Stephanie Madec

Retinol-binding protein-4 in women with untreated essential hypertension

BACKGROUND Retinol-binding protein-4 (RBP4) is a novel adipokine able to modulate the action of insulin in several tissues. A variable degree of insulin resistance characterizes the vast majority of hypertensive (HYP) patients. The aim of this study was to evaluate the relationship between RBP4 and essential hypertension, exploring potential links between RBP4 and other adipokines with some proxies of early vascular damage in female naive HYP patients. METHODS Serum RBP4, leptin, adiponectin, and resistin levels were determined in 35 HYP and 35 normotensive lean women with normal glucose tolerance paired by age and body mass index (BMI) served as controls (CTL); carotid intima-media thickness (IMT) was also measured. RESULTS A striking difference was observed in RBP4 levels between HYP and CTL with significantly higher levels in the former than in the latter. No relationship was observed between glomerular filtration rate (GFR) and RBP4. Adiponectin levels were slightly but significantly lower in HYP than in CTL, whereas no differences were observed in resistin and leptin concentrations between the two groups of women. In the whole study group, a strong linear relationship was observed between IMT value and both RBP4 (rho = 0.321, P = 0.0076) and resistin (rho = 0.340, P = 0.0048); these two adipocytokines, together with cholesterol, were the only variables independently related to IMT (r(2) = 0.24; P = 0.004) by a stepwise analysis. CONCLUSIONS RBP4 levels are increased in naive HYP women and correlated with the degree of IMT suggesting a participation of this adipocytokine in the modulation of the atherosclerotic process exerted by the adipose tissue as endocrine organ.

Pattern of expression of adiponectin receptors in human adipose tissue depots and its relation to the metabolic state

Objective:To investigate whether adiponectin receptor genes (AdipoR1 and AdipoR2) expression in human subcutaneous (SAT) and visceral (VAT) adipose tissue in severely obese patients with or without diabetes is related to adiponectin gene (APM1) expression and in vivo metabolic parameters.Design:Cross-sectional, clinical research study.Subjects:Total RNA was extracted from SAT and VAT tissue obtained during surgery from 13 lean controls, 30 obese diabetic patients, 19 obese glucose-intolerant patients and 54 obese subjects with normal glucose tolerance.Measurements:Tissue expression of APM1, AdipoR1 and AdipoR2, tissue concentration of adiponectin (ApN), and metabolic variables.Results:APM1 expression was higher in SAT than VAT (1.06±0.76 vs 0.69±0.52, P<0.0001) as was AdipoR1 (1.17±0.70 vs 0.66±0.38, P<0.0001) and AdipoR2 (7.02±6.19 vs 0.75±0.64, P<0.0001). In SAT, APM1 and AdipoR1 expression tended to be lower – by 0.38±0.22 and 0.35±0.22, respectively – and AdipoR2 expression was markedly depressed – by 4.82±1.93 – in association with obesity, whereas presence of diabetes had no additional effect. In VAT, APM1 and AdipoR1 expressions were also reduced – by 0.36±0.16 and 0.30±0.11, respectively – in association with obesity. Within both SAT and VAT, expression levels of APM1, AdipoR1 and AdipoR2 were all positively interrelated. Tissue ApN concentrations in SAT were similar across groups, whereas ApN levels in VAT were substantially lower in association with obesity (by an average of 63±12 ng/mg total protein, P<0.0001). In multivariate models adjusting for sex, age and obesity, serum triglyceride concentrations were reciprocally related to APM1 (r=−0.27, P<0.02), AdipoR1 (r=−0.37, P<0.002 and AdipoR2 expression (r=−0.37, P<0.002) in VAT. Likewise, plasma insulin concentrations were inversely related only to APM1 in VAT (r=−0.25, P<0.03).Conclusions:Severe obesity is associated with suppressed expression of both ApN and its receptors in both SAT and VAT, the expression levels in VAT are specifically linked with hyperinsulinemia and dyslipidemia.

Effects of different LDL particles on inflammatory molecules in human mesangial cells.

