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The number of humanized mouse models for the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) and other infectious diseases has expanded rapidly over the past 8 years. Highly immunodeficient mouse strains, such as NOD/SCID/gamma chain(null) (NSG, NOG), support better human hematopoietic cell engraftment. Another improvement is the derivation of highly immunodeficient mice, transgenic with human leukocyte antigens (HLAs) and cytokines that supported development of HLA-restricted human T cells and heightened human myeloid cell engraftment. Humanized mice are also used to study the HIV reservoir using new imaging techniques. Despite these advances, there are still limitations in HIV immune responses and deficits in lymphoid structures in these models in addition to xenogeneic graft-versus-host responses. To understand and disseminate the improvements and limitations of humanized mouse models to the scientific community, the NIH sponsored and convened a meeting on April 15, 2015 to discuss the state of knowledge concerning these questions and best practices for selecting a humanized mouse model for a particular scientific investigation. This report summarizes the findings of the NIH meeting.

Weak electric fields guide cell migration, known as galvanotaxis/electrotaxis. The sensor(s) cells use to detect the fields remain elusive. Here we perform a large-scale screen using an RNAi library targeting ion transporters in human cells. We identify 18 genes that show either defective or increased galvanotaxis after knockdown. Knockdown of the KCNJ15 gene (encoding inwardly rectifying K(+) channel Kir4.2) specifically abolishes galvanotaxis, without affecting basal motility and directional migration in a monolayer scratch assay. Depletion of cytoplasmic polyamines, highly positively charged small molecules that regulate Kir4.2 function, completely inhibits galvanotaxis, whereas increase of intracellular polyamines enhances galvanotaxis in a Kir4.2-dependent manner. Expression of a polyamine-binding defective mutant of KCNJ15 significantly decreases galvanotaxis. Knockdown or inhibition of KCNJ15 prevents phosphatidylinositol 3,4,5-triphosphate (PIP3) from distributing to the leading edge. Taken together these data suggest a previously unknown two-molecule sensing mechanism in which KCNJ15/Kir4.2 couples with polyamines in sensing weak electric fields.

Understanding the peopling of the Americas remains an important and challenging question. Here, we present (14)C dates, and morphological, isotopic and genomic sequence data from two human skulls from the state of Minas Gerais, Brazil, part of one of the indigenous groups known as 'Botocudos'. We find that their genomic ancestry is Polynesian, with no detectable Native American component. Radiocarbon analysis of the skulls shows that the individuals had died prior to the beginning of the 19th century. Our findings could either represent genomic evidence of Polynesians reaching South America during their Pacific expansion, or European-mediated transport.

DNA molecules are continuously released through decomposition of organic matter and are ubiquitous in most environments. Such DNA becomes fragmented and damaged (often

Resident microbiota activates regulatory cells that modulate intestinal inflammation and promote and maintain intestinal homeostasis. IL-10 is a key mediator of immune regulatory function. Our studies describe the functional importance and mechanisms by which gut microbiota and specific microbial components influence the development of intestinal IL10-producing B cells. Using fecal transplant into germ-free (GF) [Il10.sup.+/EGFP] reporter and [Il10.sup.-/-] mice, we demonstrated that microbiota from specific pathogen-free mice primarily stimulated IL-10-producing colon-specific B cells and T regulatory 1 cells in ex-GF mice. IL-10 in turn downregulated microbiota-activated mucosal inflammatory cytokines. TLR2 and -9 ligands and enteric bacterial lysates preferentially induced IL-10 production and the regulatory capacity of intestinal B cells. Analysis of [IL10.sup.+/EGFP] mice crossed with additional gene-deficient strains and B cell cotransfer studies demonstrated that microbiota-induced IL-10-producing intestinal B cells ameliorated chronic T cell-mediated colitis in a TLR2-, MyD88-, and PI3K-dependent fashion. In vitro studies implicated downstream signaling of PI3Kp110[delta] and AKT. These studies demonstrated that resident enteric bacteria activated intestinal IL-10-producing B cells through TLR2, MyD88, and PI3K pathways. These B cells reduced colonic T cell activation and maintained mucosal homeostasis in response to intestinal microbiota., Introduction Inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, are T cell-mediated, chronic disorders whose development is influenced in part by dysregulated, aggressive intestinal mucosal immune reactions to [...]

