Toll-like receptor 4 (TLR4) impairs nitric oxide contributing to Angiotensin II-induced cavernosal dysfunction

• Published in: Life sciences (1973) Vol. 191; pp. 219 - 226
• Main Authors: Nunes, Kenia P., Bomfim, Gisele F., Toque, Haroldo A., Szasz, Theodora, Clinton Webb, R.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 15.12.2017; Elsevier BV
• Subjects: ACE inhibitors; Angiotensin; Angiotensin II; Angiotensin II - immunology; Animals; Arginine; Bacteria; Bioavailability; Blood Pressure; Citrulline; Contraction; Enzyme-linked immunosorbent assay; Erectile dysfunction; Erectile Dysfunction - immunology; Erectile Dysfunction - physiopathology; Gene expression; Immune system; Immunofluorescence; Innate immunity; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Muscles; Myocytes, Smooth Muscle - immunology; Myocytes, Smooth Muscle - pathology; Nitric oxide; Nitric Oxide - immunology; Nitric Oxide Synthase Type III - immunology; Nitric-oxide synthase; Penis - immunology; Penis - physiopathology; Proteins; Reactive oxygen species; Smooth muscle; Studies; T cell receptors; TLR4; TLR4 protein; TNF-α; Toll-Like Receptor 4 - immunology; Toll-like receptors; Tumor Necrosis Factor-alpha - immunology; Tumor necrosis factor-α; Western blotting; Angiotensin-II; TNF-α; TLR4; Nitric oxide
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2017.10.014

Angiotensin II (AngII), a corpus cavernosum (CC) constrictor peptide, modulates Toll like receptor (TLR) expression, a key element of the innate immune system, contributing to impaired vascular function in pathological conditions. However, it is unknown whether TLR4 is involved in AngII-induced erectile dysfunction. In this study, we investigated whether TLR4 plays a role in cavernosal dysfunction caused by AngII upregulation. Cavernosal smooth muscle cells (CSMC) from C57/BL6 mice were treated with AngII (0.1μM) or bacterial LPS (50ng/ml) for 12–24h and TLR4 expression was assessed. Mice were infused with AngII (90ng/min, 28days) and treated with anti-TLR4 antibody (0.1mg/daily, i.p.) for the last 14days of the treatment. CC tissue was used for functional studies and for Western blotting. Nitric Oxide Synthase (NOS) activity was measured by conversion of [3H]-l-arginine to [3H]-l-citrulline, systemic TNF-α levels by ELISA, and reactive oxygen species (ROS) by immunofluorescence. We report upregulation of TLR4 in CSMC following AngII or LPS stimulation. In AngII-infused mice, chronic treatment with anti-TLR4 antibody (28±2.1%) attenuates adrenergic CC contraction, which also ameliorates nitrergic (68.90±0.21 vs. 51.07±0.63, 8Hz, AngII-infused mice treated vs. non-treated). Decreased endothelial NOS expression, reduced NOS activity, and augmented levels of TNF-α, and ROS were found following AngII-infusion. These alterations were prevented, or at least decreased by anti-TLR4 antibody treatment. Inhibition of TLR4 ameliorates AngII-impaired cavernosal relaxation, decreases TNF-α levels, and restores NO bioavailability, demonstrating that TLR4 partly mediates AngII-induced cavernosal dysfunction.