Aims/hypothesisInflammation is a mechanism of glomerular damage in chronic glomerulopathies. LDL may increase the production of inflammatory cytokines in renal tissues. However, the relative role of native, oxidised and glycated LDL in promoting this process has been only partially elucidated.MethodsWe tested the inflammatory and proapoptotic effects of native, oxidised and glycated LDL in human mesangial cells (HMCs) by measuring levels of IL6, CD40 and macrophage migration inhibitory factor (MIF) genes, MIF protein, release of IL6, soluble CD40, fibronectin and laminin, early and late apoptosis, and extracellular regulated kinases (ERK) 1/2 and c-Jun N-terminal kinase (JNK) activation.ResultsIL6 and CD40 mRNA were dose-dependently upregulated by all three species; this was closely paralleled by their increased release. MIF mRNA was potently stimulated by modified LDL, as confirmed by immunostaining. Fibronectin and laminin release was stimulated by both oxidised and glycated, but not native, LDL. All LDL species induced some increase in late, but not early, apoptosis, and similarly activated JNK2/3 phosphorylation; in contrast, ERK1/2 phosphorylation was more strongly upregulated by oxidised than either native or glycated LDL.ConclusionsIn HMCs, the production and release of IL6 and CD40 is stimulated by both native and modified LDL, while MIF is more strongly stimulated by oxidised LDL. Regarding the pattern of mesangial expansion, fibronectin and laminin are upregulated by oxidised and glycated LDL. Apoptosis, if modest, is induced by all species. Intracellular signalling of native and modified LDL involves JNK2/3 and, perhaps more specifically, ERK1/2. Tight control of the lipid profile may be useful in preserving kidney function in patients with metabolic alterations.

The complex P2X7 receptor/inflammasome in perivascular fat tissue of heavy smokers

Smoking is a recognized cardiovascular risk factor. Perivascular visceral adipose tissue (PVAT) is a source of inflammatory molecules, thus contributing to atherosclerosis progression. The P2X7 receptor (P2X7R)‐inflammasome complex, crucial in determining IL‐1β and IL‐18 release, participates in this scenario. We evaluated whether smoking might affect the PVAT inflammatory phenotype and explored the putative role of the axis P2X7R‐inflammasome in this picture.

Effects of endothelin-1 on fibroblasts from type 2 diabetic patients: Possible role in wound healing and tissue repair

Endothelin-1 (ET-1) promotes the contractile ability of fibroblasts, essential for wound closure and reconstitution of the dermis. Wound healing is impaired in type 2 diabetic patients (D). We compared the effect of ET-1 on proliferative transforming growth factor (TGFβ1) expression, fibronectin and laminin release), differentiative [α-smooth muscle actin (α-SMA) expression] and inflammatory [monocyte chemo-attractant protein (MCP-1) and interleukin-6 (IL-6) expression] responses in skin fibroblasts of healthy subjects (C) and D, testing the relative role of ETA and ETB receptors in mediating these responses. ET-1 did not influence TGFβ1, fibronectin or laminin production. α-SMA was more abundant and more stimulated in D, as well as MCP-1 and IL-6 expression and release. These effects were prevented by BMS-182874, selective antagonist of ETA, more abundant than ETB in both cell strains and whose expression rose more in D than C upon stimulation with ET-1. This peculiar pattern of responses to ET-1, presumably acquired during the chronic in vivo exposure to hyperglycemia along the natural history of the disease, may partially explain the increased susceptibility of D to chronic ulcerations.

Effect of statins on soluble CD40 ligand in hypercholesterolemic Type 2 diabetic patients

Hypercholesterolemia and Type 2 diabetes are well-recognized risk factors for cardiovascular disease, promoted by a condition of subclinical inflammation and a hypercoagulable state. Soluble CD40 ligand (sCD40L), a marker of vascular inflammation, seems to predict vascular damage in patients with Type 2 diabetes. Beside the lipid-low-ering effect, statins seem to slow the progression of atherosclerosis through a series of anti-inflammatory effects, including a reduction of sCD40L levels. This study compared the effect of a short-term (12 weeks) treatment with rosuvastatin or simvastatin on some markers of inflammation in 36 patients with Type 2 diabetes and moderate hypercholesterolemia. As expected, both drugs significantly modified lipid profile; moreover, rosuvastatin and simvastatin were both able to significantly reduce albumin excretion rate in these patients, without affecting urinary N-acetyl-beta-D-glucosaminidase. Serum homocysteine was not influenced by the treatment, as interleukin-6 levels, while C reactive protein diminished; moreover, rosuvastatin, but not simvastatin, was able to significantly reduce sCD40L. The only clinical parameter related with the variations in sCD40L was systolic blood pressure. In hypercholesterolemic Type 2 diabetic patients, sCD40L, a factor playing a pivotal role in the pathogenesis of atherosclerosis and associated with more rupture-prone lesions, is reduced by short-term treatment with rosuvastatin.

