Probucol is a lipid-lowering drug that is often prescribed for the treatment of familial hypercholesterolemia. However, it is not known whether probucol can change the lesion quality of atherosclerosis.We examined this possibility using WHHL rabbits, a model of human familial hypercholesterolemia. Three-month-old male WHHL rabbits were treated with either probucol(85 mg/kg/day) or atorvastatin(6 mg/kg/day) for 16 weeks, and their plasma lipid levels and atherosclerotic lesions were compared with those of a control group.We found that probucol treatment reduced the plasma cholesterol levels, but less remarkably than atorvastatin treatment. In spite of this, probucol treatment led to a prominent reduction of aortic en face lesions by 39%(P＜0.01), whereas atorvastatin reduced these by 16%(P＞0.05), compared with those in the control. Histological examinations revealed that the aortic lesions of probucol-treated rabbits were characterized by reduced macrophages and increased smooth muscle cells compared with those from both the control and atorvastatin groups. Furthermore, probucol treatment reduced the coronary artery stenosis and increased the plaque stability.These results suggest that probucol treatment may have beneficial effects on the plaque stability of hypercholesterolemic patients.
This study focused on the unique properties of both the Ldlr knockout defect (closely mimicking the human situation) and the BALB/c (C) inbred mouse strain (Th-2 slanted immune response). We generated two immunodeficient strains with severe combined B- and T-cell immunodeficiency with or without a complete lack of natural killer cells to revisit the role of adaptive immune responses on atherogenesis. C-Ldlr-/- Rag1-/- mice, which show severe combined B- and T-cell immunodeficiency and C-Ldlr-/- Rag1-/- Il2rg-/- mice, which combine the T- and B-cell defect with a complete lack of natural killer cells and inactivation of multiple cytokine signalling pathways were fed an atherogenic Western type diet (WTD). Both B6-Ldlr-/- and C-Ldlr-/- immunocompetent mice were used as controls. Body weights and serum cholesterol levels of both immunodeficient strains were significantly increased compared to C-Ldlr-/- controls, except for cholesterol levels of C-Ldlr-/- Rag1-/- double mutants after 12 weeks on the WTD. Quantification of the aortic sinus plaque area revealed that both strains of immunodeficient mice developed significantly more atherosclerosis compared to C-Ldlr-/- controls after 24 weeks on the WTD. Increased atherosclerotic lesion development in C-Ldlr-/- Rag1-/- Il2rg-/- triple mutants was associated with significantly increased numbers of macrophages and significantly decreased numbers of smooth muscle cells compared to both C-Ldlr-/- wild type and C-Ldlr-/- Rag1-/- double mutants pointing to a plaque destabilizing effect of NK cell loss. Collectively, the present study reveals a previously unappreciated complexity with regard to the impact of lymphocytes on lipoprotein metabolism and the role of lymphocyte subsets in plaque composition.
Abstract Atherosclerosis is a serious public health concern. Excessive inflammatory responses of vascular cells are considered a pivotal pathogenesis mechanism underlying atherosclerosis development. It is known that Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signalling plays an important role in atherosclerosis progression. Protein inhibitor of activated STAT3 (PIAS3) is the key negative regulator of JAK/STAT3 signalling. However, its effect on atherogenesis is unknown. Here, we observed that PIAS3 levels are reduced in atherosclerotic lesions and that PIAS3 expression decreases in conjunction with increases in interleukin-6 expression and atherosclerosis severity. Oxidized low-density lipoprotein (ox-LDL), an atherogenic stimulus, reduced PIAS3 expression, an effect that may be attributed to nitric oxide synthesis upregulation. In turn, PIAS3 overexpression effectively suppressed ox-LDL-induced inflammation, lipid accumulation and vascular smooth muscle cell proliferation. These results indicate that PIAS3 is a critical repressor of atherosclerosis progression. The findings of this study have contributed to our understanding on the pathogenesis of atherosclerosis and have provided us with a potential target through which we can inhibit atherosclerosis-related cellular responses.
Abstract: Atherosclerosis is a chronic inflammatory process affecting mainly elastic and muscular arteries. Although small arteries and arterioles are usually spared, atherosclerosis can occur in these small vasculatures for a very short period. Here we report a case of atherosclerosis‐like lesions that occurred in a transplanted kidney showing acute accelerated rejection in a 43‐year‐old man. Histologically, biopsy specimens at 14 and 28 days and nephrectomy material at 52 days post‐transplantation showed atherosclerosis‐like lesions in various‐sized arteries. The lesions were characterized by the intimal infiltration of inflammatory cells, including foamy macrophages and a variable number of T‐lymphocytes, with smooth muscle cell proliferation. Immunohistochemistry disclosed that the foam cells expressing CD68 contained oxidized LDL. In addition, apolipoprotein(a) (Lp(a)), another major atherogenic lipoprotein, was found in the intimal smooth muscle layer, suggesting that Lp(a) induced smooth muscle cell proliferation in the rejected kidney as a mechanism of atherosclerosis. This case shows that immunoinflammatory reactions during a relatively short period can mimic the chronic atherosclerotic process even in small arteries and arterioles. Furthermore, the deposition of atherogenic lipoproteins, Lp(a) and oxidized LDL in lesions of rejected tissue present an analogy between vascular rejection in transplanted kidney and atherosclerosis.
