Local Activation of Nrf2 Inhibits Arteriovenous Fistula Stenosis in Mice

Background: The arteriovenous fistula (AVF) is the gold standard for dialysis vascular access, yet over 50% fail to mature, often due to venous stenosis. Oxidative stress is a key driver of stenosis after vascular injury. Thus, antioxidant therapies may improve AVF maturation. The transcription factor Nrf2 is a master regulator of the antioxidant response. We have shown Nrf2 activation inhibits stenosis in other vascular injury models. We developed a novel method to quantify AVF stenosis using Light Sheet Fluorescence Microscopy (LSFM) to assess lesions in 3D by volume, geometry, and stenosis. This study evaluated the effect of synthetic Nrf2 activators on AVF maturation. We hypothesized that a single periadventitial application of bardoxolone or omevaxolone at surgery would reduce AVF stenosis. Methods: AVFs were created in 16-week-old wild-type C57BL/6 mice. At the time of fistulae creation, Nrf2 activators in pluronic gel, or vehicle alone was applied periadventitially around the venous arm and the anastomosis of the fistulae. Animals were sacrificed at 21d and the AVFs were harvested. The tissue was cleared using iDisco+ and images acquired by light sheet fluorescence microscopy. Total volume area was quantified using stereoscopy VR software (syGlass). Results: LSFM analysis showed the expected lesion of the venous segment in control mice. Quantification of the stenosis length and volume showed a 1 mm long and 0.79 mm3 lesion in mice treated with vehicle alone (N=4). Low dose application of either bardoxolone (0.5 μg/kg) or omaveloxone (1 μg/kg) did not significantly change the extent of stenosis. However, a single higher dose of either bardoxolone (1 μg/kg) or omaveloxolone (2 μg/kg) was enough to improve patency. Bardoxolone methyl reduced the volume of the stenotic lesion from 0.4 mm3 to 0.2 mm3 (Fig 1). Conclusion: Our results suggest that local Nrf2 activation at the time of AVF creation potentially improves maturation rates by inhibiting stenosis. Funding: NIDDK Support