EssE Promotes Staphylococcus aureus ESS-Dependent Protein Secretion To Modify Host Immune Responses during Infection

ABSTRACT Staphylococcus aureus, an invasive pathogen of humans and animals, requires a specialized ESS pathway to secrete proteins (EsxA, EsxB, EsxC, and EsxD) during infection. Expression of ess genes is required for S. aureus establishment of persistent abscess lesions following bloodstream infection; however, the mechanisms whereby effectors of the ESS pathway implement their virulence strategies were heretofore not known. Here, we show that EssE forms a complex with other members of the ESS secretion pathway and its substrates, promoting the secretion of EsxA, EsxB, EsxC, EsxD, and EssD. During bloodstream infection of mice, the S. aureus essE mutant displays defects in host cytokine responses, specifically in the production of interleukin-12 (IL-12) (p40/p70) and the suppression of RANTES (CCL5), activators of TH1 T cell responses and immune cell chemotaxis, respectively. Thus, essE-mediated secretion of protein effectors via the ESS pathway may enable S. aureus to manipulate host immune responses by modifying the production of cytokines. IMPORTANCE Staphylococcus aureus and other firmicutes evolved a specialized ESS (EsxA/ESAT-6-like secretion system) pathway for the secretion of small subsets of proteins lacking canonical signal peptides. The molecular mechanisms for ESS-dependent secretion and their functional purpose are still unknown. We demonstrate here that S. aureus EssE functions as a membrane assembly platform for elements of the secretion machinery and their substrates. Furthermore, S. aureus EssE-mediated secretion contributes to the production or the suppression of specific cytokines during host infection, thereby modifying immune responses toward this pathogen.

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Vaccine Protection of Leukopenic Mice against Staphylococcus aureus Bloodstream Infection

Infection and Immunity ◽

10.1128/iai.02328-14 ◽

2014 ◽

Vol 82 (11) ◽

pp. 4889-4898 ◽

Cited By ~ 16

Author(s):

Sabine Rauch ◽

Portia Gough ◽

Hwan Keun Kim ◽

Olaf Schneewind ◽

Dominique Missiakas

Keyword(s):

Staphylococcus Aureus ◽

Bloodstream Infection ◽

Immune Cell ◽

Hematologic Malignancy ◽

Surface Proteins ◽

Sortase A ◽

Antibiotic Resistant ◽

Content Type ◽

Time To Death ◽

Von Willebrand

ABSTRACTThe risk forStaphylococcus aureusbloodstream infection (BSI) is increased in immunocompromised individuals, including patients with hematologic malignancy and/or chemotherapy. Due to the emergence of antibiotic-resistant strains, designated methicillin-resistantS. aureus(MRSA), staphylococcal BSI in cancer patients is associated with high mortality; however, neither a protective vaccine nor pathogen-specific immunotherapy is currently available. Here, we modeled staphylococcal BSI in leukopenic CD-1 mice that had been treated with cyclophosphamide, a drug for leukemia and lymphoma patients. Cyclophosphamide-treated mice were highly sensitive toS. aureusBSI and developed infectious lesions lacking immune cell infiltrates. Virulence factors ofS. aureusthat are key for disease establishment in immunocompetent hosts—α-hemolysin (Hla), iron-regulated surface determinants (IsdA and IsdB), coagulase (Coa), and von Willebrand factor binding protein (vWbp)—are dispensable for the pathogenesis of BSI in leukopenic mice. In contrast, sortase A mutants, which cannot assemble surface proteins, display delayed time to death and increased survival in this model. A vaccine with four surface antigens (ClfA, FnBPB, SdrD, and SpAKKAA), which was identified by genetic vaccinology using sortase A mutants, raised antigen-specific immune responses that protected leukopenic mice against staphylococcal BSI.

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Innate Immunity Modulating Impurities and the Immunotoxicity of Nanobiotechnology-Based Drug Products

Molecules ◽

10.3390/molecules26237308 ◽

2021 ◽

Vol 26 (23) ◽

pp. 7308

Author(s):

Claire K. Holley ◽

Marina A. Dobrovolskaia

Keyword(s):

