scholarly journals Trogocytosis-associated cell to cell spread of intracellular bacterial pathogens

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Shaun Steele ◽  
Lauren Radlinski ◽  
Sharon Taft-Benz ◽  
Jason Brunton ◽  
Thomas H Kawula
Keyword(s):  
Immune Cell ◽  
Bacterial Pathogens ◽  
Immune Surveillance ◽  
Cell Types ◽  
Antimicrobial Activities ◽  
Host Cells ◽  
Phagocytic Cells ◽  
Microbial Infections ◽  
Infected Cells

Macrophages are myeloid-derived phagocytic cells and one of the first immune cell types to respond to microbial infections. However, a number of bacterial pathogens are resistant to the antimicrobial activities of macrophages and can grow within these cells. Macrophages have other immune surveillance roles including the acquisition of cytosolic components from multiple types of cells. We hypothesized that intracellular pathogens that can replicate within macrophages could also exploit cytosolic transfer to facilitate bacterial spread. We found that viable Francisella tularensis, as well as Salmonella enterica bacteria transferred from infected cells to uninfected macrophages along with other cytosolic material through a transient, contact dependent mechanism. Bacterial transfer occurred when the host cells exchanged plasma membrane proteins and cytosol via a trogocytosis related process leaving both donor and recipient cells intact and viable. Trogocytosis was strongly associated with infection in mice, suggesting that direct bacterial transfer occurs by this process in vivo.

scholarly journals Pseudomonas aeruginosa Cytotoxin ExoU Is Injected into Phagocytic Cells during Acute Pneumonia

2010 ◽  
Vol 78 (4) ◽  
pp. 1447-1456 ◽  
Author(s):  
Maureen H. Diaz ◽  
Alan R. Hauser
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Immune Cells ◽  
Type Iii Secretion ◽  
Cell Types ◽  
Secretion System ◽  
Host Cells ◽  
Phagocytic Cells ◽  
Acute Pneumonia

ABSTRACT ExoU, a cytotoxin translocated into host cells via the type III secretion system of Pseudomonas aeruginosa, is associated with increased mortality and disease severity. We previously showed that impairment of recruited phagocytic cells allowed survival of ExoU-secreting P. aeruginosa in the lung. Here we analyzed types of cells injected with ExoU in vivo using translational fusions of ExoU with a β-lactamase reporter (ExoU-Bla). Cells injected with ExoU-Bla were detectable in vitro but not in vivo, presumably due to the rapid cytotoxicity induced by the toxin. Therefore, we used a noncytotoxic ExoU variant, designated ExoU(S142A)-Bla, to analyze injection in vivo. We determined that phagocytic cells in the lung were frequently injected with ExoU(S142A). Early during infection, resident macrophages constituted the majority of cells into which ExoU was injected, but neutrophils and monocytes became the predominant types of cells into which ExoU was injected upon recruitment into the lung. We observed a modest preference for injection into neutrophils over injection into other cell types, but in general the repertoire of injected immune cells reflected the relative abundance of these cells in the lung. Our results indicate that phagocytic cells in the lung are injected with ExoU and support the hypothesis that ExoU-mediated impairment of phagocytes has a role in the pathogenesis of pneumonia caused by P. aeruginosa.

scholarly journals Establishment of a Patient-Derived, Magnetic Levitation-Based, 3D Spheroid Granuloma Model for Human Tuberculosis.

2021 ◽  
Author(s):  
Leigh Ann Kotze ◽  
Caroline G.G. Beltran ◽  
Dirk Lang ◽  
Andre G Loxton ◽  
Susan Cooper ◽  
...  
Keyword(s):  
Immune Cell ◽  
Magnetic Levitation ◽  
Cell Types ◽  
Host Cells ◽  
Cellular Interactions ◽  
Cell Recruitment ◽  
Metabolic Heterogeneity ◽  
Histological Architecture

Tuberculous granulomas that develop in response to Mycobacterium tuberculosis (M.tb) infection are highly dynamic entities shaped by the host immune response and disease kinetics. Within this microenvironment, immune cell recruitment, polarization and activation is driven not only by co-existing cell types and multi-cellular interactions, but also by M.tb-mediated changes involving metabolic heterogeneity, epigenetic reprogramming and rewiring of the transcriptional landscape of host cells. There is an increased appreciation of the in vivo complexity, versatility and heterogeneity of the cellular compartment that constitutes the tuberculosis (TB) granuloma, and the difficulty in translating findings from animal models to human disease. Here we describe a novel biomimetic in vitro 3-dimentional (3D) human lung granuloma model, resembling early innate and adaptive stages of the TB granuloma spectrum, and present results of histological architecture, host transcriptional characterization, mycobacteriological features, cytokine profiles and spatial distribution of key immune cells. A range of manipulations of immune cell populations in these granulomas will allow the study of host/pathogen pathways involved in the outcome of infection, as well as pharmacological interventions.

