[PDF][PDF] DNase expression allows the pathogen group A Streptococcus to escape killing in neutrophil extracellular traps

JT Buchanan, AJ Simpson, RK Aziz, GY Liu… - Current Biology, 2006 - cell.com
JT Buchanan, AJ Simpson, RK Aziz, GY Liu, SA Kristian, M Kotb, J Feramisco, V Nizet
Current Biology, 2006cell.com
The innate immune response plays a crucial role in satisfactory host resolution of bacterial
infection. In response to chemotactic signals, neutrophils are early responding cells that
migrate in large numbers to sites of infection. The recent discovery of secreted neutrophil
extracellular traps (NETs) composed of DNA and histones opened a novel dimension in our
understanding of the microbial killing capacity of these specialized leukocytes. M1 serotype
strains of the pathogen Group A Streptococcus (GAS) are associated with invasive infections …
Summary
The innate immune response plays a crucial role in satisfactory host resolution of bacterial infection. In response to chemotactic signals, neutrophils are early responding cells that migrate in large numbers to sites of infection. The recent discovery of secreted neutrophil extracellular traps (NETs) composed of DNA and histones opened a novel dimension in our understanding of the microbial killing capacity of these specialized leukocytes. M1 serotype strains of the pathogen Group A Streptococcus (GAS) are associated with invasive infections including necrotizing fasciitis (NF) and express a potent DNase (Sda1). Here we apply a molecular genetic approach of allelic replacement mutagenesis, single gene complementation, and heterologous expression to demonstrate that DNase Sda1 is both necessary and sufficient to promote GAS neutrophil resistance and virulence in a murine model of NF. Live fluorescent microscopic cell imaging and histopathological analysis are used to establish for the first time a direct linkage between NET degradation and bacterial pathogenicity. Inhibition of GAS DNase activity with G-actin enhanced neutrophil clearance of the pathogen in vitro and reduced virulence in vivo. The results demonstrate a significant role for NETs in neutrophil-mediated innate immunity, and at the same time identify a novel therapeutic target against invasive GAS infection.
cell.com