Development of humanized mouse models to study human malaria parasite infection

Malaria is a disease caused by infection with Plasmodium parasites that are transmitted by mosquito bite. Five different species of Plasmodium infect humans with severe disease, but human malaria is primarily caused by Plasmodium falciparum. The burden of malaria on the developing world is enormous, and a fully protective vaccine is still elusive. One of the biggest challenges in the quest for the development of new antimalarial drugs and vaccines is the lack of accessible animal models to study P. falciparum infection because the parasite is restricted to the great apes and human hosts. Here, we review the current state of research in this field and provide an outlook of the development of humanized small animal models to study P. falciparum infection that will accelerate fundamental research into human parasite biology and could accelerate drug and vaccine design in the future.     

Detection, eradication, and research implications of Helicobacter infections in laboratory rodents

Researchers first isolated and characterized Helicobacter hepaticus in 1994 as a cause of hepatitis that progressed to hepatocellular carcinoma in A/JCr mice. During the past decade, isolation and characterization of additional novel helicobacters from rodents has continued. In addition to causing overt disease, rodent helicobacter infections are important because intercurrent disease in select models will confound research data. Emerging evidence suggests that inflammatory responses to enterohepatic helicobacter infections may alter host responses to other experimental stimuli in unanticipated ways. Additionally, scientists have experimentally infected a variety of inbred mouse strains and genetically engineered mice with a variety of Helicobacter spp. isolated from rodents, birds, and higher mammals (including humans) to develop animal models of gastrointestinal diseases as well as idiopathic human disease syndromes. This review highlights current information about helicobacter infections in laboratory rodents and provides recommendations for the detection and eradication of these infections. The authors discuss the impact of subclinical and clinical disease and offer recommendations for managing helicobacter-free rodent colonies.     

Plasmodium: experimental animals for human malaria and research needs. A review.

The literature on experimental animals for human malaria has been selectively reviewed. Criteria for the selection of host animals and the experimental approaches for establishing malarial infections in them are discussed and analyzed on the bases of previous work. It is suggested that the research experiments of other countries, where feasible and applicable, should be adopted in attempts to establish animal models for human malaria indigenous to the People's Republic of China.     

Malaria modeling: In vitro stem cells vs in vivo models

The recent development of stem cell research and the possibility of generating cells that can be stably and permanently modified in their genome open a broad horizon in the world of in vitro modeling. The malaria field is gaining new opportunities from this importantbreakthrough and novel tools were adapted and opened new frontiers for malaria research. In addition to the new in vitro systems, in recent years there were also significant advances in the development of new animal models that allows studying the entire cell cycle of human malaria. In this paper, we review the different protocols available to study human Plasmodium species either by using stem cell or alternative animal models.     

Pregnancy outcome and placenta pathology in Plasmodium berghei ANKA infected mice reproduce the pathogenesis of severe malaria in pregnant women

Pregnancy-associated malaria (PAM) is expressed in a range of clinical complications that include increased disease severity in pregnant women, decreased fetal viability, intra-uterine growth retardation, low birth weight and infant mortality. The physiopathology of malaria in pregnancy is difficult to scrutinize and attempts were made in the past to use animal models for pregnancy malaria studies. Here, we describe a comprehensive mouse experimental model that recapitulates many of the pathological and clinical features typical of human severe malaria in pregnancy. We used P. berghei ANKA-GFP infection during pregnancy to evoke a prominent inflammatory response in the placenta that entails CD11b mononuclear infiltration, up-regulation of MIP-1 alpha chemokine and is associated with marked reduction of placental vascular spaces. Placenta pathology was associated with decreased fetal viability, intra-uterine growth retardation, gross post-natal growth impairment and increased disease severity in pregnant females. Moreover, we provide evidence that CSA and HA, known to mediate P. falciparum adhesion to human placenta, are also involved in mouse placental malaria infection. We propose that reduction of maternal blood flow in the placenta is a key pathogenic factor in murine pregnancy malaria and we hypothesize that exacerbated innate inflammatory responses to Plasmodium infected red blood cells trigger severe placenta pathology. This experimental model provides an opportunity to identify cell and molecular components of severe PAM pathogenesis and to investigate the inflammatory response that leads to the observed fetal and placental blood circulation abnormalities.     

