High Throughput Analysis of B Cell Dynamics and Neutralizing Antibody Development During Immunization With a Novel Clade C HIV-1 Envelope
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Broadly neutralizing antibodies from chronic infection are an area of interest for HIV-1 vaccine development. Using male and female rhesus macaques, a team of researchers conducted a high-throughput longitudinal study to determine how B cells respond to vaccines expressing different HIV-1 Env immunogens. In most animals, the B cells failed to achieve neutralizing activity. One animal, however, developed neutralizing antibodies against the vaccine strain. These data suggest that early elicitation might favor the induction of neutralizing antibodies against HIV-1 Env.
First-in-Human ImmunoPET Imaging of COVID-19 Convalescent Patients Using Dynamic Total-Body PET and a CD8-Targeted Minibody
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Developing noninvasive methods for in vivo quantification of T cell distribution and kinetics is important because most T cells reside in the tissue. Investigators presented the first use of dynamic positron emission tomography (PET) and kinetic modeling for in vivo measurement of CD8+ T cell distribution in healthy individuals and COVID-19 patients. Kinetic modeling results aligned with the expected T cell trafficking effects. Tissue-to-blood ratios were consistent with modeled net influx rates and flow cytometry analysis.
Enhanced IL-17 Producing and Maintained Cytolytic Effector Functions of Gut Mucosal CD161+ CD8+ T Cells in SIV-Infected Rhesus Macaques
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HIV infection is associated with the depletion of CD161-expressing CD4+ Th17 cells, but the effects on other IL-17–producing T cell subsets are not understood fully. Researchers characterized the functions of non-invariant CD161-expressing CD8+ T cell subpopulations in peripheral blood and mucosal tissues of rhesus macaques (sex not specified) during chronic simian immunodeficiency virus (SIV) infection.
Large-Scale Production of Human Blastoids Amenable to Modeling Blastocyst Development and Maternal-Fetal Crosstalk
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Human blastoids provide a valuable model to study early human development and implantation with reduced genetic heterogeneity between samples. Investigators reported a protocol for efficient generation of high-fidelity human blastoids from naïve pluripotent stem cells. The similarities between blastoids and blastocysts in signaling activities—demonstrated using single-cell RNA sequencing—support the use of blastoids to model lineage differentiation and cavity formation.
Intestinal Microbiota Controls Graft-Versus-Host Disease Independent of Donor–Host Genetic Disparity
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Allogeneic hematopoietic stem cell transplantation is a curative therapy for hematopoietic malignancies and non-malignant diseases, but acute graft-versus-host disease (GVHD) remains a serious complication. Specifically, severe gut GVHD is the major cause of transplant-related mortality. Here, the authors show that genetically identical mice, sourced from different vendors, had distinct commensal bacterial compositions, which resulted in significantly discordant severity in GVHD.
SALL1 Enforces Microglia-Specific DNA Binding and Function of SMADs to Establish Microglia Identity
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Microglia function is thought to play a role in neurodevelopmental, psychiatric, and neurodegenerative diseases. Using knockout mice, investigators explored functional interactions between spalt-like transcription factor 1 (SALL1) and SMAD4, which demonstrated that interactions are mediated by a conserved microglia-specific SALL1 super-enhancer and result in direct activation of regulatory elements. The concerted interactions induce a microglia lineage determining program of gene expression.
Epigenetic Dysregulation From Chromosomal Transit in Micronuclei
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The authors reported a mechanistic link between epigenetic alterations and chromosomal instability induced during their transit in micronuclei, both being hallmarks of advanced and metastatic cancers. It was demonstrated that the landscape of histone post-translational modifications was profoundly changed due to missegregation of mitotic chromosomes, their sequestration in micronuclei and subsequent rupture of the micronuclear envelope. The transcriptional redistribution was attributed to micronuclei’s strong positional bias with increased promoter accessibility.
Sequential Intrahost Evolution and Onward Transmission of SARS-CoV-2 Variants
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Most patients with COVID-19 clear the virus upon resolution of acute infection, but a subset of immunocompromised individuals develop persistent SARS-CoV-2 infections. In this study, investigators describe sequential persistent SARS-CoV-2 infections in three individuals that led to the emergence, forward transmission, and continued evolution of the Omicron BA.1 variant Omicron BA.1.23. The study demonstrated that in the presence of suboptimal immune responses, persistent viral replication is an important driver of SARS-CoV-2 diversification.
The Drosophila Chemokine-Like Orion Bridges Phosphatidylserine and Draper in Phagocytosis of Neurons
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Degenerating neurons can be cleared by phagocytosis triggered by “eat-me” signal phosphatidylserine (PS) and mediated by the engulfment receptor Draper (Drpr), yet the process is poorly understood. Investigators used several Drosophila models to study dendrite degeneration and demonstrated that the fly chemokine-like protein Orion binds to PS and mediates interactions between PS and Drpr to enable phagocytosis. This study identifies a link between immunomodulatory proteins and phagocytosis of neurons and reveals conserved mechanisms of clearing degenerating neurons.
p38MAPKα Stromal Reprogramming Sensitizes Metastatic Breast Cancer to Immunotherapy
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This study emphasizes the importance of the metastatic tumor microenvironment in metastatic breast cancer growth and the identification of effective antimetastatic therapies. Using a stromal labeling approach and single-cell RNA sequencing, the authors showed that a combination of p38MAPK inhibition (p38i) and anti-OX40 synergistically reduced metastatic tumor growth and increased overall survival. Further engagement of cytotoxic T cells cured all metastatic disease in mice and produced durable immunologic memory.