Mouse models with human immunity and their application in biomedical research

Biomedical research in human beings is largely restricted to in vitro studies that lack complexity of a living organism. To overcome this limitation, humanized mouse models are developed based on immunodeficient characteristics of severe combined immunodeficiency (SCID) or recombination activating gene (Rag)^null mice, which can accept xenografts. Peripheral constitution of human immunity in SCID or Rag^null mice has been achieved by transplantation of mature human immune cells, foetal human thymus, bone marrow, liver tissues, lymph nodes or a combination of these, although efficiency needs to be improved. These mouse models with constituted human immunity (defined as humanized mice in the present text) have been widely used to investigate the basic principles of human immunobiology as well as complex pathomechanisms and potential therapies of human diseases. Here, elements of an ideal humanized mouse model are highlighted including genetic and non-genetic modification of recipient mice, transplantation strategies and proposals to improve engraftments. The applications of the humanized mice to study the development and response of human immune cells, human autoimmune diseases, virus infections, transplantation biology and tumour biology are reviewed as well.     

Strongyloides stercoralis: oral transfer of parasitic adult worms produces infection in mice and infection with subsequent autoinfection in gerbils.

Oral transfer of parasitic adult Strongyloides stercoralis produced patent infections in gerbils, C57BL/6J and SCID mice. In gerbils receiving adult worms, 7.3% of the transferred worms established and autoinfective L3 were found beginning on day 5 post-transfer, with peak numbers seen on days 6 and 7 post-transfer and few seen by 9 days post-transfer. These results suggest that development of autoinfective L3 in the gerbil is limited by the immune response of the host. When given orally to mice, between 7.2% (C57BL/6J) and 19.5% (SCID) of the adult worms established. These levels are higher than those previously obtained by the subcutaneous infection of SCID mice with infective larvae. No autoinfective larvae were found in infected mice and the ratio of L1/adult worms was small compared with that seen in gerbils. Thus, mice infected orally can be used as a model to study the interaction between the adult worm and the host, and since autoinfection has not been seen in the murine model, as developed to date, orally infected mice may be useful as a model to study mechanisms preventing autoinfection.     

A syndromic approach to common parasitic diseases

Standard textbooks discuss parasitic disease according to specific organisms. In contrast, patients with parasitic infections present to physicians with a variety of clinical manifestations that may involve any of several organ systems and that often mimic nonparasitic diseases. A syndromic approach to the clinical situation may help the physician in considering the most important parasitic agents. Many parasitic infections can be acquired in temperate climates. While often considered tropical or exotic, other parasitic diseases are now seen more frequently in developed countries because of immigration and increased world travel. In this review the clinical syndromes associated with common parasitic diseases in North America are discussed, with an emphasis on risk factors and diagnosis of specific infections.     

车轮虫分类与系统发育研究进展

车轮虫属一大类寄生性纤毛虫原生动物,可不同程度地给宿主造成危害,故对其研究既具有理论意义,又具有经济价值。文中简单回顾了车轮虫的分类研究和系统发育研究的历史。在分类学研究领域方面,全面介绍了目前车轮虫科已发现属的寄生部位和地理分布等;而系统发育研究领域方面,则介绍了车轮虫研究在萌芽期、探索期和发展期这三个时期的进展,包括形态学和分子生物学两方面的研究内容。并对该领域今后应进行的研究提出了建议。     

Human Taenia in severe combined immunodeficiency (SCID) mice

A rodent model for the development of the larval stages of human taeniid tapeworms would help advance immunodiagnosis in human and domestic animals and vaccine development for cysticercosis cellulosae or bovis in domestic animals. Here, Akira Ito and Mamoru Ito review recent results demonstrating the potential of the severe combined immunodeficiency (SCID) mouse for supporting development of the larval stages of Taenia saginata asiatica, T. saginata and T. solium.     

Immunomodulation by helminth parasites: Defining mechanisms and mediators

Epidemiological and interventional human studies, as well as experiments in animal models, strongly indicate that helminth parasitic infections can confer protection from immune dysregulatory diseases such as allergy, autoimmunity and colitis. Here, we review the immunological pathways that helminths exploit to downregulate immune responses, both against bystander specificities such as allergens and against antigens from the parasites themselves. In particular, we focus on a highly informative laboratory system, the mouse intestinal nematode, Heligmosomoides polygyrus, as a tractable model of host-parasite interaction at the cellular and molecular levels. Analysis of the molecules released in vitro (as excretory-secretory products) and their cellular targets is identifying individual parasite molecules and gene families implicated in immunomodulation, and which hold potential for future human therapy of immunopathological conditions.     

