Beneficial effects of C-peptide on renal morphology in diabetic rats

The study was undertaken to examine the effects of C-peptide on glomerular volume (V(GLOM)), mesangial matrix synthesis, and degradation in streptozotocin (STZ)-diabetic rats with poor or moderate glycemic control. Series 1 (poor glycemic control) included groups of healthy rats, hyperglycemic rats, diabetic insulin-treated rats and diabetic C-peptide-treated rats. Series 2 (moderate glycemic control) included groups of healthy rats, diabetic insulin-treated rats, diabetic insulin- and C-peptide-treated rats. After 8 weeks, the left kidney was excised for evaluation of V(GLOM) and mesangial matrix area via light microscopy. Mesangial cells were cultured for 48 h and type IV collagen expression and matrix metalloproteinase (MMP)-2 expression were measured by ELISA and RT-PCR. The results indicated that in Series 1, C-peptide administration suppressed the diabetes-induced increase in the V(GLOM) and the mesangial matrix area. In Series 2, C-peptide administration resulted in a similar decrease in the V(GLOM) and a greater decrease in the mesangial matrix area when compared with insulin therapy alone. Moreover, C-peptide (300 nM) completely inhibited the glucose-induced increase of the collagen IV mRNA expression and protein concentration in mesangial cells cultured in 30 mM glucose medium. MMP-2 mRNA expression was not influenced by C-peptide. In conclusion, C-peptide administration to STZ-diabetic rats for 8 weeks results in the inhibition of diabetes-induced expansion of the mesangial matrix. This effect is independent of the level of glycemic control and results from the inhibition of diabetes-induced excessive formation of mesangial type IV collagen.     

Effect of paricalcitol and enalapril on renal inflammation/oxidative stress in atherosclerosis

AIM: To investigate the protective effect of paricalcitol and enalapril on renal inflammation and oxidative stress in Apo E-knock out mice. METHODS: Animals treated for 4 mo as group(1) Apo E-knock out plus vehicle, group(2) Apo E-knock out plus paricalcitol(200 ng thrice a week),(3) Apo Eknock out plus enalapril(30 mg/L),(4) Apo E-knock out plus paricalcitol plus enalapril and(5) normal. Blood pressure(BP) was recorded using tail cuff method. The kidneys were isolated for biochemical assays using spectrophotometer and Western blot analyses. RESULTS: Apo E-deficient mice developed high BP(127 ± 3 mm Hg) and it was ameliorated by enalapril and enalapril plus paricalcitol treatments but not with paricalcitol alone. Renal malondialdehyde concentrations, p22 phox, manganese-superoxide dismutase, inducible nitric oxide synthase(NOS), monocyte chemoattractant protein-1, tumor necrosis factor-alpha and transforming growth factor-β1 levels significantly elevated but reduced glutathione, Cu Zn-SOD and e NOS levels significantly depleted in Apo E-knock out animals compared to normal. Administration of paricalcitol, enalapril and combined together ameliorated the renal inflammation and oxidative stress in Apo E-knock out animals. CONCLUSION: Paricalcitol and enalapril combo treatment ameliorates renal inflammation as well as oxidative stress in atherosclerotic animals.     

慢性炎症、自身免疫和动脉粥样硬化

动脉粥样硬化是一种炎症性疾病。在粥样斑块中存在许多免疫细胞,而且在不稳定斑块中尤为丰富。近年来对动脉粥样硬化中免疫细胞的聚集,分化和激活有了更深入的了解。流行病研究发现了多种与其相关的病毒和细菌感染。通过研究初步研究了几个自身性抗原,并提出了自身免疫假说。根据这些新的认识,提出了免疫调节和预防接种等心血管疾病的预防和治疗策略。这必将极大地提高对动脉粥样硬化的研究和防治水平。     

TGR5 activation inhibits atherosclerosis by reducing macrophage inflammation and lipid loading