Angiotensin-II and rosuvastatin influence matrix remodeling in human mesangial cells via metalloproteinase modulation.

Objective Persistent inflammation and oxidative stress influence the progression of diabetic nephropathy. Metalloproteinases (MMPs) participate in extracellular matrix remodeling. Statins show favorable anti-inflammatory effects in chronic kidney disease. We evaluated the effect of rosuvastatin on inflammatory and pro-fibrotic responses due to exposure to different glucose or free fatty acid (FFA) concentrations. Methods Human mesangial cells (HMCs) grown at 5.5 (normal glucose) or 22 mmol/l (high glucose) glucose or exposed to FFA were treated with angiotensin-II in the presence or absence of rosuvastatin. We measured MMP-2, MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and TIMP-2 expression and activity, and quantified the fibrotic factors transforming growth factor-&bgr;1 (TGF-&bgr;1), fibronectin, and collagen IV. Results At normal glucose, angiotensin-II induced a dose-dependent downregulation of MMP-2; rosuvastatin reversed this effect. On the contrary, TIMP-2 and MMP-9 were upregulated by angiotensin-II and downregulated by rosuvastatin; the effects on TIMP-1 were negligible. Some of the angiotensin-II effects were potentiated in the presence of high glucose and FFA; under both conditions, rosuvastatin was able to reverse these effects. MMP-2 and MMP-9 activity followed the same trend of expression, with rosuvastatin able to upregulate MMP-2 activity. The modulation of the MMP/TIMP system was paralleled by an increase in TGF-&bgr;1, fibronectin, and collagen-IV; all were reduced by rosuvastatin treatment. Silencing the MMP-2 gene confirmed its role in modulating some of these angiotensin-II effects. Conclusion Angiotensin-II induces a pro-fibrotic response in HMCs mainly via a dysregulation of the MMP-2/TIMP-2 pattern. This effect, partially amplified in the presence of high glucose and FFA, is reversed by rosuvastatin, suggesting another potential therapeutic application for this 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor.

Pattern of expression of inflammatory markers in adipose tissue of untreated hypertensive patients

Objective Adiposity contributes to the insulin resistance and endothelial dysfunction of the hypertensive state; the inflammatory network and the metalloprotease (MMP)/tissue inhibitor of metalloprotease (TIMP) system modulate vascular structure and function. Methods We measured interleukin-6 (IL-6); plasminogen activator inhibitor-1 (PAI-1); tumor necrosis factor-alpha; transforming growth factor-beta; MMP-2, MMP-9, TIMP-1, and TIMP-2 expression; MMP-2 and MMP-9 activity; and TIMP-1 and TIMP-2 protein in adipocytes isolated from paired samples of visceral and subcutaneous adipose tissue of 30 nonobese, untreated hypertensive patients and 20 normotensive controls. Results Although expression of IL-6, PAI-1, tumor necrosis factor-alpha, and transforming growth factor-beta were generally higher in visceral adipocytes, IL-6, PAI-1, and tumor necrosis factor-alpha were overexpressed, and transforming growth factor-beta was underexpressed in hypertensive vs. controls (all P < 0.0001). These changes were paralleled by higher circulating IL-6 and PAI-1 levels in hypertensive patients. MMP-2 and TIMP-2 expression – which were higher in subcutaneous than visceral cells – were reduced in hypertensive patients (all P < 0.0001), whereas MMP-9 and TIMP-1 did not differ between the two groups. Both MMP-2 and MMP-9 activity were reduced in hypertensive patients (all P < 0.0001). In the whole dataset, SBP and DBP were directly related to IL-6 and PAI-1 expression and inversely to MMP-2 and MMP-9 activity. Conclusion Adipocytes from both visceral and subcutaneous depots of untreated hypertensive patients show a pattern of expression of inflammatory and MMP/TIMP molecules that is compatible with the raised circulating levels of inflammatory markers, is quantitatively related to the height of blood pressure, and provides the cellular basis for the proinflammatory and prothrombotic predisposition of these patients.

Rosiglitazone increases matrix production and quenches inflammation: studies in human cells

Type 2 diabetes (T2D) is characterized by an accelerated atherogenesis, a process to which both proliferative and inflammatory responses contribute. Peroxisome proliferator‐activated receptors‐gamma (PPARγ) agonists have both anti‐proliferative and anti‐inflammatory properties. We tested the effect of therapeutic doses of rosiglitazone on proliferative and inflammatory pathways in fibroblasts (HF) from five controls (C) and five T2D patients, and in aortic smooth muscle cells (hSMC).