Deletion of interleukin-6 prevents cardiac inflammation, fibrosis and dysfunctionwithout affecting blood pressure in angiotensin II-high salt-induced hypertension

Objective: Inflammation has been proposed as a key component in the development of hypertension and cardiac remodeling associated with different cardiovascular diseases. However, the role of the proinflammatory cytokine interleukin-6 in the chronic stage of hypertension is not well defined. Here, we tested the hypothesis that deletion of interleukin-6 protects against the development of hypertension, cardiac inflammation, fibrosis, remodeling and dysfunction induced by high salt diet and angiotensin II (Ang II). Methods: Male C57BL/6J and interleukin-6-knock out (KO) mice were implanted with telemetry devices for blood pressure (BP) measurements, fed a 4% NaCl diet, and infused with either vehicle or Ang II (90 ng/min per mouse subcutaneously) for 8 weeks. We studied BP and cardiac function by echocardiography at baseline, 4 and 8 weeks. Results: Myocyte cross-sectional area (MCSA), macrophage infiltration, and myocardial fibrosis were also assessed. BP increased similarly in both strains when treated with Ang II and high salt (Ang II-high salt); however, C57BL/6J mice developed a more severe decrease in left ventricle ejection fraction, fibrosis, and macrophage infiltration compared with interleukin-6-KO mice. No differences between strains were observed in MCSA, capillary density and MCSA to capillary density ratio. Conclusion: In conclusion, absence of interleukin -6 did not alter the development of Ang II-high salt-induced hypertension and cardiac hypertrophy, but it prevented the development of cardiac dysfunction, myocardial inflammation, and fibrosis. This indicates that interleukin-6 plays an important role in hypertensive heart damage but not in the development of hypertension.Fil: González, Germán Esteban. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiopatología Cardiovascular; Argentina. Henry Ford Hospital; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rhaleb, Nour Eddine. Henry Ford Hospital; Estados UnidosFil: D'Ambrosio, Martin A.. Henry Ford Hospital; Estados UnidosFil: Nakagawa, Pablo. Henry Ford Hospital; Estados UnidosFil: Liu, Yunhe. Henry Ford Hospital; Estados UnidosFil: Leung, Pablo. Henry Ford Hospital; Estados UnidosFil: Dai, Xiangguo. Henry Ford Hospital; Estados UnidosFil: Yang, Xiao Ping. Henry Ford Hospital; Estados Unidos. Wayne State University; Estados UnidosFil: Peterson, Edward L.. Henry Ford Hospital; Estados UnidosFil: Carretero, Oscar A.. Henry Ford Hospital; Estados Unido