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Abstract: TH-PO934

The Sulfate Moiety in Indoxyl Sulfate Is Critical for Activation of Aryl Hydrocarbon Receptor–Tissue Factor Axis and 3-Indole Methanol Is a Competitive Antagonist of Indoxyl Sulfate

Session Information

Category: CKD (Non-Dialysis)

  • 1903 CKD (Non-Dialysis): Mechanisms

Authors

  • Richards, Sean, Boston University Medical Center, Boston, Massachusetts, United States
  • Walker, Joshua A., Boston University, Boston, Massachusetts, United States
  • Roth, Daniel M., Boston University School of Medicine, Boston, Massachusetts, United States
  • Belghasem, Mostafa, Boston University, Boston, Massachusetts, United States
  • Lee, Norman, Boston University, Boston, Massachusetts, United States
  • Whelan, Stephen A., Boston University, Boston, Massachusetts, United States
  • Arinze, Nkiruka, Boston Medical Center, Boston, Massachusetts, United States
  • Yoo, Sung bok, Boston University, Boston, Massachusetts, United States
  • Francis, Jean M., Boston University Medical Center, Boston, Massachusetts, United States
  • Chitalia, Vipul C., Boston University School of Medicine, Boston, Massachusetts, United States
Background

Indolic solutes (indoxyl sulfate –IS, Indoxyl acetate -IA) are bonafide uremic solutes with protean systemic manifestations, including prothrombotic effect through activation of the Aryl hydrocarbon receptor (AHR) and tissue factor (TF). Despite its well-established pathogenicity, molecular determinants of IS that regulate its prothrombotic propensities remain unknown.

Methods

A structure activity relationship analysis was performed using a set of commercially available analogs. Activity was compared biochemically using validated AHR and TF activity assays, and visually in a transgenic zebrafish model containing a CYPA1 promoter tethered to a GFP reporter. A newly identified antagonist, indole-3-methanol (3-IM) was confirmed by using an carotid thrombosis model in mice treated with IS, as well as by ability to reduce TF in vascular smooth muscle cells treated with sera obtained from CKD patients with known concentration of IS levels.

Results

Modifying the sulfate moiety of IS altered its ability to increase AHR and TF activities. IA exhibited 100-fold higher AHR activation in cells and zebrafish models than IS. Of a total of thirteen analogs analyzed, five showed an agonistic activity in the presence of IS while one showed no effect. Of seven analogs with antagonistic activity towards IS, 3-IM significantly inhibited IS-induced AHR activation and TF with an IC50 of 50uM. 3-IM showed a potent anti-thrombotic activity in an IS-specific mouse model of thrombosis. Importantly, the downregulation of TF with 3-IM was significantly higher in vascular smooth muscle cells treated with uremic sera compared to cells treated with control sera. The ability of 3IM to suppress TF inversely correlated with the levels of IS in sera of end stagre renal disease patients.

Conclusion

The sulfate moiety is an important determinant of activity of IS in the AHR-TF axis. A non-sulfated analog, 3-IM suppresses TF and thrombosis in an IS-specific manner. These results point to the potential of 3-IM as a new therapeutic in counteracting IS-mediated systemic manifestations.

Funding

  • Other NIH Support