Electron tomography of HIV-1 infection in gut-associated lymphoid tissue

Abstract Critical aspects of HIV-1 infection occur in mucosal tissues, particularly in the gut, which contains large numbers of HIV-1 target cells that are depleted early in infection. We used electron tomography (ET) to image HIV-1 in gut-associated lymphoid tissue (GALT) of HIV-1-infected humanized mice, the first three-dimensional ultrastructural examination of HIV-1 infection in vivo. Human immune cells were successfully engrafted in the mice, and following infection with HIV-1, human T cells were reduced in GALT. Virions were found by ET at all stages of egress, including budding immature virions and free mature and immature viruses. Immuno-electron microscopy verified the virions were HIV-1 and showed CD4 sequestration in the endoplasmic reticulum of infected cells. Observation of HIV-1 in infected GALT tissue revealed that most HIV-1-infected cells, identified by immunolabeling and/or the presence of budding virions, were localized to intestinal crypts with pools of free virions concentrated in spaces between cells. Fewer infected cells were found in mucosal regions and the lamina propria. The preservation quality of reconstructed tissue volumes allowed details of budding virions, including structures interpreted as host-encoded scission machinery, to be resolved. Although HIV-1 virions released from infected cultured cells have been described as exclusively mature, we found pools of both immature and mature free virions within infected tissue. The pools could be classified as containing either mostly mature or mostly immature particles, and analyses of their proximities to the cell of origin supported a model of semi-synchronous waves of virion release. In addition to HIV-1 transmission by pools of free virus, we found evidence of transmission via virological synapses. Three-dimensional EM imaging of an active infection within tissue revealed important differences between cultured cell and tissue infection models and furthered the ultrastructural understanding of HIV-1 transmission within lymphoid tissue

Neutralizing anti-HIV antibodies develop in a humanized

From AIDS Vaccine 2012, Boston, MA, USA. 9-12 September 2012.Background: In BLT (bone marrow-liver-thymus) humanized mice, human thymocytes are educated by autologous human thymic tissue, resulting in functional human T cells capable of rapidly selecting for CTL escape mutations in HIV. In contrast, limitations to B cell maturation have been noted. But despite this, we show for the first time that HIV infected BLT mice can produce class-switched anti-HIV antibodies with neutralizing activities. Methods: Humanized BLT mice were generated by transplanting irradiated NOD-scid/IL2rgnull (NSG) mice with fetal thymus and liver fragments and then injecting them with autologous human CD34+ stem cells. BLT mice were then infected with HIVJRCSF and bled at various time-points. HIV neutralizing activity was measured using Tat-induced luciferase reporter TZM-bl cells. Results: Human transitional B cells were present in greater frequencies in BLT mice than adult humans. Most of these cells had a T1 phenotype in the blood and spleen. But despite this B cell maturation defect, class-switched IgG Abs against various HIV proteins were detected by Western Blot in HIV-infected BLT mice. Using ELISA to determine anti-p24 IgG Ab titers, Abs were present as early as 8 weeks post infection (p.i.), with peak Ab titers seen after 15 weeks. One infected mouse demonstrated a peak titer similar to that seen in a chronically infected human. Finally, plasma samples from infected BLT mice after 22 weeks p.i. demonstrated neutralizing activities against the challenge virus. Average IC50 neutralizing titers in these mice were similar to those from infected human samples. Conclusion: The ability of humanized BLT mice to generate functional humoral immune responses may be further improved by strategies to improve their B cell maturation, which will further improve the potential of these mice to become a model system to study candidate HIV vaccines and therapies

Dog‐assisted interventions and outcomes for older adults in residential long‐term care facilities: a systematic review and meta‐analysis

Objective To comprehensively review studies on dog‐assisted interventions (DAIs) among older people in residential long‐term care facilities (RLTCFs) and to provide an overview of their interventions, outcomes and methodological quality. Method We searched 18 electronic databases to identify English articles (published January 2000–December 2019) reporting on well‐defined DAIs targeting older adults (≥65 years) in RLTCF. Data were extracted by two independent reviewers. Descriptive statistics were produced for quantitative studies, with key themes identified among qualitative studies. Where possible, estimates were pooled from randomised controlled trials using random effects meta‐analyses. Results Forty‐three relevant studies (39 quantitative; 4 qualitative) were identified. The majority of quantitative studies were assessed as low‐quality according to the MMAT criteria (n = 26, 67%). Almost half of the quantitative studies (n = 18, 46%) found no significant changes over time or between groups across outcomes measured. The most salient intervention effects included improved social functioning (n = 10), reduced depressive symptoms (n = 6) and loneliness (n = 5). A random‐effects meta‐analysis revealed a medium effect in favour of DAT on reducing depressive or loneliness symptoms (pooled SMD: 0.66, 95%CI 0.21–1.11; I2 = 50.5; five trials), relative to treatment as usual. However, compared to treatment as usual, no overall effect of DAI on activities of daily living was detected (p = .737). Key themes from qualitative studies included (a) animals as effective transitional objects, (b) the therapeutic value of pets and (c) the significance of the care environment and stakeholders in facilitating DAI. Implications for practice The findings of this review indicate that while DAI has value for older people in RLTCF, challenges remain in accurately measuring its impact to provide a stronger evidence‐base. Standardisation of DAI service design, delivery and evaluation is required for future research and practice in providing holistic care for older adults

