Calcium Glycerophosphate (CGP) Preserves Transepithelial Integrity

We hypothesized that CGP would mitigate the effect of hypoxia, cytokines (CK) and/or α‐gliadin peptide 31‐55 (α‐GP, the gluten peptide fragment of celiac disease) to increase transepithelial permeability. All experiments used Caco‐2 monolayers with transepithelial electrical resistance (TEER) of 600‐700 Ω/cm 2 . All agents were added to the luminal side of the cell monolayer. In normoxic cells, TEER increased at 0.69 ± 0.11% / hour and mannitol flux was 28 ± 4 dpm / hour. In hypoxic cells, TEER decreased 19.4 ± 1.31 % / hour and mannitol flux increased to 162 ± 27 dpm / hour. 10 µM CGP, reduced hypoxia induced TEER loss to 10.6±1.86 % / hour and mannitol flux to 35±dpm / hour (p<0.001 compared to normoxia or hypoxia alone). CK stimulated TEER loss was 2.1 ± 0.31% / hour and mannitol flux was 54 ± 1 dpm / hour. 10 µM CGP reduced TEER loss to 1.4 ± 0.28% / hour, and mannitol flux to 13 ±1 dpm / hour (p<0.001 compared to control or to hypoxia alone). In separate experiments, α‐GP + CK increased mannitol flux from 21±1 to 39 ± 3 dpm / hour; α‐GP + CK + CGP (1 mM) group, mannitol flux was 32 ±1 dpm / hour (p<0.05 vs α ‐GP + CK). In these same experiments, TEER loss was 2.72 ± 0.497% / hour in the peptide + CK group vs. 1.20 ± 0.327% /hour in the α‐GP + CK + CGP group (p<0.05 vs α ‐GP + CK). E‐cadherin protein was 75.8±8.6% of control in the α‐GP + CK group, while in the α‐GP + CK + CGP treated cells, E‐cadherin was 101 ± 2.9% of control (p<0.05 vs α ‐GP + CK. In summary, CGP showed a significant time and concentration dependent effect to attenuate increased gut permeability caused by hypoxia, CK, or α‐GP an effect that was observable even at 1µM. These factors may make it worthwhile to pursue calcium glycerophosphate as an adjunct to other therapies to prevent loss of gut epithelial integrity in hypoxia or celiac disease.