Bile Acid (BA), Lithocholic Acid (LCA), Reverses Chenodeoxycholate (CDCA)‐ and Cytokine‐Induced Loss in Epithelial Barrier Function in Human Colon Carcinoma T84 Cells

Abstract

Epithelial apoptosis and tight junction (TJ) changes contribute to intestinal barrier dysfunction in Crohn's disease and colitis. We have reported that in T84 monolayers, CDCA decreased transepithelial resistance (TER) and caused dose‐ and time‐related cytotoxicity. CDCA increased cascade blue 10kDa dextran (CB10D) flux from apical to basal surfaces and this was enhanced by pro‐inflammatory cytokines (PiC: TNFα+IL‐1ß+IFNγ; FASEB J:28, 1113.3, '14). In this study we examined if LCA, a dehydroxylated product of CDCA, had similar effects. Confluent T84 cells (TER >1000 Ω.cm2) were treated with 5‐500µM LCA for 1 and 24 hr ± PiCs. Cell viability and apoptosis (Accuri flow cytometry), toxicity (lactate dehydrogenase), and paracellular permeability (TER and CB10D fluxes) were assessed. One hour or overnight (O/N) LCA (5 – 500μM) exposure neither affected cell viability nor apoptosis. LCA (1 Hr or O/N) did not increase LDH release and therefore was not cytotoxic. Time‐dependent studies (0.5 – 18 Hr) show that LCA alone did not affect TER (18 Hr: Control: 925+15; 50µM LCA: 848+41 Ω.cm2 n=6) or CB10D fluxes. In contrast, 50µM LCA attenuated PiC‐induced decreases in TER (data not shown) and increases in CBD10 fluxes ± 500 μM CDCA (18 Hr, in μg: Control: 7±1; LCA: 5±1; PiC: 51±4; PiC+LCA: 10±1; CDCA: 110±2; PiC+CDCA: 180±2; CDCA+LCA: 63±1 PiC+CDCA+LCA: 37.8±0.3; n>3). Surprisingly, unlike CDCA, LCA neither causes cell death nor disrupts tight junction function. On the contrary, LCA restores epithelial barrier integrity that is disrupted by cytokines ± CDCA. This study suggests that LCA could be a target therapeutic drug for inflammatory and diarrheal diseases.