Functional human T lymphocyte development from cord blood CD34+ cells in nonobese diabetic/Shi-scid,IL-2 receptor gamma null mice

An experimental model for human T lymphocyte development from hemopoietic stem cells is necessary to study the complex processes of T cell differentiation in vivo. In this study, we report a newly developed nonobese diabetic (NOD)/Shi-scid, IL-2Rgamma null (NOD/SCID/gamma(c)(null)) mouse model for human T lymphopoiesis. When these mice were transplanted with human cord blood CD34(+) cells, the mice reproductively developed human T cells in their thymus and migrated into peripheral lymphoid organs. Furthermore, these T cells bear polyclonal TCR-alphabeta, and respond not only to mitogenic stimuli, such as PHA and IL-2, but to allogenic human cells. These results indicate that functional human T lymphocytes can be reconstituted from CD34(+) cells in NOD/SCID/gamma(c)(null) mice. This newly developed mouse model is expected to become a useful tool for the analysis of human T lymphopoiesis and immune response, and an animal model for studying T lymphotropic viral infections, such as HIV.     

Utility of immunodeficient mouse models for characterizing the preclinical pharmacokinetics of immunogenic antibody therapeutics

Prior to clinical studies, the pharmacokinetics (PK) of antibody-based therapeutics are characterized in preclinical species; however, those species can elicit immunogenic responses that can lead to an inaccurate estimation of PK parameters. Immunodeficient (SCID) transgenic hFcRn and C57BL/6 mice were used to characterize the PK of three antibodies that were previously shown to be immunogenic in mice and cynomolgus monkeys. Four mouse strains, Tg32 hFcRn SCID, Tg32 hFcRn, SCID and C57BL/6, were administered adalimumab (Humira®), mAbX and mAbX-YTE at 1 mg/kg, and in SCID strains there was no incidence of immunogenicity. In non-SCID strains, drug-clearing ADAs appeared after 4–7 days, which affected the ability to accurately calculate PK parameters. Single species allometric scaling of PK data for Humira® in SCID and hFcRn SCID mice resulted in improved human PK predictions compared to C57BL/6 mice. Thus, the SCID mouse model was demonstrated to be a useful tool for assessing the preclinical PK of immunogenic therapeutics.     

TCR基因修饰淋巴细胞体内抗肿瘤作用的研究

建立荷人肝癌细胞BEL-7402的SCID小鼠模型,用脂质体介导进行基因转染,流式细胞术检测TCRVβ7.1基因表达,分别以尾静脉注射,肿瘤周围皮下注射以及腹腔注射三种方式给予荷瘤免疫缺陷小鼠(SCID鼠)转染TCRVβ7.1基因的人外周血淋巴细胞,24h后处死小鼠取各组织用免疫组化方法来检测淋巴细胞在小鼠体内的分布的情况.通过检测瘤重、肿瘤体积大小,并计算肿瘤抑制率,观察该基因对SCID荷瘤小鼠的抑瘤作用,为该基因用于肿瘤的临床治疗提供动物实验数据.     

Insect immune responses to nematode parasites

Host innate immunity plays a central role in detecting and eliminating microbial pathogenic infections in both vertebrate and invertebrate animals. Entomopathogenic or insect pathogenic nematodes are of particular importance for the control of insect pests and vectors of pathogens, while insect-borne nematodes cause serious diseases in humans. Recent work has begun to use the power of insect models to investigate host-nematode interactions and uncover host antiparasitic immune reactions. This review describes recent findings on innate immune evasion strategies of parasitic nematodes and host cellular and humoral responses to the infection. Such information can be used to model diseases caused by human parasitic nematodes and provide clues indicating directions for research into the interplay between vector insects and their invading tropical parasites.     

Immune system-dependent and -independent replication of the scrapie agent.

