Tauroursodeoxycholate is an endoplasmic reticulum (ER) stress inhibitor. Tauroursodeoxycholate significantly reduces expression of apoptosis molecules, such as caspase-3 and caspase-12. Tauroursodeoxycholate also inhibits ERK.

Tauroursodeoxycholate (TUDCA) suppresses both viability and migration of vascular smooth muscle cells (VSMCs) through inhibition of ERK phosphorylation, by induction of mitogen-activated protein kinase phosphatase-1 (MKP-1) via PKCα. Tauroursodeoxycholate inhibits both the proliferation and migration of VSMCs via inhibition of ERK, through Ca²⁺-dependent PKCα translocation. Tauroursodeoxycholate prevents platelet-derived growth factor (PDGF) and vascular injury-induced MMP-9 expression. The knock-down of MKP-1 using specific si-RNA restores the reduced VSMC viability by Tauroursodeoxycholate (200 μM), which suggests that anti-proliferative effect of Tauroursodeoxycholate depended on the MKP-1 expression^[1].

The effects of Tauroursodeoxycholate (TUDCA) on proliferation and apoptosis of VSMCs in vivo are examined using immunohistochemistry for proliferating cell nuclear antigen (PCNA) and the transferase dUTP nick-end labelling (TUNEL) assay. Tauroursodeoxycholate (10, 50, and 100 mg/kg) increases the caspase 3 activity of injured tissues in a dose-dependent manner, indicating that Tauroursodeoxycholate induces apoptosis of VSMCs in the neointima. Using the injured tissues, further examination and comparison of the phosphorylation level of ERK and MMP-9 expression is performed at 1 week after injury, compared with normal controls. Balloon injury increased both the phosphorylation of ERK and expression of MMP-9 in the tissues. Tauroursodeoxycholate (10, 50, and 100 mg/kg) inhibits phosphorylation of ERK and MMP-9 expression in a dose-dependent manner^[1]. Tauroursodeoxycholate (TUDCA) is a hydrophilic bile acid. Tauroursodeoxycholate as a cytoprotective agent improves liver function and can prevent hepatocellular carcinoma by reducing ER stress and apoptosis. Tauroursodeoxycholate significantly reduces expression of apoptosis molecules, such as caspase-3, caspase-12, C/EBP homologous protein, c-Jun N-terminal kinase (JNK), activating transcription factor 4 (ATF4), X-box binding protein (XBP), and eukaryotic initiation factor 2α (eIF2α) in Ang II induced ApoE^-/- mice (p<0.05). Tauroursodeoxycholate reduces Angiotensin (Ang) II induced abdominal aortic aneurysm (AAA) formation in ApoE^-/- mice. Tauroursodeoxycholate is used at a dose of 0.5 g/kg/day in treating Ang II induced ApoE^-/- mice (ER stress inhibitor group). Systolic blood pressure (141.3±5.6 mmHg vs 145.9±8.9 mmHg; p>0.05) and total cholesterol levels (663.6±88.7 mg/dL vs 655.7±65.4 mg/dL; p>0 .05) do not differ between the AAA model group and Tauroursodeoxycholate group. In addition, maximum aortic diameter is significantly smaller in those in Tauroursodeoxycholate group compared with those in the AAA model group (0.95±0.03 mm vs 1.79±0.04 mm; p<0.05). AAA lesion areas are also smaller in those in Tauroursodeoxycholate group than in those in the AAA model group (0.37±0.03 mm² vs 1.51±0.06 mm²; p<0.05)^[2].

• [1]. Kim SY, et al. Tauroursodeoxycholate (TUDCA) inhibits neointimal hyperplasia by suppression of ERK viaPKCα-mediated MKP-1 induction. Cardiovasc Res. 2011 Nov 1;92(2):307-16.

  [2]. Qin Y, et al. Tauroursodeoxycholic Acid Attenuates Angiotensin II Induced Abdominal Aortic Aneurysm Formation in Apolipoprotein E-deficient Mice by Inhibiting Endoplasmic Reticulum Stress. Eur J Vasc Endovasc Surg. 2017 Mar;53(3):337-345.