A Humanized Mouse Model of Tuberculosis

Citation: Calderon VE, Valbuena G, Goez Y, Judy BM, Huante MB, et al. ( A Humanized Mouse Model of Tuberculosis Veronica E. Calderon 0 Gustavo Valbuena 0 Yenny Goez 0 Barbara M. Judy 0 Matthew B. Huante 0 Putri Sutjita 0 R. Katie Johnston 0 D. Mark Estes 0 Robert L. Hunter 0 Jeffrey K. Actor 0 Jeffrey D. Cirillo 0 Janice J. Endsley 0 Pere-Joan Cardona, Fundacio Institut d'Investigacio en Cie`ncies de la Salut Germans Trias i Pujol. Universitat Auto` noma de Barcelona. CIBERES, Spain 0 1 Department of Pathology, University of Texas Medical Branch (UTMB), Galveston, Texas, United States of America, 2 Department of Microbiology and Immunology, University of Texas Medical Branch (UTMB), Galveston, Texas, United States of America, 3 University of Georgia , Athens , Georgia , United States of America, 4 University of Texas-Houston Health Science Center, Department of Pathology, Houston, Texas, United States of America, 5 Texas A&M Health Sciences Center, Department of Microbial and Molecular Pathogenesis, College Station , Texas , United States of America Mycobacterium tuberculosis (M.tb) is the second leading infectious cause of death worldwide and the primary cause of death in people living with HIV/AIDS. There are several excellent animal models employed to study tuberculosis (TB), but many have limitations for reproducing human pathology and none are amenable to the direct study of HIV/M.tb co-infection. The humanized mouse has been increasingly employed to explore HIV infection and other pathogens where animal models are limiting. Our goal was to develop a small animal model of M.tb infection using the bone marrow, liver, thymus (BLT) humanized mouse. NOD-SCID/ccnull mice were engrafted with human fetal liver and thymus tissue, and supplemented with CD34+ fetal liver cells. Excellent reconstitution, as measured by expression of the human CD45 pan leukocyte marker by peripheral blood populations, was observed at 12 weeks after engraftment. Human T cells (CD3, CD4, CD8), as well as natural killer cells and monocyte/macrophages were all observed within the human leukocyte (CD45+) population. Importantly, human T cells were functionally competent as determined by proliferative capacity and effector molecule (e.g. IFN-c, granulysin, perforin) expression in response to positive stimuli. Animals infected intranasally with M.tb had progressive bacterial infection in the lung and dissemination to spleen and liver from 2-8 weeks post infection. Sites of infection in the lung were characterized by the formation of organized granulomatous lesions, caseous necrosis, bronchial obstruction, and crystallization of cholesterol deposits. Human T cells were distributed throughout the lung, liver, and spleen at sites of inflammation and bacterial growth and were organized to the periphery of granulomas. These preliminary results demonstrate the potential to use the humanized mouse as a model of experimental TB. - Funding: This work was supported by National Institutes of Health/National Institute of Allergy and Infectious Diseases (NIH/NIAID) (R21AI089362), the Department of Microbiology and Immunology, and the Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas. V. Calderon was supported by a pre-doctoral fellowship from the McLaughlin Endowment Fund, University of Texas Medical Branch, Galveston, Texas. M. Huante was supported by an NIH/NIAID Biodefense Training Program T32 fellowship (AI060549). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Tuberculosis, caused by M.tb, is a major global health threat. Approximately 2 billion people (one-third of the worlds population) are estimated to be latently infected and nearly 9 million people became newly infected in 2011 [1]. M.tb is the second leading infectious cause of death worldwide and the leading cause of death in people with HIV/AIDS [1]. Of great concern is the growing incidence of multi- and extensively drug resistant isolates of M.tb associated with case mismanagement and immune compromise due to HIV infection [13]. There is thus an urgent need to develop and test new vaccines and drug compounds to prevent and treat TB. Towards this end, development of additional animal models to complement existing models and allow new avenues of discovery is needed. Several excellent animal models are available to study M.tb infection, including mice, guinea pigs, rabbits, cattle, and nonhuman primates (NHP) [49]. Mice are the most widely used model because they are easy to use, inexpensive, and reagents are readily available. An important limitation of this model, though, is the lack of granuloma formation similar to human infection [6,9 11]. The NHP, rabbit, and guinea pigs develop necrotic lesions similar to human TB disease [12]. Immunological reagents are limiting for the rabbit, guinea pig, and cow, however; and, like the mouse, these models are not amenable to the study of HIV/M.tb co-infection. A broad spectrum of TB disease states can develop in the NHP, and co-infection can be simulated using simian immunodeficiency virus (SIV) and M.tb [5,13,14]. Infection with SIV reproduces many clinical features of HIV and SIV/M.tb co-infection promotes aggressive TB disease and reactivation in latency models [1315]. The significant cost (animals, housing, personnel) as well as regulatory issues limit the use of the NHP co-infection model on broader scale. Further, there are significant differences between SIV and HIV including genetic heterogeneity and receptor usage for host cell entry [16]. Thus, there is a need for a small animal model that is: less expensive, available in larger numbers, does not require specialized facilities and staff, can take advantage of the availability of human reagents, and can be infected with HIV as compared to SIV. The development of the humanized BLT mice has recently opened new avenues of study for important human diseases. Several studies have demonstrated the potential to utilize this model to study HIV virus [1720] and a few other pathogens where host tropism limits use of other animal models [2123]. Currently, the humanized BLT mouse has not been developed for M.tb infection and there is no small animal model to study coinfections, such as HIV/M.tb. Such a model is urgently needed to improve our understanding of the human immune response to M.tb, advance our knowledge of HIV/M.tb co-infection pathobiology, inform vaccine development, and guide drug development to reduce side effects and drug interactions. Our studies demonstrate that the humanized BLT mouse develops TB and displays pathology similar to that observed in infected humans. We show here that humanized mice were successfully reconstituted with human leukocytes (including T cells, macrophages, natural killer cells, and antigen presenting cel (...truncated)