30 research outputs found
Protocol for the detection of defined T cell clones in a heterogeneous cell population
No full textSummary: Identifying defined T cell clones within a polyclonal population is key to clarifying their phenotype and function. Here, we present a protocol for detecting specified T cell clones in a heterogeneous cell population. We describe steps for stimulating human CD4+ T cells isolated from blood with a protein antigen, sorting antigen-specific cells by fluorescence-activated cell sorting, and detecting among these the presence of predefined T cell clones, based on their T cell receptor (TCR). TCR cDNA is amplified through 5′-RACE (TCR-SMART) and detected by qPCR.For complete details on the use and execution of this protocol, please refer to Notarbartolo et al. (2021).1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics
Human T lymphocytes at tumor sites
No full textCD4(+) and CD8(+) T lymphocytes mediate most of the adaptive immune response against tumors. Naïve T lymphocytes specific for tumor antigens are primed in lymph nodes by dendritic cells. Upon activation, antigen-specific T cells proliferate and differentiate into effector cells that migrate out of peripheral blood into tumor sites in an attempt to eliminate cancer cells. After accomplishing their function, most effector T cells die in the tissue, while a small fraction of antigen-specific T cells persist as long-lived memory cells, circulating between peripheral blood and lymphoid tissues, to generate enhanced immune responses when re-encountering the same antigen. A subset of memory T cells, called resident memory T (T(RM)) cells, stably resides in non-lymphoid peripheral tissues and may provide rapid immunity independently of T cells recruited from blood. Being adapted to the tissue microenvironment, T(RM) cells are potentially endowed with the best features to protect against the reemergence of cancer cells. However, when tumors give clinical manifestation, it means that tumor cells have evaded immune surveillance, including that of T(RM) cells. Here, we review the current knowledge as to how T(RM) cells are generated during an immune response and then maintained in non-lymphoid tissues. We then focus on what is known about the role of CD4(+) and CD8(+) T(RM) cells in antitumor immunity and their possible contribution to the efficacy of immunotherapy. Finally, we highlight some open questions in the field and discuss how new technologies may help in addressing them
SARS-CoV-2: A Glance at the Innate Immune Response Elicited by Infection and Vaccination
No full textThe COVID-19 pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has led to almost seven million deaths worldwide. SARS-CoV-2 causes infection through respiratory transmission and can occur either without any symptoms or with clinical manifestations which can be mild, severe or, in some cases, even fatal. Innate immunity provides the initial defense against the virus by sensing pathogen-associated molecular patterns and triggering signaling pathways that activate the antiviral and inflammatory responses, which limit viral replication and help the identification and removal of infected cells. However, temporally dysregulated and excessive activation of the innate immune response is deleterious for the host and associates with severe COVID-19. In addition to its defensive role, innate immunity is pivotal in priming the adaptive immune response and polarizing its effector function. This capacity is relevant in the context of both SARS-CoV-2 natural infection and COVID-19 vaccination. Here, we provide an overview of the current knowledge of the innate immune responses to SARS-CoV-2 infection and vaccination
T-Cell Immune Responses to SARS-CoV-2 Infection and Vaccination
No full textThe innate and adaptive immune systems collaborate to detect SARS-CoV-2 infection, minimize the viral spread, and kill infected cells, ultimately leading to the resolution of the infection. The adaptive immune system develops a memory of previous encounters with the virus, providing enhanced responses when rechallenged by the same pathogen. Such immunological memory is the basis of vaccine function. Here, we review the current knowledge on the immune response to SARS-CoV-2 infection and vaccination, focusing on the pivotal role of T cells in establishing protective immunity against the virus. After providing an overview of the immune response to SARS-CoV-2 infection, we describe the main features of SARS-CoV-2-specific CD4+ and CD8+ T cells, including cross-reactive T cells, generated in patients with different degrees of COVID-19 severity, and of Spike-specific CD4+ and CD8+ T cells induced by vaccines. Finally, we discuss T-cell responses to SARS-CoV-2 variants and hybrid immunity and conclude by highlighting possible strategies to improve the efficacy of COVID-19 vaccination
Non-Cooperative Interactions Between Transcription Factors and Clustered DNA Binding Sites Enable Graded Transcriptional Responses To Environmental Inputs
No full textA paradigm in transcriptional regulation is that graded increases in transcription factor (TF) concentration are translated into on/off transcriptional responses by cooperative TF binding to adjacent sites. Digital transcriptional responses underlie the definition of anatomical boundaries during development. Here we show that NF-κB, a TF controlling inflammation and immunity, is conversely an analog transcriptional regulator that uses clustered binding sites noncooperatively. We observed that increasing concentrations of NF-κB are translated into gradual increments in gene transcription. We provide a thermodynamic interpretation of the experimental observations by combining quantitative measurements and a minimal physical model of an NF-κB-dependent promoter. We demonstrate that NF-κB binds independently to adjacent sites to promote additive RNA Pol II recruitment and graded transcriptional outputs. These findings reveal an alternative mode of operation of clustered TF binding sites, which might function in biological conditions where the transcriptional output is proportional to the strength of an environmental input
The Histone H3 Lysine-27 Demethylase Jmjd3 Links Inflammation to Inhibition of Polycomb-Mediated Gene Silencing
No full textSummaryEpigenetic chromatin marks restrict the ability of differentiated cells to change gene expression programs in response to environmental cues and to transdifferentiate. Polycomb group (PcG) proteins mediate gene silencing and repress transdifferentiation in a manner dependent on histone H3 lysine 27 trimethylation (H3K27me3). However, macrophages migrated into inflamed tissues can transdifferentiate, but it is unknown whether inflammation alters PcG-dependent silencing. Here we show that the JmjC-domain protein Jmjd3 is a H3K27me demethylase expressed in macrophages in response to bacterial products and inflammatory cytokines. Jmjd3 binds PcG target genes and regulates their H3K27me3 levels and transcriptional activity. The discovery of an inducible enzyme that erases a histone mark controlling differentiation and cell identity provides a link between inflammation and reprogramming of the epigenome, which could be the basis for macrophage plasticity and might explain the differentiation abnormalities in chronic inflammation
Editorial: T cell specificity and cross-reactivity – implications in physiology and pathology
No full textISSN:1664-322
Dual Activation-Induced Marker Combinations Efficiently Identify and Discern Antigen-Specific and Bystander-Activated Human CD4⁺ T Cells
No full textISSN:0014-2980ISSN:1521-4141ISSN:1521-414
Secretory IgA amplification during immune checkpoint blockade enhances the control of tumor growth by enterotropic T cells
No full textThe gut microbiota is essential for many aspects of host physiology, and secretory immunoglobulin A (sIgA) modulates its function. The microbiota community determines the efficacy of immune checkpoint blockade (ICB) in cancer immunotherapy; however, mechanisms able to improve this function are not known. Extracellular adenosine triphosphate (ATP) released by the microbiota restricts the sIgA repertoire by limiting T follicular helper (TFH) cell activity in the Peyer's patches via stimulation of the ionotropic P2X7 receptor. We show that sIgA amplification by oral administration of the ATP hydrolyzing enzyme apyrase corrects enteropathic features of ICB and improves therapeutic efficacy. Consistent with sIgA function in reshaping the gut ecosystem and enhancing ICB, IgA-/- mice did not show any improvement of antitumor response by apyrase administration. Mechanistically, data in mice and patients with cancer suggest that invigorated enterotropic cytotoxic T cells expressing the chemokine receptor CCR9 replenish the tumor microenvironment in a CCL25-mediated manner and control tumor growth, resulting in improved ICB efficacy