Using the severe combined immunodeficiency (SCID) mouse model, we investigated the requirement of the immune system for the development of scrapie after peripheral inoculation. A total of 33% of SCID mice, all but one immunologically reconstituted SCID mice (93%), and all CB17 control mice developed the disease. PrPres was detectable in the brains of all diseased animals and in the spleens of reconstituted SCID and CB17 control mice but not of the diseased non-immunologically reconstituted SCID mice. The immune system appears to be a primary target in the pathogenesis of scrapie, but direct spread to the central nervous system from the peritoneum via visceral nerve fibers can probably also occur.     

Human peripheral blood lymphocyte severe combined immunodeficiency (hu-PBL SCID) models of toxoplasmosis

Toxoplasmosis is a potentially fatal opportunistic infection of immunocompromised hosts. Improved animal models of toxoplasmosis are needed to more nearly approximate conditions that occur in immunocompromised humans. The development of models of toxoplasmosis using human peripheral blood lymphocytes (hu-PBL) transplanted into severe combined immunodeficiency (SCID) mice is described here. Transplantation of hu-PBL into SCID mice without prior conditioning of the mice resulted in detectable differences in quantitative histological scores of brain inflammation due to Toxoplasma gondii infection, but did not alter mortality when compared to SCID mouse controls. The lack of detectable differences in survival were due to inadequate engraftment of hu-PBL, as assessed by flow cytometry. Unconditioned hu-PBL SCID mice had low titre T. gondii-specific antibody detectable after infection. When pretransplantation conditioning with irradiation and antiasialo GM 1 (n-glucolyl neuraminic acid) antibody was used, prolonged hu-PBL engraftment was observed in SCID mice, which was associated with worsened histopathology and usually impaired survival when compared with SCID mouse controls. When pretransplantation conditioning with irradiation, antiasialo GM antibody and polyethylene glycol-conjugated IL-2 was used, prolonged hu-PBL engraftment was also documented, but this did not affect survival from T. gondii infection when compared with similarly conditioned SCID mouse controls. The latter conditioning protocol resulted in hu-PBL SCID mice producing high titre T. gondii-specific antibody after infection. Conditioned hu-PBL SCID mice had evidence of increased T. gondii-induced inflammatory scores when compared with conditioned SCID mice. These models show promise for the study of the pathogenesis of toxoplasmosis and conditioned hu-PBL SCID mice may have applications for the evaluation of novel therapies for toxoplasmosis in immunocompromised humans.     

Cardiac and vascular phenotypes in the apolipoprotein E-deficient mouse

Cardiovascular death is frequently associated with atherosclerosis, a chronic multifactorial disease and a leading cause of death worldwide. Genetically engineered mouse models have proven useful for the study of the mechanisms underlying cardiovascular diseases. The apolipoprotein E-deficient mouse has been the most widely used animal model of atherosclerosis because it rapidly develops severe hypercholesterolemia and spontaneous atherosclerotic lesions similar to those observed in humans. In this review, we provide an overview of the cardiac and vascular phenotypes and discuss the interplay among nitric oxide, reactive oxygen species, aging and diet in the impairment of cardiovascular function in this mouse model.     

Effect of phenolic acids of microbial origin on production of reactive oxygen species in mitochondria and neutrophils

Cardiovascular death is frequently associated with atherosclerosis, a chronic multifactorial disease and a leading cause of death worldwide. Genetically engineered mouse models have proven useful for the study of the mechanisms underlying cardiovascular diseases. The apolipoprotein E-deficient mouse has been the most widely used animal model of atherosclerosis because it rapidly develops severe hypercholesterolemia and spontaneous atherosclerotic lesions similar to those observed in humans. In this review, we provide an overview of the cardiac and vascular phenotypes and discuss the interplay among nitric oxide, reactive oxygen species, aging and diet in the impairment of cardiovascular function in this mouse model.     