scholarly journals The ORF8 Protein of SARS-CoV-2 Mediates Immune Evasion through Potently Downregulating MHC-I

2020 ◽  
Author(s):  
Yiwen Zhang ◽  
Junsong Zhang ◽  
Yingshi Chen ◽  
Baohong Luo ◽  
Yaochang Yuan ◽  
...  
Keyword(s):  
Immune Surveillance ◽  
Cell Types ◽  
Surface Expression ◽  
Viral Immunity ◽  
Mhc I ◽  
Reading Frame ◽  
Global Pandemic ◽  
Infected Cells ◽  
Genetic Sequences

SummarySARS-CoV-2 infection have caused global pandemic and claimed over 5,000,000 tolls1–4. Although the genetic sequences of their etiologic viruses are of high homology, the clinical and pathological characteristics of COVID-19 significantly differ from SARS5,6. Especially, it seems that SARS-CoV-2 undergoes vast replication in vivo without being effectively monitored by anti-viral immunity7. Here, we show that the viral protein encoded from open reading frame 8 (ORF8) of SARS-CoV-2, which shares the least homology with SARS-CoV among all the viral proteins, can directly interact with MHC-I molecules and significantly down-regulates their surface expression on various cell types. In contrast, ORF8a and ORF8b of SARS-CoV do not exert this function. In the ORF8-expressing cells, MHC-I molecules are selectively target for lysosomal degradation by an autophagy-dependent mechanism. As a result, CTLs inefficiently eliminate the ORF8-expressing cells. Our results demonstrate that ORF8 protein disrupts antigen presentation and reduces the recognition and the elimination of virus-infected cells by CTLs8. Therefore, we suggest that the inhibition of ORF8 function could be a strategy to improve the special immune surveillance and accelerate the eradication of SARS-CoV-2 in vivo.

scholarly journals Characterization of immune cell migration using microfabrication

2021 ◽  
Author(s):  
Doriane Vesperini ◽  
Galia Montalvo ◽  
Bin Qu ◽  
Franziska Lautenschläger
Keyword(s):  
Cell Migration ◽  
Immune Cells ◽  
Immune Cell ◽  
Immune Surveillance ◽  
Advantages And Disadvantages ◽  
Infected Cells ◽  
Immune Cell Migration ◽  
Underlying Mechanisms

AbstractThe immune system provides our defense against pathogens and aberrant cells, including tumorigenic and infected cells. Motility is one of the fundamental characteristics that enable immune cells to find invading pathogens, control tissue damage, and eliminate primary developing tumors, even in the absence of external treatments. These processes are termed “immune surveillance.” Migration disorders of immune cells are related to autoimmune diseases, chronic inflammation, and tumor evasion. It is therefore essential to characterize immune cell motility in different physiologically and pathologically relevant scenarios to understand the regulatory mechanisms of functionality of immune responses. This review is focused on immune cell migration, to define the underlying mechanisms and the corresponding investigative approaches. We highlight the challenges that immune cells encounter in vivo, and the microfabrication methods to mimic particular aspects of their microenvironment. We discuss the advantages and disadvantages of the proposed tools, and provide information on how to access them. Furthermore, we summarize the directional cues that regulate individual immune cell migration, and discuss the behavior of immune cells in a complex environment composed of multiple directional cues.

scholarly journals Single-cell map of diverse immune phenotypes in the acute myeloid leukemia microenvironment

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Rongqun Guo ◽  
Mengdie Lü ◽  
Fujiao Cao ◽  
Guanghua Wu ◽  
Fengcai Gao ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Single Cell ◽  
Myeloid Leukemia ◽  
Immune Cell ◽  
Immune Surveillance ◽  
Cell Types ◽  
Developmental Trajectory ◽  
Significant Difference ◽  
Cell Phenotypes ◽  
Acute Myeloid

Abstract Background Knowledge of immune cell phenotypes, function, and developmental trajectory in acute myeloid leukemia (AML) microenvironment is essential for understanding mechanisms of evading immune surveillance and immunotherapy response of targeting special microenvironment components. Methods Using a single-cell RNA sequencing (scRNA-seq) dataset, we analyzed the immune cell phenotypes, function, and developmental trajectory of bone marrow (BM) samples from 16 AML patients and 4 healthy donors, but not AML blasts. Results We observed a significant difference between normal and AML BM immune cells. Here, we defined the diversity of dendritic cells (DC) and macrophages in different AML patients. We also identified several unique immune cell types including T helper cell 17 (TH17)-like intermediate population, cytotoxic CD4+ T subset, T cell: erythrocyte complexes, activated regulatory T cells (Treg), and CD8+ memory-like subset. Emerging AML cells remodels the BM immune microenvironment powerfully, leads to immunosuppression by accumulating exhausted/dysfunctional immune effectors, expending immune-activated types, and promoting the formation of suppressive subsets. Conclusion Our results provide a comprehensive AML BM immune cell census, which can help to select pinpoint targeted drug and predict efficacy of immunotherapy.

