N. Cruz et al., BACTERIAL TRANSLOCATION ACROSS ENTEROCYTES - RESULTS OF A STUDY OF BACTERIAL-ENTEROCYTE INTERACTIONS UTILIZING CACO-2 CELLS, Shock, 1(1), 1994, pp. 67-72
Due to the inherent limitations of in vivo studies, the cellular mecha
nisms underlying the process of bacterial translocation (BT) across th
e intestinal epithelial barrier are poorly understood. Thus, we have u
tilized the Caco-2 intestinal cell line to study this process. Caco-2
cells were grown to confluence on semipermeable membranes contained in
the upper compartment of a 2 compartment system. Cellular confluence
and tight junction integrity was verified by measurements of the trans
epithelial electrical resistance in ohms cm2. BT was measured by cultu
ring the bacteria (nonpathogenic Escherichia coli) that were able to c
ross the Caco-2 monolayer and were present in the bottom compartment,
as well as by monitoring the passage of 1-mum fluorescent beads. Caco-
2 cells were pretreated with several metabolic inhibitors: 1.0 mM sodi
um azide (oxidative phosphorylation), 10 mug/ml nocodazole (microtubul
e), 10 muM phalloidine (microfilament), and 5.0 mug/ml cytochalasin D
(microfilament). To investigate the mechanisms of BT. Both bacteria an
d fluorescent beads crossed the Caco-2 monolayer. Azide had no effect
on BT while both nocodazole (n = 17) and phalloidine (n = 14) signific
antly decreased translocation of E. coli versus control monolayers (p
< .05). Cytochalasin D increased BT versus control membranes, however
this was associated with loss of tight junction integrity (transepithe
lial electrical resistance decreased from 201 +/- 79 to 87 +/- 6.4). B
T across Caco-2 cells appears to be a polar process which is to some e
xtent microtubule- and microfilament-dependent.