The G protein-coupled receptor TGR5 has been identified as an important component of the bile acid signaling network, and its activation has been linked to enhanced energy expenditure and improved glycemic control. Here, we demonstrate that activation of TGR5 in macrophages by 6α-ethyl-23(S)-methylcholic acid (6-EMCA, INT-777), a semisynthetic BA, inhibits proinflammatory cytokine production, an effect mediated by TGR5-induced cAMP signaling and subsequent NF-κB inhibition. TGR5 activation attenuated atherosclerosis in Ldlr^−/−Tgr5^+/+ mice but not in Ldlr^−/−Tgr5^−/− double-knockout mice. The inhibition of lesion formation was associated with decreased intraplaque inflammation and less plaque macrophage content. Furthermore, Ldlr^−/− animals transplanted with Tgr5^−/− bone marrow did not show an inhibition of atherosclerosis by INT-777, further establishing an important role of leukocytes in INT-777-mediated inhibition of vascular lesion formation. Taken together, these data attribute a significant immune modulating function to TGR5 activation in the prevention of atherosclerosis, an important facet of the metabolic syndrome.     

Beneficial effects of enalapril on chlorhexidine digluconate-induced liver peritoneal fibrosis in rats

Peritoneal fibrosis (PF) is a recognized complication of long-term peritoneal dialysis (PD) and can lead to ultrafiltration failure. The present study was designed to investigate the protective effects of enalapril on chlorhexidine digluconate-induced liver PF by decreasing transforming growth factor-β1 (TGF-β1) production in rats. PF was induced in Sprague-Dawley rats by daily administration of 0.5 ml 0.1% chlorhexidine digluconate in normal saline via PD tube for one week. Rats received daily intravenous injections of low dose enalapril (1 mg/kg), or high dose enalapril (2.5 mg/kg), for one week. After 7 days, conventional 4.25% Dianeal (30 ml) was administered via a PD catheter with a dwell time of 4 h and assessment of peritoneal function. At the end of dialysis, the rats were sacrificed and liver peritoneum was harvested for microscopic examination and immunohistochemistry. There was no significant difference in mean arterial pressure and heart rate between groups. After 4 h of PD, the D?/P?(urea) level was reduced, the D?/D? glucose level, serum and the dialysate TGF-β1 level was increased, the liver peritoneum was markedly thicker, and the expression of TGF-β1, alpha-smooth muscle actin (α-SMA), fibronectin, collagen and vascular endothelial growth factor (VEGF) were elevated in the PF group compared with the vehicle group. High dose of enalapril decreased the serum and dialysate TGF-β1 levels, decreased the thickness of the liver peritoneum, and decreased the expression of TGF-β1, α-SMA, fibronectin, collagen and VEGF-positive cells in the liver peritoneum. Low dose of enalapril did not protect against chlorhexidine digluconate-induced PF in the rat. Enalapril protected against chlorhexidine digluconate-induced PF in rats by decreasing TGF-β1 production.     

Lipolysis of triglyceride-rich lipoproteins, vascular inflammation, and atherosclerosis

Epidemiological and interventional studies have implicated elevated triglyceride-rich lipoprotein (TGRL) levels as a risk factor for cardiovascular disease and vascular inflammation, though the results have not been entirely consistent. This appears particularly relevant in model systems where the lipolysis occurs in the setting of established inflammation (e.g., in pre-existing atherosclerotic plaques), rather than in the tissue capillary beds where lipolysis normally occurs. Two main mechanisms seem to link TGRL lipolysis to vascular inflammation. First, lipolysis of TGRL leaves behind partially lipolyzed remnant particles which are better able to enter the vessel wall than nascent TGRL, have a rate of egress substantially lower than their rate of entry, and contain 5-20 times more cholesterol per particle than LDL. Furthermore, remnants do not require oxidation or other modifications to be phagocytized by macrophages, enhancing foam cell formation. Second, saturated fatty acids and oxidized phospholipids released by lipolysis induce inflammation by activating Toll-like receptors of the innate immune system, via oxidative stress, or by greatly amplifying existing pro-inflammatory signals (caused by subclinical endotoxemia) via mitogen-activated protein kinases. However, n-3 and unbound n-9 unsaturated fatty acids released by lipolysis have anti-inflammatory effects. Thus, the contribution of TGRL lipolysis to inflammation likely depends less on the TGRL concentration than on the balance between pro- and anti-inflammatory factors, and on the setting in which the lipolysis occurs. In the setting of the typical "Western" diet, enriched in saturated and oxidized fatty acids and excessive in size, this balance is likely to be tilted towards increased vascular inflammation and atherosclerosis. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.     

