Dual Toxic-Peptide-Coding Staphylococcus aureus RNA under Antisense Regulation Targets Host Cells and Bacterial Rivals Unequally

Staphylococcus aureus is a species of Gram-positive staphylococcus. It can cause sinusitis, respiratory infections, skin infections, and food poisoning. Recently, it was discovered that S. aureus infects epithelial cells, but the interaction between S. aureus and the host is not well known. In this study, we confirmed S. aureus to be internalized by HaCaT cells using the ESAT-6-like protein EsxB and amplified within the host over time by escaping host immunity. S. aureus increases the expression of decay-accelerating factor (CD55) on the surfaces of host cells, which inhibits the activation of the complement system. This mechanism makes it possible for S. aureus to survive in host cells. S. aureus, sufficiently amplified within the host, is released through the initiation of cell death. On the other hand, the infected host cells increase their surface expression of UL16 binding protein 1 to inform immune cells that they are infected and try to be eliminated. These host defense systems seem to involve the alteration of tight junctions and the induction of ligand expression to activate immune cells. Taken together, our study elucidates a novel aspect of the mechanisms of infection and immune system evasion for S. aureus.

Download Full-text

A genomic and proteomic analysis of surface proteins in bovine-adapted lineages of Staphylococcus aureus

Access Microbiology ◽

10.1099/acmi.ac2020.po0394 ◽

2020 ◽

Vol 2 (7A) ◽

Author(s):

Shauna D. Drumm ◽

Rebecca Owens ◽

Jennifer Mitchell ◽

Orla M. Keane

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Surface Proteins ◽

Host Cells ◽

Mass Spectrometry Analysis ◽

In Vitro Assays ◽

Immune Recognition ◽

Independent Manner ◽

Genes Encoding

In Ireland, Staphylococcus aureus is the most common cause of intramammary infection (IMI) in cattle with the bovine-adapted lineages CC151 and CC97 most commonly found. Surface proteins play a major role in establishing and maintaining the infection. A previous study revealed that a strain from the CC151 lineage showed significant decay in genes encoding predicted surface proteins. Twenty-three S. aureus strains, twelve belonging to CC151 and eleven belonging to CC97, isolated from clinical IMI, were sequenced and genes encoding cell wall anchored (CWA) proteins predicted. Analysis showed that a minority of genes encoding putative CWA proteins were intact in the CC151 strains compared to CC97. Of the 26 known CWA proteins in S. aureus, the CC151 strains only encoded 10 intact genes while CC97 encoded on average 18 genes. Also within the CC97 lineage, the repertoire of genes varied depending on individual strains, with strains encoding between 17-20 intact genes. Although CC151 is reported to internalize within bovine host cells, it does so in a fibronectin-binding protein (FnBPA and FnBPB) independent manner. In-vitro assays were performed and results showed that strains from CC151, and surprisingly also CC97, weakly bound bovine fibronectin and that the FnBPs were poorly expressed in both these lineages. Mass spectrometry analysis of cell wall extracts revealed that SdrE and AdsA were the most highly expressed CWA proteins in both lineages. These results demonstrate significant differences between CC151 and CC97 in their repertoire of genes encoding CWA proteins, which may impact immune recognition of these strains and their interactions with host cells.

Download Full-text

ROS-Sensitive Micelles for Controlled Delivery of Antibiotics to Combat Intracellular Staphylococcus aureus-Associated Infections

Journal of Materials Chemistry B ◽

10.1039/d1tb01702k ◽

2021 ◽

Author(s):

Jing Qiao ◽

Shuolin Cui ◽

May Xiong

Keyword(s):

Staphylococcus Aureus ◽

Immune System ◽

Controlled Delivery ◽

Host Cells ◽

Bactericidal Action

Bacteria can evade the immune system once they are engulfed by phagocytic host cells. This protects them against the bactericidal action of antibiotics and allows the infection to remain latent...

