Antagonizing IL-17A Reduces Vascular Inflammation and Attenuates Oxidative Stress Formation but Does Not Significantly Improve Vascular Dysfunction Induced by One Week of Angiotensin II Treatment.

Introduction: The pro-inflammatory cytokine interleukin-17A (IL-17A) has a key role in the inflammatory cascade and promotes vascular inflammation and dysfunction. In addition, IL-17A is centrally involved in several autoimmune diseases. IL-17A deficiency has been linked to reduced vascular inflammation associated with attenuated arterial hypertension under long-term angiotensin II (Ang II) exposure for four weeks. This is of interest as IL-17A is one factor linking several autoimmune diseases with cardiovascular comorbidity. So far, little is known about the effects of IL-17A during the early stages of vascular dysfunction development-an interval possibly representing an optimal therapeutic window. Methods: Mice lacking the IL-17A receptor alpha (IL-17RAdel) and wild-type counterparts were treated with Ang II for one week (1 mg/kg bodyweight/week). We assessed systemic oxidative stress formation and vascular function, as well as inflammatory cells in the vessel wall. In parallel, C57BL/6J mice treated with Ang II received anti-IL-17A therapy, to evaluate the same parameters. Results: Both IL-17RA-deficient mice and anti-IL-17A-treated C57BL/6J mice exhibited an attenuated oxidative stress response and mitigated vascular inflammation following one week of Ang II treatment. These effects did not significantly prevent the onset of Ang II-induced vascular dysfunction at that timepoint. Conclusions: After one week of Ang II treatment, antagonizing IL-17RA or IL-17A only partially reduced/attenuated the Ang II-induced effects on the vasculature. In the context of IL-17A-driven autoimmune diseases with associated vascular pathology, our findings suggest that anti-inflammatory therapies alone may not be sufficient to attenuate vascular impairment. A combined approach including agents with direct protective vascular effects may be required for effective intervention for the associated vascular comorbidity.