Research Article

M1 Protein Allows Group A Streptococcal Survival in Phagocyte Extracellular Traps through Cathelicidin Inhibition
Xavier Lauth^{a, f}, Maren von Köckritz-Blickwede^a, Case W. McNamara^b, Sandra Myskowski^a, Annelies S. Zinkernagel^a, Bernard Beall^e, Partho Ghosh^b, Richard L. Gallo^{a, c, f}, Victor Nizet^{a, d, g}

Departments of
^aPediatrics,
^bChemistry and Biochemistry, and
^cMedicine, and
^dSkaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, Calif.,
^eRespiratory Diseases Branch, Division of Bacterial Diseases, Centers for Disease Control and Prevention, Atlanta, Ga.,
^fVeterans Affairs San Diego Healthcare Center and
^gRady Children's Hospital, San Diego, Calif., USA

Address of Corresponding Author

J Innate Immun 2009;1:202-214 (DOI: 10.1159/000203645)

  Key Words

• Group A Streptococcus
• Streptococcus pyogenes
• Virulence factor
• Innate immunity
• M protein
• Neutrophil
• Mast cell
• Extracellular traps
• Antimicrobial peptide
• Cathelicidin

  Abstract

M1 protein contributes to Group A Streptococcus (GAS) systemic virulence by interfering with phagocytosis and through proinflammatory activities when released from the cell surface. Here we identify a novel role of M1 protein in the stimulation of neutrophil and mast cell extracellular trap formation, yet also subsequent survival of the pathogen within these DNA-based innate defense structures. Targeted mutagenesis and heterologous expression studies demonstrate M1 protein promotes resistance to the human cathelicidin antimicrobial peptide LL-37, an important effector of bacterial killing within such phagocyte extracellular traps. Studies with purified recombinant protein fragments mapped the inhibition of cathelicidin killing to the M1 hypervariable N-terminal domain. A survey of GAS clinical isolates found that strains from patients with necrotizing fasciitis or toxic shock syndrome were significantly more likely to be resistant to cathelicidin than GAS M types not associated with invasive disease; M1 isolates were uniformly resistant. We conclude increased resistance to host cathelicidin and killing within phagocyte extracellular traps contribute to the propensity of M1 GAS strains to produce invasive infections.

Copyright © 2009 S. Karger AG, Basel

  Author Contacts

Prof. Victor Nizet
Department of Pediatrics and Skaggs School of Pharmacy
and Pharmaceutical Sciences, University of California
9500 Gilman Drive, MC 0687, La Jolla, CA 92093-0687 (USA)
Tel. +1 858 534 7408, Fax +1 858 534 5611, E-Mail vnizet@ucsd.edu

  Article Information

X.L. and M.v.K.-B. contributed equally to this manuscript.

Received: November 27, 2008
Accepted after revision: December 15, 2008
Published online: February 20, 2009
Number of Print Pages : 13
Number of Figures : 5, Number of Tables : 0, Number of References : 54
Additional supplemental material is available online.