Binding to and killing of human renal epithelial cells by hemolytic P-fimbriated E. coli.
Acute pyelonephritis is a common invasive infection frequently caused by E. coli that possess P-fimbriae and secrete hemolysin. We have examined the role of P fimbriae and hemolysin in the killing of putative target cells of acute pyelonephritis, that is, human renal epithelial cells (HRPTEC). Cultures of HRPTEC were overlaid with (1) a prototypic pyelonephritogenic E. coli (CFT073) which expresses both P fimbriae and hemolysin; (2) its hemolysin-negative isogenic mutant (CFT073hlyD::TnphoA); or (3) a prototypic nonpyelonephritogenic fecal E. coli (FN414) which is negative for both P fimbriae and hemolysin. CFT073 and CFT073hlyD::TnphoA but not FN414 adhered to HRPTEC, as demonstrated by electron microscopy and direct counting. Adherence was diminished by antisera directed against P fimbriae and by a monoclonal antibody recognizing the epithelial receptor for P fimbriae. CFT073 was significantly more cytolethal for HRPTEC than its hemolysin-negative mutant. The bacteria-free filtrate of CFT073 was both hemolytic and cytolethal whereas that of CFT073hyD::TnphoA was not hemolytic and was significantly less cytolethal. Finally, we demonstrated that CFT073 passed through monolayers of HRPTEC at a higher rate than CFT073hlyD::TnphoA, indicating that hemolysin damages HRPTEC, facilitating passage of bacteria through the epithelial barrier. With HRPTEC and a pyelonephritogenic strain of E. coli we have reproduced in vitro bacterial attachment and toxin delivery by P fimbriae and hemolysin, factors epidemiologically associated with acute pyelonephritis in patients.
Trifillis
A L
AL
Department of Pathology, University of Maryland School of Medicine, Baltimore.
Donnenberg
M S
MS
Cui
X
X
Russell
R G
RG
Utsalo
S J
SJ
Mobley
H L
HL
Warren
J W
JW
D001422:Bacterial Adhesion; D016923:Cell Death; D002478:Cells, Cultured; D004848:Epithelium / Q000382:microbiology / Q000473:pathology; D004926:Escherichia coli / Q000472:pathogenicity* / Q000502:physiology / Q000648:ultrastructure; D004927:Escherichia coli Infections / Q000209:etiology / Q000382:microbiology / Q000473:pathology; D010861:Fimbriae, Bacterial / Q000648:ultrastructure; D006461:Hemolysis; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000382:microbiology* / Q000473:pathology; D008854:Microscopy, Electron; D011704:Pyelonephritis / Q000209:etiology / Q000382:microbiology / Q000473:pathology