糖尿病肾病动物模型的研究进展

糖尿病肾病是终末期肾衰的主要原因,也是糖尿病致命的重要原因。但是糖尿病肾病的致病机制迄今尚不完全明了,理想的动物模型无疑可对糖尿病肾病的研究提供重要线索。糖尿病肾病动物模型包括诱发性、自发性和转基因等多种类型的动物模型,各种类型的动物模型在疾病的发生发展、病理生理变化等多个方面与人类糖尿病肾病具有相似的特征。应用这些模型有助于开展对糖尿病肾病的防治、发病机理、相关药物的开发等多方面的研究。     

Use of Transgenic Systems to Investigate Oligodendrocyte Differentiation and Function

Transgenic techniques are generating new strains of animals that are of great importance for many neurological research projects. This includes new animal models of human diseases that should allow analysis of disease etiology and treatment. The insertion of new genetic material into the mouse genome enables the investigator to study the effects of overexpression of normal or mutated genes under a variety of experimental conditions. The use of cell-specific and/or developmentally regulated promoters permits studies on the expression of the specific DNA in selected cells within the nervous system at important developmental stages. This article focuses on the techniques for generating transgenic mice, noting specific advantages or problems that should be considered when designing a transgenic project. The use of reporter genes such as the LacZ gene is discussed, using the particular example of the myelin proteolipid protein promoter directing expression of the LacZ gene in differentiating oligodendrocytes.     

The importance of human FcgammaRI in mediating protection to malaria

The success of passive immunization suggests that antibody-based therapies will be effective at controlling malaria. We describe the development of fully human antibodies specific for Plasmodium falciparum by antibody repertoire cloning from phage display libraries generated from immune Gambian adults. Although these novel reagents bind with strong affinity to malaria parasites, it remains unclear if in vitro assays are predictive of functional immunity in humans, due to the lack of suitable animal models permissive for P. falciparum. A potentially useful solution described herein allows the antimalarial efficacy of human antibodies to be determined using rodent malaria parasites transgenic for P. falciparum antigens in mice also transgenic for human Fc-receptors. These human IgG1s cured animals of an otherwise lethal malaria infection, and protection was crucially dependent on human FcgammaRI. This important finding documents the capacity of FcgammaRI to mediate potent antimalaria immunity and supports the development of FcgammaRI-directed therapy for human malaria.     

Laboratory models for research in vivo and in vitro on malaria parasites of mammals: Current status

In research aimed at developing strategies for the eradication of human malaria, various species of rodent, avian and non-human primate plasmodia are used as laboratory models. Here Barend Mons and Robert Sinden attempt to summarize the most common laboratory models for mammalian malaria, and to shed some light on their applicability to different aspects of malaria research.     

Non-invasive measurement of brain damage in a primate model of multiple sclerosis

Early recognition of whether a product has potential as a new therapy for treating multiple sclerosis (MS) relies upon the quality of the animal models used in the preclinical trials. The promising effects of new treatments in rodent models of experimental autoimmune encephalomyelitis (EAE) have rarely been reproduced in patients suffering from MS. EAE in outbred marmoset monkeys, Callithrix jacchus, is a valid new model, and might provide an experimental link between EAE in rodent models and human MS. Using magnetic resonance imaging techniques similar to those used in patients suffering from MS pathological abnormalities in the brain, white matter of the animal can be visualized and quantified. Moreover, NMR spectroscopy, in combination with pattern recognition, offers an advanced uroscopic technique for the identification of biomarkers of inflammatory demyelination.     

基因编辑动物模型在人类疾病研究中的应用

近年来,随着以CRISPR/Cas9为代表的多种CRISPR系统的开发和不断改进,基因编辑技术逐渐完善,并广泛应用于人类疾病动物模型的制备。基因编辑动物模型为人类疾病的发病机理、病理过程以及预防和治疗等方面的研究提供了重要的素材。目前,用于人类疾病研究的基因编辑动物模型主要有小鼠、大鼠为代表的啮齿类动物模型和以猪为代表的大动物模型。其中啮齿类动物在机体各方面与人类差别较大,且寿命短,无法对人类疾病的研究和治疗提供有效评估和长期追踪;而猪在生理学、解剖学、营养学和遗传学等各方面与人类更接近,是器官移植和人类疾病研究领域重要的动物模型。文中主要介绍了基因编辑动物模型在神经退行性疾病、肥厚心肌病、癌症、免疫缺陷类疾病和代谢性疾病等5种人类疾病研究中的应用情况,以期为人类疾病研究及相关动物模型的制备提供参考。     