scholarly journals Systematic comparison of high-throughput single-cell RNA-seq methods for immune cell profiling

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Tracy M. Yamawaki ◽  
Daniel R. Lu ◽  
Daniel C. Ellwanger ◽  
Dev Bhatt ◽  
Paolo Manzanillo ◽  
...  
Keyword(s):  
Single Cell ◽  
High Throughput ◽  
Immune Cell ◽  
Cell Types ◽  
Data Interpretation ◽  
Detection Sensitivity ◽  
Rna Seq ◽  
Cell Recovery

Abstract Background Elucidation of immune populations with single-cell RNA-seq has greatly benefited the field of immunology by deepening the characterization of immune heterogeneity and leading to the discovery of new subtypes. However, single-cell methods inherently suffer from limitations in the recovery of complete transcriptomes due to the prevalence of cellular and transcriptional dropout events. This issue is often compounded by limited sample availability and limited prior knowledge of heterogeneity, which can confound data interpretation. Results Here, we systematically benchmarked seven high-throughput single-cell RNA-seq methods. We prepared 21 libraries under identical conditions of a defined mixture of two human and two murine lymphocyte cell lines, simulating heterogeneity across immune-cell types and cell sizes. We evaluated methods by their cell recovery rate, library efficiency, sensitivity, and ability to recover expression signatures for each cell type. We observed higher mRNA detection sensitivity with the 10x Genomics 5′ v1 and 3′ v3 methods. We demonstrate that these methods have fewer dropout events, which facilitates the identification of differentially-expressed genes and improves the concordance of single-cell profiles to immune bulk RNA-seq signatures. Conclusion Overall, our characterization of immune cell mixtures provides useful metrics, which can guide selection of a high-throughput single-cell RNA-seq method for profiling more complex immune-cell heterogeneity usually found in vivo.

scholarly journals Single Cell Atlas of Human Dura Reveals Cellular Meningeal Landscape and Insights into Meningioma Immune Response

2021 ◽  
Author(s):  
Anthony Z Wang ◽  
Jay Bowman-Kirigin ◽  
Rupen Desai ◽  
Pujan Patel ◽  
Bhuvic Patel ◽  
...  
Keyword(s):  
Single Cell ◽  
Immune Cell ◽  
Immune Surveillance ◽  
Copy Number Variant ◽  
Cell Types ◽  
Cell Receptor ◽  
Immune Microenvironment ◽  
Clinical Models ◽  
Insight Into

Recent investigation of the meninges, specifically the dura layer, has highlighted its importance in CNS immune surveillance beyond a purely structural role. However, most of our understanding of the meninges stems from the use of pre-clinical models rather than human samples. In this study, we use single cell RNA-sequencing to perform the first characterization of both non-tumor-associated human dura and meningioma samples. First, we reveal a complex immune microenvironment in human dura that is transcriptionally distinct from that of meningioma. In addition, through T cell receptor sequencing, we show significant TCR overlap between matched dura and meningioma samples. We also identify a functionally heterogeneous population of non-immune cell types and report copy-number variant heterogeneity within our meningioma samples. Our comprehensive investigation of both the immune and non-immune cell landscapes of human dura and meningioma at a single cell resolution provide new insight into previously uncharacterized roles of human dura.

scholarly journals A critical role of the T3SS effector EseJ in intracellular trafficking and replication ofEdwardsiella piscicidain non-phagocytic cells

2018 ◽  
Author(s):  
Lingzhi Zhang ◽  
Jiatiao Jiang ◽  
Tianjian Hu ◽  
Jin Zhang ◽  
Xiaohong Liu ◽  
...  
Keyword(s):  
Bacterial Colonization ◽  
Critical Role ◽  
Host Cells ◽  
Intracellular Replication ◽  
Phagocytic Cells ◽  
T3ss Effector ◽  
Early Endosomes ◽  
Underlying Mechanisms ◽  
Endosome Maturation