Vascular endothelial growth factor (VEGF) is an important mediator in maintaining normal kidney functions. In addition, several lines of evidence suggest that upregulation of VEGF in glomeruli may be associated with or cause renal dysfunction such as diabetic nephropathy. For elucidation of the pathologic consequences of high levels of VEGF in glomeruli, transgenic (Tg) rabbits that express human VEGF(165) isoform in both kidney and liver under the control of the human alpha-1-antitrypsin promoter were generated and characterized. With the use of heterozygous Tg rabbits and their littermates aged 8 to 55 wk, renal functions and structures were investigated. Compared with control rabbits, Tg rabbits exhibited progressive proteinuria with increased GFR at the early stage and decreased GFR at the later stage. Histologic examinations revealed that Tg rabbit kidneys were characterized by considerable glomerular hypertrophy as a result of increased proliferation of both glomerular capillaries and mesangial cells accompanied by prominent podocyte hypertrophy. With increasing age starting from 20 wk, Tg rabbit kidneys showed prominent formation of microaneurysms and capillary proliferation at the vascular pole area. At a later stage (55 wk), many glomeruli showed sclerosis and tuft collapse with the formation of glomerular cysts on a background of tubular atrophy and interstitial fibrosis. This study provides the first evidence that increased expression of VEGF in glomeruli directly causes the glomerular hypertrophy that is associated with proteinuria, suggesting that VEGF exerts multiple effects on the glomerular pathophysiologic processes.
Short-term storage of embryos at low temperature induces developmental arrest of the embryo and would appear to be a valuable aid in embryo-transfer techniques to avoid wasting embryos. Embryo storage at 4°C was examined to allow synchronization with embryo-transfer recipients using the microinjection technique. Superovulation was induced in female Japanese White donor rabbits four days before mating with males. At the same time, control recipients were injected with human chorionic gonadotropin (hCG) to allow synchronization (R1); the hCG injections were delayed by 24 h in the experimental group (R2). DNA constructs for expressing human C-reactive protein or apolipoprotein AII were microinjected into the male pronuclei of the ova. The microinjected embryos were immediately transferred to recipients (R1) or stored at 4°C in phosphate-buffered saline containing 10% fetal bovine serum. After 17-20 h, the stored embryos were incubated at 37°C for one hour, and the morphologically normal embryos were transferred to recipients (R2). In the R1 rabbits, 855 embryos were transferred to 29 recipients, and 72.4% of the recipients became pregnant. Seven of the 84 offspring were transgenic. In the R2 rabbits, 478 embryos were transferred to 16 recipients, and 62.5% of the recipients became pregnant. Two of the 39 offspring were transgenic. There were no differences in pregnancy rate, litter size and transgenic integration rate between R1 and R2. These results suggest that the short-term 4°C storage of microinjected embryos can be a valuable method for synchronization with recipients, and reducing wastage of embryos and the sacrifice of rabbits.
Albumin (Alb) is the most abundant plasma protein with multiple biological functions, including antioxidative property through its thiol activity. Given that inflammatory bowel disease is associated with a decreased level of Alb and an increased level of Alb oxidation, we asked whether Alb could have a therapeutic effect on colitis. Here we tested this possibility. Bovine serum albumin (BSA) was reductively modified with dithiothreitol (DTT) and administrated via gavage or intraperitoneal injection. Dextran sulfate sodium (DSS)-induced mice colitis was associated with massive oxidative stress, as indicated by the elevated sulfenic acid formation in blood, colon tissues, and feces. Treatment of mice with the reductively modified albumin (r-Alb) attenuated the oxidative stress and reduced local inflammation and tissue injury. These effects of r-Alb were only partially achieved by unmodified Alb and wholly lost after blocking the –SH groups with maleimide. In cultured colon epithelial cells, r-Alb prevented DSS- and H2O2-induced ROS elevation and barrier dysfunction, preceded by inhibition of sulfenic acid formation and P38 activation. Further analysis revealed that Alb was susceptible to H2O2-induced oxidation, and it detoxified H2O2 in a –SH group-dependent way. Moreover, Alb reacted with GSH/GSSG via thiol-disulfide exchange and reciprocally regulated the availability of –SH groups. Collectively, our study shows that r-Alb effectively attenuates DSS colitis via –SH group-mediated antioxidative action. Given that the oxidative stress underlies many life-threatening diseases, r-Alb, functioning as a potent antioxidant, could have a wide range of applications.
The purpose of the present study was to characterize Himalayan marmot lipoprotein profiles and investigate their response to an atherogenic diet. Sixteen marmots were randomly divided into two groups. The control group was fed with a standard chow diet, and the other group was fed with a chow diet containing 0.3% cholesterol, 6.7% lard, and 3.3% corn oil (designated as HFCD) for 16 weeks. The plasma lipids were measured, and lipoprotein profiles were analyzed. With the chow diet, the major lipoproteins were high density lipoproteins. HFCD feeding increased not only plasma total cholesterol levels but also body weight compared with the control group (P<0.05). Plasma lipoprotein (a) was detected in marmots, and the plasma lipoprotein (a) levels were 4.5-fold higher after being fed HFCD for 16 weeks. However, atherosclerotic lesions were not found in the aorta of HFCD-fed marmots. This study suggested that marmots are HDL-rich mammals and resistant to HFCD-induced atherosclerosis.
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