Malaria research in the post-genomic era

Genomic sequence determination of Plasmodium falciparum and other species of the genus, as well as that of Anopheles gambiae, and human, rat and mouse genome sequencing have completely changed the landscape of fundamental research about malaria. These data should urgently be exploited, in order to develop new tools to combat the disease: new drugs, fine dissection of the cascade of events following infection of the various vector species and vertebrate host, analysis of the complex interaction leading to the pathology or, inversely, contributing to sustained protection. Powerful population biology tools are now available, allowing to investigate genetic exchanges within natural population and to identify factors structuring parasitic and vector populations. Nevertheless, important impediments persist, including the complexity of experimental systems and the unclear relevance of animals models. Numerous challenges are to be faced; they call upon a more efficient organisation of research efforts in the systematic explorations using the powerful novel post-genomic technologies, as well as the development of new tools and experimental models required by functional genomics and integrative biology.     

The origins,isolation, and biological characterization of rodent malaria parasites

Rodent malaria parasites have been widely used in all aspects of malaria research to study parasite development within rodent and insect hosts, drug resistance, disease pathogenesis, host immune response, and vaccine efficacy. Rodent malaria parasites were isolated from African thicket rats and initially characterized by scientists at the University of Edinburgh, UK, particularly by Drs. Richard Carter, David Walliker, and colleagues. Through their efforts and elegant work, many rodent malaria parasite species, subspecies, and strains are now available. Because of the ease of maintaining these parasites in laboratory mice, genetic crosses can be performed to map the parasite and host genes contributing to parasite growth and disease severity. Recombinant DNA technologies are now available to manipulate the parasite genomes and to study gene functions efficiently. In this chapter, we provide a brief history of the isolation and species identification of rodent malaria parasites. We also discuss some recent studies to further characterize the different developing stages of the parasites including parasite genomes and chromosomes. Although there are differences between rodent and human malaria parasite infections, the knowledge gained from studies of rodent malaria parasites has contributed greatly to our understanding of and the fight against human malaria.     

Sequestration and Tissue Accumulation of Human Malaria Parasites: Can We Learn Anything from Rodent Models of Malaria?

The sequestration of Plasmodium falciparum-infected red blood cells (irbcs) in the microvasculature of organs is associated with severe disease; correspondingly, the molecular basis of irbc adherence is an active area of study. In contrast to P. falciparum, much less is known about sequestration in other Plasmodium parasites, including those species that are used as models to study severe malaria. Here, we review the cytoadherence properties of irbcs of the rodent parasite Plasmodium berghei ANKA, where schizonts demonstrate a clear sequestration phenotype. Real-time in vivo imaging of transgenic P. berghei parasites in rodents has revealed a CD36-dependent sequestration in lungs and adipose tissue. In the absence of direct orthologs of the P. falciparum proteins that mediate binding to human CD36, the P. berghei proteins and/or mechanisms of rodent CD36 binding are as yet unknown. In addition to CD36-dependent schizont sequestration, irbcs accumulate during severe disease in different tissues, including the brain. The role of sequestration is discussed in the context of disease as are the general (dis)similarities of P. berghei and P. falciparum sequestration.     

FDG-PET imaging, EEG and sleep phenotypes as translational biomarkers for research in Alzheimer's disease

The lack of reliable translational procedures applicable to both patients and experimental models are a major obstacle for the advancement of basic research as well as for the development of therapeutics. This is particularly relevant to neurodegenerative disorders such as AD (Alzheimer's disease), where the predictive validity of animal models and procedures applied preclinically have met with little success. Two approaches available for human diagnostics are currently experiencing major advancements in preclinical research: in vivo imaging using MRI (magnetic resonance imaging) or PET (positron-emission tomography) and recordings of brain electrical activity via surface EEG (electroencephalogram). The present paper reviews the results obtained so far in rodent AD models, and summarizes advantages and disadvantages of such procedures.     