AbstractEdwardsiella piscicida(E. piscicida) is an intracellular pathogen within a broad spectrum of hosts. Essential toE. piscicidavirulence is its ability to survive and replicate inside host cells, yet the underlying mechanisms and the nature of the replicative compartment remain unclear. Here, we characterized its intracellular lifestyle in non-phagocytic cells and showed that intracellular replication ofE. piscicidain non-phagocytic cells is dependent on its type III secretion system. Following internalization,E. piscicidais contained in vacuoles that transiently mature into early endosomes, but subsequently bypasses the classical endosome pathway and fusion with lysosomes which depends on its T3SS. Following a rapid escape from the degradative pathway,E. piscicidawas found to create a specialized replication-permissive niche characterized by endoplasmic reticulum (ER) markers. We also found that a T3SS effector EseJ is responsible for intracellular replication ofE. piscicidaby preventing endosome/lysosome fusion. Furthermore,in vivoexperiments confirmed that EseJ is necessary for bacterial colonization ofE. piscicidain both mice and zebrafish. Thus, this work elucidates the strategies used byE. piscicidato survive and proliferate within host non-phagocytic cells.Author summaryE. piscicidais a facultative intracellular bacterium associated with septicemia and fatal infections in many animals, including fish and humans. However, little is known about its intracellular life, which is important for successful invasion of the host. The present study is the first comprehensive characterization ofE. piscicida’s intracellular life-style in host cells. Upon internalization,E. piscicidais transiently contained in Rab5-positive vacuoles, but the pathogen prevents further endosome maturation and fusion with lysosomes by utilizing an T3SS effector EseJ. In addition, the bacterium creates an specialized replication niche for rapid growth via an interaction with the ER. Our study provides new insights into the strategies used byE. piscicidato successfully establishes an intracellular lifestyle that contributes to its survival and dissemination during infection.

scholarly journals Efficient Killing of Multidrug-Resistant Intracellular Bacteria by AIEgens in Vivo

2020 ◽  
Author(s):  
Ying Li ◽  
Fei Liu ◽  
Jiangjiang Zhang ◽  
Xiaoye Liu ◽  
Peihong Xiao ◽  
...  
Keyword(s):  
Membrane Damage ◽  
Multidrug Resistant ◽  
Host Cells ◽  
Comparable Efficacy ◽  
Intracellular Bacteria ◽  
New Agents ◽  
Immune Clearance ◽  
Infected Cells ◽  
Dose Levels

<p><a>Bacteria infected cells acting as “Trojan horses” not only protect bacteria from antibiotic therapies and immune clearance, but also increase the dissemination of pathogens from the initial sites of infection. Antibiotics are hard and insufficient to treat such hidden intracellular bacteria, especially the multidrug</a>-resistant (MDR) bacteria. Herein, aggregation-induced emission luminogens (AIEgens) such as TBPs showed potent broad-spectrum bactericidal activity against both <a></a><a>extracellular and intracellular</a> Gram-positive pathogens at low-dose levels. TBPs triggered reactive oxygen species (ROS)-mediated membrane damage to kill bacteria, regardless of light irradiation. Additionally, such AIEgens activated mitochondria dependent autophagy to eliminate intracellular bacteria in host cells. Compared to the routinely used vancomycin in clinics, TBPs showed comparable efficacy against methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) <i>in vivo</i>. Our studies demonstrate that AIEgens are promising new agents for the treatment of MDR bacteria associated infections.</p>

scholarly journals An endometrial organoid model of Chlamydia-epithelial and immune cell interactions

2020 ◽  
Author(s):  
Lee Dolat ◽  
Raphael H. Valdivia
Keyword(s):  
Epithelial Cell ◽  
Cell Biology ◽  
Immune Cell ◽  
Three Dimensional ◽  
Time Lapse ◽  
Cell Types ◽  
Infection Process ◽  
Host Cells ◽  
Cell Diversity ◽  
Intracellular Organelles

ABSTRACTOur understanding of how the obligate intracellular bacterium Chlamydia trachomatis reprograms the cell biology of host cells in the upper genital tract is largely based on observations made in cell culture with transformed epithelial cell lines. Here we describe a primary spherical organoid system derived from endometrial tissue to recapitulate epithelial cell diversity, polarity, and ensuing responses to Chlamydia infection. Using high-resolution and time-lapse microscopy, we catalogue the infection process in organoids from invasion to egress, including the reorganization of the cytoskeleton and positioning of intracellular organelles. We show this model is amenable to screening C. trachomatis mutants for defects in the fusion of pathogenic vacuoles, the recruitment of intracellular organelles, and inhibition of cell death. Moreover, we reconstructed a primary immune cell response by co-culturing infected organoids with neutrophils, and determined that the effector TepP limits the recruitment of neutrophils to infected organoids. Collectively, our model details a system to study the cell biology of Chlamydia infections in three dimensional structures that better reflect the diversity of cell types and polarity encountered by Chlamydia upon infection of their animal hosts.Summary statement3D endometrial organoids to model Chlamydia infection and the role of secreted virulence factors in reprogramming host epithelial cells and immune cell recruitment

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