Sphingomyelin Depletion from Plasma Membranes of Human Airway Epithelial Cells Completely Abrogates the Deleterious Actions of S. aureus Alpha-Toxin

• Published in: Toxins 2019-02, Vol.11 (2), p.126
• Main Authors: Ziesemer, Sabine, Möller, Nils, Nitsch, Andreas, Müller, Christian, Beule, Achim G, Hildebrandt, Jan-Peter
• Format: Article
• Language: English
• Subjects: Actin; airway epithelial cells; alpha-toxin; ATP-Binding Cassette Transporters - genetics; Bacteria; Bacterial Toxins - genetics; Bacterial Toxins - toxicity; Calcium; Calcium (intracellular); Calcium ions; Cell Line; Cell Membrane - metabolism; Cell membranes; cell physiology; Cell size; Cofilin; Depletion; Depolymerization; Domains; Epithelial cells; Epithelial Cells - drug effects; Epithelial Cells - metabolism; Epithelium; Hemolysin Proteins - genetics; Hemolysin Proteins - toxicity; Humans; Kinases; Lipids; Membranes; Monomers; Oligomerization; Phosphorylation; Plasma; Plasma membranes; Pneumonia; Pore formation; Pores; Respiratory System - cytology; Respiratory tract; Sphingomyelin; Sphingomyelin phosphodiesterase; Sphingomyelins - deficiency; Staphylococcus aureus; Tightness; Toxins; Virulence; α-Toxin
• ISSN: 2072-6651; 2072-6651
• DOI: 10.3390/toxins11020126

Interaction of alpha-toxin (hemolysin A, Hla) with eukaryotic cell membranes is mediated by proteinaceous receptors and certain lipid domains in host cell plasma membranes. Hla is secreted as a 33 kDa monomer that forms heptameric transmembrane pores whose action compromises maintenance of cell shape and epithelial tightness. It is not exactly known whether certain membrane lipid domains of host cells facilitate adhesion of Ha monomers, oligomerization, or pore formation. We used sphingomyelinase (hemolysin B, Hlb) expressed by some strains of staphylococci to pre-treat airway epithelial model cells in order to specifically decrease the sphingomyelin (SM) abundance in their plasma membranes. Such a pre-incubation exclusively removed SM from the plasma membrane lipid fraction. It abrogated the formation of heptamers and prevented the formation of functional transmembrane pores. Hla exposure of rHlb pre-treated cells did not result in increases in [Ca ] , did not induce any microscopically visible changes in cell shape or formation of paracellular gaps, and did not induce hypo-phosphorylation of the actin depolymerizing factor cofilin as usual. Removal of sphingomyelin from the plasma membranes of human airway epithelial cells completely abrogates the deleterious actions of alpha-toxin.