DNGR‐1 is dispensable for CD8⁺ T‐cell priming during respiratory syncytial virus infection

Abstract

During respiratory syncytial virus (RSV) infection CD8+ T cells both assist in viral clearance and contribute to immunopathology. CD8 + T cells recognize viral peptides presented by dendritic cells (DCs), which can directly present viral antigens when infected or, alternatively, "cross-present" antigens after endocytosis of dead or dying infected cells. Mouse CD8α + and CD103 + DCs excel at cross-presentation, in part because they express the receptor DNGR-1 that detects dead cells by binding to exposed F-actin and routes internalized cell debris into the cross-presentation pathway. As RSV causes death in infected epithelial cells, we tested whether cross-presentation via DNGR-1 is necessary for CD8 + T-cell responses to the virus. DNGR-1-deficient or wild-type mice were intranasally inoculated with RSV and the magnitude of RSV-specific CD8+ T-cell induction was measured. We found that during live RSV infection, cross-presentation via DNGR-1 did not have a major role in the generation of RSV-specific CD8+ T-cell responses. However, after intranasal immunization with dead cells infected with RSV, a dependence on DNGR-1 for RSV-specific CD8 + T-cell responses was observed, confirming the ascribed role of the receptor. Thus, direct presentation by DCs may be the major pathway initiating CD8 + T-cell responses to RSV, while DNGR-1-dependent cross-presentation has no detectable role. Keywords: CD8+ T cell r Cross-presentation r DNGR-1 r Lung infection r Virus Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionRespiratory syncytial virus (RSV) is an important respiratory virus of the single-stranded RNA virus family Paramyxoviridae. RSV disease burden is estimated at 64 million cases and up to 160,000 deaths every year worldwide (www.who.int). While RSV disease manifests as a simple common cold in the majority of cases, between 2 and 3% of children develop severe bronchiolitis. Although most of these children recover, they have a greater risk of developing recurrent wheeze and asthma-like symptoms in later childhood [1,2]. RSV infection induces a robust virusCorrespondence: Dr. Cecilia Johansson e-mail: c.johansson@imperial.ac.uk specific CD8 + T-cell response. These T cells play a key role in viral clearance by destroying infected cells [3] although, in mouse models, they also contribute to lung immunopathology following RSV infection [1,4,5]. Antigen processing and presentation of peptides on MHC class I (MHC-I) is crucial for CD8 + T-cell responses to RSV and other viruses. The classical pathway, whereby peptides from the cytosol are loaded onto MHC-I molecules in the ER and transported to the cell surface, is thought to be the major mechanism by which viral antigens are displayed on the surface of infected cells [6]. However, uninfected cells can also present viral antigens in some instances. This is termed "cross-presentation" and involves antigens released from virally infected cells, often in the form of debris of lysed cells, being taken...

T cell responses are elicited against Respiratory Syncytial Virus in the absence of signalling through TLRs, RLRs and IL-1R/IL-18R

“…DNGR-1 is a receptor that can couple detection of dead cells to CD8 + T cell priming 29 , even though it is not, technically, a DC-activating receptor 30 31 . However, we have recently shown that DNGR-1 is dispensable for T cell responses to RSV in mice 32 although it could become non-redundant in the MTM −/− mice, when activation of DCs via PAMPs is absent. Other dead cell-derived mediators that could promote DC activation include heat shock proteins, HMGB1, uric acid, and ATP 28 .…”

“…according to UK home office guidelines. Bronchoalveolar lavage (BAL) and lungs were obtained as described previously 32 . Briefly, BAL was collected by flushing the lungs three times with 1 ml of PBS/0.5 mM EDTA (Life Technologies).…”

Alveolar macrophage–derived type I interferons orchestrate innate immunity to RSV through recruitment of antiviral monocytes

“…To determine the cellular composition of the BAL, cells were transferred onto a microscope slide (Thermo Fisher Scientific) using a Shandon Cytospin 3 centrifuge, and slides were stained with hematoxylin and eosin (H&E; Reagena, Gamidor). Cells were categorized as macrophages, lymphocytes, neutrophils, and eosinophils based on morphology and size under a light microscope (Axio; Carl Zeiss; Durant et al, 2014 ).…”

Long-lived tissue resident HIV-1 specific memory CD8+ T cells are generated by skin immunization with live virus vectored microneedle arrays

“…In some experiments, blood was collected from the tail vein into EDTA-coated Eppendorf tubes and further treated with red blood cell lysis buffer (Sigma–Aldrich) prior to Ab staining. Lungs and female genital tracts (GTs) were harvested from perfused female mice and broncho-alveolar lavage (BAL) fluid was also collected where indicated as described previously [19] .…”