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Role of Cardiovascular Disease-associated iron overload in Libby amphibole-induced acute pulmonary injury and inflammation
Shannahan, J., M. SCHLADWEILER, D. Padilla-Carlin, A. Nyska, J. E. RICHARDS, A. J. GHIO, S. H. GAVETT, AND U. P. KODAVANTI. Role of Cardiovascular Disease-associated iron overload in Libby amphibole-induced acute pulmonary injury and inflammation. INHALATION TOXICOLOGY. Informa Healthcare USA, New York, NY, 23(3):129-41, (2011).
This manuscript shows that underlying cardiovascular disease can prolong pulmonary injury caused by acute exposure to Libby Amphibole -asbestos-like fibers. This injury differences may involve the role of underlying iron homeostasis, oxidative stress and the ability to mount inflammatory response. The study uses three rat models: one healthy and two cardiovascular compromised models including h ertension and heart failure
Pulmonary toxicity induced by asbestos is thought to be mediated through redox-cycling of fiber-bound and bioavailable iron (Fe). We hypothesized that Libby amphibole (LA)-induced cute lung injury will be exacerbated in rat models of cardiovascular disease (CVD)-associated Fe-overload and oxidative stress. Healthy male Wistar Kyoto (WKY), spontaneously hypertensive (SH) and SH heart failure (SHHF) rats were intratracheally instilled with 0.0, 0.25 or 1.0 mg/rat LA and examined at 1 day, 1 week or 1 month. Although histologically it was not possible to distinguish severity differences between strains in LA-induced initial inflammation and later fibrosis, quantitative assessment of biomarkers showed strain-related differences. LA-induced neutrophilic inflammation was reversible in WKY but persisted more in SH and SHHF. Lung MIP-2 mRNA increased only in WKY at 1 day in response to LA but not in SH and SHHF. Bronchoalveolar lavage fluid (BALF) protein increased in SH but not WKY at 1 week and 1 month, while γ-glutamyltransferase and N-acetyl-β-D-glucosaminidase activities increased in all strains (WKY>SH=SHHF). BALF ferritin levels were high at baseline and increased following LA exposure only in SH and SHHF. Ferritin heavy chain mRNA increased only in SHHF at 1 day. At 1 month ferritin light chain mRNA declined from already high baseline levels in SHHF but increased in WKY and SH suggesting its differential involvement in LA-induced injury in Fe-overload. Unlike WKY, both SHHF and SH failed to increase the lung lining antioxidant, ascorbate, in response to LA. We conclude that underlying CVD-associated Fe-overload is likely linked to persistent lung injury, inflammation and antioxidant decompensation following LA exposure in rats.