Human Paraoxonase Gene Cluster Transgenic Overexpression Represses Atherogenesis and Promotes Atherosclerotic Plaque Stability in ApoE-Null Mice

Abstract

Abstract-The paraoxonase (PON) gene cluster consists of the PON1, PON2, and PON3 genes, each of which canindividually inhibit atherogenesis. To analyze the functions of the PON gene cluster (PC) in atherogenesis and plaque stability, human PC transgenic (Tg) mice were generated using bacterial artificial chromosome. The high-density lipoprotein from Tg mice exhibited increased paraoxonase activity. When crossed to the ApoE-null background and challenged by high-fat diet, PC Tg/ApoE-null mice formed significantly fewer atherosclerotic lesions. However overexpression of the PC transgene had no additive effect on atherosclerosis compared to the overexpression of the single PON1 or PON3 transgene. Plaques from PC Tg/ApoE-null mice exhibited increased levels of collagen and smooth muscle cells, and reduced levels of macrophages and lipid, compared with those from ApoE-null mice, indicating lesions of PC Tg/ApoE-null mice had characteristics of more stable plaques than those of ApoE-null mice. PC transgene enhanced high-density lipoprotein ability to protect low-density lipoprotein against oxidation in vitro. Serum intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 were also repressed by PC transgene. Proatherogenic reactions of Tg mouse peritoneal macrophages induced by oxidized low-density lipoprotein were inhibited by PC transgene, as indicated by reduced reactive oxygen species generation, inflammation, matrix metalloproteinase-9 expression, and foam cell formation. Our results demonstrate that the PC transgene not only represses atherogenesis but also promotes atherosclerotic plaque stability in vivo. PC may therefore be a useful target for atherosclerosis treatment. Key Words: atherosclerosis Ⅲ plaques stability Ⅲ macrophages Ⅲ paraoxonase cluster A therosclerosis constitutes the single most important contributor to cardiovascular diseases, which are the leading cause of death and illness in developed societies. 1,2 Atherosclerosis-related ischemic symptoms, especially acute cardiovascular events that result in myocardial infarction and stroke, are generally thought to result from plaque rupture and thrombosis other than narrowing of the vessel lumen. 3 New strategies for preventing and treating plaque rupture are very much needed based on understanding of factors that contributed. Oxidized low-density lipoprotein (oxLDL) plays a pivotal role in triggering proinflammatory events that initiate and exacerbate atherogenesis, 1,4 which induces the expression of adhesion molecules, chemokines, and cytokines in vascular endothelial cells, 5 triggering recruitment of monocytes into the subendothelial space of the arterial wall, where they differentiate into macrophages. Recruited macrophages ingest and further oxidize LDL, transforming into foam cell after excessive oxLDL accumulation. These transformed macrophages not only constitute early fatty streak lesions and the core of atherosclerotic plaques but also become active inflammation centers because of secretion of inflammatory molecules and ma...

Human paraoxonase gene cluster overexpression alleviates angiotensin II-induced cardiac hypertrophy in mice

“…In mice, PON1 is expressed mainly in the liver, but it can redistribute to a variety of tissues and organs including hearts by associating with HDL and secreting into the serum upon expression in the liver (Deakin et al, 2011;Marsillach et al, 2008). Indeed, we found that PON1 mRNA was absent in the heart but that its level in the liver was high, as previously reported (She et al, 2009). However, PON1 protein was detectable in the WT control hearts and increased significantly in the Ang II-induced hypertrophic hearts.…”

“…Mouse genotyping was performed by PCR and agarose gel electrophoresis ( Figure 2B). The tissue-specific expression of the human PON1 (hPON1), hPON2, and hPON3 transgenes was confirmed (She et al, 2009), and we found that the mRNA of each of hPON1-3 was detected in the PC-Tg mouse hearts ( Figure 2C-E). We did not observe any difference in the heart weight (HW)/body weight (BW) ratios ( Figure 2F), cardiac morphology (left ventricular internal diameter at end-diastole, (LVID; d)) ( Figure 2G), or cardiac function, including fractional shortening (FS) and ejection fraction (EF) (Figure 2H and I), between the PC-Tg mice and their non-transgenic littermates.…”

“…Despite the differences in substrates, all of the PON1/2/3-null mice developed significantly larger atherosclerotic lesions than their WT counterparts when fed a high-fat, high-cholesterol diet (Devarajan et al, 2011;Ng et al, 2006;Shih et al, 1998Shih et al, , 2015. In a previous study, we found that the PC transgene suppressed atherosclerosis development and promoted atherosclerotic plaque stability in an Apoe / background (She et al, 2009). Here, we first showed that PONs, which are protective factors for atherosclerosis, are protective against the progression of cardiac hypertrophy induced by Ang II in mice.…”

“…To further define the role of PC in cardiac hypertrophy, we used transgenic mice carrying the intact human PON1, PON2, and PON3 genes and their flanking sequences (Figure 2A), which were established in our lab (She et al, 2009). Mouse genotyping was performed by PCR and agarose gel electrophoresis ( Figure 2B).…”

“…Unlike PON2 and PON3, which are expressed ubiquitously in mouse (She et al, 2009), PON1 is expressed primarily in the liver and redistributes to a variety of tissues and organs, including the heart, through circulating high-density lipoprotein (HDL) (Deakin et al, 2011;Marsillach et al, 2008). It has been demonstrated that PC protects against atherosclerosis (She et al, 2009), reduces the incidence of cardiovascular diseases (CVD), and is related to diabetes, metabolic syndrome, and aging via anti-oxidative stress. However, to our knowledge, the role of PC in cardiac hypertrophy has not been reported, and little is known about the reactivity of the PON gene cluster to hypertrophic stimulation.…”