SCID-hu小鼠：HIV研究的小型动物模型

长期以来缺乏病毒体内感染的小动物模型是制约HIV-1研究取得突破性进展的一大障碍。研究者将胎儿的胸腺和胎肝组织移植到重症联合免疫缺陷(SCID)小鼠体内,构建了SCID-hu(Thy／Liv)人鼠嵌合模型。该模型具备正常功能性的人造血器官“Thy／Liv”,较真实地模拟了HIV-1感染人胸腺后的状况,是研究HIV-1体内感染较成功且很有潜力的嵌合鼠模型。SCID-hu(Thy／Liv)模型的构建使得在小型动物体内研究HIV的某些致病机制、临床前评价各种先导药物的体内抗HIV活性、评价新的治疗方案及寻求合适的基因治疗等成为可能,为在体内研究人造血系统和免疫系统的病理生理机能及人干细胞基因治疗提供了有力的工具,有广泛的应用前景。     

Model of angiogenesis in mice with severe combined immunodeficiency (SCID) and xenoengrafted with Epstein-Barr virus-transformed B cells

Xenoengraftment of human cells in mice with severe combined immunodeficiency (SCID) has been used as a model system to study the mechanisms of B-cell lymphomagenesis. In the study reported here, we determined that SCID mice can also be used as a model to study angiogenesis in B-cell lymphomas. The C.B-17 scid/scid mice were xenotransplanted with Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL), and we determined whether CD31, a marker found on endothelial cells, was detected in the human B-cell lymphomas that developed in these mice. Microvessel formation was identified by use of immunohistochemical staining for CD31. To assess possible mechanisms of angiogenic stimulus, we analyzed the expression of interleukin 8 (IL-8), a chemokine documented to promote angiogenesis, in non-small-cell lung cancer and bronchogenic carcinomas. We observed that a panel of LCL and LCL-lymphomas expressed IL-8 mRNA and protein. Neutralization of IL-8, however, did not inhibit lymphomagenesis, suggesting that IL-8 is not essential for angiogenesis in this model. To examine other parameters of angiogenesis, we identified expression of vascular endothelial growth factor in the lymphomas. These data suggest that angiogenesis accompanies EBV-associated B-cell lymphoma development, but IL-8 is not essential for this process. Thus, the SCID mouse model is amenable to testing of anti-angiogenic factors.     

Cooperative effect of the attenuation determinants derived from poliovirus sabin 1 strain is essential for attenuation of enterovirus 71 in the NOD/SCID mouse infection model

Enterovirus 71 (EV71) is a causative agent of hand, foot, and mouth disease and is also associated with serious neurological disorders. An attenuated EV71 strain [EV71(S1-3′)] has been established in the cynomolgus monkey infection model; this strain contains the attenuation determinants derived from the type 1 poliovirus vaccine strain, Sabin 1 [PV1(Sabin)], in the 5′ nontranslated region (NTR), 3D polymerase, and 3′ NTR. In this study, we analyzed the effect of the attenuation determinants of PV1(Sabin) on EV71 infection in a NOD/SCID mouse infection model. We isolated a mouse-adapted EV71 strain [EV71(NOD/SCID)] that causes paralysis of the hind limbs in 3- to 4-week-old NOD/SCID mice by adaptation of the virulent EV71(Nagoya) strain in the brains of NOD/SCID mice. A single mutation at nucleotide 2876 that caused an amino acid change in capsid protein VP1 (change of the glycine at position 145 to glutamic acid) was essential for the mouse-adapted phenotype in NOD/SCID mice. Next, we introduced attenuation determinants derived from PV1(Sabin) along with the mouse adaptation mutation into the EV71(Nagoya) genome. In 4-week-old mice, the determinants in the 3D polymerase and 3′ NTR, which are the major temperature-sensitive determinants, had a strong effect on attenuation. In contrast, the effect of individual determinants was weak in 3-week-old NOD/SCID mice, and all the determinants were required for substantial attenuation. These results suggest that a cooperative effect of the attenuation determinants of PV1(Sabin) is essential for attenuated neurovirulence of EV71.     

Understanding hereditary diseases using the dog and human as companion model systems

Animal models are requisite for genetic dissection of, and improved treatment regimens for, human hereditary diseases. While several animals have been used in academic and industrial research, the primary model for dissection of hereditary diseases has been the many strains of the laboratory mouse. However, given its greater (than the mouse) genetic similarity to the human, high number of naturally occurring hereditary diseases, unique population structure, and the availability of the complete genome sequence, the purebred dog has emerged as a powerful model for study of diseases. The major advantage the dog provides is that it is afflicted with approximately 450 hereditary diseases, about half of which have remarkable clinical similarities to corresponding diseases of the human. In addition, humankind has a strong desire to cure diseases of the dog so these two facts make the dog an ideal clinical and genetic model. This review highlights several of these shared hereditary diseases. Specifically, the canine models discussed herein have played important roles in identification of causative genes and/or have been utilized in novel therapeutic approaches of interest to the dog and human.     

