Distinct Tissue-Dependent Composition and Gene Expression of Human Fetal Innate Lymphoid Cells.

The human fetal immune system starts to develop in the first trimester and likely plays a crucial role in fetal development and maternal-fetal tolerance. Innate lymphoid cells (ILCs) are the earliest lymphoid cells to arise in the human fetus. ILCs consist of natural killer (NK) cells, ILC1s, ILC2s, and ILC3s that all share a common lymphoid origin.

CopyVAE: a variational autoencoder-based approach for copy number variation inference using single-cell transcriptomics.

Motivation: Copy number variations (CNVs) are common genetic alterations in tumour cells. The delineation of CNVs holds promise for enhancing our comprehension of cancer progression. Moreover, accurate inference of CNVs from single-cell sequencing data is essential for unravelling intratumoral heterogeneity.

Long-read whole-genome analysis of human single cells.

Long-read sequencing has dramatically increased our understanding of human genome variation. Here, we demonstrate that long-read technology can give new insights into the genomic architecture of individual cells. Clonally expanded CD8+ T-cells from a human donor were subjected to droplet-based multiple displacement amplification (dMDA) to generate long molecules with reduced bias.

Reconstructing clonal tree for phylo-phenotypic characterization of cancer using single-cell transcriptomics.

Functional characterization of the cancer clones can shed light on the evolutionary mechanisms driving cancer's proliferation and relapse mechanisms. Single-cell RNA sequencing data provide grounds for understanding the functional state of cancer as a whole; however, much research remains to identify and reconstruct clonal relationships toward characterizing the changes in functions of individual clones. We present PhylEx that integrates bulk genomics data with co-occurrences of mutations from single-cell RNA sequencing data to reconstruct high-fidelity clonal trees.

Prostate cancer disease recurrence after radical prostatectomy is associated with HLA type and local cytomegalovirus immunity.

Prostate cancer is a heterogeneous disease with a need for new prognostic biomarkers. Human leukocyte antigen (HLA) genes are highly polymorphic genes central to antigen presentation to T-cells. Two alleles, HLA-A*02:01 and HLA-A*24:02, have been associated with prognosis in patients diagnosed with de novo metastatic prostate cancer.

Divergent clonal differentiation trajectories establish CD8 memory T cell heterogeneity during acute viral infections in humans.

The CD8 T cell response to an antigen is composed of many T cell clones with unique T cell receptors, together forming a heterogeneous repertoire of effector and memory cells. How individual T cell clones contribute to this heterogeneity throughout immune responses remains largely unknown. In this study, we longitudinally track human CD8 T cell clones expanding in response to yellow fever virus (YFV) vaccination at the single-cell level.

Expansions of adaptive-like NK cells with a tissue-resident phenotype in human lung and blood.

Human adaptive-like "memory" CD56CD16 natural killer (NK) cells in peripheral blood from cytomegalovirus-seropositive individuals have been extensively investigated in recent years and are currently explored as a treatment strategy for hematological cancers. However, treatment of solid tumors remains limited due to insufficient NK cell tumor infiltration, and it is unknown whether large expansions of adaptive-like NK cells that are equipped for tissue residency and tumor homing exist in peripheral tissues. Here, we show that human lung and blood contains adaptive-like CD56CD16 NK cells with hallmarks of tissue residency, including expression of CD49a.

A heterozygous germline CD100 mutation in a family with primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is a chronic inflammatory liver disease without clear etiology or effective treatment. Genetic factors contribute to PSC pathogenesis, but so far, no causative mutation has been found. We performed whole-exome sequencing in a family with autosomal dominant inheritance of PSC and identified a heterozygous germline missense mutation in , encoding a K849T variant of CD100.

Activation of a neural stem cell transcriptional program in parenchymal astrocytes.

Adult neural stem cells, located in discrete brain regions, generate new neurons throughout life. These stem cells are specialized astrocytes, but astrocytes in other brain regions do not generate neurons under physiological conditions. After stroke, however, striatal astrocytes undergo neurogenesis in mice, triggered by decreased Notch signaling.

Cell generation dynamics underlying naive T-cell homeostasis in adult humans.

Thymic involution and proliferation of naive T cells both contribute to shaping the naive T-cell repertoire as humans age, but a clear understanding of the roles of each throughout a human life span has been difficult to determine. By measuring nuclear bomb test-derived 14C in genomic DNA, we determined the turnover rates of CD4+ and CD8+ naive T-cell populations and defined their dynamics in healthy individuals ranging from 20 to 65 years of age. We demonstrate that naive T-cell generation decreases with age because of a combination of declining peripheral division and thymic production during adulthood.