Download Full-text

Orchestration of human macrophage NLRP3 inflammasome activation by Staphylococcus aureus extracellular vesicles

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1915829117 ◽

2020 ◽

Vol 117 (6) ◽

pp. 3174-3184 ◽

Cited By ~ 10

Author(s):

Xiaogang Wang ◽

William J. Eagen ◽

Jean C. Lee

Keyword(s):

Staphylococcus Aureus ◽

Extracellular Vesicles ◽

Biological Effects ◽

Endocytic Pathway ◽

Host Cells ◽

Human Macrophage ◽

Inflammasome Activation ◽

Human Macrophages ◽

Caspase 1 ◽

Tlr2 Signaling

Release of extracellular vesicles (EVs) is a common feature among eukaryotes, archaea, and bacteria. However, the biogenesis and downstream biological effects of EVs released from gram-positive bacteria remain poorly characterized. Here, we report that EVs purified from a community-associated methicillin-resistant Staphylococcus aureus strain were internalized into human macrophages in vitro and that this process was blocked by inhibition of the dynamin-dependent endocytic pathway. Human macrophages responded to S. aureus EVs by TLR2 signaling and activation of NLRP3 inflammasomes through K+ efflux, leading to the recruitment of ASC and activation of caspase-1. Cleavage of pro–interleukin (IL)-1β, pro-IL-18, and gasdermin-D by activated caspase-1 resulted in the cellular release of the mature cytokines IL-1β and IL-18 and induction of pyroptosis. Consistent with this result, a dose-dependent cytokine response was detected in the extracellular fluids of mice challenged intraperitoneally with S. aureus EVs. Pore-forming toxins associated with S. aureus EVs were critical for NLRP3-dependent caspase-1 activation of human macrophages, but not for TLR2 signaling. In contrast, EV-associated lipoproteins not only mediated TLR2 signaling to initiate the priming step of NLRP3 activation but also modulated EV biogenesis and the toxin content of EVs, resulting in alterations in IL-1β, IL-18, and caspase-1 activity. Collectively, our study describes mechanisms by which S. aureus EVs induce inflammasome activation and reveals an unexpected role of staphylococcal lipoproteins in EV biogenesis. EVs may serve as a novel secretory pathway for S. aureus to transport protected cargo in a concentrated form to host cells during infections to modulate cellular functions.

Download Full-text

Transketolase of Staphylococcus aureus in the Control of Master Regulators of Stress Response During Infection

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz404 ◽

2019 ◽

Vol 220 (12) ◽

pp. 1967-1976

Author(s):

Xin Tan ◽

Elodie Ramond ◽

Anne Jamet ◽

Jean-Philippe Barnier ◽

Baptiste Decaux-Tramoni ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Time Lapse ◽

Pentose Phosphate ◽

Host Cells ◽

Chronic Infections ◽

Gene Encoding ◽

Master Regulators ◽

Sigma B ◽

Intracellular Proliferation ◽

Major Defect

Abstract Staphylococcus aureus is a leading cause of both acute and chronic infections in humans. The importance of the pentose phosphate pathway (PPP) during S. aureus infection is currently largely unexplored. In the current study, we focused on one key PPP enzyme, transketolase (TKT). We showed that inactivation of the unique gene encoding TKT activity in S. aureus USA300 (∆tkt) led to drastic metabolomic changes. Using time-lapse video imaging and mice infection, we observed a major defect of the ∆tkt strain compared with wild-type strain in early intracellular proliferation and in the ability to colonize kidneys. Transcriptional activity of the 2 master regulators sigma B and RpiRc was drastically reduced in the ∆tkt mutant during host cells invasion. The concomitant increased RNAIII transcription suggests that TKT—or a functional PPP—strongly influences the ability of S. aureus to proliferate within host cells by modulating key transcriptional regulators.

Download Full-text

Unstable chromosome rearrangements in Staphylococcus aureus cause phenotype switching associated with persistent infections

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1904861116 ◽

2019 ◽

Vol 116 (40) ◽

pp. 20135-20140 ◽

Cited By ~ 17

Author(s):

Romain Guérillot ◽

Xenia Kostoulias ◽

Liam Donovan ◽

Lucy Li ◽

Glen P. Carter ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Genetic Basis ◽

