Expression of and cytokine activation by Escherichia coli curli fibers in human sepsis

J Infect Dis. 2000 Feb;181(2):602-12. doi: 10.1086/315233.


Curli organelles are expressed by commensal Escherichia coli K12 and by Salmonella typhimurium at temperatures <37 degrees C, which bind serum proteins and activate the contact-phase system in vitro. This study demonstrates, by means of an anti-CsgA (curli major subunit) antibody, that a significant fraction of E. coli isolates (24 of 46) from human blood cultures produce curli at 37 degrees C in vitro. Serum samples from 12 convalescent patients with sepsis, but not serum from healthy controls, contained antibodies against CsgA (n=12). This study further demonstrates that a curli-expressing E. coli strain and a noncurliated mutant secreting soluble CsgA induce significantly (P<.05) higher levels of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin [IL]-6, and IL-8) in human macrophages differentiated from THP-1 cells. These data, therefore, provide direct evidence that curli are expressed in vivo in human sepsis and suggest a possible role for curli and CsgA in the induction of proinflammatory cytokines during E. coli sepsis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Bacterial / blood
  • Bacteremia / immunology
  • Bacteremia / microbiology*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / immunology*
  • Bacterial Proteins / metabolism*
  • Congo Red / metabolism
  • Cytokines / genetics
  • Cytokines / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Escherichia coli / isolation & purification
  • Escherichia coli / metabolism*
  • Escherichia coli / pathogenicity
  • Escherichia coli Infections / immunology
  • Escherichia coli Infections / microbiology*
  • Escherichia coli Proteins*
  • Female
  • Fibronectins / metabolism
  • Humans
  • Immunoblotting
  • Macrophage Activation
  • Male
  • Microscopy, Electron
  • Middle Aged
  • Polymerase Chain Reaction


  • Antibodies, Bacterial
  • Bacterial Proteins
  • Cytokines
  • Escherichia coli Proteins
  • Fibronectins
  • csgA protein, E coli
  • Crl protein, Bacteria
  • Congo Red