American Gut: An Open Platform For Citizen Science Microbiome Research

Copyright © 2018 McDonald et al. Although much work has linked the human microbiome to specific phenotypes and lifestyle variables, data from different projects have been challenging to integrate and the extent of microbial and molecular diversity in human stool remains unknown. Using standardized protocols from the Earth Microbiome Project and sample contributions from over 10,000 citizen-scientists, together with an open research network, we compare human microbiome specimens primarily from the United States, United Kingdom, and Australia to one another and to environmental samples. Our results show an unexpected range of beta-diversity in human stool microbiomes compared to environmental samples; demonstrate the utility of procedures for removing the effects of overgrowth during room-temperature shipping for revealing phenotype correlations; uncover new molecules and kinds of molecular communities in the human stool metabolome; and examine emergent associations among the microbiome, metabolome, and the diversity of plants that are consumed (rather than relying on reductive categorical variables such as veganism, which have little or no explanatory power). We also demonstrate the utility of the living data resource and cross-cohort comparison to confirm existing associations between the microbiome and psychiatric illness and to reveal the extent of microbiome change within one individual during surgery, providing a paradigm for open microbiome research and education. IMPORTANCE We show that a citizen science, self-selected cohort shipping samples through the mail at room temperature recaptures many known microbiome results from clinically collected cohorts and reveals new ones. Of particular interest is integrating n = 1 study data with the population data, showing that the extent of microbiome change after events such as surgery can exceed differences between distinct environmental biomes, and the effect of diverse plants in the diet, which we confirm with untargeted metabolomics on hundreds of samples

A mucosal vaccine against Chlamydia trachomatis generates two waves of protective memory T cells

Genital Chlamydia trachomatis (Ct) infection induces protective immunity that depends on interferon-γ producing CD4 T-cells. By contrast, mucosal exposure to ultraviolet light (UV)-inactivated Ct (UV-Ct) generated regulatory T-cells that exacerbated subsequent Ct infection. We show that mucosal immunization with UV-Ct complexed with charge-switching synthetic adjuvant particles (cSAP) elicited long-lived protection in conventional and humanized mice. UV-Ct-cSAP targeted immunogenic uterine CD11b+CD103− dendritic cells (DCs), whereas UV-Ct accumulated in tolerogenic CD11b−CD103+ DCs. Regardless of vaccination route, UV-Ct-cSAP induced systemic memory T-cells, but only mucosal vaccination induced effector T-cells that rapidly seeded uterine mucosa with resident memory T-cells (TRM). Optimal Ct clearance required both TRM seeding and subsequent infection-induced recruitment of circulating memory T-cells. Thus, UV-Ct-cSAP vaccination generated two synergistic memory T-cell subsets with distinct migratory properties

Global chemical effects of the microbiome include new bile-acid conjugations

A mosaic of cross-phylum chemical interactions occurs between all metazoans and their microbiomes. A number of molecular families that are known to be produced by the microbiome have a marked effect on the balance between health and disease. Considering the diversity of the human microbiome (which numbers over 40,000 operational taxonomic units), the effect of the microbiome on the chemistry of an entire animal remains underexplored. Here we use mass spectrometry informatics and data visualization approaches to provide an assessment of the effects of the microbiome on the chemistry of an entire mammal by comparing metabolomics data from germ-free and specific-pathogen-free mice. We found that the microbiota affects the chemistry of all organs. This included the amino acid conjugations of host bile acids that were used to produce phenylalanocholic acid, tyrosocholic acid and leucocholic acid, which have not previously been characterized despite extensive research on bile-acid chemistry. These bile-acid conjugates were also found in humans, and were enriched in patients with inflammatory bowel disease or cystic fibrosis. These compounds agonized the farnesoid X receptor in vitro, and mice gavaged with the compounds showed reduced expression of bile-acid synthesis genes in vivo. Further studies are required to confirm whether these compounds have a physiological role in the host, and whether they contribute to gut diseases that are associated with microbiome dysbiosis

American Gut: an Open Platform for Citizen Science Microbiome Research

McDonald D, Hyde E, Debelius JW, et al. American Gut: an Open Platform for Citizen Science Microbiome Research. mSystems. 2018;3(3):e00031-18