Aggregative adherent strains of Corynebacterium pseudodiphtheriticum enter and survive within HEp-2 epithelial cells.
Corynebacterium pseudodiphtheriticum is a well-known human pathogen that mainly causes respiratory disease and is associated with high mortality in compromised hosts. Little is known about the virulence factors and pathogenesis of C. pseudodiphtheriticum. In this study, cultured human epithelial (HEp-2) cells were used to analyse the adherence pattern, internalisation and intracellular survival of the ATCC 10700 type strain and two additional clinical isolates. These microorganisms exhibited an aggregative adherence-like pattern to HEp-2 cells characterised by clumps of bacteria with a "stacked-brick" appearance. The differences in the ability of these microorganisms to invade and survive within HEp-2 cells and replicate in the extracellular environment up to 24 h post infection were evaluated. The fluorescent actin staining test demonstrated that actin polymerisation is involved in the internalisation of the C. pseudodiphtheriticum strains. The depolymerisation of microfilaments by cytochalasin E significantly reduced the internalisation of C. pseudodiphtheriticum by HEp-2 cells. Bacterial internalisation and cytoskeletal rearrangement seemed to be partially triggered by the activation of tyrosine kinase activity. Although C. pseudodiphtheriticum strains did not demonstrate an ability to replicate intracellularly, HEp-2 cells were unable to fully clear the pathogen within 24 h. These characteristics may explain how some C. pseudodiphtheriticum strains cause severe infection in human patients.
Laboratório de Difteria e Corinebacterias de Importância Clínica, Instituto de Biologia Roberto Alcântara Gomes, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
Monica Cristina de
MC
Souza
Louisy Sanches dos
LS
Santos
Débora Leandro Rama
DL
Gomes
Priscila Soares
PS
Sabbadini
Cinta Silva dos
CS
Santos
Thereza Christina Ferreira
TC
Camello
Lídia Maria Buarque Oliveira
LM
Asad
Ana Claúdia de Paula
AC
Rosa
Prescilla Emy
PE
Nagao
Raphael
R
Hirata Júnior
Ana Luiza de Mattos
AL
Guaraldi
D001422:Bacterial Adhesion / Q000502:physiology*; D003352:Corynebacterium / Q000472:pathogenicity* / Q000502:physiology; D004847:Epithelial Cells / Q000382:microbiology*; D056945:Hep G2 Cells; D006801:Humans; D014774:Virulence