Escherichia coli cytotoxic necrotizing factor 1 effaces microvilli and decreases transmigration of polymorphonuclear leukocytes in intestinal T84 epithelial cell monolayers.
Cytotoxic necrotizing factor type 1 (CNF1), a 110-kDa toxin-like protein from pathogenic Escherichia coli strains, induces an actin cytoskeleton reorganization consisting of the formation of prominent stress fibers by permanent activation of the small GTP-binding protein Rho. Since p21Rho regulates tight-junction permeability and perijunctional actin reorganization in epithelial intestinal cells (A. Nusrat, M. Giry, J. R. Turner, S. P. Colgan, C. A. Parkos, E. Lemichez, P. Boquet, and J. L. Madara, Proc. Natl. Acad. Sci. USA 92:10629-10633, 1995), we used polarized T84 epithelial intestinal cell monolayers to examine whether CNF1 could affect microvillus structure, transepithelial resistance, and polymorphonuclear leukocyte (PMN) transmigration. Incubation of T84 cells with CNF1 did not influence transepithelial resistance, suggesting that barrier function and surface polarity were not affected by the toxin. However, CNF1 effaced intestinal cell microvilli and induced a strong decrease of PMN transepithelial migration in either the luminal-to-basolateral or the basolateral-to-luminal direction. CNF1 could thus be a virulence factor exhibiting a new type of combined activity consisting of effacing of microvilli and occlusion of the epithelial barrier to PMNs. Attenuated transepithelial migration of PMNs could result in the enhanced growth and protection of luminal bacteria.
Hofman
P
P
INSERM Unité 364, Faculté de Médecine, 06107 Nice Cedex 02, France. hofman@unice.fr
Flatau
G
G
Selva
E
E
Gauthier
M
M
Le Negrate
G
G
Fiorentini
C
C
Rossi
B
B
Boquet
P
P
D001427:Bacterial Toxins / Q000633:toxicity*; D016764:Cell Polarity; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D003599:Cytoskeleton / Q000187:drug effects; D003603:Cytotoxins / Q000633:toxicity*; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects; D004926:Escherichia coli / Q000472:pathogenicity; D029968:Escherichia coli Proteins; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects*; D008871:Microvilli / Q000187:drug effects*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000201:enzymology; D010539:Permeability / Q000187:drug effects; D009195:Peroxidase / Q000032:analysis
D001427:Bacterial Toxins; D003603:Cytotoxins; D029968:Escherichia coli Proteins; C060296:cytotoxic necrotizing factor type 1; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009195:Peroxidase