Innate Immunity ◽

Immune Responses ◽

Cell Activation ◽

Molecular Mechanisms ◽

Immune Cell ◽

Pharmaceutical Products ◽

Drug Effectiveness ◽

Host Immune Responses ◽

Drug Products ◽

The Many

Innate immunity can be triggered by the presence of microbial antigens and other contaminants inadvertently introduced during the manufacture and purification of bionanopharmaceutical products. Activation of these innate immune responses, including cytokine secretion, complement, and immune cell activation, can result in unexpected and undesirable host immune responses. These innate modulators can also potentially stimulate the activation of adaptive immune responses, including the formation of anti-drug antibodies which can impact drug effectiveness. To prevent induction of these adverse responses, it is important to detect and quantify levels of these innate immunity modulating impurities (IIMIs) that may be present in drug products. However, while it is universally agreed that removal of IIMIs from drug products is crucial for patient safety and to prevent long-term immunogenicity, there is no single assay capable of directly detecting all potential IIMIs or indirectly quantifying downstream biomarkers. Additionally, there is a lack of agreement as to which of the many analytical assays currently employed should be standardized for general IIMI screening. Herein, we review the available literature to highlight cellular and molecular mechanisms underlying IIMI-mediated inflammation and its relevance to the safety and efficacy of pharmaceutical products. We further discuss methodologies used for direct and indirect IIMI identification and quantification.

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EssD, a Nuclease Effector of the Staphylococcus aureus ESS Pathway

Journal of Bacteriology ◽

10.1128/jb.00528-16 ◽

2016 ◽

Vol 199 (1) ◽

Cited By ~ 21

Author(s):

Ryan Jay Ohr ◽

Mark Anderson ◽

Miaomiao Shi ◽

Olaf Schneewind ◽

Dominique Missiakas

Keyword(s):

Staphylococcus Aureus ◽

Molecular Mechanisms ◽

Nuclease Activity ◽

Selective Advantage ◽

Staphylococcal Infection ◽

Interleukin 12 ◽

Secretion Systems ◽

Knockout Mutant ◽

Content Type ◽

Mrsa Infection

ABSTRACT Specialized secretion systems of bacteria evolved for selective advantage, either killing microbial competitors or implementing effector functions during parasitism. Earlier work characterized the ESAT-6 secretion system (ESS) of Staphylococcus aureus and demonstrated its contribution to persistent staphylococcal infection of vertebrate hosts. Here, we identify a novel secreted effector of the ESS pathway, EssD, that functions as a nuclease and cleaves DNA but not RNA. EssI, a protein of the DUF600 family, binds EssD to block its nuclease activity in the staphylococcal cytoplasm. An essD knockout mutant or a variant lacking nuclease activity, essD L546P, elicited a diminished interleukin-12 (IL-12) cytokine response following bloodstream infection of mice, suggesting that the effector function of EssD stimulates immune signaling to support the pathogenesis of S. aureus infections. IMPORTANCE Bacterial type VII or ESAT-6-like secretion systems (ESS) may have evolved to modulate host immune responses during infection, thereby contributing to the pathogenesis of important diseases such as tuberculosis and methicillin-resistant S. aureus (MRSA) infection. The molecular mechanisms whereby type VII secretion systems achieve their goals are not fully elucidated as secreted effectors with biochemical functions have heretofore not been identified. We show here that MRSA infection relies on the secretion of a nuclease effector that cleaves DNA and contributes to the stimulation of IL-12 signaling during infection. These results identify a biological mechanism for the contribution of the ESS pathway toward the establishment of MRSA disease.

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Suppression of Staphylococcus aureus Superantigen-Independent Interferon Gamma Response by a Probiotic Polysaccharide

Infection and Immunity ◽

10.1128/iai.00661-19 ◽

2020 ◽

Vol 88 (4) ◽

Author(s):

Wonbeom Paik ◽

Francis Alonzo ◽

Katherine L. Knight

Keyword(s):

Staphylococcus Aureus ◽

Bloodstream Infection ◽

Interferon Gamma ◽

T Cell Activation ◽

Cell Activation ◽

Nk Cell ◽

Interleukin 12 ◽

Dependent Manner ◽

Content Type ◽

Ifn Γ

ABSTRACT Staphylococcus aureus is a Gram-positive opportunistic pathogen that causes a variety of diseases. Bloodstream infection is the most severe, with mortality rates reaching 20 to 50%. Exopolysaccharide (EPS) from the probiotic Bacillus subtilis reduces bacterial burden and inflammation during S. aureus bloodstream infection in mice. Protection is due, in part, to hybrid macrophages that restrict S. aureus growth through reactive oxygen species and to limiting superantigen-induced T cell activation and interferon gamma (IFN-γ) production during infection. A decrease in IFN-γ production was observed within 24 h after infection, and here, we investigated how EPS abrogates its production. We discovered that S. aureus uses a rapid, superantigen-independent mechanism to induce host IFN-γ and that this is mediated by interleukin-12 (IL-12) activation of NK cells. Furthermore, we found that EPS limits IFN-γ production by modulating host immunity in a Toll-like receptor 4 (TLR4)-dependent manner, a signaling pathway that is required for EPS-mediated protection from S. aureus infection in vivo. We conclude that EPS protects hosts from acute bloodstream S. aureus infection not only by inducing macrophages that restrict S. aureus growth and inhibit superantigen-activated T cells but also by limiting NK cell production of IFN-γ after S. aureus infection in a TLR4-dependent manner.

