adult β- and ductal cells. Loss of DISC1 function, through siRNA-mediated depletion or expression of a dominant-negative truncation that models the chromosomal translocation of human DISC1 in schizophrenia, resulted in decreased β-cell proliferation (3 vs. 1%; P < 0.01), increased apoptosis (0.1 vs. 0.6%; P < 0.01), and glucose intolerance in transgenic mice. Insulin secretion was reduced (0.5 vs. 0.1 ng/ml; P < 0.05), and critical β-cell transcription factors Pdx1 and Nkx6.1 were significantly decreased. Impaired DISC1 allowed inappropriate activation of GSK3β in β cells, and antagonizing GSK3β (SB216763; IC50 = 34.3 nM) rescued the β-cell defects. These results uncover an unexpected role for DISC1 in normal β-cell physiology and suggest that DISC1 dysregulation contributes to T2D independently of its importance for cognition.

Development of humanized mouse models to study human immune system-tumor interactions (TUM10P.1055)

Cancer progression involves interplay between tumor cells and non-malignant stoma, including immune cells. Our understanding of the interactions between immune systems and tumors is based mostly on mouse models. However many differences exist between murine and human biology, and translation of findings from mice to clinical application is challenging. The study of human immune systems and tumors is limited by logistical and ethical restrictions of working with primary specimens from patients. Here we describe a humanized mouse model to study the in vivo interactions between human immune systems and human tumors. In these studies NOD-scid IL2rgnull (NSG) mice expressing human SCF, GM-CSF and IL-3 (NSG-SGM3) were engrafted with human fetal thymus and fetal liver-derived hematopoietic stem cells (BLT). NSG-SGM3-BLT mice support high levels of human cell chimerism, including development of human myeloid cells, T cells and B cells. Engrafted NSG-SGM3-BLT mice were implanted with patient melanoma cells and monitored for tumor growth and immune system homeostasis. The human melanoma grew with similar kinetics in NSG-SGM3-BLT mice as compared to control NSG-SGM3 mice. Human immune cells, including human macrophage and T cells, infiltrated the melanoma. The T cell infiltrate was dominated by human FOXP3+ Treg and by PD1+ CD4 and CD8 T cells. These data show that NSG-SGM3-BLT mice, are a promising model to study human immune system-tumor interactions and to test novel therapies.

The development of humanized mouse models to study immune regulation of autoreactive T cells. (BA15P.229)

Type 1 diabetes (T1D) is the immune mediated destruction of insulin-producing beta cells in the pancreas, characterized by the loss of peripheral tolerance mechanisms needed to prevent autoimmunity. Regulatory T-cells (TREG) are a specialized CD4 T cell subset important for maintaining peripheral tolerance. IL-2 is critical to maintain TREG fitness and function, and deficiencies in the IL-2 receptor and signaling pathways contribute to the development of T1D. The lack of an in vivo system that fully recapitulates human T1D development impairs the ability to study the role of IL-2 signaling in T1D. Here we show that the Hu-PBL-SCID humanized mouse model can be used to study effector T cells and TREG from T1D-individuals. For these studies we injected PBMC from T1D or non-T1D donors into NOD Rag1null IL2rγnull (NRG) mice and followed the engraftment of human T cell populations. Our results show that PBMC from T1D donors engraft NRG mice with similar kinetics as compared to non-T1D donors. Moreover, our preliminary data show that expression of human IL-2 in recipient NRG mice improves T1D TREG frequency and survival. These results indicate that humanized mice are an effective model for studying autoreactive T cells from diabetic individuals

Immunodeficient mouse model for human hematopoietic stem cell engraftment and immune system development

Immunodeficient mice engrafted with human immune systems provide an exciting model to study human immunobiology in an in vivo setting without placing patients at risk. The essential parameter for creation of these "humanized models" is engraftment of human hematopoietic stem cells (HSC) that will allow for optimal development of human immune systems. However, there are a number of strategies to generate humanized mice and specific protocols can vary significantly among different laboratories. Here we describe a protocol for the co-implantation of human HSC with autologous fetal liver and thymic tissues into immunodeficient mice to create a humanized model with optimal human T cell development. This model, often referred to as the Thy/Liv or BLT (bone marrow, liver, thymus) mouse, develops a functional human immune system, including HLA-restricted human T cells, B cells, and innate immune cells.