Probiotics Play a Key Role in Alleviating Bile Acid (BA)-Induced Cytokine Release and Tight Junction (TJ) Dysfunction in Human Colonic T84 Cells
Authors: Durrani Hiba , Khan Enaya , Naseeruddin Iman , Ala Fatima , Naseeruddin Yusra , Rao Mrinalini , Poch Mark , Sarathy Jayashree 
Published: May 2023

High colonic BAs play a role in pathogenesis of diarrheal diseases in ~1% of the population. Probiotic supplements are often used to help alleviate the symptoms. We have previously reported that the primary BA, chenodeoxycholic acid (CDCA; 500μM), alters the pore and leak functions of TJs and disrupts barrier integrity in T84 cells, while its derivative, lithocholic acid (LCA; 50μM), did not; CDCA action involved reactive oxygen species, the proinflammatory cytokine IL-8, and apoptosis. Further, probiotics±LCA ameliorated CDCA-induced apoptosis and oxidative stress (FASEB J, 36, R5817, 2022). In the present study, we hypothesize that probiotics could ameliorate CDCA-induced cytokine release, barrier disruption and increases in paracellular permeability in T84 cells.Probiotics in Up & UpTM extra strength supplement ( B. bacterium and L. bacillus strains; 30 billion CFUs) were grown in T84 cell culture media±BA under anaerobic conditions at 37°C and sterile filtered to obtain conditioned media (CM), which was used in subsequent experiments. T84 cells grown to confluency in 12-well plates or Transwells to a Trans Epithelial Resistance (TER) of >1KΩ.cm2 were treated with CM±BA. Following 0.5, 1, 2, 3, 4, 6 and 18 hours (h) incubation: IL-8 released in the media was measured with a sandwich ELISA (pg/ml); TJ pore function measured as TER (Ω.cm2) and TJ leak function measured as FITC-10 kDa dextran flux (F10D; μg). *, p≤0.05 different from control (CTL); #, p≤0.05 different from treatment with only CM.CDCA increased IL-8 release over time, with significant increases starting at 6h (pg/ml; CTL:320±20; CDCA:1524±180*; n=4) and being maintained up to 18h (CTL:700±40; CDCA:3760±350*; +ve CTL: TNFα (100 ng/ml):2600±170*; n≥6; other time points not shown). As previously shown, LCA reduced basal and CDCA-induced IL-8 release (18h, LCA:348±50*; CDCA+LCA:752±30*; n≥4). Probiotic CM±LCA also significantly decreased basal and CDCA-induced IL-8 release (18h, CM:335±50*; CM+CDCA:810±43#; CM+LCA:155±15#; CM+CDCA+LCA:280±102#; n≥4).In terms of TJ pore function, CDCA caused a dramatic reduction in TER in 1 hr and LCA had no effect (% decrease vs CTL;1h, CDCA:88±9*; LCA:2±3; CDCA+LCA:88±5*; n=3). Similarly, probiotic CM did not alter CDCA±LCA-induced decreases in TER (CM+CDCA: 83±8*; CM+LCA: 3±7, CM+CDCA+LCA: 85±9*; n=4). In contrast, probiotic CM reduced the effects of CDCA on the leak function by 60% (18h, F10D flux, μg: CTL:5±1; CDCA:97±5*; CM:6±1; CM+CDCA:36±7#; n=3). LCA decreased CDCA’s effect by 40%, which was further attenuated by CM (18h (μg): LCA:11±7; CM+LCA:8±1; CDCA+LCA:51±3#; CM+CDCA+LCA:18±3#; n≥3). In summary, probiotics and LCA mitigate CDCA-induced inflammation by decreasing IL-8 release and TJ dysfunction by decreasing leak, but not pore function in T84 cells. Understanding the mechanism by which probiotics restore barrier integrity will help identify novel therapeutic strategies to target symptoms in patients with BA associated diarrhea.

JS & MP, Institutional funds, Benedictine Univ; HD, EK, IN, FA, & YN: NSSRP, Benedictine Univ.

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.