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During the Early Stages of Staphylococcus aureus Biofilm Formation, Induced Neutrophil Extracellular Traps Are Degraded by Autologous Thermonuclease

Infection and Immunity ◽

10.1128/iai.00605-19 ◽

2019 ◽

Vol 87 (12) ◽

Cited By ~ 1

Author(s):

Andi R. Sultan ◽

Tamara Hoppenbrouwers ◽

Nicole A. Lemmens-den Toom ◽

Susan V. Snijders ◽

Johan W. van Neck ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Immune Responses ◽

Structural Stability ◽

Biofilm Formation ◽

Bacterial Colonization ◽

Extracellular Dna ◽

Content Type ◽

Host Immune Responses ◽

Early Stages ◽

Biofilm Development

ABSTRACT Staphylococcus aureus extracellular DNA (eDNA) plays a crucial role in the structural stability of biofilms during bacterial colonization; on the contrary, host immune responses can be induced by bacterial eDNA. Previously, we observed production of S. aureus thermonuclease during the early stages of biofilm formation in a mammalian cell culture medium. Using a fluorescence resonance energy transfer (FRET)-based assay, we detected thermonuclease activity of S. aureus biofilms grown in Iscove’s modified Dulbecco’s medium (IMDM) earlier than that of widely studied biofilms grown in tryptic soy broth (TSB). The thermonuclease found was Nuc1, confirmed by mass spectrometry and competitive Luminex assay. These results indicate that biofilm development in IMDM may not rely on eDNA for structural stability. A bacterial viability assay in combination with wheat germ agglutinin (WGA) staining confirmed the accumulation of dead cells and eDNA in biofilms grown in TSB. However, in biofilms grown in IMDM, minimal amounts of eDNA were found; instead, polysaccharide intercellular adhesin (PIA) was detected. To investigate if this early production of thermonuclease plays a role in immune modulation by biofilm, we studied the effect of thermonuclease on human neutrophil extracellular trap (NET) formation using a nuc knockout and complemented strain. We confirmed that thermonuclease produced by early-stage biofilms grown in IMDM degraded biofilm-induced NETs. Additionally, neither the presence of biofilms nor thermonuclease stimulated an increase in reactive oxygen species (ROS) production by neutrophils. Our findings indicated that S. aureus, during the early stages of biofilm formation, actively evades the host immune responses by producing thermonuclease.

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Clearance of Staphylococcus aureus Nasal Carriage Is T Cell Dependent and Mediated through Interleukin-17A Expression and Neutrophil Influx

Infection and Immunity ◽

10.1128/iai.00084-13 ◽

2013 ◽

Vol 81 (6) ◽

pp. 2070-2075 ◽

Cited By ~ 63

Author(s):

Nathan K. Archer ◽

Janette M. Harro ◽

Mark E. Shirtliff

Keyword(s):

Staphylococcus Aureus ◽

Immune Response ◽

T Cell ◽

Immune Responses ◽

Neutrophil Migration ◽

Nasal Carriage ◽

Causal Connection ◽

Content Type ◽

Neutrophil Influx ◽

Increased Risk

ABSTRACTThe anterior nares of humans are the major reservoir forStaphylococcus aureuscolonization. Approximately 20% of the healthy human population is persistently and 80% is intermittently colonized withS. aureusin the nasal cavity. Previous studies have shown a strong causal connection betweenS. aureusnasal carriage and increased risk of nosocomial infection, as well as increased carriage due to immune dysfunction. However, the immune responses that permit persistence or mediate clearance ofS. aureuson the nasal mucosa are fundamentally undefined. In this study, we developed a carriage model in C57BL/6J mice and showed that clearance begins 14 days postinoculation. In contrast, SCID mice that have a deficient adaptive immune response are unable to eliminateS. aureuseven after 28 days postinoculation. Furthermore, decolonization was found to be T cell mediated but B cell independent by evaluating carriage clearance in T-cell receptor β/δ (TCR-β/δ) knockout (KO) and IgH-μ KO mice, respectively. Upregulation of the cytokines interleukin 1β (IL-1β), KC (also termed CXC ligand 1 [CXCL1]), and IL-17A occurred following inoculation with intranasalS. aureus. IL-17A production was crucial for clearance, since IL-17A-deficient mice were unable to effectively eliminateS. aureuscarriage. Subsequently, cell differential counts were evaluated from nasal lavage fluid obtained from wild-type and IL-17A-deficient colonized mice. These counts displayed IL-17A-dependent neutrophil migration. Antibody-mediated depletion of neutrophils in colonized mice caused reduced clearance compared to that in isotype-treated controls. Our data suggest that the Th17-associated immune response is required for nasal decolonization. This response is T cell dependent and mediated via IL-17A production and neutrophil influx. Th17-associated immune responses may be targeted for strategies to mitigate distal infections originating from persistentS. aureuscarriage in humans.

