Acid Suppressive Therapy and C. difficile Infection: Beyond Gastric pH Effects
Author(s):
Samantha Tarras, Wayne State University; Lawrence Diebel, Wayne State University Health Center; David Liberati, Wayne State University
Background: Several predisposing factors for Clostridium difficile infection (CDI) have been proposed including exposure to gastric acid reducing agents such as H2 blockers and proton pump inhibitors (PPI). The mechanism(s) for this include an effect on C. difficile spore germination via gastric acid suppression. A recent murine model of C. difficile-associated colitis demonstrated that PPI exposure increased the severity of intestinal inflammation. A comparative effect with H2 blockers and potential mechanism(s) for this "direct effect" of acid suppressive agents on the intestinal barrier against C. difficile are unknown.
Hypothesis: To compare the "non-acid suppressive" effects of H2 blockers and PPIs on intestinal barrier function following C. difficile toxin A exposure in an in vitro model.
Methods: HT29-MTX (mucus producing) colonic epithelial cell (IEC) monolayers were incubated for 48 hrs. with cimetidine (3µM), omeprazole (OME, 100µM) or media control. Tox A (50µg/ml) was added to the apical media. IEC tox A uptake, percent apoptosis and permeability to FITC-Dextran 10 quantitated. Mucin content of the mucus layer was determined using an ELISA.
Results: mean ± SD; N = 5 for each group
| |
Tox A uptake
(ng/ml)
|
% apoptosis |
Perm.
(nmol/cm2/hr.)
|
| MTX |
------ |
4.4 ± 0.2 |
0.47 ± 0.01 |
| MTX + cimet. |
------ |
4.6 ± 0.1 |
0.48 ± 0.03 |
| MTX + OME |
------ |
5.2 ± 0.2* |
0.61 ± 0.03* |
| MTX + Tox A |
32.8 ± 3.2 |
8.2 ± 0.4* |
0.56 ± 0.02* |
| MTX + Tox A + OME |
138.3 ± 5.3# |
32.2 ± 1.3*# |
1.25 ± 0.06*# |
| MTX + Tox A + cimet. |
106.6 ± 6.5#$ |
17.1 ± 1.1*#$ |
1.02 ± 0.07*#$ |
*p<0.001 vs. MTX and MTX + cimetidine, #p<0.001 vs. MTX + Tox A, $p<0.001 vs. MTX + Tox A + OME.
Treatment of IEC with cimetidine decreased the mucin content of the mucus layer from 5.0 ± 0.5 to 1.3 ± 0.4 ng/ml (p<0.001). No effect of mucin content was noted with the PPI.
Conclusions: Both H2 blockers and PPIs appear to render colonic epithelial cell monolayers “at risk” for perturbations and intestinal barrier dysfunction following C. difficile toxin exposure. It appears that this effect is more profound with omeprazole vs. cimetidine after C. difficile exposure. The mechanisms include an effect on the mucus layer by H2 blockers and likely a direct effect on IEC cellular function by PPIs.