Cross-talk between oxidized LDL, oxidative stress and renin-angiotensin-aldosterone system

Clin Res Cardiol (2025). DOI 10.1007/s00392-025-02625-4
H. Morawietz (Dresden)¹, R. Catar (Berlin)², J. Kamhieh-Milz (Berlin)³, C. Goettsch (Aachen)⁴, L. Chen (Berlin)², D. Zickler (Berlin)², A. Taye (1464040)⁵, A. Hofmann (01307)⁶, C. Brunßen (Dresden)¹, G. Müller (Dresden)¹, M. Cybularz-Bednarek (Dresden)⁷, C. Hengst (Dresden)¹, M. d. L. Villar Ballesteros (Dresden)¹, S. Lehmann (Dresden)⁸, U. Schubert (Dresden)⁸, B. Ludwig (Dresden)⁸, C. Zeigler (Dresden)⁸, S. Bornstein (Dresden)⁸, A. Krug (Dresden)⁸, T. Walther (Berlin)⁹, G. Moll (Berlin)^2
1Universitätsklinikum Carl Gustav Carus an der TU Dresden Med. Klinik III, Gefäßendothel/Mikrozirkulation Dresden, Deutschland; ²Charité - Universitätsmedizin Berlin Berlin, Deutschland; ³Charité Universitätsmedizin Berlin Institute of Transfusion Medicine Berlin, Deutschland; ⁴Uniklinik RWTH Aachen Med. Klinik I - Kardiologie, Angiologie und Internistische Intensivmedizin Aachen, Deutschland; ⁵South Valley University Department of Pharmacology and Toxicology, Faculty of Pharmacy 1464040, Ägypten; ⁶University Hospital Carl Gustav Carus, TU Dresden Division of Vascular and Endovascular Surgery, Department of Visceral, Thoracic and Vascular Surgery 01307, Deutschland; ⁷Herzzentrum Dresden GmbH an der TU Dresden Klinik für Innere Medizin, Kardiologie und Intensivmedizin Dresden, Deutschland; ⁸Universitätsklinikum Carl Gustav Carus, TU Dresden Med. Klinik III Dresden, Deutschland; ⁹Medical School Berlin (MSB) Berlin, Deutschland

Background: Hypertension and hypercholesterolemia are important risk factors of endothelial dysfunction and atherosclerosis. Previous studies suggested a crosstalk between an activated renin-angiotensin-aldosterone system (RAAS), reactive oxygen species (ROS) and oxidized low-density lipoproteins (oxLDL) in atherosclerosis, but the underlying molecular mechanisms are not well understood.

Hypothesis: Can we identify novel signaling pathways controlling the molecular crosstalk of the RAAS with ROS and oxLDL in endothelial dysfunction and atherosclerosis?

Methods: The impact of AT₁R blockade on oxLDL-induced superoxide anion formation and endothelial dysfunction was studied in human umbilical artery endothelial cells and aortic rings of wild-type mice by chemiluminescence and Mulvany myograph. We cloned 5’-terminal deletions of the AT₁R promoter and assessed the luciferase activity in human endothelial cells. Oct-1 binding to the human AT₁R promoter region was studied by EMSA. Further assays included real-time PCR, confocal microscopy, Western blotting, G protein reporter assays, phospho-ERK1/2 antibodies and specific siRNAs. The data were validated in heart of obese C57BL/6 mice and cardiac and aortic tissue of AT_1a/AT_1b double knockout mice in vivo.

Results: AT₁R promoter activation studies upon Ang II- and oxLDL-stimulation in endothelial cells revealed that Ang II and oxLDL activate AT₁R signaling through G protein Gα_12/13, followed by activation of ERK1/2 MAP kinases, and transcription and translation of Oct-1, resulting in up-regulation of AT₁R, LOX-1 and NOX2 expression, which could be antagonized by specific inhibitors at each step of the identified signaling cascade. AT₁R blockade improved oxLDL-induced endothelial dysfunction in aortic rings of wild-type mice. Male C57BL/6 mice fed a high-fat diet exhibited upregulation of Oct-1 levels in cardiac tissues, compared to normal controls, while AT_1a/AT_1b double knockout mice demonstrated downregulation of Oct-1, AT₁R, LOX-1, and NOX2 on mRNA and protein level in cardiac and aorta tissue, thus confirming the identified signaling cascade in vivo.

Conclusions: Oct-1 is an essential transcription factor for Ang II- and oxLDL-induced upregulation of AT₁R and LOX-1 expression in endothelium, thus identifying a novel molecular cross-talk of oxLDL with ROS signaling and the RAAS contributing to development of endothelial dysfunction and atherosclerosis.