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641 Spatially organized multicellular immune hubs in MMRd and MMRp colorectal cancer

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.641 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A670-A670

Author(s):

Jonathan Chen ◽

Karin Pelka ◽

Matan Hofree ◽

Marios Giannakis ◽

Genevieve Boland ◽

...

Keyword(s):

Colorectal Cancer ◽

T Cells ◽

T Cell ◽

Immune Responses ◽

Mismatch Repair ◽

Molecular Mechanisms ◽

Immune Cell ◽

Single Cells ◽

Large Set ◽

Colon Tissue

BackgroundImmune responses to cancer are highly variable, with DNA mismatch repair-deficient (MMRd) tumors exhibiting more anti-tumor immunity than mismatch repair-proficient (MMRp) tumors. Almost all tumors are infiltrated with immune cells, but the types of immune responses and their effects on tumor growth, metastasis and death, vary greatly between different cancers and individual tumors. Which of the numerous cell subsets in a tumor contribute to the response, how their interactions are regulated, and how they are spatially organized within tumors remains poorly understood.MethodsTo understand the rules governing these varied responses, we transcriptionally profiled 371,223 single cells from colorectal tumors and adjacent normal tissues of 28 MMRp and 34 MMRd treatment-naive patients. We developed a systematic approach to discover cell types, their underlying gene programs, and cellular communities based on single cell RNA-seq (scRNAseq) profiles and applied it to study the distinguishing features of human MMRd and MMRp colorectal cancer. Cellular communities discovered from this analysis were spatially mapped in tissue sections using multiplex RNA in situ hybridization microscopy.ResultsTo understand the basis for differential immune responses in CRC, we first determined and compared the immune cell composition of MMRd and MMRp CRC and normal colon tissue, finding dramatic remodeling between tumor and normal tissue and between MMRd and MMRp tumors, particularly within the myeloid, T cell, and stromal compartments. Among the clusters enriched in MMRd tumors were activated CXCL13+ CD8 T cells. Importantly, gene program co-variation analysis revealed multicellular networks. We discovered a myeloid cell-attracting hub at the tumor-luminal interface associated with tissue damage, and an MMRd-enriched immune hub within the tumor, with activated IFNG+ and CXCL13+ T cells together with malignant and myeloid cells expressing T-cell-attracting chemokines (figure 1).ConclusionsOur study provides a rich dataset of cellular states, gene programs and their transformations in tumors across a relatively large cohort of patients with colorectal cancer. Our predictions of several multicellular hubs based on co-variation of gene expression programs, and subsequent spatial localization of two major immune-malignant hubs, organizes a large set of cell states and programs into a smaller number of coordinated networks of cells and processes. Understanding the molecular mechanisms underlying these hubs, and studying their temporal and spatial regulation upon treatment will be critical for advancing cancer therapy.Ethics ApprovalThis study was approved by the DF-HCC institutional review board (protocols 03-189 and 02-240).Abstract 641 Figure 1A coordinated network of CXCL13+ T cells with myeloid and malignant cells expressing ISGs. Image shows a portion of formalin-fixed paraffin-embedded tissue from an MMRd CRC specimen stained with multiplex RNA ISH / IF for PanCK-IF, CD3E-ISH, CXCL10/CXCL11-ISH, CXCL13-ISH, and IFNG-ISH. Note IFNG+ and CXCL13+ cells in proximity to cells expressing the chemokines CXCL10/CXCL11

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Tim-3 Induces Th2-Biased Immunity and Alternative Macrophage Activation during Schistosoma japonicum Infection

Infection and Immunity ◽

10.1128/iai.00517-15 ◽

2015 ◽

Vol 83 (8) ◽

pp. 3074-3082 ◽

Cited By ~ 7

Author(s):

