D28-24 Taurine Ursodeoxycholic Acid (tudca) Attenuates Lipopolysaccharide (lps)/tumor Necrosis Factor-alpha (tnf-a) Induced Barrier Dysfunction, Inflammatory Signaling and Promotes Cell Survival in Human Pulmonary Artery Endothelial Cells (hpaecs)

Rationale

Taurine Ursodeoxycholic Acid (TUDCA) is an endogenously synthesized, taurine-conjugated, bile acid produced in mammalian species that has long been used in Traditional Chinese medicine. More recently, TUDCA gained increasing attention due to its wide range of potential clinical and health benefits, including protective effects in enterohepatic, endocrinopathies and neurodegenerative diseases. These effects have been associated with chaperone-like activity, anti-apoptotic effects modulation of Unfolded Protein Response (UPR) to Endoplasmic reticulum (ER) stress. However, the potential role of TUDCA in mitigation of endothelial cell dysfunction in pneumonia and acute lung injury (ALI) settings has not been investigated.

Methods

Primary cultures of Human Pulmonary Artery Endothelial Cells (HPAECs) obtained from Lonza (Allendale, NJ, USA) were cultured in EGM-2 growth media containing 2% fetal bovine serum and exposed to bacterial wall lipopolysaccharide (LPS) or tumor necrosis factor-α (TNF-α) in the presence or absence of various concentrations of TUDCA. Barrier properties of HPAEC monolayers were evaluated by measurements of trans-endothelial electrical resistance (TEER) via electrical cell-substrate impedance sensing system (ECIS) (Applied Biophysics, Troy, NY). TUDCA effects on preservation of EC monolayer integrity were evaluated by immunofluorescence (IF) staining of HPAEC with antibody to VE-cadherin. Expression of markers of inflammation and key proteins involved in apoptotic and cell death signaling. evaluated by western blot analysis of EC protein extracts.

Results

TUDCA did not exhibit toxic effects and did not significantly affect EC barrier function in the 50 µM - 2mM TUDCA concentration range. At higher concentrations, TUDCA caused initial sharp TEER decline which quickly normalized back to baseline and continued through the end of experiment (72 hrs).TUDCA exhibited protective effects at a cellular level based on the protein expression noted on western blot analysis. Treatment of HPAECs with TUDCA (200-500 µM) prior to LPS or TNF-α challenge dose-dependently attenuated pathogen-induced VCAM1 and ICAM1 expression, decreased levels of phospho-NFkB and prevented IkBα degradation as readouts of inflammatory activation. VE-cadherin staining showed better preservation of cell-cell contacts in LPS-challenged HPAEC treated with TUDCA. Finally, TUDCA treatment mitigated cell death signaling in pulmonary EC induced by LPS as indicated by decreased levels of phospho-MLKL, a marker of cell death pathway.

Conclusion

This study showed barrier-preserving, anti-inflammatory and pro-survival effects of TUDCA on human pulmonary EC under ALI-relevant conditions. Our findings warrant further investigations into the potential therapeutic application of TUDCA in ALI/ARDS.

This abstract is funded by: None