Rosuvastatin increases myocardial microvessels in SHR rats. Role of thioredoxin-1 and peroxiredoxin-2 expression

CAO G, LLAMBÍ HG, MULLER A, OTTAVIANO G, MILEI J

INTERNATIONAL JOURNAL OF CARDIOLOGY

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 2014 p. 153 - 155

0167-5273

Beyond their lipid-lowering action, rosuvastatin possesses pleiotropic effects including anti-inflammatory, pro-angiogenic, antioxidant effects and protective actions against endothelial dysfunction [1,2]. The spontaneously hypertensive rats (SHR) has been extensively studied as a model of essential hypertension. Analogous to that seen in humans, prolonged periods of hypertension produces left ventricular (LV) remodeling, hypertrophy and oxidative stress. Thioredoxin (Trx) and peroxiredoxin (Prx) are a ubiquitous family of cysteine-dependent antioxidant proteins, presents in mammalian cells including heart. Several reports exist in the literature indicating that these proteins are induced by oxidative stress [3]. We investigated the possible effect of long-term monotherapy with rosuvastatin in myocardial expression of redoxins and vascular endothelial growth factor (VEGF), and their relations with LV remodeling in adult SHR. Eight-week-old male SHR and Wistar?Kyoto (WKY) rats, were divided into three groups: SHR (n=20), SHR-R (n=20; rosuvastatin10 mg/kg/day) and WKY (n=20). For 16 months, animals were housed in individual cages and were given free access to tap water and standard rat chow. At 18 months of age, all the rats were sacrificed and the heart excised and processing for quantitative microscopy and immunohistochemistry studies. Animal care was according to the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH publication n°85-53, revised 1998). At baseline and after every 2 weeks systolic blood pressure (SBP) was measured by tail-cuff plethysmography. For stereological analysis [4], thin sections from LV tissue blocks were stained with Masson trichrome, and the volume density (Vv; expressed in percentage) of myocardium (Vvmyo), interstitium (Vvint) and coronary capillaries (Vvccap) were evaluated. In addition, to estimate the individual myocyte mean cross-sectional area (MCSA; expressed in µm2) and the coronary capillaries density (CCD; expressed as capillaries profiles/mm2 of LV myocardium) an image processing software was used. Immunolabeling of specimens was carried out using a modified avidin-biotin peroxidase complex technique and expressed as a semiquantitative score [5]. In order to determine the Vv and density of coronary capillaries a polyclonal mouse anti-CD34 primary antibody was used. Myocardial intensity and percentage of VEGF, Trx1 and Prx2 staining were established using the respective primary polyclonal mouse antibody. Control sections were incubated with non-immune normal rabbit serum. Both the number and density of coronary capillaries were significantly increased in SHR-R compared to SHR group. Also, the immunohistochemical scoring for VEGF, Trx1 and Prx2 in response to rosuvastatin were significantly higher in myocardium as compared with SHR. However, no significant changes were seen between SHR-R and SHR in stereological parameters such as individual myocyte mean cross-sectional area, myocardial and interstitial volume densities. Persistently elevated SBP values without changes in LV mass (LV weight normalized to body weight) were observed in SHR-R compared to SHR. Moreover, SHR-R and SHR values were significantly higher in all stereological parameters, SBP and LV mass as compared with WKY. Also, other myocardial immunohistochemical differences were seen between SHR-R, SHR and WKY groups. Table 1 summarized the analyzed stereological and immunohistochemical parameters. Our investigation suggests that long-term monotherapy with 10 mg/kg/day of rosuvastatin increases the number and density of LV coronary capillaries and myocardial expression of VEGF in adult SHR, associated to higher immunolabeling for Trx1 and Prx2. Cells protect themselves against reactive oxygen species (ROS) through a combination of enzymes and low-molecular-mass antioxidants. In this connection, thioredoxin system appears to play a crucial role in the redox regulation of the ROS signaling, comprising NADPH, thioredoxin reductase (TrxR) and thioredoxin, covering the cytoplasmic Trx1 [6]. The formation of protein and peptide hydroperoxides is of biological significance not only because their generation results in modification of the structure and properties of the amino acid residue, but also because hydroperoxide groups are themselves powerful oxidants. A further group of proteins involved in removing H2O2 are the peroxiredoxins that include cytosolic Prx2 [7]. The inhibition of NADPH oxidase is a novel pleiotropic effect described for rosuvastatin [8] that hence could explain our results. This activity may increase NADPH availability to reduce oxidized Trx1 and Prx2, accelerating the cellular antioxidant system, enhanced molecular consumption and inducing redoxin new synthesis. Then, overexpression of Trx1 seems to stimulate VEGF and angiogenesis [9]. Although, long-term therapy with rosuvastatin does not improve LV remodeling nor SBP, our findings suggest antioxidant and angiogenic effects mediated by redoxin systems in adult SHR.