Nan Hou ◽

Xianyu Piao ◽

Shuai Liu ◽

Chuang Wu ◽

Qijun Chen

Keyword(s):

Immune Response ◽

T Cells ◽

Schistosoma Japonicum ◽

Immune Cell ◽

Nk Cell ◽

Alternative Activation ◽

Interleukin 12 ◽

Content Type

T cell immunoglobulin- and mucin-domain-containing molecule 3 (Tim-3) has been regarded as an important regulatory factor in both adaptive and innate immunity. Recently, Tim-3 was reported to be involved in Th2-biased immune responses in mice infected withSchistosoma japonicum, but the exact mechanism behind the involvement of Tim-3 remains unknown. The present study aims to understand the role of Tim-3 in the immune response againstS. japonicuminfection. Tim-3 expression was determined by flow cytometry, and increased Tim-3 expression was observed on CD4+and CD8+T cells, NK1.1+cells, and CD11b+cells from the livers ofS. japonicum-infected mice. However, the increased level of Tim-3 was lower in the spleen than in the liver, and no increase in Tim-3 expression was observed on splenic CD8+T cells or CD11b+cells. The schistosome-induced upregulation of Tim-3 on natural killer (NK) cells was accompanied by reduced NK cell numbersin vitroandin vivo. Tim-3 antibody blockade led to upregulation of inducible nitric oxide synthase and interleukin-12 (IL-12) mRNA in CD11b+cells cocultured with soluble egg antigen and downregulation of Arg1 and IL-10, which are markers of M2 macrophages. In summary, we observed schistosome-induced expression of Tim-3 on critical immune cell populations, which may be involved in the Th2-biased immune response and alternative activation of macrophages during infection.

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Molecular Mechanisms of Host Immune Responses to Entamoeba

Molecular Food Microbiology ◽

10.1201/9781351120388-37 ◽

2021 ◽

pp. 461-477

Author(s):

Moisés Martínez-Castillo ◽

Jesús Serrano-Luna ◽

Daniel Coronado-Velázquez ◽

Judith Pacheco-Yépez ◽

Mireya de la Garza ◽

...

Keyword(s):

Immune Responses ◽

Molecular Mechanisms ◽

Host Immune Responses

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Immediate Interferon Gamma Induction Determines Murine Host Compatibility Differences between Toxoplasma gondii and Neospora caninum

Infection and Immunity ◽

10.1128/iai.00027-20 ◽

2020 ◽

Vol 88 (4) ◽

Cited By ~ 1

Author(s):

Rachel S. Coombs ◽

Matthew L. Blank ◽

Elizabeth D. English ◽

Yaw Adomako-Ankomah ◽

Ifeanyi-Chukwu Samuel Urama ◽

...

Keyword(s):

Toxoplasma Gondii ◽

Immune Responses ◽

Interferon Gamma ◽

Neospora Caninum ◽

Ectopic Expression ◽

Parasite Burden ◽

Interleukin 12 ◽

Content Type ◽

Ifn Γ ◽

And Control

ABSTRACT Rodents are critical for the transmission of Toxoplasma gondii to the definitive feline host via predation, and this relationship has been extensively studied as a model for immune responses to parasites. Neospora caninum is a closely related coccidian parasite of ruminants and canines but is not naturally transmitted by rodents. We compared mouse innate immune responses to N. caninum and T. gondii and found marked differences in cytokine levels and parasite growth kinetics during the first 24 h postinfection (hpi). N. caninum-infected mice produced significantly higher levels of interleukin-12 (IL-12) and interferon gamma (IFN-γ) by as early as 4 hpi, but the level of IFN-γ was significantly lower or undetectable in T. gondii-infected mice during the first 24 hpi. “Immediate” IFN-γ and IL-12p40 production was not detected in MyD88−/− mice. However, unlike IL-12p40−/− and IFN-γ−/− mice, MyD88−/− mice survived N. caninum infections at the dose used in this study. Serial measures of parasite burden showed that MyD88−/− mice were more susceptible to N. caninum infections than wild-type (WT) mice, and control of parasite burdens correlated with a pulse of serum IFN-γ at 3 to 4 days postinfection in the absence of detectable IL-12. Immediate IFN-γ was partially dependent on the T. gondii mouse profilin receptor Toll-like receptor 11 (TLR11), but the ectopic expression of N. caninum profilin in T. gondii had no impact on early IFN-γ production or parasite proliferation. Our data indicate that T. gondii is capable of evading host detection during the first hours after infection, while N. caninum is not, and this is likely due to the early MyD88-dependent recognition of ligands other than profilin.

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