Quantitative isolation and in vivo imaging of malaria parasite liver stages

The liver stages of Plasmodium, the causative agent of malaria, are the least explored forms in the parasite's life cycle despite their recognition as key vaccine and drug targets. In vivo experimental access to liver stages of human malaria parasites is practically prohibited and therefore rodent model malaria parasites have been used for in vivo studies. However, even in rodent models progress in the analysis of liver stages has been limited, mainly due to their low abundance and associated difficulties in visualisation and isolation. Here, we present green fluorescent protein (GFP)-tagged Plasmodium yoelii rodent malaria parasite liver infections in BALB/c mice as an excellent quantitative model for the live visualisation and isolation of the so far elusive liver stages. We believe P. yoelii GFP-tagged liver stages allow, for the first time, the efficient quantitative isolation of intact early and late liver stage-infected hepatocyte units by fluorescence activated cell sorting. GFP-tagged liver stages are also well suited for intravital imaging, allowing us for the first time to visualise them in real time. We identify previously unrecognised features of liver stages including vigorous parasite movement and expulsion of 'extrusomes'. Intravital imaging thus reveals new, important information on the malaria parasite's transition from tissue to blood stage.     

Genetics of host response to malaria.

A comprehension of the genetics of host resistance to malaria is essential to understanding the complex host/parasite interaction. Current research is directed towards the genetic dissection of both the murine and human host responses to the disease. Significant progress has been made towards the mapping of novel murine resistance loci. In addition, the role of the major histocompatibility complex in the host response has been examined in both animal models and human populations. Several large segregation analyses, association studies and, more recently, linkage analyses have been conducted in different African populations to examine the role of host genetics in both mild and severe malaria. The results of these studies have been collated within this review. The cloning of genes involved in malarial resistance will lead not only to a greater understanding of this complex disease but, potentially, to the development of effective medical intervention.     

SysFinder:A customized platform for search,comparison and assisted design of appropriate animal models based on systematic similarity

Animal models are increasingly gaining values by cross-comparisons of response or resistance to clinical agents used for patients.However,many disease mechanisms and drug effects generated from animal models are not transferable to human.To address these issues,we developed SysFinder(http://lifecenter.sgst.cn/SysFinder),a platform for scientists to find appropriate animal models for translational research.SysFinder offers a "topic-centered" approach for systematic comparisons of human genes,whose functions are involved in a specific scientific topic,to the corresponding homologous genes of animal models.Scientific topic can be a certain disease,drug,gene function or biological pathway.SysFinder calculates multi-level similarity indexes to evaluate the similarities between human and animal models in specified scientific topics.Meanwhile,SysFinder offers species-specific information to investigate the differences in molecular mechanisms between humans and animal models.Furthermore,SysFinder provides a userfriendly platform for determination of short guide RNAs(sgRNAs) and homology arms to design a new animal model.Case studies illustrate the ability of SysFinder in helping experimental scientists.SysFinder is a useful platform for experimental scientists to carry out their research in the human molecular mechanisms.     

运用系统论原理复制人类疾病动物模型

依据系统论的基本原理,人类疾病动物模型采用整体设计,统筹考虑模型与实验动物生物学特性方面的相似性、模型复制的重复性、可靠性、适用性、可控性、易行性和经济性等,以便模型复制的顺利开展。整体性原则应贯穿整个模型复制过程,使复制的模型具有科学性和实用性。模型复制要落实系统论的相关性原则,一个模型不是孤立的,动物的各系统、各器官、各分子之间是相互联系,人类和动物在生物学、解剖学、组织学、胚胎学、生理学、病理学等方面的相互联系,疾病的发生、发展是相互联系的,相关性原则为动物模型研究人类疾病提供了理论依据。动物模型在时间和空间上处于不断运动变化发展之中,在研究模型的过程中,要用动态的方法而不是静止的方法来研究动物模型,应根据疾病的特点,分成不同的阶段,结合动物的免疫功能、营养状况、疾病的发展、转归等采用不同的对策。模型的复制采用最优化原则,要求模型设计最优化,选用高质量的实验动物,减少动物使用数量,保护动物福利与伦理,最终实现模型评价体系的最优化。     

Animal models of human respiratory syncytial virus disease

Infection with the human pneumovirus pathogen, respiratory syncytial virus (hRSV), causes a wide spectrum of respiratory disease, notably among infants and the elderly. Laboratory animal studies permit detailed experimental modeling of hRSV disease and are therefore indispensable in the search for novel therapies and preventative strategies. Present animal models include several target species for hRSV, including chimpanzees, cattle, sheep, cotton rats, and mice, as well as alternative animal pneumovirus models, such as bovine RSV and pneumonia virus of mice. These diverse animal models reproduce different features of hRSV disease, and their utilization should therefore be based on the scientific hypothesis under investigation. The purpose of this review is to summarize the strengths and limitations of each of these animal models. Our intent is to provide a resource for investigators and an impetus for future research.