Seizure-induced hilar basal dendrites on dentate granule cells are observed in several rodent models of temporal lobe epilepsy. Ultrastructural evidence showed that basal dendrites receive predominantly excitatory synapses, including many from mossy fibers. Such highly interconnected granule cells with basal dendrites are suggested to enhance hyperexcitability within the dentate network. For an expanded treatment of this topic see Jasper's Basic Mechanisms of the Epilepsies, Fourth Edition (Noebels JL, Avoli M, Rogawski MA, Olsen RW, Delgado-Escueta AV, eds) published by Oxford University Press (available on the National Library of Medicine Bookshelf [NCBI] at). © 2010 International League Against Epilepsy.

Lifelong treatment is required for people living with HIV as current antiretroviral therapy (ART) does not eradicate HIV infection. Latently infected cells are essentially indistinguishable from uninfected cells and cannot be depleted by currently available approaches. This study evaluated antibody mediated transient CD4+ T cell depletion as a strategy to reduce the latent HIV reservoir. Anti-CD4 antibodies effectively depleted CD4+ T cells in the peripheral blood and tissues of humanized mice. We then demonstrate that antibody-mediated CD4+ T cell depletion of HIV infected ART-suppressed animals results in substantial reductions in cell-associated viral RNA and DNA levels in peripheral blood cells over the course of anti-CD4 antibody treatment. Recovery of CD4+ T cells was observed in all tissues analyzed except for the lung 26 days after cessation of antibody treatment. After CD4+ T cell recovery, significantly lower levels of cell-associated viral RNA and DNA were detected in the tissues of anti-CD4 antibody-treated animals. Further, an 8.5-fold reduction in the levels of intact HIV proviral DNA and a 3.1-fold reduction in the number of latently infected cells were observed in anti-CD4-antibody-treated animals compared with controls. However, there was no delay in viral rebound when ART was discontinued in anti-CD4 antibody-treated animals following CD4+ T cell recovery compared with controls. Our results suggest that transient CD4+ T cell depletion, a long-standing clinical intervention that might have an acceptable safety profile, during suppressive ART can reduce the size of the HIV reservoir in humanized mice. Author summary: Current long-term antiretroviral therapy does not eradicate cells latently infected with HIV. Latently HIV-infected cells are essentially indistinguishable from uninfected cells and cannot be easily targeted by currently available strategies. CD4+ T cells represent the most well-characterized and largest HIV reservoir. Anti-CD4 antibody mediated CD4+ T cells depletion has been proved to be reversible and well-tolerated in humans. In this study, we evaluated the effect of transient depletion of human CD4+ T cells with an anti-CD4 antibody on the size of the HIV reservoir in HIV-infected ART-suppressed humanized mice. CD4+ T cells in the peripheral blood and tissues of humanized mice were effectively depleted. Importantly, the size of the HIV reservoir was significantly decreased in anti-CD4 antibody treated animals following CD4+ T cell recovery compared with untreated controls. [ABSTRACT FROM AUTHOR]

The human brain is an important site of HIV replication and persistence during antiretroviral therapy (ART). Direct evaluation of HIV infection in the brains of otherwise healthy individuals is not feasible; therefore, we performed a large-scale study of bone marrow/liver/thymus (BLT) humanized mice as an in vivo model to study HIV infection in the brain. Human immune cells, including [CD4.sup.+] T cells and macrophages, were present throughout the BLT mouse brain. HIV DNA, HIV RNA, and/or [p24.sup.+] cells were observed in the brains of HIV-infected animals, regardless of the HIV isolate used. HIV infection resulted in decreased numbers of [CD4.sup.+] T cells, increased numbers of [CD8.sup.+] T cells, and a decreased [CD4.sup.+]/[CD8.sup.+]T cell ratio in the brain. Using humanized T cell-only mice (ToM), we demonstrated that T cells establish and maintain HIV infection of the brain in the complete absence of human myeloid cells. HIV infection of ToM resulted in [CD4.sup.+] T cell depletion and a reduced [CD4.sup.+]/[CD8.sup.+] T cell ratio. ART significantly reduced HIV levels in the BLT mouse brain, and the immune cell populations present were indistinguishable from those of uninfected controls, which demonstrated the effectiveness of ART in controlling HIV replication in the CNS and returning cellular homeostasis to a pre-HIV state., Introduction The advent and widespread use of effective antiretroviral therapy (ART) to treat HIV infection has dramatically curtailed the severity of the neurocognitive impairment previously observed in HIV-infected patients (1). [...]