Single-Cell RNA Sequencing of the T Helper Cell Response to House Dust Mites Defines a Distinct Gene Expression Signature in Airway Th2 Cells.

Naive CD4 T cells differentiate into functionally diverse T helper (Th) cell subsets. Th2 cells play a pathogenic role in asthma, yet a clear picture of their transcriptional profile is lacking. We performed single-cell RNA sequencing (scRNA-seq) of T helper cells from lymph node, lung, and airways in the house dust mite (HDM) model of allergic airway disease.

Conbase: a software for unsupervised discovery of clonal somatic mutations in single cells through read phasing.

Accurate variant calling and genotyping represent major limiting factors for downstream applications of single-cell genomics. Here, we report Conbase for the identification of somatic mutations in single-cell DNA sequencing data. Conbase leverages phased read data from multiple samples in a dataset to achieve increased confidence in somatic variant calls and genotype predictions.

Probabilistic count matrix factorization for single cell expression data analysis.

Motivation: The development of high-throughput single-cell sequencing technologies now allows the investigation of the population diversity of cellular transcriptomes. The expression dynamics (gene-to-gene variability) can be quantified more accurately, thanks to the measurement of lowly expressed genes. In addition, the cell-to-cell variability is high, with a low proportion of cells expressing the same genes at the same time/level.

High dimensional classification with combined adaptive sparse PLS and logistic regression.

Motivation: The high dimensionality of genomic data calls for the development of specific classification methodologies, especially to prevent over-optimistic predictions. This challenge can be tackled by compression and variable selection, which combined constitute a powerful framework for classification, as well as data visualization and interpretation. However, current proposed combinations lead to unstable and non convergent methods due to inappropriate computational frameworks.

The Lifespan and Turnover of Microglia in the Human Brain.

The hematopoietic system seeds the CNS with microglial progenitor cells during the fetal period, but the subsequent cell generation dynamics and maintenance of this population have been poorly understood. We report that microglia, unlike most other hematopoietic lineages, renew slowly at a median rate of 28% per year, and some microglia last for more than two decades. Furthermore, we find no evidence for the existence of a substantial population of quiescent long-lived cells, meaning that the microglia population in the human brain is sustained by continuous slow turnover throughout adult life.

Comparison of whole genome amplification techniques for human single cell exome sequencing.

Background: Whole genome amplification (WGA) is currently a prerequisite for single cell whole genome or exome sequencing. Depending on the method used the rate of artifact formation, allelic dropout and sequence coverage over the genome may differ significantly.

Results: The largest difference between the evaluated protocols was observed when analyzing the target coverage and read depth distribution.

Antibody-secreting plasma cells persist for decades in human intestine.

Plasma cells (PCs) produce antibodies that mediate immunity after infection or vaccination. In contrast to PCs in the bone marrow, PCs in the gut have been considered short lived. In this study, we studied PC dynamics in the human small intestine by cell-turnover analysis in organ transplants and by retrospective cell birth dating measuring carbon-14 in genomic DNA.

Identifying T Cell Receptors from High-Throughput Sequencing: Dealing with Promiscuity in TCRα and TCRβ Pairing.

Characterisation of the T cell receptors (TCR) involved in immune responses is important for the design of vaccines and immunotherapies for cancer and autoimmune disease. The specificity of the interaction between the TCR heterodimer and its peptide-MHC ligand derives largely from the juxtaposed hypervariable CDR3 regions on the TCRα and TCRβ chains, and obtaining the paired sequences of these regions is a standard for functionally defining the TCR. A brute force approach to identifying the TCRs in a population of T cells is to use high-throughput single-cell sequencing, but currently this process remains costly and risks missing small clones.

Analysis of allelic expression patterns in clonal somatic cells by single-cell RNA-seq.

Cellular heterogeneity can emerge from the expression of only one parental allele. However, it has remained controversial whether, or to what degree, random monoallelic expression of autosomal genes (aRME) is mitotically inherited (clonal) or stochastic (dynamic) in somatic cells, particularly in vivo. Here we used allele-sensitive single-cell RNA-seq on clonal primary mouse fibroblasts and freshly isolated human CD8 T cells to dissect clonal and dynamic monoallelic expression patterns.

Continuous Antigenic Stimulation of DO11.10 TCR Transgenic Mice in the Presence or Absence of IL-1β: Possible Implications for Mechanisms of T Cell Depletion in HIV Disease.

Untreated HIV disease is associated with chronic immune activation and CD4(+) T cell depletion. A variety of mechanisms have been invoked to account for CD4(+) T cell depletion in this setting, but the quantitative contributions of these proposed mechanisms over time remain unclear. We turned to the DO11.