Differential effects of dietary sodium intake on blood pressure and atherosclerosis in hypercholesterolemic mice

The amount of dietary sodium intake regulates the renin angiotensin system (RAS) and blood pressure, both of which play critical roles in atherosclerosis. However, there are conflicting findings regarding the effects of dietary sodium intake on atherosclerosis. This study applied a broad range of dietary sodium concentrations to determine the concomitant effects of dietary sodium intake on the RAS, blood pressure, and atherosclerosis in mice. Eight-week-old male low-density lipoprotein receptor ?/? mice were fed a saturated fat-enriched diet containing selected sodium concentrations (Na 0.01%, 0.1%, or 2% w/w) for 12 weeks. Mice in these three groups were all hypercholesterolemic, although mice fed Na 0.01% and Na 0.1% had higher plasma cholesterol concentrations than mice fed Na 2%. Mice fed Na 0.01% had greater abundances of renal renin mRNA than those fed Na 0.1% and 2%. Plasma renin concentrations were higher in mice fed Na 0.01% (14.2±1.7 ng/ml/30 min) than those fed Na 0.1% or 2% (6.2±0.6 and 5.8±1.6 ng/ml per 30 min, respectively). However, systolic blood pressure at 12 weeks was higher in mice fed Na 2% (138±3 mm Hg) than those fed Na 0.01% and 0.1% (129±3 and 128±4 mmHg, respectively). In contrast, mice fed Na 0.01% (0.17±0.02 mm²) had larger atherosclerotic lesion areas in aortic roots than those fed Na 2% (0.09±0.01 mm²), whereas lesion areas in mice fed Na 0.1% (0.12±0.02 mm²) were intermediate between and not significantly different from those in Na 0.01% and Na 2% groups. In conclusion, while high dietary sodium intake led to higher systolic blood pressure, low dietary sodium intake augmented atherosclerosis in hypercholesterolemic mice.     

Beneficial effects of combined treatment with niacin and chromium on the liver of hyperlipemic rats

Many studies have shown that niacin and Cr exert combined effects. Significant beneficial effects in serum lipid levels following Cr supplementation have been reported. Niacin decreases total plasma levels of cholesterol, triglycerides, and low-density lipoprotein cholesterol and increases high-density lipoprotein cholesterol. In this study, 12-mo-old female Swiss albino rats were used. They were randomly divided into four groups. The animals of group I (control) were fed with pellet chow. Group II was fed with pellet chow and treated with 250 μg/kg CrCl₃·6H₂O and 100 mg/kg niacin for 45 d, by the gavage technique. The rats of group III were fed with lipogenic diet consisting of 2% cholesterol 0.5% cholic acid, and 20% sunflower oil added to the pellet chow and given 3% alcoholic water for 60 d. Group IV was fed with the same lipogenic diet, and 15 d after, the experimental animals were made hyperlipemic; they were treated with 250 μg/kg CrCl₃·6H₂O and 100 mg/kg niacin by gavage technique for 45d. On d 60, liver and blood samples were taken from the animals. The sections were examined under light and electron microscopes. Serum total lipid and cholesterol levels were determined by spectrophotometric methods. The aim of the present study was *** DIRECT SUPPORT *** A02Q2015 00004     

Adipose triglyceride lipase in immune response, inflammation, and atherosclerosis

Abstract Consistent with its central importance in lipid and energy homeostasis, lipolysis occurs in essentially all tissues and cell types, including macrophages. The hydrolytic cleavage of triacylglycerol by adipose triglyceride lipase (ATGL) generates non-esterified fatty acids, which are subsequently used as essential precursors for lipid and membrane synthesis, mediators in cell signaling processes or as energy substrate in mitochondria. This review summarizes the current knowledge concerning the consequences of ATGL deficiency in macrophages with particular emphasis on macrophage (dys)-function, apoptosis, and atherosclerosis.     

