Staphylococcal β-Toxin Modulates Human Aortic Endothelial Cell and Platelet Function through Sphingomyelinase and Biofilm Ligase Activities

Alfa Herrera; Katarina Kulhankova; Vijay K Sonkar; Sanjana Dayal; Aloysius J Klingelhutz; Wilmara Salgado-Pabón; Patrick M Schlievert

doi:10.1128/mBio.00273-17

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Staphylococcal β-Toxin Modulates Human Aortic Endothelial Cell and Platelet Function through Sphingomyelinase and Biofilm Ligase Activities

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Staphylococcal β-Toxin Modulates Human Aortic Endothelial Cell and Platelet Function through Sphingomyelinase and Biofilm Ligase Activities

Alfa Herrera, Katarina Kulhankova, Vijay K Sonkar, Sanjana Dayal, Aloysius J Klingelhutz, Wilmara Salgado-Pabón and Patrick M Schlievert

mBio, Vol.8(2), p.e00273-17

03/21/2017

DOI: 10.1128/mBio.00273-17

PMCID: PMC5362035

PMID: 28325766

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Abstract

causes many infections, such as skin and soft tissue, pneumonia, osteomyelitis, and infective endocarditis (IE). IE is an endovascular infection of native and prosthetic valves and the lining of the heart; it is characterized by the formation of cauliflower-like "vegetations" composed of fibrin, platelets, other host factors, bacteria, and bacterial products. β-Toxin is an virulence factor that contributes to the microorganism's ability to cause IE. This cytolysin has two enzymatic activities: sphingomyelinase (SMase) and biofilm ligase. Although both activities have functions in a rabbit model of IE, the mechanism(s) by which β-toxin directly affects human cells and is involved in the infectious process has not been elucidated. Here, we compared the effects of purified recombinant wild-type β-toxin, SMase-deficient β-toxin (H289N), and biofilm ligase-deficient β-toxin (H162A and/or D163A) on human aortic endothelial cells (HAECs) and platelets. β-Toxin was cytotoxic to HAECs and inhibited the production of interleukin 8 (IL-8) from these cells by both SMase and biofilm ligase activities. β-Toxin altered HAEC surface expression of CD40 and vascular cell adhesion molecule 1 (VCAM-1). HAECs treated with β-toxin displayed granular membrane morphology not seen in treatment with the SMase-deficient mutant. The altered morphology resulted in two possibly separable activities, cell rounding and redistribution of cell membranes into granules, which were not the result of endosome production from the Golgi apparatus or lysosomes. β-Toxin directly aggregated rabbit platelets via SMase activity. Each year there are up to 100,000 cases of infective endocarditis (IE) in the United States. is the most common pathogen in patients with health care-associated IE and the leading cause of community-associated IE in the developed world. Multiple clonal group strains as defined by the Centers for Disease Control and Prevention, particularly USA200 and other clones encoding β-toxin, are highly associated with IE. Considering the strong association and established contribution of β-toxin in animal models of IE, determining how β-toxin directly affects human cell types, including endothelial cells and platelets, is important. In this study, we demonstrate that β-toxin functions to modulate endothelial cells and platelets by both toxin sphingomyelinase and biofilm ligase activities. Our data suggest that these activities modulate inflammation and increase infection severity.

Endothelial Cells - chemistry

Recombinant Proteins - metabolism

CD40 Antigens - analysis

Cell Survival - drug effects

Sphingomyelin Phosphodiesterase - genetics

Hemolysin Proteins - genetics

Humans

Biofilms - growth & development

Cells, Cultured

Mutant Proteins - genetics

Ligases - metabolism

Mutant Proteins - metabolism

Cell Membrane - ultrastructure

Recombinant Proteins - genetics

Staphylococcus aureus - pathogenicity

Host-Pathogen Interactions

Bacterial Toxins - metabolism

Sphingomyelin Phosphodiesterase - metabolism

Bacterial Toxins - genetics

Blood Platelets - drug effects

Vascular Cell Adhesion Molecule-1 - analysis

Cell Membrane - drug effects

Hemolysin Proteins - metabolism

Endothelial Cells - drug effects

Details

Title: Subtitle: Staphylococcal β-Toxin Modulates Human Aortic Endothelial Cell and Platelet Function through Sphingomyelinase and Biofilm Ligase Activities
Creators: Alfa Herrera - Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
Katarina Kulhankova - Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
Vijay K Sonkar - Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
Sanjana Dayal - Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
Aloysius J Klingelhutz - Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
Wilmara Salgado-Pabón - Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
Patrick M Schlievert - Department of Microbiology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA Patrick-schlievert@uiowa.edu
Resource Type: Journal article
Publication Details: mBio, Vol.8(2), p.e00273-17
DOI: 10.1128/mBio.00273-17
PMID: 28325766
PMCID: PMC5362035
NLM abbreviation: mBio
ISSN: 2161-2129
eISSN: 2150-7511
Publisher: United States
Grant note: T32 AI007511 / NIAID NIH HHS R01 AI032135 / NIAID NIH HHS
Language: English
Date published: 03/21/2017
Academic Unit: Microbiology and Immunology; Stead Family Department of Pediatrics; Iowa Neuroscience Institute; Radiation Oncology; Internal Medicine
Record Identifier: 9984001148002771

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