CD160 isoforms and regulation of CD4 and CD8 T-cell responses

BACKGROUND: Coexpression of CD160 and PD-1 on HIV-specific CD8(+) T-cells defines a highly exhausted T-cell subset. CD160 binds to Herpes Virus Entry Mediator (HVEM) and blocking this interaction with HVEM antibodies reverses T-cell exhaustion. As HVEM binds both inhibitory and activatory receptors, our aim in the current study was to assess the impact of CD160-specific antibodies on the enhancement of T-cell activation. METHODS: Expression of the two CD160 isoforms; glycosylphosphatidylinositol-anchored (CD160-GPI) and the transmembrane isoforms (CD160-TM) was assessed in CD4 and CD8 primary T-cells by quantitative RT-PCR and Flow-cytometry. Binding of these isoforms to HVEM ligand and the differential capacities of CD160 and HVEM specific antibodies to inhibit this binding were further evaluated using a Time-Resolved Fluorescence assay (TRF). The impact of both CD160 and HVEM specific antibodies on enhancing T-cell functionality upon antigenic stimulation was performed in comparative ex vivo studies using primary cells from HIV-infected subjects stimulated with HIV antigens in the presence or absence of blocking antibodies to the key inhibitory receptor PD-1. RESULTS: We first show that both CD160 isoforms, CD160-GPI and CD160-TM, were expressed in human primary CD4(+) and CD8(+) T-cells. The two isoforms were also recognized by the HVEM ligand, although this binding was less pronounced with the CD160-TM isoform. Mechanistic studies revealed that although HVEM specific antibodies blocked its binding to CD160-GPI, surprisingly, these antibodies enhanced HVEM binding to CD160-TM, suggesting that potential antibody-mediated HVEM multimerization and/or induced conformational changes may be required for optimal CD160-TM binding. Triggering of CD160-GPI over-expressed on Jurkat cells with either bead-bound HVEM-Fc or anti-CD160 monoclonal antibodies enhanced cell activation, consistent with a positive co-stimulatory role for CD160-GPI. However, CD160-TM did not respond to this stimulation, likely due to the lack of optimal HVEM binding. Finally, ex vivo assays using PBMCs from HIV viremic subjects showed that the use of CD160-GPI-specific antibodies combined with blockade of PD-1 synergistically enhanced the proliferation of HIV-1 specific CD8(+) T-cells upon antigenic stimulation. CONCLUSIONS: Antibodies targeting CD160-GPI complement the blockade of PD-1 to enhance HIV-specific T-cell responses and warrant further investigation in the development of novel immunotherapeutic approaches. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12967-014-0217-y) contains supplementary material, which is available to authorized users

Distinct Gene Number-Genome Size Relationships for Eukaryotes and Non-Eukaryotes: Gene Content Estimation for Dinoflagellate Genomes

The ability to predict gene content is highly desirable for characterization of not-yet sequenced genomes like those of dinoflagellates. Using data from completely sequenced and annotated genomes from phylogenetically diverse lineages, we investigated the relationship between gene content and genome size using regression analyses. Distinct relationships between log10-transformed protein-coding gene number (Y′) versus log10-transformed genome size (X′, genome size in kbp) were found for eukaryotes and non-eukaryotes. Eukaryotes best fit a logarithmic model, Y′ = ln(-46.200+22.678X′, whereas non-eukaryotes a linear model, Y′ = 0.045+0.977X′, both with high significance (p<0.001, R2>0.91). Total gene number shows similar trends in both groups to their respective protein coding regressions. The distinct correlations reflect lower and decreasing gene-coding percentages as genome size increases in eukaryotes (82%–1%) compared to higher and relatively stable percentages in prokaryotes and viruses (97%–47%). The eukaryotic regression models project that the smallest dinoflagellate genome (3×106 kbp) contains 38,188 protein-coding (40,086 total) genes and the largest (245×106 kbp) 87,688 protein-coding (92,013 total) genes, corresponding to 1.8% and 0.05% gene-coding percentages. These estimates do not likely represent extraordinarily high functional diversity of the encoded proteome but rather highly redundant genomes as evidenced by high gene copy numbers documented for various dinoflagellate species

Intersection Graphs of Maximal Sub-polygons of k-Lizards

Abstract We introduce k-maximal sub-polygon graphs (k-MSP graphs), the intersection graphs of maximal polygons contained in a polygon with sides parallel to a regular 2k-gon. We prove that all complete graphs are k-MSP graphs for all $$k>1$$ k > 1 ; trees are 2-MSP graphs; trees are k-MSP graphs for $$k>2$$ k > 2 if and only if they are caterpillars; and n-cycles are not k-MSP graphs for $$n>3$$ n > 3 and $$k>1$$ k > 1 . We derive bounds for which j-cycles appear as induced subgraphs of k-MSP graphs. As our main result, we construct examples of graphs which are k-MSP graphs and not j-MSP graphs for all $$k>1$$ k > 1 , $$j>1$$ j > 1 , $$k \ne j$$ k ≠ j

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Historical Loss: Implications for Health of American Indians in the Blackfeet Community

Abstract Background Historical loss in American Indians (AIs) is believed to contribute to high incidence of mental health disorders, yet less is known about the associations between historical loss and physical health. Purpose To investigate whether frequency of thought about historical loss predicts risk factors for chronic physical health conditions in an AI community. Methods Using Community Based Participatory research (CBPR) and Ecological Momentary Assessment (EMA), we measured frequency of thoughts about historical loss in 100 AI adults residing on the Blackfeet reservation. Participants completed a 1-week monitoring period, during which ambulatory blood pressure and daily levels of psychological stress were measured. At the end of the week, we collected a dried blood spot sample for measurement of C-reactive protein (CRP). Results In hierarchical linear regression models controlling for demographics and relevant covariates, greater frequency of thoughts about historical loss predicted higher average daily psychological stress (B = .55, t = 6.47, p &amp;lt; .001, ΔR2 = .30) and higher levels of CRP (B = .33, t = 3.93, p &amp;lt; .001, ΔR2 = .10). Using linear mixed modeling with relevant covariates, we found that greater thoughts about historical loss were associated with higher systolic ambulatory blood pressure (B = .32, 95% CI = .22–.42, t = 6.48, p &amp;lt; .001, ΔR2 = .25; Fig. 1c) and greater diastolic ambulatory blood pressure (B = .19, 95% CI = .11–.27, t = 4.73, p &amp;lt; .001, ΔR2 = .19). Conclusions The data suggest that frequency of thought about historical loss may contribute to increased subclinical risk for cardiovascular disease in the Blackfeet community. </jats:sec