Adenosine deaminase activity in recipients of bone marrow from immunodeficient mice homozygous for the wasted mutation

Mice homozygous for the mutation wasted (wst/wst) have been postulated to be a model for the form of human severe combined immunodeficiency disease (SCID) that is secondary to a genetic deficiency of adenosine deaminase (ADA). To test this hypothesis more critically, we transplanted marrow from wst/wst and littermate control mice into lethally irradiated normal recipients. The Vmax and Km values for ADA in recipient's hematologic and non-hematologic tissues did not differ significantly. These results indicate that the wasted mouse is not a model for ADA deficiency and SCID.     

Growth of MCF-7 human breast carcinoma in severe combined immunodeficient mice: Growth suppression by recombinant interleukin-2 treatment and role of lymphokine-activated killer cells

Summary The severe combined immunodeficient (SCID) mouse, lacking functional T and B lymphocytes, has been considered by many groups to be a prime candidate for the reconstitution of a human immune system in a laboratory animal. In addition, this immuno-deficient animal would appear to have excellent potential as a host for transplanted human cancers, thus providing an exceptional opportunity for the study of interactions between the human immune system and human cancer in a laboratory animal. However, because this animal model is very recent, few studies have been reported documenting the capability of these mice to accept human cancers, and whether or not the residual immune cells in these mice (e.g. natural killer, NK, cells; macrophages) possess antitumor activities toward human cancers. Thus, the purpose of this study was (a) to determine whether or not a human breast carcinoma cell line (MCF-7) can be successfully transplanted to SCID mice, (b) to determine whether or not chronic treatment of SCID mice with a potent lymphokine (recombinant interleukin-2, rIL-2) could alter MCF-7 carcinoma growth, and (c) to assess whether or not rIL-2-activated NK cells (LAK cells) are important modulators of growth of MCF-7 cells in SCID mice. To fulfill these objectives, female SCID mice were implanted s.c. with MCF-7 cells (5 × 10⁶ cells/mouse) at 6 weeks of age. Six weeks later, some of the mice were injected i.p. twice weekly with rIL-2 (1 × 10⁴ U mouse^–1 injection^–1). Results clearly show that MCF-7 cells can grow progressively in SCID mice; 100% of the SCID mice implanted with MCF-7 cells developed palpable measurable tumors within 5–6 weeks after tumor cell inoculation. In addition, MCF-7 tumor growth was significantly (P <0.01) suppressed by rIL-2 treatment. rIL-2 treatment was non-toxic and no effect of treatment on body weight gains was observed. For non-tumor-bearing SCID mice, splenocytes treated in vitro with rIL-2 (lymphokine-activated killer, LAK, cells) or splenocytes derived from rIL-2-treated SCID mice (LAK cells) had significant (P <0.01) cytolytic activity toward MCF-7 carcinoma cells in vitro. In contrast, splenocytes (LAK cells) derived from tumor(MCF-7)-bearing rIL-2-treated SCID mice lacked cytolytic activities toward MCF-7 cells in vitro. No significant concentration of LAK cells in MCF-7 human breast carcinomas was observed nor did rIL-2 treatment significantly alter growth of MCF-7 cells in vitro. Thus, while rIL-2 treatment significantly suppressed growth of MCF-7 breast carcinomas in SCID mice, the mechanism of this growth suppression, albeit clearly not involving T and B lymphocytes, does not appear to be mediated via a direct cytolytic activity of LAK cells toward the carcinoma cells. However, rIL-2-activated SCID mouse splenocytes (LAK cells) do possess the capability of significant cytolytic activity toward MCF-7 human breast carcinoma cells. Thus, treatment of SCID mice with a potent lymphokine (rIL-2) induces a significant antitumor host response, a response that does not involve T and B lymphocytes and appears not to involve NK/LAK cells. This host response must be considered in future studies designed to investigate the interactions of reconstituted human immune systems and human cancers within this highly promising immuno deficient experimental animal model.