Research Papers: Gerotarget (Focus on Aging):
Combined effects of aging and inflammation on renin-angiotensin system mediate mitochondrial dysfunction and phenotypic changes in cardiomyopathies
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Tyesha N. Burks1, Ruth Marx1, Laura Powell1, Jasma Rucker2, Djahida Bedja2, Elisa Heacock1, Barbara J. Smith3, D. Brian Foster2, David Kass2, Brian O’Rourke2, Jeremy D. Walston1, Peter M. Abadir1
1Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine Baltimore, MD 21205, USA
2Division of Cardiology, Johns Hopkins University School of Medicine Baltimore, MD 21205, USA
3Cell Biology Imaging Facility, Johns Hopkins University School of Medicine Baltimore, MD 21205, USA
Peter M. Abadir, e-mail: [email protected]
Keywords: aging, mitochondria, AT1R, inflammation, heart
Received: April 4, 2015 Accepted: May 06, 2015 Published: May 18, 2015
Although the effects of aging and inflammation on the health of the cardiac muscle are well documented, the combined effects of aging and chronic inflammation on cardiac muscle are largely unknown. The renin-angiotensin system (RAS) has been linked independently to both aging and inflammation, but is understudied in the context of their collective effect. Thus, we investigated localized cardiac angiotensin II type I and type II receptors (AT1R, AT2R), downstream effectors, and phenotypic outcomes using mouse models of the combination of aging and inflammation and compared it to a model of aging and a model of inflammation. We show molecular distinction in the combined effect of aging and inflammation as compared to each independently. The combination maintained an increased AT1R:AT2R and expression of Nox2 and exhibited the lowest activity of antioxidants. Despite signaling pathway differences, the combined effect shared phenotypic similarities with aging including oxidative damage, fibrosis, and hypertrophy. These phenotypic similarities have dubbed inflammatory conditions as premature aging, but they are, in fact, molecularly distinct. Moreover, treatment with an AT1R blocker, losartan, selectively reversed the signaling changes and ameliorated adverse phenotypic effects in the combination of aging and inflammation as well as each independently.
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