Beneficial effects of pituitary grafts under the renal capsule on behavior of dwarf mutant mice

The effects of pituitary grafts under the kidney capsule were studied in "dwarf" mutant mice which because of anterohypophyseal deficiency, exhibit dwarfism, sterility and important behavioral deficits. One month after grafting, the body weight was 120% in the grafted mutants while only 11 and 8% respectively in normal and sham-grafted controls. At the behavioral level, the animals were examined on 2 tasks: spontaneous alteration in a T maze and passive avoidance (step-through). Grafted mutant mice, as well as sham-grafted normal controls, were able to alternate successfully, while the sham-grafted "dwarf" mice persevered. In the step-through task, grafted animals as well as sham-grafted normal mice, avoided, entering the dark compartment, 24 h after the shock trial. On contrast, sham-grafted dwarf mice did not show passive avoidance of the shock. According to the literature, pituitary grafts under the kidney capsule secrete high levels of prolactin and very little, if any, of other pituitary hormones. It is not yet clear how the presence of only prolactin can explain the body weight and the maintenance of the behaviors we investigated.     

The effects of endothelial lipase gene (LIPG) variants on inflammation marker levels and atherosclerosis development

Atherosclerosis is a major pathological process related with several important adverse vascular events including coronary artery disease, stroke, and peripheral arterial disease. Endothelial lipase is an enzyme the activity of which affects all of lipoproteins, whereas HDL is the main substrate. The purpose of our study was to investigate the effects of endothelial lipase gene polymorphism and inflammation markers (CRP, IL-1β, IL-6, IL-8 and TNF-α) in the atherosclerosis. 104 patients with atherosclerosis and 76 healthy individuals were included in the study. LIPG ?584C/T polymorphism gene polymorphisms were assessed with PCR–RFLP method. The serum CRP levels were measured by turbidimetric method using a biochemistry autoanalyzer, whereas serum IL-1β, IL-6, IL-8, TNF-α levels were determined by enzyme-linked immunosorbent assay. In this study, we found that the frequencies of TC genotype are more prevalent in patients than controls. We found a statistically significant difference of IL-6 levels between patient and control group. Our findings suggest that T allele might play a potential role in the susceptibility to atherogenesis in the Turkish population.     

Beneficial effect of quercetin on cholestatic liver injury

Bile duct obstruction and subsequent cholestasis are associated with hepatocellular injury, cholangiocyte proliferation, stellate cell activation, Kupffer cell activation, oxidative stress, inflammation and fibrosis. Flavonoids have been shown to confer beneficial health effects, including hepatoprotection. However, the molecular mechanism of flavonoid-mediated hepatoprotection is incompletely understood. In this study, we report the protective effect of quercetin on cholestatic liver injury. Cholestasis was produced by bile duct ligation (BDL) in male Sprague–Dawley rats for 3 weeks. Daily oral administration of quercetin was started 1 week before injury and lasted for 4 weeks. In comparison with the control group, the BDL group showed liver injury, as evidenced by histological changes, and elevation in serum biochemicals, ductular reaction, fibrosis, inflammation and oxidative stress. These pathophysiological changes were attenuated by daily quercetin supplementation. Quercetin alleviated BDL-induced transforming growth factor beta-1 (TGF-β1), interleukin-1 beta, connective tissue growth factor and collagen expression. The antifibrotic effect of quercetin was accompanied by reductions in α-smooth muscle actin-positive matrix-producing cells and Smad 2/3 activity critical to the fibrogenic potential of TGF-β1. Quercetin also attenuated BDL-induced oxidative stress, leukocyte accumulation, nuclear factor (NF)-κB activation and proinflammatory cytokine production. Further studies demonstrated an inhibitory effect of quercetin on MyD88 and TGF-β-activated kinase-1 critical for linking toll-like receptor (TLR) and NF-κB. Taken together, the hepatoprotective, anti-inflammatory and antifibrotic effects of quercetin seem to be multifactorial. The beneficial effects of daily quercetin supplementation are associated with antioxidative and anti-inflammatory potential as well as down-regulation of NF-κB and TGF-β/Smad signaling, probably via interference with TLR signaling.