Characterization of Early-Phase Neutrophil Extracellular Traps in Urinary Tract Infections

PLoS Pathogens

Keehwan Kwon¹  Shiferaw Bekele¹  Karen E. Nelson¹  Tamara Tsitrin¹  Patricia Sikorski¹  Rembert Pieper¹  Yanbao Yu¹ 

[1] The J. Craig Venter Institute, Rockville, MD, United States of America

关键词: Neutrophils;    Proteomes;    Histones;    Deoxyribonucleases;    DNA-binding proteins;    Staphylococcus aureus;    Chromatin;    Protein extraction;   

DOI  :  10.1371/journal.ppat.1006151

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Neutrophils have an important role in the antimicrobial defense and resolution of urinary tract infections (UTIs). Our research suggests that a mechanism known as neutrophil extracellular trap (NET) formation is a defense strategy to combat pathogens that have invaded the urinary tract. A set of human urine specimens with very high neutrophil counts had microscopic evidence of cellular aggregation and lysis. Deoxyribonuclease I (DNase) treatment resulted in disaggregation of such structures, release of DNA fragments and a proteome enriched in histones and azurophilic granule effectors whose quantitative composition was similar to that of previously described in vitro-formed NETs. The effector proteins were further enriched in DNA-protein complexes isolated in native PAGE gels. Immunofluorescence microscopy revealed a flattened morphology of neutrophils associated with decondensed chromatin, remnants of granules in the cell periphery, and myeloperoxidase co-localized with extracellular DNA, features consistent with early-phase NETs. Nuclear staining revealed that a considerable fraction of bacterial cells in these structures were dead. The proteomes of two pathogens, Staphylococcus aureus and Escherichia coli, were indicative of adaptive responses to early-phase NETs, specifically the release of virulence factors and arrest of ribosomal protein synthesis. Finally, we discovered patterns of proteolysis consistent with widespread cleavage of proteins by neutrophil elastase, proteinase 3 and cathepsin G and evidence of citrullination in many nuclear proteins.

【 授权许可】

CC BY