Neisseria gonorrhoeae delays the onset of apoptosis in polymorphonuclear leukocytes

Cell Microbiol. 2006 Nov;8(11):1780-90. doi: 10.1111/j.1462-5822.2006.00748.x. Epub 2006 Jun 27.

Abstract

Neisseria gonorrhoeae (gonococcus) infection results in recruitment of polymorphonuclear leukocytes (PMNs) to the urethral lumen. Recent work from our laboratory demonstrated that N. gonorrhoeae resists killing and replicates within PMNs. In this study, we examined the effect of gonococci on PMN viability. Using both transmission electron microscopy and light microscopy, we observed nuclear condensation after 6 h in PMNs that were resting or challenged with opsonized zymosan particles (OPZ). In contrast, N. gonorrhoeae delayed nuclear condensation in PMNs for 12 h (13% apoptotic PMNs vs. 90% for resting and 94% for OPZ-stimulated PMNs). Additionally, DNA fragmentation was reduced in PMNs challenged with gonococci for 12 h (28% apoptosis vs. 52% for resting and 98% for OPZ-stimulated PMNs). However, 74% of PMNs challenged with gonococci had condensed nuclei and 67% had fragmented DNA after 24 h. Caspase activity (total caspase, caspase-3/7, caspase-9) was reduced at 4 h and mitochondrial integrity was preserved at 2 h in PMNs challenged with N. gonorrhoeae. Quantitative reverse transcription polymerase chain reaction demonstrated that mRNA levels of X-IAP and cIAP-2 remained high after challenge with gonococci, but were downregulated in OPZ-stimulated PMNs. Collectively, these findings demonstrate that N. gonorrhoeae delayed apoptosis in PMNs, perhaps as a strategy to allow intracellular replication.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Apoptosis / physiology*
  • Caspases / metabolism
  • Cell Nucleus / metabolism
  • Cell Nucleus / ultrastructure
  • Gene Expression / genetics
  • Humans
  • In Situ Nick-End Labeling / methods
  • Inhibitor of Apoptosis Proteins / genetics
  • Inhibitor of Apoptosis Proteins / metabolism
  • Microscopy, Electron, Transmission
  • Mitochondria / metabolism
  • Mitochondria / ultrastructure
  • Neisseria gonorrhoeae / growth & development*
  • Neutrophils / cytology*
  • Neutrophils / metabolism
  • Neutrophils / microbiology
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • Time Factors

Substances

  • Inhibitor of Apoptosis Proteins
  • Caspases