Effect of acute-phase and heat-shock stress on apoptosis in intestinal epithelial cells (Caco-2).
OBJECTIVE
a) To determine if the sequence of exposure of intestinal epithelial cells to heat-shock or acute-phase stimuli would affect whether cellular protection or injury would occur; and b) to determine if the effects of a thermally induced heat-shock response can be mimicked by sodium arsenite, a nonthermal inducer of the heat-shock response.


METHODS
In vitro controlled study.


METHODS
Institutional laboratories.


METHODS
Caco-2 human intestinal cell line.


METHODS
Human intestinal epithelial cells (Caco-2) were grown on 35-mm culture dishes, chamber slides, or in a bicameral culture system to confluence or until tight-junction integrity was established. The cells were examined for viability, apoptosis, and bacterial translocation after exposure to a series of insults.


RESULTS
Control Caco-2 cells (medium only) and cells exposed to arsenite or to LPS alone had an apoptotic cell rate of 5.7%, 7.9%, and 8.6%, respectively. However, Caco-2 cells exposed to the cytokines IL-1beta and IL-6 had a significantly higher rate of apoptosis (22.1%, p < .01 vs. other groups). Caco-2 cells exposed to arsenite followed by LPS had 6.7% apoptotic cells, while cells exposed to LPS followed by arsenite had a significantly greater number of apoptotic cells (19.7%, p < .05). In addition, cells exposed to cytokines followed by arsenite had a higher apoptotic rate than cells exposed to arsenite followed by cytokines (28.4% vs. 10.6%, p < .01). Similar results were seen when cell viability was quantitated. At 3 hrs after challenge with Escherichia coli, the cytokine-exposed Caco-2 monolayers had a significantly increased rate of bacterial passage across the Caco-2 monolayer than control monolayers (p < .05), while the Caco-2 monolayers exposed to arsenite followed by cytokines or arsenite alone had a decreased rate of bacterial passage (p < .05). Conversely, cells exposed to cytokines or LPS before arsenite had the highest number of bacteria crossing the monolayer (p < .05).


CONCLUSIONS
These results indicate that preinduction of a heat-shock response (arsenite) can protect against cytokine or LPS-induced apoptosis and enterocyte dysfunction, as manifested by the passage of E. coli across an intact enterocyte monolayer. In contrast, the induction of a heat-shock response after exposure to acute-phase response inducers (cytokines and LPS) may result in decreased enterocyte viability, increased apoptosis, and cellular dysfunction.
Swank
G M
GM
Department of Surgery, UMDNJ-New Jersey Medical School, Newark 07103, USA.
Lu
Q
Q
Xu
D Z
DZ
Michalsky
M
M
Deitch
E A
EA
D017209:Apoptosis; D018053:Arsenites / Q000494:pharmacology*; D018988:Bacterial Translocation; D018938:Caco-2 Cells / Q000378:metabolism*; D016207:Cytokines / Q000096:biosynthesis* / Q000187:drug effects; D004926:Escherichia coli / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000187:drug effects; D018869:Heat-Shock Response / Q000187:drug effects*; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D017670:Sodium Compounds / Q000494:pharmacology*; D013439:Sulfhydryl Reagents / Q000494:pharmacology*
D018053:Arsenites; D016207:Cytokines; D006360:Heat-Shock Proteins; D017670:Sodium Compounds; D013439:Sulfhydryl Reagents; C017947:sodium arsenite