Host Cells ◽

Type I ◽

Modification System ◽

Persistent Infections ◽

Restriction Modification System ◽

Long Read ◽

Small Colony ◽

Restriction Modification

Staphylococcus aureus small-colony variants (SCVs) are associated with unusually chronic and persistent infections despite active antibiotic treatment. The molecular basis for this clinically important phenomenon is poorly understood, hampered by the instability of the SCV phenotype. Here we investigated the genetic basis for an unstable S. aureus SCV that arose spontaneously while studying rifampicin resistance. This SCV showed no nucleotide differences across its genome compared with a normal-colony variant (NCV) revertant, yet the SCV presented the hallmarks of S. aureus linked to persistent infection: down-regulation of virulence genes and reduced hemolysis and neutrophil chemotaxis, while exhibiting increased survival in blood and ability to invade host cells. Further genome analysis revealed chromosome structural variation uniquely associated with the SCV. These variations included an asymmetric inversion across half of the S. aureus chromosome via recombination between type I restriction modification system (T1RMS) genes, and the activation of a conserved prophage harboring the immune evasion cluster (IEC). Phenotypic reversion to the wild-type–like NCV state correlated with reversal of the chromosomal inversion (CI) and with prophage stabilization. Further analysis of 29 complete S. aureus genomes showed strong signatures of recombination between hsdMS genes, suggesting that analogous CI has repeatedly occurred during S. aureus evolution. Using qPCR and long-read amplicon deep sequencing, we detected subpopulations with T1RMS rearrangements causing CIs and prophage activation across major S. aureus lineages. Here, we have discovered a previously unrecognized and widespread mechanism of reversible genomic instability in S. aureus associated with SCV generation and persistent infections.

Download Full-text

Staphylococcus aureus secretes immunomodulatory RNA and DNA via membrane vesicles

Scientific Reports ◽

10.1038/s41598-020-75108-3 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Blanca V. Rodriguez ◽

Meta J. Kuehn

Keyword(s):

Staphylococcus Aureus ◽

Nucleic Acids ◽

Immune Modulation ◽

Membrane Vesicle ◽

Membrane Vesicles ◽

Receptor Activation ◽

Host Cells ◽

Downstream Signaling ◽

Host Immune Responses ◽

Rna And Dna

Abstract Bacterial-derived RNA and DNA can function as ligands for intracellular receptor activation and induce downstream signaling to modulate the host response to bacterial infection. The mechanisms underlying the secretion of immunomodulatory RNA and DNA by pathogens such as Staphylococcus aureus and their delivery to intracellular host cell receptors are not well understood. Recently, extracellular membrane vesicle (MV) production has been proposed as a general secretion mechanism that could facilitate the delivery of functional bacterial nucleic acids into host cells. S. aureus produce membrane-bound, spherical, nano-sized, MVs packaged with a select array of bioactive macromolecules and they have been shown to play important roles in bacterial virulence and in immune modulation through the transmission of biologic signals to host cells. Here we show that S. aureus secretes RNA and DNA molecules that are mostly protected from degradation by their association with MVs. Importantly, we demonstrate that MVs can be delivered into cultured macrophage cells and subsequently stimulate a potent IFN-β response in recipient cells via activation of endosomal Toll-like receptors. These findings advance our understanding of the mechanisms by which bacterial nucleic acids traffic extracellularly to trigger the modulation of host immune responses.

Download Full-text

Interaction of Staphylococcus aureus and Host Cells upon Infection of Bronchial Epithelium during Different Stages of Regeneration

ACS Infectious Diseases ◽

10.1021/acsinfecdis.0c00403 ◽

2020 ◽

Vol 6 (8) ◽

pp. 2279-2290 ◽

Cited By ~ 1

Author(s):

Laura M. Palma Medina ◽

Ann-Kristin Becker ◽

Stephan Michalik ◽

Kristin Surmann ◽

Petra Hildebrandt ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Bronchial Epithelium ◽

Host Cells

Download Full-text

Competitive adherence as a mechanism of bacterial interference

Canadian Journal of Microbiology ◽

10.1139/m83-114 ◽

1983 ◽

Vol 29 (6) ◽

pp. 700-703 ◽

Cited By ~ 60

Author(s):

Debra Jan Bibel ◽

Raza Aly ◽

Charlene Bayles ◽

Walter G. Strauss ◽

Henry R. Shinefield ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Host Cell ◽

Virulent Strain ◽

Host Cells ◽

Aureus Strain ◽

Attachment Sites ◽

Specific Attachment ◽

Mucosal Cells ◽

Bacterial Interference

To determine whether competition among bacteria for specific attachment sites on host cells can explain bacterial interference, Staphylococcus aureus strain 502A was tested in turn against two different nasal coryneforms, a strain of Pseudomonas aeruginosa, and a virulent strain of S. aureus, all in the presence of nasal mucosal cells. Particularly examined was the influence of sequence in which bacteria were presented to the nasal cells in comparison with initial mixtures and individual suspensions. Results paralleled those observed in clinical prophylaxis: the bacterium first to adhere to the epithelial cells was able, under uniform conditions, to interfere with the colonization of subsequently added bacteria. Secondary adherence was not eliminated but substantially reduced, and was probably related to steric blockage by the initial colonizer and its particular ability to dissociate from the host cell.

Download Full-text